Method for operating motor vehicle, in particular passenger vehicle, and motor vehicle

Abstract

The invention relates to a method for operating a motor vehicle (10), the motor vehicle (10) having a front axle (12) with front wheels (16) and a front axle steering device (24) designed as a steer-by-wire device, the front axle steering device having an electric motor (26) for actively steering the front wheels (16). The motor vehicle (10) comprises a rear axle (14) with rear wheels (18), a rear axle steering device (32) and a torque vectoring device (34), by means of which the distribution of a drive torque, which can be provided by a drive device (30) of the motor vehicle (10), to the rear wheels (18) can be actively adjusted. If a fault of the front axle steering device (24) is determined by means of the electronic computing device (36), an inter-phase short circuit of the electric motor (26) is caused in a targeted manner by means of the electronic computing device (36).

Description

Technical Field

[0001] The invention relates to a method for operating a motor vehicle, in particular a passenger car. The invention also relates to a motor vehicle, in particular a passenger car. Background Art

[0002] So-called steer-by-wire devices for motor vehicles are known from the general prior art, wherein corresponding steer-by-wire devices are also referred to as steer-by-wire systems. Such a steer-by-wire device is to be understood as a steering system, thus a steering device in which a steering element, which is usually designed as a steering wheel and can be actuated by a person, is not mechanically connected to a steerable wheel in such a way that an actuation of the steering element is transmitted via a mechanical coupling between the steering element and the wheel to steer the wheel, but rather the actuation of the steering element and the resulting movement are detected by means of a sensor device and are transmitted only electrically via one or more controllers to, for example, an electromechanical actuator, which drives the wheel and thus steers the wheel. This means that the actuation of the steering element and the resulting movement are steering commands, in particular the aforementioned steering commands of the person, wherein the steering commands are not mechanically transmitted to the steerable wheel, but are detected by the sensor device and are transmitted only via one or more controllers to an actuator, which then implements the steering direction by driving the steerable wheel and thus steering it. Therefore, in such a steer-by-wire device, there is no mechanical connection between the steering element and the steerable wheels. Steering of the steerable wheels is understood to mean that a change in driving direction, cornering and lane change of the corresponding motor vehicle can be caused by steering the steerable wheels. Summary of the invention

[0003] The object of the present invention is to provide a method and a motor vehicle, which allow particularly safe operation.

[0004] This object is achieved by a method having the features of patent claim 1 and a motor vehicle having the features of patent claim 6. Advantageous embodiments with expedient developments of the invention are specified in the dependent claims.

[0005] A first aspect of the invention relates to a method for operating a motor vehicle, also referred to as a vehicle and preferably configured as a passenger car. In particular, the method is performed during the driving of the motor vehicle, which is traveling along the ground during the driving. In the method, the motor vehicle has at least or exactly two axles, also referred to as axles, which are arranged in sequence and thus one after another in the longitudinal direction of the vehicle of the motor vehicle, namely at least or exactly one front axle and at least or exactly one rear axle. The respective axle has at least or exactly two wheels, wherein the wheels are also referred to as wheels. The wheels of the motor vehicle are ground contact elements, via which the motor vehicle is supported or can be supported on the ground mentioned above in the vehicle vertical direction of the motor vehicle downward. If the motor vehicle is traveling along the ground, and the motor vehicle is supported on the ground in the vehicle vertical direction downward via the ground contact elements, the wheels roll directly on the ground in particular. The respective wheels of the respective axles are arranged on the sides of the motor vehicle that are opposite to each other in the vehicle transverse direction of the motor vehicle. The wheels of the front axle are front wheels, so that the front axle has front wheels. In addition, the front axle also has a front axle steering device, which is designed as a wire steering device, thus as a wire steering system. As is well known from the general prior art, a wire steering device is to be understood as a steering device in which the manipulation of a steering control member, for example, arranged in the interior of the motor vehicle and in particular designed as a steering wheel, caused by a person of the motor vehicle, for example a male or female driver, is detected by means of a sensor device, which provides an electrical manipulation signal that characterizes the detected manipulation. The detected manipulation of the steering control member is or describes a steering command. An actuator, for example, which is designed as an electric actuator or an electromechanical actuator, is controlled and thus operated according to the signal, whereby the actuator drives the front wheels and thus steers the front wheels, thus swivels the front wheels, thereby steering the motor vehicle. In particular, the manipulation of the steering control member is to be understood as a movement of the steering control member caused by the person. In a wire steering device, the steering command is transmitted only electrically to the actuator, which implements the steering command in order to steer the front wheels, in that the actuator drives the front wheels according to the steering command and thus steers the front wheels. Thus, in a steer-by-wire system, for example, no mechanical connection is provided between the steering element and the front wheels, via which an actuation of the steering element can be transmitted to the front wheels in order to steer the front wheels. A front axle steering system has an electric motor for actively steering the front wheels. The electric motor is thus the actuator mentioned above, by means of which the front wheels can be actively driven and thus actively steered in order to steer the front wheels and thus the motor vehicle as a whole.

[0006] The wheels of the rear axle are also referred to as rear wheels, so that the rear axle has rear wheels. The rear axle also has a rear axle steering system. This means that the front wheels are steerable wheels that can be steered by means of an electric motor so that the motor vehicle can be turned, changed in direction, and changed in lane. The rear wheels are also steerable wheels that can be steered so that the motor vehicle can be changed in direction, changed in lane, and turned. It is conceivable that the rear axle is also designed as a steer-by-wire system.

[0007] The rear axle also has a torque vectoring distribution device, which is also called a torque vectoring distribution unit or a torque distribution unit or a torque distribution device. As is well known from the general prior art, the distribution of the drive torque that can be provided by the drive device of the motor vehicle to the rear wheels, which is also called the torque distribution or torque division, can be adjusted, that is, the distribution can be actively changed by means of the torque vectoring distribution device. In other words, the active distribution of the drive torque to the individual rear wheels can be performed by means of the torque vectoring distribution device. In this regard, it should be understood in particular that the torque vectoring distribution device can distribute the drive torque, that is, divide it to the rear wheels in such a way that, for example, a first torque with a first value generated by the drive torque acts on the first of the rear wheels, and a second torque with a second value generated by the drive torque acts on the second of the rear wheels. It is particularly conceivable that the first value and the second value are different from each other, in particular during the period when the first torque acts on the first rear wheel and the second torque acts on the second rear wheel. In particular, the drive device can drive the rear wheels via the torque vectoring distribution device by means of the drive torque, which drive torque can be actively distributed, that is, divided, to the rear wheels as described by means of the torque vectoring distribution device. The torque vectoring device thus makes it possible in particular to distribute the drive torque to the rear wheels differently such that the first torque has a first value and the second torque has a second value that is different from the first value. It is particularly conceivable that the torque vectoring device is designed to selectively distribute, i.e. divide, the drive torque to the rear wheels such that the first torque and the second torque can be in the same direction or in opposite directions, so that, for example, one of the rear wheels is driven while, for example, the other of the rear wheels is braked.

[0008] The drive device is thus designed to provide a drive torque and thereby drive the rear wheels and thus the motor vehicle as a whole. In particular, the drive device can drive the rear wheels via a torque vectoring device. For example, the drive device comprises at least one electric motor, by means of which the rear wheels and thus the motor vehicle can be driven, in particular purely electrically. Preferably, the electric motor is designed as a high-voltage component, the voltage of which (in particular the operating voltage or rated voltage) is preferably greater than 50 volts, in particular greater than 60 volts and quite preferably several hundred volts. Alternatively or additionally, the drive device can have an internal combustion engine, by means of which the rear wheels and thus the motor vehicle can be driven. Thus, the motor vehicle can be designed as a hybrid vehicle or as an electric vehicle, in particular as a battery electric vehicle (BEV).

[0009] If a fault in the front axle steering system is determined in the method with the aid of an electronic computing device (which can have at least or exactly one controller or a plurality of controllers, in particular connected to one another in a signaling manner), a phase short circuit of the electric motor is caused in a targeted manner with the aid of the electronic computing device. A fault in the front axle steering system can be determined with the aid of the electronic computing device, for example, by the fact that at least one (in particular electrical) measurement signal meets at least one preset criterion. The measurement signal is provided, for example, by a detection device. The measurement signal characterizes the state of at least one component of the motor vehicle. In particular, the measurement signal characterizes the position, in particular the rotational or pivoting position, of the component, wherein the position is detected, for example, with the aid of a detection device. For example, if the position of the component deviates from the nominal position, the criterion is met, and a fault is therefore determined.

[0010] In the method, if a fault is detected by means of an electronic computing device, the rear axle steering device and the torque vectoring device are controlled in a targeted manner by means of the electronic computing device in order to thereby steer the motor vehicle in a targeted manner. By controlling the rear axle steering device, for example, the rear wheels are pivoted and thus steered, thereby steering the motor vehicle. By controlling the torque vectoring device, the drive torque is distributed in such a targeted manner, i.e., divided, to the rear wheels by means of the torque vectoring device, thereby steering the motor vehicle, in particular the rear wheels. For example, by controlling the torque vectoring device, the drive torque is distributed in such a targeted manner to the rear wheels by means of the torque vectoring device that a first torque has a first value and at the same time a second torque has a second value different from the first value. By controlling the torque vectoring device in a targeted manner, a torque, also called a yaw torque, acting in particular about the vehicle vertical direction of the motor vehicle can be caused, thereby causing a steering movement of the motor vehicle, so that the motor vehicle can be steered in a particularly targeted manner in a desired direction, in particular in the direction of travel. The method according to the invention thus realizes a redundant steering function at the level of the entire vehicle, so that the motor vehicle can still remain steerable or steered in the event of a fault. In particular, in the event of a fault, in particular in the event of a failure of the front axle steering system, the method according to the invention implements a fallback concept in order to continue, i.e. to enable lateral steering of the motor vehicle despite the fault. Thus, for example, in the event of a fault, in particular in the event of a failure of the front axle steering system, a so-called emergency driving state can be implemented, in which, despite the fault, the motor vehicle can be steered in a targeted manner, i.e., the motor vehicle can be driven to a desired location, such as the driver's or driver's home or a repair shop, or the motor vehicle can be steered to the edge of the road or lane, in particular to a side road or an emergency parking strip, despite the fault.

[0011] The phase short circuit of the electric motor is switched or caused, for example, by software, thus by an algorithm which is also referred to as a software algorithm.

[0012] The front axle steering device has, for example, a steering gear, by which the front wheel can be driven by an electric motor and thus can be steered. In particular, the steering gear can have, for example, a rack that is movable at least in the transverse direction of the vehicle. In addition, the steering gear can have, for example, a gear, also called a pinion, which meshes with the rack and is thus engaged in the rack. For example, the electric motor can drive the gear and thereby rotate it, so as to thereby move the rack and thus steer the front wheel. In the method according to the invention, the phase short circuit of the electric motor is used as a blocking device or damping device, so that the motor vehicle can be steered in a targeted manner by controlling the rear axle steering device and the torque vectoring device. In other words, due to the phase short circuit of the electric motor, the electric motor is or is used as a blocking or damping device, in particular by self-locking and / or friction, so that, for example, undesirable swinging movements and / or undesirable resets of the front wheels can be avoided. Therefore, despite a fault in the front axle steering device, the motor vehicle can still be steered advantageously and in particular in a targeted manner by means of the rear axle steering device by means of the torque vectoring device. Targeted control of the rear axle steering and the torque vectoring device is used as a redundant steering function in the event of a fault, in particular a failure of the front axle steering. In particular, due to a phase short circuit, the electric motor acts on the gear rack in a blocking or damping manner, in order to counteract an undesired resetting of the front wheels or to avoid such an undesired resetting.

[0013] The method can be distributed, for example, in a controller of a steer-by-wire device or in another intelligent controller. This is particularly feasible because the method is only required or executed when a fault is detected, in particular when the steer-by-wire device fails. In particular, at least the following advantages can be achieved by the present invention:

[0014] - Utilizing the synergistic effect of the rear-axle steering system and the torque vectoring device in order to realize a redundant steering function for the steer-by-wire system. In this case, the rear-axle steering system and the torque vectoring device are used as further actuators in order to generate a yawing torque acting about the vehicle vertical direction by actuator intervention, thus by actuating further actuators, and thus steer the motor vehicle.

[0015] By short-circuiting the phases of the electric motor, the electric motor can act as a damping unit, in particular in or on a steering gear, in order, for example, to:

[0016] In order to be able to steer the motor vehicle precisely despite a fault in the front axle steering system and thus to achieve particularly safe operation, in one embodiment of the invention it is provided that the steering angle of the front wheels is kept constant, in particular in a targeted manner, by causing a phase short circuit in a targeted manner. Thus, by actuating the rear axle steering system, and thus by steering the rear wheels, the motor vehicle can be steered precisely despite a fault, thereby achieving particularly safe operation.

[0017] In another particularly advantageous embodiment of the invention, it is provided that by the targeted initiation of a phase short circuit, the steering angle of the front wheels is adjusted in a particularly targeted manner and, for example, is then kept constant. In this context, it is to be understood in particular that, for example, by the targeted initiation of a phase short circuit, the steering angle of the front wheels is adjusted in a particularly targeted manner from a first value to a second value different from the first value and is thus changed and then preferably kept constant at the second value. Thus, for example, a defined state, in particular a defined position, can be set, in which the front wheels are adjusted, so that the rear wheels can be steered in such a targeted manner by actuating the rear axle steering device that the motor vehicle can be steered in a targeted manner and, therefore, reliably and precisely.

[0018] Another embodiment is distinguished by the fact that, by actuating the torque vectoring device, a braking of at least or exactly one of the rear wheels is brought about in a targeted manner by means of the torque vectoring device. This makes it possible, for example, to bring about a particularly large yaw torque acting about the vertical direction of the vehicle, thereby making it possible to steer the motor vehicle precisely and strongly. This ensures a particularly high level of safety.

[0019] Finally, it has been shown to be particularly advantageous that, by actuating the torque vectoring device, at least or exactly one of the rear wheels is driven, thus positively accelerated, in a targeted manner by means of the torque vectoring device. Driving at least or exactly one rear wheel is to be understood in particular to mean that at least or exactly one rear wheel is initially rotated in one direction of rotation and is accelerated by actuating the torque vectoring device, thereby increasing the speed of at least or exactly one rear wheel, which rotates in the same direction of rotation. In particular, it is conceivable that, by means of the torque vectoring device, a first of the rear wheels is braked by its actuation and that, by means of the torque vectoring device, a second of the rear wheels is driven, i.e. positively accelerated, by its actuation, thereby making it possible to steer the motor vehicle particularly strongly.

[0020] The second aspect of the present invention relates to a motor vehicle, preferably configured as a passenger car, which is also referred to as a vehicle for short and is configured to carry out the method of the first aspect of the present invention. The advantages and advantageous configurations of the first aspect of the present invention should also be regarded as advantages and advantageous configurations of the second aspect of the present invention, and vice versa.

[0021] Further advantages, features and details of the invention are apparent from the following description of preferred exemplary embodiments and from the drawings. The features and feature combinations mentioned above in the description and the features and feature combinations mentioned below in the description of the drawings and / or shown individually in the single drawing may be used not only in the respectively specified combination but also in other combinations or alone without departing from the scope of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawing shows a schematic representation of a motor vehicle in the single figure. DETAILED DESCRIPTION

[0023] The single figure shows in a schematic diagram a motor vehicle 10 which is designed as a passenger car and is also referred to as a vehicle, which has, for example, a steering member, which is particularly designed as a steering wheel, in its interior space, which is also referred to as a passenger compartment or passenger space. The steering member can be operated and thus moved by a person who is in the interior space, for example, a male or female driver of the motor vehicle, so as to thereby, for example, turn the motor vehicle 10, thus causing a turning movement of the motor vehicle 10. This is explained in more detail below. A method for operating the motor vehicle 10 is also described below with the aid of the single figure. The motor vehicle 10 has exactly two axles 12 and 14 arranged in sequence along the longitudinal direction of the vehicle 10, wherein the longitudinal direction of the vehicle is indicated by a double arrow 15. The axle 12 is the front axle, and the axle 14 is the rear axle. The respective axles 12, 14 have exactly two wheels 16, 18, wherein the wheel 16 of the front axle is the front wheel, and the wheel 18 of the rear axle is the rear wheel. Wheels 16 and 18 are ground-engaging elements, via which motor vehicle 10 (also referred to as motor vehicle) is supported or can be supported on the ground in a vehicle vertical direction. The vehicle vertical direction is indicated in the drawing by a double arrow 20 and runs perpendicular to the image plane of the drawing. It can be seen that the respective wheels 16, 18 of the respective axles 12, 14 are arranged on sides of motor vehicle 10 that are opposite to each other in the vehicle transverse direction. The vehicle transverse direction is indicated by a double arrow 22.

[0024] The front axle includes a front axle steering device 24, which is particularly schematically shown in the drawings and is designed as a steer-by-wire device. In particular, it should be understood that if a person who is located in the interior space actuates the steering member and thus moves it, the movement of the steering member is detected by means of a sensor device. The sensor device provides an electrical sensor signal, wherein an actuator of the front axle steering device 24, which is designed as an electric motor 26, is actuated and thus operated according to the sensor signal. As a result, the electric motor 26 drives the wheels 16 (front wheels), thereby steering the wheels 16 and thus the motor vehicle 10. As a result, lane changes, changes in driving direction and cornering of the motor vehicle 10 can be caused, for example. There is no mechanical connection between the steering member and the wheels 16, via which the movement of the steering member can be transmitted to the wheels 16 and thus converted into a corresponding steering movement of the wheels 16. The front axle steering device 24 includes a steering gear 28, which is particularly schematically shown in the drawings and has, for example, a rack. It can be seen that the electric motor 26 can drive the wheels 16 via the steering gear 28 and thus via the toothed rack and thus steer them.

[0025] The motor vehicle 10 has a drive device 30, which is particularly schematically shown in the drawing, which can provide a drive torque for driving the wheels 18 and thus the motor vehicle 10 as a whole. In this case, the axle 14 (rear axle) has a rear axle steering device 32, by means of which the rear wheels (wheels 18) can be steered. The rear axle also has a torque vectoring device 34, wherein, for example, the drive device 30 can drive the wheels 18 via the torque vectoring device 34. The torque vectoring device 34 can be used to actively adjust the distribution of the drive torque provided or available by the drive device 30 to the wheels. In other words, the torque vectoring device 34 can distribute or divide the drive torque to the wheels 18 in a targeted manner, in particular so that the drive torque is divided differently to the wheels 18, so that, for example, a first torque that acts on a first of the wheels 18 and a second torque that acts on a second wheel 18 and is different from the first torque are generated from the drive torque. The first torque and the second torque differ, for example, in their values, i.e., they differ from each other in terms of their values ​​and / or the first torque and the second torque differ from each other, for example, in terms of their respective directions of action.

[0026] The figures also particularly schematically show an electronic computing device 36, which is, for example, a component of the motor vehicle 10. The electronic computing device 36 can include at least or exactly one controller or a plurality of controllers. In other words, the electronic computing device 36 can be formed by at least or exactly one controller or by a plurality of (in particular interconnected) controllers.

[0027] If a fault in the front axle steering system 24 is now detected in the method with the aid of the electronic computing device 36, a short circuit between the phases of the electric motor 26 is selectively caused with the aid of the electronic computing device 36. Furthermore, if a fault is detected with the aid of the electronic computing device 36, the rear axle steering system 32 and the torque vectoring device 34 are selectively actuated with the aid of the electronic computing device 36 in order to thereby selectively steer the motor vehicle 10.

[0028] If it is determined that the steering angle of the front wheels cannot (anymore) be measured, and therefore detected, by means of the detection device, a fault is determined, for example. The detection device is, for example, configured to measure the steering angle of the front wheels and to provide a measurement signal, which characterizes the steering angle of the front wheels measured by means of the detection device. If, for example, the measuring device now does not (anymore) provide a measurement signal, although the measuring device should, should or must provide this measurement signal, a fault is inferred. Furthermore, it is conceivable, for example, that if the measurement signal deviates from the rated signal, a fault is inferred and therefore determined. Thus, the fault includes in particular that the measuring device does not (anymore) detect the steering angle of the front wheels. For example, a fault is determined when at least one preset or pre-settable criterion is met. This criterion is met, for example, when the measuring device does not provide a measurement signal. Alternatively or additionally, this criterion is met, for example, when the measurement signal deviates from the above-mentioned rated signal.

[0029] By actuating the torque vectoring device 34 and the rear axle steering device 32 , a redundant steering function can be realized, in particular at the level of the entire vehicle, so that a particularly safe operation of the motor vehicle 10 can be ensured.

[0030] Reference numerals list

[0031] 10 Motor Vehicles

[0032] 12 Axles

[0033] 14 Axles

[0034] 15 Double Arrow

[0035] 16 Wheels

[0036] 18 Wheels

[0037] 20 Double Arrow

[0038] 22 Double Arrow

[0039] 24 Front axle steering

[0040] 26 Electric Motor

[0041] 28 Steering transmission mechanism

[0042] 30 Drive equipment

[0043] 32 Rear axle steering

[0044] 34 Torque vectoring device

[0045] 36 Electronic computing equipment

Claims

1. A method for operating a motor vehicle (10), wherein: The motor vehicle (10) has a front axle (12) with front wheels (16) and a front axle steering device (24) designed as a steer-by-wire device, which has an electric motor (26) for actively steering the front wheels (16); The motor vehicle (10) has a rear axle (14) with rear wheels (18), a rear axle steering device (32) and a torque vectoring device (34), by means of which the distribution of a drive torque that can be provided by a drive device (30) of the motor vehicle (10) to the rear wheels (18) can be actively adjusted; If a fault in the front axle steering system (24) is detected by means of the electronic computing device (36): o Inducing a phase-to-phase short circuit of the electric motor (26) in a targeted manner by means of the electronic computing device (36); o The rear axle steering device (32) and the torque vectoring device (34) are controlled in a targeted manner by means of the electronic computing device (36) in order to thereby steer the motor vehicle (10) in a targeted manner.

2. The method according to claim 1, characterized in that: By causing the phase-to-phase short circuit in a targeted manner, the steering angle of the front wheels (16) is kept constant.

3. The method according to claim 1 or 2, characterized in that: By selectively causing the phase-to-phase short circuit, the steering angle of the front wheels (16) is adjusted.

4. The method according to any one of the preceding claims, characterized in that By actuating the torque vectoring device (34), at least or exactly one of the rear wheels (18) is braked in a targeted manner using the torque vectoring device (34).

5. The method according to any one of the preceding claims, characterized in that By actuating the torque vectoring device (34), at least or exactly one of the rear wheels (18) is driven in a targeted manner using the torque vectoring device (34).

6. A motor vehicle (10) which is designed to carry out the method according to any one of the preceding claims. 。

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