STEER-BY-WIRE STEERING SYSTEM FOR A MOTOR VEHICLE

Abstract

A steer-by-wire steering system for a motor vehicle, comprising: a steering rack for transmitting a steering movement to wheels of the motor vehicle, a steering motor for driving a steering movement, a steering gear having a steering angle pinion for transmitting the steering movement of the steering motor to the steering rack, a gear wheel coupled to the steering angle pinion for determining an initial position of the steering rack when the motor vehicle is started. The gear wheel is configured relative to the steering angle pinion and arranged inside the steer-by-wire steering system in such a way that the gear wheel covers a complete steering range of the steering rack when the steering rack is moved over the steering angle pinion.

Claims

1. A steer-by-wire steering system for a motor vehicle, the system comprising: a steering rack to transmit a steering movement to wheels of the motor vehicle; a steering motor to control a steering movement, a steering gear with a steering angle pinion to transmit the steering movement of the steering motor to the steering rack; and a gear wheel coupled to the steering angle pinion to determine an initial position of the steering rack at a starting process of the motor vehicle, wherein the gear wheel is configured relative to the steering angle pinion and arranged inside the steer-by-wire steering system such that the gear wheel covers a complete steering range of the steering rack when the steering rack is moved via the steering angle pinion.

2. The steer-by-wire steering system according to claim 1, further comprising an angle sensor for sensing a rotation angle of the gear wheel, wherein the angle sensor is designed such that data acquisition is adapted to be performed in ASIL D quality.

3. The steer-by-wire steering system according to claim 2, wherein the angle sensor is a magnetic sensor, wherein a magnet is arranged on the gear wheel for the purpose of sensing a rotation angle, wherein the magnet is arranged between the angle sensor and the gear wheel.

4. The steer-by-wire steering system according to claim 1, wherein a cover is provided to accommodate the gear wheel and/or the angle sensor, wherein the gear wheel is arranged between a top of the cover and the angle sensor.

5. The steer-by-wire steering system according to claim 1, wherein a transmission ratio is present between the steering angle pinion and the gear wheel that is designed such that a complete steering range of the steering rack is executable by a rotation of the gear wheel about its rotational axis with a rotation angle of <360, or with a rotation angle of <340.

6. The steer-by-wire steering system according to claim 1, wherein a motor position sensor is provided for determining a current position of a steering rack after a starting process of the motor vehicle on the basis of the initial position of the steering rack, and wherein the motor position sensor is a magnetic sensor.

7. The steer-by-wire steering system according to claim 1, wherein the gear wheel and/or the angle sensor are movable toward the steering angle pinion or are movable by at least 3 mm toward the steering angle pinion.

8. The steer-by-wire steering system according to claim 1, wherein the gear wheel is eccentrically mounted on a shaft.

9. The steer-by-wire steering system according to claim 1, wherein a spring element for preadjusting a radial play between the gear wheel and the steering angle pinion is provided, and wherein the spring element is permanently arranged on a housing of the steering gear.

10. A method for determining a position of a steering rack of a steer-by-wire steering system of a motor vehicle, preferably of a steer-by-wire steering system according to claim 1, the method comprising: driving a steering angle pinion for moving a steering rack between a first steering stop and an opposite, second steering stop and, substantially simultaneously, a gear wheel for determining an initial position of the steering rack; moving the steering rack between the first steering stop and the second, opposite, steering stop via the steering angle pinion; moving the gear wheel about a rotational axis with a rotation angle of <360; and determining an initial position of the steering rack through the rotation angle of the gear wheel about the rotational axis.

11. A motor vehicle comprising the steer-by-wire steering system according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein:

[0024] FIG. 1 shows a steer-by-wire steering system according to the invention for a motor vehicle according to an example in a sectional view,

[0025] FIG. 2 shows a part of the steer-by-wire steering system according to the invention for a motor vehicle according to the example in a sectional view,

[0026] FIG. 3 shows a first (top) and second (bottom) partial sectional view of the steer-by-wire steering system according to the invention according to the example,

[0027] FIG. 4 shows a first (top) and second (bottom) partial sectional view of the steer-by-wire steering system according to the invention according to an example,

[0028] FIG. 5 shows a first (top) and second (bottom) partial sectional view of the steer-by-wire steering system according to the invention according to an example,

[0029] FIG. 6 shows the individual steps of a method according to the invention for determining the position of a steering rack of a steer-by-wire steering system of a motor vehicle.

DETAILED DESCRIPTION

[0030] FIG. 1 shows a steer-by-wire steering system 2 according to the invention for a motor vehicle according to a first example in a sectional view.

[0031] As can be seen according to FIG. 1, the steer-by-wire steering system 2 according to the invention comprises a steering rack 4 for transmitting a steering movement to wheels of the motor vehicle, a steering motor 6 for controlling a steering movement, a steering gear 12 with a steering angle pinion 14 for transmitting the steering movement of the steering motor 6 to the steering rack 4, a gear wheel 8 coupled to the steering angle pinion 14 for determining an initial position of the steering rack 4 at a starting process of the motor vehicle, wherein the gear wheel 8 is configured relative to the steering angle pinion 14 and arranged inside the steer-by-wire steering system 2 in such a manner that the gear wheel 8 covers a complete steering range of the steering rack 4 when the steering rack 4 is moved by means of the steering angle pinion 14.

[0032] FIG. 2 shows the part of the steer-by-wire steering system 2 according to the invention located in the dashed box in FIG. 1 in a somewhat enlarged representation.

[0033] As can be seen according to FIG. 2, the steering angle pinion 14 is driven by means of the worm drive 22 that is driven by the steering motor 6.

[0034] FIG. 3 shows a first (top) and second (bottom) partial sectional view of the part of the steer-by-wire steering system 2 according to the invention located in the dashed box in FIG. 2 according to the first example, wherein the bottom representation shows a partial sectional view of the top representation along the section line A-A.

[0035] As can be seen according to FIG. 3, the steer-by-wire steering system 2 additionally comprises an angle sensor 10 for sensing a rotation angle of the gear wheel 8 coupled to the steering angle pinion 14, wherein the angle sensor 10 in the present case is designed for data acquisition in ASIL D quality. The gear wheel 8 is rotatably mounted on the shaft 20 by means of the bearing 26 in this case.

[0036] The angle sensor 10 is designed in the form of a magnetic sensor in this case, wherein a magnet 18 is arranged on the gear wheel 8 for sensing a rotation angle between the angle sensor 10 and the gear wheel 8.

[0037] Furthermore, a cover 16 is provided to accommodate the gear wheel 8 and the angle sensor 10, wherein the gear wheel 8 in the present case is arranged between a top 16a of the cover 16 and the angle sensor 10.

[0038] The transmission ratio between the steering angle pinion 14 and the gear wheel 8 is designed in the present case such that a complete steering range of the steering rack 4 is executable by means of a rotation of the gear wheel 8 about its rotational axis X with a rotation angle of <360, preferably with a rotation angle of <340.

[0039] The gear wheel 8 and/or the angle sensor 10 are movable toward the steering angle pinion 14 in this case, preferably by at least 3 mm, in order to adjust a zero-play coupling between the gear wheel 8 and the steering angle pinion 14.

[0040] FIG. 4 shows a first (top) and second (bottom) partial sectional view of the part of the steer-by-wire steering system 2 according to the invention located in the dashed box in FIG. 2 according to a second example, wherein the bottom representation shows a partial sectional view of the top representation along the section line A-A.

[0041] As can be seen according to FIG. 4, according to the second example the angle sensor 10 is arranged between the top 16a of the cover 16 and the gear wheel 8, wherein the gear wheel 8 in the present case is mounted eccentrically on the shaft 20 and in this way ensures or creates a zero-play coupling with the steering angle pinion 14. In addition, the steering angle pinion 14 is also provided with a magnet 18.

[0042] FIG. 5 shows a first (top) and second (bottom) partial sectional view of the part of the steer-by-wire steering system 2 according to the invention located in the dashed box in FIG. 2 according to a third example, wherein the bottom representation shows a partial sectional view of the top representation along the section line A-A.

[0043] As can be seen according to FIG. 5, the third example additionally has a spring element 24 for preadjusting a radial play between the gear wheel 8 and the steering angle pinion 14, which in the present case is permanently arranged on the housing of the steering gear 12.

[0044] Finally, FIG. 6 shows the individual steps of a method according to the invention for determining the position of a steering rack 4 of a steer-by-wire steering system 2 of a motor vehicle.

[0045] As can be seen according to FIG. 6, the method according to the invention comprises the steps of: a driving 100 of a steering angle pinion 14 for moving a steering rack 4 between a first steering stop and an opposite, second steering stop and, simultaneously, a gear wheel 8 for determining an initial position of the steering rack 4; a moving 200 of the steering rack 4 between the first steering stop and the second, opposite, steering stop by means of the steering angle pinion 14; a moving 300 of the gear wheel 8 about a rotational axis X with a rotation angle of <360; as well as a determining 400 of an initial position of the steering rack 4 through the rotation angle of the gear wheel 8 about the rotational axis X.

[0046] The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.