AU610126B2 - Axial engine - Google Patents

Description

C;'i a AU-AI-11869/88 WORLD NTELLETUA ROP RTY GANlTI P C T Int i3 a] TT t .TREATY (PCT) INTERNATIONAL APPLICATION PUBLISHED DE T PATET PE T TREATY (PCT) (51) International Patent Classification 4 (11) International Publication Number: WO 88/ 05495 F02B 75/26, 75/32, F01B 3/04 Al F01B 7/04, 9/06, F16H 25/12 (43) International Publication Date: 28 July 1988 (28.07.88) (21) International Application Number: PCT/AU88/00009 (81) Designated States: AT (European patent), AU, BE (European patent), BR, CH (European patent), DE (Eu- (22) International Filing Date: 15 January 1988 (15.01.88) ropean patent), FR (European patent), GB (European patent), IT (European patent), LU (European patent), NL (European patent), SE (European pa- (31) Priority Application Number: PH 9910 tent), US.

(32) Priority Date: 16 January 1987 (16.01.87) Published (33) Priority Country: AU With international search report.

(71) Applicant (for all designated States except US): GEE- LONG ENGINE CO., PTY. LTD. [AU/AU]; Harvey Carr, Latrobe Terrace, Geelong, VIC 3220 (72) Inventor; and Inventor/Applicant (for US only) WESTBURY, Doug- las, Gordon [AU/AU]; 8 Jamieson Street, Geelong East, VIC 3219 a. .J.P 15 SEP 988 (74) Agent: EDWD. WATERS SONS; 50 Queen Street, Melbourne, VIC 3000

AUSTRALIAN

AUG 1988 PATENT OFFICE (54) Title: AXIAL ENGINE (57) Abstract A transfer mechanism for'converting reciprocating motion to rotary motion in a reciprocating-piston type machine or engine comprises a motion conversion assembly (12) having a rotor (19) with a cam track groove (20) connected by a cam follower (17) to a piston rod (13) which joins pistons 3A) inside cylihders 2A) of the engine. In operation the reciprocating motion of the piston rod (13) causes the cam follower (17) to move along the cam groove (20) to drive the rotor (19) and hence the output shaft (16).

SURECEIVED

-1- AXIAL ENGINE The present invention relates principally to an internal combustion engine which includes means for converting reciprocating motion to rotary power output, and particularly to engines having the ability to substantially complete combustion under constant volume conditions.

Known means for converting reciprocating motion to rotary output comprise crank mechanisms, which establish a fixed ratio between rotor velocity and piston velocity of n i0 to 2. This does not correspond to ideal conditions for maximum engine output. Other mechanisms for achieving this conversion of reciprocating motion to rotary output motion are disclosed in U.S. Patent Nos. 1352985, 1382485, 1565184, 1762437, 1802902, 1918840, 2664866, 3598094; U.K. Patent Nos. 254261, 273542 and German Patent No. 3408447.

U.S. Patent 7o. 1352985 discloses a construction" whereby a plurality of combustion cylinders are arranged around a cylindrical cam block having a radially extending cam track engagabe with roller followers connected with piston rods associated with the combustion cylinders. The reciprocation of the piston rods thereby causes a rotary output from the cam block. The cam track, however, appears to be essentially sinusoidal.

U.S. Patent Nos. 1382485, 1565184, 1762437, 1802902,'1918840, 2664866, U.K. Patent No. 254261 and German Patent No. 3598094 essentially disclose similar engine arrangements to U.S. Patent No. 1352985 except that the follower members connected with the piston rod assemblies co-operate with a cam track formed by a groove formed in the cylindrical output drum. The grooves are essentially continuous and generally sinusoidal in configuration.

U.S. Patent No. 3592985 again is similar to the aforementioned patent specifications but in this instance the sinusoidal continuous cam track or groove is formed in the inner surface of an annular cylindrical output member that generally surrounds the combustion cylinders.

%/4 ^W L"iJl:^:- 4' SPC/AU 3. /000 07 REC I E 6 AU9 1989 2 U.K. Patent No. 273542 shows another complicated arrangement which in principal operates in the manner described briefly above in relation to the prior identified patent specifications except in this instance the cam track is actually formed in the piston members.

None of the above described prior art specifications disclose an arrangement enabling combustion processes to be completed under substantially constant volume conditions.

The principal objective of the present invention is to provide a mechanism of the aforementioned type for heat engines whereby it is possible to achieve a torque output that is substantially proportional to the force exerted by reciprocating pistons of the engine. Moreover, it is desired to achieve a situation whereby the pistons can remain stopped at the end of their strokes for a period of time sufficient to allow combustion in the engine to be completed at constant volume. A further preferred objective is to achieve a situation within the engine whereby the positive and negative acceleration of the piston is arranged to best transfer the inertia of the piston to the rotary member.

Accordingly, the present invention provides an internal combustion engine comprising at least one combustion chamber, a piston assembly reciprocable in said combustion chamber and a transfer mechanism for converting reciprocating movement of said piston assembly into rotary motion at an output shaft, said transfer mechanism comprising a rotary member adapted to drive said output shaft, a cam track carried by said rotary member, a cam follower means adapted to move along said cam track to thereby drive said rotary member, said cam follower means being driven by the reciprocating movement applied to said cam follower means by said reciprocating piston assembly, 3 and said cam track being configured to maintain said piston assembly stopped at each end of its stroke for a period sufficient to allow combustion in said combustion chamber to be completed at constant volume.

0 C' r ,,7 Cr/A 88/000 07 RECEIVED 1 6"AUG 1988 3 Preferably the internal combustion engine includes a plurality of said combustion chambers arranged around the transfer mechanism, each housing a separate said piston assembly co-operating with a respective said cam follower means. The or each said piston assembly may comprise at least two piston members each said piston member being located in opposed axially aligned cylinders forming said combustion chamber. The piston members of the or each said piston assembly may be connected by connecting rod means.

Conveniently the cam track resembles a continuous helix around an outer circumferential surface of the rotary member. The cam track may comprise F groove into which the cam follower fits. The cam .follower may comprise a spherical member housed partially within an axially sliding member and partially within the cam track; a wheel with an axle mounted on an axis parallel to a rotation axis of said rotary member and disposed similarly to the former; a hemispherical element rotatable on an axis radial to the rotation axis of the rotary member disposed on an axially sliding member; or other suitable means. The axially sliding member is connected to or moved by one or each of the piston assemblies. Preferably the transfer mechanism is located between at least one pair of in line axially arranged reciprocating piston assemblies whereby the cam follower is acted upon alternately by each of said pair of piston assemblies.

It is believed that the arrangement proposed by the present invention has significant advantages over the conventional crank pin system, and the systems discussed above with reference to the cited prior art, for converting reciprocating motion to rotary work output. Constant volume combustion is a convenient title for stating that the piston stops when it reaches its inner dead centre position, whereupon the spark ignites the gas, combustion progresses to the start of end burn; which is the point in the combustion process where the temperature and pressure are beginning to rise too high; this same point is where the expansion stroke begins so as to have the effect of ,a ELI -4 P-C/A 3 8/ 0 0 0 0 7 RECEIVED 1 6 AUG 1988 S- 4 diminishing the rise in temperature and pressure. What may be termed a phase of combustion at constant pressure.

Combustion at constant volume enables complete combustion regardless of engine RPM. This is seen to be a distinct advantage at low RPM's and when idling. Other advantages include a. it is impossible for the engine to back-lash when it is being cranked up, spark occurring when the piston is stopped at inner dead centre b. a shorter overlap of the combustion and expansion phases increases the expansion which is believed to improve efficiency; c. the surface of the clearance volume is less. Thus heat loss will be less and thermal efficiency is improved; d. the piston, being stopped during the combustion phase also means the piston is stopped for the same time at the bottom of it's stroke at outer dead centre this would give the opportunity of improving air efficiency.

Poor air efficiency being one of the worst features of two stroke engines; e. lower port openings can be used in a two stroke engine because of the greater time provided for gas flow.

This also improves the volume of the charge and also the expansion ratio; and f. density of the air or gas charge can be substantially increased due to the pistons rapid initial acceleration from bottom and its delay at the top of it's stroke.

In effect, the cam mechanism enables improvements in torque, air efficiency, mechanism efficiency and where combustion pressures are reduced with more emphasis placed on torque, combustion temperatures are reduced and thermal efficiencies are improved further.

The cam mechanism provides a much longer torque arm than can be provided by known crank mechanism, thus enabling 1. Less force needed to achieve the same torque; or 2. More torque to be achieved from the same force.

i I 4 [I PCr/AU 38/ 0 0 0 7 RECEIVED i 6AUG 1988 In relation to conventional crank pin systems, the angular velocity is never constant relative to the linear velocity of the reciprocating pistons except for two instants for each crank cycle, e.g. at 90* and 2700. In contrast, in the present invention, the angular velocity of the transfer mechanism may be arranged proportional to the linear velocity of the piston assemblies except, in a preferred case, for three periods per half cycle. The three periods allow for zero velocity, positive acceleration, negative acceleration, and then returning to zero velocity for the beginning of a second half cycle.

Furthermore, the torque output achieved by a conventional crank pin drive shaft system is dependent upon the angular position of the crank pin relative to the connecting rod. Only at the position where this angle is at 900 is there achieved a situation where the force applied by the piston is fully converted to torque output.

In conventional crank pin systems, the reciprocating members stop only for an instant at the beginning and the end of each stroke, whereas, in the present invention, it is possible to arrange the pistons to stop at each end of their strokes for a period of time depending on the shape given to the cam track. Furthermore, in the known arrangements, the crank pin system requires the alignment of the reciprocating pistons at right angles to the crank shaft whereas, according to the present invention the alignment of the reciprocating piston assemblies is parallel to the axis of the output shaft.

Moreover, in conventional internal combustion engines, the right angle alignment of the cylinder relative to the crankshaft requires a camshaft and drive arrangement, push rods and rocker to operate valves whereas the present invention allows any valves to be opened directly off a cam on the front or rear of the rotary member or on the drive or output shaft.

The use of conventional crank pins in internal combustion engines also has a further disadvantage in that it imposes compression on the combustion process whereas the

I

Pcr/AU 38 00 07 RECEIVED I 6 AU8 1988 -6present invention allows a substantially ideal cycle for combustion to occur in the internal combustion engine, at constant volume so that compression is complete before combustion begins.

Furthermore, the use of conventional crank pin drive shafts in internal combustion engines provides a constant ratio of less than one to one between the length of the compression and expansion strokes, whereas the present invention permits the choice of a difference between the rate and length of the compression stroke and the expansion stroke. Whereas also the present invention would allow any two stroke cycle engine using it to merge to and fro from spark ignition to compression ignition at will. This is possible when exhaust valves are located in the clearance space of the internal combustion engine. Late closing of the exhaust valve increases scavenging and pressure control of exhaust cavity to effectively increase air density in the cylinder. An increase in air density has the effect of increasing compression ratio thus enabling higher temperatures which could sustain compression ignition.

The use of conventional crank pin drive systems in internal combustion engines also contributes to th' deterioration of the volumetric efficiency with any increase in revolutions per minute. The present invention would allow substantially one hundred per cent volumetric efficiency in a two stroke engine at reasonable R.P.M.s.

The use of conventional crank pin drive systems in internal combustion engines also constrains the length of the working (expansion) stroke to conform in length to that of the compression stroke whereas in the present invention the length of the working stroke can be greater than that of the compression stroke.

Furthermore, internal combustion engines that make use of compression ignition systems and which are confined 3 to a constant compression ratio by the known crank generally use a high pressure fuel injection system. Whereas internal combustion engines that make use of the present invention can make use of low pressure fuel injection systems for both spark ignition and compression ignition types.

/1~J a ~i.

CT/A 88 0 07 RECEIVED 1 C AUG 1988 -7 An important advantage of the instant invention is that the ratio between rotor velocity and piston velocity can be varied to achieve a predetermined pattern. The desired predetermined pattern is that which most nearly enables the piston movement to be most compatible with the intake, compression, combustion and expansion of gas.

The present invention will now be more fully described with reference to the accompanying drawings Figure 1 is a schematic view of an embodiment of the instant invention.

Figures 2, 3 and 4 are cross-sectional views of various cam follower mechanisms for use in the instant invention.

Figure 1 illustrates essentially a two stroke engine comprising in line cylinders arranged in pairs. The number of cylinders may be varied as desired generally arranging same in pairs circumferentially spaced around the output drive shaft. For example a six cylinder engine might be produced by having three pairs of cylinders equally spaced around the output drive shaft. In Figure 1, one pair of such cylinders is illustrated for the sake of clarity.

In Figure 1, the engine housing 1 is provided having two in line cylinders 2 and 2A as discussed above.' Each cylinder has a piston 3, 3A respectively for reciprocation along the cylinder's and a piston rod 13 joins each of the pistons 3, 3A. The piston rod 13 is shown as one element but this need not necessarily be the case. For example separate piston rods might be used engaging against a slider block or the like co-operating with the output transfer mechanism as hereinafter described.

The output or drive shaft 16 is shown generally parallel to the axis of the cylinders 2, 2A. A transfer mechanism 12 is shown generally located between the two cylinders 2, 2A and co-axial with the drive shaft 16. The transfer mechanism 12 is adapted to transfer the reciprocating motion of the pistons 3, 3A into a rotary output motion transmitted to the drive shaft 16. The transfer mechanism comprises a rotor 19 with a cam track in S 7 V4 F® 1 a I *1 PCT/A: 8 8 /00007 RECEIVED 1 6'AUG 1988 -8 the form of a groove 20 around its outer periphery. The direction of the groove 20, as hereinafter explained, controls the movement of the pistons 3, 3A, however it does generally resemble a continuous helix around the outer periphery. A cam follower 17 couples the piston rod 13 to the rotor 12. The follower 17 as more clearly shown in Figure 2, may comprise a spherical member housed in a partial spherical recess in the piston rod 13 (or slider block member), the member 17 also rolling within the groove 20 in the rotor 19. Thus reciprocation of the pistons 3, 3A causes the rotor 19 to rotate with the spherical member or ball 17 travelling along the groove 20. The configuration of the groove 20 controls the movement of the pistons. For example, a length of groove having a helical component enables the pistons to move axially along their cylinders while peripherally extending sections of the groove constant relative to the drive shaft axis will hold the pistons stationary. The angle of the groove 20 relative to the radial direction of the rotor 19 controls acceleration or deceleration of the pistons 3, 3A, Figure 3 shows an alternative cam follower mechanism. In this arrangement, the piston rod 13 or separate slider block has affixed thereto a substantially hemispherical element 24 by means of an axle 25. The element 24 is rotatable about an axis radial to the axis of the rotor 19. Hence, the reciprocation of the pistons 3,3A causes the rotor 19 to rotate by means of the element 24 rolling through the groove Figure 4 illustrates a further preferred embodiment of the cam follower mechanism. A wheel 22 is affixed by means of an axle 23 to the piston rod 13 or separate slider block and is disposed within the groove 20 so as to be rotatable about an axis substantially parallel both to the axis of the piston rod 13 and the axis of the rotor 19. In this arrangement, the reciprocating pistons 3,3A cause the rotor 19 to rotate by means of the rotatary wheel 22 moving along the groove.

.i Z, S/I ~T PCT/AU 88/00007 7 RECEIVED 1 6'AUG'1989 -9 It is to be understood that while it is desirable that the cam follower elements described in Figures 3 and 4 have a circular cross-section, the exact shape is to be determined with regard to the interactions with the groove.

Moreover, it is necessary for the width and profile of the groove to be varied along-its length when-using the embodiment of Figure 4.

As shown schematically, it is possible, if desired to couple the rotor 19 with the output shaft 16 via a differential gear mechanism 18. Alternatively, the shaft 16 might be directly coupled to the rotor 19.

Operation of the piston cylinder arrangements, while containing certain design variations, is generally similar in principal to a conventional internal combustion engine. The engine arrangement includes an exhaust valve 4, 4A for each cylinder. The timed operation of the valves 4, 4A may be achieved by cam members 5, 5A directly arranged on the drive shaft 16. Alternatively the timed operation of the valves 4, 4A may be achieved by axial cams directly arranged on the ends of the rotor 19 so as to directly actuate valves when the valves 4, 4A are inclined generally parallel to the axis of the output shaft. Air intake ports 6, 6A are provided leading to each cylinder 3, 3A from transfer manifolds 9, 9A, an air manifold 14 and an air intake regulator 15. Air valves 10, 10A are provided regulating flow from the air manifold 14 to the transfer manifolds 9, 9A. Each of the exhaust valves 4, 4A are contained in passage means leading to an exhaust manifold 8 and an exhaust pressure regulator 7. When the exhaust valves 4,4a are located in the clearance space of the engine, it is possible to provide for late closing of the exhaust valves. This increases scavenging and enables an effective increase of the air density in the cylinder. An increase in the air density has the effect of increasing the compression ratio thus enabling higher temperatures which could maintain compression ignition.

Although it has been shown that the conformation of the groove 20 would allow each piston to complete one d I- 1C, f c r r Sc RECEI 1 6 ALIG 1989 10 Scombustion cycle per each revolution of the output shaft, it is also possible to so arrange the groove 19 whereby any desirable number of combustion cycles can be completed by each piston per revolution of the output shaft.

An engine utilising the instant invention may comprise a plurality of pairs of reciprocating pistons mounted around a single rotor. The number of piston assemblies is only limited by the size of the rotor, and the rotor housing. Preferably, the piston assemblies are mounted symmetrically about the rotor.

The rotor housing should be configured so as to allow the piston assemblies to be mounted thereon.

Conveniently, the rotor housing or at least the ends thereof has a polygonal cross-section. This allows for easy affixing of the piston assemblies to the rotor housing, and easy mounting at the assembly in the engine.

The rotor is preferably supported in its housing by bearings which are so constructed as to cope with axial and radial stresses.

An alternative to the poppet valves 4,4A operated by cams on the output shaft 16 is to utilise, for both or either exhaust and inlet valves, a rotary valve system.

Such a rotary valve could be mounted on the output shaft 16 and comprise a disc or the like, with openings located therein'to allow flow-through of the inlet or exhaust gases at a predetermined time in the combustion cycle. This eliminates cam wear and associated problems and the need for springs associated with poppet valves. Moreover, one such rotary valve disc might be employed for operation of a plurality of cylinder arrangements located around the transfer mechanism. The rotary exhaust valve is intended to operate in conjunction with piston porting as is typical of two stroke systems, and is not intended to be placed in the clearance space at the top of the cylinder as is the usual location for poppet valves.

17- I i

Claims (5)

1. An internal combustion engine comprising at least one combustion chamber, a piston assembly reciprocable in said combustion chamber and a transfer mechanism for converting reciprocating movement-of- said piston assembly into rotary motion at an output shaft, said transfer mechanism comprising a rotary member adapted to drive said output shaft, a cam track carried by said rotary member, a cam follower means adapted to move along said cam track to thereby drive said rotary member, said cam follower means being driven by the reciprocating movement applied to said cam follower means by said reciprocating piston assembly, and said cam track being configured to maintain said piston assembly stopped at each end of its stroke for a period sufficient to allow combustion in said combustion chamber. to be completed at constant volume.

2. An internal combustion engine according to claim 1 wherein a plurality of said combustion chambers are arranged around said transfer mechanism, each housing a separate said piston assembly cooperating with a respective said cam follower means.

3. An internal combustion engine according to claim 1 or claim 2 wherein the or each said piston assembly comprises at least two piston members each said piston member being located in opposed axially aligned cylinders forming said combustion chamber.

4. An internal combustion engine according to claim 3 wherein the piston members of the or each said piston assembly are connected by connecting rod means. An internal combustion engine according to claim 3 wherein the piston members of each said piston assembly act to drive a slider block member along a reciprocating path of movement. l v PCT/AU 8 0 0 0 07 RECEIVED 1 6 AUG 1989

12- 6. An internal combustion engine according to claim 4 or claim 5 wherein said cam follower means comprises a spherical member partially retained by the or each said piston assembly and carried by said cam track. 7. An internal combustion engine according to claim 4 or claim 5 wherein said cam follower means comprises a coupling member for the or each said piston assembly, the or each said coupling member being rotatable about an axis substantially radial to the axis of said rotary member, the or each said coupling member being carried by a said piston assembly. 8. An internal combustion engine according to claim 4 or claim 5 wherein said cam follower means comprises a coupling member, for the or each said piston assembly mounted for rotation about an axis substantially parallel to Sthe axis of said rotary member, the or each said coupling member being partially received in said cam track. 9. An internal combustion engine according to any one of claims 2 to 8 wherein there is provided a rotary valve assembly for either or both inlet and exhaust valves, said rotary valve assembly comprising a disc member with appropriate apertures therein mounted for rotation with said output shaft. An internal combustion engine according to claim 9 wherein said rotary member includes a polygonal shaped housing or polygonal shaped end sections such that the reciprocating piston assemblies are mounted to flat faces of said polygonal shaped housing or said end sections. VAX (DOC 2)