WO1995004876A1 - Petrol to gas engine conversion - Google Patents

Petrol to gas engine conversion Download PDF

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Publication number
WO1995004876A1
WO1995004876A1 PCT/AU1994/000451 AU9400451W WO9504876A1 WO 1995004876 A1 WO1995004876 A1 WO 1995004876A1 AU 9400451 W AU9400451 W AU 9400451W WO 9504876 A1 WO9504876 A1 WO 9504876A1
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WO
WIPO (PCT)
Prior art keywords
ecu
gaseous fuel
gas
metering means
microcontroller
Prior art date
Application number
PCT/AU1994/000451
Other languages
French (fr)
Inventor
Victor Vrubel
Dan Vrubel
Original Assignee
Victor Vrubel
Dan Vrubel
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Victor Vrubel, Dan Vrubel filed Critical Victor Vrubel
Publication of WO1995004876A1 publication Critical patent/WO1995004876A1/en

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M21/00—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form
    • F02M21/02—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form for gaseous fuels
    • F02M21/0218—Details on the gaseous fuel supply system, e.g. tanks, valves, pipes, pumps, rails, injectors or mixers
    • F02M21/0248—Injectors
    • F02M21/0257—Details of the valve closing elements, e.g. valve seats, stems or arrangement of flow passages
    • F02M21/0272—Ball valves; Plate valves; Valves having deformable or flexible parts, e.g. membranes; Rotatable valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B69/00—Internal-combustion engines convertible into other combustion-engine type, not provided for in F02B11/00; Internal-combustion engines of different types characterised by constructions facilitating use of same main engine-parts in different types
    • F02B69/02—Internal-combustion engines convertible into other combustion-engine type, not provided for in F02B11/00; Internal-combustion engines of different types characterised by constructions facilitating use of same main engine-parts in different types for different fuel types, other than engines indifferent to fuel consumed, e.g. convertible from light to heavy fuel
    • F02B69/04—Internal-combustion engines convertible into other combustion-engine type, not provided for in F02B11/00; Internal-combustion engines of different types characterised by constructions facilitating use of same main engine-parts in different types for different fuel types, other than engines indifferent to fuel consumed, e.g. convertible from light to heavy fuel for gaseous and non-gaseous fuels
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D19/00—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
    • F02D19/02—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with gaseous fuels
    • F02D19/021—Control of components of the fuel supply system
    • F02D19/023—Control of components of the fuel supply system to adjust the fuel mass or volume flow
    • F02D19/024—Control of components of the fuel supply system to adjust the fuel mass or volume flow by controlling fuel injectors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D19/00—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
    • F02D19/06—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed
    • F02D19/066—Retrofit of secondary fuel supply systems; Conversion of engines to operate on multiple fuels
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/0025—Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
    • F02D41/0027—Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures the fuel being gaseous
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M21/00—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form
    • F02M21/02—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form for gaseous fuels
    • F02M21/0218—Details on the gaseous fuel supply system, e.g. tanks, valves, pipes, pumps, rails, injectors or mixers
    • F02M21/0248—Injectors
    • F02M21/0251—Details of actuators therefor
    • F02M21/0254—Electric actuators, e.g. solenoid or piezoelectric
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D2400/00—Control systems adapted for specific engine types; Special features of engine control systems not otherwise provided for; Power supply, connectors or cabling for engine control systems
    • F02D2400/11—After-sales modification devices designed to be used to modify an engine afterwards
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M21/00—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form
    • F02M21/02—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form for gaseous fuels
    • F02M21/0218—Details on the gaseous fuel supply system, e.g. tanks, valves, pipes, pumps, rails, injectors or mixers
    • F02M21/023—Valves; Pressure or flow regulators in the fuel supply or return system
    • F02M21/0242—Shut-off valves; Check valves; Safety valves; Pressure relief valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M21/00—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form
    • F02M21/02—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form for gaseous fuels
    • F02M21/0218—Details on the gaseous fuel supply system, e.g. tanks, valves, pipes, pumps, rails, injectors or mixers
    • F02M21/0248—Injectors
    • F02M21/0278—Port fuel injectors for single or multipoint injection into the air intake system
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/30—Use of alternative fuels, e.g. biofuels

Definitions

  • This invention relates to internal combustion engines. More particularly although not exclusively it provides an improved apparatus for enabling petrol fuel injection engines to run on gaseous fuel such as LPG.
  • the gas flow control relies on monitoring of a single parameter only such as vacuum or air flow rate and takes no account of external loads on the engine that may cause it to require more or less LPG for smooth operation and constant idle speed. More importantly these prior art systems of gas flow control are inherently slow and exhibit a significant lag in response to the engine driver's demands. This is because the method relies on monitoring vacuum and is also limited by the inertia of moving parts of the gas control system and restrictions in the air flow presented by the diaphragm and other parts.
  • this invention discloses an apparatus for enabling a fuel injected petrol engine having an electronic control unit (ECU) to operate on a gaseous fuel such as LPG, said apparatus comprising a gas metering means for connection to a pressurised source of said gaseous fuel and adapted for fitting into the air intake duct of said engine, a microcontroller which in use of the apparatus is connected between said ECU and gas metering means and is programmed to receive and translate an input signal form the ECU into an output signal for the gas metering means whereby said gas metering means may be operated to selectively control the amount of gaseous fuel entering said air intake stream in accordance with engine parameters sensed by said ECU and/or microcontroller.
  • ECU electronice control unit
  • said gas metering means is adapted for fitting into the air intake duct above the throttle valve and for injecting said gaseous fuel into the centre of the duct in the direction of air flow.
  • FIG. 1 shows a block diagram of an apparatus according to this concept for fuelling motor vehicles with LPG
  • Figure 2 is a cross-sectional view of the metering means looking along the direction of air flow in the duct.
  • Figure 3 is a cross-sectional view of part of the metering means along direction A of Figure 2,
  • Figure 4 is a view of part of the metering means along a direction opposite the direction of air flow in the duct.
  • Figures 5 and 6 are cross-sectional views along the line B-B of Figure 4,
  • Figure 7 shows examples of fuel injector signals A' from a typical ECU
  • FIG. 8 is a block diagram of a programmed microcontroller (PCM) according to this invention.
  • the apparatus may basically comprise a pressurised liquid petroleum fuel tank 1 which supplies liquid phase gas through conduit 2 to a solenoid activated safety valve 3.
  • the liquid phase gas then enters a vaporiser/pressure regulator 4 which changes it to vapour phase gas at a controlled pressure of for example 200 kPa.
  • the vapour phase gas then flows through a second safety valve 5 and via line 5A to a metering valve 6 actuated by a stepper motor 7.
  • a metered quantity of gas may thus be injected into the middle of the air intake duct 8 upstream of throttle valve 9 as shown.
  • the gas exits valve 6 in the direction of air flow and mixes with it for distribution though the intake manifold 10 to engine 11.
  • a gas control microcontroller unit 12 is connected directly to the existing ECU of a petrol fuel engine via the fuel injector lead 13 to receive input signals directly therefrom and preferably additional input from gas temperature sensor 14.
  • the microcontroller unit 12 is programmed to translate these inputs into an output signal for controlling the stepper motor 7 in combination with the gas metering valve 6.
  • the gas flow into the intake manifold is thus precisely related not only to conventional petrol fuel injected parameters such as engine speed, load, throttle position and the oxygen loop feedback but also the gas temperature/density.
  • the engine coolant temperature sensor 15 also enables the microcontroller unit to select the most suitable time for switching over from petrol to gas operation.
  • the metering valve 6 may comprise a barrel 16 which connects to gas supply line 5A and extends radially into the centre of the air intake duct 8 from a housing 17.
  • the end 18 of the barrel is closed off but a transverse slot 19 is cut partly though the circular wall of the barrel a short distance from the end.
  • Within the end section of barrel there is rotatable head 20 also with a slot 21.
  • This slot 21 in accordance with the angular position of the head aligns with slot 19 in varying degrees to allow an infinitely graduated gas flow control from the interior of the barrel to the air duct (see arrow A) between fully open position of Figure 5 to the fully closed position of Figure 6.
  • the angular position of the head is controlled by any suitable type of commercially available stepper motor 7 through shaft 22. Any suitable type of bearings may be used to support the head 20 and opposite end of the shaft 22 where it couples to the motor 7.
  • the gas flow control provides a very similar feel to the original petrol injected engine and retains the character of the engine regardless of the fuel used.
  • the engine idle is exceptionally economical and smooth.
  • the gas flow control apparatus according to this invention is smaller, cheaper and more compact than gas carburettor systems.
  • the fuel injector signal A' (shown in Figure 7) which is generated at the output of the ECU and which is used as an input to the PCM represents an ON/OFF signal for one or more petrol injectors.
  • the duration of each ON and OFF phase is precisely calculated by the ECU and depends on many input parameters such as engine speed, throttle position etc. All possible ON/OFF signal combinations are too numerous to show diagrammatically but some typical examples are depicted in Figure 7.
  • the PMC integrates by time this ON/OFF signal and converts the result to an immediate value represented by a digit say within limits of 0 to 1000 (B in Figure 8).
  • the value of 0 represents no ON pulses for injectors i.e. no petrol injected
  • the value of 1000 represents no OFF pulses for injectors, i.e. petrol injected continuously.
  • the value of 500 means that the injectors are switched ON for the same length of time as they are switched OFF.
  • the amount of gas supplied at any instant is proportional to the amount of petrol that would be injected to the engine according to the ECU signal.
  • the actual amount is represented by signal B in Figure 8. If this signal B was used to directly control the metering valve the result in maintaining the proportionality in supply of gas/petrol would not be accurate. This is because of non-linear resistance in the whole gas supply system (including safety valve, gas conduit and the metering valve itself) due to increased turbulence at higher gas flow capacities.
  • the stepper motor controlling the metering valve has to be equipped with a provision for setting its initial position in relation to the fully closed position of the metering valve.
  • the PMC is then capable of calculating the accurate position of the stepper motor (and thus the metering valve) at any time from the information about its initial position and the number of step signals sent to the stepper motor.
  • the signal reflecting the accurate position is represented by D in Figure 8.
  • the stepper motor currently proposed for controlling the metering valve according to this invention has 200 full steps per revolution.
  • the maximum usable working angle of the metering valve is 180 degrees however quick changes of valve position require the use of 90 degree angle of operation only. This results in only 50 steps being available for control of the metering valve throughout its full range from closed to fully open position.
  • stepper motor/metering valve can be adjusted in say one of 20 positions between each two full steps.
  • Microstep mode can be achieved for example by vibrating between two nearest steps with different time ratio in this example between 1:19 to 19:1.
  • the corrected signal C is compared in PMC with the memorised position D of the stepper motor. If the signals are different the PMC starts generating phase shifted pulses to turn the stepper motor in the required direction to attain the value dictated by signal C. To reach high speed and accuracy the stepper motor operates in full step mode for quick changes of valve position and in microstep mode for fine adjustments only.
  • each metering valve is manufactured with slightly differing tolerances it is necessary to have the means of adjusting the limits of its opening range.
  • the design of PMC allows adjustment to be made so that the metering valve can for example be fully closed when D value is 50 and fully open when D value is 850 while the input signal C range is from 0 to 1000.
  • the PMC preferably directly controls all safety (shut off) valves. Rotational speed of the engine is calculated at all times and when the engine stops the power is cut to close the safety valves.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
  • Output Control And Ontrol Of Special Type Engine (AREA)

Abstract

An apparatus for enabling fuel injected petrol engines having an existing electronic control unit (ECU) to operate on a gaseous fuel, comprising a gas metering means (6) connected to a pressurized gas fuel source (1) adapted to fit into the air intake duct (8) of an engine. A programmable micro-controller (12) connected between the ECU and the gas metering means (6) is programmed to receive and translate an input signal from the ECU into an output signal for the gas metering means (6).

Description

PF.TRO TO GAS ENGINE CONVERSION
This invention relates to internal combustion engines. More particularly although not exclusively it provides an improved apparatus for enabling petrol fuel injection engines to run on gaseous fuel such as LPG.
At present fuel injected petrol engines when converted for LPG operation require the back fitting of carburettor-like devices. For example it is known to control the flow of LPG by means of devices that measure the vacuum in the engine intake manifold and operate a valve that allows the entry of LPG into the engine according to the value of the vacuum. It is also known to control the flow of LPG by means of a device that operates a valve allowing the entry of LPG in accordance with the flow rate of the air entering the intake manifold. This is typically achieved by a diaphragm placed in the way of the entering air that moves according to the air flow rate and thus controls the entry of LPG into the engine.
In such systems the gas flow control relies on monitoring of a single parameter only such as vacuum or air flow rate and takes no account of external loads on the engine that may cause it to require more or less LPG for smooth operation and constant idle speed. More importantly these prior art systems of gas flow control are inherently slow and exhibit a significant lag in response to the engine driver's demands. This is because the method relies on monitoring vacuum and is also limited by the inertia of moving parts of the gas control system and restrictions in the air flow presented by the diaphragm and other parts. It is an object of this invention to ameliorate the aforementioned disadvantages and accordingly this invention discloses an apparatus for enabling a fuel injected petrol engine having an electronic control unit (ECU) to operate on a gaseous fuel such as LPG, said apparatus comprising a gas metering means for connection to a pressurised source of said gaseous fuel and adapted for fitting into the air intake duct of said engine, a microcontroller which in use of the apparatus is connected between said ECU and gas metering means and is programmed to receive and translate an input signal form the ECU into an output signal for the gas metering means whereby said gas metering means may be operated to selectively control the amount of gaseous fuel entering said air intake stream in accordance with engine parameters sensed by said ECU and/or microcontroller.
Preferably said gas metering means is adapted for fitting into the air intake duct above the throttle valve and for injecting said gaseous fuel into the centre of the duct in the direction of air flow.
The currently preferred embodiment of this invention will now be described with reference to the attached drawings in which:
Figure 1 shows a block diagram of an apparatus according to this concept for fuelling motor vehicles with LPG,
Figure 2 is a cross-sectional view of the metering means looking along the direction of air flow in the duct. Figure 3 is a cross-sectional view of part of the metering means along direction A of Figure 2,
Figure 4 is a view of part of the metering means along a direction opposite the direction of air flow in the duct.
Figures 5 and 6 are cross-sectional views along the line B-B of Figure 4,
Figure 7 shows examples of fuel injector signals A' from a typical ECU, and
Figure 8 is a block diagram of a programmed microcontroller (PCM) according to this invention.
Referring first to Figure 1 the apparatus may basically comprise a pressurised liquid petroleum fuel tank 1 which supplies liquid phase gas through conduit 2 to a solenoid activated safety valve 3. The liquid phase gas then enters a vaporiser/pressure regulator 4 which changes it to vapour phase gas at a controlled pressure of for example 200 kPa. The vapour phase gas then flows through a second safety valve 5 and via line 5A to a metering valve 6 actuated by a stepper motor 7. A metered quantity of gas may thus be injected into the middle of the air intake duct 8 upstream of throttle valve 9 as shown. The gas exits valve 6 in the direction of air flow and mixes with it for distribution though the intake manifold 10 to engine 11. A gas control microcontroller unit 12 according to this invention is connected directly to the existing ECU of a petrol fuel engine via the fuel injector lead 13 to receive input signals directly therefrom and preferably additional input from gas temperature sensor 14. The microcontroller unit 12 is programmed to translate these inputs into an output signal for controlling the stepper motor 7 in combination with the gas metering valve 6. The gas flow into the intake manifold is thus precisely related not only to conventional petrol fuel injected parameters such as engine speed, load, throttle position and the oxygen loop feedback but also the gas temperature/density. The engine coolant temperature sensor 15 also enables the microcontroller unit to select the most suitable time for switching over from petrol to gas operation.
As best shown in figures 2 to 6 the metering valve 6 may comprise a barrel 16 which connects to gas supply line 5A and extends radially into the centre of the air intake duct 8 from a housing 17. The end 18 of the barrel is closed off but a transverse slot 19 is cut partly though the circular wall of the barrel a short distance from the end. Within the end section of barrel there is rotatable head 20 also with a slot 21. This slot 21 in accordance with the angular position of the head aligns with slot 19 in varying degrees to allow an infinitely graduated gas flow control from the interior of the barrel to the air duct (see arrow A) between fully open position of Figure 5 to the fully closed position of Figure 6. The angular position of the head is controlled by any suitable type of commercially available stepper motor 7 through shaft 22. Any suitable type of bearings may be used to support the head 20 and opposite end of the shaft 22 where it couples to the motor 7.
- 4 - The above described arrangement has been found to provide a high speed and extremely accurate mixture control response which has the following advantages:
- The control continues to work in the same "closed loop" configuration as the original petrol injected engine and has no detrimental effects on the engine combustion efficiency and exhaust pollution levels as originally designed by the engine manufacturer.
- The gas flow control provides a very similar feel to the original petrol injected engine and retains the character of the engine regardless of the fuel used.
- The engine idle is exceptionally economical and smooth.
- Because of the one point electrical connection to the existing ECU the installation is simple and unified.
- The overall performance of gas flow control apparatus according to this invention surpasses all other prior.art systems.
- The gas flow control apparatus according to this invention is smaller, cheaper and more compact than gas carburettor systems.
- With dual fuel engines fitted with apparatus according to this invention the switchover to gas operation is smooth and automatic with manual override provided.
- 5 -
SUBSTITUTΕ SHEET(RULE26) The function of the programmed microcontroller (PMC) can be described in more detail as follows:
The fuel injector signal A' (shown in Figure 7) which is generated at the output of the ECU and which is used as an input to the PCM represents an ON/OFF signal for one or more petrol injectors. When the signal is ON the petrol flows through the injectors and when the signal is OFF the flow of petrol is completely stopped. The duration of each ON and OFF phase is precisely calculated by the ECU and depends on many input parameters such as engine speed, throttle position etc. All possible ON/OFF signal combinations are too numerous to show diagrammatically but some typical examples are depicted in Figure 7.
Referring now to Figure 8 the PMC integrates by time this ON/OFF signal and converts the result to an immediate value represented by a digit say within limits of 0 to 1000 (B in Figure 8). As an example in this conversion the value of 0 represents no ON pulses for injectors i.e. no petrol injected, the value of 1000 represents no OFF pulses for injectors, i.e. petrol injected continuously. The value of 500 means that the injectors are switched ON for the same length of time as they are switched OFF.
When the engine is operated on gas it is desirable that the amount of gas supplied at any instant is proportional to the amount of petrol that would be injected to the engine according to the ECU signal. The actual amount is represented by signal B in Figure 8. If this signal B was used to directly control the metering valve the result in maintaining the proportionality in supply of gas/petrol would not be accurate. This is because of non-linear resistance in the whole gas supply system (including safety valve, gas conduit and the metering valve itself) due to increased turbulence at higher gas flow capacities.
In order to eliminate the above problem a correction is introduced to signal B by way of a specific correction map created by plotting the actual gas flow through the metering valve against the input control signal from ECU (B in Figure 8). The corrected signal is represented by signal C.
The stepper motor controlling the metering valve has to be equipped with a provision for setting its initial position in relation to the fully closed position of the metering valve. The PMC is then capable of calculating the accurate position of the stepper motor (and thus the metering valve) at any time from the information about its initial position and the number of step signals sent to the stepper motor. The signal reflecting the accurate position is represented by D in Figure 8.
The stepper motor currently proposed for controlling the metering valve according to this invention has 200 full steps per revolution. The maximum usable working angle of the metering valve is 180 degrees however quick changes of valve position require the use of 90 degree angle of operation only. This results in only 50 steps being available for control of the metering valve throughout its full range from closed to fully open position. Such
- 7 - limitation in precise control has been overcome by the design of PMC which allows the control of the stepper motor in microstep mode. For higher accuracy the stepper motor/metering valve can be adjusted in say one of 20 positions between each two full steps. Microstep mode can be achieved for example by vibrating between two nearest steps with different time ratio in this example between 1:19 to 19:1.
The corrected signal C is compared in PMC with the memorised position D of the stepper motor. If the signals are different the PMC starts generating phase shifted pulses to turn the stepper motor in the required direction to attain the value dictated by signal C. To reach high speed and accuracy the stepper motor operates in full step mode for quick changes of valve position and in microstep mode for fine adjustments only.
Because each metering valve is manufactured with slightly differing tolerances it is necessary to have the means of adjusting the limits of its opening range. The design of PMC allows adjustment to be made so that the metering valve can for example be fully closed when D value is 50 and fully open when D value is 850 while the input signal C range is from 0 to 1000.
The PMC preferably directly controls all safety (shut off) valves. Rotational speed of the engine is calculated at all times and when the engine stops the power is cut to close the safety valves. It will thus be appreciated that this invention at least in the form of the embodiment described provides a novel and useful improvement to existing LPG installations on motor vehicles. Clearly however the example disclosed is only the currently preferred form of this invention and a wide variety of modifications may be made which would be apparent to a person skilled in the art. For example the configuration of the metering valve and functions of the PCM may all be changed according to design preference. Also the engine parameters monitored may be changed according to application.

Claims

The claims defining the invention are as follows:
1. An apparatus for enabling a fuel injected petrol engine having an electronic control unit (ECU) to operate on a gaseous fuel, said apparatus comprising a gas metering means for connection to a pressurised source of said gaseous fuel and adapted for fitting into the air intake duct of said engine, a microcontroller which in use of the apparatus is connected between said ECU and gas metering means and is programmed to receive and translate an input signal from the ECU into an output signal for the gas metering means whereby said gas metering means may be operated to selectively control the amount of gaseous fuel entering said air intake stream in accordance with engine parameters sensed by said ECU and /or microcontroller.
2. The apparatus as claimed in claim 1 wherein said gas metering means is adapted for fitting into the air intake duct above the throttle valve and for injecting said gaseous fuel into the centre of the duct in the direction of air flow.
3. The apparatus as claimed in claim 2 wherein the metering means comprises a barrel which is connectable to a gas supply line from said source of gaseous fuel and which may extend from a housing into the centre of the air supply duct, the operative end of the barrel including a slot through the wall thereof, and a slotted head rotatable within said barrel by a stepper motor so that the slot in said head aligns with the slot in said barrel in varying degrees to allow a graduated gas flow from the barrel into the air intake duct.
4. The apparatus as claimed in claim 3 wherein the stepper motor is activated to rotate said head in accordance with said output from the microcontroller.
5. The apparatus as claimed in claim 4 wherein the stepper motor is linked to the slotted head by means of a shaft extending the interior length of the barrel.
6. The apparatus as claimed in claim 5 wherein the microcontroller is conectable directly to the ECU by the existing fuel injector lead.
7. The apparatus as claimed in claim 6 wherein the microcontroller also receives input from an engine coolant temperature sensor and a gaseous fuel temperature sensor.
8. The apparatus as claimed in claim 7 wherein said gaseous fuel is LPG.
9. The apparatus as claimed in claim 8 wherein the microcontroller is adapted to select the most suitable time for switching from petrol to said gaseous fuel.
10. A motor vehicle fitted with apparatus as claimed in any one of claims 1 - 9.
- 11-
PCT/AU1994/000451 1993-08-06 1994-08-05 Petrol to gas engine conversion WO1995004876A1 (en)

Applications Claiming Priority (2)

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AUPM0400 1993-08-06
AUPM040093 1993-08-06

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Cited By (15)

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DE19539170A1 (en) * 1995-10-20 1997-04-24 Bayerische Motoren Werke Ag Operating method for road vehicle internal combustion engine
EP0872634A1 (en) * 1997-04-17 1998-10-21 Marco Bianchi Method and apparatus for feeding internal combustion engines with gaseous fuels
FR2768463A1 (en) * 1997-09-12 1999-03-19 Michel Blandin Indirect fuel injection with pressure regulation for IC engines
FR2780754A1 (en) * 1998-07-01 2000-01-07 Siemens Ag DEVICE FOR DETERMINING A SIZE WHICH CHARACTERIZES THE AIR MASS IN A CYLINDER OF AN INTERNAL COMBUSTION ENGINE
WO2004106722A2 (en) * 2003-05-27 2004-12-09 Avl List Gmbh Internal combustion engine
GB2437098A (en) * 2006-04-12 2007-10-17 Clean Air Power Ltd Dual fuel engine with respective fuel type controllers.
EP1890021A1 (en) * 2006-08-11 2008-02-20 GREENCAR Consult GmbH & Co. KG Method for converting a diesel engine for liquid gas, combustion engine and actuating device for operating a combustion motor with liquid gas
CN100434667C (en) * 2006-12-21 2008-11-19 上海交通大学 General gasoline engine power system for water surface and underwater vehicle
US20120266846A1 (en) * 2011-04-25 2012-10-25 Michael Kilbourne Dual fuel diesel engine system
US8616177B2 (en) 2010-02-11 2013-12-31 Wisconsin Alumni Research Foundation Engine combustion control via fuel reactivity stratification
ITRE20120091A1 (en) * 2012-12-03 2014-06-04 Alberto Castagnini VARIABLE FLOW GAS INJECTOR FOR ENDOTHERMIC MOTORS
US8851045B2 (en) 2011-03-31 2014-10-07 Wisconsin Alumni Research Foundation Engine combustion control at low loads via fuel reactivity stratification
US9057321B2 (en) 2012-01-24 2015-06-16 Wisconsin Alumni Research Foundation Fuel reactivity stratification in rotary diesel engines
US9915235B2 (en) 2015-10-02 2018-03-13 Wisconsin Alumni Research Foundation Engine combustion control at high loads via fuel reactivity stratification
CN114483324A (en) * 2022-01-10 2022-05-13 江苏大学 Binary coding digital valve array regulated and controlled fuel metering valve and control method thereof

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WO1989000640A1 (en) * 1987-07-10 1989-01-26 Gaspower Limited Improvements in or relating to fuel injection
WO1992008888A1 (en) * 1990-11-20 1992-05-29 Biocom Pty. Ltd. A dual fuel injection system and a method of controlling such a system
US5092305A (en) * 1990-11-26 1992-03-03 Gas Research Institute Apparatus and method for providing an alternative fuel system for engines

Cited By (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19539170A1 (en) * 1995-10-20 1997-04-24 Bayerische Motoren Werke Ag Operating method for road vehicle internal combustion engine
EP0872634A1 (en) * 1997-04-17 1998-10-21 Marco Bianchi Method and apparatus for feeding internal combustion engines with gaseous fuels
FR2768463A1 (en) * 1997-09-12 1999-03-19 Michel Blandin Indirect fuel injection with pressure regulation for IC engines
FR2780754A1 (en) * 1998-07-01 2000-01-07 Siemens Ag DEVICE FOR DETERMINING A SIZE WHICH CHARACTERIZES THE AIR MASS IN A CYLINDER OF AN INTERNAL COMBUSTION ENGINE
WO2004106722A2 (en) * 2003-05-27 2004-12-09 Avl List Gmbh Internal combustion engine
WO2004106722A3 (en) * 2003-05-27 2005-05-12 Avl List Gmbh Internal combustion engine
GB2437098A (en) * 2006-04-12 2007-10-17 Clean Air Power Ltd Dual fuel engine with respective fuel type controllers.
GB2437098B (en) * 2006-04-12 2010-06-09 Clean Air Power Ltd Gas-Fueled Compression Ignition Engine having OEM-type Liquid Fuel Controller
EP1890021A1 (en) * 2006-08-11 2008-02-20 GREENCAR Consult GmbH & Co. KG Method for converting a diesel engine for liquid gas, combustion engine and actuating device for operating a combustion motor with liquid gas
CN100434667C (en) * 2006-12-21 2008-11-19 上海交通大学 General gasoline engine power system for water surface and underwater vehicle
US9080501B2 (en) 2010-02-11 2015-07-14 Wisconsin Alumni Research Foundation Engine combustion control via fuel reactivity stratification
US8616177B2 (en) 2010-02-11 2013-12-31 Wisconsin Alumni Research Foundation Engine combustion control via fuel reactivity stratification
US9376955B2 (en) 2010-02-11 2016-06-28 Wisconsin Alumni Research Foundation Engine combustion control via fuel reactivity stratification
US8851045B2 (en) 2011-03-31 2014-10-07 Wisconsin Alumni Research Foundation Engine combustion control at low loads via fuel reactivity stratification
US9850812B2 (en) 2011-03-31 2017-12-26 Wisconsin Alumni Research Foundation Engine combustion control at low loads via fuel reactivity stratification
US20120266846A1 (en) * 2011-04-25 2012-10-25 Michael Kilbourne Dual fuel diesel engine system
US9057321B2 (en) 2012-01-24 2015-06-16 Wisconsin Alumni Research Foundation Fuel reactivity stratification in rotary diesel engines
ITRE20120091A1 (en) * 2012-12-03 2014-06-04 Alberto Castagnini VARIABLE FLOW GAS INJECTOR FOR ENDOTHERMIC MOTORS
US9915235B2 (en) 2015-10-02 2018-03-13 Wisconsin Alumni Research Foundation Engine combustion control at high loads via fuel reactivity stratification
CN114483324A (en) * 2022-01-10 2022-05-13 江苏大学 Binary coding digital valve array regulated and controlled fuel metering valve and control method thereof
CN114483324B (en) * 2022-01-10 2023-06-09 江苏大学 Fuel metering valve regulated and controlled by binary coded digital valve array and control method thereof

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