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Patent Searching and Data


Title:
INTERNAL COMBUSTION ENGINE
Document Type and Number:
WIPO Patent Application WO/2018/081854
Kind Code:
A1
Abstract:
A system (1, 401) and method (100, 200, 300, 400) to initiate combustion based on energy of combustion gasses from a previous cycle in an internal combustion engine (3, 403). In some examples, this includes storing some of the energised combustion gasses (9) in a reservoir (7), whereby the combustion gasses (9) are selectively reintroduced into the combustion chamber (5) to cause combustion. In other examples, the energised combustion gasses (9) can energise a mechanism, which in turn, is selectively activated so that energy is released to the combustion chamber (5) to cause combustion. The mechanism may include an auxiliary piston (60) and a biasing mechanism (62) to store energy, wherein the auxiliary piston (60) is selectively released by a retaining mechanism (64, 464).

Inventors:
PARLE, Anthony (C/- 7 Maegraith Place, Griffith, New South Wales 2680, 2680, AU)
Application Number:
AU2017/051197
Publication Date:
May 11, 2018
Filing Date:
October 31, 2017
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
AUSTRALIAN FROZEN FOODS PTY LTD (7 Maegraith Place, Griffith, New South Wales 2680, 2680, AU)
International Classes:
F02B1/12; F02B75/04; F02D15/04; F02D41/00; F02M26/00
Foreign References:
US20070084428A12007-04-19
US6276334B12001-08-21
US20030192490A12003-10-16
US6427643B12002-08-06
US6065456A2000-05-23
US20090241896A12009-10-01
US20060005818A12006-01-12
US20070193545A12007-08-23
US4020808A1977-05-03
US7516731B22009-04-14
Attorney, Agent or Firm:
FB RICE PTY LTD (Level 23, 44 Market StSydney, New South Wales 2000, 2000, AU)
Download PDF:
Claims:
CLAIMS:

1. An ignition system (1) for an internal combustion engine (3) including a combustion chamber (5) comprising:

- a reservoir (7) to store high pressure and high temperature combustion gasses

(9);

- a combustion gas valve (11) selectively operable to provide fluid communication between the reservoir (7) and the combustion chamber (5), wherein the combustion gas valve (11) is operable to open to inject high pressure and high temperature combustion gasses (9) from the reservoir (7) into the combustion chamber (5) that contains a compressed fuel air mixture (13), wherein the injected high pressure and high temperature combustion gasses (9) are above an autoignition

temperature and increases pressure to cause combustion of the compressed fuel air mixture (13); wherein during, or after, combustion of the compressed fuel air mixture (13), the combustion gas valve (11) is operable to be open for the reservoir (7) to receive high pressure and high temperature combustion gasses (9) from the combustion chamber (5); and wherein after combustion, the combustion gas valve (11) is operable to be closed for the reservoir (7) to store the high pressure and high temperature combustion gasses (9) during: exhaust of combustion gasses from the combustion chamber (5); intake of fuel air mixture into the combustion chamber (5); and compression of fuel air mixture in the combustion chamber (5).

2. An ignition system (1) according to claim 1 wherein the ignition system (1) is for a reciprocating internal combustion engine (3) that includes a reciprocating piston (15) in a cylinder (17) that drives a crankshaft (18), wherein when the reciprocating piston (15) is at or near top dead centre in the cylinder to provide the combustion chamber (5) containing the compressed fuel air mixture (13), the combustion gas valve (11) is operable to open to inject high pressure and high temperature combustion gasses (9) into the combustion chamber (5).

3. An ignition system (1) according to claim 2 wherein the reciprocating internal combustion engine (3) has a four-stroke cycle for each piston (15), including:

- a power stroke whereby the piston (15) moves from the top dead centre to a bottom dead centre in the cylinder (17) due to expansion of high pressure and high temperature combustion gasses (9) in the combustion chamber (5);

- an exhaust stroke whereby the piston (15) moves from the bottom dead centre to the top dead centre in the cylinder (17) to remove combustion gasses from the cylinder (17);

- an intake stroke whereby the piston (15) moves from the top dead centre to the bottom dead centre where the fuel air mixture is introduced into the cylinder (17); and

- a compression stroke whereby the piston (15) moves from the bottom dead centre to the top dead centre to compress the fuel air mixture in the cylinder (17), wherein the combustion gas valve (11) is selectively operable from close to open when the piston (15) is at, or near, top dead centre between the compression stroke and the power stroke of the four- stroke cycle; and wherein the combustion gas valve (11) is selectively operable from open to close during the power stroke and before the piston (15) is at bottom dead centre.

4. An ignition system (1) according to claim 2 wherein the reciprocating internal combustion engine (3) has a two stroke cycle for each cylinder (17), including: - a down stroke whereby the piston (15) moves from the top dead centre to the bottom dead centre in the cylinder (17) due to expansion of high pressure and high temperature combustion gasses (9) in the combustion chamber (5);

- an up stroke whereby the piston (15) moves from the bottom dead centre to the top dead centre in the cylinder (17) to compress the fuel air mixture in the cylinder (17); wherein combustion gasses are exhausted from the cylinder (17) and fuel air mixture is introduced into the cylinder (17) at the end of the down stroke and beginning of the up stroke, wherein the combustion gas valve (11) is selectively operable from open to close during the power stroke before the piston (15) is at bottom dead centre and before the combustion gasses are exhausted from the cylinder (17); and wherein the combustion gas valve (11) is selectively operable from close to open when the piston (15) is at, or near, top dead centre.

5. An ignition system (1) according to claim 3 or 4 wherein the combustion gas valve (11) is selectively operable from open to close when the piston (15) is closer to the top dead centre than the bottom dead centre.

6. An ignition system (1) according to any one of the preceding claims further comprising:

- an actuator (21) to selectively open and close the combustion gas valve (11); and

- a controller (23) to provide a control signal (25) to the actuator (21) to selectively operate the combustion gas valve (11).

7. An ignition system (1) according to claim 6 further comprising at least one sensor (27), wherein the controller (23) provides the control signal (25) based on sensor signals (29) indicative of one or more of:

- position of a piston (15) in the cylinder (17); - velocity of a piston (15) in the cylinder (17);

- engine temperature;

- temperature of the fuel air mixture;

- ambient temperature;

- engine speed;

- engine load;

- fuel quality;

- fuel quantity in the fuel air mixture;

- air quality of the surrounding environment;

- air quantity in the fuel air mixture;

- fuel versus air ratio in the fuel air mixture;

- compression ratio of the engine;

- desired pressure of the compressed fuel air mixture;

- temperature of the high pressure and high temperature combustion gasses (9);

- pressure of the high pressure and high temperature combustion gasses (9); and

- quality of exhaust gasses.

8. An ignition system (1) according to either claim 6 or 7 wherein the controller (25) sends the control signal (25) based on a specified or specified range for the temperature and/or pressure of the compressed fuel air mixture (13) in the combustion chamber (5).

9. An internal combustion engine (3) comprising:

- an engine block (16) that defines cylinder walls of a cylinder (17);

- a reciprocating piston (15) that reciprocates inside the cylinder (17), wherein a combustion chamber (5) is defined at least in part by the cylinder (17) and the

reciprocating piston (15);

- a crankshaft (18) driven by the reciprocating piston (15);

- an ignition system (1) according to any one of claims 1 to 8, wherein each piston (15) operates to include:

- a power stroke, or down stroke, whereby the piston (15) moves from a top dead centre to a bottom dead centre in the cylinder (17) due to expansion of high pressure and high temperature combustion gasses (9) in the combustion chamber (5): wherein during at least part of the power stroke, or down stroke, the combustion gas valve (11) is open for the reservoir (7) to receive high pressure combustion gas (9) from the combustion chamber (5), and wherein the combustion gas valve (11) is selectively operable from open to close during the power stroke and before the piston (15) is at bottom dead centre for the reservoir to store the high pressure and high temperature combustion gasses (9);

- a compression stroke, or up stroke, whereby the piston (15) moves from the bottom dead centre to the top dead centre to compress a fuel air mixture in the cylinder (17) and provide the combustion chamber (5) containing the compressed fuel air mixture (13), wherein the combustion gas valve (11) is selectively operable from close to open when the piston (15) is at, or near, top dead centre between: - the compression stroke, or up stroke, and

- the power stroke, or down stroke, to inject high pressure and high temperature combustion gasses (9) from the reservoir (7) into the combustion chamber (5), wherein the injected high pressure and high temperature combustion gasses (9) are above an autoignition temperature and increases pressure to cause combustion of the compressed fuel air mixture (13).

10. An internal combustion engine (3) according to 9 wherein the engine has a four- stroke cycle for each cylinder (15), whereby each piston (15) further operates to include:

- an exhaust stroke whereby the piston (15) moves from the bottom dead centre to the top dead centre in the cylinder (17) to remove combustion gasses from the cylinder (17) via an exhaust (33); and

- an intake stroke whereby the piston (15) moves from the top dead centre to the bottom dead centre where the fuel air mixture is introduced into the cylinder (17) through an intake (31).

11. An internal combustion engine (3) according to 9 wherein the engine has a two- stroke cycle for each cylinder (15), wherein each piston (15) operates to:

- exhaust combustion gasses from the cylinder (17) through an exhaust (33) and introduce the fuel air mixture into the cylinder (17) though an intake (31) at the end of the down stroke and beginning of an up stroke.

12. An ignition method (100) for an internal combustion engine (3) comprising:

- injecting (110), from a reservoir (7), high pressure and high temperature combustion gasses (9) into a combustion chamber (5) that contains a compressed fuel air mixture (13), wherein the high pressure and high temperature combustion gasses (9) are above an autoignition temperature and increases pressure to cause combustion of the compressed fuel air mixture (13); - receiving (120), at the reservoir (7), high pressure and high temperature combustion gasses (9) from the combustion chamber (5) during, or after, combustion;

- storing (130), at the reservoir (7), the high pressure and high temperature combustion gasses (9) during: exhaust of the combustion gasses from the combustion chamber (5); intake of the fuel air mixture into the combustion chamber (5); and compression of the fuel air mixture in the combustion chamber (5).

13. An ignition method (100) according to claim 12 wherein the internal combustion engine (3) is a reciprocating internal combustion engine (3) that includes a reciprocating piston (15) in a cylinder (17) that drives a crankshaft (18), wherein the step of injecting the high pressure and high temperature combustion gasses (9) into the combustion chamber (5) occurs when: the reciprocating piston (15) is at or near top dead centre in the cylinder (17) to provide the combustion chamber (5) containing the compressed fuel air mixture (13).

14. An ignition method (100) according to 13 wherein the reciprocating internal combustion engine (3) has a four-stroke cycle for each cylinder (15) that includes an exhaust stroke, an intake stroke, a compression stroke and a power stroke, and wherein the step of receiving (120), at the reservoir (7), the high pressure and high temperature combustion gasses (9) from the combustion chamber (5) during combustion occurs: during the power stroke of the reciprocating piston (15) where the piston (15) moves from the top dead centre to a bottom dead centre due to expansion of high pressure and high temperature combustion gasses (9) in the combustion chamber (5); and

- before the piston (15) is at bottom dead centre.

15. An ignition method (100) according to 13 wherein the reciprocating internal combustion engine (3) has a two-stroke cycle for each cylinder (15) that includes a down stroke and an up stroke, and wherein the step of receiving (120), at the reservoir (7), the high pressure and high temperature gasses (9) from the combustion chamber (5) during combustion occurs:

- during the down stroke of the reciprocating piston (15) where the piston (15) moves from the top dead centre to a bottom dead entre due to expansion of high pressure and high temperature gasses (9) in the combustion chamber (5); and

- before the piston (15) is at bottom dead centre and before the combustion gasses are exhausted from the cylinder (17).

16. An ignition method (100) according to claim 14 or 15 wherein the step of receiving (120), at the reservoir (7), the high pressure and high temperature combustion gasses (9) from the combustion chamber (5) for each cycle of the piston (15) finishes when the piston (15) is closer to the top dead centre than the bottom dead centre.

17. An ignition method (100) according to any one of claims 12 to 16 further comprising sending a control signal (25) from a controller (23) to an actuator (21), whereby the actuator (21) is operable to open an close a combustion gas valve (11) for injecting, receiving and storing of the high pressure and high temperature combustion gasses (9).

18. An ignition method (100) according to claim 17 wherein the control signals (25) are sent by the controller (23) based on received sensor signals (29), wherein the received sensor signals are indicative of one or more of:

- position of a piston (15) in the cylinder (17);

- velocity of a piston (15) in the cylinder (17);

- engine temperature; - temperature of the fuel air mixture;

- ambient temperature;

- engine speed;

- engine load;

- fuel quality;

- fuel quantity in the fuel air mixture;

- air quality of the surrounding environment;

- air quantity in the fuel air mixture;

- fuel versus air ratio in the fuel air mixture;

- compression ratio of the engine;

- desired pressure of the compressed fuel air mixture;

- temperature of the high pressure and high temperature combustion gasses (9);

- pressure of the high pressure and high temperature combustion gasses (9); and

- quality of exhaust gasses.

19. An ignition method (100) according to either claim 17 or 18 wherein sending a control signal (25) is based on a specified or specified range for the temperature and/or pressure of the compressed fuel air mixture (13) in the combustion chamber (5).

20. A method (200) of operating an internal combustion engine (3) that includes a reciprocating piston (15) in a cylinder (17) that drives a crankshaft (18), and where the engine (3) has a four-stroke cycle for each piston (15), the method comprising: - introducing (101) a fuel air mixture into the cylinder (17) by moving the piston (15) from a top dead centre to a bottom dead centre;

- compressing (103) the fuel air mixture in the cylinder (17) by moving the piston (15) from the bottom dead centre to the top dead centre to provide a combustion chamber (5) containing a compressed fuel air mixture (13);

- injecting (110), from a reservoir (7), high pressure and high temperature combustion gasses (9) into the combustion chamber (5) according to the method according to any one of claims 12 to 14 and 16 to 19;

- powering (115) the piston (15) from the top dead centre to the bottom dead centre due to expansion of high pressure combustion gasses (9) in the combustion chamber (5);

- receiving (120), from the reservoir (7), high pressure and high temperature combustion gasses (9) from the combustion chamber (5) according to the method of any one of claims 12 to 14 and 16 to 19;

- exhausting (125) combustion gasses from the cylinder (17) by moving the piston (15) from the bottom dead centre to the top dead centre;

- storing (130), at the reservoir (7), the high pressure and high temperature combustion gasses (9) according to the method of any one of claims 12 to 14 and 16 to 19.

21. A method (200) of operating an internal combustion engine (3) that includes a reciprocating piston (15) in a cylinder (17) that drives a crankshaft (18), and where the engine (3) has a two-stroke cycle for each piston (15), the method comprising:

- compressing the fuel air mixture in the cylinder (17) in an up stroke by moving the piston (15) from the bottom dead centre to the top dead centre to provide a combustion chamber (5) containing a compressed fuel air mixture (13); - injecting, from a reservoir (7), high pressure and high temperature combustion gasses (9) into the combustion chamber (5) according to the method according to any one of claims 12, 14 and 15 to 19;

- powering the piston (15) in a down stroke from the top dead centre to the bottom dead centre due to expansion of high pressure combustion gasses (9) in a combustion chamber (5);

- receiving, at the reservoir (7), high pressure and high temperature combustion gasses (9) from the combustion chamber (5) according to the method of any one of claims 12, 14 and 15 to 19;

- exhausting combustion gasses from the cylinder (17) and introducing a fuel air mixture into the cylinder (17) at the end of the down stroke and beginning of the up stroke; and wherein the method further comprises:

- storing, at the reservoir (7), the high pressure and high temperature combustion gasses (9) according to the method of any one of claims 12, 14 and 15 to 19.

22. A method of operating an internal combustion engine according to either claim 20 or 21 further comprising:

- increasing an effective compression ratio in the combustion chamber (5) by selectively injecting the high pressure and high temperature combustion gasses (9) from the reservoir (7).

23. A method of operating an internal combustion engine according to any one of claims 20 to 22 further comprising:

- reducing a peak pressure in the combustion chamber (5) by selectively receiving, at the reservoir (7), high pressure and high temperature combustion gasses (9) from the combustion chamber (5).

24. An ignition system (401) for an internal combustion engine (403) including a combustion chamber (5) comprising:

- an auxiliary cylinder (58) in fluid communication with the combustion chamber

(5);

- an auxiliary piston (60) movable within the auxiliary cylinder (58) between a first position and a second position;

- a biasing mechanism (62) to move the auxiliary piston (60) from the first position toward the second position; and

- a retaining mechanism (64, 464) to releasably hold the auxiliary piston (60) in the first position and operable to release the auxiliary piston (60) so that the biasing mechanism (62) moves the auxiliary piston (60) toward the second position.

25. An ignition system according to claim 24, wherein the auxiliary piston (60) is movable from the second position toward the first position against a biasing force of the biasing mechanism (62) due to expansion of high pressure and high temperature combustion gasses (9) in the combustion chamber (5), and wherein, when the auxiliary piston moves to the first position, the retaining mechanism (64, 464) is operable to hold the auxiliary piston (60) at the first position.

26. An ignition system according to claim 24 or 25, wherein the retaining mechanism (64) includes at least one projection (68) which is retractably extendible into an interior of the auxiliary cylinder (58) to engage the auxiliary piston (60) to thereby hold the auxiliary piston (60) in the first position.

27. An ignition system according to claim 26 wherein the auxiliary piston (60) includes at least one recess (70) to receive the at least one projection (68).

28. An ignition system (401) according to claim 24 or 25, wherein the retaining mechanism (464) includes an arm (222) having a first end (222a) and a second end (222b), the first end (222a) of the arm being pivotably connected to the auxiliary piston (60), wherein, when the auxiliary piston (60) moves from the second position to the first position, the second end (222b) of the arm (222) moves relative to the auxiliary piston (60), and wherein the retaining mechanism (464) controls movement of the second end (222b) of the arm (222) when the auxiliary piston (60) is in the first position to thereby hold the auxiliary piston (60) in the first position.

29. An ignition system according to claim 28, wherein the retaining mechanism includes a toggle-like mechanism to control the movement of the second end (222b) of the arm (222) to hold the auxiliary piston in the first position.

30. An ignition system (401) according to any one of claims 24 to 29, wherein the ignition system (401) is for a reciprocating internal combustion engine (403) that includes a reciprocating piston (15) in a main cylinder (17) that drives a crankshaft (18), and wherein, when the reciprocating piston (15) is at, near, or past top dead centre in the main cylinder (17) to provide the combustion chamber (5) containing the compressed fuel air mixture (13), the retaining mechanism (64) is operable to release the auxiliary piston (60) so that the biasing mechanism (62) moves the auxiliary piston (60) toward the second position.

31. An ignition system (401) according to claim 30, wherein the reciprocating internal combustion engine (403) has a four-stroke cycle for each reciprocating piston (15), including:

- a power stroke whereby the reciprocating piston (15) moves from the top dead centre to a bottom dead centre in the main cylinder (17) due to the expansion of the high pressure and high temperature combustion gasses (9) in the combustion chamber (5); - an exhaust stroke whereby the reciprocating piston (15) moves from the bottom dead centre to the top dead centre in the main cylinder (17) to remove combustion gasses from the main cylinder (17);

- an intake stroke whereby the reciprocating piston (15) moves from the top dead centre to the bottom dead centre where the fuel air mixture is introduced into the main cylinder (17); and

- a compression stroke whereby the reciprocating piston (15) moves from the bottom dead centre to the top dead centre to compress the fuel air mixture in the main cylinder (17), wherein the retaining mechanism (64, 464) is selectively operable to release the auxiliary piston (60) when the reciprocating piston (15) is at, near, or past top dead centre between the compression stroke and the power stroke of the four-stroke cycle.

32. An ignition system (401) according to claim 31, wherein the retaining mechanism (64, 464) is selectively operable to hold the auxiliary piston (60) at the first position during the power stroke and before the reciprocating piston (15) is at bottom dead centre.

33. An ignition system (401) according to claim 30, wherein the reciprocating internal combustion engine (403) has a two stroke cycle for each main cylinder (17), including:

- a down stroke whereby the reciprocating piston (15) moves from the top dead centre to the bottom dead centre in the main cylinder (17) due to the expansion of the high pressure and high temperature combustion gasses (9) in the combustion chamber (5); and

- an up stroke whereby the reciprocating piston (15) moves from the bottom dead centre to the top dead centre in the main cylinder (17) to compress the fuel air mixture in the main cylinder (17); wherein combustion gasses are exhausted from the main cylinder (17) and fuel air mixture is introduced into the main cylinder (17) at the end of the down stroke and beginning of the up stroke, and wherein the retaining mechanism (64) is selectively operable to release the auxiliary piston (60) when the reciprocating piston (15) is at, near, or past top dead centre.

34. An ignition system (401) according to claim 33, wherein the retaining mechanism (64, 464) is selectively operable to hold the auxiliary piston (60) at the first position during the power stroke before the reciprocating piston is at bottom dead centre before the combustion gasses are exhausted from the main cylinder (17).

35. An ignition system (401) according to any one of claims 31 to 34, wherein the retaining mechanism (64, 464) is selectively operable to release the auxiliary piston (60) when the reciprocating piston (15) is closer to the top dead centre than the bottom dead centre.

36. An ignition system (401) according to any one of claims 24 to 35 further comprising:

- an actuator (421) to selectively operate the retaining mechanism (64, 464) to release and to hold the auxiliary piston (60); and

- a controller (23) to provide a control signal (25) to the actuator (421) to selectively operate the retaining mechanism (64).

37. An ignition system (401) according to claim 36 further comprising at least one sensor (27), wherein the controller (23) provides the control signal (25) based on sensor signals (29) indicative of one or more of:

- position of a reciprocating piston (15) in the main cylinder (17);

- velocity of a reciprocating piston (15) in the main cylinder (17);

- engine temperature;

- temperature of the fuel air mixture;

- ambient temperature;

- engine speed;

- engine load;

- fuel quality;

- fuel quantity in the fuel air mixture; - air quality of the surrounding environment;

- air quantity in the fuel air mixture;

- fuel versus air ratio in the fuel air mixture;

- compression ratio of the engine;

- desired pressure of the compressed fuel air mixture;

- temperature of the high pressure and high temperature combustion gasses (9);

- pressure of the high pressure and high temperature combustion gasses (9); and

- quality of exhaust gasses.

38. An ignition system (401) according to either claim 36 or 37, wherein the controller (25) sends the control signal (25) based on a specified or specified range for the temperature and/or pressure of the compressed fuel air mixture (13) in the combustion chamber (5).

39. An internal combustion engine (403) comprising:

- an engine block (16) that defines cylinder walls of a main cylinder (17);

- a reciprocating piston (15) that reciprocates inside the main cylinder (17), wherein a combustion chamber (5) is defined at least in part by the main cylinder (17) and the reciprocating piston (15);

- a crankshaft (18) driven by the reciprocating piston (15);

- an ignition system (401) according to any one of claims 24 to 38, wherein each reciprocating piston (15) operates to include:

- a power stroke, or down stroke, whereby the reciprocating piston (15) moves from a top dead centre to a bottom dead centre in the main cylinder (17) due to expansion of high pressure and high temperature combustion gasses (9) in the combustion chamber (5): wherein the retaining mechanism (64) is selectively operable to hold the auxiliary piston (60) when the auxiliary piston (60) moves to the first position due to the expansion of high pressure and high temperature combustion gases (9) during the power stroke and before the reciprocating piston (15) is at bottom dead centre;

- a compression stroke, or up stroke, whereby the reciprocating piston (15) moves from the bottom dead centre to the top dead centre to compress a fuel air mixture in the main cylinder (17) and provide the combustion chamber (5) containing the fuel air mixture (13): wherein the retaining mechanism is selectively operable to release the auxiliary piston when the reciprocating piston (15) is at, near, or past top dead centre between:

- the compression stroke, or up stroke, and

- the power stroke, or down stroke, so that the biasing mechanism (62) moves the auxiliary piston (60) toward the second position to increase a pressure within the combustion chamber (5) to cause combustion of a compressed fuel air mixture (13) contained in the combustion chamber.

40. An internal combustion engine (403) according to claim 39, wherein the engine has a four-stroke cycle for each cylinder (17), whereby each reciprocating piston (15) further operates to include:

- an exhaust stroke whereby the reciprocating piston (15) moves from the bottom dead centre to the top dead centre in the main cylinder (17) to remove combustion gasses from the main cylinder (17) via an exhaust (33); and

- an intake stroke whereby the reciprocating piston (15) moves from the top dead centre to the bottom dead centre where the fuel air mixture is introduced into the main cylinder (17) through an intake (31).

41. An internal combustion engine (403) according to claim 39, wherein the engine has a two-stroke cycle for each cylinder (15), wherein each reciprocating piston (15) operates to:

- exhaust combustion gasses from the main cylinder (17) through an exhaust (33) and introduce the fuel air mixture into the main cylinder (17) though an intake (31) at the end of the down stroke and beginning of an up stroke.

42. An ignition method (300) for an internal combustion engine (403) comprising:

- moving (350) an auxiliary piston (60) from a first position toward a second position within an auxiliary cylinder (58) in fluid communication with a combustion chamber (5) that contains a fuel air mixture (13) to increase a pressure within the combustion chamber (5) to cause combustion of the compressed fuel air mixture (13);

- moving (360) the auxiliary piston (60) from the second position to the first position due to an expansion of combustion gases in the combustion chamber (5) during, or after, combustion; holding (370) the auxiliary piston (60) in the first position during: exhaust of the combustion gasses from the combustion chamber (5); intake of the fuel air mixture into the combustion chamber (5); and compression of the fuel air mixture in the combustion chamber (5).

43 The ignition method (300) of claim 42, further comprising, before the step of holding the auxiliary piston (60), the step of engaging (380) the auxiliary piston (60) at the first position when the auxiliary piston (60) returns to the first position.

44. An ignition method (300) according to claim 42 or 43, wherein the internal combustion engine (403) is a reciprocating internal combustion engine (403) that includes a reciprocating piston (15) in a main cylinder (17) that drives a crankshaft (18), wherein the step of moving (360) the auxiliary piston (60) from the first position toward the second position occurs when: the reciprocating piston (15) is at, near, or past top dead centre in the main cylinder (17) to provide the combustion chamber (5) containing the compressed fuel air mixture (13).

45. An ignition method (300) according to claim 44, wherein the reciprocating internal combustion engine (403) has a four-stroke cycle for each cylinder (15) that includes an exhaust stroke, an intake stroke, a compression stroke and a power stroke, and wherein the step of holding (370) the auxiliary piston at the first position begins: during the power stroke of the reciprocating piston (15) where the reciprocating piston (15) moves from the top dead centre to a bottom dead centre due to expansion of high pressure and high temperature combustion gasses (9) in the combustion chamber (5); and

- before the reciprocating piston (15) is at bottom dead centre.

46. An ignition method (300) according to claim 44, wherein the reciprocating internal combustion engine (403) has a two-stroke cycle for each cylinder (15) that includes a down stroke and an up stroke, and wherein the step of holding (370) the auxiliary piston at the first position begins:

- during the down stroke of the reciprocating piston (15) where the reciprocating piston (15) moves from the top dead centre to a bottom dead entre due to expansion of high pressure and high temperature gasses (9) in the combustion chamber (5); and

- before the reciprocating piston (15) is at bottom dead centre and before the combustion gasses are exhausted from the main cylinder (17).

47. An ignition method (300) according to claim 45 or 46, wherein the step of holding (370) the auxiliary piston (60) at the first position for each cycle of the reciprocating piston (15) begins while the reciprocating piston (15) is closer to the top dead centre than the bottom dead centre.

48. An ignition method (300) according to any one of claims 42 to 47 further comprising sending a control signal (25) from a controller (23) to an actuator (421), whereby the actuator (421) is operable to cause a retaining mechanism (64) to release or catch the auxiliary piston.

49. An ignition method (300) according to claim 48, wherein the control signals (25) are sent by the controller (23) based on received sensor signals (29), wherein the received sensor signals are indicative of one or more of:

- position of a reciprocating piston (15) in the main cylinder (17);

- position of an auxiliary piston (60) in the auxiliary cylinder (58);

- velocity of a reciprocating piston (15) in the main cylinder (17);

- velocity of an auxiliary piston (60) in the auxiliary cylinder (58); - engine temperature;

- temperature of the fuel air mixture;

- ambient temperature;

- engine speed;

- engine load;

- fuel quality;

- fuel quantity in the fuel air mixture;

- air quality of the surrounding environment;

- air quantity in the fuel air mixture;

- fuel versus air ratio in the fuel air mixture;

- compression ratio of the engine;

- desired pressure of the compressed fuel air mixture;

- temperature of the high pressure and high temperature combustion gasses (9);

- pressure of the high pressure and high temperature combustion gasses (9); and

- quality of exhaust gasses.

50. An ignition method (300) according to either claim 48 or 49, wherein sending a control signal (25) is based on a specified or specified range for the temperature and/or pressure of the compressed fuel air mixture (13) in the combustion chamber (5).

51. A method (400) of operating an internal combustion engine (403) that includes a reciprocating piston (15) in a main cylinder (17) that drives a crankshaft (18), and where the engine (403) has a four-stroke cycle for each reciprocating piston (15), the method comprising:

- introducing (101) a fuel air mixture into the main cylinder (17) by moving the reciprocating piston (15) from a top dead centre to a bottom dead centre; - compressing (103) the fuel air mixture in the main cylinder (17) by moving the reciprocating piston (15) from the bottom dead centre to the top dead centre to provide a combustion chamber (5) containing a compressed fuel air mixture (13);

- moving (350) an auxiliary piston from a first position toward a second position within an auxiliary cylinder (58) in fluid communication with the combustion chamber (5) according to the method according to any one of claims 45 and 47 to 50;

- powering (115) the reciprocating piston (15) from the top dead centre to the bottom dead centre due to expansion of high pressure combustion gasses (9) in the combustion chamber (5);

- moving (360) the auxiliary piston from the second position to the first position according to the method of any one of claims 45 and 47 to 50;

- exhausting (125) combustion gasses from the main cylinder (17) by moving the reciprocating piston (15) from the bottom dead centre to the top dead centre; and

- holding (380) the auxiliary piston (60) at the first position according to the method of any one of claims 45 and 47 to 50.

52. A method (400) of operating an internal combustion engine (403) that includes a reciprocating piston (15) in a main cylinder (17) that drives a crankshaft (18), and where the engine (403) has a two-stroke cycle for each reciprocating piston (15), the method comprising:

- compressing the fuel air mixture in the main cylinder (17) in an up stroke by moving the reciprocating piston (15) from the bottom dead centre to the top dead centre to provide a combustion chamber (5) containing a compressed fuel air mixture (13);

- moving (350) an auxiliary piston from a first position toward a second position within an auxiliary cylinder (58) in fluid communication with the combustion chamber (5) according to the method according to any one of claims 46 to 50;

- powering the reciprocating piston (15) in a down stroke from the top dead centre to the bottom dead centre due to expansion of high pressure combustion gasses (9) in a combustion chamber (5); - moving (360) the auxiliary piston from the second position to the first position according to the method of any one of claims 46 to 50;

- exhausting combustion gasses from the main cylinder (17) and introducing a fuel air mixture into the main cylinder (17) at the end of the down stroke and beginning of the up stroke; and wherein the method further comprises:

- holding (380) the auxiliary piston (60) at the first position according to the method of any one of claims 46 to 50.

53. A method of operating an internal combustion engine according to either claim 51 or 52 further comprising:

- increasing an effective compression ratio in the combustion chamber (5) by selectively moving the auxiliary piston (60) from the first position toward the second position within the auxiliary cylinder (58).

54. An ignition system (401) for an internal combustion engine (403) including a combustion chamber (5) comprising:

- an auxiliary cylinder (58) in fluid communication with the combustion chamber

(5);

- an auxiliary piston (60) movable within the auxiliary cylinder (58) between a first position and a second position;

- a biasing mechanism (62) to move the auxiliary piston (60) from the first position toward the second position; and

- a retaining mechanism (64) to releasably hold the auxiliary piston (60) in the first position and operable to release the auxiliary piston (60) so that the biasing

mechanism (62) moves the auxiliary piston (60) toward the second position, wherein movement of the auxiliary piston (60) from the first position toward the second position increases a pressure within the combustion chamber (5) to cause combustion of a compressed fuel air mixture (13) contained in the combustion chamber.

55. An ignition system (401) according to claim 54, wherein the auxiliary cylinder (58) and a head (80) of the auxiliary piston (60) define an auxiliary chamber (61) which opens into the combustion chamber (5) of a main cylinder (17).

56. An ignition system (401) according to any one of claims 24 to 38, wherein the auxiliary cylinder (58) and a head (80) of the auxiliary piston (60) define an auxiliary chamber (61) which opens into the combustion chamber (5) of a main cylinder (17).

57. An ignition system (401) according to claim 55 or 56, wherein movement of the auxiliary piston (60) from the first position toward the second position increases a pressure within the combustion chamber (5) and the auxiliary chamber (61) to cause combustion of a compressed fuel air mixture.

58. An ignition system (401) according to any one of claims 55 to 57, wherein the auxiliary chamber (61) is a pre-chamber or a pre-combustion chamber.

59. An ignition system (401) according to anyone of claims 24 to 38 and 54 to 58, wherein the auxiliary cylinder (58) is separated from the main cylinder (17) via a wall (63) in which at least one opening (65) is formed.

60. An ignition system (401) according to any one of claims 24 to 38 and 54, further comprising: at least one additional chamber, wherein the at least one additional chamber is at a position intermediate the auxiliary cylinder (58) and the main cylinder (17).

61. An internal combustion engine according to any one of claims 39 to 41, further comprising at least one additional chamber at a position intermediate the auxiliary cylinder (58) and the main cylinder (17).

62. An ignition method according to claim 42 to 50, wherein the ignition system (401) includes at least one additional chamber provided at a position intermediate the auxiliary cylinder (58) and the main cylinder (17).

63. An ignition system (501) according to any one of claims 24 to 38, 53 and 60 further comprising an adjustment system (502) to selectively adjust the first position and second position of the auxiliary piston in the auxiliary cylinder.

64. An internal combustion engine (503) according to any one of claims 39 to 41, and 61 further comprising an adjustment system (502) to selectively adjust the first position and second position of the auxiliary piston in the auxiliary cylinder.

65. An ignition method according to claim 42 to 50, and 62, wherein the first position and second position of the auxiliary piston in the auxiliary cylinder is selectively adjustable, and wherein the first position and second position is selected to adjust the increase in pressure within the combustion chamber when the auxiliary piston moves from the first position and the second position.

66. An ignition system (1) for an internal combustion engine (3) according to claim 1, 24 or 54 wherein the internal combustion engine is a rotary engine.

67. An ignition method for an internal combustion engine according to claim 12 or 42 wherein the internal combustion engine is a rotary engine.

Description:
"Internal combustion engine"

Technical Field

[0001] The present disclosure relates to an internal combustion engine. Background

[0002] Internal combustion engines require means to reliably and safely initiate combustion of fuel inside the engine. For reciprocating engines there are two types that are commonly used, spark ignition and compression ignition.

[0003] Spark ignition typically involves using a spark plug to create a spark inside a combustion chamber containing a compressed fuel air mixture. The spark ignites the compressed fuel air mixture and the subsequent combustion results in high temperature and high pressure combustion gasses that expand to drive the reciprocating piston. Spark ignition is typically used in internal combustion engines that use petrol (gasoline).

[0004] Compression ignition on the other hand uses compression of the contents in the combustion chamber to elevate the temperature that is high enough to cause ignition of fuel injected into the combustion chamber. Common engines that use compression ignition include diesel fuelled engines.

[0005] There have been experiments with internal combustion engines that use homogenous charge compression ignition (HCCI). Such engines, at least in theory, have a fuel air mixture (the homogenous charge) that is introduced into the cylinder and then compressed by the piston. The compression of the fuel air mixture results in high pressure and, more

importantly, high temperature of the homogenous charge. The high temperature is such at or above the autoignition temperature of the fuel air mixture to cause combustion. Such research into HCCI engines has shown some disadvantages and challenges. One difficulty is controlling the point of autoignition as variables (such as the temperature of the fuel air mixture, the engine, and/or speed of the engine) may change the timing of autoignition. One challenge includes preventing autoignition that occurs prematurely (in particular when the piston is still moving upwards and well before top dead centre).

[0006] Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

[0007] Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present disclosure as it existed before the priority date of each claim of this application.

Summary

[0008] The present disclosure relates to a system and method to initiate combustion based on energy of combustion gasses from a previous cycle in an internal combustion engine. In some examples, this includes storing some of the energised combustion gasses in a reservoir, whereby the exhaust combustion gasses are selectively reintroduced into the combustion chamber to cause combustion. In other examples, the energised combustion gasses can energise a mechanical system, which in turn, is selectively activated so that energy is released to the combustion chamber to cause combustion.

[0009] An ignition system for an internal combustion engine including a combustion chamber comprising: a reservoir to store high pressure and high temperature combustion gasses; and a combustion gas valve selectively operable to provide fluid communication between the reservoir and the combustion chamber. The combustion gas valve is operable to open to inject high pressure and high temperature combustion gasses from the reservoir into the combustion chamber that contains a compressed fuel air mixture, wherein the injected high pressure and high temperature combustion gasses are above an autoignition temperature and increases pressure to cause combustion of the compressed fuel air mixture. During, or after, combustion of the compressed fuel air mixture, the combustion gas valve is operable to be open for the reservoir to receive high pressure and high temperature combustion gasses from the combustion chamber. After combustion, the combustion gas valve may be operable to be closed for the reservoir. This allows the reservoir to store the high pressure and high temperature combustion gasses during: exhaust of combustion gasses from the combustion chamber; intake of fuel air mixture into the combustion chamber; and compression of fuel air mixture in the combustion chamber. LOOIOJ The ignition system may be lor a reciprocating internal combustion engine that includes a reciprocating piston in a cylinder that drives a crankshaft. When the reciprocating piston is at or near top dead centre in the cylinder to provide the combustion chamber containing the compressed fuel air mixture, the combustion gas valve may be operable to open to inject high pressure and high temperature combustion gasses into the combustion chamber.

[0011] In some examples, the ignition system is for an reciprocating internal combustion engine that has a four-stroke cycle for each piston, including:

- a power stroke whereby the piston moves from the top dead centre to a bottom dead centre in the cylinder due to expansion of high pressure and high temperature combustion gasses in the combustion chamber;

- an exhaust stroke whereby the piston moves from the bottom dead centre to the top dead centre in the cylinder to remove combustion gasses from the cylinder;

- an intake stroke whereby the piston moves from the top dead centre to the bottom dead centre where the fuel air mixture is introduced into the cylinder; and

- a compression stroke whereby the piston moves from the bottom dead centre to the top dead centre to compress the fuel air mixture in the cylinder, wherein the combustion gas valve is selectively operable from close to open when the piston is at, or near, top dead centre between the compression stroke and the power stroke of the four-stroke cycle; and wherein the combustion gas valve is selectively operable from open to close during the power stroke and before the piston is at bottom dead centre.

[0012] In other examples, ignition system is for a reciprocating internal combustion engine that has a two stroke cycle for each cylinder, including: - a down stroke whereby the piston moves from the top dead centre to the bottom dead centre in the cylinder due to expansion of high pressure and high temperature combustion gasses in the combustion chamber;

- an up stroke whereby the piston moves from the bottom dead centre to the top dead centre in the cylinder to compress the fuel air mixture in the cylinder; wherein combustion gasses are exhausted from the cylinder and fuel air mixture is introduced into the cylinder at the end of the down stroke and beginning of the up stroke, wherein the combustion gas valve is selectively operable from open to close during the power stroke before the piston is at bottom dead centre and before the combustion gasses are exhausted from the cylinder; and wherein the combustion gas valve is selectively operable from close to open when the piston is at, or near, top dead centre.

[0013] In some examples, the combustion gas valve is selectively operable from open to close when the piston is closer to the top dead centre than the bottom dead centre.

[0014] In some examples the ignition system further comprises: an actuator to selectively open and close the combustion gas valve; and a controller to provide a control signal to the actuator to selectively operate the combustion gas valve.

[0015] The ignition system may further comprise at least one sensor, wherein the controller provides the control signal based on sensor signals indicative of one or more of:

- position of a piston in the cylinder;

- velocity of a piston in the cylinder;

- engine temperature;

- temperature of the fuel air mixture; - ambient temperature;

- engine speed;

- engine load;

- fuel quality;

- fuel quantity in the fuel air mixture;

- air quality of the surrounding environment;

- air quantity in the fuel air mixture;

- fuel versus air ratio in the fuel air mixture;

- compression ratio of the engine;

- desired pressure of the compressed fuel air mixture;

- temperature of the high pressure and high temperature combustion gasses;

- pressure of the high pressure and high temperature combustion gasses; and

- quality of exhaust gasses.

[0016] In the ignition system, the controller may send the control signal based on a specified or specified range for the temperature and/or pressure of the compressed fuel air mixture in the combustion chamber.

[0017] An internal combustion engine comprising:

- an engine block that defines cylinder walls of a cylinder;

- a reciprocating piston that reciprocates inside the cylinder, wherein a combustion - a crankshaft driven by the reciprocating piston;

- an ignition system as described in the examples above, wherein each piston operates to include:

- a power stroke, or down stroke, whereby the piston moves from a top dead centre to a bottom dead centre in the cylinder due to expansion of high pressure and high temperature combustion gasses in the combustion chamber: wherein during at least part of the power stroke, or down stroke, the combustion gas valve is open for the reservoir to receive high pressure combustion gas from the combustion chamber, and wherein the combustion gas valve is selectively operable from open to close during the power stroke and before the piston is at bottom dead centre for the reservoir to store the high pressure and high temperature combustion gasses;

- a compression stroke, or up stroke, whereby the piston moves from the bottom dead centre to the top dead centre to compress a fuel air mixture in the cylinder and provide the combustion chamber containing the compressed fuel air mixture, wherein the combustion gas valve is selectively operable from close to open when the piston is at, or near, top dead centre between:

- the compression stroke, or up stroke, and

- the power stroke, or down stroke, to inject high pressure and high temperature combustion gasses from the reservoir into the combustion chamber, wherein the injected high pressure and high temperature combustion gasses are above an autoignition temperature and increases pressure to cause combustion of the compressed fuel air mixture. L0018J In some examples, the internal combustion engine has a four-stroke cycle lor each cylinder, whereby each piston further operates to include:

- an exhaust stroke whereby the piston moves from the bottom dead centre to the top dead centre in the cylinder to remove combustion gasses from the cylinder via an exhaust; and

- an intake stroke whereby the piston moves from the top dead centre to the bottom dead centre where the fuel air mixture is introduced into the cylinder through an intake.

[0019] In some examples, the internal combustion engine has a two-stroke cycle for each cylinder, wherein each piston operates to:

- exhaust combustion gasses from the cylinder through an exhaust and introduce the fuel air mixture into the cylinder though an intake at the end of the down stroke and beginning of an up stroke.

[0020] An ignition method for an internal combustion engine comprising:

- injecting, from a reservoir, high pressure and high temperature combustion gasses into a combustion chamber that contains a compressed fuel air mixture, wherein the high pressure and high temperature combustion gasses are above an autoignition temperature and increases pressure to cause combustion of the compressed fuel air mixture;

- receiving, at the reservoir, high pressure and high temperature combustion gasses from the combustion chamber during, or after, combustion;

- storing at the reservoir the high pressure and high temperature combustion gasses during: exhaust of the combustion gasses from the combustion chamber; intake of the fuel air mixture into the combustion chamber; and compression of the fuel air mixture in the combustion chamber.

[0021] In some examples of the ignition method, the internal combustion engine is a reciprocating internal combustion engine that includes a reciprocating piston in a cylinder that drives a crankshaft, wherein the step of injecting the high pressure and high temperature the reciprocating piston is at or near top dead centre in the cylinder to provide the combustion chamber containing the compressed fuel air mixture.

[0022] In some examples of the ignition method, the reciprocating internal combustion engine has a four-stroke cycle for each cylinder that includes an exhaust stroke, an intake stroke, a compression stroke and a power stroke, and wherein the step of receiving, at the reservoir, the high pressure and high temperature combustion gasses from the combustion chamber during combustion occurs:

- during the power stroke of the reciprocating piston where the piston moves from the top dead centre to a bottom dead centre due to expansion of high pressure and high temperature combustion gasses in the combustion chamber; and

- before the piston is at bottom dead centre.

[0023] In some examples of the ignition method, the reciprocating internal combustion engine has a two- stroke cycle for each cylinder that includes a down stroke and an up stroke, and wherein the step of receiving, at the reservoir, the high pressure and high temperature gasses from the combustion chamber during combustion occurs:

- during the down stroke of the reciprocating piston where the piston moves from the top dead centre to a bottom dead entre due to expansion of high pressure and high temperature gasses in the combustion chamber; and

- before the piston is at bottom dead centre and before the combustion gasses are exhausted from the cylinder.

[0024] In some examples of the ignition method, the step of receiving, at the reservoir, the high pressure and high temperature combustion gasses from the combustion chamber for each cycle of the piston finishes when the piston is closer to the top dead centre than the bottom dead centre. L0025J In some examples, the ignition method further comprises sending a control signal from a controller to an actuator, whereby the actuator is operable to open an close a combustion gas valve for injecting, receiving and storing of the high pressure and high temperature combustion gasses.

[0026] In some examples, the control signals are sent by the controller based on received sensor signals, wherein the received sensor signals are indicative of one or more of:

- position of a piston in the cylinder;

- velocity of a piston in the cylinder;

- engine temperature;

- temperature of the fuel air mixture;

- ambient temperature;

- engine speed;

- engine load;

- fuel quality;

- fuel quantity in the fuel air mixture;

- air quality of the surrounding environment;

- air quantity in the fuel air mixture;

- fuel versus air ratio in the fuel air mixture;

- compression ratio of the engine;

- desired pressure of the compressed fuel air mixture; - temperature of the high pressure and high temperature combustion gasses;

- pressure of the high pressure and high temperature combustion gasses; and

- quality of exhaust gasses.

[0027] In some examples of the ignition method, sending a control signal is based on a specified or specified range for the temperature and/or pressure of the compressed fuel air mixture in the combustion chamber.

[0028] A method of operating an internal combustion engine that includes a reciprocating piston in a cylinder that drives a crankshaft, and where the engine has a four-stroke cycle for each piston, the method comprising:

- introducing a fuel air mixture into the cylinder by moving the piston from a top dead centre to a bottom dead centre;

- compressing the fuel air mixture in the cylinder by moving the piston from the bottom dead centre to the top dead centre to provide a combustion chamber containing a compressed fuel air mixture;

- injecting, from a reservoir , high pressure and high temperature combustion gasses into the combustion chamber according to the ignition method described above;

- powering the piston from the top dead centre to the bottom dead centre due to expansion of high pressure combustion gasses in the combustion chamber;

- receiving, from the reservoir, high pressure and high temperature combustion gasses from the combustion chamber according to the ignition method described above;

- exhausting combustion gasses from the cylinder by moving the piston from the bottom dead centre to the top dead centre;

- storing, at the reservoir, the high pressure and high temperature combustion gasses according to ignition method described above. L0029J A method of operating an internal combustion engine that includes a reciprocating piston in a cylinder that drives a crankshaft, and where the engine has a two-stroke cycle for each piston, the method comprising:

- compressing the fuel air mixture in the cylinder in an up stroke by moving the piston from the bottom dead centre to the top dead centre to provide a combustion chamber containing a compressed fuel air mixture;

- injecting, from a reservoir, high pressure and high temperature combustion gasses into the combustion chamber according to the ignition method described above.

- powering the piston in a down stroke from the top dead centre to the bottom dead centre due to expansion of high pressure combustion gasses in a combustion chamber;

- receiving, at the reservoir, high pressure and high temperature combustion gasses from the combustion chamber according to the ignition method described above;

- exhausting combustion gasses from the cylinder and introducing a fuel air mixture into the cylinder at the end of the down stroke and beginning of the up stroke; and wherein the method further comprises:

- storing, at the reservoir, the high pressure and high temperature combustion gasses according to the ignition method described above.

[0030] In some examples, the method of operating an internal combustion engine further comprises increasing an effective compression ratio in the combustion chamber by selectively injecting the high pressure and high temperature combustion gasses from the reservoir.

[0031] In some examples, the method of operating an internal combustion engine further comprises reducing a peak pressure in the combustion chamber by selectively receiving, at the reservoir, high pressure and high temperature combustion gasses from the combustion chamber. [0032] An ignition system for an internal combustion engine including a combustion chamber comprises: an auxiliary cylinder in fluid communication with the combustion chamber; an auxiliary piston movable within the auxiliary cylinder between a first position and a second position; a biasing mechanism to move the auxiliary piston from the first position toward the second position; and a retaining mechanism to releasably hold the auxiliary piston in the first position and operable to release the auxiliary piston so that the biasing mechanism moves the auxiliary piston toward the second position.

[0033] Disclosed herein is an ignition system for an internal combustion engine including a combustion chamber which comprises: an auxiliary cylinder in fluid communication with the combustion chamber; an auxiliary piston movable within the auxiliary cylinder between a first position and a second position; a biasing mechanism to move the auxiliary piston from the first position toward the second position; and a retaining mechanism to releasably hold the auxiliary piston in the first position and operable to release the auxiliary piston so that the biasing mechanism moves the auxiliary piston toward the second position, wherein movement of the auxiliary piston from the first position toward the second position increases a pressure within the combustion chamber to cause combustion of a compressed fuel air mixture contained in the combustion chamber.

[0034] The auxiliary piston may be movable from the second position toward the first position due to expansion of high pressure and high temperature combustion gasses in the combustion chamber and the retaining mechanism may be operable to hold the auxiliary piston at the first position.

[0035] The auxiliary piston may be movable from the second position toward the first position due to a mechanical means and the retaining mechanism may be operable to hold the auxiliary piston at the first position.

[0036] The retaining mechanism may include at least one projection which is retractably extendible into an interior of the auxiliary cylinder to engage the auxiliary piston to thereby hold the auxiliary piston in the first position.

[0037] The auxiliary piston may include at least one recess to receive the at least one projection.

[0038] The retaining mechanism may include an arm having a first end and a second end. The first end of the arm may be pivotably connected to the auxiliary piston. When the auxiliary piston moves from the second position to the first position, the second end of the arm may move relative to the auxiliary piston. The retaining mechanism may control movement of the second end of the arm when the auxiliary piston is in the first position to thereby hold the auxiliary piston in the first position.

[0039] The retaining mechanism may include a toggle-like mechanism to control the movement of the second end of the arm to hold the auxiliary piston in the first position. The retaining mechanism may include a pair of the toggle-like mechanisms.

[0040] The ignition system may be for a reciprocating internal combustion engine that includes a reciprocating piston in a main cylinder that drives a crankshaft. When the reciprocating piston is at, near, or past top dead centre in the main cylinder to provide the combustion chamber containing the compressed fuel air mixture, the retaining mechanism may be operable to release the auxiliary piston so that the biasing mechanism moves the auxiliary piston toward the second position.

[0041] In some examples, the ignition system is for a reciprocating internal combustion engine that has a four- stroke cycle for each reciprocating piston, including:

- a power stroke whereby the reciprocating piston moves from the top dead centre to a bottom dead centre in the cylinder due to expansion of high pressure and high temperature combustion gasses in the combustion chamber;

- an exhaust stroke whereby the reciprocating piston moves from the bottom dead centre to the top dead centre in the cylinder to remove combustion gasses from the cylinder;

- an intake stroke whereby the reciprocating piston moves from the top dead centre to the bottom dead centre where the fuel air mixture is introduced into the cylinder; and

- a compression stroke whereby the reciprocating piston moves from the bottom dead centre to the top dead centre to compress the fuel air mixture in the cylinder, wherein the retaining mechanism is selectively operable to release the auxiliary piston when the reciprocating piston is at, near, or past top dead centre between the compression stroke and the power stroke of the four-stroke cycle.

[0042] In such examples, the retaining mechanism may be selectively operable to hold the auxiliary piston at the first position during the power stroke and before the reciprocating [0043] In other examples, the ignition system is for a reciprocating internal combustion engine that has a two stroke cycle for each main cylinder, including:

- a down stroke whereby the reciprocating piston moves from the top dead centre to the bottom dead centre in the main cylinder due to expansion of high pressure and high temperature combustion gasses in the combustion chamber; and

- an up stroke whereby the reciprocating piston moves from the bottom dead centre to the top dead centre in the main cylinder to compress the fuel air mixture in the main cylinder; wherein combustion gasses are exhausted from the main cylinder and fuel air mixture is introduced into the main cylinder at the end of the down stroke and beginning of the up stroke, wherein the retaining mechanism is selectively operable to release the auxiliary piston when the reciprocating piston is at, near, or past top dead centre.

[0044] In such examples, the retaining mechanism may be selectively operable to hold the auxiliary piston at the first position during the power stroke before the reciprocating piston is at bottom dead centre before the combustion gasses are exhausted from the main cylinder.

[0045] In some examples, the retaining mechanism is selectively operable to release the auxiliary piston when the reciprocating piston is closer to the top dead centre than the bottom dead centre.

[0046] In some examples, the ignition system further comprises: an actuator to selectively operate the retaining mechanism to release and to hold the auxiliary piston; and a controller to provide a control signal to the actuator to selectively operate the retaining mechanism.

[0047] The ignition system may further comprise at least one sensor, wherein the controller provides the control signal based on sensor signals indicative of one or more of:

- position of a reciprocating piston in the main cylinder;

- position of an auxiliary piston in the auxiliary cylinder;

- velocity of a reciprocating piston in the main cylinder;

- velocity of an auxiliary piston in the auxiliary cylinder; - engine temperature;

- temperature of the fuel air mixture;

- ambient temperature;

- engine speed;

- engine load;

- fuel quality;

- fuel quantity in the fuel air mixture;

- air quality of the surrounding environment;

- air quantity in the fuel air mixture;

- fuel versus air ratio in the fuel air mixture;

- compression ratio of the engine;

- desired pressure of the compressed fuel air mixture;

- temperature of the high pressure and high temperature combustion gasses;

- pressure of the high pressure and high temperature combustion gasses; and

- quality of exhaust gasses.

[0048] In the ignition system, the controller may send the control signal based on a specified or specified range for the temperature and/or pressure of the compressed fuel air mixture in the combustion chamber.

[0049] The auxiliary cylinder may be separated from the main cylinder. For example, the auxiliary cylinder may be separated from the main cylinder by a wall in which at least one opening is formed.

[0050] The auxiliary cylinder and a head of the auxiliary piston may define an auxiliary chamber which opens into the combustion chamber of the main cylinder. The auxiliary chamber may be further defined by the wall in which at least one opening is formed.

Therefore, movement of the auxiliary piston from the first position toward the second position may increase a pressure within the combustion chamber and/or the auxiliary chamber to cause combustion of a compressed fuel air mixture. The auxiliary chamber may be a pre-chamber or a pre-combustion chamber. Combustion of the fuel air mixture may begin in the auxiliary chamber. The auxiliary chamber may include a glow plug or a spark plug.

[0051] In addition, the ignition system may further include at least one additional chamber. The at least one additional chamber may be at a position intermediate the auxiliary cylinder and the main cylinder. Movement of the auxiliary piston from the first position toward the second position may increase a pressure within the combustion chamber and/or the additional chamber to cause combustion of a compressed fuel air mixture contained in the combustion chamber and the additional chamber. The additional chamber may be a pre-chamber or a pre- combustion chamber.

[0052] The ignition system may further comprise an adjustment system to selectively adjust the first position and second position of the auxiliary piston in the auxiliary cylinder. This may be used to adjust the increase in pressure within the combustion chamber. This may be advantageous when the engine is operating at various throttle settings (and different volumetric efficiencies) and adjustment of the pressure may allow consistent and reliable ignition.

[0053] An internal combustion engine comprises:

- an engine block that defines cylinder walls of a main cylinder;

- a reciprocating piston that reciprocates inside the main cylinder, wherein a combustion chamber is defined at least in part by the main cylinder and the reciprocating piston;

- a crankshaft driven by the reciprocating piston;

- an ignition system as described in the examples above, wherein each reciprocating piston operates to include:

- a power stroke, or down stroke, whereby the reciprocating piston moves from a top dead centre to a bottom dead centre in the cylinder due to expansion of high pressure and high temperature combustion gasses in the combustion chamber: wherein the retaining mechanism is selectively operable to hold the auxiliary piston when the auxiliary piston moves to the first position due to the expansion of high pressure and high temperature combustion gases during the power stroke and before the reciprocating piston is at bottom dead centre;

- a compression stroke, or up stroke, whereby the reciprocating piston moves from the bottom dead centre to the top dead centre to compress a fuel air mixture in the cylinder and provide the combustion chamber containing the compressed fuel air mixture, wherein the retaining mechanism is selectively operable to release the auxiliary piston when the reciprocating piston is at, near, or past top dead centre between:

- the compression stroke, or up stroke, and

- the power stroke, or down stroke, so that the biasing mechanism moves the auxiliary piston toward the second position to increase a pressure within the combustion chamber to cause combustion of a compressed fuel air mixture contained in the combustion chamber.

[0054] In some examples, the internal combustion engine has a four-stroke cycle for each cylinder, whereby each reciprocating piston further operates to include:

- an exhaust stroke whereby the reciprocating piston moves from the bottom dead centre to the top dead centre in the cylinder to remove combustion gasses from the cylinder via an exhaust; and

- an intake stroke whereby the reciprocating piston moves from the top dead centre to the bottom dead centre where the fuel air mixture is introduced into the cylinder through an intake.

[0055] In some examples, the internal combustion engine has a two-stroke cycle for each cylinder, wherein each reciprocating piston operates to:

- exhaust combustion gasses from the cylinder through an exhaust and introduce the fuel air mixture into the cylinder though an intake at the end of the down stroke and beginning of an up stroke.

[0056] In the internal combustion engine, the auxiliary cylinder and a head of the auxiliary piston may define an auxiliary chamber which opens into the combustion chamber of the main cylinder. The auxiliary chamber may be a pre-chamber or a pre-combustion chamber. Combustion of the fuel air mixture may begin in the auxiliary chamber. The auxiliary chamber may include a glow plug or a spark plug.

[0057] In the internal combustion engine may further comprising: at least one additional chamber at a position intermediate the auxiliary cylinder and the main cylinder.

[0058] The internal combustion engine may also comprise an adjustment system to selectively adjust the first position and second position of the auxiliary piston in the auxiliary cylinder.

[0059] An ignition method for an internal combustion engine comprises:

- moving an auxiliary piston from a first position toward a second position within an auxiliary cylinder in fluid communication with a combustion chamber that contains a fuel air mixture to increase a pressure within the combustion chamber to cause combustion of the compressed fuel air mixture;

- moving the auxiliary piston from the second position to the first position due to an expansion of combustion gases in the combustion chamber during, or after, combustion; holding the auxiliary piston in the first position during: exhaust of the combustion gasses from the combustion chamber; intake of the fuel air mixture into the combustion chamber; and compression of the fuel air mixture in the combustion chamber.

The ignition method may comprise, before the step of holding the auxiliary piston, the step of engaging the auxiliary piston at the first position when the auxiliary piston returns to the first position.

[0060] In some examples of the ignition method, the internal combustion engine is a reciprocating internal combustion engine that includes a reciprocating piston in a cylinder that drives a crankshaft, wherein the step of moving the auxiliary piston from the first position toward the second position occurs when: the reciprocating piston is at, near, or past top dead centre in the main cylinder to provide the combustion chamber containing the compressed fuel air mixture. [0061] In some examples of the ignition method, the reciprocating internal combustion engine has a four-stroke cycle for each cylinder that includes an exhaust stroke, an intake stroke, a compression stroke and a power stroke, and wherein the step of holding the auxiliary piston at the first position begins:

- during the power stroke of the reciprocating piston where the reciprocating piston moves from the top dead centre to a bottom dead centre due to expansion of high pressure and high temperature combustion gasses in the combustion chamber; and

- before the reciprocating piston is at bottom dead centre.

[0062] In some examples of the ignition method, the reciprocating internal combustion engine has a two- stroke cycle for each cylinder that includes a down stroke and an up stroke, and wherein the step of holding the auxiliary piston at the first position begins:

- during the down stroke of the reciprocating piston where the reciprocating piston moves from the top dead centre to a bottom dead entre due to expansion of high pressure and high temperature gasses in the combustion chamber; and

- before the reciprocating piston is at bottom dead centre and before the combustion gasses are exhausted from the main cylinder.

[0063] In some examples of the ignition method, the step of holding the auxiliary piston at the first position for each cycle of the reciprocating piston begins while the reciprocating piston is closer to the top dead centre than the bottom dead centre.

[0064] In some examples, the ignition method further comprises sending a control signal from a controller to an actuator, whereby the actuator is operable to cause a retaining mechanism to release or catch the auxiliary piston.

[0065] In some examples, the control signals are sent by the controller based on received sensor signals, wherein the received sensor signals are indicative of one or more of:

- position of a reciprocating piston in the main cylinder;

- position of an auxiliary piston in the auxiliary cylinder;

- velocity of a reciprocating piston in the main cylinder; - velocity of an auxiliary piston in the auxiliary cylinder;

- engine temperature;

- temperature of the fuel air mixture;

- ambient temperature;

- engine speed;

- engine load;

- fuel quality;

- fuel quantity in the fuel air mixture;

- air quality of the surrounding environment;

- air quantity in the fuel air mixture;

- fuel versus air ratio in the fuel air mixture;

- compression ratio of the engine;

- desired pressure of the compressed fuel air mixture;

- temperature of the high pressure and high temperature combustion gasses;

- pressure of the high pressure and high temperature combustion gasses; and

- quality of exhaust gasses.

[0066] In some examples of the ignition method, sending a control signal is based on a specified or specified range for the temperature and/or pressure of the compressed fuel air mixture in the combustion chamber.

[0067] In the ignition method, the auxiliary cylinder and a head of the auxiliary piston may define an auxiliary chamber which opens into the combustion chamber of the main cylinder. The auxiliary chamber may be a pre-chamber or a pre-combustion chamber. The ignition method may include the step of initiating combustion in the auxiliary chamber. The auxiliary chamber may include a glow plug or a spark plug.

[0068] In the ignition method, the ignition system may include at least one additional chamber provided at a position intermediate the auxiliary cylinder and the main cylinder. [0069] In the ignition method, the first position and second position of the auxiliary piston in the auxiliary cylinder may be selectively adjustable, and wherein the first position and second position is selected to adjust the increase in pressure within the combustion chamber when the auxiliary piston moves from the first position and the second position.

[0070] A method of operating an internal combustion engine that includes a reciprocating piston in a cylinder that drives a crankshaft, and where the engine has a four-stroke cycle for each reciprocating piston, the method comprising:

- introducing a fuel air mixture into the cylinder by moving the reciprocating piston from a top dead centre to a bottom dead centre;

- compressing the fuel air mixture in the cylinder by moving the reciprocating piston from the bottom dead centre to the top dead centre to provide a combustion chamber containing a compressed fuel air mixture;

- moving an auxiliary piston from a first position toward a second position within an auxiliary cylinder in fluid communication with the combustion chamber according to the ignition method described above;

- powering the reciprocating piston from the top dead centre to the bottom dead centre due to expansion of high pressure combustion gasses in the combustion chamber;

- moving an auxiliary piston from a first position toward a second position within an auxiliary cylinder in fluid communication with the combustion chamber according to the ignition method described above;

- exhausting combustion gasses from the cylinder by moving the reciprocating piston from the bottom dead centre to the top dead centre;

- holding the auxiliary piston at the first position according to ignition method described above.

[0071] A method of operating an internal combustion engine that includes a reciprocating piston in a cylinder that drives a crankshaft, and where the engine has a two-stroke cycle for each reciprocating piston, the method comprising: - compressing the fuel air mixture in the cylinder in an up stroke by moving the reciprocating piston from the bottom dead centre to the top dead centre to provide a combustion chamber containing a compressed fuel air mixture;

- moving an auxiliary piston from a first position toward a second position within an auxiliary cylinder in fluid communication with the combustion chamber according to the ignition method described above.

- powering the reciprocating piston in a down stroke from the top dead centre to the bottom dead centre due to expansion of high pressure combustion gasses in a combustion chamber;

- moving the auxiliary piston from the second position to the first position according to the ignition method described above;

- exhausting combustion gasses from the cylinder and introducing a fuel air mixture into the cylinder at the end of the down stroke and beginning of the up stroke; and wherein the method further comprises:

- holding the auxiliary piston at the first position according to the ignition method described above.

[0072] In some examples, the method of operating an internal combustion engine further comprises increasing an effective compression ratio in the combustion chamber by selectively moving the auxiliary piston from the first position toward the second position within the auxiliary cylinder.

[0073] In the method of operating the internal combustion engine, the auxiliary cylinder and a head of the auxiliary piston may define an auxiliary chamber which opens into the combustion chamber of the main cylinder. Movement of the auxiliary piston from the first position toward the second position may increase a pressure within the combustion chamber and/or the auxiliary chamber to cause combustion of a compressed fuel air mixture. The auxiliary chamber may be a pre-chamber or a pre-combustion chamber. Combustion of the fuel air mixture may begin in the auxiliary chamber. The auxiliary chamber may include a glow plug or a spark plug. [0074] In the method of operating the internal combustion engine, the internal combustion engine may include at least one additional chamber provided at a position intermediate the auxiliary cylinder and the main cylinder.

[0075] In some examples, the ignition system and the method of operating an internal combustion engine is for an internal combustion engine that is a rotary engine.

[0076] It is to be appreciated that the above described method may be controlled by a computer. Accordingly, there is also disclosed software that when installed on a computer causes the computer to implement the method described above.

Brief Description of Drawings

[0077] Fig. 1 illustrates a cross section of a simplified internal combustion engine having an ignition system;

[0078] Figs. 2 illustrates a sequence of a four-stroke cycle of an engine;

[0079] Figs. 3 illustrates a sequence in the internal combustion engine including the ignition system performing the disclosed ignition method;

[0080] Fig. 4 is a flow diagram of the method performed by the ignition system;

[0081] Fig. 5 is a flow diagram of the method performed by a four-stroke internal combustion engine;

[0082] Figs. 6a to 6c illustrates a sequence of a two-stroke cycle of an engine; [0083] Fig. 7 illustrates a side view of a rotary engine;

[0084] Fig. 8 illustrates a cross section of a simplified internal combustion engine having an ignition system;

[0085] Fig. 9 illustrates a cross section of the internal combustion engine of Fig. 8 with the cylinder at top dead centre;

[0086] Figs. 10a to lOe illustrate a sequence in the internal combustion engine including the ignition system performing the disclosed ignition method; [0087] Fig. 11 is a flow diagram of the method performed by the ignition system;

[0088] Fig. 12 is a flow diagram of the method performed by a four-stroke internal combustion engine;

[0089] Figs. 13a to 13d illustrate an ignition system having an alternative retaining mechanism, with the auxiliary piston in the first position;

[0090] Fig. 13a is a plan view of the ignition system;

[0091] Fig. 13b is a side view of the ignition system ;

[0092] Fig. 13c is an illustration of the ignition system when viewed in the direction indicated by arrow L in Fig. 13b ;

[0093] Fig. 13d is an illustration of the ignition system when viewed in the direction indicated by arrow R in Fig. 13b.

[0094] Figs. 14a to 14d illustrate the ignition system of Fig. 13 with the auxiliary piston at a position close to the second position.

[0095] Fig. 14a is a plan view of the ignition system;

[0096] Fig. 14b is a side view of the ignition system;

[0097] Fig. 14c is an illustration of the ignition system when viewed in the direction indicated by arrow L in Fig. 14b;

[0098] Fig. 14d is an illustration of the ignition system when viewed in the direction indicated by arrow R in Fig. 14b;

[0099] Figs. 15a to 15d illustrate the ignition system of Fig. 13 with the auxiliary piston in the first position;

[0100] Fig. 15a is a plan view of the ignition system; [0101] Fig. 15b is a side view of the ignition system;

[0102] Fig. 15c is an illustration of the ignition system when viewed in the direction indicated by arrow L in Fig. 15b;

[0103] Fig. 15d is an illustration of the ignition system when viewed in the direction indicated by arrow R in Fig. 15b; [0104] Fig. 16 shows a schematic cross section of a simplified internal combustion engine having an ignition system;

[0105] Figs. 17a to 17c illustrates a sequence of a two-stroke cycle of an engine; [0106] Fig. 18 illustrates a side view of a rotary engine;

[0107] Figs. 19a to 19d illustrate an alternative ignition system with an adjustment system in various configurations;

[0108] Figs. 20a and 20b illustrate partially sectioned perspective views of the ignition system of Fig. 19a; and

[0109] Fig. 21 is a schematic of an example processing device. Description of Embodiments

Overview of a first example of an ignition system

[0110] Fig. 1 shows an example of an internal combustion engine (3) that includes an engine block (16) that defines cylinder walls of a cylinder (17). A reciprocating piston (15) is provided inside the cylinder (17), where the piston (15) and cylinder (17) defines a combustion chamber (5). A crankshaft (18) is driven by the reciprocating piston (15) via a connecting rod (20) to convert linear reciprocating motion to rotational motion. The crankshaft (18) provides an output that may be transmitted along the power train. In some examples, this may include driving a transmission, which in turn via other components such as a driveshaft, drives wheels of a vehicle.

[0111] The internal combustion engine (3) also includes an ignition system (1) having a reservoir (7) that can store high pressure and high temperature combustion gasses (9). A combustion gas valve (11) is selectively operable to provide fluid communication between the reservoir (7) and the combustion chamber (5). This operation to provide fluid communication includes two purposes. Firstly, selectively opening the combustion gas valve (11) allows high pressure and high temperature combustion gasses (9) from the combustion chamber (5) during combustion to be received, and subsequently stored, by the reservoir (7). Secondly, selectively opening the combustion gas valve (11) allows the high pressure and high temperature combustion gasses (9) to be injected back into the combustion chamber (5). Before injection, the high pressure combustion gasses (9) in the reservoir (7) are at a higher pressure than the compressed fuel air mixture (13). The high temperature combustion gasses (9) elevate the pressure and temperature of a combustible mixture (14) inside the combustion chamber (5) to above an auto ignition temperature to cause combustion. The combustible mixture (14) may include a fuel air mixture (13) that was compressed in the combustion chamber (5) as well as the high temperature combustion gasses (9) injected from the reservoir (7).

[0112] The reservoir (7) may store the high pressure and temperature combustion gasses (9) when the piston (15) and cylinder (17) are at other cycles. For example, in a four-stroke engine this may include holding the combustion gasses (9) substantially during an exhaust stroke, intake stroke and compression stroke of the engine.

[0113] By selective operation of the combustion gas valve (11), this may allow control of the autoignition of the combustible mixture (14) in the combustion chamber (5). By manipulating operation of the combustion gas valve (11), this may also allow some variation, such as leading, or lagging the autoignition point during the piston's (15) reciprocating cycle which may be useful for better fuel efficiency, power, emissions, for various engine speeds and loads. Advantageously, this may prevent, or reduce the instances, of autoignition occurring prematurely in the combustion chamber (5). This may also increase reliable autoignition in the combustion chamber (5).

[0114] Selective operation of the combustion gas valve (11) may allow control of the pressure in the combustion chamber (5) at, or just before, combustion. In particular, controlling the injection of high pressure combustion gasses (9) may allow manipulation of the pressure in the combustion chamber (5) to provide an "effective compression ratio" that is higher than a compression ratio solely from the movement of the piston (15).

[0115] Selective operation of the combustion gas valve (11) may also allow control of pressure in the combustion chamber (5) during the power stroke. Selective operation of the combustion gas valve (11) may allow control of the amount of combustion gasses (9) received in the reservoir (7) which in turn can reduce the pressure in the combustion chamber (5). This may be used to reduce peak pressure spikes, which in turn may enable higher forced induction (e.g. turbo, supercharger) boost pressure whilst achieving manageable peak cylinder pressures. [0116] An example of the internal combustion engine (3) and the ignition system (1) will be described in detail with reference to Fig. 1.

Description of the engine

[0117] The internal combustion engine (3) includes an intake (31) and an exhaust (33). The intake (31) may include one or more valves, such as poppet valves, that open and close to allow air or a fuel air mixture (13) to be introduced into the cylinder (17). The exhaust (33) may also include one or more valves that open and close to allow combustion gasses to be exhausted from the cylinder (17). In some examples, the valves may be operated by a series of cams on a camshaft that is operatively timed with the piston's (15) reciprocating cycle. In some examples, the valve timing and valve lift may be variable depending on engine conditions, loads, etc. to achieve desired efficiency, power, and/or emission requirements. In other examples, the valves may be operated by rocker arms. It is to be appreciated that other intake and exhaust types could be used, such as side ports.

[0118] In some examples, the inlet (31) introduces air and the fuel is directly injected into the combustion chamber (5).

[0119] The engine (3) may use the ignition system (1) described herein to cause combustion in the combustion chamber (5) during particular times, whilst an alternative ignition system (or method) may be used to cause ignition at other times. For example, the ignition system (1) may cause autoignition during normal operating conditions, whilst an alternative ignition system may operate during when starting and warm up. For example, an alternative ignition system may include a spark plug (or glow plug, etc.) to assist ignition of the fuel air mixture (13) for a number of reciprocation cycles so that high pressure and high temperature combustion gasses (9) can be received and accumulated in the reservoir (7). Once sufficient high pressure and high temperature combustion gasses (9) are stored in the reservoir (7), and/or when the engine has warmed up, the engine (3) may then switch to using the ignition system (1) as the main ignition mechanism. Furthermore the engine may have different operating modes, such as a maximum efficiency mode and a maximum power mode, whereby the engine may switch from using the ignition system (1) to cause combustion or using alternative ignition systems such as a spark plug. [0120] Fig. 1 illustrates a single piston (15) of the engine (3). However, it is to be appreciated that the engine (3) may have more than one cylinder (17) and piston (5) combination. For example, the engine (3) may have two cylinders, four cylinders, five cylinders, six cylinders, eight cylinders, ten cylinders, twelve cylinders, etc. It is to be appreciated that the ignition system (1) may be used in different configurations of engines (3), such as inline cylinders, "V" configuration cylinders, flat configuration (boxer configuration), "W" configuration engine, radial engines, etc.

Description of the ignition system including the controller

[0121] The ignition system (1) may further include one or more actuators (21) to open and close the combustion gas valve (11). In some examples, the actuators may be

electromechanical actuators. In one example, the combustion gas valve (11) and actuators (21) may include a solenoid valve system. In yet other examples, the actuators (21) may be mechanically operated via a cam system. In some examples, this may be a variable cam system, similar to cam systems that operate known inlet and exhaust valves. In further examples, the actuators (21) may include hydraulic and/or pneumatic systems.

[0122] The combustion gas valves (11) may provide a fluid path to the combustion chamber (5) with one or more apertures. These apertures may be of a constricted size (and may include a venturi) such that as the high pressure and high temperature combustion gasses (9) are injected into the combustion chamber (5) at high velocity. In some examples, this may include injecting the high pressure and high temperature combustion gasses (9) into the combustion chamber (5) above the speed of sound inside the combustion chamber (5).

[0123] The ignition system (1) may also include one or more sensors (27) that provide sensor signals (29) indicative of conditions or states of the engine (3) and/or environment. This may include one or more of:

- position of a piston (15) in the cylinder (17) (which may include a sensor that provides an output based on the crank angle);

- velocity of a piston (15) in the cylinder (17);

- engine temperature; - temperature of the fuel air mixture at the intake (31);

- ambient temperature;

- engine speed;

- engine load;

- fuel quality;

- fuel quantity in the fuel air mixture;

- air quality of the surrounding environment;

- air quantity in the fuel air mixture;

- fuel versus air ratio in the fuel air mixture;

- compression ratio of the engine;

- desired pressure of the compressed fuel air mixture;

- temperature of the high pressure and high temperature combustion gasses (9) in the reservoir (7);

- pressure of the high pressure and high temperature combustion gasses (9) in the reservoir (7);

- quality of the combustion gasses at the exhaust; and

- temperature of the combustion gasses at the exhaust.

[0124] The sensor signals (29) may be received by a controller (23) that in turn determines desirable combustion gas valve (11) timing. In turn, the controller (23) provides a control signal (25) to the actuator (21) to selectively open and close the combustion gas valve (11). The controller may include a processing device to assist control and timing of the combustion gas valve (11) and implement the method (100) described in further detail below.

[0125] The reservoir (7) may be a pressure vessel that is part of a head of the engine (3). In some alternatives, the reservoir (7) may be separate to the head of the engine (3). The reservoir (7) is constructed to withstand the high pressure and high temperature of the combustion gasses (9), which may be in the order of 60 bar (~6000kPa) for a normally aspirated engine. However in some examples, such as HCCI type engines, this may be at 120 bar (-12000 kPa). The combustion gasses (9) may be around 800 to 900°C. The reservoir (7) may be constructed of a metal or metal alloy, including steel, iron, aluminium alloy, etc.

[0126] The reservoir (7) may be configured with a sufficient volume to store sufficient high pressure and high temperature combustion gasses (9) such that a required pressure and temperature is maintained. In particular, the volume should be sufficient so that when the combustion gas valve (11) is open, the injected combustion gasses (9) has sufficient pressure and temperature to raise the temperature of the combustible gasses (14) in the combustion chamber(5) by around an additional 200°C. In some examples, the reservoir (7) has a volume around the same size as the combustion chamber (5).

[0127] In some examples, the engine may have multiple cylinders (17) and respective pistons (15). In some examples, each cylinder (17) may have a respective reservoir (7) so that the high pressure and high temperature combustion gasses (9) of one cylinder (17) is stored and used to ignite a subsequent power stroke for that cylinder (17). However, it is to be appreciated that in multi-cylinder engines (3), two or more cylinders (17) may share a common reservoir (7). In some examples, this may be advantageous as the high pressure and high temperature combustion gasses (9) may be stored in the reservoir (7) for a shorter period of time since multiple cylinder engines usually have a staggered cycle for each cylinder. The shorter period of storage may assist in retaining the high temperature of the combustion gasses (9) that may result in more effective and/or reliable ignition of the combustible mixture (14).

[0128] For example, in a four cylinder engine with a first, second, third and fourth cylinders, the combustion gasses (9) received from the first cylinder may be stored in the reservoir (7) and subsequently injected into the second cylinder to cause combustion. The combustion gasses (9) received from the second cylinder may be stored in the reservoir (7) and subsequently injected into the third cylinder and so on for the other cylinders.

[0129] It is to be appreciated that the engine (3) may use one or more types of fuels depending on engineering choice. In one example, petroleum (gasoline) may be used in the engine (3). The autoignition temperature of petrol is around 246°C to 280°C (depending on octane). Accordingly, a compression ratio for the piston (15) and cylinder (17) should be selected so that (rapid) compression of the fuel air mixture (13) during engine operation conditions does not elevate the fuel air mixture (13) above the expected autoignition temperature, but injection of the high pressure and high temperature combustion gasses (9) will increase the temperature to above the autoignition temperature. An example of a compression ratio for petrol is around 10.5:1.

[0130] It is to be appreciated that the engine (3) and ignition system (1) can be designed for use with other fuels depending on the characteristics of that fuel. For example diesel fuel has a lower autoignition temperature of around 210°C and therefore the engine design should be adjusted accordingly.

Four-stroke cycle

[0131] The example engine (3) may operate on a four-stroke cycle for each piston (15). The four-stroke cycle, in general, includes: a power stroke, exhaust stroke, intake stroke and compression stroke. This is illustrated in the sequence of Figs. 2a to 2d. The ignition system (1) has not been illustrated in Figs. 2a to 2d for simplicity but it is to be appreciated that the ignition system (1) is to be included with the engine as shown in Figs. 1 and 3.

[0132] Fig. 2a illustrates a power stroke (115) whereby the piston (15) moves from the top dead centre to a bottom dead centre in the cylinder (17) due to expansion of high pressure and high temperature combustion gasses (9) in the combustion chamber (5). The power stroke normally occurs soon after ignition of the fuel air mixture (13) in the cylinder (the method of ignition will be described in further detail below). As combustion may not occur at an instantaneous moment, at least part of the fuel air mixture (13) may burn throughout the initial portion of the power stroke. During the power stroke, valves of the intake (31) and the exhaust (33) are normally closed to prevent the combustion gasses (9) from escaping from the combustion chamber (5).

[0133] Fig. 2b illustrates an exhaust stroke (125) whereby the piston (15) moves from the bottom dead centre to the top dead centre in the cylinder (17) to remove remaining combustion gasses (22) from the cylinder (17). The valves of the exhaust (33) open during the exhaust stroke so that as the piston (15) moves towards top dead centre, the remaining combustion gasses (22) are pushed out of the cylinder (17). The valves of the intake (31) remain closed substantially during the exhaust stroke (125). However it is to be appreciated that in some engines the opening of the intake and exhaust valves can overlap (e.g. the intake valve may open just before the exhaust has closed fully).

[0134] Fig. 2c illustrates an intake stroke whereby the piston (15) moves from the top dead centre to the bottom dead centre. The valves of the intake (31) open during the intake stroke so that as the piston (15) moves towards the bottom dead centre, air is introduced (101) into the cylinder (17) via the intake (31). In some particular examples, the intake supplies a fuel air mixture (13) to be introduced into the cylinder (17). The fuel air mixture (13) may contain various ratios of fuel and air. In some examples, the ratio of fuel and air may be determined by the throttle input and/or the desired output of the engine (3). The valves of the exhaust (33) are closed so the exhausted gasses are not sucked back into the cylinder.

[0135] Fig. 2d illustrates a compression stroke whereby the piston (15) moves from the bottom dead centre to the top dead centre to compress (103) the fuel air mixture in the cylinder (17). The valves of the intake (31) and exhaust (33) are closed so that the fuel air mixture (13) can be rapidly compressed to a higher pressure which causes an elevation in temperature. The result of this is that as the piston (15) is towards the top dead centre, the combustion chamber (5) contains the compressed fuel air mixture (13) that is at a high temperature and ready for ignition. However, it is preferable that the fuel air mixture (13) is below the autoignition temperature of the fuel air mixture (13), and even more preferably the engine (3) may be configured so that there is a safety margin (i.e. buffer) between the high temperature of the compressed fuel air mixture (13) and the even higher temperature for autoignition. This safety margin may prevent or reduce the risk of unwanted premature combustion in the combustion chamber (5). [0136] Ignition of the fuel air mixture (13) is controlled by the ignition system (1) as will be described in further detailed below. Ignition of the fuel air mixture (13) typically occurs around where the piston (15) is at top dead centre between the compression stroke (as shown in Fig. 2d and the power stroke (as shown in Fig. 2a). In some examples, ignition is at the top dead centre although having ignition occur slightly before (i.e. leading) and/or slightly after (i.e. lagging) may be desirable depending on factors such as operating conditions, engine load, engine speed, emission requirements, etc.

[0137] How the ignition system (1) operates to cause ignition will now be describe with reference to Figs. 3 and 4. This generally occurs during and between the compression and power strokes.

Method of operation of the ignition system

[0138] Fig. 3a illustrates the piston (15) moving up during the compression stroke. The combustion gas valve (11) remains closed to store and maintain the high pressure and high temperature combustion gasses (9) that were received during a previous power stroke. The valves of the intake (31) and exhaust (33) remain closed for the sequence between Figs. 3a to 3e. A flow chart of this method 100 performed by the ignition system (1) is illustrated in Fig. 4 and the method 200 performed by the engine (3), including the ignition system (1), is shown in Fig. 5.

[0139] Fig. 3b illustrates the piston (15) as is nearing the end of the compression stroke and approaching top dead centre. The combustion gas valve (11) remains closed. At this time, the fuel air mixture (13) is compressed, thereby having a higher pressure and higher temperature (but with a temperature below autoignition temperature). In some examples, such as an engine (3) with a compression ratio of around 10: 1, this may include a compressed fuel air mixture (13) that is at around 10 bar (1000 kPa) and at around 240°C.

[0140] Fig. 3c illustrates the piston (15) around top dead centre and with the ignition system (1) operating to initiate ignition and combustion. The combustion gas valve (11) is selectively opened to provide a fluid passage for the high pressure and high temperature combustion gasses (9) in the reservoir (7) to be injected into the combustion chamber (5) as shown as step 110 in Figs. 4 and 5. It is to be appreciated that initially, the combustion gasses (9) in the reservoir (7) is at a higher pressure than the compressed fuel air mixture (13) in the combustion chamber (5). This pressure differential assists in the flow of the high pressure and high temperature combustion gasses (9) to flow into the combustion chamber (5) to mix with the fuel air mixture (13). The mixture of combustion gasses (9) and compressed fuel air mixture (13) forms a combustible mixture (14).

[0141] The combustion gasses (9) are of a high temperature and higher than the temperature of the compressed fuel air mixture (13) in Fig. 3b. The resultant combustible mixture (14) would therefore have a temperature that is between the two. The ignition system (1) aims to have this temperature of the resultant combustible mixture (14) to be above the autoignition temperature so that it causes combustion of the combustible mixture (14).

[0142] In some examples, the high pressure and high temperature combustion gasses (9) that wast stored in the reservoir (7) may be around 600°C or higher and with a pressure of at least 20 bar (-2000 kPa). When the high pressure and high temperature combustion gasses (9) are injected into the combustion chamber (5), there will be some temperature and pressure drop. However the reservoir (7) and the ignition system (1) is preferably designed so that as a result of the injection, the temperature of the combustible gasses (14) is above 300°C and preferably closer to 400°C. This will allow reliable ignition of the fuel air mixture, which may have an autoignition temperature around 300°C (depending on the octane level).

[0143] It is to be appreciated that in some examples, it the localised temperature and/or pressure at different parts of the combustion chamber (5) may vary. For example, the part of the combustion chamber (5) proximal to an aperture of the combustion gas valve (11) may experience a temperature and/or pressure spike that is high enough to initiate ignition of the compressed fuel air mixture (13) in that area of the combustion chamber (5). This will result in combustion that will then propagate to other areas of the combustion chamber (5).

Therefore, combustion of the combustible mixture (14) described above may, in some examples, relate to combustion of the combustible mixture (14) at a localised area of the combustion chamber (5) as opposed to a uniform mixture throughout the combustion chamber (5) that combusts instantaneously.

[0144] The timing of opening the combustion gas valve (11) may be varied so that ignition of the combustible mixture (14) occurs at a desired time. It is to be appreciated that there may be some latency for the combustible mixture (14) to burn (and for the high pressure combustion gasses (9)). Therefore in some situations, it may be desirable for the ignition system (1) to open the combustion gas valve (11) earlier (i.e. lead) and before top dead centre to account for the latency. It is to be appreciated that in other circumstances, it may be desirable to delay (i.e. lag) opening of the combustion gas valve (11).

[0145] The variation of the timing of the combustion gas valve (11) may be controlled by the controller (23) that provides a control signal (25) to the actuator (21) that opens and closes the combustion gas valve (11). The controller may determine the timing based on receiving sensor signals (29) from one or more sensors (27) that measure conditions and parameters relevant to the operation of the engine (3) as described above. This includes varying the timing to achieve a desired pressure of the combustible mixture (14) in the combustion chamber (5) prior to and/or during combustion. This may affect an "effective compression ratio" in the combustion chamber (5) that may achieve higher efficiency and/or power output.

[0146] Fig. 3d illustrates the piston (15) moving from the top dead centre towards the bottom dead centre during the power stroke. The combustion gas valve (11) remains open so that the reservoir (7) may receive new high pressure and high temperature combustion gasses (9) from the combustible mixture (14) that was ignited. This recharges the reservoir (7) for ignition during the next power stroke and is shown as step 120 in Figs. 4 and 5.

[0147] Fig. 3e. illustrates the piston (15) that moving during the power stroke but with the combustion gas valve (11) closed. This occurs when there is sufficient high pressure and high temperature combustion gasses (9) in the reservoir (7) and so that the remaining combustion gasses (22) in the combustion chamber (5) can be used to power the piston (15) in the power stroke.

[0148] The timing to close the combustion gas valve (11) may be dependent on a number of factors and controlled by the controller (23). For example, on a cold start or conditions the combustion gas valve (11) timing may be adjusted to maximise the amount of high pressure and high temperature combustion gasses (9) entering the reservoir (7). On the other hand, when the engine is operating at higher temperature conditions, the requirement for high pressure and high temperature combustion gasses (9) may be less and the timing of the combustion gas valve (11) may be closed relatively earlier so less combustion gasses (9) enter the reservoir (7). In another example, the timing of the combustion gas valve (11) may be based, at least in part, on the throttle setting of the engine (3). At high throttle settings, more combustion gasses (9) may be produced in each cylinder 17 so that a shorter timing is required, whereas at lower throttle settings the combustion gas valve (11) may be open for longer to allow more combustion gasses (9) into the reservoir (7).

[0149] Once the combustion gas valve (11) is closed, the high pressure and high temperature combustion gasses (9) are then stored (130) in the reservoir (7) until the next requirement for ignition. This may include storing the combustion gasses (9) during the exhaust stroke, intake stroke, and compression stroke of the piston (15). In cases where a reservoir (7) may be shared with multiple cylinders (17) and pistons (15) the reservoir (7) may store the combustion gasses (9) until the next cylinder and piston in the engine (3) requires ignition.

[0150] It is to be appreciated that the selective operation of combustion gas valve (11), as well as other parts of the ignition system (1) and engine (3) may be controlled by the controller (23). Therefore these methods described herein may include computer

implemented methods to achieve the above disclosure.

Variations

Multiple valve operations

[0151] In the above example, the combustion gas valve (11) is selectively opened to inject the combustion gasses (9) and held open so that combustion gasses (9) (from the ignited fuel air mixture) can then be received at the reservoir (7). However, in some alternatives the combustion gas valve (11) may be selectively opened and closed multiple times.

[0152] For example, the combustion gas valve (11) may be briefly opened to inject the combustion gasses (9) into the combustion chamber (5) and then closed. The injected combustion gasses (9) cause combustion of the fuel air mixture (13) in the combustion chamber (5). For a brief time period, the combustion gas valve (11) as well as the intake (31) and exhaust (33) may also have valves that are closed. This may allow the maximum amount of power from the expanding combustion gasses (9) to drive the piston (15) in the power stroke. Subsequently in the power stroke, the combustion gas valves (11) may then be selectively opened to allow some of the high pressure and high temperature combustion gasses (9) to be received at the reservoir (7) and then subsequently closed again to store the combustion gasses (9) in the reservoir (7).

[0153] In yet further examples, the combustion gas valve (11) may open to various states. For example, the combustion gas valve (11) may have a wide open setting to allow maximum flow between the reservoir (7) and the combustion chamber (5) and a narrow open setting to have restricted flow between the reservoir (7) and the combustion chamber (5). It is to be appreciated that variable opening states may be used to alter the flow and achieve different characteristics. In one example, when injecting high pressure and high temperature gases from the reservoir (7) to the combustion chamber (5) a narrow open setting may be used to have higher velocity of gasses to be injected. In another example, when receiving high pressure and high temperature gasses (9) from the combustion chamber (5) a wide open setting may be used to maximise the amount of gasses received in the reservoir (7) and/or to quickly lower the peak pressure in the combustion chamber (5).

Varying an effective compression ratios

[0154] In some examples, the timing of combustion gas valve (11) opening and/or opening at different states may be used to manipulate the pressure in the combustion chamber (5) at, or just before, combustion.

[0155] As an illustrative example, say an engine (3) has a standard compression ratio of 10: 1 when the piston (15) reaches top dead centre on the combustion stroke. The pressure of the fuel air mixture (13) in the combustion chamber (5) will then be around 10 bar (-1000 kPa). Furthermore, say the reservoir (7) has a volume approximately the same as the combustion chamber (5) when the piston (15) is at top dead centre, and the high pressure and temperature combustion gasses (9) in the reservoir (7) is at 20 bar (~2000kPa). When the combustion gas valve (11) is opened, and the combustion gasses (9) are injected into the combustion chamber (5), this will result in (before combustion) pressure in the combustion chamber (5) to be around 15 bar (~1500kPa). That is, providing an effective compression ratio of around 15: 1.

[0156] Say in another illustrative example, the standard compression ratio is also 10: 1. However, when the engine (3) is operating at a higher throttle the resultant pressure of high pressure and high temperature combustion gasses (9) in the reservoir (7) is at 60 bar (-6000 kPa) which may be close to the maximum cylinder pressure. When the combustion gas valve (11) is opened, this may result in the pressure in the combustion chamber (5) before combustion to be around 35 bar (~3500kPa) and therefore an effective compression ratio of around 35: 1.

[0157] It is to be appreciated that the volume and pressures in the reservoir (7) may be selected and the combustion gas valve (11) selectively operated to achieve various desired effective compression ratios. This may include operating the combustion gas valve (11) when receiving combustion gasses (9) to control the pressure of combustion gasses (9) in the reservoir (7).

[0158] There may be various ways to increase power output of the engine (3) compared to known engines. In one illustrative example, there is a four cylinder engine with each cylinder having a bore of 100mm. When operated in a conventional mode (i.e. without the ignition system (1)), the peak pressure in each combustion chamber (5) may be around 60 bar (~6000kPa). To increase the output of such an engine, this may include:

(i) increasing the number of times per minute the four pistons achieve 60 bar. This may include providing an engine that can operate at higher revolutions per minute.

(ii) increasing the maximum pressure in each cylinder during combustion which would increase the energy on the power strokes. This may be achieved by providing a homogenous charge system that may operate at higher maximum pressures, such as 120 bar (-12000 kPa). This will require an engine (3) having strengthened components.

(iii) increasing the starting compression ratio from 10 bar (~1000kPa) to an effective compression ratio of 20 bar (~2000kPa) as described in the example above. This may increase the effective final maximum pressure in the combustion chamber (5) during combustion to provide more energy in the power strokes. In some examples, this may increase the effective maximum pressure in the combustion chamber (5) by 10 bar

(~1000kPa). This may allow some increase in power in the engine (3) without requiring substantial strengthening of the engine (3). (iv) various combinations of the above. Reducing pressure spikes in the combustion chamber

[0159] Operation of the combustion gas valves (11) may also be used to control or regulate the peak pressures in the combustion chamber (5). In one illustrative example, say the combustion chamber (5) operates with a peak pressure of 60 bar (~6000kPa) using known ignition systems (i.e. not the ignition system (1)). If the ignition system (1) was then introduced and the reservoir (7) is approximately the same size as the combustion chamber (5), then the resultant peak pressure may have halved. This may be achieved by opening the combustion gas valve (11) to allow the high pressure combustion gasses (9) to be spread out to the two volumes.

[0160] It is to be appreciated that in some practical examples, this may not be exactly half and may depend on other factors such as the time the combustion gas valve (11) is open, the apertures of the valve (11), etc. It is also appreciated that in other examples the reservoir (7) may be other sizes.

[0161] This may be useful for engines (3) operating homogenous charge principles as the designed pressure rating may be reduced (and therefore reduce costs and complexity). For example, say a homogenous charge engine can expect a peak pressure of 120 bar (12000 kPa) in the combustion chamber (5). By implementing the ignition system (1) that has the combustion gas valve (11), this may be operable to allow some of the combustion gasses (9) to escape the combustion chamber (5) (and into the reservoir (7)) so that the peak pressure is less than 120 bar. In one example, if the combustion gas valve (11) is held open long enough during the power stroke and the reservoir (7) is around the same volume as the combustion chamber (5) this may even halve the maximum pressure to 60 bar (-6000 kPa). Accordingly, an engine (3) using this ignition system (1) may be constructed with a lower maximum pressure requirement that may reduce complexity, materials and costs.

[0162] In some examples, this may also be applied to forced induction engines where the peak pressure in the combustion chamber (5) is typically higher than a normally aspirated engine. [0163] It is to be appreciated that peak pressure, peak torque, and volume of gas(es) at a given pressure in an engine are interrelated and therefore having an ignition system (1) including a controller (23) that selectively controls the combustion gas valve (11) may allow this to be varied depending on the desired results (e.g. maximum efficiency, maximum power, etc.).

Two stroke cycle

[0164] In some variations, the ignition system (1) may be adapted for use with an engine (3) operating on a two-stroke cycle as illustrated in Figs. 6a to 6c.

[0165] In the down stroke, as shown in Fig. 6a, the piston (15) move from the top dead centre to the bottom dead centre due to expansion of high pressure combustion gasses (9) in the combustion chamber (5).

[0166] Around the bottom dead centre, as shown in Fig. 6b, the piston (15) has moved in the cylinder (17) such that the intake port (31) and the exhaust port (33) are open. This allows introduction of a fuel air mixture (13) into the cylinder (17) and exhausting of combustion gasses from the cylinder (17) as shown in Fig. 6b.

[0167] A subsequent up stroke, as shown in Fig. 6b, includes moving the cylinder (15) from the bottom dead centre to the top dead centre thereby compressing the fuel air mixture (13).

[0168] The two-stroke cycle engine (3) may use an adaptation of the ignition system (1) and method (100) (such as that described with reference to Figs. 3a to 3e) between the end of the up stroke (Fig. 6c) and the beginning of the down stroke (Fig. 6a).

[0169] In particular, as the piston (15) is approaching or at top dead centre, the ignition system (1) may inject, from the reservoir (7), high pressure and high temperature combustion gasses (9) into the combustion chamber (5) to elevate the combustible mixture (14) therein to above an autoignition temperature. This is done by opening the combustion gas valve (11) as shown in Fig. 3c. [0170] As the combustible mixture (14) undergoes combustion to power the piston (15) during a down stroke, the high pressure and high temperature combustion gasses are received from the combustion chamber (5) and into the reservoir (7) as shown in Fig. 3d.

[0171] Subsequently, the combustion gas valve (11) is closed so that the combustion gasses (9) in the reservoir (7) are stored for subsequent ignition as shown in Fig. 3e. This also allows the remaining combustion gasses in the combustion chamber (5) to expand and drive the piston (15) down through the rest of the down stroke.

Rotary engine

[0172] It is to be appreciate that the ignition system (1) may be adapted to operate in other types of internal combustion engines, such as rotary engines (43). A rotary engine (also called "wankel engine" after the inventor Felix Wankel), includes an epitrochoid- shaped housing within which a rotor (47) (having a triangle-like shape) that moves to drive an eccentric shaft (49) as shown in Fig. 7. The combustion chambers (51, 53, 55) are formed in the space between the sides of the triangle-like rotor (47) and the epitrochoid- shaped housing 45. The apexes of the rotor maintain contact with the walls of the epitrochoid- shaped housing throughout rotation. Typically for a single rotor engine, there are three combustion chambers that move as the rotor moves (which will be at different stages of intake, compression, power and exhaust of the combustion chamber). In some examples, a rotary engine may have more than one rotor, each enclosed in a respective epitrochoid- shaped housing.

[0173] Rotary engines, like reciprocating internal combustions engines described above, require an ignition system to ignite compressed fuel air mixture. In conventional rotary engines, this may include providing a spark plug to ignite the compressed fuel air mixture.

[0174] It is to be appreciated that the ignition system (1) described above could be used to inject high pressure and high temperature combustion gasses (9) to cause combustion of the compressed fuel air mixture in a rotary engine. This may include providing the combustion gas valve(s) (11) that open to selectively inject the high pressure and high temperature gasses (9) into the combustion chamber, and having the same combustion gas valve (11) or another combustion gas valve (11) open to allow high pressure and high temperature gasses (9) to be received at the reservoir (7). It is to be appreciated that some examples may have two or more combustion gas valves (11a, 1 lb) as shown in Fig. 7. This may assist in receiving the high pressure and high temperature gasses (9) since the combustion chambers (51, 53, 55) moves as the rotor moves. That is, a first combustion gas valve (11a) may predominately function to "inject" and another combustion gas valve (l ib) may predominately function to "receive" (when the rotor 47 rotates in a clockwise direction in Fig. 7).

Overview of a second example of an ignition system with an auxiliary piston

[0175] Figs. 8 and 9 shows an example of an internal combustion engine (403) that includes an engine block (16) that defines cylinder walls of a main cylinder (17). Components of the internal combustion engine (403) that are similar, or the same, as the earlier example of the internal combustion engine (3) have been given the same reference numerals.

[0176] The internal combustion engine (403) also includes an ignition system (401) having an auxiliary cylinder (58) in fluid communication with the combustion chamber (5). An auxiliary piston (60) is provided inside the auxiliary cylinder (58) and is movable within the auxiliary cylinder (58) between a first position and a second position. In Fig. 8, the auxiliary piston (60) is shown in the first position. In Fig. 9, the auxiliary piston (60) is shown in the second position. An auxiliary chamber (61) is defined at least in part by the auxiliary cylinder (58) and the auxiliary piston (60). In this embodiment, the auxiliary chamber (61) opens into the combustion chamber (17) such that gases (such as the fuel air mixture prior to combustion and the high pressure and high temperature combustion gases resulting from combustion) within the combustion chamber move freely into the auxiliary chamber (61).

[0177] The auxiliary piston (60) includes a head (80) having a face (82) directed toward the auxiliary chamber (61) and the main chamber (17) and a shaft (84). The engine block defines the cylinder walls (86) of the auxiliary cylinder (58). In the example shown in Figs. 8 and 9, the auxiliary cylinder (58) includes a wide bore portion (88) and a narrow bore portion (90) (see Fig. 8). A collar (92) and a stop spring (94) may be provided to limit travel of the auxiliary piston (60) into the combustion chamber (5) if necessary.

[0178] The ignition system (401) also includes a biasing mechanism (62) to move the auxiliary piston (60) from the first position toward the second position. In the embodiment shown in Figs. 8 and 9, the biasing mechanism is a coil spring (72). The ignition system (401) also includes a retaining mechanism (64) to releasable hold the auxiliary piston (60) in the first position. In the embodiment shown in Figs. 8 and 9, the retaining mechanism (64) includes a projection (68). The retaining mechanism (64) is selectively operable to release the auxiliary piston (60) so that the biasing mechanism (62) moves the auxiliary piston (60) toward the second position. Movement of the auxiliary piston (60) from the first position toward the second position increases a pressure within the combustion chamber (5) to cause combustion of a compressed fuel air mixture (13) contained in the combustion chamber (5). Increasing the pressure within the combustion chamber (5) elevates the pressure and temperature of a fuel air mixture (13) in the combustion chamber (5) to above an auto ignition temperature to cause combustion.

[0179] In the embodiment shown in Figs. 8 and 9, the projection (68) is retractably extendible into the interior of the auxiliary cylinder (58) to engage the auxiliary piston (60). In this embodiment, the auxiliary piston (60) includes a corresponding recess (70) in which the projection (68) is receivable. In Fig. 8, the projection (68) is shown extended into the interior of the auxiliary cylinder (58) and engaging the auxiliary piston (60) at the recess (70) to thereby hold the auxiliary position (60) in the first position. In Fig. 9, the projection (68) is shown retracted. Retracting the projection (68) from the position shown in Fig. 8 releases the auxiliary piston (60) and permits the auxiliary piston (60) to move toward the second position due to the biasing action of the coil spring (72).

[0180] The auxiliary piston (60) is also movable from the second position toward the first position due to expansion of high pressure and high temperature combustion gasses (9), which are produced by combustion of the fuel air mixture, in the combustion chamber (5). In this case, when the auxiliary piston (60) moves to the first position, the retaining mechanism (64) is operable to hold the auxiliary piston (60) at the first position. As discussed above, in the embodiment shown in Figs. 8 and 9, operation of the retaining mechanism (64) extends the projection (68) into the auxiliary cylinder (58) when the auxiliary piston is at the first position to engage the recess (70) of the auxiliary piston (60) and to thereby hold the auxiliary piston (60) at the first position.

[0181] The retaining mechanism (64) may hold the auxiliary piston (60) in the first position when the reciprocating piston (15) and main cylinder (17) are at other cycles. For example, in a four-stroke engine this may include holding the auxiliary piston (60) substantially during an exhaust stroke, intake stroke and compression stroke of the engine.

[0182] By selective operation of the auxiliary piston (60) by means of the operation of the retaining mechanism (64), this may allow control of the autoignition of the fuel air mixture (13) in the combustion chamber (5). By manipulating operation of the auxiliary piston (60), this may also allow some variation, such as leading, or lagging the autoignition point during the reciprocating piston's (15) reciprocating cycle which may be useful for better fuel efficiency, power, emissions, for various engine speeds and loads. Advantageously, this may prevent, or reduce the instances, of autoignition occurring prematurely in the combustion chamber (5). This may also increase reliable autoignition in the combustion chamber (5).

[0183] Selective operation of the retaining mechanism (64) may allow control of the pressure in the combustion chamber (5) at, or just before, combustion. In particular, controlling the increase in pressure within the combustion chamber (5) by the selective release of the auxiliary piston (60) may allow manipulation of the pressure in the combustion chamber (5) to provide an "effective compression ratio" that is higher than a compression ratio solely from the movement of the reciprocating piston (15).

[0184] An example of the internal combustion engine (403) and the ignition system (401) will be described in detail with reference to Figs. 8 and 9.

Description of the engine according to a second example

[0185] The internal combustion engine (403) includes similar components such as intake (31) and exhaust (33) as described in the earlier example of the internal combustion engine (3) and components have the same, or similar, function are given the same reference numerals.

[0186] The engine (403) may use the ignition system (401) described herein to cause combustion in the combustion chamber (5) during particular times, whilst an alternative ignition system (or method) may be used to cause ignition at other times. For example, the ignition system (401) may cause autoignition during normal operating conditions, whilst an alternative ignition system may operate during starting and warm up. For example, an alternative ignition system may include a spark plug (or glow plug, etc.) to assist ignition of the fuel air mixture (13) for a number of reciprocation cycles so that expansion of high pressure and temperature combustion gases in the combustion chamber (5) moves the auxiliary piston (60) from the second position to the first position at which it is held by the retaining mechanism (64). Once the auxiliary piston is held at the first position by the retaining mechanism (64), and/or when the engine has warmed up, the engine (403) may then switch to using the ignition system (401) as the main ignition mechanism. Furthermore the engine may have different operating modes, such as a maximum efficiency mode and a maximum power mode, whereby the engine may switch from using the ignition system (401) to cause combustion or using alternative ignition systems such as a spark plug.

[0187] Figs. 8 and 9 illustrates a single reciprocating piston (15) of the engine (403).

However, it is to be appreciated that other variations and combinations of cylinders may be used as discussed above.

Description of the ignition system including the controller

[0188] The ignition system (401) may further include one or more actuators (421) to operate the retaining mechanism (64). In some examples, the actuators (421) may be

electromechanical actuators. In one example, the retaining mechanism (64) and actuators (421) may include a solenoid bolt or latch system. In the example shown in Figs. 8 and 9, the actuator (421) includes a solenoid (21a) to extend and retract the projection (68). In yet other examples, the actuators (421) may be mechanically operated via a cam system. In some examples, this may be a variable cam system. In further examples, the actuators (421) may include hydraulic and/or pneumatic systems.

[0189] The ignition system (401) may also include one or more sensors (27) that provide sensor signals (29) indicative of conditions or states of the engine (403) and/or environment. This may include one or more of:

- position of a reciprocating piston (15) in the main cylinder (17) (which may include a sensor that provides an output based on the crank angle);

- position of an auxiliary piston (60) in the auxiliary cylinder (58);

- velocity of a reciprocating piston (15) in the main cylinder (17);

- velocity of an auxiliary piston (60) in the auxiliary cylinder (58);

- engine temperature;

- temperature of the fuel air mixture at the intake (31);

- ambient temperature;

- engine speed;

- engine load;

- fuel quality; - fuel quantity in the fuel air mixture;

- air quality of the surrounding environment;

- air quantity in the fuel air mixture;

- fuel versus air ratio in the fuel air mixture;

- compression ratio of the engine;

- desired pressure of the compressed fuel air mixture;

- temperature of the high pressure and high temperature combustion gasses (9);

- pressure of the high pressure and high temperature combustion gasses (9);

- quality of the combustion gasses at the exhaust; and

- temperature of the combustion gasses at the exhaust.

[0190] The sensor signals (29) may be received by a controller (23) that in turn determines desirable timing for the operation of the retaining mechanism (64). In turn, the controller (23) provides a control signal (25) to the actuator (421) to selectively operate the retaining mechanism (64) to release the auxiliary piston (60) and to hold the auxiliary piston (60). The controller may include a processing device to assist control and timing of the operation of the retaining mechanism (64) and implement the method (300) described in further detail below.

[0191] The auxiliary cylinder (58) may be coaxially aligned with the main cylinder (17) and the auxiliary piston (60) may be coaxially aligned with the reciprocating piston (15) as illustrated in Figs. 8 and 9. However, other arrangements for the auxiliary cylinder (58) and the auxiliary piston (60) relative to the main cylinder (17) and the reciprocating piston (15) are possible. For example, the auxiliary cylinder may open into the main cylinder (17) at a position in the head of the cylinder off centre from the longitudinal axis of the main cylinder (17). The auxiliary cylinder may also open into the main cylinder through a side wall of the main cylinder. In such situations, the opening of the auxiliary cylinder into the main cylinder will be at a position such that fluid communication between the auxiliary cylinder and the main cylinder is maintained when the reciprocating piston is at top dead centre. In addition, as described in more detail below, an additional chamber (or chambers) may be provided between the auxiliary cylinder and the main cylinder and the auxiliary cylinder may open into that additional chamber and that additional chamber may in turn open into the main cylinder. [0192] The auxiliary cylinder (58) and auxiliary piston (60) are constructed to withstand the same environment and conditions as the other components of the engine and may be constructed from the same materials as the main cylinder (17) and the reciprocating piston (15).

[0193] When the auxiliary piston (60) is released from the first position and moves toward the second position, the combined volume of the combustion chamber (5) and the auxiliary chamber (61) is further reduced. The auxiliary cylinder (58) and the auxiliary piston (60) may be configured so that the auxiliary chamber (61) has a sufficient volume and size that the decrease in the combined volume of the auxiliary chamber (61) which is in fluid

communication with the combustion chamber (5) is sufficient to increase the pressure within the combustion chamber (5) to increase the temperature of the compressed fuel air mixture (13) in the combustion chamber(5) by around an additional 200°C. In some examples, the volume of the auxiliary chamber (61) is around the same as the volume of the combustion chamber (5).

[0194] In some examples, the engine may have multiple main cylinders (17) and respective reciprocating pistons (15). In such examples, each main cylinder (17) may have a respective auxiliary cylinder (58) and auxiliary piston (60) in order for high pressure and high temperature combustion gasses (9) to move the auxiliary piston (60) to the first position to be held by a respective retaining mechanism (64) and subsequently released to ignite a subsequent power stroke for that main cylinder (17).

[0195] It is to be appreciated that the engine (403) may use one or more types of fuels depending on engineering choice. In one example, petroleum (gasoline) may be used in the engine (403). The autoignition temperature of petrol is around 246°C to 280°C (depending on octane). Accordingly, a compression ratio for the reciprocating piston (15) and main cylinder (17) should be selected so that (rapid) compression of the fuel air mixture (13) during engine operation conditions does not elevate the fuel air mixture (13) above the expected autoignition temperature, but movement of the auxiliary piston (60) from the first position to the second position will increase pressure and increase the temperature of the fuel air mixture (13) to above the autoignition temperature. An example of a compression ratio for petrol is around 10.5: 1.

[0196] It is to be appreciated that the engine (403) and ignition system (401) can be designed for use with other fuels depending on the characteristics of that fuel. For example, diesel fuel has a lower autoignition temperature of around 210°C and therefore the engine design should be adjusted accordingly.

Method of operation of the ignition system

[0197] Fig. 10a illustrates the reciprocating piston (15) moving up during the compression stroke. The retaining mechanism (64) holds the auxiliary piston (60) at the first position. The valves of the intake (31) and exhaust (33) remain closed for the sequence between Figs. 10a to lOe. A flow chart of this method 300 performed by the ignition system (401) is illustrated in Fig. 11 and the method 400 performed by the engine (403), including the ignition system (401), is shown in Fig. 12.

[0198] Fig. 10b illustrates the reciprocating piston (15) as it is nearing the end of the compression stroke and approaching top dead centre. The retaining mechanism (64) continues to hold the auxiliary piston (60) in the first position. At this time, the fuel air mixture (13) is compressed, thereby having a higher pressure and higher temperature (but with a temperature below autoignition temperature). In some examples, such as an engine (403) with a compression ratio of around 10: 1, this may include a compressed fuel air mixture (13) that is at around 10 bar (1000 kPa) and at around 240°C.

[0199] Fig. 10c illustrates the reciprocating piston (15) around top dead centre and with the ignition system (401) operating to initiate ignition and combustion. The retaining mechanism (64) has released the auxiliary piston (60) so that the biasing mechanism (62) moves the auxiliary piston (60) toward the second position as shown as step (350) in Figs. 11 and 12. It is to be appreciated that, at this time, the biasing force of the biasing mechanism (62) on the auxiliary piston (60) is greater than the force exerted on the auxiliary piston (60) by the compressed fuel air mixture (13) in the combustion chamber (5) and the auxiliary chamber (61).

[0200] The movement of the auxiliary piston (60) from the first position toward the second position increases the pressure within the combustion chamber (5) and increases the temperature of the compressed fuel air mixture (13) to above an autoignition temperature of the fuel air mixture (13) so that it causes combustion of the fuel air mixture (13). The ignition system (401) is preferably designed so that as a result of the increase in pressure, the temperature of the fuel air mixture (13) is above 300°C and preferably closer to 400°C. This will allow reliable ignition of the fuel air mixture (13), which may have an autoignition temperature around 300°C (depending on the octane level).

[0201] The timing of the release of the auxiliary piston (60) may be varied so that ignition of the fuel air mixture (13) occurs at a desired time. It is to be appreciated that there may be some latency for the fuel air mixture (13) to burn. Therefore in some situations, it may be desirable for the ignition system (401) to release the auxiliary piston (60) earlier (i.e. lead) and before the reciprocating piston (15) is at top dead centre to account for the latency. It is to be appreciated that in other circumstances, it may be desirable to delay (i.e. lag) the release of the auxiliary piston so that the auxiliary piston (60) is released when the reciprocating piston (15) is past top dead centre (that is, after the reciprocating piston (15) has reached top dead centre and has begun the intake stroke and is moving from top dead centre toward bottom dead centre). Of course, the auxiliary piston (60) may be released when the reciprocating cylinder (15) is at dead centre.

[0202] The variation of the timing of the release of the auxiliary piston (64) may be controlled by the controller (23) that provides a control signal (25) to the actuator (421) that operates the retaining mechanism (64) to release the auxiliary piston (60). The controller (23) may determine the timing based on receiving sensor signals (29) from one or more sensors (27) that measure conditions and parameters relevant to the operation of the engine (403) as described above. This includes varying the timing to achieve a desired pressure of the fuel air mixture (13) in the combustion chamber (5) prior to and/or during combustion. This may affect an "effective compression ratio" in the combustion chamber (5) that may achieve higher efficiency and/or power output.

[0203] Fig. lOd illustrates the reciprocating piston (15) moving from the top dead centre towards the bottom dead centre during the power stroke. In the power stroke, the

reciprocating piston (15) moves from the top dead centre to a bottom dead centre in the main cylinder (17) due to expansion of high pressure and high temperature combustion gasses (9) in the combustion chamber (5). This expansion of the high pressure and high temperature combustion gasses (9) in the combustion chamber (5) also moves (360) the auxiliary piston (60) within the auxiliary cylinder (58) from the second position back to the first position. When the auxiliary piston (60) reaches the first position, the retaining mechanism (64) is operated to hold (370) the auxiliary piston (60) in the first position. This positions the auxiliary piston (60) for ignition during the next power stroke and is shown as step (370) in Figs. 11 and 12.

[0204] Fig. lOe illustrates the reciprocating piston (15) moving during the power stroke but with the auxiliary piston (60) held by the retaining mechanism (64).

[0205] The timing for the retaining mechanism (64) to begin holding the auxiliary piston (60) may be dependent on a number of factors and controlled by the controller (23).

However, once the auxiliary piston (60) has reached the first position, the retaining mechanism (64) is operated to hold the auxiliary piston (60). The timing of the operation of the retaining mechanism (64) may be controlled by the controller (23) based on a condition of the auxiliary piston (60) as determined by a sensor (27a). Such conditions may include a position of the auxiliary piston (60) in the auxiliary cylinder (58) or a velocity of the auxiliary piston (60) in the auxiliary cylinder (58).

[0206] Once the auxiliary piston (60) is held at the first position by the retaining mechanism (64), the auxiliary piston (60) is held at the first position until the next requirement for ignition. This may include holding the auxiliary piston (60) in the first position during the exhaust stroke, intake stroke, and compression stroke of the reciprocating piston (15).

[0207] It is to be appreciated that the selective operation of retaining mechanism (64) to hold and release the auxiliary piston (60), as well as other parts of the ignition system (401) and engine (403) may be controlled by the controller (23). Therefore, these methods described herein may include computer implemented methods to achieve the above disclosure.

Variations

Biasing mechanisms

[0208] In the embodiment illustrated in Figs. 8 and 9, the biasing mechanism (62) includes a coil spring (72). The coil spring (72) acts to store the energy transferred by the high pressure and high temperature combustion gases produced by the combustion of the fuel air mixture (13) in the combustion chamber (5) to the auxiliary piston (60) which moves the auxiliary piston (60) against the biasing action of the coil spring (72) from the second position to the second position. When the auxiliary piston (60) moves from the second position to the first position, the auxiliary piston (60) compresses the coil spring (72). While the auxiliary piston (60) is held in the first position by the retaining mechanism (64), the coil spring (72) remains compressed. When the retaining mechanism (64) releases the auxiliary piston (60), the coil spring (72) expands and transfers the stored energy to the auxiliary piston (60) which moves toward the combustion chamber (5) to further compresses the fuel air mixture (13) introduced into the combustion chamber (5) (and the auxiliary chamber 61)) while the auxiliary piston (60) was held at the first position by the retaining mechanism (64).

[0209] In some alternatives, the biasing mechanism (62) may comprise a gas (for example, nitrogen) held in a reservoir in fluid communication with the auxiliary cylinder such that movement of the auxiliary piston (60) from the second position to the first position compresses the gas. While the auxiliary piston (60) is held by the retaining mechanism (64) in the first position, the gas remains compressed. When the auxiliary piston (60) is released by the retaining mechanism (64), expansion of the compressed gas moves the auxiliary piston (60) from the first position toward the second position to increase pressure within the combustion chamber (5) and cause combustion of a compressed fuel air mixture (13) in the combustion chamber (5) (as described above). It will be appreciated that, in such an alternative, while the reservoir is in fluid communication with the auxiliary cylinder (58), it is separated from the main cylinder and the combustion chamber by the head of the auxiliary piston and it is not in fluid communication with the main cylinder or the combustion chamber at any time during the operation of the engine.

[0210] In the embodiment illustrated in Figs. 8 and 9, the retaining mechanism (64) includes a projection (68) which is retractably extendable into the auxiliary cylinder (58) to engage and hold the auxiliary piston (60) and the auxiliary piston (60) has a recess (70) formed in the head of the auxiliary piston for receiving the projection. The positions of the projection (68) and the recess (70) are not restricted to these positions. For example, the recess (70) may be provided in the shaft (84) of the auxiliary piston (60) and the retaining mechanism (64) and associated projection (68) may be provided at a corresponding position in the wall of the auxiliary cylinder (58). In addition, the retaining mechanism (64) may include multiple projections (68) and recesses (70) which act together to engage and hold the auxiliary piston (60) in the first position. In alternative embodiments, there is no recess provided in the auxiliary piston and the projection is extended into the interior of the auxiliary cylinder at a position to engage the face of the auxiliary piston directed toward the auxiliary chamber (61) and the combustion chamber (5). The retaining mechanism (64) may comprise other components for engaging and holding the auxiliary piston (60) in the first position. For example, the retaining mechanism may use an electromagnet to engage and hold the auxiliary piston in the first position. In such situations, at least a portion of the auxiliary piston comprises a suitable magnetic material.

An alternative retaining mechanism

[0211] Figs. 13 to 15 illustrate an alternative arrangement for the retaining mechanism (464) for holding the auxiliary piston (60) in the first position. Figs. 13 to 15 are intended to illustrate the operation of the retaining mechanism (464) and the ignition system (401) and therefore other elements of the engine are omitted while others are included to provide context. For example, Figs. 13 and 14 show the top of the reciprocating piston (15) with the wall of the main cylinder (17) partially cut away. Fig. 15 includes a part of the cylinder head (19). In the following, features already described above are indicated with the same reference numbers.

[0212] In this example, the piston shaft (84) includes two mounting pins (220) arranged on opposite sides of the piston shaft (84) (see Fig. 14a). The retaining mechanism (464) includes a pair of first arms (222), each first arm having a first end (222a) and a second end (222b). The retaining mechanism (464) also includes a pair of second arms (224), each second arm has a first end (224a) and a second end (224b). The retaining mechanism (464) also includes a forked connecting rod (226) having a generally U-shape fork (227) formed by two arms (228) and shaft (230). In this example, the curve of the U-shaped fork 227 corresponds to the curve of the shaft of the auxiliary piston (60).

[0213] With respect to one mounting pin (220) on the auxiliary piston (60), the first end (222a) of one first arm (222) is pivotably connected to that mounting pin (220). The second end (222b) of that first arm (222) is pivotably connected to one arm (228) of the connecting rod (226). In addition, the second end (222b) of that first arm (222) is pivotably connected to the second end (224b) of one second arm (224). The first end (224a) of that second arm (224) is pivotably connected to a mount (232) formed in the engine block (16) (see Fig. 15c). In this example, as can be understood from the figures, the second end (222b) of the first arm (222), the second end (224b) of the second arm (224) and the arm (228) of the connecting rod (226) pivot around the same axis A (co-axial with the length of mounting pin (220)). This arrangement of one mounting pin (220), a first arm (222), a second arm (224) and the connecting rod (228) is repeated with respect to the other mounting pin (220). [0214] This arrangement of the first arms (222), second arms (224) and the connecting rod (226) provides a toggle-like mechanism on each side of the piston shaft (84) of the auxiliary piston (60) which can be used to hold the auxiliary piston (60) in the first position and to release the auxiliary piston (60) so that the auxiliary piston (60) moves from the first position toward the second position (as described earlier).

[0215] In the embodiment shown in Figs. 9 to 11, the shaft (230) of the connecting rod (226) is arranged within a solenoid (234) which is operable to control movement of the connecting rod (226) away from the auxiliary piston (60) (in the direction indicated by arrow R in Figs. 13b and 14b) and/or toward (in the direction indicated by arrow L in Figs. 13b and 14b) the auxiliary piston (60) and thereby to hold the auxiliary piston (60) in the first position. The first arm (222) is operably connected to the solenoid (234) via the connecting rod (226).

[0216] Fig. 13 shows the auxiliary piston (60) in the first position with the coil spring (72) compressed (elements with which the coil spring (72) is associated other than the auxiliary piston (60) have been omitted). Fig. 15 also shows the auxiliary piston (60) in the first position.

[0217] In Fig. 14, the auxiliary piston is shown in the second position. The retaining mechanism (64) is not holding the auxiliary piston (60) and the auxiliary piston (60) can be acted on by the biasing mechanism (62) (in this example, the coil spring 72) or by expanding combustion gases within the combustion chamber (5) to move the auxiliary piston (60) from the second position toward the first position. As can be seen in Figs. 14a and 14b, the connecting rod (226) is in a position away from the piston shaft (84) of the auxiliary piston (60) such that the arms (228) of the fork (227) of the connecting rod (226) do not extend around the piston shaft (84). In addition, in this configuration, the axis A (around which the second end of the first arm, the second end of the second arm and the arms of the connecting rod pivot) is at a position to one side of the piston shaft (84) of the auxiliary piston (60) and toward the solenoid (234).

[0218] In Figs. 13 and 15, the retaining mechanism (464) is shown holding the auxiliary piston (60) in the first position. The connecting rod (226) is extended toward the piston shaft (84) such that the arms (228) of the fork (227) extend past a center point/line (represented by the dot CP in Fig. 13a and the dashed line CL in Fig. 13b) of the piston shaft (84) of the auxiliary piston (60). In this position, the axis A is also at a position past the centre point/line CP/CLof the piston shaft (84) relative to the position of the axis A when the auxiliary piston (60) is in the second position (see Figs. 14a and 14b). With the connecting rod (226) held in this position, the retaining mechanism (464) holds the auxiliary piston (60) in the first position. Further movement of the connecting rod (226) in the direction indicated by the arrow L in the figures is prevented by the U-shaped fork (227), the arms (228) of which extends around the piston shaft (84). In addition, from this position, for the connecting rod (226) to move in the direction indicated by arrow R, a force in that direction will be applied to the connecting rod (226) in order for the first arms (222) and the second arms (224) to become parallel with the centre line CL and raise the auxiliary piston sufficiently for the axis A to move past the centre point/line CP/CL of the piston shaft (84) and toward the solenoid (234). As a result of this arrangement, the connecting rod (226) can be maintained in the position shown in Figs. 13 and 15. Operation of the solenoid (234) to retract the connecting rod (226) in the direction indicated by arrow R and toward the solenoid (234) will release the auxiliary piston (60) so that the biasing mechanism (60) can move the auxiliary piston (60) toward the second position.

[0219] While the retaining mechanism (464) illustrated in Figs. 13 to 15 is different in structure to the retaining mechanism (64) illustrated in Figs. 8 and 9, it will be appreciated that the ignition system (401) comprising the retaining mechanism (464) can be operated in the same manner and method to cause combustion of a fuel air mixture in the combustion chamber (5) as described above for the ignition system (401) comprising the retaining mechanism (64).

Auxiliary Chamber

[0220] The size of the auxiliary cylinder and the range of movement of the auxiliary piston may be set so that when the auxiliary piston (60) is in the second position, the size of the auxiliary chamber (61) (which is defined by the head (80) of the auxiliary piston (60) and the walls of the auxiliary cylinder (58)) is reduced to a minimum or is absent (for example, as schematically illustrated in Fig. 9). In Fig. 9, the head (80) of the auxiliary piston (60) reaches to the combustion chamber (5) of main cylinder (17).

[0221] However, the size of the auxiliary cylinder (58) and the range of movement of the auxiliary piston (60) may be set so that even when the auxiliary cylinder (60) is in the second position, the auxiliary chamber (61) defined by the head (80) of the auxiliary piston (60) and the walls (59) of the auxiliary cylinder (58) is still present despite being reduced in size. An example of this is schematically illustrated in Fig. 16, in which the auxiliary piston (60) is shown in the second position.

[0222] In addition, the auxiliary cylinder (58) may be separated from the main cylinder (17). For example, in the example shown in Fig. 16, the auxiliary cylinder (58) is separated from the main cylinder (17) by a wall (63) in which an opening (65) is formed. In this case, the auxiliary chamber (61) is defined by the head of the auxiliary piston (60), the walls (59) of the auxiliary cylinder (58) and the wall (63). In Fig. 16, one opening (65) is shown. However, there may be multiple openings (65) formed in the wall (63) and the size, number and position of the openings is not limited.

[0223] It will be appreciated that, as the auxiliary chamber (61) opens into combustion chamber (5) via the opening (65), gases (such as the fuel air mixture prior to combustion and the high pressure and high temperature combustion gases resulting from combustion) within the combustion chamber (5) can move from the combustion chamber (5) into the auxiliary chamber (61) and vice versa.

[0224] In Fig. 16, the reciprocating piston (15) is at top dead centre. The volume of the combustion chamber (5) is reduced. In this arrangement, the components of the fuel air mixture which have been introduced into the combustion chamber (5) have been compressed first by the movement of the reciprocating piston (15) in the main cylinder (17) from bottom dead centre to top dead centre during the compression stroke and secondly by the movement of the auxiliary piston (60) from the first position to the second position. As a result, the bulk of the compressed fuel air mixture (13) may be in the auxiliary chamber (61). The movement of the auxiliary piston (60) to the second position increases the pressure in the auxiliary chamber (61) and the combustion chamber (5) to cause combustion. In such an arrangement, combustion of the fuel air mixture (13) may begin in the auxiliary chamber (61).

[0225] It will also be appreciated that the auxiliary chamber (61) may be a pre-chamber or a pre-combustion chamber. In addition, some of the components of the fuel air mixture may be introduced into the auxiliary chamber (61) as well as into the combustion chamber (5). In such cases, these components may be delivered to the auxiliary chamber via valves as described earlier with respect to the introduction of components of the fuel air mixture (13) into the main cylinder (17). In an alternative example, all of the components of the fuel air mixture are introduced via the auxiliary chamber (61). [0226] Depending on the type of engine, a glow plug may be present in the auxiliary chamber (61) (for example, for a diesel engine) or a spark plug may be present in the auxiliary chamber (61) (for example, for a gasoline engine). It will also be understood that where valves, glow plugs spark plugs or the like are provided in the auxiliary chamber (61), they will be provided at a position which is out of the range of the movement of the auxiliary piston (60).

[0227] In an alternative arrangement to the example described above with reference to Fig. 16, there is no wall (63) and the auxiliary cylinder opens into the main cylinder (17) in the manner shown in Figs. 8 and 9. A wall (63) and opening (65) as described above with respect to Fig. 16 would also be compatible with the arrangement shown in Figs. 8 and 9.

Additional chamber(s)

[0228] As mentioned above, the auxiliary cylinder (58) and the main cylinder (17) may be separated. For example, an additional chamber (or chambers) may be provided between the auxiliary cylinder (58) and the main cylinder (17) and the auxiliary cylinder (58) may open into that additional chamber and that additional chamber may in turn open into the main cylinder (17). In such an arrangement, the auxiliary cylinder (58) is in fluid communication with the combustion chamber (5) (defined by the reciprocating piston (15) and the main cylinder (17)) via the additional chamber.

[0229] Thus, in this arrangement, the additional chamber opens into the combustion chamber (5) and the auxiliary chamber (61) opens into the additional chamber such that gases (such as the fuel air mixture prior to combustion and the high pressure and high temperature combustion gases resulting from combustion) within the combustion chamber (5) can move into the additional chamber and into the auxiliary chamber (61) and vice versa.

[0230] In an embodiment, when the reciprocating piston (15) is at top dead centre within the main cylinder (17), the bulk of the compressed fuel air mixture (13) may be in the additional chamber as a result of the compression stroke of the reciprocating piston (15) within the main cylinder (17). In such embodiments, combustion of the fuel air mixture (13) may begin in the additional chamber.

[0231] As with the embodiments described earlier, movement of the auxiliary piston (60) from the first position toward the second position increases a pressure within the combustion chamber (5) and within the additional chamber to cause combustion of a compressed fuel air mixture (13). Increasing the pressure within the combustion chamber (5) and the additional chamber elevates the pressure and temperature of the fuel air mixture (13) in the combustion chamber (5) and the additional chamber to above an auto ignition temperature to cause combustion.

[0232] In this variation as well, the auxiliary piston (60) is movable from the second position toward the first position due to expansion of high pressure and high temperature combustion gasses (9), which are produced by combustion of the fuel air mixture (13), in the combustion chamber (5) and/or the additional chamber. In this case, when the auxiliary piston (60) moves to the first position, the retaining mechanism (64, 464) is operable to hold the auxiliary piston (60) at the first position.

[0233] Furthermore, when the auxiliary piston (60) is released from the first position and moves toward the second position, the combined volume of the combustion chamber (5), the additional chamber and the auxiliary chamber (61) is further reduced. The auxiliary cylinder (58) and the auxiliary piston (60) may be configured so that the auxiliary chamber (61) has a sufficient volume and size that the decrease in the combined volume of the auxiliary chamber (61) which is in fluid communication with the combustion chamber (5) is sufficient to increase the pressure within the combustion chamber (5) and the additional chamber to increase the temperature of the compressed fuel air mixture (13) by around an additional 200°C. In some examples, the volume of the auxiliary chamber (61) is around the same as the volume of the combustion chamber (5). In addition, in other examples, the volume of the auxiliary chamber (61) is around the same as the combined volume of the combustion chamber (5) and the additional chamber. In yet other examples, the volume of the auxiliary chamber (61) is around the same as the volume of the additional chamber.

[0234] In addition, there may be more than one additional chamber between the auxiliary cylinder (58) and the combustion chamber (5). The additional chamber may be a conduit between the auxiliary cylinder (58) and the combustion chamber (5).

[0235] The additional chamber may be a pre-chamber or a pre-combustion chamber. In addition, some of the components of the fuel air mixture may be introduced into the additional chamber as well as into the combustion chamber (5). In such cases, these components may be delivered to the additional chamber via valves as described earlier with respect to the introduction of components of the air fuel mixture (13) into the main cylinder (17). [0236] In an alternative example, all of the components of the air fuel mixture are introduced into the additional chamber.

[0237] In another example, the auxiliary cylinder (58) and auxiliary piston (60) are provided at a position between (intermediate) an additional chamber and the combustion chamber (5).

[0238] As described above, the ignition system (401) may include one or more sensors (27) which provide sensors signals (29) indicative of conditions or states of the engine and/or environment. Where one or more additional chamber is present, the ignition system (401) may also include one or more sensors (27) which provide sensor signals (29) indicative of conditions or states related to the additional chamber or chambers. These may include (but are not limited to) conditions related to the composition, temperature, and/or pressure of the fuel air mixture (13) within the additional chamber. In addition, the controller (23) described earlier may perform control of the ignition system (401) with reference to those sensor signals (29).

Varying an effective compression ratios

[0239] In some examples, the timing of the release and/or holding of the auxiliary piston (60) may be used to manipulate the pressure in the combustion chamber (5) at, or just before, combustion.

Variable auxiliary chamber 561

[0240] In some examples of the internal combustion engine (503), the auxiliary piston (560) and auxiliary cylinder (558) includes an adjustment system (502) to allow variation in the volume of the auxiliary chamber (561). An example of an internal combustion engine (503) with an adjustment system (502) is illustrated in Figs. 19a to 19d and 20a to 20b. By varying the volume of the auxiliary chamber (561), this may allow variation in the elevated pressure within the combustion chamber (5) caused by the auxiliary piston (560) as it moves from the first position to the second position. It is to be appreciated that this may be used to assist in increasing the efficiency and operation of the engine (503).

[0241] The volumetric efficiency of an engine may depend on the particular throttle setting that the engine is running (as well as other factors including engine speed). Therefore the volumetric efficiency (503) may vary between idle, part throttle, and full throttle. A consequence of this change in volumetric efficiency is that the pressure of the fuel air mixture (13) when the piston (15) is at top dead centre may differ depending on the throttle setting. Consequently, the pressure increase required of the ignition system (501) to cause combustion of the fuel air mixture (13) can also vary.

[0242] In one example, at a lower throttle, less fuel air mixture (13) is introduced into the main cylinder (17) during intake. This may lead to a relative lower pressure of the fuel air mixture (13) when the piston (15) is at top dead centre (compared to when the engine is at full throttle). Thus the ignition system (501) may be adjusted to compensate for this lower relative pressure by increasing the pressure of gasses that the auxiliary piston (560) provides into the main cylinder (17). Conversely at higher throttle settings the ignition system (501) may be adjusted to provide a smaller pressure increase since the fuel air mixture (13) will be at a high pressure.

[0243] Figs. 19a and 19b illustrate an example of the ignition system (501) configured to provide a relatively smaller volume in the auxiliary chamber (561). In this example, the ignition system (501) has similar features to the system illustrated in Figs. 13a to 15d. One difference is that the first end (224a) of the second arm (224) is pivotally connected to a slot in an adjustment member (504) instead of a fixed mount 232. In particular, the adjustment member (504) may selectively adjust the position of a pivot point (510) of the first end (224a) of the second arm (224). In Figs. 19a and 19b, the pivot point (510) of the first end (224) is relatively lower (and closer to the main cylinder (17)) than the configuration in Figs. 19c and 19d. Accordingly, when the auxiliary piston (560) is at the second position (as shown in Fig. 19b) it will be closer to the main cylinder (17) than the configuration in 19d. This results in an auxiliary chamber (561) having a smaller volume so that the ignition system (501) provides higher pressure to the main cylinder (17).

[0244] The adjustment member (504) may be manipulated by an actuator (not shown) via an arm (506). In some examples, the arm (506) may be actuated by a linear motor, a rotary motor coupled to a rack and pinion system, or a worm gear. It is to be appreciated that other forms of actuating the adjustment member (504) can be used. A slot (532) of a fixed mount guides a pin (550) at pivot point (510) in a linear direction that is in substantially the same directional as movement of the auxiliary piston (560), as best illustrated in Fig. 20b.

[0245] Figs. 19c and 19d illustrate where the adjustment member (504) of the adjustment system (502) is configured to provide a relatively larger volume in the auxiliary chamber (561). In this example, the pivot point (510) is displaced away from the main cylinder (17) (i.e. upwards) so that at the first and second positions (as shown in Figs. 19c and 19d respectively) are further away from the main cylinder (17). This in turn, provides a relatively larger volume for the auxiliary chamber (561) at these positions. During operation, this may provide a lower increase in pressure in the combustion chamber (5) when the auxiliary piston (560) is moved from the first position to the second position. This may suitable, for example, when there is higher volumetric efficiency such as during full throttle.

[0246] The variation in the volume of the auxiliary chamber (561), in particular enlarging the volume, may also be used to prevent detonation during the combustion cycle. In some engines, it may be desirable to keep a constant compression ratio (for a given fuel and air mixture) just before combustion at top dead centre. For example, some fuels used in compression ignition engines may operate best at around 16: 1 to 17: 1 compression ratio. To maintain such a compression ratio, even at different volumetric efficiencies, the volume of the auxiliary chamber (561) is adjusted.

[0247] It is to be appreciated that the compression ratio will be based on the adjustable volume of the auxiliary chamber (561), the volume of the combustion chamber (5) and the swept volume of the cylinder (5). Thus the adjustment of the auxiliary chamber (561) may allow adjustment of the compression ratio towards a desired ratio before activation of the auxiliary piston (560), which is usually around top dead centre. Upon activation of the auxiliary piston (560), the pressure will increase further to initiate combustion.

Two stroke cycle

[0248] In some variations, the ignition system (401) may be adapted for use with an engine (403) operating on a two-stroke cycle as illustrated in Figs. 17a to 17c.

[0249] In the down stroke, as shown in Fig. 17a, the reciprocating piston (15) moves from the top dead centre to the bottom dead centre due to expansion of high pressure combustion gasses (9) in the combustion chamber (5).

[0250] Around the bottom dead centre, as shown in Fig. 17b, the reciprocating piston (15) has moved in the main cylinder (17) such that the intake port (31) and the exhaust port (33) are open. This allows introduction of a fuel air mixture (13) into the main cylinder (17) and exhausting of combustion gasses from the main cylinder (17) as shown in Fig. 17b.

[0251] A subsequent up stroke, as shown in Fig. 17c, includes moving the main cylinder (17) from the bottom dead centre to the top dead centre thereby compressing the fuel air mixture (13). [0252] The two-stroke cycle engine (403) may use an adaptation of the ignition system (401) and method (300) (such as that described with reference to Figs. 10a to lOe) between the end of the up stroke (Fig. 17c) and the beginning of the down stroke (Fig. 17a).

[0253] In particular, as the reciprocating piston (15) is approaching top dead centre, is at top dead centre, or is past top dead centre, the ignition system (401) may release the auxiliary piston (60) from the first position to elevate the fuel air mixture (13) therein to above an autoignition temperature. This is done by releasing the auxiliary piston (60) as shown in Fig. 10c.

[0254] As the fuel air mixture (13) undergoes combustion and the high pressure and high temperature combustion gases generated by that combustion power the reciprocating piston (15) during a down stroke, the high pressure and high temperature combustion gasses also move the auxiliary piston (60) from the second position toward the first position as shown in Fig. lOd.

[0255] The retaining mechanism (64, 464) holds the auxiliary piston (60) in the first position for subsequent ignition as illustrated in Fig. lOe.

Rotary engine

[0256] It is to be appreciated that the ignition system (401) may be adapted to operate in other types of internal combustion engines, such as rotary engines (443). A rotary engine (also called "wankel engine" after the inventor Felix Wankel), includes an epitrochoid- shaped housing within which a rotor (47) (having a triangle-like shape) that moves to drive an eccentric shaft (49) as shown in Fig. 18. The combustion chambers (51, 53, 55) are formed in the space between the sides of the triangle-like rotor (47) and the epitrochoid- shaped housing 45. The apexes of the rotor maintain contact with the walls of the epitrochoid- shaped housing throughout rotation. Typically for a single rotor engine, there are three combustion chambers that move as the rotor moves (which will be at different stages of intake, compression, power and exhaust of the combustion chamber). In some examples, a rotary engine may have more than one rotor, each attached in a respective epitrochoid- shaped housing.

[0257] Rotary engines, like reciprocating internal combustions engines described above, require an ignition system to ignite compressed fuel air mixture. In conventional rotary engines, this may include providing a spark plug to ignite the compressed fuel air mixture. [0258] It is to be appreciated that the ignition system (401) described above could be used to increase the pressure in the combustion chambers to cause combustion of the compressed fuel air mixture in a rotary engine. This may include providing an auxiliary piston within an auxiliary cylinder which moves from a first position to a second position to selectively increase a pressure in the combustion chamber to cause combustion of the fuel air mixture in the combustion chamber. An example is shown in Fig. 18. This may assist in causing combustion since the combustion chambers (51, 53, 55) moves as the rotor moves.

Processing device

[0259] Fig. 21 illustrates an example of a processing device. The processing device may be in the form of a computer. The processing device may be used as part of the controller (23) for the ignition system (1) that receives sensor signals (29) from sensors (27) and sends control signals (25) to actuators (21). The processing device (23) includes a processor (1310), a memory (1320) and an interface device (1340) that communicates with each other via a bus (1330). The memory (1320) stores instructions and data for implementing the method (100, 200, 300) described above, and the processor (1310) performs the instructions from the memory (1320) to implement the method (100, 200, 300). The interface device (1340) facilitates communication other peripherals, such as the sensor(s) (27) and actuator(s) (21). In some examples, the interface device (1340) allows communication with a user interface and/or with other processing devices networked with the processing device. It should be noted that although the processing device (23) may be independent, functions performed by the processing device (23) may be distributed between multiple network elements.

[0260] It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the above-described embodiments, without departing from the broad general scope of the present disclosure. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.