WO2012155178A1

WO2012155178A1 - An apparatus, an engine, a pump, an electrical motor and/or an electrical generator

Info

Publication number: WO2012155178A1
Application number: PCT/AU2012/000487
Authority: WO
Inventors: Martin Robert SHUTLAR
Original assignee: Shutlar Martin Robert
Priority date: 2011-05-13
Filing date: 2012-05-07
Publication date: 2012-11-22

Abstract

An apparatus (10), comprising: a cam set (20) of three barrel cams (40, 50, 60) concentrically disposed about a common rotational axis (70), the cam set (20) comprising a radially inner, middle and outer cam (40, 50, 60) with respective multilobate cam tracks (100) disposed at a first axial end region (80) of the cam set (20), the inner and outer cams (40, 60) synchronised to rotate in use at the same angular velocity, the middle cam (50) arranged to counter rotate in use with an equal and opposite angular velocity with respect to the inner and outer cams (40, 60); and at least one first cam follower assembly (30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h) comprising three first roller followers (110a, 110b, 110c) supported for independent rotation, the first roller followers (110a, 110b, 110c) engaging with the cam track (100) of the respective inner, middle or outer cam (40, 50, 60), the first cam follower assembly assembly (30a,) connected to a reciprocating first piston (150a) slidable in an axially orientated first cylinder (160a), and thereby in use, during rotational motion of the cam set (20) on the axis (70), a scissor action by the cam tracks (100) of the respective inner, middle and outer cams (40, 50, 60) constrains the first cam follower assembly (30a) to move in an axial direction.

Description

AN APPARATUS, AN ENGINE, A PUMP, AN ELECTRICAL MOTOR AND/OR AN

ELECTRICAL GENERATOR

Field of the Invention

The present invention relates to an apparatus, an engine, a pump, an electrical motor and/or an electrical generator.

The invention has been developed primarily for use in reciprocating piston engines and will be described hereinafter with reference to this application. However, it will be appreciated that the invention is not limited to this particular field of use.

Background

A reciprocating piston engine, such as an internal combustion (or "IC") engine, converts gas pressure into an output torque at a rotating shaft. Typically, in the case of the most common form of IC engine, a piston reciprocates in a bore of a cylinder due to the pressure exerted on the piston by the combustion of a fuel-air mixture. The piston is mechanically coupled to a

"big end" crank shaft bearing by a connecting rod ("conrod"). The big end bearing has an axis which is parallel to, but radially offset from, the rotational axis of the crank shaft, and thus axial forces acting on the piston are able to rotate and generate an output torque at the crank shaft. However, it is this mechanical arrangement of the piston, the conrod and the crank shaft which is often a substantial source of noise, wear and energy inefficiencies in typical IC engines. To overcome some of the limitations and inefficiencies associated with these most common form of IC engine, prior art IC engine designs have been proposed in which the crank shaft and conrod arrangement is replaced with two multilobate cams as described in Australian Patent Application No. 63496/96. Some of the limitations and power inefficiencies have been ameliorated by such IC engines.

The present invention seeks to provide an apparatus, an engine, a pump, an electrical motor and/or an electrical generator which will overcome or substantially ameliorate at least some of the deficiencies of the prior art, or to at least provide an alternative. It is to be understood that, if any prior art information is referred to herein, such reference does not constitute an admission that the information forms part of the common general knowledge in the art, in Australia or any other country.

Summary

According to one aspect, there is provided an apparatus, comprising: a cam set of three barrel cams concentrically disposed about a common rotational axis, the cam set comprising a radially inner, middle and outer cam with respective multilobate cam tracks disposed at a first axial end region of the cam set, the inner and outer cams synchronised to rotate in use at the same angular velocity, the middle cam arranged to counter rotate in use with an equal and opposite angular velocity with respect to the inner and outer cams; and at least one first cam follower assembly comprising three first roller followers supported for independent rotation, the first roller followers engaging with the cam track of the respective inner, middle or outer cam, the first cam follower assembly connected to a reciprocating first piston slidable in an axially orientated first cylinder, and thereby in use, during rotational motion of the cam set on the axis, a scissor action by the cam tracks of the respective inner, middle and outer cams constrains the first cam follower assembly to move in an axial direction.

Advantageously, the apparatus is able to convert linear motion to rotational motion.

Beneficially, the apparatus is able to substantially replace a conventional crank shaft and conrod arrangement found in conventional reciprocating engines and pumps and function in a more efficient manner.

Advantageously, torsional movement of the first cam follower assembly is able to be substantially reduced when the scissor action constrains the first cam follower assembly to move in an axial direction in use as force components that are transverse to the axial direction and applied to the first cam follower assembly are able to be substantially balanced and generate a negligible torsional moment. Therefore, torsional movement of the first piston is able to be substantially reduced within the first cylinder in use such that friction between the first piston and the first cylinder is substantially reduced. Thus, the first piston is able to reciprocate within the first cylinder more efficiently in use. Advantageously, the cam track of the respective inner, middle and outer cam allows the reciprocation of the first piston within the first cylinder to be more easily and effectively controlled. Therefore, the first piston is able to be easily positioned within the first cylinder during use, for example during the cycling of a conventional IC engine, to produce a more tailored or more efficient output.

Preferably, the multilobate cam tracks of the inner and outer cams have a substantially matching cam form which is a rotational mirror image of the cam form of the multilobate cam track of the middle cam.

Advantageously, force components that are transverse to the axial direction and applied to the first cam follower assembly by the inner and outer cams are equal and substantially balanced by force components that are transverse to the axial direction and applied to the first cam follower assembly by the middle cam. Beneficially, the risk of a moment being applied to the first cam follower assembly by the inner and outer cams is substantially reduced.

Advantageously, the inner, middle and outer cams are able to rotate with angular velocities of substantially equal magnitude. Beneficially, the need for complicated gearing between the inner, middle and outer cams is substantially reduced. Therefore, the apparatus requires fewer parts and is substantially more economical to manufacture.

Preferably, the apparatus further comprises a shaft and wherein one or more of the inner, middle and outer cams are geared with respect to the shaft. Advantageously, although the direction of rotation of the middle cam is opposed to the direction of rotation of the inner and outer cams, the rotation of the inner, middle and outer cams can be utilised to rotate the shaft and thereby increase the torque of the shaft.

Preferably, the inner and outer cams are rotationally fixed to the shaft and wherein the shaft is aligned with the axis. Advantageously, the rotation of the inner and outer cams directly rotates the shaft and thus substantially increases the efficiency of the apparatus as the loss of energy between the inner and outer cams and the shaft is substantially reduced. Furthermore, the apparatus requires fewer parts and is substantially more economical to manufacture. Preferably, the middle cam is rotationally fixed to the shaft and wherein the shaft is aligned with the axis.

Advantageously, the rotation of middle cam directly rotates the shaft and thus substantially increases the efficiency of the apparatus as the loss of energy between the middle cam and the shaft is substantially reduced. Furthermore, the apparatus requires fewer parts and is substantially more economical to manufacture.

Preferably, the inner, middle and outer cams also comprise respective multilobate cam tracks disposed at a second axial end region of the cam set.

Preferably, the apparatus further comprises at least a second cam follower assembly comprising three second roller followers supported for independent rotation, each of the second roller followers engaging with the cam track of the respective inner, middle or outer cam at the second axial end region of the cam set, the second cam follower assembly connected to a reciprocating second piston slidable in an axially orientated second cylinder.

Advantageously, the reciprocation of the second piston within the second cylinder rotates the cam set. Beneficially, the apparatus is able to substantially replace a conventional crank shaft and conrod arrangement found in conventional reciprocating engines and pumps and function in a more efficient manner.

Advantageously, the reciprocation of the second piston is able to substantially aid the reciprocation of the first piston in rotating the cam set. Therefore, the cam set is able to rotate with substantially increased power.

Preferably, the reciprocation of the first and second pistons is in phase.

Advantageously, the reciprocation of the first piston aids in the reciprocation of the second piston. Simultaneously, the reciprocation of the second piston aids in the reciprocation of the first piston. Therefore, the first and second pistons are able to rotate the cam set more efficiently.

Preferably, the apparatus further comprises a fluid interconnection between respective breather regions under the first and second pistons in the first and second cylinders respectively. Advantageously, the first and second pistons reciprocating in phase is aided by the fluid interconnection. Beneficially, the requirement for the first and second pistons to be mechanically coupled is substantially reduced.

Preferably, the multilobate cam tracks disposed at the first axial end region of the cam set are in the form of circumferential grooves, thereby axially mechanically constraining the respective first roller followers.

Advantageously, the circumferential grooves substantially reduce the risk of the first roller follower from disengaging the multilobate cam tracks. Therefore, the stability and the efficiency of the apparatus are substantially increased. Preferably, the multilobate cam tracks disposed at the second axial end region of the cam set are in the form of circumferential grooves, thereby axially mechanically constraining the respective second roller followers.

Advantageously, the circumferential grooves substantially reduce the risk of the first roller follower from disengaging the multilobate cam tracks. Therefore, the stability and the efficiency of the apparatus are substantially increased in use.

Preferably, the three first roller followers are supported for independent rotation about a radially orientated first follower axle.

Preferably, the first follower axle comprises multiple axle segments.

Preferably, the scissor action further constrains the first follower axle to have a radial orientation.

Advantageously, torsional movement of the first cam follower assembly is able to be substantially reduced, when the scissor action constrains the first follower axle to have a radial orientation, as force components that are transverse to and applied to the first follower axle are able to be substantially balanced and thereby generate negligible torsional moment. Therefore, torsional movement of the first piston is able to be substantially reduced within the first cylinder in use such that friction between the first piston and the first cylinder is substantially reduced. Thus, the first piston is able to reciprocate within the first cylinder more efficiently in use. Preferably, the three second roller followers are supported for independent rotation about a radially orientated second follower axle.

Preferably, the second follower axle comprises multiple axle segments.

Preferably, the scissor action further constrains the second follower axle to have a radial orientation.

Advantageously, torsional movement of the second cam follower assembly is able to be substantially reduced, when the scissor action constrains the second follower axle to have a radial orientation, as force components that are transverse to and applied to the second follower axle are able to be substantially balanced and thereby generate negligible torsional moment. Therefore, torsional movement of the second piston is able to be substantially reduced within the second cylinder in use such that friction between the second piston and the second cylinder is substantially reduced. Thus, the second piston is able to reciprocate within the second cylinder more efficiently in use.

According to another aspect, there is provided an engine, comprising: an apparatus as described in any one of the above paragraphs, the engine being arranged to generate an output torque at the shaft in use.

Advantageously, the engine is more efficient than conventional engines as there is no need for a conventional crank shaft and conrod arrangement.

Advantageously, the engine is able to be substantially more compact when compared to conventional engines. Furthermore, the engine requires fewer parts and is substantially easier to manufacture.

Preferably, the engine is any one of the following engines: an internal combustion engine; a Stirling cycle engine; a steam powered engine; a propellant powered engine; a hydraulic motor; or a pneumatic motor. According to another aspect, there is provided a pump, comprising: an apparatus as described in any one of the above paragraphs, the pump being arranged such that a fluid is pressurized in the first cylinder as a result of an input torque applied at the shaft in use.

Advantageously, the fluid pump is more efficient than conventional pumps as there is no need for a conventional crank shaft and conrod arrangement.

Advantageously, the pump is able to be substantially more compact compared to conventional pumps. Furthermore, the pump requires fewer parts and is substantially easier to manufacture.

Preferably, the pump is any one of the following pumps: a liquid fluid pump; a gaseous fluid pump; a mixed-phase fluid pump; or a compressor.

According to another aspect, there is provided an electrical motor, comprising: an apparatus as described in any one of the above paragraphs, the electrical motor being arranged to generate an output torque at the shaft in use.

Advantageously, the electrical motor is able to assist another means, reciprocating the first and/or second pistons, in rotating the shaft. Therefore, more power is able to be applied to the shaft in use.

Advantageously, the electrical motor is able to rotate the shaft when there is no other means to reciprocate the first and/or second pistons.

Preferably, the electrical motor further comprises a rotor arrangement attached to the outer cam and a stator arrangement located substantially around the rotor arrangement such that when the electrical motor is energised in use, the rotor arrangement applies a torque to the shaft.

Advantageously, electromagnetic forces are applied to the rotor arrangement to cause the outer cam to rotate and thereby rotating the shaft in use. Preferably, the stator arrangement comprises a magnetising means to form two or more magnetic poles.

Advantageously, the stator arrangement provides a stationary magnetic field for the rotor arrangement.

Preferably, the magnetising means comprises any one of the following magnets: permanent magnets; or electromagnets.

Preferably, the rotor arrangement comprises two or more armature members, each having an electrical winding adapted to induce a magnetic field in use.

Advantageously, the magnetic fields generated by the armature members cause

electromagnetic forces to be applied to the rotor arrangement.

According to another aspect, there is provided an electrical generator, comprising: an apparatus as described in any one of the above paragraphs, the electrical generator being arranged to generate an electrical current in use.

Advantageously, the electrical generator is able to generate an electrical current to electrically power other equipment or recharge batteries.

Preferably, the electrical generator further comprises a rotor arrangement attached to the outer cam and a stator arrangement located substantially around the rotor arrangement such that when the outer cam rotates in use, the electrical generator generates the electric current.

Advantageously, reciprocation of the first and/or second pistons causes the electrical generator to generate the electric current. Preferably, the stator arrangement comprises a magnetising means to form two or more magnetic poles.

Advantageously, the stator arrangement provides a stationary magnetic field for the rotor arrangement. Preferably, the magnetising means comprises any one of the following magnets: permanent magnets; or electromagnets.

Preferably, the rotor arrangement comprises two or more armature members, each having an electrical winding adapted such that in use an electric current is induced therein. Other aspects of the invention are also disclosed. Brief Description of the Drawings

Notwithstanding any other forms which may fall within the scope of the present invention, preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:

Fig. 1 is a sectional elevation view of an engine with cam tracks disposed on both first and second axial end regions of a cam set in accordance with a preferred embodiment of the present invention;

Fig. 2 is a front elevation view of the engine of Fig. 1;

Fig. 3 is a back elevation view of the engine of Fig. 1;

Fig. 4 is a two-dimensional unwrapped view of an inner, middle and outer cam with cam tracks and cam follower assemblies engaging the cam tracks in one position;

Fig. 5 is a two-dimensional unwrapped view of the inner, middle and outer cam with cam tracks of Fig. 4 and cam follower assemblies of Fig. 4 engaging the cam tracks in another position;

Fig. 6 is a two-dimensional unwrapped view of the inner, middle and outer cam with cam tracks of Fig. 4 and cam follower assemblies of Fig. 4 engaging the cam tracks in still another position; Fig. 7 is a sectional elevation view of the middle cam of Fig. 4 and differential gearing with a shaft;

Fig. 8 is a schematic view of the cam follower assemblies of Fig. 4 with fluid interconnections, having pistons moving from one position shown in Fig. 8(i) to another position shown in Fig. 8(H);

Fig. 9 is sectional elevation view of the engine with cam tracks on one axial end region in accordance with another preferred embodiment of the present invention;

Fig. 10(i) is a front elevation view of the engine in Fig. 9 with 16 cam follower assemblies, pistons and cylinders and Fig. 10(ii) is a front elevation view of the engine in Fig. 9 with 8 cam follower assemblies, pistons and cylinders in accordance with another preferred embodiment of the present invention; and

Fig. l l(i) is a sectional elevation view of an engine that is able to function as an electrical generator or electric motor in accordance with another embodiment of the present invention and Fig. 11(H) is a back elevation view of the engine of Fig. 1 l(i). Detailed Description of Specific Embodiments

It should be noted in the following description that like or the same reference numerals in different embodiments denote the same or similar features.

According to an aspect of the present invention, there is provided a two-stroke IC engine. It will be appreciated that, in other embodiments, the engine cycle may be based on any number of strokes, for example the IC engine may be a four-stroke engine. It will also be appreciated that, in still other embodiments, the engine may be any other type of piston engine such as a sterling cycle engine, steam powered engine, a propellant powered engine, a hydraulic motor or a pneumatic motor. Piston engines convert pressure exerted on one or more pistons to an output torque at a rotating shaft in use i.e. energy is transferred from a working fluid to a rotating shaft.

The engine comprises an apparatus 10 as shown in Figs. 1 to 3. The apparatus 10 comprises a cam set 20 and eight cam follower assemblies 30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h. Although it is shown in Fig. 1 that there are eight follower assemblies 30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h, in other embodiments, there may be one or more follower assemblies. The cam set 20 comprises three barrel cams: an inner cam 40, a middle cam 50 and an outer cam 60. Each of the cams 40, 50, 60 is tubular in shape and has a circular transverse cross-section. The cams 40, 50, 60 are concentrically disposed about a common rotational axis 70. In this embodiment, the outer cam 60 has the largest diameter and is radially furthest from the common rotational axis 70 compared to the inner 40 and middle 50 cams. The middle cam 50 has an incrementally smaller diameter compared to the outer cam 60 such that the middle cam 50 is within the outer cam 60 and radially closer to the common rotational axis 70. The inner cam 40 has an incrementally smaller diameter compared to the middle cam 50 such that the inner cam 40 is within the middle cam 50 and radially closer to the common rotational axis 70. In this embodiment, the inner cam 40 is rotationally fixed to the outer cam 60 such that the inner cam 40 and outer cam 60 rotate, in use, at the same angular velocity. The middle cam 50 rotates, in use, at an angular velocity that is equal in magnitude but opposite in direction compared to the angular velocity of the inner cam 40 and outer cam 60.

Referring to Figs. 2 to 6, each of the cams 40, 50, 60 has two axial end regions 80, 90 and multilobate cam tracks disposed on the each of these axial end regions 80, 90. Each of the multilobate cam tracks comprise four lobes 100 located around the circumference of the respective axial end regions 80, 90 and extending axially outwardly from the respective axial end regions 80, 90 such that a pseudo-sinusoidal cam form is defined, as shown in Figs. 4 to 6. The cam forms of the inner cam 40 and the outer cam 60 substantially match and are always in phase. The cam form of the middle cam 50 is a substantially rotational mirror image of the cam forms of the inner cam 40 and the outer cam 60. In each of the cams 40, 50, 60, the cam form of the first axial end region 80 is matching and always in phase with the cam form of the second axial end region 90.

Each of the cam follower assemblies 30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h comprises three roller followers 110a, 110b, 110c and a follower axle. In each of the follower assemblies 30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h, the follower axle is orientated radially from the common rotational axis 70 and the roller followers 110a, 110b, 110c are rotatably supported by the follower axle such that the roller followers 110a, 110b, 110c are able to independently rotate. In this embodiment, each of the roller followers 110a, 110b, 110c of the first cam follower assemblies 30a, 30b, 30c, 30d engage the multilobate cam track of the first axial end region 80 of the respective cams 40, 50, 60. Specifically, the roller follower 110a engages the multilobate cam track of the inner cam 40, the roller follower 110b engages the multilobate cam track of the middle cam 50 and the roller follower 110c engages the multilobate cam track of the outer cam 60. Similarly, each of the roller followers 110a, 110b, 110c of the second cam follower assemblies 30e, 30f, 30g, 30h engage the multilobate cam track of the second axial end region 90 of the respective cams 40, 50, 60. Specifically, the roller follower 110a engages the multilobate cam track of the inner cam 40, the roller follower 110b engages the multilobate cam track of the middle cam 50 and the roller follower 110a engages the multilobate cam track of the outer cam 60. In other embodiments not shown, each of the follower axles of the cam follower assemblies 30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h comprises multiple axle segments sharing a common radially orientated axis

It will be appreciated that, during rotational motion of the cam set 20 in use, a scissor action by the cam tracks of the respective inner 40, middle 50 and outer 60 cams, constrains the cam follower assemblies 30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h to move in an axial direction parallel with the common rotational axis 70. For example and as shown in Figs. 4, each of the relevant roller followers 110a, 110b, and 110c of the second cam follower assemblies 30e, 30f, 30g, 30h are located between one of the lobes 100 of the inner cam 40, one of lobes 100 of the outer cam 60 and one of the lobes 100 of the middle cam 50. As the cam set 20 rotates, the lobe 100 of the inner cam 40 and the lobe 100 of the outer cam 60 move towards the lobe 100 of the middle cam 50. Simultaneously, the lobe 100 of the middle cam 50 moves towards the lobes 100 of the inner cam 40 and outer cam 60. Consequently, the relevant roller followers 110a, 110b, and 110c are constrained by the lobes 100 of the inner cam 40, middle cam 50, and outer cam 50 to move outwardly from the second axial end region 90 in the axial direction. Transverse force components with respect to the common rotational axis 70 that are applied to the roller followers 110a, 110c as the follower axle is constrained is balanced by the transverse force components that are applied to the roller followers 110b generating a substantially zero torsional moment, such that transverse movement is prevented and the follower axle is maintained in a radial orientation with respect to the common rotational axis 70.

Each of the cam follower assemblies 30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h further comprises a member 130 perpendicularly extending from the follower axle such that the member 130 is orientated parallel with the common rotational axis 70 and extending outward away from the respective axial end regions 80, 90 to a free end. The first cam follower assemblies 30a, 30b, 30c, 30d are arranged around the first axial end region 80 such that the first cam follower assemblies 30a, 30c are diametrically opposed and the follower first cam follower assemblies 30b, 30d are diametrically opposed such that the follower axles of the first cam follower assemblies 30a, 30c are orientated perpendicularly to the follower axles of the first cam follower assemblies 30b, 30d. Similarly, the second cam follower assemblies 30e, 30f, 30g, 30h are arranged around the second axial end region 90 such that the second cam follower assemblies 30e, 30g are diametrically opposed and the second cam follower assemblies 30f, 30h are diametrically opposed such that the follower axles of the second cam follower assemblies 30e, 30g are orientated perpendicularly to the follower axles of the second cam follower assemblies 30f, 30h. Furthermore, the members 130 of the first and second cam follower assemblies 30a, 30e are axially aligned, the members 130 of the first and second cam follower assemblies 30b, 30f are axially aligned, the members 130 of the first and second cam follower assemblies 30c, 30g are axially aligned, and the members 130 of the first and second cam follower assemblies 30d, 30h are axially aligned.

The engine further comprises eight pistons 150a, 150b and eight cylinders 160a, 160b. Each of the pistons 150a, 150b is housed within a respective cylinder 160a, 160b such that the pistons 150a, 150b are able to linearly reciprocate therein. Each of the first pistons 150a attaches to the free end of the member 130 of a respective first cam follower assembly 30a, 30b, 30c, 30d, and the respective first cylinders 160a are orientated in line with the member 130 of the respective first cam follower assembly 30a, 30b, 30c, 30d such that the first pistons 150a are able to linearly reciprocate in line with the member 130 of the respective first cam follower assembly 30a, 30b, 30c, 30d. Each of the second pistons 150b attaches to the free end of the member 130 of a respective second cam follower assembly 30e, 30f, 30g, 30h, and the respective second cylinders 160b are orientated in line with the member 130 of the respective cam follower assembly 30e, 30f, 30g, 30h such that the second pistons 150b are able to linearly reciprocate in line with the member 130 of the respective cam follower assembly 30e, 30f, 30g, 30h.

It will be appreciated that, in other embodiments not shown, the apparatus 10 may not comprise members 130 but instead have the first and second pistons 150a, 150b directly attached to the respective follower axles, or segmented axles, of the respective first cam follower assemblies 30a, 30b, 30c, 30d and second cam follower assemblies 30e, 30f, 30g, 30h. In such embodiments, the apparatus 10 would require fewer parts and is more economical to manufacture. The apparatus 10 further comprises a engine output shaft 170 extending through the inner cam 40. The shaft 170 is orientated to be collinear with the common rotational axis 70 and is rotatable about the common rotational axis 70. In this embodiment, the inner cam 40 and the outer cam 60 are rotationally fixed to the shaft 170 such that the rotation of the inner cam 40 and the outer cam 60 directly rotates the shaft 170 (with a 1: 1 ratio). As shown in Fig. 7, the middle cam 50 is synchronized to rotate in an equal and opposite direction to the shaft 170 (and hence to inner cam 40 and outer cam 60) by the use of a concentric planetary gearing arrangement, well known in the art of gearing. It will be appreciated that, in other embodiments not shown, the middle cam 50 may be fixed to the shaft 170 and the inner cam 40 and outer cam 50 set may be geared with respect to the shaft 170. Still alternatively, both the inner cam 40 and outer cam 60 set, and the middle cam 50, may be geared with respect to the shaft 170.

During a cycle of the engine, for example, a first piston 150a is positioned at the top-dead- centre (TDC) and an opposed second piston 150b is positioned at the bottom-dead-centre (BDC) as shown in Fig. 4. The combustion of a fuel-air mixture in the relevant first cylinder 160a above the first piston 150a causes a significant increase in pressure and thus forces the first piston 150a to move towards the BDC. In turn, the respective first cam follower assembly 30a, 30b, 30c, 30d is forced to move towards the first axial end region 80 and cause transverse force components, with respect to the common rotational axis 70, to be applied to the adjacent lobes 100 of the inner cam 40, the middle cam 50, and the outer cam 60. Consequently, the inner cam 40, the middle cam 50, and the outer cam 60 rotate and therefore generate an output rotation of the shaft 170. It will be appreciated that the transverse force components applied to the adjacent lobes 100 of the inner cam 40 and the outer cam 60 are opposite in direction to the transverse force components applied to the adjacent lobe 100 of the middle cam 50. Simultaneously, the rotation of the cam set 20 causes the scissor action on the opposed second cam follower assembly 30e, 30f, 30g, 30h such that the relevant second cam follower assembly 30e, 30f, 30g, 30h moves away from the axial end region 90. In turn, the opposed second piston 150b linearly moves to the TDC. Furthermore, the combustion of a fuel-air mixture in the relevant second cylinder 160b above the second piston 150b forces the second piston 150b to move towards the BDC. In turn, the respective second cam follow assembly 30e, 30f, 30g, 30h is forced to move towards the axial end region 90 and cause transverse force components with respect to the common rotational axis 70, to be applied to the adjacent lobes 100 of the inner cam 40, the middle cam 50, and the outer cam 60. Consequently, the inner cam 40, the middle cam 50 and the outer cam 60 rotate and therefore generate an output rotation of the shaft 170. It will be appreciated that the transverse force components applied to the adjacent lobes 100 of the inner cam 40 and the outer cam 60 are opposite in direction compared to the transverse force components applied to the adjacent lobe 100 of the middle cam 50. Simultaneously, the rotation of the cam set 20 causes the scissor action on to the first cam follower assembly 30a, 30b, 30c, 30d such that the first cam follower assembly 30a, 30b, 30c, 30d moves away from the axial end region 80. In turn, the first piston 150a linearly moves to the TDC. It will be appreciated that the cycle is continually repeated during use of the engine to generate an output torque on the shaft 170. It will be appreciated that, in the case of the embodiment shown, the reciprocation of the first and second pistons 150a, 150b are in phase such that the reciprocation of the first pistons 150a aids in the reciprocation of the respective opposed second pistons 150b and vice-versa, allowing the apparatus 10 to function efficiently. However, in other embodiments not shown, the reciprocation of the first and second pistons may be out of phase, for example 180 degrees out of phase, in which circumstances the first pistons 150a will achieve TDC at the same time that the opposed second pistons 150b also achieve TDC. This embodiment will of course achieve perfect axial balance of the engine, but disadvantageously, will generate a large periodic torque output at the shaft 170.

As the rotational motion of the inner cam 40, middle cam 50 and outer cam 60 all contribute to the rotation of the shaft 170, more torque is applied to the shaft 170. Also, as the rotation of the inner cam 40 and the outer cam 60 cams rotates the shaft 170, the apparatus 10 is more efficient because the loss of energy between the inner cam 40 and the outer cam 60 and the shaft 170 is reduced. Furthermore, the apparatus 10 requires fewer parts and is more economical to manufacture. The cam tracks of the inner cam 40, middle cam 50 and outer cam 60 allows the reciprocation of the first and second pistons 150a, 150b to be more easily and effectively controlled by changing the shape of the lobes 100. For example, a steeper gradient on one side of the lobes 100 is able to make the first and second pistons 150a, 150b move more quickly form the BDC to the TDC for a given angular velocity of the output shaft 170. In the embodiment shown the cam tracks are pseudo-sinusoidal, however the cam tracks in other not shown embodiments may be far from sinusoidal. In some cases the cam tracks may be almost a straight saw-tooth (i.e. "W") in shape, generating a region of near-constant velocity ratio between the axial velocity of the first and second pistons 150, 150b and the angular velocity of the output shaft 170. Beneficially also, the first and second pistons 150a, 150b are able to be easily positioned within the respective first and second cylinders 160a, 160b to produce a more tailored or more efficient output. It will be appreciated that torsional movement of the cam follower assemblies 30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h are able to be reduced when the scissor action constrains the cam follower assembly 30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h to move in the axial direction in use as force components that are transverse to the common rotational axis 70 and applied to the cam follower assemblies 30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h are able to be balanced. Therefore, torsional movement of each of the first and second pistons 150a, 150b is able to be reduced within the respective first and second cylinders 160a, 160b in use such that friction between the first and second pistons 150a, 150b and the respective first and second cylinders 160a, 160b is reduced. Thus, the first and second pistons 150a, 150b are able to reciprocate within the respective first and second cylinders 160a, 160b more efficiently in use. The apparatus 10 is able to convert linear reciprocating motion of the first and second pistons 150a, 150b to rotational motion of the shaft 170. Beneficially, the apparatus 10 is able to substantially replace a conventional crank shaft and conrod arrangement found in conventional IC engines, allowing the engine to function more efficiently. Also, the engine is able to be more compact compared to conventional IC engines due to the orientation and positioning of the first and second pistons 150a, 150b and corresponding first and second cylinders 160a, 160b.

Referring to Figs. 8(i) and 8(ii), in this embodiment, each of the first and second cylinders 160a, 160b have a breather region under the respective first and second pistons 150a, 150b therein. The apparatus 10 further comprises a fluid interconnection 180 between breather regions of each of the first cylinders 160a and the corresponding opposed second cylinder 160b. It will be appreciated that the reciprocation of the pistons 150a, 150b will either reduce or enlarge the volume of the breather regions of the cylinders 160a, 160b displacing air between the breather regions. Therefore, the pistons 150a, 150b are better maintained in-phase without the need for a mechanical coupling between each first piston 150a and the corresponding opposed second piston 150b. However, in other not shown embodiments, a mechanical coupling can actually be employed between each first piston 150a and the corresponding opposed second piston 150b, mechanically maintaining this in-phase relationship.

In another embodiment, as shown in Fig. 9, the cam tracks are only disposed on the first axial end region 80 of the cam set 20, and the apparatus 10 only comprises first cam follower assemblies 30a, 30b, 30c, 30d, four first pistons 150a and four first cylinders 160a. It will be appreciated that the rotational momentum of the cam set 20 is utilized, after being rotated when the first pistons 150a move from TDC to BDC, to cause the scissor action on the first cam follower assemblies 30a, 30b, 30c, 30d to linearly move the first pistons 150a from BDC to TDC. In another embodiment not shown, the cam tracks are in the form of circumferential grooves on the outside periphery or inside periphery of the respective inner cam 40, middle cam 50 and outer cam 60. These circumferential grooves are adapted to receive and precisely engage with the respective roller followers 110a, 110b, 110c, thereby axially mechanically constraining the roller followers 110a, 110b, 110c and they follow the cam form of the cam tracks. The use of circumferential grooves reduce the risk of the roller followers 110a, 110b, 110c from disengaging from the multilobate cam tracks in use, for example as of a result of the linear inertia of the cam follower assembly and piston combination at TDC. Therefore, the stability and the efficiency of the apparatus 10 are increased.

In another embodiment, the apparatus 10 comprises one or more cam follower assemblies 190, each of the cam follower assemblies 190 being attached to a respective piston within a respective cylinder. For example, and as shown in Figs. 10 (i) and 10(ii), there can be 16 or 8 cam follower assemblies 190, each having respective roller followers 110a, 110b, 110c engaging the cam tracks of the respective inner cam 40, middle cam 50, and outer cam 60 at the first axial end region 80. In another aspect of the invention, there is provided a piston pump using the same or similar apparatus as described above, again negating the need for a crank shaft and conrod arrangement with the various accompanying advantages as previously described. The pump may be any type of piston pump including a liquid fluid pump, a gaseous fluid pump, a mixed-phase fluid pump, or a compressor. The pump operates basically in reverse principle to an engine: in a pump fluid is pressurized in the cylinder as a result of an input torque applied at a rotating shaft in use i.e. energy is transferred from the rotating shaft to the fluid. Referring to Figs. l l(i) and 11 (ii), in another embodiment, the engine is able to function as a brushed direct current (DC) electrical generator and a brushed DC electrical motor. It will be appreciated that, in other embodiments, the engine is able to function as any other type of electrical generator or electrical motor such as a brushless DC generator, a brushless DC motor, a brushed AC motor, a brushed AC generator, a brushless AC motor or a brushless AC generator.

In this embodiment, the engine further comprises a battery, a rotor arrangement and a stator arrangement. The rotor arrangement is attached to the outer cam 60 and the stator arrangement is located around the rotor arrangement such that the outer cam 60 is able to rotate therein. The stator arrangement comprises a case 200 that is cylindrical in shape and hollow. The case 200 has an inner and outer surface that both have a transverse cross-section that is circular in shape. The stator arrangement further comprises two permanent magnets 210a, 210b adapted to form a stationary magnetic field with two magnetic poles. The permanent magnet 210a has a north pole and the permanent magnet 210b has a south pole. Each of the permanent magnets 210a, 210b has a transverse cross-section that is semi-circular in shape. The permanent magnets 210a, 210b are attached to the inner surface of the case 200 such that the permanent magnet 210a is diametrically opposed to the permanent magnet 210b. In other embodiments, there are two or more permanent magnets forming two or more magnetic poles. Furthermore, in other embodiments, the permanent magnets 210a, 210b may be replaced by electromagnets.

The rotor arrangement comprises four armature members 220a, 220b, 220c, 220d extending radially outwardly from the outer cam 60. Although it is shown in Fig. 11 (ii) that there are four armature members 220a, 220b, 220c, 220d, in other embodiments, there may be two or more armature members. The armature members 220a, 220b, 220c, 220d are evenly spaced apart such that the armature members 220a, 220c are diametrically opposed and the armature members 220b, 220d are diametrically opposed. In this embodiment, the armature members 220a, 220b, 220c, 220d are manufactured from a ferromagnetic metal such as iron. In other embodiments, the armature members 220a, 220b, 220c, 220d may be manufactured from a ferromagnetic compound such as a ferrite. Each of the armature members 220a, 220b, 220c, 220d have a free end that is proximal to the permanent magnets 210a, 210b in use. Each of the free ends have a transverse cross-section that is semi-circular in shape such that the free ends of the armature members 220a, 220b, 220c, 220d are able to be close to the permanent magnets 210a, 210b in use and yet not contact the permanent magnets 210a, 210b as the armature members 220a, 220b, 220c, 220d rotate. It will be appreciated that the free ends being close to the permanent magnets 210a, 210b reduces the air gap between them and therefore orientate the magnetic flux from the permanent magnets 210a, 210b in a more efficient manner in use. In this embodiment, each of the armature members 220a, 220b, 220c, 220d is laminated to prevent the formation of eddy currents within the armature members 220a, 220b, 220c, 220d and therefore reduce energy loss and heat formation in use. Each of the armature members 220a, 220b, 220c, 220d has an electric winding 230. The electric windings 230 are conductive copper wires that are wound into coils. It will be appreciated that, when an electrical current is applied to an electric winding 230, a magnetic field will be induced and cause the formation of a magnetic pole at the respective armature member 220a, 220b, 220c, 220d. It will also be appreciated that the electric windings 230 are wound in certain directions such that when an electrical current is applied to the electric windings 230, the magnetic pole formed at the armature member 220a will be opposite to the magnetic pole formed at the armature member 220c. Similarly, the magnetic pole formed at the armature member 220b will be opposite to the magnetic pole formed at the armature member 220d.

The engine further comprises a mechanical commutator 240 that is electrically connected in a circuit to the battery and the electric windings 230 of the armature members 220a, 220b, 220c, 220d. The commutator 240 is adapted to periodically reverse the current direction between each of the electric windings 230 and the battery as the outer cam 60 rotates. It will be appreciated that the electrical connections between the electric windings 230 and the commutator 240 are via brushes such that the rotor arrangement is able to rotate freely.

When the engine functions as the DC motor, electrical current is applied to the commutator 240 and then to the electric windings 230 of the armature members 220a, 220b, 220c, 220d by the battery. As such, magnetic poles are formed at the armature members 220a, 220b, 220c, 220d. Referring to Fig. 11 (ii), for example, in one instance the armature members 220a, 220d have north poles and the armature members 220b, 220c have south poles. Therefore, the armature member 220a is attracted to the permanent magnet 210b, the armature member 220b is repelled from the permanent magnet 210b, the armature member 220c is attracted to the permanent magnet 210a and the armature member 220d is repelled by the permanent magnet 210a. Thus, when viewed from the back, the rotor arrangement moves clockwise rotating the outer cam 60 and consequently the shaft 170. When the armature member 220d has moved to the original position of the armature member 220a, the commutator reverses the electrical current being applied to the electric windings 230 of each of the armature members 220a, 220b, 220c, 220d such that the magnetic poles formed at the armature members 220a, 220b, 220c, 220d are reversed. Therefore, the rotor arrangement will continue to rotate clockwise and therefore rotate the outer cam 60 and the shaft 170. It will be appreciated that, in certain embodiments, the engine further comprises a microcontroller that is electrically connected to the circuit. The microcontroller is able to control the average voltage experienced by the electrical windings 230 by pulse- width modulation (PWM). As speed of the rotation of the rotor arrangement is proportional to the voltage applied, the microcontroller is able to control the speed at which the rotor arrangement rotates and therefore control the speed of the rotation of the shaft 170.

Beneficially, while the engine is rotating the shaft 170 by reciprocating the pistons 150a, 150b in a manner described in any one of the above paragraphs, electrical current can be applied to the rotor arrangement to further assist in the rotation of the shaft 170. Therefore, more power is transmitted to the shaft 170 in use. Furthermore, the engine does not need to combust fuel to reciprocate the pistons 150a, 150b, 150c, 150d to rotate the shaft 170, but could rely solely upon the motor effect to rotate the shaft 170.

When the engine functions as the DC generator, the outer cam 60 is rotated by the reciprocation of the pistons 150a, 150b in a manner described in any one of the above paragraphs. The rotation of the outer cam 60 rotates the rotor arrangement with respect to the stator arrangement. Therefore, the armature members 220a, 220b, 220c, 220d are rotated within the stationary magnetic field formed by the permanent magnets 210a, 210b. The rapidly changing magnetic flux experienced by the electrical windings 230 of each of the armature members 220a, 220b, 220c, 220d during rotation will induce an electrical current in the electrical windings 230. It will be appreciated that the induced electrical current in each of the electrical windings 230 will be of varying direction at different instances of rotation. However, the commutator will allow a direct current to be applied to the battery for recharging as the electrical current is reversed periodically during rotation.

It will be appreciated that any other electrical equipment may be electrically connected to the circuit to be powered by the electrical generator. It will also be appreciated that the arrangements described above could be used in hybrid vehicles that require an internal combustion engine, an electrical generator and an electrical motor. As the engine described in any one of the above paragraphs is able to function as an electrical generator and an electrical motor, a hybrid vehicle using this engine may be manufactured with fewer parts and therefore reduce the complexity and price of the vehicle.

Interpretation

Embodiments:

Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment, but may. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure, in one or more embodiments.

Similarly it should be appreciated that in the above description of example embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the Detailed Description of Specific Embodiments are hereby expressly incorporated into this Detailed Description of Specific Embodiments, with each claim standing on its own as a separate embodiment of this invention.

Furthermore, while some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

Different Instances of Objects

As used herein, unless otherwise specified the use of the ordinal adjectives "first", "second", "third", etc., to describe a common object, merely indicate that different instances of like objects are being referred to, and are not intended to imply that the objects so described must be in a given sequence, either temporally, spatially, in ranking, or in any other manner.

Specific Details

In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practiced without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

Terminology

In describing the preferred embodiment of the invention illustrated in the drawings, specific terminology will be resorted to for the sake of clarity. However, the invention is not intended to be limited to the specific terms so selected, and it is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar technical purpose. Terms such as "forward", "rearward", "radially", "peripherally", "upwardly", "downwardly", and the like are used as words of convenience to provide reference points and are not to be construed as limiting terms.

Comprising and Including

In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" are used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

Any one of the terms: including or which includes or that includes as used herein is also an open term that also means including at least the elements/features that follow the term, but not excluding others. Thus, including is synonymous with and means comprising.

Scope of Invention

Thus, while there has been described what are believed to be the preferred embodiments of the invention, those skilled in the art will recognize that other and further modifications may be made thereto without departing from the spirit of the invention, and it is intended to claim all such changes and modifications as fall within the scope of the invention. For example, any formulas given above are merely representative of procedures that may be used. Functionality may be added or deleted from the block diagrams and operations may be interchanged among functional blocks. Steps may be added or deleted to methods described within the scope of the present invention.

Although the invention has been described with reference to specific examples, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms.

Industrial Applicability

It is apparent from the above, that the arrangements described are applicable to industries related to engines, pumps, road and rail vehicles, aircraft, and industrial manufacturing.

Claims

Claims:

1. An apparatus, comprising:

a cam set of three barrel cams concentrically disposed about a common rotational axis, the cam set comprising a radially inner, middle and outer cam with respective multilobate cam tracks disposed at a first axial end region of the cam set, the inner and outer cams synchronised to rotate in use at the same angular velocity, the middle cam arranged to counter rotate in use with an equal and opposite angular velocity with respect to the inner and outer cams; and at least one first cam follower assembly comprising three first roller followers supported for independent rotation, the first roller followers engaging with the cam track of the respective inner, middle or outer cam, the first cam follower assembly connected to a reciprocating first piston slidable in an axially orientated first cylinder, and thereby in use, during rotational motion of the cam set on the axis, a scissor action by the cam tracks of the respective inner, middle and outer cams constrains the first cam follower assembly to move in an axial direction.

2. An apparatus as claimed in claim 1, wherein the multilobate cam tracks of the inner and outer cams have a substantially matching cam form which is a rotational mirror image of the cam form of the multilobate cam track of the middle cam.

3. An apparatus as claimed in claim 1, further comprising a shaft and wherein one or more of the inner, middle and outer cams are geared with respect to the shaft.

4. An apparatus as claimed in claim 3, wherein the inner and outer cams are rotationally fixed to the shaft and wherein the shaft is aligned with the axis.

5. An apparatus as claimed in claim 3, wherein the middle cam is rotationally fixed to the shaft and wherein the shaft is aligned with the axis.

6. An apparatus as claimed in claim 1, wherein the inner, middle and outer cams also comprise respective multilobate cam tracks disposed at a second axial end region of the cam set.

7. An apparatus as claimed in claim 6, further comprising at least a second cam follower assembly comprising three second roller followers supported for independent rotation, each of the second roller followers engaging with the cam track of the respective inner, middle or outer cam at the second axial end region of the cam set, the second cam follower assembly connected to a reciprocating second piston slidable in an axially orientated second cylinder.

8. An apparatus as claimed in claim 7, wherein the reciprocation of the first and second pistons is in phase.

9. An apparatus as claimed in claim 8, further comprising a fluid interconnection

between respective breather regions under the first and second pistons in the first and second cylinders respectively.

10. An apparatus as claimed in claim 1, wherein the multilobate cam tracks disposed at the first axial end region of the cam set are in the form of circumferential grooves, thereby axially mechanically constraining the respective first roller followers.

11. An apparatus as claimed in claim 6, wherein the multilobate cam tracks disposed at the second axial end region of the cam set are in the form of circumferential grooves, thereby axially mechanically constraining the respective second roller followers.

12. An apparatus as claimed in claim 1, wherein the three first roller followers are

supported for independent rotation about a radially orientated first follower axle.

13. An apparatus as claimed in claim 12, wherein the first follower axle comprises

multiple axle segments.

14. An apparatus as claimed in claim 12, wherein the scissor action further constrains the first follower axle to have a radial orientation.

15. An apparatus as claimed in claim 7, wherein the three second roller followers are supported for independent rotation about a radially orientated second follower axle.

16. An apparatus as claimed in claim 15, wherein the second follower axle comprises multiple axle segments.

17. An apparatus as claimed in claim 15, wherein the scissor action further constrains the second follower axle to have a radial orientation.

18. An engine, comprising:

- an apparatus as claimed in any one of claims 1 to 17, the engine being arranged to generate an output torque at the shaft in use.

19. An engine as claimed in claim 18, being any one of the following engines:

an internal combustion engine;

a Stirling cycle engine;

a steam powered engine;

a propellant powered engine;

a hydraulic motor; or

a pneumatic motor.

20. A pump, comprising: an apparatus as claimed in any one of the claims 1 to 17, the pump being arranged such that a fluid is pressurized in the first cylinder as a result of an input torque applied at the shaft in use.

21. A pump as claimed in claim 20, being any one of the following pumps:

a liquid fluid pump;

a gaseous fluid pump;

a mixed-phase fluid pump; or

a compressor.

22. An electrical motor, comprising:

an apparatus as claimed in any one of claims 1 to 17, the electrical motor being arranged to generate an output torque at the shaft in use.

23. An electrical motor as claimed in claim 22, further comprising a rotor arrangement attached to the outer cam and a stator arrangement located substantially around the rotor arrangement such that when the electrical motor is energized in use, the rotor arrangement applies a torque to the shaft.

24. An electrical motor as claimed in claim 23, wherein the stator arrangement comprises a magnetising means to form two or more magnetic poles.

25. An electrical motor as claimed in claim 24, wherein the magnetising means comprises any one of the following magnets:

permanent magnets; or

electromagnets.

26. An electrical motor as claimed in claim 23, wherein the rotor arrangement comprises two or more armature members, each having an electrical winding adapted to induce a magnetic field in use.

27. An electrical generator, comprising:

an apparatus as claimed in any one of claims 1 to 17, the electrical generator being arranged to generate an electrical current in use.

28. An electrical generator as claimed in claim 27, further comprising a rotor arrangement attached to the outer cam and a stator arrangement located substantially around the rotor arrangement such that when the outer cam rotates in use, the electrical generator generates the electric current.

29. An electrical generator as claimed in claim 28, wherein the stator arrangement

comprises a magnetising means to form two or more magnetic poles.

30. An electrical generator as claimed in claim 30, wherein the magnetising means comprises any one of the following magnets:

permanent magnets; or

electromagnets.

31. An electrical generator as claimed in claim 28, wherein the rotor arrangement

comprises two or more armature members, each having an electrical winding adapted such that in use an electric current is induced therein.