USOO7762219B2

(12) United States Patent (10) Patent No.: US 7.762,219 B2 Shuttleworth (45) Date of Patent: Jul. 27, 2010

(54) RECIRCULATION SYSTEM FOR MOTOR 5,647.309 A 7/1997 Avery 5,782,226 A 7/1998 Gartner (75) Inventor: Richard Jack Shuttleworth, Nelson 6,386,154 B1* 5/2002 Hellman et al...... 123,588 (NZ) 6.427,644 B1 8, 2002 Dabadie et al. 6,431,128 B1 8, 2002 Dabadie (73) Assignee: Shuttleworth Axial Motor Company, Nelson (NZ) FOREIGN PATENT DOCUMENTS (*) Notice: Subject to any disclaimer, the term of this EP O682743 11, 1995 patent is extended or adjusted under 35 EP O953745 11, 1999 U.S.C. 154(b) by 576 days. 2.E. 2. (21) Appl. No.: 10/590,337 W s 12 (22) PCT Filed: Feb. 7, 2005 W S. :3. (86). PCT No.: PCT/NZ2OOS/OOOO11 * cited by examiner S371 (c)(1), (2), (4) Date: Jun. 22, 2007 Primary Examiner Noah Kamen (74) Attorney, Agent, or Firm—Dann, Dorfman, Herrell and (87) PCT Pub. No.: WO2005/080781 Skillman, P.C. PCT Pub. Date: Sep. 1, 2005 (57) ABSTRACT (65) Prior Publication Data A motor has an engine block with cylinders arranged to fire in US 2007/O295OO8A1 Dec. 27, 2007 a firing order. Arecirculation system delivers combusted mix s ture from a cylinder which has just fired to at least partly mix (30) Foreign Application Priority Data with fuel for the next cylinder in the firing order. Injector bodies (401-405) are associated with each cylinder. Each Feb. 23, 2004 (NZ) ------531314 injector body (401-405) has an internal chamber (424) in communication with a fuel inlet port (426) for delivering fuel (51) Int. Cl. into the internal chamber, a fuel outlet port (428) for deliver F02B 75/20 (2006.01) ing fuel under pressure from the chamber into the associated (52) U.S. Cl...... 123/58.8 cylinder and a combusted mixture out-let port (442). The (58) Field of Classification Search ...... 123/58.8 combusted mixture outlet port (442) of each injector body See application file for complete search history. (401–405) is fluidly connected to the combusted mixture inlet port (438) of the next cylinder in the firing order. Alterna (56) References Cited tively, the recirculation system is arranged Substantially inter U.S. PATENT DOCUMENTS nally within the cylinder head. 4.475,524 A 10, 1984 Eckert et al. 4,787,343 A 1 1/1988 Tuckey 34 Claims, 7 Drawing Sheets

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NZZ (Z ||89 US 7,762,219 B2 1. 2 RECIRCULATION SYSTEM FOR MOTOR plurality of cylinders arranged to fire with a firing order, and a recirculation system configured to deliver combusted mix FIELD OF THE INVENTION ture under combustion pressure and temperature from a cyl inder which has just fired to at least partly mix with fuel for the The present invention relates to a recirculation system for a 5 next cylinder in the firing order to improve the combustion motor or engine and to a motor or engine incorporating the properties of the fuel. recirculation system. While the invention has application for It should be noted that where reference herein is made to axial motors, it also has applications for other motors. The “combusted mixture under combustion temperature and pres term “motor is used interchangeably with “engine'. Sure', that need not mean that the temperature and pressure 10 will be at the same levels as at the time of combustion, as BACKGROUND TO THE INVENTION pressure and temperature losses will occur during transfer of the mixture. However, the mixture will be at a significantly Over the years engine manufacturers have been working to elevated temperature and pressure relative to any combustible improve the weight, size efficiency and manufacturing costs mixture in the next cylinder in the firing order. of engines. In part this has lead to the development of axial 15 motors. An axial motor includes an engine block in which the The term comprising as used in this specification and cylinders are spaced evenly in a circular configuration about claims means consisting at least in part of, that is to say an axis of the engine block, rather than in the inline, “V” or when interpreting statements in this specification and claims horizontally opposed configurations of traditional engines. which include that term, the features prefaced by that term in The reciprocal motion of the pistons in an axial motor can be each statement all need to be present but other features can transferred to rotational motion of an output shaft by way of also be present. a wobble plate configuration, such as that disclosed in NZ In accordance with a second aspect of the present inven 221336. tion, there is provided a motor comprising: an engine block Generally, as with conventional internal combustion with a plurality of cylinders arranged to fire with a firing engines, the compression ratio and therefore power output of 25 order; and a recirculation system comprising fluid transfer the axial motor is at least in part limited by the quality of the paths which are arranged to provide a fluid connection fuel being burnt. If poor quality fuel is used, a lower com between cylinders sequentially in the firing order of the pression ratio must be used in the motor or else “knocking’ or motor, the motor configured Such that combustion in a cylin auto-igniting will occur, which ultimately could damage der creates a combusted mixture having a combustion pres components of the motor. Some higher density fuels (“heavy' 30 Sure, which combustion pressure forces some of that com fuels) such as diesel hydrocarbon fuel exhibit poor combus busted mixture to at least partly mix with fuel for the next tion properties as they are difficult to atomise prior to com cylinder in the firing order to improve the combustion prop bustion, compared to lower density fuels (“light' fuels) such erties of the fuel. as petrol. In one embodiment, each cylinder has an injector body A number of internal combustion engines are configured to 35 associated therewith, with each injector body having an inter deliver exhaust gas under relatively low pressure to cylinders nal chamber in communication with a fuel inlet port for to go some way towards improving combustion properties delivering fuel into the internal chamber, a fuel outlet port for and/or reducing emissions. Such engines are described in delivering fuel under pressure from the chamber into the U.S. Pat. No. 6,427,644; U.S. Pat. No. 5,782,226; U.S. Pat. associated cylinder, a mixture inlet port and a mixture outlet No. 4,475,524 and EP 0682743. 40 port, with the mixture inlet port of each injector body in fluid WO 03/008785 and WO 03/040530 to Scuderi describe communication with the mixture outlet port of an injector four stroke split cycle internal combustion engines. The body associated with the immediately preceding cylinder in engines have a compression cylinder containing a compres the firing order of the motor, the motor configured to deliver sion piston and a power cylinder containing a power piston. combusted mixture under combustion pressure and tempera The compression piston performs the intake and compression 45 ture from an outlet port of an injector body associated with a strokes of a four stroke cycle, and the power piston performs cylinder that has just fired to an inlet port of an injector body the power and exhaust strokes of the same four stroke cycle. associated with the next cylinder in the firing order of the A fresh air/fuel mixture is compressed in the compression motor to at least partly mix with fliel in the internal chamber cylinder and is delivered via a gas passage to the combustion of the injector body associated with said next cylinder in the cylinder for combustion, and then exhausted from the engine. 50 firing order to improve the combustion properties of the fuel. The two pistons are provided so that the power piston can be The fuel inlet port of each injector body is preferably offset to align the maximum combustion pressure with the configured for receipt of a respective fuel injector. maximum torque applied to the crank shaft, and so that the Advantageously, each mixture inlet port comprises a non compression piston can be offset to align the maximum com return valve which allows the mixture to travel into the inter pression with the maximum torque applied from the crank 55 shaft. The Scuderi systems do not address compression ratio nal chamber through the port but not out of the internal issues. Only fresh compressed mixture is shared between chamber through the port. cylinders. Preferably, each mixture outlet port comprises a non-return It is an object of the present invention to provide a recircu valve which allows mixture to travel out of the internal cham lation system for a motor which is operable to improve com 60 berthrough the port but not into the internal chamber through bustion properties and improve performance and/or which at the port. least provides the public with a useful choice. Suitably, each fuel inlet port comprises a non-return valve which allows fuel to flow into the internal chamber through SUMMARY OF THE INVENTION the fuel inlet port, but not out of the internal chamber through 65 the fuel inlet port. In accordance with a first aspect of the present invention, Transfer paths are preferably provided to fluidly connect there is provided a motor comprising: an engine block with a the mixture outlet port of each injector body with the mixture US 7,762,219 B2 3 4 inlet port of the injector body associated with the next cylin Preferably, each mixture outlet port comprises a non-return der in the firing order. The transfer paths may be pipes, tubes, valve which allows mixture to travel out of the internal cham or the like. berthrough the port but not into the internal chamber through In an alternative embodiment, the recirculation system is the port. arranged substantially internally within a cylinder head of the Each fuel inlet port may comprise a non-return valve which motor. Preferably, the cylinder head comprises a pre-mix allows fuel to flow into the internal chamber through the fuel chamber is associated with each cylinder, and the cylinder inlet port, but not out of the internal chamber through the fuel head includes transfer paths configured to deliver combusted inlet port. mixture under combustion pressure and temperature from the Preferably, the mixture outlet port of each injector body is pre-mix chamber associated with a cylinder that has just fired 10 fluidly connected to the mixture inlet port of the injector body to the pre-mix chamber associated with the next cylinder in associated with the next cylinder in the firing order of the the firing order. Preferably, each transfer path comprises at motor by a transfer path. Each transfer path may comprise a least one non-return valve configured to allow combusted pipe or tube. mixture under combustion pressure and temperature to be The recirculation system is preferably configured such that delivered to the pre-mix chamber associated with the next 15 the combusted mixture at least partly atomises the fuel in the cylinder in the firing order. internal chamber to which the combusted mixture has been It is preferred that a fluid path is provided between each delivered under combustion pressure and temperature. pre-mix chamber and the respective cylinder, and preferably In accordance with a fourth aspect of the present invention, the fluid path includes a nozzle to deliver mixture for com there is provided a method of enhancing combustion in a bustion into the respective cylinder under pressure. motor having an engine block with a plurality of cylinders The motor may be an inline, “V”, or horizontally opposed arranged to fire with a firing order, comprising delivering (“boxer') configuration two- or four-stroke internal combus combusted mixture under combustion pressure and tempera tion motor. Alternatively, the motor may be a two- or four ture from a cylinder which has just fired to at least partly mix stroke axial motor. The system could also be used with a with fuel for the next cylinder in the firing order to improve rotary engine. 25 the combustion properties of the fuel. In the two-stroke embodiment, the motor is preferably Preferably, each cylinder has an injector body associated configured such that the combusted mixture is delivered to at therewith, with each injector body having an internal cham least partly mix with the fuel for the next cylinder in the firing ber in communication with a fuel inlet port for delivering fuel order as the piston in said next cylinder is nearing the top of its into the internal chamber, a fuel outlet port for delivering fuel compression stroke. Preferably, the motor is configured Such 30 underpressure from the chamber into the associated cylinder, that when a cylinder is on its compression stroke, some a mixture inlet port and a mixture outlet port, with the mixture uncombusted air/fuel mixture is delivered under relatively inlet port of each injector body in fluid communication with low pressure to the next cylinder in the firing order as said next the mixture outlet port of an injector body associated with the cylinder is undergoing its compression stroke. immediately preceding cylinder in the firing order of the In a preferred embodiment the motor is configured to 35 motor, and wherein the method comprises delivering com deliver some uncombusted mixture from a cylinder as its busted mixture under combustion pressure and temperature piston is undergoing a compression stroke to a fluid transfer from an outlet port of an injector body associated with a path which provides a fluid connection between that cylinder cylinder that has just fired to an inlet port of an injector body and the following cylinder in the firing order, such that when associated with the next cylinder in the firing order of the combustion occurs in the cylinder, the combusted mixture 40 motor to at least partly mix with fuel in the internal chamber from that cylinder forces the uncombusted mixture from the of that adjacent injector to improve the combustion properties transfer path to mix with fuel for the next cylinder in the firing of the fuel. order. Transfer paths may be provided to link the mixture outlet In accordance with a third aspect of the present invention, port of each injector body with the mixture inlet port of the there is provided a recirculation system for a motor having a 45 injector body associated with the next cylinder in the firing plurality of cylinders arranged to fire with a firing order, order, and the step of delivering combusted mixture under comprising: a plurality of fuel injector bodies, each injector combustion pressure and temperature from an outlet port of body having an internal chamber in communication with a an injector body associated with a cylinder that has just fired fuel inlet port for delivering fuel into the internal chamber, a to an inlet port of an injector body associated with the next fuel outlet port for delivering fuel under pressure into an 50 cylinder in the firing order of the motor, may comprise trans associated cylinder, a mixture inlet port and a mixture outlet ferring the combusted mixture via the respective transfer port, and arranged with the mixture inlet port of each injector path. body in fluid communication with the mixture outlet port of The recirculation may occur internally within a cylinder an injector body associated with the immediately preceding head of the motor. Preferably, a pre-mix chamber is associ cylinder in the firing order of the motor; the recirculation 55 ated with each cylinder, and the method comprises delivering system configured to deliver combusted mixture from an combusted mixture under combustion pressure and tempera outlet port of an injector body associated with a cylinder that ture from the pre-mix chamber associated with a cylinder that has just fired to an inlet port of the injector body associated has just fired to the pre-mix chamber associated with the next with the next cylinder in the firing order to at least partly mix cylinder in the firing order. The method preferably comprises with fuel in the internal chamber of that next injector body to 60 delivering mixture for combustion from each pre-mix cham improve the combustion properties of the fuel. ber into the respective cylinder under pressure. The fuel inlet port of each injector body may be configured In a preferred embodiment, the motor may be configured to for receipt of a respective fuel injector. operate in a two-stroke configuration, and the step of deliv Preferably, each mixture inlet port comprises a non-return ering combusted mixture under combustion pressure and valve which allows the mixture to travel into the internal 65 temperature from a cylinder which has just fired to at least chamber through the port but not out of the internal chamber partly mix with fuel for the next cylinder in the firing order through the port. occurs as the piston in said next cylinder is nearing the top of US 7,762,219 B2 5 6 its compression stroke. Preferably the method comprises is visible. This illustrates that the location of the turbocharger delivering from a cylinder on its compression stroke some 308 which is disposed in the engine block 106, is substantially uncombusted air/fuel mixture under relatively low pressure to within the centre of the circularly arranged cylinders 101 the next cylinder in the firing order as said next cylinder is 105. The location of the entire turbocharger 308 is more undergoing its compression stroke. clearly illustrated in FIG. 3. Each cylinder 101-105 has a Preferably, the method comprises delivering some uncom respective opening 111-115 for an injector body of the recir busted mixture from a cylinder as its piston is undergoing a culation system of the present invention to be described compression stroke to a fluid transfer path which provides a below. Apertures 111a-115a are provided for spark plugs or fluid connection between that cylinder and the following cyl other ignition related devices. The block also includes tie inder in the firing order. Such that when combustion occurs in 10 down bolt holes 116-120. the cylinder, the combusted mixture from that cylinder forces FIG. 2 shows the bottom plan view of the axial two-stroke the uncombusted mixture from the transfer path to mix with engine 100. An airchest cover 320 has been removed to reveal fuel for the next cylinder in the firing order. a compression turbine 200 which forms part of the opposite end of the turbocharger 308. Formed between the compres BRIEF DESCRIPTION OF THE DRAWINGS 15 sion turbine 200 and circularly arranged cylinders 101-105 is an air chest 201. The air chest 201 is linked to each cylinder Preferred embodiments of the invention will be described 101-105 by way of transfer passages 202-206. Reed valves with reference to the accompanying drawings in which: 207-211 which are disposed between each transfer passage FIG. 1 is a plan view of an engine block of an axial motor 202-206 and the airchest 201, control the airflow between the which may be used with the recirculation system of the air chest 201 and each transfer passage 202-206. The opera present invention; tion of the air chest 201, reed valves 207-211 and transfer FIG. 2 is a part diagrammatical plan view of the engine passages 202-206 will be described in detail below. block from the opposite end of FIG. 1 with an airchest cover The integral turbocharger 308 arrangement will now be removed, showing a radial compressor; described in more detail with reference to FIG. 3. FIG. 3 FIG. 3 is a section through a multi-cylinder axial engine 25 shows a section view of an engine block 106 with five evenly block showing the turbocharger and one cylinder and part of spaced cylinders 101-105 about an axis 305 of the engine the recirculation system of one embodiment of the present block 106. The section has been taken through A-A shown in invention, on a view through line A-A of FIG. 1; FIG. 1 and illustrates one 101 of the five cylinders 101-105. FIG. 4 is a plan view of the recirculation system in accor Each cylinder 101-105 is substantially identical and there dance with a first preferred embodiment of the present inven 30 fore the description will refer to the visible cylinder 101 tion; however it will be appreciated that the description will extend FIG. 5 is a section through an injector body along line B-B to all the cylinders 101-105 contained within the engine block of FIG. 4; 106. A piston 300 operates in a reciprocal motion within the FIGS. 6a, 6b, and 6c are schematic diagrams showing the cylinder 101. The cylinder 101 has associated with it an sequence of operation of the recirculation system of a pre 35 injector body 401 which forms part of one preferred recircu ferred embodiment of the present invention between three lation system of the present invention. cylinders; and Associated with the piston 300 is a connecting rod 302. A FIG. 7 is a schematic sectional view of part of an engine ball joint 303 disposed at one end of the connecting rod 302 is having a recirculation system in accordance with a second located in an associated socket 304 disposed in a bottom preferred embodiment of the present invention. 40 portion of the piston 300. The reciprocal motion of the piston 300 and connecting rod 302 arrangement in the engine block DETAILED DESCRIPTION OF THE PREFERRED 106 is transferred to rotational motion of an output shaft by EMBODIMENTS any power transmission means Suitable for an axial motor, for example a wobble plate arrangement. FIGS. 1 to 3 show an axial two-stroke motor which may be 45 Within the engine block there is a chamber aligned sub used with the recirculation system of the preferred embodi stantially axially with the longitudinal axis 305 of the engine ment of the present invention. The general motor arrangement block 106. The chamber forms an intake duct 306 and an and operation will be described first. exhaust collector duct 307. The turbocharger 308 is located FIG. 1 shows a top plan view of the axial two-stroke motor within the chamber. The turbocharger 308 is located within which includes an integral turbocharger. The axial two-stroke 50 the engine block 106 substantially in alignmentwith the axis motor or engine 100 includes an engine block 106 preferably 305 so that it is substantially parallel with the length of the formed as an aluminium casting into which have been cylinders 101-105. The turbocharger 308 includes a sub machined a plurality of cylinders 101-105. The cylinders are assembly 309 which supports a rotatable turbine shaft 310, on arranged in a Substantially circular arrangement about alon one end of which is disposed the exhaust turbine 107 and on gitudinal axis 305 of the engine block 106 such that the 55 an opposite end is disposed the compression turbine or radial cylinders are spaced substantially evenly about the axis 305. compressor 200. The longitudinal axis 305 is illustrated in FIG. 3. In the Other features of the turbocharger are described in our PCT preferred embodiment there are five cylinders 101-105 in the Publication No. WO 00/11330, the subject matter of which is motor. More or less cylinders could be provided as is desir incorporated herein by reference. able. 60 Disposed in the wall of the cylinder 101 are one or more The axial-two stroke motor 100 shown includes a turbo exhaust ports 316 which are linked to the exhaust duct307 via charger 308 which is disposed substantially within the engine an exhaust passage 317. Also disposed in the wall of the block 106. Preferably the turbocharger 308 is aligned with the cylinder 101 are one or more inlet ports 319 which are linked axis 305 of the engine block 106 such that it is surrounded by to the air chest 201 via the transfer passage 202 as shown in the evenly spaced cylinders 101-105. 65 FIG. 2. Reed valves 207 disposed between the transfer pas FIG. 1 shows an end view of the turbocharger 308 in which sage 202 and inlets to the air chest 201 control the flow of air an exhaust turbine 107 which forms part of the turbocharger between the airchest 201 and the transfer passage 202. The air US 7,762,219 B2 7 8 chest 201 has an air chest cover 320. A diffusor 321 is formed tion to a source of fuel, and in the embodiment shown between the airchest cover 320 and turbocharger sub-assem includes an aperture 414 into which a fuel injector 416 such as bly 309. shown in FIG. 4 is inserted. Each of the fuel injectors 416 is Operation of the engine will now be described with refer connected to a tube or pipe 418 which will generally be in ence to cylinder 101, however it will be appreciated that each fluid communication with a fuel source and fuel pump (not cylinder is Substantially identical and therefore any descrip shown). The fuel injectors 416 may be conventional electro tion with regard to the cylinder 101 should be considered to magnetic Solenoid valve injectors. extend to the remaining cylinders. The lower part of the injector body includes a fuel outlet The turbocharger is driven by exhaust gases 327 which are port 428 and a nozzle 420 for delivering fuel into an associ expelled from the cylinder 101. During the exhaust phase of 10 ated cylinder. The nozzle 420 preferably includes a restriction the engine cycle, the piston 300 travels downwards within the orifice 422 to deliver fuel underpressure into the cylinder. The cylinder 101 and exposes one or more exhaust ports 316 typical delivery pressure may be in the order of 90 psi (about disposed in the cylinder 101 wall. The exhaust gases 327 from 621 kPa). The aperture 414 and restriction orifice 422 are in the combustion cycle are expelled from cylinder 101 through fluid communication with an internal chamber 424 in the the one or more exhaust ports 316. The exhaust gases 327 pass 15 injector body via a fuel inlet port 426 and a fuel outlet port 428 through the exhaust passage 317, where the exhaust gases 327 respectively. A non-return valve 430 is provided in the fuel pass through the stator 313 which guides the exhaust gases inlet port 426 to allow fuel to be delivered into the internal 327 directly onto the exhaust turbine 107. Once the exhaust chamber 424 through the fuel inlet port 426 and to prevent gases 327 have impacted on the exhaust turbine 107they pass fuel from travelling out through the fuel inlet port 426. The through to the exhaust duct 307. non-return valve 430 is preferably in the form of a ball valve. The rotation of the exhaust turbine 107 rotates the turbine The housing also includes a mixture inlet port 438 which shaft 310 and thus drives the compression turbine 200. The extends into the housing and provides for the delivery of rotating compression turbine 200 draws air 328 through the air/fuel mixture to the internal chamber 424. Again, the mix intake duct306 and passes the compressed air 328through the ture inlet port includes a non-return valve 440 which may be diffusor 321 into the airchest 201. As the piston 300 rises the 25 of the type described above, and which allows mixture to differential pressure opens the reed valves 207 and enables travel into the internal chamber 424 through the mixture inlet the air 328 from the airchest 201 to transfer to the volume 326 port but which also prevents mixture from exiting the housing underneath the piston 300. During the air transfer portion of from the internal chamber 424 via the mixture inlet port. the combustion cycle, the piston 300 travels downwards A mixture outlet port 442 is also provided in the housing within the cylinder 101 which pressurises the air 328 under 30 which allows mixture to travel out of the internal chamber neath the piston, thus closing the reed valves 207. As the 424. Again, the mixture outlet port preferably includes a piston 300 travels further the inlet ports 319 disposed in the non-return valve 444 which may be of the type described wall of the cylinder 101 are exposed. The compressed air 328 above, and which allows mixture to travel out of the housing in the volume 326 underneath the piston 300 is then trans from the internal chamber 424, but which prevents mixture ferred through the transfer passage 202-206 and the one or 35 from travelling back into the internal chamber through the more inlet ports 319 into the cylinder 101. mixture outlet port 442. The fuel inlet port 426, fuel outlet In a further embodiment the engine includes a coolant port 428, mixture inlet port 438 and mixture outlet port 442 jacket 322. The jacket 322 is formed by a combination of the are all in fluid communication with the internal chamber 424. turbocharger sub-assembly 309, inwardly protruding sur The mixture outlet port 442 is preferably of narrower diam faces 314, 315 and engine block 106. The normal coolant 40 eter than the fuel outlet port 428, so there is greater resistance used is water which can be fed into the coolantjacket 322 via to fuel travel through the mixture outlet port 442 than through a coolant entry port 323. The coolant circulates through the the fuel outlet port 428. In the preferred embodiment, the fuel jacket 322 to enable heat dissipation from the turbocharger outlet port 428 and restriction orifice 422 are less restrictive 308. The turbocharger sub-assembly 309 in combination with than any other entry into or exit out of the injector body. the mass of metal comprising the inwardly protruding Sur 45 In some circumstances, it may be desirable to have only a faces 314,315 and engine block 106 provides a sufficient heat single non-return valve between adjacent injector bodies. sink to enable circulating coolant to dissipate heat from the One of the non-return valves could be excluded and instead turbocharger 308 upon cessation of the engine 100 operation. the port could pass directly through. In a particularly pre The dissipation of heat from the turbocharger 308 in this ferred alternative embodiment, one of the non-return valves manner will minimise the likelihood of carbonisation of 50 440, 444 shown in the figures (and preferably the mixture lubricant used within the turbocharger 308. outlet port non-return valve 444) could be replaced with a In a further embodiment a water cooling jacket may Sur spacer having an aperture extending therethrough. The aper round the external portion 400 of exhaust duct 307 to provide ture will substantially align with the port to enable mixture to cooling for turbine shaft 310 and bearing 503. flow through the port. Preferably, the spacer is adjustable or The axial motor is configured with a recirculation system 55 removable and replaceable with a spacer having an aperture in accordance with a first preferred embodiment of the of a different size, to “tune' the port for different fuels. present invention, which has a layout shown more clearly in While the preferred internal chamber 424 is shown as a FIG. 4. The preferred recirculation system is in the form of a Somewhat enlarged region within the injector body, that is not fuel injection system which includes a plurality of injector necessary and the chamber could instead simply be defined bodies 401-405, each of which is mounted in an opening 60 by a junction between the mixture inlet port, mixture outlet 111-115 associated with a respective cylinder 101-105. The port, fuel inlet port and fuel outlet port. injector bodies are configured to deliver gas to, and receive Reverting to FIG. 4, a transfer path which in the embodi gas from, the cylinders. A cross section through one of the ment shown is provided by a pipe, tube or the like 446 is injector bodies 401 is shown in FIG. 5. While only one injec connected between the mixture outlet port 442 of each injec tor body is shown, it should be appreciated that the other 65 tor body and the mixture inlet port of an injector body asso injector bodies will generally have the same features. An ciated with the next cylinder in the firing order. More particu upper part of the injector body 401 is configured for connec larly, a connector 448 on one end of each pipe 446 is US 7,762,219 B2 9 10 connected to the mixture inlet port of a respective injector 438 of the injector body 401 associated with cylinder 101. body, and a connector 450 on the other end of each pipe 446 The pressure in the air/fuel mixture being transferred is is connected to the mixture outlet port of the injector body greater than the pressure in the upper part of the cylinder 101 associated with the immediately preceding cylinder in the at the time, which enables the transfer to take place. Some of firing order. By this manner, the injector bodies are connected 5 the transferred uncombusted mixture will remain in the pipe in a sequential manner around the engine block, which 446. sequence corresponds to the firing order of the motor. The piston 300 in cylinder 102 meanwhile, is on its power As will be described in more detail with reference to FIG. stroke, about 72 degrees behind the piston in cylinder 101. 6, during operation of the motor combusted mixture is deliv Due to the pressure in cylinder 102 being greater than in ered under combustion temperature and pressure via the pipes 10 cylinder 101 and the configuration of the non-return valves in 446, mixture outlet ports 442 and mixture inlet ports 438 to the ports, the mixture from cylinder 105 will be prevented adjacent injector bodies associated with the following cylin from travelling beyond cylinder 101 to cylinder 102. ders in the firing order, to improve combustion properties for Referring now to FIG. 6b, the piston in cylinder 101 is the adjacent cylinders. nearing the top of its compression stroke, the piston in cylin FIG. 4 also shows an air-start valve 452 which is connect 15 der 102 is earlier in its compression stroke, and the piston in able to a source of air for starting the engine. It has been found cylinder 105 is on its power stroke just after combustion. The that it is possible to start the present system using a relatively high pressure in cylinder 105 forces combusted mixture back heavy fuel such as diesel at ambient temperature without up into injector body 405, and that is delivered to the neigh additional heating. During cranking of the engine via the air bouring injector body 401 under combustion temperature and start, the pressurised air from the air start forces the mixture pressure, where it mixes with fuel. As can be seen in FIG. 5, through the recirculation system in Substantially the same due to the fuel outlet port 428 being less restrictive than the way as occurs during normal operation of the engine (as mixture outlet port, the majority of the mixture will travel to described below), however the mixture will not be at such an cylinder 101 rather than 102. Also, the time factor also pre elevated temperature. vents a large amount of the combusted mixture travelling to In FIG. 6, three cylinders 101, 102, 105 of the engine are 25 cylinder 102 at this stage of the process. The combusted shown. As mentioned above, each cylinder has a respective mixture also forces any remaining residual uncombusted fuel injector body 401, 402,405 with a mixture inlet port 438 mixture from the compression stroke in the pipe to the injec and mixture outlet port 442. The mixture outlet port 442 of tor body associated with cylinder 101. Meanwhile, the each injector body is connected to the mixture inlet port 438 upwards movement of the piston in cylinder 101 forces air/ of a neighbouring injector body by a pipe 446. It will be 30 fuel mixture under relatively low pressure into cylinder 102. appreciated that the mixture outlet port 442 of injector body Referring now to FIG. 6c, cylinder 101 has just undergone 402 will be influid communication with the mixture inlet port combustion (which occurs just before top dead centre), and its 438 of injector body 403, and the mixture outlet port 442 of piston 300 is on the power stroke. The piston in cylinder 102 injector body 404 will be in fluid communication with the meanwhile is nearing the top of its compression stroke, and mixture inlet port 438 of injector body 405. 35 the piston in cylinder 105 is further through its power stroke. The motoris configured Such that the cylinders fire sequen Following combustion of the mixture in the cylinder 101, tially around the motor. As this embodiment of axial motor combusted mixture under combustion pressure and tempera has five cylinders, the pistons will be sequentially operating ture is delivered to the injector body 402 associated with 72 degrees behind one another. cylinder 102, and will mix with the fuel in that injector 402 In the position shown in FIG. 6a, the piston 300 in cylinder 40 prior to combustion. Meanwhile, relatively low pressure air/ 101 is moving downwards towards bottom dead centre, and fuel mixture will be delivered from injector body 402 to the the injector body 401 is delivering fuel into the cylinder. injector body 403 associated with cylinder 103 due to the Generally speaking, in the preferred embodiment fuel injec compression movement of the piston in cylinder 102. tion would start when the piston is about 19 degrees before Typical combustion pressures which may occur in an axial bottom dead centre, but it will be appreciated that that would 45 motor of this type are in the order of about 600 psi to about be variable to obtain the desired firing properties. As the 100 psi (about 4137 KPa to about 6895 KPa). exhaust port 316 is open a vacuum is created above the piston, Meanwhile, there will be higher pressure in cylinder 105 which assists in drawing fuel in from the injector body 401. than in cylinder 104 due to relatively recent combustion in The downward movement is also forcing pressurised air into cylinder 105; therefore no mixture will be delivered from the upper part of the cylinder from the volume below the 50 cylinder 104 to cylinder 105 in the position shown in FIG. 6c. cylinder via the inlet ports 319, as described above with It will be appreciated that while only three cylinders are reference to FIG. 3. That air is effectively supercharged, due shown here, the procedure will continue in a sequential man to the pressure provided by the piston movement. The fuel ner around the engine block. The same amount of fuel can be from the injector body is mixed with the air which has entered delivered to each injector body by the injectors, but the sys the upper part of the cylinder from the inlet ports 319. 55 tem will equalise the delivery of mixture and fuel as necessary Meanwhile, the piston 300 in cylinder 105 is on its com around the engine. pression stroke, and the inlet and exhaust ports of that cylin It will be appreciated from the above description that a der are closed. The compression movement applies pressure stratified combusted mixture is transferred under high pres to the uncombusted air/fuel mixture in the region above the Sure and temperature, along with some residual uncombusted piston 300 which drives some air/fuel mixture into the inter 60 mixture, to a neighbouring injector body and mixed with a nal chamber 424 in the injector body 405. Due to the non combustible mixture under compression pressure as that cyl return valve 440 in the mixture inlet port 438 of injector body inder nears its firing position, to assist in atomising and dis 405 preventing mixture from exiting via the mixture inlet port tributing that combustible mixture in the cylinder. 438, as well as the non-return valve 430 preventing mixture It has also been found that during combustion in a cylinder, from exiting via the fuel inlet port, the mixture is forced under 65 if piston rings are not used, then part of the combusted charge relatively low pressure through the mixture outlet port 442 of will travel down the sides of the piston. This assists in reduc the injector body 405 and pipe 446 into the mixture inlet port ing the friction associated with piston movement, which is US 7,762,219 B2 11 12 particularly useful if non-metallic pistons such as carbon Rather than using the inlet ports 319 and exhaust ports 316 pistons are to be used for example. The amount of combusted as shown, the engine could have conventional intake and mixture being transferred to an adjacent cylinder is dependent exhaust valves for each cylinder. on the combustion pressure, which is a product of the amount Rather than providing the interconnection between injector of fuel delivered into the cylinderprior to combustion. There 5 bodies for transfer of combusted mixture, the transfer could fore, the properties can be adjusted by altering the amount of occur substantially within the cylinder head of the motor. For fuel delivered to each cylinder by the respective injector and example, the part of the cylinder head associated with the tops injector body. Further, the lengths of the pipes or tubes 446 of each cylinder could have ports at or adjacent the tops of the can be adjusted to “tune” the properties of the fuel injection cylinders. These ports could be interconnected via internal system. If longer pipes or tubes 446 are used there will be 10 transfer paths such as internal channels. In one embodiment, greater delay in delivery of the combusted mixture to the a pre-mix chamber is provided at the top of each cylinder, and adjacent injector body, whereas if shorter pipes or tubes are the motor includes transfer paths. Such as internal channels used there will be less delay in delivery of the combusted which are configured to deliver combusted mixture under mixture to the adjacent injector body. combustion temperature and pressure from the pre-mix By delivering combusted mixture under combustion tem 15 chamber associated with a cylinder that has just fired to the perature and pressure from one cylinder to a following cylin pre-mix chamber associated with the next cylinder in the der, the combustion properties have been found to improve. firing order. Each pre-mix chamber may have a mixture inlet The combusted mixture slows the flame travel and retards port, a mixture outlet port, an aperture or port for receipt of ignition in the following cylinder in the firing order. That fuel from a fuel injector, and a fluid path into the cylinder enables higher compression ratios to be used with heavy fuels which preferably includes a nozzle or restriction to deliver such as diesel hydrocarbon fuel, with reduced “knocking or mixture for combustion into the respective cylinder under auto-ignition. Further, the elevated temperature and pressure pressure. The spark plug(s) associated with each cylinder are of the combusted mixture picks up fuel in the adjacent injec preferably present in the cylinder itself rather than in the tor body and atomises the fuel prior to its delivery into the pre-mix chamber, so that the combustion occurs in the cylin cylinder, again improving combustion properties for that cyl 25 der and then forces combusted mixture back up into the inder. This is particularly useful when using heavy fuels such pre-mix chamber and to the pre-mix chamber associated with as diesel. However, the preferred embodiment systems are the next cylinder in the firing order via the transfer path. The also useful with light fuels such as petrol. operation will generally be the same as described above. For example, with an axial motor having a configuration Such a system is shown schematically in FIG. 7. Unless shown in FIGS. 1 to 3 and including a preferred embodiment 30 described otherwise, the functioning and features in the sys recirculation system, the maximum compression ratio (the tem of FIG. 7 should be considered to be the same as in the volume of the cylinder above the piston at bottom-dead systems described above, and like reference numerals are centre divided by the Volume of the cylinder above the piston used to indicate like parts, with the addition of 1000. at top-dead-centre) at which useful combustion of diesel 35 FIG. 7 shows three cylinders 1105, 1101, 1102 of a pre could occur was about 8:1. At higher compression ratios, the ferred embodiment engine 1100. The cylinders are located in piston was burning out due to detonation/auto-ignition. With an engine block 1106. A piston 1300 is reciprocably mounted a system incorporating a preferred embodiment recirculation in each cylinder. A cylinder head 106a is mounted to the system, it has been found that useful combustion of diesel can occur at compression ratios of between 9:1 and 10:1 without engine block, and in the embodiment shown has a pre-mix 40 chamber 1105a, 1101a, 1102a associated with each cylinder. any significant detonation, and it may be possible to achieve A fuel injector 416 is mounted in an aperture in the top of each compression ratios of up to 10.5:1-11:1. Generally, improved pre-mix chamber 1105.a. 1101a, 1102a. Each pre-mix cham engine performance is achieved with a higher compression ber has a mixture inlet port 1438 and a mixture outlet port ratio, provided there is not excessive detonation. 1442. A non-return valve 1440 is positioned between the The above describes a preferred embodiment of the present 45 mixture outlet port 1442 of each one of the pre-mix chambers invention, and modifications may be made thereto without and the mixture inlet port of the pre-mix chamber associated departing from the scope of the invention. For example, while with the following cylinder in the firing order. An aperture or the motor is described as being a two-stroke axial motor, it nozzle 1422 provides fluid communication between each cyl could alternatively be a four-stroke axial motor. In that case, inder and its respective pre-mix chamber. Within each cylin air/fuel mixture would be delivered from a cylinder to an 50 der, an aperture 1111a, 1112a, 1113a, 1114a is provided for adjacent cylinder under relatively low pressure during the receipt of a spark plug (not shown), and is preferably in the compression stroke, and under higher pressure immediately vicinity of the respective aperture or nozzle 1422. If neces following combustion. sary, a non-return valve can be provided between each fuel Further, the motor may be an in-line, vee, or horizontally injector 416 and its respective pre-mix chamber to prevent opposed (“boxer) configuration two- or four-stroke internal 55 combusted mixture from entering the fuel injector. combustion motor, or a rotary engine. In use, combusted mixture from a cylinder which has just It will be appreciated that the recirculation system need not fired is forced back up into the pre-mix chamber associated be used in conjunction with an internal turbocharger, and it with that cylinder. Due to the configurations of the non-return will work Successfully with a normally aspirated engine. Fur valves 1440, the combusted mixture exits that pre-mix cham ther, the fuel injection system could be used in an axial motor 60 ber via the mixture outlet port and enters the pre-mix chamber having opposed pistons, such as that described in our PCT associated with the next cylinder in the firing order. That publication number WO 03/010417. It will be appreciated combusted mixture mixes with and atomises fuel from the that if a fuel injection system is used with both banks of fuel injector 416 and enters the cylinder which is about to fire. pistons in the opposed piston motor, the configuration of That mixture is then combusted by the spark plug, and com valves between the injectors in one bank will be the opposite 65 busted mixture is forced back up into the pre-mix chamber to the other bank, so that overall the sequence of operation and delivered to the following pre-mix chamber in the same will be in the same direction for both banks. manner described above. That process will continue around US 7,762,219 B2 13 14 the cylinders of the engine in the firing order. While three injector body with the mixture outlet port of the injector body cylinders are shown, it will be appreciated that the engine may associated with the immediately preceding cylinder in the have more cylinders. firing order. It is preferred that the injector bodies and external transfer 8. A motor as claimed in claim 7, wherein the transfer paths paths are used, as they can more be easily dismantled for comprise pipes or tubes. cleaning. 9. A motor as claimed in claim 1, wherein the motor is an The invention claimed is: axial motor. 1. A motor comprising: an engine block with three or more 10. A motor comprising: an engine block with three or cylinders arranged to fire with a firing order, a fuel injector more cylinders arranged to fire with a firing order; a fuel associated with each cylinder; and a recirculation system 10 injector associated with each cylinder, and a recirculation comprising fluid transfer paths which are arranged to provide system comprising fluid transfer paths which are arranged to a fluid connection between cylinders sequentially in the firing provide a fluid connection between cylinders sequentially in order of the motor, the motor configured such that combustion the firing order of the motor, the motor configured such that in a cylinder creates a combusted mixture having a combus combustion in a cylinder creates a combusted mixture having tion pressure, which combustion pressure forces some of that 15 a combustion pressure, which combustion pressure forces combusted mixture to at least partly mix with fuel for the next some of that combusted mixture to at least partly mix with cylinder in the firing order to improve the combustion prop fuel for the next cylinder in the firing order to improve the erties of the fuel, and to deliver a mixture of the combusted combustion properties of the fuel, and to deliver a mixture of mixture and fuel under elevated temperature and pressure into the combusted mixture and fuel under elevated temperature said next cylinder in the firing order. and pressure into said next cylinder in the firing order, 2. A motor comprising: an engine block with three or more wherein the recirculation system is arranged substantially cylinders arranged to fire with a firing order, a fuel injector internally within a cylinder head of the motor. associated with each cylinder; and a recirculation system 11. A motor as claimed in claim 10, wherein the cylinder comprising fluid transfer paths which are arranged to provide head comprises a pre-mix chamber associated with each cyl a fluid connection between cylinders sequentially in the firing 25 inder, and the cylinder head includes transfer paths config order of the motor, the motor configured such that combustion ured to deliver combusted mixture under combustion pres in a cylinder creates a combusted mixture having a combus Sure and temperature from the pre-mix chamber associated tion pressure, which combustion pressure forces some of that with a cylinder that has just fired to the pre-mix chamber combusted mixture to at least partly mix with fuel for the next associated with the next cylinder in the firing order. cylinder in the firing order to improve the combustion prop 30 12. A motor as claimed in claim 11, wherein each transfer erties of the fuel, and to deliver a mixture of the combusted path comprises at least one non-return valve configured to mixture and fuel under elevated temperature and pressure into allow combusted mixture under combustion pressure and said next cylinder in the firing order, wherein each cylinder temperature to be delivered to the pre-mix chamber associ has an injector body associated therewith, with each injector ated with the next cylinder in the firing order. body having an internal chamber in communication with a 35 13. A motor as claimed in claim 11, wherein a fluid path is fuel inlet port for delivering fuel into the internal chamber, a provided between each pre-mix chamber and the respective fuel outlet port for delivering fuel under pressure from the cylinder. chamber into the associated cylinder, a mixture inlet port and 14. A motor as claimed in claim 13 wherein each fluid path a mixture outlet port, with the mixture inlet port of each comprises a nozzle to deliver mixture for combustion into the injector body in fluid communication with the mixture outlet 40 respective cylinder under pressure. port of an injector body associated with the immediately 15. A motor comprising: an engine block with three or preceding cylinder in the firing order of the motor, the motor more cylinders arranged to fire with a firing order; a fuel configured to deliver combusted mixture under combustion injector associated with each cylinder, and a recirculation pressure and temperature from an outlet port of an injector system comprising fluid transfer paths which are arranged to body associated with a cylinder that has just fired to an inlet 45 provide a fluid connection between cylinders sequentially in port of an injector body associated with the next cylinder in the firing order of the motor, the motor configured such that the firing order of the motor to at least partly mix with fuel in combustion in a cylinder creates a combusted mixture having the internal chamber of the injector body associated with said a combustion pressure, which combustion pressure forces next cylinder in the firing order to improve the combustion some of that combusted mixture to at least partly mix with properties of the fuel. 50 fuel for the next cylinder in the firing order to improve the 3. A motor as claimed in claim 2, wherein the fuel inlet port combustion properties of the fuel, and to deliver a mixture of of each injector body is configured for receipt of a respective the combusted mixture and fuel under elevated temperature fuel injector. and pressure into said next cylinder in the firing order, 4. A motor as claimed in claim 2, wherein each mixture wherein the motor is configured to operate in a two-stroke inlet port comprises a non-return valve which allows the 55 configuration and wherein the motor is configured Such that mixture to travel into the internal chamber through the port the combusted mixture is delivered to at least partly mix with but not out of the internal chamber through the port. the fuel for the next cylinder in the firing order as the piston in 5. A motor as claimed in claim 2, wherein each mixture said next cylinder is nearing the top of its compression stroke. outlet port comprises a non-return valve which allows mix 16. A motor as claimed in claim 15, wherein the motor is ture to travel out of the internal chamber through the port but 60 configured Such that when a cylinder is on its compression not into the internal chamber through the port. stroke, some uncombusted air/fuel mixture is delivered under 6. A motor as claimed in claim 2, wherein each fuel inlet relatively low pressure to the next cylinder in the firing order port comprises a non-return valve which allows fuel to flow said next cylinder is undergoing its compression stroke. into the internal chamber through the fuel inlet port, but not 17. A motor comprising: an engine block with three or out of the internal chamber through the fuel inlet port. 65 more cylinders arranged to fire with a firing order; a fuel 7. A motor as claimed in claim 2, whereintransfer paths are injector associated with each cylinder, and a recirculation provided to fluidly connect the mixture inlet port of each system comprising fluid transfer paths which are arranged to US 7,762,219 B2 15 16 provide a fluid connection between cylinders sequentially in with a firing order, and a fuel injector associated with each the firing order of the motor, the motor configured such that cylinder, comprising delivering a combusted mixture under combustion in a cylinder creates a combusted mixture having combustion pressure and temperature from a cylinder which a combustion pressure, which combustion pressure forces has just fired to at least partly mix with fuel for the next some of that combusted mixture to at least partly mix with cylinder in the firing order to improve the combustion prop fuel for the next cylinder in the firing order to improve the erties of the fuel, and delivering a mixture of the combusted combustion properties of the fuel, and to deliver a mixture of mixture and fuel under elevated temperature and pressure into the combusted mixture and fuel under elevated temperature said next cylinder in the firing order. and pressure into said next cylinder in the firing order, 27. A method of enhancing combustion in a motor having wherein the motor is configured to deliver some uncombusted 10 an engine block with at least three cylinders arranged to fire mixture from a cylinder as its piston is undergoing a com with a firing order, and a fuel injector associated with each pression stroke to a fluid transfer path which provides a fluid cylinder, comprising delivering a combusted mixture under connection between that cylinder and the following cylinder combustion pressure and temperature from a cylinder which in the firing order, such that when combustion occurs in the has just fired to at least partly mix with fuel for the next cylinder, the combusted mixture from that cylinder forces the 15 cylinder in the firing order to improve the combustion prop uncombusted mixture from the transfer path to mix with fuel erties of the fuel, and delivering a mixture of the combusted for the next cylinder in the firing order. mixture and fuel under elevated temperature and pressure into 18. A recirculation system for a motor having three or more said next cylinder in the firing order, wherein each cylinder cylinders arranged to fire with a firing order, comprising: a has an injector body associated therewith, with each injector plurality of fuel injector bodies, each injector body having an body having an internal chamber in communication with a internal chamber in communication with a fuel inlet port for fuel inlet port for delivering fuel into the internal chamber, a delivering fuel into the internal chamber, a fuel outlet port for fuel outlet port for delivering fuel under pressure from the delivering fuel under pressure into an associated cylinder, a chamber into the associated cylinder, a mixture inlet port and mixture inlet port and a mixture outlet port, and arranged with a mixture outlet port, with the mixture inlet port of each the mixture inlet port of each injector body in fluid commu 25 injector body in fluid communication with the mixture outlet nication with the mixture outlet port of an injector body port of an injector body associated with the immediately associated with the immediately preceding cylinder in the preceding cylinder in the firing order of the motor; and firing order of the motor; the recirculation system configured wherein the method comprises delivering combusted mixture to deliver combusted mixture from an outlet port of an injec under combustion pressure and temperature from an outlet tor body associated with a cylinder that has just fired to an 30 port of an injector body associated with a cylinder that has just inlet port of the injector body associated with the next cylin fired to an inlet port of an injector body associated with the der in the firing order to at least partly mix with fuel in the next cylinder in the firing order of the motor to at least partly internal chamber of that next injector body to improve the mix with fuel in the internal chamber of that adjacent injector combustion properties of the fuel, and to deliver a mixture of to improve the combustion properties of the fuel. the combusted mixture and fuel under elevated temperature 35 28. A method as claimed in claim 27, wherein transfer and pressure from the fuel outlet port of said injector body paths are provided to link the mixture outlet port of each associated with the next cylinder in the firing order. injector body with the mixture inlet port of the injector body 19. A recirculation system as claimed in claim 18, wherein associated with the next cylinder in the firing order and the the fuel inlet port of each injector body is configured for step of delivering combusted mixture under combustion pres receipt of a respective fuel injector. 40 Sure and temperature from an outlet port of an injector body 20. A recirculation system as claimed in claim 18, wherein associated with a cylinder that has just fired to an inlet port of each mixture inlet port comprises a non-return valve which an injector body associated with the next cylinder in the firing allows the mixture to travel into the internal chamber through order of the motor, comprises transferring the combusted the port but not out of the internal chamber through the port. mixture via the respective transfer path. 21. A recirculation system as claimed in claim 18, wherein 45 29. A method of enhancing combustion in a motor having each mixture outlet port comprises a non-return valve which an engine block with at least three cylinders arranged to fire allows mixture to travel out of the internal chamber through with a firing order, and a fuel injector associated with each the port but not into the internal chamber through the port. cylinder, comprising delivering a combusted mixture under 22. A recirculation system as claimed in claim 18, wherein combustion pressure and temperature from a cylinder which each fuel inlet port comprises a non-return valve which allows 50 has just fired to at least partly mix with fuel for the next fuel to flow into the internal chamber through the fuel inlet cylinder in the firing order to improve the combustion prop port, but not out of the internal chamber through the fuel inlet erties of the fuel, and delivering a mixture of the combusted port. mixture and fuel under elevated temperature and pressure into 23. A recirculation system as claimed in claim 18, wherein said next cylinder in the firing order, wherein the step of the mixture outlet port of each injector body is fluidly con 55 delivering the combusted mixture under combustion pressure nected to the mixture inlet port of the injector body associated and temperature to at least partly mix with fuel for the next with the next cylinder in the firing order of the motor by a cylinder in the firing order occurs internally within a cylinder transfer path. head of the motor. 24. A recirculation system as claimed in claim 23, wherein 30. A method as claimed in claim 29, wherein a pre-mix each transfer path comprises a pipe or tube. 60 chamber is associated with each cylinder, and the method 25. A recirculation system as claimed in claim 18, config comprises delivering combusted mixture under combustion ured such that the combusted mixture at least partly atomises pressure and temperature from the pre-mix chamber associ the fuel in the internal chamber to which the combusted ated with a cylinder that has just fired to the pre-mix chamber mixture has been delivered under combustion pressure and associated with the next cylinder in the firing order. temperature. 65 31. A method as claimed in claim 30, comprising deliver 26. A method of enhancing combustion in a motor having ing mixture for combustion from each pre-mix chamber into an engine block with at least three cylinders arranged to fire the respective cylinder under pressure. US 7,762,219 B2 17 18 32. A method of enhancing combustion in a motor having 34. A method of enhancing combustion in a motor having an engine block with at least three cylinders arranged to fire an engine block with at least three cylinders arranged to fire with a firing order, and a fuel injector associated with each with a firing order, and a fuel injector associated with each cylinder, comprising delivering a combusted mixture under cylinder, comprising delivering a combusted mixture under combustion pressure and temperature from a cylinder which 5 combustion pressure and temperature from a cylinder which has just fired to at least partly mix with fuel for the next has just fired to at least partly mix with fuel for the next cylinder in the firing order to improve the combustion prop cylinder in the firing order to improve the combustion prop erties of the fuel, and delivering a mixture of the combusted erties of the fuel, and delivering a mixture of the combusted mixture and fuel under elevated temperature and pressure into mixture and fuel under elevated temperature and pressure into said next cylinder in the firing order, wherein the motor is 10 configured to operate in a two-stroke configuration, and the said next cylinder in the firing order, the method further step of delivering combusted mixture under combustion pres comprising delivering some uncombusted mixture from a Sure and temperature from a cylinder which has just fired to at cylinder as its piston is undergoing a compression stroke to a least partly mix with fuel for the next cylinder in the firing fluid transfer path, which provides a fluid connection between order occurs as the piston in said next cylinder is nearing the 15 that cylinder and the following cylinder in the firing order, top of its compression stroke. Such that when combustion occurs in the cylinder the com 33. A method as claimed in claim 32, comprising deliver busted mixture from that cylinder forces the uncombusted ing from a cylinder on its compression stroke some uncom mixture from the transfer path to mix with fuel for the next busted air/fuel mixture under relatively low pressure to the cylinder in the firing order. next cylinder in the firing order as said next cylinder is under going its compression stroke.