"INTERNAL COMBUSTION ENGINE"

TECHNICAL FIELD

The present invention relates to internal combustion engines. In conventional internal combustion engines the power range is controlled by a throttle which regulates the volume of air entering the engine.

BACKGROUND ART

To get the most mechanical power from the combustion, first the fuel air mixture must be compressed to the optimum pressure, then ignited, a little before the minimum volume in the cylinder is reached. This results in the most efficient use of the fuel. Although this can be achieved at full power, when the throttle control is used, the air entering the cylinder is less dense. This effectively lowers the compression ratio. The rate of combustion is slowed. Efficiency continually decreases, until at idle, the combustion is less than optimal. This is shown by the presence of carbon monoxide in the exhaust gasses.

It is therefore an object of the present invention to provide an internal combustion engine which addresses the abovementioned disadvantages and/or at least provides the public with a useful choice.

DISCLOSURE OF INVENTION

In an aspect the present invention consists in a constant compression ratio reciprocating internal combustion engine having between the or each piston and the crank a three part or bar ("part") toggle linkage where the disposition (positional and/or orientation) of the intermediate part of the three part toggle linkage can be selectively varied. Preferably said intermediate part of the three part toggle linkage is mounted by a pivot and is able to be shuttled on a rectilinear or curved locus (thereby to affect position and/or orientation of the intermediate part).

Preferably the effect of shuttle position of said pivot and/ or variation of the disposition of the intermediate part of the three part toggle linkage is to achieve at least one or more of: (1) a substantially constant compression ratio throughout the power range (eg, preferably to optimise the combustion efficiency),

(2) a longer power stroke than induction stroke,

(3) a control of power without the use of a throttle (preferably to maintain induction air density and/or reduce induction pumping losses), and/ or (4) a maintenance of the power stroke at a maximum length.

In another aspect the present invention consists in a four stroke reciprocating internal combustion engine of a kind having a crank axis at least substantially normal to any piston axis of reciprocation, and wherein the four stroke reciprocating internal combustion engine can achieve, by variation of the piston to crank linkage, at least one or more of:

(1) a substantially constant compression ratio throughout the .power range (eg, preferably to optimise the combustion efficiency),

(2) a longer power stoke than induction stroke,

(3) a control of power without the use of a throttle (preferably to maintain induction air density and/or reduce induction pumping losses), and/or

(4) a maintenance of the power stroke at a maximum length.

In another aspect the invention consists in a four stroke reciprocating internal combustion engine of a kind having a crank axis at least substantially normal to any piston axis of reciprocation, wherein the crank is connected to the or each piston by a three part toggle linkage system, and wherein a shuttling pivot mount of an intermediate part of a three part toggle linkage system allows one or more of:

(1) a substantially constant compression ratio throughout the power range (eg, preferably to optimise the combustion efficiency),

(2) a longer power stoke than induction stroke,

(3) a control of power without the use of a throttle (preferably to maintain induction air density and/or reduce induction pumping losses), and/or

(4) a maintenance of the power stroke at a maximum length. In another aspect the invention consists in a four stoke reciprocating internal combustion engine of the kind having a crank axis at least substantially normal to the piston or piston's axis of reciprocation, there being a linkage pivotally from the crank and pivotaHy to the or each piston, and where said linkage includes a member pivotally attached to each direct linkage to the piston and to the crank and itself pivotally mounted, to be adjustable yet selectively movable relative to the crank axis, all such pivot axes being substantially parallel, the effect of which is to enable one or more of:

(1) maintaining a constant compression ratio throughout the power range to optimise the combustion efficiency,

(2) providing a longer power stoke than induction stroke,

(3) controlling power without the use of a throttle to maintain induction air density, and eliminate induction pumping losses, and/ or

(4) maintaining the power stroke at a maximum length.

Preferably the shuttling of said pivot is determined by the position of an accelerator. Preferably the shuttling of said pivot is effected by an electric motor.

Preferably said electric motor drives a screw thread to effect the shuttling of said pivot. Preferably the shuttling of said pivot is effected by a hydraulic system. Preferably said hydraulic system utilises the engines oil pressure.

In another aspect, the invention may broadly be said to consist in an internal combustion engine comprising: an engine block having a crank axis and a cylinder bore lying in a plane generally perpendicular to the crank axis, a piston sealingly co-operating with said cylinder bore for reciprocal movement therein, a crankshaft supported by the engine block and rotatable about a crank axis, said crankshaft having a crank pin radially spaced from said crank axis, at least one intermediate link pivotally attached to a slide, said slide being slidably adjustable, an elongate piston connecting rod having a first end pivotably attached to the said piston and a second end pivotally attached to the said intermediate link, an elongated crank connecting rod having a first end pivotably attached to the said crank pin and a second end pivotally attached to the said intermediate link, wherein adjustment of said slide varies the length of the stroke of the piston. Preferably adjustment of said slide enables one or more of:

(1) a substantially constant compression ratio throughout the power range (eg, preferably to optimise the combustion efficiency),

(2) a longer power stoke than induction stroke,

(3) a control of power without the use of a throttle (preferably to maintain induction ait density and/or reduce induction pumping losses, and/or

(4) a maintenance of the power stroke at a maximum length. Preferably said internal combustion engine is a four stroke engine.

Preferably said slide can be adjusted between a position resulting in maximum power of the internal combustion engine and a position resulting in minimum power of the internal combustion engine.

Preferably said slide can be adjusted a length of 40mm.

- A -

Preferably the compression ratio of the internal combustion engine is 10:1 when said slide is in said position resulting in minimum power of the engine.

Preferably the compression ratio of said internal combustion engine is 10:1 when said slide is in said position resulting in maximum power of the engine. Preferably said internal combustion engine has an oil pressure system to lubricate the internal components.

The invention also is a constant compression ratio reciprocation internal combustion engine having a longer power stroke than induction stroke reliant articulating an intermediate zone of the crank to piston connecting assembly. As used herein the term "and/or" means "and" or "or", or both.

As used herein the term "(s)" following a noun includes, as might be appropriate, the singular or plural forms of that noun.

The term "comprising" as used in this specification means "consisting at least in part of. When interpreting statements in this specification which include that term, the features, prefaced by that term in each statement, all need to be present but other features can also be present. Related terms such as "comprise" and "comprised" are to be interpreted in the same manner.

BRIEF DESCRIPTION OF DRAWINGS Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings in which:

Figure 1 is a cross-sectional view of a first embodiment of an internal combustion engine showing the piston at the end of the induction stroke with the slide on maximum,

Figure 2 is a cross-sectional view of an internal combustion engine showing the piston at the point of ignition with the slide on maximum,

Figure 3 is a cross-sectional view of an internal combustion engine showing the piston during the power stroke, with the slide on maximum,

Figure 4 is a cross-sectional view of an internal combustion engine showing the piston at bottom dead centre with the slide on maximum, Figure 5 is a cross-sectional view of an internal combustion engine showing the piston at the end of the induction stroke with the slide on minimum,

Figure 6 is a cross-sectional view of an internal combustion engine showing the piston at top dead centre with the slide on minimum,

Figure 7 is a cross-sectional view of a second embodiment of an internal combustion engine showing the piston at the end of the induction stroke with the slide on maximum,

Figuf e 8 is a cross-sectional view of an internal combustion engine of Figure 7 showing the piston at the point of ignition with the slide on maximum,

Figure 9 is a cross-sectional view of an internal combustion engine of Figures 7 and 8 showing the piston during the power stroke, with the slide on maximum, Figure 10 is a cross-sectional view of an internal combustion engine of Figures 7 to 9 showing the piston at bottom dead centre with the slide on maximum,

Figure 11 is a cross-sectional view of an internal combustion engine of Figures 7 to 10 showing the piston at the end of the induction stroke with the slide on minimum, and

Figure 12 is a cross-sectional view of an internal combustion engine of Figures 7 to 11 showing the piston at top dead centre with the slide on minimum.

We will now describe the embodiment of Figures 1 to 6.

Figure 1 shows a cross-sectional view of an internal combustion engine 1. The engine 1 has an engine block 2 which is preferably a machined casting but may alternatively be manufactured using any other suitable manufacturing process. The engine block 2 has at least one cylinder 3 which defines a cylinder bore. A cylindrical piston 4 has a diameter approximately equal to that of the cylinder bore. The piston 4 is therefore in a co-operative engagement with the cylinder 3. In operation, the piston 4 may travel up and down the cylinder 3 in a reciprocating manner. The piston 4 may be manufactured from any suitable metal and may include piston rings or any other such features of a typical piston obvious to someone skilled in the art.

A crankshaft 5 may be located within the engine block 2. The crankshaft 5 may be fixed to the engine block by bearings such that it is constrained to one axis of rotation. The crank shaft 5 rotates about the crank axis 6. The crank shaft 5 may be cast or forged metal, or manufactured in any other suitable way. At least one intermediate link 7 may be incorporated into the internal combustion engine 1 to act as an intermediate linkage between the crank shaft 5 and the piston 4. Preferably there are two intermediate links for each piston 4.

Each intermediate link 7 is pivotally attached to a slide 8. The slide 8 provides a shuttling pivot for the intermediate link 7. The intermediate link 7 pivots on axis 9 of the slide 8. Any suitable bearing may be employed to allow the intermediate link 7 to pivot on axis 9 of the slide 8.

The slide 8 may be in a sliding engagement with a beam 10 which may be rigidly bolted to the engine block 2. Alternatively, the slide 8 may be in a sliding engagement directly with a surface of the engine block 2. The slide 8 is preferably confined so that it can only slide in one direction along the beam 10.

Preferably the engine has an oil pressure system to lubricate the components within the engine block. This oil pressure system may also be used to lubricate the slide 8.

A piston connecting rod 11 may link the piston 4 to the intermediate links 7. The piston connecting rod 11 may be pivotally connected to the piston 4 by way of a gudgeon pin which provides a bearing for the pivoting motion of the connecting rod 11. Alternatively, any other suitable method of pivotally attaching the piston connecting rod 11 to the piston 4 may be employed. The piston connecting rod pivots on axis 12 during reciprocal movement of the piston 4.

The lower end of the elongate piston connecting rod 11 may be pivotally attached to the upper extent of the intermediate link 7. The piston connecting rod 11 can pivot on axis 13, of the intermediate link 7 on any suitable bearing.

A crank shaft connecting rod 14 may link the crank shaft 5 to the intermediate links 7. The crank shaft connecting rod 14 may be connected to the crank shaft 5 by way of a big end bearing 15. Alternatively, any other suitable method of attaching the crank shaft connecting rod 14 to the crank shaft may be employed. The upper extent of the crank shaft connecting rod may pivot about axis 16 during operation of the engine.

Preferably there is a intermediate link 7 located each side of the crank shaft connecting rod 14 and the piston connecting rod 11. The two intermediate links 7 positioned either side of the connecting rods ensure there is no unbalanced lateral forces acting on the linkages. As the crank shaft 5 rotates, it causes the intermediate links 7 to pivot from side to side in an oscillating manner. The piston 4 is moved, up and down the cylinder 4, by the piston connecting rod 11 attached to the intermediate links 7.

The engine 1 is a four-stroke internal combustion engine. On the first stroke air is drawn into the cylinder 3 through one or more inlet valves as the piston 4 moves downwardly. The second stroke involves compressing the air as the piston 4 moves upwardly. Fuel is preferably injected into the cylinder 4 through an injection nozzle. Alternatively, fuel may be mixed with the air prior to entering the cylinder. Just before the piston reaches its upper most point in the cylinder the fuel/ air mixture is ignited by way of a spark from a spark plug. The ignition of the fuel/air mixture forces the piston 4 downward during this power stroke. Finally, as the piston moves upwardly, the products of the combustion (the exhaust gases) are forced out of the cylinder 3 through one or more exhaust valves.

Injecting the fuel directly into the chamber helps achieve stratified combustion which can increase fuel efficiency.

For every rotation of the crank shaft 5 the piston will make two top dead centres and two bottom dead centres. This results in ignition of the fuel/air mixture inside the cylinder once for every crank shaft rotation.

The valves and any other essential components required for operation of the engine may comprise of any suitable components that are obvious to someone skilled in the art.

Figure 1 shows the piston 4 at the end of the induction stroke, with the slide 8 in the lower position, which results in maximum power. The piston 4 will start moving upwardly compressing the air in the cylinder 3. The volume of the cylinder at this position may be approximately 66% of the volume of the cylinder at the end of the power stroke, indicating that the length of the power stroke is longer than length of the induction stroke.

Figure 2 shows the piston 4 at the point of ignition, with the slide 8 in the lower position, which results in maximum power. The volume of the cylinder is preferably 10% of the volume of the cylinder at the point shown in Figure 1. Therefore the cylinder has a 10:1 compression ratio when in this configuration. Figure 3 shows the piston 4 after ignition during the power stroke. The combustion of the fuel/ air mixture in the cylinder 3 forces the piston downwards. The slide 8 is in the lower position, resulting in maximum power.

Figure 4 shows the piston 4 at bottom dead centre at the end of the power stroke. This is the point before it starts moving upwards again to force the exhaust gases out of the cylinder 3. The slide 8 is in the lower position, resulting in maximum power. The cycle as shown in Figures 1-4 occurs twice for every full revolution of the crank shaft.

An accelerator controls the position of the slide 8. The system would be in continuous operation to respond to small adjustments, or rapid power changes, throughout the entire normal engine running conditions. Therefore, the slide 8 changes position depending on the power requirements from the engine which is dictated by an accelerator. In most circumstances the accelerator would be controlled by a user of a vehicle or machine in which the engine is incorporated. Alternatively, the accelerator may be controlled automatically.

There is preferably no throttle to control the volume of air entering the engine. The air and fuel entering the engine is preferably constant. Adjustment of the slide 8 will therefore alter the power output of the engine, as required.

The accelerator may communicate with an electric motor, which may control the position of the slide 8. An electric motor may be coupled to a screw thread, to adjust the position of the slide 8 depending on the power requirements of the engine. More preferably, a hydraulic system which uses the engines oil pressure would control the position of the slide 8 based on and input from an accelerator.

The slide 8 may be travel 40mm between its lower position resulting in maximum power and its upper position resulting in minimum power. Alternatively the length of travel of the slide 8 may be any suitable length to achieve the desired results from the engine.

The slide 8 may be positioned at any point between the lower position and the upper position depending on the input from the accelerator.

Figures 5 and 6 show a similar relationship to Figures 1 and 2 but with the slide 8 on minimum. The compression ratio is 10:1, as it is when the power slide is on maximum.

Figure 5 shows the piston 4 at the end of the induction stroke with the slide 8 on minimum. The volume of the cylinder when the piston 4 is in this position is approximately 10% of the volume of the cylinder compared with when the slide 8 is on maximum, and the piston 4 is in tiie same position.

The piston 4 reaches top dead centre in Figure 6, which may be just after the point of ignition.

When the slide 8 is on minimum, the stroke of the piston may be 4.5mm, and the length of the combustion chamber when the piston is at top dead centre may be 0.5mm. This equates to a compression ratio of 10:1.

When the slide 8 is on maximum, the stroke of the piston may be 45mm, and the length of the combustion chamber when the piston is at top dead centre may be 5mm. This also equates to a compression ration of 10:1. Therefore the engine has a constant compression ratio, irrespective of the location of the slide 8.

We now describe the second embodiment, ie, that of Figures 7 onwards. In this description we attempt to use the same reference numbers as used hitherto.

In this embodiment the crank shaft is now located within a crank case 19, not in the engine block 2, and rotates on main bearings 6. At the other end of this crank case 19, is a cylindrical hole bored parallel to, and in the same plane as, the main bearings 6. Within this bore is a" shaft 17 that has, "in effect", had its centre machined away leaving a full disc at each end, to form the mountings for the intermediate links 7. The pivot pin, with axis 9, is also fitted into a suitably bored hole, which passes right through this mounting 17. Thus as this cylindrical mounting 17 rotates about its axis 18, the pivot axis 9, moves from the maximum, to the minimum power settings. Or can stop at any point in between. This assembly ensures that the pivot axis 9 is always parallel to the main bearings 6, and the primary forces are carried in a short closed loop within the case. The need for this becomes more apparent when a multi- cylinder engine is considered.

This crank case assembly is mounted in the engine block 2 with a bearing each side concentric with the main bearings 6. As the angular movement, in these bearings to the block is

small, and a small amount of radial movement would not effect the engines performance, a resilient bearing may prove the quietest option. At the other end of the crank case assembly, the pivot pin axis 9 is extended each side to engage in a hole in the sliding blocks 8. These blocks 8 slide in recessed slide ways 10, in the engine block 2. The curvature and slope of these slide ways 10 control the accuracy of the required compression ratio, nominally 10:1, throughout the entire power range. The secondary forces from the piston acceleration and combustion are taken directly through the slides to the engine block.

The crank case 19 would preferably be cast in cast iron for its sound deadening qualities and as the important loads are in compression. Whereas the mounting 17 would need the extra tensile strength of nodular cast iron.

Figure 7 has been added to show that, although the induction stroke is very short at this minimum power setting, the power stroke is still full length.

In this specification where reference has been made to patent specifications, other external documents, or other sources of information, this is generally for the purpose of providing a context for discussing the features of the invention. Unless specifically stated otherwise, reference to such external documents is not to be construed as an admission that such documents, or such sources of information, in any jurisdiction, are prior art, or form part of the common general knowledge in the art.