VEHICLE FUEL TANK MANAGEMENT

Abstract: A vehicle engine management system includes a single engine control unit (4) with a control/processor (22) and store devices (23-25). The vehicle can be powered by gas fuel from tank (27) via gas injectors (6) or by petrol from tank (8) via petrol injectors (2). The control (22) determines whether gas or petrol is utilised dependent on driving conditions using mapping (23, 24). To refuel the vehicle a cycle of operations is carried out by control (22) using the sequences stored in device (25). The presence of a connected gas supply is determined via detector (13a) and gas tank pressure via sensor (27a) and a compressor (28) is operable during the cycle to refuel the tank. Refilling automatically terminates and after this the car can be driven away when fuel line decoupling is detected.

Description: VEHICLE FUEL TANK MANAGEMENT The invention relates to an engine management system arrangement typically for a passenger vehicle. In petrol (gasoline) cars an electronic engine management system is provided which controls the operation of fuel injectors supplying fuel to the engine so as to maximise effectiveness in dependence on load, speed and other sensed conditions. In bi-fuel vehicles such as for petrol and natural gas there is a need to provide electronic engine management systems for both fuels. The present invention is concerned with utilising an engine management system to assist in refuelling such a bi-fuel vehicle with gas. According to the invention there is provided a multiple fuel vehicle management system for operating a motor vehicle on either gas or liquid fuel during normal road use and including means for controlling an automatic refill cycle to fill a gas tank at high pressure from a low pressure gas supply in response to sensed information from sensors within the vehicle. Further according to the invention there is provided a method of managing the operation of a multiple fuel motor vehicle, including the steps of operating the vehicle on either gas or liquid fuel during normal road use and controlling the vehicle when stationary to provide an automatic refill cycle following receipt of an initiating signal, the cycle including the steps of sensing the presence of a gas supply the source and filling a gas tank with high pressure gas derived from a low pressure source. According to a further aspect of the invention there is provided a program on a carrier for controlling the operation of gas fuel utilisation vehicle in use, the program providing a refuelling cycle includes the steps of detecting the presence of a source of low pressure gas fuel, detecting the pressure of gas stored within a tank mounted on the vehicle, determining whether tank pressure is such as to be capable of replenishment, providing an operation signal for a compressor to power up a compressor during a period required to replenish stored gas fuel and terminating the power up when detecting pressure meets requirements. The invention is now described by way of example with reference to the accompanying drawings in which: Figure 1 shows a bi-fuel vehicle with facilities for gas refuelling with an on-board compressor; Figure 2 shows aspects of the vehicle in more detail including the electronic control mechanism for all three operations with a single unit; Figure 3A and 3B shows the flowchart associated with the refuelling operation; and Figure 4 shows a more detailed configuration of the onboard gas compression of the supply. In a petrol vehicle an engine management arrangement including an electronic control unit (ECU) controls fuel injectors which ECU controls the fuel intake and engine speed and so on, by utilising vehicle sensors and actuators at various points within the vehicle. Where bi-fuel capability is required, compressed natural gas is utilised in addition to the petrol (gasoline) or diesel liquid fuel. The arrangement of Figure 1 shows a bi-fuel vehicle 100 with the capability of gas refuelling with on-board compression and control. The vehicle includes an engine block 7 with both petrol injectors 2 and gas injectors 6 associated with an inlet manifold 3. In addition to accommodating the injectors 2 and 6 the manifold will accommodate the suction intakes from the brake servo, petrol tank vapour canister " discharge, engine crankcase ventilation and the like. Such a manifold is described in more detail in our copending patent application. A throttle 5 regulates the air intake to the engine under the control of the ECU 4. Gas will pass from gas tank 27 through pipe 15 to the injectors 2 and petrol will pass from petrol tank 8 through pipe 16 to injectors 6. The petrol tank 8 is refilled via filler point 14. The gas stored in tank 27 is at high pressure (typically 200 bar) and this is obtained from a low pressure source, typically a domestic natural gas source 17 at 1 bar and is made available to the vehicle via a low pressure quick release hose 12 coupled to the gas filling point 13 mounted on the vehicle. This low pressure gas passes through hose 36 and is converted into high pressure via the compressor 28 mounted in the region of the gas tank 27. The compressor is operated using vehicle power as described in more detail below. The petrol tank 8 at least partially surrounds the gas tank 27 to act as impact buffer and to provide dual fuels storage from a compact source of storage. The gas tank could typically have a capacity of 17 litres and the petrol tank a capacity of 50 litres. The ECU 4 is configured to provide three modes of operation. The first is to control the provision of vehicle power using petrol as the fuel. The second is to control the provision of vehicle power using gas as the fuel. The third is to control the provision of vehicle power to drive the compressor refuelling sequence . The manner in which this can be achieved is described in more detail with reference to Figure 2. In an ECU, used for petrol vehicle control the device receives information from vehicle sensors and uses this information to control the petrol injectors. The ECU determines the flowrate of air via the throttle and the correct amount of petrol for each cylinder intake stroke dependent on sensed information. The quantity of fuel is determined from stored information, known as mapping or calibration, of the engine speed and load, temperature, throttle position, ignition timing, air/fuel ratio, exhaust emissions and other powertrain sensors specific to the model of engine fitted. Such an arrangement is replicated in the present configuration by the control/processor 22 and the storage area 23. The control 22 together with stored mapping controls the petrol injectors via electric- connections 19. The throttle has the electrical connection 43. The known engine sensors mentioned above are shown collectively as being received by input 44. In the present vehicle, however, two other operations are envisaged and to keep down costs and size as well as to maximise control effectiveness, these have been incorporated into the same ECU 4, by the provision of additional storage areas 24 and 25 and extended programming control. The same control 22 (e.g. a microprocessor) can be utilised for all three functions as now described. For the sake of simplicity any interfacing for the sensors and power output stages for actuating the controls are omitted. For gas operation, the petrol injectors 2 are no longer used and the gas injectors 6 come into play. The gas supplied to the injectors will typically be at a pressure of 7 bar, having been reduced from the tank pressure via regulator 20. The gas injectors operate in a similar manner to the petrol injectors, but the amount of gas fuel mixing with the air will be different for the same set of circumstances. To accommodate this change, a separate mapping store 24 is provided. The existing engine sensors can be employed to provide intelligence on conditions to allow the gas mapping to be effective. Hence the throttle position will be different but the throttle position sensor will provide an output via electrical cable 43 to the control 22. The injectors 6 will be pulsed to open a needle valve against spring pressure using an internal electromagnetic coil within the injector housing via control cable 19. The control 22 can be programmed to make the decision as to which fuel is the most appropriate and this can be determined from sensed parameters such as load, speed and fuel capacity remaining. Sensor 27a is provided to supply information on gas pressure indicative of volume in the tank 27 via cable 42. In such an embodiment, the switchover of fuel will be effected without any noticeable change of handling of the vehicle by the driver. It may be preferable, however, to include an indicator device 45 to display to the driver what fuel source is currently employed. In addition to the bi-fuel operation, the vehicle has the capability to allow refuelling at a convenient gas supply source at the driver's house, for example. The driver can initiate the gas refill cycle once the vehicle is parked and the low pressure hose is connected to the gas filling point as detected by sensor 13a via- lead 41. The ECU 4 controls operation of the compressor 28 via lead 46. The compressed gas begins to fill the tank 27 and pressure information is available to the ECU from sensor 27a via lead 42. The cycle can be arranged to be automatic so that replenishment is effected without further intervention from the driver once manual initiation is instigated using the stored sequence information stored in store 25 within the ECU 4. A flow chart shown in Figure 3A and 3B illustrates the steps and decisions programmed into the ECU 4 to allow the automatic sequence to operate. Although not shown on the flow chart, for simplification the presence of the low pressure quick release hose and other parameters could in practice be continuously monitored during the cycle. After the manual initiation by means of a designated switch the program follows a sequence of steps and checks to ensure safe operation automatically. The detection of an error will trigger an audible/visual alarm. The visual alarm could comprise a display unit with indicia relating to the particular detected event. This could be incorporated in an expanded display 45. Hence in operation, for example if the hose is determined not to be connected this will result in an indication or prompt on the display. The on-board compressor arrangement utilised during the automatic cycle is described in more detail in Figure 4. The compressor 28 is a two stage compressor of the type disclosed in our copending patent application. It includes a body portion 50 which includes a first cylindrical chamber 51 and a second smaller cylindrical chamber 52. Rams A and B are connected by rod 54 and hydraulic fluid under pressure simultaneously pushes piston A and pulls piston B during part of the operational cycle. This allows gas received externally via coupling 13 and duct 36 to be drawn into chamber 51. On completion of the stroke, the hydraulic pressure rises rapidly and a spool valve 34 switches and causes hydraulic fluid to force the rod 54 in the reverse direction so compressing the gas in chamber 51. The compressed gas passes via conduit 55 and valve 56 into the now open chamber 52 to provide a second stage of compression, once the hydraulic fluid reverses flow on actuation of the spool valve into its second bistable position. After the second stage of compression the compressed gas is allowed to exit to the storage tank 27. The hydraulic fluid spool valve 34 ensures that correct passage of the hydraulic fluid is maintained. The power to drive the hydraulic fluid is provided by an electric motor 30 via a belt 31 to hydraulic pump 29 under the control of the ECU 4. Fluid passes to the compressor 28 under the switching action of spool valve 34 to allow second stage compression of the gas whilst the first stage intake is occurring and vice versa. The compressor may be cooled internally by liquid in a reservoir 35 passing through a radiator 32 and filter 33 in the vehicle engine cooling system. This may be simplified by using a hydraulic pump 29 designed to operate with a glycol based fluid so that the coolant in the engine cooling system can be used directly to power and cool the compressor without the need for an intermediate fluid or secondary cooling circuit. The electrical power is provided by the engine running to generate electricity via an alternator (not shown) . This avoids draining the battery. It would also be possible to utilise a hydraulic pump directly linked to the engine as in the manner employed with a power steering pump. The on-board arrangement utilising the common ECU avoids long recharging times when a low pressure source of natural gas is available. A recharge cycle of 30 minutes or less is possible. Typical gas flowrates and pressures for the on-board compressor for a passenger road vehicle are given in the following table. The arrangement shown in the example is for a naturally aspirated engine. This arrangement could also be applied to turbocharged or blown systems, where air is forced through the manifold by an external fan or blower rather than being drawn into the engine by suction from- the engine cylinders as each piston performs an intake stroke, or to more recent engine technologies which employ air ram and direct fuel injection. The vehicle ECU will normally be programmed to use the compressed natural gas as the preferred fuel but in use where operational load or speed requirements favour the liquid fuel (e.g. petrol) the system automatically switches over without noticeable loss of power. When changing between fuels under load, the ECU can be programmed to switch in steps such that the gas injectors switch over in sequence rather than all together to ensure an smooth changeover over several engine revolutions between each injector switching. Hence the switchover may occur over 30 or more revolutions .

Claims: CLAIMS 1 . A multiple fuel vehicle management system for operating a motor vehicle on either gas or liquid fuel during normal road use and including means for controlling an automatic refill cycle to fill a gas tank at high pressure from a low pressure gas supply in response to sensed information from sensors within the vehicle . 2. A system wherein the management system is configured to share a common control device and including a compressor and mounted on the vehicle utilising power available for the vehicle under the control of the common device. 3. A system as claimed in claim 2 wherein the compressor is constructed to use pressurised hydraulic fluid to compress the gas by means of at least one operational compression stage. 4. A system as claimed in claim 3 wherein the pressurised hydraulic fluid is provided by pump means operated during a running period of the vehicle engine. 5. A system as claimed in claims 1, 2 or 3 wherein pressurised hydraulic fluid is provided by electric pump means operated by electrical power derived from the vehicle. 6. A system as claimed in any preceding claim wherein the means for controlling the automatic cycle includes means for initiating engine start up, means for monitoring gas pressure during refuelling and means for shutting down of the engine when refuelling requirements are detected to have been met. 7. A system as claimed in claim 5 wherein the means for controlling the automatic cycle includes means for inhibiting driving operation of the vehicle during the refuelling cycle. 8. A system as claimed in claim 1 wherein the means for controlling the automatic refill cycle includes first detector means for detecting the presence of a source of low pressure gas fuel, first detector means for detecting stored gas pressure from a vehicle storage tank, compressor means for compressing gas from the low pressure source and control means for automatically powering the compressor means during the period required to replenish stored gas as determined by information from the second detector means. 9. A system as claimed in claim 8 wherein the control means includes automatic vehicles immobilisation means to prevent movement of the vehicle when an external source of low pressure gas fuel is connected to the vehicle and means for automatically activating vehicle- power to facilitate driving of the compressor means during the refill cycle. 10. A method of managing the operation of a multiple fuel motor vehicle, including the steps of operating the vehicle on either gas or liquid fuel during normal road use and controlling the vehicle when stationary to provide an automatic refill cycle following receipt of an initiating signal, the cycle including the steps of sensing the presence of a gas supply the source and filling a gas tank with high pressure gas derived from a low pressure source. 11. A method as claimed in claim 10 including the step of compressing the gas to convert it to high pressure and powering the compressing step by means of power derived from the vehicle. 12. A method as claimed in claim 11 including the step of initiating engine start-up, monitoring gas pressure within a tank during refuelling and shutting down engine operation when monitored gas pressure reaches a predetermined value. 13. A method as claimed in claim 12 including the step of inhibiting vehicle movement during the refuelling cycle. 14. A method as claimed in any one of claims 10 to 13 including the steps of detecting correct coupling of a gas hose for gas supply during refilling, detecting engine speed, detecting compressor operation and providing indication to a driver in the vehicle as to any error status associated with such operations. 15. A program on a carrier for controlling the operation of gas fuel utilisation vehicle in use, the program providing a refuelling cycle includes the steps of detecting the presence of a source of low pressure gas fuel, detecting the pressure of gas stored within a tank mounted on the vehicle, determining whether tank pressure is such as to be capable of replenishment, providing an operation signal for a compressor to power up the compressor during a period required to replenish stored gas fuel and terminating the power up when detected pressure meets requirements. 16. A program as claimed in claim 15 including the steps of providing control signals to operate the vehicle on either gas or liquid fuel during normal use and switching to the refuelling cycle following receipt of a refuelling cycle request. 17. A multiple fuel management system substantially as- described herein with reference to the accompanying drawings . 18. A method of managing the operation of a multiple fuel motor vehicle substantially as described. 19. A program on a carrier for controlling the operation of a gas fuel utilisation vehicle, in use, substantially as described with reference to the drawings .

Inventors: BRIGHTWELL ALAN, LACEY NIGEL RAYMOND, WEDGE PHILIP JOHN, BRIGHTWELL, ALAN, LACEY, NIGEL RAYMOND, WEDGE, PHILIP, JOHN
Applicants: BG INTELLECTUAL PTY LTD, BRIGHTWELL ALAN, LACEY NIGEL RAYMOND, WEDGE PHILIP JOHN, BG INTELLECTUAL PROPERTY LTD., BRIGHTWELL, ALAN, LACEY, NIGEL RAYMOND, WEDGE, PHILIP, JOHN
Application year: 1999
Main classification: B60K15
IPC codes: B60K13, B60K15, F02D17, F02D19, F02D29, F02D41, F02D45, F02M21, F02M35, F02M37, F17C1