Steering column for a motor vehicle

Abstract

The invention relates to a steering column (1) for a motor vehicle, comprising a steering shaft (4) rotatably mounted in a steering column housing (3) about a longitudinal axis (L) extending in a longitudinal direction, a rotation limiter (5) for limiting a rotation of the steering shaft (4), and a feedback actuator (6) for coupling a feedback torque into the steering shaft (4), the feedback actuator comprises an actuator housing (61) and an actuator shaft (62) which can be driven to rotate relative to the actuator housing by a motor. In order to achieve an optimized design and improved production and assembly, the invention proposes that the feedback actuator (6) and the steering column (1) have a releasable connection.

Description

Technical Field

[0001] The present invention relates to a steering column for a motor vehicle, comprising: a steering shaft rotatably supported in a steering column housing about a longitudinal axis extending in a longitudinal direction; a rotation limiter for limiting rotation of the steering shaft; and a feedback actuator for coupling a feedback torque into the steering shaft, the feedback actuator including an actuator housing and an actuator shaft rotatable by a motor relative to the actuator housing. Background Technology

[0002] To steer a motor vehicle, a manual steering command can be input by turning a steering wheel mounted on the driver's side at the rear end along the direction of travel. This steering command is translated into the steering angle of the vehicle's steerable wheels. The steering shaft is rotatably supported in a steering column housing, also known as a housing unit or guide box. The steering column housing is typically held by a support unit that can be connected to the vehicle body and is adjustable relative to this support unit.

[0003] In conventional steering systems, the steering shaft is mechanically connected to the wheels via a steering transmission. In steer-by-wire systems, the rotation of the steering shaft is detected by a rotation sensor (which includes an angle sensor and / or a torque sensor) and converted into an electrical control signal for controlling the electric steering actuator. Because of the lack of mechanical coupling with the wheels, the rotation of the steering shaft is not limited by mechanical end stops of the wheels when the maximum steering angle is reached. However, to avoid overly abrupt steering and to simulate a realistic steering feel, it is known that the maximum possible steering angle of the steering wheel is limited by a rotation limiter, which constitutes a limiting device with end stops for limiting the maximum possible rotation of the steering shaft.

[0004] Another effect of the lack of mechanical coupling is that the driver does not receive any direct mechanical feedback from the steering wheels through the steering line. In a mechanically coupled steering system, this feedback, as a reaction torque or return torque related to road characteristics, vehicle speed, current steering angle, and other operating conditions, is transmitted to the steering wheel via the steering transmission and its mechanically associated steering shaft. This lack of tactile feedback makes it difficult for the driver to reliably perceive the current driving conditions and perform appropriate steering maneuvers, thereby impairing the vehicle's steerability and, consequently, driving safety.

[0005] To generate a realistic driving feel, it is known in the prior art to detect parameters such as vehicle speed, steering angle, and steering reaction torque from actual instantaneous driving conditions, or to calculate these parameters in a simulation, and to form a feedback signal based on these parameters, which is then fed into a feedback actuator. This feedback actuator has an electrical control unit and an electric motor connected thereto, which drives an actuator shaft connected to the steering shaft. During driving, the motor is controlled to couple a feedback torque corresponding to the actual reaction torque into the steering wheel via the steering shaft. This "force feedback" system gives the driver the impression of a realistic driving situation, similar to that in conventional steering, making intuitive reactions easier. The feedback actuator can also be alternatively called a handwheel actuator (HWA) or hand force adjuster.

[0006] A steering column equipped with a rotation limiter and a feedback actuator is known from WO 2022 / 175278 A1 or EP 3 620 350 A1. Such a steering column can theoretically solve the aforementioned problems. However, a disadvantage is the relatively costly construction and assembly, especially considering the testing and calibration procedures required during manufacturing (e.g., to operate the feedback actuator, which becomes difficult with the rotation limiter).

[0007] In view of the above problems, the object of the present invention is to provide an optimized structure and improved manufacturing and assembly. Summary of the Invention

[0008] According to the invention, this task is accomplished by a steering system having the features of claim 1. Advantageous improvements are derived from the dependent claims.

[0009] A steering column for a motor vehicle includes: a steering shaft rotatably supported in a steering column housing about a longitudinal axis extending in a longitudinal direction; a rotation limiter for limiting the rotation of the steering shaft; and a feedback actuator for coupling a feedback torque into the steering shaft, the feedback actuator including an actuator housing and an actuator shaft rotatable by a motor relative to the actuator housing, wherein, according to the invention, the feedback actuator and the steering column have a releasable connection.

[0010] By definition, the longitudinal direction runs axially. The actuator shaft, also synonymously called the drive shaft, extends coaxially, or at least substantially coaxially, relative to the longitudinal axis. In other words, the steering shaft and the actuator shaft are arranged aligned. The feedback actuator has an electric motor, which can drive the actuator shaft (preferably via a transmission) to rotate about the longitudinal axis.

[0011] According to the invention, at least one mechanical interface is constructed between the steering column and the feedback actuator, the mechanical interface having a separable connection. The separable connection is arranged between the rotation limiter and the feedback actuator.

[0012] The releasable connection can be created and disengaged. Thus, for example, it is possible to mount the feedback actuator as a whole onto the steering column and then disassemble it again as needed, or it is possible to couple and decouple at least individual functional components of the steering shaft and the feedback actuator according to their function.

[0013] Preferably, the decoupling or loosening of the connection can be achieved through spatial separation.

[0014] The releasable connection simplifies the manufacturing and assembly of the steering column. Furthermore, different types of feedback actuators and steering column housings can be combined with minimal overhead.

[0015] Advantageously, the actuator housing can be connected to the steering column housing. Both the actuator housing and the steering column housing can have connecting elements that create a preferably releasable connection. This allows for the assembly and disassembly of the feedback actuator onto the steering column. Another advantage is that, during steering column manufacturing, the actuator housing or steering column housing can be temporarily connected to manufacturing and / or testing equipment via releasable connecting elements, for example, during testing phases for detecting operating parameters or for coupling input test loads, starting torque, etc. Alternatively or additionally, non-releasable connecting elements can be provided.

[0016] In the aforementioned embodiments, an axial connection may be provided between the actuator housing and the steering column housing. This axial connection is characterized in that the actuator housing and the steering column housing can be joined together in the axial direction, i.e., in the longitudinal direction, preferably in linear axial relative movement. The axial connection may, for example, have form-fitting elements that can fit together in the axial direction to generate a form fit that acts in the longitudinal direction and / or in the circumferential direction with respect to rotation about the longitudinal axis. For example, corresponding flange elements may be provided, mounted on opposite ends of the steering column housing and the actuator housing, and may be axially tensioned together. The connection may be designed to be releasable, for example by means of bolts or the like, or alternatively or additionally, the connection may include non-releasable fasteners, such as riveted connections, adhesive connections, welded connections, etc.

[0017] Preferably, an axially connected coupling can be arranged between the steering shaft and the actuator shaft. This coupling is used to transmit the torque of the feedback torque to the steering shaft. The coupling constitutes a releasable connection and is correspondingly constructed as a separable coupling, meaning it can be engaged and disengaged. Preferably, the coupling includes coupling components respectively anti-rotationally mounted on the steering shaft and the actuator shaft, these coupling components being axially connected to create a torque-fitted connection. This means that the coupling can be brought into engagement by axial, preferably purely axial, relative movement between the steering shaft and the actuator shaft. This configuration of the coupling can also be synonymously referred to as an axial coupling. This coupling has the advantage of simple assembly.

[0018] Preferably, the aforementioned axial connection between the actuator housing and the steering column housing, and the axially connected coupling, can be arranged and combined such that by mounting the actuator housing onto the steering column housing, the coupling is automatically brought into engagement. For assembling the feedback actuator, only the actuator housing needs to be axially connected and secured to the steering column; no additional securing of the coupling is required. This advantageously reduces manufacturing and assembly costs. Another advantage is that the steering column housing and actuator housing can be constructed in a closed manner and sealed to each other, allowing the steering shaft and actuator shaft to be installed together with the coupling in a way that optimally protects them from external influences.

[0019] The aforementioned embodiment can be advantageously achieved by constructing the coupling as a form-fitting connector capable of axial engagement. The form-fitting connector has form-fitting elements that can be brought into form-fitting engagement through preferred linear relative movement in the longitudinal direction. The resulting form-fitting action with respect to rotation about the longitudinal axis in the circumferential direction enables torque transmission between the steering shaft and the actuator shaft. For example, the form-fitting connector can be designed as a claw connector with circumferentially offset connector protrusions extending axially from the end sides of the connector components. These connector protrusions can be brought into a mutually engaged state through simple axial insertion, thereby forming a form-fitting action for rotation. This embodiment can be provided with minimal cost and reliable function.

[0020] Preferably, the coupling can be configured as a two-piece assembly. In this two-piece assembly, exactly two coupling components, i.e., two coupling halves, are provided. One coupling half is anti-rotationally connected to the steering shaft, and the other coupling half is anti-rotationally connected to the actuator shaft. These two coupling halves are arranged on the axially opposite end faces of the steering shaft and the actuator shaft. Thus, these two coupling halves can be easily brought into coupling engagement through axial engagement during the installation of the feedback actuator.

[0021] Advantageously, the coupling can be connected without tools. This allows for a torque-fitted coupling engagement without the use of external tools or other aids. Accordingly, the steering shaft and actuator shaft can be connected to each other without tools, for example, by simply axially inserting the two coupling halves. Preferably, the coupling can also be disassembled without tools. Therefore, the steering shaft and actuator shaft can be easily and tool-free connected and disconnected, allowing the feedback actuator to be easily assembled and equally easily disassembled from the steering column housing.

[0022] An advantageous improvement could be that the coupling incorporates damping elements. One or more damping elements can be provided, arranged between the torque-transmitting coupling components. These damping elements can be designed to buffer the relative rotational and / or axial motion between the steering shaft and the actuator shaft. This advantageously reduces the transmission of vibrations or torque peaks. The damping elements can, for example, be elastomeric or rubber elements, which can be arranged between, for example, the torque-transmitting form-fitting elements of a claw coupling.

[0023] It is possible that the coupling incorporates spring elements. One or more spring elements can be provided, arranged between the steering shaft and the actuator shaft, depending on whether they act axially and / or circumferentially. Elastomer elements, rubber elements, and / or metal springs, such as coil springs, leaf springs, etc., can be used as spring elements between the torque-transmitting coupling components. This allows the torque peak at startup of the feedback actuator to be reduced relative to the steering shaft, resulting in a tactilely comfortable feedback. It is also possible that spring elements and damping elements are functionally combined.

[0024] The coupling can be configured to compensate for misalignment. Therefore, radial and / or angular misalignment that may occur between the steering shaft and actuator shaft due to tolerances can be compensated for by the coupling. Consequently, the acceptable tolerance range can be increased, which reduces manufacturing and assembly costs and improves operational safety.

[0025] Preferably, the rotation limiter can be integrated into the steering column housing. The rotation limiter is configured to limit the maximum possible angle of rotation of the steering shaft relative to the steering column housing. Different configurations are known for this. For example, stops that can contact each other in the circumferential direction can be provided on the steering shaft and in the steering column housing, said stops being a coilable belt element or the like installed between the steering shaft and the steering column housing. Integrating the rotation limiter into the steering column housing allows for a compact configuration.

[0026] The rotation limiter can be configured to be axially mounted on the steering shaft, for example, from the end of the steering shaft (on which a coupling according to the invention is arranged). In this way, the rotation limiter can be mounted through an axial opening in the steering column housing, and then the feedback actuator can be axially mounted on the steering column housing.

[0027] The feedback actuator can be configured to have a speed reduction transmission. This speed reduction transmission is located between the motor shaft and the actuator shaft, which rotates more slowly relative to the motor shaft, and can include a belt drive, a worm gear drive, or other suitable transmission configuration.

[0028] It is possible that the coupling is structurally integrated with the rotation limiter and the feedback actuator. The rotation limiter may, for example, have a stop element on a shaft component or hub component connected to the steering shaft. The feedback actuator may, for example, have a drive wheel connected to the actuator shaft. Because such shaft components or hub components, drive wheels, or other functional elements of the rotation limiter or feedback actuator have coupling components, the coupling half, for example, mounted thereon or constructed integrally, can advantageously achieve a compact configuration.

[0029] Advantageously, the rotation limiter can be configured to have a limiting torque that is higher than the maximum feedback torque of the feedback actuator. This limiting torque can be directly supported on the steering column housing and, consequently, not transmitted through a coupling. This has the advantage that the coupling only needs to transmit a smaller feedback torque than the limiting torque and can be designed to be correspondingly smaller and lighter. Attached Figure Description

[0030] Advantageous embodiments of the invention will now be explained in detail with reference to the accompanying drawings. Details are shown below: Figure 1 A schematic perspective view of the steering column according to the invention is shown. Figure 2 A schematic diagram showing the axial separation of the two sides along the longitudinal axis is provided. Figure 1 The steering column, Figure 3 A schematic diagram showing the two axes separated from each other is shown according to... Figure 1 Detailed diagram of the steering column rotation limiter. Figure 4 The dissection is shown according to Figure 1 Longitudinal sectional view of the steering column. Figure 5 With similar Figure 1 A schematic perspective view illustrates a second embodiment of the steering column according to the present invention. Figure 6 The dissection is shown according to Figure 5 A partial longitudinal sectional view of the steering column. Figure 7 With similar Figure 1 The schematic perspective view illustrates a third embodiment of the steering column according to the present invention. Figure 8 The dissection is shown according to Figure 7 A partial longitudinal section view of the steering column. Detailed Implementation

[0031] In different accompanying drawings, the same parts are always given the same reference numerals, and therefore are usually named or mentioned only once each.

[0032] Figure 1 The steering column 1 is shown in a schematic perspective view, viewed diagonally forward from the upper right along the direction of travel with respect to its mounting position.

[0033] The steering column 1 has a support unit 2, which has a fastener 21 for mounting on the vehicle body (not shown) and carries a housing unit 3, which constitutes the steering column housing.

[0034] The steering shaft 4 (which may also be referred to as the steering spindle) is rotatably supported in the housing unit 3 about a longitudinal axis L extending axially in the longitudinal direction. The steering shaft 4 has a connecting section 41 at its rear end, which faces the driver's position, on which a steering wheel, not shown, is mounted anti-rotatably.

[0035] Figure 2 The steering column 1 is shown in a schematic diagram, which shows the column separated from each other along the longitudinal direction of the longitudinal axis L.

[0036] The housing unit 3 is designed to be longitudinally adjustable by having an inner housing 32 that can be adjusted longitudinally in a coaxial and telescopic manner within the outer housing 31, as indicated by the double arrows. Similarly, the steering shaft 4 is designed to be of variable length and has an inner shaft 43 that is rotatably accommodated within the outer shaft 42.

[0037] Figure 3 A longitudinal sectional view of the steering column 1 is shown.

[0038] Rotation limiter 5 restricts the maximum possible rotation of steering shaft 4 relative to carrier unit 2. This rotation limiter has a hub 51 antirotatably connected to the inner shaft 43 of steering shaft 4, the hub having radially outwardly projecting stop elements 52. Hub 52 is arranged in an axial channel of an annular or tubular outer component 53, which is antirotatably fixed within the outer sleeve 31 of housing unit 3 about the longitudinal axis L, and has radially inwardly projecting mating stop elements 54. These mating stop elements can stop circumferentially on stop elements 52, thereby limiting the relative rotation of hub 51 relative to outer component 53, and consequently limiting the maximum relative rotation of steering shaft 4 relative to housing unit 3.

[0039] The feedback actuator 6 is capable of coupling feedback torque input to the steering shaft 4. This feedback actuator has an actuator housing 61, which, according to... Figure 1 or Figure 3 In its installation position, the actuator shaft 62 is rotatably supported within the actuator housing about the longitudinal axis L; that is, the actuator shaft is arranged here aligned with the steering shaft 4. The actuator shaft 62 can be driven to rotate by an electric motor 63, specifically via a transmission mechanism comprising a drive wheel 64 anti-rotatingly mounted on the actuator shaft 62. According to... Figure 1 , Figure 2 and Figure 3 In this embodiment, the transmission device is configured as a belt drive, and the transmission pulley 64 is correspondingly configured as a pulley, around which a belt 65, which can be driven by a motor 63, moves. The belt 65 may preferably be configured as a toothed belt. The feedback actuator 6 includes a control instrument 68, which is configured and electrically connected to the motor 63 to operate the motor 63.

[0040] The electronic control instrument 68 is also known as an ECU (Electronic Control Unit). The main function of the ECU is to control and monitor the operation of the motor 63. In this way, the ECU receives and processes electronic signals from the vehicle or on-board rotation sensor 8, and controls the motor 63 based on these signals.

[0041] To transmit the feedback torque, a coupling 7 is arranged between the rotation limiter 5 and the feedback actuator 6. This coupling, according to the invention, is configured as a releaseable or separable connector, specifically, as a two-piece claw connector. The claw connector includes a first connector half 71 mounted on the actuator shaft 62 and a second connector half 72 mounted on the steering shaft 4, specifically on the inner shaft 43.

[0042] The two connector halves 71 and 72 have axially projecting, segmental connector claws 73 on their axially opposite end sides. These connector claws can be moved toward the housing unit 3 by an axially oriented assembly motion M (by means of the feedback actuator 6), as in... Figure 2 As indicated by the arrow in the image, it enters the torque-fitted coupling with a rotational shape about the longitudinal axis L.

[0043] During assembly, the actuator housing 61 is axially secured to the housing unit 3 by means of fasteners (e.g., bolts or the like) not explicitly shown herein, in order to achieve the desired effect according to... Figure 1 or Figure 4 The assembly is complete. Here, the coupling halves 71 and 72 are engaged, so that the coupling 7 is connected.

[0044] In the example shown, the second connector half 72 is rotatably fixed to the inner shaft 43 and can be axially supported on the hub 51. However, it is also conceivable and feasible for the second connector half 72 to be constructed together with the hub 51 as a single or integral component.

[0045] Figure 5 and Figure 6 A second embodiment of the steering column 1 according to the invention is shown, wherein the same reference numerals are used for components that function identically. Figure 6 The image shows an enlarged partial view of a longitudinal cross-sectional view in the region of the rotation limiter 6 and the feedback actuator 6. The feedback actuator 6 includes a control instrument 68, which is configured and electrically connected to the motor 63 to operate the motor 63.

[0046] The difference from the first embodiment lies in the design of the transmission device of the feedback actuator 6, which is here constructed as a worm gear transmission device. The worm gear transmission device includes a worm 66, which is connected to the motor shaft of the motor 63, and the worm is engaged with a transmission wheel 65, which is here constructed as a worm wheel, and the transmission wheel is connected to the actuator shaft 62 as in the first embodiment.

[0047] exist Figure 7 and Figure 8 In, with similar Figure 5 and Figure 6 The third embodiment shown in the view differs from the two embodiments described above in that it implements direct drive. Here, no transmission device is provided between the motor 63 and the actuator shaft 62. Instead, the rotor 67 is directly mounted on the actuator shaft 62, as in... Figure 8As can be seen in the example shown, the actuator housing 61 is identical to the motor housing of the motor 63. The feedback actuator 6 includes a control instrument 68, which is configured and electrically connected to the motor 63 to operate the motor 63.

[0048] In all the embodiments shown herein, when the feedback actuator 6 is axially mounted on the steering column 1, the coupling 7 is automatically and without tools brought into engagement. According to the invention, the coupling 7 is designed to be separable. Thus, the feedback actuator 6 can be easily removed from the housing unit 3 when needed, while the coupling 7 automatically disengages.

[0049] In all the embodiments shown, a rotation sensor 8 may be provided, which rotation sensor in Figure 8 The rotation sensor is illustrated exemplarily in the figure. This rotation sensor can detect the rotation of the steering shaft 4 relative to the steering column housing 3 using measurement techniques, and includes, for example, position and / or torque sensors. Alternatively or additionally, the rotation sensor 8 can be mounted on the feedback actuator 6, such as... Figure 4 and Figure 6 As shown.

[0050] Explanation of reference numerals in the attached figures

[0051] 1 Steering column

[0052] 2 bearing units

[0053] 21 Fasteners

[0054] 3-shell unit

[0055] 31 outer casing

[0056] 32 Inner Shell

[0057] 4 steering shafts

[0058] 41 Connecting Section

[0059] 42 inner shaft

[0060] 43 outer shaft

[0061] 5. Rotation limiter

[0062] 51 wheel hub parts

[0063] 52 Stop element

[0064] 53 External Components

[0065] 54 Matching stop elements

[0066] 6 feedback actuators

[0067] 61 Actuator Housing

[0068] 62 actuator shaft

[0069] 63 motor

[0070] 64 drive wheels

[0071] 65 belt

[0072] 66 worm gear

[0073] 67 rotor

[0074] 68. Control Instruments (ECUs)

[0075] 7 couplings

[0076] 71 First connector half

[0077] 72 Second connector half

[0078] 73 Connector Claw

[0079] 8 Rotation Sensors

[0080] L-axis

[0081] M Assembly Movement

Claims

1. A steering column (1) for a motor vehicle, comprising: The steering shaft (4) is rotatably supported in the steering column housing (3) about a longitudinal axis (L) extending in the longitudinal direction, a rotation limiter (5) for limiting the rotation of the steering shaft (4), and a feedback actuator (6) for coupling feedback torque into the steering shaft (4), the feedback actuator including an actuator housing (61) and an actuator shaft (62) that can be driven to rotate relative to the actuator housing by a motor. Its features are, The feedback actuator (6) and the steering column (1) have a releasable connection.

2. A steering column according to claim 1, wherein The actuator housing (61) can be connected to the steering column housing (31).

3. A column according to any one of the preceding claims, characterised in that An axial connection is arranged between the actuator housing (61) and the steering column housing (3).

4. A column according to any one of the preceding claims, characterised in that A coupling (7) capable of axial connection is arranged between the steering shaft (4) and the actuator shaft (62).

5. A column according to claim 4, wherein The coupling (7) is constructed as a form-fitting connector capable of axial engagement.

6. A column according to any one of the preceding claims, characterised in that The coupling (7) has a two-piece construction.

7. A column according to any one of the preceding claims, characterised in that The coupling (7) can be connected without tools.

8. The steering column according to any one of the preceding claims, characterized in that, The coupling (7) has vibration damping elements.

9. The steering column according to any one of the preceding claims, characterized in that, The coupling (7) has a spring element.

10. The steering column according to any one of the preceding claims, characterized in that, The coupling (7) has a misalignment compensation structure.

11. The steering column according to any one of the preceding claims, characterized in that, The rotation limiter (5) is integrated into the steering column housing (3).

12. The steering column according to any one of the preceding claims, characterized in that, The feedback actuator (6) has a transmission device.

13. The steering column according to any one of the preceding claims, characterized in that, The coupling (7) is structurally integrated with the rotation limiter (5) and the feedback actuator (6).

14. The steering column according to any one of the preceding claims, characterized in that, The rotation limiter (5) has a limiting torque that is greater than the maximum feedback torque of the feedback actuator (6).

Images