Single wheel actuator for a motor vehicle steering system

Abstract

The invention relates to an individual wheel actuator (1) for a steering system, in particular a steer-by-wire steering system, of a motor vehicle, comprising: a housing (10) and a drive unit (14) arranged at least partially in a housing interior (12), wherein the drive unit (14) has an electric machine (16) and a conversion gear (18) coupled to the electric machine (16); and a joint (20) coupled to the conversion gear (18) and coupled to a wheel suspension (22), in particular a wheel carrier (24), of the steering system in such a way that a wheel of the steering system can be deflected by a rotational movement of the joint (20). The invention further relates to a wishbone (26) for a wheel suspension (22) of a motor vehicle and to a steering system, in particular a steer-by-wire steering system, for a motor vehicle.

Description

[0001] The invention relates to an individual wheel actuator for a steering system, in particular a steer-by-wire steering system, of a motor vehicle.

[0002] The invention further relates to a wishbone for a wheel suspension of a motor vehicle.

[0003] The invention further relates to a steering system, in particular a steer-by-wire steering system, for a motor vehicle. State of the art

[0004] In conventional steering systems, the desired steering angle is transmitted from the steering wheel to the two front wheels via a mechanical connection. The steering torque is amplified by a servo gear to enable easy steering.

[0005] Future steer-by-wire steering systems will eliminate the mechanical connection between the steering wheel and the steered wheels. The steering angle set on the steering wheel is detected by a sensor and transmitted electronically to the steering actuator, which then adjusts the front wheels accordingly.

[0006] The steering system can act centrally, meaning the steering actuator controls both wheels simultaneously. Typically, the translational movement of a rack is transferred to the tie rods, which pivot the wheels. However, the kinematics limit the maximum steering angle at the front wheels.

[0007] In decentralized steering systems, each steered wheel is assigned its own steering actuator, allowing each wheel to be controlled individually. This allows for an increase in the maximum steering angle. Since the central steering actuator in the center of the vehicle is eliminated, this can result in advantages for the vehicle manufacturer. Decentralized steering systems also enable new functions such as a parking brake function by turning the wheels in opposite directions.

[0008] Furthermore, it is known to transmit the rotation of an electric motor via a worm gear to pivot the steered wheel. Since the electric motor is attached to the chassis, a universal joint must be installed to transmit the rotational movement. This compensates for any vertical movement of the wheel carrier caused by the compression movement.

[0009] DE 102020213664 A1 discloses an electric single-wheel actuator for a motor vehicle with a double-wheel carrier, which consists of an axle carrier and a pivoting carrier, and wherein the pivoting carrier is rotatably mounted within the axle carrier, with an electric motor which pivots the pivoting carrier via a gear, wherein the electric motor is arranged on the axle carrier.

[0010] Wheel suspensions with conventional steering systems, as well as the aforementioned independent wheel actuator, also exhibit a phenomenon called bump steer. The ideal situation would be that the steering angle does not change during vertical compression of a vehicle wheel. However, this cannot normally be prevented.

[0011] It is therefore an object of the invention to provide a compact single-wheel actuator which enables efficient steering torque transmission while simultaneously reducing or compensating for disruptive steering influences such as bump steer.

[0012] This object is achieved by an individual wheel actuator for a steering system, in particular a steer-by-wire steering system, of a motor vehicle having the features of patent claim 1.

[0013] The object is further achieved by a wishbone for a wheel suspension of a motor vehicle having the features of patent claim 11.

[0014] Furthermore, the object is achieved by a steering system, in particular a steer-by-wire steering system, for a motor vehicle having the features of patent claim 12. Disclosure of the invention

[0015] The present invention provides an individual wheel actuator for a steering system, in particular a steer-by-wire steering system, of a motor vehicle.

[0016] The single-wheel actuator comprises a housing and a drive unit arranged at least partially in a housing interior, wherein the drive unit has an electric machine and a conversion gear coupled to the electric machine.

[0017] The individual wheel actuator further comprises a joint coupled to the conversion gear, which is coupled to a wheel suspension, in particular a wheel carrier, of the steering system in such a way that a wheel of the steering system can be deflected by a rotational movement of the joint.

[0018] The present invention further provides a wishbone for a wheel suspension of a motor vehicle, wherein the independent wheel actuator according to the invention is integrated into the wishbone or fastened to it.

[0019] The present invention further provides a steering system, in particular a steer-by-wire steering system, for a motor vehicle, having a plurality of individual wheel actuators according to the invention, which are designed to steer the wheel connected to a respective individual wheel actuator.

[0020] One idea of ​​the present invention is to enable a direct transmission of steering torque to the wheel without the conventional provision of a push rod by connecting the joint to the wheel suspension, in particular the wheel carrier.

[0021] In contrast to a conventional centrally arranged steering system, the center of the vehicle remains free in the present invention.

[0022] The connection of the independent wheel actuator to the wheel suspension thus advantageously exhibits lower elasticity. Furthermore, no bump steer effect occurs within the scope of the present invention. The steering angle is thus decoupled from the spring deflection.

[0023] Advantageous embodiments and further developments emerge from the subclaims and from the description with reference to the figures.

[0024] According to a preferred development, it is provided that the independent wheel actuator can be integrated into a wishbone, in particular a lower wishbone, of the wheel suspension of the steering system or can be fastened to the wishbone of the wheel suspension of the steering system.

[0025] The function according to the invention consists in the fact that the steering actuator is housed in or on a wishbone and executes the steering movement of the wheel via a direct torque transmission. This location for the steering can be directly transferred to the lower wishbone of a double-wishbone axle. This represents a steering actuator that can be used in many vehicles commonly used today.

[0026] According to a further preferred development, the joint coupled to the torque converter is a constant velocity joint, which is designed to rotate the wheel suspension coupled to the joint, in particular the wheel carrier. The use of a constant velocity joint has the advantage of enabling a uniform, jerk-free transmission of steering torque.

[0027] According to a further preferred development, a rotational axis of the joint coupled to the torque converter is arranged substantially perpendicular to the wishbone, in particular the lower wishbone, of the wheel suspension of the steering system. This allows the rotation of the joint and the rotation of the wheel connected to it to be carried out in the same or parallel plane.

[0028] According to a further preferred development, it is provided that the individual wheel actuator is formed in one piece, in particular milled or in two parts, wherein respective parts of the individual wheel actuator are glued or welded.

[0029] Thus, the steering drive, i.e. ECU, electric motor and gearbox, is protected against both dust and splash water.

[0030] According to a further preferred development, the conversion gear is formed by a worm gear, wherein a worm gear of the worm gear is coupled to the joint, wherein a rotational axis of the worm gear and a rotational axis of the joint are arranged concentrically. Thus, an efficient drive of the rotatable joint can be provided.

[0031] According to a further preferred development, a first gear stage of the conversion gear coupled to the electric motor is formed by a harmonic drive, and a second gear stage of the conversion gear coupled to the joint, in particular the constant velocity joint, is formed by a bevel gear. Thus, the rotation axis can advantageously be rotated by 90° and thus approximately in the orientation of the steering axis.

[0032] According to a further preferred development, a first gear stage of the conversion gear, coupled to the electric motor, is formed by a planetary gear, and a second gear stage of the conversion gear, coupled to the joint, in particular the constant velocity joint, is formed by a bevel gear. The use of the planetary gear as the first gear stage offers the advantage of an axially compact design.

[0033] According to a further preferred development, it is provided that the bevel gear has at least one input-side first bevel gear and one output-side second bevel gear, wherein the output-side second bevel gear has a circumferential angle of less than or equal to 270°, in particular a circumferential angle of less than or equal to 180°.

[0034] There are only minor restrictions on the angle range. The remaining requirement is that the rim and wishbone must not touch each other. This allows for a larger steering angle range. Therefore, a complete bevel gear is not required for the output side bevel gear. Instead, a cutout can be used to free up installation space in the rim and thus also avoid collisions with the braking system, for example.

[0035] According to a further preferred development, a first gear stage of the conversion gear, coupled to the electric motor, is formed by a planetary gear, and a second gear stage of the conversion gear, coupled to the joint, in particular the constant velocity joint, is formed by a worm gear. The planetary gear advantageously allows for large gear ratios to be realized.

[0036] The described designs and further training courses can be combined as desired.

[0037] Further possible embodiments, further developments and implementations of the invention also include combinations of features of the invention described previously or below with regard to the exemplary embodiments that are not explicitly mentioned. Short description of the drawings

[0038] The accompanying drawings are intended to provide a further understanding of embodiments of the invention. They illustrate embodiments and, in conjunction with the description, serve to explain principles and concepts of the invention.

[0039] Other embodiments and many of the aforementioned advantages will become apparent upon review of the drawings. The elements illustrated in the drawings are not necessarily drawn to scale.

[0040] They show: Fig. 1 is a plan view of an individual wheel actuator integrated into a wishbone for a steering system according to a preferred embodiment of the invention; Fig. 2 a schematic representation of the Fig. 1, the individual wheel actuator integrated into the wishbone for the steering system according to the preferred embodiment of the invention; and Fig. 3 is a schematic representation of the steering system according to the preferred embodiment of the invention.

[0041] In the figures of the drawings, the same reference symbols designate the same or functionally equivalent elements, parts or components, unless otherwise stated.

[0042] The Fig. 1 comprises a housing 10 and a drive unit 14 arranged at least in sections in a housing interior 12, wherein the drive unit 14 has an electric machine 16 and a conversion gear 18 coupled to the electric machine 16.

[0043] Furthermore, the individual wheel actuator 1 comprises a joint 20 coupled to the conversion gear 18, which is coupled to a wheel suspension 22, in particular a wheel carrier 24, of the steering system in such a way that a wheel of the steering system can be deflected by a rotational movement of the joint 20.

[0044] In the present preferred embodiment, the independent wheel actuator 1 is integrated into a wishbone 26, in particular a lower wishbone 26, of the wheel suspension 22 of the steering system, i.e., the housing of the wishbone 26 also accommodates the independent wheel actuator 1. Alternatively, the independent wheel actuator 1 can be attached, for example, to the wishbone 26 of the wheel suspension 22 of the steering system.

[0045] The joint 20 coupled to the conversion gear 18 is a constant velocity joint which is designed to rotate the wheel suspension 22 coupled to the joint 20, in particular the wheel carrier 24.

[0046] An axis of rotation of the joint 20 coupled to the conversion gear 18 is arranged substantially perpendicular to the wishbone 26, in particular the lower wishbone 26, of the wheel suspension 22 of the steering system.

[0047] The individual wheel actuator 1 is further formed in one piece, in particular milled or in two parts, wherein respective parts of the individual wheel actuator 1 are glued or welded.

[0048] The conversion gear 18 is preferably formed by a worm gear, wherein a worm gear 28 of the worm gear is coupled to the joint 20, wherein an axis of rotation of the worm gear and an axis of rotation of the joint 20 are arranged concentrically.

[0049] Fig. 2 shows a schematic representation of the Fig. 1, integrated into the wishbone 26, for the steering system according to the preferred embodiment of the invention.

[0050] The joint 20, coupled to the conversion gear 18, or its underside, is rotatable with the worm gear. The upper side, or wheel carrier 24, is freely pivotable relative to the underside of the joint 20.

[0051] According to a Fig. 1, it is provided that a first gear stage of the conversion gear 18 coupled to the electric machine 16 is formed by a harmonic gear, and wherein a second gear stage of the conversion gear 18 coupled to the joint 20, in particular the constant velocity joint, is formed by a bevel gear.

[0052] According to a Fig. 1, it is provided that a first gear stage of the conversion gear 18 coupled to the electric machine 16 is formed by a planetary gear, and wherein a second gear stage of the conversion gear 18 coupled to the joint 20, in particular the constant velocity joint, is formed by a bevel gear.

[0053] The bevel gear according to the two alternative embodiments mentioned above has at least one first bevel gear on the input side and one second bevel gear on the output side. The second bevel gear on the output side has a circumferential angle of less than or equal to 270°, in particular a circumferential angle of less than or equal to 180°.

[0054] In this arrangement, the wave gear is connected directly to the electric motor 16. The bevel gear is used as the second gear stage, causing the rotational axis to rotate by 90° and thus approximately in the orientation of the steering axis. A compensating joint 20 or a coupling, for example, can be used after the bevel gear to compensate for the angular changes that occur between the steering axis and the wishbone 26 during suspension compression.

[0055] Wave gears are ideal for very large gear ratios in the range i = 50...150. Thus, the bevel gear can represent a gear ratio or it can be used to rotate the torque flow by 90° (i = 1).

[0056] According to another Fig. 1, it is provided that a first gear stage of the conversion gear 18 coupled to the electric machine 16 is formed by a planetary gear, and wherein a second gear stage of the conversion gear 18 coupled to the joint 20, in particular the constant velocity joint, is formed by a worm gear.

[0057] The dimensioning is primarily determined by the worm gear. A joint 20 or a coupling can also be used after the worm gear to compensate for the angular changes that occur between the wishbone 26 and the steering axle during suspension compression.

[0058] Planetary gears are ideal for large gear ratios. As with the previous designs, a complete gear is not required for the output side of the worm gear.

[0059] Fig. 3 shows a schematic representation of the steering system according to the preferred embodiment of the invention, in particular the integration of the individual wheel actuator 1 into the wheel suspension 22 of the motor vehicle.

[0060] The illustration shows, among other things, a drive shaft 32 of the wheel, sections of a spring strut 34 and a brake disc 30, to which components the individual wheel actuator 1 is coupled via the joint 20. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 102020213664 A1

[0009]

Claims

[1] Individual wheel actuator (1) for a steering system, in particular a steer-by-wire steering system, of a motor vehicle, comprising: a housing (10) and a drive unit (14) arranged at least partially in a housing interior (12), wherein the drive unit (14) has an electric machine (16) and a conversion gear (18) coupled to the electric machine (16); and a joint (20) coupled to the conversion gear (18), which is coupled to a wheel suspension (22), in particular a wheel carrier (24), of the steering system in such a way that a wheel of the steering system can be deflected by a rotational movement of the joint (20). [2] Independent wheel actuator according to claim 1, wherein the independent wheel actuator (1) can be integrated into a wishbone (26), in particular a lower wishbone (26), of the wheel suspension (22) of the steering system or can be fastened to the wishbone (26) of the wheel suspension (22) of the steering system. [3] Independent wheel actuator according to claim 1 or 2, wherein the joint (20) coupled to the conversion gear (18) is a constant velocity joint (20) which is designed to rotate the wheel suspension (22), in particular the wheel carrier (24), coupled to the joint (20). [4] Independent wheel actuator according to one of the preceding claims, wherein an axis of rotation of the joint (20) coupled to the conversion gear (18) is arranged substantially perpendicular to the wishbone (26), in particular the lower wishbone (26), of the wheel suspension (22) of the steering system. [5] Individual wheel adjuster according to one of the preceding claims, wherein the individual wheel adjuster (1) is formed in one piece, in particular milled or two-part, wherein respective parts of the individual wheel adjuster (1) are glued or welded. [6] Single-wheel actuator according to one of the preceding claims, wherein the conversion gear (18) is formed by a worm gear, wherein a worm gear (28) of the worm gear is coupled to the joint (20), wherein an axis of rotation of the worm gear (28) and an axis of rotation of the joint (20) are arranged concentrically. [7] Single wheel actuator according to one of claims 1 to 5, wherein a first gear stage of the conversion gear (18) coupled to the electric machine (16) is formed by a harmonic gear, and wherein a second gear stage of the conversion gear (18) coupled to the joint (20), in particular the constant velocity joint (20), is formed by a bevel gear. [8] Single wheel actuator according to one of claims 1 to 5, wherein a first gear stage of the conversion gear (18) coupled to the electric machine (16) is formed by a planetary gear, and wherein a second gear stage of the conversion gear (18) coupled to the joint (20), in particular the constant velocity joint (20), is formed by a bevel gear. [9] Single-wheel actuator according to claim 7 or 8, wherein the bevel gear has at least one drive-side first bevel gear and one output-side second bevel gear, wherein the output-side second bevel gear has a circumferential angle of less than or equal to 270°, in particular a circumferential angle of less than or equal to 180°. [10] Single-wheel actuator according to one of claims 1 to 5, wherein a first gear stage of the conversion gear (18) coupled to the electric machine (16) is formed by a planetary gear, and wherein a second gear stage of the conversion gear (18) coupled to the joint (20), in particular the constant velocity joint (20), is formed by a worm gear. [11] Wishbone (26) for a wheel suspension (22) of a motor vehicle, wherein an independent wheel actuator (1) according to one of claims 1 to 10 is integrated into the wishbone (26) or fastened thereto. [12] Steering system, in particular steer-by-wire steering system, for a motor vehicle, with a plurality of individual wheel actuators (1) according to one of claims 1 to 10, which are designed to steer the wheel connected to a respective individual wheel actuator (1).

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