Method for controlling a drive train of a motor vehicle, control device and motor vehicle

Abstract

The invention relates to a method for controlling a drive train of a motor vehicle (10), wherein the drive train comprises a drive motor configured to drive at least one wheel of the motor vehicle (10) and an electric traction machine that can be coupled and uncoupled by means of a coupling unit for driving the motor vehicle (10), in which method a control device, during a journey of the motor vehicle (10), uses driving data characterizing the journey of the motor vehicle (10) to create a prediction as to whether the motor vehicle (10) will be in a dynamic situation (12) in the future during the journey in which the motor vehicle (10) is to be driven by means of the electric traction machine (V1), and if the dynamic situation (12) is predicted, the coupling unit is triggered to be closed before the dynamic situation (12) occurs,whereby the electric traction machine for driving the motor vehicle (10) is coupled (V2).,

Description

[0001] The invention relates to a method for controlling a drive train of a motor vehicle, a control device for controlling a drive train of a motor vehicle and a motor vehicle.

[0002] DE 10 2014 215 906 A1 discloses a method for decoupling a rechargeable electrical energy storage device of a serial hybrid drive of a motor vehicle. The serial hybrid drive comprises an electric drive motor for driving the vehicle with upstream power electronics, an energy converter for generating electrical energy for the electric drive motor and for the electrical energy storage device, and the electrical energy storage device coupled to the energy converter and the power electronics of the electric drive motor. Furthermore, the serial hybrid drive comprises controllable decoupling means for electrically decoupling the electrical energy storage device from the energy converter and the electric drive motor.

[0003] The object of the present invention is to provide a solution by means of which a motor vehicle can be driven in a particularly energy-efficient manner and a particularly high power of the motor vehicle can be provided in defined situations.

[0004] This object is achieved according to the invention by the subject matter of the independent claims. Further possible embodiments of the invention are disclosed in the subclaims, the description, and the figures. Features, advantages, and possible embodiments presented in the description for one of the subject matter of the independent claims are to be regarded at least analogously as features, advantages, and possible embodiments of the respective subject matter of the other independent claims, as well as any possible combination of the subject matter of the independent claims, optionally in conjunction with one or more of the subclaims.

[0005] The invention relates to a method for controlling a drive train of a motor vehicle. The drive train is designed to provide a torque which is transmitted to at least one wheel of the motor vehicle, whereby the motor vehicle is driven. The motor vehicle is in particular a motor vehicle, in particular a passenger car. The drive train comprises a drive motor designed to drive at least one wheel of the motor vehicle. This drive motor can be, for example, an electric motor or an internal combustion engine. The drive train further comprises an electric traction machine which can be coupled and decoupled by means of a coupling unit for driving the motor vehicle. This means that the electric traction machine can be switched on or off by means of the coupling unit.If the electric traction motor is coupled, the torque provided by the electric traction motor can be transmitted to at least one wheel of the motor vehicle, thus driving the motor vehicle both by the drive motor and by the electric traction motor. If the electric traction motor is uncoupled and the coupling unit is open, no torque can be transmitted from the electric traction motor to the wheels of the motor vehicle. This means that in this case, the motor vehicle is driven only by the drive motor at most.

[0006] If the drive motor is an internal combustion engine, then the motor vehicle is a hybrid vehicle. If the drive motor is an electric motor and thus an electric machine, then the motor vehicle is an electric vehicle, which can also be referred to as a battery electric vehicle.

[0007] The method provides that, by means of a control device, in particular a control device of the motor vehicle, a prediction is made during a journey of the motor vehicle on the basis of driving data characterizing the journey of the motor vehicle as to whether the motor vehicle will find itself in a dynamic situation during the journey in which the motor vehicle is to be driven by the electric traction motor. In particular, it is provided that, if the motor vehicle is in a dynamic situation, it should always be additionally driven by the electric traction motor. The method therefore checks whether a dynamic situation will arise during the current journey of the motor vehicle.If the dynamic situation is predicted, which means that it is determined that the motor vehicle will find itself in the dynamic situation in the future while driving, the control device triggers the coupling unit to be closed before the dynamic situation occurs. This couples up the electric traction motor to drive the motor vehicle. In particular, it is provided that the control device controls the coupling unit in such a way that the electric traction motor is already coupled up before the dynamic situation begins and thus provides a torque for at least one wheel of the motor vehicle. If no dynamic situation is predicted, the coupling unit is not triggered to close and thus the electric traction motor is not coupled up.The coupling unit can, for example, be a clutch configured to establish or interrupt a torque transmission path from the electric traction motor to at least one wheel of the motor vehicle. In particular, the control device is configured to trigger the coupling unit to be closed within a predetermined limit distance from a position at which the motor vehicle enters the dynamic situation and / or within a predetermined time interval ending with the onset of the dynamic situation.If there is still a long time period before the motor vehicle enters the dynamic situation, or if the motor vehicle is a long distance from the position upon reaching which the motor vehicle enters the dynamic situation, then the coupling unit can be omitted from closing until the motor vehicle is only a short distance from the point specified by the limit distance, or until at most only the time period of the time interval has to elapse until the motor vehicle is in the dynamic situation. In other words, the control device triggers the coupling unit to be closed only shortly before the dynamic situation is reached, whereby the motor vehicle is not driven by the electric traction motor for a particularly long time.The motor vehicle is only additionally propelled by the electric traction motor shortly before the dynamic situation occurs. If the motor vehicle is additionally propelled by the electric traction motor, then the motor vehicle can drive highly dynamically and a particularly high torque is available to drive the motor vehicle. However, if the electric traction motor is coupled and not driving the motor vehicle, for example because the electric traction motor is merely towed along, then the motor vehicle is not maximally efficient. If the electric traction motor is towed along due to its coupled state, then electrical losses and friction losses occur because the rotor of the electric traction motor rotates and an inverter of the electric traction motor has to be activated to supply current to the electric traction motor.The described method thus makes it possible for the electric traction machine to be uncoupled by arranging the coupling unit in the open position when the torque that can be provided by the electric traction machine is not required to drive the motor vehicle. Furthermore, the method makes it possible for the torque that can be provided by the electric traction machine to be available for driving the motor vehicle in a dynamic situation due to the closed position of the coupling unit. In order to make it possible for the torque that can be provided by the electric traction machine to be available from the outset in the dynamic situation, the method provides that the control device triggers the coupling unit to be closed and the electric traction machine to be coupled even before the dynamic situation occurs.Coupling or uncoupling is understood to mean, in particular, opening or closing a torque transmission path from the electric traction machine to the wheels of the motor vehicle.

[0008] In a possible development of the invention, it is provided that, when the control device determines that the motor vehicle has left the dynamic situation, the coupling unit is triggered to open, thereby uncoupling the electric traction motor from the wheels of the motor vehicle. This prevents torque from being transmitted from the electric traction motor to the wheels of the motor vehicle. In other words, the method triggers the electric traction motor to be uncoupled again by opening the coupling unit when the motor vehicle has left the dynamic situation, in particular as soon as the motor vehicle has left the dynamic situation.This allows the motor vehicle to be operated particularly efficiently again after the dynamic situation, since the electric traction machine does not have to be dragged along by the drive motor due to the decoupling and thus neither friction losses nor electrical losses occur in the electric traction machine.

[0009] In a further possible embodiment of the invention, it is provided that the control device predicts the dynamic situation as a function of the driving data, wherein the driving data comprise at least one of the data classes mentioned below. As a first data class, the driving data can comprise at least historical data characterizing a past journey of the motor vehicle. In this case, the historical data can characterize, for example, how the motor vehicle has usually been controlled and thus in the past in similar traffic situations. In this case, the historical data can be evaluated for each individual driver. In other words, the historical data can store how dynamically the driver of the motor vehicle, for example, negotiated curves during past journeys. As a second possible data class, the driving data can comprise driving mode data characterizing a set driving mode of the motor vehicle.This driving mode data can, in particular, characterize whether the motor vehicle's driving mode is set to a sport mode, a comfort mode, or an efficiency mode, which can also be referred to as eco mode. For example, if the motor vehicle is set to sport mode, the probability that the motor vehicle will be in at least one dynamic situation during the journey is significantly higher than if, for example, the motor vehicle is set to comfort mode. As a third data class, the driving data can include traffic situation data characterizing a current traffic situation in which the motor vehicle is located.Based on the current traffic situation in which the motor vehicle is located, as characterized by the traffic situation data, a particularly reliable statement can be made as to whether the motor vehicle will find itself in a dynamic situation in the future during its journey, in particular in the near future, in particular within the time interval or at the latest after covering a distance corresponding to the limit distance. As a third data class, the driving data can include navigation data characterizing a planned route of the motor vehicle. The navigation data can characterize the planned route of the motor vehicle from a starting point to a destination. Based on the navigation data, it can therefore be determined particularly easily and reliably what course the route along which the motor vehicle will be moved during the journey is likely to take.Using the navigation data, it is thus possible to determine particularly easily and with particularly high reliability the curves that the motor vehicle will travel through in the future. The navigation data can also be used to determine how tight the respective curves are, which allows it to be determined with particularly high reliability whether the motor vehicle will find itself in a dynamic situation while traveling through or as a result of traveling through the respective curve. The more of the described data classes the driving data includes, the lower the probability of error with which the existence of at least one dynamic situation is determined.

[0010] In this context, it can be provided, in particular, that the traffic situation data are received by the control device from a sensor device of the motor vehicle. This sensor device of the motor vehicle can be, for example, a radar device and / or a lidar device and / or an ultrasonic sensor device and / or a camera device of the motor vehicle.The traffic situation data can, in particular, characterize a road course on which the motor vehicle is located and / or a number of lanes on the road on which the motor vehicle is located and / or a position of at least one other road user within a predefined radius around the motor vehicle and / or a type of the at least one other road user within the predefined radius of the motor vehicle and / or a speed of the motor vehicle and / or a lateral and / or longitudinal acceleration of the motor vehicle. Alternatively or additionally, the traffic situation data can characterize whether the motor vehicle is in a city, on a country road, or on a motorway.The more traffic situation data are used to determine the dynamic situation, or the more of the above-mentioned parameters are characterized by the traffic situation data, the more accurately the dynamic situation can be determined by the control device.

[0011] In a further possible embodiment of the invention, the control device determines a probability of the dynamic situation occurring based on the driving data, and the coupling unit is triggered to close if the determined probability is above a predetermined probability threshold. This means that the driving data can be incorporated into a calculation rule as input data, whereby this calculation rule, in turn, calculates the probability of the dynamic situation based on the driving data. The higher the determined probability value, the lower the error probability that a dynamic situation is predicted but this predicted dynamic situation does not occur.

[0012] In a further possible embodiment of the invention, it is provided that it is determined that the motor vehicle will be in the dynamic situation if it is predicted for a situation that the motor vehicle in this situation will have a speed above a predetermined speed limit and / or an acceleration of the motor vehicle will have above a predetermined acceleration limit and / or a probability of oversteering or understeering for this situation is above a predetermined probability limit.If it is predicted that the motor vehicle will have a particularly high speed, which is above the specified speed limit, and / or a particularly high acceleration, which is above the specified acceleration limit, and / or there is a particularly high probability of oversteering or understeering of the motor vehicle in this situation, then this situation is determined to be a dynamic situation. In order to enable the high speed or the high acceleration of the motor vehicle, in particular a high longitudinal acceleration of the motor vehicle, in the dynamic situation, a torque provided by the electric traction machine may be necessary in addition to the torque provided by the drive motor.In order to limit, and in particular to prevent, oversteering or understeering of the motor vehicle, it can be provided that the motor vehicle is driven on one of its axles by the drive motor and on the other of its axles by the electric traction motor. Alternatively, it is possible for the coupling unit to be configured to connect individual wheels of the motor vehicle to the electric traction motor in a power-transmitting manner or to interrupt the power transmission from the electric traction motor to the respective wheels. If it is thus determined that, based on the driving data examined, the motor vehicle should also be driven by the electric traction motor in the situation, then it is determined that this examined situation is a dynamic situation.The situation can thus be classified as dynamic or non-dynamic depending on whether additional torque is required from the electric traction motor to propel the vehicle. By predicting and thus forecasting dynamic situations for the vehicle's travel, the driver can be supported in such dynamic driving situations to achieve the respective speed or acceleration, or to limit oversteering or understeering by coupling the electric traction motor.

[0013] The invention further relates to a control device for controlling a drive train of a motor vehicle. The drive train comprises a drive motor configured to drive at least one wheel of the motor vehicle, as well as an electric traction motor that can be coupled and uncoupled by means of a coupling unit for driving the motor vehicle. The control device is configured to make a prediction during a journey of the motor vehicle, based on driving data characterizing the journey of the motor vehicle, as to whether the motor vehicle will find itself in a future dynamic situation during the journey in which the motor vehicle is to be driven by the electric traction motor.Furthermore, the control device is configured to trigger, when the dynamic situation is predicted, the coupling unit to be closed before the dynamic situation occurs, thereby coupling the electric traction motor to drive the motor vehicle. In particular, the control device is configured to execute a method as already described in connection with the method according to the invention for controlling a drive train of a motor vehicle.

[0014] The invention further relates to a motor vehicle having a drive train comprising a drive motor configured to drive at least one wheel of the motor vehicle, as well as an electric traction machine that can be coupled and decoupled by means of a coupling unit for driving the motor vehicle. Furthermore, the motor vehicle comprises the coupling unit and a control device, as already described in connection with the control device according to the invention.

[0015] Further features of the invention may emerge from the claims, the figures, and the description of the figures. The features and combinations of features mentioned above in the description, as well as the features and combinations of features shown below in the description of the figures and / or in the figures alone, can be used not only in the respective combinations specified, but also in other combinations or on their own, without departing from the scope of the invention.

[0016] The drawing shows in: Fig. 1 shows a process diagram for a method for controlling a drive train of a motor vehicle; Fig. 2 a first exemplary driving situation and Fig. 3 a second exemplary driving situation.

[0017] In the figures, identical and functionally identical elements are provided with the same reference numerals.

[0018] The drawing shows Fig. 1 shows a method diagram for a method for controlling a drive train of a motor vehicle 10. The drive train of the motor vehicle 10 comprises a drive motor, in this case an electric motor, configured to drive at least one wheel of the motor vehicle 10, as well as an electric traction machine that can be coupled and uncoupled by means of a coupling unit for driving the motor vehicle 10. It is provided that the method is carried out by means of a control device of the motor vehicle 10. The method comprises a first method step V1 and a second method step V2.In the method, it is provided that in the first method step V1 during a journey of the motor vehicle 10, a prediction is made on the basis of driving data characterizing the journey of the motor vehicle 10 as to whether the motor vehicle 10 will be in a dynamic situation 12 in the future during the journey in which the motor vehicle 10 is to be driven by means of the electric traction machine.It is determined that the motor vehicle 10 will be in the dynamic situation 12 if it is predicted that the motor vehicle 10 will have a speed above a predetermined speed limit in an examined situation and / or an acceleration, in particular a longitudinal and / or lateral acceleration, above a predetermined acceleration limit and / or a probability of oversteering or understeering of the motor vehicle 10 in the situation is above a predetermined probability limit. It is provided that the control device predicts the dynamic situation 12 as a function of the driving data, wherein the driving data can include historical data and / or driving mode data and / or traffic situation data and / or navigation data. The historical data characterize at least one past journey of the motor vehicle 10.The driving mode data characterize a currently set driving mode of the motor vehicle 10. The navigation data characterize a planned route of the motor vehicle 10. The traffic situation data characterize a current traffic situation in which the motor vehicle 10 is located. In this case, the traffic situation data can be received by the control device from a sensor device of the motor vehicle 10. In particular, the traffic situation data characterize a road course of a road 14 on which the motor vehicle 10 is located and / or a position and / or type of at least one other road user 16 within a predetermined radius of the motor vehicle 10 and / or a speed of the motor vehicle 10 and / or a lateral and / or longitudinal acceleration of the motor vehicle 10.The control device can determine a probability of the occurrence of the dynamic situation 12 based on the driving data. If the determined probability is above a predetermined probability threshold, the dynamic situation 12 is predicted accordingly. The method further provides that in the second method step V2, if the dynamic situation 12 has been predicted, the control device triggers the closing of the coupling unit before the occurrence of the dynamic situation 12. By closing the coupling unit, the electric traction machine is coupled to drive the motor vehicle 10.

[0019] It can be provided that, when the control unit determines that the motor vehicle 10 has left the dynamic situation 12 again, the control device triggers the opening of the coupling unit, whereby the electric traction machine is decoupled from the wheels of the motor vehicle 10.

[0020] In Fig. 2 shows a first traffic situation in which the motor vehicle 10 is traveling on a country road without a vehicle in front. Based on the navigation data, the control device detects a tight curve 18 500 m in front of the motor vehicle 10. Additionally, based on the driving mode data, it is determined that a sport mode is set in the motor vehicle 10. Based on these driving data, it is determined that the motor vehicle 10 will be in a dynamic situation 12 in the curve 18. In other words, the probability determined from the driving data that the situation in which the motor vehicle 10 will be when traveling through the curve 18 is a dynamic situation 12 is higher than the predefined probability threshold. As a result, the coupling unit is closed.Because the electric traction machine can provide torque for wheels of the motor vehicle 10 before entering the curve 18 and thus already before reaching the dynamic situation 12, the curve 18 can be negotiated dynamically by the motor vehicle 10.

[0021] In Fig. 3 shows a second traffic situation, which corresponds to the one in Fig. 2 is different. In the case of the first traffic situation shown in Fig. In the traffic situation shown in Figure 3, the motor vehicle 10 is on a country road. On this country road, there is oncoming traffic from other road users 16. In addition, in the lane of road 14 on which the motor vehicle 10 is located, a truck 20 is arranged in front of the motor vehicle 10 as another road user 16. In the Fig. In the traffic situation described in Figure 3, it is determined from the navigation data that the tight curve 18 is located 500 m in front of the motor vehicle 10, and from the driving mode data it is established that the sport mode is currently selected in the motor vehicle 10. In addition, however, the traffic situation data characterize the truck 20 driving slowly ahead of the motor vehicle 10 and that there is no overtaking opportunity for the motor vehicle 10. As a result, the determined probability that the motor vehicle 10 is in a dynamic driving situation in the curve 18 is below the specified probability threshold or corresponds to the specified probability threshold. As a result, it is determined that the motor vehicle 10 will not be in a dynamic situation 12 in the curve 18. Thus, the coupling unit remains open and the electric traction machine is or remains uncoupled.Would be at the in . Fig. 3, there is no oncoming traffic, but an overtaking ban applies to a section of road in which the motor vehicle 10 is located and which extends at least as far as the curve 18, then the determined probability of the existence of the dynamic situation 12 would also be less than or equal to the predetermined probability threshold and, as a result, it would be determined that the motor vehicle 10 - due to the following behind the truck 20 - will not be in a dynamic driving situation in the curve 18.

[0022] In particular, it is provided that the electric traction machine is coupled when there is a high load requirement and / or a high vehicle speed of the motor vehicle 10. If the electric traction machine is coupled, then an all-wheel drive capability of the motor vehicle 10 can be present, whereby particularly good traction and agility of the motor vehicle 10 can be achieved. Furthermore, when the electric traction machine is coupled, the drive train has a particularly high torque potential. A state change between the coupled state and the uncoupled state of the electric traction machine requires time. This coupling time depends on the driving speed of the motor vehicle 10 and a mechanical synchronization time. This coupling time can limit the dynamics of the motor vehicle 10, for example with regard to torque buildup.The higher the current driving speed of the motor vehicle 10, the greater the speed range over which the electric traction machine must be rotated from a standstill in order to synchronize the speed of the electric traction machine with an output speed of the drive train.

[0023] The mechanical synchronization time describes the time required to actually couple the electric traction machine from a point in time at which the speed of the electric traction machine is already synchronized with the output speed of the rest of the drive train.

[0024] To enable the motor vehicle 10 to be operated with maximum efficiency and to ensure that neither a change in the state of the coupling unit nor disadvantages of the uncoupled state of the electric traction machine are noticeable to a driver in relevant driving situations and thus dynamic situations 12, it is provided that the coupling unit is coupled before the dynamic situation 12 based on the driving data. Thus, the motor vehicle 10 is not yet in the dynamic situation 12 when the electric traction machine is coupled. As a result, the coupling process is barely noticeable to the driver of the motor vehicle 10. After the dynamic situation 12 has ended, the coupling unit can be opened again.

[0025] The method provides for the coupling unit to be kept open for as long and as often as possible, thus disconnecting the electric traction motor. This allows the greatest possible range of the motor vehicle 10 to be achieved, since neither electrical losses nor braking effects occur due to the electric traction motor being dragged along. If the dynamic situation 12 is expected, a dynamic potential is provided by anticipatory closing of the coupling unit. If it is thus known that the motor vehicle 10 will not experience a dynamic situation 12 in the near future, the motor vehicle 10 is operated with the electric traction motor disconnected for as long as possible, thereby enabling particularly low fuel consumption of the motor vehicle 10.If the dynamic situation 12 is predicted, the electric traction machine is coupled as promptly as possible so that the driver of the motor vehicle 10 does not notice the coupling.

[0026] The termination of the dynamic situation 12 can be determined in particular when the driving speed of the motor vehicle 10 drops to or below the predetermined speed limit and / or the acceleration of the motor vehicle 10 drops to or below the predetermined acceleration limit.

[0027] Overall, the invention shows how an intelligent operating strategy for a coupling unit can be implemented. List of reference symbols 10 motor vehicle 12 dynamic situations 14 Street 16 road users 18 curve 20 trucks V1 - V2 respective process steps QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2014 215 906 A1

[0002]

Claims

[1] Method for controlling a drive train of a motor vehicle (10), wherein the drive train comprises a drive motor configured to drive at least one wheel of the motor vehicle (10) and an electric traction machine that can be coupled and uncoupled by means of a coupling unit for driving the motor vehicle (10), in which by means of a control device - during a journey of the motor vehicle (10), a prediction is made on the basis of driving data characterising the journey of the motor vehicle (10) as to whether the motor vehicle (10) will be in a dynamic situation (12) in the future during the journey in which the motor vehicle (10) is to be driven by means of the electric traction machine (V1), - if the dynamic situation (12) is predicted, the coupling unit is triggered to be closed before the dynamic situation (12) occurs, whereby the electric traction machine is coupled (V2) for driving the motor vehicle (10). [2] Method according to claim 1, characterized by that when it is determined by means of the control device that the motor vehicle (10) has left the dynamic situation (12), the coupling unit is opened, whereby the electric traction machine is decoupled from the wheels of the motor vehicle (10). [3] Method according to claim 1 or 2, characterized by that the control device predicts the dynamic situation (12) as a function of the driving data, wherein the driving data comprise at least one of the following data classes: - historical data characterising at least one past journey of the motor vehicle (10), - driving mode data characterizing a set driving mode of the motor vehicle (10), - traffic situation data characterising a current traffic situation in which the motor vehicle (10) is located, - navigation data characterising a planned route of the motor vehicle (10). [4] Method according to claim 3, characterized by that the traffic situation data are received by means of the control device from a sensor device of the motor vehicle (10) and in particular characterize a road course of a road (14) on which the motor vehicle (10) is located and / or a position of at least one further road user (16) and / or a type of at least one further road user (16) and / or a speed of the motor vehicle (10) and / or a lateral and / or longitudinal acceleration of the motor vehicle (10). [5] Method according to one of the preceding claims, characterized bythat a probability of the occurrence of the dynamic situation (12) is determined by means of the control device on the basis of the driving data and the closing of the coupling unit is triggered if the determined probability is above a predetermined probability limit value. [6] Method according to one of the preceding claims, characterized by that it is determined that the motor vehicle (10) will be in the dynamic situation (12) if it is predicted that the motor vehicle in this situation will have a speed above a predetermined speed limit and / or an acceleration above a predetermined acceleration limit and / or a probability of oversteering or understeering is above a predetermined probability limit. [7] Control device for controlling a drive train of a motor vehicle (10), wherein the drive train comprises a drive motor configured to drive at least one wheel of the motor vehicle (10) and an electric traction machine that can be coupled and uncoupled by means of a coupling unit for driving the motor vehicle (10), wherein the control device is configured to - during a journey of the motor vehicle (10), to make a prediction based on driving data characterising the journey of the motor vehicle (10) as to whether the motor vehicle (10) will be in a dynamic situation (12) in the future during the journey in which the motor vehicle (10) is to be driven by means of the electric traction machine, - if the dynamic situation (12) is predicted, to trigger that the coupling unit is closed before the occurrence of the dynamic situation (12), whereby the electric traction machine is coupled for driving the motor vehicle (10). [8] Motor vehicle (10), having a drive train which comprises a drive motor configured to drive at least one wheel of the motor vehicle (10) and an electric traction machine which can be coupled and uncoupled by means of a coupling unit for driving the motor vehicle (10), having the coupling unit and a control device according to claim 7.

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