THIS INVENTION relates to a rotary machine which may operate as an internal combustion engine, fluid motor, fluid pump or compressor.

It is known to provide a rotary machine comprising a rotor supported for rotation in a cavity defined within a machine housing, and a plurality of vanes which in combination . with the housing and rotor define a plurality of chambers within the cavity which vary in volume upon relative rotation between the rotor and the housing. While the volume of each chamber does vary with relative rotation between the rotor and housing, the volumetric capacity of each chamber is constant at any rotational position. As a consequence of this, the volume ratio between the minimum volume to which each chamber can contract and the maximum volume to which the chamber can expand is always constant. While the rotary machine might be constructed to perform at optimum efficiency at certain operating conditions with the fixed volume ra ^' tio, it is most unlikely that the machine will continue to operate at such optimum efficiency when the operating conditions change.

The present invention seeks to provide a novel and useful rotary machine in which the volume ratio can be selectively changed in accordance with operating conditions of the rotary machine.

In one form the invention resides in a rotary machine comprising a machine housing having a cavity, a rotor rotatably supported in the cavity, a plurality of vanes arranged to form with the housing and the rotor a •plurality of chambers which vary in volume on relative rotation between the rotor and the housing, characterised

in that there is provided means for selectively shifting the rotor relative to the housing - in a direction transverse to the axis of rotation of the rotor in order to vary the volumetric capacity of each chamber at any rotational position.

Preferably, said means for selectively shifting the rotor relative to the machine housing comprises bearings rotatably supporting the rotor and being mounted in respective bearing housings each of which is selectively rotatable about an axis eccentric to the rotational axis of the rotor whereby rotation of the bearing housings effects said shifting movement of the rotor relative to the machine housing.

Preferably, the cavity is defined by an internal peripheral wall and a pair of opposed end walls, each end wall being defined by an end member on to which the respective bearing housing is mounted for selective rotation.

Preferably, the vanes are supported for reciprocatory movement in slots in the rotor and extend outwardly to slidably and sealingly engage with internal peripheral wall in the housing.

Preferably, a first sealing means operates between each vane and the respective slot in the rotor which receives the vane, the first sealing means may comprise a pair of sealing strips corresponding to each vane with one sealing strip of each pair being disposed on each side of the vane and in sealing contact with the vane, each sealing strip being received in an elongated recess so formed in the rotor as to open onto the respective slot receiving the vane and extending longitudinally with respect to the

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rotor. The first sealing means may further comprise a spring means for biassing each sealing strip into sealing contact with the respective vane.

Preferably, the rotor has a peripheral face extending between said opposed end walls of the housing and has opposed end faces one confronting each end wall of the machine housing, and a second sealing means provided between each end wall and ,the corresponding end face of the rotor. The second sealing means preferably includes a plurality of seal segments one extending between each pair of adjacent vanes, each seal segment being located in a recess in the rotor end face and being urged into sealing contact with the adjacent end wall. Conveniently, each seal ^' segment is urged into contact with the facing end wall by means of spring means acting between the seal segment and the end face of the rotor. This arrangement serves a two fold purpose. First, it allows the seal segments to adjust automatically for wear. Secondly, it allows the seal segments to compensate for thermal distortions of the machine housing and rotor which occur during operation of the rotary machine.

Preferably the seal segments are of an arcuate configuration having a centre of curvature coincident with the axis of rotation of the rotor.

Preferably, a third sealing means operates between the first and second sealing means. The third sealing means may comprise a plurality of seal elements each providing a junction between corresponding ends of neighbouring sealing strips and sealing segments, each seal element being received in a respective socket in the corresponding end face of the rotor and having first and second sealing faces orthogonal to each other, the first sealing face

being in sealing contact with the adjacent face of the corresponding vane and the second sealing face being in sealing contact with the corresponding end wall of the housing. Preferably, the first sealing face of each seal element has a recess which receives the adjacent end of the corresponding seal strip and the second sealing face has a recess which receives the adjacent end of the corresponding seal segment.

It is desirable to urge the vanes in a radially outward direction to maintain engagement between the free end of each vane and the peripheral wall of the housing. While this may be achieved by suitable spring devices acting between the vanes and the rotor, it is preferred that fluid pressure be utilised for such purpose. To this end, there is provided a fluid flow path for fluid flow across said seal means so that pressured fluid may enter the region on the inner side of the seal means and thereby act oa. the radially inner ends of the vanes. Preferably, a return fluid flow path is provided for pressure relief. The first-mentioned fluid flow path and the return fluid flow path may each be in the form of a radially extending slot formed in one or both of the end walls of the housing so as to bridge the sealing means. In another arrangement the fluid flow path may be a passage which extends through the housing with one end of the passage communicating with the cavity at the region where the chambers undergo compression and the other end of the passage communicating with the cavity inwardly of the sealing means. A similar alternative arrangement can be employed for the return flow path.

The invention will be better understood by reference to the following description of several specific embodiments thereof as applied to an internal combustion engine. The description will be made with reference to the accompanying drawings in which:-

Fig. 1 is a cross-sectional view of an engine according to the first embodiment;

Fig. 2 is a schematic side view of the engine of Fig. l;

Fig. 3 is a schematic end view of the engine of Fig.

1;

Fig. 4 is a view of the inner face of an end plate for the engine of Fig. 1;

Fig. 5 is a perspective view of a rotor forming part of . the engine;

Fig. 6 is view of an end face of the rotor;

Fig. 7 is a section along the line 7-7 of Fig. 6;

Fig. 8 is a section along the line 8-8 of Fig. 6;

Fig. 9 is a schematic perspective view of a segment of the rotor deferred between two adjacent slots in the rotor;

Fig. 10 is an exploded perspective view of part of the first sealing means;

Fig. 11 is a perspective view of a sealing segment which forms part of the second sealing means;

Fig. 12 is a perspective view of a seal element which forms part of the third sealing means;

Fig. 13 is a diagrammatic view illustrating a fuel injection cycle of the engine;

Fig. 14 is a diagrammatic view illustrating an air induction cycle of the engine;

Fig. 15 is a diagrammatic view illustrating a compression cycle of the engine;

Fig. 16 is a diagrammatic view illustrating a combustion -and power cycle of the engine;

Fig. 17 is a diagrammatic view illustrating an exhaust cycle of the engine; and

Fig. 18 is an exploded view of part of an engine according to a second embodiment.

The engine comprises a housing 11 having a cavity 13. The housing 11 includes a hollow central portion 15 and a pair of end plates 17 one at each of two opposed ends of the central portion 15. Each end plate 17 is bolted or ^' otherwise attached to the central portion 15. The central portion 15 has an internal peripheral wall 19 which in combination with the inner walls 21 of the end plates 17 define the cavity 13, as there shown in Fig. 2 of the drawings. The internal peripheral wall 19 of the central portion 15 is substantially elliptical in -cross-section, as shown in Fig. 1 of the drawings.

The engine further comprises a rotor 23 supported within the cavity 13 on a shaft 25 which is itself rotatably supported in bearings 27 mounted on the end plates 17.

A plurality of vanes 31 are slidably supported in slots 33- in the rotor. The vanes 31 extend outwardly of the rotor for sliding and sealing engagement with the internal peripheral wall ' 19 of the intermediate member 15. The vanes 31 ex ^' tend the full length of the rotor and slidingly and sealingly engage the inner walls 21 of the end plates 17.

The vanes 31 divide the space between the inner peripheral wall 19 of the central portion 15 and the peripheral surface 27 of the rotor 23 into a plurality of chambers 35 which vary in volume on rotation of the rotor relative to the housing.

As mentioned hereinbefore, the rotor shaft 25 is rotatably supported in bearings mounted on the end plates 17. Each bearing is supported within a bearing housing 39 which is attached to the exterior face of the respective end plate 17 by means of clamping elements 41. The clamping

elements 41 can be selectively released to permit rotational adjustment of the bearing housing for the purpose of shifting the rotor as will be explained in detail later.

Each end plate 17 is provided with a bore 43 through which the rotor shaft 25 extends, and as seen in Fig. 2 of the drawings. The bore 43 is of a diameter which is larger than might otherwise be required to accommodate the shaft 25 so as to permit selective lateral adjustment of the shaft. The bore 43 is eccentric to the circular end plate 17. This is illustrated in Fig. 4 of the drawings where the centre of the end plate is designated by reference numeral 45 and the centre of the bore is designated by reference numeral 47.

As mentioned hereinbefore, the bearing housing 39 is selectively rotatable for positional adjustment. The baaring housing has a circular periphery the centre of which corresponds to the axis of rotation of the bearing housing and is designated by reference numeral 49. The bearing is so positioned within the bearing housing that the centre of the bearing (which is designated by reference numeral 51) is eccentric to the centre 49 of the bearing housing. The axis of rotation of the rotor 45 is of course coincident with the centre 51 of the bearing. Because the centre 51 of the bearing is eccentric to the centre 49 of the bearing housing 39, rotation of the bearing housing about the centre 49 causes the position of the centre of the bearing 51 to shift. As a consequence of this, the shaft 25 is shifted laterally as is the rotor 23 within the cavity 13. Shifting of the rotor relative to the housing in such a manner varies the volumetric capacity of each chamber 35 at any rotational position of the rotor.

The ability to selectively vary the volumetric capacity of each chamber 35 at any rotational position is beneficial in that the volume to which the chamber expands can be varied from the volume to which the chamber contracts. In this way, the engine can be adjusted so that the induction cycle of the engine is larger than the power cycle so as to enhance power output. Alternatively, the engine may be so adjusted that the induction cycle is less than the power cycle so as to enhance fuel economy. It would, of course, also be possible to operate in a conventional mode where the capacities of the induction and power cycles are equal. The compression ratio is, of course, varied on lateral adjustment of the rotor relative to the housing and such variation provides an additional benefit.

In this embodiment, the position of the rotor relative to the housing is adjusted manually. In an alternative arrangement, such adjustment may be performed automatically according to the desired operating requirements of the engine.

A means 55 is provided for admitting fuel into each chamber 35. In this embodiment, the fuel inlet means 55 is in the form of a fuel injector mounted on the intermediate member 15 and communicating with the cavity 13. The vanes 31 sweep over the fuel injector 55 and in doing so sequentially expose the chambers 35 to incoming f el. The fuel may be of any suitable type such as petrol, kerosine, grain alcohol, diesoline, LPG, LNG or hydrogen gas.

Means 57 are provided for admitting combustion air in __. chamber at the appropriate time. The air inlet means includes a plurality of ports 59 formed in the central portion 15 and communicating with the cavity. The ports are circumferentially spaced, as shown in the drawings.

The vanes sweep over the ports 59 on rotation of the rotor and the chambers are sequentially exposed to the ports so as to receive combustion air.

The air inlet means 57 is positioned relative to the fuel inlet means 55 so that combustion air is received after the admission of fuel into each chamber and at a point where the chamber is expanding in volume.

An ignition means 61 is provided for igniting the combustible mixture in each chamber. The ignition means 61 is in the form of a spark plug, although other forms of ignition means may be used.

A means 63 is provided for exhausting the spent products ^' of combustion from each chamber. The exhaust means 63 comprises a plurality of .ports 65 which communicate with- the cavity. The ports 65 are circumferentially spaced, as shown in the drawings. The vanes sweep over the ports 65 on rotation of the rotor and the chambers are sequentially exposed to the exhaust ports.

The engine includes a sealing system for preventing, or at least limiting, leakage of fluid from chambers 35. The sealing system is arranged to maintain sealing of the chambers while accommodating shifting movement of the rotor. The sealing system comprises first sealing means 66 operating between the slots 33 in the rotor and the slidable vanes 31 received therein, second sealing means 71 operating between each end face 29 of the rotor and the inner wall 21 of the corresponding end plate 17, and third sealing means 81 provided between the first and second sealing means for a purpose which will become apparent later.

The first sealing means 66 comprises respective pairs of sealing strips 67 acting between the rotor and each vane,

the sealing strips extending longitudinally of the rotor and- being located one on each side of the respective vane. Each sealing strip 67 is received in an elongated recess 68 which is formed in the rotor and which opens onto the corresponding slot 33 in the rotor. The outermost edge of each sealing strip 67 sealingly contacts the respective vane under the influence of a spring device 69 in the form of a leaf spring which acts between the innermost edge of the sealing strip and the inner end of the elongated recess 68.

The second sealing means 71 is provided between each end face 29 of the rotor 23 and the inner wall 21 of the corresponding end plate 17 and is intended to prevent leakage of fluid through clearance spaces between the rotor and the end plates of the housing. The second sealing means 71 includes a plurality of arcuate seal segments 73 extending between adjacent vanes 31. The seal segments 73 are located at substantially the same radial distance from the axis of rotation of the rotor as are the sealing strips 67 and thus each end of each seal segment is located adjacent an end of one of the sealing strips. Each seal segment has its radius of curvature centred at the rotational axis of the rotor and is located in a respective recess 75 in the end face 29 of the rotor. A spring means 77 in the form of a pair of compression springs acts between the rotor and each seal segment in order to urge the seal segment into sealing engagement with the inner wall 21 of the end plate 17. This arrangement allows the second sealing means to automatically compensate for wear and to accommodate thermal distortions of the rotor and the housing which occur during operation of the engine.

The third sealing means 81 comprises a plurality of seal elements 82 each providing a junction between neighbouring

ends of the sealing strips 67 and seal segments 73. Each seal element 82 is generally semi-cylindrical in shape and has a two neighbouring orthogonal sealing faces 83 and 84. The seal elements 82 are received in respective sockets 85 formed in the end faces 29 of the rotor at the ends of the elongated recess 68. With this arrangement, the elongated recesses each open at its ends into a respective one of the sockets 85. With each seal element 82 received within one of the sockets 85, the first sealing face 83 of the seal element is in sealing contact with the adjacent face of the corresponding vane and the second sealing face 84 is in sealing contact with the inner wall 21 of the corresponding end plate 17. The first sealing face 83 has a recess 86 which receives the adjacent end of the corresponding seal strip 67 in a manner such that the outermost edge of the sealing strip is level with the first sealing face. The effect of this is that the first sealing face provides a continuation of the seal es-tablished by the sealing strip. The second sealing face 84 has a recess 87 which receives the adjacent end of the corresponding seal segment 73 in a manner such that the outermost edge face of the seal segment is level with the second sealing face. In this way, the second sealing face provides a continuation of the seal established by the seal segment. Because the first and second sealing faces 83 and 84 are orthogonal and neighbouring, the seal segment 83 interconnects the seals established by the corresponding sealing strip and seal segment without significant interruption to sealing of the chambers 35.

A fluid flow path is provided across the second sealing means 71 so that pressurised fluid can enter the region on the inner side of the sealing means 71 and act on the radially inner end of the vanes 31. This provides an outwardly directed force on the vanes which assists in

maintaining engagement between the free ends of the vanes and the internal peripheral wall of the housing, particularly when the engine is first started. The fluid path is provided by a radially extending slot 91 formed on the inner face 21 of one of the end plates 17 so as to bridge the sealing means. There is also provided a return fluid flow path in the form of a further radially extending slot 93 formed in the inner face 21 of the end plate. The cross-sectional area of the further fluid flow path 93 is less than that of the fluid flow path 91 so as to maintain a positive pressure in the region on the interior of the sealing means. The circulation of fluid through said region via the two flow paths 91 and 93 respectively facilitates lubrication of certain parts of engine, particularly the vanes sliding in the slots. In this connection, lubricant may be included with the fuel introduced into the chambers 35 by the fuel inlet means 55. The lubricant is conveyed to the vanes and slots by th-e fluid which passes through the slot "91.

Operation of engine will now be described on the basis that the engine has been started up and is running. . The description will be made with reference to the chamber designated 35a in Figs. 13 to 17 of the drawings, said chamber being defined between vanes 31a and 31b. Fuel is admitted to chamber 35a as it moves into communication with the fuel inlet means 55, as shown in Fig. 13. At this point, chamber 35a commences to expand in volume. On continued rotation of the rotor- chamber 35a moves into communication with the air inlet means 57 and air is induced into the chamber as it continues to expand, as shown in Fig. 14. On further rotation of the rotor, the volume of chamber 35a commences to reduce and the combustible mixture formed by the mixture of fuel and air is compressed, as shown in Fig. 15. The compressed

combustible mixture is ignited when chamber 35a moves into communication with the ignition means 61. The ignition may be effected by operation of the ignition means 61 in ^■ timed sequence. Alternatively, the ignition means may be arranged to operate only at start-up of the engine and subsequently ignition of each chamber is effected by a spill-over of the ignited mixture in the chamber ahead of chamber 35a when the particular vane separating those two chambers sweeps over the ignition means which is somewhat recessed relative to the internal peripheral wall of the cavity so as to provide a clearance space for such spill-over. After ignition of the combustible mixture, the expanding gases within chamber 35a act on the rotor so as to continue rotary motion thereof. The spent gases exhaust from chamber 35a when the chamber moves into communication with the exhaust means 63.

To improve the performance of the engine either in terms oS- _~ fuel economy or power output, the rotor shaft 25 may be shifted laterally as described hereinbefore either before start-up of the engine or during operation of the engine according to the demands of the engine.

Referring now to Fig. 18 of the drawings (which is an exploded view) , the engine according to the second embodiment is similar to that of the first embodiment with the exception of- a variation in the manner in which the shaft of the rotor is supported. In the second embodiment the shaft of the rotor is supported at each end in a bearing 27 which is itself supported in a bearing housing 95. The bearing housing 95 is mounted in a sleeve 96 for selective rotation about an axis eccentric to the axis of rotation of the rotor. This is achieved by providing the bearing housing 95 with a cylindrical outer wall 97 eccentric to the rotor axis. The bearing housing 95 is received within a corresponding bore 98 in the sleeve 96

and is rotatable therein about an axis co-incident with .the central axis of the cylindrical outer wall 97. A locking means 99 is provided for releasably locking the bearing housing 95 against rotation relative to the sleeve. The locking means 99 is in the form of a grub screw (not shown) engaged with a threaded bore 103 in the sleeve. The grub screw extends into a circumferential groove 104 formed in the outer wall 97 of the bearing housing and can be frictionally engaged with the groove in ' a selective manner to lock the housing against rotation relative to the sleeve.

The sleeve 96 is mounted for selective rotation about an axis eccentric to the axis of rotation of the bearing housing 95. More particularly the sleeve is rotatably supported in a retainer ring 105 provided on the end plate 17 of the housing 11. The retainer ring 105 is concentric with bore 43 in the endplate. In this embodiment, the bore 43-_.is itself concentric with the endplate 17. The sleeve has a cylindrical outer wall 107 which locates adjacent the cylindrical inner wall 108 of the retaining ring A . locking means 109 is provided for releasably locking the sleeve against rotation relative to the retainer ring. The locking means 109 is i ^" the form of a grub screw (not shown) engaged with a threaded bore 111 in the retaining ring. The grub screw extends into a circumferential groove 112 formed in the outer wall 107 of the sleeve and can be frictionally engaged with the groove in a selective manner to lock the sleeve against rotation relative to the retaining ring 105.

With this arrangement for supporting the rotor shaft, the latter can be shifted laterally by selective rotation of the bearing housing 95 and/or the sleeve 96.

. _, .

The bearing housing 95 and sleeve 96 are each provided with means which can be engaged by a tool to facilitate selective manual rotation in the manner required.

It should be appreciated that the scope of the invention need not be limited to the scope of the embodiment. For instance, the invention is not limited to an internal combustion engine and may be applied to other rotary machines such as fluid motors, fluid pumps, and compressors. Furthermore, while the machine according to the embodiment has been described as having a circular rotor and an elliptical cavity wall, it should be appreciated that other configurations may be employed such as a cavity wall which is circular and a rotor which is elliptical, or a cavity wall which is circular and a rotor which is also circular but offset from the axis of the cavity.