SE541113C2

SE541113C2 - Method and system for controlling fuel injection in connection to engine start procedure

Info

Publication number: SE541113C2
Application number: SE1650887A
Authority: SE
Inventors: Mikael Nordin; Susanna Jacobsson
Original assignee: Scania Cv Ab
Priority date: 2016-06-22
Filing date: 2016-06-22
Publication date: 2019-04-09
Also published as: DE102017005860A1; SE1650887A1

Abstract

The present invention relates to a method for controlling fuel injection in connection to engine start procedure. The method comprises the steps of: choosing (S1) a certain amount of fuel for injection to initiate said engine start procedure; and determining (S2) a resulting engine speed development based upon said certain amount of fuel. The method further comprises the steps of: determining (S3) the engine speed increase rate of said resulting engine speed development; and adapting (S4) the amount of fuel based upon said engine speed increase rate.The present invention also relates to a system for controlling fuel injection in connection to engine start procedure. The present invention also relates to a vehicle. The present invention also relates to a computer program and a computer program product.

Description

METHOD AND SYSTEM FOR CONTROLLING FUEL INJECTION IN CONNECTION TO ENGINE START PROCEDURE TECHNICAL FIELD The invention relates to a method for controlling fuel injection in connection to engine start procedure according to the preamble of claim 1. The invention also relates to a system for controlling fuel injection in connection to engine start procedure. The invention also relates to a vehicle. The invention in addition relates to a computer program and a computer program product.

BACKGROUND ART In connection to the start procedure of an internal combustion engine the amount of fuel used need to be sufficient in order for the engine to start. In order to determine the amount of fuel to be used in an engine start procedure a calibrated engine water/oil temperature/engine speed map may be used. Determining the amount of fuel based on such calibrated data may however result in overshoot of the engine speed in connection to reaching the idle speed for engine start, and may also result in uneven control of the idle speed.

US20030047164 discloses a method in which the engine speed at an engine start procedure is measured, wherein the measured value is compared to a reference value, wherein the fuel may be modified based on a difference between the measured value and the reference value in order to improve reduction in emissions.

There is thus a need for improving control of fuel injection in connection to engine start procedure.

OBJECTS OF THE INVENTION An object of the present invention is to provide a method for controlling fuel injection in connection to engine start procedure which facilitates improving control of engine start procedures.

An object of the present invention is to provide a method for controlling fuel injection in connection to engine start procedure which facilitates control of the engine start so as to obtain a desired start behaviour of the engine.

An object of the present invention is to provide a method for controlling fuel injection in connection to engine start procedure which facilitates control of the engine start so as to obtain start behaviour of the engine such that the engine starts within a desired time, reducing/mitigating/avoiding undesired overshoot of the engine speed during the start procedure.

An object of the present invention is to provide a system for controlling fuel injection in connection to engine start procedure which facilitates control of the engine start so as to obtain a desired start behaviour of the engine.

An object of the present invention is to provide a system for controlling fuel injection in connection to engine start procedure which facilitates control of the engine start so as to obtain start behaviour of the engine such that the engine starts within a desired time, reducing/mitigating/avoiding undesired overshoot of the engine speed during the start procedure.

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 controlling fuel injection in connection to engine start procedure. The method comprises the step of: choosing a certain amount of fuel for injection to initiate said engine start procedure. Said chosen amount of fuel being based upon an estimated power demand for keeping said engine running at idle speed. The method further comprises the steps of: during engine idle speed of the engine start procedure after start of the engine determining an actual power demand required for keeping said engine running at idle speed based upon current conditions comprising engine temperature; and adapting the amount of fuel based upon said determined actual power demand in a following engine start procedure.

A first certain amount of fuel chosen for a first engine start procedure is according to an embodiment chosen taking current engine temperature into account. A first certain amount of fuel chosen for a first engine start procedure is thus chosen based upon the demanded power demand required for keeping said engine running at idle speed.

The engine start procedure comprises the start of injection when said certain amount of fuel is injected and until the engine has started. The engine start procedure comprises according to an embodiment a certain period of engine idle speed. The period from start of injection when said certain amount of fuel is injected to when the engine has started at idle speed is according to an embodiment denoted engine start development.

By thus adapting the amount of fuel based upon said determined actual power demand in a following engine start procedure control of engine start procedures are improved. By thus adapting the amount of fuel based upon said determined actual power demand in a following engine start procedure a good basis for choosing a suitable amount of fuel in a following engine start is obtained. Hereby control of the engine start so as to obtain a desired start behaviour of the engine is improved in following engine start procedures. Hereby a starting behaviour which is repeatable may be obtained in an efficient way. Having repeated the adaption of amount of fuel in a few following engine start procedures the engine starting behaviour will be optimized to the desired behaviour, i.e. the engine speed development during the engine start procedures will be repeatable. The behaviour of the particular internal combustion engine during engine start procedures will be repeatable during the life time of the engine. Certain changes in the engine with respect to ageing will be considered by performing said adaption of amount of fuel. By thus adapting the amount of fuel based upon said determined actual power demand in a following engine start procedure the need for calibrating the amount of fuel for start procedures is reduced.

By thus adapting the amount of fuel based upon said determined actual power demand in a following engine start procedure the engine speed development during the engine start procedure can be controlled such that a desired starting behaviour of the engine is obtained wherein the time for starting the engine, i.e. the time for reaching the engine idle speed, does not take too long, and wherein an overshoot behaviour with respect to said engine speed can be reduced/mitigated/avoided.

According to an embodiment the method comprises the step of adapting the determined actual power demand for keeping the engine running at idle speed to the engine speeds during the engine start procedure. Adapting the determined actual power demand for keeping the engine running at idle speed the engine speeds during the engine start procedure, i.e. the engine speed development during the engine start development, results in different torques which corresponds to a certain amount of fuel. Adapting the amount of fuel based upon said determined actual power demand required for keeping said engine running at a certain idle speed in a following engine start procedure is thus performed where the determined actual power demand for keeping the engine running at idle speed has been adapted to the engine speeds during the engine start procedure.

According to an embodiment of the method the step of adapting the amount of fuel based upon said actual power demand in a following engine start procedure comprises the step of adapting the amount of fuel to current conditions with respect to engine temperature in the following engine start. Hereby a more accurate amount of fuel may be chosen for that engine start thus facilitating improved engine start procedure. The amount of fuel adapted based upon the actual power demand in a following engine start procedure comprises in addition to adapting the amount of fuel to current conditions with respect to engine temperature in the following engine start taking the engine speed of the engine start procedure into consideration.

According to an embodiment of the method the step of adapting the amount of fuel based upon said actual power demand in a following start taking current conditions into account comprises: decreasing the amount of fuel if the power demand is lower than said estimated power demand, and increasing the amount of fuel if power demand is higher than said estimated power demand. By thus taking the current conditions comprising engine temperature into consideration a good estimation of the chosen amount based upon determined actual power demand is facilitated.

According to an embodiment the method comprises the step of storing actual power demands required for keeping said engine running at idle speed for different current conditions comprising engine temperature, the actual power demands being determined during engine idle speed of the engine start procedure after start of the engine in connection to different engine start procedures so as to provide a basis for choosing the amount of fuel for injection to initiate following engine start procedures. Hereby the power demand required for keeping the engine running at idle speed for the current condition of an engine start may be stored and made available for that start such that the adaptation of the amount of fuel can be made based upon a power demand determined for such conditions, the conditions comprising engine temperature.

The determined actual power demand for keeping the engine running at idle speed is thus adapted to the engine speeds during an engine start procedure, thus resulting in different torques which corresponds to a certain amount of fuel.

According to an embodiment of the method the step of determining an actual power demand required for keeping said engine running at idle speed is performed during idle speed when drivetrain is disengaged. Hereby a more accurate power demand is obtained.

According to an embodiment the method further comprises the steps of: determining a resulting engine speed development based upon said certain amount of fuel; determining the engine speed increase rate of said resulting engine speed development; and adapting the amount of fuel based upon said engine speed increase rate.

According to an embodiment a predicted engine speed development during engine start procedure is determined based upon said engine speed increase rate, wherein the amount of fuel is adapted based upon the predicted engine speed development.

By thus adapting the amount of fuel based upon said engine speed increase rate control of the engine speed development during the engine start procedure can be further improved such that a desired starting behaviour of the engine is obtained wherein the time for starting the engine, i.e. the time for reaching the engine idle speed, does not take too long, and wherein an overshoot behaviour with respect to said engine speed can be reduced/mitigated/avoided. Hereby further improvement of a starting behaviour which is repeatable may be obtained in an efficient way.

Said adaption of the amount of fuel based upon said engine speed increase rate may be performed during the engine start procedure which thus further improves the respective engine start procedure. Said adaption based upon said engine speed increase rate may also be taken into consideration together with the adaption based upon the determined actual power demand and current conditions in connection to a following engine start procedure where the certain amount of fuel chosen for injection in connection to the following injection is adapted by adding or reducing the amount of fuel for that following engine start procedure. Thus, hereby the engine speed development will be further improved in a following engine start procedure. Having repeated the adaption of amount of fuel in a few following engine start procedures the engine starting behaviour will be optimized to the desired behaviour, i.e. the engine speed development during the engine start procedures will be corresponding to the desired behaviour in order for the engine to start within a desired starting time avoiding overshoot behaviour of the engine speed. The behaviour of the particular internal combustion engine during engine start procedures will be repeatable during the life time of the engine. Certain changes in the engine with respect to ageing will be considered by performing said adaption of amount of fuel.

According to an embodiment of the method the step of adapting the amount of fuel based upon the engine speed increase rate comprises: increasing the amount of fuel if the engine speed increase rate is too low indicating that the engine speed increases too slow so that the accumulated time before engine idle speed is obtained is too long, and decreasing the amount of fuel if the engine speed increase rate is too high indicating an overshoot behaviour with respect to said engine speed. Hereby efficient adaption of amount of fuel is obtained such that the behaviour of the engine speed development during the engine start procedure corresponds to a desired starting behaviour of the engine is obtained.

According to an embodiment of the method the step of adapting the amount of fuel based upon the engine speed increase rate comprises adapting the amount of fuel for injection during the engine start procedure at a certain engine speed prior to reaching the demanded engine idle speed. By thus performing possible adaption of amount of fuel at a certain engine speed prior to reaching the demanded engine idle speed the engine start procedure can be controlled during a particular engine start procedure, thus facilitating obtaining a desired engine start time avoiding extreme overshoot behaviour of the engine speed.

According to an embodiment of the method the step of adapting the amount of fuel based upon the engine speed increase rate comprises adapting said certain amount of fuel for injection to initiate said engine start procedure in accordance with said adapted amount of fuel in a following engine start procedure. According to an embodiment the adapted amount of fuel, i.e. a certain decreased amount or a certain increased amount of fuel, determined in the previous engine start procedure is stored to be used in the following engine start procedure by adding/reducing the certain amount of fuel used in the previous starting procedure with this amount of fuel for the following engine start procedure. Hereby the engine speed development will be improved in a following engine start procedure as the amount of fuel used has been adapted to the behaviour, i.e. engine speed increase rate, of an earlier engine start procedure. Thus, the engine will have learned from an earlier engine start procedure such that an improved engine starting behaviour may be obtained, thus facilitating further reducing possible overshoot behaviour of the engine speed and improving the time for the engine speed to reach the engine idle speed and thus start of the engine. Thus, if a certain overshoot behaviour of the engine speed has been determined in an earlier engine start procedure the certain amount of fuel to be injected in this following engine start procedure is reduced in accordance with that overshoot behaviour so as to reduce/eliminate the overshoot behaviour in this engine start procedure.

According to an embodiment of the method the step of adapting the amount of fuel based upon the determined engine speed increase rate is performed in following engine start procedures. Hereby the speed development and hence the engine start behaviour will be improved and within a few engine start procedures will have reached a very good level so that the starting behaviour of the engine will be a desired starting behaviour giving a good an repeatable feeling for a vehicle operator when starting the engine of the vehicle.

Specifically an object of the invention is achieved by a system for controlling fuel injection in connection to engine start procedure. The system comprises means for choosing a certain amount of fuel for injection to initiate said engine start procedure, said chosen amount of fuel being based upon an estimated power demand for keeping said engine running at idle speed. The system further comprises means for determining, during engine idle speed of the engine start procedure after start of the engine, an actual power demand required for keeping said engine running at idle speed based upon current conditions comprising engine temperature; and means for adapting the amount of fuel based upon said determined actual power demand in a following engine start procedure.

According to an embodiment of the system the means for adapting the amount of fuel based upon said actual power demand in a following engine start procedure comprises adapting the amount of fuel to current conditions with respect to engine temperature in the following engine start. Hereby a more accurate amount of fuel may be chosen for that engine start.

According to an embodiment of the system the means for adapting the amount of fuel based upon said actual power demand in a following start taking current conditions into account comprises means for decreasing the amount of fuel if the power demand is lower than said estimated power demand, and means for increasing the amount of fuel if power demand is higher than said estimated power demand.

According to an embodiment of the system the means for storing actual power demands required for keeping said engine running at idle speed for different current conditions comprising engine temperature, the means for determining the actual power demands being arranged to determine the power demands during engine idle speed of the engine start procedure after start of the engine in connection to different engine start procedures so as to provide a basis for choosing the amount of fuel for injection to initiate following engine start procedures.

According to an embodiment of the system the means for determining an actual power demand required for keeping said engine running at idle speed is arranged to be performed during idle speed when drivetrain is disengaged.

According to an embodiment the system comprises means for determining a resulting engine speed development based upon said certain amount of fuel; means for determining the engine speed increase rate of said resulting engine speed development; and means for adapting the amount of fuel based upon said engine speed increase rate.

According to an embodiment of the system the means for adapting the amount of fuel based upon the engine speed increase rate comprises: means for increasing the amount of fuel if the engine speed increase rate is too low indicating that the engine speed increases too slow so that the accumulated time before engine idle speed is obtained is too long, and means for decreasing the amount of fuel if the engine speed increase rate is too high indicating an overshoot behaviour with respect to said engine speed.

According to an embodiment of the system the means for adapting the amount of fuel based upon the engine speed increase rate comprises adapting the amount of fuel for injection during the engine start procedure at a certain engine speed prior to reaching the demanded engine idle speed.

According to an embodiment of the system the means for adapting the amount of fuel based upon the engine speed increase rate comprises adapting said certain amount of fuel for injection to initiate said engine start procedure in accordance with said adapted amount of fuel in a following engine start procedure.

According to an embodiment of the system the means for adapting the amount of fuel based upon the determined engine speed increase rate is performed in following engine start procedures.

The system for controlling fuel injection in connection to engine start procedure 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 vehicle comprising a system according to the invention as set out herein.

Specifically an object of the invention is achieved by a computer program for controlling fuel injection in connection to engine start procedure, 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 a function of an engine start procedure according to an embodiment of the present invention; Fig. 3 schematically illustrates amount of fuel as a function of engine speed for different engine temperatures according to an embodiment of the present invention; Fig. 4 schematically illustrates the amount of fuel and engine speed development during an engine start procedure according to an exemplary embodiment of the present invention; Fig. 5 schematically illustrates a system for controlling fuel injection in connection to engine start procedure according to an embodiment of the present invention; Fig. 6 schematically illustrates a block diagram of a method for controlling fuel injection in connection to engine start procedure 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 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 “engine temperature” refers to the engine water temperature and/or engine oil temperature.

The engine according to the present invention could be any suitable internal combustion engine with any suitable number of cylinders. The internal combustion engine according to the present invention could for example be a 5-cylinder engine, a 6-cylinder engine or an 8-cylinder engine. The cylinders could be in any suitable alignment, for example inline engine or a V-engine. The internal combustion engine according to the present invention could be any supercharged internal combustion engine such as a turbocharged internal combustion engine.

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. The vehicle 1 comprises a system I for controlling fuel injection in connection to engine start procedure according to an embodiment of the present invention.

Fig. 2 schematically illustrates a function of an engine start procedure according to an embodiment of the present invention.

In a first engine start procedure a certain amount of fuel for injection to initiate said engine start procedure is chosen. The box EF is according to an embodiment set to 0 amount of fuel and the box EP1 is set to a fuel amount corresponding to a demanded power required for keeping the engine running at idle speed where current conditions such as engine temperature has been taken into account. According to an example the box EP1 has been set to an amount of fuel corresponding to a demanded power of e.g. 10 kW, the amount of fuel according to an embodiment being 100 mg.

When the engine has reached engine idle speed it is observed in box IDLE. During engine idle speed of the engine start procedure after start of the engine an actual power demand required for keeping the engine running at idle speed is determined in box EP2 taking current conditions comprising the current engine temperature into consideration. The amount of fuel based upon said actual power demand is adapted in a following engine start procedure.

The amount of fuel adapted based upon the actual power demand in a following engine start procedure comprises adapting the amount of fuel to current conditions with respect to engine temperature in the following engine start and for the engine speed of the engine start procedure.

The determined actual power demand for keeping the engine running at idle speed is adapted to the engine speeds during the engine start procedure, thus resulting in different torques which corresponds to a certain amount of fuel.

Adapting the amount of fuel based upon said actual power demand in a following start taking current conditions into account comprises decreasing the amount of fuel if the power demand is lower than the estimated power demand in a previous engine start procedure, and increasing the amount of fuel if power demand is higher than said estimated power demand in a previous engine start procedure.

The starting amount of fuel of the box START is in this example 100 mg. The engine speed increase rate of said resulting engine speed development based upon the amount of fuel used in the box START for the engine start procedure is determined in E.

If the engine speed increase rate is too low indicating that the engine speed increases too slow so that the accumulated time before engine idle speed is obtained is too long the amount of fuel is increased by means of the box RAMP wherein a certain additional amount of fuel is added, e.g. 10 mg, from the box RAMP providing a ramp function such that the additional amount is added to the box EF. This may be performed during the engine start procedure at a certain engine speed and results in a higher amount of fuel at the box Fuel for start.

For a following engine start procedure the added amount of fuel is taken into consideration such that, given the same conditions, in this example 100 10 = 110 mg of fuel is used for the following engine start procedure.

If 110 mg of fuel used as the amount of fuel in the following engine start procedure reveals an overshoot behaviour with respect to said engine speed the amount of fuel is decreased during the engine start procedure at a certain engine speed.

An overshoot behaviour may be predicted in the box OS-P by predicting the engine speed development during the start procedure. If an overshoot behaviour is predicted in OS-P the amount of fuel for injection during the engine start procedure may be reduced at a certain engine speed prior to reaching the demanded engine idle speed.

An overshoot behaviour may be determined in the box OS by determining the engine speed development during the start procedure.

For a following engine start procedure the reduced amount of fuel is taken into consideration such that an amount of fuel lower than 110 mg is used by reducing that amount with the thus determined amount causing said overshoot behaviour of the engine speed.

Fig. 3 schematically illustrates amount of fuel as a function of engine speed for different engine temperatures according to an embodiment of the present invention.

In this example a certain amount of fuel is chosen for a first engine start procedure taking current engine temperature into account. The chosen amount of fuel is according to an embodiment based upon an estimated power demand for keeping said engine running at idle speed. Thus, for a relatively low engine temperature illustrated with a dotted line in fig. 3, where a low temperature according to a certain situation could e.g. be below zero degrees, a relatively higher amount of fuel is chosen. For a relatively high engine temperature illustrated with a chain line in fig. 3, where a high temperature according to a situation could be above e.g. 100 degrees, a relatively lower amount of fuel is chosen.

The amount of fuel is adapted based upon the engine speed increase rate during the engine start procedure at a certain engine speed prior to reaching the demanded engine idle speed. In this case the engine speed increase rate has been determined to be too high indicating an overshoot behaviour with respect to said engine speed, wherein, at a certain engine speed, e.g. about 50 rpm before reaching idle speed, the amount of fuel is decreased so as to reduced/mitigate/eliminate the overshoot behaviour in connection to reaching the idle speed. This is illustrated with the dotted vertical line with “adapted” in fig. 3. By thus performing possible adaption of amount of fuel at a certain engine speed prior to reaching the demanded engine idle speed the engine start procedure can be controlled during a particular engine start procedure, thus facilitating obtaining a desired engine start time avoiding extreme overshoot behaviour of the engine speed.

Fig. 4 schematically illustrates the amount of fuel and engine speed development during an engine start procedure according to an exemplary embodiment of the present invention.

In this example in which the fuel injection in connection to engine start procedure is controlled in accordance with an embodiment of the present invention a certain amount of fuel for injection to initiate engine start procedure has been chosen as can be seen in the upper graph of fig. 4 illustrating the amount of fuel during the engine start procedure. The chosen amount of fuel is according to an embodiment based upon an estimated power demand for keeping said engine running at idle speed. A resulting engine speed development is determined based upon said certain amount of fuel.

The engine speed increase rate of said resulting engine speed development is also determined. A predicted engine speed development is determined based upon the engine speed increase rate. The predicted engine speed development is illustrated as a dotted line and the actual engine speed development is illustrated as a solid line in the lower graph of fig. 4. The predicted engine speed development predicts an overshoot behaviour of the engine speed development in connection to reaching the idle speed. In order to reduce/limit/eliminate the overshoot behaviour the amount of fuel is adapted, i.e. in this case reduced, based upon said engine speed increase rate, i.e. based upon the predicted overshoot behaviour of the engine speed development. The reduction of fuel is performed a certain time before the idle speed has been reached by means of a controlled decrease of fuel amount as shown in fig. 4.

Hereby the overshoot behaviour of the engine speed development is reduced as can be seen in the lower graph illustrating the actual engine speed development as a result of the reduction of fuel.

During engine idle speed of the engine start procedure after start of the engine determining the actual power demand required for keeping the engine running at idle speed based upon current conditions comprising engine temperature is determined. In a following engine start procedure the amount of fuel is adapted based upon said determined actual power taking current conditions with respect to engine temperature in that following engine start into consideration.

Fig. 5 schematically illustrates a system I for controlling fuel injection in connection to engine start procedure according to an embodiment of the present invention.

The system I comprises an electronic control unit 100.

The system I comprises means 110 for choosing a certain amount of fuel for injection to initiate said engine start procedure. The means 110 for choosing a certain amount of fuel is configured to taking current conditions into account comprising current engine conditions comprising current engine temperature and whether the engine is being started from a cold condition or a relatively warm condition such as relatively shortly after having been used. The means 110 for choosing a certain amount of fuel is, where applicable, configured to take an adaption of fuel performed in an earlier engine start procedure into account.

The means 110 for choosing a certain amount of fuel comprises means 112 for determining the current engine temperature. The means 110 for choosing a certain amount of fuel comprises means 114 for determining the demanded power demand required for keeping said engine running at idle speed based upon current conditions comprising said engine temperature and may further comprise torque loss. A first certain amount of fuel chosen for a first engine start procedure is according to an embodiment chosen based upon the demanded power demand required for keeping said engine running at idle speed based upon.

The system I further comprises means 160 for determining, during engine idle speed of the engine start procedure after start of the engine, an actual power demand required for keeping said engine running at idle speed based upon the current engine temperature. The means 160 for determining an actual power demand required for keeping said engine running at idle speed based upon the current engine temperature comprises means 162 for determining the current engine temperature. The means 162 may be comprised in or comprise the means 112. The means 160 for determining an actual power demand required for keeping said engine running at idle speed comprises using predetermined data for demanded power for certain engine temperatures.

The system I further comprises means 170 for adapting the amount of fuel based upon said determined actual power demand in a following engine start procedure.

The means 170 for adapting the amount of fuel based upon said actual power demand in a following engine start procedure comprises adapting the amount of fuel to current conditions with respect to engine temperature in the following engine start.

The means 170 for adapting the amount of fuel based upon said actual power demand in a following start taking current conditions into account comprises means 172 for decreasing the amount of fuel if the power demand is lower than said estimated power demand The means 170 for adapting the amount of fuel based upon said actual power demand in a following start taking current conditions into account comprises means 174 for increasing the amount of fuel if power demand is higher than said estimated power demand.

The determined actual power demand for keeping the engine running at idle speed is arranged to be adapted to the engine speeds during an engine start procedure, thus resulting in different torques which corresponds to a certain amount of fuel. This certain amount of fuel is adapted taking current conditions comprising engine temperature into consideration.

The means 170 for adapting the amount of fuel based upon said actual power demand in a following engine start procedure comprises adapting the amount of fuel based upon an adaption of determined actual power demand for keeping the engine running at idle speed to the engine speeds during the engine start procedure.

The system I comprises according to an embodiment means 190 for adapting the determined actual power demand for keeping the engine running at a certain idle speed to the engine speeds during the engine start procedure.

Adapting the determined actual power demand for keeping the engine running at idle speed the engine speeds during the engine start procedure, i.e. the engine speed development during the engine start development, results in different torques which corresponds to a certain amount of fuel. Adapting the amount of fuel based upon said determined actual power demand required for keeping said engine running at a certain idle speed in a following engine start procedure is thus performed where the determined actual power demand for keeping the engine running at idle speed has been adapted to the engine speeds during the engine start procedure.

The system I further comprises means 180 for storing actual power demands required for keeping said engine running at idle speed for different current conditions comprising engine temperature. The means 160 for determining the actual power demands is arranged to determine the power demands during engine idle speed of the engine start procedure after start of the engine in connection to different engine start procedures so as to provide a basis for choosing the amount of fuel for injection to initiate following engine start procedures.

The means 180 for storing actual power demands comprises according to an embodiment internal storage means on board the vehicle. The internal storage means may be any suitable means for storing information such as a control unit, a computer or the like. The internal storage means is according to an embodiment comprised in the electronic control unit 100.

The means 180 for storing actual power demands comprises according to an embodiment external storage means external to the vehicle. The external storage means may be any suitable external storage means such as a sever unit, a personal computer, a tablet, a so called cloud-storage, a laptop and/or a smartphone or the like.

By thus storing actual power demands required for keeping said engine running at idle speed for different current conditions comprising engine temperature, the power demand required for keeping the engine running at idle speed for the current condition of an engine start may be stored and made available for that start such that the adaptation of the amount of fuel can be made based upon a power demand determined for such conditions, the conditions comprising engine temperature.

The system I comprises means 120 for determining a resulting engine speed development based upon said certain amount of fuel.

The means 120 for determining a resulting engine speed development based upon said certain amount of fuel may comprise any suitable detector unit for detecting the engine speed development during engine start procedure.

The system I comprises means 130 for determining the engine speed increase rate of said resulting engine speed development.

The means 130 for determining the engine speed increase rate may comprise any suitable means for determining the engine speed increase rate based upon said engine speed development. The means 130 comprises a calculation unit for calculating the engine speed increase rate based upon the engine speed development during the engine start procedure. The means 130 may be comprised in the electronic control unit 100.

The system I comprises means 140 for adapting the amount of fuel based upon said engine speed increase rate.

The means 140 for adapting the amount of fuel based upon said engine speed increase rate comprises according to an embodiment means 140a for determining a predicted engine speed development during the engine start procedure. The means 140a for determining a predicted engine speed development during the engine start procedure may comprise any suitable means for predicting an engine speed development. The means 140a for determining a predicted engine speed development comprises according to an embodiment said electronic control unit 100.

The means 140 for adapting the amount of fuel based upon the engine speed increase rate comprises means 142 for increasing the amount of fuel if the engine speed increase rate is too low indicating that the engine speed increases too slow so that the accumulated time before engine idle speed is obtained is too long. The means 142 for increasing the amount of fuel comprises according to an embodiment fuel injections means comprising a fuel injector of the engine, the fuel injector being arranged to increase the amount injected.

The means 140 for adapting the amount of fuel based upon the engine speed increase rate comprises means 144 for decreasing the amount of fuel if the engine speed increase rate is too high indicating an overshoot behaviour with respect to said engine speed. The means 144 for decreasing the amount of fuel comprises according to an embodiment fuel injections means comprising a fuel injector of the engine, the fuel injector being arranged to decrease/stop the amount injected.

The means 140 for adapting the amount of fuel based upon the engine speed increase rate comprises adapting the amount of fuel for injection during the engine start procedure at a certain engine speed prior to reaching the demanded engine idle speed. The means 140 for adapting the amount of fuel based upon the engine speed increase rate comprises according to an embodiment determining whether the predicted engine speed development during the engine start procedure is predicted to result in an overshoot or is predicted to result in the accumulated time before engine idle speed is obtained will be too long.

The means 140 for adapting the amount of fuel based upon the engine speed increase rate comprises adapting said certain amount of fuel for injection to initiate said engine start procedure in accordance with said adapted amount of fuel in a following engine start procedure. The means 140 for adapting the amount of fuel based upon the engine speed increase rate comprises adapting said certain amount of fuel for injection to initiate said engine start procedure in accordance with said adapted amount of fuel in a following engine start procedure comprises adding or reducing the certain amount of fuel used in a previous starting procedure with the determined amount of fuel with which the fuel is intended to be adapted for the following engine start procedure.

The system I comprises according to an embodiment means 150 for storing the adapted amount of fuel, i.e. a certain decreased amount or a certain increased amount of fuel, determined in a previous engine start procedure to be used in the following engine start procedure by adding/reducing the certain amount of fuel used in the previous starting procedure with this amount of fuel for the following engine start procedure.

The means 140 for adapting the amount of fuel based upon the determined engine speed increase rate is performed in following engine start procedures.

The electronic control unit 100 is operably connected to the means 110 for choosing a certain amount of fuel for injection to initiate said engine start procedure via a link 10a. The electronic control unit 100 is via the link 10a arranged to send a signal to said means 110 representing data for amount of fuel comprising data for current conditions and possible data for earlier engine start procedure comprising data for adapted amount of fuel in earlier engine start procedure.

The electronic control unit 100 is operably connected to the means 110 for choosing a certain amount of fuel for injection to initiate said engine start procedure via a link 10b. The electronic control unit 100 is via the link 10b arranged to receive a signal from said means 110 representing data for chosen amount of fuel.

The electronic control unit 100 is operably connected to the means 112 for determining the current engine temperature via a link 12. The electronic control unit 100 is via the link 12 arranged to receive a signal from said means 112 representing data for current engine temperature.

The electronic control unit 100 is operably connected to the means 114 for determining the demanded power demand required for keeping said engine running at idle speed based upon said engine temperature via a link 14a. The electronic control unit 100 is via the link 14a arranged to send a signal to said means 114a representing data for current engine temperature.

The electronic control unit 100 is operably connected to the means 114 for determining the demanded power demand required for keeping said engine running at idle speed based upon said engine temperature via a link 14b. The electronic control unit 100 is via the link 14b arranged to receive a signal from said means 114b representing data for demanded power demand required for keeping said engine running at idle speed based upon said engine temperature.

The electronic control unit 100 is operably connected to the means 160 for determining, during engine idle speed of the engine start procedure after start of the engine, an actual power demand required for keeping said engine running at idle speed based upon the current engine temperature via a link 60a. The electronic control unit 100 is via the link 60a arranged to send a signal to said means 160 representing data for current conditions comprising engine temperature.

The electronic control unit 100 is operably connected to the means 160 for determining, during engine idle speed of the engine start procedure after start of the engine, an actual power demand required for keeping said engine running at idle speed based upon current conditions comprising engine temperature via a link 60b. The electronic control unit 100 is via the link 60b arranged to receive a signal from said means 160 representing data for actual power demand required for keeping said engine running at idle speed.

The electronic control unit 100 is operably connected to the means 162 for determining the current engine temperature via a link 62. The electronic control unit 100 is via the link 62 arranged to receive a signal from said means 162 representing data for current engine temperature.

The electronic control unit 100 is operably connected to the means 170 for adapting the amount of fuel for keeping said engine running at idle speed based upon said actual power demand via a link 70a. The electronic control unit 100 is via the link 70a arranged to send a signal to said means 170 representing data for actual power demand.

The electronic control unit 100 is operably connected to the means 170 for adapting the amount of fuel for keeping said engine running at idle speed based upon said actual power demand via a link 70b. The electronic control unit 100 is via the link 70b arranged to receive a signal from said means 170 representing data for adapting the amount of fuel.

The electronic control unit 100 is operably connected to the means 190 for adapting the determined actual power demand for keeping the engine running at a certain idle speed to the engine speeds during the engine start procedure via a link 90a. The electronic control unit 100 is via the link 90a arranged to send a signal to said means 190 representing data for determined actual power at a certain idle speed and data for engine speeds during the engine start procedure.

The electronic control unit 100 is operably connected to the means 190 for adapting the determined actual power demand for keeping the engine running at a certain idle speed to the engine speeds during the engine start procedure via a link 90b. The electronic control unit 100 is via the link 90b arranged to receive a signal from said means 190 representing data for adapted actual power demand.

The electronic control unit 100 is operably connected to the means 180 for storing actual power demands required for keeping said engine running at idle speed for different current conditions comprising engine temperature via a link 80a. The electronic control unit 100 is via the link 80a arranged to send a signal to said means 180 representing data determined actual power demands required for keeping said engine running at idle speed for different current conditions comprising engine temperature.

The electronic control unit 100 is operably connected to the means 180 for storing actual power demands required for keeping said engine running at idle speed for different current conditions comprising engine temperature via a link 80b. The electronic control unit 100 is via the link 80b arranged to receive a signal from said means 180 representing data for actual power demand for current condition comprising engine temperature.

The electronic control unit 100 is operably connected to the means 120 for determining a resulting engine speed development based upon said certain amount of fuel via a link 20. The electronic control unit 100 is via the link 20 arranged to receive a signal from said means 120 representing data for engine speed during the engine start procedure.

The electronic control unit 100 is operably connected to the means 130 for determining the engine speed increase rate of said resulting engine speed development via a link 30a. The electronic control unit 100 is via the link 30a arranged to send a signal to said means 130 representing data for engine speed during the engine start procedure.

The electronic control unit 100 is operably connected to the means 130 for determining the engine speed increase rate of said resulting engine speed development via a link 30b. The electronic control unit 100 is via the link 14b arranged to receive a signal from said means 30b representing data for demanded power demand required for keeping said engine running at idle engine speed increase rate.

The electronic control unit 100 is operably connected to the means 140a for determining a predicted engine speed development rate via a link 40a-1. The electronic control unit 100 is via the link 40a-1 arranged to send a signal to said means 140a representing data for engine speed increase rate.

The electronic control unit 100 is operably connected to the means 140a for determining a predicted engine speed development via a link 40a-2. The electronic control unit 100 is via the link 40a-2 arranged to receive a signal from said means 140a representing data for predicted engine speed development.

The electronic control unit 100 is operably connected to the means 140 for adapting the amount of fuel based upon said engine speed increase rate via a link 40-1. The electronic control unit 100 is via the link 40-1 arranged to send a signal to said means 140 representing data for engine speed increase rate and/or data for predicted engine speed development.

The electronic control unit 100 is operably connected to the means 140 for adapting the amount of fuel based upon said engine speed increase rate via a link 40-2. The electronic control unit 100 is via the link 40-2 arranged to receive a signal from said means 140 representing data for adapting the amount of fuel.

The electronic control unit 100 is operably connected to the means 142 for increasing the amount of fuel if the engine speed increase rate is too low indicating that the engine speed increases too slow so that the accumulated time before engine idle speed is obtained is too long via a link 42a. The electronic control unit 100 is via the link 42a arranged to send a signal to said means 142 representing data for engine speed increase rate and/or data for predicted engine speed development.

The electronic control unit 100 is operably connected to the means 142 for increasing the amount of fuel if the engine speed increase rate is too low indicating that the engine speed increases too slow so that the accumulated time before engine idle speed is obtained is too long via a link 42b. The electronic control unit 100 is via the link 42b arranged to receive a signal from said means 142 representing data for increasing the amount of fuel.

The electronic control unit 100 is operably connected to the means 144 for decreasing the amount of fuel if the engine speed increase rate is too high indicating an overshoot behaviour with respect to said engine speed via a link 44a. The electronic control unit 100 is via the link 44a arranged to send a signal to said means 144 representing data for engine speed increase rate and/or data for predicted engine speed development.

The electronic control unit 100 is operably connected to the means 144 for decreasing the amount of fuel if the engine speed increase rate is too high indicating an overshoot behaviour with respect to said engine speed via a link 44b. The electronic control unit 100 is via the link 44b arranged to receive a signal from said means 142 representing data for decreasing the amount of fuel.

The electronic control unit 100 is operably connected to the means 150 for storing the adapted amount of fuel determined in a previous engine start procedure via a link 50a. The electronic control unit 100 is via the link 50a arranged to send a signal to said means 150 representing data for adapted amount of fuel determined in a previous engine start procedure.

The electronic control unit 100 is operably connected to the means 150 for storing the adapted amount of fuel determined in a previous engine start procedure via a link 50b. The electronic control unit 100 is via the link 50b arranged to receive a signal from said means 150 representing data for adapted amount of fuel to be used in a following engine start procedure.

Fig. 6 schematically illustrates a block diagram of a method for controlling fuel injection in connection to engine start procedure according to an embodiment of the present invention.

According to the embodiment the method for controlling fuel injection in connection to engine start procedure according to an embodiment of the present invention comprises a step S1. In this step a certain amount of fuel for injection to initiate said engine start procedure is chosen, said chosen amount of fuel being based upon an estimated power demand for keeping said engine running at idle speed.

According to the embodiment the method for controlling fuel injection in connection to engine start procedure according to an embodiment of the present invention comprises a step S2. In this step an actual power demand required for keeping said engine running at idle speed is determined during engine idle speed of the engine start procedure after start of the engine based upon current conditions comprising engine temperature.

According to the embodiment the method for controlling fuel injection in connection to engine start procedure according to an embodiment of the present invention comprises a step S3. In this step the amount of fuel is adapted based upon said determined actual power demand in a following engine start procedure.

By thus adapting the amount of fuel based upon said determined actual power demand in a following engine start procedure control of engine start procedures are improved. By thus adapting the amount of fuel based upon said determined actual power demand in a following engine start procedure a good basis for choosing a suitable amount of fuel in a following engine start is obtained. Hereby control of the engine start so as to obtain a desired start behaviour of the engine is improved in following engine start procedures. Hereby a starting behaviour which is repeatable may be obtained in an efficient way. Having repeated the adaption of amount of fuel in a few following engine start procedures the engine starting behaviour will be optimized to the desired behaviour, i.e. the engine speed development during the engine start procedures will be repeatable. The behaviour of the particular internal combustion engine during engine start procedures will be repeatable during the life time of the engine. Certain changes in the engine with respect to ageing will be considered by performing said adaption of amount of fuel.

According to an embodiment of the method the step of adapting the amount of fuel based upon said actual power demand in a following start taking current conditions into account comprises: decreasing the amount of fuel if the power demand is lower than said estimated power demand, and increasing the amount of fuel if power demand is higher than said estimated power demand.

According to an embodiment of the method the step of determining an actual power demand required for keeping said engine running at idle speed is performed during idle speed when drivetrain is disengaged.

According to an embodiment of the method the step of adapting the amount of fuel based upon the engine speed increase rate comprises: increasing the amount of fuel if the engine speed increase rate is too low indicating that the engine speed increases too slow so that the accumulated time before engine idle speed is obtained is too long, and decreasing the amount of fuel if the engine speed increase rate is too high indicating an overshoot behaviour with respect to said engine speed.

According to an embodiment of the method the step of adapting the amount of fuel based upon the engine speed increase rate comprises adapting said certain amount of fuel for injection to initiate said engine start procedure in accordance with said adapted amount of fuel in a following engine start procedure. According to an embodiment the adapted amount of fuel, i.e. a certain decreased amount or a certain increased amount of fuel, determined in the previous engine start procedure is stored to be used in the following engine start procedure by adding/reducing the certain amount of fuel used in the previous starting procedure with this amount of fuel for the following engine start procedure.

With reference to figure 7, a diagram of an apparatus 500 is shown. The system I described with reference to fig. 5 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 controlling fuel injection in connection to engine start procedure.

The program P comprises routines for during engine idle speed of the engine start procedure after start of the engine determining an actual power demand required for keeping said engine running at idle speed based upon current conditions comprising engine temperature. The program P comprises routines for adapting the amount of fuel based upon said determined actual power demand in a following engine start procedure. The routines for adapting the amount of fuel based upon said determined actual power demand in a following engine start procedure comprises routines for adapting the amount of fuel to current conditions with respect to engine temperature in the following engine start. The routines for adapting the amount of fuel based upon said determined actual power demand in a following engine start procedure taking current conditions into account comprises routines for decreasing the amount of fuel if the power demand is lower than said estimated power demand, and comprises routines for increasing the amount of fuel if power demand is higher than said estimated power demand. The program P comprises routines for storing actual power demands required for keeping said engine running at idle speed for different current conditions comprising engine temperature, the actual power demands being determined during engine idle speed of the engine start procedure after start of the engine in connection to different engine start procedures so as to provide a basis for choosing the amount of fuel for injection to initiate following engine start procedures. The program P comprises routines for choosing a certain amount of fuel for injection to initiate said engine start procedure. The program P comprises routines for determining a resulting engine speed development based upon said certain amount of fuel. The program P comprises routines for determining the engine speed increase rate of said resulting engine speed development. The program P comprises routines for adapting the amount of fuel based upon said engine speed increase rate. The routines for adapting the amount of fuel based upon the engine speed increase rate comprises routines for adapting the amount of fuel for injection during the engine start procedure at a certain engine speed prior to reaching the demanded engine idle speed. The routines for adapting the amount of fuel based upon the engine speed increase rate comprises routines for adapting said certain amount of fuel for injection to initiate said engine start procedure in accordance with said adapted amount of fuel in a following engine start procedure taking current conditions comprising engine temperature into account. 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 choosing a certain amount of fuel for injection to initiate said engine start procedure, said chosen amount of fuel being based upon an estimated power demand for keeping said engine running at idle speed. The signals received on data port 599 can be used by apparatus 500 for during engine idle speed of the engine start procedure after start of the engine determining an actual power demand required for keeping said engine running at idle speed based upon current conditions comprising engine temperature. The signals received on data port 599 can be used by apparatus 500 for adapting the amount of fuel based upon said determined actual power demand in a following engine start procedure. The signals used for adapting the amount of fuel based upon said determined actual power demand in a following engine start procedure are used for adapting the amount of fuel to current conditions with respect to engine temperature in the following engine start. The signals used for adapting the amount of fuel based upon said determined actual power demand in a following engine start procedure taking current conditions into account are used for decreasing the amount of fuel if the power demand is lower than said estimated power demand, and are used for increasing the amount of fuel if power demand is higher than said estimated power demand. The signals received on data port 599 can be used by apparatus 500 for storing actual power demands required for keeping said engine running at idle speed for different current conditions comprising engine temperature, the actual power demands being determined during engine idle speed of the engine start procedure after start of the engine in connection to different engine start procedures so as to provide a basis for choosing the amount of fuel for injection to initiate following engine start procedures. The signals received on data port 599 can be used by apparatus 500 for determining a resulting engine speed development based upon said certain amount of fuel. The signals received on data port 599 can be used by apparatus 500 for determining the engine speed increase rate of said resulting engine speed development. The signals received on data port 599 can be used by apparatus 500 for adapting the amount of fuel based upon said engine speed increase rate. The signals used for adapting the amount of fuel based upon the engine speed increase rate are used for adapting the amount of fuel for injection during the engine start procedure at a certain engine speed prior to reaching the demanded engine idle speed. The signals used for adapting the amount of fuel based upon the engine speed increase rate are used for adapting said certain amount of fuel for injection to initiate said engine start procedure in accordance with said adapted amount of fuel in a following engine start procedure taking current conditions comprising engine temperature into account.

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 controlling fuel injection in connection to engine start procedure, comprising the steps of: choosing (S1) a certain amount of fuel for injection to initiate said engine start procedure; characterized in that said chosen amount of fuel is based upon an estimated power demand for keeping said engine running at idle speed, the method further comprising the steps of: - during engine idle speed of the engine start procedure after start of the engine determining (S2) an actual power demand required for keeping said engine running at idle speed based upon current conditions comprising engine temperature; - adapting (S3) the amount of fuel based upon said determined actual power demand in a following engine start procedure.

2. A method according to claim 1, wherein the step of adapting the amount of fuel based upon said actual power demand in a following engine start procedure comprises the step of adapting the amount of fuel to current conditions with respect to engine temperature in the following engine start.

3. A method according to claim 1 or 2, wherein the step of adapting the amount of fuel based upon said actual power demand in a following start taking current conditions into account comprises: decreasing the amount of fuel if the power demand is lower than said estimated power demand, and increasing the amount of fuel if power demand is higher than said estimated power demand.

4. A method according to any of claims 1-3, comprising the step of storing actual power demands required for keeping said engine running at idle speed for different current conditions comprising engine temperature, the actual power demands being determined during engine idle speed of the engine start procedure after start of the engine in connection to different engine start procedures so as to provide a basis for choosing the amount of fuel for injection to initiate following engine start procedures.

5. A method according to any of claims 1-4, wherein the step of determining an actual power demand required for keeping said engine running at idle speed is performed during idle speed when drivetrain is disengaged.

6. A method according to any of claims 1-5, comprising the steps of: - determining a resulting engine speed development during the engine start procedure based upon said certain amount of fuel; - determining the engine speed increase rate of said resulting engine speed development; and - adapting the amount of fuel based upon said engine speed increase rate.

7. A method according to claim 6, wherein the step of adapting the amount of fuel based upon the engine speed increase rate comprises: increasing the amount of fuel if the engine speed increase rate is too low indicating that the engine speed increases too slow so that the accumulated time before engine idle speed is obtained is too long, and decreasing the amount of fuel if the engine speed increase rate is too high indicating an overshoot behaviour with respect to said engine speed.

8. A method according to claim 6 or 7, wherein the step of adapting the amount of fuel based upon the engine speed increase rate comprises adapting the amount of fuel for injection during the engine start procedure at a certain engine speed prior to reaching the demanded engine idle speed.

9. A method according to any of claims 6-8, wherein the step of adapting the amount of fuel based upon the engine speed increase rate comprises adapting said certain amount of fuel for injection to initiate said engine start procedure in accordance with said adapted amount of fuel in a following engine start procedure taking current conditions comprising engine temperature into account.

10. A system (I) for controlling fuel injection in connection to engine start procedure, comprising means (110) for choosing a certain amount of fuel for injection to initiate said engine start procedure; characterized in that said chosen amount of fuel is based upon an estimated power demand for keeping said engine running at idle speed, the system further comprising means (160) for determining, during engine idle speed of the engine start procedure after start of the engine, an actual power demand required for keeping said engine running at idle speed based upon current conditions comprising engine temperature; and means (170) for adapting the amount of fuel based upon said determined actual power demand in a following engine start procedure.

11. A system according to claim 10, wherein the means (170) for adapting the amount of fuel based upon said actual power demand in a following engine start procedure comprises the step of adapting the amount of fuel to current conditions with respect to engine temperature in the following engine start.

12. A system according to claim 10 or 11, wherein the means (170) for adapting the amount of fuel based upon said actual power demand in a following start taking current conditions into account comprises means (172) for decreasing the amount of fuel if the power demand is lower than said estimated power demand, and means (174) for increasing the amount of fuel if power demand is higher than said estimated power demand.

13. A system according to any of claims 10-12, means (180) for storing actual power demands required for keeping said engine running at idle speed for different current conditions comprising engine temperature, the means (160) for determining the actual power demands being arranged to determine the power demands during engine idle speed of the engine start procedure after start of the engine in connection to different engine start procedures so as to provide a basis for choosing the amount of fuel for injection to initiate following engine start procedures.

14. A system according to any of claims 10-13, wherein the means (160) for determining an actual power demand required for keeping said engine running at idle speed is arranged to be performed during idle speed when drivetrain is disengaged.

15. A system according to any of claims 10-14, comprising means (120) for determining a resulting engine speed development based upon said certain amount of fuel; means (130) for determining the engine speed increase rate of said resulting engine speed development; and means (140) for adapting the amount of fuel based upon said engine speed increase rate.

16. A system according to claim 15, wherein the means (140) for adapting the amount of fuel based upon the engine speed increase rate comprises: means (142) for increasing the amount of fuel if the engine speed increase rate is too low indicating that the engine speed increases too slow so that the accumulated time before engine idle speed is obtained is too long, and means (144) for decreasing the amount of fuel if the engine speed increase rate is too high indicating an overshoot behaviour with respect to said engine speed.

17. A system according to claim 15 or 16, wherein the means (140) for adapting the amount of fuel based upon the engine speed increase rate comprises adapting the amount of fuel for injection during the engine start procedure at a certain engine speed prior to reaching the demanded engine idle speed.

18. A system according to any of claims 15-17, , wherein the means (140) for adapting the amount of fuel based upon the engine speed increase rate comprises adapting said certain amount of fuel for injection to initiate said engine start procedure in accordance with said adapted amount of fuel in a following engine start procedure.

19. A vehicle (1) comprising a system (I) according to any of claims 10-18.

20. A computer program (P) for, 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 1-9.

21. A computer program product comprising a digital storage medium storing the computer program according to claim 20.