SE539374C2

SE539374C2 - Method and system for determining an available engine torqueduring a gear shift operation

Info

Publication number: SE539374C2
Application number: SE1550983A
Authority: SE
Inventors: Nordin Mikael; Jacobsson Susanna
Original assignee: Scania Cv Ab
Priority date: 2015-07-07
Filing date: 2015-07-07
Publication date: 2017-08-22
Also published as: SE1550983A1; BR102016015691A2; BR102016015691B1; DE102016007717A1; DE102016007717B4

Abstract

36 ABSTRACT The present invention relates to a method for determining an availableengine torque of a vehicle during a gear shift operation (A, B, C, D) prior toperforming said gear shift operation. The method comprises the step of:determining a development (D, D1) of available engine torque from a certainlevel of available engine torque (P1, P2) up to an engine torque (P3, P3a)corresponding to a demanded engine torque. The present invention also relates to a system for determining an availableengine torque of a vehicle during a gear shift operation prior to performingsaid gear shift operation. The present invention also relates to a computerprogram and a computer program product. (Fig. 2)

Description

METHOD AND SYSTEM FOR DETERMINING AN AVAILABLE ENGINETORQUE DURING A GEAR SHIFT OPERATION TECHNICAL FIELD The invention relates to a method for determining an available engine torqueduring a gear shift operation prior to performing said gear shift operationaccording to the preamble of claim 1. The invention also relates to a systemfor determining an available engine torque during a gear shift operation priorto performing said gear shift operation. The invention also relates to avehicle. The invention in addition relates to a computer program and acomputer program product.

BACKGROUND ART For automatic or semi-automatic transmissions the gear shift operation isperformed based on an assessed available engine torque.

The gear shift operation comprises an off-ramp phase in which the torque isreduced to substantially zero. Then there is a synchronisation phase in whichthe gear shift is completed by disengaging the current gear and engaging thechosen gear. During the synchronisation phase the engine is synchronized tothe next target speed. After the synchronisation phase the gearbox controllerreturns the torque control to the driver demanded torque. The driver demandtorque is supplied to the engine, increasing the available torque up to a levelwhere an exhaust gas smoke limiting function of the combustion engine limitsthe development of available engine torque up to a driver demand torque. ln order to assess the gear shift tests are made with the specific vehicle inorder to determine the available engine torque. This however does not provide an accurate assessment in that the engine torque may vary due to the boost pressure to such an extent that the chosen gear is not the most suitable gear.

There is thus a need for improving determination of available engine torqueduring a gear shift operation.

OBJECTS OF THE INVENTION An object of the present invention is to provide a method for determining anavailable engine torque during a gear shift operation prior to performing saidgear shift operation which provides a more accurate a basis for the gear shift operation.

Another object of the present invention is to provide a system for determiningan available engine torque during a gear shift operation prior to performingsaid gear shift operation which provides a more accurate a basis for the gear shift operation.

SUMMARY OF THE INVENTION These and other objects, apparent from the following description, areachieved by a method, a system, a vehicle, a computer program and acomputer program product, as set out in the appended independent claims.Preferred embodiments of the method and the system are defined inappended dependent claims.

Specifically an object of the invention is achieved by a method fordetermining an available engine torque of a vehicle during a gear shiftoperation prior to performing said gear shift operation. The methodcomprises the step of: determining a development of available engine torquefrom a certain level of available engine torque up to an engine torque corresponding to a demanded engine torque. Hereby a more accurate abasis for the gear shift operation is provided such that the correct gear ischosen prior to the gear shift operation. By thus determining the developmentof available engine torque after the determined available engine torque, i.e.how long it will take from that torque up to the demanded engine torque, aneven more accurate basis for the gear shift operation is provided such thatthe correct gear is chosen prior to the gear shift operation. This furtherfacilitates diagnosing the boost pressure system in that a deviation from thedetermined point of time when the demanded engine torque is to be reachedwould indicate a leakage in the boost pressure system, and if the point oftime is correct it would indicate that the boost pressure system is workingcorrectly.

According to an embodiment of the method the step of determining adevelopment of available engine torque from a certain level of availableengine torque up to an engine torque corresponding to a demanded enginetorque comprises the step of determining an estimation of a linear functionwith a certain torque development increase rate. Hereby an efficient way of estimating the development of available engine torque is facilitated.

According to an embodiment of the method the step of determining adevelopment of available engine torque from a certain level of availableengine torque up to an engine torque corresponding to a demanded enginetorque comprises the step of, for a certain number of different enginerotational speeds, estimating the maximum engine torque and the responsetime for the engine from motoring to the maximum engine torque. Hereby anefficient way of estimating the development of available engine torque isfacilitated. The estimation of response time for the engine from motoring tothe maximum engine torque is according to an embodiment obtained by calibration of the engine in a testbed.

According to an embodiment of the method said certain level corresponds toactivation of Iimitation of available engine torque provided by an exhaust gassmoke limiting function of a combustion engine control system of the vehicle.

According to an embodiment of the method the available engine torquecorresponding to activation of limitation of engine torque is determined basedon a determined boost pressure drop during said gear shift operation. Herebya more accurate a basis for the gear shift operation is provided such that thecorrect gear is chosen prior to the gear shift operation.

According to an embodiment the method comprises the step of taking saiddetermined development of available engine torque as a basis for said gearshift operation. Hereby the gear shift operation will be improved.

According to an embodiment the method comprises the step of taking saiddetermined development of available engine torque as a basis for diagnosingthe boost pressure system of the vehicle engine. Hereby diagnosing of theboost pressure system of the vehicle engine will be improved.

Specifically an object of the invention is achieved by a system for determiningan available engine torque of a vehicle during a gear shift operation prior toperforming said gear shift operation. The system comprises means fordetermining a development of available engine torque from a certain level ofavailable engine torque up to an engine torque corresponding to a demanded engine torque.

According to an embodiment of the system the means for determining adevelopment of available engine torque from a certain level of availableengine torque up to an engine torque corresponding to a demanded enginetorque comprises means for determining an estimation of a linear function with a certain torque development increase rate.

According to an embodiment of the system the means for determining adevelopment of available engine torque from a certain level of available engine torque up to an engine torque corresponding to a demanded enginetorque comprises means for estimating the maximum engine torque and theresponse time for the engine from motoring to the maximum engine torque for a certain number of different engine rotational speeds.

According to an embodiment of the system said certain level corresponds toactivation of limitation of available engine torque provided by an exhaust gassmoke |imiting function of a combustion engine control system of the vehicle.

According to an embodiment of the system means for determining theavailable engine torque corresponding to activation of Iimitation of enginetorque based on a determined boost pressure drop during said gear shiftoperation.

According to an embodiment the system comprises means for taking saiddetermined development of available engine torque as a basis for said gear shift operation.

According to an embodiment the system comprises means for taking saiddetermined development of available engine torque as a basis for diagnosingthe boost pressure system of the vehicle engine.

The system according to the invention has the advantages according to thecorresponding method.

Specifically an object of the invention is achieved by a vehicle comprising asystem according to the invention.

Specifically an object of the invention is achieved by a computer program fordetermining an available engine torque during a gear shift operation prior toperforming said gear shift operation, said computer program comprisingprogram code which, when run on an electronic control unit or anothercomputer connected to the electronic control unit, causes the electronic control unit to perform the method according to the invention.

Specifically an object of the invention is achieved by a computer program product comprising a digital storage medium storing the computer program.

BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of the present invention reference is made to thefollowing detailed description when read in conjunction with theaccompanying drawings, wherein like reference characters refer to like parts throughout the several views, and in which: Fig. 1 schematically illustrates a side view of a vehicle according to the present invention;Fig. 2 schematically illustrates executed torque during a gear shift operation; Fig. 3a schematically illustrates the boost pressure drop during a gear shiftoperation for different boost pressures prior to the gear shift operation; Fig. 3b schematically illustrates the boost pressure drop during a gear shiftoperation for different boost pressures change rates prior to the gear shiftoperation; Fig. 4 schematically illustrates a system for determining an available enginetorque during a gear shift operation prior to performing said gear shiftoperation according to an embodiment of the present invention; Fig. 5 schematically illustrates a block diagram of a method for determiningan available engine torque during a gear shift operation prior to performingsaid gear shift operation according to an embodiment of the present invenüon;and Fig. 6 schematically illustrates a computer according to an embodiment of the present invention.

DETAILED DESCRIPTION Hereinafter the term “link” refers to a communication link which may be aphysical connector, such as an optoelectronic communication wire, or a non-physical connector such as a wireless connection, for example a radio or microwave link.

Hereinafter the term “demanded torque”, “demanding a torque”, “demandedengine torque” or the like for a vehicle refers to a torque demanded by thedriver of the vehicle, or by any suitable torque demanding function such as acruise control torque demanding function, i.e. a torque demanding functionprovided by a cruise control system, or a speed limiter torque demandingfunction, i.e. a torque demanding function provided by a speed limitersystem. The torque may thus be demanded by the driver of the vehicle or any other suitable torque demanding function.

Fig. 1 schematically illustrates a side view of a vehicle 1 according to thepresent invention. The exemplified vehicle 1 is a heavy vehicle in the shapeof a truck. The vehicle according to the present invention could be anysuitable vehicle such as a bus or a car. The vehicle is driven by means of aninternal combustion engine being turbocharged by means of a turbocompressor configured to compress air in to the cylinders of the engine. Thevehicle comprises an automatic or semi-automatic transmission configured toprovide automatic gear shift operation during drive of the vehicle. The vehiclecomprises a combustion engine control system having an exhaust gaslimiting function for limiting exhaust gas smoke during combustion by limiting the allowable amount of fuel to the cylinders when applicable.

The vehicle 1 comprises a system I for determining an available enginetorque during a gear shift operation prior to performing said gear shift operation.

Fig. 2 schematically illustrates executed torque during a gear shift operation.The gear shift operation in fig. 2 is an up-shift operation, i.e. shift from a lowergear to a higher gear. ln an up-shift operation there is a decrease in enginerotational speed. The up-shift operation is an example. The invention isequally applicable to a down-shift operation.

The gear shift operation comprises an off-ramp phase A in which the torqueT is reduced to substantially zero.

Then there is a gear disengagement, synchronisation and gear engagementphase B in which the gear shift is completed. The synchronisation phase Bcomprises a disengagement phase B1 in which a gear shift disengagementof the current gear is effected. The phase B comprises a synchronisationphase B2 in which no gear is connected. The phase B comprises anengagement phase B3 in which a gear shift engagement to the changed gear is effected. The gear shift engagement is initiated in point P1.

After the phase B including the synchronisation phase B2 and the change ofactual gear in the gear disengagement phase B1 to target gear in the gearengagement phase B3, an on-ramp phase C is initiated, in which fuelcorresponding to the demanded torque to the engine is supplied, increasingthe available torque up to a level in the point P2 where an exhaust gassmoke limiting function of the combustion engine is arranged to limit thedevelopment of available engine torque.

The gear shift operation thus comprises a smoke limiting development phaseD of the available torque up to an engine torque corresponding to ademanded torque reached in the point P3.

The development of available engine torque from the point P2, i.e. the pointfor activation of limitation of available engine torque provided by an exhaustgas smoke limiting function of a combustion engine control system of thevehicle, up to an engine torque corresponding to a demanded engine torqueis determined. The change rate of the available engine torque from the point P2 up to the demanded engine torque in point P3 is thus assessed prior to the gear shift operation.

The development of available engine torque from point P2 to point P3comprises according to an embodiment determining an estimation of a linear function with a certain torque development increase rate.

The determination of linear function with a certain torque developmentincrease rate is according to an embodiment provided by means of testbeds,i.e. calibration of the engine in which the time required to reach thedemanded engine torque from the point P2 of limitation is determined. Thecalibration of the engine comprises performing motoring, driving the engine atfull load and determining the engine torque at full load and then performingmotoring again. Motoring is performed over a short time span. Thiscalibration of the engine is performed for different engine rotational speeds.

The torque at full load is also denoted maximum engine torque.

The determination of linear function with a certain torque developmentincrease rate is according to an embodiment provided by means of modellingthe torque development increase rate.

The calibration test is engine specific in that the torque at full load fordifferent engine rotational speeds varies for different engines. ln this calibration test certain parameters are taken into account comprisingnumber of cylinders of the engine and losses needed to be overcome in order to rotate the engine one revolution.

The development of available engine torque from point P2 to point P3 isdetermined prior to the gear shift operation by means of assessing themaximum engine torque at full load for the engine as a function of the enginerotational speed and dividing that torque with the response time from motoring to the maximum engine torque.

The response time from motoring to maximum torque is determined bymeans of a response time factor as a function of the engine rotational speedtimes the maximum engine torque as a function of the engine rotationalspeed divided by a torque factor as a function of number of cylinders of the engine.

The maximum torque as a function of the engine rotational speed is providedfrom the engine control system as a torque or as an amount of fuel.

The response time factor as a function of the engine rotational speed iscalculated in a function comprising the engine rotational speed.

The torque factor as a function of number of cylinders of the engine is afunction where the number of cylinders of the engine is included as a parameter.

The determined development of available engine torque is taken as a basis for the gear shift operation.

Above, the development of engine torque has been determined from acertain level P2 corresponding to activation of limitation of available enginetorque provided by an exhaust gas smoke limiting function of a combustion engine control system of the vehicle.

The development of engine torque may be determined from any suitablelevel. The development of engine torque is according to an embodimentdetermined from the point P1, i.e. from the point where the gear shiftengagement has been initiated. The determined development from the pointP1 will have the same inclination resulting in the demanded engine torquebeing reached at a late stage, i.e. in point P3a.

Determining the development of engine torque further facilitates diagnosingthe boost pressure system of the vehicle in that a deviation from thedetermined point P3 of time when the demanded engine torque is to bereached would indicate a leakage in the boost pressure system. Thus, if the 11 actual point P4 where the demanded engine torque is reached is determinedto deviate from the estimated point P3 Ieakage of the boost pressure systemis indicated. lf the actual point P3 where the demanded engine torque isreached is determined to substantially correspond to the estimated point P3the boost pressure system is indicated to function correctly. This diagnosingis equally applicable if the development of engine is determined from anotherlevel of available engine torque, e.g. from the point P1.

Thus, the determined development of available engine torque is taken as abasis for diagnosing the boost pressure system of the vehicle engine. ln order to determine the available torque up to a level in the point P2 wherean exhaust gas smoke limiting function of the combustion engine is arrangedto limit the development of available engine torque prior to the gear shiftoperation the current engine boost pressure is determined intermittently orcontinuously. The engine boost pressure may according to an embodimentbe determined several times per second in order to have a good basis inconnection to a gear shift operation. The engine boost pressure is according to an embodiment determined by means of a pressure sensor unit.

The boost pressure drop corresponding to the determined engine boostpressure during a gear shift of the gear shift operation is determined bycomparing the determined boost pressure to the boost pressure drop at sucha boost pressure which has been assessed by plotting boost pressure dropsduring phase A and B of the gear shift operation for different boost pressuresdetermined for the particular vehicle by performing tests with a vehicle. Anexample of such a plot is illustrated in fig. 3a. The boost pressure inconnection to gear shift engagement, i.e. the boost pressure in point P1 infig. 2, thus corresponds to the determined boost pressure subtracted by the corresponding boost pressure drop.

For situations where the engine boost pressure prior to the gear shiftoperation is relatively low and increasing the boost pressure drop is 12 determined by comparing a determined boost pressure change rate prior tothe gear shift operation. Such a situation for engine boost pressures below acertain level may typically be a vehicle starting situation where the vehicle isaccelerated from a standstill or close to a standstill by a demanded torque.This situation may occur at a stop at a red light, in a roundabout or the like.

Such a situation may also occur when demanding a torque after motoring.

The boost pressure drop corresponding to the determined engine boostpressure change rate during a gear shift of the gear shift operation for such asituation of low and increasing boost pressure is determined by comparingthe determined boost pressure change rate to the boost pressure drop atsuch a boost pressure which has been assessed by plotting boost pressuredrops during phase A and B of the gear shift operation for different boostpressures change rates determined for the particular vehicle. An example ofsuch a plot is illustrated in fig. 3b. The boost pressure in connection to gearshift engagement, i.e. the boost pressure in point P1 in fig. 2, thuscorresponds to the determined boost pressure subtracted by thecorresponding boost pressure drop determined from the corresponding boost pressure change rate.

The available engine torque at point P2 is determined based on the thusdetermined boost pressure in connection to gear shift engagement. Theavailable engine torque corresponding to activation of limitation of enginetorque is thus determined based on a determined boost pressure drop duringsaid gear shift operation.

For a certain boost pressure in connection to gear shift engagement at pointP1 for a certain engine rotational speed there is a certain lowest allowableair/fuel ratio. The air/fuel ratio is also called lambda Å.

Thus, a lowest allowable air/fuel ratio for said determined boost pressure inconnection to gear shift engagement is determined for a certain number ofdifferent engine rotational speeds. The lowest allowable lambda is according 13 to an embodiment obtained from a smoke limiter map containing data for lambda for the boost pressure in P1 for different engine rotational speeds.

An allowable amount of fuel is then determined based on the determinedIowest allowable air/fuel ratio. The current atmospheric pressure is herebyconsidered. The boost pressure at point P1, the boost temperature and theoxygen weight ratio are according to an embodiment also taken into accountin determining the allowable amount of fuel. For selective catalytic reduction(SCR) systems the exhaust gas recirculation (EGR) content is taken intoconsideration with regard to the Iowest allowable air/fuel ratio. Thestoichiometric air/fuel ratio, i.e. the theoretically necessary relationshipbetween fuel and air amount for accomplishing complete combustion, is alsotaken into account. The air, or rather oxygen, required for completecombustion may be determined if the chemical composition of the fuel is known.

Based on the determined allowable amount of fuel the torque at point P2 isdetermined by means of combustion efficiency for the certain boost pressure,and losses such as aggregate losses, i.e. losses of compressor, generator,fan; friction losses, cooling losses; pump losses. Such data is according to anembodiment provided from a map for the respective engine rotational speed.

Fig. 3a schematically illustrates the boost pressure drop during a gear shiftoperation for different boost pressures prior to the gear shift operation. ln the graph, the boost pressure drop has been determined for different boostpressures for 1-step shifts, 2-step shifts and 3-step shifts. ln the graph 1-stepshifts, 2-step shifts and 3-step shifts are illustrated as examples. For boostpressures above a certain level, here above approximately 1500 mbar, theboost pressure drop increases substantially linear, essentially independentlyof whether it is a 1-step shift, a 2-step shift or a 3-step shift. ln the graph 1-step shifts, 2-step shifts and 3-step shifts are illustrated as examples.However, all gear shifts are applicable, i.e. gear shifts higher than 3-step shift 14 such as 4-step shift, 5-step shift etc. are applicable and would result in the linear increase of boost pressure drop above the certain boost pressure.

During drive of the vehicle, the boost pressure is determined continuously orintermittently and for each determined boost pressure the boost pressuredrop that would be the result of a gear shift operation is determined from theplot. For example a determined boost pressure of 2500 mbar corresponds toa boost pressure drop of approximately 800 mbar in connection to a gearshift engagement should a gear shift operation be initiated. This results in aboost pressure in connection to gear shift engagement during a gear shiftoperation of 2500-800=1700 mbar, which is used as a basis for determiningthe available engine torque corresponding to activation of limitation of enginetorque provided by the exhaust gas smoke limiting function.

For low boost pressures, e.g. boost pressures below about 1500 mbar,illustrated with L in fig. 3a, the boost pressure drop may advantageously bedetermined by means of engine boost pressure change rate determined bymeans of the boost pressure prior to the gear shift operation. This isillustrated in fig. 3b.

Fig. 3b schematically illustrates the boost pressure drop during a gear shiftoperation for different boost pressures change rates prior to the gear shiftoperation.

The graph is determined for situations where the engine boost pressure priorto the gear shift operation is relatively low and increasing. Such an increasinglow level of boost pressure is below a certain level, e.g. about 1500 mbar.Such a situation may typically be a vehicle starting situation where thevehicle is accelerated from a standstill or close to a standstill by a demandedtorque. This situation may occur at a stop at a red light, in a roundabout orthe like. Such a situation may also occur when demanding a torque after motoring. ln the graph, the boost pressure drop has been determined for different boostpressure change rates for up-shifts for low gears, i.e. gears prior to gear shiftoperation being at 3 or lower, and for high gears, i.e. gears being at 4 orhigher. For such relatively low boost pressures up to a certain level, the boostpressure drop increases substantially linear with increasing boost pressurechange rate, essentially independently of whether it is a gear shift from lowgear or a gear shift from a high gear.

During drive of the vehicle, the boost pressure and the boost pressurechange rate is determined continuously or intermittently and for eachdetermined boost pressure change rate the boost pressure drop that wouldbe the result of a gear shift operation is determined from the plot. Forrate of 700 mbar/s corresponds to a boost pressure drop of approximately 900 mbar in example a determined boost pressure change connection to a gear shift engagement should a gear shift operation beinitiated. The boost pressure in connection to gear shift engagement during agear shift operation is determined by subtracting the determined boostpressure drop from the boost pressure corresponding to the determinedboost pressure change rate. The boost pressure in connection to gear shiftengagement is used as a basis for determining the available engine torquecorresponding to activation of limitation of engine torque provided by theexhaust gas smoke limiting function.

Fig. 4 schematically illustrates a system for determining an available enginetorque during a gear shift operation prior to performing the gear shiftoperation according to an embodiment of the present invention.

The system I comprises an electronic control unit 100.

The system is arranged to consider an exhaust gas smoke limiting function of a combustion engine control system of a vehicle.

The vehicle is driven by means of an internal combustion engine beingturbocharged by means of a turbo compressor configured to compress air in 16 to the cylinders of the engine. The vehicle comprises an automatic or semi-automatic transmission configured to provide automatic gear shift operationduring drive of the vehicle. The vehicle comprises a combustion enginecontrol system having an exhaust gas limiting function for limiting exhaustgas smoke during combustion by limiting the allowable amount of fuel to the cylinders when applicable.

The system I comprises means 160 for determining a development ofavailable engine torque from a certain level of available engine torque up toan engine torque corresponding to a demanded engine torque.

The means 160 for determining a development of available engine torque upto an engine torque corresponding to a demanded engine torque comprisesmeans 162 for estimating a linear function with a certain torque developmentincrease rate. The estimation of a linear function with a certain torquedevelopment increase rate is according to an embodiment provided bymeans of testbeds, i.e. calibration of the engine in which the time required toreach the demanded engine torque from the point of limitation is determined.The estimation of linear function with a certain torque development increaserate is according to an embodiment provided by means of modelling the torque development increase rate.

The means 160 for determining a development of available engine torquecomprises means 164 for estimating the maximum engine torque and theresponse time for the engine from motoring to the maximum engine torquefor a certain number of different engine rotational speeds. The estimation ofresponse time for the engine from motoring to the maximum engine torque isaccording to an embodiment obtained by calibration of the engine in atestbed.

The maximum engine torque at full load for the engine as a function of theengine rotational speed is estimated in the calibration. The maximum enginetorque thus determined is divided with the response time from motoring to the 17 maximum engine torque. The response time from motoring to maximumtorque is determined by means of a response time factor as a function of theengine rotational speed times the maximum engine torque as a function ofthe engine rotational speed divided by a torque factor as a function ofnumber of cylinders of the engine. The maximum torque as a function of theengine rotational speed is provided from the engine control system as atorque or as an amount of fuel. The response time factor as a function of theengine rotational speed is calculated in a function comprising the enginerotational speed. The torque factor as a function of number of cylinders of theengine is a function where the number of cylinders of the engine is included as a parameter.

The certain level of available engine torque corresponds according to anembodiment to activation of limitation of available engine torque provided byan exhaust gas smoke limiting function of a combustion engine controlsystem of the vehicle.

The system I comprises means 110 for determining the engine boostpressure. The means 110 for determining the engine boost pressurecomprises according to an embodiment one or more pressure detector units 112 for detecting the engine boost pressure.

The system I comprises means 190 for determining the engine boostpressure change rate. The means 190 for determining the engine boostpressure change rate comprises according to an embodiment one or morepressure detector units for detecting the engine boost pressure over a certainperiod of time. The one or more pressure detector units are according to anembodiment constituted by the one or more pressure detector units 112. Themeans 190 for determining the engine boost pressure change rate comprisesaccording to an embodiment means for processing the thus determinedboost pressure over a certain time so as to determining the boost pressurechange rate. The means for processing the thus determined boost pressure 18 is arranged to determine the engine boost pressure change rate based on a filtered mean value of determined engine boost pressures over time.The system I comprises means 120 for determining a boost pressure drop.

The means 120 for determining a boost pressure drop is arranged todetermine boost pressure drops for boost pressures above a certain levelarranged to determine boost pressure drops corresponding to the determinedengine boost pressure during a gear shift of the gear shift operation. This isfor normal driving situations where start situations as described below are excluded.

The means 120 for determining a boost pressure drop corresponding to thedetermined engine boost pressure during a gear shift of the gear shiftoperation comprises according to an embodiment data for boost pressuredrops during a gear shift operation for different boost pressures prior to agear shift operation. The data for boost pressure drops corresponding todifferent boost pressures prior to a gear shift operation are according to anembodiment boost pressure drops determined for different boost pressuresfor 1-step shifts, 2-step shifts, 3-step shifts or shift with more steps during agear shift operation. The means 120 comprises according to an embodimentdata according to the plot illustrated in fig. 3a.

The means 120 for determining a boost pressure drop is arranged todetermine boost pressure drops for boost pressures below the certain levelarranged to determine boost pressure drops corresponding to the determinedengine boost pressure change rate during a gear shift of the gear shiftoperation. This is for situations where the engine boost pressure prior to thegear shift operation is relatively low and increasing. Such an increasing lowlevel of boost pressure is below a certain level. Such a situation the forengine boost pressures below a certain level may typically be a vehiclestarting situation where the vehicle is accelerated from a standstill or close toa standstill by a demanded torque. 19 The means 120 for determining a boost pressure drop corresponding to thedetermined engine boost pressure change rate during a gear shift of the gearshift operation comprises according to an embodiment data for boostpressure drops during a gear shift operation for different boost pressureschange rates prior to a gear shift operation. The data for boost pressuredrops corresponding to different boost pressure change rates prior to a gearshift operation are according to an embodiment boost pressure dropsdetermined for different boost pressure change rates for up-shifts for lowgears, e.g. gears prior to gear shift operation being at 3 or lower, and for highgears, i.e. gears being at 4 or higher prior to gear shift operation _ The means120 comprises according to an embodiment data according to the p|oti||ustrated in fig. 3.

The means 120 is arranged to predict the boost pressure drop during a gearshift operation so as to determine the boost pressure in connection to gearshift engagement. This in accordance with the gear shift operation describedwith reference to fig. 2.

The means 120 is according to an embodiment arranged to determine theboost pressure in connection to gear shift engagement during the gear shiftoperation by subtracting the thus determined boost pressure drop from thedetermined boost pressure prior to the gear shift operation. According to analternative embodiment the electronic control unit 100 is arranged todetermine the boost pressure in connection to gear shift engagement duringthe gear shift operation by subtracting the thus determined boost pressuredrop from the determined boost pressure prior to the gear shift operation.The system thus comprises means for determining the boost pressure inconnection to gear shift engagement during the gear shift operation.

The means 120 comprises according to an embodiment a storage unitcomprising data for boost pressure drops during a gear shift operation fordifferent boost pressures prior to a gear shift operation. The storage unit isaccording to an embodiment an internal storage unit arranged on board the vehicle. The storage unit is according to an embodiment an external storage unit accessible for the vehicle.

The means 120 is according to an embodiment comprised in the electroniccontrol unit 100.

The system I comprises means 130 for determining an available enginetorque corresponding to activation of limitation of engine torque provided bysaid exhaust gas smoke limiting function based on a determined boostpressure drop during said gear shift operation.

The means 130 for determining an available engine torque corresponding toactivation of limitation of engine torque is arranged to determine the based ona determined boost pressure drop during said gear shift operation utilises thedetermined boost pressure in connection to gear shift engagementdetermined by means of the boost pressure drop.

The means 130 comprises means 132 for determining a lowest allowableair/fuel ratio for a certain number of different engine rotational speeds.

The means 132 for determining a lowest allowable air/fuel ratio for a certainnumber of different engine rotational speeds comprises according to anembodiment data for lowest allowable air/fuel ratios for different enginerotational speeds for different boost pressures. The thus determined boostpressure in connection to gear shift engagement is hereby used to determinelowest allowable air/fuel ratios for different engine rotational speeds. Theengine rotational speed is depending on the gear shift of the gear inconnection to the gear shift operation.

The means 132 comprises according to an embodiment a storage unitcomprising data for data for lowest allowable air/fuel ratios for differentengine rotational speeds for different boost pressures. The storage unit is according to an embodiment an internal storage unit arranged on board the 21 vehicle. The storage unit is according to an embodiment an external storage unit accessible for the vehicle.

The means 132 is according to an embodiment comprised in the electroniccontrol unit 100.

The means 130 for determining an available engine torque corresponding toactivation of limitation of engine torque provided by said exhaust gas smokelimiting function comprises means 134 for determining an allowable amount of fuel based on said determined lowest allowable air/fuel ratio.

The means 134 for determining an allowable amount of fuel based on saiddetermined lowest allowable air/fuel ratio comprises taking volumetricefficiency, i.e. fill rate in the cylinder. The volumetric efficiency is providedfrom a vector which has been calibrated in a testbed. The means 134 fordetermining an allowable amount of fuel based on said determined lowestallowable air/fuel ratio further comprises taking boost temperature. The boosttemperature is determined by means of one or more sensor units arranged inthe inlet manifold. The means 134 for determining an allowable amount offuel based on said determined lowest allowable air/fuel ratio is determinedwith regard to the determined boost pressure in connection to gear shiftengagement. The oxygen weight ratio is according to an embodiment alsotaken into account in determining the allowable amount of fuel. For selectivecatalytic reduction (SCR) systems the exhaust gas recirculation (EGR)content is taken into consideration with regard to the lowest allowable air/fuelratio. The stoichiometric air/fuel ratio, i.e. the theoretically necessaryrelationship between fuel and air amount for accomplishing completecombustion. The air, or rather oxygen, required for complete combustion may be determined if the chemical composition of the fuel is known.

The means 130 for determining an available engine torque corresponding toactivation of limitation of engine torque provided by said exhaust gas smokelimiting function is arranged to be performed based on the determined 22 allowable amount of fuel. The means 130 for determining an available enginetorque corresponding to activation of limitation of engine torque provided bysaid exhaust gas smoke limiting function comprises taking friction losses,cooling losses, pump losses and aggregate losses such as fan losses,compressor losses, generator losses.

The determined available engine torque corresponding to activation oflimitation of engine torque provided by said exhaust gas smoke limitingfunction constitutes a basis for said gear shift operation.

The system I comprises means 140 for determining the demanded enginetorque. The means 140 for determining the demanded engine torquecomprises according to an embodiment means for detecting the position ofthe gas pedal. The means 140 for determining the demanded engine torquecomprises according to an embodiment means for detecting speed limiter control, cruise control or other similar system.

The system I comprises means 150 for determining the atmosphericpressure. The means 150 for determining the atmospheric pressurecomprises an air pressure sensor. The means 150 for determining theatmospheric pressure comprises according to an embodiment a barometerunit. The means 150 for determining the atmospheric pressure comprisesaccording to an embodiment weather data received from an external unit, e.g. from a weather station.

The system I comprises means 170 for determining a suitable gear shift for agear shift operation.

The means 170 for determining a suitable gear shift for a gear shift operationcomprises means 172 for taking the determined available engine torquecorresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function as a basis. 23 The means 170 for determining a suitable gear shift for a gear shift operationcomprises means 174 for taking the determined development of availableengine torque as a basis.

The system I comprises means 180 for diagnosing the boost pressuresystem of the vehicle. The means 180 for diagnosing the boost pressuresystem of the vehicle comprises means for determining the actualdevelopment of available engine torque after the determined available enginetorque corresponding to activation of limitation of engine torque provided bysaid exhaust gas smoke limiting function up to an engine torquecorresponding to a demanded engine torque determined after the gear shiftoperation. The means 180 comprises means for comparing the actualdevelopment of available engine torque to the development of engine torquedetermined prior to the gear shift operation with the means 160. lf there is adifference such that the actual development of available engine torquereaches the demanded torque at a later stage than the assesseddevelopment of engine torque there may be a leakage in the boost pressure system of the vehicle.

The electronic control unit 100 is operably connected to means 160 fordetermining a development of available engine torque from a certain level ofavailable engine torque up to an engine torque corresponding to a demandedengine torque via a link 60a. The electronic control unit 100 is via the link 60aarranged to send a signal to the means 160 representing data for demandedengine torque and data for available engine torque corresponding the certain level.

The electronic control unit 100 is operably connected to the means 160 fordetermining a development of available engine torque from a certain level ofavailable engine torque up to an engine torque corresponding to a demandedengine torque via a link 60b. The electronic control unit 100 is via the link 60barranged to receive a signal from the means 160 representing data for 24 development of available engine torque after the determined available engine torque up to an engine torque corresponding to a demanded engine torque.

The electronic control unit 100 is operably connected to the means 162 forestimating a linear function with a certain torque development increase ratevia a link 62a. The electronic control unit 100 is via the link 62a arranged tosend a signal to the means 162 representing data for response time frommotoring to demanded engine torque and data for engine rotational speed.

The electronic control unit 100 is operably connected to the means 162 forestimating a linear function with a certain torque development increase ratevia a link 62b. The electronic control unit 100 is via the link 62b arranged tosend a signal to the means 162 representing data for linear function with a certain torque development increase rate.

The electronic control unit 100 is operably connected to the means 164 forestimating the maximum engine torque and the response time for the enginefrom motoring to the maximum engine torque for a certain number of differentengine rotational speeds via a link 64a. The electronic control unit 100 is viathe link 64a arranged to send a signal to the means 164 representing data for maximum engine torque and the response time for the engine.

The electronic control unit 100 is operably connected to the means 164 forestimating the maximum engine torque and the response time for the enginefrom motoring to the maximum engine torque for a certain number of differentengine rotational speeds via a link 64b. The electronic control unit 100 is viathe link 64b arranged to receive a signal from the means 164 representingdata for estimated torque development increase rate based on maximum engine torque and the response time for the engine.

The electronic control unit 100 is operably connected to the means 110 fordetermining the engine boost pressure via a link 10. The electronic controlunit 100 is via the link 10 arranged to receive a signal from the means 110 representing data for the engine boost pressure prior to a gear shift operation.

The electronic control unit 100 is operably connected to the pressure detectorunit 112 for detecting the engine boost pressure via a link 12. The electroniccontrol unit 100 is via the link 12 arranged to receive a signal from thepressure detector unit 112 representing data for the engine boost pressureprior to a gear shift operation.

The electronic control unit 100 is operably connected to the means 190 fordetermining the engine boost pressure change rate via a link 90a. Theelectronic control unit 100 is via the link 90a arranged to send a signal to themeans 190 representing data for the engine boost pressure prior to a gearshift operation.

The electronic control unit 100 is operably connected to the means 190 fordetermining the engine boost pressure change rate via a link 90b. Theelectronic control unit 100 is via the link 90b arranged to receive a signal fromthe means 190 representing data for boost pressure change rate prior to agear shift operation.

The electronic control unit 100 is operably connected to the means 120 fordetermining a boost pressure drop during a gear shift of the gear shiftoperation via a link 20a. The electronic control unit 100 is via the link 20aarranged to send a signal to the means 120 representing data for the engineboost pressure prior to a gear shift operation and/or data for engine boostpressure change rate.

The electronic control unit 100 is operably connected to the means 120 fordetermining a boost pressure drop during a gear shift of the gear shiftoperation via a link 20b. The electronic control unit 100 is via the link 20barranged to receive a signal from the means 120 representing data for boostpressure drop during a gear shift of the gear shift operation. According to anembodiment the electronic control unit 100 is via the link 20b arranged to 26 receive a signal from the means 120 representing data for boost pressure in connection to gear shift engagement.

The electronic control unit 100 is operably connected to the means 130 fordetermining an available engine torque corresponding to activation oflimitation of engine torque is arranged to determine the based on adetermined boost pressure drop during said gear shift operation via a link30a. The electronic control unit 100 is via the link 30a arranged to send asignal to the means 130 representing data for boost pressure in connection to gear shift engagement.

The electronic control unit 100 is operably connected to the means 130 fordetermining an available engine torque corresponding to activation oflimitation of engine torque is arranged to determine the based on adetermined boost pressure drop during said gear shift operation via a link30b. The electronic control unit 100 is via the link 30b arranged to receive asignal from the means 130 representing data for available engine torquecorresponding to activation of limitation of engine torque provided by saidexhaust gas smoke limiting function.

The electronic control unit 100 is operably connected to the means 132 fordetermining a lowest allowable air/fuel ratio for a certain number of differentengine rotational speeds via a link 32a. The electronic control unit 100 is viathe link 32a arranged to send a signal to the means 132 representing data for boost pressure in connection to gear shift engagement.

The electronic control unit 100 is operably connected to the means 132 fordetermining a lowest allowable air/fuel ratio for a certain number of differentengine rotational speeds via a link 32b. The electronic control unit 100 is viathe link 32b arranged to receive a signal from the means 132 representingdata for lowest allowable air/fuel ratio for a certain number of different engine rotational speeds. 27 The electronic control unit 100 is operably connected to the means 134 fordetermining an allowable amount of fuel via a link 34a. The electronic controlunit 100 is via the link 34a arranged to send a signal to the means 134representing data for lowest allowable air/fuel ratio for a certain number ofdifferent engine rotational speeds.

The electronic control unit 100 is operably connected to the means 134 fordetermining an allowable amount of fuel via a link 34b. The electronic controlunit 100 is via the link 34b arranged to receive a signal from the means 134representing data for an allowable amount of fuel.

The electronic control unit 100 is operably connected to the means 140 fordetermining the demanded engine torque via a link 40. The electronic controlunit 100 is via the link 40 arranged to receive a signal from the means 140representing data for demanded engine torque.

The electronic control unit 100 is operably connected to the means 150 fordetermining the atmospheric pressure via a link 50. The electronic controlunit 100 is via the link 50 arranged to receive a signal from the means 150representing data for atmospheric pressure.

The electronic control unit 100 is operably connected to the means 170 fordetermining a suitable gear shift for a gear shift operation via a link 70a. Theelectronic control unit 100 is via the link 70a arranged to send a signal to themeans 170 representing data for available engine torque and data for engine torque development.

The electronic control unit 100 is operably connected to the means 170 fordetermining a suitable gear shift for a gear shift operation via a link 70b. Theelectronic control unit 100 is via the link 70b arranged to receive a signal fromthe means 170 representing data for suitable gear shift for a gear shift operation. 28 The electronic control unit 100 is operably connected to the means 172 fortaking the determined available engine torque corresponding to activation oflimitation of engine torque provided by said exhaust gas smoke limitingfunction as a basis for gear shift via a link 72. The electronic control unit 100is via the link 72 arranged to send a signal to the means 172 representing data for available engine torque.

The electronic control unit 100 is operably connected to the means 174 fortaking the determined development of available engine torque as a basis forgear shift via a link 74. The electronic control unit 100 is via the link 74arranged to send a signal to the means 174 representing data for engine torque development.

The electronic control unit 100 is operably connected to the means 180 fordiagnosing the boost pressure system of the vehicle via a link 80a. Theelectronic control unit 100 is via the link 80a arranged to send a signal to themeans 180 representing data for actual engine torque development aftergear shift operation and data for determined engine torque development prior to the gear shift operation.

The electronic control unit 100 is operably connected to the means 180 fordiagnosing the boost pressure system of the vehicle via a link 80b. Theelectronic control unit 100 is via the link 80b arranged to receive a signal fromthe means 180 representing data for diagnose of the boost pressure system of the vehicle.

Fig. 5 schematically illustrates a block diagram of a method for determiningan available engine torque during a gear shift operation prior to performingsaid gear shift operation.

According to the embodiment the method for determining an available enginetorque during a gear shift operation prior to performing said gear shift operation comprises a step S1. ln this step a development of available 29 engine torque from a certain level of available engine torque up to an engine torque corresponding to a demanded engine torque is determined.

According to an embodiment of the method the step of determining adevelopment of available engine torque from a certain level of availableengine torque up to an engine torque corresponding to a demanded enginetorque comprises the step of determining an estimation of a linear functionwith a certain torque development increase rate. The estimation of a linearfunction with a certain torque development increase rate is according to anembodiment provided by means of testbeds, i.e. calibration of the engine inwhich the time required to reach the demanded engine torque from the pointof limitation is determined. The estimation of linear function with a certaintorque development increase rate is according to an embodiment provided by means of modelling the torque development increase rate.

According to an embodiment of the method the step of determining adevelopment of available engine torque from a certain level of availableengine torque up to an engine torque corresponding to a demanded enginetorque comprises the step of, for a certain number of different enginerotational speeds, estimating the maximum engine torque and the responsetime for the engine from motoring to the maximum engine torque. Theestimation of response time for the engine from motoring to the maximumengine torque is according to an embodiment obtained by calibration of the engine in a testbed.

According to an embodiment of the method said certain level corresponds toactivation of limitation of available engine torque provided by an exhaust gassmoke limiting function of a combustion engine control system of the vehicle.

According to an embodiment of the method the available engine torquecorresponding to activation of limitation of engine torque is determined basedon a determined boost pressure drop during said gear shift operation.

According to an embodiment the method comprises the step of taking saiddetermined development of available engine torque as a basis for said gearshift operation.

According to an embodiment the method comprises the step of taking saiddetermined development of available engine torque as a basis for diagnosingthe boost pressure system of the vehicle engine.

The method and the method steps described above with reference to fig. 5 isaccording to an embodiment performed with the system I according to fig. 4.

With reference to figure 6, a diagram of an apparatus 500 is shown. Thecontrol unit 100 described with reference to fig. 4 may according to anembodiment comprise apparatus 500. Apparatus 500 comprises a non-volatile memory 520, a data processing device 510 and a read/write memory550. Non-volatile memory 520 has a first memory portion 530 wherein acomputer program, such as an operating system, is stored for controlling thefunction of apparatus 500. Further, apparatus 500 comprises a bus controller,a serial communication port, I/O-means, an A/D-converter, a time date entryand transmission unit, an event counter and an interrupt controller (not shown). Non-volatile memory 520 also has a second memory portion 540.

A computer program P is provided comprising routines for determining anavailable engine torque during a gear shift operation prior to performing saidgear shift operation. The program P comprises routines for determining adevelopment of available engine torque from a certain level of availableengine torque up to an engine torque corresponding to a demanded enginetorque. The computer program P may be stored in an executable manner orin a compressed condition in a separate memory 560 and/or in read/writememory 550.

When it is stated that data processing device 510 performs a certain functionit should be understood that data processing device 510 performs a certain 31 part of the program which is stored in separate memory 560, or a certain part of the program which is stored in read/write memory 550.

Data processing device 510 may communicate with a data communicationsport 599 by means of a data bus 515. Non-volatile memory 520 is adaptedfor communication with data processing device 510 via a data bus 512.Separate memory 560 is adapted for communication with data processingdevice 510 via a data bus 511. Read/write memory 550 is adapted forcommunication with data processing device 510 via a data bus 514. To thedata communications port 599 e.g. the links connected to the control units 100 may be connected.

When data is received on data port 599 it is temporarily stored in secondmemory portion 540. When the received input data has been temporarilystored, data processing device 510 is set up to perform execution of code ina manner described above. The signals received on data port 599 can beused by apparatus 500 for determining a development of available enginetorque from a certain level of available engine torque up to an engine torque corresponding to a demanded engine torque.

Parts of the methods described herein can be performed by apparatus 500by means of data processing device 510 running the program stored inseparate memory 560 or read/write memory 550. When apparatus 500 runsthe program, parts of the methods described herein are executed.

The foregoing description of the preferred embodiments of the presentinvention has been provided for the purposes of illustration and description. ltis not intended to be exhaustive or to limit the invention to the precise formsdisclosed. Obviously, many modifications and variations will be apparent topractitioners skilled in the art. The embodiments were chosen and describedin order to best explain the principles of the invention and its practicalapplications, thereby enabling others skilled in the art to understand the 32 invention for various embodiments and with the various modifications as are suited to the particular use contemplated.

Claims

33 CLAIIVIS

1. A method for determining an available engine torque of a vehicle (1) duringa gear shift operation (A, B, C, D) prior to performing said gear shift operation, step of: - determining (S1) a development (D, D1) of available engine torque from acertain level of available engine torque (P1, P2) up to an engine torque (P3,P3a) corresponding to a demanded engine torque, characterized bv that: wherein-said certain level corresponds to activation of limitation of availableengine torque (P2) provided by an exhaust gas smoke limiting function of acombustion engine control system of the vehicle, and wherein-thiattheavailable engine torque corresponding to activation of limitation of enginetorque is determined based on a determined boost pressure drop during said gear shift operation.

2. A method according to claim 1, wherein the step of determining adevelopment of available engine torque from a certain level of available enginetorque up to an engine torque corresponding to a demanded engine torquecomprises the step of determining an estimation of a linear function with a certain torque development increase rate.

3. A method according to claim 1 or 2, wherein the step of determining adevelopment of available engine torque from a certain level of available enginetorque up to an engine torque corresponding to a demanded engine torquecomprises the step of, for a certain number of different engine rotationalspeeds, estimating the maximum engine torque and the response time for the engine from motoring to the maximum engine torque.

4. A method according to any of claims 1-3, comprising the step of taking saiddetermined development (D) of available engine torque as a basis for said gear shift operation.

5. A method according to any of claims 1-4, comprising the step of taking saiddetermined development (D, D1) of available engine torque as a basis fordiagnosing the boost pressure system of the vehicle engine.

6. A system (l) for determining an available engine torque of a vehicle (1)during a gear shift operation (A, B, C, D) prior to performing said gear shiftoperation, comprising means (160) for determining adevelopment (D, D1) of available engine torque from a certain level of availableengine torque (P1, P2) up to an engine torque (P3, P3a) corresponding to ademanded engine torque, wherein-characterized bv that said certain levelcorresponds to activation of limitation of available engine torque (P2) providedby an exhaust gas smoke limiting function of a combustion engine controlsystem of the vehicle, and that the system (l) comprises means(130) for determining the available engine torque (P2) corresponding toactivation of limitation of engine torque based on a determined boost pressuredrop during said gear shift operation.

7. A system according to claim 6, wherein the means (160) for determining adevelopment of available engine torque from a certain level of available enginetorque up to an engine torque corresponding to a demanded engine torquecomprises means (162) for determining an estimation of a linear function with a certain torque development increase rate.

8. A system according to claim 6 or 7, wherein the means (160) fordetermining a development of available engine torque from a certain level ofavailable engine torque up to an engine torque corresponding to a demandedengine torque comprises means (164) for estimating the maximum enginetorque and the response time for the engine from motoring to the maximum engine torque for a certain number of different engine rotational speeds.

9. A system according to any of claims 6-8, comprising means (1 74) for takingsaid determined development (D) of available engine torque as a basis for said gear shift operation.

10. A system according to any of claims 6-9, comprising means (1 80) for takingsaid determined development (D, D1) of available engine torque as a basis for diagnosing the boost pressure system of the vehicle engine.

11. A vehicle (1) comprising a system (l) according to any of claims 6-10.

12. A computer program (P) for determining an available engine torque of avehicle during a gear shift operation prior to performing said gear shiftoperation, said computer program (P) comprising program code which, whenrun on an electronic control unit (100) or another computer (500) connected tothe electronic control unit (100), causes the electronic control unit to perform the steps according to claim 1-5.

13. A computer program product comprising a digital storage medium storing the computer program according to claim 12.