DE102007061732A1 - Internal combustion engine operating method for motor vehicle, involves plausibilizing parameter determined in function level to control engine and another parameter determined in function monitoring level to monitor engine's function - Google Patents

Abstract

The method involves injecting fuel in two partial injections. A parameter characterizing energy conversion in an internal combustion engine (1) e.g. momentum efficiency factor, of each partial injection determined in a function level for controlling the engine and another parameter characterizing the energy conversion determined in a function monitoring level for monitoring proper function i.e. function level, of the engine are plausibilized with each other. A value of difference between the parameters is verified when a preset threshold is exceeded. Independent claims are also included for the following: (1) a computer program comprising instructions for executing a method for operating an internal combustion engine (2) a control device for an internal combustion engine of a motor vehicle.

Description

State of the art

The The invention relates to a method for operating an internal combustion engine, at the fuel injected in at least two partial injections and one that characterizes the energy conversion in the internal combustion engine Size, in particular a moment efficiency, the respective partial injection is determined.

The The invention further relates to an internal combustion engine and a control unit for an internal combustion engine. In addition concerns the present invention also a computer program for a control unit of an internal combustion engine.

An operating method and a control device of the aforementioned type are already known from DE 10 2004 048 008 A1 known. The method described there is used, for example, to monitor an actual torque which is output by the internal combustion engine. The described consideration of the torque efficiency of partial injections allows accurate monitoring of the actual torque.

Disclosure of the invention

It Object of the present invention, an operating method and a control unit of the type mentioned above to improve that even more precise and reliable monitoring the operation of the internal combustion engine is possible.

These Task is in the operating method of the type mentioned solved according to the invention that one in a functional level for controlling the internal combustion engine determined first characterizing size, in particular a first torque efficiency, the respective partial injection and one in a functional monitoring level for monitoring a proper function of the internal combustion engine, in particular for monitoring the functional level second characterizing size, in particular a second torque efficiency, the respective partial injection be plausibilized with each other.

The first in the context of the method according to the invention considered operating level, the functional level, sees a processing the sizes controlling the operation of the internal combustion engine before and is used directly for the formation of drive signals, with which the internal combustion engine or they controlling actuators controlled be to influence the operation of the internal combustion engine.

additionally to the functional level is also according to the invention a function monitoring level, which, for example using redundant signal processing to the functional level or also by the processes representing the functional level Models advantageous to monitor the proper Function of the control unit or functional level, which increases compared to conventional systems Reliability is given.

According to the invention preferably as the energy conversion in the internal combustion engine charakaterisierende Size of the partial injection of the torque efficiency considered the relevant partial injection; it is, however conceivable, other suitable, the energy conversion in the internal combustion engine to consider characaterizing quantities.

In Realization of the invention at least partially redundant signal processing becomes a first torque efficiency for a partial injection in the functional level, for example, directly determined for tax purposes, eg. For example, one in the future to calculate the amount of fuel to be injected and the like. additionally this is advantageous for monitoring purposes in the function monitoring level a second torque efficiency for the relevant partial injection which has the same physical significance as the first one Torque efficiency of the functional level, but due to its Determination in the function monitoring level i. d. R. different is obtained as the first moment efficiency of the functional level. The Determination of the second torque efficiency in the function monitoring level Namely, preferably using simplified Models and therefore usually requires a lower Computing effort than that performed in the functional level Determination of the first torque efficiency.

The plausibility check of the torque efficiency according to the invention advantageously makes it possible to determine whether the simplified model used in the function monitoring level for determining the second torque efficiency agrees reasonably well with the real operating parameters used in the function level. In this case, z. B. be assumed that there are no errors and continue safe operation of the internal combustion engine is possible. In conventional systems that do not have the plausibility check according to the invention, an error-related deviation of the torque efficiencies can not or at most be recognized at a later time, so based on a faulty second torque efficiency already calculated, derived variables incorrect before the error is detected.

The Plausibilisierung invention can one particularly preferred and less computationally intensive variant of the invention Operating procedure, that an amount of the Difference between the first moment efficiency and the second Torque efficiency checked for exceeding a predetermined threshold becomes.

A Another very advantageous embodiment of the invention Operating procedure provides that - if successful Plausibility is present - that in the functional level determined first torque efficiency also in the function monitoring level is used. That is, instead of the model-based determined second torque efficiency may be the functional monitoring level after a successful plausibility check since then in the functional level assumed first torque efficiency and use for further calculations without the operational safety the internal combustion engine according to the invention impaired is. Possibly. by that for determining the second torque efficiency used simplified model can cause errors thus, they do not cumulate randomly and lead to consequential errors, because after a successful plausibility check on the value of the first torque efficiency from the functional level recourse which usually complies better with real-world operations.

A another particularly preferred embodiment of the invention Operating procedure provides that in case of a faulty plausibility a preferably multi-stage error reaction is initiated. According to the invention in a first stage of the error reaction, an operating mode of the internal combustion engine be set, in which no corresponding to the plausibility torque efficiency Partial injection is provided, so that a possibly incorrect calculation the torque efficiency is not or only slightly for the further operation is significant.

Provided even after such a measure and / or a predefinable Waiting time no successful plausibility check of the considered Values for the torque efficiency is possible, can according to another variant of the invention in a second Stage of the error reaction emitted by the internal combustion engine Torque can be limited to a predetermined maximum value, in particular to an undesirable acceleration of the internal combustion engine to avoid in case of failure. Alternative or supplementary can also trigger a reset of the internal combustion engine controlling the controller become.

The Inventive determination of the second torque efficiency in the functional monitoring level can thereby continue in Their precision increases that fuel pressure considered in a fuel storage of the internal combustion engine becomes. This takes into account the fact that at a higher fuel pressure better fuel atomization takes place in a combustion chamber and accordingly an increased Torque efficiency is given.

From Of particular importance is the realization of the invention Procedure in the form of a computer program running on a computer or an arithmetic unit of a control unit executable and is suitable for carrying out the method. The computer program can for example be stored on an electronic storage medium For example, the storage medium in the control unit may be included.

Further Features, applications and advantages of the invention result from the following description of exemplary embodiments of the invention, which are illustrated in the figures of the drawing. All described or illustrated features form for itself or in any combination the subject of the invention, independently from its summary in the claims or their relationship and regardless of theirs Formulation or presentation in the description or in the drawing.

In the drawing shows:

1 a schematic block diagram of an inventive internal combustion engine,

2 a flowchart of an embodiment of the inventive method, and

3 a functional diagram of another embodiment of the inventive method.

In the 1 is an internal combustion engine 1 a motor vehicle shown in which a piston 2 in a cylinder 3 is reciprocable. The cylinder 3 is with a combustion chamber 4 provided, inter alia, by the piston 2 , an inlet valve 5 and an exhaust valve 6 is limited. With the inlet valve 5 is an intake pipe 7 and with the exhaust valve 6 is an exhaust pipe 8th coupled.

In the area of the inlet valve 5 and the exhaust valve 6 protrudes an injection valve 9 in the combustion chamber 4 , about the fuel in the combustion chamber 4 can be injected. In the exhaust pipe 8th is a Ka talysator 12 housed, which is used to clean the resulting from the combustion of the fuel exhaust gases. The injection valve 9 is via a pressure line with a fuel tank 13 connected. In a corresponding manner, the injection valves of the other cylinders of the internal combustion engine 1 with the fuel storage 13 connected. The fuel storage 13 is supplied via a supply line with fuel. For this purpose, a preferably mechanical fuel pump is provided which is adapted to the desired pressure in the fuel tank 13 build.

Furthermore, on the fuel tank 13 a pressure sensor 14 arranged, with which the pressure in the fuel tank 13 is measurable. This pressure is the pressure exerted on the fuel, and therefore the fuel through the injector 9 in the combustion chamber 4 the internal combustion engine 1 is injected. In operation of the internal combustion engine 1 fuel gets into the fuel tank 13 promoted. This fuel is delivered through the injectors 9 the single cylinder 3 in the associated combustion chambers 4 injected. By burning the in the combustion chambers 4 predominant air / fuel mixture are the pistons 2 be put into a float. These movements are transmitted to a non-illustrated crankshaft and exert on this torque.

A control unit 15 is of input signals 16 acted upon, the measured by means of sensors operating variables of the internal combustion engine 1 represent. For example, the controller 15 with the pressure sensor 14 , an air mass sensor, a speed sensor and the like. Furthermore, the control unit 15 connected to an accelerator pedal sensor which generates a signal indicative of the position of a driver operable accelerator pedal and thus the requested torque. The control unit 15 generates output signals 17 , with which about actuators or Steller the behavior of the internal combustion engine 1 can be influenced. For example, the controller 15 with the injector 9 and the like, and generates the signals required to drive them.

Among other things is the control unit 15 intended to the operating variables of the internal combustion engine 1 to control and / or to regulate. For example, that of the injection valve 9 in the combustion chamber 4 injected fuel mass from the controller 15 controlled and / or regulated in particular with regard to low fuel consumption and / or low pollutant development. For this purpose, the control unit 15 provided with a microprocessor which has stored in a storage medium, in particular in a flash memory, a computer program which is adapted to perform said control and / or regulation.

Also in the control unit 15 implemented is a function monitoring of the internal combustion engine 1 that on a determination of that of the internal combustion engine 1 delivered torque is based, which is hereinafter referred to as actual torque. The actual torque is output from the control unit 15 recorded operating variables of the internal combustion engine 1 , see. the input signals 16 , arithmetically in the control unit 15 determined. Such operating variables are, for example, an injection duration, ie the length of a time interval, via the fuel into the combustion chamber 4 is injected and an injection pressure, ie the pressure sensor 14 determined pressure in the fuel tank 13 with which the fuel enters the combustion chamber 4 is injected.

The function monitoring is preferably realized in a so-called functional monitoring level, which as well as a substantially for controlling the internal combustion engine 1 provided function level is provided in the form of a computer program that on a computing unit of the control unit 15 the internal combustion engine 1 expires. According to the invention, the control processes taking place in the functional level are used to control the internal combustion engine 1 a first torque efficiency determined in the functional level. In this case, the first torque efficiency indicates to what proportion one of a plurality of partial injections, moreover, contributes to the total output torque from the internal combustion engine. A second torque efficiency is additionally formed in the function monitoring level. For this purpose, for example, the behavior of the engine representing models are used. The second torque efficiency determined in the function monitoring level corresponds to the first torque efficiency formed in the function level and, under normal operating conditions, substantially coincides therewith.

any Deviations arise experience shows primarily in that that for determining the second torque efficiency used simplified model to some extent from the real one Ratios in the functional level in the determination the first moment efficiency is taken into account, differs.

To ensure proper functioning of the internal combustion engine 1 It is provided according to the invention that the first torque efficiency of a partial injection determined in the functional level and the second torque efficiency determined in the functional monitoring level are the same ben Teileinspritzung be plausibilized with each other.

The Plausibilisierung can be done, for example, that the Values of the first and second torque efficiency are subtracted from each other and that an amount of the difference obtained in this case checks the exceeding of a predefinable threshold becomes. This check is preferably carried out periodically.

2 shows a simplified flow diagram of a corresponding embodiment of the operating method according to the invention. In the first step 200. the above-described difference of the respective torque efficiencies is formed, and then the amount of the difference is determined. Subsequently, in the step 210 checked, above the amount value exceeds a predetermined threshold. The threshold value may preferably be an operating-point-dependent variable. In particular, it is conceivable that in the method step according to the invention 210 Verified threshold of a speed of the internal combustion engine 1 is dependent. The selection of a corresponding threshold can be done in a conventional manner using a speed-dependent characteristic.

If the plausibility check according to the invention in step 210 shows that the first torque efficiency and the second torque efficiency are too different from each other, the evaluated magnitude value correspondingly above the threshold value, is in the Vefahrensschritt 230 branches, which represents the execution of an error reaction.

According to the invention, the error reaction 230 multi-level trained. For example, the plausibility check described above 200. . 210 over a predefinable number of operating cycles of the controller 15 be carried out, and only when no successful plausibility is possible for a predetermined time, a first stage of the error response is initiated.

In this case, it may in particular be provided that an operating mode of the internal combustion engine 1 is set, in which no corresponding with the plausibilized torque efficiency partial injection is provided. By avoiding an operating mode according to the invention with partial injections in the first stage of the error reaction 230 can thus be ensured that the internal combustion engine 1 no longer works in an operating mode in the future, which leads to the plausibility error described above.

In addition, a second stage of the error reaction according to the invention can also be used 230 be executed. This second stage includes, for example, a limitation of that of the internal combustion engine 1 output torque to avoid unwanted acceleration of the internal combustion engine. It is also conceivable within the scope of the second stage of the error reaction according to the invention 230 a reset of the engine driving the control unit 15 perform.

However, if in the step according to the invention 210 a successful plausibility of the torque efficiencies has been carried out, then in the process step 220 be branched. After the successful plausibility check in the context of the operating method according to the invention says that there is a sufficiently good match of the first torque efficiency determined in the function level with the second torque efficiency determined preferably model-based in the function monitoring level, it can now be advantageously assumed that for future calculations within the function monitoring level the originating from the functional level first torque efficiency can be used without safe operation of the internal combustion engine 1 to impair. After a positive plausibility check according to the invention, the first torque efficiency formed from the currently detected operating variables of the internal combustion engine can thus also be used for the calculations in the function monitoring level and thus replaces the second torque efficiency, which has since been determined model-based.

As a result, calculations based on the torque efficiency performed in the function monitoring level can henceforth be performed with a more accurate value for the torque efficiency. In particular, also provided in the functional monitoring level monitoring of the internal combustion engine 1 delivered actual torque can be performed more precisely if the invention according to the invention plausibilized first torque efficiency in the function monitoring level takes the place of the second torque efficiency used since then. This means that an actual torque calculated in the function monitoring level coincides more exactly with the actual torque of the internal combustion engine, because this calculation is based on the previously plausibilized torque efficiency from the functional level.

As a result, it is advantageously possible to provide lower tolerance limits when comparing the actual torque determined in the function monitoring level with an actual actual torque hen and thus allow a more accurate detection of the occurrence of error cases.

In a further particularly advantageous embodiment of the operating method according to the invention, it may further be provided that, even in the case of a successful plausibility check, the first torque efficiency originating from the functional level is not used to replace the second torque efficiency in the functional monitoring level. That is to say, it has been confirmed by the successful plausibility check that the model-based second torque efficiency still agrees sufficiently well with the first torque efficiency from the functional level. However, the model-based second torque efficiency is still being used in the function monitoring level. This functionality enables complete compatibility of the operating method according to the invention with conventional operating methods. The activation of the functionality according to the invention can be achieved, for example, by an applicable parameter for the control unit 15 be implemented software provided.

The following is based on 3 describes a further embodiment of the inventive operating method, wherein the fuel by means of five partial injections into the combustion chamber 4 the internal combustion engine 1 out 1 is injected. Accordingly, the partial injection quantities Qt1, Qt2, Qt3, Qt4, Qt5 are assigned to the five split injections 3 top left as input quantities of the function diagram shown.

In this case, the partial injection quantities Qt1, Qt2, Qt3 designate one each within the scope of a so-called pre-injection into the combustion chamber 4 injected fuel quantity, while the partial injection amount Qt4 represents a partial injection amount injected during a so-called main injection. The partial injection quantity Qt5 is associated with a so-called post injection, which is usually carried out to increase the exhaust gas temperature and, for example, can be used in the exhaust tract of the internal combustion engine 1 regenerate particulate filter (not shown).

How out 3 is apparent, the Teileinspritzmengen Qt1 and Qt2 by means of the adder 101 and the resulting sum 101 by means of the adder 102 added to the partial injection quantity Qt3. The resulting sum signal 102 ' at the output of the adder 102 finally becomes the adder 103 in which the part injection quantity corresponding to the main injection Qt4 is added, resulting in the output of the adder 103 the sum signal 103 ' results.

The sum signal 103 ' indicates that amount of fuel which in the context of the three pilot injections with the respective partial injection quantities Qt1, Qt2, Qt3 and the main injection with the partial injection quantity Qt4 in total in the combustion chamber 4 the internal combustion engine 1 is injected.

In contrast to the pilot injections and the main injection, which have approximately the same torque efficiency with respect to one of the internal combustion engine 1 have delivered actual torque causes one in the context of post-injection into the combustion chamber 4 the internal combustion engine 1 injected part injection quantity Qt5 a comparatively lower actual torque. This difference is taken into account by the torque efficiency eta_M, which is at the output of the multiplier 106a is obtained and whose determination is described below.

The torque efficiency eta_M described below is the quantity previously referred to as the second torque efficiency, ie the torque efficiency that is present in the function monitoring level of the control unit 15 is formed for monitoring purposes model-based.

The with the moment efficiency eta_M in the multiplier 107 multiplied partial injection quantity Qt5 of the post-injection leads at the output of the multiplier 107 to the effective partial injection quantity 107 ' the post-injection, in the adder 104 finally to the sum signal 103 ' is added, resulting in the output of the adder 104 a so-called total virtual fuel quantity Q_v is obtained.

The total virtual fuel quantity Q_v represents that amount of fuel which, in the main injection or in another partial injection, has the same torque efficiency as the main injection, that is, for example also during a pre-injection, into the combustion chamber 4 the internal combustion engine 1 would have to be injected in order to achieve the same actual torque as in an injection of the partial injection quantities actually used Qt1 to Qt5. In the present example, only the post-injection has a reduced torque efficiency eta_M compared with the main injection, so that the effective post-injection quantity 107 ' is smaller than the actual partial injection amount Qt5 of the post injection, whereby the total virtual fuel amount Q_v is also smaller than an unweighted sum of the partial injection amounts Qt1 to Qt5.

How out 3 can be seen, the torque efficiency eta_M the post-injection is according to the invention of several input variables together. A first factor f_1 becomes a speed n_BKM of the internal combustion engine 1 ( 1 ) and from a so-called Ansteuerbeginnwinkel phi means of a map 108 receive. Instead of the Ansteuerbeginnwinkels phi can also be used a different size, which the injection time or its temporal position in relation to a crank angle of the crankshaft of the internal combustion engine 1 indicates.

Based on the partial injection quantity Qt5 of the post-injection. and the characteristic 109 a second factor f_2 is formed in the multiplier 105 is multiplied by the first factor f_1. That at the output of the multiplier 105 applied signal 105 indicates an influence of the timing of the post injection with respect to the crank angle and the injected partial injection amount Qt5 in the post injection to the torque efficiency eta_M of the post injection.

Since no or at least no complete combustion of the nacheingespritzten fuel quantity takes place in the post-injection from a certain time interval delta_t for main injection, this time interval is delta_t through the map 110 considered. The injected during the main injection part injection quantity Qt4 also enters into the relationship described above and is according to 3 therefore also as an input signal for the map 110 used.

The by means of the map 110 factor f_3 obtained is in the multiplier 106 with the output signal 105 ' of the multiplier 105 , ie multiplied by the product of the factors f_1 and f_2, from which the size 106 ' is obtained.

Another map, 110a , the input side of the pressure p_rail in the fuel tank 13 ( 1 ), finally provides a fourth factor f_4, which takes into account the pressure-dependent atomization processes in the injection and the associated different momentum efficiency.

The fourth factor f_4 is given by the multiplier 106a with the signal 106 ' multiplied, whereby finally the torque efficiency eta_M of the post-injection is obtained.

Accordingly, according to the invention, the torque efficiency eta_M is dependent on a partial injection quantity Qt4 of the main injection, a partial injection quantity Qt5 of the post-injection, as well as on the rotational speed n_BKM of the internal combustion engine 1 , the drive start angle phi and a time difference delta t between the main injection and the post injection and the pressure p_rail of the injected fuel.

Depending on these parameters, the torque efficiency eta_M assumes a value between 0 and 1. Accordingly large or small is the influence of the weighted with the torque efficiency eta_M partial injection quantity Qt5 of the post-injection on the actual torque that in the control unit 15 ( 1 ) can be determined from the total virtual fuel quantity Q_v.

at the determination of the actual torque from the total virtual fuel quantity Q_v are the torque contributions of the respective partial injections and their possibly deviating from 100% torque efficiencies, as it z. B. in the post-injection is the case, all already in the total virtual fuel Q_v summarized, making a special simple determination of the actual torque using known methods is possible.

As an alternative to evaluating the actuation start angle phi, the time position of the post-injection can be based, for example, on the top dead center of the working cycle of the cylinder 3 can also be represented by any other sizes. For example, instead of the actuation start angle phi, an injection time of the main injection or of the post-injection may also be used, as long as a corresponding characteristic field is available.

at a further very advantageous embodiment of the present invention Invention can analogously to the factors f_1, f_2, f_3, f_4 also takes into account other factors (not shown) which are suitable, the torque efficiency eta_M influence.

The torque efficiency eta_M can z. B. also in dependence of an intake air temperature and / or an air pressure and / or signals of a knock sensor and / or other sensor signals and / or operating variables of the internal combustion engine 1 be determined.

It is also conceivable to determine the torque efficiency eta_M as a function of a chronological course of the combustion. This could z. B. a pressure and / or temperature profile in the combustion chamber 4 be used for even more precise determination of the torque efficiency eta_M.

It is also possible in a further variant of the invention, in the manner described above, values of the moment efficiency eta_M z. B. depending on some or all input variables Qt1, Qt2, Qt3, Qt4, Qt5, n_BKM, phi, delta_t, p_rail store, for example, for diagnostic purposes or for the creation of correspond the maps.

In this case, it is also particularly advantageous to create or compare a multi-dimensional characteristic diagram for the moment efficiency eta_M, which includes the in 3 input variables Qt4, Qt5, r_BKM, phi, delta_t, p_rail. The inventive method is not limited to the determination or plausibility of the torque efficiency of a post-injection. For example, it is also possible with the method according to the invention to determine or make plausible a torque efficiency of a pilot injection.

The total virtual fuel quantity Q_v is used - as already described - for a calculation of the of the internal combustion engine 1 given actual torque, which due to the inventive consideration of the torque efficiency eta_M the post-injection provides a more accurate result than conventional methods. Due to the more accurate calculation of the actual torque, an improvement in the monitoring of the same, for example in the context of a comparison with an allowable torque allows because the monitoring lower tolerance thresholds must be recognized and deviations of the actual torque can therefore be detected faster. As a result, a safer operation of the internal combustion engine 1 allows. The above with reference to the 2 . 3 The inventive method described is independent of the specific design of the injection system of the internal combustion engine 1 applicable. For example, it is in so-called. Common rail injection systems with magnetically or piezoelectrically actuated injectors 9 as applicable as with pump-nozzle injection systems. Also a superimposed lambda control for optimizing the emission behavior of the internal combustion engine 1 does not exclude the application of the method according to the invention.

Even though the invention described above based on torque efficiencies of the partial injection However, it is also conceivable other suitable, the energy conversion in the internal combustion engine charakaterisierende sizes to look at the part injections. This results in the same Benefits of more accurate and reliable monitoring the operation of the internal combustion engine.

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• - DE 102004048008 A1 [0003]

Claims (10)

Method for operating an internal combustion engine ( 1 ), in which fuel is injected into at least two partial injections and a variable (eta_M) characterizing the energy conversion in the internal combustion engine, in particular a torque efficiency, of the respective partial injection is determined, characterized in that one in a functional plane for controlling the internal combustion engine ( 1 ) determined first charakaterisierende size, in particular a first torque efficiency, the respective partial injection and one in a function monitoring level for monitoring a proper operation of the internal combustion engine ( 1 ), in particular for monitoring the functional level, determined second charakaterisierende size, in particular a second torque efficiency, the respective partial injection are plausible together. Method according to claim 1, characterized in that that the plausibility check is made by an amount of the difference between the first torque efficiency and the second torque efficiency checked for the exceeding of a predetermined threshold becomes. Method according to one of the preceding claims, characterized in that in a successful plausibility the determined in the functional level first torque efficiency is also used in the function monitoring level. Method according to one of the preceding claims, characterized in that, in the event of a faulty plausibility check, a (preferably multi-stage) fault reaction ( 230 ) is initiated. Method according to claim 4, characterized in that in a first stage of the error reaction ( 230 ) an operating mode of the internal combustion engine ( 1 ) is set, in which no partial injection corresponding to the plausibilized torque efficiency is provided. Method according to claim 4 or 5, characterized in that in a second stage of the error reaction ( 230 ) one of the internal combustion engine ( 1 ) Torque is limited to a predetermined maximum value. Method according to one of claims 4 to 6, characterized in that in a second stage of the error reaction ( 230 ) a reset of an internal combustion engine ( 1 ) controlling the control device ( 15 ) is triggered. Method according to one of the preceding claims, characterized in that in the determination of the second torque efficiency in the function monitoring level, a fuel pressure in a Kraftoffspeicher ( 13 ) is taken into account. Computer program, characterized in that it for carrying out the method according to one of the claims 1 to 8 is programmed. Control unit ( 15 ) for an internal combustion engine ( 1 ) of a motor vehicle, characterized in that it is designed for carrying out the method according to one of claims 1 to 8.