WO2012167978A1

WO2012167978A1 - Steering system in a vehicle

Info

Publication number: WO2012167978A1
Application number: PCT/EP2012/056810
Authority: WO
Inventors: Achim Neubauer; Hussam Helmi
Original assignee: Robert Bosch Gmbh
Priority date: 2011-06-10
Filing date: 2012-04-13
Publication date: 2012-12-13
Also published as: CN103717476A; DE102011084507A1; CN103717476B

Abstract

The invention relates to steering system in a vehicle comprising a steering shaft (3) for transmitting a steering angle and an electric servomotor (7) for generating supporting torque, said servomotor being coupled to the steering shaft. Said steering shaft and the servomotor are received in a common bearing housing (8). Electronic components for controlling the servomotor are housed on the electronic printed circuit board (40) which is provided with a recess (41) through which the steering shaft is guided.

Description

description

title

Steering system in a vehicle The invention relates to a steering system in a vehicle according to the generic term of claim 1.

PRIOR ART Known steering systems in vehicles have a steering shaft via which the steering shaft

Driver by pressing the steering wheel sets a steering angle, which is implemented via a coupling of the steering shaft with a rack in a Radlenkwinkel the steerable wheels of the vehicle. For steering power assistance, an electric servomotor can be used, which, for example, according to DE 197 03 903 A1 acts directly on the steering shaft and this is acted upon by a supporting servo torque.

DISCLOSURE OF THE INVENTION The object of the invention is to design a steering system in a vehicle with simple structural measures with compact steering assistance.

This object is achieved according to the invention with the features of claim 1. The dependent claims indicate expedient developments.

By means of the steering system according to the invention, a steering angle predefined by the driver can be converted into a wheel steering angle of the steerable wheels in vehicles. The steering system includes a steering shaft connected to a driver-operable steering wheel, and a steering linkage including a rack which is actuatable by and operable by the steering shaft the desired angle on the steerable wheels is adjustable. For steering power assistance, an electric servomotor is used, which is advantageously coupled to the steering shaft. Upon actuation of the servomotor, the rotational movement of the steering shaft is acted upon by a supporting moment.

The kinematic coupling between the motor shaft of the electric servomotor and the steering shaft via transmission components, which are designed for example as a worm and worm wheel, wherein the worm is driven by the motor shaft and the worm wheel rotatably connected to the steering shaft can be connected. According to an advantageous embodiment, the worm is formed integrally with the motor shaft.

The steering shaft and the servo motor can be accommodated in a common bearing housing, wherein the motor longitudinal axis expediently extends at least approximately orthogonal and laterally offset from the steering shaft axis. The servomotor can be held on a bearing flange of the bearing housing. The inclusion of the servomotor in or on the bearing housing takes place in particular in such a way that servomotors with stators of different lengths can be used.

To control the electric servomotor, electronic components are used on an electronic circuit board, which is held on the bearing housing. The electronic circuit board has a recess through which the steering shaft is passed, wherein in the mounted state, the plane of the electronic circuit board is at least approximately perpendicular to the longitudinal axis of the steering shaft. The steering system designed in this way is compact and has both in the axial direction and in the radial direction - with respect to the steering shaft longitudinal axis - small dimensions. The integrated electronic circuit board in the bearing housing requires no or only slightly larger space. In the bearing housing, a recess for receiving the steering shaft is inserted, into which the electronic circuit board can be inserted or which can be covered by the electronic circuit board.

The recess in the electronic circuit board, through which the steering shaft is guided, is formed either as a hole, which is surrounded on all sides by the electronic circuit board, or as a U-shaped recess, which extends to the edge of the electronic circuit board. Another advantage is that due to the passage of the steering shaft through the recess in the electronics board a correct position centering of the electronic board is given in the bearing housing. In the direction of rotation about the longitudinal axis of the steering shaft, the desired position of the electronic circuit board can be defined by stops or positive locking elements on the bearing housing. Overall, this assembly is simplified.

According to an expedient embodiment, it is provided that the electronic board is equipped both with power electronics and with control electronics. In this embodiment, both the power electronics and the control electronics are located on a common board, which is provided with the recess for passing the steering shaft. In an alternative embodiment, in contrast, it is provided that the power electronics and the control electronics are located on different boards, but which are expediently connected, for example such that both boards are accommodated in a common electronics housing. The provided with the recess for the steering shaft board is expediently carrier of the power electronics, whereas the second board receives the control electronics. Optionally, the two boards with the power electronics or the control electronics are aligned at an angle to each other, in particular in a 90 ° angle. During assembly, the power electronics and the terminal lugs or contacts of the servomotor may be welded together in a common step on the electronic board.

According to another expedient embodiment, a magnetic element is arranged on the end face of the motor shaft of the servomotor, which is part of a Rotorlagesenso- rik and a housing fixed arranged magnetic field sensor is assigned to an electronic board. The current position of the motor shaft can be determined via the rotor position sensor. The magnetic field sensor is located in particular on that electronic board which extends orthogonal to the motor shaft longitudinal axis. This is preferably that board, which is provided in addition to that with the recess for the steering shaft and preferably includes an angle of at least approximately 90 ° with this. In the embodiment of the gear parts for coupling the electric servo motor with the steering shaft as a worm and worm wheel, the board containing the recess is preferably arranged adjacent to the worm wheel. The worm wheel and the electronic board extend in parallel planes. It may be expedient to arrange a protective disk between the electronic circuit board and the worm wheel, which protects the board or the electronic components arranged thereon from contamination and grease originating from the worm wheel.

Further advantages and expedient embodiments can be taken from the further claims, the description of the figures and the drawings. Show it:

1 is a schematic view of a steering system in a vehicle, with a servo motor associated with the steering shaft of the steering system,

2 shows a bearing housing including a servomotor and a power and control electronics controlling the servomotor,

3, but with attached housing shell of the servomotor receiving housing portion,

4 shows a section through a bearing housing for receiving the steering shaft and the servomotor along the motor shaft longitudinal axis,

Fig. 5 shows a bearing housing with servo motor, on the motor shaft frontally a magnetic element can be placed, with one of the front side of the motor shaft upstream control electronics.

6 is a perspective view of the bearing housing, with an electronic board, in which a recess is introduced, through which the steering shaft is passed,

7 shows a section through the bearing housing along the steering shaft longitudinal axis.

In the figures, the same components are provided with the same reference numerals. The steering system 1 shown in Fig. 1 in a vehicle comprises a steering wheel 2, a steering shaft 3, a steering gear 4, a steering linkage 5 with a rack and steerable wheels 6. The driver is by operation of the steering wheel 2, a steering angle 5 _L w in the connected to the steering wheel steering shaft 3, which adjusts the rack of the steering linkage 5 in the transverse direction via the steering gear 4, whereupon the wheel steering angle δ _{ν is} set at the steerable wheels.

An electric servomotor 7, which introduces a supporting drive torque into the steering shaft 3 via a transmission, serves to assist the steering force. The transmission comprises a worm on a shaft portion of the motor shaft of the servomotor 7 and a worm gear meshing with the worm, which is rotatably connected to the steering shaft 3. The steering shaft 3 and the motor shaft of the electric servomotor 7 are accommodated in a bearing housing 8 of the steering system 1.

In the figures 2 and 3 and in the sectional view of FIG. 4, an embodiment with a bearing housing 8 is shown, which is provided with a two-part motor bearing housing 10. A housing shell 10a of the motor bearing housing 10 is integrally formed with the housing portion having a

Has receiving opening 9 for the steering shaft. A second housing shell 10b can be placed on the first housing shell 10a. The first and the second housing shell 10a, 10b are not formed symmetrically; the detachable, second housing shell 10b has, in the area of the stator-side end face, a vertical, archway-shaped section which can be inserted into a corresponding recess on the housing shell 10a fixed to the housing.

The bearing housing 8 has a receiving opening 9 for the steering shaft in a first housing section. A second housing portion of the bearing housing 8 forms the engine mount housing 10 for receiving the electric servomotor

7, wherein the longitudinal axis 13 of the motor bearing housing 10 extends orthogonal and laterally offset from the longitudinal axis 14 of the receiving opening 9 and the steering shaft used. Overall, the engine mount housing 10 is composed of a motor shaft housing 11, in which the motor shaft 15 of the servomotor 7 is received, and a stator housing 12 for receiving the stator 16 of the servomotor together. The motor shaft 15 is mounted in two housing-side individual bearings 17 and 18, of which the stator 16 adjacent individual bearings 17, which is axially upstream of the stator, designed as a floating bearing and the statorferne single bearing 18 as a fixed bearing. The two individual bearings 17 and 18 are axially on opposite sides relative to a worm 19, which meshes with the worm wheel 20 schematically indicated in Fig. 4, which is rotatably connected to the steering shaft 3. The individual bearing 18 is adjacent to the free end face of the motor shaft 15. The entire, the stator 16 axially überragen- de shaft portion, which is also a carrier of the screw 19, is integral with the

Motor shaft 15 executed or is formed by the motor shaft 15. As a result, the bearing of the motor shaft 15 in the bearing housing 8 with only two individual bearings 17, 18 is possible.

FIGS. 2 and 4 also show power electronics 23 comprising a number of power electronics components on a circuit board for controlling the servomotor. The power electronics 23 is arranged on a housing-side mounting platform 24, which adjoins the stator housing 12 and is formed as a flat plate which extends tangentially to the motor shaft housing 11 and parallel to the motor shaft. On the side opposite to the stator 16 of the servomotor, the electronics has an angled section 25, which forms the control electronics on a circuit board. The control electronics 25 extends orthogonal to the motor shaft longitudinal axis 13 and is located axially in front of the free end face of the motor shaft of the servomotor. The control electronics 25 may optionally have a magnetic field sensor which senses the magnetic field of a magnetic element 21, which is attached to the free end face of the motor shaft and rotates together with the motor shaft 15. The magnetic element 21 and the magnetic field sensor together form a rotor position sensor for determining the current rotational position of the motor shaft 15.

In the embodiment according to FIG. 5, the magnetic element 21 and the axially upstream magnetic field sensor 22 of the rotor position sensor system are shown.

6 and 7, the bearing housing 8 with mounted steering shaft 3 and e- lektrischem servo motor 7 is shown. The electronic components of the power electronics 23 are arranged on an electronic circuit board 40, which has a Has recess 41 through which the steering shaft 3 is passed in the mounted state. The plane of the electronic circuit board 40 is perpendicular to the longitudinal axis 14 of the steering shaft 3. The power electronics 23 is located on the upper side of the electronic circuit board 40 and is connected to the stator 16 of the electric servo motor, which is arranged on a stator flange 28 of the bearing housing 8. The stator flange 28 is located in a plane orthogonal to the electronic circuit board 40. The motor shaft longitudinal axis is orthogonal to the steering shaft longitudinal axis 14 and offset parallel to this. The motor shaft of the electric servomotor is accommodated in a motor shaft housing 11, which is formed integrally with the bearing housing 8 and extends below the electronic circuit board 40.

In Fig. 7, the bearing housing 8 is shown with an attached cover 42, which advantageously consists of plastic. The cover 42 has a dome 43, through which the steering shaft 3 is passed. When assembled, the cover 42 covers the electronics board 40 including the received thereon

Power electronics 23 and possibly also the servo motor 7. The cover 42 may be made of plastic, possibly made of fiber-reinforced plastic.

The motor shaft 15 is a carrier of the worm, which meshes with the worm wheel 20, which is non-rotatably connected to the steering shaft 3. The steering shaft 3 is received on axially opposite sides of the worm wheel 20 in pivot bearings, which may be formed as eccentric bearing for radial adjustability of the steering shaft 3. For reasons of protection, it may be expedient to arrange a protective screen 44 which is fixed to the housing immediately below the electronics board 40 and which has the function of keeping grease originating from the worm wheel 20 away from the electronic board 40. The protective disk 44 extends in the radial direction at least as far as the worm wheel 20.

The control electronics can also be arranged on the electronic board 40. However, an embodiment is also possible in which the control electronics are arranged on a further circuit board which extends at an angle, in particular at a 90 ° angle, to the power electronics, as in the embodiment according to FIGS. 2 to 5 is shown. Even in these cases, it is expedient that the electronic board, which is perpendicular to Steering shaft longitudinal axis 14 extends, has a central recess through which the steering shaft 3 is passed.

Claims

Steering system in a vehicle, comprising a steering shaft (3) for transmitting a steering angle predetermined by the driver, and an electric servomotor (7) for generating an assisting drive torque, characterized in that an electronic circuit board (40) with electronic components for controlling the servomotor (7 ) is provided with a recess (41), wherein the steering shaft (3) through the recess (41) in the electronic circuit board (40) is guided and the plane of the electronic circuit board (40) at least approximately perpendicular to the longitudinal axis of the steering shaft (3).

Steering system according to claim 1, characterized in that an electronic board (40) is provided with power electronics and control electronics.

Steering system according to claim 1, characterized in that a first E- lektronikplatine with power electronics (23) and a second electronic board (40) is provided with a control electronics (25).

Steering system according to claim 3, characterized in that the electronic board (40) with the power electronics (23) and the electronic board (40) with the control electronics (25) are aligned at an angle to each other.

Steering system according to one of claims 1 to 4, characterized in that the recess (41) for the steering shaft (3) containing the electronic circuit board (40) has the power electronics (23).

Steering system according to one of claims 1 to 5, characterized in that on the end face of the motor shaft (15) of the servomotor (7), a magnetic element (21) is arranged, which is part of a rotor position sensor and a housing fixedly arranged magnetic field sensor (22) on a Electronic board (40) is assigned.

7. Steering system according to claim 6, characterized in that the magnetic field sensor (22) on the electronic circuit board (40) is arranged, which extends orthogonal to the motor shaft longitudinal axis.

8. Steering system according to one of claims 1 to 7, characterized in that integrally with the motor shaft (15) of the servo motor (7) is formed a stator (16) of the servomotor (7) axially superior shaft portion, the carrier of a screw (19 ) which meshes with a worm wheel (20) connected to the steering shaft (3).

9. Steering system according to claim 8, characterized in that the recess (41) for the steering shaft (3) containing the electronic board (40) adjacent to the worm wheel (20) is arranged.

10. Steering system according to claim 9, characterized in that between E- lektronikplatine (40) and worm wheel (20) a protective plate (44) is arranged.

1 1. Steering system according to one of claims 1 to 10, characterized in that the steering shaft (3) and the servo motor (7) are accommodated in a common bearing housing (8) and the servo motor (7) with the steering shaft (3) is coupled ,

12. Steering system according to one of claims 1 to 1 1, characterized in that the bearing housing (8) has a cover (42) is associated with a recess (43) through which the steering shaft (3) is passed, wherein the cover (42 ) covers the electronics board (40).

13. Steering system according to claim 12, characterized in that the cover (42) consists of plastic.