WO2009155913A1

WO2009155913A1 - Vehicle

Info

Publication number: WO2009155913A1
Application number: PCT/DE2009/050033
Authority: WO
Inventors: Metin Ersoy
Original assignee: Zf Friedrichshafen Ag
Priority date: 2008-06-27
Filing date: 2009-06-18
Publication date: 2009-12-30
Also published as: DE102008002719A1

Abstract

Disclosed is a vehicle comprising a chassis (2), two front wheel carriers (3, 4) which are connected to the chassis (2) and on each of which a front wheel (9, 10) is rotatably mounted, a front axle steering mechanism that allows the front wheel carriers (3, 4) to be swiveled, two rear wheel carriers (5, 6) which are connected to the chassis (2) and on each of which a rear wheel (11, 12) is rotatably mounted, and a rear axle steering mechanism which allows the rear wheel carriers (5, 6) to be swiveled. Both the front axle steering mechanism and the rear axle steering mechanism are designed as an electric steering mechanism and are or can be controlled by means of a controller (33) such that the total current consumed by the steering mechanism does not exceed a predefined threshold value.

Description

vehicle

description

The invention relates to a vehicle having a vehicle body, two front wheel carriers connected to the vehicle body, on each of which a front wheel is rotatably mounted, a front axle steering, by means of which the front wheel carriers are pivotable, two rear wheel carriers connected to the vehicle body, to each of which a rear wheel is rotatably supported, and a rear axle steering, by means of which the rear wheel carrier are pivotable.

US 2007/0144818 A1 describes a vehicle having a front steering gear which is connected to steerable front wheels and can be operated to pivot the front wheels by means of a steering wheel to which a torque sensor is connected. Furthermore, a rear steering gear is provided, which is connected to steerable rear wheels. A controller connected to the torque sensor is connected to the rear steering gear and can operate this in response to an output signal of the torque sensor when a predetermined steering wheel force engages the steering wheel. By turning the rear wheels in a direction opposite to the front wheels, the steering radius of the vehicle can be reduced.

Electric steering systems have many advantages over hydraulic steering systems and are increasingly used in passenger cars up to the middle class. However, the use in passenger cars of the upper class fails, because due to the steering forces and steering dynamics occurring here electric motors are required, which require a current of more than 8OA. A current of 8OA is for today's cars with a 12V electrical system but the upper limit, which may accommodate a single electrical consumer. Thus, smaller vehicles may be equipped with electric steering, larger ones Vehicles, however, not because their higher weight would have an excessive power consumption of the electric motors result. Therefore, hydraulic solutions are used for larger vehicles.

Based on this prior art, the invention has the object to be able to use an electric front-axle steering even in a larger vehicle.

This object is achieved with a vehicle according to claim 1 and with a use according to claim 10. Preferred embodiments of the invention are given in the dependent claims.

The vehicle according to the invention, in particular motor vehicle, has a vehicle body, two front wheel carriers connected to the vehicle body, on each of which a front wheel is rotatably mounted, a front axle steering, by means of which the front wheel brackets are pivotable, two rear wheel carriers connected to the vehicle body, on each of which a rear wheel is rotatably mounted, and a rear axle steering, by means of which the rear wheel carrier are pivotable, both the front axle steering and the rear axle steering are designed as electrical steering and controlled by a controller such or can be that the total power consumption of the steering a predetermined Limit does not exceed.

Since a steering movement of the vehicle is supported by the rear axle steering, a steering lever associated with the front wheels of the vehicle according to the invention can be designed to be longer than the same vehicle without rear axle steering at the same turning circle. The longer lever allows the use of a weaker electric drive for the front axle steering, so that their current consumption and / or the sum of the power consumption of both steering systems does not exceed a predetermined limit. Although it is possible that the longer steering lever has a reduction of the steering angle of the front wheels result, but this is compensated by the contribution of the rear axle steering to the steering movement of the vehicle, so that despite a smaller steering angle of the front wheels of the turning circle of the vehicle does not exceed a desired size , Therefore, a turning circle can be achieved with the vehicle according to the invention, the only without a rear axle steering stronger electric drive would be possible. The limit value is preferably 8OA, in particular in the case of a 12V vehicle electrical system.

In particular, the term "steer" is to be understood to mean the meaning of "steer" and / or "steer." The rear axle steering and the front axle steering are thus controlled and / or regulated by means of the control "Total power consumption of the steering" to understand the sum of the power consumption of rear axle steering and front axle steering. The current consumption and the limit value should represent positive values. If, due to the selected counting arrow system, one or more power inputs are negative, their sign must be reversed.

If a simultaneous operation of the steering systems would lead to a total power consumption exceeding the limit value, the rear axle steering and the front axle steering are not operated simultaneously. Preferably, the steering systems are then operated successively or with a time delay, which is controlled in particular by means of the controller. According to one embodiment, by means of the control, in particular as a function of the current consumption of the steering systems, optionally a common or a sequential operation of rear axle steering and front axle steering is possible. Preferably, the front axle steering but operated primarily.

Preferably, each of the wheel carriers is pivotable relative to the vehicle body, in particular about a steering axis extending in or substantially in the vehicle vertical direction. In this case, each of the wheel carriers is preferably assigned a separate steering axle. In particular, each of the wheel carrier is pivotally connected to the vehicle body and preferably resiliently supported with respect to this, so that each of the wheel carrier with respect to the vehicle body and can rebound.

The front axle steering system preferably has a front electric steering drive, by means of which the front wheel carriers are pivotable. Furthermore, the rear axle steering preferably has a rear electric steering drive, by means of which the rear wheel carriers are pivotable. The electric steering drives are connected in particular to an electrical vehicle electrical system. According to one embodiment, the controller forms a common control and / or regulation for the rear axle steering and the front axle steering. Preferably, the rear axle steering and the front axle steering form a four-wheel steering, in particular together with the control. The electric steering drives are preferably connected to the controller, by means of which the electric steering drives, preferably jointly, can be regulated or.

Preferably, a steering wheel rotatable about a steering wheel axis is provided, whose rotation is converted to the steering wheel axis in a pivoting of the wheel carrier. The pivoting of the wheel carriers in response to the rotation of the steering wheel is in particular in accordance with a transfer function which may be the same or different for the individual wheels and / or which may additionally depend on one or more other variables, e.g. of the vehicle speed, the torque exerted on the steering wheel, etc. Preferably, the steering wheel is coupled with the interposition of a sensor arrangement with the controller. In particular, a rotation and / or a torque of the steering wheel is detected by means of the sensor arrangement coupled to the controller and supplied as a signal to the controller. The signal is preferably an electrical signal which carries information about the angle of rotation and / or the torque of the steering wheel.

The steering wheel is preferably rotatably mounted on the vehicle body about the steering wheel axis. According to one embodiment, a steering shaft is rotatably connected to the steering wheel. In particular, the sensor arrangement for detecting the rotation and / or the torque of the steering wheel cooperates with the steering shaft and / or the steering wheel.

Preferably, a front steering gear is provided, which is operated by means of the front electric steering drive for pivoting the front wheel carrier or can be. Furthermore, a rear steering gear is preferably provided, which is actuated by means of the rear electric steering drive for pivoting the rear wheel carrier or can be. According to a first alternative, the steering wheel is mechanically coupled to transmit a rotational movement with the front steering gear, so that the front wheel carrier can be pivoted by means of the steering wheel in a mechanical way. The front electric steering drive supports the pivoting of the front wheel carrier. According to a second alternative, there is no mechanical coupling between the steering wheel and the front steering gear, so that a pivoting of the wheel carrier is carried out purely by electricity (steer-by-wire).

According to a further development, a front steering lever is provided at least on one of the front wheel carrier, by means of which the one or more front wheel carriers are or can be pivoted. In particular, the front steering lever is coupled to the front electric steering drive. This can be done with the interposition of the front steering gear. Preferably, a rear steering lever is provided at least on one of the rear wheel carrier, by means of which the one or more rear wheel carriers are or can be pivoted. The rear steering lever is in particular coupled to the rear electric steering drive. This can be done with the interposition of the rear steering gear.

According to one embodiment of the invention, the front wheel carrier are interconnected by means of a front tie rod and / or the rear wheel carrier connected to each other by means of a rear tie rod.

When parking, the rear wheels are preferably pivoted in opposite directions and / or not simultaneously with the front wheels. In this way, a small turning circle and / or a relatively small total current consumption of the steering can be realized. In a lane change, the rear wheels are preferably pivoted in the same direction and / or simultaneously to the front wheels. By co-directing and / or simultaneously steering both axes, e.g. the vehicle stability can be increased. How much the rear wheels are pivoted compared to the front wheels and whether the rear wheels are pivoted in the same direction or in opposite directions to the front wheels, is controlled by the controller and / or controlled. Preferably, the controller is connected to a speed sensor, by means of which the speed of the vehicle can be determined, so that the pivoting of the wheels can also depend on the determined vehicle speed.

The invention further relates to the use of a rear axle steering system of a vehicle, in particular a motor vehicle, for reducing the power consumption of an electric front axle steering system of the vehicle. Since the vehicle is preferably a vehicle according to the invention it may be developed according to all the embodiments described in this context. In particular, the rear axle steering is an electric rear axle steering system. Furthermore, the rear axle steering and the front axle steering can be jointly controlled and / or controlled.

According to a further development, the rear axle steering and the front axle steering are optionally operated jointly or sequentially. Preferably, the front axle steering is operated primarily. In particular, the choice of joint or sequential operation of the steering systems depends on the power consumption of one or both of the steering systems. Of course, this choice may also depend on other parameters.

According to one embodiment, the invention proposes the integrated use of electric front axle steering and rear axle steering, which in combination with the electric front axle steering reduces the necessary front wheel steering angle, e.g. about 15 - 20%, because the rear wheels are deflected. In such a case, an electric front axle steering can be used, which has a 20% lower performance than a hydraulic front axle steering without rear axle steering, since the lack of power is compensated by the rear wheel steering. The realization is very easy by extending the steering lever on the wheel possible.

There is thus the possibility of using electric power steering in vehicles of the upper middle class, without the power requirement exceeding the electrical system limit of 8OA. Thus, e.g. the electric steering of a smaller vehicle can be used in a larger vehicle, which is constructed on the same platform as the smaller vehicle, wherein only the steering lever is extended, e.g. about 20%. The thus reduced by 20% wheel steering angle of the front wheels is compensated by the rear wheel steering. According to one embodiment, the two steering systems are controlled together.

The invention will be described below with reference to a preferred embodiment with reference to the drawing. In the drawing show:

Fig. 1 is a schematic plan view of a vehicle according to a Embodiment of the invention,

Fig. 2 is a schematic plan view of the vehicle during parking and

Fig. 3 is a schematic plan view of the vehicle during a lane change.

From Fig. 1 is a schematic plan view of a vehicle 1 according to an embodiment of the invention can be seen, wherein on a vehicle body 2 a plurality of wheel carrier 3, 4, 5 and 6 are articulated. The wheel carriers 3 and 4 are part of a steerable front axle 7, and the wheel carriers 5 and 6 are part of a steerable rear axle 8. On the wheel carriers 3, 4, 5 and 6 are each a vehicle wheel 9, 10, 11 and 12 rotatably mounted, wherein the axis of rotation of the vehicle wheel 9 by the reference numeral 13, the axis of rotation of the vehicle wheel 10 by the reference numeral 14, the axis of rotation of the vehicle wheel 11 by the reference numeral 15 and the axis of rotation of the vehicle wheel 12 by the reference numeral 16. The front wheel carriers 3 and 4 are coupled together by means of a front tie rod 17, which is articulated to each of the front wheel carriers 3 and 4. Further, the wheel carrier 5 and 6 are coupled together by means of a rear tie rod 18 which is pivotally connected to each of the rear wheel carrier 5 and 6. The wheel carrier 4 has a steering lever 19, with which a steering gear 20 is connected by means of a connecting piece 21. The steering gear 20 can move the connecting piece 21 in and counter to the direction of travel x, so that the wheel carrier 4 can be pivoted together with the vehicle wheel 10 in the direction of the arrow 22 relative to the vehicle body 2. The front steering gear 20 is connected to a designed as an electric motor front electric steering drive 23, by means of which the front steering gear 20 is actuated and thus the vehicle wheel 10 can be pivoted. Because of the tie rod 17, a pivoting movement of the wheel carrier 4 is also transmitted to the wheel carrier 3. As can be seen from the figure, the steering lever 19 extends in or substantially in the vehicle transverse direction y.

At the rear wheel 6, a rear steering lever 24 is provided, with the interposition of a connecting piece 25, a rear steering gear 26 is connected, which the connector 25 in and move x opposite the direction of travel and thus the wheel carrier 6 with the vehicle wheel 12 in the direction of the arrow 27 can pivot relative to the vehicle body 2. With the rear steering gear 26, a rear electric steering drive 28 is connected, by means of which the rear steering gear 26 is actuated and thus the vehicle wheel 12 can be pivoted. Because of the tie rod 18, a pivoting movement of the wheel carrier 6 is also transmitted to the wheel carrier 5. As can be seen from the figure, the steering lever 24 extends in or substantially in the vehicle transverse direction y.

The vehicle 1 has a steering wheel 29, which is rotatably mounted in the direction of the arrow 30 on the vehicle body 2. The steering wheel 29 is non-rotatably connected to a steering shaft 31 to which a sensor arrangement 32 is provided, by means of which the angle of rotation of the steering wheel 29 and a torque exerted on this detected and can be delivered as electrical signals to a controller 33. The controller 33 evaluates the signals and optionally one or more other signals, e.g. the vehicle speed, and controls the electric steering drives 23 and 28 such that the rotation angle of the steering wheel 29 associated pivoting of the vehicle wheels 9, 10, 11 and 12 is made. The electrical steering drives 23 and 28 and the controller 33 are supplied from an electrical system 34 with electrical energy. The transfer of a rotational movement of the steering wheel to the vehicle wheels 9 to 12 can be done only electrically (steer-by-wire). Alternatively, it is possible that the front steering gear 20 is mechanically coupled to the steering shaft 31 (indicated by dashed lines), so that between the steering wheel 30 and the steering gear 20 is a mechanical coupling. In Fig. 1, the vehicle wheels 9, 10, 11 and 12 are shown unpivoted, so that the vehicle 1 in the direction of travel x drives straight out.

From Fig. 2 it can be seen that the vehicle wheels 9 and 10 are pivoted in the direction of the arrows 35 and 36 to the left, whereas the wheels 11 and 12 are pivoted in the direction of the arrows 37 and 38 in the opposite direction as the wheels 9 and 10 , The means of

Control device 33 caused opposite pivoting of the front and rear vehicle wheels is particularly suitable for parking the vehicle 1, since a comparatively small turning circle or steering radius can be achieved. When parking but can large steering moments occur so that the front wheels are preferably not pivoted simultaneously with the rear wheels. In particular, the pivoting of the front wheels and the pivoting of the rear wheels takes place sequentially. Preferably, opposite pivoting of front and rear vehicle wheels is performed only at relatively low speeds of the vehicle.

According to one embodiment, the front wheels in one direction are maximally up to a front limit angle of e.g. 32 ° swiveling. If this angle is insufficient, the rear wheels are in the opposite direction at most up to a rear critical angle of e.g. 8 ° swiveling. Thus, a relatively small turning circle for the vehicle can be realized, although the swing angle of the front wheels is limited to the front limit angle. This limitation is based here on the fact that the length of the front steering lever is extended relative to the length of the front steering lever of a similar vehicle without rear-wheel steering, e.g. by 20%. By extending the front steering lever, it is possible to use a weaker front steering drive with a lower power consumption in the vehicle according to the invention.

At higher speeds and / or a lane change, the vehicle wheels 9, 10, 11 and 12 are preferably deflected in the same direction, which can be seen in Fig. 3, after which the vehicle wheel 11 in the direction of arrow 39 and the vehicle wheel 12 in the direction of the arrow 40 is pivoted. In particular, at relatively high speeds and / or when changing lanes, comparatively small steering torques occur which, for example, are significantly smaller than the steering torques occurring during parking. The bar provided with the reference numeral 2 represents in FIGS. 2 and 3 schematically the vehicle body. LIST OF REFERENCE NUMBERS

Vehicle Body structure Wheel carrier Wheel carrier Wheel carrier Front axle Rear axle Vehicle wheel Vehicle wheel Vehicle wheel Vehicle wheel Rotary axis Rotary axis Rotary axis Rotary axis Front tie rod Rear tie rod Front steering lever Front steering gear Front connector Swivel direction Front electric steering drive Rear steering lever Rear connector Rear steering mechanism Pivoting direction Rear electric steering drive Steering wheel Direction of rotation of the steering wheel Steering shaft 32 sensor arrangement

33 control

34 electrical wiring system

35 pivoting direction

36 pivoting direction

37 pivoting direction

38 pivoting direction

39 pivoting direction

40 pivoting direction x direction of travel y vehicle transverse direction

Claims

Vehicle patent claims

1. vehicle having a vehicle body (2), two with the vehicle body (2) connected to the front wheel carriers (3, 4), on each of which a front wheel (9, 10) is rotatably mounted, a Vorderachslenkung, by means of which the front wheel carrier (3 , 4) are pivotable, two with the vehicle body (2) connected rear wheel carriers (5, 6), on each of which a rear wheel (11, 12) is rotatably mounted, a Hinterachslenkung, by means of which the rear wheel carrier (5, 6) pivotally are, characterized in that both the front axle steering and the rear axle steering are formed as an electric steering and by means of a controller (33) are controlled or can be such that the total current consumption of the steering does not exceed a predetermined limit.

2. Vehicle according to claim 1, characterized in that the front axle steering and the rear axle steering are operated by the controller sequentially or can be.

3. Vehicle according to claim 1 or 2, characterized in that the front axle steering and the rear axle steering by means of the controller are either operated jointly or sequentially, or may be, with priority, the front axle steering is operated.

4. Vehicle according to one of the preceding claims, characterized in that the front axle steering has a front electric steering drive (23) by means of which the front wheel carrier (3, 4) are pivotable, the rear axle steering a rear electric steering drive (28), by means of which the rear wheel carriers (5, 6) are pivotable, the electric steering drives (23, 28) are connected to an electrical vehicle electrical system (34) and connected to the controller (33), by means of which the electric steering drives (23, 28) are controlled or can be.

5. Vehicle according to claim 4, characterized in that at least on one of the front wheel carrier (4) with the front electric steering drive (23) coupled front steering lever (19) is provided, by means of which or the front wheel carrier (3, 4) be pivoted or can be, at least on one of the rear wheel (6) with the rear electric steering drive (28) coupled rear steering lever (24) is provided, by means of which or the rear wheel (5, 6) are pivoted or can be ,

6. Vehicle according to one of the preceding claims, characterized by a rotatable steering wheel (29) whose rotation and / or torque detected by means of a controller (33) coupled to the sensor arrangement (32) and as an electrical signal to the controller (33) is supplied or can be .

7. Vehicle according to claim 6, characterized by a with the steering wheel (29) rotatably connected steering shaft (31) which is mechanically coupled to a front steering gear (20) which by means of the front electric steering drive (23) for pivoting the front wheel carrier (23). 3, 4) is or can be operated.

8. Vehicle according to one of the preceding claims, characterized in that the front wheel carrier (3, 4) by means of a front tie rod (17) are interconnected, the rear wheel carrier (5, 6) by means of a rear tie rod (18) are interconnected ,

9. Vehicle according to one of the preceding claims, characterized in that when parking the vehicle, the front wheels (9, 10) and the rear wheels (11, 12) are pivoted or can be sequential, the lane change of the vehicle, the front wheels (9, 10) and the rear wheels (11, 12) can be or can be pivoted simultaneously.

10. Use of an electric rear axle steering of a vehicle (1) for reducing the power consumption of an electric front axle steering of the vehicle (1).

11. Use according to claim 10, characterized in that the rear axle steering and the front axle steering are operated either jointly or sequentially, with priority, the front axle steering is operated.

12. Use according to claim 11, characterized in that the choice of the common or sequential operation of the steering systems depends on the current consumption of one or both steering systems.