DE102005040780B4 - Method and engine control unit for increasing the availability of motor vehicle engines - Google Patents

Abstract

Method for controlling a motor vehicle drive, wherein the motor vehicle drive has at least one internal combustion engine and at least one electric motor, wherein in a first step at least one engine nominal torque (140) is calculated and in a second step the at least one engine nominal torque (140) is converted into at least one engine driver variable (158) and that further in the first step at least one electric motor target torque (142) is calculated, which is converted into at least one Elektromotoransteuergröße (162) in the second step, that at least one actual torque (132; 168, 170) of the motor vehicle drive is determined a comparison between at least one actual torque (168) of the at least one internal combustion engine and the at least one engine nominal torque (140) and a comparison between at least one actual torque (170) of the at least one electric motor and the at least one electric motor Sollmo 142 (142) is performed, characterized in that at a predetermined combustion engine threshold exceeding deviation of the at least one actual torque (168) of the at least one internal combustion engine from the at least one engine target torque (140) is switched to a Verbrennungsmotorfehleransteuerbetrieb (138), wherein the at least an internal combustion engine drive variable (158) is replaced by at least one internal combustion engine drive variable, and that at a deviation of the at least one actual torque (170) of the at least one electric motor from the at least one electric motor target torque (142) is switched to an electric motor fault drive operation (138) the at least one electric motor drive variable (162) is replaced by at least one electric motor drive control variable.

Description

The invention relates to a method for controlling a motor vehicle drive, in particular a hybrid drive. Furthermore, the invention relates to a motor control device for implementing the method according to the invention in one of its embodiments.

State of the art

In the prior art (eg DE 103 20 017 A1 ) Control devices for a drive unit are known which control or regulate the drive unit, in particular with regard to a given drive torque, wherein the drive unit is an internal combustion engine of a motor vehicle. In this case, the motor vehicle usually comprises a driver request recording device which can be actuated by the driver of the motor vehicle, in particular a foot-operated accelerator pedal which is provided to emit an output signal representing a current actuation state of the driver request recording device. A control unit receives the output signal from the driver request recording device and assigns to the received output signal at least one desired output variable, in particular a desired drive torque of the drive unit. The drive unit is controlled by the control unit in such a way that an actual output quantity output by the drive unit approaches the desired output variable. Such control devices are known in various interpretations for conventional motor vehicle engines, in particular gasoline engines and diesel engines, such. For example, the Bosch Engine Control System with Electronic Accelerator (EGAS).

Furthermore, it is known in the prior art to perform a continuous torque monitoring to detect malfunctions in the control unit. This serves in particular for the protection of passengers in the motor vehicle and external road users. It is to prevent unwanted acceleration of the vehicle. The core of continuous torque monitoring is the comparison of an actual torque provided by the motor with an allowable torque. Normally, the actual torque is smaller than the permissible torque. If the actual torque exceeds the allowable torque, there is a fault in the engine control unit and an error response leading to a safe vehicle condition is initiated. The monitoring of the engine control units usually takes place according to a 3-level monitoring concept. The engine control itself, in particular the specification of the desired torque, takes place in the first plane designated as the functional plane. The second level (monitoring level) is executed as the continuous torque monitoring. In this level, among other things, a permissible torque is determined as a function of vehicle and engine functions and compared with an actual engine torque. Level 2 is extensively secured (double storage of all variables, cyclic RAM and ROM check, program sequence check, command test). Level 3 is used for computer backup.

DE 102 10 684 A1 relates to a method for monitoring a moment of a drive unit of a vehicle. The torque to be monitored is compared with a permissible torque, the permissible torque is readjusted to the torque to be monitored and an error is detected if the torque to be monitored deviates more than a first predetermined value from the permissible torque, the error only in that case is detected, in which a position of a control element, in particular an accelerator pedal position, at least for a first predetermined time is within a predetermined tolerance range.

DE 197 39 565 A1 relates to a method for controlling the torque of a drive unit of a motor vehicle, wherein the torque of the drive unit is set at least in accordance with the driver's request, wherein the actual torque of the drive unit is determined and at least on the basis of the driver's request, a maximum allowable torque is determined. There is a torque reduction and / or limitation when the maximum permissible torque is exceeded by the actual torque. In this case, at least one operating state is determined, in which the torque of the drive unit is increased by additional load. During this at least one operating state, the maximum permissible torque is increased. In particular, the permissible torque is thereby increased during operation with a cold drive unit and / or load-consuming consumers during operation.

DE 197 48 355 A1 has a method for controlling the drive unit of a vehicle to the subject, wherein the torque of the drive unit depending on a derived from the position of a driver operable control element driver command torque and depending on at least one target torque, which is predetermined by at least one external function, instead of or in addition to driver specification affects the torque. A maximum permissible torque is specified and when this maximum permissible value is exceeded, a reduction of the torque is made by the corresponding actual value. The maximum permissible torque is at least formed depending on the position of the operating element and the maximum permissible torque is formed depending on the desired torque of at least one external function, if this setpoint torque is greater than the permissible torque dependent on the control element position. The external function can, for. B. increase the torque over the driver's request, such as a motor drag torque control or a vehicle speed control.

From the DE 198 29 303 A1 a method is known for a gasoline engine, in which a deterioration of the driving characteristics due to lean combustion is prevented in gasoline engine. For this purpose, a target engine torque tTe is calculated as a function of an operating condition of the engine, while an actual engine torque Te actually applied by the engine is detected. Furthermore, an error quantity ΔTQ = Te-tTe is calculated. If the error quantity ΔTQ is equal to or greater than a predetermined value, the lean burn is inhibited.

From the DE 196 24 822 C1 a safety system for a motor vehicle with internal combustion engine known. It is proposed to use independent quantities for motor control and for monitoring the motor control. The control of the internal combustion engine via an operating condition of the internal combustion engine characterizing operating parameters - for example, the engine load. The monitoring of the engine control, however, takes place on the basis of a characteristic of the vehicle propulsion size - for example, the vehicle output torque, which is determined on the basis of a wheel speed. From the accelerator pedal position setpoint values for the engine control and for the monitoring are determined. The acquisition of the corresponding actual values is based on independent input variables.

From the DE 195 36 038 A1 a method for controlling a drive unit of a motor vehicle is known in which the maximum permissible torque or the maximum permissible power is determined and at least one fault reaction is initiated when this limit value is exceeded by a calculated actual torque or power value.

The described, from the prior art known methods of torque monitoring are not readily transferable to hybrid vehicles. In hybrid vehicles, at least one additional torque source (motor) is used in addition to an internal combustion engine. In most cases this is an electric drive.

In the prior art, there is only one engine in a vehicle that includes an engine controller that receives a variety of torque request information from an external source (eg, by a brake controller or an ACC) over a signal bus. The engine controller checks the integrity of the received external torque request signals and plausibility of the torque request information based on available vehicle status signals. The engine control unit then determines, based on the external information and other signals (including the driver's request, which is set by the accelerator pedal, for example) the torque (desired torque) to be requested by the engine and accordingly directly drives the engine without communicating with another control unit ,

In the engine control, the torque required by the driver, which is set, for example, by operating an accelerator pedal, must be divided among the existing torque source (at least two motors) for several existing engines. This is done depending on numerous environmental variables, including the goal of setting the most fuel-efficient operating point for all torque sources. Such a method is for example in DE 102 02 531 A1 described. The divided moments must then be transmitted from the engine control unit, where appropriate, to further, the individual motors associated with control units.

In order to increase the availability of an engine, in the prior art, in addition to the continuous torque monitoring in level 2, the requested torque is checked for plausibility prior to driving the engine in level 1. If the calculated desired torque to be requested is marked too high, the torque is limited to a plausible torque. By means of this torque limitation, the above-described error reaction triggered in level 2 of the monitoring concept can be avoided, even if the torque to be requested is too high. Such an error reaction should be avoided as far as possible, since it can be very uncomfortable for an occupant of the vehicle.

Such a torque limit is barely noticeable to the driver of the vehicle, so that the loss of comfort is minimal. A shortcoming of this method from the prior art, however, is that although errors in the calculation of the setpoint torque are intercepted, but that errors in the implementation of the limited setpoint torques in corresponding actual moments are no longer recognized and prevented. Such a faulty conversion of the setpoint torque into an actual moment again leads to an uncomfortable error reaction that should be avoided.

Advantages of the invention

Therefore, a method for controlling a motor vehicle drive is proposed which avoids the disadvantages of the methods known from the prior art. The method is particularly suitable for reliably intercepting errors in the implementation of a desired torque in control variables, whereby the availability of the motor vehicle is increased. The inventive method is also suitable for the operation of a hybrid vehicle, with the possibility already in level 1 to determine the faulty torque adjuster and to choose an appropriate operating strategy before the level 2 error response operation is triggered.

A basic idea of the invention is the testing of the conversion of a setpoint torque into control variables and an actual moment in the first level designated as the function level. Thus, errors in the calculation of the control variables can be intercepted.

As with methods known from the prior art, in the method according to the invention for operating a motor vehicle drive in a first step, at least one desired torque is calculated. In a second step, the at least one desired torque is converted into at least one drive variable for the motor vehicle drive.

A core element of the present invention is to determine at least one actual torque, ie an actual moment of the motor vehicle drive in the first, the functional level and then to perform a comparison between the at least one actual torque torque and the at least one desired torque. Exceeds the deviation between the at least one actual torque and the at least one desired torque a predetermined threshold, it is switched to a fault drive operation, in which the at least one control variable is replaced by at least one Ersatzansteuergröße. The predetermined threshold can be chosen arbitrarily and also assume the value zero. Thus, even with very small deviations, the at least one control variable can be replaced by the at least one substitute control variable. A replacement control can z. B. consist in that changes the operating strategy of the hybrid vehicle from hybrid to pure combustion engine drive.

The at least one actual moment can be obtained from different sources. Thus, in internal combustion engines (eg in diesel engines with diesel injection systems) a measurement of internal cylinder pressures is recommended. These internal cylinder pressures can in turn be converted into torques. Alternatively or additionally, in internal combustion engines from the oscillation of a rotational speed signal of a crankshaft and / or camshaft to a torque can be deduced. Furthermore, in the case of internal combustion engines and / or electric motors, it is possible to calculate back to the torques from the control variables (in level 1 and / or in level 2). Alternatively or additionally, in the case of electric motors, it is possible to calculate the torque back from the motor current, motor voltage and speed. If external torque actuators are used to set a torque, then, for example via a bus system, feedback can be sent to the engine control unit, which contains information about the torque. Finally, alternatively or additionally, torque sensors can be applied to the crankshaft in most types of engines, which sensors detect the torques directly and report them back to the engine control unit as an actual torque.

The method described for operating a motor vehicle drive can be advantageously developed in various ways. Thus, in addition to the already described comparison of the actual torque with a desired torque, an additional, preceding comparison step can also be carried out in which the calculated target torque is checked by comparing this with at least one permissible torque. When the permissible torque is exceeded by the calculated setpoint torque, the calculated setpoint torque is replaced by a fault setpoint torque. For example, in this comparison step, the calculated target torque can be replaced in each case by the smaller of the two values, namely the calculated target torque and the permissible torque.

This development of the method according to the invention combines the control method known from the prior art for checking the calculated moments with the method according to the invention, in which the actual moments are checked and monitored. Thus, this method provides protection against errors occurring, since now errors in the functional level (first level) can be detected and compensated, without necessarily switching immediately to the level 2 uncomfortable fault reaction mode.

In a further embodiment of the method, the comparison of the at least one actual torque and the at least one desired torque is carried out with the aid of filters and / or dead-time elements. In this way, for example, runtime differences can be compensated and time differences, which are due to a time-delayed implementation of the drive signals in corresponding engine torques.

The method according to the invention can be used particularly advantageously for hybrid drives. In this case, the motor vehicle drive has at least one internal combustion engine and at least one further motor, preferably an electric motor. In the following, the at least one further motor will be referred to as an electric motor, whereby mutatis mutandis hybrid drives with other types of engines as another engine to be covered by the invention.

Instead of at least one calculated desired torque, at least two desired torques are now calculated in the first method step: at least one engine nominal torque and at least one electric motor nominal torque. These are converted in the second method step into corresponding control variables, namely at least one internal combustion engine control variable and at least one electric motor control variable.

In hybrid drives, the actual torque (actual moment) is composed of individual torques of the motors, that is to say of the at least one internal combustion engine and of the at least one electric motor. The inventive method generates separate control variables for these individual torque controllers, which may have separate engine control units.

For fault diagnosis, a comparison can now be made between the setpoint torques of the individual motors and the actual moments of these motors. Thus, a comparison is made between the at least one actual torque of the at least one internal combustion engine and the at least one engine nominal torque and, analogously, a comparison between at least one actual torque of the at least one electric motor and the at least one electric motor nominal torque. By means of this method, it is possible in particular to diagnose in which torque controller a possible error has occurred.

Depending on which torque controller an error has been detected, an operating mode can be selected which responds to this error and is adapted. Thus, for example, in the case of a deviation of the at least one actual torque of the at least one internal combustion engine that exceeds a predefined combustion engine threshold, it is possible to switch over from the at least one internal combustion engine desired torque to an internal combustion engine fault control operation. In this engine failure driving operation, the at least one engine control amount is replaced with at least one engine replacement drive amount. In addition, other control variables can be replaced by Ersatzansteuergrößen. Similarly, when a deviation of the at least one actual torque of the at least one electric motor exceeding a predetermined electric motor threshold is detected by the at least one electric motor target torque, an electric motor fault drive operation is switched over. In this electric motor fault driving operation, the at least one electric motor drive amount is replaced by at least one electric motor drive drive amount. Again, additional control variables can be replaced by Ersatzansteuergrößen.

These Ersatzansteuergrößen can be configured in various ways. Thus, these Ersatzansteuergrößen example cause a particularly low moment of the respective affected by the error engines. In particular, these can also trigger a complete shutdown of each affected by the fault motors, so that, for example, in the engine fault drive operation, the at least one internal combustion engine is completely switched off and the electric motor fault driving operation of the at least one electric motor is completely switched off. In this way, for example, in the engine fault control operation can be switched to a purely electric driving, so that the at least one torque controller of the at least one electric motor now takes over the tasks of at least one torque controller of the internal combustion engine. In this way, errors can be compensated complementarily. The case perceived by the driver of the motor vehicle comfort loss is extremely low. In this way, errors in the torque conversion of hybrid drives can be detected and compensated particularly effectively and efficiently, without having to switch to a fault reaction mode of level 2. In addition, however, the driver may also be informed of the occurring error, for example by a corresponding cockpit display, which indicates the driver that a visit to a workshop in the near future is required.

list of figures

Reference to the drawings, the invention will be explained in more detail below.

• 1 ein Flussdiagramm eines dem Stand der Technik entsprechenden Verfahrens zur Momentenüberwachung mit einer Momentenbegrenzung in Ebene 1;
• 2 eine Ausgestaltung eines erfindungsgemäßen Verfahrens mit einer Prüfung der Umsetzung der Sollmomente; und
• 3 ein zu 2 analoges Verfahren in einem Hybridantrieb.

It shows:

• 1 a flowchart of a prior art method for torque monitoring with a torque limit in level 1;
• 2 an embodiment of a method according to the invention with an examination of the implementation of the desired moments; and
• 3 one too 2 analogous method in a hybrid drive.

Exemplary embodiments

In 1 a method according to the prior art is shown, in which by means of a so-called torque limitation in level 1 (reference numeral 110 in 1 ) erroneously high moments are detected.

The method is divided into two consecutive process steps, which here symbolically through the dividing line 112 are separated. The dividing line 112 separates the moment calculation (reference number 110 ) of the torque conversion (reference numeral 114 ). In the moment calculation 110 are initially made of different input variables 116 in a calculation step 118 setpoint torques 120 calculated. For example, the input variables 116 contain electronic information of an accelerator pedal, via which the desire of a driver with respect to a certain torque is transmitted to an engine control unit. In the calculation step 118 become these input variables 116 in corresponding desired moments 120 transformed. For example, this conversion may be in step 118 take place continuously or at predetermined time intervals. The conversion in step 118 For example, it can be done with the aid of characteristic fields, functions, or electronic tables.

The way in step 118 generated target moments 120 be in a moment limit 122 with allowable moments 124 compared. If it is determined that the calculated target moments 120 these permissible moments 124 exceed, then the target moments 120 replaced by fault setpoints. For example, these fault setpoints may be the allowable moments 124 act. The way in the torque limit 122 generated limited target moments 126 thus do not exceed the permissible moments 124 ,

By means of these limited target moments 126 is then the torque conversion (reference numeral 114 ) a conversion step 128 carried out. In this implementation step 128 become the limited target moments 126 in control variables 130 transformed. With these control variables 130 For example, these may be electronic signals which are applied to moment adjusters of a motor vehicle drive (in FIG 1 not shown). The control variables 130 thus provide for error-free operation of the implementation step 128 the "hardware analogue" to the limited setpoint torques 126 represents.

This in 1 illustrated, the prior art corresponding method can be accommodated for example in a conventional engine control unit. For example, this engine control device may include a microcomputer and other electronic components. The engine control unit does not necessarily have to be integrated in an electronic unit, but can also be housed decentrally in the motor vehicle, for example. Advantageously, in the moment calculation (reference numeral 110 ) executed process steps wholly or partially designed as a computer program, the computer program, for example, the input variables 116 in the calculation step 118 in the target moments 120 converts. Also the torque limit 122 can be realized by a computer program. Alternatively or additionally, this torque limit 122 However, also be implemented by a corresponding electronic circuit, for example, an electronic comparison circuit, by means of which the desired torques 120 with the permissible moments 124 be compared and the minimum of these two values 120 . 124 as a limited target torque 126 is forwarded.

Similarly, in the torque conversion (reference numeral 114 ) illustrated conversion step 128 wholly or partly realized in an engine control unit. In particular, this process step 128 again be implemented in whole or in part in a microcomputer of the engine control unit. This microcomputer can be the same microcomputer which is also used for the moment calculation (reference numeral 110 ), or it may be a separate microcomputer. Furthermore, alternatively or additionally, electronic components can be used. For example, for generating the drive variables 130 corresponding electronic converters, filters, power amplifiers or the like can be used, so that suitable control variables 130 are generated for moment adjuster of the motor vehicle drive. These control variables 130 can be transmitted via a corresponding line system, for example, suitable interface cable (BUS system) to the or the moment adjuster of the motor vehicle.

As described above, this suffers in 1 illustrated, prior art method lacking, that although errors in the moment calculation 110 , so errors, which in the calculation step 118 in the calculation of the setpoint moments 120 occur, be detected and compensated. A control of the implementation of these target moments 120 or the limited target moments 126 in the implementation step 128 the moment implementation 114 in appropriate control variables 130 does not happen.

In contrast, in 2 an embodiment of a method according to the invention for engine control shown, which the described disadvantages of the method according to 1 avoids. In the method according to the invention are first in the moment calculation 110 analogous process steps as in the method according to 1 carried out. Accordingly, in a calculation step 118 from input variables 116 first target moments 120 calculated. These setpoint moments are in a torque limit 122 with allowable moments 124 compared. Accordingly, analogous to the method described above, limited set torques 126 which ensures that these are not the permissible moments 124 exceed. These limited target moments 126 become the moment implementation 114 handed over to there in an implementation step 128 analogous to 1 in control variables 130 to be converted for at least one moment master.

In the inventive method according to 2 However, in addition, there is a feedback of actual moments 132 from the torque adjusters to the engine control unit. These are actual moments 132 are in the form of signals for determining the actual moments 134 detected, which, as described above, for example, include the signals of corresponding torque sensors on a crankshaft. These signals 134 can be converted accordingly to subsequently as actual moments 132 with the corresponding limited target torques 126 to be compared. If necessary, runtime differences, which can be achieved, for example, by time-delayed implementation of the limited setpoint torques 126 in corresponding actual moments 132 be compensated by filters and dead-time links (not shown) before the comparison with the limited target torques 126 is carried out.

This comparison between the actual moments 132 and the limited target moments 126 will be in an exam to implement the target moments 136 in the moment implementation 114 carried out. Be implausible actual moments 132 has been determined, it can be switched to a comfortable alternative mode instead of switching to the above EMB operation. By "implausible moments" can be understood, for example, that if the actual moments 132 by more than a predetermined tolerance threshold from the limited target torques 126 deviate to an error control operation 138 is switched. In this fault control operation, in particular the control variables 130 be replaced by appropriate Ersatzansteuergrößen.

In 3 a preferred embodiment of a method according to the invention is shown in which the in 2 illustrated method for the operation of a hybrid drive has been modified. Analogous to 2 In turn, input variables, for example signals of an accelerator pedal and / or other signals, are converted into setpoint moments in a calculation step. It is assumed that the hybrid drive in this embodiment has an internal combustion engine and an electric motor. Accordingly, in the calculation step, a target engine torque and a target electric motor torque are generated. The distribution of the moments to these individual moments can be optimally adapted to the operating state, so that in particular an energy-saving operation is possible.

Corresponding 2 These individual setpoint moments can be compared in a torque limitation with allowable moments. In this way, a limited internal combustion engine Sollmoment 152 and a limited electric motor target torque 154 is generated. The limited target moments 152 . 154 will be followed by the momentum conversion 114 to hand over.

Analogous to 2 takes place in the moment implementation 114 an implementation of the limited target moments 152 . 154 in control variables. This implementation is divided into two to meet the requirements of the hybrid drive. So is in a moment implementation of the internal combustion engine 156 the limited engine torque 152 in an engine control quantity 158 transformed. These engine control variables 158 can then be forwarded to one or more internal combustion engines. Analog is in a torque reduction of the electric motor 160 the limited electric motor target torque 154 in corresponding Elektromotoransteuergrößen 162 converted, which in turn are forwarded to one or more electric motors.

Analogous to 2 takes place in the embodiment according to 3 again a feedback of actual moments for error adjustment. This feedback takes place, according to the nature of the hybrid drive, via signals for determining the actual moments of the internal combustion engine or electric motor 164 . 166 .. Analogous to step 132 in 2 become the signals 164 . 166 in an actual moment 168 of the internal combustion engine and an actual moment 170 the electric motor converted. Again, a delay and filtering of the signals can take place.

Subsequently, the actual moments 168 . 170 in an examination of the implementation of the target moments 136 with the limited target moments 152 . 154 compared. This exam 136 in the embodiment according to 3 is more complex than the test due to the doubling of the number of signals 136 in 2 , For example, the actual moment 168 of the internal combustion engine with the limited internal combustion engine target torque 152 be compared and parallel the actual moment 170 of the electric motor with the limited electric motor target torque 154 , If, in one or both cases, deviations are ascertained which in each case exceed predefined tolerance thresholds (which in turn can be configured as desired and, in particular, can be zero), an error triggering operation is used 138 switched.

In this fault drive operation 138 can control variables 158 . 162 each be replaced by appropriate Ersatzansteuergrößen. For example, as described above, upon detection of a fault in the internal combustion engine, the engine may be controlled by the engine control quantities 158 are completely switched off, whereas the electric motor drive variables 162 can be modified accordingly, so that the electric motor takes over the failure of the engine. Thus, the total torque of the motor vehicle drive can be kept constant, for example, despite failure of one of the two motors, so that a driver of the motor vehicle perceives no change. Again, the fault drive operation can 138 but also an error message z. B. on a display or acoustic type to stop a driver to visit a workshop.

LIST OF REFERENCE NUMBERS

110

torque calculation

112

parting line

114

moment implementation

116

input variables

118

calculation step

120

setpoint torques

122

torque limit

124

permissible moments

126

limited target moments

128

conversion step

130

control variables

132

Is Moments

134

Signals for determining the actual moment

136

Checking the implementation of the set torques

138

Fehleransteuerbetrieb

152

limited engine torque

154

limited electric motor target torque

156

Torque conversion internal combustion engine

158

Verbrennungsmotoransteuergrößen

160

Torque conversion electric motor

162

Elektromotoransteuergrößen

164

Signals for determining the actual torque of the internal combustion engine

166

Signals for determining the actual torque of the electric motor

168

Actual moment internal combustion engine

170

Actual moment electric motor

Claims (6)

Method for controlling a motor vehicle drive, wherein the motor vehicle drive has at least one internal combustion engine and at least one electric motor, wherein in a first step at least one engine nominal torque (140) is calculated and in a second step the at least one engine nominal torque (140) is converted into at least one engine driver variable (158) and that further in the first step at least one electric motor target torque (142) is calculated, which is converted into at least one Elektromotoransteuergröße (162) in the second step, that at least one actual torque (132; 168, 170) of the motor vehicle drive is determined a comparison between at least one actual torque (168) of the at least one internal combustion engine and the at least one engine nominal torque (140) and a comparison between at least one actual torque (170) of the at least one electric motor and the at least one electric motor Sollmo 142 (142) is performed, characterized in that at a predetermined combustion engine threshold exceeding deviation of the at least one actual torque (168) of the at least one internal combustion engine from the at least one engine target torque (140) is switched to a Verbrennungsmotorfehleransteuerbetrieb (138), wherein the at least an internal combustion engine drive variable (158) is replaced by at least one internal combustion engine drive variable, and that at a deviation of the at least one actual torque (170) of the at least one electric motor from the at least one electric motor target torque (142) is switched to an electric motor fault drive operation (138) the at least one electric motor drive variable (162) is replaced by at least one electric motor drive control variable. Method according to the preceding claim, characterized in that in addition at least a calculated desired torque (120; 140, 142) having at least a permissible torque (124; 148, 150) is compared and that when the permissible torque (124; 148, 150 ) the calculated target torque (120; 140, 142) is replaced by a fault set torque (124; 148, 150). Method according to one of the two preceding claims, characterized in that the at least one actual torque (132; 168, 170) is determined by at least one of the following methods: a measurement of a cylinder internal pressure; an oscillation of a speed signal of a crankshaft; a conversion of the at least one control variable; a conversion of current, voltage and speed of an electric motor; by feedback via a BUS system; by at least one torque sensor on a crankshaft or camshaft. Method according to one of the preceding claims, characterized in that the at least one actual torque (132; 168, 170) and / or the at least one desired torque (120; 140, 142) is filtered prior to carrying out the comparison and / or time-delayed by means of a deadtime element become. A method according to the preceding claim, characterized in that in the engine fault drive operation (138) the at least one internal combustion engine is completely shut down and that in the electric motor fault drive operation (138) the at least one electric motor is completely switched off. Motor control device with means for carrying out a method according to one of the preceding method claims.

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