GB2458500A

GB2458500A - A method of and system for fuel injected internal combustion engines

Info

Publication number: GB2458500A
Application number: GB0805221A
Authority: GB
Inventors: Edward Christopher Zyla; Mark Vincent Howarth; Gary Michael Mcmahon
Original assignee: HYBRID COMB Ltd
Current assignee: HYBRID COMB Ltd
Priority date: 2008-03-20
Filing date: 2008-03-20
Publication date: 2009-09-23
Also published as: WO2009115845A1; GB0805221D0; EP2279339A1

Abstract

A method of improving the fuel efficiency of electrically controlled fuel injected internal combustion engines, and including a system adapted to interrupt a control signal from an engine management computer or power train control module (PCM) (15) to a fuel injector (11) comprising a current sensor (17) adapted to measure the duration of a pulsed supply of fuel to the injector, a switching block (18) to interrupt the supply if required, and a microprocessor (22) to actuate the switching block and to produce a signal which may be used to effect injection into the engine of a secondary fuel or shorter molecular structure thus to achieve, as far as possible, homogenous combustion within the engine.

Description

A METHOD OF AND SYSTEM FOR IMPROVING THE FUEL EFFICIENCY OF

ELECTRONICALLY CONTROLLED FUEL INJECTED INTERNAL

COMBUSTION ENGINES

This invention is concerned with improving the fuel efficiency of fuel injected diesel or petrol engines in order to effect within the engine the principle of homogenous combustion, i.e., to ensure that fuel is utilised (burnt) as fully as possible thus improving the efficiency of the engine and bringing about a reduction of harmful exhaust emissions.

it is known that hydrocarbon fuels such as diesel have a molecular structure which is long and complex and when combusted in an engine creates hot spots within the combustion chamber which prevents some hydrocarbon fractions from burning fully. Again in the case of diesel engines this is largely responsible for smoke and particulate matter issuing from the exhaust system of the engine.

It is an object of the present invention to ensure a more complete burn of the hydrocarbon fuel while reducing the mean combustion temperature within the combustion chamber resulting in increased energy transfer and enabling a reduction in fuel consumption.

Typically, a conventional diesel engine on a heavy commercial vehicle has an effective diesel burn of between 75% and 80% of its total capability and it is a further object of the present invention to increase this to a level much closer to 100%.

According to a first aspect of the present invention, there is provided a method of improving the fuel efficiency of an electronically controlled fuel injected internal combustion engine, comprising the steps of controlling the quantity of a first fuel having a first molecular structure injected into a combustion chamber of the engine during a combustion cycle, and sequentially supplying to the combustion chamber a controlled proportional quantity of a second fuel of a shorter molecular structure.

The controlled quantity of the first fuel injected into the combustion chamber may be determined by a microprocessor which produces a signal to determine the proportional quantity of the second fuel and the sequential timing of injection thereof into the combustion chamber.

The controlled quantity of the first fuel may be determined by measuring the normal duration of a pulsed supply of the first fuel by an injector as determined by an engine management computer or powertrain control module (PCM), and, if required, interrupting the pulsed supply at a predetermined point in time, the proportional quantity of the second fuel being injected into the combustion chamber at a subsequent point in time coincident with a combustion stroke of the engine.

The controlled quantity of the first fuel may be determined by monitoring the duration of the supply of the first fuel by an injector in relation to a signal representative of the instantaneous fuel pressure derived from a fuel pump, and interrupting the supply at a predetermined point in time.

A signal may be sent to the fuel pump to modify the fuel pressure in addition to, or as an alternative to, modification of the duration of a pulsed fuel supply to the combustion chamber of the engine.

The first fuel may be diesel.

I'he second fuel may be liquefied petroleum gas (LPG).

The second fuel may be hydrogen.

The second fuel may comprise two or more different fuels of different molecular structures.

The second fuel may be injected into the air stream supplied to the combustion chamber of the engine.

According to a second aspect of the present invention there is provided a system for improving the fuel efficiency of an electronically controlled fuel injected internal combustion engine, comprising means for connection to the fuel supply system of the engine, means for controlling the quantity of a first fuel having a first molecular structure injected into a combustion chamber of the engine during a combustion cycle, and means for sequentially supplying to the combustion chamber a proportional quantity of a second fuel of a shorter molecular structure The system may be adapted for connection between an engine management computer (ECU) and a fuel injector for the engine thus to interrupt the signals issued by the PCM to the injector and to supply modified signals to the injector.

The system may comprise means for measuring the normal duration of a pulsed supply of a first fuel to the injector, means for modifying the pulsed length of the supply of the first fuel, a microprocessor for receiving signals from the measuring means and for transmitting signals to the pulsed length modifying means, and adapted to produce and transmit a resultant signal to means for sequentially supplying a proportional quantity of the second fuel.

The system may include means to monitor the instantaneous pressure of the first fuel derived by a fuel pump and to modify the pressure as a parameter of the supply of the first fuel to the engine.

The pressure monitoring means may be the microprocessor adapted to receive signals from, and transmit signals to, the fuel pump.

l'he microprocessor may be connected to the PCM and adapted to transmit signals thereto representative of the overall fuel supply to the engine, thus to emulate normal engine operational conditions as monitored by the PCM.

The means for measuring the normal duration of the pulsed supply of the first hydrocarbon fuel to the injector may be a Hall Effect current sensing device producing an analogue signal, and connected, via an analogue to digital converter, to the microprocessor.

l'he means for modifying the pulsed length of the supply of the first hydrocarbon fuel to the injector may be an optically coupled MOSFET switching block connected to the microprocessor.

The Hall Effect current sensor and the optically coupled MOSFET switching block may provide a low-resistance, electrically conductive path completing a circuit between the PCM and the injector.

An opto-coupler may be connected in parallel to the optically coupled MOSFET switching block to detect any potential difference during an "off' state of the switching block.

According to a third aspect of the present invention there is provided an electronically controlled fuel injected internal combustion engine comprising at least one combustion chamber, a fuel injector connected to the combustion chamber and to a supply of a first fuel having a first molecular structure, a microprocessor connected to the injector and adapted to control the duration of a pulsed supply of the first fuel to the injector, means to interrupt the supply of the first fuel to the injector at a point in time during a combustion cycle, and means for sequentially supplying to the combustion chamber a proportional quantity of a second hydrocarbon fuel of a shorter molecular structure.

An embodiment of the invention, as applied to a diesel engine, will now be described, by way of example only, with reference to the accompanying drawings, in which: Fig. I is a diagram representing the manner of operation of the system to be described; and F'ig. 2 is a circuit diagram of the system as applied to the PCM and each fuel injector of an engine.

The method of and system for improving the fuel efficiency of an electronically controlled fuel injected diesel engine, in accordance with the invention, is intended to bring about, as completely as possible, homogenous combustion within each cylinder or combustion chamber of the engine in order most effectively to burn the entire quantity of diesel fuel supplied to the combustion chamber and thus increase the effective diesel burn from between 75% to 80% as typically experienced in a conventional diesel engine, to something in the region of 98% to 99% ie, almost 100%.

This is achieved by electronically reading the signal to each fuel injector, as supplied by the engine management computer or powertrain control module (PCM) and, if necessary, cross-referencing data pulses derived from these signals with a pressure reading from the fuel supply pump, and then controlling the exact amount of a primary fuel being supplied to the engine by each injector. This then triggers a second signal which is used to control a secondary fuel injector which proportionally injects a correct amount of a secondary fuel of a shorter molecular structure than the primary fuel to increase the optimum burn, i.e., to achieve, as far as possible, homogenous combustion. The secondary fuel system is a sequential injection system which applies the secondary pulse in an appropriate timing pattern The system imposes a control over the fuelling mechanism which, if required, can vary the fuel pressure andlor the duration of the pulsed supply of diesel fuel to the engine.

Thus, the normal performance characteristics can be maintained while efficiency is increased.

Electronic fuel injection systems currently available vary considerably in characteristics according to different fuel types, and seek to address the ever increasing demands for improved performance, efficiency and lower exhaust emissions. While these systems share the same basic principle of injecting fuel into an internal combustion engine via an electronically controlled valve known as an injector, the control technology and the design of the injectors themselves vary considerably across the range of systems available. Therefore, in order to impose control over the efficiency of such an engine the applicants have developed a system which can be applied universally to most, if not all, electronic fuel injection systems irrespective of the differences in their design and performance characteristics.

Referring now to Fig 1, the system of the present invention is illustrated diagrammatically at 3 and is adapted to receive signals monitoring the injection pulses 1 applied to each injector from the engine management computer (15 in Fig. 2). These may consist of individual pulses or groups of pulses per engine cylinder combustion stroke.

The total injection duration is calculated in system 3 and multiplied by a relative voltage 2 representing the fuel pressure derived from a fuel supply pump (16a in Fig. 2). Output data is generated at 4 representing the total fuel quantity delivered to the combustion chamber, and this may consist of one or more of an individual pulse 4a, per combustion, of variable pulse width, a variable voltage/current analogue output 4b, a digital output 4c, or a combination of all three.

Referring now to Fig. 2, a dotted line X represents a point of connection of the system illustrated below the line X, to an engine management computer or powertrain control module (PCM) and the engine injectors, which are represented above the line X. Therefore, the engine to which this system is to be connected will include a series of fuel injectors 11 in the form of electrically operated valves, all connected to a common fuel supply iail 12, an engine management computer (PCM) 15 and a fuel pump 16a. A pressure sensor 13 produces a signal representative of the instantaneous fuel pressure in the rail 12 and transmits the signal to the PCM 15 which is connected also the fuel pump 1 6a.

The system of the invention is connected to the components above the line X by interrupting the normal circuit from the PCM 15 to each injector Ii as shown at 14, and so an entire system as illustrated below the line X is required and connected between the PCM 15 and each of the injectors 11.

Therefore, the intercepted circuit 14 is replaced by a circuit including a Hall Effect current sensing device 17 and an optically coupled MOSFET switching block 18. The resultant circuit illustrated by thickened line Y provides a low-resistance, electrically conductive path thus completing the circuit and ensuring any changes made to the injector control circuit characteristics by its insertion are negligible, and completing the circuit between the PCM and the injector.

An opto-coupler 19 is connected in parallel with the MOSFET switching block 18 to enable detection of any potential difference in the circuit during the MOSFET "of?' state, duting operation. The opto-coupler 19 is connected to a microprocessor 22, an output of which is also connected to the MOSFET switching block 18 while the analogue signal from the Hall Effect current sensor 17 is supplied via a multiplex analogue to digital converter (ADC) 20 to the microprocessor 22. The signal from the pressure sensor 13 is also connected to the microprocessor 22 via ADC 20.

Any or all external circuits having an affect upon or receiving effective signals from the system, are represented at 21 and are thus connected to the microprocessor 22 both to receive signals from and to transmit signals to the latter.

As shown at I 7b, there is a connection between the fuel pump I 6a and the microprocessor 22 which is also connected to the PCM 15.

In use, analogue signal voltages from the fuel pressure sensor 3, the Hall Effect current sensing device 7, and external control voltages are converted into digital signals by the ADC 20, while signals from the latter, from the opto-coupler 19, and from external control interface circuits 21 arc received and monitored by the microprocessor 22.

The microprocessor 22 mathematically combines the fuel pressure reading from pressure sensor 13 and the duration of injection pulses as read by the Hall Effect current sensor 17 thus providing a proportional digital output signal from the microprocessor 22 representing the relative quantity of fuel injected into the engine.

The microprocessor 22 is programmed to enable a fuel injection pulse generated by the PCM 15 and transmitted to the injector 11 to be interrupted if necessary at a predetermined point in time by transmitting a signal to the MOSFET switching block 18 thus to turn off the supply pulse at a precise moment, thus prematurely stopping the injection of fuel into the combustion chamber. A resultant signal is then transmitted from the microprocessor 22 via the interface 21 to control a second set of injectors (not shown) arranged to inject a pulse or pulses of predetermined length of a second, lighter fuel such as LPG into the air stream supplied to the combustion chamber. The timing generated by the microprocessor 22 is such that the injection of secondary fuel coincides with the combustion cycle of the engine.

Accordingly, a predetermined and controlled injection of diesel fuel takes place during OflC combustion stroke, while a predetermined quantity of the second fuel is injected into the combustion chamber sequentially, so that the overall fuel supply to the combustion chamber is a sum of the first and second fuels in their predetermined and controlled proportions, the second fuel having a shorter molecular structure ensuring substantially complete combustion of the first fuel thus considerably increasing the efficiency of the engine and reducing carbon emissions from the exhaust as well as smoke and particulate matter.

The microprocessor 22 may also intercept the fuel pump pressure control signals 16b to cause the fuel pressure to be modified. This is not essential in all cases since the pressure can be a constant while the volume of the fuel supply is controlled and modified as appropriate to maximise efficiency.

Since the system, in this example, is readily connected physically to and between the PCM 15 and injector ii of any electronically controlled fuel injected engine, the microprocessor 22 can be programmed to bring about a control of a single or dual fuel supply to the engine to achieve improved efficiency and reduce emissions, irrespective of the design of the engine or the control imposed over it by the PCM 15.

The system can be used for other purposes by imposing a control over the fuel supplied to the injectors 11.

It can be used for electronic fuel injection fault diagnosis by providing an injected fuel quantity reference as a means of checking and confirming correct fuel delivery.

It can be used to enhance engine performance by injecting a secondary fuel in proportions which serve to increase engine power output.

The system is fully bi-directional so that it may be connected in either polarity and it is electrically isolated so that high voltages cannot enter the control circuit. The system may be used with both diesel and gasoline direct injection engines. While in operation current sensing within the circuit is monitored by the Hall Effect sensor 17, and any improper current flow conditions within the circuit can be rectified by switching off the MOSFET switching block 1 8 thus protecting the circuit from damage.

When used for the sequential supply of a secondary fuel any liquid/gaseous fuel may be used, provided that it is fuel of shorter molecular structure than the diesel or gasoline supplied as the primary fuel. Examples of lighter secondary fuels include liquefied petroleum gas (LPG), hydrogen, compressed natural gas, and bioethanol.

The improved thermal efficiency within the internal combustion engine afforded by dual-fuel control as described, serves to create a cooler, leaner burn, which will provide improved output in terms of power, torque and energy, while using less overall fuel and producing considerably less harmful emissions, particularly nitrogen oxides, as well as, in the case of diesel fuel, a considerable reduction in particulate matter and smoke. In the case of a truck engine, for example, this improvement in efficiency is interpreted by the engine's PCM as though it were a reduction in load carried by the vehicle, so the PCM will consequently retard the quantity of diesel fuel supplied and thus improve the economy of the engine in direct proportion to the improvement in engine efficiency.

lypical results on a truck engine are considered to provide a reduction in primary fuel consumption of around 50%, using only 5% to 10% of secondary fuel to achieve this improvement. Emission reductions are typically 40% to 70% reduction in nitrogen oxides, 80% to 90% reduction in smoke and particulate matter, and a reduction of 20% to 35% of carbon dioxide. These improvements are achieved in a completely non-invasive manner so that the engine life and/or periods between servicing will be extended due to the lower combustion temperatures achieved by homogenous combustion, and the reduction in carbon deposits. It is found that the heavier the primary fuel, the greater is the improvement in engine efficiency and reduction in exhaust emissions.

Claims

CLAIMS1. A method of improving the fuel efficiency of an electronically controlled fuel injected internal combustion engine, comprising the steps of controlling the quantity of a first fuel having a first molecular structure injected into a combustion chamber ol the engine during a combustion cycle, and sequentially supplying to the combustion chamber a control led proportional quantity of a second fuel of a shorter molecular structure.
2. A method according to claim 1 wherein the second fuel is supplied to the combustion chamber during the same combustion cycle.
3 A method according to claim 1 wherein the second fuel is supplied to the combustion chamber during a subsequent combustion cycle.
4. A method according to claim 1 wherein the controlled quantity of the first fuel injected into the combustion chamber during a combustion cycle is determined by a microprocessor which produces a signal to determine the proportional quantity of the second fuel and the sequential timing of injection thereof into the combustion chamber.
5. A method according to any preceding claim wherein the controlled quantity of the first fuel is determined by measuring the normal duration of a pulsed supply of the first fuel by an injector as determined by an engine management computer or powertrain control module (PCM) , the proportional quantity of the second fuel being injected into the combustion chamber at a subsequent point in time coincident with a combustion stroke of the engine.
6. A method according to claim 5 wherein the pulsed supply of the first fuel is interrupted at a predetermined point in time.
7 A method according to any preceding claim wherein the controlled quantity of the first fuel is determined by monitoring the duration of the supply of the first fuel by an injector in relation to a signal representative of the instantaneous fuel pressure derived from a fuel pump, and interrupting the supply at a predetermined point in time.
8. A method according to claim 7 wherein a signal is sent to the fuel pump to modify the fuel pressure in addition to, or as an alternative to, modification of the duration of a pulsed fuel supply to the combustion chamber of the engine.
9. A method according to any preceding claim wherein the first fuel is diesel.
10. A method according to any preceding claim wherein the second fuel is liquefied petroleum gas (LPG).

11 A method according to any one of claims I to 10 wherein the second fuel is hydrogen 12. A method according to any one of claims Ito 10 wherein the second fuel comprises two or more different fuels of different molecular structures.13. A method according to any one of claims I to 10 wherein the second fuel is a hydrocarbon fuel.14. A method according to any preceding claim wherein the second fuel is injected into the air stream supplied to the combustion chamber of the engine.15. A system for improving the fuel efficiency of an electronically controlled fuel injected internal combustion engine, comprising means for connection to the fuel supply system of the engine, means for controlling the quantity of a first fuel having a first molecular structure injected into a combustion chamber of the engine during a combustion cycle, and means for sequentially supplying to the combustion chamber a controlled proportional quantity of a second fuel of a shorter molecular structure 16. A system according to claim 15 adapted for connection between an engine management computer or powertrain control module (PCM) and a fuel injector for the engine thus to interrupt the signals issued by the PCM to the injector and to supply modified signals to the injector 17. A system according to claim 15 or claim 16 comprising means for measuring the normal duration of a pulsed supply of a first fuel to the injector, means for modifying the pulsed length of the supply of the first fuel, a microprocessor for receiving signals from the measuring means and for transmitting signals to the pulsed length modifying means, and adapted to produce and transmit a resultant signal to means for sequentially supplying a controlled proportional quantity of the second fuel.18. A system according to any one of claims 15 to 17 including means to monitor the instantaneous pressure of the first fuel deiived by a fuel pump and to modify the pressure as a parameter of the supply of the first fuel to the engine.19. A system according to claims 17 and 18 wherein the pressure monitoring means is the microprocessor and is adapted to receive signals from, and transmit signals to, the fuel pump.20. A system according to claim 19 wherein the microprocessor is connected to the PCM and adapted to transmit signals thereto representative of the overall fuel supply to the engine thus to emulate normal engine operational conditions as monitored by the PCM.21. A system according to claim 17 wherein the means for measuring the normal duration of the pulsed supply of the first fuel to the injector is a Hall Effect current sensing device producing an analogue signal, and connected, via an analogue to digital converter, to the microprocessor.22. A system according to claim 17 wherein the means for modifying the pulsed length of the supply of the first fuel to the injector is an optically coupled MOSFET switching block connected to the microprocessor.23. A system according to claims 21 and 22 wherein the Hall Effect current sensor and optically coupled MOSFET switching block are connected to provide a low-resistance electrically conductive path completing a circuit between the PCM and the injector.24. A system according to claim 23 including an opto-coupler connected in parallel to the optically coupled MOSFET switching block to detect any potential difference during an "off' state of the switching block.25. An electronically controlled fuel injected internal combustion engine comprising at least one combustion chamber, a fuel injector connected to the combustion chamber and to a supply of a first fuel having a first molecular structure, a microprocessor connected to the injector and adapted to control the duration of a pulsed supply of the [irst fuel to the injector, and means for subsequently supplying to the combustion chamber a controlled proportional quantity of a second fuel of a shorter molecular structure during a combustion cycle.