EP2959143A1

EP2959143A1 - Method for the correction of a fuel quantity injected by means of a fuel injection device during operation of an internal combustion engine

Info

Publication number: EP2959143A1
Application number: EP14702188.5A
Authority: EP
Inventors: Andreas Flohr; Francois Layec
Original assignee: MTU Friedrichshafen GmbH
Current assignee: Rolls Royce Solutions GmbH
Priority date: 2013-02-07
Filing date: 2014-01-23
Publication date: 2015-12-30
Also published as: DE102013202038B3; US9982620B2; US20150377167A1; HK1215724A1; WO2014121896A1; CN104968921B; CN104968921A

Abstract

The invention relates to a method for the correction of a fuel quantity injected by means of a fuel injection device during operation of an internal combustion engine, said method having the following steps: determination of at least one air heat characteristic variable, on which an air heat stream (3;Q_L) fed to at least one combustion chamber (1) of the internal combustion engine functionally depends; determination of at least one exhaust heat characteristic variable, on which an exhaust heat stream (9;QA) discharged from the at least one combustion chamber (1) functionally depends; determination of a heat distribution factor (x), which specifies a fraction of the exhaust heat stream (9;QA) reduced by the air heat stream (3;QL) in relation to a heat stream (5) fed with the injected fuel to the at least one combustion chamber (1); calculation of a fuel mass (mbr) fed to the internal combustion engine from the at least one air heat characteristic variable, the at least one exhaust heat characteristic variable and the heat distribution factor (x); calculation of a comparison variable by comparison of the calculated fuel mass (mbr) with a fuel mass setpoint value (ms) and adaptation of an actuation of the fuel injection device depending on a value of the comparison variable.

Description

Method for correcting a fuel quantity injected by means of a fuel injection device during operation of an internal combustion engine

The invention relates to a method for correcting a means of a

Fuel injector injected fuel quantity in the operation of a

Internal combustion engine according to claim 1.

Method of the type discussed here are known.

In internal combustion engines having at least one fuel injector for injecting fuel into at least one combustion chamber of the internal combustion engine, parameters for driving the fuel injector are typically tuned to conditions in a new condition.

Especially due to wear or cavitation in the area of

Fuel injection device, it is possible that are injected with increasing operating time of the internal combustion engine to high fuel quantities. This is problematic because exhaust gas values, in particular upper limits for soot emission, can no longer be met. Also, this increases the fuel consumption of the internal combustion engine. It is possible to pre-commission the first

Internal combustion engine in a motor control unit to deposit a calibration curve, which anticipates the change in the injected amount of fuel over time and changed the control of the fuel injection device accordingly depending on the operating time. This has the disadvantage that the parameters for controlling the fuel injection device are also changed when in fact no excessive amounts of fuel are injected. Alternatively, it is known, consuming procedures by means of targeted quantity variations of the injected fuel quantity and observation of a resulting rotational irregularity to determine the actual amount of fuel injected and to calculate a corresponding To carry out correction. Also, methods are known in which complex models of the fuel injection device are used, wherein the injected amounts of fuel in particular by detecting a storage pressure for the

be corrected fuel to be injected. Overall, these solutions are very complicated and complicated.

From the German patent application DE 10 2010 035 026 A1 is a method for correcting a injected by means of a fuel injection device

Fuel quantity in an internal combustion engine forth, in which a temperature of the exhaust gas of the internal combustion engine is measured and a reference temperature of the exhaust gas is calculated by means of a temperature model. The measured and the calculated temperature are charged, whereby the calculation of a

Temperature difference, which is used to determine a correction amount of injected fuel. This method is complicated because it uses a complicated temperature model, and in particular, the inclusion of a large number of correction variables is necessary.

The invention is therefore based on the object to provide a method which allows a simple and rapid correction of the injected amount of fuel in the operation of an internal combustion engine.

The object is achieved by providing a method with the steps of claim 1. Here, a Luftwärmekenngröße is determined by the one

Air heat flow, which is supplied to at least one combustion chamber of the internal combustion engine, functionally dependent. At least one exhaust gas heat variable is determined, of which one exhaust heat flow, which of the at least one

Combustion chamber is discharged, functionally dependent. Under a functional dependence is both in terms of the air heat flow and in terms of

Exhaust heat flow to understand that a relationship between each

Heat flow and the respective characteristic is such that a mathematical function can be specified, which describes the heat flow as a function of the parameter. A heat distribution factor is determined that reduces a fraction of the exhaust heat flow by the air heat flow divided by one

Heat flow indicates which of the combustion chamber is supplied with the injected fuel, thus a fuel mass flow supplied to the combustion chamber. It is in particular the given by the calorific value, by chemical reaction in the combustion chamber releasable amount of heat of the injected fuel addressed. In contrast, it is possible to neglect the comparatively small amount of heat resulting from the temperature of the injected fuel and its heat capacity. One of the internal combustion engine supplied fuel mass is from the at least one air heat characteristic, the at least one

Exhaust gas heat quantity and the heat distribution factor calculated. A comparison amount calculated by comparing the calculated fuel mass with a target fuel mass target value is calculated. Finally, a control of the fuel injection device is adjusted as a function of a value of the comparison variable.

The method is based on a comparatively simple consideration of the heat flows through the at least one combustion chamber of the internal combustion engine. It will

assumed that heat is supplied to the combustion chamber substantially in two ways, namely by the supplied combustion air, which has a certain heat capacity and a certain temperature, and thus a certain heat content, and the chemical energy of the injected fuel, wherein the heat flow supplied here from the product of the per unit time supplied

Fuel quantity and the calorific value of the fuel results. Heat or power is dissipated from the at least one combustion chamber essentially by three mechanisms: a first mechanism relates to the mechanical work performed by the combustion chamber. A second mechanism addresses the amount of heat that is removed with an exhaust gas mass flow from the combustion chamber, wherein the exhaust gas has a certain heat capacity and a certain temperature, and thus a certain heat content. Finally, a third mechanism suggests that heat is removed from the combustion chamber by cooling, heat radiation and convection. It is now assumed that the percentage distribution of the heat flows in any case does not change at a given load point of the internal combustion engine, even if the actually injected fuel quantity is changed by aging. It is therefore possible to provide a heat distribution factor whose value is independent of an aging change of the injected fuel amount, and which indicates the ratio of the amount of heat discharged with the exhaust gas and reduced by the amount of heat supplied to the combustion air to the amount of heat supplied by the fuel. The exhaust heat flow and the air heat flow can be specified as a function of the at least one air heat parameter or the at least one exhaust heat parameter. The heat flow, which results from the injected fuel, can be used as a function of the

Fuel mass flow or the injected fuel mass are expressed. Overall, it is thus possible to establish a functional relationship between the injected fuel mass as a function of the

Specify the air thermal parameter, the exhaust gas heat parameter and the heat distribution factor. By means of this functional relationship, it is possible to calculate the injected fuel mass if a value for the distribution factor is assumed, and if the values of the at least one air thermal parameter and the

Exhaust gas heat quantity are known. By comparing the calculated

Fuel mass with the fuel mass setpoint, it is then readily possible to obtain a comparison, on the basis of the control of the

Fuel injector can be corrected, in particular a

compensate for age-related change in the injected fuel quantity. The

Method is relatively easy and fast to perform, with only a few sizes to be known or accepted. Also, the calculations underlying the method are simple and fast

perform.

Preferably, the method is performed by a control unit of the internal combustion engine or is implemented in such. The air heat parameter and the exhaust gas heat variable are preferably measured by suitable sensors for this purpose, which particularly preferably with the control unit for transmitting the

Measured values are operatively connected. The heat distribution factor is preferably stored in the control unit, wherein at least one stored value for the heat distribution factor is used to calculate the injected fuel quantity.

A method is preferred which is characterized in that a first

Air thermal parameter is determined by a combustion air temperature is measured. The term combustion air temperature refers to the temperature of an air mass flow which is supplied to the at least one combustion chamber. It is obvious that the air heat flow functionally depends on the combustion air temperature. Preferably, a second air heat parameter is determined by a Combustion air pressure is measured. Here speaks the concept of

Combustion air pressure to the pressure prevailing in the at least one combustion chamber supplied air mass flow. The air mass flow itself depends on a state equation, in particular on the thermal state equation of ideal gases, which is also referred to as a general gas equation, from the

Combustion air temperature and the combustion air pressure from. The air heat flow in turn can be represented as a function of the air mass flow and the combustion air temperature taking into account the heat capacity, in particular the isobaric heat capacity.

The method is preferably also carried out when an exhaust gas recirculation is provided for the internal combustion engine. In this case, the air mass flow preferably comprises the combustion air supplied to the combustion chamber and in the

Combustion chamber recirculated exhaust gas mass flow. Accordingly, the

Air heat flow, the amounts of heat both the combustion air and the

recirculated exhaust gas. The combustion air temperature is then responsive to the temperature prevailing in the combined stream of combustion air and recirculated exhaust gas.

A method is preferred which is characterized in that a

Exhaust gas heat quantity is determined by an exhaust gas temperature is measured. The exhaust gas temperature is the temperature of an exhaust gas mass flow emitted by the at least one combustion chamber. The exhaust gas heat flow may then be determined as a function of the exhaust gas mass flow and the exhaust gas temperature, taking into account the

Heat capacity, in particular the isobaric heat capacity, the exhaust gas can be represented.

Preferably, the exhaust gas mass flow is based on the mass conservation rate as the sum of the air mass flow and the fuel mass flow, thus the injected fuel quantity, recognized. In a preferred embodiment of the method, the functional relationships mentioned here are inserted into one another and the resulting equation is based on the injected

Fuel mass dissolved. It can be seen in this way that with knowledge of the combustion air temperature, the combustion air pressure and the exhaust gas temperature and assuming a value for the heat distribution factor, the injected fuel mass can be easily calculated. For this purpose, in the context of the preferred embodiment of the method, the combustion air temperature, the combustion air pressure and the exhaust gas temperature are measured. For this purpose, sensors can be used, anyway in the

Internal combustion engine are present. In one embodiment of the

Internal combustion engine, which has no exhaust gas temperature sensor, must for

Only one such additional sensor can be added to carry out the method.

It turns out that calculating the air mass flow based on the equation of ideal gas may not be accurate enough. Around

Deviations of the combustion air from the behavior of an ideal gas and

If necessary, to take into account further corrections, a method is preferred in which the air mass flow from the first and second air heat parameters, ie from the combustion air temperature and the combustion air pressure, under

Considering a correction factor is calculated. In one embodiment of the method, the correction factor is estimated. In another embodiment of the method, the correction factor is determined on the basis of bench tests for a specific model of the internal combustion engine.

A method is preferred which is characterized in that the quotient of the calculated fuel mass divided by the

Fuel mass setpoint is calculated. Thus, the factor is calculated by which the calculated fuel mass flow, which is assumed to correspond to the actually injected fuel quantity, deviates from the fuel mass desired value. If the quotient is greater than one, the calculated and thus also the assumed actual value deviates upwards from the desired value. On the other hand, if the quotient has a value that is less than one, there is a corresponding downward deviation. Preferably, in the context of the method, a deviation is tolerated down, with a deviation indicating upward that a correction of the injected fuel quantity is necessary. In this case, the control of the

Fuel injector adapted only if the quotient has a value greater than one. Preferably, in this case, an injector characteristic, which operating point dependent on the amount of fuel to be injected, adjusted, which is scaled in a particularly preferred and simple embodiment of the method with an adjustment factor, which corresponds to the reciprocal of the quotient.

Alternatively or additionally, it is possible that the control of

Fuel injector is also adapted when the quotient has a value less than one. In this case can also be tendencies or changes

be taken into account, which lead to a reduction in the injected amount of fuel with increasing aging of the internal combustion engine. In particular, the injected amount of fuel can be regulated by means of the method to a predetermined nominal value, even if deviations are corrected downwards.

It is also a method is preferred, which is characterized in that the

Fuel mass setpoint value is determined in dependence on a current speed and a current torque setpoint of the internal combustion engine. The

Preferably, in the control unit deposited, fuel quantity to be injected accordingly depends on the speed of the internal combustion engine and of a

Torque request to the internal combustion engine. Preferably, a map is stored for the fuel mass setpoint, depending on the

current speed and the momentary torque setpoint

Fuel mass setpoint read and to carry out the process

is used.

It is also a method is preferred, which is characterized in that the

Fuel mass setpoint is adjusted once during an initialization of the process in terms of a deployment height of the internal combustion engine. Alternatively or additionally, the fuel mass desired value is preferably once at an initialization of

Process adapted with respect to an operating temperature of the internal combustion engine. The initialization of the method is preferably in a new state of

Internal combustion engine can be made by bed parameters of the process. In this case, it is preferable to correct typical values of the fuel mass desired value which are quasi characteristic of the internal combustion engine, preferably with regard to a deployment height and / or an application temperature of the internal combustion engine. Namely, the quantity of fuel to be injected at a certain speed and torque demand depends in particular on the external ambient pressure the level of use of the internal combustion engine, and also of which temperature the internal combustion engine typically reaches during their operation, which in turn depends on the ambient temperature and / or the cooling conditions. In particular, in stationary internal combustion engines, which are used for example for operating generators for power generation, it is possible to reliably predict the operating altitude and also the operating temperature in the long term.

It is also a method is preferred, which is characterized in that the

Heat distribution factor is determined in dependence on the at least one air heat parameter. Alternatively or additionally, the correction factor is preferably in

Dependent on the determined at least one air heat parameter. Preferably, a functional dependence of the heat distribution factor and / or the

Taking into account the correction factor of the combustion air temperature, wherein it is possible that in a control device, a map is stored, in which of the

Combustion air temperature dependent values for the heat distribution factor and / or the correction factor are stored. Also preferred is a functional dependence of the heat distribution factor and / or the correction factor of the

Taking into account combustion air pressure, preferably in the control unit, a map is stored, in which values for the distribution factor and / or the correction factor as a function of the combustion air pressure are stored. Preferably, a functional dependency on both the combustion air temperature and the combustion air pressure is taken into account for the heat distribution factor and / or correction factor, wherein a characteristic map is preferably stored in the control unit, which values for the heat distribution factor and / or the correction factor depending on both the combustion air pressure also includes the combustion air temperature. It is possible that such values are obtained analytically or in bench tests.

A method is also preferred, which is characterized in that it is performed only in an operating point of the internal combustion engine, in which a maximum torque is output from the internal combustion engine. This means, in particular, that the method is carried out only under full load, with only one fuel mass desired value being stored for a maximum torque operating point. It is possible that this fuel mass desired value is corrected with regard to a deployment altitude and / or a service temperature of the internal combustion engine. In principle, it is sufficient to carry out the method only under full load, because it can be assumed that a deviation of the injected fuel quantity occurring under full load will have the same or at least very similar effect in other operating points of the internal combustion engine, so that the correction determined for the entire engine at full load Operating range of the internal combustion engine is valid.

Alternatively, however, it is possible for the method to be carried out in at least some load points deviating from the full load. Particularly preferably, the method is carried out in the entire load range of the internal combustion engine. In this case, the heat distribution factor, the correction factor and the

Fuel mass setpoint selected in dependence on a current load point of the internal combustion engine. Preferably, corresponding characteristic maps are stored in the control unit, in which values for the heat distribution factor, the

Correction factor and the fuel mass setpoint depending on the load point of the internal combustion engine are stored. The basic assumption of the method that the heat distribution factor does not depend on aging of the fuel injector or of the internal combustion engine as a whole is not affected by this. It is only additionally assumed that the heat distribution factor assumes different values in different load points of the internal combustion engine. The same is assumed for the correction factor. That the fuel mass setpoint depends on the load point of the internal combustion engine is obvious, because overall the fuel consumption of the internal combustion engine is dependent on the load point.

Finally, a method is preferred which is characterized in that the fuel mass desired value as a function of the at least one air heat parameter and / or as a function of a current application level and / or

Use temperature of the internal combustion engine is selected. Thus, in the determination of the fuel mass desired value, it is preferably taken into account that it is selected from at least one size from the combustion air temperature, the

Combustion air pressure, the operating altitude and the operating temperature of the

Internal combustion engine, in particular from the ambient pressure, depends. Preferably, a map for the fuel mass setpoint is stored in the control unit by storing values as a function of at least one of the variables mentioned.

The invention will be explained in more detail below with reference to the drawing. Showing: Fig. 1 is a schematic representation of a combustion chamber of an internal combustion engine and the heat flows flowing through them, and

Fig. 2 is a schematic representation of a combustion chamber of a

Internal combustion engine with sensors used to carry out the method.

FIG. 1 schematically shows the theoretical basis on which the method is based. A combustion chamber 1 is penetrated by different heat flows, it being assumed that the combustion chamber 1 acts neither as a heat source nor as a heat sink, so that all the heat flowing into the combustion chamber 1, also exits therefrom, wherein a temperature of the combustion chamber. 1 at least approximately constant. In Figure 1 coming from the left, an air heat flow 3 and a fuel heat flow 5 are shown by the

Combustion chamber 1 heat is supplied. The fuel heat flow 5

transporting fuel mass flow is previously, here and hereinafter also referred to as injected fuel mass or injected fuel quantity, these figures are preferably based on a working cycle of the internal combustion engine to understand. In particular, it is readily possible to convert an amount of fuel injected per working cycle into a fuel mass fed to the combustion chamber per unit of time, and consequently a fuel mass flow. In order to obtain the combustion chamber 1 supplied with the fuel heat flow Q _br , which is also referred to as m _br fuel mass flow 5 multiplied by the calorific value H _{u of} the fuel used. Thus the equation results:

From the combustion chamber 1, heat is dissipated by doing in this or by this mechanical work, which is shown schematically by a working heat flow 7. The combustion chamber 1 is further removed heat by an exhaust heat flow 9. Other paths over which heat is extracted from the combustion chamber 1, are summarized in a waste heat flow 11, in which case in particular a heat dissipation by cooling, heat radiation and convection is addressed. The method is based on the assumption that the percentage distribution of the various heat flows is at least approximately constant even in the event of a change in the quantity of fuel injected in particular due to aging. Therefore, a heat distribution factor x is assumed, which is the quotient of Q _A

designated exhaust heat flow 9 reduced by the designated as Q _L

Air heat flow 3 divided by the fuel heat flow Q _br after the following

Equation yields:

, = ß ^. (2) a,

FIG. 2 shows an embodiment of one for carrying out a preferred one

Embodiment of the method arranged internal combustion engine in a schematic representation. Again, the combustion chamber 1 is shown, which has a

Combustion air duct 13, an air heat flow 3 is supplied during the

Combustion chamber 1 via an exhaust pipe 15, the exhaust heat flow 9 is removed. In the combustion air line 13, a combustion air temperature sensor 17 for measuring the combustion air temperature is provided as the first air heat characteristic. The

Combustion air temperature is referred to below as T _L. Furthermore, in the combustion air line 13, a combustion air pressure sensor 19 for measuring a combustion air pressure is provided as a second air heat characteristic. Of the

Combustion air pressure is referred to below as p _L. Finally, in the

Exhaust pipe 15, an exhaust gas temperature sensor 21 is provided, with a

Exhaust gas temperature is measured as the exhaust gas heat variable. The exhaust gas temperature is referred to below as T _A.

The method is preferably carried out in an internal combustion engine, which is designed as a reciprocating engine, wherein it is preferably operated by the diesel or by the Otto process. Accordingly, the fuel used is preferably diesel, gasoline, gas, in particular lean gas, or another suitable fuel. The internal combustion engine preferably has a plurality of

Combustion chambers, which corresponds to the number of their cylinders. It is preferred within the scope of the invention, an internal combustion engine, which is adapted to carry out the method. Preferably, the

Internal combustion engine, a device for determining at least one

Air thermal parameter, means for determining at least one

Exhaust gas heat quantity, as well as a device for calculating the injected fuel mass from the at least one air heat parameter, for calculating the comparison variable and for adjusting a control of the

Fuel injection device in dependence on a value of the comparison variable. A preferred embodiment of the internal combustion engine has in particular the combustion air temperature sensor 17, the combustion air pressure sensor 19 and the exhaust gas temperature sensor 21. Furthermore, the internal combustion engine preferably has a control unit which is set up to carry out the method and is in particular operatively connected to the sensors 17, 19, 21.

Also preferred is an engine control unit in which the method according to one of the embodiments discussed here is implemented.

It can be seen that only the combustion air temperature sensor 17, the combustion air pressure sensor 19 and the exhaust gas temperature sensor 21 are preferably provided for carrying out the method with regard to a sensor system of the internal combustion engine. These sensors are provided in any case in a variety of internal combustion engines, so that it requires no additional sensors for performing the method. It is possible that in an internal combustion engine, only the

Combustion air temperature sensor 17 and the combustion air pressure sensor 19 are provided. In this case, to carry out the preferred embodiment of the method described here, it is only necessary to provide a further sensor, namely the exhaust gas temperature sensor 21 on the internal combustion engine. This shows that the method relies in particular on a little complicated and at least essentially existing sensors.

The following procedure is preferably used to calculate the injected fuel mass:

One of the combustion chamber 1 ideally supplied air mass flow m _L , id is on the general gas equation as a function of the combustion air temperature T _L , the Combustion air pressure p _L and a stroke volume V _{h of} a combustion chamber of the

Internal combustion engine multiplied by a number Z of combustion chambers, and the speed n of the internal combustion engine - preferably in terms of revolutions per second - specified, taking into account a Taktzahlfaktor which indicates how many intake strokes the engine has per revolution of its crankshaft. The following is without limitation of generality

Four-stroke internal combustion engine has gone out, so that the clock number factor is 0.5. This results in a total for the ideally supplied air mass flow m _L , i _d . with the general gas constant R the following equation:

P _L ^V h ^Z

RT _L 2 ^"

To simplify the illustration, the stroke volume V _h, the number of combustion chambers Z, the rotational speed n, the general gas constant R and the

Taktzahlfaktor summarized in a constant K:

V _h Zn

(4) 2R such that, taking into account (4) in (3), the following equation gives the ideally supplied mass air flow m _{L id} :

m Cid K (3 ')

Deviations of the combustion air from the ideal behavior as well as possibly further effects that require a correction are taken into account by the air mass flow m _{L is} set as the product of the ideal air mass flow ητΐυ ,. multiplied by a correction factor λ:

m _L = Am _Lrid = ÄK -. (5)

L The exhaust gas mass flow m _A is assumed taking into account the mass conservation rate as the sum of the air mass flow m _L and the

Fuel _{mass flow} or the injected fuel _{mass mbr} : m _A = m _L + m _br . (6)

It is now possible to express the exhaust gas heat flow Q _A taking into account the isobaric heat capacity of the exhaust gas c _p , _A as a function of the exhaust gas temperature T _A :

In an analogous manner, it is possible, the air heat flow Q _L taking into account the isobaric heat capacity of the combustion air c _p , _L as a function of

Combustion air temperature T _u express:

Q _L = m _L c _PJ T _L (8)

Overall, the following equation results for the difference between the exhaust gas heat flow and the air heat flow:

Q _A - Q _L = K ^ c _{p <A} T _A + m _br c _{p, A} T _A - _{p L} T _L. (9)

If, on the one hand, equation (9) and, on the other hand, equation (1) in equation (2) are used and the resulting equation is solved according to the fuel mass flow m _br , the calculated fuel mass results in:

_mbr = ^L - ^{~ ■} (10)

x ^H u ~ ^C p, A ^T A

It thus appears that the injected fuel _mass m _br can be calculated from the measured values of the combustion air temperature sensor 17,

Combustion air sensor 19 and the exhaust gas temperature sensor 21, if a value for the Correction factor λ and a value for the heat distribution factor x is assumed. The heat capacities of the exhaust gas c _p , _A and the combustion air c _p , _L are preferably assumed to be constant and are particularly preferred in the

Control unit deposited.

In order to correct the injected fuel quantity, a quotient k from the calculated fuel _mass m _br and one is preferably used as comparison _quantity

Fuel mass setpoint m _s calculated:

(11)

Preferably, an injector characteristic is stored in the control unit, which

Depending on the load point, in particular Depending on the speed n and a

Torque request of the internal combustion engine control parameters for the fuel injection device or values for a injected

Fuel mass includes. This injector characteristic curve is preferably corrected if the quotient k has a value that is greater than 1. On the other hand, preferably no correction of the injector characteristic is made if the value of the quotient k is less than or equal to 1. In a particularly preferred embodiment of the method, the injector characteristic is scaled with an adjustment factor which is equal to the reciprocal of the quotient k.

In another embodiment of the method, the injector characteristic is always corrected even when the quotient k has a value that is different from 1. Also in this case, the injector characteristic is preferably scaled with an adjustment factor, which is the reciprocal of the quotient k.

In a particularly simple embodiment of the method, in each case a constant value is assumed both for the correction factor λ and for the heat distribution factor x. In another embodiment, it is possible for the

Correction factor λ and / or for the heat distribution factor x a dependence on the combustion air temperature T _{L is} assumed. Alternatively or additionally, it is possible that a dependence on the combustion air pressure p _{L is} assumed for the correction factor λ and / or for the heat distribution factor x. The different, Pressure- and / or temperature-dependent values are preferably stored in maps. Alternatively or additionally, an analytical description of the

Dependencies are possible, whereby the corresponding values are always recalculated within the framework of the method.

The fuel mass desired value m _s is preferably adjusted once during an initialization of the method with regard to a deployment height and / or a service temperature of the internal combustion engine. In another embodiment of the method, it is alternatively or additionally possible for the fuel mass desired value to be selected as a function of the combustion air temperature T _L and / or of the combustion air pressure p _L , whereby preferably also a deployment altitude and an operating temperature of the internal combustion engine are taken into account via these values. It is at one

Embodiment of the method possible, additionally or alternatively explicitly a

Dependence of the fuel mass desired value m _s of a current operating altitude and / or operating temperature of the internal combustion engine to take into account. The corresponding, dependent values of the fuel mass desired value m _s are preferably stored in a characteristic map.

It is possible in one embodiment of the method that this is carried out only under full load of the internal combustion engine. In this case, the

Fuel mass setpoint m _s always a torque maximum of

Value assigned to internal combustion engine.

Alternatively, it is possible for the method to be carried out in at least some operating points of the internal combustion engine deviating from the full load. The method is particularly preferably carried out over the entire operating or load range of the internal combustion engine. In this case, the fuel mass setpoint value m _s depends on the instantaneous load point of the internal combustion engine. Preferably

Load point-dependent values for the fuel mass setpoint m _s stored in a map. If the method is performed depending on the load point, preferably also a load point dependence for the correction factor λ and / or for the

Heat distribution factor x taken into account. The corresponding values are preferably also stored in maps. Experiments show that the method makes it possible to accurately determine a deviation of the injected fuel mass to at least 3% and to carry out corresponding corrections. The accuracy can in particular by detailed consideration of the dependencies of the heat distribution factor x and the correction factor λ of the combustion air temperature T _L and the

Combustion air pressure p _{L be} further increased.

Thus, overall, it can be seen that the method based on a simple physical approach using only three measured values makes it possible to carry out a correction without great effort

Fuel injector injected amount of fuel in the operation of

Internal combustion engine perform.

Claims

claims

A method of correcting a fuel injector

Injected amount of fuel in the operation of an internal combustion engine, comprising the following steps: determining at least one air heat parameter from which at least one combustion chamber (1) of the internal combustion engine supplied

Air heat flux (3; Q _L ) functionally dependent; Determine at least one

Exhaust gas heat quantity, from which one of the at least one combustion chamber (1) emitted exhaust heat flow (9; Q _A ) functionally dependent; Determining a heat distribution factor (x) indicative of a fraction of the exhaust heat flow (9; Q _A ) reduced by the air heat flow (3; Q _L ) relative to one of the at least one combustion chamber (1) and the injected heat flow (5); Calculating a fuel mass (m _br ) supplied to the internal combustion engine from the at least one air heat parameter, the at least one exhaust gas heat parameter and the heat distribution factor (x); Calculating a comparison quantity by comparing the calculated fuel mass (m _br ) with a fuel mass desired value (m _s ) and adjusting a drive of the fuel injector depending on a value of

Comparison.

2. The method according to claim 1, characterized in that a first

Air thermal parameter is determined by a combustion air temperature (T _L ) supplied as a temperature of at least one combustion chamber (1)

Air mass flow (m _L ) is measured, preferably a second

Air thermal parameter is determined by a combustion air pressure (p _L ) as Pressure of the at least one combustion chamber (1) supplied air mass flow (m _L ) is measured.

3. The method according to any one of the preceding claims, characterized in that a Abgaswärmekenngröße is determined by an exhaust gas temperature (T _A ) as the temperature of one of the at least one combustion chamber (1) emitted exhaust gas mass flow (m _A ) is measured.

4. The method according to any one of the preceding claims, characterized in that the air mass flow (m _L ) from the first and the second

Air thermal parameter is calculated taking into account a correction factor (λ).

5. The method according to any one of the preceding claims, characterized in that a quotient (k) from the calculated fuel mass (m _br ) and the fuel _{mass setpoint} (m _s ) is calculated as a comparison variable, wherein preferably the control of the fuel injection device is adapted only if Quotient (k) has a value greater than one.

6. The method according to any one of the preceding claims, characterized in that the fuel mass setpoint (m _s ) determined in dependence on a current speed (n) and a current torque setpoint of the internal combustion engine, preferably a map is taken.

7. The method according to any one of the preceding claims, characterized in that the fuel mass desired value (m _s ) is adjusted once during an initialization of the method in terms of a deployment height and / or an operating temperature of the internal combustion engine.

8. The method according to any one of the preceding claims, characterized in that the heat distribution factor (x) and / or the correction factor (λ) in

Dependent on the determined at least one air heat parameter

will be.

9. The method according to any one of the preceding claims, characterized in that the method only in an operating point of the internal combustion engine

is performed, wherein a maximum torque of the

Internal combustion engine is discharged, or that the method is performed in at least some different load points, preferably in an entire operating range of the internal combustion engine, wherein the heat distribution factor (x), the correction factor (λ) and the fuel mass setpoint (m _s ) selected in dependence on a current load point become.

10. The method according to any one of the preceding claims, characterized in that the fuel mass desired value (m _s ) is selected as a function of at least one air heat parameter and / or in dependence on a current operating height of the internal combustion engine.