METHOD FOR OPERATING A MOTOR VEHICLE AND CORRESPONDING MOTOR VEHICLE

Abstract

A method for operating a motor vehicle, wherein the motor vehicle has a steering system for steering at least one wheel of the motor vehicle by means of a drive. In doing so, it is provided that a time span is determined for at least one countermeasure limiting a hazard to a vehicle occupant upon an at least partial failure of the steering system, within which time span the countermeasure deploys an effect, and that a state variable (T) influencing the operating capacity of the steering system is determined and extrapolated over time and a point in time (t.sub.1) is calculated in which the state variable (T) exceeds a limit value (T.sub.1), wherein the countermeasure is introduced when the point in time (t.sub.1) is less than the time span in the future.

Claims

1. A method for operating a motor vehicle, comprising: a steering system for steering at least one wheel of the motor vehicle by a drive, wherein a time span is determined for at least one countermeasure limiting a hazard to a vehicle occupant upon an at least partial failure of the steering system, within which time span the countermeasure deploys an effect, and in that a state variable (T) influencing the operating capacity of the steering system is determined and extrapolated over time and a point in time (t.sub.1) is calculated in which the state variable (T) exceeds a limit value (T.sub.1), wherein the countermeasure is introduced when the point in time (t.sub.1) is less than the time span in the future.

2. The method according to claim 1, wherein a temperature, an electric voltage, an electrical resistance, a road slope, or a wind speed is used as the state variable (T).

3. The method according to claim 1, wherein a reduction in the speed of the motor vehicle, particularly to the point of stoppage, a switchover to a further drive in order to steer the at least one wheel, or information about a vehicle occupant is used as the countermeasure.

4. The method according to claim 1, wherein the information about the vehicle occupant occurs at a time before the point in time (t.sub.1) and upon or after the determination that the point in time (t.sub.1) is less than the time span in the future, and the reduction in speed of the motor vehicle or the switchover to the further drive is implemented at the point in time and/or upon the exceeding of the limit value (T.sub.1) by the state variable (T).

5. The method according to claim 1, wherein the information is a prompt to the vehicle occupant to take over a lateral control of the motor vehicle by means of a control element.

6. The method according to claim 1, wherein a control element coupled mechanically to the wheel is used as the control element.

7. A motor vehicle, wherein the motor vehicle has a steering system for steering at least one wheel of the motor vehicle by means of a drive, wherein the motor vehicle is formed to determine a time span for at least one countermeasure limiting a hazard to a vehicle occupant upon an at least partial failure of the steering system, within which time span the countermeasure deploys an effect, and in that a state variable (T) influencing the operating capacity of the steering system is determined and extrapolated over time and a point in time (t.sub.1) is calculated in which the state variable (T) exceeds a limit value (T.sub.1), wherein the countermeasure is introduced when the point in time (t.sub.1) is less than the time span in the future.

8. The method according to claim 2, wherein a reduction in the speed of the motor vehicle, particularly to the point of stoppage, a switchover to a further drive in order to steer the at least one wheel, or information about a vehicle occupant is used as the countermeasure.

9. The method according to claim 2, wherein the information about the vehicle occupant occurs at a time before the point in time (t.sub.1) and upon or after the determination that the point in time (t.sub.1) is less than the time span in the future, and the reduction in speed of the motor vehicle or the switchover to the further drive is implemented at the point in time and/or upon the exceeding of the limit value (T.sub.1) by the state variable (T).

10. The method according to claim 3, wherein the information about the vehicle occupant occurs at a time before the point in time (t.sub.1) and upon or after the determination that the point in time (t.sub.1) is less than the time span in the future, and the reduction in speed of the motor vehicle or the switchover to the further drive is implemented at the point in time and/or upon the exceeding of the limit value (T.sub.1) by the state variable (T).

11. The method according to claim 2, wherein the information is a prompt to the vehicle occupant to take over a lateral control of the motor vehicle by means of a control element.

12. The method according to claim 3, wherein the information is a prompt to the vehicle occupant to take over a lateral control of the motor vehicle by means of a control element.

13. The method according to claim 4, wherein the information is a prompt to the vehicle occupant to take over a lateral control of the motor vehicle by means of a control element.

14. The method according to claim 2, wherein a control element coupled mechanically to the wheel is used as the control element.

15. The method according to claim 3, wherein a control element coupled mechanically to the wheel is used as the control element.

16. The method according to claim 4, wherein a control element coupled mechanically to the wheel is used as the control element.

17. The method according to claim 5, wherein a control element coupled mechanically to the wheel is used as the control element.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The disclosure is explained in more detail in the following by means of exemplary embodiments, without limiting the invention. The following is shown:

[0032] FIG. 1 a schematic representation of a region of a motor vehicle; and

[0033] FIG. 2 a diagram in which a state variable of a steering system of the motor vehicle is applied over time.

DETAILED DESCRIPTION

[0034] FIG. 1 shows a schematic representation of a region of a motor vehicle 1, namely a front axle 2 of the motor vehicle 1. Two wheels, 3 and 4, with different driving lanes are arranged on the front axle 2. Each of the wheels, 3 and 4, is rotatably mounted on a wheel carrier 5. The wheel carriers 5 are each rotatably mounted about an axis of rotation 6 on a part of a body 7 of the motor vehicle 1, for example on a cross-member 8. A steering lever 9 is effectively connected, particularly rigidly connected, to each of the wheel carriers 5.

[0035] In the exemplary embodiment shown here, the steering levers 9 are in the form of steering arms, which are connected to one another via a tie rod 10. The tie rod 10 is rotatably mounted about an axis of rotation 11 on each of the steering levers 9. The axes of rotation 11 are each arranged some distance from respective axis of rotation 6 such that a displacement of the tie rod 10, particularly a linear displacement of the tie rod 10, effects a rotational movement of the wheel carriers 5 about respective axis of rotation 6.

[0036] The steering levers 9 and the tie rod 10 are components of a steering system 12 for steering the motor vehicle 1 and/or the wheels, 3 and 4. The steering system 12 has a drive 13, which has at least one electric motor. The drive 13 and/or the electric motor is coupled to the tie rod 10. The drive 13 engages the tie rod 10 directly in this respect. In addition to drive 13, the steering system 12 has a further drive 14, which is designed similarly to drive 13. Upon a first adjustment of the steering system 12, drive 13 is coupled to the tie rod 10, but drive 14 is decoupled from the tie rod 10. Upon a second adjustment on the other hand, drive 13 is decoupled from the tie rod 10 and drive 14 is coupled to the tie rod. Thus, wheels 3 and 4 are optionally steered with the assistance of drive 13 or drive 14. A switchover between the first adjustment and the second adjustment requires a certain time span.

[0037] FIG. 2 shows a diagram in which a state variable of the steering system 12, namely a temperature T, is applied over time t. The state variable is reflected by the curve 15. The state variable is extrapolated over time, namely over the current point in time t.sub.0. To this end, the regression line 16 is derived from the curve 15 of the state variable. A point in time t.sub.1 is calculated from the extrapolation over time, that is, for example, by means of the regression line 16, in said point in time the state variable predictably reaches or exceeds a limit value T.sub.1. Subsequently, the time difference t this point in time has in the future is calculated. Thus, difference t corresponds to the difference between point in time t.sub.1 and point in time t.sub.0.

[0038] At least one countermeasure, which reduces and/or limits a hazard to a vehicle occupant of the motor vehicle 1 upon an at least partial failure of the steering system 12, is stored in the motor vehicle 1 and/or the steering system 12. This countermeasure may be, for example, the previously mentioned switchover between drive 13 and further drive 14. Alternatively, the countermeasure may be the reduction in speed of the motor vehicle 1. The particular time span in which the effect is deployed is determined for the countermeasure. In the case of switchover between drives 13 and 14, the time span describes the time that is necessary for switchover between the drives. If the countermeasure is the reduction in speed, the time span thus describes the time that is necessary to reduce the speed to a particular speed or until stoppage of the motor vehicle.

[0039] If it is then determined that the point of time t.sub.1 in which the state variable T exceeds the limit value T.sub.1 is less than the time span in the future, the countermeasure or one of the countermeasures is thus introduced immediately. It may be provided that information on the vehicle occupant is in the introduced countermeasure. In this case, the time span is, for example, the time period minimum that is required by the vehicle occupant or a driver of the motor vehicle in order to take over the lateral control completely. For example, the time span is at least 1 second, at least 5 seconds, or at least 10 seconds. After the information, another one of the countermeasures, that is a countermeasure different from the information, is undertaken preferably only upon the reaching of point in time t.sub.1.

[0040] A reliable and safe lateral control of the motor vehicle 1 can be achieved with the described procedure and the described design of the motor vehicle 1. To this end, countermeasures are introduced particularly well before an at least partial failure of the steering system 12.