Rotary heat engine

Abstract

A rotary heat engine (100) comprising a rotor (200) centred on, and rotatable about, a rotational axis (202) and a stator (300) which bounds the rotor (200). The rotor (200) is rotatable relative to the stator (300) that defines a radially inner surface (304) which faces a radially outer surface (204) of the rotor (200). The rotor radially outer surface (204) defines at least one rotor combustion chamber (210) having a leading edge (212) and a trailing edge (214). The stator radially inner surface (304) defines at least one stator combustion chamber (310) having a leading edge (312) and a trailing edge (314). The number of rotor combustion chambers (210) is not equal to the number of stator combustion chambers (310). The rotor (200) comprises a first air inlet port (230) configured for communication with a source of air (600)and provided proximate to, but circumferentially spaced apart from, the or each rotor combustion chamber trailing edge (214); and the first air inlet port (230) opens on the rotor radially outer surface (204).

Description

[0001] ROTARY HEAT ENGINE

[0002] The present disclosure relates to a heat engine.

[0003] Background

[0004] As is well understood in the art, a heat engine is a system that converts heat to usable energy, particularly mechanical energy, which can then be used to do mechanical work. Heat engines provided as internal combustion engines are well known and have been developed for many years to improve their efficiency for a given power output. However, there is a pressing environmental need for further improvements in internal combustion engine design in order to reduce greenhouse gas emissions.

[0005] Hence a heat engine which is highly efficient and / or is configurable for use with environmentally friendly fuels, and yet has a comparable or greater power output than examples of the related art, is highly desirable.

[0006] Summary

[0007] According to the present disclosure there is provided an apparatus as set forth in the appended claims. Other features of the invention will be apparent from the dependent claims, and the description which follows.

[0008] Accordingly there may be provided a rotary heat engine (100). The rotary heat engine (100) may comprise a rotor (200) centred on, and rotatable about, a rotational axis (202) and a stator (300) which bounds the rotor (200). The rotor (200) may be rotatable relative to the stator (300). The stator (300) may define a radially inner surface (304) which faces a radially outer surface (204) of the rotor (200). The rotor radially outer surface (204) may define at least one rotor combustion chamber (210) having a leading edge (212) and a trailing edge (214). The stator radially inner surface (304) may define at least one stator combustion chamber (310) having a leading edge (312) and a trailing edge (314). The number of rotor combustion chambers (210) may not equal to the number of stator combustion chambers (310).

[0009] The or each rotor combustion chamber (210) may be aligned with the or each stator combustion chamber (310) on a common circumferential path centred on the rotational axis (202) such that the or each rotor combustion chamber (210) is in fluid communication with the or each stator combustion chamber (310) during a revolution of the rotor (200) about the rotational axis (202).

[0010] There may be provided an even number of rotor combustion chambers (210) and an odd number of stator combustion chambers (310).

[0011] There may be provided an odd number of rotor combustion chambers (210) and an even number of stator combustion chambers (310).

[0012] There may be provided an even number of rotor combustion chambers (210) and an even number of stator combustion chambers (310).

[0013] There may be provided an odd number of rotor combustion chambers (210) and an odd number of stator combustion chambers (310).

[0014] The number of rotor combustion chambers (210) provided may be N, and the number of stator combustion chambers (310) provided may be N+1.

[0015] The number of stator combustion chambers (310) provided may be N, and the number of rotor combustion chambers (210) may be N+1.

[0016] The or each rotor combustion chamber (210) may be provided as a recess (206) extending along part, but not all, of the rotor radially outer surface (204). The or each stator combustion chamber (310) may be provided as a recess (306) which extends along part, but not all, of the stator radially inner surface (304).

[0017] The or each rotor combustion chamber (210) may extend radially inwardly into the rotor (200) at the leading edge (212) to define a rotor step (216) with a leading edge depth (RDIe). The or each rotor combustion chamber (210) may reduce in depth towards their trailing edge (214).

[0018] The or each rotor combustion chamber (210) may be defined by a rotor surface base wall (218) which faces the stator (300) and extends from the leading edge (212) to the trailing edge (214) of the rotor combustion chamber (210) to define a rotor combustion chamber convex surface (220) extending at least part of the way from the leading edge (212) to the trailing edge (214) of the rotor combustion chamber (210).

[0019] The or each stator combustion chamber (310) may extend radially outwardly into the stator (300) at the leading edge (312) to define a stator step (316) with a leading edge depth (SDIe), the or each stator combustion chamber (310) reducing in depth towards the trailing edge (314).

[0020] The or each stator combustion chamber (310) may be defined by a stator surface base wall (318) which faces the rotor (200) and extends from the stator combustion chamber leading edge (312) to the stator combustion chamber trailing edge (314) such that the stator surface base wall (318) defines a concave surface (319) extending at least part of the way from the stator combustion chamber leading edge (312) to the stator combustion chamber trailing edge (314).

[0021] The stator combustion chamber concave surface (319) may comprise a first section (311) which extends from the stator combustion chamber leading edge (312) at the inner surface of the stator (300) to define a stator step (316), and a second section (313) which extends at an angle to the first section (311), and extends from the first section (311) towards the trailing edge (314).

[0022] The or each rotor combustion chamber (210) may extend at least 25 deg, but no more than 70 deg, around the outer circumference of the rotor (200).

[0023] The or each stator combustion chamber (310) may extend at least 15 deg, but no more than 35 deg, around the inner circumference of the stator (300).

[0024] A rotor combustion chamber wall (260) may extend from the rotor combustion chamber leading edge (212) to the rotor combustion chamber trailing edge (214) on both sides of the or each rotor combustion chamber (210) to thereby define the transverse extent of the or each rotor combustion chamber (210).

[0025] A stator combustion chamber wall (360) may extend from the stator combustion chamber leading edge (312) to the stator combustion chamber trailing edge (314) on both sides of the or each stator combustion chamber (310) to thereby define the transverse extent of the or each stator combustion chamber (310).

[0026] A first labyrinth seal (262) may be provided at the lateral edges of the rotor (200) which extends around the circumference of the rotor (200), extending over the radial land (222) of the or each rotor combustion chamber wall (260).

[0027] A layer of material (264) with a low coefficient of thermal expansion may be provided at the lateral edges of the rotor (200) which extends around the circumference of the rotor (200), extending over the radial land (222) of the or each rotor combustion chamber wall (260).

[0028] The or each stator combustion chamber (310) may be in fluid communication with a fuel source (400).

[0029] A fuel igniter (402) may be located in the or each stator combustion chamber (310).

[0030] Spaced apart from the or each stator combustion chamber (310) around the circumference of the stator radially inner surface (304), there may be provided a corresponding exhaust port (320) which opens onto the stator radially inner surface (304). The or each rotor combustion chamber (210) may extend around the circumference of the rotor radially outer surface (204) such that they span the distance between the corresponding stator combustion chamber (310) and exhaust port (320) such that during a part of a period of a revolution of the rotor (200) about the rotational axis (202) as the or each rotor combustion chamber (210) comes into fluid communication with the corresponding exhaust port (320) the corresponding stator combustion chamber (310) is in fluid communication with the rotor combustion chamber (210).

[0031] The rotor (200) may comprise a first air inlet port (230) for communication with a source of air (600), the first air inlet port (230) is provided proximate to, but circumferentially spaced apart from, the or each rotor combustion chamber trailing edge (214) and opens on the rotor radially outer surface (204).

[0032] The or each first air inlet port (230) may be located such that during a revolution of the rotor (200) about the rotational axis (202), for a part of a period when the end of the or each rotor combustion chamber (210) overlaps the corresponding stator combustion chamber (310) and exhaust port (320), the first air inlet port (230) is in flow communication with the exhaust port (320) and respective stator combustion chamber (310).

[0033] The rotor (200) may comprise a second air inlet port (232) for communication with the source of air (600), the second air inlet port (232) being provided proximate to, but circumferentially spaced apart from, the first air inlet port (230), such that the second air inlet port (232) is circumferentially spaced apart from the respective rotor combustion chamber trailing edge (214) by the respective first air inlet port (230).

[0034] The second air inlet port (232) may be located such that during a revolution of the rotor (200) about the rotational axis (202), the second air inlet port (232) is in flow communication with the or each stator combustion chamber (310) for a part of a period when the proximate rotor combustion chamber (210) is fluidly isolated from the respective stator combustion chamber (310).

[0035] The first air inlet port (230) and the second air inlet port (232) may be located such that during a revolution of the rotor (200) about the rotational axis (202) in a first subperiod of the period when the or each rotor combustion chamber (210) is fluidly isolated from the or each stator combustion chamber (310), the first air inlet port (230) and the second air inlet port (232) are in flow communication with the respective stator combustion chamber (310). The first air inlet port (230) and the second air inlet port (232) may be located such that during a revolution of the rotor (200) about the rotational axis (202) in a second subperiod of the period when the or each rotor combustion chamber (210) is fluidly isolated from the or each stator combustion chamber (310), the first air inlet port (230) is fluidly isolated from the respective stator combustion chamber (310) and the second air inlet port (232) is in flow communication with the respective stator combustion chamber (310).

[0036] The stator (300) may comprise a third air inlet port (330) for communication with the source of air (600) the third air inlet port (330) being provided circumferentially spaced apart from the corresponding exhaust port (320).

[0037] The rotary heat engine (100) may further comprise a housing (700), wherein the rotor (200) and stator (300) are located between a first housing side wall (702) and a second housing side wall (704), such that the first housing side wall (702) is spaced apart from the second housing side wall (704) along the rotational axis (202) by the rotor (200) and stator (300). Each of the first housing side wall (702) and the second housing side wall (704) may be in sealing engagement with the stator (300). A first clearance may be maintained between the first housing side wall (702) and a first side (215) of the rotor (200). A second clearance may be maintained between the second housing side wall (704) and a second side (217) of the rotor (200) so that the rotor (200) is rotatable relative to each of the first housing side wall (702) and second housing side wall (704).

[0038] A side wall inlet port (708) may be provided in the first housing side wall (702) and / or the second housing side wall (704). The external side of the side wall inlet port (708) may be configured for fluid communication with the source of air (600). The internal side of the side wall inlet port (708) may be in fluid communication with the or each first air inlet port (230) and the or each second air inlet port (232) when the or each first air inlet port (230) and the or each second air inlet port (232) pass the respective side wall inlet port (708) as the rotor (200) rotates about the rotational axis (202).

[0039] The first air inlet port (230) and / or the second air inlet port (232) may be provided as an outlet slot (270) which extend transversely across the rotor outer surface (204), wherein the outlet slot (270) extends radially into the rotor (200).

[0040] A feed slot (272) may be provided on at least one side of the rotor (200) for fluid communication with the side wall inlet port (708), the feed slot (272) being provided as a recess which extends part, but not all, of the way around the or each side of the rotor (200).

[0041] The outlet slot (270) may be in fluid communication with the feed slot (272) via a passage (274) in the rotor (200). A second labyrinth seal (263) may be provided on each the side of the rotor (200). Each second labyrinth seal (263) may extend around a diameter the rotor (200). Each second labyrinth seal (263) may be provided between the side of the rotor (200) and a respective housing side wall (702, 704). The second labyrinth seal (263) may extend at a smaller diameter than the first labyrinth seal (262). The feed slot (272) may be being provided between the first labyrinth seal (262) and the second labyrinth seal (263).

[0042] There may be provided a method of operation of a rotary heat engine (100). The rotary heat engine (100) may comprise a rotor (200) centred on, and rotatable about, a rotational axis (202) and a stator (300) which bounds the rotor (200). The rotor (200) may be rotatable relative to the stator (300). The stator (300) may define a radially inner surface (304) which faces a radially outer surface (204) of the rotor (200). The rotor radially outer surface (204) may define at least one rotor combustion chamber (210). The stator radially inner surface (304) may define at least one stator combustion chamber (310). The number of rotor combustion chambers (210) may not be equal to the number of stator combustion chambers (310). The method may comprise the steps of controlling combustion events to occur in the or each rotor combustion chamber (210) and the or each stator combustion chamber (310) when a rotor combustion chamber (210) and a stator combustion chamber (310) are in fluid communication, and controlling combustion events to occur in sequential pairings of the or each rotor combustion chamber (210) and the or each stator combustion chamber (310).

[0043] Hence there is provided a heat engine which is highly efficient, configurable for use with environmentally friendly fuels, and has a comparable or greater power output than examples of the related art.

[0044] Brief Description of the Drawings

[0045] Examples of the present disclosure will now be described with reference to the accompanying drawings, in which:

[0046] Figure 1 shows a perspective view of an assembled rotary heat engine according to the present disclosure;

[0047] Figure 2 shows an exploded view of part of the assembly shown in figure 1 ;

[0048] Figure 3 shows an end-on view of the assembled rotary heat engine as shown in figures 1 , 2; Figure 4 shows a cross-sectional view of the heat engine along the line A-A shown in figure 3;

[0049] Figure 5 shows a perspective view of a stator of the rotary heat engine;

[0050] Figure 6 shows a perspective view of a first side of a first example of a rotor of the rotary heat engine;

[0051] Figure 7 shows a perspective view of a second side of a second example of a rotor of the rotary heat engine;

[0052] Figure 8 shows part of the housing of the rotary heat engine;

[0053] Figures 9 to 20 illustrate stages of operation of the rotary heat engine according to the present disclosure;

[0054] Figure 21 shows a perspective view of a further example of a stator of the rotary heat engine;

[0055] Figures 22, 23 illustrate stages of operation of a rotary heat engine including the stator shown in figure 21 ; and

[0056] Figure 24 shows a perspective view of an alternative example of a rotor of the rotary heat engine.

[0057] Detailed Description

[0058] The present disclosure relates to a heat engine 100. In particular, the present disclosure relates to a rotary heat engine 100. The heat engine 100 of the present disclosure may be configured as an internal combustion engine. The heat engine 100 of the present disclosure may be configured to be operable to be powered by a combustible fuel, for example a fluid (i.e. gas or liquid) fuel, including, but not limited to, hydrogen or hydrocarbon based fuels (e.g. petrol, diesel, liquefied petroleum gas (LPG), methane, bio-fuels), synthetic fuels (e.g. “e-fuel”), town gas and / or a blend of fluid fuels, for example hydrogen and a hydrocarbon based fuel.

[0059] The heat engine 100 of the present disclosure may be incorporated into a vehicle to drive and power the vehicle. For example, as shown in figure 2, the heat engine 100 may comprise an output shaft 802 (i.e. a power offtake shaft) configured to be coupled to a vehicle powertrain. Additionally, or alternatively the output shaft 802 of the heat engine 100 may be operable to power an electricity generator which in turn powers an electrical drive motor of a vehicle. The heat engine 100 of the present disclosure may also form part of an electricity generation plant, operable to drive electricity generators. The heat engine 100 of the present disclosure may be used in any application where a conventional internal combustion engine may be used, for example in land based applications (e.g. vehicles or static structures), watercraft and aircraft.

[0060] Figures 1 to 8 and 21 illustrate examples of the structure of the heat engine 100 of the present disclosure. Figures 9 to 20 and 22, 23 illustrate stages of operation of the rotary heat engine 100 examples. Some features of the engine are omitted from some of the drawings. For example, in figures 9 to 20 and 22, 23 the igniter 402, fuel injector 404, and pipe work associated with the exhaust ports 320 and the third air inlet ports 330 are omitted. However, it should be understood that although these details are not shown in the figures, it should be assumed their presence (or some appropriate functional alternative) is implicit.

[0061] Figure 1 shows a perspective view of the rotary heat engine 100. Figure 2 shows an exploded view of part of the assembly shown in Figure 1. Figure 3 shows an end-on (i.e. an edge) view of the assembled rotary heat engine 100.

[0062] As shown in figure 1 , the rotary heat engine 100 comprises a housing 700. The housing 700 comprises a first housing side wall 702 and a second housing side wall 704. An example of these is shown in isolation in figure 8. The first housing side wall 702 is spaced apart from the second housing side wall 704, with a stator 300 therebetween. The stator 300 is coupled to, and fixed relative to, the first housing side wall 702 and the second housing side wall 704.

[0063] As shown in figure 2, the heat engine 100 further comprises a rotor 200 centred on, and rotatable about, a rotational axis 202. The rotor 200 may be configured as a flywheel. As shown in figure 2, the stator 300 bounds (i.e. surrounds, encircles) the rotor 200. That is to say, the stator 300 is radially outward of the rotor 200. Put another way, the stator 300 and the rotor 200 may be concentrically arranged around the rotational axis 202, with the rotor 200 being radially inward of the stator 300.

[0064] The rotor 200 is rotatable relative to the stator 300 about the rotational axis 202. The rotor 200 may be carried on a support shaft 800. The rotor 200 may be coupled to the support shaft 800, and the support shaft 800 and the rotor 200 may be rotatable about the rotational axis 202 together. The power offtake 802 may extend from and / or be coupled to the support shaft 800. For example, the power offtake 802 may extend from and / or be coupled to either end of the support shaft 800 or be coupled indirectly to the support shaft 800 via a gearing.

[0065] The rotor 200 and the support shaft 800 may be centred on the rotational axis 202. The first housing side wall 702 may be spaced apart from the second housing side wall 704 along the rotational axis 202 by the rotor 200 and stator 300. That is to say, the rotor 200 and the stator 300 may be located between the first housing side wall 702 and the second housing side wall 704. Put another way, the first housing side wall 702 may be axially spaced apart from the second housing side wall 704 along the rotational axis 202 by the rotor 200 and the stator 300.

[0066] Each of the first housing side wall 702 and the second housing side wall 704 may be in sealing engagement with the stator 300.

[0067] The rotor 200 is rotatable relative to each of the first housing side wall 702 and the second housing side wall 704. A first clearance may be maintained between the first housing side wall 702 and a first side 215 of the rotor 200, and a second clearance may be maintained between the second housing side wall 704 and a second side 217 of the rotor 200 so that the rotor 200 is rotatable relative to each of the first housing side wall 702 and the second housing side wall 704.

[0068] The first housing side wall 702 and the second housing side wall 704 are coupled to the stator 300 in such a way, and configured, to physically constrain the stator 300 from expanding radially. For example (as shown in figure 2) a recess 710 may be provided in the first housing side wall 702 and the second housing side wall 704 within which a part of the stator 300 (for example a radially outer rim 350) is located. Alternatively, and additionally the first housing side wall 702 and the second housing side wall 704 may be coupled to the stator 300 laterally by clamping fixings bolts, studs or the like. The first housing side wall 702 and the second housing side wall 704 may be coupled to the stator 300 by any conventional means. Dowls, pins and such like may be used to achieve alignment between the stator 300 and the housing side walls 702, 704.

[0069] A side wall inlet port 708 may be provided in the first housing side wall 702 and / or the second housing side wall 704. The external side of the side wall inlet port 708 (i.e. the inlet) is configured for fluid communication with a source of air 600. The source of air 600 may be the local environment (e.g. at atmospheric pressure) or a pressurised air source. The supply of pressurised air may be a compressor. That is to say, the pressurised air may be provided by a compressor. The compressor may be coupled to or spaced apart from the housing 700 and connected by tubes / pipes etc. The compressor may be of any conventional kind (for example an axial or centrifugal compressor).

[0070] The heat engine 100 may further comprise an air cooler which reduces the temperature of the air prior to delivery to the side wall inlet ports(s) 708. The heat engine 100 may further comprise an air cooler which reduces the temperature of the air prior to delivery to the third air inlet port 330. Cooling the air may improve volumetric efficiency of the heat engine 100.

[0071] Figure 4 shows a cross-sectional view of the heat engine 100 along the line A-A shown in figure 3. Figure 5 shows a perspective view of the stator 300. As can be seen in figures 4, 5 the stator 300 defines a radially inner surface 304.

[0072] Figure 6 shows a perspective view of a first side of a first example of a rotor 200. Figure 7 shows a perspective view of part of a second side of a second example of the rotor 200. As can be seen in figures 2, 6, 7 the rotor 200 comprises a radially outer surface 204.

[0073] As shown in figure 4, when the rotor 200 and stator 300 are assembled the radially inner surface 304 of the stator 300 faces the radially outer surface 204 of the rotor 200.

[0074] As shown in figures 4, 6, 7, the rotor 200 may comprise a support structure 207 which extends from a hub 211 to a radially outer rim 213. The radially outer rim 213 defines the radially outer surface 204 of the rotor 200. The hub 211 may be coupled to the support shaft 800. The hub 211 may be coupled to the support shaft 800 such that they are fixed relative to one another and hence are rotatable with one another. In other examples the hub 211 may be supported on the support shaft 800 by a bearing arrangement such that the rotor 200 is rotatable relative to the support shaft 800.

[0075] The support structure 207 may be provided as a solid disc or as a disc with cut outs (for example to reduce weight).

[0076] In the example shown in the drawings (see for example figure 6), the support structure 207 may comprise spokes 208 which extend from the hub 211 to the radially outer rim 213. The spokes 208 may be spaced apart from one another to define spaces 209 therebetween.

[0077] The radially outer surface 204 of the rotor 200 defines (i.e. is provided with) at least one rotor combustion chamber 210 having a leading edge 212 and a trailing edge 214. The rotor combustion chamber leading edge 212 and the rotor combustion chamber trailing edge 214 are so termed because when the rotor 200 is rotating the leading edge 212 precedes the trailing edge 214.

[0078] The stator radially inner surface 304 defines (i.e. is provided with) at least one stator combustion chamber 310 having a leading edge 312 and a trailing edge 314. The stator combustion chamber leading edge 312 and the stator combustion chamber trailing edge 314 are so termed because when the rotor 200 is rotating, the leading edge 212 of the or each rotor combustion chamber 210 passes the leading edge 312 of the or each stator combustion chamber 310 before it passes the trailing edge 314 of the or each stator combustion chamber 310.

[0079] In the examples shown in the figures, and as labelled in figures 9 to 20, 22, 23 there are provided three rotor combustion chambers 210 (i.e. the first rotor combustion chamber RC1 , the second rotor combustion chamber RC2 and the third rotor combustion chamber RC3) and two stator combustion chambers 310 (the first stator combustion chamber SC1 and the second stator combustion chamber SC2). In the example shown in the figures the two stator combustion chambers 310 are provided diametrically opposite one another (i.e. 180 degrees apart around the circumference of the stator 300). In other examples, not shown, there may be provided two rotor combustion chambers 210 and three stator combustion chambers 310.

[0080] In other examples, not shown, there may be provided one rotor combustion chamber 210 and two stator combustion chambers 310. In other examples, not shown, there may be provided two rotor combustion chambers 210 and one stator combustion chamber 310.

[0081] The number of rotor combustion chambers 210 may not be equal to the number of stator combustion chambers 310. That is to say, either the number of rotor combustion chambers 210 exceeds the number of stator combustion chambers 310 or the number of stator combustion chambers 310 exceeds the number of rotor combustion chambers 210.

[0082] In an example in which the number of rotor combustion chambers 210 provided is N, the number of stator combustion chambers 310 provided may be N+1 . In an example in which the number of stator combustion chambers 310 is N, the number of rotor combustion chambers 210 may be N+1.

[0083] In some examples there may be provided an even number of rotor combustion chambers 210 and an odd number of stator combustion chambers 310. Alternatively, there may be provided an odd number of rotor combustion chambers 210 and an even number of stator combustion chambers 310.

[0084] In some examples there may be provided an even number of rotor combustion chambers 210 and an even number of stator combustion chambers 310.

[0085] In some examples there may be provided an odd number of rotor combustion chambers 210 and an odd number of stator combustion chambers 310. The rotor combustion chambers 210 may be equally (e.g. evenly) distributed around the circumference of the rotor 200. The stator combustion chambers 310 may be equally (e.g. evenly) distributed around the circumference of the stator 300.

[0086] As will be described later, these arrangements of rotor combustion chambers 210 and stator combustion chambers 310 enable sequential combustion events as the rotor 200 rotates around the rotational axis 202 relative to the stator 300.

[0087] The or each rotor combustion chamber 210 is aligned with the or each stator combustion chamber 310 on a common circumferential path centred on the rotational axis 202 such that the or each rotor combustion chamber 210 is in fluid communication with the or each stator combustion chamber 310 during a revolution of the rotor 200 about the rotational axis 202. That is to say, the or each rotor combustion chamber 210 is aligned with the or each stator combustion chamber 310 on a common circumferential path centred on the rotational axis 202 such that the or each rotor combustion chamber 210 overlaps the or each stator combustion chamber 310 for a part of a revolution of the rotor 200 about the rotational axis 202.

[0088] The or each rotor combustion chamber 210 is provided as a recess 206 (e.g. a cavity) extending along part, but not all, of the rotor radially outer surface 204.

[0089] The or each stator combustion chamber 310 is provided as a recess 306 (e.g. cavity) which extends along part, but not all, of the stator radially inner surface 304.

[0090] The or each rotor recess 206 is open on a side facing the stator 300. The or each stator recess 306 is open on a side facing the rotor 200.

[0091] The or each rotor combustion chamber 210 extend radially inwardly into the rotor 200 at the leading edge 212 to define a rotor step 216 with a leading edge depth RDIe, the or each rotor combustion chamber 210 reducing in depth towards their trailing edge 214. That is to say, the depth RDIe of the or each of the rotor combustion chamber 210 at the leading edge 212 is greater than the depth RDte of the or each rotor combustion chamber 210 at their trailing edge 214.

[0092] The or each rotor combustion chamber 210 may be defined by a rotor surface base wall 218 which faces the stator 300 and extends from the leading edge 212 to the trailing edge 214 of the rotor combustion chamber 210 to define a rotor combustion chamber convex surface 220 extending at least part of the way from the leading edge 212 to the trailing edge 214 of the rotor combustion chamber 210.

[0093] The rotor combustion chamber 210 may be defined by a rotor surface base wall 218 which faces the stator 300 and extends from the radially innermost point of the rotor step 216 to the trailing edge 214 to define a rotor combustion chamber convex surface 220 extending at least part of the way from the radially innermost point of the rotor step 216 to the trailing edge 214.

[0094] The or each stator combustion chamber 310 may extend radially outwardly into the stator 300 at the leading edge 312 to define a stator step 316 with a leading edge depth SDIe, the or each stator combustion chamber 310 reducing in depth towards the trailing edge 314. The depth SDIe of the or each of the stator combustion chamber 310 at the leading edge 312 is greater than the depth SDte of the or each stator combustion 310 at the trailing edge 314.

[0095] The or each stator combustion chamber 310 may be defined by a stator surface base wall 318 which faces the rotor 200 and extends from the stator combustion chamber leading edge 312 to the stator combustion chamber trailing edge 314 such that the stator surface base wall 318 defines a concave surface 319 extending at least part of the way from the stator combustion chamber leading edge 312 to the stator combustion chamber trailing edge 314.

[0096] The or each stator combustion chamber 310 may be defined by a stator surface base wall 318 which faces the rotor 200 and extends from the radially outermost point of the stator step 316 at the stator combustion chamber leading edge 312 to the stator combustion chamber trailing edge 314 such that the stator surface base wall 318 defines a concave surface 319 extending from the stator combustion chamber leading edge 312 to the stator combustion chamber trailing edge 314.

[0097] In the example shown in figure 4, the stator combustion chamber concave surface 319 comprises a first section 311 which extends from the stator combustion chamber leading edge 312 at the inner surface of the stator 300 to define the stator step 316, and a second section 313 which extends at an angle (for example perpendicular or an alternative angle) to the first section 311 , and extends from the first section 311 towards the trailing edge 314. By way of non-limiting example, and as shown in the figures, the stator combustion chamber concave surface 319 may define a wedge shape.

[0098] The or each rotor combustion chamber 210 may extend at least 25 deg, but no more than 70 deg, around the outer circumference of the rotor 200. The or each rotor combustion chamber 210 may extend (i.e. between the rotor combustion chamber leading edge 212 and the rotor combustion chamber trailing edge 214) at least 25 deg, but no more than 70 deg, around the outer circumference of the rotor 200.

[0099] The or each stator combustion chamber 310 may extend at least 15 deg, but no more than 35 deg, around the inner circumference of the stator 300. The or each stator combustion chamber 310 may extend (i.e. between the stator combustion chamber leading edge 312 and the stator combustion chamber trailing edge 314) at least 15 deg, but no more than 35 deg, around the inner circumference of the stator 300.

[0100] As shown in figures 2, 6, 8 a rotor combustion chamber wall 260 may extend from the rotor combustion chamber leading edge 212 to the rotor combustion chamber trailing edge 214 on both sides of the or each rotor combustion chamber 210 to thereby define the transverse extent of the or each rotor combustion chamber 210.

[0101] A first labyrinth seal 262 may be provided at the lateral edges of the rotor 200 which extends around the circumference of the rotor 200, extending over the radial land 222 (e.g. tip) of the or each rotor combustion chamber wall 260.

[0102] The outer circumference of the rotor 200 may be defined by a first layer 266 of material 264 with a low coefficient of thermal expansion. The outer circumference of the rotor 200 may be provided by a first layer 266 of material 264 with a low coefficient of thermal expansion. That is to say, and as shown in figure 24, the material which defines / provides the radially outer surface 204 of the rotor 200 may be provided as a first layer 266 of material 264 with a lower coefficient of thermal expansion than the material of the remainder of the rotor 200 which is radially inward of the first layer 266 of material 264.

[0103] Hence the radially outer rim 213 of the rotor 200 may comprise, at least in part, a material 264 with a low coefficient of thermal expansion. The radially outer rim 213 may comprise the first layer 266 of the material 264 with a first coefficient of thermal expansion and a second layer 268 of a second material (which may be the same material as the support structure 207 or different to the material of the support structure 207) which has a second coefficient of thermal expansion, the first coefficient of thermal expansion being substantially / significantly less than the second coefficient of thermal expansion. The first layer 266 of the material 264 may be provided radially outwards of the second layer 268 of the second material.

[0104] A layer of material 264 with a low coefficient of thermal expansion may be provided at the lateral (i.e. peripheral) edges of the rotor 200 which extends around the circumference of the rotor 200, extending over the radial land 222 (e.g. tip) of the or each rotor combustion chamber wall 260.

[0105] The layer 266 of material 264 may be provided as a ring. The layer 266 of material 264 may be provided as a ring at each of the lateral (i.e. peripheral) edges of the rotor 200. As illustrated in figure 24, the first layer 266 of material 264 may be provided as a ring which extends across the whole width W of the rotor 200. The material 264 with a low coefficient of thermal expansion may be nickel steel, for example an alloy comprising 1 to 10% Cobalt and / or 30 to 40% Nickel.

[0106] The second material may be a metal (for example steel).

[0107] In other examples, the rim 213, rim layers 266, 268 and / or support structure 207 may be formed of and / or comprise other materials with suitable properties, which, by way of non limiting example, may be metal, metallic alloys and / or ceramics.

[0108] As shown in figure 5, a stator combustion chamber wall 360 may extend from the stator combustion chamber leading edge 312 to the stator combustion chamber trailing edge 314 on both sides of the or each stator combustion chamber 310 to thereby define the transverse extent of the or each stator combustion chamber 310.

[0109] The or each stator combustion chamber 310 is in fluid communication with a fuel source 400 via a fuel injector 404. That is to say the part of the stator 300 which defines a stator combustion chamber 310 may be configured to mount a fuel injector 404, or define a passage in fluid communication with a fuel injector 404, such that fuel may be delivered to the stator combustion chamber 310.

[0110] In the example shown in the figures there are provided two fuel injectors 404, one for each stator combustor 310. The two fuel injectors 404 are provided diametrically opposite one another (i.e. 180 degrees apart around the circumference of the stator 300). As will be appreciated, in other examples, where three or more fuel injectors 404 are provided, the spacing of the fuel injectors 404 will be adapted accordingly (e.g. spaced apart by 360 / [number of injectors 404] degrees).

[0111] The fuel source 400 may be provided as tank, reservoir or the like. The fuel source 400 may be pressurised. For example, a pump may be provided to deliver the fuel to the fuel injector 404.

[0112] The fuel source 400 may comprise a combustible fuel, for example a fluid (i.e. gas or liquid) fuel, including, but not limited to, hydrogen and hydrocarbon based fuels (e.g. petrol, diesel, liquefied petroleum gas (LPG), methane, bio-fuels), synthetic fuel (e.g. “e- fuel”), town gas and / or a blend of fluid fuels, for example hydrogen and a hydrocarbon based fuel.

[0113] A fuel igniter 402 may be located in the or each stator combustion chamber 310. The fuel igniter 402 may be configured to generate a source of heat sufficient to ignite fuel from the fuel source 400 under the temperature and pressure conditions defined by the rotary heat engine 100. The fuel igniter 402 may be any conventional fuel ignition device, for example a spark plug. The fuel igniter 402 may be provided as a laser. In the example shown in the figures there are provided two fuel igniters 402, one for each stator combustor 310. The two fuel igniters 402 are provided diametrically opposite one another (i.e. 180 degrees apart around the circumference of the stator 300). As will be appreciated, in other examples, where three or more fuel igniters 402 are provided, the spacing of the fuel igniters 402 will be adapted accordingly (e.g. spaced apart by 360 / [number of fuel igniters 402] degrees).

[0114] As illustrated for the second rotor combustion chamber RC2 and the first stator combustion chamber SC1 in figure 11 , the stator radially inner surface 304 and the rotor radially outer surface 204 are configured such that when the or each rotor combustion chamber 210 is circumferentially offset from the or each stator combustion chamber 310, the or each rotor combustion chamber 210 and the or each stator combustion chamber 310 are fluidly isolated from one another (e.g. separated with the flow path between configured to prevent or inhibit flow of gas therebetween to provide an at least partial seal). For example, the clearance between the stator radially inner surface 304 and rotor radially outer surface 204 may be chosen such that fluid isolation (e.g. at least a partial seal) between a rotor combustion chamber 210 and a corresponding stator combustion chamber 310 at this stage in the cycle is achieved when a seal is created between them. The clearance between the stator radially inner surface 304 and rotor radially outer surface 204 may be chosen such that fluid isolation (e.g. at least a partial seal) between a rotor combustion chamber 210 and a corresponding stator combustion chamber 310 at this stage in the cycle is achieved by a tortuous path (e.g. which restricts / limits fluid flow) created between them.

[0115] There may be provided a corresponding exhaust port 320 spaced apart from the or each stator combustion chamber 310 around the circumference of the stator radially inner surface 304. The exhaust port 320 may open onto the stator radially inner surface 304.

[0116] That is to say, an exhaust port 320 may be provided spaced apart from a stator combustion chamber 310 around the stator radially inner surface 304, positioned at such a distance from the stator combustion chamber 310 that as the rotor 200 rotates around the rotational axis 202 combustion will be completed, or at least sufficiently complete, by the time the rotor combustion chamber 210 is in fluid communication with the exhaust port 320.

[0117] The or each rotor combustion chamber 210 extends around the circumference of the rotor radially outer surface 204 such that they span the distance between an adjacent (i.e. corresponding) stator combustion chamber 310 and exhaust port 320, for example as illustrated for the second rotor combustion chamber RC2 and the first stator combustion chamber SC1 in figure 10.

[0118] That is to say, the or each rotor combustion chamber 210 may extend around the circumference of the rotor radially outer surface 204 such that during a part of a period of a revolution of the rotor 200 about the rotational axis 202, the rotor combustion chamber 210 will be in fluid communication with an exhaust port 320 and the stator combustion chamber 310 which corresponds to the same stator combustion chamber 310. Hence after a combustion event when the or each rotor combustion chamber 210 and stator combustion chamber 310 are in fluid communication (and hence work is being done on the rotor 200 by the expanding gas due to combustion, which results in an increase in pressure), but fluidly isolated from the corresponding exhaust port 320, the rotor 200 turns to align the rotor combustion chamber 210 with the next exhaust port 320 along the inner circumference of the stator 300 such that the rotor combustion chamber 210 and stator combustion chamber 310 are both in fluid communication with the said exhaust port 320 so that exhaust gas may be purged from the rotor combustion chamber 210 and stator combustion chamber 310 through the exhaust port 320.

[0119] As shown in figures 2, 4, 6, the rotor 200 comprises (i.e. defines) a first air inlet port 230 for communication with the air source air 600. The first air inlet port 230 opens on the rotor radially outer surface 204. That is to say, the first air inlet port 230 is provided as an aperture in the radially outer surface 204 of the rotor 200. A first air inlet port 230 is provided for each rotor combustion chamber 210.

[0120] The first air inlet port 230 is provided proximate to, but circumferentially spaced apart from, a rotor combustion chamber trailing edge 214. That is to say, a first air inlet port 230 opens onto the radially outer surface 204 of the rotor 200, and is provided spaced apart from an adjacent rotor combustion chamber trailing edge 214 along the radially outer surface 204 of the rotor 200.

[0121] That is to say, the rotor 200 may comprise a first air inlet port 230. A first air inlet port 230 may be provided proximate to, but circumferentially spaced apart from, the or each rotor combustion chamber trailing edge 214. Hence in examples in which a plurality of rotor combustion chambers 210 are provided (and as shown in the figures), a first air inlet port 230 may be provided proximate to, but circumferentially spaced apart from, each rotor combustion chamber trailing edge 214. The first air inlet port 230 may be configured for communication with a source of air 600. The first air inlet port 230 may open on the rotor radially outer surface 204. Hence the first air inlet port 230 is only in fluid communication with the rotor combustion chamber 210 if both the rotor combustion chamber 210 and the first air inlet port 230 are in fluid communication with the stator combustion chamber 310 (for example as shown in figure 17 with reference to the first rotor combustion chamber RC1).

[0122] As illustrated in figure 17 with reference to the first rotor combustion chamber RC1 and the first stator combustion chamber SC1, the or each first air inlet port 230 is located such that during a revolution of the rotor 200 about the rotational axis 202, for a part of a period when the end of the or each rotor combustion chamber 210 overlaps the corresponding stator combustion chamber 310 and the exhaust port 320, the first air inlet port 230 is in flow communication (e.g. fluid communication) with the rotor combustion chamber 210 and the respective stator combustion chamber 310, and hence the first air inlet port 230 is also in flow communication with the respective exhaust port 320 to thereby purge the respective stator combustion chamber 310.

[0123] As illustrated in figure 18 with reference to the first rotor combustion chamber RC1 and the first stator combustion chamber SC1 the first air inlet port 230 is located such that during a revolution of the rotor 200 about the rotational axis 202, the first air inlet port 230 is in flow communication with the or each stator combustion chamber 310 for a part of a period when the or each rotor combustion chamber 210 is fluidly isolated from the respective stator combustion chamber 310.

[0124] As shown in figures 2, 4, 6, the rotor 200 comprises (i.e. defines) a second air inlet port 232 for communication with the source of air 600, the second air inlet port 232 being provided proximate to, but circumferentially spaced apart from, the first air inlet port 230, such that the second air inlet port 232 is circumferentially spaced apart from the respective rotor combustion chamber trailing edge 214 by the respective first air inlet port 230.

[0125] Hence the rotor 200 comprises a second air inlet port 232 for communication with the air source air 600. The second air inlet port 232 opens on the rotor radially outer surface 204. That is to say, the second air inlet port 232 is provided as an aperture in the radially outer surface 204 of the rotor 200. A second air inlet port 232 is provided for each rotor combustion chamber 210.

[0126] That is to say, the rotor 200 may comprise a second air inlet port 232. The second air inlet port 232 may be configured for communication with a source of air 600. The second air inlet port 232 may open on the rotor radially outer surface 204. The second air inlet port 232 may be circumferentially spaced apart from the first air inlet port 230 such that the second air inlet port 232 is circumferentially spaced apart from the respective rotor combustion chamber trailing edge 214 by the respective first air inlet port 230.

[0127] Hence in examples in which a plurality of rotor combustion chambers 210 are provided (and as shown in the figures), a second air inlet port 232 may be circumferentially spaced apart from each first air inlet port 230 such that each second air inlet port 232 is circumferentially spaced apart from its respective rotor combustion chamber trailing edge 214 by the respective first air inlet port 230.

[0128] As illustrated in figure 18 with reference to the first rotor combustion chamber RC1 and the first stator combustion chamber SC1 the second air inlet port 232 is located such that during a revolution of the rotor 200 about the rotational axis 202, the second air inlet port 232 is in flow communication with the or each stator combustion chamber 310 for a part of a period when the proximate rotor combustion chamber 210 is fluidly isolated from the respective stator combustion chamber 310.

[0129] As illustrated in figure 19 with reference to the first rotor combustion chamber RC1 and the first stator combustion chamber SC1 the first air inlet port 230 and the second air inlet port 232 are located such that during a revolution of the rotor 200 about the rotational axis 202, in a second sub-period of the period when the or each rotor combustion chamber 210 is fluidly isolated from the or each stator combustion chamber 310, the first air inlet port 230 is fluidly isolated from the respective stator combustion chamber 310 and the second air inlet port 232 is in flow communication with the respective stator combustion chamber 310.

[0130] As illustrated in figure 18 with reference to the first rotor combustion chamber RC1 and the first stator combustion chamber SC1 , the first air inlet port 230 and the second air inlet port 232 are located such that during a revolution of the rotor 200 about the rotational axis 202, in a first sub-period of the period when the or each rotor combustion chamber 210 is fluidly isolated from the or each stator combustion chamber 310, the first air inlet port 230 and the second air inlet port 232 are in flow communication (e.g. fluid communication) with the respective stator combustion17 chamber 310.

[0131] As shown in figures 2, 6, 7, the first air inlet port 230 and / or the second air inlet port 232 may be provided as an outlet slot 270 which extend transversely across the rotor outer surface 204.

[0132] As illustrated in figure 7, a feed slot 272 may be provided on at least one side 215, 217 of the rotor 200 for fluid communication with the side wall inlet port 708 shown in figure 8. That is to say, a feed slot 272 may be provided on the first side 215 of the rotor 200 and / or the second side 217 of the rotor 200. For example, a feed slot 272 may be provided on the first side 215 of the rim 213 of the rotor 200 and / or the second side 217 of the rim 213 of the rotor 200. The feed slot 272 may be provided as a recess which extends part, but not all, of the way around the or each side of the rotor 200. In the example shown, the outlet slots 270 extend radially into the rotor 200 and the outlet slots 270 are in fluid communication with the feed slot 272 via a passage (or passages) 274 in the rotor 200.

[0133] Hence the internal side of the side wall inlet port 708 is in fluid communication with a first air inlet port 230 and a second air inlet port 232 when they pass the respective side wall inlet port 708 as the rotor 200 rotates about the rotational axis 202.

[0134] As shown in figures 2, 8, there are provided two side wall inlet ports 708 diametrically opposite one another across the rotational axis 202. A side wall inlet port 708 is provided for every stator combustion chamber 310. Hence, however many stator combustion chambers 310 are provided, the same number of side wall inlet ports 708 are provided.

[0135] Each side wall inlet port 708 is provided at the same radius from the rotational axis 202 as the feed slot 272 such that, as the rotor 200 rotates, each feed slot 272 passes a side wall inlet port 708 and is temporarily in fluid communication with the side wall inlet port 708.

[0136] As illustrated in figure 20, with reference to the first rotor combustion chamber RC1 , the first air inlet port 230 and the second air inlet port 232 are located such that after the second sub-period the second air inlet port 232 is fluidly isolated from the rotor combustion chamber 210.

[0137] As illustrated in figure 7, a second labyrinth seal 263 may be provided on each side of the rotor 200. Each second labyrinth seal 263 may extend around a diameter the rotor 200. Each second labyrinth seal 263 may be provided between the side of the rotor 200 and a respective housing side wall 702, 704. The second labyrinth seal 263 may extend at a smaller diameter than the first labyrinth seal 262. The feed slot 272 may be provided between the first labyrinth seal 262 and the second labyrinth seal 263.

[0138] The first labyrinth seal 262 and the second labyrinth seal 263 are configured such that air delivered to the wall inlet ports 708 is sealed between the first labyrinth seal 262 and the second labyrinth seal 263. That is to say, the first labyrinth seal 262 and the second labyrinth seal 263 are configured such they provided a tortuous leakage path, thereby retaining air delivered to the wall inlet ports 708 between the first labyrinth seal 262 and the second labyrinth seal 263. As shown in figures 2, 4, 5, the stator 300 comprises a third air inlet port 330 for communication with the source of air 600. The third air inlet port 330 is provided circumferentially spaced apart from the corresponding exhaust port 320. The third air inlet port 330 opens on the radially inner surface 304 of the stator 300.

[0139] That is to say, the third air inlet port 330 is provided in the stator 300 for communication with the source of air 600, and for delivery of air to the or each rotor combustion chamber 210 as the or each rotor combustion chamber 210 at least partially overlaps the third air inlet port 330 (for example, with reference to the first rotor combustion chamber RC2, as shown in figures 12 to 16). The third air inlet port 330 is located circumferentially spaced apart from the corresponding exhaust port 320 such that, as the rotor 200 rotates about the rotational axis 202, a rotor combustion chamber 210 is first in fluid communication with an exhaust port 320 and then in fluid communication with a third air inlet port 330.

[0140] In examples where multiple stator combustion chambers 310 are provided, a third air inlet port 330 is provided spaced apart, and around the stator radially inner surface 304, from the stator combustion chamber 310. Hence the or each third air inlet port 330 is positioned such that as the rotor 200 rotates about the rotational axis 202, a rotor combustion chamber 210 is first in fluid communication with a stator combustion chamber 310, then in fluid communication with an exhaust port 320, and then in fluid communication with a third air inlet port 330.

[0141] In some examples, fuel injection may also be provided through the third air inlet port 330. For example, this may be desirable with fuels which require a longer mixing, evaporation and / or atomisation time prior to ignition. Hence fuel injection via the third inlet port 330 may be in addition to fuel injection via the fuel injector 404. For such fuels, the same, different or no fuel may be injected via the fuel injector 404.

[0142] The or each first air inlet port 230 and the or each second air inlet port 232 are in fluid communication with the air source 600 via the or each side wall inlet port 708. The third air inlet port 330 may be in fluid communication with the same air source 600 as the or each first air inlet port 230 and the or each second air inlet port 232. That is to say, the third air inlet port 330 may be in fluid communication with the same air source 600 as the side wall inlet port 708, for example via pipework (not shown). The third air inlet port 330 may be in fluid communication with a different air source 600 to the or each first air inlet port 230 and the or each second air inlet port 232.

[0143] The air delivered to the or each first air inlet port 230, the or each second air inlet port 232 (i.e. delivered to the side wall inlet port 708) and the or each third inlet port 330 may be provided / delivered at constant pressure through at least part of the running range of the engine. That is to say, the air delivered to the or each first air inlet port 230, the or each second air inlet port 232 (i.e. delivered to the side wall inlet port 708) and the or each third inlet port 330 may be provided at the same / common pressure through at least part of the running range of the engine.

[0144] The system is configured such that the or each third air inlet port 330 is fluidly isolated from the or each rotor combustion chamber 210 until the or each rotor combustion chamber 210 overlaps the or each third air inlet port 330. Hence no air will enter the rotor combustion chamber 210 via the third air inlet port 330 until the rotor combustion chamber 210 at least partially overlaps the third air inlet port 330.

[0145] Hence there are provided an exhaust port 320 and a third air inlet port 330 for each stator combustion chamber 310. That is to say, there is provided a sequence of third air inlet port 330, stator combustion chamber 310 and exhaust port 320 in sequence around the radially inner surface 304 of the stator 300 which correspond with one another. In the example shown in the figures there are provided two exhaust ports 320 and two third air inlet ports 330. In the example shown in the figures the two exhaust ports 320 are provided diametrically opposite one another (i.e. 180 degrees apart around the circumference of the stator 300). In the example shown in the figures the two third air inlet ports 330 are provided diametrically opposite one another (i.e. 180 degrees apart around the circumference of the stator 300).

[0146] Each set of fuel igniter 402, fuel injector 404 and stator combustion chamber 310 are provided in series around the radially inner circumference 304 of the stator 300 with the exhaust port 320 and third air inlet port 330. Hence, the or each unit which comprises the fuel igniter 402, fuel injector 404 and stator combustion chamber 310 is provided between a corresponding exhaust port 320 and a third air inlet port 330 around the inner circumference 304 of the stator 300. Hence as the rotor 200 rotates, the rotor combustion chamber 210 will first be in fluid communication with the third air inlet port 330, then the unit comprising a fuel igniter 402, fuel injector 404 and stator combustion chamber 310, and then the exhaust port 320.

[0147] The operation of the heat engine 100 of the present disclosure will now be described with reference to figures 9 to 20. Figures 9 to 20 represent half a cycle. That is to say, figures 9 to 20 represent half a rotation of the rotor 200 about the rotational axis 202 in which there are three combustion events in series (rather than simultaneously), one in each of the rotor combustion chambers RC1, RC2, RC3, as labelled in figures 9 to 20. As will be appreciated, since there are examples in which there are a different number of rotor combustion chambers 210 and stator combustion chambers 310 to that shown in the figures, the precise operation of different examples will vary. The following description focusses on one cycle of one of the rotor combustion chambers 210, the first rotor combustion chamber RC1, and what is occurring in each of the other rotor combustion chambers RC2, RC3 at the same time. In this context “cycle” means air intake, fuel intake, combustion and exhaust.

[0148] Figure 9 shows a stage where the first rotor combustion chamber RC1 is in fluid communication with an exhaust port 320 and fluidly isolated from the first stator combustion chamber SC1 and the second stator combustion chamber SC2. At the same time combustion is occurring in the second rotor combustion chamber RC2 and the first stator combustion chamber SC1 (which are in fluid communication with one another). Also, at the same time the third rotor combustion chamber RC3 and the second stator combustion chamber SC2 (being in fluid communication with one another) are being charged with air from a third air inlet port 330.

[0149] Figure 10 shows a stage where the first rotor combustion chamber RC1 is in fluid communication with a third air inlet port 330 and an exhaust port 320 and hence is being purged of any residual combustion gases. At the same time the second rotor combustion chamber RC2 (which is still in fluid communication with the first stator combustion chamber SC1) has just come into fluid communication with an exhaust port 320 to start exhausting combustion gases. Also, at the same time the third rotor combustion chamber RC3 is being charged with air from a third air inlet port 330 and is in fluid communication with the second stator combustion chamber SC2, which is consequentially also being charged with air.

[0150] Figure 11 shows a stage where the first rotor combustion chamber RC1 is still in fluid communication with the third air inlet port 330, but is fluidly isolated from the exhaust port 320 and hence is being charged with air. At the same time the second rotor combustion chamber RC2 is fluidly isolated from the first stator combustion chamber SC1 and the second rotor combustion chamber RC2 is in fluid communication with an exhaust port 320 and so is exhausting combustion gases. The corresponding first air inlet port 230 and second air inlet port 232 are in fluid communication with the first stator combustion chamber SC1 to thereby charge the first stator combustion chamber SC1. Also, at the same time in the third rotor combustion chamber RC3 and the second stator combustion chamber SC2, which are fully aligned, having been charged with fuel from the associated fuel injector 404, the associated fuel igniter 402 is triggered to start combustion.

[0151] Figure 12 shows a stage where the first rotor combustion chamber RC1 is still in fluid communication with a third air inlet port 330 and is in fluid communication with the first stator combustion chamber SC1 , and hence both the first rotor combustion chamber RC1 and the first stator combustion chamber SC1 are being charged by air. At the same time the second rotor combustion chamber RC2 is in fluid communication with a third air inlet port 330 and an exhaust port 320 and hence is being purged of any residual combustion gases. Also, at the same time in the third rotor combustion chamber RC3 and the second stator combustion chamber SC2 combustion is complete and the third rotor combustion chamber RC3 has just come into fluid communication with an exhaust port 320 to start exhausting combustion gases.

[0152] Figure 13 shows a stage where the first rotor combustion chamber RC1 is now fluidly isolated from the third air inlet port 330 and is in fluid communication with the first stator combustion chamber SC1. Additionally, fuel is being injected by the fuel injector 404 into the volume created by the first rotor combustion chamber RC1 and the first stator combustion chamber SC1. At the same time the second rotor combustion chamber RC2 is still in fluid communication with the third air inlet port 330, but is fluidly isolated from the exhaust port 320 and hence is being charged by air. Also, at the same time the third rotor combustion chamber RC3 (which is still in fluid communication with the second stator combustion chamber SC2) is in fluid communication with the exhaust port 320 and is exhausting combustion gases. The first air inlet port 230 is in fluid communication with the volume created by the third rotor combustion chamber RC3 and the second stator combustion chamber SC2, which drives the exhaust gas purging process.

[0153] Figure 14 shows a stage where the first rotor combustion chamber RC1 and the first stator combustion chamber SC1 are fully aligned and charged with fuel from the associated fuel injector 404. The associated fuel igniter 402 is triggered to start combustion. At the same time the second rotor combustion chamber RC2 is still in fluid communication with the third air inlet port 330, but is fluidly isolated from the exhaust port 320 and hence is being charged with air. Also, at the same time the third rotor combustion chamber RC3 is fluidly isolated from the second stator combustion chamber SC2 and is in fluid communication with the exhaust port 320 so is continuing to exhaust combustion gases. The corresponding first air inlet port 230 and second air inlet port 232 are in fluid communication with the second stator combustion chamber SC2 to thereby charge the second stator combustion chamber SC2.

[0154] Figure 15 shows a stage where combustion is occurring in the first rotor combustion chamber RC1 and the first stator combustion chamber SC1 (which are in fluid communication with one another). At the same time the second rotor combustion chamber RC2 is still in fluid communication with the third air inlet port 330 and is in fluid communication with the second stator combustion chamber SC2, and hence both the second rotor combustion chamber RC2 and the second stator combustion chamber SC2 are being charged by air. Also, at the same time the third rotor combustion chamber RC3 is in fluid communication with the exhaust port 320 and fluidly isolated from the second stator combustion chamber SC2, so is continuing to exhaust combustion gases.

[0155] Figure 16 shows a stage where the first rotor combustion chamber RC1 (which is still in fluid communication with the first stator combustion chamber SC1) has just come into fluid communication with an exhaust port 320 to start exhausting combustion gases. Also, at the same time the second rotor combustion chamber RC2 is still in fluid communication with the third air inlet port 330 and is in fluid communication with the second stator combustion chamber SC2, and hence both the second rotor combustion chamber RC2 and the second stator combustion chamber SC2 are being charged by air. At the same time the third rotor combustion chamber RC3 is in fluid communication with a third air inlet port 330 and the exhaust port 320 and hence is being purged of any residual combustion gases.

[0156] Figure 17 shows a stage where the first rotor combustion chamber RC1 (which is still in fluid communication with the first stator combustion chamber SC1) is still in fluid communication with an exhaust port 320 and exhausting combustion gases. The first air inlet port 230 is in fluid communication with the volume created by the first rotor combustion chamber RC1 and the first stator combustion chamber SC1 , which drives the exhaust gas purging process. At the same time the second rotor combustion chamber RC2 is now fluidly isolated from the third air inlet port 330 and is in fluid communication with the second stator combustion chamber SC2. At the same time the third rotor combustion chamber RC3 is still in fluid communication with the third air inlet port 330, but is fluidly isolated from the exhaust port 320 and hence is being charged by air.

[0157] Figure 18 shows a stage where the first rotor combustion chamber RC1 is fluidly isolated from the first stator combustion chamber SC1 and is in fluid communication with the exhaust port 320 so is continuing to exhaust combustion gases. The corresponding first air inlet port 230 and second air inlet port 232 are in fluid communication with the first stator combustion chamber SC1 to thereby charge the first stator combustion chamber SC1. At the same time the second rotor combustion chamber RC2 (being fluidly isolated from the third air inlet port 330) is in fluid communication with the second stator combustion chamber SC2. Additionally, fuel is being injected by the fuel injector 404 into the volume created by the second rotor combustion chamber RC2 and the second stator combustion chamber SC2. At the same time the third rotor combustion chamber RC3 is still in fluid communication with the third air inlet port 330, but is fluidly isolated from the exhaust port 320 and hence is being charged by air.

[0158] Figure 19 shows a stage where the first rotor combustion chamber RC1 is fluidly isolated from the first stator combustion chamber SC1 and is in fluid communication with an exhaust port 320 so is continuing to exhaust combustion gases. The corresponding first air inlet port 230 is closed and fluidly isolated from the first rotor combustion chamber RC1 and the first stator combustion chamber SC1. The second air inlet port 232 is in fluid communication with the first stator combustion chamber SC1 to thereby charge the first stator combustion chamber SC1. Also, at the same time in the second rotor combustion chamber RC2 and the second stator combustion chamber SC2 the associated fuel igniter 402 is triggered to start combustion. At the same time the third rotor combustion chamber RC3 is still in fluid communication with the third air inlet port 330, but is fluidly isolated from the exhaust port 320 and hence is being charged by air.

[0159] Figure 20 shows a stage where the first rotor combustion chamber RC1 is in fluid communication with the exhaust port 320 and fluidly isolated from the first stator combustion chamber SC1 and continues to purge exhaust gas. At the same time combustion is occurring in the second rotor combustion chamber RC2 and the second stator combustion chamber SC2 (which are in fluid communication with one another). At the same time the third rotor combustion chamber RC3 is still in fluid communication with the third air inlet port 330, but is fluidly isolated from the exhaust port 320 and hence is being charged by air.

[0160] After this stage the process continues and repeats as the rotor combustion chambers 210 cycle around past the stator combustors 310 in turn.

[0161] Hence, in the example shown, in a full rotation of the rotor 200 about the rotational axis 202 there would be six combustion events in series (rather than simultaneously), two in each of the rotor combustion chambers RC1, RC1, RC3. In the example shown, in a full rotation of the rotor 200 about the rotational axis 202 there would be a maximum of six combustion events in series. That is to say, the combustion events may occur in the following order:

[0162] Combustion event 1 in the first rotor combustion chamber RC1 and the first stator combustion chamber SC1 ;

[0163] Combustion event 2 in the second rotor combustion chamber RC2 and the second stator combustion chamber SC2;

[0164] Combustion event 3 in the third rotor combustion chamber RC3 and the first stator combustion chamber SC1 ;

[0165] Combustion event 4 in the first rotor combustion chamber RC1 and the second stator combustion chamber SC2;

[0166] Combustion event 5 in the second rotor combustion chamber RC2 and the first stator combustion chamber SC1 ; and

[0167] Combustion event 6 in the third rotor combustion chamber RC3 and the second stator combustion chamber SC2.

[0168] That is to say, an example of the rotary engine 100 may be operated by controlling combustion events to occur in the or each rotor combustion chamber 210 and the or each stator combustion chamber 310 when a rotor combustion chamber 210 and a stator combustion chamber 310 are in fluid communication, and controlling combustion events to occur in sequential pairings of the or each rotor combustion chamber 210 and the or each stator combustion chamber 310.

[0169] Put another way, an example of the rotary engine 100 may be operated by controlling combustion events to occur when a rotor combustion chamber 210 and a stator combustion chamber 310 are in fluid communication, and since there are a different number of rotor combustion chambers 210 and stator combustion chambers 310, combustion occurs with each pairing of a rotor combustion chamber 210 and a stator combustion chamber 310, in turn, as the rotor 200 rotates.

[0170] Figure 21 illustrates an alternative example stator 300 which may form part of a heat engine 100 of the present disclosure. In addition to features of the stator 300 previously described, the stator 300 in figure 21 comprises a first fuel injector 4041 , a second fuel injector 4042 and a first fuel igniter 4021. As shown in figures 21 to 23 the stator 300 may further comprise a second fuel igniter 4022. Hence each stator combustion chamber 310 may be provided with a first fuel injector 4041 , a second fuel injector 4042 and a first fuel igniter 4021 and, in some examples, may further comprise a second fuel igniter 4022.

[0171] The part of the stator 300 which defines a stator combustion chamber 310 may be configured to mount the first fuel injector 4041 and the second fuel injector 4042 such that fuel may be delivered to the stator combustion chamber 310 from the first fuel injector 4041 and / or the second fuel injector 4042.

[0172] As illustrated in figures 21 to 23, the first fuel injector 4041 may be mounted such that it injects fuel from / through the stator combustion chamber base wall 318.

[0173] The part of the stator 300 which defines a stator combustion chamber 310 may define a first fuel passage, and may be configured to mount the first fuel injector 4041 such that fuel may be delivered to the stator combustion chamber 310 from the first fuel injector 4041 via the first fuel passage. That is to say the first fuel injector 4041 may be in fluid communication with the first fuel passage. The first fuel passage may be located such that it opens onto the stator combustion chamber base wall 318.

[0174] As illustrated in figures 21 to 23, the second fuel injector 4042 may be mounted such that it injects fuel from / through the stator combustion chamber leading edge 312 (e.g. from the stator step 316).

[0175] The part of the stator 300 which defines a stator combustion chamber 310 may define a second fuel passage, and may be configured to mount the second fuel injector 4042 such that fuel may be delivered to the stator combustion chamber 310 from the second fuel injector 4042 via the second fuel passage. That is to say the second fuel injector 4042 may be in fluid communication with the second fuel passage. The second fuel passage may be located such that it opens onto the stator combustion chamber leading edge 312 (e.g. from the stator step 316).

[0176] The first fuel igniter 4021 may be mounted in a side wall of the stator 300 such that it extends through the stator combustion chamber wall 360.

[0177] In examples in which a second fuel igniter 4022 is provided, the first fuel igniter 4021 and the second fuel igniter 4022 may be mounted in opposite side walls of the stator 300 such that they extend through opposing stator combustion chamber walls 360. That is to say, the first fuel igniter 4021 and the second fuel igniter 4022 may be mounted opposite one another, spaced apart by the stator combustion chamber 310.

[0178] The operation of an example of a heat engine 100 of the present disclosure including the stator 300 shown in figure 21 is described with reference to figures 22, 23.

[0179] Figure 22 occurs in the cycle at the same time as the event illustrated in figure 13. Hence figure 22 shows a stage where the first rotor combustion chamber RC1 is fluidly isolated from the third air inlet port 330 and is in fluid communication with the first stator combustion chamber SC1. Additionally, fuel (indicated by the broken line arrow) is being injected by the first fuel injector 4041 into the volume created by the first rotor combustion chamber RC1 and the first stator combustion chamber SC1.

[0180] Figure 23 occurs in the cycle at the same time as the event illustrated in figure 14. Hence figure 23 shows a stage where the first rotor combustion chamber RC1 and the first stator combustion chamber SC1 are fully aligned and charged with fuel from the associated first fuel injector 4041. The associated first fuel igniter 4021 is triggered to start combustion. In examples in which a second fuel igniter 4022 is provided, the second fuel igniter 4022 may be triggered at the same time or at a later time to the first fuel igniter 4021. Fuel (indicated by the broken line arrow) is then injected by the second fuel injector 4042 into the volume created by the first rotor combustion chamber RC1 and the first stator combustion chamber SC1 . The fuel injected by the second fuel injector 4042 is ignited by the fuel already burning in the volume created by the first rotor combustion chamber RC1 and the first stator combustion chamber SC1.

[0181] The same process of double fuel injection and (in examples in which a second fuel igniter 4022 is provided) double fuel ignition occurs during charging and ignition events with the second stator combustion chamber SC2. The remainder of the cycle is the same as illustrated in, and described in relation to, figures 9 to 20.

[0182] Hence there is provided a heat engine which is highly efficient, configurable for use with environmentally friendly fuels, and has a comparable, or greater, power output than examples of the related art.

[0183] These advantages are achieved by the nested rotary arrangement of the equipment of the present disclosure (i.e. the rotor being within the stator) and the unequal number of combustors in the rotor and stator which enables sequential firing as the rotor rotates. This enables a higher torque than a conventional internal combustion engine.

[0184] In the example shown in the figures, such an arrangement achieves six ignition firings per revolution. Hence at full power the engine of the present disclosure delivers constant smooth power output.

[0185] The arrangement of the present disclosure may purge the exhaust in both the stator and rotor combustion chambers with compressed air thereby ensuring that each cycle within a combustion chamber achieves high volumetric efficiency without the risk of preignition.

[0186] Additionally, the configuration of the apparatus which provides sealing / fluid isolation (e.g. at least partial sealing), for example using tight tolerances, control of expansion of the rotor and stator expansion, and / or the use of labyrinth technology between the rotor and the stator and between the rotor and the housing side walls is effective in avoiding losses through leakage.

[0187] Lubrication between the rotor and stator may not be required, and neither may a water cooling system, which (in such examples) would avoid the need for pumps and passageways in the apparatus to deliver the lubrication and cooling fluid.

[0188] The heat engine of the present disclosure is adaptable to operate on a wide range of fluid fuels, for example (but not limited to) petrol, diesel, Liquid Petroleum Gas, methane and hydrogen.

[0189] Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

[0190] All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and / or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and / or steps are mutually exclusive.

[0191] Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

[0192] The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

CLAIMS1 . A rotary heat engine (100) comprising: a rotor (200) centred on, and rotatable about, a rotational axis (202); and a stator (300) which bounds the rotor (200); wherein the rotor (200) is rotatable relative to the stator (300); the stator (300) defines a radially inner surface (304) which faces a radially outer surface (204) defined by the rotor (200); the rotor radially outer surface (204) defines at least one rotor combustion chamber (210) having a leading edge (212) and a trailing edge (214); the stator radially inner surface (304) defines at least one stator combustion chamber (310) having a leading edge (312) and a trailing edge (314); and the number of rotor combustion chambers (210) is not equal to the number of stator combustion chambers (310); and the rotor (200) comprises a first air inlet port (230), wherein: the first air inlet port (230) is configured for communication with a source of air (600); the first air inlet port (230) is provided proximate to, but circumferentially spaced apart from, the or each rotor combustion chamber trailing edge (214); and the first air inlet port (230) opens on the rotor radially outer surface (204).

2. A rotary heat engine (100) as claimed in claim 1 wherein the or each rotor combustion chamber (210) is aligned with the or each stator combustion chamber (310) on a common circumferential path centred on the rotational axis (202) such that the or each rotor combustion chamber (210) is in fluid communication with the or each stator combustion chamber (310) during a revolution of the rotor (200) about the rotational axis (202).

3. A rotary heat engine (100) as claimed in claim 1 or claim 2 wherein there is provided: an even number of rotor combustion chambers (210) and an odd number of stator combustion chambers (310); an odd number of rotor combustion chambers (210) and an even number of stator combustion chambers (310); an even number of rotor combustion chambers (210) and an even number of stator combustion chambers (310); oran odd number of rotor combustion chambers (210) and an odd number of stator combustion chambers (310).

4. A rotary heat engine (100) as claimed in any one of claims 1 to 3 wherein the number of rotor combustion chambers (210) provided is N, and the number of stator combustion chambers (310) provided is N+1 ; or the number of stator combustion chambers (310) is N, and the number of rotor combustion chambers (210) is N+1.

5. A rotary heat engine (100) as claimed in any one of claims 1 to 4 wherein: the or each rotor combustion chamber (210) is provided as a recess (206) extending along part, but not all, of the rotor radially outer surface (204); and the or each stator combustion chamber (310) is provided as a recess (306) which extends along part, but not all, of the stator radially inner surface (304).

6. A rotary heat engine (100) as claimed in any one of claims 1 to 5 wherein the or each rotor combustion chamber (210) extends radially inwardly into the rotor (200) at the leading edge (212) to define a rotor step (216) with a leading edge depth (RDIe), the or each rotor combustion chamber (210) reducing in depth towards their trailing edge (214).

7. A rotary heat engine (100) as claimed in claim 6 wherein the or each rotor combustion chamber (210) is defined by a rotor surface base wall (218) which faces the stator (300) and extends from the leading edge (212) to the trailing edge (214) of the rotor combustion chamber (210) to define a rotor combustion chamber convex surface (220) extending at least part of the way from the leading edge (212) to the trailing edge (214) of the rotor combustion chamber (210).

8. A rotary heat engine (100) as claimed in any one of claims 1 to 7 wherein the or each stator combustion chamber (310) extends radially outwardly into the stator (300) at the leading edge (312) to define a stator step (316) with a leading edge depth (SDIe), the or each stator combustion chamber (310) reducing in depth towards the trailing edge (314).

9. A rotary heat engine (100) as claimed in claim 8 wherein the or each stator combustion chamber (310) is defined by a stator surface base wall (318) which faces the rotor (200) and extends from the stator combustion chamber leading edge (312) to the stator combustion chamber trailing edge (314) such that the stator surface base wall (318) defines a concave surface (319) extending at least part of the way from the stator combustion chamber leading edge (312) to the stator combustion chamber trailing edge (314).

10. A rotary heat engine (100) as claimed in claim 9 wherein the stator combustion chamber concave surface (319) comprises: a first section (311) which extends from the stator combustion chamber leading edge (312) at the inner surface of the stator (300) to define a stator step (316), and a second section (313) which extends at an angle to the first section (311), and extends from the first section (311) towards the trailing edge (314).11 . A rotary heat engine (100) as claimed in any one of claims 1 to 10 wherein the or each rotor combustion chamber (210) extends at least 25 deg, but no more than 70 deg, around the outer circumference of the rotor (200).

12. A rotary heat engine (100) as claimed in any one of claims 1 to 11 wherein the or each stator combustion chamber (310) extends at least 15 deg, but no more than 35 deg, around the inner circumference of the stator (300).

13. A rotary heat engine (100) as claimed in any one of claims 1 to 12 wherein: a rotor combustion chamber wall (260) extends from the rotor combustion chamber leading edge (212) to the rotor combustion chamber trailing edge (214) on both sides of the or each rotor combustion chamber (210) to thereby define the transverse extent of the or each rotor combustion chamber (210); anda stator combustion chamber wall (360) extends from the stator combustion chamber leading edge (312) to the stator combustion chamber trailing edge (314) on both sides of the or each stator combustion chamber (310) to thereby define the transverse extent of the or each stator combustion chamber (310).

14. A rotary heat engine (100) as claimed in claim 13 wherein a first labyrinth seal (262) is provided at the lateral edges of the rotor (200) which extends around the circumference of the rotor (200), extending over a radial land (222) of the or each rotor combustion chamber wall (260).

15. A rotary heat engine (100) as claimed in claim 13 or claim 14 wherein a layer (266) of material (264) with a low coefficient of thermal expansion extends around the circumference of the rotor (200).

16. A rotary heat engine (100) as claimed in any one of claims 1 to 15 wherein the or each stator combustion chamber (310) is in fluid communication with a fuel source (400).

17. A rotary heat engine (100) as claimed in any one of claims 1 to 16 wherein a fuel igniter (402) is located in the or each stator combustion chamber (310).

18. A rotary heat engine (100) as claimed in any one of claims 1 to 17 wherein, spaced apart from the or each stator combustion chamber (310) around the circumference of the stator radially inner surface (304), there is provided a corresponding exhaust port (320) which opens onto the stator radially inner surface (304).

19. A rotary heat engine (100) as claimed in claim 18 wherein the or each rotor combustion chamber (210) extends around the circumference of the rotor radially outer surface (204) such that they span the distance between the corresponding stator combustion chamber (310) and exhaust port (320) such that during a part of a period of a revolution of the rotor (200) about the rotational axis (202) as the or each rotor combustion chamber (210) comes into fluid communication with the corresponding exhaust port (320) the corresponding stator combustion chamber (310) is in fluid communication with the rotor combustion chamber (210).

20. A rotary heat engine (100) as claimed in any one of claims 1 to 19 wherein the or each first air inlet port (230) is located such that during a revolution of the rotor (200) about the rotational axis (202), for a part of a period when the end of the or each rotor combustion chamber (210) overlaps the corresponding stator combustion chamber (310) and exhaust port (320), the first air inlet port (230) is in flow communication with the exhaust port (320) and the respective stator combustion chamber (310).

21. A rotary heat engine (100) as claimed in any one of claims 1 to 20 wherein the rotor (200) comprises a second air inlet port (232) for communication with the source of air (600), the second air inlet port (232) being provided proximate to, but circumferentially spaced apart from, the first air inlet port (230), such that the second air inlet port (232) is circumferentially spaced apart from the respective rotor combustion chamber trailing edge (214) by the respective first air inlet port (230).

22. A rotary heat engine (100) as claimed in claim 21 wherein the second air inlet port (232) is located such that during a revolution of the rotor (200) about the rotational axis (202), the second air inlet port (232) is in flow communication with the or each stator combustion chamber (310) for a part of a period when the proximate rotor combustion chamber (210) is fluidly isolated from the respective stator combustion chamber (310).

23. A rotary heat engine (100) as claimed in claims 21 , 22 wherein the first air inlet port (230) and the second air inlet port (232) are located such that during a revolution of the rotor (200) about the rotational axis (202): in a first sub-period of the period when the or each rotor combustion chamber (210) is fluidly isolated from the or each stator combustion chamber (310), the first air inlet port (230) and the second air inlet port (232) are in flow communication with the respective stator combustion chamber (310); and in a second sub-period of the period when the or each rotor combustion chamber (210) is fluidly isolated from the or each stator combustion chamber (310), the first air inlet port (230) is fluidly isolated from the respectivestator combustion chamber (310) and the second air inlet port (232) is in flow communication with the respective stator combustion chamber (310).

24. A rotary heat engine (100) as claimed in any of claims 1 to 23 wherein the stator (300) comprises a third air inlet port (330) for communication with the source of air (600), the third air inlet port (330) being provided circumferentially spaced apart from the corresponding exhaust port (320).

25. A rotary heat engine (100) as claimed in any one of claims 1 to 24 further comprising a housing (700), wherein the rotor (200) and the stator (300) are located between a first housing side wall (702) and a second housing side wall (704), such that the first housing side wall (702) is spaced apart from the second housing side wall (704) along the rotational axis (202) by the rotor (200) and the stator (300); each of the first housing side wall (702) and the second housing side wall (704) being in sealing engagement with the stator (300); a first clearance being maintained between the first housing side wall (702) and a first side (215) of the rotor (200), and a second clearance being maintained between the second housing side wall (704) and a second side (217) of the rotor (200), so that the rotor (200) is rotatable relative to each of the first housing side wall (702) and the second housing side wall (704).

26. A rotary heat engine (100) as claimed in claim 25 wherein a side wall inlet port (708) is provided in the first housing side wall (702) and / orthe second housing side wall (704); the external side of the side wall inlet port (708) configured forfluid communication with the source of air (600); the internal side of the side wall inlet port (708) being in fluid communication with the or each first air inlet port (230) and the or each second air inlet port (232) when the or each first air inlet port (230) and the or each second air inlet port (232) pass the respective side wall inlet port (708) as the rotor (200) rotates about the rotational axis (202).

27. A rotary heat engine (100) as claimed in claim 26 when dependent on any one of claims 21 to 23 or as claimed in claims 21 to 23, wherein the first air inlet port (230)and / or the second air inlet port (232) are provided as an outlet slot (270) which extend transversely across the rotor outer surface (204), wherein the outlet slot (270) extends radially into the rotor (200); a feed slot (272) is provided on at least one side of the rotor (200) for fluid communication with the side wall inlet port (708), the feed slot (272) being provided as a recess which extends part, but not all, of the way around the or each side (215, 217) of the rotor (200); the outlet slot (270) being in fluid communication with the feed slot (272) via a passage (274) in the rotor (200).

28. A rotary heat engine (100) as claimed in claim 27 wherein a second labyrinth seal (263) is provided on each side (215, 217) of the rotor (200), each second labyrinth seal (263) extending around a diameter of the rotor (200) and provided between the side (215, 217) of the rotor (200) and a respective housing side wall (702, 704), the second labyrinth seal (263) extending at a smaller diameter than the first labyrinth seal (262), the feed slot (272) being provided between the first labyrinth seal (262) and the second labyrinth seal (263).

29. A method of operation of a rotary heat engine (100), the rotary heat engine (100) comprising: a rotor (200) centred on, and rotatable about, a rotational axis (202); and a stator (300) which bounds the rotor (200); wherein the rotor (200) is rotatable relative to the stator (300); the stator (300) defines a radially inner surface (304) which faces a radially outer surface (204) of the rotor (200); the rotor radially outer surface (204) defines at least one rotor combustion chamber (210); the stator radially inner surface (304) defines at least one stator combustion chamber (310); the number of rotor combustion chambers (210) is not equal to the number of stator combustion chambers (310); and the rotor (200) comprises a first air inlet port (230), wherein: the first air inlet port (230) is configured for communication with a source of air (600); the first air inlet port (230) is provided proximate to, but circumferentiallyspaced apart from, the or each rotor combustion chamber trailing edge (214); and the first air inlet port (230) opens on the rotor radially outer surface (204); whereby the method comprises the steps of controlling combustion events to occur in the or each rotor combustion chamber (210) and the or each stator combustion chamber (310) when a rotor combustion chamber (210) and a stator combustion chamber (310) are in fluid communication, and controlling combustion events to occur in sequential pairings of the or each rotor combustion chamber (210) and the or each stator combustion chamber (310).

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