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    • 专利摘要:
    The present invention relates to a method for adapting engine control of a gas engine in a vehicle. The method comprises determining, during operation of the gas engine, the specific gas constant of a fuel gas for the gas engine. The method further comprises determining the stoichiometric air fuel ratio of the fuel gas for the gas engine. The control of the gas engine is adapted based on the determined specific gas constant and the determined stoichiometric air fuel ratio. The present invention also relates to a system for adapting engine control of a gas engine in a vehicle, to a vehicle, to a computer program and to a computer program product.(Fig. 2)
    公开号:SE1650386A1
    申请号:SE1650386
    申请日:2016-03-23
    公开日:2017-09-24
    发明作者:Wallengren Mårten
    申请人:Scania Cv Ab；
    IPC主号:
    专利说明:

    1 A method and a system for adapting engine control of a gas engine in a vehicle TECHNICAL FIELD The present invention relates to a method and a system for adapting engine control of a gasengine in a vehicle. The present relation also relates to vehicle, to a computer program for adapting engine control of a gas engine in a vehicle and to a computer program product.
    BACKGROUND ART The exhaust aftertreatment of a spark ignited engine running stoichiometric consists often of athree-way catalytic converter in the exhaust system. A three-way catalytic converter must bein chemical balance to be able to reduce nitrogen-oxides emissions and oxidize carbon-monoxide and hydrocarbon emissions. A modern engine management system, EMS, adapts todifferent fuel qualities by adjusting the air-fuel ratio, AFR, until a so-called stoichiometric ratiocould be measured. This is usually done by means of a so-called lambda sensor situated in theexhaust pipe relatively close to the engine. The lambda sensor measures the ratio of actualAFR to stoichiometric AFR. This ration is usually denoted Å. The EMS then controls the fuelinjection by adding or reducing the fuel in relation to the air going in to the engine. This is done by a control algorithm called lambda controller.
    For petrol as the fuel this works very well and can compensate for different energy contents inthe fuel. lt also compensates for if some components like fuel injectors, air mass meters orother components involved in calculating air or fuel, are not nominal to their specification. Thevalue ofthe lambda controller is then saved as an adaptation in the flash memory of anelectronic control unit, ECU. This means that the value ofthe lambda controller can be usednext time engine is started. When fuel is stable and all components are functioning properly the adjustments made by the lambda controller are relatively small.
    For gaseous fuels a similar control is used. 2Problems relating to different fuel qualities of petrol are basically related to differentevaporation properties of the petrol. Functions of the EMS relating to different evaporation properties are of no need for gaseous fuels since gaseous fuels do not need to be evaporated.
    SUMMARY OF THE INVENTION Whereas the energy content of petrol usually only differs by i 1-2 MJ/kg, the energy contentof gaseous fuel can differ by around i 5 MJ/kg. Whereas the density of petrol usually onlydiffers with a few percent, the density of gaseous fuels can differ by up to 20%. As a result, thestoichiometric AFR of gaseous fuels can differ considerably. As an example, methane has astoichiometric AFR of 17.2, while some natural gas on the market has a stoichiometric AFR of13.1. As a further result, the specific gas constant can be different. While methane has aspecific gas constant of around 520 in the international system of units, Sl-units, said natural gas on the market has a specific gas constant of around 450 in Sl-units.
    The solution of using a similar EMS for gaseous fuels as for petrol, i.e. using basically thelambda controller for adjusting differences between different gases, has some drawbacks. Thedifference between different gases can be so large that it can be difficult to manage the adjustments between the limits of the lambda controller.
    The idea of having the standard fuel adaptation in the system is to correct for differences inthe hardware ofthe components involved in the fuel injection and lambda control, such asinjectors and lambda sensors. lf the fuel adaptation shall handle both quality differencesbetween gaseous fuels and hardware the risk of going outside the limits and getting an engine malfunction will be much higher.
    A further drawback of the solution is that the effect of the gas quality on the air masscalculation will be completely ignored. Even though Å will be correct the amount of aircalculated could be wrong. This affects the calculated torque and also the ignition angle used,which risks running the engine on an ignition angle which is not optimal and calculating an incorrect torque which could affect the drivability in a negative way.
    There is thus a need for improving the adaption of an engine control for gaseous fuels. 3lt is thus an object ofthe present invention to provide a method, a system, a vehicle, acomputer program and a computer program product for improved adaption of an engine control for gaseous fuels. lt is further an object of the present invention to provide an alternative method, a system avehicle, a computer program and a computer program product for adaption of an engine control for gaseous fuels.
    At least parts of the objects are achieved by a method for adapting engine control of a gasengine in a vehicle. The method comprises determining, during operation of the gas engine,the specific gas constant of a fuel gas for the gas engine. The method further comprisesdetermining the stoichiometric air fuel ratio of the fuel gas for the gas engine. The control of the gas engine is adapted based on the determined specific gas constant and the determined stoichiometric air fuel ratio. This has the advantage that better fuel efficiency can be achieved.
    Also the composition of the exhaust mix from the gas engine can be optimised. By this somecompositions in the exhaust can be minimised, which reduces negative effects on theenvironment. The method can also result in less wear of components in the gas engine and thus to a longer lifetime ofthese components. ln one example ofthe method the determining of the specific gas constant and/or thestoichiometric air fuel ratio is based on a determined time period of gas injection. The timeperiod of the gas injection is easy to determine. This results in an easy implementation of the method. ln one example the method further comprises performing measurements in the vehicle. Thedetermining of the specific gas constant and/or the determining of the stoichiometric air fuelratio is based on a result ofthe performed measurements. Using measurements for themethod improves the flexibility of the method for a large variety of fuel gases. Further, better results can be achieved compared to basing parameters on assumptions. ln one example the performed measurements comprise measuring a pressure value and atemperature value in the inlet manifold. Sensors for providing these value exist in many nowadays vehicles. Thus, an implementation of the method in present vehicles without the 4need of new or additional hardware is facilitated. Not needing new hardware is an especially cost effective implementation of the method. ln one example the performed measurements comprise measuring a temperature valueand/or a pressure value of the fuel gas upstream of a gas injector. Sensors for providing thesevalue exist in many nowadays vehicles. Thus, an implementation of the method in presentvehicles without the need of new or additional hardware is facilitated. Not needing new hardware is an especially cost effective implementation of the method. ln one example the performed measurements comprise measuring a Å value by means of alambda sensor. The lambda sensor is provided downstream the gas engine. A lambda sensor isstandard in many nowadays vehicles. Thus, an implementation of the method in presentvehicles without the need of new or additional hardware is facilitated. Not needing new hardware is an especially cost effective implementation of the method. ln one example the method further comprises determining a flow of air into the gas engineand/or determining a mass of air in a cylinder ofthe gas engine. The determining ofthespecific gas constant and/or the stoichiometric air fuel ratio is based on the determined flowof air into the gas engine and/or the determined mass of air in the cylinder of the gas engine.
    This determination can be implemented in many different ways. An implementation ofthis determination is often possible in nowadays vehicles without the need of additional hardware.
    Not needing new hardware is an especially cost effective implementation of the method.
    At least parts of the objects are achieved by a system for adapting engine control of a gasengine in a vehicle. The system comprises means for determining, during operation of the gasengine, the specific gas constant of a fuel gas for the gas engine. The system further comprisesmeans for determining the stoichiometric air fuel ratio of the fuel gas for the gas engine. Thesystem even further comprises means for adapting the control of the gas engine based on the determined specific gas constant and the determined stoichiometric air fuel ratio. ln one embodiment the system further comprises means for determining a time period of gasinjection per working cycle of the engine. The means for determining the stoichiometric airfuel ratio of the fuel gas for the gas engine and/or the means for determining, during operation of the gas engine, the specific gas constant of a fuel gas for the gas engine are then 5arranged for basing the determining of the stoichiometric air fuel ratio and/or the specific gas constant on the determined time period of gas injection. ln one embodiment the system further comprises means for performing measurements in thevehicle. The means for determining the specific gas constant and/or the means fordetermining the stoichiometric air fuel ratio are then arranged to base the determining on a result of the performed measurements. ln one embodiment the means for performing measurements comprise means for measuring a pressure value and a temperature value in the inlet. ln one embodiment the means for performing measurements comprise means for measuring a temperature value and/or a pressure value ofthe fuel gas upstream of a gas injector. ln one embodiment the means for performing measurements comprise a lambda sensorwhich is arranged downstream the gas engine. The lambda sensor is arranged for measuring a Åvalue. ln one embodiment the system further comprises means for determining a flow of air into thegas engine and/or means for determining a mass of air in a cylinder ofthe gas engine. Themeans for determining the specific gas constant and/or the means for determining thestoichiometric air fuel ratio are arranged for basing said determining ofthe specific gasconstant and/or the stoichiometric air fuel ratio on the determined flow of air into the gas engine and/or the determined mass of air in the cylinder of the gas engine.
    At least some of the objects ofthe present invention are achieved by a vehicle whichcomprises a system for adapting engine control of a gas engine in a vehicle according to the present disclosure.
    At least some of the objects ofthe present invention are achieved by a computer program foradapting engine control of a gas engine in a vehicle. The computer program comprises program code for causing an electronic control unit or a computer connected to the electroniccontrol unit to perform the steps of the method for adapting engine control of a gas engine in a vehicle according to the present disclosure. 6At least some of the objects ofthe present invention are achieved by a computer programproduct containing a program code stored on a computer-readable medium for performingmethod steps according to a method for adapting engine control of a gas engine in a vehicleaccording to the present disclosure. This is done when the computer program is run on an electronic control unit or a computer connected to the electronic control unit.
    The system, the vehicle, the computer program and the computer program product havecorresponding advantages as have been described in connection with the corresponding examples of the method according to this disclosure.
    Further advantages of the present invention are described in the following detailed description and/or will arise to a person skilled in the art when performing the invention.
    BRIEF DESCRIPTION OF THE DRAWINGS For a more detailed understanding of the present invention and its objects and advantages,reference is made to the following detailed description which should be read together withthe accompanying drawings. Same reference numbers refer to same components in the different figures. ln the following, Fig. 1 shows, in a schematic way, a vehicle according to one embodiment of the present invention; Fig. 2 shows, in a schematic way, a system according to one embodiment ofthe present invention; Fig. 3 shows, in a schematic way, a flow chart over an example of a method according to the present invention; Fig. 4 shows, in a schematic way, a device which can be used in connection with the present invention.
    DETAILED DESCRIPTION 7Fig. 1 shows a side view of a vehicle 100. ln the shown example, the vehicle comprises atractor unit 110 and a trailer unit 112. The vehicle 100 can be a heavy vehicle such as a truck.ln one example, no trailer unit is connected to the vehicle 100. The vehicle 100 comprises agas engine. The vehicle 100 comprises a system 299, se Fig. 2a. The system 299 can be arranged in the tractor unit 110. ln one example, the vehicle 100 is a bus. The vehicle 100 can be any kind of vehicle comprisinga gas engine. Other examples of vehicles comprising a gas engine are boats, passenger cars,construction vehicles, and locomotives. The present invention can also be used in connection with any other platform than vehicles, as long as such a platform comprises a gas engine.
    The innovative method and the innovative system according to one aspect of the inventionare also well suited to, for example, systems which comprise industrial engines and/or engine- powered industrial robots.
    The term ”link” refers herein to a communication link which may be a physical connectionsuch as an optical, electrical, or opto-electronic communication line, or a non-physical connection such as a wireless connection, e.g. a radio link or microwave link.
    Fig. 2 shows schematically an embodiment of a system 299 for adapting engine control of agas engine in a vehicle according to the present invention. The system 299 comprises a gasengine 210. The gas engine 210 can be arranged to propel a vehicle. The gas engine 210comprises at least one cylinder. Each cylinder has a corresponding volume of the cylinder, VCW.ln the following it is assumed that the volumes of the cylinders are equal. However, it shouldbe understood that the present invention easily could be adapted to cylinders of differentvolumes by defining different volumes Vcy|_,, for a specific cylinder n. The value Vcy| relates to avolume in the cylinder in which air and/or fuel can be injected at a pre-determined position ofa piston in the cylinder. ln one example, the value Vcy| relates to the maximum possiblevolume of the cylinder, for example when the position of the piston is in its least extendedposition. The value Vcy| is pre-determined for a given gas engine and can be stored in first control unit 200. 8Said first control unit 200 is arranged to control operation of said gas engine 210. Said firstcontrol unit 200 is arranged for communication with said gas engine 210 via a link L210. Said first control unit 200 is arranged to receive information from said gas engine 210.
    Said system 299 comprises an air inlet 241. The possible flowing direction of air into the airinlet is indicated by the white arrow. The air then passes a throttle 260 before entering aninlet manifold 230. Said throttle 260 is arranged for controlling the flow of air into said inletmanifold 230. Said throttle 260 is, for example, controlled by said first control unit 200 and/or by a pedal (not shown) of the vehicle.
    Said system 299 further comprises a tank 220. Said tank 220 is arranged for storing the fuelgas of the vehicle. The fuel gas can, for example, be compressed natural gas, CNG. lt should,however, be noted that the invention is not limited to CNG but could use any suitable gaswhich can act as a fuel gas for the gas engine 210. The tank 220 is connected via connectingmeans 243 to a fuel rail 242. Said connecting means 243 can comprise pipes, tubes, or the like.Said connecting means 243 are arranged for transporting the fuel gas from the tank 220 to the fuel rail 242.
    The system 299 further comprises a gas injector 270. Said gas injector 270 is arranged forinjecting gas from the fuel rail 242 into the inlet manifold 230. The gas is injected during a timeperiod tim- for each working cycle. Said gas injector 270 has an effective cross-sectional area, ACD, of its injector nozzle.
    Said first control unit 200 is arranged to control operation of said gas injector 270. Said firstcontrol unit 200 is arranged for communication with said gas injector 270 via a link L270. Said first control unit 200 can be arranged to receive information from said gas injector 270.
    Said first control unit 200 can, for example, be arranged to control tim-_ ln one example, tim- iscalculated by said first control unit 200. ln one example, tim- is measured at the gas injector 270. ACD can be stored in said first control unit 200.
    Said system 299 further comprises an exhaust pipe 240. Said exhaust pipe 240 is connected tothe gas engine 210 and arranged to transport exhausts from the gas engine 210 into the environment as indicated by the white arrow. lt should be understood that means for treating 9the exhaust (not shown) can be arranged along the exhaust pipe. Such means are for example catalytic means for exhaust treatment.
    Said system 299 further comprises a lambda sensor 250. Said lambda sensor 250 is provideddownstream said gas engine. Said lambda sensor 250 is provided at said exhaust pipe 240.Said lambda sensor 250 is arranged to per perform a measurement of Å, i.e. the ratio between actual air-fuel ratio, AFR, and stoichiometric air-fuel ratio, AFRS.
    Said first control unit 200 is arranged to control operation of said lambda sensor 250. Said firstcontrol unit 200 is arranged for communication with said lambda sensor 250 via a link L250.Said first control unit 200 can be arranged to receive information from said lambda sensor 250.
    Said system 299 further comprises first means for measuring a temperature value. Said firstmeans for measuring a temperature value can be a first temperature sensor 254. Said first l temperature sensor is arranged upstream said gas injector 270. Here, the term ”upstream”should be understood in the sense that said first temperature sensor 254 is arranged formeasuring the temperature Tran of the fuel gas before it passes the gas injector 270. ln the shown example, said first temperature sensor 254 is arranged at the fuel rail 242.
    Said first control unit 200 is arranged to control operation of said first temperature sensor254. Said first control unit 200 is arranged for communication with said first temperaturesensor 254 via a link L254. Said first control unit 200 can be arranged to receive information from said first temperature sensor 254.
    Said system 299 further comprises first means for measuring a pressure value. Said first meansfor measuring a pressure value can be a first pressure sensor 255. Said first pressure sensor isarranged upstream said gas injector 270. Here, the term ”upstream” should be understood inthe sense that said first pressure sensor 255 is arranged for measuring the pressure pm" of thefuel gas before it passes the gas injector 270. ln the shown example, said first pressure sensor 255 is arranged at the fuel rail 242.
    Said first control unit 200 is arranged to control operation of said first pressure sensor 255.
    Said first control unit 200 is arranged for communication with said first pressure sensor 255 via a link L255. Said first control unit 200 can be arranged to receive information from said first pressure sensor 255.
    Said system 299 further comprises second means for measuring a temperature value. Saidsecond means for measuring a temperature value can be a second temperature sensor 252.Said second temperature sensor 252 is arranged at the in|et manifold 230. Said second temperature sensor 252 is arranged to measure the temperature Tin in the in|et manifold 230..
    Said first control unit 200 is arranged to control operation of said second temperature sensor252. Said first control unit 200 is arranged for communication with said second temperaturesensor 252 via a link L252. Said first control unit 200 can be arranged to receive information from said second temperature sensor 252.
    Said system 299 further comprises second means for measuring a pressure value. Said secondmeans for measuring a pressure value can be a second pressure sensor 253. Said secondpressure sensor 253 is arranged at the in|et manifold 230. Said second pressure sensor 253 is arranged to measure the pressure pan in the in|et manifold 230.
    Said first control unit 200 is arranged to control operation of said second pressure sensor 253.Said first control unit 200 is arranged for communication with said second pressure sensor 253via a link L253. Said first control unit 200 can be arranged to receive information from said second pressure sensor 253.
    Said system 299 further comprises means for determining a flow of air into the gas engine and/or means for determining a mass of air in a cylinder of the gas engine. ln one example, said means for determining a flow of air into the gas engine and/or means fordetermining a mass of air in a cylinder of the gas engine comprise a mass air flow sensor, I/|AF-sensor, 251. Said I/IAF-sensor 251 can be a hot film air mass sensor, HFI/I-sensor. Said I/|AF- sensor 251 is arranged for measuring an air mass flow in the air in|et 241.
    Said first control unit 200 is arranged to control operation of MAF-sensor 251. Said firstcontrol unit 200 is arranged for communication with said I/IAF-sensor 251 via a link L251. Said first control unit 200 can be arranged to receive information from said I/IAF-sensor 251. 11ln one example, said means for determining a flow of air into the gas engine and/or means fordetermining a mass of air in a cylinder of the gas engine comprise means for determining aflow through the throttle 260. Said means for determining a flow through the throttle 260 can,for example, comprise a third pressure sensor at the air inlet 241 and a third temperaturesensor at the air inlet 241 (not shown). Said means for determining a flow through the throttle260 can also comprise means for determining an effective area of the throttle. Said effectivearea relates to an effective area through which the air can flow from the air inlet 241 throughthe throttle. Said means for determining an effective area of the throttle can comprise asensor for determining an angle of a throttle flap. The first control unit 200 can then bearranged to calculate the flow of air mass through the throttle based on the measurementresults of at least one of said third temperature sensor, said third pressure sensor and said sensor for determining an angle of a throttle flap. ln one example, the mass of air in a cylinder of the gas engine can be determined by said firstcontrol unit 200. This can, for example, be done based on a volumetric efficiency, VE, of thecylinder and the ideal gas law. The VE is defined as the ratio of air in the cylinder when no fuelis present in relation to VCW. The VE is generally less than one since also exhaust gas residualsmight be present in the volume of the cylinder. Values for the VE might be stored in said first control unit 200. ln one example, said values for the VE depend on pan and/or Tin.
    Said first control unit 200 is arranged for determining, during operation of the gas engine 210,the specific gas constant of a fuel gas for the gas engine 210. A way of doing this is described in relation to Fig. 3 and 4.
    Said first control unit 200 is arranged for determining the stoichiometric air fuel ratio of the fuel gas for the gas engine 210. A way of doing this is described in relation to Fig. 3 and 4.
    Said first control unit 200 is arranged for adapting the control of the gas engine 210 based onthe determined specific gas constant and the determined stoichiometric air fuel ratio. Saidadapting the control of the gas engine 210 can comprise adapting the amount of fuel injectedinto the gas engine 210. This is in one example done by adapting tinj. Said adapting the controlof the gas engine 210 can comprise adapting the amount of air injected into the gas engine210. This is in one example done by adapting the amount of air which can pass the throttle 260. This is in one example done by controlling the throttle flap. Said adapting the control of 12the gas engine 210 can comprise adapting the control of an exhaust gas recirculation, EGR (notshown). Said adapting the control of the gas engine 210 can comprise adapting a time ofignition in a cylinder of the gas engine 210. A person skilled in the art will realise that the control of a gas engine can relate to other parameters then those named here.
    Adapting the control of the gas engine 210 based on the stoichiometric air fuel ratio and thespecific gas constant of the fuel gas allows minimising fuel consumption and emissions. lt alsoallows increasing drivability of the gas engine 210. A further advantage of system 299 is thatmost or all of its components present in nowadays vehicles. The present invention can thus beapplied to present vehicles via software updates, without the need of any new hardware alTaHgemeHtS. lt should also be understood that one or more of the measured parameters which aredescribed in this application can instead be estimated or pre-determined. This is especiallyuseful when the component of the system 299 which corresponds to measuring theparameter is not present at a present vehicle. Said estimation can, for example, be performedby said first control unit 200. Said estimation can, for example, be based on measurementresults from the remaining sensors and/or a model of the fuel/air/engine system in the corresponding vehicle.
    A second control unit 205 is arranged for communication with the first control unit 200 via alink L205 and may be detachably connected to it. lt may be a control unit external to thevehicle 100. lt may be adapted to conducting the innovative method steps according to theinvention. The second control unit 205 may be arranged to perform the inventive methodsteps according to the invention. lt may be used to cross-load software to the first control unit200, particularly software for conducting the innovative method. lt may alternatively bearranged for communication with the first control unit 200 via an internal network on boardthe vehicle. lt may be adapted to performing substantially the same functions as the firstcontrol unit 200, such as adapting engine control of a gas engine in a vehicle. The innovativemethod may be conducted by the first control unit 200 or the second control unit 205, or by both of them. 13ln Fig. 3 a flowchart of an example of a method 300 for adapting engine control of a gasengine in a vehicle is schematically illustrated. The method starts with an optional step 310. ltshould be emphasised that the steps of the method 300 not necessarily have to be performedin the order at which they are presented. The order of the steps is only limited in so far thatone step might need the result of another step as input. Where this is not the case, the steps might be performed in any order, or in parallel. ln the optional step 310 measurements are performed in the vehicle 100. ln one example, ameasurement of pm" is performed by said first pressure sensor 255. ln one example, ameasurement of Tran is performed by said first temperature sensor 254. ln one example, ameasurement of pin is performed by said second pressure sensor 253. ln one example, ameasurement of Tin is performed by said second temperature sensor 252. ln one example, ameasurement of Å is performed by said lambda sensor 250. ln one example, a mass air flow ismeasured by said I/IAF-sensor 251. ln one example the angle of a throttle flap of the throttle 260 is measured. ln one example tim- of said gas injector 270 is measured. ln relation to step 330 and to step 340 several alternatives will be described how the specificgas constant and/or AFRS can be determined. The measurements which are performed in step310 are preferably adapted to which parameters are needed in the respective chosen way fordetermining the specific gas constant and/or AFRS. lt should, however, also be understood thatone or several of the needed parameters which will be described in relation to step 330 andstep 340 can be pre-determined and, for example, stored in control unit. Alternatively, one orseveral of the needed parameters which will be described in relation to step 330 and step 340can be determined based on one or several of the other measured parameters which are described here.
    One such example is that a mass air flow measured by the I/IAF-sensor 251 can be replaced bydetermining the effective area of the throttle 260 and a measurement of the pressure and thetemperature in the air inlet. This can be done via said third pressure sensor and said thirdtemperature sensor. Determining the effective area of the throttle 260 comprises in oneexample measuring an angle of a throttle flap. ln another example no measurement isperformed for determining the effective area of the throttle 260. This can be achieved by sending a control signal to the throttle flap, where a specific control signal corresponds to a 14specific angle of the throttle flap. By knowing the control signal the angle of the throttle flap and thus the effective area can be derived without an additional measurement, see step 325.
    Even the measurement of other of the parameters described in step 330 and step 340 can bereplaced by assumptions and/or by deriving them from the measurement results of other measurements. After step 320 an optional step 320 is performed. ln the optional step 320 a time period of gas injection tim- is determined. This is in one exampledone by measuring the time period of gas injection. ln one example the time period of gasinjection depends on a control signal which is sent from the first control unit 200 to the gasinjector 270. The first control unit 200 can then derive tim- from the control signal without the need of performing a measurement. The method continues with the optional step 325. ln the optional step 325 a flow of air into the gas engine is determined and/or a mass of air ina cylinder of the gas engine is determined. ln one example this is done based on measuringthe mass air flow with the I/IAF-sensor 251. ln one example this is done via determining theeffective area of the throttle. This has been described in more detail above, for example in relation to step 310. The method continues with step 330. ln step 330, during operation of the gas engine, the specific gas constant, RFG, of the fuel gasfor the gas engine is determined. This can be done based on the determined time period ofgas injection in step 320. This can be done based on the result of one or more performedmeasurements, for example those described in relation to step 310. This can be done basedon the determined flow of air into the gas engine and/or the determined mass of air in the cylinder of the gas engine as described in step 325. ln one example, the specific gas constant RPG can be determined via the following relation: pÜLVFGm 2RFG<>< i _prailTintinjACDl-/J ln one example equality is used in the above relation. ln one example, one or several additional conversion constants are used in the above relation.
    L|J is a nozzle flow factor, which in one example is a constant value. This is especially the case in a so-called sonic velocity regime where the pressure ratio p, over the nozzle of the gas injector 270 is below a certain critical value pc, wherein pr=prrr/prr,r|. ln one example L|J depends on thepressure ration over the nozzle pr. This is especially the case in a so-called subsonic velocityregime where the pressure ratio pr over the nozzle of the gas injector 270 is above the criticalvalue pc. Values for L|J, either constant values and/or values depending on pr can be stored in the first control unit 20.
    VFGin denotes the volume of the injected fuel gas and is in general dependent on the temperature and the pressure in the inlet manifold 230. ln one example, VFGin can be determined via the equation VFGin = (VE-VEFG)*VCV|, wherein VEFG denotes the volumetric efficiency of the gas engine when running on the fuel gas. ln oneexample, VEFG can be determined via the relation VEFG = marr*Rarr*Trrr/(prrr*Vcy|), where Rarr is the specific gas constant of air and marr is the mass of air in the cylinder. lt should be understood that the above examples of how RFG, VFGin and VEFG can be determined are only presented for showing an enabling example of the present invention.
    There are different ways of determining RFG, VFGin and VEFG, for example by measuring different values and/or by deriving one or more of the values based on assumptions and/orinformation already present in the first control unit 200. Said deriving is in one example basedon control signals. Said control signals can relate to components which are not present in Fig.2 but well known in the art for constructing vehicles with gas engines. The present inventioncan thus be adapted to different kinds of vehicles with gas engines. The present step isperformed during operation of the gas engine. The whole method can be performed duringoperation of the gas engine. This has the advantage that a driver does not need to wait for themethod to be performed when driving and thus will not experience any negative effects oftime delays or similar. Further, the method is performed at the vehicle alone. Thus, there is noneed to develop any interfaces to fuel stations or similar. The present method can thus beused with any fuel gas from any supplier without the need of additional investments for asupplier. Further, investments for vehicle constructors are neither needed since sensors andthe like which are already present in the vehicle can be used. The method continues with step 340. 16ln step 340 the stoichiometric air fuel ratio AFRS of the fuel gas for the gas engine isdetermined. This can be done based on the determined time period of gas injection in step320. This can be done based on the result of one or more performed measurements, forexample those described in relation to step 310. This can be done based on the determinedflow of air into the gas engine and/or the determined mass of air in the cylinder of the gas engine as described in step 325. ln the following, some examples are presented how AFRS can be determined: RPGAFRS zVE ' _ Å. I Rai -. R .AFRS = ,vFGinÄ I TinR 1AFRS = AFRS F” - ref RFGTef Äc I Some vehicles assume a reference fuel gas for a gas engine. This reference fuel gas has then an assumed reference stoichiometric air-fuel ratio AFRSref and an assumed reference specificgas constant RFGref. A lambda controller in those vehicles usually produces a control factor Åc for an actual fuel gas which is multiplied by a so-called fuel factor to achieve Å=1. For those vehicles the last of the above three equations can be used.
    The above equations show that AFRS can be determined in a number of different ways. Theabove examples are not limiting and a person skilled in the art will realise that yet otherequations can be used for determining AFRS. A suitable equation is preferably chosen based onwhich sensors are present in the vehicle and/or which values can be easily determined by a control unit in the vehicle. The method continues with step 350. ln step 350 the control of the gas engine is adapted based on the determined specific gas constant and based on the determined stoichiometric air fuel ratio.
    Said adaption of the control of the gas engine comprises in one example adapting the amountof fuel injected into the gas engine. Said adapting of the control of the gas engine comprises in one example adapting tinj. Said adapting of the control of the gas engine comprises in one 17example adapting the amount of air injected into the gas engine. This is in one example doneby controlling the throttle flap. Said adapting of the control of the gas engine can compriseadapting the control of an exhaust gas recirculation, EGR. Said adapting the control of the gasengine can comprise adapting a time of ignition in a cylinder of the gas engine. Depending onthe design of the gas engine there are other parameters as well which can be adapted. Aperson skilled in the art will be aware of which other parameters are present at a specific gasengine. Some advantages of the adaptions based on AFRS and RFG are lower fuel consumption and/or lower amount of certain exhausts from the gas engine.After step 350 the method ends.
    The method or parts of the method can be performed repeatedly. As an example, none of thesteps 300-340 does affect driveability of the vehicle. These steps can thus be performed atpre-determined time intervals or continuously. Even step 350 can be performed at pre-determined time intervals or continuously. An adaption in step 350 can be made dependenton that a determined AFRS and/or a determined RPG differs from a previously assumed ordetermined AFRS and/or RFG with more than a predetermined threshold. ln one example, anaverage of AFRS and/or a RPG is taken over different runs of the steps 310-340 before step 350is performed. ln one example the method is performed when a refuelling of the gas tank 220is detected. ln one example, AFRS and/or RFG are determined by different equations and an average value of AFRS and/or RFG is taken before step 350 is performed.
    Figure 4 is a diagram of one version of a device 500. The control units 200 and 205 describedwith reference to Figure 2 may in one version comprise the device 500. The device 500comprises a non-volatile memory 520, a data processing unit 510 and a read/write memory550. The non-volatile memory 520 has a first memory element 530 in which a computerprogram, e.g. an operating system, is stored for controlling the function of the device 500. Thedevice 500 further comprises a bus controller, a serial communication port, I/O means, an A/Dconverter, a time and date input and transfer unit, an event counter and an interruptioncontroller (not depicted). The non-volatile memory 520 has also a second memory element 540. 18The computer program comprises routines for adapting engine control of a gas engine in a vehicle.
    The computer program P may comprise routines for determining, during operation of the gasengine, the specific gas constant of a fuel gas for the gas engine. This may at least partly beperformed by means of said first control unit 200 controlling operation of any of the sensors250-255, and/or the throttle 260, and/or the gas injector 270. Said specific gas constant may be stored in said non-volatile memory 520.
    The computer program P may comprise routines for determining the stoichiometric air fuelratio of the fuel gas for the gas engine. This may at least partly be performed by means of saidfirst control unit 200 controlling operation of any of the sensors 250-255, and/or the throttle260, and/or the gas injector 270. Said stoichiometric air fuel ratio of the fuel gas for the gas engine may be stored in said non-volatile memory 520.
    The computer program P may comprise routines for adapting the control of the gas enginebased on the determined specific gas constant and the determined stoichiometric air fuel ratio.
    The computer program P may comprise routines for determining a time period of gas injection.
    The computer program P may comprise routines for performing at least one measurement inthe vehicle. Said at least one measurement can comprise at least one temperaturemeasurement and/or at least one measurement of temperature. Said at least onemeasurement can comprise a measurement of a Å value. This may at least partly beperformed by means of said first control unit 200 controlling operation of any of the sensors250-255, and/or the throttle 260, and/or the gas injector 270. The result of said performed at least one measurement may be stored in said non-volatile memory 520.
    The computer program P may comprise routines for determining a flow of air into the gas engine 210 and/or for determining a mass of air in a cylinder ofthe gas engine 210.
    The program P may be stored in an executable form or in compressed form in a memory 560 and/or in a read/write memory 550. 19Where it is stated that the data processing unit 510 performs a certain function, it means thatit conducts a certain part of the program which is stored in the memory 560 or a certain part of the program which is stored in the read/write memory 550.
    The data processing device 510 can communicate with a data port 599 via a data bus 515. Thenon-volatile memory 520 is intended for communication with the data processing unit 510 viaa data bus 512. The separate memory 560 is intended to communicate with the dataprocessing unit via a data bus 511. The read/write memory 550 is arranged to communicatewith the data processing unit 510 via a data bus 514. The links L205, L210, L250-255, and L270, for example, may be connected to the data port 599 (see Figure 2).
    When data are received on the data port 599, they can be stored temporarily in the secondmemory element 540. When input data received have been temporarily stored, the data processing unit 510 can be prepared to conduct code execution as described above.
    Parts of the methods herein described may be conducted by the device 500 by means of thedata processing unit 510 which runs the program stored in the memory 560 or the read/write memory 550. When the device 500 runs the program, methods herein described are executed.
    The foregoing description of the preferred embodiments of the present invention is providedfor i|ustrative and descriptive purposes. lt is neither intended to be exhaustive, nor to limitthe invention to the variants described. I/|any modifications and variations will obviouslysuggest themselves to one skilled in the art. The embodiments have been chosen anddescribed in order to best explain the principles of the invention and their practicalapplications and thereby make it possible for one skilled in the art to understand the inventionfor different embodiments and with the various modifications appropriate to the intended USS.
    权利要求:
    Claims (8)
    [1] 1. A method for adapting engine control of a gas engine in a vehicle, the methodcomprising the steps of: - determining, during operation of the gas engine, the specific gas constant of afuel gas for the gas engine; - determining the stoichiometric air fuel ratio of the fuel gas for the gas engine;and - adapting the control of the gas engine based on the determined specific gasconstant and the determined stoichiometric air fuel ratio.
    [2] 2. The method according to claim 1, wherein said determining of the specific gasconstant and/or the stoichiometric air fuel ratio is based on a determined timeperiod of gas injection.
    [3] 3. The method according to claim 1 or 2, further comprising the step of performingmeasurements in the vehicle, wherein said determining of the specific gas constantand/or said determining of the stoichiometric air fuel ratio is based on a result ofsaid performed measurements.
    [4] 4. The method according to claim 3, wherein said performed measurements comprisemeasuring a pressure value and a temperature value in the inlet.
    [5] 5. The method according to claim 3 or 4, wherein said performed measurementscomprise measuring a temperature value and/or a pressure value of the fuel gasupstream of a gas injector.
    [6] 6. The method according to anyone of claim 3-5, wherein said performedmeasurements comprise measuring a Å value by means of a lambda sensor beingprovided downstream said gas engine.
    [7] 7. The method according to anyone of claim 1-6, further comprising the step ofdetermining a flow of air into the gas engine and/or determining a mass of air in acylinder of the gas engine, wherein said determining of the specific gas constantand/or the stoichiometric air fuel ratio is based on said determined flow of air intothe gas engine and/or said determined mass of air in the cylinder ofthe gas engine.
    [8] 8. A system for adapting engine control of a gas engine in a vehicle, the system comprising: 10. 11. 12. 13. 14. 21- means for determining, during operation of the gas engine, the specific gasconstant of a fuel gas for the gas engine;- means for determining the stoichiometric air fuel ratio of the fuel gas for thegas engine; and- means for adapting the control of the gas engine based on the determinedspecific gas constant and the determined stoichiometric air fuel ratio. The system according to claim 8, further comprising means for determining a timeperiod of gas injection, wherein said means for determining the stoichiometric airfuel ratio of the fuel gas for the gas engine and/or said means for determining,during operation of the gas engine, the specific gas constant of a fuel gas for the gasengine are arranged for basing said determining of the stoichiometric air fuel ratioand/or said specific gas constant on said determined time period of gas injection.The system according to claim 8 or 9, further comprising means for performingmeasurements in the vehicle, wherein said means for determining the specific gasconstant and/or said means for determining the stoichiometric air fuel ratio arearranged to base the determining on a result of said performed measurements.The system according to claim 10, wherein said means for performing measurementscomprise means for measuring a pressure value and a temperature value in the inletmanifold.The system according to claim 10 or 11, wherein said means for performingmeasurements comprise means for measuring a temperature value and/or apressure value of the fuel gas upstream of a gas injector.The system according to anyone of claim 10-12, wherein said means for performingmeasurements comprise a lambda sensor arranged downstream said gas engine,wherein the lambda sensor is arranged for measuring a Å value.The system according to anyone of claim 8-13, further comprising further means fordetermining a flow of air into the gas engine and/or means for determining a mass ofair in a cylinder of the gas engine, wherein said means for determining the specificgas constant and/or said means for determining the stoichiometric air fuel ratio arearranged for basing said determining of the specific gas constant and/or thestoichiometric air fuel ratio on said determined flow of air into the gas engine and/or said determined mass of air in the cylinder ofthe gas engine. 15.16. 17. 22 A vehicle, comprising a system according to any of claims 8-14. A computer program (P) for adapting engine control of a gas engine in a vehicle,wherein said computer program (P) comprises program code for causing anelectronic control unit (200; 500) or a computer (205; 500) connected to theelectronic control unit (200; 500) to perform the steps according to any of the claims1-7. A computer program product containing a program code stored on a computer-readable medium for performing method steps according to any of claims 1-7, whensaid computer program is run on an electronic control unit (200; 500) or a computer (205; 500) connected to the electronic control unit (200; 500).
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    同族专利:
    公开号 | 公开日
    BR112018015327A2|2018-12-18|
    SE541091C2|2019-04-02|
    WO2017164795A1|2017-09-28|
    KR20180118228A|2018-10-30|
    CN108779722A|2018-11-09|
    US20190101068A1|2019-04-04|
    EP3433478A1|2019-01-30|
    EP3433478A4|2019-11-06|
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    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    SE1650386A|SE541091C2|2016-03-23|2016-03-23|A method and a system for adapting engine control of a gas engine in a vehicle|SE1650386A| SE541091C2|2016-03-23|2016-03-23|A method and a system for adapting engine control of a gas engine in a vehicle|
    KR1020187029522A| KR20180118228A|2016-03-23|2017-03-20|Method and system for adjusting engine control of a gas engine in a vehicle|
    US16/085,980| US20190101068A1|2016-03-23|2017-03-20|A method and a system for adapting engine control of a gas engine in a vehicle|
    PCT/SE2017/050264| WO2017164795A1|2016-03-23|2017-03-20|A method and a system for adapting engine control of a gas engine in a vehicle|
    CN201780015332.9A| CN108779722A|2016-03-23|2017-03-20|A kind of method and system of engine control for adjusting the gas engine in vehicle|
    EP17770708.0A| EP3433478A4|2016-03-23|2017-03-20|A method and a system for adapting engine control of a gas engine in a vehicle|
    BR112018015327A| BR112018015327A2|2016-03-23|2017-03-20|Method and system for adapting engine control of a gas engine to a vehicle|
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