Single-wheel steering actuator for a motor vehicle

Abstract

The invention relates to a single-wheel steering actuator (1) for a motor vehicle, comprising a suspension strut (10) that can be fastened to a motor vehicle body, and an actuator (12) that is operatively connected to the suspension strut (10) in a steering torque-transmitting operative connection, wherein the suspension strut (10) has an outer tube (14) and has an inner tube (18) connected to the outer tube (14) via a linear guide (16), wherein a steering torque applied to the outer tube (14) by the actuator (12) via a force transmission element (20) can be transmitted to the inner tube (18) by the linear guide (16).

Description

[0001] R. 415855

[0002] - 1 -

[0003] Description

[0004] title

[0005] Individual wheel steering actuator for a motor vehicle

[0006] The invention relates to a single-wheel steering actuator for a motor vehicle.

[0007] State of the art

[0008] Modern steering systems conventionally consist of a central actuator that turns the left and right wheels approximately equally. In most vehicles on the market, such an actuator is only installed on the front axle, and there is a mechanical connection between the steering wheel and the steered wheels. So-called steer-by-wire systems eliminate this mechanical connection. In these systems, the steering action is performed solely by one or more actuators.

[0009] Individual wheel steering actuators can be categorized as either translational or rotational. Translational actuators, similar to conventional steering systems, act on the wheel carrier via a lever arm around the steering axis, thus converting translational motion into rotational movement. However, these systems require complex mechanical conversion mechanisms that can incur losses due to friction and backlash. Furthermore, they are limited in terms of integration and size.

[0010] Rotary steering linkages offer a more direct transmission of steering torque, as they do not require a change in the type of motion. However, systems of this type also have their problems, particularly if the steering actuator cannot be positioned directly on the steering axis. In such cases, relative movements occur between the steering actuator and the transmission element during suspension compression or steering movements, leading to increased wear, power losses, and more complex design requirements. R. 415855

[0011] - 2 -

[0012] Another problem lies in the complexity and space requirements of conventional independent steering systems. These systems often comprise several mechanical and electronic components that must be installed separately in the vehicle. This additional space requirement not only restricts the design of modern vehicle platforms but also increases the vehicle's weight. This is a significant disadvantage, especially for electric vehicles, whose range is heavily dependent on weight and energy efficiency.

[0013] The object of the present invention is therefore to provide a single-wheel steering actuator which has a reduced installation space, a reduction in complexity and costs, as well as improved load-bearing capacity and service life.

[0014] The problem is solved by a single-wheel steering actuator with the features of claim 1.

[0015] Disclosure of the invention

[0016] According to one aspect, a single-wheel steering actuator for a motor vehicle is proposed, comprising a strut which can be attached to a motor vehicle body and an actuator which is in a steering torque-transmitting operative connection with the strut, wherein the strut has an outer tube and an inner tube connected to the outer tube via a linear guide, wherein a steering torque introduced by the actuator via a force transmission element onto the outer tube can be transmitted to the inner tube via the linear guide.

[0017] The combination of a shock absorber with an actuator that applies steering torque to the outer tube via a force transmission element enables precise and direct transmission of steering forces. The linear guide ensures that rotational forces are efficiently transferred to the inner tube, thereby improving the vehicle's movement accuracy and dynamic stability. R. 415855

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[0019] The proposed design of an individual wheel steering actuator offers a multitude of additional advantages resulting from its specific construction. The combination of a strut with an actuator that transmits the steering torque to the outer tube via a force transmission element leads to significantly improved integration of steering and suspension functions. The direct transmission of the steering torque from the outer tube to the inner tube via a linear guide not only enables precise control of the steering forces but also minimizes mechanical losses from additional connection points. This efficient force transmission ensures a more accurate steering response.

[0020] Furthermore, integrating the steering mechanism into the strut significantly reduces the space required in the vehicle, which is particularly advantageous for modern vehicle platforms with limited installation space. This opens up new possibilities for the design of electric and autonomous vehicles, where optimal use of available space is essential.

[0021] At the same time, combining several functions into a compact assembly reduces weight, which has a positive impact on the vehicle's energy efficiency. The linear guide between the outer and inner tubes plays a key role here, as it not only ensures the precise transmission of rotational forces but also enables the shock absorber's translational movements. The resulting design thus contributes to increased stability, improved steering precision, and an overall more efficient vehicle design.

[0022] In another aspect, it is proposed that the linear guide has a ball guide consisting of several parallel tracks, in particular in a star arrangement, which is designed to transmit translational movements of the inner tube and rotational forces between the outer tube and the inner tube.

[0023] The use of a ball guide consisting of several parallel tracks in a star arrangement increases the load-bearing capacity of the linear guide and distributes the forces evenly across the guide tracks. This ensures R. 415855

[0024] - 4 - high stability and low friction in both rotary and translational movements, which increases the durability and precision of the system.

[0025] Another aspect is proposed: the balls of the ball guide are held in a cage.

[0026] Holding the balls in a cage within the ball guide improves the stability of the movement and prevents the balls from tilting or jamming. This ensures a smooth motion, which increases the efficiency of the system and reduces wear on the contact surfaces.

[0027] In another aspect, it is proposed that the actuator is an electric servomotor which is coupled via a mechanical connection to the force transmission element, in particular an upper spring plate and a lower bearing shell of a strut mount.

[0028] The coupling of an electric servo motor to the outer tube or a power transmission element enables fast and precise control of steering torque. The mechanical connection ensures that the generated forces are transmitted without loss, thus improving the vehicle's steering response.

[0029] In another aspect, it is proposed that the actuator is coupled to a gear unit which has a worm gear coupled to an output shaft of the electric servo motor and a pinion coupled to the power transmission element, which engages with the worm gear.

[0030] The combination of a worm gear and a pinion in the gearbox unit offers a high gear ratio and enables controlled and powerful movement of the outer tube. This design reduces the energy required by the actuator and ensures smooth and precise power transmission, even under high loads. R. 415855

[0031] - 5 -

[0032] In another aspect, it is proposed that the inner tube of the strut is designed as part of a hydraulic telescopic shock absorber, and wherein the outer tube of the strut is connected to the force transmission element by a rigid connection, preferably by screwing, pressing or welding.

[0033] The use of a hydraulic telescopic shock absorber as part of the inner tube and the rigid connection of the outer tube to the power transmission element increase the structural integrity of the system. This ensures precise function of the shock absorber and steering without unwanted movement or deformation.

[0034] In another aspect, it is proposed that the actuator is additionally connected to an electronic control unit that adjusts the steering movement depending on driving situations and sensor data.

[0035] Connecting the actuator to an electronic control unit allows the steering movements to be adapted to different driving situations and sensor data. This leads to dynamic optimization of the vehicle's steering and increases safety through individually tailored steering responses.

[0036] In another aspect, it is proposed that the outer tube has an outer circumferential surface with guide tracks in which the balls can be guided.

[0037] The arrangement of guide tracks on the outer circumferential surface of the outer tube ensures precise guidance of the balls and prevents lateral play. This results in high precision of movement and even distribution of forces, thereby increasing the system's service life. R. 415855

[0038] - 6 -

[0039] In another aspect, it is proposed that the linear guide consists of at least four guide elements that are evenly distributed along the outer surface of the inner tube.

[0040] The linear guide with at least four evenly distributed guide elements improves stability and force transmission between the inner and outer tubes. This even distribution reduces local load peaks and minimizes the risk of deformation or wear on the guide tracks.

[0041] In another aspect, it is proposed that the inner tube has a receiving device at an axial end section, which is designed for mechanical connection with a wheel carrier.

[0042] The mounting device at the axial end section of the inner tube enables a stable and reliable connection with the wheel carrier. This ensures precise transmission of steering torque to the wheel and improves vehicle control and responsiveness, especially under dynamic conditions.

[0043] The described configurations and training programs can be combined in any way desired.

[0044] Further possible embodiments, developments and implementations of the invention also include combinations of features of the invention described previously or subsequently with regard to the exemplary embodiments that are not explicitly mentioned.

[0045] Brief description of the drawings

[0046] The accompanying drawings are intended to provide a further understanding of the embodiments of the invention. They illustrate embodiments and, in conjunction with the description, serve to explain the principles and concepts of the invention. R. 415855

[0047] - 7 -

[0048] Other embodiments and many of the aforementioned advantages become apparent with reference to the drawings. The elements depicted in the drawings are not necessarily shown to scale.

[0049] Fig. 1 shows a schematic representation of an individual wheel steering actuator for a motor vehicle according to a preferred embodiment of the invention;

[0050] Fig. 2 shows a schematic representation of the single-wheel steering actuator for a motor vehicle without an actuator according to the preferred embodiment of the invention;

[0051] Fig. 3 shows a cross-sectional view of a linear guide of the

[0052] Single-wheel steering actuator for a motor vehicle according to the preferred embodiment of the invention; and

[0053] Fig. 4 shows a top view of the single-wheel steering actuator for a

[0054] Motor vehicle according to the preferred embodiment of the invention;

[0055] In the figures of the drawings, identical reference symbols denote identical or functionally equivalent elements, parts or components, unless otherwise stated.

[0056] The single-wheel steering actuator 1 for a motor vehicle shown in Fig. 1 comprises a strut 10, which can be attached to a motor vehicle body, and an actuator 12, which is in a steering torque-transmitting operative connection with the strut 10, wherein the strut 10 has an outer tube 14 and an inner tube 18 connected to the outer tube 14 via a linear guide 16, wherein a steering torque introduced by the actuator 12 via a force transmission element 20 onto the outer tube 14 can be transmitted to the inner tube 18 via the linear guide 16.

[0057] The actuator 12 is an electric servomotor which is mechanically connected to the force transmission element 20, in particular an upper R. 415855

[0058] - 8 -

[0059] The spring plate 27 and a lower bearing shell 25 of a strut mount are coupled. An output shaft of the actuator 12 is non-rotatably connected to the power transmission element 20. An upper bearing shell of the strut mount (not shown) is located in the housing of the gearbox unit 24.

[0060] The actuator 12 is further coupled to a gear unit 24, which has a worm gear coupled to an output shaft of the electric servo motor and a pinion coupled to the power transmission element 20, which engages with the worm gear.

[0061] The actuator 12 is optionally also connected to an electronic control unit 26, which adjusts the steering movement depending on driving situations and sensor data.

[0062] Fig. 2 shows a schematic representation of the single-wheel steering actuator for a motor vehicle without an actuator according to a preferred embodiment of the invention.

[0063] The inner tube 18 has a receiving device 28 at an axial end section, which is designed for mechanical connection with a wheel carrier.

[0064] Fig. 3 shows a cross-sectional view of a linear guide of the single-wheel steering actuator for a motor vehicle according to a preferred embodiment of the invention.

[0065] The inner tube 18 of the strut 10 is designed as part of a hydraulic telescopic shock absorber. Furthermore, the outer tube 14 of the strut 10 is connected to the force transmission element 20 by a rigid connection, preferably by bolting, crimping or welding.

[0066] Fig. 4 shows a top view of the individual wheel steering actuator for a motor vehicle according to a preferred embodiment of the invention. R. 415855

[0067] - 9 -

[0068] The linear guide 16 has a ball guide consisting of several parallel tracks, in particular in a star arrangement, which is designed to transmit translational movements of the inner tube 18 and rotational forces between the outer tube 14 and the inner tube 18. The balls of the ball guide are preferably held in a cage.

[0069] The outer tube 14 has an outer circumferential surface with guide tracks in which the balls can be guided.

[0070] The linear guide 16 comprises at least four guide elements which are evenly distributed along the outer surface of the inner tube 18.

Claims

R. 415855 - 10 - Claims 1. Individual wheel steering actuator (1) for a motor vehicle, comprising: a strut (10) which can be attached to a motor vehicle body; and an actuator (12) which is in a steering torque-transmitting operative connection with the strut (10), wherein the strut (10) has an outer tube (14) and an inner tube (18) connected to the outer tube (14) via a linear guide (16), wherein a steering torque applied to the outer tube (14) by the actuator (12) via a force transmission element (20) can be transmitted to the inner tube (18) via the linear guide (16).

2. Single-wheel steering actuator according to claim 1, wherein the linear guide (16) has a ball guide consisting of several parallel tracks, in particular in a star arrangement, which is designed to transmit translational movements of the inner tube (18) and rotational forces between the outer tube (14) and the inner tube (18).

3. Single wheel steering actuator according to claim 2, wherein balls of the ball guide are held in a cage.

4. Individual wheel steering actuator according to claim 1 or 2, wherein the actuator (12) is an electric servomotor which is coupled via a mechanical connection to the force transmission element (20), in particular an upper spring plate (27) and a lower bearing shell (25) of a strut mount.

5. Single-wheel steering actuator according to claim 4, wherein the actuator (12) is coupled to a gear unit (24) which has a worm gear coupled to an output shaft of the electric servo motor and a pinion coupled to the power transmission element (20) which engages with the worm gear. R. 415855 - 11 - 6. Individual wheel steering actuator according to one of the preceding claims, wherein the inner tube (18) of the strut (10) is designed as part of a hydraulic telescopic shock absorber, and wherein the outer tube (14) of the strut (10) is connected to the force transmission element (20) by a rigid connection, preferably by screwing, crimping or welding.

7. Individual wheel steering actuator according to one of the preceding claims, wherein the actuator (12) is additionally connected to an electronic control unit (26) which adapts the steering movement depending on driving situations and sensor data.

8. Single-wheel steering actuator according to one of the preceding claims, wherein the outer tube (14) has an outer circumferential surface with guide tracks in which the balls can be guided.

9. Single-wheel steering actuator according to one of the preceding claims, wherein the linear guide (16) consists of at least four guide elements which are evenly distributed along the outer surface of the inner tube (18).

10. Single-wheel steering actuator according to one of the preceding claims, wherein the inner tube (18) has a receiving device (28) at an axial end section, which is designed for mechanical connection with a wheel carrier.

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