CN110871843A

CN110871843A - Chassis for a motor vehicle, motor vehicle and method for operating a motor vehicle

Info

Publication number: CN110871843A
Application number: CN201910827374.3A
Authority: CN
Inventors: F.米勒; K.贝利奇
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2018-09-04
Filing date: 2019-09-03
Publication date: 2020-03-10
Anticipated expiration: 2039-09-03
Also published as: CN110871843B; DE102018214983A1

Abstract

The invention relates to a chassis (20, 30) for a, in particular, autonomous motor vehicle (10), said motor vehicle (10) having two wheels (21, 22, 31, 32) and a steering (23, 33). The steering mechanism (23, 33) has a restoring device (26, 27, 36, 37) which is designed to set the chassis (20, 30) in a neutral position. The invention further relates to a particularly autonomous motor vehicle (10) having two such chassis (20, 30). In a method for operating a particularly autonomous motor vehicle (10), the motor vehicle (10) is controlled in all-wheel mode during normal operation. The motor vehicle (10) is controlled only by means of an uninjured steering gear (23, 33) in emergency operation, in which the steering gear (23, 33) of one of the chassis (20, 30) is disabled.

Description

Chassis for a motor vehicle, motor vehicle and method for operating a motor vehicle

Technical Field

The invention relates to a particularly autonomous motor vehicle and to a chassis for a particularly autonomous motor vehicle. The invention further relates to a method for operating a motor vehicle, in particular an autonomous motor vehicle. Furthermore, the invention relates to a computer program for carrying out each step of the method and to a machine-readable storage medium storing the computer program. Finally, the invention relates to an electronic control unit which is set up to carry out the method.

Background

In conventional motor vehicles, the wheels of the front axle are steered. In a few motor vehicles, a steered rear axle is additionally provided for increasing the driving power. Such an all-wheel steering mechanism works mechanically together with a planetary gear (Planetengetriebe). The rear wheels are deflected in the same direction as the front wheels when the steering angle is small, and they are deflected in the opposite direction when the steering angle is large. This allows the turn circumference to be reduced by reversing the rear wheels at a larger steering angle (Wendekreises). Further, for medium and low speeds, the lateral power can be increased by reversely steering the rear wheels at a smaller steering angle. For higher speeds, an improvement in driving stability can be achieved by steering the rear wheels in reverse at a small angle.

DE 102015011408B 3 describes a steering mechanism for a vehicle having steerable front wheels on a front axle and steerable rear wheels on a rear axle. The wheels each have an actual wheel steering angle and can each be adjusted to a target wheel steering angle by means of an actuator. The steering radius currently described by the motor vehicle is continuously adjusted by adjusting the actual wheel steering angle on at least one of the axles, wherein the target wheel steering angle is adjusted by actuating the steering handle. The steering handle has a zero position. When the target wheel steering angle is predefined by the steering handle in the range around the zero position, the rear wheels change their actual wheel steering angle when the actual wheel steering angle of the front wheels is constant.

Disclosure of Invention

The chassis for a particularly autonomous motor vehicle has two steerable wheels and a steering mechanism. Furthermore, it has a resetting device which is set up to place the chassis in the neutral position. The "intermediate position" is understood here to mean a position of the chassis in which the two wheels of the chassis are arranged parallel, in particular parallel to the longitudinal axis of the vehicle. Thus, if no further steering intervention is performed by the steering mechanism, the chassis is forcibly placed in the neutral position by the resetting device. In other words, the intermediate position is a position of the chassis in which the running vehicle runs straight.

By "chassis" is meant the component of a motor vehicle which comprises at least wheels, wheel suspensions and steering mechanisms. Furthermore, the wheel carrier, wheel bearings, brake, subframe (Fahrschemel) and suspension (Federung) can also be part of the chassis.

The invention is based on the following recognition: a chassis of this type can be part of an all-wheel steering mechanism, which can be used in particular for autonomous motor vehicles. In the case of a steering mechanism for an autonomous vehicle, the steering drive is designed as a multiple-redundant construction. In the event of a failure of the semiconductors or the windings, the torque of the steering drive is taken over by the remaining branch windings of the electric drive. Due to the corresponding oversizing of the drive, the necessary steering torque can also be applied in the event of a branch failure. However, the redundancy necessary in autonomous motor vehicles with all-wheel steering is already achieved by the fact that the motor vehicle has two steering mechanisms. If one steering mechanism fails, the other steering mechanism can always be used to control the motor vehicle. However, this requires that the wheels of the chassis with the failed steering mechanism are placed in a neutral position and behave in the subsequent steering movement like the rigid wheels of a conventional vehicle with a front-wheel steering mechanism. Although, in general, during cornering, a restoring force is acting due to the caster (Nachlauf) of the wheels, said restoring force generates a moment which places the wheels in a straight position and thus the chassis in a neutral position. The magnitude of the acting force, however, depends in this case on the caster, which in turn influences the driving power. For low caster, it may not be possible to put the chassis back into the neutral position again fast enough in the event of a failure of the steering mechanism for ensuring the controllability of the motor vehicle. However, the resetting device increases the resetting force in the event of a failure of the steering mechanism, so that the motor vehicle can be quickly controlled.

The return device preferably has springs which are arranged in particular on separate tie rods on both sides of the steering gear. During the steering movement, one of the springs is compressed in each case and generates a restoring force which acts on the separate tie rods in such a way that it returns the chassis into its neutral position when no more torque acts on the autonomous steering drive of the steering gear.

Furthermore, it is preferred that the chassis has a locking element for mechanically locking a steering gear of a steering mechanism of the chassis. If the chassis with the failed steering mechanism is already in its neutral position, it can be locked there by means of a mechanical lock in order to prevent it from moving out of this neutral position again during cornering. This can be achieved in particular by the locking element engaging into a steering rack of the steering gear.

In particular autonomous motor vehicles have two of the above-described chassis. This provides an all-wheel steering system, in particular of an autonomous motor vehicle, which has its beneficial effects on the steering circumference, the lateral dynamics and the driving stability. At the same time, in the event of failure of the steering mechanism of one of the chassis, this chassis can be quickly placed in its neutral position and the steering mechanism of the remaining chassis can take over the control of the motor vehicle. Redundancy of the steering function is thus ensured.

In order to be able to drive the motor vehicle equally well forward and backward, it is preferred that the two chassis are identical. Furthermore, the use of the same components on the front and rear sides of the motor vehicle also facilitates its production.

In a method for operating a particularly autonomous motor vehicle, in normal operation, an all-wheel control or all-wheel steering of the motor vehicle is carried out. "normal operation" means an operation in which no defects of at least one steering system of the motor vehicle are present. In addition to the normal operation, the method provides an emergency operation in which the steering of one of the chassis is disabled. In the emergency mode, the motor vehicle is controlled or steered solely by means of the steering mechanism which is not defective.

In order to ensure that the motor vehicle has the same driving behavior as a conventional motor vehicle which is steered on only one axle in emergency operation, it is preferred that the chassis with the failed steering mechanism is brought into the neutral position and locked therein in emergency operation. In this case, the resetting device can be brought into the intermediate position and can be locked by means of the locking element.

The computer program is set up for: in particular, each step of the method is carried out when it is executed on a computer or an electronic control unit. The computer program enables implementation of the various embodiments of the method on an electronic control unit without structural modifications to the electronic control unit. To this end, the computer program is stored on the machine-readable storage medium.

The computer program is loaded onto a conventional electronic control unit, which is set up to operate a particularly autonomous motor vehicle by means of the method. In particular, autonomous motor vehicles preferably have such an electronic control unit.

Drawings

Embodiments of the invention are illustrated in the drawings and are explained in detail in the following description.

Fig. 1a and 1b show the wheel positions of a particularly autonomous motor vehicle, which is controlled by means of an all-wheel control, according to an exemplary embodiment of the present invention.

Fig. 2 shows a schematic sectional illustration of a particularly autonomous motor vehicle according to an exemplary embodiment of the invention.

Fig. 3a and 3b show the wheel positions of a particularly autonomous motor vehicle according to an exemplary embodiment of the present invention in the event of a failure of the steering mechanism of one of its chassis.

Detailed Description

The particularly autonomous motor vehicle 10 according to one embodiment of the invention has two

wheels

21, 22 on its front axle and two

wheels

31, 32 on its rear axle. In normal operation, all wheels can be steered for enabling all-wheel control of the motor vehicle 10 in this way. Fig. 1a shows the wheel positions of a reverse (gegensingchlags) steering turn at a medium or low speed of the motor vehicle 10, for example not exceeding 50 km/h. Fig. 1b shows a co-directional steering slew at high speeds, e.g. over 50 km/h.

As shown in fig. 2, the motor vehicle 10 has two

chassis

20, 30. Two

front wheels

21, 22 are fixed on the front chassis 20. Which are controlled by means of a front steering mechanism 23. The present invention relates to a rack-and-pinion steering system (zahnstangenlnkung) having a steering gear (lenkgriebe) 231 and a steering rod (lenkstage) 232. The steering rod 232 can be moved during autonomous driving by means of a steering drive device, not shown. The front chassis 20 has a track rod (sprarstaing) with two

partial track rods

24, 25. A spring is arranged as a

return device

26, 27 on each of the

steering tie rods

24, 25. The front steering 23 furthermore has a locking element (arrestierelement) 233, which is designed to mechanically lock the steering rod 232 in such a way that the front chassis 20 can no longer be moved out of its neutral position.

The

rear wheels

31, 32 of the motor vehicle 10 are part of the rear chassis 30 thereof. The rear chassis is identical in structure to the front chassis 20. It has a rear steering 33, which in turn has a steering gear 331, a steering rod 332 and a locking element 333. Furthermore, it has part of the

tie rods

34, 35 and the

return devices

36, 37. The steering drives of the front steering mechanism 32 and the rear steering mechanism 33 are controlled by an electronic controller 40.

If the steering drive of the front steering 23 fails, the

return devices

26, 27 of the front chassis place the front chassis in its neutral position. In the illustrated position of the

wheels

21, 22 of the front chassis, the springs of the restoring device 26, which are arranged on top in fig. 2, are compressed and cause a restoring force, which is indicated by means of an arrow, acting on the tie rods 24 of the latter, which is transmitted via the steering gear 231 to the other tie rod 25 and to the steering rod 232. If the electronic controller 40 recognizes a failure of the steering drive of the front steering mechanism 23, it actuates the actuator by means of which the locking element 233 of the front steering mechanism 23 locks the front steering mechanism in the neutral position as soon as the front chassis 20 reaches its neutral position. The motor vehicle 10 is now switched to an emergency operation, in which the motor vehicle is controlled exclusively by the rear steering 33.

As shown in fig. 3a, vehicle 10 now behaves like a vehicle with a rear axle control when moving in the direction of the arrow shown there. The

rear wheels

31, 32 can be moved for steering the motor vehicle, while the

front wheels

21, 22 are fixed in a straight position (geradeafahretposition).

If the steering drive on the front chassis 20, but in other words on the rear chassis 30, fails, the rear chassis is locked in its intermediate position and the motor vehicle 10 is then controlled by means of the front steering 23. As shown in fig. 3b, the motor vehicle 10, when moving in the direction of the arrow, behaves like a motor vehicle with a front steering, for which the

front wheels

21, 22 can be moved for steering and the

rear wheels

31, 32 are fixed in a straight-ahead position.

Claims

1. Chassis (20, 30) for an in particular autonomous motor vehicle (10) having two wheels (21, 22, 31, 32) and a steering (23, 33), characterized in that it has a resetting device (26, 27, 36, 37) which is set up to place the chassis (20, 30) in a neutral position.

2. Chassis (20, 30) according to claim 1, characterized in that the return means (26, 27, 36, 37) have a spring.

3. Chassis (20, 30) according to claim 1 or 2, characterized in that the chassis furthermore has a locking element (233, 333) for mechanically locking a steering gear (231, 331) of a steering mechanism (23, 33) of the chassis.

4. Motor vehicle (10), in particular autonomous motor vehicle (10), having two chassis (20, 30) according to one of claims 1 to 3.

5. Motor vehicle (10) according to claim 4, characterized in that said two chassis (20, 30) are identical.

6. Method for operating a particularly autonomous motor vehicle (10) according to claim 4 or 5, wherein the motor vehicle (10) is controlled all-wheel in normal operation and the motor vehicle (10) is controlled only by means of the steering mechanism (23, 33) which is not deactivated in emergency operation, in which the steering mechanism (23, 33) of one of the chassis (20, 30) is deactivated.

7. Method according to claim 6, characterized in that in emergency operation the chassis (20, 30) with the failed steering mechanism (23, 33) is brought into an intermediate position and locked in the intermediate position.

8. Computer program which is set up for carrying out each step of the method according to claim 6 or 7.

9. A machine readable storage medium having stored thereon the computer program according to claim 8.

10. Electronic control unit (40) which is set up for operating a particularly autonomous motor vehicle (10) by means of the method according to claim 6 or 7.

11. Motor vehicle (10) according to claim 4 or 5, characterized in that it has an electronic controller (40) according to claim 10.