Steering column module for a steer-by-wire system for a motor vehicle

Abstract

It is proposed to implement a mechanical end stop for a steer-by-wire steering system by having a traction element with a stop rotate around a system consisting of a drive wheel mounted on the steering shaft and at least one idler wheel. The drive wheel and the idler wheel can then be designed to provide a suitable stop for the stop element. At least one of the wheels can be designed such that the stop element can pass over it without contact.

Description

[0001] The invention relates to a steering column module for a steer-by-wire system for a motor vehicle with a steering shaft and with a rotation angle limitation system, and to a motor vehicle with such a steering column module.

[0002] Steer-by-wire systems for steering motor vehicles are a known technology. They are increasingly used in electric and hybrid vehicles. This technology replaces the mechanical connection between the steering wheel and the wheels with electronic controls. Instead of using a mechanical or hydraulic linkage, a steer-by-wire system transmits steering commands electronically via cables. A sensor detects the movement and angle of the steering wheel, which is then converted into electronic signals. These signals are then sent to electronic control units and actuators, which in turn control the steering movements of the wheels.Steer-by-wire steering systems consist of a wheel actuator and a steering column module, also known as a force feedback actuator (FFA), which is designed to provide the driver with an electrically applied steering feel. The actuators take over the physical movement of the steering wheel, which is normally achieved through a mechanical linkage. To give the driver the feeling of the road that conventional systems provide through the direct connection between the steering wheel and the wheels, an artificial feedback system is often used. This simulates the resistance and vibrations that are normally felt through the steering wheel.

[0003] Such a force feedback actuator requires a mechanical end stop to limit the steering angle when the system is switched off, for example, when de-energized or in the event of a malfunction. This prevents damage to components such as the steering wheel control wiring or the steering wheel airbag wiring. The rotation angle limiting system restricts the range of motion accessible to the control element, such as the steering wheel or steering shaft. Since this is a purely rotary motion, this range can be described by specifying an angular range. In a conventional vehicle with a steering wheel mechanically connected to the wheels being steered, this range of motion is determined, for example, by the length of a rack driven by the steering shaft. A steer-by-wire steering system lacks such a mechanical end stop.This end stop can be implemented in various ways. It is desirable to allow steering angles greater than 360°. Therefore, the end stop must allow more than one rotation, or the distance between the two end stops must allow the desired rotation angle, for example, 540°. To enable such large steering angles, the known technical solutions are relatively complex and costly.

[0004] For example, DE 10 2018 115 565 A1 discloses a steer-by-wire system with a lockable clutch, wherein the clutch is controlled by an electromagnetic actuator to prevent further rotation of the steering wheel shaft when the wheels have reached the end stop position specified in the respective direction of rotation. For this purpose, the clutch locks the steering wheel shaft in the aforementioned situation according to an electronic control of the power generation means.

[0005] DE 10 2023 103 513 A1 describes a rotation angle limiting device for a steering unit, in particular for a steer-by-wire system of a vehicle. This device consists of two ring-shaped elements, each connected to the steering shaft and the housing of the steering unit. Both elements have circular segment-shaped rolling tracks, which together form a pair in which a rolling element rolls. The rolling element limits the relative rotational movement between the two elements by contacting the ends of the rolling tracks, thereby limiting the rotation angle to a specific range.

[0006] The known systems are often expensive, friction-intensive, require a large amount of installation space in the axial direction, and / or are limited in the achievable end-stop angle. It is therefore the object of the present invention to provide an improved method for a mechanical end stop of a steer-by-wire system with regard to the problems described.

[0007] The problem is solved by a steering column module for a steer-by-wire system for a motor vehicle, comprising a steering shaft and a steering angle limiting system, wherein the steering angle limiting system includes a drive wheel arranged on the steering shaft, at least one idler wheel, and a traction element connecting the drive wheel to the idler wheel, and wherein a stop element is arranged on the traction element which limits movement of the traction element relative to the drive wheel and / or to the idler wheel. The problem is further solved by a motor vehicle with such a steering column module.

[0008] It is therefore proposed to implement a mechanical end stop for a steer-by-wire steering system by having a traction element with a stop rotate around a system consisting of a drive wheel mounted on the steering shaft and at least one idler wheel. The drive wheel and the idler wheel can then be designed to provide a suitable stop for the stop element. At least one of the wheels can be designed such that the stop element can pass over it without contact.

[0009] For the purposes of this description, a steering shaft is understood to be, in particular, a structure rotatable about a longitudinal axis, on which a control element is arranged by means of which a user can steer a motor vehicle. The control element can be, for example, a steering wheel. Typically, the control element, usually the steering wheel, is arranged at one end of the steering shaft, and the drive wheel is carried at a position not visible from the interior of the motor vehicle. The drive wheel can be, for example, a gear or a toothed disc. The drive wheel rotates together with the steering shaft and the control element. This rotational movement is transmitted via the traction element to the idler wheel, which then also rotates. The steering shaft can be designed as a rod or a tube. The drive wheel transmits a torque applied by the user to the idler wheel via the traction element.

[0010] The traction element can be designed to engage positively with the drive wheel. This traction element can be a toothed belt or a chain. A toothed belt results in a particularly quiet system. Other traction elements, such as friction-based traction elements like belts or straps, are also possible. However, a positive-locking traction element is less prone to failure.

[0011] The stop element is rigidly connected to the drive element. The stop element moves along the path of the drive element as the drive wheel rotates. Two different situations must be distinguished here. In the first state, the section of the drive element where the stop element is located is not in contact with the drive wheel or the idler wheel and can therefore move freely between them. In the second state, the section of the drive element where the stop element is located is in contact with the drive wheel or the idler wheel. In this case, mechanical interaction between the stop element and the respective wheel is possible, which can prevent further movement of the stop element and thus of the entire system. If the drive element is a toothed belt, the stop element may, for example, be heat-embedded within the toothed belt.

[0012] According to an advantageous embodiment, the stop element has a projection arranged on the wheel side. The term "arranged on the wheel side" here refers in particular to the fact that the projection extends from the traction element towards the wheels, i.e., the drive wheel and the idler wheel. In other words, the projection faces the inside of the closed curve formed by the traction element. This ensures that the projection can mechanically interact with the drive wheel and lock it.

[0013] Advantageously, the stop element can be provided to have a width of 10% to 80%, preferably 20% to 70%, and particularly preferably 30% to 60% of the width of the traction element. In other words, the stop element does not occupy the entire width of the traction element. In the area of ​​the traction element where the stop element is not located, the traction element can, under certain conditions, continue to perform its original function of transmitting power between the wheels, whereas in an area of ​​the traction element that would be completely filled by the stop element, the transmission of force from the traction element to the respective wheel, or vice versa, would be made more difficult or impossible.

[0014] At the same time, it is advantageous if the stop element is located in a central area of ​​the traction element when viewed axially. This ensures the most symmetrical possible load distribution on the traction element and the respective wheels.

[0015] As previously described, the traction element can be a toothed belt with teeth of reduced width on both sides of the stop element. This ensures that the area of ​​the traction element where the stop element is located is also suitable for transmitting forces between the traction element and the wheel. This results in smooth and low-wear operation.

[0016] Advantageously, the traction element is designed to be enclosed around the drive wheel and the idler wheel. The drive wheel, the idler wheel, and the steering shaft then perform purely rotational movements, but are otherwise stationary. The only linear movement relevant to the system's function is executed by the stop element.

[0017] According to an advantageous embodiment, the deflection wheel is designed such that, in a position of the traction element where a portion of the traction element, in which the stop element is arranged, is in contact with the deflection wheel, a projection arranged on the stop element does not touch the deflection wheel. It is correspondingly possible that, in the described situation, the entire stop element does not touch the deflection wheel. The stop element is then therefore not in physical contact with the deflection wheel. In other words, the stop element can then pass the deflection wheel without contact. The system is thus designed such that there is no interaction whatsoever between the stop element and the deflection wheel.

[0018] It can be advantageous to provide the deflection wheel with a groove that largely prevents contact between the stop element and the deflection wheel when the traction element is in a position where a portion of the traction element, in which the stop element is located, is in contact with the deflection wheel. For example, if the stop element has a projection facing the deflection wheel, located in a central region of the traction element, the deflection wheel can have a corresponding groove. This groove can also be located in a central region of the deflection wheel. The depth of the groove can correspond to the extent of the projection from the traction element towards the wheel. Advantageously, the depth of the groove is slightly greater than the extent of the projection towards the deflection wheel.Accordingly, it is advantageous if the width of the groove is slightly larger than the width of the projection. This allows the projection to move completely without contact through the groove.

[0019] The drive wheel can be designed such that when the stop element comes into contact with the drive wheel, the stop element blocks any further rotation of the drive wheel. This results in the desired stop effect, preventing the user from further rotating the control element, such as the steering wheel.

[0020] For this purpose, the drive wheel can be designed to form a positive connection with the stop element upon contact. An axial force can then be exerted on the stop element, preventing the traction element from lifting or riding up onto the drive wheel.

[0021] It is advantageous if the traction element has the lowest possible elasticity. The positive locking mechanism can, in particular, involve the engagement of a portion of the stop element, for example, the projection of the stop element, behind a retaining element arranged on the drive wheel. Such a retaining element can be arranged in such a way that it defines a cavity located between the retaining element and the axle of the drive wheel, into which a portion of the stop element, for example, the projection of the stop element, can engage.

[0022] According to an advantageous embodiment, the drive wheel has a groove in which a plurality of transverse ribs run. These transverse ribs can perform the function of the previously described retaining element. The groove can have two radially extending side walls, and the two side walls can be connected to each other by the plurality of transverse ribs. The stop element, for example, the projection of the stop element, can then engage in the area of ​​the groove that lies between the transverse ribs and the bottom of the groove. The stop element can thereby come into contact with the side of the respective transverse rib facing the bottom of the groove and thus transmit the force.

[0023] Depending on the variation in the number and arrangement of the idler wheels and the drive wheel, as well as their diameters, the package size of the system and the maximum end stop angle (or the achievable angular range of the system) can be influenced. For example, the diameter of the drive wheel can be larger than the diameter of the idler wheel. This improves the power transmission from the steering shaft to the traction element. It is also possible for the diameter of the drive wheel to be smaller than the diameter of the idler wheel. In this way, the required installation space can be reduced, as the system can achieve a larger accessible angular range with a smaller linear distance between the drive wheel and the idler wheel(s).The circumference of the drive wheel can also be between 50% and 200%, between 100% and 200%, or between 100% and 150% of the linear distance between the drive wheel and an idler wheel. Depending on the precise design of the system and the number of idler wheels, a desired steering angle range of, for example, 540° can be achieved within these ranges for most systems. The linear distance can be defined as the distance between the axes of rotation of the respective wheels.

[0024] According to one embodiment, the steering column module can have at least a first deflection wheel and a second deflection wheel. In this way, the required installation space can be reduced in at least one dimension.

[0025] As previously described, the angular range accessible to the system can be adjusted by appropriately selecting the number of deflection pulleys, the spacing between them, and their diameters. For example, the rotation angle limiting system can be designed such that the angle between a first stop position of the stop element and a second stop position is between 400° and 800°, preferably between 450° and 680°. The system can thus be adapted to the specific application. It is possible, for example, to provide two, three, four, five, or even more deflection pulleys. Some of the deflection pulleys can also function as tension rollers. This allows the system to be adapted to different space constraints.For example, if a V-shaped or "banana-shaped" installation space is available, a system consisting of one drive wheel and a total of three deflection wheels could be used to create an outer circumference of the traction element that is adapted to the available space. One of the deflection wheels can then be positioned relatively close to the drive wheel. The other deflection wheels or tension rollers can also be designed to allow for contactless passage over the stop element. Preferably, all wheels are arranged in the same plane.

[0026] Advantageously, the stop element and / or the drive wheel can have a noise-reducing coating. This prevents loud clicking noises when the end stop is reached.

[0027] The above descriptions illustrate embodiments in which the stop element can pass the deflection wheel(s) without contact. The mechanical end stop is achieved by the stop element striking the drive wheel. A kinematic reversal, in which the stop element can pass the drive wheel without contact and the end stop is achieved by the stop element striking another wheel, for example, the deflection wheel or one of the deflection wheels, is also conceivable. It is also possible to limit the steering angle when the steering shaft rotates clockwise by the stop element striking a first wheel, and to limit the steering angle when the steering shaft rotates counterclockwise by the stop element striking a second wheel.Both the first and second wheels can be the drive wheel or a deflection wheel.

[0028] Exemplary embodiments of the invention are explained in more detail with reference to the drawings and the following description. The drawings show: Fig. 1: a schematic sectional view of a rotation angle limiting system according to the invention, Fig. 2: a side view of the rotation angle limiting system made of Fig. 1, Fig. 3: a view of a second embodiment of a rotation angle limiting system according to the invention, and Fig. 4: a sectional view according to marking A in Fig. 3.

[0029] Fig. Figure 1 shows a schematic sectional view of a rotation angle limiting system 2 according to the invention. The rotation angle limiting system 2 essentially consists of a drive wheel 6 arranged on the steering shaft 4, a first deflection wheel 8, a second deflection wheel 10, and the traction element 12, which in the illustrated embodiment is designed as a toothed belt. Accordingly, the drive wheel 6 and the deflection wheels 8 and 10 are designed as toothed pulleys. The traction element 12 connects the drive wheel 6 to the two deflection wheels 8 and 10. The three wheels 6, 8, and 10 are arranged in a triangular shape. In the illustrated embodiment, the triangular shape roughly corresponds to an equilateral triangle. The distance from the center point of the first deflection wheel 8 to the center point of the second deflection wheel 10 is denoted by l1. The distance from the center point of the first deflection wheel 8 to the center point of the drive wheel 6 is denoted by l2. In the illustrated embodiment, therefore, l1 roughly equals l2.

[0030] The drive wheel 6 has a diameter d1 that is larger than the diameter d2 of the two deflection wheels 8 and 10. The two deflection wheels 8 and 10 are identical in design. The diameter d1 is more than twice the diameter d2. Other values ​​for the lengths l1 and l2 and the diameters d1 and d2, or their ratios to each other, are of course also possible.

[0031] The figure shows the system in its neutral position. In other words, a steering wheel (not shown) attached to the steering shaft 4 is not deflected. This corresponds to a vehicle traveling straight ahead. The stop element 14 is arranged and attached to the traction element 12. The stop element 14 consists of a base body 16 and a projection 18. The projection 18 is located on the side of the stop element 14 facing the wheels 6, 8, and 10. In the neutral position shown, the stop element 14 is located exactly midway between the first idler wheel 8 and the second idler wheel 10. If the drive wheel 6 is now rotated, for example, clockwise, the stop element 14 moves to the right in the figure, toward the second idler wheel 10. If the drive wheel 6 continues to rotate clockwise, the stop element 14 passes the second idler wheel 10 and then moves toward the drive wheel 6.It can be seen that the stop element 14 projects perpendicularly to the longitudinal direction of the traction element 12 on both sides beyond the traction element 12. For the function of the rotation angle limiting system 2, the projection 18, which extends towards the inside of the system formed by the wheels 6, 8, 10 and the traction element 12, is particularly important. The two deflection wheels 8, 10 are designed such that when the traction element 12 moves around the respective deflection wheel 8, 10, they do not come into contact with the stop element 14, and in particular not with its projection 18. The drive wheel 6, on the other hand, is designed to interact with the stop element 14 in such a way that if the stop element 14 comes into contact with the drive wheel 6, further rotation of the drive wheel 6 is blocked. When the direction of rotation is reversed, the stop element 14 then releases itself from the drive wheel 6.For example, if, after the stop element 14 has struck the drive wheel 6, and the drive wheel 6 has been rotated clockwise, the drive wheel 6 is then rotated counterclockwise again, the stop element 14 releases itself from the drive wheel 6 as described, passes first the second deflection wheel 10 and then the first deflection wheel 8, and then, during a further counterclockwise rotation of the drive wheel 6, strikes the drive wheel 6 on the left side shown in the figure.

[0032] Fig. Figure 2 shows a side view of the rotation angle limitation system 2. Fig. 1. It can be seen that the traction element 12, designed as a toothed belt, has teeth 24 extending over its entire width b1. The traction element 12 also has, as described, the stop element 14, which essentially consists of the base body 16 and the projection 18. The first deflection pulley 8, in turn, has a circumferential groove 26, which is designed such that the projection 18 of the stop element 14 can move through the groove 26 without touching the first deflection pulley 8.

[0033] Fig. 3 shows a view analogous to Fig. Figure 2 shows a second embodiment of a rotation angle limiting system 2 according to the invention. For clarity, the traction element is not shown in the illustrated view. The upper part of the figure shows the first deflection wheel 8, in which the interaction of the stop element 14 and the groove 26 is particularly evident. The lower part of the figure shows the drive wheel 6 in a sectional view. The drive wheel 6 also has a circumferential groove 28, which is interrupted by the webs 30 at approximately half its height. This creates a cavity between the webs 30 and the bottom of the groove 28, into which the projection 18 of the stop element 14 can engage. This establishes a positive-locking connection between the stop element 14 and the drive wheel 6 when the stop element 14 comes into contact with the drive wheel 6.This positive locking connection transmits the forces that then lead to a blockage of further rotation of the drive wheel 6 and thus also of the connection with it via the in the . Fig. 3. Steering shaft not shown, connected to the control element or the steering wheel.

[0034] Fig. 4 shows a sectional view according to marker A in Fig. 3. It is particularly evident here that the webs 30, which are arranged in the groove 28 of the drive wheel 6, together with the inner circumference of the groove 28, define the cavity 32 into which the projection of the stop element can then engage. In the illustrated embodiment, the webs 30 are arranged near the outer circumference 36 in the groove 28. Reference symbol list 2 Rotation angle limiting system 4 Steering shaft 6 drive wheel 8 first deflection wheel 10 second deflection wheel 12 traction elements 14 Stop element 16 basic shapes 18 lead 20 first end 22 second end 24 teeth 26 Nut 28 Nut 30 crossbar 32 Cavity 34 inner circumference 36 outer circumference QUOTES INCLUDED IN THE DESCRIPTION

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

[0000] DE 10 2018 115 565 A1

[0004] DE 10 2023 103 513 A1

[0005]

Claims

[1] Steering column module for a steer-by-wire system for a motor vehicle, comprising a steering shaft (4) and a steering angle limiting system (2), wherein the steering angle limiting system (2) comprises a drive wheel (6) arranged on the steering shaft (2), at least one deflection wheel (8) and a traction element (12) connecting the drive wheel (6) to the deflection wheel (8), and wherein a stop element (14) is arranged on the traction element (12) which limits a movement of the traction element (12) relative to the drive wheel (6) and / or to the deflection wheel (8). [2] Steering column module according to claim 1, wherein the traction element (12) is a toothed belt. [3] Steering column module according to one of the preceding claims, wherein the stop element (14) has a wheel-side projection (18). [4] Steering column module according to one of the preceding claims, wherein the stop element (14) has a width of 10% to 80%, preferably 20% to 70%, particularly preferably 30% to 60% of a width of the traction element (12). [5] Steering column module according to one of the preceding claims, wherein the deflection wheel (8) is designed such that in a position of the traction element (12) in which a portion of the traction element (12) in which the stop element (14) is arranged is in contact with the deflection wheel (8), a projection (18) arranged on the stop element (14) does not touch the deflection wheel (8). [6] Steering column module according to one of the preceding claims, wherein the deflection wheel (8) has a groove (26) which at least largely avoids contact between the stop element (14) and the deflection wheel (8) when the traction element (12) is in a position in which a portion of the traction element (12) in which the stop element (14) is arranged is in contact with the deflection wheel (8). [7] Steering column module according to one of the preceding claims, wherein the drive wheel (6) is configured to engage positively with the stop element (14) when the stop element (14) makes contact with the drive wheel (6), so that a force in the axial direction is exerted on the stop element (14) which prevents the traction element (12) from lifting or riding up onto the drive wheel (6). [8] Steering column module according to one of the preceding claims, wherein the drive wheel (6) has a groove (28) in which a plurality of cross webs (30) run. [9] Steering column module according to one of the preceding claims, wherein the stop element (14) and / or the drive wheel (6) have a noise-reducing coating. [10] Motor vehicle with a steering column module according to one of the preceding claims.

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