SE540509C2

SE540509C2 - Method and system for determining an available engine torqueduring a gear shift operation

Info

Publication number: SE540509C2
Application number: SE1550981A
Authority: SE
Inventors: Nordin Mikael; Jacobsson Susanna
Original assignee: Scania Cv Ab
Priority date: 2015-07-07
Filing date: 2015-07-07
Publication date: 2018-09-25
Also published as: SE1550981A1; BR102016015692A2; DE102016007715B4; DE102016007715A1

Abstract

The present invention relates to a method for determining an available engine torque during a gear shift operation (A, B, C, D) prior to performing said gear shift operation, wherein an exhaust gas smoke limiting function of a combustion engine control system of a vehicle is considered. The method comprises the steps of: determining the engine boost pressure; and determining a boost pressure drop corresponding to said determined engine boost pressure during a gear shift of the gear shift operation so as to determine the boost pressure in connection to gear shift engagement. The method further comprises the step of determining an available engine torque (P2) corresponding to activation of limitation of engine torque provided by the exhaust gas smoke limiting function based on the determined boost pressure in connection to gear shift engagement (B3).The present invention also relates to a system for determining an available engine torque during a gear shift operation prior to performing said gear shift operation. The present invention also relates to a computer program and a computer program product.

Description

METHOD AND SYSTEM FOR DETERMINING AN AVAILABLE ENGINE TORQUE DURING A GEAR SHIFT OPERATION TECHNICAL FIELD The invention relates to a method for determining an available engine torque during a gear shift operation prior to performing said gear shift operation according to the preamble of claim 1. The invention also relates to a system for determining an available engine torque during a gear shift operation prior to performing said gear shift operation. The invention also relates to a vehicle. The invention in addition relates to a computer program and a computer program product.

BACKGROUND ART For automatic or semi-automatic transmissions the gear shift operation is performed based on an assessed available engine torque. For certain vehicles, e.g. heavy vehicles such as trucks, the gear shift may according to a variant be effected through shifts of one or more steps, e.g. a one-step shift, a two-step shift, a three-step shift, etc. depending on the available engine torque.

The gear shift operation comprises an off-ramp phase in which the torque is reduced to substantially zero. Then there is a synchronisation phase in which the gear shift is completed by disengaging the current gear and engaging the chosen gear. During the synchronisation phase the engine is synchronized to the next target speed. After the synchronisation phase the gearbox controller returns the torque control to the driver demanded torque. The driver demand torque is supplied to the engine, increasing the available torque up to a level where an exhaust gas smoke limiting function of the combustion engine limits the development of available engine torque up to a driver demand torque.

In order to assess the gear shift tests are made with the specific vehicle in order 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 torque during a gear shift operation.

OBJECTS OF THE INVENTION An object of the present invention is to provide a method for determining an available engine torque during a gear shift operation prior to performing said gear 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 determining an available engine torque during a gear shift operation prior to performing said 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, are achieved by a method, a system, a vehicle, a computer program and a computer program product, as set out in the appended independent claims. Preferred embodiments of the method and the system are defined in appended dependent claims.

Specifically an object of the invention is achieved by a method for determining an available engine torque during a gear shift operation prior to performing said gear shift operation, wherein an exhaust gas smoke limiting function of a combustion engine control system of a vehicle is considered. The method comprises the steps of: determining the engine boost pressure; and determining a boost pressure drop corresponding to said determined engine boost pressure during a gear shift of the gear shift operation so as to determine the boost pressure in connection to gear shift engagement. The method further comprises the step of determining an available engine torque corresponding to activation of limitation of engine torque provided by the exhaust gas smoke limiting function based on the determined boost pressure in connection to gear shift engagement. Hereby a more accurate a basis for the gear shift operation is provided such that the correct gear is chosen prior to the gear shift operation. According to the method, said determined available engine torque corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function constitutes a basis for said gear shift operation. Hereby the gear shift operation will be improved.

According to an embodiment of the method the step of determining an available engine torque corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function comprises the step of, for a certain number of different engine rotational speeds, determining a lowest allowable air/fuel ratio for said determined boost pressure in connection to gear shift engagement. Hereby a more accurate lowest allowable air/fuel ratio may be provided for the relevant engine rotational speed such that an accurate basis for determining the available torque transmission corresponding to activation of limitation of engine torque provided by the exhaust gas smoke limiting function is provided.

According to an embodiment of the method the step of determining an available engine torque corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function comprises the step of determining an allowable amount of fuel based on said determined lowest allowable air/fuel ratio. Hereby an accurate allowable amount of fuel is determined providing an accurate basis for determining the available torque transmission corresponding to activation of limitation of engine torque provided by the exhaust gas smoke limiting function is provided.

According to an embodiment of the method the step of determining an available engine torque corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function is performed based on said determined allowable amount of fuel. Hereby an accurate available engine torque is obtained providing a more accurate basis for the gear shift operation is provided such that the correct gear is chosen prior to the gear shift operation.

According to an embodiment the method comprises the step of determining a development of available engine torque after the determined available engine torque corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function up to an engine torque corresponding to a demanded engine torque. By thus determining the development of 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, an even more accurate basis for the gear shift operation is provided such that the correct gear is chosen prior to the gear shift operation. This further facilitates diagnosing the boost pressure system in that a deviation from the determined point of time when the demanded engine torque is to be reached would indicate a leakage in the boost pressure system, and if the point of time is correct it would indicate that the boost pressure system is working correctly.

According to an embodiment of the method the step of determining a development of available engine torque comprises an estimation of a linear function with 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 said determined development of available engine torque after the determined available engine torque corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function up to an engine torque corresponding to a demanded engine torque constitutes a basis for said gear shift operation. Hereby the gear shift operation will be improved.

Specifically an object of the invention is achieved by a system for determining an available engine torque during a gear shift operation prior to performing said gear shift operation, the system being arranged to consider an exhaust gas smoke limiting function of a combustion engine control system of a vehicle. The system comprises means for determining the engine boost pressure; and means for determining a boost pressure drop corresponding to said determined engine boost pressure during a gear shift of the gear shift operation so as to determine the boost pressure in connection to gear shift engagement. The system further comprises means for determining an available engine torque corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function based on said determined boost pressure in connection to gear shift engagement.

According to an embodiment of the system the means for determining an available engine torque corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function comprises means for determining a lowest allowable air/fuel ratio for said determined boost pressure in connection to gear shift engagement for a certain number of different engine rotational speeds.

According to an embodiment of the system the means for determining an available engine torque corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function comprises means for determining an allowable amount of fuel based on said determined lowest allowable air/fuel ratio.

According to an embodiment of the system the means for determining an available engine torque corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function is arranged to be performed based on said determined allowable amount of fuel.

According to an embodiment the system comprises means for determining a development of available engine torque after the determined available engine torque corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function up to an engine torque corresponding to a demanded engine torque.

According to an embodiment of the system the means for determining a development of available engine torque comprises an estimation of a linear function with a certain torque development increase rate.

According to an embodiment of the system said determined available engine torque corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function constitutes a basis for said gear shift operation.

According to an embodiment of the system said determined development of available engine torque after the determined available engine torque corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function up to an engine torque corresponding to a demanded engine torque constitutes a basis for said gear shift operation.

The system for determining an available engine torque during a gear shift operation prior to performing said gear shift operation is adapted to perform the method as set out herein.

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

Specifically an object of the invention is achieved by a computer program for determining an available engine torque during a gear shift operation prior to performing said gear shift operation, said computer program comprising program code which, when run on an electronic control unit or another computer 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 the following detailed description when read in conjunction with the accompanying 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. 3 schematically illustrates the boost pressure drop during a gear shift operation for different boost pressures prior to the gear shift operation ; Fig. 4 schematically illustrates a system for determining an available engine torque during a gear shift operation prior to performing said gear shift operation according to an embodiment of the present invention; Fig. 5 schematically illustrates a block diagram of a method for determining an available engine torque during a gear shift operation prior to performing said gear shift operation according to an embodiment of the present invention; 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 a physical connector, such as an optoelectronic communication wire, or a nonphysical connector such as a wireless connection, for example a radio or microwave link.

Hereinafter the term “demanded torque”, “demanding a torque”, “demanded engine torque” or the like for a vehicle refers to a torque demanded by the driver of the vehicle, or by any suitable torque demanding function such as a cruise control torque demanding function, i.e. a torque demanding function provided by a cruise control system, or a speed limiter torque demanding function, i.e. a torque demanding function provided by a speed limiter system. 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 the present invention. The exemplified vehicle 1 is a heavy vehicle in the shape of a truck. The vehicle according to the present invention could be any suitable vehicle such as a bus or a car. The vehicle is driven by means of an internal combustion engine being turbocharged by means of a turbo compressor configured to compress air in to the cylinders of the engine. The vehicle comprises an automatic or semi-automatic transmission configured to provide automatic or semi-automatic gear shift operation during drive of the vehicle. The vehicle comprises a combustion engine control system having an exhaust gas limiting 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 engine torque 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 lower gear to a higher gear. In an up-shift operation there is a decrease in engine rotational speed. The up-shift operation is an example. The invention is equally applicable to a down-shift operation.

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

Then there is a gear disengagement, synchronisation and gear engagement phase B in which the gear shift is completed. The synchronisation phase B comprises a disengagement phase B1 in which a gear shift disengagement of the current gear is effected. The phase B comprises a synchronisation phase B2 in which no gear is connected. The phase B comprises an engagement 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 of actual gear in the gear disengagement phase B1 to target gear in the gear engagement phase B3, an on-ramp phase C is initiated, in which fuel corresponding to the demanded torque to the engine is supplied, increasing the available torque up to a level in the point P2 where an exhaust gas smoke limiting function of the combustion engine is arranged to limit the development of available engine torque.

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

In order to determine the available torque up to a level in the point P2 where an exhaust gas smoke limiting function of the combustion engine is arranged to limit the development of available engine torque prior to the gear shift operation the current engine boost pressure is determined intermittently or continuously. The engine boost pressure may according to an embodiment be determined several times per second in order to have a good basis in connection 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 boost pressure during a gear shift of the gear shift operation is determined by comparing the determined boost pressure to the boost pressure drop at such a boost pressure which has been assessed by plotting boost pressure drops during phase A and B of the gear shift operation for different boost pressures determined for the particular vehicle. An example of such a plot is illustrated in fig. 3. The boost pressure in connection to gear shift engagement, i.e. the boost pressure in point P1 in fig. 2, thus corresponds to the determined boost pressure subtracted by the corresponding boost pressure drop.

The available engine torque at point P2 is determined based on the thus determined boost pressure in connection to gear shift engagement.

For a certain boost pressure in connection to gear shift engagement at point P1 for a certain engine rotational speed there is a certain lowest allowable air/fuel ratio. The air/fuel ratio is also called lambda ?.

Thus, a lowest allowable air/fuel ratio for said determined boost pressure in connection to gear shift engagement is determined for a certain number of different engine rotational speeds. The lowest allowable lambda is according 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 determined lowest allowable air/fuel ratio. The current atmospheric pressure is hereby considered. The boost pressure at point P1, the boost temperature and the oxygen weight ratio are according to an embodiment also taken into account in determining the allowable amount of fuel. For selective catalytic reduction (SCR) systems the exhaust gas recirculation (EGR) content is taken into consideration with regard to the lowest allowable air/fuel ratio. The stoichiometric air/fuel ratio, i.e. the theoretically necessary relationship between fuel and air amount for accomplishing complete combustion, is also taken into account. The air, or rather oxygen, required for complete combustion 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 is determined 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 an embodiment provided from a map for the respective engine rotational speed.

The development of available engine torque from the point P2, i.e. the point for activation of limitation of available engine torque provided by an exhaust gas smoke limiting function of a combustion engine control system of the vehicle, up to an engine torque corresponding to a demanded engine torque is 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 P3 comprises 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 development increase rate is according to an embodiment provided by means of testbeds, i.e. calibration of the engine in which the time required to reach the demanded engine torque from the point P2 of limitation is determined. The calibration of the engine comprises performing motoring, driving the engine at full load and determining the engine torque at full load and then performing motoring again. Motoring is performed over a short time span. This calibration 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 development increase rate is according to an embodiment provided by means of modelling the torque development increase rate.

The calibration test is engine specific in that the torque at full load for different engine rotational speeds varies for different engines.

In this calibration test certain parameters are taken into account comprising number 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 is determined prior to the gear shift operation by means of assessing the maximum engine torque at full load for the engine as a function of the engine rotational 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 by means of a response time factor as a function of the engine rotational speed times the maximum engine torque as a function of the engine rotational speed 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 provided from 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 is calculated in a function comprising the engine rotational speed.

The torque factor as a function of number of cylinders of the engine is a function 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.

Determining the development of engine torque further facilitates diagnosing the boost pressure system of the vehicle in that a deviation from the determined point P3 of time when the demanded engine torque is to be reached would indicate a leakage in the boost pressure system. Thus, if the actual point P4 where the demanded engine torque is reached is determined to deviate from the estimated point P3 leakage of the boost pressure system is indicated. If the actual point P3 where the demanded engine torque is reached is determined to substantially correspond to the estimated point P3 the boost pressure system is indicated to function correctly.

Thus, the determined development of available engine torque is taken as a basis for diagnosing the boost pressure system of the vehicle engine.

Fig. 3 schematically illustrates the boost pressure drop during a gear shift operation for different boost pressures prior to the gear shift operation.

In the graph, the boost pressure drop has been determined for different boost pressures for 1-step shifts, 2-step shifts and 3-step shifts. In the graph 1-step shifts, 2-step shifts and 3-step shifts are illustrated as examples. For boost pressures above a certain level, here above approximately 1500 mbar, the boost pressure drop increases substantially linear, essentially independently of whether it is a 1 -step shift, a 2-step shift or a 3-step shift. In the graph 1 -step shifts, 2-step shifts and 3-step shifts are illustrated as examples. Flowever, all gear shifts are applicable, i.e. gear shifts higher than 3-step shift 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 or intermittently and for each determined boost pressure the boost pressure drop that would be the result of a gear shift operation is determined from the plot. For example a determined boost pressure of 2500 mbar corresponds to a boost pressure drop of approximately 800 mbar in connection to a gear shift engagement should a gear shift operation be initiated. This results in a boost pressure in connection to gear shift engagement during a gear shift operation of 2500-800=1700 mbar, which is used as a basis for determining the available engine torque corresponding to activation of limitation of engine torque 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. 3, the boost pressure drop may advantageously be determined by means of engine boost pressure change rate determined by means of the boost pressure prior to the gear shift operation. Such a situation where the engine boost pressure prior to the gear shift operation is relatively low and increasing may typically be a vehicle starting situation where the vehicle is accelerated from a standstill or close to a standstill by a demanded torque. In a graph, boost pressure drop is determined for different boost pressure change rates for up-shifts for low gears, i.e. gears prior to gear shift operation being at 3 or lower, and for high gears, i.e. gears being at 4 or higher. For such relatively low boost pressures up to a certain level, the boost pressure drop increases substantially linear with increasing boost pressure change rate, essentially independently of whether it is a gear shift from low gear or a gear shift from a high gear.

Fig. 4 schematically illustrates a system for determining an available engine torque during a gear shift operation prior to performing the gear shift operation 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 being turbocharged by means of a turbo compressor configured to compress air in to the cylinders of the engine. The vehicle comprises an automatic or semiautomatic transmission configured to provide automatic or semi-automatic gear shift operation during drive of the vehicle. The vehicle comprises a combustion engine control system having an exhaust gas limiting function for limiting exhaust gas smoke during combustion by limiting the allowable amount of fuel to the cylinders when applicable.

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

The system I comprises means 120 for determining a boost pressure drop corresponding to the determined engine boost pressure during a gear shift of the gear shift operation.

The means 120 for determining a boost pressure drop corresponding to the determined engine boost pressure during a gear shift of the gear shift operation comprises according to an embodiment data for boost pressure drops during a gear shift operation for different boost pressures prior to a gear shift operation. The data for boost pressure drops corresponding to different boost pressures prior to a gear shift operation are according to an embodiment boost pressure drops determined for different boost pressures for 1 -step shifts, 2-step shifts and 3-step shifts during a gear shift operation. The means 120 comprises according to an embodiment data according to the plot illustrated in fig. 3.

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

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

The means 120 comprises according to an embodiment a storage unit comprising data for boost pressure drops during a gear shift operation for different boost pressures prior to a gear shift operation. The storage unit is according 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 electronic control unit 100.

The system I comprises means 130 for determining an available engine torque corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function based on said determined boost pressure in connection to gear shift engagement.

The means 130 for determining an available engine torque corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function comprises means 132 for determining a lowest allowable air/fuel ratio for a certain number of different engine rotational speeds.

The means 132 for determining a lowest allowable air/fuel ratio for a certain number of different engine rotational speeds comprises according to an embodiment data for lowest allowable air/fuel ratios for different engine rotational speeds for different boost pressures. The thus determined boost pressure in connection to gear shift engagement is hereby used to determine lowest allowable air/fuel ratios for different engine rotational speeds. The engine rotational speed is depending on the gear shift, i.e. if it is a 1 -shift, 2-shift or 3-shift of the gear in connection to the gear shift operation.

The means 132 comprises according to an embodiment a storage unit comprising data for data for lowest allowable air/fuel ratios for different engine rotational speeds for different boost pressures. The storage unit is according 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 132 is according to an embodiment comprised in the electronic control unit 100.

The means 130 for determining an available engine torque corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting 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 said determined lowest allowable air/fuel ratio comprises taking volumetric efficiency, i.e. fill rate in the cylinder. The volumetric efficiency is provided from a vector which has been calibrated in a testbed. The means 134 for determining an allowable amount of fuel based on said determined lowest allowable air/fuel ratio further comprises taking boost temperature. The boost temperature is determined by means of one or more sensor units arranged in the inlet manifold. The means 134 for determining an allowable amount of fuel based on said determined lowest allowable air/fuel ratio is determined with regard to the determined boost pressure in connection to gear shift engagement. The oxygen weight ratio is according to an embodiment also taken into account in determining the allowable amount of fuel. For selective catalytic reduction (SCR) systems the exhaust gas recirculation (EGR) content is taken into consideration with regard to the lowest allowable air/fuel ratio. The stoichiometric air/fuel ratio, i.e. the theoretically necessary relationship between fuel and air amount for accomplishing complete combustion. 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 to activation of limitation of engine torque provided by said exhaust gas smoke limiting function is arranged to be performed based on the determined allowable amount of fuel. The means 130 for determining an available engine torque corresponding to activation of limitation of engine torque provided by said 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 of limitation of engine torque provided by said exhaust gas smoke limiting function constitutes a basis for said gear shift operation.

The system I comprises means 140 for determining the demanded engine torque. The means 140 for determining the demanded engine torque comprises according to an embodiment means for detecting the position of the gas pedal. The means 140 for determining the demanded engine torque comprises 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 atmospheric pressure. The means 150 for determining the atmospheric pressure comprises an air pressure sensor. The means 150 for determining the atmospheric pressure comprises according to an embodiment a barometer unit. The means 150 for determining the atmospheric pressure comprises according to an embodiment weather data received from an external unit, e.g. from a weather station.

The system I comprises means 160 for determining a development of available engine torque after the determined available engine torque corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function up to an engine torque corresponding to a demanded engine torque.

The means 160 for determining a development of available engine torque comprises means 162 for estimating a linear function with a certain torque development increase rate. The estimation of a linear function with a certain torque development increase rate is according to an embodiment provided by means of testbeds, i.e. calibration of the engine in which the time required to reach the demanded engine torque from the point of limitation is determined. The estimation of linear function with a certain torque development increase rate 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 torque comprises means 164 for estimating the maximum engine torque and the response time for the engine from motoring to the maximum engine torque for a certain number of different engine rotational speeds. The estimation of response time for the engine from motoring to the maximum engine torque is according to an embodiment obtained by calibration of the engine in a testbed.

The maximum engine torque at full load for the engine as a function of the engine rotational speed is estimated in the calibration. The maximum engine torque thus determined is divided with the response time from motoring to the maximum engine torque. The response time from motoring to maximum torque is determined by means of a response time factor as a function of the engine rotational speed times the maximum engine torque as a function of the engine rotational speed 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 provided from 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 is calculated in a function comprising the engine rotational speed. The torque factor as a function of number of cylinders of the engine is a function where the number of cylinders of the engine is included as a parameter.

The determined development of available engine torque after the determined available engine torque corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function constitutes a basis for said gear shift operation.

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

The means 170 for determining a suitable gear shift for a gear shift operation comprises means 172 for taking the determined available engine torque corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function as a basis.

The means 170 for determining a suitable gear shift for a gear shift operation comprises means 174 for taking the determined development of available engine torque after the determined available engine torque corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function as a basis.

The system I comprises means 180 for diagnosing the boost pressure system of the vehicle. The means 180 for diagnosing the boost pressure system of the vehicle comprises means for determining the actual development of available engine torque after the determined available engine torque corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function up to an engine torque corresponding to a demanded engine torque determined after the gear shift operation. The means 180 comprises means for comparing the actual development of available engine torque to the development of engine torque determined prior to the gear shift operation with the means 160. If there is a difference such that the actual development of available engine torque reaches the demanded torque at a later stage than the assessed development 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 the means 110 for determining the engine boost pressure via a link 10. The electronic control unit 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 detector unit 112 for detecting the engine boost pressure via a link 12. The electronic control unit 100 is via the link 12 arranged to receive a signal from the pressure detector unit 112 representing data for the engine boost pressure prior to a gear shift operation.

The electronic control unit 100 is operably connected to the means 120 for determining a boost pressure drop corresponding to the determined engine boost pressure during a gear shift of the gear shift operation via a link 20a. The electronic control unit 100 is via the link 20a arranged to send a signal to the means 120 representing data for the engine boost pressure prior to a gear shift operation.

The electronic control unit 100 is operably connected to the means 120 for determining a boost pressure drop corresponding to the determined engine boost pressure during a gear shift of the gear shift operation via a link 20b. The electronic control unit 100 is via the link 20b arranged to receive a signal from the means 120 representing data for boost pressure drop corresponding to the determined engine boost pressure during a gear shift of the gear shift operation. According to an embodiment the electronic control unit 100 is via the link 20b arranged to 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 for determining an available engine torque corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function based on said determined boost pressure in connection to gear shift engagement via a link 30a. The electronic control unit 100 is via the link 30a arranged to send a signal 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 for determining an available engine torque corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function based on said determined boost pressure in connection to gear shift engagement via a link 30b. The electronic control unit 100 is via the link 30b arranged to receive a signal from the means 130 representing data for available engine torque corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function.

The electronic control unit 100 is operably connected to the means 132 for determining a lowest allowable air/fuel ratio for a certain number of different engine rotational speeds via a link 32a. The electronic control unit 100 is via the 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 for determining a lowest allowable air/fuel ratio for a certain number of different engine rotational speeds via a link 32b. The electronic control unit 100 is via the link 32b arranged to receive a signal from the means 132 representing data for lowest allowable air/fuel ratio for a certain number of different engine rotational speeds.

The electronic control unit 100 is operably connected to the means 134 for determining an allowable amount of fuel via a link 34a. The electronic control unit 100 is via the link 34a arranged to send a signal to the means 134 representing data for lowest allowable air/fuel ratio for a certain number of different engine rotational speeds.

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

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

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

The electronic control unit 100 is operably connected to the means 160 for determining a development of available engine torque after the determined available engine torque corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function up to an engine torque corresponding to a demanded engine torque via a link 60a. The electronic control unit 100 is via the link 60a arranged to send a signal to the means 160 representing data for demanded engine torque and data for available engine torque corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function.

The electronic control unit 100 is operably connected to the means 160 for determining a development of available engine torque after the determined available engine torque corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function up to an engine torque corresponding to a demanded engine torque via a link 60b. The electronic control unit 100 is via the link 60b arranged to receive a signal from the means 160 representing data for development of available engine torque after the determined available engine torque corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function up to an engine torque corresponding to a demanded engine torque.

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

The electronic control unit 100 is operably connected to the means 162 for estimating a linear function with a certain torque development increase rate via a link 62b. The electronic control unit 100 is via the link 62b arranged to send 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 for estimating the maximum engine torque and the response time for the engine from motoring to the maximum engine torque for a certain number of different engine rotational speeds via a link 64a. The electronic control unit 100 is via the 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 for estimating the maximum engine torque and the response time for the engine from motoring to the maximum engine torque for a certain number of different engine rotational speeds via a link 64b. The electronic control unit 100 is via the link 64b arranged to receive a signal from the means 164 representing data 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 170 for determining a suitable gear shift for a gear shift operation via a link 70a. The electronic control unit 100 is via the link 70a arranged to send a signal to the means 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 for determining a suitable gear shift for a gear shift operation via a link 70b. The electronic control unit 100 is via the link 70b arranged to receive a signal from the means 170 representing data for suitable gear shift for a gear shift operation.

The electronic control unit 100 is operably connected to the means 172 for taking the determined available engine torque corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function via a link 72. The electronic control unit 100 is 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 for taking the determined development of available engine torque after the determined available engine torque corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function via a link 74. The electronic control unit 100 is via the link 74 arranged 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 for diagnosing the boost pressure system of the vehicle via a link 80a. The electronic control unit 100 is via the link 80a arranged to send a signal to the means 180 representing data for actual engine torque development after gear 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 for diagnosing the boost pressure system of the vehicle via a link 80b. The electronic control unit 100 is via the link 80b arranged to receive a signal from the 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 determining an available engine torque during a gear shift operation prior to performing said gear shift operation, wherein an exhaust gas smoke limiting function of a combustion engine control system of a vehicle is considered according to an embodiment of the present invention.

According to the embodiment the method for determining an available engine torque during a gear shift operation prior to performing said gear shift operation comprises a step S1. In this step the engine boost pressure is determined. The engine boost pressure is continuously or intermittently determined prior to a gear shift operation. The engine boost pressure is detected by means of one or more detector units.

According to the embodiment the method for determining an available engine torque during a gear shift operation prior to performing said gear shift operation comprises a step S2. In this step a boost pressure drop corresponding to said determined engine boost pressure during a gear shift of the gear shift operation is determined so as to determine the boost pressure in connection to gear shift engagement. The boost pressure drop during a gear shift operation is thus assessed prior to the gear shift operation by means of the engine boost pressure. The boost pressure in connection to gear shift engagement is assessed prior to the gear shift operation by means of the thus determined boost pressure drop. The boost pressure drop corresponding to the determined engine boost pressure during a gear shift of the gear shift operation is determined by comparing the determined boost pressure to the boost pressure drop at such a boost pressure which has been assessed by plotting boost pressure drops during a gear shift operation for different boost pressures determined for the vehicle. The boost pressure in connection to gear shift engagement is determined by subtracting the boost pressure drop determined from the corresponding boost pressure prior to gear shift operation.

According to the embodiment the method for determining an available engine torque during a gear shift operation prior to performing said gear shift operation comprises a step S3. In this step an available engine torque corresponding to activation of limitation of engine torque provided by the exhaust gas smoke limiting function based on the determined boost pressure in connection to gear shift engagement is determined.

According to an embodiment of the method the step of determining an available engine torque corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function comprises the step of, for a certain number of different engine rotational speeds, determining a lowest allowable air/fuel ratio for said determined boost pressure in connection to gear shift engagement.

According to an embodiment of the method the step of determining an available engine torque corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function comprises the step of determining an allowable amount of fuel based on said determined lowest allowable air/fuel ratio.

According to an embodiment of the method the step of determining an available engine torque corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function is performed based on said determined allowable amount of fuel.

According to an embodiment the method comprises the step of determining a development of available engine torque after the determined available engine torque corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function up to an engine torque corresponding to a demanded engine torque.

According to an embodiment of the method the step of determining a development of available engine torque comprises an estimation of a linear function with a certain torque development increase rate. The estimation of a linear function with a certain torque development increase rate is according to an embodiment provided by means of testbeds, i.e. calibration of the engine in which the time required to reach the demanded engine torque from the point of limitation is determined. The estimation of linear function with a certain torque 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 a development of available engine torque comprises the step of, for a certain number of different engine rotational speeds, estimating the maximum engine torque and the response time for the engine from motoring to the maximum engine torque. The estimation of response time for the engine from motoring to the 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 determined available engine torque corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function constitutes a basis for said gear shift operation.

According to an embodiment of the method said determined development of available engine torque after the determined available engine torque corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function up to an engine torque corresponding to a demanded engine torque constitutes a basis for said gear shift operation.

The method and the method steps described above with reference to fig. 5 is according 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. The control unit 100 described with reference to fig. 4 may according to an embodiment comprise apparatus 500. Apparatus 500 comprises a non-volatile memory 520, a data processing device 510 and a read/write memory 550. Non-volatile memory 520 has a first memory portion 530 wherein a computer program, such as an operating system, is stored for controlling the function of apparatus 500. Further, apparatus 500 comprises a bus controller, a serial communication port, l/O-means, an A/D-converter, a time date entry and 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 an available engine torque during a gear shift operation prior to performing said gear shift operation, wherein an exhaust gas smoke limiting function of a combustion engine control system of a vehicle is considered. The program P comprises routines for determining the engine boost pressure. The program P comprises routines for determining a boost pressure drop corresponding to said determined engine boost pressure during a gear shift of the gear shift operation so as to determine the boost pressure in connection to gear shift engagement. The program P comprises routines for determining an available engine torque corresponding to activation of limitation of engine torque provided by the exhaust gas smoke limiting function based on the determined boost pressure in connection to gear shift engagement. The computer program P may be 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 function it should be understood that data processing device 510 performs a certain 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 communications port 599 by means of a data bus 515. Non-volatile memory 520 is adapted for communication with data processing device 510 via a data bus 512. Separate memory 560 is adapted for communication with data processing device 510 via a data bus 511. Read/write memory 550 is adapted for communication with data processing device 510 via a data bus 514. To the data 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 second memory portion 540. When the received input data has been temporarily stored, data processing device 510 is set up to perform execution of code in a manner described above. The signals received on data port 599 can be used by apparatus 500 for determining the engine boost pressure. The signals received on data port 599 can be used by apparatus 500 for determining a boost pressure drop corresponding to said determined engine boost pressure during a gear shift of the gear shift operation so as to determine the boost pressure in connection to gear shift engagement. The signals received on data port 599 can be used by apparatus 500 for determining an available engine torque corresponding to activation of limitation of engine torque provided by the exhaust gas smoke limiting function based on the determined boost pressure in connection to gear shift engagement.

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

The foregoing description of the preferred embodiments of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to understand the invention for various embodiments and with the various modifications as are suited to the particular use contemplated.

Claims

1. A method for determining an available engine torque during a gear shift operation (A, B, C, D) prior to performing said gear shift operation, wherein an exhaust gas smoke limiting function of a combustion engine control system of a vehicle (1) is considered, characterized by the steps of: - determining (S1) the engine boost pressure; - determining (S2) a boost pressure drop corresponding to said determined engine boost pressure during a gear shift of the gear shift operation so as to determine the boost pressure in connection to gear shift engagement; - determining (S3) an available engine torque (P2) corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function based on said determined boost pressure in connection to gear shift engagement (B3), wherein said determined available engine torque (P2) corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function constitutes a basis for said gear shift operation.

2. A method according to claim 1, wherein the step of determining an available engine torque corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function comprises the step of, for a certain number of different engine rotational speeds, determining a lowest allowable air/fuel ratio for said determined boost pressure in connection to gear shift engagement.

3. A method according to claim 2, wherein the step of determining an available engine torque corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function comprises the step of determining an allowable amount of fuel based on said determined lowest allowable air/fuel ratio.

4. A method according to claim 3, wherein the step of determining an available engine torque corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function is performed based on said determined allowable amount of fuel.

5. A method according to any of claims 1-4, comprising the step of determining a development (D) of available engine torque after the determined available engine torque (P2) corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function up to an engine torque (P3) corresponding to a demanded engine torque.

6. A method according to claim 5, wherein the step of determining a development of available engine torque comprises an estimation of a linear function with a certain torque development increase rate.

7. A method according to claim 5 or 6, wherein said determined development (D) of available engine torque after the determined available engine torque (P2) corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function up to an engine torque (P3) corresponding to a demanded engine torque constitutes a basis for said gear shift operation.

8. A system (I) for determining an available engine torque during a gear shift operation prior to performing said gear shift operation (A, B, C, D), the system being arranged to consider an exhaust gas smoke limiting function of a combustion engine control system of a vehicle (1), characterized by means (110) for determining the engine boost pressure; means (120) for determining a boost pressure drop corresponding to said determined engine boost pressure during a gear shift of the gear shift operation so as to determine the boost pressure in connection to gear shift engagement; and means (130) for determining an available engine torque (P2) corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function based on said determined boost pressure in connection to gear shift engagement (B3), wherein said determined available engine torque (P2) corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function constitutes a basis for said gear shift operation.

9. A system according to claim 8, wherein the means (130) for determining an available engine torque corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function comprises means (132) for determining a lowest allowable air/fuel ratio for a certain number of different engine rotational speeds.

10. A system according to claim 9, wherein the means (130) for determining an available engine torque corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function comprises means (134) for determining an allowable amount of fuel based on said determined lowest allowable air/fuel ratio.

11. A system according to claim 10, wherein the means (130) for determining an available engine torque corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function is arranged to be performed based on said determined allowable amount of fuel.

12. A system according to any of claims 8-11, comprising means (160) for determining a development (D) of available engine torque after the determined available engine torque corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function up to an engine torque (P3) corresponding to a demanded engine torque.

13. A system according to claim 12, wherein the means (160) for determining a development (D) of available engine torque comprises means (162) for estimating a linear function with a certain torque development increase rate.

14. A system according to claim 12 or 13, wherein said determined development (D) of available engine torque after the determined available engine torque (P2) corresponding to activation of limitation of engine torque provided by said exhaust gas smoke limiting function up to an engine torque (P3) corresponding to a demanded engine torque constitutes a basis for said gear shift operation.

15. A vehicle (1) comprising a system (I) according to any of claims 8-14.

16. A computer program (P) for determining an available engine torque during a gear shift operation prior to performing said gear shift operation, said computer program (P) comprising program code which, when run on an electronic control unit (100) or another computer (500) connected to the electronic control unit (100), causes the electronic control unit to perform the steps according to claim 1-7.

17. A computer program product comprising a digital storage medium storing the computer program according to claim 16.