GB2470725A - Controlling fuel source changeover in a bi-fuel vehicle based on air-to-fuel ratio - Google Patents

Controlling fuel source changeover in a bi-fuel vehicle based on air-to-fuel ratio Download PDF

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Publication number
GB2470725A
GB2470725A GB0909365A GB0909365A GB2470725A GB 2470725 A GB2470725 A GB 2470725A GB 0909365 A GB0909365 A GB 0909365A GB 0909365 A GB0909365 A GB 0909365A GB 2470725 A GB2470725 A GB 2470725A
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Prior art keywords
fuel
fuel source
air
vehicle
source
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GB0909365A
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GB0909365D0 (en
GB2470725B (en
Inventor
Andreas Jauss
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GM Global Technology Operations LLC
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GM Global Technology Operations LLC
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Classifications

    • 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
    • F02D19/0602—Control of components of the fuel supply system
    • F02D19/0613—Switch-over from one fuel to another
    • F02D19/0615—Switch-over from one fuel to another being initiated by automatic means, e.g. based on engine or vehicle operating conditions
    • 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
    • F02D19/0626—Measuring or estimating parameters related to the fuel supply system
    • F02D19/0628—Determining the fuel pressure, temperature or flow, the fuel tank fill level or a valve position
    • F02D19/0631—Determining the fuel pressure, temperature or flow, the fuel tank fill level or a valve position by estimation, i.e. without using direct measurements of a corresponding sensor
    • 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
    • F02D19/0639—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 characterised by the type of fuels
    • F02D19/0642—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 characterised by the type of fuels at least one fuel being gaseous, the other fuels being gaseous or liquid at standard conditions
    • F02D19/0647—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 characterised by the type of fuels at least one fuel being gaseous, the other fuels being gaseous or liquid at standard conditions the gaseous fuel being liquefied petroleum gas [LPG], liquefied natural gas [LNG], compressed natural gas [CNG] or dimethyl ether [DME]
    • 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
    • F02D19/08—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 simultaneously using pluralities of 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
    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
    • B60K15/00—Arrangement in connection with fuel supply of combustion engines or other fuel consuming energy converters, e.g. fuel cells; Mounting or construction of fuel tanks
    • B60K15/03—Fuel tanks
    • B60K15/03006—Gas tanks
    • 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
    • F02D19/0626—Measuring or estimating parameters related to the fuel supply system
    • F02D19/0628—Determining the fuel pressure, temperature or flow, the fuel tank fill level or a valve position
    • 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
    • F02D19/0663—Details on the fuel supply system, e.g. tanks, valves, pipes, pumps, rails, injectors or mixers
    • F02D19/0686—Injectors
    • F02D19/0692—Arrangement of multiple injectors per combustion chamber
    • 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
    • F02D19/0663—Details on the fuel supply system, e.g. tanks, valves, pipes, pumps, rails, injectors or mixers
    • F02D19/0697—Arrangement of fuel supply systems on engines or vehicle bodies; Components of the fuel supply system being combined with another device
    • 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
    • F02D41/22—Safety or indicating devices for abnormal conditions
    • F02D2041/228—Warning displays
    • 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
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/14—Introducing closed-loop corrections
    • F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
    • F02D41/1444—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases
    • F02D41/1454—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being an oxygen content or concentration or the air-fuel ratio
    • 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

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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)
  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
  • Output Control And Ontrol Of Special Type Engine (AREA)

Abstract

A bi-fuelled vehicle has a source (104, fig.1) of gaseous fuel, eg CNG, eg methane, and a second fuel source (106), eg a conventional petrol tank. Fuel source changeover is controlled by an ECU (108) that receives inputs from a gaseous fuel tank pressure sensor (126) and an exhaust gas oxygen sensor, eg lambda probe (128), to provide a parameter value indicative of the air-to-fuel ratio (AFR) in the combustion chamber(s). If when the engine is being supplied with gaseous fuel the air-to-fuel ratio falls outside an allowable range, eg if λ<1.2, the ECU switches to the second fuel source. This step may occur only if the gaseous fuel tank pressure is below a predetermined minimum pressure. The method allows more of the gaseous fuel in the gas tank to be utilized to power the vehicle, thereby extending the distance during which the vehicle can be gas-powered, and protects the catalytic converter from the effects of an over-lean air-fuel mixture. An indication may be given to the driver that the gas tank pressure is too low.

Description

I
METHOD FOR SELECTING FUEL SOURCE FOR VEHICLE HAVING A FIRST
FUEL SOURCE AND A SECOND FUEL SOURCE
Technical field
The present invention relates to a method for selecting fuel source for a vehicle having a first fuel source and a second fuel source, wherein said first fuel source contains gaseous fuel.
Background of the invention
The number of vehicles that use gaseous fuel is growing.
An example would be CNG (Compressed Natural Gas) -vehicles which use Compressed Natural Gas as fuel. The gas is typically stored in a gas tank in the vehicle, wherein the gas tank can be refuelled at a filling station. As gas is consumed, the pressure in the gas tank is reduced, and at some point the remaining pressure in the gas tank is not sufficient to reliably supply fuel to the combustion engine in all driving conditions.
To extend the driving distance, many gas-powered vehicles have a supplementary fuel source containing e.g. petrol. Thus, as the pressure in the gas tank falls below a predetermined pressure level, the fuel is changed from gas to petrol. This predetermined pressure level is typically set based on driving conditions involving maximum fuel consumption plus a safety margin. As a result a not insignificant amount of gas remains *in the gas tank upon switching over to the complementary fuel source.
In an effort to increase the driving distance during which the vehicle is gas-powered, JP2004239114 discloses a bi-fuel engine comprising a residual pressure detection sensor detecting residual pressure in a gaseous fuel container, and a remaining amount detection sensor detecting a remaining amount in a liquid fuel container. When the residual pressure is the predetermined pressure or less and the remaining amount is the predetermined amount or less, a control for changing ignition timing is performed so that gaseous fuel can be injected into a cylinder, and the residual gaseous fuel in the container can Je utilized for elongate the cruising distance.
However, this typically requires that the vehicle is equipped with a sophisticated ignition control system having a detrimental effect on cost.
Summary of the invention
In view of the above, an object of the invention is to solve or at least reduce at least one of the problems discussed above. In particular, an object is to provide a cost-efficient way to increase the driving distance during which the vehicle is gas-powered.
According to a first aspect of the invention, there is provided a method for selecting fuel source for a vehicle having a first fuel source and a second fuel source, wherein the first fuel source contains gaseous fuel; the method *comprising the steps of: supplying gaseous fuel from the first fuel source to a combustion chamber of a combustion engine of the vehicle; acquiring a parameter value indicative of an air-to-fuel ratio of an air-fuel mixture provided to the combustion chamber; evaluating the parameter value; and if the acquired parameter value is outside an allowable range, switching to the second fuel source.
The present invention is based on the understanding that the driving distance during which the vehicle is gas-powered can be extended by providing a switch-over timing based on engine operating conditions. The inventor has further realized that the engine operating conditions can be monitored by acquiring a parameter value indicative of the air-to-fuel ratio of the air-fuel mixture provided to the combustion chamber, wherein the switch-over timing can be based on the detected air-to-fuel ratio.
The method enables more of the gas in the gas tank to be utilized before switching over to a supplementary fuel source, without detrimentally influencing the performance of the vehicle. For example, damage to the catalytic converter may be avoided while efficiently utilizing more of the gas. In particular, gaseous fuel may be supplied as long as the air-fuel mixture is not too lean, i.e. the mixture is not so lean that the air-fuel mixture provided to the combustion chamber results in a detrimentally high temperature in the catalytic converter.
As the switch over timing is based on engine operating conditions, rather than just a predetermined pressure level in the gas tank, a driver of the vehicle can be allowed to adapt his driving in such a way that the operating conditions in the engine are less likely to trigger a switch-over to the supplementary fuel source. This can be done by driving such that the engine is under low-load conditions, for example, by maintaining a constant speed or accelerating gently. Thus, some of the gaseous fuel (that otherwise would have remained in the gas tank) can be utilized to power the vehicle, thereby further extending the distance for which the vehicle can be gas-powered.
As information indicative of the air-to-fuel ratio in the air-fuel mixture in the combustion chamber is typically already available in today's vehicle (e.g. to control fuel injection to ensure complete combustion) no additional sensors may be required, and all the required functionality can advantageously be implemented in the form of software in an existing control device in the vehicle, such as, for example, the Engine Control Unit (ECU), thereby enabling a cost-efficient solution.
The method may further comprise the steps of: acquiring a pressure of the gaseous fuel in the first fuel source; evaluating the acquired pressure; and only if the acquired pressure is below a predetermined minimum pressure, selecting fuel source according to the above described method.
The predetermined minimum pressure may advantageously be set such that the remaining pressure in the first fuel source is sufficient to reliably supply fuel to the combustion engine in all driving conditions. For example, the predetermined minimum pressure may be set based on maximum fuel consumption (e.g. wide open throttle, maximum load, and/or the engine operating at high r.p.m.) plus a safety margin. An advantage is that the method for selecting fuel source is activated when needed, i.e. when there is a risk that there is not sufficient gaseous fuel to reliably supply fuel to the engine.
The parameter value indicative of an air-to-fuel ratio of an air-fuel mixture provided to the combustion chamber may be a measure of the proportion of oxygen in the exhaust gas that results from combustion of gaseous fuel in the combustion engine. An advantage is that the proportion of oxygen in the exhaust gas is a reliable and easily detectable indication of the air-to-fuel ratio of the air-fuel mixture provided to the combustion chamber.
According to an embodiment, the proportion of oxygen remaining in the exhaust gas may be determined from a so-called lambda-value provided by a so-called lambda-probe arranged in an exhaust system of the vehicle. An advantage is that the lambda-probe is a standard component already available in today's vehicles, and thus no additional sensor is typically required, enabling a cost-efficient solution.
The lambda-value provides a way of measuring the air-to-fuel ratio of the air-fuel mixture in the combustion chamber, where =l indicates an optimum mix of air-fuel in the combustion chamber, X<l indicates a lack of air (rich mixture), and ?>l indicates a surplus of air (lean mixture) The allowable range may be selected so as to protect the catalytic converter from detrimental effects (e.g. detrimentally high temperatures) due to a too lean air-fuel mixture. For example, the allowable range may be that the lambda-value is less than 1.2. However, it is recognized by a person skilled in the art that this value may vary depending on the application.
The method may further comprise the step of indicating to a driver of the vehicle that the pressure in the gas tank is below the minimum pressure or in some other way indicating to the driver that the fuel source is now selected based on the air-to-fuel ratio of the air-fuel mixture provided to the combustion chamber. An advantage is that a driver of the vehicle becomes aware that he should avoid high load conditions of the engine to reduce the probability that a switch-over to the supplementary fuel source is triggered.
The second fuel source may contain petrol. However, other types of fuel are possible, such as, e.g. Compressed Natural Gas (CNG) According to a second aspect of the invention, there is provided a control device for controlling operation of a combustion engine in a vehicle having a first fuel source and a second fuel source, wherein the first fuel source contains gaseous fuel, the control device comprising an input for receiving signals; an output for outputting signals; and processing circuitry configured to acquiring via the input a parameter value indicative of an air-to-fuel ratio of an air-fuel mixture provided to a combustion chamber of the combustion engine; evaluating the parameter value; if the acquired parameter is outside an allowable range, controlling the combustion engine to switch to the second fuel source.
According to a third aspect of the invention, there is provided a computer program enabling the processing circuitry comprised in the control device to perform the steps of the method according to the invention.
According to a fourth aspect of the invention, there is provided a control system for a vehicle having a first fuel source and a second fuel source, wherein the first fuel source contains gaseous fuel, the control system comprising an oxygen sensor for detecting a parameter indicative of an air-to fuel ratio of an air-fuel mixture provided to a combustion chamber; and a control device according to the invention.
Other objectives, features and advantages will appear from the following detailed disclosure, from the attached dependent claims as well as from the drawings.
Brief description of the drawings
The above, as well as additional objects, features and advantages of the present invention, will be better understood through the following illustrative and non-limiting detailed description of preferred embodiments of the present invention, with reference to the appended drawings, where the same reference numerals will be used for similar elements, wherein: Fig. 1 schematically illustrates a bi-fuel system according to an embodiment of the invention; and Fig. 2 is a schematic block diagram illustrating a method for selecting fuel source for the bi-fuel system depicted in figure 1.
Detailed description of preferred embodiments
Figure 1 schematically illustrates a bi--fuel system 100 according to a preferred embodiment of the invention. The bi-fuel system 100 comprises a combustion engine 102 having a first 104 and a second 106 fuel source, and a control device 108 controlling the fuel supply to the engine.
The first fuel source 104 is a gas tank 104 containing *gaseous fuel, such as, Compressed Natural Gas (CNG), e.g. methane. A first fuel pipe 110 connects the gas tank 104 to a gas injection valve 112 arranged to inject gas to a combustion chamber 113 of the combustion engine 102. Furthermore, a regulator 114 may be arranged between the gas tank 104 and the gas injection valve 112, to provide a gas pressure appropriate for injection to the combustion chamber.
The second fuel source 106 is here a conventional petrol tank 106 containing petrol. A second fuel pipe 116 connects the petrol tank 106 to a petrol injection valve 118 arranged to inject petrol to the combustion chamber 113. A fuel pump is arranged to pump petrol from the petrol tank 106 to the petrol injection valve 118.
The combustion engine 102 further comprises, an air intake duct (not shown) arranged to supply air to the combustion chamber, and an ignition plug 121. There is also an exhaust port (not shown) connecting the combustion chamber to an exhaust system 124 of the vehicle. The exhaust system typically comprises an exhaust manifold, a catalytic converter and an exhaust pipe.
Although only one combustion chamber 113 is illustrated in figure 1, there is typically one combustion chamber per cylinder in the engine.
The control device 108 is here an Engine Control Unit (ECU) 108. The ECU 108 may typically comprise functionality to control, for example, the fuel injection and ignition timing pf the engine. Here, the ECU also has functionality to control whether the supplied fuel is gas or petrol.
A pressure sensor 126, connected to the ECU 108, is arranged at the outlet of the gas tank, to measure the pressure in the gas tank 104. Typically the pressure sensor 126 generates an output voltage proportional to the pressure in the gas tank 104. This output voltage can then converted by an A/D-converter and supplied to the ECU 108.
Furthermore, an oxygen sensor 128, connected to the ECU 108, is arranged to measure the proportion of oxygen in the exhaust gas. The oxygen sensor may, for example, be a conventional lambda-probe which measures a difference in oxygen between the exhaust gas and the external air, and generates an output voltage depending on this difference. This output voltage can then converted by an A/D-converter and 25.supplied to the ECU 108. It is recognized by a person skilled in the art that the location of the oxygen sensor may vary, and there may be more than one oxygen sensor. For example, the oxygen sensor may be positioned after the branch manifold of the exhaust system, and before the catalytic converter. An alternative would be to have oxygen sensors arranged both before and after the catalytic converter.
There may also be an indicator 130 arranged, for example, on the dashboard 132 of the vehicle. The indicator lamp 130 is connected to the ECU 108 and can be turned on and off to display a message to driver.
A method for selecting fuel source will now be described with reference to figure 1 and 2.
In the illustrated example it is assumed that the gas in the gas tank 104 is utilized as a primary fuel source, and that the petrol in the petrol tank 106 is only used as the vehicle runs out of gas in the gas tank.
In a situation where the gas tank 104 is filled with gas, the pressure in the gas tank is typically about 200 bar, and gas in the gas tank 104 will be used to power the vehicle.
Thus, in step 201, gas is supplied from the gas tank 104 to the combustion engine 102 of the vehicle. The gas is injected to the combustion chambers 113 via the gas injection valves 112. The injection timing and the air-to-fuel ratio of the air-fuel mixture injected in the combustion chamber is controlled by the ECU 108 by controlling the gas injection valve.
As the engine is used to power the vehicle, gas in the gas tank will be consumed and the pressure therein will be reduced.
In step 202, the ECU 108 acquires a signal indicative of the gas pressure in the gas tank 104 from the pressure sensor 126.
In step 203, the acquired gas pressure in the gas tank 104 is evaluated by comparing it to a predetermined minimum pressure. The predetermined minimum pressure is typically set such that the remaining pressure in the gas tank is sufficient to reliably supply fuel to the combustion engine in all driving conditions. Thus, the minimum gas pressure is based on driving conditions involving maximum fuel consumption (for example maximum load and revolutions per minute (r.p.m.)) plus a safety margin.
If the detected gas pressure in the gas tank 104 is equal to or above the predetermined minimum pressure the method will return to step 201, and the vehicle will remain gas-powered whereas the ECU 108 continues to monitor the pressure in the gas tank 104.
However, if the detected gas pressure in the gas tank 104 is below the predetermined minimum pressure, the control logic according to the invention can be activated and monitor the signal of the lambda-probe 128, as will be described below with reference to step 204 to 207.
In step 204, the ECU 108 acquires a parameter value indicative of an air-to-fuel ratio of an air-fuel mixture provided to the combustion chamber of the combustion engine.
In this embodiment the ECU acquires a lambda-value from the lambda-probe 128.
In step 205, the acquired lambda value is evaluated.
The lambda-value is indicative of the air-fuel ratio of the air-fuel mixture in the combustion chamber. X=1 indicates a optimum mix of air-fuel in the combustion chamber. For A.<1 there is a lack of air (rich mixture), and for 2.>1 there is a surplus of air (lean mixture) . An allowable lambda-value for ensuring proper operation of the engine in a typical application may be in the range 0.8<?.<1.2 (although it is recognized that these values may vary depending on the application) . Thus, if the acquired parameter is below 1.2 the remaining pressure in the gas tank is considered to be sufficient to reliably supply fuel to the combustion engine for the current driving conditions, and the ECU will continue to use the gas tank 104 as a fuel source.
However, if the acquired parameter is equal to or above 1.2 this indicates that the remaining pressure in the gas tank is not sufficient to reliable supply fuel to the combustion engine for the current driving conditions and the ECU will switch fuel source to the petrol tank in step 206.
Through the arrangement more of the gas in the gas tank can be utilized before switching over to an alternative fuel source, whereas the arrangement protects the catalytic converter of the exhaust system which can react detrimentally on rapid changes in the lambda-value (e.g. short high exothermic with damage to the catalytic converter through rapid reduction of gas in the mixture (i.e. too lean mixture)) The method may further comprise a step 207 of turning on an indicator lamp 130 on the dashboard of the vehicle (e.g. when the pressure in the gas tank falls below the predetermined minimum pressure) to encourage a driver of the vehicle to adapt his driving in a way that the operating conditions in the engine are less likely to trigger a switch-over to the complementary fuel source. It would also be possible to indicate to the driver when a switch-over to the complementary fuel source has occurred.
It is recognized by a person skilled in the art that the functionality described above with reference to step 201-207 can be implemented, for example, in a software in the ECU.
The invention has mainly been described above with reference to a few embodiments. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the invention, as defined by the appended claims. For example, an indication to the driver can be conveyed to the driver via other means than an indicator lamp, such as, for example by a text on a display.
Furthermore, although it may be preferable to utilize the processors of the ECU that are used for engine control (e.g. fuel injection, and injection timing) to implement the functionality of the invention, other parts of the ECU may also be used, as well as any additional processor.
Furthermore, the functionality can be distributed among processors.

Claims (10)

  1. CLAIMS1. A method for selecting fuel source for a vehicle having a first fuel source (104) and a second fuel source (106), wherein said first fuel source (104) contains gaseous fuel; said method comprising the steps of: -supplying (201) gaseous fuel from said first fuel source (104) to a combustion chamber (113) of a combustion engine (102) of the vehicle; -acquiring (204) a parameter value indicative of an air-to-fuel ratio of an air-fuel mixture provided to the combustion chamber (113); -evaluating (205) the parameter value; and -if the acquired parameter value is outside an allowable range, switching (206) to said second fuel source.
  2. 2. A method according to claim 1, further comprising the steps of: -acquiring (202) a pressure of the gaseous fuel in said first fuel source; -evaluating (203) the acquired pressure; and -only if the acquired pressure is below a predetermined minimum pressure, selecting fuel source according to claim 1.
  3. 3. A method according to claim 1 or 2, wherein said parameter value is a measure of the proportion of oxygen in the exhaust gas resulting from combustion of gaseous fuel in said combustion engine.
  4. 4. A method according to claim 3, wherein said proportion of oxygen in the exhaust gas is determined from a so-called lambda-value provided by a so-called lambda-probe (128) arranged in an exhaust system of the vehicle.
  5. 5. A method according to any one of the preceding claims, wherein said allowable range is selected so as to protect the catalytic converter from detrimental effects due to a too lean air-fuel mixture.
  6. 6. A method according to any one of the preceding claims, further comprising the step of indicating (207) to a driver of the vehicle that the pressure in the gas tank is below the minimum pressure.
  7. 7. A method according to any one of the preceding claims, wherein said second fuel source (106) contains petrol.
  8. 8. A control device (108) for controlling operation of a combustion engine in a vehicle having a first fuel source (104) and a second fuel source (106), wherein said first fuel source (104) contains gaseous fuel, said control device (108) comprising: -an input for receiving signals; an output for outputting signals; and -processing circuitry configured to: i. acquire via said input a parameter value indicative of an air-to-fuel ratio of an air-fuel mixture provided to a combustion chamber (113) of the combustion engine (102); ii. evaluating the parameter value; iii. if the acquired parameter is outside an allowable range, controlling said combustion engine to switch to said second fuel source (106)
  9. 9. A computer program enabling said processing circuitry comprised in the control device (108) according to claim 8, to 30.perform the steps according to any one of claims 1 to 7.
  10. 10. A control system for a vehicle having a first fuel source (104) and a second fuel source (106), wherein the first fuel source contains gaseous fuel, the control system comprising: -an oxygen sensor (128) for detecting a parameter indicative of an air-to fuel ratio of an air-fuel mixture provided to a combustion chamber (113); and -a control device (108) according to claim 8.
GB0909365.9A 2009-06-01 2009-06-01 Method for selecting fuel source for vehicle having a first fuel source and a second fuel source Expired - Fee Related GB2470725B (en)

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WO2013100844A1 (en) * 2011-12-28 2013-07-04 Scania Cv Ab Arrangement and method for estimating a fuel mixture's content of a supplementary fuel
CN110730862A (en) * 2017-02-15 2020-01-24 高斯科尔发电机组股份有限公司 Fuel mixing system and method

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CH709242A1 (en) * 2014-02-11 2015-08-14 Bang & Clean Gmbh Method and apparatus for cleaning the interiors of containers and equipment by means of explosion technology.

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JPS59544A (en) * 1982-06-23 1984-01-05 Takeshi Ikeda Engine using liquid fuel and gas fuel simultaneously
GB2402754A (en) * 2003-06-11 2004-12-15 Clean Air Partners Inc A method of operating a dual fuel internal combustion engine
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JPS59544A (en) * 1982-06-23 1984-01-05 Takeshi Ikeda Engine using liquid fuel and gas fuel simultaneously
GB2402754A (en) * 2003-06-11 2004-12-15 Clean Air Partners Inc A method of operating a dual fuel internal combustion engine
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JP2006132405A (en) * 2004-11-04 2006-05-25 Mazda Motor Corp Engine control device

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WO2013100844A1 (en) * 2011-12-28 2013-07-04 Scania Cv Ab Arrangement and method for estimating a fuel mixture's content of a supplementary fuel
CN110730862A (en) * 2017-02-15 2020-01-24 高斯科尔发电机组股份有限公司 Fuel mixing system and method
CN110730862B (en) * 2017-02-15 2022-07-01 西门子能源发动机独资有限公司 Fuel mixing system and method

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GB2470725B (en) 2013-09-11

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