Method for operating a motor vehicle drive device of a motor vehicle and corresponding motor vehicle drive device

Abstract

The invention relates to a method for operating a motor vehicle drive system of a motor vehicle (1), comprising a drive device, which is drivingly connected to at least one wheel (9) of the motor vehicle (1) via a torque transmission device at least for a short time, and a parking lock device, in a first setting state, the parking lock device fixes a locking element in a form-fitting manner, which locking element is coupled to the torque transmission device in a rotationally fixed manner, and in a second setting state, the parking lock device releases the locking element, when the parking lock device is switched from the first setting state to the second setting state, a compensation torque acting on the locking element is generated by means of the power device, which compensation torque counteracts a loading torque caused by the loading torque transmission device when the locking element is fixed. According to the invention, the compensation torque is determined as a function of a torsional stiffness of the torque transmission device and a rotational angle of the torque transmission device, which is determined after the locking element is fixed. The invention also relates to a motor vehicle power transmission device (1) for a motor vehicle.

Description

Technical Field

[0001] The invention relates to a method for operating a motor vehicle power transmission device of a motor vehicle, the motor vehicle power transmission device having a motor and a parking lock device, the motor being at least temporarily connected to at least one wheel of the motor vehicle in a driving manner via a torque transmission device, the parking lock device fixing a locking element in a form-fitting manner in a first setting state, the locking element being connected to the torque transmission device in a non-rotatable manner, the parking lock device releasing the locking element in a second setting state, and generating a compensating torque acting on the locking element by means of a power device when the parking lock device switches from the first setting state to the second setting state, the compensating torque reacting to a loading torque caused by the loading torque transmission device when fixing the locking element. The invention also relates to a motor vehicle power transmission device for a motor vehicle. Background Art

[0002] For example, the document DE 10 2010 011 557 A1 is known from the prior art. This document discloses a motor vehicle drivetrain device having a parking lock device, which is configured to lock a motor vehicle drivetrain at least partially in a topographically locking manner, and a control and / or regulating unit, which is configured to set a defined drive torque in at least one operating state. It is provided that the control and / or regulating unit is configured to set a compensating drive torque in order to release the parking lock device in order to reduce the load torque on the drivetrain.

[0003] In addition, document DE 10 2019 219 670 A1 discloses a transmission for a motor vehicle, which includes a parking lock device, which is designed to lock a moving element of the transmission device at least temporarily and / or as required in the engaged state of the parking lock device, and to release the moving element in the disengaged state of the parking lock device, wherein the transmission device is designed to generate a defined torque by means of an electric motor assigned to the transmission device in order to disengage the parking lock device, wherein the transmission device is designed to release the connection between the locking element of the transmission device and the corresponding element to be locked by generating the defined torque, wherein the parking lock device is designed to transition at least one locking element to a disengaged state when the defined torque is present. Summary of the invention

[0004] The object of the present invention is to propose a method for operating a motor vehicle drive train of a motor vehicle, which has advantages over known methods, in particular a high-precision determination of the compensation torque, thereby avoiding a sudden unloading of the torque transmission device when releasing the parking lock device, i.e. when releasing the locking element by the parking lock device.

[0005] This is achieved according to the invention by a method for operating a motor vehicle drivetrain of a motor vehicle having the features of claim 1. Provision is made here for the compensation torque to be determined as a function of the torsional rigidity of the torque transmission device and the rotation angle of the torque transmission device determined after fixing the locking element.

[0006] Advantageous designs and suitable improvements of the invention are given in the dependent claims. It should be pointed out that the embodiments described in the description are non-limiting; on the contrary, any changes to the features disclosed in the description, claims and drawings are possible.

[0007] The method described is used for operating a motor vehicle drive train. The motor vehicle drive train is preferably a component of the motor vehicle, but can of course also exist independently of the motor vehicle. The motor vehicle drive train is used to establish a drive connection between the wheels of the motor vehicle and a drive unit of the motor vehicle, at least temporarily. The drive unit is used to drive the motor vehicle, that is, to this extent, to provide a drive torque intended to drive the motor vehicle. To provide the drive torque, the drive unit has at least one drive unit, which is designed, for example, as an internal combustion engine or an electric machine, more precisely as a power motor.

[0008] The power unit is at least temporarily connected to at least one wheel of the motor vehicle via a torque transmission device of the motor vehicle drive train in a driving manner so that a torque, in particular a drive torque, is transmitted between the power unit and the wheel. In this case, a torque transmission device is any component that can be used to transmit a torque between the power unit and the wheel of the motor vehicle. In the simplest case, the torque transmission device is a shaft. Particularly preferably, the torque transmission component has a shiftable transmission, by means of which different gears or transmission ratios can be set between the power unit and the wheel.

[0009] In addition to the torque transmission device, the motor vehicle drive train has a motor. Preferably, the motor is a component of the already mentioned power unit, so that in this case the motor vehicle drive train also includes a component of the power unit of the motor vehicle. Particularly preferably, the motor corresponds to the power unit of the power unit, in particular the power motor. Alternatively, however, the motor can also be present independently of the power unit and be designed, for example, as a separate electric machine.

[0010] Furthermore, the parking lock device is a component of the power transmission of the motor vehicle. The parking lock device is used to lock the torque transmission device by temporarily fixing a locking element which is connected to the torque transmission device in a rotationally fixed manner. The locking element is preferably permanently connected to the wheel in a driving manner via the torque transmission device. For example, the locking element is present as a parking lock wheel, such as a locking ratchet, a tooth clutch wheel or a gear, which is rigidly connected to the shaft of the torque transmission device.

[0011] The parking lock device can be used to immobilize a motor vehicle in a stationary state. When the motor vehicle is stationary, the parking lock device is activated and locks the torque transmission device, so that the wheels of the motor vehicle are also immobilized. For this purpose, in a first setting state of the parking lock device, the locking element acts on the locking element or interacts with the locking element in a form-fitting manner to fix the locking element and accordingly prevents a rotational movement of the locking element. On the other hand, in a second setting state of the parking lock device, the locking element releases the locking element so that the locking element can move freely, more precisely can rotate, thereby also releasing the wheels of the motor vehicle.

[0012] For example, if the motor vehicle is parked on a slope, after the locking element has been fixed, a torque still acts on the wheels of the motor vehicle, which torque is also applied to the locking element due to the connection between the wheel and the locking element. The torque transmission device is thus loaded with a loading torque. The loading torque corresponds in particular to the torque that is applied to the wheel due to the weight of the motor vehicle, the resulting downhill forces, and the adhesion coefficient between the wheel and the wheel contact surface, more precisely the ground.

[0013] The wheels of the motor vehicle are located in particular at a first axle of the motor vehicle. The motor vehicle preferably has a parking brake or a parking brake, in particular an electronic parking brake. The parking brake is used in particular to fix at least one wheel of at least one of the axles of the motor vehicle, in particular a second axle of the motor vehicle, preferably all wheels of the respective axle, in particular when the motor vehicle is stationary. The first axle is used, for example, as a front axle and the second axle as a rear axle, or vice versa. If the parking brake is set to fix the respective axle, this can influence the load torque, in particular reduce its absolute value.

[0014] The loading torque acts between the locking element and the locking element. When releasing the parking lock device, i.e., when changing from the first setting state to the second setting state, the parking lock device must overcome the loading torque in order to terminate the positive locking of the locking element. This has the consequence, on the one hand, that the parking lock device must be of sufficient size in order to reliably release the locking element even in the case of large loading torques. On the other hand, depending on the magnitude of the loading torque, undesirable noises and / or jerking movements of the motor vehicle may occur when releasing the parking lock device.

[0015] In order to avoid this, it is provided that when the parking lock device is switched from the first setting state to the second setting state, a compensating torque acting on the locking element is generated by means of a motor. The compensating torque is selected in this case so that it counteracts the load torque that occurs when the locking element is fixed due to the load torque transmission device. The compensating torque to be induced by means of the motor can be determined, for example, as a function of the tilt angle of the motor vehicle.

[0016] However, this is often not accurate enough. For example, if the motor vehicle is parked so that the wheels are on the edge of the curb, a load torque can occur that is significantly different from the load torque caused solely by the tilt angle of the motor vehicle. For this reason, it is provided that the compensation torque is determined in another way, in particular independently of the tilt angle of the motor vehicle.

[0017] The rotation angle of the torque transmission device and its torsional stiffness are used here. The rotation angle describes the angle through which the torque transmission device will be rotated or has been rotated after the locking element is fixed. Based on the rotation angle of the torque transmission device and the known torsional stiffness, the compensation torque can be determined directly. The torsional stiffness is described, for example, by a torsional stiffness coefficient, which represents a proportionality constant between the compensation torque and the rotation angle. In this case, the compensation torque is generated by the product of the torsional stiffness coefficient, which describes the torsional stiffness, and the rotation angle. The torsional stiffness, more precisely the torsional stiffness coefficient, is determined, preferably measured, for example on a test bench. The measured torsional stiffness is preferably stored in the motor vehicle drivetrain or in a controller of the motor vehicle. The torsional stiffness is preferably stored constantly, so that the torsional stiffness does not change at least during the driving operation of the motor vehicle.

[0018] The rotation angle of the torque transmission device is determined at the rotation angle determination point. The rotation angle determination point can be selected arbitrarily in principle, for example at the wheel or at a wheel carrier to which the wheel is mounted or can be mounted. When determining the compensation torque, the torsional stiffness of the torque transmission device between the rotation angle determination point and the locking element must naturally be taken into account in order to determine the compensation torque with high accuracy. The described method makes it possible to compensate or at least nearly compensate the load torque under a number of boundary conditions by using a motor, so that the locking element can be released without difficulty and without causing disruptive side effects.

[0019] According to a further development of the invention, the torque transmission device has a transmission, in particular a shift transmission, and the transmission, in particular a shift transmission, is used as a transmission with a parking lock, in particular a shift transmission. In other words, the parking lock is a component of the transmission, and the transmission is in turn a component of the torque transmission device and thus a component of the motor vehicle drive train. The transmission can be a transmission with a constant and constant transmission ratio. Thus, the same transmission ratio always exists between the transmission input shaft and the transmission output shaft of the transmission, and thus between the drive train and the wheels of the motor vehicle.

[0020] However, the transmission can also be designed as a gearshift transmission. A gearshift transmission is used to set different gears or transmission ratios between the power unit and the wheels of a motor vehicle. To this end, a gear is selected from a plurality of gears of the gearshift transmission and is set at the gearshift transmission so that a transmission ratio corresponding to the gear exists between the power unit and the wheels.

[0021] Preferably, the input shaft of the transmission is coupled to the power unit, in particular via a starting clutch. The output shaft of the transmission is preferably rigidly and permanently connected to the wheels of the motor vehicle in a driving manner. The locking element is also assigned to the transmission, for example, rigidly arranged and fixed at the output shaft. When generating the compensation torque by means of the motor, the transmission ratio set on the transmission or at the gearshift transmission is obviously taken into account. This means that the motor provides a motor torque, which is converted into a compensation torque by means of the transmission and its transmission ratio, more precisely by means of the gearshift transmission and the transmission ratio set at the gearshift transmission. The described design allows a simple implementation of the method according to the present description.

[0022] A further development of the invention provides that the rotation angle is measured by means of a rotation pulse encoder. A rotation pulse encoder is an incremental encoder with the aid of which a rotational movement, more precisely the degree of rotation, can be determined. The rotational movement of the torque transmission device causes one or more rotation pulses to be generated by the rotation pulse encoder, wherein each of the rotation pulses corresponds to a determined rotation angle difference. In this regard, the rotation angle is obtained from the number of rotation pulses generated by the rotation pulse encoder and the rotation angle difference. The advantages already explained are thus achieved.

[0023] A further development of the invention provides that a rotary pulse encoder is used as a rotary pulse encoder which measures the wheel speed. In this context, the rotary pulse encoder serves, for example, as a wheel sensor, preferably as a wheel speed sensor. It is arranged in particular at a wheel hub which is a component of a motor vehicle drive train and via which a wheel of the motor vehicle can be coupled in a driving manner to the motor vehicle drive train. Measuring the wheel speed, more precisely the rotation angle of the wheel, allows a particularly precise determination of the compensation torque.

[0024] A refinement of the invention provides that the longitudinal acceleration of the motor vehicle is additionally taken into account when determining the compensation torque. In particular, if the rotary pulse encoder does not provide information about the direction of rotation of the torque transmission device at the rotation angle determination point, the longitudinal acceleration is used at this time. The longitudinal acceleration is taken into account in this case in order to determine the direction of rotation and to determine whether the rotary pulse causes an increase or decrease in the loading torque and, accordingly, an increase or decrease in the compensation torque. In particular, the sign of the loading torque and, therefore, the sign of the compensation torque are derived based on the longitudinal acceleration, and this enables a particularly precise determination of the compensation torque. The longitudinal acceleration is preferably measured by means of an acceleration sensor. The acceleration sensor is particularly preferably a component of the ESP system and is therefore, in any case, a component of the motor vehicle drivetrain or the motor vehicle.

[0025] A development of the invention provides that the angle of rotation used is the angle of rotation difference between a first angle of rotation of the torque transmission device present when the locking element is fixed and a second angle of rotation of the torque transmission device present before the locking element is released. After the locking element is fixed, the angle of rotation increases over time. This usually occurs within a relatively short period of time, i.e. from the time of fixing the locking element until the motor vehicle is completely stationary. In this regard, the angle of rotation is in the form of an angle of rotation difference between the first angle of rotation and the second angle of rotation.

[0026] When the locking element is fixed or immediately after it is fixed, the torque transmission device is at a first rotational angle. Subsequently, a second rotational angle of the torque transmission device is adjusted over time. It can be provided that the second rotational angle is determined in a certain period of time after the determination of the first rotational angle and the rotational angle is calculated. For example, the second rotational angle is determined as soon as the stationary state of the motor vehicle is determined. However, it is particularly preferred that the second rotational angle is determined just before releasing the locking element in order to determine the rotational angle difference and thus the rotational angle with particularly high accuracy. In this case, the rotational angle accumulated over the entire period between fixing the locking element and releasing the locking element is therefore detected.

[0027] A further development of the invention provides that the determination of the rotation angle is carried out from the time of fixing the locking element until immediately before releasing the locking element. Such a method has already been indicated. It enables the determination of the rotation angle with particularly high accuracy.

[0028] A further development of the invention provides that the rotation angle is determined by the signal of the rotation pulse encoder and the longitudinal acceleration in an integral / accumulative manner. As described above, the signal of the rotation pulse encoder includes one or more rotation pulses. The rotation angle can be determined in an integral form, i.e. by summing, based on the rotation angle difference associated with the one or more rotation pulses. The sign of each addend is determined here in accordance with the longitudinal acceleration corresponding to the rotation angle difference. In this regard, the longitudinal acceleration indicates whether the rotation angle increases or decreases the rotation angle difference when a rotation pulse occurs. The advantages mentioned are also achieved thereby.

[0029] A refinement of the invention provides that, in the case of a fixed locking element, the current value of the rotation angle is stored when the controller that determines the rotation angle is shut down, and when the controller is switched on, the holding angle is further determined based on the stored value. The controller is a component of the power transmission device of the motor vehicle. Usually, the controller is switched off after a certain period of time after the motor vehicle is parked or parked. The switched-off controller no longer monitors changes in the rotation angle and no longer evaluates the rotation pulses generated by the rotation pulse encoder. Nevertheless, the rotation angle determined until the controller is switched off should be maintained so that a compensating torque can be provided with high precision when the locking element is released.

[0030] For this reason, the current value of the rotation angle is stored when the controller is shut down. In other words, if the controller is shut down when the locking element is fixed, the current value of the rotation angle is stored. If the controller is subsequently switched on again while the locking element is still fixed, the holding angle continues to be determined based on the stored value. This means in particular that when the motor is or should be operated to generate a compensating torque, the compensating torque is determined based on the stored value. In addition, changes in the rotation angle that occur after the controller is switched on again and before the locking element is released are preferably taken into account. The described method has the advantage that the value of the rotation angle that has already been determined is retained, so that when the locking element is released, the motor can be controlled in a targeted manner to generate a compensating torque.

[0031] The invention also relates to a motor vehicle drive train for a motor vehicle, in particular for carrying out a method according to an embodiment of the invention described in the description, the motor vehicle drive train having a motor and a parking lock device, the drive unit being at least temporarily connected to at least one wheel of the motor vehicle in a driving manner via a torque transmission device, the parking lock device in a first setting state fixing a locking element in a form-fitting manner, the locking element being connected to the torque transmission device in a rotationally fixed manner, the parking lock device releasing the locking element in a second setting state, and generating a compensating torque acting on the locking element by means of the motor when the parking lock device is switched from the first setting state to the second setting state, the compensating torque counteracting the load torque caused by the load on the torque transmission device when the locking element is fixed. In this case, the motor vehicle drive train is arranged and designed to determine the compensating torque as a function of the torsional rigidity of the torque transmission device and the rotation angle of the torque transmission device determined after fixing the locking element.

[0032] The advantages of this embodiment of the motor vehicle drivetrain and the method described have already been pointed out. The motor vehicle drivetrain and the method for operating a motor vehicle drivetrain can be developed according to the embodiments described in the description, so that reference is made to these embodiments in this regard.

[0033] The features and feature combinations described in the specification, in particular the features and feature combinations described in the following description of the figures and / or shown in the figures, can be used not only in the respectively specified combination, but also in other combinations or alone without departing from the scope of the present invention. Therefore, embodiments that are not explicitly shown or explained in the specification and / or the figures, but are derived from or can be derived from the described embodiments, should also be regarded as embodiments covered by the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The present invention will be further explained below with reference to the exemplary embodiments shown in the drawings.

[0035] FIG1 shows a schematic diagram of a motor vehicle in a first parking state,

[0036] 2 shows a diagram in which the signal of the rotary pulse encoder and the longitudinal acceleration of the motor vehicle are plotted over time for a first parking state,

[0037] FIG3 shows a schematic diagram of a motor vehicle in a second parking state,

[0038] FIG. 4 shows a diagram in which the signal of the rotary pulse encoder and the longitudinal acceleration of the motor vehicle are plotted over time for a second parking state. DETAILED DESCRIPTION

[0039] 1 shows a schematic diagram of a motor vehicle 1 in a first parking state, in which the motor vehicle 1 is parked or parked on a sloping ground surface 2 spaced apart from a curb 3. In this case, the ground surface 2 is at an angle α to the geoid 4. This means that a longitudinal acceleration acts on the motor vehicle 1 from the center of gravity 5 of the motor vehicle 1, which is indicated by an arrow 6 and is dependent on the weight acting on the motor vehicle 1 and the angle α.

[0040] The motor vehicle 1 has a plurality of axles 7, 8, wherein axle 7 is the front axle and axle 8 is the rear axle. In the embodiment shown here, axle 7 is a drive axle, and at least one wheel 9 on this axle is respectively coupled in a driving manner to a drive unit (not shown here). The drive unit is coupled in a driving manner to the wheel 9 at least temporarily via a torque transmission device (also not shown) of the motor vehicle drive train.

[0041] The torque transmission device has a locking element which can be positively fixed by means of the parking lock device, i.e. in a first setting state of the parking lock device. In a second setting state of the parking lock device, the locking element is released. After the motor vehicle 1 has been parked and the locking element has been fixed by means of the parking lock device, a loading torque acts on the wheel 9, which is caused by the longitudinal acceleration indicated by the arrow 6.

[0042] Therefore, in order to facilitate the release of the locking element, a compensating torque which counteracts the loading torque should be generated by means of a motor which is preferably a component of the power unit and is present in particular as an electric motor. The compensating torque is determined after the locking element is fixed by determining the rotation angle of the torque transmission device. The compensating torque is calculated from the rotation angle using the known torsional stiffness of the torque transmission device.

[0043] FIG. 2 shows a diagram in which curves 11, 12 are plotted over time. Curve 11 shows the signal of the rotary pulse encoder assigned to the wheel 9. Curve 11 thus illustrates the rotary movement of the wheel 9 before, during and after the fixing of the locking element. At time t1, the locking element is fixed. Subsequently, the motor vehicle 1 still continues to move slightly due to the influence of the gravity acting on it, i.e. until time t2. This is shown in curve 11, which indicates a number of rotary pulses of the rotary pulse encoder and accordingly indicates the distance travelled by the wheel 9. Curve 12 shows the corresponding longitudinal acceleration of the motor vehicle 1.

[0044] FIG. 3 shows the motor vehicle 3 in the second parking state. In this second parking state, the motor vehicle 1 is parked in such a way that the wheels 9 rest on the curb edge of the curb 3. This means that although the longitudinal acceleration indicated by the arrow 6 and exerted on the motor vehicle 1 by gravity is in principle similar to the longitudinal acceleration in the first parking state, the torque acting on the wheel 9, indicated by the arrow 10, runs in the opposite direction, namely due to the wheel contact force at the wheel contact point on the curb edge and the resulting effective lever arm. This cannot be taken into account when determining the compensation torque solely by means of the angle α or the inclination of the ground surface 2 and leads to an erroneous value for the compensation torque.

[0045] FIG. 4 shows a diagram in which the curves 11, 12 are again shown, more specifically for the second parking state. It can be clearly seen from the curve 11 that the magnitude of the loading torque is the same as for the first parking state, since the same number of rotation pulses is generated. However, the loading torque and the compensating torque required thereby are of completely opposite signs, as indicated by the arrow 10. For this reason, when determining the compensating torque, not only the rotation angle of the torque transmission device is taken into account, but also the longitudinal acceleration of the motor vehicle 1 according to the curve 12, which describes the displacement direction of the motor vehicle 1 during the loading of the torque transmission device.

[0046] The method allows the compensation torque required for unloading the torque transmission device to be determined very accurately. Thus, the locking element can be released by the parking lock device with a high degree of comfort for the motor vehicle occupants.

[0047] Reference numerals list

[0048] 1 Motor Vehicles

[0049] 2 Ground

[0050] 3. Curbstone

[0051] 4 Planes

[0052] 5 Center of Gravity

[0053] 6 Arrows

[0054] 7 Axles

[0055] 8 Axles

[0056] 9. Wheels

[0057] 10 Arrow

[0058] 11 Change curve

[0059] 12 Change curve

Claims

1. A method for operating a motor vehicle drive device of a motor vehicle (1), the motor vehicle drive device having a motor and a parking lock device, the motor being at least temporarily connected to at least one wheel (9) of the motor vehicle (1) in a driving manner via a torque transmission device, the parking lock device fixing a locking element in a form-fitting manner in a first setting state, the locking element being connected to the torque transmission device in a non-rotatable manner relative to each other, the parking lock device releasing the locking element in a second setting state, generating a compensating torque acting on the locking element by means of the motor when the parking lock device switches from the first setting state to the second setting state, the compensating torque counteracting a loading torque caused by loading the torque transmission device when fixing the locking element, characterized in that The compensation torque is determined as a function of the torsional rigidity of the torque transmission device and the rotation angle of the torque transmission device determined after fixing the locking element.

2. The method according to claim 1, characterized in that The torque transmission device has a transmission mechanism, and the transmission mechanism used as the transmission mechanism is the transmission mechanism having the parking lock device.

3. The method according to any one of the preceding claims, characterized in that The rotation angle is measured with the aid of a rotary pulse encoder.

4. The method according to any one of the preceding claims, characterized in that The rotary pulse encoder used is a rotary pulse encoder for measuring the rotation speed of the wheel (9).

5. The method according to any one of the preceding claims, characterized in that The longitudinal acceleration of the motor vehicle is additionally taken into account when determining the compensation torque.

6. The method according to any one of the preceding claims, characterized in that The rotation angle used is the rotation angle difference between a first rotation angle of the torque transmission device which is present when the locking element is fixed and a second rotation angle of the torque transmission device which is present before the locking element is released.

7. The method according to any one of the preceding claims, characterized in that The determination of the rotation angle is carried out from the time of fixing the locking element until immediately before releasing the locking element.

8. The method according to any one of the preceding claims, characterized in that The rotation angle is determined by integrating the signal of the rotation pulse encoder and the longitudinal acceleration.

9. The method according to any one of the preceding claims, characterized in that In the case of a fixed locking element, the current value of the rotation angle is stored when the control unit which determines the rotation angle is switched off, and when the control unit is switched on, the holding angle is further determined based on the stored value.

10. A motor vehicle power transmission device for a motor vehicle (1), the motor vehicle power transmission device is particularly used to perform the method according to any one or more of the above claims, the motor vehicle power transmission device has a motor and a parking lock device, the motor is at least briefly connected to at least one wheel of the motor vehicle in a driving manner via a torque transmission device, the parking lock device fixes a locking element in a form-locked manner in a first setting state, the locking element is connected to the torque transmission device in a non-rotatable manner, the parking lock device releases the locking element in a second setting state, when the parking lock device switches from the first setting state to the second setting state, a compensation torque acting on the locking element is generated by means of the motor, the compensation torque reacts to the loading torque caused by the loading of the torque transmission device when the locking element is fixed, characterized in that The motor vehicle drive train is provided and designed to determine the compensation torque as a function of the torsional rigidity of the torque transmission device and a rotation angle of the torque transmission device determined after fixing the locking element.

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