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    • 专利摘要:
    A method of supplying fuel to an engine, including combining a first fuel and a second fuel to form combined fuel; supplying the combined fuel to the engine; and varying the rate at which the combined fuel is supplied to the engine to suit the relative 5 proportions of the first fuel and the second fuel in the combined fuel. Vehicle ECU 14 I njector Steering Controls A 16 .;t U Vehicle LCD Pressure sensor High Pressur 30F ~ Pump -J 141 Return lock --- Pump PowerRtuRIfin --------- Petrol Supply lock z LPG Supply lock S 32 Mixing Unit retum line Petrol Boost powerL -- Mixing Unit LPG Supply -Petrol Boost I CV PGFiller up- 3 Tank ----- -- J Petrol Tak 20 30 FIGURE 1
    公开号:AU2013203207A1
    申请号:U2013203207
    申请日:2013-04-09
    公开日:2014-06-26
    发明作者:Benjamin Lee
    申请人:YAPP AUSTRALIA AUTOMOTIVE SYSTEMS Pty Ltd；
    IPC主号:F02D19-08
    专利说明:
    P1057AUAU FUEL SUPPLY FIELD The invention relates to engines and vehicles, which for example may be operable on two or more fuels, and to components, component systems and methods therefor. 5 The invention will be described with reference to a retro-fit fuel system for modifying a vehicle, wherein the unmodified vehicle includes a direct injection engine configured to run on petroleum, and the system modifies the vehicle to operate also on a low boiling point fuel. The invention will also be described with reference to a mono-fuel vehicle. The invention is not so limited. By way of example, the invention may be embodied in a 10 stationary engine employing conventional carburetion and configured to consume two fuels, neither of which is a low boiling point fuel. "Retro-fit" refers to adding to and/or modifying that which is already fully operational (i.e. adding and/or modifying "original equipment"). Low boiling point fuels such as liquid petroleum gas (LPG), propane and butane are gaseous at normal atmospheric 15 conditions, in contrast to other fuels such as petroleum which are liquids when exposed to the same conditions. "Direct injection" refers to the injection of fuel directly into the combustion chamber(s) (e.g. cylinder bores) of an engine as opposed to conventional injection in which fuel is injected at some point along the air intake path so as to mix with the incoming charge of air before entering the combustion chamber(s). 20 BACKGROUND In the past, vehicles configured to consume petroleum and including injectors arranged to spray fuel into the air inlet path have been modified to operate also on LPG by adding additional injectors to spray the LPG into the air inlet path. Accordingly, vehicles so modified have a dedicated set of LPG injectors potentially alongside a dedicated set of P1057AUAU 2 petroleum injectors. Alternatively such vehicles have been modified by replacing the injectors with LPG injectors to run only on LPG. Recently vehicle manufacturers have moved to direct injection for various reasons. A lack of space makes it difficult or impossible to add dedicated LPG injectors to such 5 engines. Moreover, most new direct-injection engines incorporate "lean burn" technology in which a very localised stoichiometric mixture of air and fuel is sprayed close to the ignition source (e.g. spark plug). This spray ignites and then rapidly cools as it reaches a "non-combustible area" within the combustion chamber. In "lean burn" engines the position at which fuel is injected is critical. If the same quantity of fuel was injected into 10 the inlet manifold it would not create the localised stoichiometric mixture, but would rather create a chamber full of a lean mixture. Conveniently, the injectors of a direct injection system supply fuel at much higher pressures than in other systems. Conveniently these pressures are high enough that LPG can be supplied to the original equipment injector and remain in its liquid state until 15 it is atomised at the injector nozzle. Accordingly, the original equipment petroleum injectors have been used to inject LPG. The inventor has recognised various difficulties with this approach. Petroleum and LPG have different combustion characteristics. This leads to difficulties in effecting a smooth transition from one fuel to the other. LPG is more inclined to vaporise than petroleum. 20 This leads to unwanted vapour at various points in the fuel system from time to time. Having specific components for these and other problems leads to additional design and inventory costs. At least preferred forms of various aspects of the invention aim to provide improvements in and for vehicles and engines, or at least to provide alternatives for those concerned 25 with engines and/or vehicles. It is not admitted that any of the information in this patent specification is common general knowledge, or that the person skilled in the art could be reasonably expected to P1057AUAU 3 ascertain or understand it, regard it as relevant or combine it in any way at the priority date. SUMMARY One aspect of the invention provides a method, of supplying fuel to an engine, including 5 combining a first fuel and a second fuel to form combined fuel; supplying the combined fuel to the engine; and varying the rate at which the combined fuel is supplied to the engine to suit the relative proportions of the first fuel and the second fuel in the combined fuel. The combining, supplying and varying may be during switching 10 from supplying to the engine one of the first fuel and the second fuel; to supplying to the engine the other of the first fuel and the second fuel. Preferably in substance the combining includes supplying the other fuel to a control volume containing the one fuel, in which case the varying the rate at which the combined fuel is supplied is preferably varying as a function of an indication of an 15 amount of combined fuel supplied from the control volume. The indication may be or include a control signal to, or feedback signal from, one or more fuel injectors. The varying preferable includes intercepting and modifying an input signal to a control system controlling the rate at which fuel is supplied. By way of example, the input signal may correspond to a pressure at which fuel is delivered to fuel injector(s). 20 Optionally the first fuel is petroleum and/or the second fuel is a low boiling point fuel. The engine may be driving a vehicle.
    P1057AUAU 4 Another aspect of the invention provides a fuel system for supplying fuel to an engine system; the engine system including an engine; the fuel system including 5 a fuel tank; a vessel including one or more inlets for receiving into the vessel, from a fuel supply, a first fuel and, from the fuel tank, a second fuel; an outlet for dispatching from the vessel fuel to the engine system; and 10 a control system configured to vary the rate at which the dispatched fuel is supplied to the engine to suit the relative proportions of the first fuel and the second fuel in the dispatched fuel. The fuel system preferable includes a flow control arrangement responsive to the control system to control the receipt of the first fuel and the second fuel via the one or more 15 inlets. Preferably the control system is configured to, when switching from one of the first fuel and the second fuel to the other of the first fuel and the second fuel, cause the other fuel to be received via the inlet(s) to, within the vessel, combine with the one fuel. By way of example, the flow control arrangement may include an electromechanical valve for selectively communicating the fuel supply with the vessel, and/or an 20 electromechanical valve for selectively communicating the fuel tank with the vessel. The control system is preferably configured to vary the rate at which the fuel is supplied to the engine by influencing the engine system. By way of example, the control system may be configured to intercept and modify a data signal of the engine system to so P1057AUAU 5 influence the engine system. The data signal may correspond to a pressure at which fuel is delivered to fuel injector(s). The vessel may include a further inlet for receiving fuel returning from the engine system, in which case the fuel system preferably includes an electromechanical valve 5 responsive to the control system to selectively direct the returning fuel to the fuel tank. The vessel may internally carry a pump for driving fluid through the outlet. The fuel system is preferably in a vehicle wherein the engine is arranged to drive the vehicle. Another aspect of the invention provides the fuel system and the engine system. 10 Another aspect of the invention provides a vehicle including the fuel system and the engine system. Another aspect of the invention provides a pump, for pumping fuel to injector(s) of a direct injection engine, including an inlet for receiving the fuel from a fuel supply; 15 a first outlet for conveying the received fuel toward the injector(s); one or more dynamic components for driving the received fuel from the inlet to the first outlet; and a second outlet, upstream of the dynamic components, for conveying the received fuel toward the fuel supply. 20 The pump is preferably a positive displacement pump. The dynamic components may be gears.
    P1057AUAU 6 Another aspect of the invention provides a fuel system, for supplying a low boiling point fuel to a direct injection engine, including the pump; and conduit connecting the fuel supply to the inlet, and conduit connecting the second outlet 5 to the fuel supply, to define a fluid circuit; and a second pump for driving the fuel about the fluid circuit. The fuel system preferably includes a control system to control the pump; wherein the control system is configured to 10 receive an indication of a person interacting with a dormant vehicle; and before the person gives an input to start the engine, activate the pump in response to the indication. Another aspect of the invention provides a fuel system, for supplying fuel to an engine of vehicle, including 15 conduit for conveying the fuel toward the engine; a pump for driving the fuel along the conduit; a control system to control the pump; wherein the control system is configured to receive an indication of a person interacting with a dormant vehicle; and P1057AUAU 7 before the person gives an input to start the engine, activate the pump in response to the indication. The indication may be associated with the one or more doors of the vehicle being at least one of unlocked and opened. 5 Another aspect of the invention provides a fuel system, for supplying fuel to an engine of vehicle, including conduit for conveying the fuel toward the engine; a pump for driving the fuel along the conduit; a control system to control the pump; 10 wherein the control system is configured to activate the pump in response to one or more doors of the vehicle being at least one of unlocked and opened. Another aspect of the invention provides a vehicle, operable on at least one low boiling point fuel, including 15 a direct injection engine from specifications of an existing vehicle operable on petroleum; a fuel tank from specifications of an existing vehicle operable on low boiling point fuel; a fuel system for conveying the low boiling point fuel from the fuel tank to the engine. The specifications of the existing vehicle operable on petroleum may include a 20 petroleum supply tube, in which case the vehicle preferably includes the petroleum supply tube arranged to convey the low boiling point fuel away from the fuel tank.
    P1057AUAU 8 Preferably the specifications of the existing vehicle operable on petroleum include a flexible petroleum supply hose under its bonnet; and the vehicle includes a high pressure hose in place of the flexible petroleum supply hose. Optionally the specifications of the existing vehicle operable on petroleum include a 5 steel pipe connecting a vapour purge canister to a purge solenoid; and the vehicle includes the steel pipe arranged to convey the low boiling point fuel towards the tank. Flexible hose may connect the steel pipe to the fuel tank. The specifications of the existing vehicle operable on low boiling point fuel may include a 10 tank pressure sensor, in which case the vehicle preferably includes a return line fitting in place of the tank pressure sensor. The return line fitting may include a one way valve. The specifications of the existing vehicle operable on low boiling point fuel may include a return-less pressure regulator, in which case the vehicle preferably includes in place of the return-less pressure regulator a regulator connected to an internal side of the return 15 line fitting. Optionally, the regulator connected to an internal side of the return line fitting is in substance a 5 bar regulator. Another aspect of the invention provides a method, of manufacturing a pump for pumping low boiling point fuel to injector(s) of a direct injection engine, including 20 modifying a pump for pumping fuel to an engine; the pump for pumping fuel including an inlet for receiving fuel from a fuel supply; P1057AUAU 9 an outlet for conveying the received fuel toward the injector(s); one or more dynamic components for driving the received fuel from the inlet to the outlet; and the method including creating a second outlet, upstream of the dynamic components, for 5 conveying the received fuel toward a fuel supply. The creating the second outlet may include or consist of drilling a hole in a housing of the pump. Another aspect of the invention provides a method of modifying an engine system the engine system including an engine and a pump for driving fuel toward the engine; the pump including a housing, housing dynamic components for so driving the fuel; 10 the method including creating an opening in the housing to convey heated fuel away from the pump. Another aspect of the invention provides a method, of readying an engine of a dormant vehicle for activation, including before a person gives an input to start the engine, activating a pump in response to an indication of the person interacting with the dormant 15 vehicle. The indication is preferably associated with the one or more doors of the vehicle being at least one of unlocked and opened. Another aspect of the invention provides a method of designing a vehicle; the vehicle having a direct injection engine and being operable on at least one low 20 boiling point fuel; the method in substance including P1057AUAU 10 selecting a direct injection engine from specifications of an existing vehicle operable on petroleum; selecting a fuel tank from specifications of another existing vehicle operable on an or the low boiling point fuel; 5 specifying a fuel system for conveying low boiling point fuel from the fuel tank to the engine. Another aspect of the invention provides a method of manufacturing a vehicle, the vehicle including a direct injection engine and being operable on low boiling point fuel; 10 the method including modifying an existing vehicle having a direct injection engine and being operable on petroleum; the modifying including; fitting a fuel tank for containing the low boiling point fuel; and connecting conduit to convey fuel from the fuel tank to the engine. 15 Another aspect of the invention provides a method, of readying an engine of a dormant vehicle for activation, including activating a pump in response to one or more doors of the vehicle being at least one of unlocked and opened. Another aspect of the invention provides a vehicle, operable on at least one low boiling point fuel, including 20 a direct injection engine; a fuel tank for containing the low boiling point fuel; P1057AUAU 11 a fuel system for conveying the low boiling point fuel from the fuel tank to the engine; and a steel pipe arranged to convey the low boiling point fuel from the engine towards the tank. 5 Preferably flexible hose connects the steel pipe to the fuel tank. Another aspect of the invention provides a method of defining a return line in a vehicle the vehicle including a direct injection engine and being operable on at least one low boiling point fuel; the method including connecting a steel pipe to convey towards a fuel tank low boiling 10 point fuel from the engine. The method preferably includes installing flexible hose to connect the steel pipe to the fuel tank. BRIEF DESCRIPTION OF DRAWINGS The figures illustrate various exemplary features. 15 Figure 1 schematically illustrates selected components of a vehicle. Figure 2 is an exploded view of a mixing vessel and its flow control arrangements. Figure 3 is a cross-section view of a petroleum inlet and associated flow control arrangement. Figure 4 is an electronics diagram for the components of Figure 1. 20 Figure 5 is a perspective view of a fuel pump.
    P1057AUAU 12 Figure 6 is a chart of vaporisation pressures. Figure 7 schematically illustrates selected components of another vehicle. DESCRIPTION OF EMBODIMENTS Figure 1 schematically illustrates selected components of a vehicle's original equipment 5 engine system 10 along with a fuel supply, in the form of the original equipment petroleum tank 2, and selected components of a retro-fit fuel system 30. The fuel system 30 allows the vehicle to run on LPG. The engine system 10 includes amongst other things pump 11, pressure sensor 12, injector 13, electronic control unit (ECU) 14, steering wheel mounted controls 15, LCD 10 display screen 16 and an engine (not shown). The engine system 10 further includes a data system in the form of a CAN bus 17 by which the ECU 14 communicates with controls 15 and screen 16. The engine is a direct injection engine. Injector 13 is one of a plurality of injectors, each of which is arranged to deliver fuel directly into a respective cylinder bore. 15 For convenience a single injector 13 is illustrated and described. Accordingly "injector" should be understood as a reference to "injector or injectors" except where the context dictates otherwise. Prior to the installation of the fuel system 30, the pump 11 would be arranged to draw fuel from the petroleum tank 20 and drive that fuel at high pressure to the injector 13 via 20 a fuel rail. The high pressure pump 11 has an inlet 11a and an outlet 11b that runs to the fuel rail. The inlet pressure on a petrol system is about 3 bar. The high pressure pump 11 boosts this pressure in substance anywhere from 10 to 150 bar. The pressure is controlled by pulsing open a flow valve which relieves pressure internally. Per its conventional use in this art, as used herein "fuel rail pressure" refers to the pressure at 25 which fuel is delivered to the injector and does not require there being a fuel rail per se.
    P1057AUAU 13 The pressure sensor 12 is mounted in the fuel rail to produce a data signal indicative of the fuel rail pressure. The ECU 14 is a control system for controlling the rate at which fuel is supplied to the engine. The ECU 14 communicates with the sensor 12 to receive the data signal, i.e. the data signal from the pressure sensor is an input signal to the 5 ECU 14. The ECU 14 is also in communication with the pump 11 and the injector 13. Based on the data signal and other inputs, the ECU controls the rate at which fuel is supplied to the engine by varying the fuel rail pressure and the duty cycle of injector 13. The fuel system 30 includes an LPG tank 31, LPG ECU 32, mixing unit 33 and a booster pump 34. When the system 30 is installed, the line of communication between the 10 sensor 12 and ECU 14 is cut (as suggested by scissors A in Figure 1) and the ECU 32 inserted therealong to intercept and modify the data signal from the sensor 12. Likewise the physical conduit communicating the petroleum tank 20 with the pump 11 is severed and pump 34 and mixing unit 33 inserted in series therealong. A further step in the installation of system 30 involves modifying the original equipment 15 pump 11. The original equipment pump 11 is a gear type pump including dynamic components, in the form of meshing gears rotationally driven, within a suitable housing to drive fuel from the pump's low pressure side to its high pressure side. A gear pump is an example of a positive displacement pump. Other pumps are possible, e.g. the pump may include a dynamic component in the form of an impellor. 20 The pump 11 is modified by the addition of a further flow port 11 c to function as a return port. A hole is drilled and tapped into the housing on the low pressure side of, and as close as practical to, the gears. A suitable fitting is screwed into this new hole. The mixing unit 33 includes a vessel 33a and a capping unit 33b of flow control arrangements. The vessel 33a includes an upwardly open cylindrical cup-like housing 25 33c sealingly closed by the capping unit 33b. Inlets 33d and 33e open through the capping unit 33b into the interior of the vessel 33a. The inlet 33d is communicated with the petroleum tank 20 via the pump 34 to receive petroleum therefrom into the vessel P1057AUAU 14 33a. The inlet 33e is communicated with the LPG tank 31 to receive LPG therefrom into the vessel 33a. The pump 34 serves to drive petroleum into the vessel. An internally mounted pump (not shown) within the LPG tank likewise serves to drive LPG towards the vessel. 5 The capping unit 33b includes a respective one-way valve (in the form of a ball check valve) associated with each of the inlets 33e, 33d to prevent the reversal of flow. A pair of electromechanical valves in the form of piloted solenoid valves 33g, 33h are provided to selectively open and close the inlets 33e, 33d. Figure 3 shows a vertical cross-section view through the axis of inlet 33d's tubular outer. Inlet 33d defines a flow 10 path into the vessel. This flow path includes portions 33d 1 , 33d 2 , 33d 3 and 33d 4 . Portion 33d 1 runs concentrically along the tubular outer from its open free end to the ball check valve at its inner end. Portion 33d 2 sits laterally outwards from the ball check valve and runs generally parallel to the portion 33d 1 to open into region 33d 3 . Portion 33d 4 follows a right-angled path including an initial section open to portion 33d 3 and aligned with, but 15 running in the opposition direction to, portion 33d 1 . From this opposite running section a vertical section extends downwardly into the interior of the vessel 33a. The ball check valve includes a ball driven by a spring to engage a conical valve seat in the inner end of the tubular outer and serves to selectively separate portions 33d 1 and 33d 2 . The solenoid 33g includes a horizontally acting piston which moves generally 20 parallel to portion 33d 1 (and the initial section of portion 33d 4 ) to engage structure defining portion 33d 4 so as to separate portions 33d 3 and 33d 4 . The inlet 33e and the flow control arrangements associated therewith are closely analogous to the details described in respect of Figure 3. The vessel 33a internally carries a pump 33f sealingly engaged with the capping unit 25 33b via sealing arrangement 33i. The pump 33f is powered via suitable conductors 33j passing through the capping unit 33b. The pump 33f serves to drive fuel out of the vessel via outlet 33k of the capping unit 33b.
    P1057AUAU 15 The capping unit 33b further includes flow ports 331, 33m and 33n and a further solenoid 33o associated therewith. The port 331 is an inlet (for receiving fuel returning from the pump 11) which (internally to the capping unit 33b) opens to both the port 33m and the solenoid valve 33o. The port 33n is an outlet for returning fuel to the fuel tank 31. The 5 solenoid 33o selectively communicates the port 33n with the ports 331, 33m. When the valve 33o is open, the port 33n is in fluid communication with the ports 33m, 331; when the valve 33o is closed, the outlet 33n is isolated. Each of the ports 33m, 33n is fitted with a respective ball check valve to prevent flow reversal. The ball check valve associated with the port 33m is configured only to open when 10 presented with returning fuel above a certain pressure predetermined to be greater than the pressure required to drive the returning fuel to the tank 31 via the outlet 33n. Accordingly, the valve 33o and ball check valve of the port 33m together constitute a flow controlling arrangement for directing the returning fuel to the vessel 33a or directing that fuel to the tank 31. When the valve 33o is closed, the pump 33f overcomes the ball 15 check valve of the port 33m to drive fuel to the vessel; when the ball check valve 33o is open, the ball check valve of the port 33m remains closed and the returning fuel continues on to the fuel tank 31. During operation of the vehicle, either one fuel or the other would be supplied to the engine most of the time. During changeover from one fuel to the other, the fuels are 20 combined within the unit 33 and the combined fuel supplied to the engine. By varying the rate at which the combined fuel is supplied to the engine to suit the relative proportions of the fuels in the combined fuel, at least preferred variants of the system 30 provide for improved engine operation during fuel transition relative to various existing approaches. Preferred forms of the system 30 also substantially avoid having petroleum 25 supplied to the LPG tank. In operation, fuel is recirculated between the unit 33 and the pump 11. It is thus useful to consider these two items together as a control volume CV.
    P1057AUAU 16 The ECU 32 is operatively linked to the pump of the fuel tank 31, pump 33f, solenoid valves 33g, 33h, 33o and pump 34. Under the control of ECU 32, when the vehicle is operating in a "petroleum-only" mode: * solenoid 33g is open to convey petroleum from the tank 20 into the unit 33; 5 e solenoid 33h is closed and the pump of tank 31 is inactive to prevent LPG entering the unit 33; * solenoid 33o is closed to prevent fuel returning from the pump 11 being conveyed to the tank 31; * the fuel in the control volume CV is in substance pure petroleum (i.e. is in 10 substance free of LPG); * the data signal from ECU 32 to ECU 14 is substantially identical to the data signal from the sensor 12 (or put another way, in substance the ECU 32 does not modify the data signal); and * the system 10 operates (and in particular the ECU 14 controls the supply of fuel 15 to the engine) substantially as in the original mono-fuel vehicle, excepting that ECU 32 controls the screen 16 via the CAN bus system 17 to display an indication that petroleum is being consumed. Upon receipt of a suitable user input the system 30, or more specifically the ECU 32, controls transition to an LPG-only mode. In this example, the user input can be made 20 using original equipment controls such as the stereo controls 15 mounted on the steering wheel. Thus preferred forms of the system 30 maintain the original equipment look, feel and quality of the vehicle interior. To effect transition to the LPG-only mode, first solenoid 33h is opened to communicate the unit 33 with the tank 31 and the solenoid 33g is closed to isolate the unit 33 from the P1057AUAU 17 tank 20. This serves to elevate the unit to the pressure of the LPG tank 31 (typically in the vicinity of 1 bar to 25 bar) without an appreciable flow of LPG to the unit 33. The ECU 32 monitors, via the CAN bus system 17, the control signal from the ECU 14 to the injector 13 (the "CAN bus injector duty signal"). Based on this control signal and a 5 known injector flow rate parameter, the ECU determines the rate at which fuel is being supplied to the engine and integrates this figure to monitor the amount of fuel supplied to the engine since the transition between modes was initiated. This amount of fuel is equal to the amount of fuel leaving the control volume CV. The ECU waits until about 50% of the fuel in the unit 33 (and control volume CV) has 10 been depleted before taking further action. In this example, the vessel 33a is dimensioned to carry about 1000 mg of fuel and the threshold amount of fuel for the next step in the transition is about 500 mg. Once this threshold, or "criterion", is reached, the pump of tank 31 is activated to begin driving LPG into the vessel 33 and the ECU 32 begins modifying the data signal between the sensor 12 and the ECU 14 to influence the 15 engine system 10 to vary the rate at which fuel is supplied to the engine via the injector 13. This process is referred to as signal emulation and the modified data signal from ECU 32 to ECU 14 is referred to as an emulated signal or emulated output (EO). The pump 33f is also activated at this stage. As LPG is driven into the vessel 33a via the inlet 33e, within the vessel the LPG 20 combines with the petroleum to form combined fuel. The vessel may or may not include an active mixing mechanism. In turn the outlet 331 and pump 11 now drive a blend of LPG and petroleum towards the injectors. During this phase, LPG but not petroleum is supplied to the control volume CV whilst combined fuel incorporating some petroleum leaves the control volume on its way to the 25 engine. Over time the relative proportions of fuels within the combined fuel changes as the petroleum within the control volume CV is depleted.
    P1057AUAU 18 Also during this phase, the ECU 13 continues to monitor the control signals from ECU 14 to injector 13 to obtain an indication of the amount of combined fuel supplied to the engine after the pump of tank 31 is activated. By suitably modifying the data signal, the ECU 32 influences the engine system 10 (or more specifically its ECU 14) to vary the 5 rate at which fuel is delivered to the engine to suit the changing relative proportions of fuel. With continued operation, the relative proportion of petroleum in the combined fuel approaches zero, or put another way, the relative proportion of LPG approaches 100%. After 1000 mg of fuel has been conveyed to the engine (since the pump of tank 31 was 10 activated), the combined fuel is sufficiently pure LPG to be treated as LPG, i.e. the combined fuel is in substance LPG. Once this important threshold is reached, the final step in the transition from the petroleum-only mode to LPG-only mode is to open the solenoid 30o to allow returning fuel to flow to the tank 31. This return flow carries heat from the fuel rail back to the tank 15 31 to prevent fuel vaporisation in the fuel rail. The returning fuel passes through the capping unit 33b entirely bypassing the vessel 33a. In the described system 10, 20, 30 LPG must be supplied to pump 11 is in a liquid state. There are two main factors that determine if LPG is in liquid state or not. They are temperature and pressure. With reference to Figure 6, if pressure and temperature is 20 below the upper line the LPG will change to vapour. LPG typically predominantly consists of propane and butane and its vaporisation properties are equivalent to the weighted average of the properties of these constituents. The upper and lower lines of Figure 5 illustrate the vaporisation characteristics of propane and butane respectively. To keep the LPG in its liquid state as it enters the HP Pump 11 the system 10, 20, 30 25 does 2 things: 1. Boosts the LPG pressure by activating the pump internal to tank 31 and the pump 33f.
    P1057AUAU 19 2. Lowers the temperature of the LPG approaching the pump 11. To lower the temperature LPG is returned from the HP pump via the retro-fit return port 11c and returned to the tank. The HP pump 11 can get very hot as it is typically mounted on the back of the engine's cylinder head. Flowing fuel through the housing of the pump 5 reduces the pump's temperature and heats the fuel in the LPG tank 31. Increasing the tank temperature increases the pressure within the tank 31 and so further contributes to the LPG approaching the pump remaining in its liquid state. When the system 10, 20, 30 is turned off the temperature increases in the HP pump and the pressure drops. At this point the LPG turns to a vapour. Before starting the engine 10 the LPG should be converted back to a liquid. As part of the startup procedure, under the control of ECU 32 the pump 33f circulates fuel through the pump housing (via the retro-fit port 11c) to flush the vapour out with liquid from the tank and to decrease temperature and increase pressure at the pump 11. Once the pump 11 boosts the pressure it is actually too high to change state so (in this 15 example) there is no need to purge liquid from the high pressure side of the system. There may be some instances where the high pressure side drops in pressure to the point of vaporisation if the factory calibration were followed. The ECU operates to remove this drop in pressure to ensure the system maintains liquid at the injector tip. In the LPG-only mode, the ECU 13 controls the screen 16 to display an indication that 20 LPG is being consumed and to display an indication of the amount of LPG remaining in the tank 31 (based on the signal from a zero to 90 ohm sender within the tank 31 and a level calibration table). The pressure differential across the pump in tank 31 is also monitored to provide an indication that the tank is emptying. If the sender or other indication suggests that the amount of fuel is below a predetermined threshold, the ECU 25 32 controls the vehicle via the CAN bus 17 to activate an alarm (e.g. sound a chime) to indicate that LPG is running out. In addition to the automatic warning, the ECU 32 will P1057AUAU 20 also automatically control transition to the petroleum-only mode to allow for the uninterrupted running of the vehicle. Transition from the LPG-only mode to the petroleum-only mode follows a similar process. Again the transition may be initiated by a user input and in response thereto 5 the ECU 32 sends control signals. The ECU 32: * closes the solenoid 33h to isolate the vessel 33a from the tank 31 and the pump of tank 31 is deactivated; and * closes the valve 33o to stop returning fuel being conveyed to the tank 31 (instead the ball valve of return fuel inlet 33m will open so that the returning fuel is 10 received into the vessel 33a), and the pump 33f is activated. The ECU 32 again waits until about 500 mg of fuel has been delivered to the engine before entering the next phase of transition. Once this 500 mg threshold has been met, the pump 34 is activated to drive petroleum towards the vessel 33. After a short delay sufficient for the pump 34 to build pressure, 15 valve 33g is opened for petroleum to be received into the vessel 33a via the inlet 33d and to mix with the LPG therein to form combined fuel. During this phase the relative proportions of fuels in the combined fuel varies and approaches pure petroleum over time. As in the transition from petroleum to LPG, the ECU 32 monitors the amount of fuel delivered to the engine and influences the system 20 10 to vary the rate at which fuel is supplied to the engine to suit the changing blend of fuel. In the present example, after 1000 mg of fuel has been delivered to the engine in this phase of the transition, the combined fuel is in substance petroleum. A short period after this important threshold (e.g. 500 milliseconds after), the pumps 33f, 34 are deactivated. 25 The transition to the petroleum-only mode is now complete.
    P1057AUAU 21 If at any point a user deactivates the vehicle (e.g. the ignition voltage is open circuit), the ECU 32 records the mode in which the vehicle is operating, and if the vehicle is in transition records the progress of the transition (i.e. the amount of fuel to have been delivered to the engine since the transition was initiated or since the target fuel, i.e. the 5 fuel to which the vehicle was transitioning, was first supplied to the vessel 33a). In addition to recording this data, upon vehicle shut-down the ECU 32 closes solenoids 33g, 33h, 33o and deactivates the pump of tank 31 and pumps 33f, 34 (should those valves be open or those pumps be active). Once the data is recorded, valves closed and pumps deactivated, the ECU 32 powers down. 10 The operation of the systems 10, 30 and calculations internal to ECU 32 will now be described with reference to Tables 1 to 6. Table 1 outlines the operating procedures described above. Table 2 outlines the operating procedures in more detail and with reference to the latter tables. Tables 3 to 5 are examples of (potentially calibratable) input data carried by the ECU 32. Table 6 details how the emulated pressure signal (and 15 in turn the rate at which combined fuel is supplied to the engine) varies as a function of an indication of an amount of fuel to flow to the engine. The fuel pressure compensation curve detailed by Table 3 differs significantly from a standard fuel pressure compensation curve. When the inlet pressure is modified on its way to the petrol ECU, a proportional integral derivative (PID) controller is used to move 20 the inlet pressure.
    P1057AUAU 22 Table 1 Function Description Vehicle start-up Last fuel mode determined If petrol or LPG mode was last used it will start in that mode after crank signal If switch over mode was last used, it will continue from where it left off It will continue wherever it was in the decay tables Start on petrol Vehicle was last running on Petrol When crank recognised, petrol inlet solenoid opens As reservoir was already in petrol mode the petrol boost pump has no need to run LCD display shows petrol and the LPG level is displayed Start on LPG Vehicle was last running on LPG When crank recognised, LPG inlet, return Valve Solenoid and LPG tank solenoid opens LPG in tank pump and mixing unit pump on Petrol pressure sensor is read and emulated to as per tables and calculations LCD display shows LPG and the LPG level is displayed Switch from LPG to petrol LPG tank, return Valve and LPG inlet solenoid close LPG in tank pump off Flow is measured from that point Once calibrated flow met, petrol boost pump is turned on After set time, petrol inlet solenoid is opened This then triggers the Petrol decay table for the emulated petrol sensor output This will decay from 100% emulation to 0% emulation once 100% petrol in system LCD will display petrol and indicate LPG level P1057AUAU 23 Function Description Switch from petrol to LPG LPG tank solenoid opens Petrol solenoid closes Flow is measured from that point Once calibrated flow met, LPG inlet solenoid is opened, LPG in tank pump and mixing unit pump on This then triggers the LPG decay table for the emulated petrol sensor output This will decay from 0% emulation to 100% emulation once 100% LPG in system Once at 100% emulation, open return valve solenoid LCD will display LPG and indicate LPG level Vehicle switched off Current status is memorised If switched off during a switch over (in a decay table) the position will be memorised for continuation at start-up All solenoids and pumps are turned off Low level switch back In tank differential pump pressure switch activates Switch to petrol mode automatically selected Error switch back Error is detected Switch to petrol mode automatically selected Table 2 Function Description Vehicle start-up Controller receives ignition power Last fuel mode determined and selection made based on this P1057AUAU 24 Function Description If LPG mode was last used GoTo "Switch to LPG" and continue from same line and same table location of flow or decay table If Petrol mode was last used GoTo "Switch to Petrol" and continue from same line and same table location of flow or decay table Switch to petrol Off LPG tank, LPG inlet solenoid, return valve solenoid On Mixing Unit Pump Measure Accumulated Flow from that point. This is measured by (accumulated injector duty (measured by CAN bus injector duty signal or signal from an actual injector) X injector flow rate (set flow value in software)) Wait for required flow to be met, (Variable called "LPG to use" value that can be set in calibration software) On petrol boost pump Wait set time "Petrol Boost Delay" (default 1 second but calibratable in software) Open Petrol inlet solenoid Measure Accumulated Flow from that point. This is measured by (accumulated injector duty (measured by CAN bus injector duty signal or signal from an actual injector) X injector flow rate (set flow value in software)) Wait for required flow to be met, (Variable called "rail Volume" value that can be set in calibration software) Emulation sent to petrol pressure sensor The output is based on Petrol Decay Table location This will decay from 100% emulation to 0% emulation once 100% Petrol in system This table uses the fuel flow calculation (measured by CAN bus injector duty signal or signal from an actual injector) X injector flow rate (set flow value in software) Wait until 0% Emulation above Wait 500ms Off petrol boost pump Off Mixing unit pump P1057AUAU 25 Function Description IN THIS MODE ALWAYS Display the word "Petrol" and the LPG level (indicated by tank percentage) on the LCD display via CAN LPG level is determined by the 0-90 ohm sender against level calibration table If the change fuel signal from CAN switch input or manual switch input detected Beep once via CAN bus buzzer Display the word "LPG" and the LPG level (indicated by tank percentage) on the LCD display via CAN LPG level is determined by the 0-90 ohm sender against level calibration table GoTo "Switch to LPG" mode If Ignition voltage open circuit Record if in petrol or LPG mode Record position in either mode Record position in any table being used Off All solenoids and pumps Power down Switch to LPG ON LPG tank solenoid Off Petrol inlet solenoid Measure Accumulated Flow from that point. This is measured by (accumulated injector duty (measured by CAN bus injector duty signal or signal from an actual injector) X injector flow rate (set flow value in software)) Wait until the set accumulated flow is met (Variable called "Petrol to use", a value set in software) On LPG inlet solenoid, Mixing unit pump, In tank LPG Pump Measure Accumulated Flow from that point This is measured by (accumulated injector duty (measured by CAN bus injector duty signal or signal from an actual injector) X injector flow rate (set flow value in software)) P1057AUAU 26 Function Description Wait until the set accumulated flow is met (Variable called "Rail Volume" a value set in software) Emulation sent to petrol pressure sensor The output is based on LPG Decay Table location This will decay from 0% emulation to 100% emulation once 100% LPG in system. This table uses the fuel flow calculation (measured by CAN bus injector duty signal or signal from an actual injector) X injector flow rate (set flow value in software) ON Return Valve Solenoid (only after on 100% LPG (100% Emulation)) IN THIS MODE ALWAYS Display the word "LPG" and the LPG level (indicated by tank percentage) on the LCD display via CAN LPG level is determined by the 0-90 ohm sender against level calibration table If low level switch closed circuit to ground Activate alarm via CAN (chime three times to indicate fuel run out) goto "switch to petrol" If change fuel signal from CAN switch input or manual switch inputdetected Beep once via CAN bus buzzer Display the word "Petrol" and the LPG level (indicated by tank percentage) on the LCD display via CAN LPG level is determined by the 0-90 ohm sender against level calibration table GoTo "Switch to Petrol" mode If Ignition voltage open circuit Record if in petrol or LPG mode Record position in either mode Record position in any table being used Off All solenoids and pumps Power down P1057AUAU 27 Table 3 Fuel pressure multiplier Pressure (bar) LPG multiplier 4 0.0010 10 0.0010 20 0.0010 30 0.0010 40 0.0010 50 0.0010 60 0.0010 70 0.0010 80 0.0010 90 0.0010 100 0.0015 110 0.0020 120 0.0122 130 0.0602 140 0.1323 150 0.1924 160 0.2645 170 0.3663 180 0.4688 190 0.5650 200 0.6972 210 0.8174 220 0.9366 230 1.0818 240 1.2621 250 1.4164 P1057AUAU 28 Table 4 (part 1) ECT Temperature (DegC) -40 -32 -24 -16 -8 0 8 16 0 0.86 0.87 0.89 0.90 0.91 0.92 0.93 0.94 500 0.87 0.88 0.89 0.90 0.92 0.93 0.93 0.94 1000 0.87 0.88 0.90 0.91 0.92 0.93 0.94 0.95 1500 0.88 0.89 0.91 0.92 0.93 0.94 0.95 0.96 2000 0.89 0.90 0.92 0.93 0.94 0.95 0.96 0.97 2500 0.90 0.91 0.93 0.94 0.95 0.96 0.97 0.97 3000 0.91 0.92 0.94 0.95 0.96 0.97 0.97 0.97 I.. 3500 0.92 0.93 0.95 0.96 0.97 0.97 0.97 0.97 4000 0.93 0.94 0.96 0.96 0.97 0.97 0.97 0.97 4500 0.94 0.95 0.96 0.97 0.97 0.97 0.97 0.97 5000 0.95 0.96 0.97 0.97 0.97 0.97 0.97 0.97 5500 0.96 0.96 0.97 0.97 0.97 0.97 0.97 0.97 6000 0.96 0.97 0.97 0.97 0.97 0.97 0.97 0.97 6500 0.97 0.97 0.97 0.97 0.97 0.97 0.97 0.97 7000 0.98 0.98 0.98 0.98 0.98 0.98 0.98 0.98 Table 4 (part 2) ECT Temperature (DegC) 24 32 40 56 72 80 88 92 112 0 0.95 0.96 0.97 0.98 0.99 0.99 1.00 1.00 1.00 500 0.95 0.96 0.97 0.98 0.99 0.99 1.00 1.00 1.00 1000 0.96 0.97 0.97 0.98 0.99 0.99 1.00 1.00 1.00 1500 0.97 0.97 0.97 0.98 0.99 0.99 1.00 1.00 1.00 2000 0.97 0.97 0.97 0.98 0.99 0.99 1.00 1.00 1.00 2500 0.97 0.97 0.97 0.98 0.99 0.99 1.00 1.00 1.00 3000 0.97 0.97 0.97 0.98 0.99 0.99 1.00 1.00 1.00 I.. 3500 0.97 0.97 0.97 0.98 0.99 0.99 1.00 1.00 1.00 4000 0.97 0.97 0.97 0.98 0.99 0.99 1.00 1.00 1.00 4500 0.97 0.97 0.97 0.98 0.99 0.99 1.00 1.00 1.00 5000 0.97 0.97 0.97 0.98 0.99 0.99 1.00 1.00 1.00 5500 0.97 0.97 0.97 0.98 0.99 0.99 1.00 1.00 1.00 6000 0.97 0.97 0.97 0.98 0.99 0.99 1.00 1.00 1.00 6500 0.97 0.97 0.97 0.98 0.99 0.99 1.00 1.00 1.00 7000 0.98 0.98 0.98 0.99 0.99 0.99 1.00 1.00 1.00 5 P1057AUAU 29 Table 5 (part 1) PUMP PRESSURE OFFSET TABLE - Air Per Cylinder (grams per cylinder) Calculated by ("Mass Air Flow" X 15 / "RPM") BAR 0.08 0.12 0.16 0.2 0.24 0.28 0.32 0.36 0.4 400 -20.00 -20.00 -20.00 -10.00 0.00 0.00 0.00 0.00 0.00 800 -20.00 -20.00 -20.00 -10.00 0.00 0.00 0.00 0.00 0.00 1200 0.00 0.00 -10.00 0.00 0.00 0.00 0.00 0.00 0.00 1600 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2400 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2800 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 3200 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 3600 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 4000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 4400 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 4800 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 5200 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 5600 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 6000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 6400 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 6800 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Table 5 (part 2) PUMP PRESSURE OFFSET TABLE - Air Per Cylinder (grams per cylinder) Calculated by ("Mass Air Flow" X 15 / "RPM") BAR 0.44 0.48 0.52 0.56 0.6 0.64 0.68 0.72 400 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 800 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1200 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1600 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2400 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2800 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 3200 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 3600 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 4000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 P1057AUAU 30 PUMP PRESSURE OFFSET TABLE - Air Per Cylinder (grams per cylinder) Calculated by ("Mass Air Flow" X 15 / "RPM") BAR 0.44 0.48 0.52 0.56 0.6 0.64 0.68 0.72 4400 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 4800 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 5200 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 5600 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 6000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 6400 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 6800 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Table 5 (part 3) PUMP PRESSURE OFFSET TABLE - Air Per Cylinder (grams per cylinder) Calculated by ("Mass Air Flow" X 15 / "RPM") BAR 0.76 0.8 0.84 0.88 0.92 0.96 1 1.04 400 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 800 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1200 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1600 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2400 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2800 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 3200 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 3600 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 4000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 4400 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 4800 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 5200 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 5600 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 6000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 6400 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 6800 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 5 P1057AUAU 31 Table 5 (part 4) PUMP PRESSURE OFFSET TABLE - Air Per Cylinder (grams per cylinder) Calculated by ("Mass Air Flow" X 15 / "RPM") BAR 1.08 1.12 1.16 1.2 1.24 1.28 1.32 1.36 400 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 800 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1200 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1600 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2400 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2800 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 3200 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 3600 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 4000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 4400 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 4800 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 5200 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 5600 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 6000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 6400 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 6800 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Table 6 Fuel used mg Multiplier 0 0 100 0.1 200 0.2 300 0.3 400 0.4 500 0.5 600 0.6 700 0.7 800 0.8 900 0.9 1000 1 P1057AUAU 32 Embedded within the calculation steps of ECU 32 is a calculation of the modified data signal from ECU 32 ("emulation output" EO) to suit LPG-only running. This calculation is based on engine coolant temperature, the pressure of the fuel delivered to the injector 5 13 (i.e. fuel rail pressure) and the crank speed (RPM) of the engine. Firstly a fuel pressure multiplier (PM) is determined based on the fuel rail pressure and Table 3. Secondly a temperature multiplier (TM) is taken from Table 4. Table 4 lists TM as a function of RPM and engine coolant temperature. Thirdly a cylinder air flow offset (CO) is taken from Table 5. Table 5 lists CO as a function of RPM and fuel rail pressure. 10 Reading from Tables 3 to 6 will likely involve interpolation. The inventors have recognised that the injectors (being deeply embedded within the engine) can be hotter than the fuel rail and that at low rail pressures and low RPM this temperature difference can cause low boiling point fuels to vaporise within the injectors. The CO parameter is included in the calculations to address this potential temperature 15 difference. The rail pressure (RP), pressure multiplier (PM), temperature multiplier (TM) and cylinder offset are then combined to produce an emulation output to suit LPG-only running (EOLPG only) as follows: EOLPG only = RP + ((RP * PM) -RP) + ((RP * TM)-RP) - CO (1) 20 As previously mentioned the ECU 32 does not modify the pressure signal from the sensor 12 for petroleum-only running: EOPetroleum only = RP (2) Subtracting (2) from (1) gives the amount by which the emulated signal to suit LPG-only running varies from petroleum-only running (AEO): 25 AEOPetroleum only to LPG only = ((RP * PM)-RP) + ((RP * TM) -RP) - CO (3) P1057AUAU 33 To transition from petroleum-only running to LPG-only running, EOLPG only is "phased in" in accordance with Table 6 and equation 4. Table 6 lists "Fuel Used" multiplier FU as a function of the mass of fuel delivered to the engine after the solenoid valve is opened to supply the incoming fuel to the vessel. FU in substance ranges from 0 to 1. Accordingly 5 the emulation output during transition can be expressed as: EOTransition = EOPetrol only + (AEOPetroleum only to LPG only * FU) (4a) = RP + ((((RP * PM) -RP) + ((RP * TM) -RP) -CO)*FU) (4b) In this example the FU multiplier varies in direct proportion to the mass of fuel supplied. 10 Other functions are possible and it is contemplated that this parameter be calibratable by system installers to suit individual vehicles. In particular, it is foreshadowed that the function, rather than being linear, may well be hyperbolic and asymptotically approach 1, in which case the function may be truncated so that FU is given the value of 1 when the fuel supplied to the engine is in substance LPG. 15 To transition from LPG-only to petroleum-only mode a similar process is applied in reverse. At this point it is worth emphasising that this particular calculation procedure is by way of example only and may be replaced by other calculation procedures (which may or may not be equivalent) and/or an entirely different approach. By way of example whilst the 20 inclusion of the temperature multiplier TM and cylinder air flow offset CO are preferred, the simple product of rail pressure RP and the pressure multiplier PM has been found to be a workable value for EOLPG only, and it is contemplated that Table 6 could be eliminated by measuring characteristics of the fuel to the injectors. It is also worth emphasising that the invention is not limited to the described particular 25 implementation of these calculations. Control systems and logic arrangements other than ECU 32 are possible and could take the form of single integrated units or of a set of distributed components. Similarly, whilst various examples of the fuel systems are described, other variants are possible (e.g. whilst the above examples speak of P1057AUAU 34 switching from one fuel to another, the unit 33 might be employed to supply a blend of fuels on an ongoing basis) and the various components described herein may be usefully applied to other applications (e.g. the retro-fit port 11c may be convenient in the context of converting a vehicle to operate only on low boiling point fuel from operating 5 only on another fuel such as petroleum). Figure 1 illustrates the addition of a retro-fit kit to a petrol-only OEM vehicle so that the vehicle is operable on both petrol and LPG. Figure 7 schematically illustrates selected components of a different OEM vehicle operable only on LPG. The design of the vehicle of Figure 7 is based on the design of the OEM vehicle of 10 Figure 1 and on another OEM vehicle. The other OEM vehicle is operable only on LPG and includes a vapour injection system in which LPG is supplied to the inlet runners of the engine. The major components of the vehicle of Figure 7 are selected from the specifications of two earlier existing OEM vehicles. This leads to significant efficiencies for the 15 manufacturer. In particular the design and engineering cost associated with developing new major components is avoided as are the inventory costs of having additional components. Moreover a single engine (the engine of the petrol-only existing vehicle) can be used to power an LPG-only vehicle so the significant expense of manufacturing an engine dedicated to the vapour injection system can be avoided. 20 Whilst Figure 7 describes a new OEM LPG-only vehicle, it is also possible that the described technology may be retro-fitted to an existing petrol-only vehicle to convert that vehicle to run only on LPG. Preferably the two existing vehicles share major components excepting their fuel and engine systems so that the fuel tank of one may be readily fitted to the other, etc. Also, 25 both vehicles are preferably mass-produced, adding to the economies of scale.
    P1057AUAU 35 The vehicle of Figure 7 is most closely based on the petrol-only earlier vehicle. In particular, its engine (not shown), pressure sensor 12, fuel injectors 13, ECU 14, gauges 16 and CAN bus system 17 are retained. Its petrol tank and its spare wheel are removed from the rear of the vehicle and replaced with a fuel tank assembly 31'. The boot floor, 5 which fits over the fuel tank assembly 31', of the LPG-only existing vehicle is fitted, restoring the boot to its original OEM appearance without any new components being required. For the avoidance of doubt, outside of Australia a boot is sometimes referred to as a trunk and a bonnet is sometimes referred to as a hood. 10 The tank assembly 31' includes the tank 31 a' of the LPG-only vehicle and a multi-valve cluster 31b'. New multi-valve 31b' includes a return line fitting in place of the LPG-only existing vehicle's tank pressure sensor as the tank pressure sensor is no longer required. The return fitting includes a one way valve. The fuel filler assembly, by which the vehicle may be refuelled, of the LPG-only existing vehicle is of course co-operable 15 with the tank 31a' without any re-engineering. The modifications to the design of the multi-valve 31b' also include removing the return less pressure regulator and replacing it with a new 5 bar pressure regulator connected to the internal site of the return fitting. As part of the redesign process, the pump 11 is redesigned to incorporate a return port 20 akin to the port 11 c, although it is also possible that the return port 11 c may be retro fitted within the OEM environment should that be more cost effective. Conveniently the conduits of the existing petrol-only vehicle are used to form a pair of fluid connections between the tank assembly 31' and the pump 11. The petrol-only vehicle includes a petrol supply tube running from the fuel tank at the rear of the vehicle 25 to the under bonnet region at the front of the vehicle. Flexible petrol supplier hose connects this tube to the pump 11. The flexible petrol supplier hose is replaced by a higher pressure and the original petrol supply tube connected to the tank assembly 31'.
    P1057AUAU 36 By reusing this tube, engineering time required to route and appropriately mount the tube is avoided. Similar efficiencies are realised when defining a return flow path from the port 11 c to the return line fitting. The existing petrol-only vehicle includes a steel pipe connecting the 5 engine, or more specifically the purge solenoid of the engine, to a petrol purge canister at the rear of the vehicle. As this pipe is no longer required it can be repurposed to provide a return line for conveying fuel from the high pressure pump 11 to the tank. This is achieved by a suitable flexible hose connecting the return port 11c to the steel pipe and another suitable hose connecting the steel pipe to the return fitting. 10 During the re-design, the internal pressure relief of the tank 31 is removed and attached to the return line in the design specifications. This changes the system from a return-less system to a return system and regulates pressure. In this example the regulation pressure is increased from 2.5 bar (in the existing LPG-only vehicle) to 5 bar (in the new LPG-only vehicle). 15 The tank 31 includes its own internal pump which in a manner akin to the pump 33f circulates fuel between the tank 31 and the pump 11 to cool the pump and ensure that the pump's dynamic components are continuously supplied with liquid fuel. The return line from the pump 11 to the tank 31 is fitted with an external pressure regulator which serves to boost the pressure to 5 bar above tank pressure. 20 Figure 7 suggests that the vehicle include a dedicated LPG ECU. This implementation is suited to the retro-fit environment. It may carry a similar set of calculations to those described in respect of Figure 1 although the calculations relating to fuel transition would not be required. In the OEM context it is preferred that the ECU 32 be eliminated by providing a modified 25 variant of the ECU 14.
    P1057AUAU 37 However implemented, it is preferred that the ECU 14 (or ECU's 14, 32) have full control over fuelling and that (relative to the existing petrol-only vehicle) the calibration be changed including changes to injector flow, injector pressure compensation, stoichiometric value, cold start tables and fuel temperature compensation, etc. Also, a 5 pump speed table should be modified to allow high speed pumping during purging before start up. When the vehicle is shut down LPG along the various conduits vaporises. So running the pump at high speed before start up serves to purge the conduits between the tank 31 and the pump 11 of vapour. 10 In various simple implementations of the system, the vapour purge cycle might be initiated in response to a specific user input or in response to a user input (e.g. turning a key or pressing a start button) to start the engine. Both implementations result in some delay and inconvenience to the user. A preferred implementation of the purging cycle involves a control system (e.g. the 15 vehicle ECU) configured to receive an indication of a person interacting with a dormant vehicle. A user unlocking the driver's door is a convenient indication. By way of example, the door might be unlocked by a key being inserted into the door lock, a button being pressed on a key fob, or the vehicle's security system detecting a transponder carried by an authorised driver as part of a keyless entry system. The indication may be carried to 20 the vehicle's ECU from the vehicle's security system associated with the door lock and conveyed to the ECU 14 via the CAN bus system 17. Thus according to this preferred implementation of the system, the pump of the tank assembly 31' is activated, in anticipation of the engine being started, when its driver enters the vehicle. Thus the dormant vehicle, or more specifically its engine, is made 25 ready for activation. Once the driver is ready to activate the engine they may do so in the usual fashion, e.g. by turning a key in the ignition or pressing a start button, and the engine can start instantaneously as in a conventional petroleum powered vehicle.
    权利要求:
    Claims (45)
    [1] 1. A method, of supplying fuel to an engine, including combining a first fuel and a second fuel to form combined fuel; supplying the combined fuel to the engine; and 5 varying the rate at which the combined fuel is supplied to the engine to suit the relative proportions of the first fuel and the second fuel in the combined fuel.
    [2] 2. The method of claim 1 wherein the combining, supplying and varying are during switching from supplying to the engine one of the first fuel and the second fuel; 10 to supplying to the engine the other of the first fuel and the second fuel.
    [3] 3. The method of claim 2 wherein in substance the combining includes supplying the other fuel to a control volume containing the one fuel.
    [4] 4. The method of claim 3 wherein the varying the rate at which the combined fuel is supplied is varying as a function of an indication of an amount of combined fuel supplied 15 from the control volume.
    [5] 5. The method of claim 4 wherein the indication is or includes a control signal to, or feedback signal from, one or more fuel injectors.
    [6] 6. The method of any one of claims 1 to 5 wherein the varying includes intercepting and modifying an input signal to a control system controlling the rate at which fuel is 20 supplied. P1057AUAU 39
    [7] 7. The method of claim 6 wherein the input signal corresponds to a pressure at which fuel is delivered to fuel injector(s).
    [8] 8. The method of any one of claims 1 to 7 wherein the first fuel is petroleum.
    [9] 9. The method of any one of claims 1 to 8 wherein the second fuel is a low boiling 5 point fuel.
    [10] 10. The method of any one of claims 1 to 9 wherein the engine is driving a vehicle.
    [11] 11. A fuel system for supplying fuel to an engine system; the engine system including an engine; the fuel system including 10 a fuel tank; a vessel including one or more inlets for receiving into the vessel, from a fuel supply, a first fuel and, from the fuel tank, a second fuel; an outlet for dispatching from the vessel fuel to the engine system; and 15 a control system configured to vary the rate at which the dispatched fuel is supplied to the engine to suit the relative proportions of the first fuel and the second fuel in the dispatched fuel.
    [12] 12. The fuel system of claim 11 including a flow control arrangement responsive to the control system to control the receipt of the first fuel and the second fuel via the one or 20 more inlets. P1057AUAU 40
    [13] 13. The fuel system of claim 12 wherein the control system is configured to, when switching from one of the first fuel and the second fuel to the other of the first fuel and the second fuel, cause the other fuel to be received via the inlet(s) to, within the vessel, combine with the one fuel. 5 14. The fuel system of claim 12 or 13 wherein the flow control arrangement includes an electromechanical valve for selectively communicating the fuel supply with the vessel.
    [14] 15. The fuel system of any one of claims 12 to 14 wherein the flow control arrangement includes an electromechanical valve for selectively communicating the fuel tank with the vessel. 10 16. The fuel system of any one of claims 11 to 15 wherein the varying the rate at which the combined fuel is supplied is varying as a function of an indication of an amount of fuel supplied to the engine.
    [15] 17. The fuel system of claim 16 wherein the indication is or includes a control signal to, or feedback signal from, one or more fuel injectors of the engine system. 15 18. The fuel system of any one of claims 11 to 17 wherein the control system is configured to vary the rate at which the fuel is supplied to the engine by influencing the engine system.
    [16] 19. The fuel system of claim 18 wherein the control system is configured to intercept and modify a data signal of the engine system to so influence the engine system. 20 20. The fuel system of claim 19 wherein the data signal corresponds to a pressure at which fuel is delivered to fuel injector(s).
    [17] 21. The fuel system of any one of claims 11 to 20 wherein the vessel includes a further inlet for receiving fuel returning from the engine system. P1057AUAU 41
    [18] 22. The fuel system of claim 21 including an electromechanical valve responsive to the control system to selectively direct the returning fuel to the fuel tank.
    [19] 23. The fuel system of any one of claims 11 to 22 wherein the vessel internally carries a pump for driving fluid through the outlet. 5 24. The fuel system of any one of claims 11 to 23 wherein the first fuel is petroleum.
    [20] 25. The fuel system of any one of claims 11 to 24 wherein the second fuel is a low boiling point fuel.
    [21] 26. The fuel system of any one of claims 11 to 25 in a vehicle wherein the engine is arranged to drive the vehicle. 10 27. The fuel system of any one of claims 11 to 26 and the engine system.
    [22] 28. A vehicle including the fuel system of any one of claims 11 to 26 and the engine system.
    [23] 29. A pump, for pumping fuel to injector(s) of a direct injection engine, including an inlet for receiving the fuel from a fuel supply; 15 a first outlet for conveying the received fuel toward the injector(s); one or more dynamic components for driving the received fuel from the inlet to the first outlet; and a second outlet, upstream of the dynamic components, for conveying the received fuel toward the fuel supply. 20 30. The pump of claim 29 being a positive displacement pump. P1057AUAU 42
    [24] 31. The pump of claim 30 wherein the dynamic components are gears.
    [25] 32. A fuel system, for supplying a low boiling point fuel to a direct injection engine, including the pump of claim 29, 30 or 31; and 5 conduit connecting the fuel supply to the inlet, and conduit connecting the second outlet to the fuel supply, to define a fluid circuit; and a second pump for driving the fuel about the fluid circuit.
    [26] 33. The fuel system of claim 32 including a control system to control the pump; 10 wherein the control system is configured to receive an indication of a person interacting with a dormant vehicle; and before the person gives an input to start the engine, activate the pump in response to the indication.
    [27] 34. A fuel system, for supplying fuel to an engine of vehicle, including 15 conduit for conveying the fuel toward the engine; a pump for driving the fuel along the conduit; a control system to control the pump; wherein the control system is configured to receive an indication of a person interacting with a dormant vehicle; and P1057AUAU 43 before the person gives an input to start the engine, activate the pump in response to the indication.
    [28] 35. The fuel system of claim 33 or 34 wherein the indication is associated with the one or more doors of the vehicle being at least one of unlocked and opened. 5 36. A fuel system, for supplying fuel to an engine of vehicle, including conduit for conveying the fuel toward the engine; a pump for driving the fuel along the conduit; a control system to control the pump; wherein the control system is configured to 10 activate the pump in response to one or more doors of the vehicle being at least one of unlocked and opened.
    [29] 37. A vehicle, operable on at least one low boiling point fuel, including a direct injection engine from specifications of an existing vehicle operable on petroleum; 15 a fuel tank from specifications of an existing vehicle operable on low boiling point fuel; a fuel system for conveying the low boiling point fuel from the fuel tank to the engine.
    [30] 38. The vehicle of claim 35 wherein the fuel system is the fuel system of any one of claims 32 to 35.
    [31] 39. The vehicle of claim 37 or 38 wherein P1057AUAU 44 the specifications of the existing vehicle operable on petroleum include a petroleum supply tube; and the vehicle includes the petroleum supply tube arranged to convey the low boiling point fuel away from the fuel tank. 5 40. The vehicle of claim 37, 38 or 39 wherein the specifications of the existing vehicle operable on petroleum include a flexible petroleum supply hose under its bonnet; and the vehicle includes a high pressure hose in place of the flexible petroleum supply hose.
    [32] 41. The vehicle of any one of claims 37 to 40 wherein 10 the specifications of the existing vehicle operable on petroleum include a steel pipe connecting a vapour purge canister to a purge solenoid; and the vehicle includes the steel pipe arranged to convey the low boiling point fuel towards the tank.
    [33] 42. The vehicle of claim 41 including flexible hose connecting the steel pipe to the 15 fuel tank.
    [34] 43. The vehicle of any one of claims 37 to 42 wherein the specifications of the existing vehicle operable on low boiling point fuel include a tank pressure sensor; and the vehicle includes a return line fitting in place of the tank pressure sensor. 20 44. The vehicle of claim 43 wherein the return line fitting includes a one way valve. P1057AUAU 45
    [35] 45. The vehicle of any one of claims 37 to 44 or wherein the specifications of the existing vehicle operable on low boiling point fuel include a return-less pressure regulator; and the vehicle includes in place of the return-less pressure regulator a regulator connected 5 to an internal side of the return line fitting.
    [36] 46. The vehicle of claim 45 wherein the regulator connected to an internal side of the return line fitting is in substance a 5 bar regulator.
    [37] 47. A method, of manufacturing a pump for pumping low boiling point fuel to injector(s) of a direct injection engine, including modifying a pump for pumping fuel to an 10 engine; the pump for pumping fuel including an inlet for receiving fuel from a fuel supply; an outlet for conveying the received fuel toward the injector(s); one or more dynamic components for driving the received fuel from the inlet to 15 the outlet; and the method including creating a second outlet, upstream of the dynamic components, for conveying the received fuel toward a fuel supply.
    [38] 48. The method of claim 47 wherein the creating the second outlet includes or consists of drilling a hole in a housing of the pump. 20 49. A method of modifying an engine system the engine system including an engine and a pump for driving fuel toward the engine; P1057AUAU 46 the pump including a housing, housing dynamic components for so driving the fuel; the method including creating an opening in the housing to convey heated fuel away from the pump.
    [39] 50. A method, of readying an engine of a dormant vehicle for activation, including 5 before a person gives an input to start the engine, activating a pump in response to an indication of the person interacting with the dormant vehicle.
    [40] 51. The method of claim 50 wherein the indication is associated with the one or more doors of the vehicle being at least one of unlocked and opened.52.A method, of readying an engine of a dormant vehicle for activation, including activating a pump in 10 response to one or more doors of the vehicle being at least one of unlocked and opened.
    [41] 53. A method of designing a vehicle; the vehicle having a direct injection engine and being operable on at least one low boiling point fuel; 15 the method in substance including selecting a direct injection engine from specifications of an existing vehicle operable on petroleum; selecting a fuel tank from specifications of another existing vehicle operable on an or the low boiling point fuel; 20 specifying a fuel system for conveying low boiling point fuel from the fuel tank to the engine.
    [42] 54. A method of manufacturing a vehicle, P1057AUAU 47 the vehicle including a direct injection engine and being operable on low boiling point fuel; the method including modifying an existing vehicle having a direct injection engine and being operable on petroleum; 5 the modifying including; fitting a fuel tank for containing the low boiling point fuel; and connecting conduit to convey fuel from the fuel tank to the engine.
    [43] 55. A vehicle, operable on at least one low boiling point fuel, including a direct injection engine; 10 a fuel tank for containing the low boiling point fuel; a fuel system for conveying the low boiling point fuel from the fuel tank to the engine; and a steel pipe arranged to convey the low boiling point fuel from the engine towards the tank. 15 56. The vehicle of claim 55 including flexible hose connecting the steel pipe to the fuel tank.
    [44] 57. A method of defining a return line in a vehicle the vehicle including a direct injection engine and being operable on at least one low boiling point fuel; P1057AUAU 48 the method including connecting a steel pipe to convey towards a fuel tank low boiling point fuel from the engine.
    [45] 58. The method of claim 57 including installing flexible hose to connect the steel pipe to the fuel tank.
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    同族专利:
    公开号 | 公开日
    AU2013203207B2|2016-03-17|
    NZ614355A|2014-11-28|
    NZ629150A|2016-02-26|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    US5911210A|1997-10-03|1999-06-15|Cooper Cameron Corporation|Method and apparatus for supplying fuel to an internal combustion engine|
    SE534873C2|2010-06-22|2012-01-31|Scania Cv Ab|Fuel system for injecting a fuel mixture into an internal combustion engine|
    法律状态:
    2016-07-14| FGA| Letters patent sealed or granted (standard patent)|
    2019-11-07| MK14| Patent ceased section 143(a) (annual fees not paid) or expired|
    优先权:
    申请号 | 申请日 | 专利标题
    AU2012905368||2012-12-10||
    AU2012905368A|AU2012905368A0||2012-12-10|Dual fuel supply|
    AU2013203207A|AU2013203207B2|2012-12-10|2013-04-09|Fuel supply|AU2013203207A| AU2013203207B2|2012-12-10|2013-04-09|Fuel supply|
    NZ614355A| NZ614355A|2012-12-10|2013-08-15|Fuel supply|
    NZ629150A| NZ629150A|2012-12-10|2013-08-15|Fuel supply|
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