STEER-BY-WIRE STEERING APPARATUS AND METHOD FOR OPERATING A STEER-BY-WIRE STEERING APPARATUS

Abstract

The disclosure relates to a steering wheel actuator unit for a steer-by-wire steering apparatus for a motor vehicle and having a steering axle, wherein a free end of the steering axle is designed for arranging a steering wheel and the steering axle is rotatably mounted about its longitudinal axle, the steering wheel actuator unit comprising at least one feedback device which acts on the steering axle to realize a predetermined torque and/or a predetermined damping, and a spindle device connected to the steering axle for providing end stops for the rotational movement of the steering axle. In order to be able to reduce and/or avoid incorrect operation in case of failure of the feedback device, the steering wheel actuator unit further comprising an eddy current device which generates a resistance for the rotation of the steering axle about its longitudinal axle.

Claims

1. A steering wheel actuator unit for a steer-by-wire steering apparatus for a motor vehicle and having a steering axle, wherein a free end of the steering axle is designed for arranging a steering wheel and the steering axle is rotatably mounted about its longitudinal axle, the steering wheel actuator unit comprising at least one feedback device which acts on the steering axle to realize a predetermined torque and/or a predetermined damping, and a spindle device connected to the steering axle for providing end stops for the rotational movement of the steering axle, wherein an eddy current device generates a resistance for the rotational movement of the steering axle about its longitudinal axle.

2. The steering wheel actuator unit according to claim 1, wherein the eddy current device is designed to generate a resistance that is dependent on a rotational speed of the steering axle wherein the eddy current device designed to generate a torque and/or a damping on the steering axle and in case of a rotational movement of the steering axle about its longitudinal axle.

3. The steering wheel actuator unit according to claim 1, wherein the spindle device has the eddy current device.

4. The steering wheel actuator unit according to claim 3, wherein the eddy current device provides a redundancy function in case of failure of the feedback device.

5. The steering wheel actuator unit according to claim 3, wherein the spindle nut has at least one magnet, and wherein the at least one magnet is arranged in a region of an outer circumference of a spindle nut of the spindle device.

6. The steering wheel actuator unit according to claim 12, wherein the eddy current device has an electrical conducting unit, the electrical conducting unit surrounding at least one portion of the spindle device and configured for it to generating eddy currents in the electrical conducting unit wherein the spindle and the spindle nut being arranged within the electrical conducting unit.

7. The steering wheel actuator unit according to claim 6, wherein the electrical conducting unit is designed as an electrically conductive tube, wherein the tube is designed to be slotted in the longitudinal direction, a slot of the tube being open in a switched-off or inactive state of the eddy current device and being closed in a switched-on or active state of the eddy current device.

8. The steering wheel actuator unit according to claim 6, wherein the electrical conducting unit is designed as a coil, wherein the coil is part of a circuit for short-circuiting the coil.

9. A steer-by-wire steering apparatus comprising a steering wheel actuator unit according to claim 1, and a front axle actuator unit, which is assigned to a front axle of a motor vehicle and is designed to steer wheels of the front axle, and a control unit, wherein the control unit is connected to the steering wheel actuator unit and the front axle actuator unit for transmitting electrical signals.

10. A method for operating a steering wheel actuator unit according to claim 1, wherein a resistance for the rotation of the steering axle about its longitudinal axle is generated by the eddy current device.

11. The steering wheel actuator unit according to claim 2, wherein the resistance generated by the eddy current device increases with increasing rotational speed of the steering axle.

12. The steering wheel actuator unit according to claim 3, wherein the spindle device has a spindle connected to the steering axle for common rotation and a spindle nut arranged non-rotatably on the spindle and linearly displaceable in the direction of a longitudinal axle of the spindle.

13. The steering wheel actuator unit according to claim 5, wherein two poles-of the at least one magnet are aligned with one another in the direction of the longitudinal axle of the spindle.

14. The steering wheel actuator unit according to claim 8, wherein a switch is arranged in the circuit, the switch being open in a switched-off or inactive state of the eddy current device and being closed in a switched-on or active state of the eddy current device.

15. The steering wheel actuator unit according to claim 12, wherein the spindle nut is guided in a guide of a housing.

16. The steering wheel actuator unit according to claim 12, wherein the spindle nut has a plurality of magnets and wherein the plurality of magnets is arranged in a region of an outer circumference of the spindle nut of the spindle device, two poles of the plurality of magnets are aligned with one another in the direction of the longitudinal axle of the spindle.

17. The steering wheel actuator unit according to claim 16, wherein the plurality of magnets are fastened to one another in a ring shape about the spindle nut.

18. The steering wheel actuator unit according to claim 17, wherein each magnet of the plurality of magnets are arranged at a uniform distance from one another on the outer circumference of the spindle nut.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0023] The disclosure is explained in more detail below with reference to the drawings. In this case, like reference signs relate to the like, similar, or functionally identical components or elements. In the drawings:

[0024] FIG. 1 is a sectional plan view of a steering wheel actuator unit according to an exemplary arrangement of the disclosure,

[0025] FIG. 2 is a cross section of a spindle nut on a spindle for a steering wheel actuator unit according to the disclosure in accordance with FIG. 1,

[0026] FIG. 3a, 3b are schematic representations of an electrical conducting unit for a steering wheel actuator unit according to the disclosure in accordance with FIG. 1, and

[0027] FIG. 4 is a schematic circuit of a further electrical conducting unit for a further steering wheel actuator unit according to the disclosure.

DETAILED DESCRIPTION

[0028] FIG. 1 shows a sectional plan view of a steering wheel actuator unit 1 according to the disclosure. The steering wheel actuator unit 1 is part of a steer-by-wire steering apparatus 10. The steering wheel actuator unit 1 has a steering axle 2. The steering axle 2 has a free end 3. The free end 3 of the steering axle 2 is designed for arranging a steering wheel (not shown in detail in this case). The steering axle 2 is mounted rotatably about its longitudinal axle 4, in one particular arrangement by the steering wheel. The steering wheel actuator unit 1 also has a feedback device 5. The feedback device 5 acts on the steering axle 2 in order to realize a predetermined torque and/or a predetermined damping. In this exemplary arrangement, the feedback device 5 has a schematically indicated first feedback actuator 6 and a schematically indicated second feedback actuator 7. Because of the two feedback actuators 6, 7, the feedback device 5 is designed to be redundant at the same time.

[0029] The torque or damping acting on the rotation of the steering axle 2 by the feedback device 5 is predetermined or controlled by a control unit 8, which is only indicated schematically in this case. The control unit 8 is also connected to a front axle actuator unit 9, which is only indicated schematically in this case. The front axle actuator unit 9 is assigned to a front axle (not shown in more detail in this case) of a motor vehicle and is designed to steer wheels (not shown in more detail in this case) of the front axle. By operation of the control unit 8, electrical signals are exchanged between the steering wheel actuator unit 1 and the front axle actuator unit 9. The steering wheel actuator unit 1, the control unit 8 and the front axle actuator unit 9 are components of the steer-by-wire steering apparatus 10.

[0030] The steering wheel actuator unit 1 has a spindle device 11. The spindle device 11 is connected to the steering axle 2. In this case, the spindle device 11 provides a first end stop 12 and a second end stop 13 for stopping a rotational movement of the steering axle 2. The spindle device 11 has a spindle 14. The spindle 14 has an external thread 15. The spindle 14 is connected to the steering axle 2 for common rotation. Furthermore, the spindle device 11 has a spindle nut 16. The spindle nut 16 is arranged non-rotatably on the spindle 14 and is linearly displaceable in the direction of a longitudinal axle 17 of the spindle 14. In this case, the longitudinal axle 17 of the spindle 14 and the longitudinal axle 4 of the steering axle 2 coincide. The spindle nut 16 has an internal thread 18 which is designed to correspond in shape to the external thread 15 of the spindle 14 and which engages in a form-fitting manner. To implement the non-rotatable arrangement of the spindle nut 16 on the spindle 14, the spindle nut 16 is guided in this exemplary arrangement in a guide 19 of a housing 20 in the longitudinal direction to the longitudinal axle 17. In this case, the spindle device 11 is arranged within the housing 20.

[0031] In the case of a rotation of the steering axle 2, for example due to actuation of a steering wheel, about the longitudinal axle 4 according to the double arrow 21 in a first direction of rotation or in a second direction of rotation facing away from the first direction of rotation, the spindle 14 connected to the steering axle 2 is also brought into a corresponding rotation about the longitudinal axle 17. As a result, the spindle nut 16 is brought into a linear movement according to the double arrow 22 in the direction of the first end stop 12 or in the direction of the second end stop 13.

[0032] The steering wheel actuator unit 1 also has an eddy current device 23. In this case, the eddy current device 23 is designed as an eddy current brake for the spindle 14. Due to the eddy current device 23, a resistance for or to the rotation of the steering axle 2 about its longitudinal axle 4 can be generated. The eddy current device 23 is assigned to the spindle device 11. To form the eddy current device 23, the spindle nut 16 has a plurality of magnets 24 in this exemplary arrangement. For the sake of clarity, not all magnets 24 are provided with a reference number. The plurality of magnets 24 are arranged on the spindle nut 16 in the region of an outer circumference of the spindle nut. In the case of a linear movement of the spindle nut 16 in the longitudinal direction of the longitudinal axle 17, the magnets 24 also move with it. The magnets 24 are designed as permanent magnets and have two poles 25, 26. In this exemplary arrangement, the first pole 25 is designed as a north pole and the second pole 26 is designed as a south pole. Furthermore, the two poles 25, 26 of the plurality of magnets 24 are each aligned in the direction of the longitudinal axle 17 of the spindle 14. As a result, in this exemplary arrangement, the pole 25 faces the first end stop 12 and the pole 26 faces the second end stop 13. In an alternative exemplary arrangement, the first pole 25 of the magnets 24 can face the second end stop 13 and the second pole 26 can face the first end stop 12.

[0033] Furthermore, the steering wheel actuator unit 1 has an electrical conducting unit 27 for forming the eddy current device 23. In this exemplary arrangement, the electrical conducting unit 27 surrounds a portion of the spindle device 11 which corre-sponds to the portion of the spindle 14 with the external thread 15. In this case, the spindle 14 and the spindle nut 16 are arranged within the electrical conducting unit 27. In this exemplary arrangement, the electrical conducting unit 27 is designed as an electrically conductive tube. In this case, the tube is implemented as a copper tube, for example. Furthermore, in this exemplary arrangement, the electrical conducting unit 27 is assigned to the housing 20.

[0034] Eddy currents can be generated in the electrical conducting unit 27 during a movement of the spindle nut 16 by the magnets 24. These eddy currents in turn generate a further autonomous magnetic field which is directed in the opposite direction to the magnetic field of the magnets 24. As a result, a resistance acting on the rotation of the spindle 14 and thus on the steering axle 2 is generated. This results in a resistance that is dependent on the rotational speed of the steering axle 2 or of the spindle 14. Thus, the resistance generated by the eddy current device 23 increases with increasing rotational speed of the steering axle 2 or the spindle 14. By the eddy current device 23, a torque counteracting the rotation of the steering axle 2 and/or counteracting damping acts on the spindle 14 and via this on the steering axle 2.

[0035] In case of failure of the feedback device 5, the eddy current device 23 provides a redundancy function. In this case, the eddy current device 23 can be configured to be switched on and/or off.

[0036] FIG. 2 shows a cross section of a spindle nut 16 on a spindle 14 for the steering wheel actuator unit 1 according to the disclosure in accordance with FIG. 1. The plurality of magnets 24 can be clearly seen, which are arranged or fastened to one another in a ring shape in the region of the outer circumference of the spindle nut 16 on the spindle nut 16. In one exemplary arrangement, the multiple magnets 24 are arranged at a uniform distance from one another on the outer circumference of the spindle nut 16.

[0037] FIGS. 3a and 3b are schematic representations of an electrical conducting unit 28 as an alternative for the electrical conducting unit 27 for use in a steering wheel actuator unit 1 in accordance with FIG. 1. In this exemplary arrangement, the electrical conducting unit 28 is designed as an electrically conductive tube, this tube being designed to be slotted in the longitudinal direction and thus having a slot 29 in accordance with FIG. 3a.

[0038] In this case, FIG. 3a shows the electrical conducting unit 28 in a switched-off or inactive state of an associated eddy current device 23 in the sense of FIG. 1. In this switched-off or inactive state, the slot 29 is open. As a result, during a movement of the spindle nut 16 with the magnets 24 in the longitudinal direction of the spindle 14 in accordance with FIG. 1, no eddy currents, or only weak eddy currents, are generated in the electrical conducting unit 28. As a result, the eddy current device 23 causes no or a negligibly low resistance to the rotation of the spindle 14 and thus the steering axle 2.

[0039] FIG. 3b shows the electrical conducting unit 28 with a closed slot 29. In contrast to FIG. 3a, this results in a closed ring-shaped cross section of the electrical conducting unit 28. When the slot 29 is closed in accordance with FIG. 3b, the eddy current device 23 is in a switched-on or active state according to FIG. 1.

[0040] The opening and/or closing of the slot 29 can be brought about by an actuating device 30 which is only indicated schematically in this case. In particular, the actuating device 30 is designed in such a way that it closes the slot 29 in case of failure of the feedback device 5 in accordance with FIG. 1.

[0041] FIG. 4 shows a schematic circuit of a further electrical conducting unit 31 as an alternative for the electrical conducting unit 27 or 28 and for a further steering wheel actuator unit according to the disclosure. In this exemplary arrangement, the electrical conductor unit 31 is designed as a coil. This electrical conducting unit 31, designed as a coil, is part of a circuit 32 for short-circuiting the coil. Furthermore, in this exemplary arrangement, a switch 33 is arranged in the circuit 32. In this case, the switch 33 is shown closed. When the switch 33 is closed, a correspondingly designed eddy current device is in a switched-on or active state. When the switch 33 is open, the corresponding eddy current device is in a switched-off or inactive state.

[0042] In case of a steering wheel actuator unit 1 in accordance with FIG. 1, the coil 31 can be provided instead of the electrical conducting unit 27 designed as a tube.