AU2006230688B2

AU2006230688B2 - Engine

Info

Publication number: AU2006230688B2
Application number: AU2006230688A
Authority: AU
Inventors: James Anderson
Original assignee: HOOPER AILEEN
Current assignee: HOOPER AILEEN
Priority date: 2005-10-20
Filing date: 2006-10-19
Publication date: 2012-02-02
Anticipated expiration: 2026-10-19
Also published as: AU2006230688A1

Abstract

- 25 Abstract An engine (10) powered by a working fluid mixture comprising heated air under pressure and water which interact to generate superheated steam. Rapid expansion of the superheated steam is utilised to operate the engine and deliver 5 output power. The engine (10) comprises a body (11) in which is rotatably supported a central output shaft (12). The output shaft (12) comprises two shaft end sections (13) which extend from opposite ends of the body (11) for delivery of output shaft power. A flywheel (14) is supported between the two shaft sections (132). The flywheel (14) accommodates a swash plate mechanism (15) which is 10 drivingly mounted on the shaft (12). A bank of input shafts (23) is provided on each side of the swash plate mechanism (15). Each input shaft (23) comprises the piston shaft (25) of a double-headed piston structure (27) having a working piston head (29) and a pumping piston head (31) each mounted on the piston shaft (25). The double-headed piston structures (27) are each accommodated within a 15 respective cylinder (35) within the body (11). Each cylinder (35) is divided by its double-headed piston structure (27) into three chambers, being a working chamber (51), a pumping chamber (52) and a transition chamber (53). The working chamber (51) is defined between the working piston head (29) and an adjacent part (43) of the body 11. The pumping chamber (52) is defined between 20 the pumping piston head (31) and an adjacent part (39) of the body (11). The transition chamber (53) is defined between the two piston heads (29, 31). An air pressure chamber (65) is provided for accommodating pressurised air for delivery to the working chambers (51). A heater (71) is provided for heating air contained within the air pressure chamber (65). An inlet valve means (91) is associated with 25 each working chamber (51) for controlling intake air flow from the air pressure chamber (65) into the working chamber upon volume expansion of the working chamber. An exhaust valve means (103) is associated with each working chamber (51) for controlling exhaust flow from the working chamber (5)1 to the exhaust chamber (67). An air valve means (111) is provided for controlling air flow 30 from the exhaust chamber (67) into the pumping chamber (52) upon volume expansion thereof and ( 6)5 upon volume reduction of the pumping chamber (52). An injection means (150) is provided for injecting working fluid in the form of water - 26 into the working chamber (51). The injection means (150) injects a metered quality of water into the working chamber(51) as the working chamber completes a compression stroke, at which stage the air (which was previously introduced into the working chamber in a heated and pressurised state) has been further 5 compressed to significantly increase its pressure and temperature. Upon its injection, the water interacts with the heated and pressurised air to produce superheated steam which expands rapidly and causes the piston structure(27) to undergo a power stroke. C%4 rr m00 (NN

Description

P/00/0 11 28/5/91 Regulation 3.2 AUSTRALIA Patents Act 1990 ORIGINAL COMPLETE SPECIFICATION STANDARD PATENT Name of Applicants: James Anderson Aileen Hooper Lynette Anderson Cheryl Storrs Actual Inventor: James Anderson Address for service is: WRAY & ASSOCIATES Level 4, The Quadrant 1 William Street Perth, WA 6000 Attorney code: WR Invention Title: Engine The following statement is a full description of this invention, including the best method of performing it known to me: 1 -2 "Engine" Field of the Invention This invention relates to an engine. The engine according to the invention has been devised particularly, although 5 not necessarily solely, to produce work from steam generated from interaction between air and water in a working chamber of the engine. The engine according to the invention is not, however, limited to production of work from steam. The engine may be adapted to produce work from a combustion process in the working chamber. 10 Background Art It is known to produce work from steam using a reciprocating steam engine which involves a piston and cylinder assembly defining a working chamber into which steam is delivered to expand from high to low pressure. The expansion of the steam drives the piston which is typically coupled to a crank shaft at which 15 the useful work is extracted. Typically, such an engine requires a steam generator to supply the steam for the engine. It would be advantageous for there to be a steam engine which can generate steam for operating the engine as part of the engine operating cycle. 20 The preceding discussion of the background to the invention to the invention is intended only to facilitate an understanding of the present invention. It should be appreciated that the discussion is not an acknowledgement or admission that any of the material referred to was part of the common general knowledge as at the priority date of the application. 25 Summary of the Invention According to a first aspect of the invention there is provided an engine comprising a plurality of working chambers and associated pumping chambers, a plurality of working cylinders and a plurality of working pistons within the working -3 cylinders co-operating to define the working chambers, a pumping cylinders and a plurality of pumping pistons within the pumping cylinders co-operating to define the pumping chambers, each working chamber and its associated pumping chamber having a common piston shaft so that the working and pumping pistons 5 of each working chamber and its associated pumping chamber are thereby interconnected for reciprocatory movement in unison, the interconnected pistons being operatively connected to a rotatable output shaft, the plurality of working chambers and associated pumping chamber being disposed circumferentially about the output shaft, the common piston shaft for each working chamber and 10 its associated pumping chamber being operably connected to the output shaft through a swash-plate mechanism, an air pressure chamber, means for heating air within the air pressure chamber, air valve means for controlling air flow into the pumping chambers upon volume expansion thereof and for controlling air flow from the pumping chambers into the air pressure chamber upon volume 15 reduction of the pumping chambers, an inlet valve means for controlling intake air flow under pressure from the air pressure chamber into the working chambers, exhaust valve means for controlling exhaust flow from the working chambers, and injection means for injecting a working fluid into the working chambers for mixing with heated air introduced thereinto from the air pressure 20 chamber, whereby interaction between the heated air and the working fluid causes rapid expansion to provide a working fluid mixture, thereby to cause the working pistons to undergo a power stroke. The working fluid may take any appropriate form. In one arrangement, the working fluid may comprise water which, when injected 25 into the working chambers following a compression stroke of the working pistons to compress the heated air confined therein, interacts with the heated pressurised air to generate rapidly expanding steam to cause the working pistons to undergo the power stroke. Preferably, the steam comprises superheated steam. 30 Where the working fluid comprises water, it is preferably heated water. The water may be heated to about 95 0

C.

-4 In another arrangement, the working fluid may comprise an ignitable fuel which can undergo combustion in the presence of the pressurised air in each working chamber. The ignition process may be any suitable type, such as compression ignition or spark ignition. 5 Preferably, the working and pumping pistons of each working chamber and its associated pumping chamber are configured as a double-headed piston structure comprising two piston heads mounted on the common piston shaft, the common piston shaft being operably connected to the output shaft. The means for heating air contained within the air pressure chamber may 10 comprise a heater associated with the air pressure chamber. The heater may comprise an electrical heater element accommodated within the air pressure chamber. An exhaust chamber may be provided for receiving exhaust discharge from each working chamber upon opening of the exhaust valve means. 15 Where the working fluid comprises a mixture of air and water which is interacted to generate steam the exhaust fluid may separate in the exhaust chamber into its air component and its water component. The water component may be recirculated for subsequent injection into each pumping chamber at the injection means. The separated air component may be subsequently drawn into each 20 pumping chamber to be subsequently returned under pressure to the air pressure chamber. Where the working chambers and associated pressure chambers are disposed circumferentially about the output shaft in an array, there may be a common chamber disposed within the annular array of working chambers and associated 25 chambers, the common chamber providing the air pressure chamber. Further, there may be a common chamber disposed outwardly of the annular array of working chambers and associated pumping chambers, the outer chamber providing the exhaust chamber for the various working chambers and associated pumping chambers.

-5 The injection means associated with each working chamber may be adapted to operate in response to the position of the working piston of the working chamber. Preferably, the injection means is adapted to operate in response to contact by the working piston. In this regard, contact of the working piston with the injection 5 means may cause displacement of a pump element, initiating a pumping action to inject a metered quantity of working fluid into the working chamber. Preferably, the injection means comprises an injection chamber adapted to receive a charge of working fluid to be delivered into the injection chamber, an injection piston defining a wall of the injection chamber, the injection piston being 10 movable in response to said displacement of the pump element to cause volume contraction of the injection chamber, a valve controlling communication between the injection chamber and the working chamber for delivery of the charge of working fluid into the working chamber upon opening of the valve, and means for opening the valve in response to a predetermined level of pressure being 15 generated in the working fluid during volume contraction of the injection chamber. Preferably, there is a further injection piston, the two injection pistons being in opposed relation with the injection chamber defined therebetween. The two injection pistons may be adapted for movement in a direction transverse to the direction of displacement of the pump element. A cam mechanism may be 20 provided to act upon the two injection pistons to cause movement thereof inwardly with respect to each other and thereby cause volume contraction of the injection chamber upon the displacement of the pump element. Further, there may be provision for varying the profile of the cam mechanism operating the two injection pistons to adjust the volume of the charge of working fluid delivered 25 upon volume contraction of the injection chamber.

-6 Brief Description of the Drawings The invention will be better understood by reference to the following description of one specific embodiment thereof as shown in the accompanying drawings in which: 5 Figure 1 is a schematic sectional side elevational view of the engine according to the embodiment; Figure 2 is a fragmentary a schematic sectional side elevational view of the engine; Figure 3 is a schematic sectional elevational view of one working chamber 10 and associated pumping chamber within the engine, with the working chamber being shown at its maximum volume condition and the pumping chamber being shown at its minimum volume condition; Figure 4 is a view similar to Figure 3, with the exception that the working chamber is undergoing compression and the pumping chamber is 15 undergoing expansion; Figure 5 is also a view similar to Figure 3, with the exception that the working chamber is at its minimum volume condition in readiness for injection of fuel (water) and the pumping chamber is approaching its maximum volume condition; 20 Figure 6 illustrates the working chamber and the pumping chamber at the condition corresponding to Figure 3, following completion of a power stroke; Figure 7 is a schematic elevational view of a double piston structure used in the engine; 25 Figure 8 is a schematic elevational view of a cylinder used in the engine; -7 Figure 9 is a fragmentary view of the output shaft and flywheel of the engine, illustrating in particular a swash plate incorporated in the flywheel; Figure 10 is a schematic elevational view of an end housing of the engine; Figure 11 is a view of one end of the engine with the cover of the end 5 housing removed; Figure 12 is a schematic cross-sectional view of the engine, illustrating a bank of cylinders in which piston structures are received to define the working and pumping chambers; Figure 13 is a view of one of the cylinders illustrated in Figure 12; 10 Figure 14 is a view similar to Figure 13, illustrating flow passages between each cylinder and inner and outer chambers associated with the cylinders; Figure 15 is a schematic view of intake and exhaust valves associated with the flow passage illustrated in Figure 14; Figure 16 is a sectional view of an injection means for injecting fuel 15 (water) into each working chamber; Figure 17 is a further sectional elevational view of the injection means of figure 16; Figure 18 is a plan view of Figure 17; Figure 19 is a sectional view of the main housing of the injection means illustrating cam grooves provided therein; and 20 Figure 20 is a cross-sectional view of the main housing illustrating the profile of the cam grooves.

-8 Best Mode(s) for Carrying Out the Invention The embodiment shown in the drawings is directed to an engine which is powered by a working fluid mixture comprising heated air under pressure and water which interact to generate superheated steam. Rapid expansion of the 5 superheated steam is utilised to operate the engine and deliver output power. The engine 10 according to the embodiment comprises a body 11 in which is rotatably supported a central output shaft 12. The output shaft 12 comprises two shaft end sections 13 which extend from opposite ends of the body 11 for delivery of output shaft power. A flywheel 14 is supported between the two shaft 10 sections 13. The flywheel 14 accommodates a swash plate mechanism 15 which is drivingly mounted on the shaft 12. The swash plate mechanism 15 comprises a swash plate 16 having two opposed sides 17, 18 to which reciprocating forces are applied (as will be explained later) to cause rotation of the swash plate 15 mechanism and hence rotation of the drive shaft 12 to which it is drivingly connected. A bank 21 of input shafts 23 is provided on each side 17, 18 of the swash plate mechanism 15. Each input shaft 23 has an end configured for rolling or sliding engagement with the swash plate 16, whereby reciprocatory movement of the 20 input shaft transmits force to the swash plate to cause the latter to undergo rotation. The flywheel 14 is configured as a cylindrical structure comprising a cylindrical inner portion 19 and an annular outer portion 20 in spaced apart relation to define an annular space 22 therebetween. A drive plate 24 is connected between 25 the inner and outer portions 19, 20 to extend across the annular space 22 to define the swash plate 16 within the annular space. In the arrangement shown, the inner portion 19 is formed in two sections 19a, 19b between which the drive plate 24 is clamped, as shown in Figure 9. The two sections 19a, 19b are connected together by bolts 26 which also extend through the drive plate 24. The -9 drive plate 24 is connected to the outer portion 20 of the flywheel 14 by screw fasteners 28. The two sections 19a, 19b of the inner portion 19 of the flywheel 14 are each connected to one of the two shaft end sections 13, such as by bolted connections. 5 The opposed faces 17, 18 of the swash plate 16, as well as the faces of the inner and outer portions 19, 20 which confront the space 22, are hardened and polished (or otherwise treated) for wear resistance and to provide low-frictional properties. Each input shaft 23 comprises the piston shaft 25 of a double-headed piston 10 structure 27. The double-headed piston structure 27 has a working piston head 29 and a pumping piston head 31 each mounted on the piston shaft 25. The piston heads 29, 31 may be formed integrally with the piston shaft 25 or made separately and attached to the piston shaft. The piston heads 29, 31 are fitted with sealing rings or other sealing elements of any appropriate type. 15 This arrangement provides an array of double-headed piston structures 27 disposed circumferentially about the output shaft 12 on each side of the swash plate mechanism 15, with the piston shafts 25 defining the respective input shafts 23 in driving contact with the swash plate mechanism 15. The double-headed piston structures 27 are each accommodated within a 20 respective cylinder 35 within the body 11. Accordingly, there are a plurality of cylinders 35 disposed circumferentially about the output shaft 12 on each side of the swash plate mechanism 15. The engine body 11 comprises a central section 36 which accommodates the flywheel 14 and two end sections 37 which accommodate the cylinders 35. 25 The central section 36 comprises an outer casing 38 supported between two inner plates 39. Specifically, the outer casing 38 is clampingly engaged between the two inner plates 39 which are connected together by clamp rods 40 extending therebetween.

- 10 The two end sections 37 each comprise an outer casing 41 supported between a respective one of the inner plates 29 and an end housing 42. Each end housing 42 comprises an end plate 43 and an end cover 44 which cooperate to define an end space. The outer casing 41 is supported between the respective inner plate 5 39 and the respective end housing 42. Specifically, the outer casing 41 is clampingly engaged between the inner plate 39 and the end plate 43, with the inner plate 39 and the end housing 42 being connected together by clamp rods 44 extending therebetween. The cylinders 35 accommodated in each end section 37 are also supported 10 between the respective inner plate 39 and the respective end plate 43 forming part of the end cover 44. With this arrangement, the cylinders 35 are closed at their inner ends by the inner plates 39 and are closed at their outer ends by the end plates 43. Each cylinder 35 comprises an inner cylinder wall 45 which defines the cylinder 15 space accommodating the double-headed piston structure 27, and an outer cylinder wall 46 spaced from the inner wall 45. An annular space 47 is defined between the inner and outer cylinder walls 45, 46 through which cylinder clamps rods 48 extend to clamp the two cylinder walls between the inner plate 39 and the end plate 43. Each cylinder inner wall 45 is formed in two sections 45a, 45b 20 bonded together. The flywheel 14 is accommodated in the space 50 defined between the outer casing 38 and the two inner plates 39. The various input shafts 23 extend through openings 55 in the respective inner plates 39 into the annular space 22 for engagement with the swash plate 16. Bearings 56 are provided at the 25 openings 55 for supporting the reciprocating input shafts 23. Further, the input shafts 23 have bearings 57 thereon for rolling engagement with the adjacent faces of the inner and outer portions 19, 20 as the flywheel 14 rotates, as shown in Figure 7. The sides of the input shafts 23 may be hardened and polished. The end 58 of each input shaft 23 in contact with the swash plate 16 may 30 configured for rolling engagement with the swash plate, such as by provision of a - 11 roller 59, as shown in Figure 7. Each cylinder 35 is divided by its double-headed piston structure 27 into three chambers, being a working chamber 51, a pumping chamber 52 and a transition chamber 53. The working chamber 51 is defined between the working piston head 29 and the adjacent end plate 43 of the body 5 11. The pumping chamber 52 is defined between the pumping piston head 31 and the inner plate 39 closing the adjacent end of the cylinder 35. The transition chamber 53 is defined between the two piston heads 29, 31. The section 45a of each cylinder wall 45 is of a larger diameter than the section 45b in order to provide at least some compensation in chamber 52 for the volume therein 10 occupied by the piston shaft 25. As mentioned above, the bank 21 of cylinders 35 are disposed circumferentially about the output shaft 12. With this arrangement, an inner chamber 61 is defined within the body 11, the inner chamber being disposed around the output shaft 12 and inwardly of the bank 21 of cylinders 35. More particularly, the inner 15 chamber 61 is defined between the bank of cylinders 21 and an inner wall 62 defined by a tube which surrounds the output shaft 12 in spaced apart relation therewith. Additionally, an outer chamber 63 is defined within the body 11, on the outer side of the bank of cylinders 35. More particularly, the outer chamber 63 is defined 20 between the bank of cylinders 21 and the outer casing 41. The inner chamber 61 provides a pressure chamber 65 for accommodating pressurised air for delivery to the working chambers 51, as will be explained in more detail later. The outer chamber 63 provides an exhaust chamber 67 to receive exhaust 25 products discharged from the working chambers 51, also as will be explained in more detail later. A heater 71 is provided for heating air contained within the pressure chamber 65. The heater 71 comprises an electrical heater coil 73 winding around the inner - 12 wall 62 which surrounds the output shaft 12. Electrical power is delivered to the heater coil 73 from a power source (not shown) by electrical leads 77. A refrigeration system 81 is provided for cooling exhaust products received in the exhaust chamber 67 from the various working chambers 51. The refrigeration 5 system 81 comprises a condenser 83 accommodated within the exhaust chamber 67, the condenser receiving refrigerant via a refrigerant line 85. An inlet valve means 91 is associated with each working chamber 51 for controlling intake air flow from the air pressure chamber 65 into the working chamber upon volume expansion of the working chamber (corresponding to 10 movement of the working piston head 29 away from the head plate 39). The inlet valve means 91 comprises two intake valves 93 each comprising a valve port 95 opening onto the working chamber 51 and a valve member 97 for opening and closing the valve port 95. The valve member 97 is in the form of a conventional poppet valve comprising a valve head 98 and a valve stem 99 operably 15 connected to a valve control mechanism 100 accommodated in the end housing 44. The control mechanism 100 comprises a rocker arm 101 pivotally mounted on a pedestal 102 projecting from end plate 43. The rocker arm 101 has one end 104 in sliding contact with a cam plate 110 mounted on the output shaft 12 for 20 rotation therewith. The rocker arm 101 is bifurcated at its other end 106 to provide two end sections 106a, 106b each operating one of the two intake valves 93. With this arrangement, the cam plate 110 is common to the rocker arms 101 of the valve control mechanisms 100 for all the working chambers 51. An exhaust valve means 103 is associated with each working chamber 51 for 25 controlling exhaust flow from the working chamber 51 to the exhaust chamber 67. In this embodiment, the exhaust valve means 103 comprises a plurality of circumferentially spaced exhaust ports 105 incorporated in the side wall of the respective cylinder 35 and arranged to be open and closed by the working piston head 29.

-13 An air valve means 111 is provided for controlling air flow from the exhaust chamber 67 into the pumping chamber 52 upon volume expansion thereof (corresponding to movement of the pumping piston head 31 away from the inner wall 41) and for controlling air flow from the pumping chamber 52 into the air 5 pressure chamber 65 upon volume reduction of the pumping chamber 52 (corresponding to movement of the pumping piston head 31 towards the inner wall 41). Specifically, the air valve means 111 comprises a plurality of intake valves 113 for controlling air flow through ports 114 into the pumping chamber 52 upon volume expansion thereof and a plurality of discharge valves 115 for 10 controlling discharge of air through ports 116 from the pumping chamber 52 into the pressurised air chamber 65 upon volume reduction of the pumping chamber. Each discharge valve 115 is set to open after the air pressure within the pumping chamber 52 attains a prescribed level exceeding the prescribed air pressure within the air pressure chamber 65. In this way, replenishment air is delivered to 15 the air pressure chamber 65 and the air pressure within that chamber maintained at a pressure level above a prescribed minimum operating level. Because the replenishment air is source from the exhaust chamber 67 there is in fact recirculation of air within the engine. A compressor (not shown) is provided for delivery of an initial charge of air to the 20 air pressure chamber 65 via air delivery line 117 and for also providing any replenishment air that might be necessary during operation of the engine in order to maintain air pressure within the air pressure chamber 65 above the prescribed minimum. The air pressure chamber 65 incorporates a pressure sensor for monitoring air pressure within the chamber and operating the compressor as 25 necessary for delivery of replenishment air. In this embodiment, the intake valves 113 are in the form of mechanically actuated poppet valves 117 each comprising a valve member 119 adapted to move into and out of sealing engagement with a valve seat 121, as shown in figure 9, for opening and closing flow passages 120 (including ports 114) 30 extending between the exhaust chamber 67 and the pumping chamber 52. Similarly, the discharge valves 115 are in the form of mechanically operated -14 poppet valves 123 each comprising a valve member 125 moveable into and out of sealing engagement with a valve seat 127 for opening and closing flow passages 129 (including ports 116) extending between the pumping chamber 52 and the air pressure chamber 65. 5 The ports 105, 114 and 116 are incorporated in the walls 45, 46 of the cylinders 35, as best seen in Figure 8. An injection means 150 is provided for injecting working fluid in the form of water into the working chamber 51. The injection means 150 injects a metered quality of water into the working chamber 51 as the working chamber completes a 10 compression stroke, at which stage the air (which was previously introduced into the working chamber in a heated and pressurised state) has been further compressed to significantly increase its pressure and temperature. At this stage, the air is typically at a pressure of about 900 KN/m 2 and a temperature of about 3000 0 C. Upon its injection, the water interacts with the heated and pressurised 15 air to produce superheated steam which expands rapidly and causes the piston structure 27 to undergo a power stroke. Because the air within the working chamber 51 is highly pressurised at the time of water injection, it is necessary for the injection means 150 to inject the water at high pressure (at a level exceeding the pressure within the working chamber). 20 The injection means 150 is responsive to the position of the working piston 51 and is in fact actuated by the working piston head 29. The injector means 150 is accommodated primarily in the respective end housing 42. In Figure 11 of the drawings, only one injection means 150 is shown, although there is in fact an injection means associated with each working chamber 51. 25 The injector means 150 comprises a main housing 151 having a threaded stud 153 for mating engagement in a threaded hole 155 in the end plate 43. The main housing 151 is of hollow construction, incorporating a first bore 157 which opens onto the end of the main housing corresponding to the stud 153, and a second bore 159 which is of larger diameter than the first bore 157 and which -15 opens onto the other end of the main housing. A step 161 is incorporated in the main housing at the junction between the two bores 157,159. The other end of the main housing is fitted with an end cap 162. An actuator 163 is slidably and rotatably accommodated in the two bores 5 157,159 within the main housing 151. The actuator 163 comprises a pump element configured as a spigot portion 165 which is accommodated within the first bore 157 and which extends beyond the threaded stud 153 to define a contact face 167 at the end thereof. The actuator 163 further comprises a main body portion 169 which is accommodated within the second bore 159. The end 10 of the main body portion 169 opposite to the spigot portion 165 incorporates a circumferential recess 171 which accommodates an actuator return spring 173. The return spring 173 acts between a face 175 of the main body portion 169 adjacent the recess 171 and a boss 177 accommodated within the end cap 162 fitted onto the main housing 151. 15 The boss 177 is operably connected to a throttle lever 181 and is also coupled to the actuator 63. With this arrangement, angular movement of the throttle lever 181 causes rotation of the throttle boss 177 with respect to the end cap 162 and also corresponding rotational movement of the actuator 163. An injection pump chamber 183 is provided within the main body portion 169 of 20 the actuator 163. The pump chamber 183 is defined within a transverse bore 185, the outer ends of which each accommodate an injection pump piston 187. Each piston 187 has an inner end 189 defining an end face 191 confronting the pump chamber 183 and an outer end 193 configured as a lobe 195 accommodated within a cam groove 197 on the wall of the second bore 159. 25 Each cam groove 197 presents a cam surface 198 configured as a ramp to cause the piston 187 with which it is engaged to undergo displacement as the piston moves along the groove 197. The injection pump chamber 183 receives fuel (water) via a fuel supply path 201 which extends from a fuel pipe nipple 203 incorporating a non-return valve 205.

-16 The actuator 163 incorporates a central passage 211 which accommodates a needle valve 213. The needle valve 213 comprises a needle shank 215 and head 217. The shank 215 terminates at a valve end 217 adapted to cooperate with a valve seat 219 at the adjacent end of the central passage 211. The valve 5 needle 213 is moveable axially within the central passage 211 for moving the valve end 217 into and out of sealing engagement with the valve seat 219. A delivery passage 221 extends from the valve seat 219 to two opposed delivery ports 223 adjacent the end face 167 of the actuator 163. A valve spring 231 acts on the head 217 of the needle valve 213 for maintaining the valve end 217 in 10 sealing engagement with the valve seat 219. The spring tension, and thereby the spring force acting on the needle valve 213, is selectively variable by adjusting screws 233 against which the spring 231 acts and which is in threaded engagement with the actuator. In this way, rotation of the screws 233 varies the spring force acting on the needle valve. 15 The needle valve 213 extends through the pump chamber 113 and there is a clearance space 220 between the shank 215 of the needle valve 213 and the central passage 211 within the actuator. The clearance space 220 defines an annular cavity along which fuel from the pump chamber 183 can flow, both towards the valve seat 219 and also towards the needle valve head 217. 20 The injection pump chamber 183 receives water from a fuel source via the fuel supply passage 201. When the contact face 167 of the fuel injection means 150 is contacted by the working piston head 29 as the working chamber 51 approaches its minimum volume condition, the spigot portion 165 is pushed inwardly within the main 25 housing 151. The inward movement of the actuator 163 as a whole causes the lobes 195 of the injection pump pistons 117 to move along their respecting cam grooves 197 within the main housing 151. This causes the injection pump pistons 187 to move inwardly, thereby contracting the volume of the pumping chamber 183. The volume contraction of the injection pumping chamber 183 30 applies pressure to water contained within the chamber. This in turn applies fluid - 17 pressure to the head 217 of the needle valve 213 to lift the valve to overcome the biasing effect of the valve spring 231, thereby lifting the valve end 217 out of sealing engagement with the valve seat 219. The water under pressure can then flow along delivery passage 221 to delivery port 223 from where it is injected into 5 the working chamber 51. Once the water has been injected into the working chamber 51, fluid pressure within the needle valve mechanism drops and the needle valve 213 is closed under the influence of the valve spring 231. Once the pump piston head 51 moves out of engagement with the contact face 167, the spring 173 returns the actuator 163 to its original position, with the spigot portion 10 165 at it maximum outward extent with respect to the main housing 151. As the actuator 163 undergoes this return movement, the piston lobes 195 also undergo return movement along their respecting cam grooves 197, thereby allowing the pistons to move outwardly under the influence of the pressure of water entering the pump chamber 183. 15 With this arrangement, it can be seen that the injection means 150 delivers a metered quantity of fuel (which in this embodiment is in the form of water) into the working chamber 51 when it is actuated in response to contact by the piston. Throttling can be achieved by rotation of the actuator 163 through operation of the throttle lever 181. Rotation of the actuator 163 varies the profile of the cam 20 surface 198 confronted by each piston lobe 195 as it moves along the respective cam groove 197. In this way, the volume of water delivered by the injection means 150 can be varied. Operation of the engine according to the embodiment will now be described with reference to figures 3 to 6. 25 At start up, it is necessary to operate the air compressor to deliver air under pressure to the air pressure chamber 65 and to also operate the heater 71 to heat the air. Once the engine 10 is ready to be started, a starter motor (not shown) is engaged to rotate the output shaft 12 to cause the operating cycle of the engine to commence. The description will commence with the engine at the 30 stage of its cycle as illustrated in Figure 3 where the particular working chamber -18 51 shown is at its maximum volume condition and its associated pumping chamber 52 is at its minimum volume condition. As the swash plate mechanism 15 rotates, the piston structure 27 undergoes reciprocation, with the working piston head 29 moving towards end plate 43 and the pumping piston head 31 5 moving away from the inner plate 39 causing expansion of the pumping chamber 52. As the pumping chamber 52 expands, air is drawn from exhaust chamber 67 through flow passages 120 and the open intake valves 113 into the pumping chamber 52. As the working piston head 29 moves past exhaust ports 105, it closes the working chamber 51. Air is injected into the working chamber 51 from 10 the air pressure chamber 65 via the inlet valve means 91 which open under the influence of the valve control mechanism 101. The air delivered into the working chamber 51 is compressed as the working chamber contracts. The compression of the air heats the air further, typically to temperatures of about 30000C. As the working chamber 51 approaches its minimum volume condition, the working 15 piston head 29 contacts the injection means 150, thereby causing the spigot portion 165 to deflect inwardly, with the result that a metered quantity of water is injected into the working chamber. Because of its construction, the injection means 150 delivers the injected water at a pressure exceeding the air pressure within the air chamber. Typically, the water is injected at a pressure exceeding 20 900 KN/m2 and at a temperature of about 95 *C. As the injected water interacts with the air (which is of high pressure and temperature), superheated steam is generated. The superheated steam expands rapidly, driving the piston structure 27 in the reverse direction. Consequently, the working chamber 51 expands and the pumping chamber 52 contracts. As the working chamber 51 continues to 25 expand, the working piston head 51 moves past the exhaust ports 105, thereby opening the exhaust ports and allowing exhaust products within the working chamber 51 to discharge through the exhaust ports into the exhaust chamber 67. There is some overlap in the operation of the intake valve 93 and the exhaust ports 105, such that while the exhaust ports 105 are still open the intake valve 93 30 open to deliver air into the working chamber. The incoming air assists scavenging of the working chamber 51 until such time as the piston structure commences its return movement and closes the exhaust ports 105.

- 19 The contraction of the pumping chamber 52 delivers air under pressure from the pumping chamber through the flow passages 129 and open discharge valves 115 into the air pressure chamber 65 to replenish air previously drawn therefrom. Air contained within the air pressure chamber 65 is heated as previously 5 mentioned by the heater 71, typically to a temperature of about 95*C. The exhaust products which enter the exhaust chamber 67 are cooled by the condenser 83 and separated into water and air components. The water components are withdrawn from the exhaust chamber 67 and recirculated to a supply which provides a source of water for the injection means 150. The air 10 remains in the exhaust chamber 67 in readiness to be drawn into the pumping chamber 52 upon volume expansion thereof. From the foregoing, it is evident that the present embodiment provides an engine which is powered by steam generated from interaction between air and water, with the exhaust being processed to be separated into its water and air 15 components for re-use. The engine has certain advantages over conventional reciprocating piston internal combustion engines in that it is of a simpler design and so may be easier to manufacture from an engineering perspective, it has no crankshaft and also does not release emissions to atmosphere. It should be appreciated that the scope of the invention is not limited to the scope 20 of the embodiment described. For example, while the engine according to the embodiment has been described as operating under steam pressure, it should be appreciated that the engine can also be adapted to operate as an internal combustion engine where an ignitable fuel (such as gasoline or Diesel fuel) would be injected into the working chamber to interact with air contained therein 25 to provide a combustible mixture. The combustible mixture may be caused to ignite by an external influence such as an ignition spark, or alternatively may be self-igniting by virtue of the temperatures and pressures to which it is exposed. Exhaust products may be exhausted to atmosphere (after undergoing any appropriate pre-treatment) in a manner similar to conventional internal 30 combustion engines. Further, the exhaust products may be cooled by a cooling -20 system other than refrigeration, if desired. For example, air cooling systems and water cooling systems (including recirculated water) may be used. Modifications and changes can be made without departing from the scope of the invention. 5 Throughout the specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers. 10 15 20

Claims

1. An engine comprising a plurality of working chambers and associated pumping chambers, a plurality of working cylinders and a plurality of working pistons within the working cylinders co-operating to define the working chambers, a plurality of pumping cylinders and a plurality of pumping pistons within the pumping cylinders co-operating to define the pumping chambers, each working chamber and its associated pumping chamber having a common piston shaft so that the working and pumping pistons of each working chamber and its associated pumping chamber are thereby interconnected for reciprocatory movement in unison, the interconnected pistons being operatively connected to a rotatable output shaft, the plurality of working chambers and associated pumping chambers being disposed circumferentially about the output shaft, the common piston shaft for each working chamber and its associated pumping chamber being operably connected to the output shaft through a swash-plate mechanism, an air pressure chamber, means for heating air within the air pressure chamber, air valve means for controlling air flow into the pumping chambers upon volume expansion thereof and for controlling air flow from the pumping chambers into the air pressure chamber upon volume reduction of the pumping chambers, an inlet valve means for controlling intake air flow under pressure from the air pressure chamber into the working chambers, exhaust valve means for controlling exhaust flow from the working chambers, and injection means for injecting a working fluid into the working chambers for mixing with heated air introduced thereinto from the air pressure chamber, whereby interaction between the heated air and the working fluid causes rapid expansion to provide a working fluid mixture, thereby to cause the working pistons to undergo a power stroke.

2. An engine according to claim 1 wherein the working fluid comprises water which, when injected into the working chambers following a compression stroke of the working pistons to compress the heated air confined therein, interacts with the heated pressurised air to generate rapidly expanding steam to cause the working pistons to undergo the power stroke.

3. An engine according to claim 2 wherein the steam comprises superheated steam. - 22

4. An engine according to claim 2 or 3 wherein the water comprises heated water.

5. An engine according to claim 4 wherein the water is heated to about 95 0 C.

6. An engine according to claim 1 the working fluid may comprise an ignitable fuel which can undergo combustion in the presence of the pressurised air in each working chamber.

7. An engine according to any one of the preceding claims wherein the working and pumping pistons of each working chamber and its associated pumping chamber are configured as a double-headed piston structure comprising two piston heads mounted on the common piston shaft, the common piston shaft being operably connected to the output shaft.

8. An engine according to any one of the preceding claims wherein the means for heating air contained within the air pressure chamber comprises a heater associated with the air pressure chamber.

9. An engine according to claim 8 wherein the heater comprises an electrical heater element accommodated within the air pressure chamber.

10. An engine according to any one of the preceding claims further comprising an exhaust chamber for receiving exhaust discharge from each working chamber upon opening of the exhaust valve means.

11. An engine according to claim 10 when dependent upon claim 2 wherein the exhaust fluid undergoes separation in the exhaust chamber into its air component and its water component.

12. An engine according to claim 11 wherein the water component is recirculated for subsequent injection into each pumping chamber at the injection means.

13. An engine according to claim 11 or 12 wherein the separated air component is drawn into each pumping chamber for return under pressure to the air pressure chamber. -23

14. An engine according to any one of the preceding claims wherein the working chambers and associated pressure chambers are disposed circumferentially about the output shaft in an array.

15. An engine according to claim 14 wherein there is a common chamber disposed within the array, the common chamber providing the air pressure chamber.

16. An engine according to claim 14 or 15 when dependent on claim 10 wherein there is a common chamber disposed outwardly of the array, the common chamber providing the exhaust chamber for the various working chambers and associated pumping chambers.

17. An engine according to any one of the preceding claims wherein the injection means associated with each working chamber is adapted to operate in response to the position of the working piston of the working chamber.

18. An engine according to claim 17 wherein the injection means is adapted to operate in response to contact by the working piston.

19. An engine according to claim 18 wherein contact of the working piston with the injection means is adapted to cause displacement of a pump element, initiating a pumping action to inject a metered quantity of working fluid into the working chamber.

20. An engine according to claim 19 wherein the injection means comprises an injection chamber adapted to receive a charge of working fluid to be delivered into the injection chamber, an injection piston defining a wall of the injection chamber, the injection piston being movable in response to said displacement of the pump element to cause volume contraction of the injection chamber, a valve controlling communication between the injection chamber and the working chamber for delivery of the charge of working fluid into the working chamber upon opening of the valve, and means for opening the valve in response to a predetermined level of pressure being generated in the working fluid during volume contraction of the injection chamber. - 24

21. An engine according to claim 20 wherein there is a further injection piston, the two injection pistons being in opposed relation with the injection chamber defined therebetween,

22. An engine according to claim 21 wherein the two injection pistons are adapted for movement in a direction transverse to the direction of displacement of the pump element.

23. An engine according to claim 22 further comprising a cam mechanism for acting upon the two injection pistons to cause movement thereof inwardly with respect to each other and thereby volume contraction of the injection chamber upon said displacement of the pump element.

24. An engine according to claim 23 further comprising means for varying the profile of the cam mechanism operating the two injection pistons to adjust the volume of the charge of working fluid delivered upon volume contraction of the injection chamber.

25. An engine substantially as herein described with reference to the accompanying drawings.