Force feedback actuator of a steering column

Abstract

Force feedback actuator of a steering column of a vehicle with a magnetorheological braking device (1), wherein the magnetorheological braking device (1) has a shaft (2) arranged along an axis of rotation (L) and a rotating element (7) connected to the shaft, a stationary element (9) and at least one housing element (3) arranged around the shaft (2), wherein a magnetorheological medium is provided in a receiving space (5) formed between the shaft (2) and the housing element (3), wherein the receiving space (5) is sealed by means of a sealing device (6) between the housing element (3) and the shaft (2), and wherein a friction element (11, 12) is provided between the housing element (3), which is operatively connected to the shaft (2) in such a way that a braking torque is exerted on the shaft (2).

Description

Field of the invention

[0001] The present invention relates to a force feedback actuator of a steering column of a vehicle and a steer-by-wire steering system with such a force feedback actuator. Background of the invention

[0002] In today's steering systems and steering devices, the steering wheel can be adjusted in height and length, i.e., in an axial position. In such adjustment systems, the steering column elements or steering shaft elements are movable relative to each other, for example, designed as a telescopic arrangement. This allows the steering wheel to be adjusted to a position that suits the driver.

[0003] Steer-by-wire steering systems are also known, which dispense with the mechanical connection between the steering wheel and the axle to be steered via the steering column, and the steering of the wheels is controlled via corresponding signals. Two types of steer-by-wire steering systems can be distinguished: steer-by-wire steering systems with a force feedback actuator remote from the steering wheel and steer-by-wire steering systems with a force feedback actuator close to the steering wheel.

[0004] Steer-by-wire steering systems with a force-feedback actuator located away from the steering wheel utilize common crash elements, such as metal strips that plastically deform when a defined force is exceeded. Plastic sleeves on the telescopic steering shaft are also known, which are destroyed by a predetermined force. Steer-by-wire steering systems with a force-feedback actuator located close to the steering wheel can eliminate the need for a telescopic steering shaft.

[0005] Furthermore, with such steering column adjustment systems, the steering column housing sections must be able to move relative to each other. This is achieved by a telescopic arrangement of the housing sections. This allows the steering wheel to be adjusted to a position that suits the driver.

[0006] Furthermore, such adjustment systems must be equipped with braking devices that enable targeted deceleration, even to the point of locking. Magnetorheological braking devices, among others, can be used for this purpose.

[0007] From WO 2022 / 170 050 A1, a force feedback actuator is known in which the generation of a restoring torque is made possible by means of a control strategy of the motor and the brake.

[0008] DE 10 2018 222 235 A1 discloses a rotation control device for steering a vehicle, comprising a user interface surface that can rotate about a rotation axis of the device. The device includes a sensor unit for monitoring the orientation and / or rotational movement of the user interface surface, a processing unit, and a communication interface for transmitting control signals based on sensor data. Furthermore, the device includes a magnetorheological actuator that is mechanically connected to the user interface surface and whose rotational movement is influenced by a magnetic field. The actuator can generate and / or influence the magnetic field according to command signals from the processing unit.

[0009] DE 10 2013 002 958 A1 discloses a device for unlocking or locking a steering column, comprising an electric motorless actuator system. This actuator system causes a movement or change in size of a component and uses a shape memory alloy to unlock the steering column, with a spring force acting as a counterforce. The steering column is held in a housing for longitudinal movement, and the device is characterized by a simple design that enables automatic unlocking and manual position adjustment.

[0010] DE 10 2017 114 517 A1 discloses a steering column for a motor vehicle, comprising a steering spindle surrounded by a steering column tube and connected to a steering wheel. The steering spindle is slidably guided in a guide clamp, wherein the guide clamp is pivotally mounted about a pivot axis in a holding part that is connectable to a chassis of the motor vehicle. A locking device is arranged between the steering column tube and the holding part, comprising a threaded rod and a spindle nut. The spindle nut is mounted in a rolling bearing whose rolling elements are at least partially surrounded by a magnetorheological fluid, and the locking device contains an electromagnet. Summary of the invention

[0011] It is therefore an object of the present invention to provide a force feedback actuator with improved steering feel feedback.

[0012] According to the invention, this object is achieved by a force feedback actuator of a steering column of a vehicle with a magnetorheological braking device, wherein the magnetorheological braking device has a shaft arranged along a rotational axis and a rotating element connected to the shaft, a stationary element and at least one housing element arranged around the shaft, wherein a magnetorheological medium is provided in a receiving space formed between the shaft and the housing element, wherein the receiving space is sealed by means of a sealing device between the housing element and the shaft, wherein a friction element is provided which is operatively connected to the shaft in such a way that a braking torque is exerted on the shaft.

[0013] The inventive design serves to provide the driver with improved steering feel by means of the force feedback actuator. Depending on the design, the friction element results in constant or varying friction between components connected to the shaft. To this end, the friction element acts as a brake on the shaft, thus generating a perceptible torque on a control element connected to the force feedback actuator, such as the steering wheel.

[0014] According to the invention, the friction element is arranged between the rotating element and the stationary element and / or the housing element. Advantageously, the friction element is positioned at a location where the distance between the components is smallest in order to generate the most sufficient friction force possible.

[0015] According to the invention, the rotating element is designed as a rotor and the stationary element as a stator.

[0016] Additionally, additional friction elements such as friction rings or similar components can be provided. In addition to a disc spring, the friction element or the friction effect can be created by a rubber ring, an additional seal, or even an existing seal. Advantageously, a material with predictable wear, such as plastic (PA66), is used to ensure a consistent friction torque and thus steering feel throughout the service life of the steering system. Furthermore, the friction element can be designed as a self-adjusting friction element.

[0017] According to the invention, the friction element is designed as a permanent magnet. Indirect friction is generated by arranging the permanent magnet outside the magnetorheological braking device. This can be, for example, on the housing element or stator to generate a base friction torque between the rotor, powder, and stator.

[0018] Preferably, the permanent magnet has an adjustable magnetic effect. This can be achieved, for example, by an adjustable distance between the housing / stator and the permanent magnet. A screw, for example, can be used for adjustment.

[0019] Furthermore, in the event of a power failure, the permanent magnet can contact the housing / stator. Consequently, the permanent magnet's magnetic flux generates an increased friction torque between the magnetorheological braking device, rotor, and stator. Thus, the permanent magnet generates an adjustable base friction and simultaneously serves as a fallback mechanism in the event of a malfunction.

[0020] According to one embodiment of the invention, the magnetorheological medium comprises magnetorheological particles and / or gas and / or liquid as filling medium.

[0021] Further aspects of the invention relate to an adjustment unit and a steer-by-wire steering system using a force feedback actuator according to the invention. Short description of the drawing

[0022] Two exemplary embodiments of the invention are illustrated below with reference to two figures. They show: Fig. 1 a longitudinal section of a magnetorheological braking device of a force feedback actuator according to the invention according to a first embodiment, and Fig. 2 a longitudinal section of a magnetorheological braking device of a force feedback actuator according to the invention according to a second embodiment. Detailed description of the drawings

[0023] Fig. 1 shows a longitudinal section of a force feedback actuator according to the invention (not shown in detail) with a magnetorheological braking device 1 according to a first embodiment.

[0024] The magnetorheological braking device 1 has a shaft 2 arranged along a rotational axis L and at least one housing element 3 rotatable about the shaft. This housing element 3 is mounted relative to the shaft by means of at least one bearing arrangement 4. The housing element 3 can be designed as a type of cover, sleeve, or in another form. Between the shaft 2 and the housing element 3, a receiving space 5 is formed, which provides a magnetorheological medium. The magnetorheological medium can be provided as magnetorheological particles and / or gas and / or liquid as a filling medium. The receiving space 5 is sealed by means of a sealing device 6 between the housing element 3 and the shaft 2.

[0025] Connected to the shaft 2 is a rotating element 7, designed as a rotor 8, and a stationary element 9, designed as a stator 10. As can be seen from the exemplary embodiment, two different types of friction elements 11, 12 are provided here. The friction element 11, 12 itself is operatively connected to the shaft 2 in such a way that a braking torque is exerted on the shaft 2.

[0026] The friction element 11 is designed as a permanent magnet 13. The permanent magnet 13 is arranged in the area of ​​the sealing device 6 or is formed as part of it. This generates indirect friction.

[0027] The other friction element 12 is designed as a combination of a disc spring 14 and a friction ring 15. The friction element 12 is positioned between the housing element 3 and the rotor 8 at a point that provides the smallest distance between these two components. Furthermore, the housing element 3 has a recess 16 in which the disc spring 14 is arranged. The disc spring 14 is mounted on the friction ring 15, which is connected to the rotor 8.

[0028] The Fig. Figure 2 shows a second embodiment of the invention. To simplify the description, identical components are designated by the same reference numerals. The following description therefore focuses on the differences.

[0029] The difference to Fig.1 lies in the positioning and design of the friction element 12. As can be seen, a combination of a disc spring 14 and two friction rings 17, 18 is also provided. The friction element 12 is positioned between the housing element 3 and the rotor 8 at a location that provides a greater distance between these two components. Furthermore, the disc spring 14 is arranged between the two friction rings 17, 18. The friction ring 17 bears against the housing element 3, and the friction ring 18 bears against the rotor 8. List of reference symbols 1 magnetorheological braking device 2nd wave 3 Housing element 4 Bearing arrangement 5 Recording room 6 Sealing device 7 Rotating element 8 Rotor 9 Fixed element 10 Stator 11 Friction element 12 Friction element 13 Permanent magnet 14 disc spring 15 Friction ring 16 Recess 17 Friction ring 18 Friction ring L axis of rotation

Claims

[1] Force feedback actuator of a steering column of a vehicle with a magnetorheological braking device (1), wherein the magnetorheological braking device (1) has a shaft (2) arranged along a rotational axis (L) and a rotating element (7) connected to the shaft, a stationary element (9) and at least one housing element (3) arranged around the shaft (2), wherein a magnetorheological medium is provided in a receiving space (5) formed between the shaft (2) and the housing element (3), wherein the receiving space (5) is sealed by means of a sealing device (6) between the housing element (3) and the shaft (2), wherein a friction element (11, 12) is provided which is operatively connected to the shaft (2) in such a way that a braking torque is exerted on the shaft (2), wherein the friction element (11, 12) is arranged between the rotating element (7) and the stationary element (9) and / or the housing element (3),wherein the rotating element (7) is designed as a rotor (8) and the fixed element (9) is designed as a stator (10), , characterized by that the friction element (11) is designed as a permanent magnet (13). [2] Force feedback actuator according to claim 1, wherein the permanent magnet (13) has an adjustable magnetic effect. [3] Force feedback actuator according to one of the preceding claims, wherein the magnetorheological medium comprises magnetorheological particles and / or gas and / or liquid as filling medium. [4] Adjustment unit of a steering column of a vehicle comprising a force feedback actuator according to one of the preceding claims. [5] Steer-by-wire steering system comprising a force feedback actuator or an adjustment unit according to one of the preceding claims.

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