DE102004046056A1 - Internal combustion engine e.g. diesel engine, controlling method for vehicle, involves detecting positions of actuating unit such that deviation between measured pressure and calculated pressure in inlet line presents minimum amplitude - Google Patents

Abstract

The method involves calculating pressure of an inlet line for each adjusting position of an actuating unit using models (50, 55), and comparing the pressure measured in the inlet line to each calculated pressure value. Respective positions of the actuating unit are detected, such that a deviation between the measured pressure and calculated pressure in the inlet line presents a minimum amplitude. An independent claim is also included for a device for controlling an internal combustion engine.

Description

The The invention relates to a method and a device for Operating an internal combustion engine with at least one cylinder after the genus of independent claims out.

It are already methods and apparatus for operating an internal combustion engine known with several cylinders. The cylinders is thereby from a Intake manifold of the internal combustion engine via each supplied with an air duct air. This includes such Air duct two air ducts, being in one of the two air ducts a charge movement flap is arranged, which in a closed Position to a reduced opening cross-section of the associated Air duct leads and those in an open position to a maximum opening cross section of associated air duct leads. Between the open Position of the cargo movement flap and the closed position the charge movement flap can be switched. Charge movement flaps ensure sufficient air movement even in partial load. The mixture preparation is getting better. The burning gets better. Emissions are falling. It is also known by closing Inlet valves perform a cylinder shutdown to to reduce fuel consumption. Furthermore, the use is at least a resonance flap in the intake manifold for power increase known. In multi-cylinder engines, such as e.g. for engines with eight cylinders For example, in a part load range, four cylinders will go through Shut down of the respective intake valve turned off. To the engine or the Continue to run the internal combustion engine with the same power, the remaining, un-deactivated cylinders are filled with a higher pressure in the intake manifold. The higher one Pressure in the intake manifold reduces the charge cycle losses and thus the fuel consumption. In full load range, provided in the intake manifold resonance flaps dependent be set from the engine speed so that at the time of closing the inlet valve of the respective cylinder, the pressure of a pressure wave this inlet valve for a better filling of the combustion chamber and thus increases the performance. The aforementioned Cargo movement flaps provide for a greater movement the air mass flow and thus for a better mixing of the air / fuel mixture in the part-load operating range of the Internal combustion engine, in its closed position the Cross sectional area the associated air duct, the inlet valve of the associated Cylinder leads, reduce. In full load operating area, they then enter in their open Position the maximum cross-sectional area of the associated air duct free, so as not to impair performance. The effected thereby larger air mass flow in the Full load operating range is sufficient even without narrowing the cross-sectional area Move.

to Measurement of air filling the combustion chamber so far air mass meter are used. It will the air mass flow switched by the air controls correct measured. In this way, also the correct injection quantity be sprayed on fuel. The air plates are not emission-relevant. For cost reasons However, the air mass meter are more and more by intake manifold pressure sensors replaced. It is about a model of the relationship between intake manifold pressure and air charge in the Combustion chamber made. In this model then the position of the switching air actuator taken into account become. However, the model provides an incorrect value for the air charge when the Air actuator does not assume its specified target position. The air actuator is therefore relevant to exhaust emissions in this case and must therefore be monitored become. Therefore one uses position feedback to the supervision obligation comply. In the case of cylinder deactivation are such position feedback not easily feasible. Therefore it is recommended for this case, the Maintain air mass meter.

Advantages of invention

The inventive method and the device according to the invention for operating an internal combustion engine having at least one cylinder the characteristics of the independent claims have in contrast the advantage of that for each adjustable position of the first actuator by means of a model An intake manifold pressure is calculated that the intake manifold pressure measured is that the measured intake manifold pressure with each of the calculated Values for the Saugrohrdruck is compared and that the position of the first Actuator is detected, in which the deviation of the measured Saugrohrdruckes assigned to this position calculated Intake manifold pressure absolute minimum is. That way to diagnose the position of the first actuator, without that requires an air mass meter or a complicated position feedback is.

By in the subclaims listed activities are advantageous developments and improvements of the main claim specified method possible.

It is particularly advantageous if the respective intake manifold pressure is formed starting from an initial pressure value by adding a differential pressure value, the differential pressure value being determined from a difference of the charge flowing into the intake manifold and the charge flowing out of the intake manifold. In this way, the respective intake manifold pressure can be particularly easy iteratively be expected.

Advantageous is also when the effluent from the suction pipe filling for each adjustable position of the first actuator is calculated. That way you can for every adjustable position of the first actuator an associated intake manifold pressure model.

The same applies if the inflowing into the suction pipe filling for each adjustable position of the first actuator is calculated.

Especially simply the calculation of the respective intake manifold pressure, if to a linear relationship between filling and intake manifold pressure too Basically swept.

there let yourself each adjustable position of the first actuator particularly simple take into account by adding a value for Offset and / or slope of the linear relationship is specified.

One Another advantage arises when the inflowing in the suction pipe filling depends on a position of a second, the air supply into the suction pipe influencing Actuator and an inflow velocity of the air in the suction pipe for each adjustable Position of the first actuator is calculated. In this way let yourself the inflowing into the suction pipe filling especially easy and reliable model.

there can easily measure the inflow rate from a pressure ratio above that second actuator are derived.

additional precision in the determination of the inflowing into the suction pipe filling results when the flowing into the intake manifold filling dependent calculated from a temperature upstream of the second actuator becomes.

drawing

An embodiment of the invention is illustrated in the drawing and explained in more detail in the following description. Show it 1 a schematic view of an internal combustion engine and 2 a functional diagram for explaining the method and apparatus of the invention.

description of the embodiment

In 1 features 1 an internal combustion engine that drives, for example, a vehicle. The internal combustion engine 1 can be configured for example as a gasoline engine or as a diesel engine. In the following it is assumed by way of example that the internal combustion engine 1 is designed as a gasoline engine. In the present example according to 1 includes the internal combustion engine 1 with two cylinders 5 . 10 , Alternatively, the internal combustion engine could 1 include only one cylinder or more than two cylinders. About a common air supply 85 be the two cylinders 5 . 10 supplied with fresh air. The flow direction of the fresh air in the air supply 85 is indicated by an arrow. The two cylinders 5 . 10 about the common air supply 85 supplied air mass flow can be via the position of a second actuator 45 , For example, a throttle valve influence. This is the throttle 45 from a device 60 driven. In the device 60 it may, for example, be a motor control. The position of the throttle 45 is doing by the Mo gate control 60 for example, driven to implement a driver's request. The driver's request, in turn, is from the degree of activation of an in 1 derived not shown accelerator pedal. The area of air supply 85 downstream of the throttle 45 is called intake manifold and is in 1 with the reference number 15 characterized. The first common intake manifold 15 then branches into two air channels. A first air duct leads the fresh air from the common intake manifold 15 the first cylinder 5 and a second air duct leads the fish air from the common intake manifold 15 the second cylinder 10 to. In this case, the first air duct according to 1 a first air line 20 and a second air line 25 , The second air duct comprises according to 1 a third air line 30 and a fourth air line 35 , In the second air line 25 is a first charge movement flap 100 arranged. In the fourth air line 35 is a second charge movement flap 105 arranged. The two charge movement flaps 100 . 105 are rigidly connected together and form a first actuator 40 also from the engine control 60 is controlled. The activation of the first actuator 40 takes place on the part of the engine control 60 such that the two charge movement flaps 100 . 105 either both fully open or both fully closed. In a partial load range controls the engine control 60 while the first actuator 40 so on, that the two charge movement flaps 100 . 105 are completely closed, so that the resulting opening cross-section for the first air duct and the second air duct is reduced because the air in the first air duct to the first cylinder 5 only over the first air line 20 and the air in the second air passage to the second cylinder 10 only over the third air line 30 can be supplied. In full load operation of the internal combustion engine 1 however, the engine control controls 60 the first actuator 40 such that the two charge movement flaps 100 . 105 are fully open, so a maximum mögli flow through the two cylinders 5 . 10 is possible and thus by the two charge movement flaps 100 . 105 no power reduction is effected. Those for injection of fuel and for ignition of the in the cylinder 5 . 10 formed air / fuel mixture required devices are in 1 for clarity, not shown and can be formed and controlled in the art known manner. The combustion of the air / fuel mixture in the combustion chambers of the cylinders 5 . 10 formed exhaust gas is then in a common exhaust system 110 ejected, the flow direction in 1 also marked by an arrow. Inlet and exhaust valves of the two cylinders 5 . 10 are for clarity in green 1 also not shown and can be formed and controlled in the conventional manner.

In the common intake manifold 15 is an intake manifold pressure sensor 65 arranged, which measures the intake manifold pressure ps and the measured value to the engine control 60 forwards. Upstream of the throttle 45 is a second pressure sensor 95 in the common air supply 85 arranged the pressure pu upstream of the throttle 45 measures and the reading to the engine control 60 forwards. In the following, it should be assumed for the sake of simplicity that this pressure corresponds approximately to the ambient pressure. However, this assumption applies in the event that the internal combustion engine 1 for example, is charged by an exhaust gas turbocharger, no longer. Therefore, in the following, generally, the pressure pu becomes upstream of the throttle valve 45 spoken. Furthermore, upstream of the throttle 45 in the common air supply 85 a temperature sensor 90 arranged the temperature Tvdk upstream of the throttle 45 measures and the reading to the engine control 60 forwards. Via a position feedback device, for example in the form of a potentiometer, the position wdkba of the throttle valve 45 recorded and to the engine control 60 forwarded.

In 2 is a functional diagram shown, the software and / or hardware in the engine control 60 can be implemented and according to the invention a diagnosis of the position of the charge movement flaps 100 . 105 and thus the first actuator 40 allows. According to the invention, it is provided that for each adjustable position of the first actuator 40 , in the example described so for the open position and the closed position of the first actuator 40 in that an intake manifold pressure is calculated by a model that the intake manifold pressure is also measured, that the measured intake manifold pressure is compared with each of the calculated values for the intake manifold pressure and that position of the first actuator 40 is detected, in which the deviation of the measured intake manifold pressure to the associated associated with this position Saugrohrdruck amount is minimal. For this purpose, the functional diagram according to 2 a first calculation unit 115 , which is the temperature Tvdk and the pressure pu upstream of the throttle 45 are supplied as input variables. In addition, the first calculation unit 115 the position wdkba of the throttle 45 fed. Furthermore, the first calculation unit 115 a first modeled intake manifold pressure psmod1 supplied to the closed position of the first actuator 40 and thus the two charge movement flaps 100 . 105 is modeled. The first calculation unit is modeled from the mentioned input variables 115 in the manner known in the art, a first value rldkroh1 for the in the common intake manifold 15 inflowing filling. This modeling is done depending on the position wdkba the throttle 45 and an inflow velocity of the air into the common intake manifold 15 in the event that the first actuator 40 is present in its fully closed position. The said inflow rate of air into the common intake manifold 15 becomes from a pressure ratio over the throttle 45 derived, that is from the ratio of the first modeled intake manifold pressure psmod1 to the measured pressure pu upstream of the throttle 45 , The derivation of the inflow rate from said pressure ratio also takes place in a manner known to those skilled in the art. The precision of the first value rldkroh1 for those in the common intake manifold 15 inflowing filling can be increased if this in the common intake manifold 15 inflowing charge in the manner known in the art also depends on the temperature Tvdk upstream of the throttle 45 is calculated. The calculation of the common intake manifold 15 inflowing filling depending on the position wdkba the throttle 45 and the inflow velocity of the air into the common intake manifold 15 for the fully closed position of the first actuator 40 takes place in the manner known in the art. The first value rldkroh1 for in the common intake manifold 15 inflowing filling becomes a first model 50 fed. In the first model 50 a characteristic curve is created which results according to the following equation: rl1 = (psmod1 - pbrint1) · fupsrl1 (1)

Here, pbrint1 is a first value for an offset and fupsrl1 a first value for a slope of the characteristic according to equation (1). The first value pbrint1 for the offset corresponds to a residual gas content in the combustion chamber of the two cylinders 5 . 10 , The first value pbrint1 for the offset and the first value fupsrl1 for the slope of the characteristic curve according to equation (1) can be found, for example, on a test stood in the case of the fully closed first actuator 40 and thus the fully closed cargo movement flaps 100 . 105 be determined, and are in one of the engine control 60 associated memory stored. The first value pbrint1 for the offset and the first value fupsrl1 for the slope of the characteristic curve according to the equation (1) are also parameters of the first model 50 fed. Based on the last modeled intake manifold pressure psmod1, the first model is determined 50 according to the characteristic curve according to (1) a first value rl1 for from the common intake manifold 15 over the two air channels in the two cylinders 5 . 10 outflowing filling, which occurs when the first actuator is completely closed 40 and in the case of completely closed charge movement flaps 100 . 105 results. Subsequently, the first model forms 50 a first filling difference Δrl1 = rldkroh1 - rl1. This first filling difference Δrl1 is then converted into a corresponding first intake pipe pressure difference Δps1 with the aid of the characteristic curve according to equation (1) and the predetermined parameters pbrint1 and fupsrl1. This first intake manifold pressure difference Δps1 is then added to the last formed first modeled intake manifold pressure psmod1 to generate a new modeled first intake manifold pressure psmod1 at the output of the first model 50 to obtain. The output of the first model 50 Thus, the currently determined first modeled intake manifold pressure psmod1 is then applied to the first calculation unit 115 returned in the manner described with the help of the other input variables of the first calculation unit 115 a new first value rldkroh1 for those in the joint air supply 85 to determine inflowing filling. In this way, the first modeled intake manifold pressure psmod1 is iteratively formed, wherein an iteration step advantageously an ignition timing of the gasoline engine 1 equivalent. From the first modeled intake manifold pressure psmod1 is in a first subtraction member 125 the measured intake manifold pressure ps subtracted. The resulting difference is fed to a first absolute value generator, which forms the amount of this difference and to a detection unit 80 forwards.

Furthermore, the functional diagram according to 2 a second calculation unit 120 , in turn, the temperature Tvdk and the pressure pu upstream of the throttle 45 , as well as the position wdkba the throttle 45 are supplied as input variables. Furthermore, the second calculation unit 120 a second modeled intake manifold pressure psmod2 is supplied. The second modeled intake manifold pressure psmod2 results for the fully open position of the first actuator 40 and thus the fully open position of the two charge movement flaps 100 . 105 , Analogous to the first calculation unit 115 determines the second calculation unit 120 from the mentioned input values a second value rldkroh2 for the in the common intake manifold 15 inflowing filling, that for the fully opened first actuator 40 and thus the fully opened charge movement flaps 100 . 105 is characteristic. The second value rldkroh2 for the common intake manifold 15 inflowing filling becomes a second model 55 fed: the second model 55 comprises a second characteristic which is characterized according to the following equation: rl2 = (psmod2 - pbrint2) · fupsrl2 (2)

In equation (2), pbrint2 denotes a second offset value and fupsrl2 a second slope, which are specified for the characteristic curve according to equation (2). In this case, the second offset value pbrint2 corresponds to the residual gas fraction in the combustion chamber of the two cylinders 5 . 10 in the event that the first actuator 40 and thus the two charge movement flaps 100 . 105 are completely open. The second offset value pbrint2 and the second slope fupsrl2 are analogous to the first model 50 for example, also on a test bench in the case of the fully opened first actuator 40 aplitziert and in which the engine control 60 associated memory in association with the fully open position of the first actuator 40 stored. Analogous to the first model 50 determines the second model 55 from the mentioned input variables rldkroh2, pbrint2, fupsrl2, the second modeled intake manifold pressure psmod2, that at the output of the second model 55 is present and as described on the second calculation unit 120 is returned to turn a new second value rldkroh2 for the common intake manifold 15 to determine inflowing filling. From the second modeled intake manifold pressure psmod2 at the outlet of the second model 55 is then in a second subtraction member 130 subtracts the measured intake manifold pressure ps and the difference that forms becomes a second absolute value generator 75 supplied, which forms the amount of this difference and the detection unit 80 supplies.

The first subtraction element 125 thus provides a first comparison unit and the second subtraction element 130 a second comparison unit dar. This can also be the first amount 70 to be added to the first comparison unit and the second amount generator 75 can still be added to the second comparison unit. The detection unit 80 Now check which of the two values | psmod1 - ps | and | psmod2 - ps | is smaller. Is the amount | psmod1 - ps | smaller than the amount | psmod2 - ps |, the detection unit recognizes 80 that the first actuator 40 and thus the charge movement flaps 100 . 105 are in their fully closed position, otherwise, that is if the magnitude | psmod2-ps | is less than the amount | psmod1 - ps, then the detection detects unit 80 in that the first actuator 40 and thus the two charge movement flaps 100 . 105 in their fully open position. The detection unit is there 80 at its output from a detection signal D, which is set when the detection unit 80 recognizes that the first actuator 40 and thus the two charge movement flaps 100 . 105 are in their fully closed position and reset when the detection unit 80 recognizes that the first actuator 40 and thus the two charge movement flaps 100 . 105 are in their fully open position.

The inventive method described and the device according to the invention described can be correspondingly for any number of cylinders of the internal combustion engine 1 implement. Furthermore, the inventive method and the device according to the invention can be correspondingly for any number of adjustable positions of the first actuator 40 and thus the two charge movement flaps 100 . 105 implement, in which case for each of these adjustable positions, a corresponding calculation branch of the calculation unit, model, subtraction element and amount generator according to 2 is provided, whose output to the detection unit 80 leads. In addition to the complete closed position of the first actuator 40 and the complete opening of the first actuator 40 can also arbitrary positions of the first actuator 40 between the complete closure and the full opening by appropriate control of the engine control 60 be adjustable. The detection unit 80 can then from the supplied amount of amounts the smallest amount and thus the amount associated with this position of the first actuator 40 and thus the two charge movement flaps 100 . 105 detect. In a variety of possible adjustable positions of the first actuator 40 In this case, the detection signal D may have a correspondingly assigned binary code for each possible adjustable position. For the assignment of the individual amounts to the assigned positions of the first actuator 40 it is in the detection unit 80 only necessary to know which input of the detection unit 80 with which position of the first actuator 40 is linked to the minimum amount of the assigned position of the first actuator 40 to allocate correctly. This is the case in the example 2 a first with 11 marked input the amount | psmod1 - ps | and a second input with the reference numeral 22 the amount | psmod2 - ps | assigned.

This allows any number of adjustable positions of the first actuator 40 and thus the two charge movement flaps 100 . 105 detect. In this case, each of the cylinders used such a charge movement flap is assigned, so that in more than two cylinders also correspondingly more than two charge movement flaps are used.

The number of air ducts per air duct is not crucial for the function of the invention. There may also be more than two air ducts per air duct. It can also be used per air duct only a single air line, in which case in the case of a fully closed first actuator 40 the air supply to the individual cylinders is not completely interrupted, but is minimized due to a minimal opening cross-section. In the case of complete opening of the first actuator 40 There is no reduction of the air supply through the air ducts. In the event that more than two air ducts are provided per air duct, a charge movement flap is provided per air duct, that is, one air duct comprises a charge movement flap and the remaining air ducts do not comprise a charge movement flap. Alternatively, several of the air ducts of an air duct could each have a charge movement flap, in extreme cases, even all air ducts of an air duct, but then at least in one of the air ducts of the air duct even with complete closure of the charge movement flap disposed therein still air is supplied to the associated cylinder. Also, the air ducts used need not be symmetrical to the individual cylinders, that is to say that the different air ducts may differ in the number of their air ducts and also in the number of charge movement flaps used therein. In any case, it is important that all charge movement flaps used by the first actuator 40 be set synchronously, that is, that all charge movement flaps used always have the same position at the same time.

The first iteration step in the first model 50 and the second model 55 For example, can be done with switching on the ignition, which can be assumed as the output for the first modeled intake manifold pressure psmod1 and the second modeled intake manifold pressure psmod2 when switching on the ignition of the ambient pressure pu, which at this time both upstream and downstream of the throttle 45 should be approximate.

In the example above it was assumed that for the models used 50 . 55 the given parameters, pbrint1 and pbrint2 and fupsrl1 and fupsrl2 are different. It can also be that the models 50 . 55 only in the specification of one of the two parameters However, the other parameter is the same for both models. So can the two models 50 . 55 For example, in parameter pbrint1 or pbrint2 differ, but fupsrl1 can be equal to fupsrl2. Conversely, the two models can 50 . 55 for example, in the parameters fupsrl1 and fupsrl2, where the parameters pbrint1 and pbrint2 are the same.

In general, it can thus be provided that for each adjustable position of the first actuator 40 a value for the offset and / or the slope of the linear relationship according to the predetermined for example by equations (1) and (2) characteristics is specified. In general, it is crucial that there are no two models among all models where the default values for the offset are the same and where the given values for the slope are the same. In this case, namely, the two associated adjustable positions of the first actuator could be 40 no longer distinguish each other. If only one value for the offset is specified for the different models used, then no two of the models used must have the same value for the offset. If only one value for the slope is given for the different models, then it must be ruled out that there are two models with the same given slope of the linear relationship. Thus, for example, different values for the offset at the same predetermined pitch or different values for the pitch at the same predetermined offset can be used for the individual models.

Depending on whether the internal combustion engine 1 is to be operated in a partial load operating state or at full load, controls the engine control 60 the first actuator 40 different. In partial load operation, the engine control 60 the first actuator 40 in such a way that it is completely closed, in the full load operating range becomes the engine control 60 the first actuator 40 such that it is fully open. Thus results for the partial load operation as a desired position for the first actuator 40 a full closure and in the full load operating range as a target position a complete opening of the first actuator 40 , Corresponds to the nominal position of the first actuator 40 in the corresponding operating state, not that of the detection unit 80 detected position, so we made a mistake in the engine control 60 detected and this error can be reproduced optically and / or acoustically. In addition, an emergency operation of the internal combustion engine could 1 be initiated, for example, in a reduction of a desired value for an output of the internal combustion engine 1 , For example, a torque or power results. In the final analysis, the internal combustion engine could 1 in case of failure also be switched off.

Through the first actuator 40 In addition to or instead of the charge movement flaps, at least one intake valve of the two cylinders can also be provided 5 . 10 in particular for switching off at least one of the cylinders 5 . 10 and / or at least one resonance flap in the common intake manifold 15 be operated in particular to increase the air pulsation. According to the above for the cargo movement flaps 100 . 105 described method can then be in an analogous manner, the position of the first actuator 40 detect.

Claims (10)

Method for operating an internal combustion engine ( 1 ) with at least one cylinder ( 5 . 10 ), by a suction tube ( 15 ) via at least one air channel ( 20 . 25 ; 30 . 35 ) Is supplied with air, wherein a first actuator ( 40 ) is provided, which in different positions the opening cross-section of the at least one air channel ( 20 . 25 ; 30 . 35 ) sets different, characterized in that for each adjustable position of the first actuator ( 40 ) by means of a model ( 50 . 55 an intake manifold pressure is calculated, that the intake manifold pressure is measured, that the measured intake manifold pressure is compared with each of the calculated values for the intake manifold pressure, and that the position of the first actuator ( 40 ), in which the deviation of the measured intake manifold pressure to the calculated intake manifold pressure associated with this position is minimal in absolute value. A method according to claim 1, characterized in that the respective intake manifold pressure is formed from an initial pressure value by adding a differential pressure value, wherein the differential pressure value from a difference in the intake manifold ( 15 ) inflowing filling and from the suction tube ( 15 ) outflowing filling is determined. A method according to claim 2, characterized in that from the suction tube ( 15 ) outflowing filling for each adjustable position of the first actuator ( 40 ) is calculated. A method according to claim 2 or 3, characterized in that in the suction pipe ( 15 ) inflowing filling for each adjustable position of the first actuator ( 40 ) is calculated. Method according to one of claims 2 to 4, characterized that for the calculation of the respective intake manifold pressure a linear relationship between stuffing and intake manifold pressure is used. A method according to claim 5, characterized gekenn records that for each adjustable position of the first actuator ( 40 ) a value for offset and / or slope of the linear relationship is given. Method according to one of claims 2 to 6, characterized in that in the suction pipe ( 15 ) inflowing charge depending on a position of a second, the air supply into the intake manifold ( 15 ) influencing actuator ( 45 ) and an inflow velocity of the air into the suction tube ( 15 ) for each adjustable position of the first actuator ( 40 ) is calculated. A method according to claim 7, characterized in that the inflow velocity from a pressure ratio across the second actuator ( 45 ) is derived. A method according to claim 7 or 8, characterized in that in the suction tube ( 15 ) inflowing depending on a temperature upstream of the second actuator ( 45 ) is calculated. Contraption ( 60 ) for operating an internal combustion engine ( 1 ) with at least one cylinder ( 5 . 10 ), by a suction tube ( 15 ) via at least one air channel ( 20 . 25 ; 30 . 35 ) Is supplied with air, wherein a first actuator ( 40 ) is provided, which in different positions the opening cross-section of the at least one air channel ( 20 . 25 ; 30 . 35 ), characterized in that models ( 50 . 55 ) are provided for each adjustable position of the first actuator ( 40 ) calculate an intake manifold pressure that measuring means ( 65 ) are provided, which measure the intake manifold pressure, that comparison means ( 70 . 125 ; 75 . 130 ) are provided, which compare the measured intake manifold pressure with each of the calculated values for intake manifold pressure, and that detection means ( 80 ) are provided which the position of the first actuator ( 40 ), in which the deviation of the measured intake manifold pressure to the calculated intake manifold pressure associated with this position is minimal in terms of amount.