SE1650875A1

SE1650875A1 - Method and system for controlling torque reduction of a gearshift operation

Info

Publication number: SE1650875A1
Application number: SE1650875A
Authority: SE
Inventors: Forslund Christer
Original assignee: Scania Cv Ab
Priority date: 2016-06-21
Filing date: 2016-06-21
Publication date: 2017-12-22
Also published as: SE541342C2; BR102017012743A2; DE102017005412A1

Abstract

The present invention relates to a method for controlling torque reduction of a gear shift operation of a vehicle having a turbocharged internal combustion engine. The method comprises the steps of: prior to performing said torque reduction, determining (S1) current conditions comprising torque and engine speed and/or pressure ratio over and air mass flow through the turbo compressor of the engine; choosing (S2) a certain torque reduction rate prior to said gear shift operation; performing (S3) said torque reduction at said chosen rate; determining (S4) a possible appearance of a surge event; and adapting (S5) the torque reduction rate based upon the result of the determination of said possible appearance of a surge event in order to obtain a high torque reduction rate and at the same time avoid said surge event under said determined current conditions for a following gear shift operation.The present invention also relates to a system for controlling torque reduction of a gear shift operation of a vehicle having a turbocharged internal combustion engine. The present invention also relates to a vehicle. The present invention also relates to a computer program and a computer program product.

Description

|\/IETHOD AND SYSTEM FOR CONTROLLING TOROUE REDUCTION OFA GEAR SHIFT OPERATION TECHNICAL FIELD The invention relates to a method for controlling torque reduction of a gearshift operation of a vehicle having a turbocharged internal combustion engineaccording to the preamble of claim 1. The invention also relates to a systemfor controlling torque reduction of a gear shift operation of a vehicle having aturbocharged internal combustion engine. The invention also relates to avehicle. The invention in addition relates to a computer program and a computer program product.

BACKG ROUND ART For vehicles having a turbocharged internal combustion engine torquereduction of a gear shift operation with a high torque reduction rate mayresult in so called surge noise, i.e. a backflow of pressurised air through theturbo compressor. This is due to the fact that the turbo compressor is unableto maintain the pressure that is accumulated in the charge air cooler during the relatively quick reduction of exhaust gas energy content.

By installing a bypass valve for bypassing such pressurised air passed theturbo compressor this problem may be avoided. However, this requireschange of hardware in the turbocharged internal combustion engine by installation of additional component adding costs.

There is thus a need for improving control of torque reduction of a gear shiftoperation of a vehicle having a turbocharged internal combustion engine.

OBJECTS OF THE INVENTION An object of the present invention is to provide a method for controllingtorque reduction of a gear shift operation of a vehicle having a turbochargedinternal combustion engine which easily and efficiently facilitates optimizationof the speed of the gear shift performance with reduced risk of surge noise.

An object of the present invention is to provide a system for controlling torquereduction of a gear shift operation of a vehicle having a turbocharged internalcombustion engine which easily and efficiently facilitates optimization of thespeed of the gear shift performance with reduced risk of surge noise.

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 for controllingtorque reduction of a gear shift operation of a vehicle having a turbochargedinternal combustion engine. The method comprises the steps of: prior toperforming said torque reduction, determining current conditions comprisingtorque and engine speed and/or pressure ratio over and air mass flowthrough the turbo compressor of the engine; choosing a certain torquereduction rate prior to said gear shift operation; performing said torquereduction at said chosen rate; determining a possible appearance of a surgeevent; and adapting the torque reduction rate based upon the result of thedetermination of said possible appearance of a surge event in order to obtaina high torque reduction rate and at the same time avoid said surge eventunder said determined current conditions for a following gear shift operation.

Hereby the gear shift performance may be optimized with respect to speed atthe same time as the risk of a surge event causing undesired noise isreduced, this being facilitated in an easy and efficient way not requiring anychange of hardware or a complex model requiring a lot of calibrations. Thegear shift performance with respect to speed and avoidance of surge noisewill improve in following gear shift operations as it will learn from previousresults and may adapt accordingly. Certain changes in the engine during thelife time of the engine with respect to ageing will be considered by performingsaid adaption of torque reduction. The possible required adaption will bespecific and hence accurate for the particular engine/engine type and will also take changes of the respective engine into consideration.

By thus optimizing the speed of the gear shift the comfort for the operator ofthe vehicle is optimized in that the speed of the gear shift operation isincreased at the same time as surge noise may be avoided to a great extent.Further, by thus facilitating faster gear shift operations and avoiding surgenoise, more efficient drive of the vehicle is facilitated. By thus optimising thetorque reduction rate, i.e. facilitating a faster torque reduction during a gearshift operation with low risk of surge noise, the level at which activation oflimitation of engine torque increase rate provided by an exhaust gas smokelimiting function based on a determined boost pressure in connection to gearshift engagement may be increased, thus facilitating further increasing thespeed of the gear shift operation. This is due to the fact that the boostpressure will drop more for an off-ramp of a gear shift operation with arelatively slower torque reduction than for an off-ramp with a relatively fastertorque reduction rate.

By using current conditions comprising torque and engine speed determinedprior to performing a torque reduction and the certain chosen torquereduction for that gear shift operation as a basis for a following gear shiftoperation under essentially the same conditions with regard to torque andengine speed when adapting the torque reduction rate based upon the result of the determination of said possible appearance of a surge event in thatprevious gear shift operation, the basis for adaption is obtained in an easyway as torque and engine speed is easy to determine in that suchinformation is easy to communicate between transmission and engine.Further this provides a more general basis and is not dependent on thespecific engine of the vehicle but may advantageously be used as information for other similar engines under such conditions.

By using current conditions comprising pressure ratio over the turbocompressor and air mass flow through the turbo compressor of the enginedetermined prior to performing a torque reduction and the certain chosentorque reduction for that gear shift operation as a basis for a following gearshift operation under essentially the same conditions with regard to pressureratio over the turbo compressor and air mass flow through the turbocompressor when adapting the torque reduction rate based upon the result ofthe determination of said possible appearance of a surge event in thatprevious gear shift operation the basis for adaption obtained is accurate forthat particular engine and may advantageously be used as information for theengines of the vehicle under such conditions. By using pressure ratio overthe turbo compressor no compensation due to ambient pressure is required,i.e. if the current condition regarding ambient pressure differs from thecondition regarding ambient pressure in the previous gear shift operationwhich is used as a basis, the use of pressure ratio will take this into account.

Current conditions regarding torque and engine speed may be determinedalone prior to such a torque reduction of a gear shift operation. Currentconditions regarding pressure ratio over the turbo compressor and air massflow through the turbo compressor of the engine may be determined aloneprior to such a torque reduction of a gear shift operation. Current conditionsregarding torque and engine speed and pressure ratio over the turbocompressor and air mass flow through the turbo compressor of the enginemay all be used prior to such a torque reduction of a gear shift operation. By using both torque and engine speed and pressure ratio over the turboCompressor and air mass flow through the turbo compressor of the engineredundancy is obtained.

According to an embodiment the current conditions determined prior toperforming said torque reduction further comprises engine speed changerate, i.e. whether the engine speed is changing prior to and in connection tosaid torque reduction of the gear shift operation. Thus, according to anembodiment the method comprises the step of, prior to performing saidtorque reduction, determining possible engine speed change rate, i.e.possible engine speed increase rate or engine speed decrease rate.Changes in engine speed prior to a gear shift operation may have influenceon the torque reduction rate in connection to the gear shift operation and maybe relevant information for a following gear shift operation.

According to an embodiment the current conditions determined prior toperforming said torque reduction further comprises the current ambient airpressure. Thus, according to an embodiment the method comprises the stepof, prior to performing said torque reduction, determining current ambient air pressure.

According to an embodiment of the method, for a following gear shiftoperation under said determined current conditions, the step of adapting thetorque reduction rate comprises the step of increasing the torque reductionrate if no surge event has appeared, and decreasing the torque reductionrate if a surge event has appeared. Hereby the optimization of the gear shiftperformance is further improved with respect to speed of the gear shiftoperation at the same time as the risk of a surge event causing undesirednoise is reduced.

According to an embodiment of the method the step of determining apossible appearance of a surge event comprises the step of detecting air pressure conditions related to the compressor of the turbocharged arrangement of said engine so as to decide the seriousness of determinedsurge events. By thus determining the seriousness of a possible surge eventa more accurate adaption in torque reduction rate for a following gear shiftoperation may be provided, thus further improving optimization of the gearshift performance.

According to an embodiment of the method the step of decreasing the torquereduction rate if a surge event has appeared is based upon the seriousnessof said determined surge event. Hereby the optimization of the gear shiftperformance is further improved with respect to speed of the gear shiftoperation at the same time as the risk of a surge event causing undesired noise is reduced.

According to an embodiment the method comprises the step of storingcurrent conditions comprising torque and engine speed and/or pressure ratioover and air mass flow through the turbo compressor of the enginedetermined prior to performing torque reduction for different gear shiftoperations, and the resulting adaption for avoiding surge events as a basisfor choosing certain torque reduction rate. Hereby the required adaption ofthe torque reduction rate for the current condition of the forthcoming gearshift operation has been stored and is avaiiable/retrievable for that gear shiftoperation such that the adaptation of the torque reduction rate will beoptimized for the current condition. Thus, hereby the optimization of the gearshift performance is further improved with respect to speed of the gear shiftoperation at the same time as the risk of a surge event causing undesirednoise is reduced. The thus stored required adaption of the torque reductionrate for a current condition of a forthcoming gear shift operation may bestored externally and be made available for an upcoming gear shift operationfor another vehicle such that the adaption of the torque reduction rate will beoptimized for the current condition in connection to the gear shift operationfor that other vehicle.

Specifically an object of the invention is achieved by a system for controllingtorque reduction of a gear shift operation of a vehicle having a turbochargedinternal combustion engine. The system comprises means for, prior toperforming said torque reduction, determining current conditions comprisingmeans for determining torque and means for determining engine speedand/or means for determining pressure ratio over the turbo compressor andmeans for determining air mass flow through the turbo compressor; meansfor choosing a certain torque reduction rate prior to said gear shift operation;means for performing said torque reduction at said chosen rate; means fordetermining a possible appearance of a surge event; and means for adaptingthe torque reduction rate based upon the result of the determination of saidpossible appearance of a surge event in order to obtain a high torquereduction rate and at the same time avoid said surge event under saiddetermined current conditions for a following gear shift operation.

According to an embodiment of the system, for a following gear shiftoperation under said determined current conditions, the means for adaptingthe torque reduction rate comprises means for increasing the torquereduction rate if no surge event has appeared, and means for decreasing the torque reduction rate if a surge event has appeared.

According to an embodiment of the system the means for determining apossible appearance of a surge event comprises means for detecting airpressure conditions related to the compressor of the turbochargedarrangement of said engine so as to decide the seriousness of determined SUFQG GVGHÉS.

According to an embodiment of the system the means for decreasing thetorque reduction rate if a surge event has appeared is based upon the seriousness of said determined surge event.

According to an embodiment the system comprises means for storing currentconditions comprising torque and engine speed and/or pressure ratio over and air mass flow through the turbo Compressor of the engine determinedprior to performing torque reduction for different gear shift operations, and theresu|ting adaption for avoiding surge events as a basis for choosing certaintorque reduction rate.

The system for contro||ing torque reduction of a gear shift operation of avehicle having a turbocharged internal combustion engine is adapted toperform the method as set out herein.

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 a system according to the invention as set out herein.

Specifically an object of the invention is achieved by a computer program forcontro||ing torque reduction of a gear shift operation of a vehicle having aturbocharged internal combustion engine, said computer program comprisingprogram code which, when run on an electronic control unit or anothercomputer connected to the electronic control unit, causes the electroniccontrol 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 the gas flow through a turbocharged internal combustion engine according to an embodiment of the present invention; Fig. 2 schematically illustrates the pressure ratio over the turbo compressoras a function of compressor air mass flow for different engine speeds and loads; Fig. 3a schematically illustrates a torque development course during a gearshift operation; Fig. 3b schematically illustrates an engine speed development course duringa gear shift operation corresponding to the gear shift operation in fig. 3a; Fig. 4 schematically illustrates a system for controlling torque reduction of agear shift operation of a vehicle having a turbocharged internal combustion engine according to an embodiment of the present invention; Fig. 5 schematically illustrates a side view of a vehicle according to the present invention; Fig. 6 schematically illustrates a block diagram of a method for controllingtorque reduction of a gear shift operation of a vehicle having a turbochargedinternal combustion engine according to an embodiment of the present invention; and Fig. 7 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 “means for” e.g. in relation to “means for determiningcurrent conditions”, “means for choosing a certain torque reduction rate”,“means for performing said torque reduction at said chosen rate”, “means fordetermining a possible appearance of a surge event” and “means foradapting the torque reduction rate based upon the result of the determinationof said possible appearance of a surge event in order to obtain a high torquereduction rate and at the same time avoid said surge event under saiddetermined current conditions for a following gear shift operation” comprises“means adapted for”.

The engine according to the present invention could be any suitableturbocharged internal combustion engine with any suitable number ofcylinders. The internal combustion engine according to the present inventioncould for example be a 5-cylinder engine, a 6-cylinder engine or an 8-cylinderengine. The cylinders could be in any suitable alignment, for example inlineengine or a V-engine. ln fig. 2 an embodiment for a turbocharged internalcombustion engine with six cylinders is described. The internal combustionengine according to the present invention could be any turbocharged internal combustion engine.

Fig. 1 schematically illustrates the gas flow through a turbocharged internalcombustion engine 10 i.e. a turbocharged diesel engine 10.

The components relevant for the gas flow during engine operation aredenoted as the engine operation configuration E. The engine operation configuration E comprises the engine 10. ln this example an engine 10 with six cylinders G1, G2, G3, G4, G5, G6 isshown. The engine 10 comprises an engine block 12 for housing thecylinders and other engine operation components.

The engine operation configuration E further comprises an air filter 20through which ambient air A1 is arranged to pass so that filtered air A2 isobtained. 11 The engine operation configuration E comprises a turbocharger 30 having aturbo Compressor 32, a turbine 34 and a shaft 36 operably connecting theturbo compressor 32 and turbine 36. The turbo compressor 32 is arranged tocompress the filtered air A2 so that compressed air A3 is obtained.

The engine operation configuration E comprises an intercooler 40 for cooling the compressed air A3 such that coo|ed compressed air A4 is obtained.

The turbo charger 30 comprising the turbo compressor 32, the intercooler 40and/or the throttle valve are comprised in the turbocharged arrangement ofthe engine/engine operation configuration E.

The engine operation configuration E comprises an intake manifold 50 for distributing the air, i.e. the compressed air A4 to the cylinders C1-C6.

The engine operation configuration E comprises a throttle valve V1 arrangedto control the distribution of air A4 to the cylinders C1-C6.

The engine operation configuration E comprises an exhaust manifold 60 fordistributing exhaust gas G1 from the cylinders C1-C6 to the turbine 34, theexhaust gas being arranged to pass the turbine 34 for operating theturbocharger 30 such that the turbo compressor 32 compresses the filteredair A2.

The exhaust manifold 60 comprises a waste gate 62 for allowing exhaust gasto bypass the turbine 34 and further to the exhaust pipe 64. The engineoperation configuration E comprises a valve V2 arranged to control thedistribution of exhaust gas through the waste gate 62.

The engine operation configuration E comprises an exhaust gas brake V3arranged downstream of the turbine and downstream of the waste gate.When activated, the exhaust gas brake V3 is configured to provide anexhaust back pressure by rendering exhaust gas flow through the exhaust pipe 64 more difficult. The exhaust back pressure is used for braking the 12 engine. The exhaust gas brake V3 comprises a valve configuration for controlling the exhaust gas flow through the exhaust pipe 64.

The engine operation configuration E comprises an exhaust treatmentsystem 70 arranged to treat the exhaust gas in order to reduce emissions sothat treated exhaust gases G2 exits the exhaust gas pipe 64.

Fig. 1 thus i||ustrates the gas flow through the turbocharged internalcombustion engine and hence the gas flow through the engine operationconfiguration E. Ambient air A1 enters through the air filter 20, is compressedin the turbo compressor 32 and led through the intercooler 40 to the intakemanifold 50 before entering the cylinders 1-6. Fuel F is added by injectioninto the cylinders and after combustion, the exhaust gas G1 pass through theturbine 34 to the exhaust treatment system 70. ln fig. 1 the gas flow through a turbocharged diesel engine 10 is shown,where the engine operation configuration E comprises a turbocharger 30 witha turbo compressor 32 and turbine 34, where exhaust gas is arranged topass the turbine 34 for operating the turbocharger 30 such that the turbocompressor 32 compresses the filtered air A2, the turbo compressor 32 thusbeing driven by the turbine 34.

A backflow of pressurised air through the turbo compressor 32 may occur.This is due to the fact that the turbo compressor 32 is unable to maintain thepressure that is accumulated in the intercooler 40 during a relatively quicktorque reduction.

The root cause for surge in connection to torque reduction in a gear shiftoperation is due to the fact that the turbo compressor 32 is unable tomaintain the pressure that is accumulated in the intercooler 40 during therelatively quick reduction of exhaust gas energy content. The rapid drop inexhaust gas energy content follows the rapid reduction of engine torque, i.e.high torque reduction rate, necessary to be able to disengage current gear. 13 The engine torque is directly connected to the injected amount of fuel, andthe injected fuel generates exhaust gas energy. ln the off-ramp phase of thegear shift operation of the transmission when ramping down the torque, i.e.reducing the torque with a certain torque reduction rate, the turbine power will decrease simultaneously.

The decreased turbine power equals less power to drive the turbocompressor 32 resulting in a decreased speed turbine speed.

Since the intercooler 40 for certain vehicles constitutes a relatively largevolume of pressurized air that needs to be consumed or evacuated in someway the evacuation of pressurized air A5 backwards through the turbocompressor 32 is what happens during a surge event causing undesired noise. l\/leans 82, 84, 90 for determining a possible appearance of a surge event areprovided.

Such a possible appearance of a surge event may be determined by meansof detecting changes in the boost pressure, i.e. changes of the air pressure.Detection of rapid changes of the pressure indicates a surge event. Theseriousness of the surge event may also be determined by thus determiningthe changes in pressure and also the magnitude of the changes and thenumber of changes so as to rate the surge event. The means 82, 84, 90 fordetermining a possible appearance of a surge event comprises herepressure sensor units 82, 84 comprising a pressure sensor unit 82 arrangedprior to the compressor 32, i.e. upstream of the compressor during normal airflow, and a pressure sensor unit 84 arranged after the compressor 32, i.e.downstream of the compressor 32 during normal air flow. The pressuresensor units 82, 84 may be comprised in or comprise the means 142 fordetecting air pressure conditions related to the compressor described withreference to the system l in fig. 4. 14 Such a possible appearance of a surge event may be determined by meansof detecting the air mass flow, wherein an air mass flow backwards throughthe turbo compressor indicates a surge event. The means 82, 84, 90 fordetermining a possible appearance of a surge event comprises here a flowsensor unit 90 for detecting air flow. The flow sensor unit 90 may becomprised in or comprise the means 144 for determining air flow related to the compressor described with reference to the system l in fig. 4. ln order to optimize the gear shift performance when controlling torquereduction of a gear shift operation of a vehicle having a turbocharged internalcombustion engine current conditions comprising according to anembodiment pressure ratio over and air mass flow through the turbocompressor 32 are determined prior to performing a torque reduction in an off-ramp phase of the gear shift operation. l\/leans 82, 84 for determining the pressure ratio over the compressor 32 ofthe turbocharged arrangement of said engine are hereby provided. ln thisexample the means 82, 84 for determining the pressure ration over thecompressor 32 comprises the pressure sensor means 82 and pressuresensor means 84. The pressure ratio is determined by means of dividing thepressure after the compressor 32 determined by the means 84 with thepressure before the compressor 32 determined by the means 82. The means82, 84 for determining the pressure ratio over the compressor 32 may becomprised in or comprise the means 113 described with reference to thesystem I in fig. 4. l\/leans 90 for determining the air mass flow through the turbo compressor arehereby provided. ln this example the means flow for determining the air massflow through the turbo compressor comprises the flow sensor unit 90. Theflow sensor unit 90 may be comprised in or comprise the means 114 fordetermining the air mass flow through the turbo compressor described withreference to the system l in fig. 4.

Fig. 2 schematically illustrates the pressure ration over the turbo Compressoras a function of Compressor air mass flow for different engine speeds andloads.

For a turbocharged internal combustion engine with no bypass valve forbypassing pressurised air passed the turbo compressor and where thustorque reduction of a gear shift operation with a high torque reduction ratemay result in surge events. For such an engine the engine speed and relativeload, i.e. relative torque, have strong correlation to the compressor mass flow and pressure ratio.

At a given engine speed, a specific boost pressure relates to the air mass flow by the volumetric efficiency of the engine (neglecting boosttemperature). During normal ambient conditions at sea-level the steady-statecorrelation of the engine speed and relative load to the pressure ratio andmass flow can be illustrated in accordance with fig. 2, which thus illustrates a map of the turbo compressor.

This relation makes the engine speed and relative torque suitable fordescribing the area of interest in the compressor map During load transients when the boost pressure is changing rapidly, the massflow through the turbo compressor differs from the mass flow through the engine.

Fig. 3a schematically illustrates a torque development course during a gearshift operation of a vehicle having a turbocharged internal combustion engineand fig. 3b schematically illustrates an engine speed development courseduring such a gear shift operation. The gear shift operation in fig. 3a is an up-shift operation, i.e. shift from a lower gear to a higher gear. ln an up-shiftoperation there is a decrease in engine rotational speed as illustrated in fig.3b. The up-shift operation is an example. The invention is equally applicableto a down-shift operation. The invention is further applicable to any engine speed. 16 The gear shift operation comprises an off-ramp phase A in which the torque Tq is reduced from a torque T1 to substantially zero as seen in fig. 3a.

The torque Tq in the off-ramp phase A in fig. 3a is reduced with a torquereduction rate TA1 having a certain inclination d.

According to the present invention the torque reduction of the vehicle havinga turbocharged internal combustion engine is controlled in order to optimizethe gear shift performance with respect to the duration of the gear shiftoperation without reaching a torque reduction rate in the off-ramp phase causing surge noises. ln order to thus optimize the gear shift performance current conditionscomprising according to an embodiment torque and engine speed aredetermined prior to performing said torque reduction. The torque and enginespeed determined prior to performing said torque reduction are in thisexample determined immediately prior to off-ramp phase A at a point PO witha determined torque T1 and an engine speed N1. Alternatively or in additionthe pressure ratio over and air mass flow through the turbo compressor maybe determined prior to performing said torque reduction.

A certain torque reduction rate TA1 is chosen prior to the gear shift operation.

The torque reduction in the off-ramp A is performed at said chosen rate TA1.

A possible appearance of a surge event due to the torque reduction rate TA1of the off-ramp phase A is then determined. Determination of such a possibleappearance of a surge event comprises detecting air pressure conditionsrelated to the compressor of the turbocharged arrangement of theturbocharged internal combustion engine so as to decide the seriousness of determined surge events.

The torque reduction rate is adapted to the result of the determination of said possible appearance of a surge event in order to obtain a high torque 17 reduction rate and at the same time avoid said surge event under saiddetermined current conditions for a following gear shift operation. lf no surge event has appeared with the torque reduction rate TA1 during theoff-ramp phase A the torque reduction rate is adapted in a following gear shiftoperation to a higher torque reduction rate TA2. lf no surge event hasappeared with the torque reduction rate TA2 during the off-ramp phase ofthat gear shift operation the torque reduction rate is adapted in a followinggear shift operation to an even higher torque reduction rate TA3. lf a surge event has appeared has appeared with the torque reduction rateTA1 during the off-ramp phase A the torque reduction rate is adapted in afollowing gear shift operation to a lower torque reduction rate TA4. lf a surgeevent has appeared with the torque reduction rate TA4 during the off-rampphase of that gear shift operation the torque reduction rate is adapted in a following gear shift operation to an even lower torque reduction rate TA5. lf a surge event has appeared has appeared with the torque reduction rateTA1 during the off-ramp phase A the torque reduction rate is adapted in afollowing gear shift operation to a lower torque reduction rate where thedecrease of the torque rate is based upon the seriousness of the determinedsurge event, i.e. a more serious surge event comprising repeated surgenoises results in a greater decrease of the torque rate, e.g. a torque rateTA5, and a less serious surge event results in decrease of the torque ratethat is not as great as the one for a serious surge event, e.g. a torque rateTA4.

Current conditions comprising torque and engine speed determined prior toperforming torque reduction for different gear shift operations and theresulting adaption for avoiding surge events as a basis for choosing certaintorque reduction rate are stored in suitable storage means. Hereby therequired adaption of the torque reduction rate for the current condition of athe forthcoming gear shift operation may be stored and made available for 18 that gear shift operation such that the adaptation of the adaption of the torque reduction rate will be optimized for the current condition.

As the engine speed has reached its gear shift speed N1 the off-ramp phaseA starts and then engine speed decreases.

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.

During the synchronisation phase B the engine speed is decreased down tothe target speed N2.

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 according to the example in fig. 3a thus comprises asmoke limiting development phase D of the available torque up to an engine torque corresponding to a demanded torque reached in the point P3.

During the smoke limiting development phase D the engine speed isincreasing up to an engine speed being lower than the gear shift speed N1,this being an up-shift operation.

By thus optimising the torque reduction rate, i.e. facilitating a faster torquereduction during a gear shift operation with low risk of surge noise, the level 19 at which activation of Iimitation of engine torque increase rate provided by anexhaust gas smoke Iimiting function based on a determined boost pressure inconnection to gear shift engagement may be increased, thus facilitatingfurther increasing the speed of the gear shift operation.

Fig. 4 schematically i||ustrates a system I for contro||ing torque reduction of agear shift operation of a vehicle having a turbocharged internal combustion engine according to an embodiment of the present invention.

The system I comprises an electronic control unit 100. The electronic controlunit 100 may comprises one or more electronic control units comprising e.g.electronic control unit for engine and electronic control unit fortransmission/gear box, where electronic control units of the electronic control unit 100 are arranged to communicate.

The system I comprises means 110 for determining current conditionscomprising torque and engine speed and/or pressure ratio over and air massflow through the turbo compressor of the engine prior to performing saidtorque reduction.

The means 110 for determining current conditions prior to performing saidtorque reduction comprises means 111 for determining the engine torqueprior to performing said torque reduction. The means for determining enginetorque comprises according to an embodiment means for detecting theposition of the gas pedal. The means 110 for determining the engine torquecomprises according to an embodiment means for detecting speed limiter control, cruise control or other similar system.

The means 110 for determining current conditions prior to performing saidtorque reduction comprises means 112 for determining engine speed prior toperforming said torque reduction. The means 112 for determining engine speed may comprise any suitable detector unit for detecting engine speed.

The means 110 for determining current conditions prior to performing saidtorque reduction comprises means 113 for determining the pressure ratioover the compressor of the turbocharged arrangement of said engine. Themeans 113 for determining the pressure ratio over the compressor of theturbocharged arrangement of said engine comprises means for determiningthe pressure prior to the compressor and means for determining the pressureafter the compressor. The means 113 for determining the pressure ratio overthe compressor of the turbocharged arrangement of said engine may comprise any suitable pressure sensor unit.

The means 110 for determining current conditions prior to performing saidtorque reduction comprises means 114 for determining the air mass flowthrough the turbo compressor. The means 114 for determining the air massflow through the turbo compressor may comprises any suitable flow sensor unit.

The means 110 for determining current conditions prior to performing saidtorque reduction comprises means 115 for determining ambient pressure.The means 115 for determining ambient pressure may comprise any suitable DFGSSUFG SGFISOI' Unit.

The means 110 for determining current conditions prior to performing saidtorque reduction comprises means 116 for determining possible changes inengine speed, i.e. the engine speed change rate. The means 116 fordetermining possible changes in engine speed may comprises any suitable speed sensor unit.

The system I comprises means 120 for choosing a certain torque reductionrate prior to said gear shift operation.

The means 120 for choosing a certain torque reduction rate prior to said gearshift operation may be based on earlier performed torque reduction for similar current conditions. 21 The system I comprises means 130 for performing said torque reduction at said chosen rate.

The means 130 for performing said torque reduction at said chosen ratecomprises a torque reduction demand for reducing the torque at said torquereduction rate. The means 130 for performing said torque reduction at saidchosen rate is comprised in the gear shift operation and thus comprises agear shift demand for performing a gear shift operation.

The system I comprises means 140 for determining a possible appearance of 8. SUFQG GVGHÉ.

The means 140 for determining a possible appearance of a surge eventcomprises means 142 for detecting air pressure conditions related to thecompressor of the turbocharged arrangement of said engine. The means 142for detecting air pressure conditions related to the compressor of theturbocharged arrangement of said engine comprises detecting comprisesdetermining changes in the pressure. The means 142 for detecting airpressure conditions comprises determining the rate of changes of the airpressure. The means 142 for detecting air pressure conditions related to thecompressor of the turbocharged arrangement of said engine provides a basisfor deciding the seriousness of determined surge events. The means 142 fordetecting air pressure conditions may be comprised in or comprise themeans 113 for determining the pressure ratio over the compressor of theturbocharged arrangement of said engine.

The means 140 for determining a possible appearance of a surge eventcomprises means 144 for determining air flow related to the compressor ofthe turbocharged arrangement of said engine. The means 144 fordetermining air flow may be any suitable flow detector unit. The means 144for determining air flow may be comprised in or comprise the means 114 fordetermining the air mass flow through the turbo compressor. 22 The system I comprises means 150 for adapting the torque reduction ratebased upon the result of the determination of said possible appearance of asurge event in order to obtain a high torque reduction rate and at the sametime avoid said surge event under said determined current conditions for a following gear shift operation.

The means 150 for adapting the torque reduction rate comprises means 152for increasing the torque reduction rate for a following gear shift operationunder said determined current conditions if no surge event has appeared The means 150 for adapting the torque reduction rate comprises means 154for decreasing the torque reduction rate for a following gear shift operation under said determined current conditions if a surge event has appeared.

The means 154 for decreasing the torque reduction rate if a surge event hasappeared is based upon the seriousness of said determined surge event.

The system I comprises according to an embodiment means 160 for storingcurrent conditions comprising torque and engine speed and/or pressure ratioover and air mass flow through the turbo compressor of the enginedetermined prior to performing torque reduction for different gear shiftoperations, and the resulting adaption for avoiding surge events as a basis for choosing certain torque reduction rate.

The means 160 for storing comprises internal storage means 162 on boardthe vehicle. The internal storage means 162 may be any suitable means forstoring information such as a control unit, a computer or the like. The internalstorage means 162 is according to an embodiment comprised in theelectronic control unit 100.

The means 160 for storing comprises external storage means 164 external tothe vehicle. The external storage means 164 may be any suitable externalstorage means such as a sever unit, a personal computer, a tablet, a laptop,a smartphone and/or a so called storage-cloud or the like. 23 The electronic control unit 100 is operably connected to the means 110 fordetermining current conditions comprising torque and engine speed and/orpressure ratio over and air mass flow through the turbo compressor of theengine prior to performing said torque reduction via a link 110a. Theelectronic control unit 100 is via the link 110a arranged to receive a signal from said means 110 representing data for said current conditions.

The electronic control unit 100 is operably connected to the means 111 fordetermining the engine torque prior to performing said torque reduction via alink 111a. The electronic control unit 100 is via the link 111a arranged to receive a signal from said means 111 representing data for engine speed.

The electronic control unit 100 is operably connected to the means 112 fordetermining engine speed prior to performing said torque reduction via a link112a. The electronic control unit 100 is via the link 112a arranged to receive a signal from said means 112 representing data for engine torque.

The electronic control unit 100 is operably connected to the means 113 fordetermining the pressure ratio over the compressor of the turbochargedarrangement of said engine via a link 113a. The electronic control unit 100 isvia the link 113a arranged to receive a signal from said means 113 representing data for pressure ratio over the compressor.

The electronic control unit 100 is operably connected to the means 114 fordetermining the air mass flow through the turbo compressor via a link 114a.The electronic control unit 100 is via the link 114a arranged to receive asignal from said means 114 representing data for air mass flow through theturbo compressor.

The electronic control unit 100 is operably connected to the means 115 for determining ambient pressure via a link 115a. The electronic control unit 100 24 is via the link 115a arranged to receive a signal from said means 115 representing data for ambient pressure.

The electronic control unit 100 is operably connected to the means 116 fordetermining possible changes in engine speed via a link 116a. The electroniccontrol unit 100 is via the link 116a arranged to receive a signal from said means 116 representing data for changes in engine speed.

The electronic control unit 100 is operably connected to the means 120 forchoosing a certain torque reduction rate prior to said gear shift operation viaa link 120a. The electronic control unit 100 is via the link 120a arranged tosend a signal to said means 120 representing data for suggested certaintorque reduction rate based upon earlier gear shift operation under similar conditions.

The electronic control unit 100 is operably connected to the means 120 forchoosing a certain torque reduction rate prior to said gear shift operation viaa link 120b. The electronic control unit 100 is via the link 120b arranged toreceive a signal from said means 120 representing data for chosen certaintorque reduction rate.

The electronic control unit 100 is operably connected to the means 130 forperforming said torque reduction at said chosen rate via a link 130a. Theelectronic control unit 100 is via the link 130a arranged to send a signal tosaid means 130 representing data for chosen certain torque reduction rate.

The electronic control unit 100 is operably connected to the means 130 forperforming said torque reduction at said chosen rate via a link 130b. Theelectronic control unit 100 is via the link 130b arranged to receive a signalfrom said means 130 representing data for torque reduction rate of gear shift operation.

The electronic control unit 100 is operably connected to the means 140 for determining a possible appearance of a surge event via a link 140a. The electronic control unit 100 is via the link 140a arranged to receive a signalfrom said means 140 representing data for possible appearance of a surge eVent.

The electronic control unit 100 is operably connected to the means 142 for detecting air pressure conditions related to the compressor of theturbocharged arrangement of said engine via a link 142a. The electroniccontrol unit 100 is via the link 142a arranged to receive a signal from saidmeans 142 representing data for detected air pressure conditions related to the compressor.

The electronic control unit 100 is operably connected to the means 144 fordetermining air flow related to the compressor of the turbochargedarrangement of said engine via a link 144a. The electronic control unit 100 isvia the link 144a arranged to receive a signal from said means 144 representing data for air flow related to the compressor.

The electronic control unit 100 is operably connected to the means 150 foradapting the torque reduction rate based upon the result of the determinationof said possible appearance of a surge event in order to obtain a high torquereduction rate and at the same time avoid said surge event under saiddetermined current conditions for a following gear shift operation via a link150a. The electronic control unit 100 is via the link 150a arranged to send asignal to said means 150 representing data for possible appearance of a surge event.

The electronic control unit 100 is operably connected to the means 150 foradapting the torque reduction rate based upon the result of the determinationof said possible appearance of a surge event in order to obtain a high torquereduction rate and at the same time avoid said surge event under saiddetermined current conditions for a following gear shift operation via a link150b. The electronic control unit 100 is via the link 150b arranged to receive a signal from said means 150 representing data for adaption of the torque 26 reduction rate under the current conditions for a following gear shift operation.

The electronic control unit 100 is operably connected to the means 152 forincreasing the torque reduction rate for a following gear shift operation undersaid determined current conditions if no surge event has appeared via a link152a. The electronic control unit 100 is via the link 152a arranged to send asignal to said means 152 representing data for non-appearance of a surge GVGHL The electronic control unit 100 is operably connected to the means 152 forincreasing the torque reduction rate for a following gear shift operation undersaid determined current conditions if no surge event has appeared via a link152b. The electronic control unit 100 is via the link 152b arranged to receivea signal from said means 152 representing data for increasing the torquereduction rate under the current conditions for a following gear shift operation.

The electronic control unit 100 is operably connected to the means 154 fordecreasing the torque reduction rate for a following gear shift operation undersaid determined current conditions if a surge event has appeared via a link154a. The electronic control unit 100 is via the link 154a arranged to send asignal to said means 154 representing data for appearance of a surge eventcomprising data for seriousness of the serge event/events.

The electronic control unit 100 is operably connected to the means 154 fordecreasing the torque reduction rate for a following gear shift operation undersaid determined current conditions if a surge event has appeared via a link154b. The electronic control unit 100 is via the link 154b arranged to receivea signal from said means 154 representing data for decreasing the torquereduction rate under the current conditions for a following gear shiftoperation, the seriousness of said determined surge event being taken into QCCOUHL 27 The electronic control unit 100 is operably connected to the means 160 forstoring current conditions comprising torque and engine speed and/orpressure ratio over and air mass flow through the turbo compressor of theengine determined prior to performing torque reduction for different gear shiftoperations, and the resulting adaption for avoiding surge events as a basisfor choosing certain torque reduction rate via a link 160a. The electroniccontrol unit 100 is via the link 160a arranged to send a signal to said means160 representing data for current conditions and the resulting adaption fortorque reduction rate for avoiding surge events.

The electronic control unit 100 is operably connected to the means 160 forstoring current conditions comprising torque and engine speed and/orpressure ratio over and air mass flow through the turbo compressor of theengine determined prior to performing torque reduction for different gear shiftoperations, and the resulting adaption for avoiding surge events as a basisfor choosing certain torque reduction rate via a link 160b. The electroniccontrol unit 100 is via the link 160b arranged to receive a signal from saidmeans 160 representing data for suitable torque reduction rate under thecurrent conditions for a following gear shift operation.

Fig. 5 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. The vehicle 1 is operated by means of aturbocharged internal combustion engine. The vehicle 1 comprises a systemI for controlling torque reduction of a gear shift operation according to anembodiment of the present invention.

Fig. 6 schematically illustrates a block diagram of a method for controllingtorque reduction of a gear shift operation of a vehicle having a turbochargedinternal combustion engine according to an embodiment of the present invenﬁon. 28 According to the embodiment the method for controlling torque reduction of agear shift operation of a vehicle having a turbocharged internal combustionengine comprises a step S1. ln this step current conditions comprising torqueand engine speed and/or pressure ratio over and air mass flow through theturbo compressor of the engine are determined prior to performing said torque reduction.

According to the embodiment the method for controlling torque reduction of agear shift operation of a vehicle having a turbocharged internal combustionengine comprises a step S2. ln this step a certain torque reduction rate ischosen prior to said gear shift operation.

According to the embodiment the method for controlling torque reduction of agear shift operation of a vehicle having a turbocharged internal combustionengine comprises a step S3. ln this step said torque reduction at said chosenrate is performed.

According to the embodiment the method for controlling torque reduction of agear shift operation of a vehicle having a turbocharged internal combustionengine comprises a step S4. ln this step a possible appearance of a surge event is determined.

According to the embodiment the method for controlling torque reduction of agear shift operation of a vehicle having a turbocharged internal combustionengine comprises a step S5. ln this step the torque reduction rate is adaptedbased upon the result of the determination of said possible appearance of asurge event in order to obtain a high torque reduction rate and at the sametime avoid said surge event under said determined current conditions for a following gear shift operation.

Current conditions regarding torque and engine speed may be determinedalone prior to such a torque reduction of a gear shift operation. Currentconditions regarding pressure ratio over the turbo compressor and air mass flow through the turbo compressor of the engine may be determined alone 29 prior to such a torque reduction of a gear shift operation. Current conditionsregarding torque and engine speed and pressure ratio over the turbocompressor and air mass flow through the turbo compressor of the enginemay all be used prior to such a torque reduction of a gear shift operation. Byusing both torque and engine speed and pressure ratio over the turbocompressor and air mass flow through the turbo compressor of the engineredundancy is obtained.

According to an embodiment of the method, for a following gear shiftoperation under said determined current conditions, the step of adapting thetorque reduction rate comprises the step of increasing the torque reductionrate if no surge event has appeared, and decreasing the torque reduction rate if a surge event has appeared.

According to an embodiment of the method the step of determining apossible appearance of a surge event comprises the step of detecting air pressure conditions related to the Compressor of the turbochargedarrangement of said engine so as to decide the seriousness of determined SUFQG GVGHÉS.

According to an embodiment of the method the step of decreasing the torquereduction rate if a surge event has appeared is based upon the seriousness of said determined surge event.

According to an embodiment the method comprises the step of storingcurrent conditions comprising torque and engine speed and/or pressure ratioover and air mass flow through the turbo compressor of the enginedetermined prior to performing torque reduction for different gear shiftoperations, and the resulting adaption for avoiding surge events as a basisfor choosing certain torque reduction rate. Hereby the required adaption ofthe torque reduction rate for the current condition of the forthcoming gearshift operation has been stored and is available/retrievable for that gear shiftoperation such that the adaptation of the torque reduction rate will beoptimized for the current condition. The thus stored required adaption of thetorque reduction rate for a current condition of a forthcoming gear shiftoperation may be stored externally and be made available for an upcominggear shift operation for another vehicle such that the adaption of the torquereduction rate will be optimized for the current condition in connection to thegear shift operation for that other vehicle.

With reference to figure 7, a diagram of an apparatus 500 is shown. Thesystem l described with reference to fig. 4 may according to an embodimentcomprise apparatus 500. Apparatus 500 comprises a non-volatile memory520, a data processing device 510 and a read/write memory 550. Non-volatile memory 520 has a first memory portion 530 wherein a computerprogram, such as an operating system, is stored for controlling the function ofapparatus 500. Further, apparatus 500 comprises a bus controller, a serialcommunication port, I/O-means, an A/D-converter, a time date entry and 31 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 controlling torquereduction of a gear shift operation of a vehicle having a turbocharged internalcombustion engine. The program P comprises routines for, prior toperforming said torque reduction, determining current conditions comprisingtorque and engine speed and/or pressure ratio over and air mass flowthrough the turbo compressor of the engine. The program P comprisesroutines for choosing a certain torque reduction rate prior to said gear shiftoperation. The program P comprises routines for performing said torquereduction at said chosen rate; determining a possible appearance of a surgeevent. The program P comprises routines for adapting the torque reductionrate based upon the result of the determination of said possible appearanceof a surge event in order to obtain a high torque reduction rate and at thesame time avoid said surge event under said determined current conditionsfor a following gear shift operation. The program P comprises routines for, fora following gear shift operation under said determined current conditions,adapting the torque reduction rate comprises the step of increasing thetorque reduction rate if no surge event has appeared, and decreasing thetorque reduction rate if a surge event has appeared. The routines fordetermining a possible appearance of a surge event comprises routines fordetecting air pressure conditions related to the compressor of theturbocharged arrangement of said engine so as to decide the seriousness ofdetermined surge events. The routines for decreasing the torque reductionrate if a surge event has appeared are based upon the seriousness of saiddetermined surge event. The program P comprises routines for storingcurrent conditions comprising torque and engine speed and/or pressure ratioover and air mass flow through the turbo compressor of the enginedetermined prior to performing torque reduction for different gear shiftoperations, and the resulting adaption for avoiding surge events as a basis for choosing certain torque reduction rate. The computer program P may be 32 stored in an executable manner or in a compressed condition in a separate memory 560 and/or in read/write memory 550.

When it is stated that data processing device 510 performs a certain functionit should be understood that data processing device 510 performs a certainpart 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 units100 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, prior to performing said torque reduction,determining current conditions comprising torque and engine speed and/orpressure ratio over and air mass flow through the turbo compressor of theengine. The signals received on data port 599 can be used by apparatus 500for choosing a certain torque reduction rate prior to said gear shift operation.The signals received on data port 599 can be used by apparatus 500 forperforming said torque reduction at said chosen rate; determining a possibleappearance of a surge event. The signals received on data port 599 can beused by apparatus 500 for adapting the torque reduction rate based upon theresult of the determination of said possible appearance of a surge event inorder to obtain a high torque reduction rate and at the same time avoid said surge event under said determined current conditions for a following gear 33 shift operation. The signals received on data port 599 can be used byapparatus 500 for, for a following gear shift operation under said determinedcurrent conditions, adapting the torque reduction rate comprises the step ofincreasing the torque reduction rate if no surge event has appeared, anddecreasing the torque reduction rate if a surge event has appeared. Thesignals used for determining a possible appearance of a surge event areused for detecting air pressure conditions related to the compressor of theturbocharged arrangement of said engine so as to decide the seriousness ofdetermined surge events. The signals used for decreasing the torquereduction rate if a surge event has appeared are based upon the seriousnessof said determined surge event. The signals received on data port 599 canbe used by apparatus 500 for storing current conditions comprising torqueand engine speed and/or pressure ratio over and air mass flow through theturbo compressor of the engine determined prior to performing torquereduction for different gear shift operations, and the resulting adaption foravoiding surge events as a basis for choosing certain torque reduction rate.

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 theinvention for various embodiments and with the various modifications as are suited to the particular use contemplated.

Claims

34 CLAIIVIS

1. A method for controlling torque reduction of a gear shift operation of avehicle having a turbocharged internal combustion engine, characterized bythe steps of: - prior to performing said torque reduction, determining (S1) currentconditions comprising torque and engine speed and/or pressure ratio overand air mass flow through the turbo compressor (32) of the engine; - choosing (S2) a certain torque reduction rate prior to said gear shiftoperation; - performing (S3) said torque reduction at said chosen rate; - determining (S4) a possible appearance of a surge event; and - adapting (S5) the torque reduction rate based upon the result of thedetermination of said possible appearance of a surge event in order to obtaina high torque reduction rate and at the same time avoid said surge event under said determined current conditions for a following gear shift operation.

2. A method according to claim 1, wherein, for a following gear shiftoperation under said determined current conditions, the step of adapting thetorque reduction rate comprises the step of increasing the torque reductionrate if no surge event has appeared, and decreasing the torque reduction rate if a surge event has appeared.

3. A method according to claim 1 or 2, wherein the step of determining apossible appearance of a surge event comprises the step of detecting airpressure conditions related to the compressor of the turbochargedarrangement of said engine so as to decide the seriousness of determined SUFQG GVGHÉS.

4. A method according to claim 3, wherein the step of decreasing the torquereduction rate if a surge event has appeared is based upon the seriousness of said determined surge event.

5. A method according to any of claims 1-4, comprising the step of storingcurrent conditions comprising torque and engine speed and/or pressure ratioover and air mass flow through the turbo compressor of the enginedetermined prior to performing torque reduction for different gear shiftoperations, and the resulting adaption for avoiding surge events as a basis for choosing certain torque reduction rate.

6. A system (l) for contro||ing torque reduction of a gear shift operation of avehicle having a turbocharged internal combustion engine, characterized bymeans (110) for, prior to performing said torque reduction, determiningcurrent conditions comprising means (111) for determining torque and means(112) for determining engine speed and/or means (113) for determiningpressure ratio over the turbo compressor (32) and means (114) fordetermining air mass flow through the turbo compressor (32); means (120)for choosing a certain torque reduction rate prior to said gear shift operation;means (130) for performing said torque reduction at said chosen rate; means(140) for determining a possible appearance of a surge event; and means(150) for adapting the torque reduction rate based upon the result of thedetermination of said possible appearance of a surge event in order to obtaina high torque reduction rate and at the same time avoid said surge eventunder said determined current conditions for a following gear shift operation.

7. A system according to claim 6, wherein, for a following gear shiftoperation under said determined current conditions, the means (150) foradapting the torque reduction rate comprises means (154) for increasing thetorque reduction rate if no surge event has appeared, and means (154) fordecreasing the torque reduction rate if a surge event has appeared.

8. A system according to claim 6 or 7, wherein the means (140) fordetermining a possible appearance of a surge event comprises means (142)for detecting air pressure conditions related to the compressor of theturbocharged arrangement of said engine so as to decide the seriousness of determined surge events. 36

9. A system according to claim 8, wherein the means (154) for decreasingthe torque reduction rate if a surge event has appeared is based upon the seriousness of said determined surge event.

10. A system according to any of c|aims 6-9, comprising means (160) forstoring current conditions comprising torque and engine speed and/orpressure ratio over and air mass flow through the turbo compressor of theengine determined prior to performing torque reduction for different gear shiftoperations, and the resulting adaption for avoiding surge events as a basisfor choosing certain torque reduction rate.

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

12. A computer program (P) for contro||ing torque reduction of a gear shiftoperation of a vehicle having a turbocharged internal combustion engine,said computer program (P) comprising program code which, when run on anelectronic control unit (100) or another computer (500) connected to theelectronic control unit (100), causes the electronic control unit to perform thesteps according to claim 1-5.

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