TECHNICAL FIELD

This invention relates to a displacement device. In particular, this invention relates to a displacement device for a piston and cylinder assembly which is typically connected to a drive means or conventional crankshaft.

SUMMARY OF THE INVENTION

According to the invention, there is provided a displacement device for a piston and cylinder arrangement, which displacement device includes: - a storage member for storing pressurised gas therein; a controller for controlling a quantity of pressurised gas to be stored within the storage member; a communication arrangement for allowing flow communication between the storage member and the piston and cylinder arrangement; and an inlet valve arrangement for controlling the flow of pressurised gas between the storage member and the piston and cylinder arrangement.

The storage member may define a storage zone which may be arranged in flow communication with a pressure source via a pressure source communication member. The storage member may include a volume adjustment member for allowing the volume of the storage zone to be adjusted, the volume adjustment member preferably being displaceable relative walls defining the storage zone.

The controller may be in the form of any one or more of the group including an electronic, mechanical, and electromechanical controller. The communication arrangement may be in the form of a body defining a plurality of passageways therein for allowing flow communication between the pressure source, storage member and piston and cylinder arrangement. The body may be shaped and/or configured to be mounted on a conventional engine body or block having a piston and cylinder arrangement operating therein.

The inlet valve arrangement may be in the form of any suitable conventional valve, preferably being in the form of any one or more of the group including a rotary valve, poppet valve, shuttle valve, and spool valve. The inlet valve arrangement may be configured to control the flow of pressurised gas into the storage member. The inlet valve arrangement may include an inlet valve controller for controlling displacement of the inlet valve arrangement between open and closed conditions.

An outlet valve arrangement may be provided for controlling the flow of pressurised gas out of the piston and cylinder arrangement. The outlet valve arrangement may be in the form of any suitable conventional valve, preferably being the form of a poppet valve. The outlet valve arrangement may include an outlet valve controller for controlling displacement of the outlet valve arrangement between open and closed conditions.

The inlet and outlet valve controllers may be configured to control the displacement of the respective valves between the open and closed conditions according to a position of a crankshaft or piston of a piston and cylinder arrangement. The controllers may be in the form of any one or more of the group including electronic, mechanical, and electromechanical controllers, preferably being in the form of mechanical controllers connected to a crankshaft of the piston and cylinder arrangement.

A cylinder pressure controller may be provided for controlling pressure in the cylinder. The cylinder pressure controller may include an extension member extending between the body and the piston and cylinder arrangement. The extension member may include an opening which may be arranged in register with the cylinder of the piston and cylinder arrangement. The cylinder pressure controller may include a volume tuning member mounted displaceably on the extension member and which may be configured to be displaceable between a reduced volume condition wherein pressure in the cylinder may be increased and an increased volume condition wherein pressure in the cylinder may be reduced during discharge of pressurised gas from the inlet valve arrangement.

A regulator may be provided for regulating the flow of pressurised gas from the pressure source into the storage member.

The pressure source may include a drive means which may be coupled to a compressor for generating compressed gas to be supplied to the storage member. The compressor may be arranged in flow communication with a first reservoir which may be capable of storing pressurised gas having a pressure in the range of 5 bar to 20 bar, preferably being in the region of 10 bar. The first reservoir may be configured to supply pressurised gas to a pressure intensifier for increasing the pressure of the gas before being supplied to the inlet valve arrangement. The pressure intensifier may be driven by the drive means. In particular, the pressure intensifier may be coupled to a hydraulic pressure source which may be driven by the drive means. An air outlet of the pressure intensifier may be arranged in flow communication with a second reservoir which may be capable of storing gas at a pressure in the range of 100 bar to 500 bar, preferably being in the region of 250 bar. The second reservoir may be arranged in flow communication with the storage member for supplying pressurised gas thereto.

BRIEF DESCRIPTION OF THE DRAWINGS

A displacement device in accordance with the invention will now be described by way of the following, non-limiting examples with reference to the accompanying drawings. In the drawings: -

Figure 1 is a three-dimensional schematic showing the displacement device in accordance with the invention, mounted on a piston and cylinder arrangement;

Figures 2a and 2b are sectioned views of a part of the displacement device depicting the filling and discharge conditions of the inlet valve arrangement, respectively;

Figures 3a to 3c are sectioned views of a part of the displacement device depicting the minimum, reduced and increased volume conditions of the storage member;

Figure 4 is a partially sectioned three-dimensional schematic showing parts of the displacement device and cylinder arrangement;

Figure 5 is a three-dimensional schematic showing a valve cam assembly of the displacement device;

Figure 6 is a three-dimensional schematic showing a controller cam assembly of the displacement device;

Figures 7 and 8 are three-dimensional schematics showing part of a cylinder pressure controller of the displacement device in increased and reduced volume conditions respectively; and

Figure 9 is a partially sectioned three-dimensional schematic of the displacement device shown in Figure 1 .

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, reference numeral 10 refers generally to a displacement device for a piston and cylinder arrangement 12. The displacement device 10 includes a storage member 14 for storing pressurised gas, typically being air, therein, a controller 16 for controlling a quantity of pressurised gas to be stored within the storage member 14, a communication arrangement in the form of a body 18 defining a plurality of passageways for allowing flow communication between the storage member 14 and the piston and cylinder arrangement 12 and an inlet valve arrangement 20 for controlling the flow of pressurised gas between the storage member 14 and the piston and cylinder arrangement 12.

The storage member 14 defines a storage zone 22 which is arranged in flow communication with a pressure source (not shown) via a pressure source communication member, typically being in the form of a passageway 18.1 defined in the body 18. In particular, an inlet and outlet passage 26 of the storage zone 22 is arranged in flow communication with the pressure source (not shown) via the passageway 18.1 defined in the body 18. The inlet and outlet passage 26 of the storage zone 22 are defined by a single passage 18.1 extending between storage member 14 and the inlet valve arrangement 20. The storage zone 22 has a generally cylindrical shape. A plurality of recesses 28 are defined in an inner wall 30 of the storage member 14 for increasing the volume of the storage zone 22. The recesses 28 are arranged in a spaced apart configuration along a length of the storage member 14. The storage member 14 includes a volume adjustment member in the form of a rod 32 for allowing the volume of the storage zone 22 to be adjusted, the rod 32 typically being displaceable relative walls 30 defining the storage zone 22. The rod 32 is sized, shaped and configured to be received co-axially and complementally by the storage zone 22. As most clearly shown in Figures 3a to 3c, the rod 32 is configured to be displaceable between an increased volume condition, as shown in Figure 3a, wherein an increased volume of the storage zone 22 is in flow communication with the inlet passage 26 and a reduced volume condition, as shown in Figure 3b, wherein a reduced volume of the storage zone 22 is in flow communication with the inlet passage 26. The rod 32 includes a first end region 34 which extends into the storage zone 22. The rod 32 includes a reduced diameter portion 36, typically located between a generally central region 38 of the rod 32 and the first end region 34 thereof, which defines a flow passage 40 for allowing pressurised gas to flow from the inlet passage 26 to a recess 28 defined in the inner wall 30 of the storage zone 22. More particularly, the reduced diameter portion 36 has a length such that during the reduced volume condition, the inlet 26 is in flow communication with fewer recesses 28 and during the increased volume condition, the inlet 26 is in flow communication with all the recesses 28 thereby allowing the full capacity of the storage zone 22 to be utilised. The rod 32 is typically displaced to the increased volume condition during power demanding conditions. The rod 32 can be displaced to a minimum volume condition, as shown in Figure 3c, wherein flow communication between the inlet 26 and the recesses 28 is inhibited, this condition typically corresponding to a situation where little to no power from the piston and cylinder arrangement 12 is required. It is to be appreciated that displacement of the rod 32 between the minimum and increased volume conditions is unaffected by pressure build up in the storage member 22.

The controller (not shown) is in the form of an electronic controller (not shown), typically in the form of a processor (not shown), which is arranged in electrical communication with a displacement mechanism 42, as shown in Figure 6, for displacing the rod 32 between the minimum, reduced and increased volume conditions. The displacement mechanism 42 is in the form of a controller cam assembly 44. A cam 46 of the controller cam assembly 44 is configured to engage a free end region 48 of the rod 32, which free end region 48 extends from the storage zone 22. A biasing member, typically in the form of a spring 50, is provided for biasing the rod 32 towards the minimum volume condition. The displacement mechanism 42 further includes a controller drive means, typically in the form of a stepper motor 52, for driving the controller cam assembly 44.

The passageways defined in the body 18 are configured to allow flow communication between the pressure source (not shown), storage member 14 and piston and cylinder arrangement 12. The body 18 is shaped and configured to be mounted on a conventional engine body or block 54 having a piston and cylinder arrangement 12 operating therein.

The inlet valve arrangement 20 is in the form of any suitable valve, typically being in the form of a spool valve 56. The inlet valve arrangement 20 is further configured to control the flow of pressurised gas into the storage member 22, typically being arranged in flow communication with the pressure source (not shown) via an inlet passageway 18.2 defined in the body 18. The inlet valve arrangement 20 is displaceable between a filling condition, as shown in Figure 2a, wherein the flow of pressurised gas between the pressure source (not shown) and the storage member 22, via passageways 18.1 and 18.2, is permitted and the flow of pressurised gas between the storage member 22 and the piston and cylinder arrangement 12 is inhibited and a discharge condition wherein the flow of pressurised gas between the pressure source (not shown) and the storage member 22 is inhibited and the flow of pressurised gas between the storage member 22 and the piston and cylinder arrangement 12 is permitted, typically via an inlet valve passageway 20.1. The inlet valve arrangement 20 is sized, shaped and configured to allow rapid discharge of air from the storage member 22 to the piston and cylinder arrangement 12. The inlet valve arrangement 20 includes an inlet valve controller 58 for controlling displacement of the inlet valve arrangement between open and closed conditions. The inlet valve controller 58 is configured to displace the inlet valve arrangement 20 towards the discharge condition when the piston 12.1 of the piston and cylinder arrangement 12 is nearest to the body 18 thereby allowing the pressurised gas to displace the piston 12.1 away from the body 18. It is to be appreciated that the position of the piston 12.1 nearest to the body 18 corresponds to a piston position commonly known as top dead centre and the displacement of the piston 12.1 away from this position is known as a power stroke. It is to be further appreciated that displacement of the spool valve 56 between the filling and discharge conditions is unaffected by pressure build up in the valve 56 or in the storage member 22.

An outlet valve arrangement 60 is provided for controlling the flow of pressurised gas out of the piston and cylinder arrangement 12. The outlet valve arrangement 60 is in the form of any suitable conventional valve, typically being in the form of a poppet valve 62. The outlet valve arrangement 60 is configured to be displaceable between a closed condition and an open exhaust condition wherein the flow of gas out of the cylinder 12.2 of the piston and cylinder arrangement 12 is permitted. The outlet valve arrangement 60 includes an outlet valve controller 64 for controlling displacement of the outlet valve arrangement 60 between the open and closed conditions. More particularly, the outlet valve controller 64 is configured to displace the outlet valve arrangement 60 into an open exhaust condition typically when the piston 12.1 is being displaced from a position furthest away from the body 18 toward the position nearest thereto to allow lower pressure gas to exit the cylinder 12.2. It is to be appreciated that the position of the piston 12.1 furthest from the body 18 corresponds to a piston position commonly known as bottom dead centre and the displacement of the piston 12.2 away from this position is known as an exhaust stroke.

The inlet and outlet valve controllers 58 and 64 are configured to control the displacement of the respective valves between the filling and discharge and open and closed conditions, respectively, according to a position of a crankshaft 66 or piston

12.1 of the piston and cylinder arrangement 12. Biasing members, typically in the form of springs 68, are provided for biasing the inlet and outlet valve arrangements 20 and 60 towards the filling and closed conditions, respectively. The controllers 58 and 64 are in the form of mechanical controllers which are connected to the crankshaft 66. The mechanical controllers include cams 70 of a valve cam assembly 72 which is driven by the crankshaft 66 of the piston and cylinder arrangement 12. A timing adjustment arrangement 74 is provided for allowing the timing of the valve cam assembly 72 to be adjusted according to operational conditions of the piston and cylinder arrangement 12.

A cylinder pressure controller 76 is provided for controlling pressure in the cylinder 12.2 during the discharge condition. The cylinder pressure controller 76 includes an extension member, typically being in the form of a plate 78, which extends between the body 18 and the piston and cylinder arrangement 12. The plate 78 includes a generally circular opening 80 which is arranged in register with the cylinder

12.2 of the piston and cylinder arrangement 12. The generally circular opening 80 has a diameter which corresponds to a diameter of the cylinder 12.2. The cylinder pressure controller 76 includes a volume tuning member, typically in the form of a planar member 82, which is mounted displaceably on the plate 78 and which is configured to be displaceable between a reduced volume condition wherein pressure in the cylinder

12.2 is increased and an increased volume condition wherein pressure in the cylinder

12.2 is reduced during discharge of pressurised gas from the inlet valve arrangement 20. A pressure controller drive means, typically in the form of a stepper motor 84, is provided for displacing the volume tuning member 82 between the reduced and increased volume conditions. The pressure controller stepper motor 84 is configured to be controlled by the processor (not shown). Typically, the volume tuning member 82 is displaced towards the reduced volume condition when a user requires higher output from the piston and cylinder arrangement 12.

A regulator 86 is provided for regulating the flow of pressurised gas from the pressure source into the storage member 22. The regulator 86 is controlled by the processor (not shown).

A plurality of pressure sensors (not shown) are provided which are configured to provide pressure data to the processor (not shown) in order to close a feedback control loop. Pressure sensors are located in the regulator 86, storage member 22 and cylinder 12.2 for allowing the processor (not shown) to analyse the pressure therein and control the regulator 86, controller stepper motor 52 and timing adjustment arrangement 74 in operation. The processor (not shown) is configured to analyse pressure readings from the pressure sensors (not shown) and control the regulator 86 such that pressure supplied to the storage member 22 is maintained at a constant level throughout operation.

The pressure source (not shown) includes a drive means (not shown) which is coupled to a compressor (not shown) for generating compressed gas to be supplied to the storage member 22. The compressor (not shown) is arranged in flow communication with a first reservoir (not shown) which is capable of storing pressurised gas having a pressure in the range of 5 bar to 20 bar, typically being in the region of 10 bar. The first reservoir (not shown) is configured to supply pressurised gas to a pressure intensifier (not shown) for increasing the pressure of the gas before being supplied to the inlet valve arrangement 20. The pressure intensifier (not shown) is driven by the drive means (not shown). In particular, the pressure intensifier (not shown) is coupled to a hydraulic pressure source (not shown) which is driven by the drive means (not shown). An air outlet of the pressure intensifier (not shown) is arranged in flow communication with a second reservoir (not shown) which is capable of storing gas at a pressure in the range of 100 bar to 500 bar, typically being in the region of 250 bar. The second reservoir (not shown) is arranged in flow communication with the storage member 22 via inlet piping 88 and passageways 18.1 and 18.2 defined in the body 18 for supplying pressurised gas thereto.

The body 18 defines a plurality, typically a set of three, chambers 90 therein which is sized, shaped and configured to receive the storage member 22, inlet valve arrangement 20 and outlet valve arrangement 60 therein. It is to be appreciate that the body 18 can include any number of sets of chambers for accommodating any number of piston and cylinder arrangements 12.

The inventor believes that the displacement device in accordance with the invention is advantageous in that it displaces a piston and cylinder arrangement with improved efficiency when compared to conventional combustion engines. In addition, the displacement device produces fewer harmful emissions and due to the absence of substantial heat transfer during operation of the displacement device, the parts have an improved life span.

It is, of course, to be appreciated that the displacement device in accordance with the invention is not limited to the precise constructional and functional details as hereinbefore described with reference to the accompanying drawings and which is varied as desired.