WO1986003558A1

WO1986003558A1 - Rotary engine with external combustion chamber

Info

Publication number: WO1986003558A1
Application number: PCT/AU1985/000311
Authority: WO
Inventors: Bryan John Davies; Geoffrey Phillip Danes
Original assignee: Bryan John Davies; Geoffrey Phillip Danes
Priority date: 1984-12-10
Filing date: 1985-12-10
Publication date: 1986-06-19
Also published as: EP0203973A1

Abstract

A rotary piston engine is supplied with high pressure working fluid from an external combustion chamber (not shown). Air is inducted through intake port (16), compressed and delivered via port (17) to the external combustion chamber where, with the addition of fuel, a continuous combustion process takes place. High pressure gases from the combustion chamber pass through port (18) for expansion within the working space and exhaust via exhaust port (19). The engine may consist of a number of rotary pistons driving a common output shaft and the air inducted through intake port (16) may be pressurized by an exhaust-driven turbo charger. Also disclosed is an arrangement of partitions within port (17) to reduce air leakage past the apex seals (10) as these seals traverse the port (17).

Description

ROTARY ENGINE WITH EXTERNAL COMBUSTION CHAMBER

This invention relates to combustion engines wherein combustion is maintained substantially continuously in a chamber, and the high pressure combustion gas is expanded in a variable volume chamber of the engine to 5 develop torque.

Internal combustion engines are currently used extensively, particularly as the means of driving vehicles. Because of the intermittent nature of the combustion of the fuel in such engines, and the short duration of each ^*-^* combustion cycle, it is difficult to obtain complete combustion of the fuel available to be burnt during each cycle. This naturally leads to unburnt and partial burnt fuel being discharged for the engine. The fuel efficiency of such such engine is thus far from the theoretically 5 attainable value, and the exhaust gas is high in pollutants. Current laws in many countries require vehicles to have equipment to treat the exhaust gas to remove or reduce harmful pollutants before the exhaust gas is released to the atmosphere. 0 These problems, inherent with internal combustion engines, are known to be substantially reduced if there is continuous combustion of the fuel , preferable externally of the chamber in which the gases are expanded to extract energy therefrom as usable motive power. One application of

25 this principle is a gas turbine, however, they have the disadvantage of a relatively limited operational speed range. The restricted speed range results in gas turbines not being acceptable as an alternative to the internal combustion engine in many applications, and particularly

30 in vehicles.

Numerous proposal for engines operating on the continuous combustion cycle have been presented over the years but so far as is known a commercially acceptable form of this type of engine has not been produced.

^■*^•'-' It is the object of this invention to provide a continuous combustion engine that is suitable for use as the source of motive power for a vehicle, and may be economically applied to engines of a known basic construction currently operating on the Otto combustion cycle.

With this object in view there is provided by the present^" invention a continuous combustion engine comprising a housing defining a main chamber, a shaft journalled for rotating in said housing, a piston member disposed within said main chamber and supported on the shaft to rotate on an axis eccentric to the rotation axis of the shaft, said piston member and main chamber being shaped and arranged to define two or more working chambers which vary in volume as the piston member rotates on its axis and that axis rotates about the rotational axis of the shaft, said piston member being operably connected to the shaft to rotate same as the piston member rotates, air inlet and outlet ports ^• communicating with the main chamber and arranged so each working chamber communicates with the air inlet and outlet port- in sequence as the piston member rotates and the air in the working chamber is compressed as it is conveyed from the inlet to the outlet port, working gas inlet and outlet ports communicating with the main chamber and arranged so each working chamber communicates with the gas inlet and outlet ports in sequence as the piston member rotates and subsequent to communication with the air outlet and gas inlet ports, a combustion chamber in communication with the air outlet and gas inlet ports to receive compressed air from and deliver combustion gases to the main chamber, fuel means operative associated with said combustion chamber to supply fuel thereto in accordance with the engine load demand and to maintain combustion therein while the engine is operating to provide combustion gases to the working chambers in sequence.

Preferably the opening and closing of the respective ports is controlled by the co-operation of the piston member with the portions of the surface of the main chamber in which the ports are located as the piston member rotates. Some of the ports may be arranged in the peripheral surface of the main chamber, and preferably the air inlet port is located in a wall of the chamber normal to the rotor axis.

Conveniently the air outlet port communicating the working chambers with the combustion chamber is provided with an automatic or passive type valve which only opens when the pressure in the working chamber is above that in the combustion chamber. This valve prevents flow back of combustion gas from the combustion chamber during the initial part of the air compression cycle, when the air pressure in the working chamber is substantially below the combustion chamber pressure. Also the air outlet port may be of a labyrinth construction so that it is uncovered in steps as the edge of the piston member travels across the port. This reduces the communicat^'ion that may occur between the respective adjacent working chamber as the edge of the piston member travels across the port. Such free communication can result in substantial loss of compression pressure.

It is also desirable to adapt the peripheral surfaces of the piston member and main chamber so that there is minimum working clearance therebetween in that portion of the chamber between the air outlet and gas inlet ports. This also contributes to a reduction of pressure loss between the working chamber effecting compression of the incoming air and the working chamber receiving high pressure combustion gas from the combustion chamber. In this regard it is convenient for the surface of the piston member to be flat in the direction parallel to the axis of the piston member axis.

In order to avoid loss of volumetric compression ratio in the engine the valve associated with the air outlet port should be located close to the peripheral surface of the main chamber, that is the axial length of - -

the port upstream of the valve should be short. Also the temperature lost from the passage leading from the air outlet port to the combustion chamber should be kept to a minimum, such as by insulation of the passage. The combustion chamber gases are of very high temperature, and the combustion chamber is not subject to the cooling effects existing in an Otto cycle engine. Accordingly the chamber will be required to be lined with suitable heat resistance materials. Likewise the gas inlet port from the combustion chamber to the working chamber will be required to be cooled without substantial loss of heat energy. This may, in part, be achieved by arranging the air flow from the air outlet port to the combustion chamber to be in close proximity to the passage leading from the combustion chamber to the gas inlet port.

Conveniently the air passage includes an annular .portion disposed about the gas passage so that the heat loss from the combustion gas in the gas passage is maintained at an acceptable temperature, and is, at least partly, taken up y the incoming air to the combustion chamber, and is therefore not a net loss to the heat balance of the engine.

The basic configuration of the main chamber and piston member may be in the form of a Wankel engine of either the single or multiple rotor type. In that engine the peripheral surface of the main chamber is epitrochoidal and the piston member is of general triangular shape with the sides of the triangle slightly convex in the direction of the length thereof. At each corner of. the triangle there is provided a seal structure extending across the external peripheral face of the piston to co-operate with the internal peripheral surface of the main chamber.

The invention will be more readily understood from the following description of one practical arrangement of the engine in accordance with the present invention with reference to the accompanying drawings.

In the drawings; Fig. 1 is a diagrammatic cross-sectional view of the housing and piston member of a typical embodiment of the engine of the present invention.

Figs. 2a to 2f are diagrammatic cross-sections of the engine showing the piston member in various positions throughout an engine cycle.

Fig. 3 is an enlarged cross-sectional view of the combustion chamber and adjacent engine housing incorporating the air outlet port and gas outlet port. 0 Fig. is an exploded view of one construction of a two rotor engine according to the present invention.

Fig. 5 is a split perspective view of one of the housing in Figure 4 showing the port arrangement.

There is illustrated diagrammatically in Fig. 1 5 the basic construction of a rotatory engine of the type commonly known as the 'Wankel' rotatory engine and having a port arrangement devised to enable that engine to operate • in accordance with the continuous combustion cycle of the present invention. 0 Referring now to Fig. 1, the housing 3 may have any appropriate external shape with an internal cavity 4 of epitrochoidal shape with a peripheral wall .7 and opposite substantially flat end walls 8. The piston member 12 is located within the cavity 4 and supported to rotate on the 5 axis 2, eccentric to the axis 6 of the shaft 9. The shaft is journal in bearing in the end walls 8 of the cavity 4.

The piston member 12 is of a generally triangular shape carrying peripheral seals 10 at each corner thereof, engaging with the peripheral wall 7 of the cavity 4, ^*-^* throughout the total movement of the piston member within the cavity. End seals 14 are provided in end faces 13 of the piston member 12 to engage the end walls 8 of the cavity 4. The main chamber or cavity 4 and piston member 12 define three working chambers 15 which vary in volume as the piston member rotates.

It will be noted in Fig. 1 that in the areas X on the minor axis Y-Y of the epitrochoidal shaped cavity 4, there is a minimum clearance between the peripheral surface of the cavity 4 and piston member 12. This minimal clearance relation exist in the areas X at all times as the piston member rotates in the cavity.

The internal peripheral wall 7 of the cavity 4 is of a smooth continuous surface in the peripheral direction, and is flat and parallel to the piston axis along any line parallel to the piston axis. The triangular shaped peripheral surface of the piston member is made up of three arcuate portions 11, each of which is a smooth continuous convex surface in the peripheral direction, and is flat and parallel to the piston axis along any line parallel to the piston axis. The peripheral seal means 10, located at the junctions of the arcuate portions 11 , are mounted in respective slots in the piston member. The seal means 10 extend transversely of the piston member peripheral surface for the full axial extent thereof, and parallel to the piston member axis. The seal means 10 engage in sealing contact the peripheral wall 7 of the cavity 4, and maintain that engagement throughout the movement of the piston member within the cavity 4. The seal means 10 thus divide the cavity 4 into three working chambers that vary in volume as the piston member moves in the cavity 4.

The modification of the engine to operate on the continuous combustion cycle requires the provision of an air inlet port 16 and an air outlet port 17 in the portion of the cavity 4 above the minor axis Y-Y, as seen in Fig. i, and a gas inlet port 18 and gas outlet port 19 on the opposite side or below the minor axis Y-Y. The air inlet port 16 is in communication with atmospheric air, preferably through an air filter (not shown) , and the gas outlet port 19 communicates with an engine exhaust system. The air outlet port 17 and gas inlet port 18 communicates with a combustion chamber 20.

Referring to Figs. 2a to 2d inclusive, a cycle of one working chamber of the engine occupying one revolution of the piston member 12 will be described. The piston member is rotating in a clockwise direction as seen in Fig. 2a.

Starting at Fig. 2a, the peripheral seal 10a on the piston member 12 has just past the air inlet port 16 and so a small working chamber 21 is formed between seal 10a and area X_ of the housing 3. As the piston member rotates clockwise the volume of the working chamber 21 increase and so air is drawn there into through the port 16 (Fig. 2b). As the seal 10b passes the air inlet port 16 (Fig. 2c) the seal 10a has passed the air outlet port 17 and is approaching area X„ of the housing 3, which is opposite X, on the minor axis of cavity 4. Further clockwise movement of the piston member produces a progressive decrease in the volume of the working chamber 21, and a resulting compression of the air therein. When the pressure in the working chamber is above that in the combustion chamber 20 a check valve (to be described later) in the port 17 opens and air is delivered to the combustion chamber 20 to maintain combustion therein.

Further rotation of the piston member will move the seal 10a past the gas inlet port 18 while the seal 10b is moving towards the air outlet port 17 , Fig. 2d. In this position combustion gases from the combustion chamber 20 will enter that part of the working chamber 21 between seal 10a and are X₂ while air is continued to be discharged from the part of the working chamber 21 between seal 10b and area X_ . The supply of high pressure combustion gas to the part of the working chamber 21 in advance of area X„ created a net force on the piston member between seals 10a and 10b to rotate the piston member in the clockwise direction and develop a usable torque in the shaft 9, Fig. 2e. Further rotation of the piston member 12 will take seal 10b past the gas inlet port 18 so that the working chamber 21 is isolated from the combustion chamber 20. Thereafter the seal 10a will move across the gas outlet port 19 and exhaust of the gases from the work chamber will commence, Fig. 2f. Thereafter the piston member will rotate further to return to the position shown in Fig. 2a.

In the above description we have described a full cycle of one working chamber of the engine, however, it is to be understood that, with a three sided piston member as illustrated, three working chambers pass through the same cycle in sequence. It is also to be understood that the engine may have more than one cavity 4 and complementary piston member 12, each piston member being coupled to the same shaft 9 and each cavity co-operating with the same combustion chamber 20.

^' Gas pressure in this engine, while' running, will be substantially constant from ^'air outlet port -17 to the gas outlet port 19. Power output will be proportional to this gas pressure that is developed in the combustion chamber, which may vary from near atmospheric pressure to a maximum pressure obtainable by an air/fuel ratio which provides stoichiometric -combustion at any specified engine speed. An exhaust driven turbocharger may be provided to increase the mass airflow at the air inlet port 16 and so increase the brake mean effective pressure without significantly increasing the combustion temperature.

It is apparent from the above description that the peripheral seals 10, mounted in the three corners of the piston member 12, are provided to prevent the passage of air and combustion gas between the working chambers. However, as the peripheral seals 10 travel across the ports provided in the internal peripheral surface of the cavity 4, and as the sealing face 40 of the seal 10 is generally narrower than the width of the port, in the direction of movement of the piston member, leakage may occur between working chambers as the peripheral seals pass over the port. This leakage problem will be better understood from the following description with reference to Fig. 3, which is a sectional view of the part of the housing 3 incorporating the air outlet port 17 leading from the working chamber to the combustion chamber. The piston member 12 is shown in the position where the seal 10 on the piston member 12 is mid-way in its travel across the port 17. It will be appreciated from Fig. 3 that if the port 17 was composed of a single opening there would be a substantial leakage path across the seal 10 between the working chambers on either side of the seal. Also this leakage path would be relatively short, that is, equal to the thickness of the seal 10.

In order to reduce this leakage, the port 17 is divided into a plurality of narrow port openings 42 by the transverse walls 41 , which extend across the full width of ^• the port 17 parallel to the direction of the seal 10. The walls 41 extend.into the port 17 a substantial distance from the peripheral wall 7 of the cavity 4 so that as seal ιo travels across the face of the port, the leakage path between the working' chambers is of a considerable length. That is, that leakage .path is at least twice the length of the walls 41, and is also of a smaller cross-section than exists if the walls 41 were not present. These factors will considerably reduce the quantity of air that would leak from one working chamber to the next in the time interval available as the seal 10 passes over the port 17.

This control of air leakage is particularly important in respect to the air outlet port 17 and is important, but to a somewhat lesser extent, in respect of the combustion gas outlet port 19 (exhaust). Accordingly the gas outlet port 19 may also be divided into a number of narrow ports opening the same as openings 42 in the port 17 by transverse walls the same as walls 41 in port 17. i a preferred construction the length of the walls 41 in the axial direction of the port 17 is at least 5, conveniently about 10, times the height of the individual openings 40 in the direction of the movement of the seal across the port.

A typical combustion chamber 20 is shown in Fig. 3 5 having an outer casing 24 designed to withstand forseeable maximum pressures and temperatues . Inside the casing 24 there is provided a smaller diameter combustion chamber liner 22, made of a high temperature resistant steel. An array of holes in various groupings is provided in the

I--¹ liner to create the desired airflow pattern to deflect the flame, and hence excessive heat from the liner, and to produce, as near as possible, stoichiometric combustion conditions in the combustion chamber throughout the operating speed range of the engine.

15 in order to achieve compression efficiency during the compression section of the engine cycle it is desirable to prevent a back flow air into the working chamber through the port 17. Accordingly, a floating valve 43 is located at 'the upstream end of the openings 42 in the air outlet port 0 17. The valve 43 has limited movement between the ends of the walls 41 and the stop pins 44 on the insert 45. When the pressure in the working chamber is below the pressure in the combustion chamber the valve 43 closes the openings 42 to prevent a gas flow back to the working chamber from 5 the combustion chamber. It is preferable that the valve 43 have a bias towards the position closing the openings 42 such as by a spring loading on the valve 43.

The air delivered through the air outlet port 17 passes along the passage 44 into the cavity 45 surrounding 0 the duct 46 communicating the combustion chamber 20 with the port 18. The air passes from the cavity 45 through ducts 47 into the combustion chamber in the area surrounding the liner 22. The incoming air flowing through 5 the cavity 25 and ducts 47 reduces the heat transfer from the duct 46 to the housing 3 while providing cooling of the duct 46 and preheating of the incoming air to the combustion chamber. It may be desirable to incorporate devices to control the air flow to the combustion chamber such as a flow limiting sonic choking device in the air outlet port 17, or a pressure differential regulating device in the combustion chamber liner to bypass excessive air downstream of the area of combustion. These devices are particularly useful at high speed and at low power operation. Fuel is supplied to the combustion chamber 20 through a nozzle fitted to the combustion chamber at 23, and at a pressure adequate to achieve delivery at all expected combustion chamber pressures, and to produce the required degree of atomization of the fuel for obtaining complete combustion of the fuel.

The fuel supply system may comprise a positive displacement engine driven pump supplying fuel directly and continuously to the fuel nozzle 26 in the combustion chamber. The fuel flow rate will vary from zero "to a maximum as required for stoichiometric combustion at maximum power. Fuel flow could be controlled electronically by a "spill" or "bypass" type system controlled by temperature, pressure, and power required, inputs.

. Ignition of the 'atomized fuel is by a spark igniter 24 installed in the combustion chamber. This igniter is connected to a high energy capacitor discharge electronic device, and is positioned such that it will initiate combustion at all fuel/air ratios that will be experienced under operating conditions.

Starting of the engine may be achieved by a traditional electric cranking motor or by releasing stored compressed air into the combustion chamber, while applying fuel and ignition. Compressed air could be replenished from a compressor that will be selectively coupled to the engine when running at high power. This stored air could also be released as a supplementary supply to the combustion chamber for increased power output for short periods.

One practical construction of a two rotor form of the engine will now be described with reference to Figs. 4 and 5 of the drawing.

In this drawing the engine is shown in an exploded form to reveal the internal components. The engine comprises two rotors 50 and 60 and respective rotor housings 51 and 61. Interposed between the housing 51 and 61 is the separator plate 55 which in assembly forms a wall between the rotor housings 51 and 61.

The opposite end faces 56 and 57 of the separator plate 55 abut the inner end faces 52 and 62 of the housings 51 and 61, and are in sealing engagement with the inner end faces 53 and 63 of the rotors 50 and 60. End plates 54 and 64 in assembly abut the outer end faces 58 and 68 of the housings 51 and 61, and are in sealing engagement with the outer end faces 59 and 69 of the rotors.

The end plates 54 and 64, the housings 51 and 61 and the separator plate 55 are held' together i the above assembled relation by suitable arrangement of bolts and/or. studs which have been omitted from the drawing for the purpose of clarity. It is also to be appreciated that coolant cavities and passage will be required in each of these components, and these have al-so been omitted for clarity purposes.

Each of the housings 51 and 61 together with the adjacent end plate and separator plate from a cavity in which the respective rotor 50 and 60 are disposed. Each of the rotors are supported on the crank shaft 70 which is rotatably supported in bearing in the end plates 54,64. The eccentric cranks on the crankshaft are 180 out of phase to provide even distribution of the torque inputs from the two rotors to the crankshaft.

The single combustion chamber 71 receives compressed air from, and supplies combustion gas to, each of the housings 51 and 61 through the air passage 72 and combustion gas passage 73 provided in the separator plate 55. The air passage 72 communicates with the passage 74 in the housing 51, which communicates with the air outport 75 the housing 51, which communicates with the air outport 75 and the housing 51 as seen in Fig. 5. The air passage 72 similarly communicates with a passage in the housing 61 corresponding to passage 74 in housing 51. Also the combustion gas passage 73 communicates with the passage 76 in the housing 51 which communicates with the gas inlet port 77 as seen in Fig. 5, and similarly communicates with a gas inlet port in housing 61.

In the construction shown in Fig. 4 the air inlet ports are not provided in the peripheral wall of the housings, as previously described with reference to Figs. 1 and 2a to 2f, but are provided in the end faces 56 and 57 of the separator plate 55, one air inlet port being shown at 78 in the face 57. The port 78 and a corresponding port in the opposite end face 56 each communicate with an air intake duct 79 which in use receives atmospheric air through a suitable air filter (not shown).

The disposition and shape of the port 78 is selected so that the movement of the seals provided in the end face of the rotor (as indicated at 14 in Fig. 1) will regulate communication of the respective working chambers with atmospheric air as the rotor moves in the housing. The provision of the air inlet port in the end wall of the working chamber rather than the peripheral wall provides some advantage in selection of timing of the opening and closing of the air inlet port.

The crankshaft 70 is supported in bearings provided in the end plates 54 and 64, the bearings not being shown in the drawings, but one would be located in the central opening 90 in end plate 64. In assembly the rotor 60 is supported on the eccentric journal 80 on the crankshaft, and the main journal 81 is supported in a bearing located in the opening 90.

Each of the rotors 50 and 60 are of the generally triangular shape previously referred to, and are provided at each corner with a perepheral seal 91 extending across the perepheral face of the rotor in a direction parallel to the axis of the rotor, as best seen in rotor 60 in Fig 5.

Further seals 9.2 are supported in each opposite end face of the rotor to co-operate in sealing relation with the respective adjacent faces of the end plate and separator plate. The seals 92 extend between the seals 91 and are spaced inward from the respective perepheral edges 93 of the rotor and of generally the same contour as said edges.

As can be seen in Fig 6 each of the air outlet port 95 and gas outlet port 96 are provided with transverse walls 97 and 98 respectively to divide the ports into a number of openings 99 and 100. The function of these transverse walls and the relevance thereof to the operation of the engine has been previously discussed with reference to Figure 3. The gas inlet port 101 is also shown in Fig.

In a modification of the engine previously described provision may be made for a' second stage of expansion of the combustion gas, in order to increase power output and efficiency. This may conveniently be achieved by providing a third rotor mounted on the same crankshaft as the previously described two rotors, and operating in a third epilrochoidal shaped chamber, The third rotor and chamber define two working chambers, both being expansion chambers. One of these expansion chambers would receive combustion gas from the gas outlet port of one of the existing working chambers and the other expansion chamber would receive combustion gas from the gas outlet port of the other existing working chambers. It will be appreciated that these expansion chambers provided by the third rotor and chamber must be of a greater volume than the working chamber from which they receive the combustion gas since they receive that gas at a lower pressure.

1865/621

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. A continuous combustion engine comprising a housing defining a main chamber, a shaft journalled for rotating in said housing, a piston member disposed within said main chamber and supported on the shaft to rotate on an axis eccentric to the rotation axis of the shaft, said piston member and main chamber being shaped and arranged to define two or more working chambers which vary in volume as the piston member rotates on its axis and that axis rotates about the rotational axis of the shaft, said piston member being operably connected to the shaft to rotate same as the piston member rotates, air inlet and outlet ports communicating with the main chamber and arranged so each working chamber communicates with the air inlet and outlet port in sequence as the piston member rotates and the air in the working chamber is compressed as it is conveyed from the inlet to the outlet port, working gas inlet and outlet ports communicating with the main chamber and arranged so each working chamber communicates with the gas inlet and outlet ports in sequence as the piston member rotates and subsequent to communication with the air inlet and air outlet ports, a combustion chamber in communication with the air outlet and gas inlet ports to receive compressed air from and deliver combustion gases to the main chamber, fuel means operative associated with said combustion chamber to supply fuel thereto in accordance with the engine load demand and to maintain combustion therein while the engine is operating to provide combustion gases to the working chambers in sequence, the main chamber having an internal peripheral surface and the piston member having an external peripheral surface and including a plurality of seal means carried by the piston member and spaced equally along the periphery thereof, each seal means extending transversely of the external peripheral surface of the piston member and sealably engaging the internal peripheral surface of the main chamber to divide the main chamber in a number of working chambers equal to the number of seal means, said air outlet port being located in the internal peripheral surface of the main chamber so that each seal means traverses the air outlet port as the piston rotates, at least one partition spanning said air outlet port in a direction tranverse to the direction of movement of the seal means across the air outlet port and located to sealingly engage the seal means as the latter moves across the port.

2. A continuous combustion engine as claimed in claim

1 wherein the or each partition divides the air outlet port into a number of openings spaced in the direction of movement of the seal means across said port and having a minor dimension in said direction, and the or each partition extends from the internal peripheral surface of the main chamber into said port a distance not less than said minor dimensions.

3. A continuous combustion engine as claimed in claim

2 wherein the or each partition extends from the internal peripheral surface a distance not less than five times said minor dimensions.

4. A continuous combustion engine as claimed in any one of claims 1 to 3 , at least one partition spanning the combustion gas outlet port in a direction transverse to the direction of movement of the seal means across said port and located to sealingly engage the seal means as the latter moves across the port.

5. A continuous combustion engine as claimed in claim 4 wherein the or each partition divide the combustion gas outlet port into a number of openings spaced in the direction of movement of the seal means across said port and having a minor dimension in said direction, and the or . _

each partition extends from the internal peripheral surface of the main chamber into said port a distance not less than said minor dimensions.

6. A continuous combustion engine as claimed in claim 5 wherein the or each partition extends from the internal peripheral surface a distance not less than five times said minor dimensions.

7. A continuous combustion engine as claimed in any one of the preceding claims including a first passage communicating the combustion chamber with the combustion gas inlet port and a second passage communicating the combustion chamber with the air outlet port, said first and second passages over at least part of the length being in heat transfer relation.

8. A continuous combustion engine as claimed in claim 7 wherein part of one of .said passages extends about part of the other passage.

9. A continuous combustion engine as claimed in claim 9 wherein the first passage over part of the length thereof is located within the second passage.

1865/621:mp