WO2007049226A1

WO2007049226A1 - External combustion rotary vane engine

Info

Publication number: WO2007049226A1
Application number: PCT/IB2006/053911
Authority: WO
Inventors: Stephanus Christoffel Hendrik Botha
Original assignee: Botha Stephanus Christoffel He
Priority date: 2005-10-24
Filing date: 2006-10-24
Publication date: 2007-05-03

Abstract

The invention provides an engine (10) having a housing (12) defining a compressor (26) having an inlet and an outlet, a combustion chamber (92) and a power unit (28) having an inlet and an outlet. The combustion chamber (92) has an inlet which is connectable in flow communication with an outlet of the compressor and an outlet which is in flow communication with an inlet of the power unit. Each of the compressor and power unit (28) includes a rotor mounted in a complementary chamber having a pair of part-circular lobes. The rotor is mounted concentrically with one of the lobes and eccentrically relative to the other lobe. Seals are provided on the rotors. The compressor feeds air, under pressure, into a reservoir (90). Air is fed from the reservoir (90) into the combustion chamber where it is mixed with fuel and ignited. Exhaust gases are fed from the combustion chamber into the power unit to extract useful work.

Description

EXTERNAL COMBUSTION ROTARY VANE ENGINE

THIS INVENTION relates to an engine.

According to one aspect of the invention there is provided an engine which includes a housing defining a rotor chamber in a pair of transversely spaced side walls and a cylindrical transversely extending connecting wall, the rotor chamber having a first part circular lobe and a second part circular lobe, the lobes having a pair of circumferentially spaced interfaces; a rotor rotatably mounted within the rotor chamber concentrically with the first lobe and eccentrically relative to the second lobe; combustion chamber defining means defining a combustion chamber having a combustion chamber inlet through which air can be fed into the combustion chamber and a combustion chamber exhaust outlet; fuel supply means for feeding fuel to the combustion chamber; a rotor chamber inlet which leads into the rotor chamber at or adjacent one interface between the first and second lobes, the rotor chamber inlet being in flow communication with the outlet of the combustion chamber to permit exhaust gases to be fed from the combustion chamber into the rotor chamber behind a trailing edge of the seal thereby to drive the rotor; and at least one rotor chamber outlet which leads from the rotor chamber at or adjacent the other interface between the first and second lobes to facilitate the discharge, from the rotor chamber, of exhaust gases contained within the rotor chamber ahead of a leading edge of the seal.

The engine may include a compressor having a low pressure air inlet and a high pressure air outlet which is in flow communication with the combustion chamber inlet. The compressor may include a housing defining a compressor chamber in a pair of transversely spaced side walls and a cylindrical transversely extending connecting wall, the compressor chamber having a part circular first lobe and a second part circular lobe, the lobes having a pair of circumferentially spaced interfaces; a compressor rotor rotatably mounted within the compressor chamber concentrically with the first lobe and eccentrically relative to the second lobe; an inlet which leads into the compressor chamber at or adjacent an interface between the first and second lobes; and at least one outlet which leads from the compressor chamber at or adjacent the other interface between the first and second lobes, the at least one outlet being in flow communication with the combustion chamber inlet.

The rotor may be drivingly connected to the compressor. Typically, the rotor is drivingly connected to the compressor rotor through a gear train.

The engine may include a pressure regulator for regulating the pressure of air being fed, in use, into the combustion chamber. The engine may include a compressed air reservoir which is connected in flow communication between the compressor and the combustion chamber, the pressure regulator comprising a pressure relief valve connected to the reservoir to regulate the pressure of air contained therein.

Valve means may be provided for regulating the flow of compressed air from the compressed air reservoir into the combustion chamber and flow of combustion gases, i.e. the high pressure gases which result from combustion of an air/fuel mixture in the combustion chamber, from the combustion chamber into the rotor chamber.

The combustion chamber may be of a fixed volume.

The or each rotor may include a seal arrangement. The or each rotor may include a pair of diametrically opposed seals mounted thereon, the seals being displaceable radially relative to the rotor to permit the seals to remain in contact with or in close proximity with at least the portion of the connecting wall in the second lobe.

Each seal may include a guide member which protrudes transversely from the associated rotor parallel with the axis about which the rotor is rotatable and engages an arcuate slide which is mounted in a circular guide channel in one of the side walls, the guide channel being concentric with the second lobe, the guide member being mounted in the slide so that as the rotor rotates the seal member is displaced in a reciprocating fashion radially relative thereto, or the seal member continuously changes position relative to the rotor. Preferably, a guide member protrudes transversely from each seal, each guide member engaging an arcuate slide.

The engine may include two combustion chambers, the outlets of which are connectable alternately in flow communication with the rotor chamber inlet so that, in use, the combustion gases from one of the combustion chambers are fed into the rotor chamber behind a trailing edge of one of the seals and combustion gases from the other of the combustion chambers are fed into the rotor chamber behind a trailing edge of the other of the seals. Hence the rotor experiences two driving pulses or strokes per rotation thereof.

The fuel may be a liquid hydrocarbon, the fuel supply means including a fuel injector arranged to inject fuel into the combustion chamber. The fuel supply means may include a pump for supplying fuel under pressure to the fuel injector, the pump being driven from the rotor, e.g. by means of a cam mounted on a shaft of the rotor.

The fuel pump may have an inlet which is connected in flow communication with a fuel tank and an outlet which is connected in flow communication with the fuel injector.

According to another aspect of the invention there is provided an engine which includes a compressor having an inlet and an outlet; a combustion chamber having an inlet connected in flow communication with the outlet of the compressor and an exhaust outlet; fuel supply means for supplying fuel to the combustion chamber; and a power unit connected to the exhaust outlet of the combustion chamber for converting energy released due to combustion into useful work.

The engine may include a compressed air reservoir positioned intermediate the compressor and the combustion chamber. The compressed air reservoir may include a pressure relief valve configured to regulate the pressure within the compressed air reservoir thereby to supply air to the combustion chamber at a more or less constant pressure in use.

The power unit may include a housing defining a rotor chamber between a pair of transversely spaced side walls and a cylindrical transversely extending connecting wall, the chamber having a first part circular lobe and a second part circular lobe with a pair of circumferentially spaced interfaces between the first and second lobes; a rotor rotatably mounted within the rotor chamber concentrically with the first lobe; a seal mounted on the rotor and configured to form a seal at least with the walls in the second lobe as the rotor rotates; an inlet which is connected to the outlet of the combustion chamber whereby combustion gases being exhausted from the combustion chamber can be fed into the rotor chamber of the power unit behind a trailing edge of the seal thereby to drive the rotor ; and at least one exhaust gas outlet leading from the rotor chamber so as to facilitate the discharge of exhaust gases contained within the rotor chamber ahead of the leading edge of the seal.

The compressor may be of similar construction to the power unit. More particularly, the compressor may include a housing defining a compressor chamber in a pair of transversely spaced side walls and a cylindrical transversely extending connecting wall, the compressor chamber having a first part circular lobe and a second part circular lobe, the lobes having a pair of circumferentially spaced interfaces; a compressor rotor rotatably mounted within the compressor chamber concentrically with the first lobe and eccentrically relative to the second lobe; a seal mounted on the compressor rotor and configured to seal at least with the walls in the second chamber as the rotor rotates; an inlet which leads into the compressor chamber at or adjacent an interface between the first and second lobes; and the outlet leading from the compressor chamber at or adjacent the other interface between the first and second lobes.

The compressor may be arranged to compress the air to raise the temperature of the air sufficiently such that the temperature of an air-fuel mixture contained within the combustion chamber is sufficiently high to cause combustion thereof in the manner of a compression ignition engine.

Instead , the air/fuel mixture contained within the combustion chamber may be ignited by means of a spark in the manner of a spark ignition engine.

The invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings.

In the drawings,

FIGURE 1 shows a side view of an engine in accordance with the invention;

FIGURE 2 shows an end view of the engine of Figure 1 ;

FIGURE 3 shows a sectional view taken at Ill-Ill in Figure 2;

FIGURES 4 to 7 show three-dimensional fragmentary views of the engine from different views with different components omitted for the sake of clarity;

FIGURE 8 shows a fragmentary plan view;

FIGURE 9 shows a three-dimensional fragmentary view;

FIGURE 10 shows a three-dimensional view of a fuel injector and relief valve support; FIGURE 11 shows a plan view of the support of Figure 10;

FIGURE 12 shows a sectional view taken at XII-XII in Figure 11 ;

FIGURE 13 shows a sectional view taken at XIII-XIII in Figure 11 ;

FIGURE 14 shows a three-dimensional view of a seal element of the invention;

FIGURE 15 shows a three-dimensional view of the seal element of Figure 14 from an opposite side thereof;

FIGURE 16 shows a side view of the seal element of Figures 14 and 15; FIGURE 17 shows a side view of a rotor element of the engine;

FIGURE 18 shows an end view of the rotor element;

FIGURE 19 shows a sectional view of the rotor element of Figure 18;

FIGURE 20 shows a three-dimensional view of an internal surface of a side member of the engine; FIGURE 21 shows a sectional elevation of a central member of the engine;

FIGURE 22 shows a three-dimensional view of the engine with certain components omitted for the sake of clarity;

FIGURE 23 shows a three-dimensional view of the engine with certain components omitted for the sake of clarity;

FIGURE 24 shows a longitudinal vertical section through the engine;

FIGURE 25 shows a longitudinal horizontal section through the engine;

FIGURE 26 shows a three-dimensional view of another engine in accordance with the invention; FIGURE 27 shows an oblique view of a central member of the engine of Figure 26;

FIGURES 28 to 30 show oblique views from different angles of the engine of Figure 26 with certain components omitted for the sake of clarity; and FIGURE 31 shows a three-dimensional view of the rotors and shafts of the engine of Figure 2.

In the drawings, reference numeral 10 refers generally to an engine in accordance with the invention. The engine 10 includes a housing 12. The housing 12 includes a central member 14, a pair of side members 16, 18 mounted on opposite sides of the central member 14 and a fuel injector and relief valve support 20 mounted on the central member 14. Covers 22, 24 are mounted respectively on the outer surfaces of the side members 16, 18.

The engine 10 includes a compressor, generally indicated by reference numeral 26 and a power unit, generally indicated by reference numeral 28.

The compressor 26 includes a compressor chamber 30 which has a pair of side walls 32, 34 defined by the side members 16, 18, respectively and a cylindrical transversely extending connecting wall 36 defined in the central member 14. The compressor chamber 30 has a first part circular lobe 38 and a second part circular lobe 40, the lobe 40 having a diameter which is greater than that of the lobe 38. The lobes have a pair of circumferentially spaced interfaces 42, 44. A circular cylindrical compressor rotor 46 is mounted in the chamber 30 concentrically with the first lobe 38 for rotation about an axis of rotation 48. The rotor 46 is hence eccentric relative to the second lobe 40 such that a generally crescent-shaped cavity 50 is defined in the second lobe 40 between the radially outer surface of the rotor 46, the portions of the side walls 32, 34 protruding beyond the rotor 46 and the portion of the connecting wall 36 extending therebetween.

As can best be seen in Figures 3, 18 and 19, the rotor 46 has a diametrically extending slot 52 extending therethrough. With the exception of a central region 55 (Figures 18 and 19), the slot 52 extends for the full width of the rotor 46. A pair of substantially identical seal elements 54 is mounted in the slot 52. As can best be seen in Figures 14 to 16 of the drawings, each seal element 54 includes a generally rectangular body 56 having an outer edge 58 and side edges 60 in which recesses 62 are provided in which contact or seal members 64 are receivable. A pair of oppositely disposed guide pins 66 protrude transversely from the body 56. Further, a lug 68 protrudes from an inner end of the body 56. The lug 68 has a guide pin 70 protruding therefrom and a parallel hole 72 provided therein.

The seal elements 54 are inserted into the slot 52 in the rotor 46 from opposite ends thereof such that the pin 70 of one seal element 54 is positioned in the hole 72 of the other seal element 54, thereby connecting the seal elements 54 together whilst permitting a degree of relative movement towards and away from one another. The pins 66 protrude transversely from the rotor 46 and parallel with the axis of rotation 48 and are received in complementary holes 74 provided in arcuate slides or shoes 76 (Figure 4) which in turn are mounted in circular guide channels 78 (Figure 20) provided in the side walls 32 and 34 (Figure 4). The guide channels 78 are concentric with the second lobe 40. The positions of the pins 66 and channels 78 are selected such that, as the rotor rotates, the radially outer surface of each seal element 54 will describe a circle corresponding closely to that of the second lobe 40.

An inlet 80 opens into the chamber 30 adjacent to the interface 42. The inlet 80 is connected to atmosphere through an air filter 82. An outlet 84 leads from the chamber 30 adjacent the interface 44. Three non-return valves 86 are provided at the outlet 84. The rotor shaft 47 protrudes transversely from the chamber 30 and is supported on bearings 88 (Figure 9 and 25).

The outlet 84 feeds into a compressed air reservoir 90 (Figure 21 ) defined in the connecting wall 36.

A pair of transversely spaced combustion chambers 92, 94 (parts of which are shown in Figure 6) is defined between the central member 14 and the support 20. Each combustion chamber 92, 94 is generally ovoid in shape, to ensure complete combustion, and has an inlet which is connected in flow communication with the compressed air reservoir 90, the flow of compressed air through the inlets being regulated by valves 98. Further, each combustion chamber 92, 94 has an outlet and the flow of exhaust gas therethrough is regulated by valves 102. Fuel injectors 104 are mounted on the support 20 for injecting liquid hydrocarbon fuel or other fuel under pressure into the combustion chambers 92, 94.

The power unit 28 is substantially identical in construction to the compressor 26. The power unit 28 includes a chamber 106 defined between the transversely spaced side walls 32, 34 and a transversely extending connecting wall 112. The chamber 106 has a first lobe 114 and a second lobe 116. The second lobe 116 is of greater diameter than the first lobe 114. The lobes 114, 116 have a pair of circumferentially spaced interfaces 118, 120. A circular cylindrical rotor 122 is supported on a shaft 124 which protrudes transversely from the chamber 106 for rotation about an axis of rotation 126 which is parallel with the axis 48. The rotor 122 is mounted concentrically with the first lobe 114 and eccentrically relative to the second lobe 116 such that a crescent-shaped cavity 128 is defined between a radially outer surface of the rotor 122 and portions of the side walls 32, 34 and connecting wall 112. The rotor 122 is substantially identical in shape to the rotor 46 and has seal elements 130 which are substantially identical to the seal elements 54 mounted therein. Displacement of the seal elements 130 relative to the rotor 122 is achieved by means of slides 132, substantially identical to the slides 76, which slides 132 are slidably mounted in annular channels 134 provided on the side members 16, 18. The shaft 124 is supported in bearings 136. An inlet 138 (Figure 21 ) leads into the cavity 128 at or adjacent the interface 118 and an outlet 140 leads from the cavity 128 at or adjacent the interface 120. The inlet 138 is connected in flow communication with the combustion chamber outlets 100. The outlet 140 leads to atmosphere through an exhaust pipe 142 which may, if desired, incorporate one or more mufflers.

A drive gear 144 is mounted on the shaft 124. A driven gear 146 is mounted on the shaft 47 and drive from the drive gear 144 to the driven gear 146 is through an intermediate gear 148 mounted on a shaft 149. The gears 144, 146, 148 are all substantially identical so that the rotors 46, 122 are rotationally synchronized. Control of the valves 98, 102 is by means of push rods 150, 152 which are driven via cams mounted on the shaft 124 and the intermediate shaft 149, respectively. In use, the compressor rotor 46 is displaced in the direction of arrow 154. As can be seen in Figure 3 of the drawings, as the rotor 46 rotates, the radially outer edges of the seal elements 54 describe a circle which corresponds to a circle having a diameter and centre which is substantially coincident with that of the lobe 40. Hence, the radially outer surface of the seal elements 54 will be in contact with or closely spaced from the surface of the connecting wall 36 forming the cavity 50. However, as the seal element passes the interface 44, it is retracted into the rotor 46. The seal members 64 may be designed that upon initial operation of the engine, there is slight contact between the seal members and the adjacent surfaces, the surfaces of the seal members wearing off to a point of minimum contact providing a low friction seal between the seal elements and the surfaces of the side walls 32, 34 and the connecting wall 36. It will be appreciated that as a seal element 54 passes the inlet 80, the volume of the cavity 50 behind a trailing edge of the seal element 54 will increase, thereby drawing air through the air filter 82 and the inlet 80 into the cavity 50. Correspondingly, as the rotor rotates, the volume of the cavity 50 ahead of the leading edge of the seal element 54 decreases such that air contained in the cavity ahead of the seal element 54 is compressed and discharged through the outlet 84 through the non-return valve 86 into the compressed air reservoir 90. A pressure relief valve 156 is connected in flow communication with the compressed air reservoir 90 to limit the pressure of air contained therein to a maximum desired pressure, typically 2300 - 3000 kPa when using diesel fuel. It will be appreciated that the pressure can vary depending on the type of fuel used.

The valves 98 are operated alternately and regulated by cams corresponding to the position of the rotor 122. Accordingly, compressed air is fed through the valve 98 from the reservoir 90 into the combustion chamber 92. Fuel is then injected through the fuel injector 104 into the combustion chamber 92. The air is compressed sufficiently by the compressor 26 such that the temperature of air contained within the combustion chamber 92 is sufficiently high to ignite the fuel. In this regard, to facilitate starting of the engine, a glow plug or spark plug (not shown) may be provided to ignite the air/fuel mixture on start-up.

As one of the seal elements 130 mounted on the rotor 122 passes the inlet 138, the valve 102 opens, permitting exhaust gases to be discharged from the combustion chamber 92 through the outlet 100 into the cavity 128 immediately behind the seal element 130. By virtue of the pressure on the trailing surface of the seal element 130, the expanding combustion gases drive the rotor in the direction of arrow 158. It will be appreciated, once again, that gases contained in the cavity 128 ahead of the seal element 130 will be compressed, by virtue of the reducing volume of the cavity 128 and will be discharged through the outlet 140 and the exhaust pipe 142 to atmosphere. It will be appreciated that the exhaust gases from the combustion chamber will be at maximum pressure and temperature just as the valve 102 opens. This will be synchronized so that it opens as the seal element 130 passes the inlet 138 and enters the second lobe 116. At this point, the seal element 130 barely protrudes from the rotor such that the area of the seal element 130 exposed to the high pressure gases is relatively small thereby reducing the leverage on the seal element. The extent to which the seal element 130 protrudes from the rotor continues to increase to a maximum when the rotor is in the position shown in Figure 3 of the drawings where the depth of the chamber 106 is at a maximum. Thereafter, the seal element 130 retracts so that at the interface 120 it withdraws into the rotor 122.

Similarly, air is fed from the reservoir 90 into the combustion chamber 94 and is discharged through the outlet 100 into the cavity 128 immediately behind the other seal element 130. Hence, ignition of the fuel in the combustion chambers 92, 94 occurs at intervals corresponding to a rotation of the rotor through 180°. In other words, two combustion cycles occur per rotation of the rotor.

The chamber 106 is larger than the chamber 30. Accordingly, vacuum relief valves 180 are provided in the transversely spaced side walls to permit air to be fed from atmosphere into the cavity 128. This arrangement prevents the creation of a zone of sub-atmospheric pressure in the cavity 128 behind the trailing edge of the seal when the engine is operating at low loads, e.g. when idling.

As mentioned above, drive to the rotor 46 is from the rotor 122 through the intermediate gear 148.

Each of the shafts 47, 124 and 149 protrude from the housing 12 and could be used as a drive source, e.g. for a vehicle.

Reference is now made to Figure 26 to 31 of the drawings, in which reference numeral 200 refers generally to another engine in accordance with the invention and, unless otherwise indicated, the same reference numerals used above are used to designate similar parts.

The main difference between the engines 200 and 10 is in the configuration of the fuel injector and relief valve support 20. Further, in the case of the engine 200, a gate valve 202 is positioned in the reservoir chamber. The valve 202 is mechanically operated by means of a cam 204 fitted on the intermediate shaft 149 to operate a push rod 206 to open the gate valve 202. The gate valve 202 is retained in a closed position by means of a spring 208 and is opened at the appropriate time in order to permit compressed air to flow from the reservoir to the combustion chamber.

The engine 200 operates in substantially the identical fashion to the engine 10 described above.

The inventor believes that advantages of the engine compared with conventional ignition engines of which he is aware include that by virtue of the fact that combustion occurs in a combustion chamber of constant volume, complete combustion can be achieved thereby releasing maximum energy from the fuel consumed which in turn leads to increased efficiency. Further, by designing the engine such that the volume of the combustion chamber and that of the cavity 128 are selected such that the exhaust gases expand to the optimum level, typically slightly above atmospheric pressure, efficiency can be further improved.

The engine incorporates relatively little reciprocating mass and as a result vibration and friction can be reduced thereby ensuring effective cooling and sealing.

By varying the pressure at which the pressure relief valve opens, the pressure of air which is fed to the combustion chamber can be varied.

By virtue of the fact that the exhaust gases are almost fully expanded in the cavity 128, noise levels are kept to a minimum and the inventor believes that the engine may operate without the requirement of an expensive energy consuming muffler system.

By virtue of the fact that complete combustion occurs in the combustion chamber, there is substantially less air pollution and smoke emission. Accordingly, relatively low grade fuels can be used.

The specific design of the engine results in a very compact engine having low weight relative to its power output.

The mechanical simplicity of the engine will, the inventor believes, lead to substantial reduction in cost associated with manufacturing and maintenance.

Claims

1. An engine which includes a housing defining a rotor chamber in a pair of transversely spaced side walls and a cylindrical transversely extending connecting wall, the rotor chamber having a first part circular lobe and a second part circular lobe, the lobes having a pair of circumferentially spaced interfaces; a rotor rotatably mounted within the rotor chamber concentrically with the first lobe and eccentrically relative to the second lobe; combustion chamber defining means defining a combustion chamber having a combustion chamber inlet through which air can be fed into the combustion chamber and a combustion chamber exhaust outlet; fuel supply means for feeding fuel to the combustion chamber; a rotor chamber inlet which leads into the rotor chamber at or adjacent one interface between the first and second lobes, the rotor chamber inlet being in flow communication with the outlet of the combustion chamber to permit exhaust gases to be fed from the combustion chamber into the rotor chamber behind a trailing edge of the seal thereby to drive the rotor; and at least one rotor chamber outlet which leads from the rotor chamber at or adjacent the other interface between the first and second lobes to facilitate the discharge, from the rotor chamber, of exhaust gases contained within the rotor chamber ahead of a leading edge of the seal.

2. An engine as claimed in claim 2, which includes a compressor having a low pressure air inlet and a high pressure air outlet which is in flow communication with the combustion chamber inlet.

3. An engine as claimed in claim 2, in which the compressor includes a housing defining a compressor chamber in a pair of transversely spaced side walls and a cylindrical transversely extending connecting wall, the compressor chamber having a first part circular lobe and a second part circular lobe, the lobes having a pair of circumferentially spaced interfaces; a compressor rotor rotatably mounted within the compressor chamber concentrically with the first lobe and eccentrically relative to the second lobe; an inlet which leads into the compressor chamber at or adjacent an interface between the first and second lobes; and at least one outlet which leads from the compressor chamber at or adjacent the other interface between the first and second lobes, the at least one outlet being in flow communication with the combustion chamber inlet.

4. An engine as claimed in claim 3, in which the rotor is dhvingly connected to the compressor.

5. An engine as claimed in claim 4, in which the rotor is dhvingly connected to the compressor rotor through a gear train.

6. An engine as claimed in any one of claims 3 to 5, inclusive, which includes a pressure regulator for regulating the pressure of air being fed, in use, into the combustion chamber.

7. An engine as claimed in claim 6, which includes a compressed air reservoir which is connected in flow communication between the compressor and the combustion chamber, the pressure regulator comprising a pressure relief valve connected to the reservoir to regulate the pressure of air contained therein.

8. An engine as claimed in claim 7, in which valve means is provided for regulating the flow of compressed air from the compressed air reservoir into the combustion chamber and flow of combustion gases from the combustion chamber into the rotor chamber.

9. An engine as claimed in claim 8, in which the combustion chamber is of a fixed volume.

10. An engine as claimed in any one of the preceding claims in which the or each rotor includes a seal arrangement.

11. An engine as claimed in claim 10, in which the or each rotor includes a pair of diametrically opposed seals mounted thereon, the seals being displaceable radially relative to the rotor to permit the seals to remain in contact with or in close proximity with at least the portion of the connecting wall in the second lobe.

12. An engine as claimed in claim 11 , in which each seal includes a guide member which protrudes transversely from the associated rotor parallel with the axis about which the rotor is rotatable and engages an arcuate slide which is mounted in a circular guide channel in one of the side walls, the guide channel being concentric with the second lobe, the guide member being mounted in the slide so that as the rotor rotates the seal member is displaced in a reciprocating fashion radially relative thereto.

13. An engine as claimed in claim 11 or claim 12, which includes two combustion chambers, the outlets of which are connectable alternately in flow communication with the rotor chamber inlet so that, in use, the combustion gases from one of the combustion chambers are fed into the rotor chamber behind a trailing edge of one of the seals and combustion gases from the other of the combustion chambers are fed into the rotor chamber behind a trailing edge of the other of the seals.

14. An engine as claimed in any one of the preceding claims, in which the fuel supply means includes a fuel injector arranged to inject fuel into the combustion chamber.

15. An engine as claimed in claim 14, in which the fuel supply means includes a pump for supplying fuel under pressure to the fuel injector, the pump being driven from a cam mounted on a rotor shaft.

16. An engine which includes a compressor having an inlet and an outlet; a combustion chamber having an inlet connected in flow communication with the outlet of the compressor and an exhaust outlet; fuel supply means for supplying fuel to the combustion chamber; and a power unit connected to the exhaust outlet of the combustion chamber for converting energy released due to combustion into useful work.

17. An engine as claimed in claim 16, which includes a compressed air reservoir positioned intermediate the compressor and the combustion chamber.

18. An engine as claimed in claim 17, in which the compressed air reservoir includes a pressure relief valve configured to regulate the pressure within the compressed air reservoir thereby to supply air to the combustion chamber at a more or less constant pressure in use.

19. An engine as claimed in any one of claims 16 to 18, inclusive, in which the power unit includes a housing defining a rotor chamber between a pair of transversely spaced side walls and a cylindrical transversely extending connecting wall, the chamber having a first part circular lobe and a second part circular lobe with a pair of circumferentially spaced interfaces between the first and second lobes; a rotor rotatably mounted within the rotor chamber concentrically with the first lobe; a seal mounted on the rotor and configured to form a seal at least with the walls in the second lobe as the rotor rotates; an inlet which is connected to the outlet of the combustion chamber whereby combustion gases being exhausted from the combustion chamber can be fed into the rotor chamber of the power unit behind a trailing edge of the seal thereby to drive the rotor ; and at least one exhaust gas outlet leading from the rotor chamber so as to facilitate the discharge of exhaust gases contained within the rotor chamber ahead of the leading edge of the seal.

20. An engine as claimed in claim 19, in which the compressor includes a housing defining a compressor chamber in a pair of transversely spaced side walls and a cylindrical transversely extending connecting wall, the compressor chamber having a first part circular lobe and a second part circular lobe, the lobes having a pair of circumferentially spaced interfaces; a compressor rotor rotatably mounted within the compressor chamber concentrically with the first lobe and eccentrically relative to the second lobe; a seal mounted on the compressor rotor and configured to seal at least with the walls in the second chamber as the rotor rotates; an inlet which leads into the compressor chamber at or adjacent an interface between the first and second lobes; and the outlet leading from the compressor chamber at or adjacent the other interface between the first and second lobes.

21. An engine as claimed in claim 1 or claim 16 substantially as described and illustrated herein with reference to the drawings.