Steering system for a vehicle

Abstract

The invention relates to a steering system (10) for a motor vehicle comprising a steering shaft (11), an extendable outer tube (12), and an extendable support (13), wherein the steering shaft (11) is rotatably mounted in the extendable outer tube (12). The extendable outer tube (12) is longitudinally adjustable within the extendable support (13). A magnetorheological brake (18) is arranged in the extendable outer tube (12) and is configured to act between the extendable outer tube (12) and the steering shaft (11). The extension tube (12) has in a first longitudinal section (16) a plurality of external sliding bearing zones (14) distributed around the circumference of the extension tube (12) for longitudinally sliding bearing of the extension tube (12) relative to the extension carrier (13) and a plurality of internal press-fit zones (17) distributed around the circumference of the extension tube (12) for mounting the magnetorheological brake (18).

Description

[0001] The invention relates to a steering system for a motor vehicle with the features of the preamble of claim 1.

[0002] Prior art steering systems often feature longitudinal adjustment to adapt the position of the steering linkage or steering wheel to the driver's seating position. In electronic steering systems, which lack a mechanical connection between the steering linkage or steering wheel and the wheels being steered (so-called steer-by-wire systems), installation space is particularly limited to fully exploit the space-saving advantages of eliminating the steering linkage. Furthermore, additional components are required, such as magnetorheological brakes, end stops, or electric motors, to compensate for the lack of feedback from the mechanical connection, thus compensating for the absence of haptic feedback to the driver. For example, magnetorheological brakes are known in the prior art for use in steer-by-wire systems to simulate the steering resistance of a mechanical linkage for the operator.In a magnetorheological brake, for example, two components rotating relative to each other—a stator with a coil and a rotor—are slowed down when the brake is activated. A magnetorheological medium is located in an annular gap between the stator and rotor. When current flows through the coil, this medium forms chain-like structures in the resulting magnetic field. This generates a braking force between the rotor and stator, which depends on the magnetic field generated by the coil in the annular gap. Such electrically controlled brakes are often also called powder brakes because of the magnetorheological medium.

[0003] The object of the invention is therefore to provide a steering system for a motor vehicle that allows longitudinal adjustment and the inclusion of additional components in the smallest possible installation space.

[0004] The invention solves the problem with the features of the independent claims.

[0005] A steering system for a motor vehicle is proposed, comprising a steering shaft, an extension tube, and an extension support. The steering shaft is rotatably mounted in the extension tube, which is longitudinally adjustable within the extension support. A magnetorheological brake is arranged within the extension tube and is configured to act between the extension tube and the steering shaft. The extension tube has, in a first longitudinal section, a plurality of outer sliding bearing zones distributed around its circumference for longitudinally sliding mounting of the extension tube relative to the extension support, and a plurality of inner press-fit zones distributed around its circumference for mounting the magnetorheological brake.

[0006] This steering system allows for a very compact design. The magnetorheological brake can be easily inserted into the extension tube and held in place by the press-fit zones. The extension tube is preferably a formed tube element in which the press-fit zones have been, for example, formed inwards. Furthermore, cutouts are preferably made or notched. The extension tube can therefore be manufactured cost-effectively. Simultaneously, the extension tube can be slidably mounted along its longitudinal axis in the same longitudinal section by means of the sliding bearing zones. The longitudinal axis is parallel to the axis of rotation of the steering shaft. Accordingly, the steering shaft is rotatably mounted about its longitudinal axis in the extension tube, for example by steering shaft bearings. The steering shaft is preferably fixed in position longitudinally within the extension tube.The steering torque can be transferred from the steering shaft to the extension tube via the magnetorheological brake. For this purpose, the magnetorheological brake has, for example, a rotor rigidly connected to the steering shaft and a stator rigidly connected to the extension tube, between which a magnetorheological medium can be activated by a coil. The corresponding braking torque is absorbed by the extension tube and transferred to the extension carrier. The extension tube is mounted in the extension carrier in a rotationally fixed manner to dissipate the steering torque, for example, into a vehicle structure.

[0007] The rotationally fixed mounting, combined with the longitudinal sliding motion of the drawer slide tube within the drawer support, is achieved by the numerous external sliding bearing zones distributed around the circumference. Simultaneously, the magnetorheological brake can be held in place by the press-fit zones in this longitudinal section. The press-fit zones and sliding bearing zones can alternate, for example, in the first longitudinal section. Furthermore, additional zones or sections can be provided around the circumference alongside the majority of sliding bearing and press-fit zones. The distribution of the press-fit and sliding bearing zones around the circumference of the drawer slide tube can be uniform or uneven.

[0008] In preferred embodiments, the sliding bearing zones have a flat or concave outer surface. This allows the use of comparatively simple sliding bearings, which are preferably arranged on the extension arm. The flat surface facilitates the absorption of steering torques. Concave outer surfaces of the sliding bearing zones, which preferably have a constant concave curvature parallel to the longitudinal axis, are very advantageous for absorbing and transmitting steering torques from the extension tube to the extension arm. In further possible embodiments, at least one sliding bearing zone has a flat outer surface and at least one other sliding bearing zone has a concave outer surface.

[0009] According to a further development, it is proposed that the press-fit zones have a partially cylindrical, inner surface. In this way, a cylindrical stator of a magnetorheological brake can be easily inserted into the extension tube and fixed there. In alternative embodiments, the outer contour of a magnetorheological brake can have a non-circular shape that deviates from a cylinder, at least in some zones, with the press-fit zones preferably being shaped to accommodate the magnetorheological brake.

[0010] According to a further development, it is proposed that the first longitudinal section transitions into a second longitudinal section in one longitudinal direction, with radially inwardly directed shoulders, tabs, and / or indentations being provided at the end of the press-fit zones at the transition between the first and second longitudinal sections. This allows for easy positioning during the installation of the magnetorheological brake, while simultaneously absorbing the corresponding bearing forces. The tabs can, for example, be pressed in during installation. Furthermore, the extension tube preferably has through-holes for fixing it after the insertion of a magnetorheological brake or another component.

[0011] Preferably, the first longitudinal section transitions into a second longitudinal section in one longitudinal direction, with the sliding bearing zones of the first longitudinal section continuing into the second longitudinal section, and the press-fit zones transitioning into intermediate zones. In the second longitudinal section, therefore, as in the first longitudinal section, displacement along the longitudinal axis is possible due to the bearings on the sliding bearing zones, while a receptacle for the magnetorheological brake is preferably not present in the second longitudinal section. The extension tube can, for example, be positioned in the intermediate zones at a distance from the central or longitudinal axis between the press-fit zones and the sliding bearing zones.

[0012] Furthermore, according to an advantageous embodiment, it is proposed that the extension tube has an internal, cylindrical bearing seat zone for a steering shaft bearing in a third longitudinal section. The third longitudinal section preferably adjoins the second longitudinal section. This allows, for example, simple, step-by-step assembly of a steering shaft bearing and a magnetorheological brake in the extension tube.

[0013] Preferably, at least one sliding bearing zone has a connection point for longitudinal adjustment of the extension tube relative to the extension carrier. This allows the position of the extension tube, and thus also of the steering shaft, relative to the extension carrier to be fixed, enabling various positions along the longitudinal axis, for example, for positioning a steering wheel in the interior of a motor vehicle. The longitudinal movement of the extension tube can preferably be locked and unlocked by the longitudinal adjustment at the connection point, allowing, for example, manual adjustment. In an advantageous embodiment, at least one electric actuator for the longitudinal adjustment of the extension tube relative to the extension carrier is arranged on the extension carrier. This allows for a simple, electrically controlled longitudinal adjustment of the steering shaft.

[0014] According to a further development, several sliding bearings are arranged on the extension arm for supporting the extension tube at the sliding bearing zones. This allows for smooth sliding parallel to the longitudinal axis and high rigidity when absorbing steering torque as well as forces acting perpendicular to the steering axis, for example at the free end with a steering wheel, and their resulting moments. The sliding bearings are preferably plain bearings, and more preferably adjustable, backlash-free plain bearings, which require little installation space. Furthermore, the sliding bearings can preferably also be rolling bearings with advantageously low sliding friction. In further advantageous embodiments, combinations of both bearing principles are also possible.

[0015] Furthermore, an electric motor is preferably arranged within the extendable housing tube. This motor is connected to the steering shaft and configured to rotate the steering shaft relative to the housing tube. In addition to the magnetorheological brake, the electric motor can provide haptic feedback to the steering operator. The proposed arrangement of the electric motor allows for a compact steering system, while simultaneously providing an actuating torque to the steering shaft in addition to the braking torque of the magnetorheological brake. Therefore, the steering shaft does not need to exit the extendable housing tube opposite the input device or steering wheel. In some embodiments, a gearbox is provided on the electric motor. In alternative embodiments, the electric motor is located outside the extendable housing tube, which correspondingly increases the required installation space.

[0016] Preferably, the steering system has a cable routing channel formed between the extension tube and the magnetorheological brake for longitudinal cable routing. This allows cable routing to an airbag and / or control element at the free end of the steering shaft, for example, on a steering mechanism or steering wheel.

[0017] The invention is explained below with reference to preferred embodiments and the accompanying figures. Fig. 1 a steering system; Fig. 2 a steering system in a sectional view along the longitudinal axis; Fig. 3 another steering system in a sectional view along the longitudinal axis; Fig. 4 a steering system in a sectional view perpendicular to the longitudinal axis; Fig. 5 a steering system with a freestanding extension carrier; and Fig. 6 a sectional view of a steering system with a freestanding extension beam.

[0018] Fig. Figure 1 shows an advantageous embodiment of a steering system 10 for a motor vehicle. The steering system 10 has a steering shaft 11 which is rotatably mounted in an extendable tube 12. The extendable tube 12 is held in an extendable support 13 and is slidably mounted therein along a longitudinal axis 29. The extendable tube 12 has several, in this advantageous embodiment five, sliding bearing zones 14, which are arranged distributed around the circumference of the extendable tube 12. The sliding bearing zones 14 are outer surfaces on the extendable tube 12 which are designed for mounting with slidability along the longitudinal axis 29.

[0019] The sliding bearing zones 14 are arranged in a first longitudinal section 16 and a second longitudinal section 19. The first longitudinal section 16 is located further from the free end 31 of the steering shaft 11 than the second longitudinal section 19, which merges into the first longitudinal section 16. In this advantageous embodiment, the sliding bearing zones 14 extend to the rear end of the extension sleeve tube 12.

[0020] The first longitudinal section 16 has, in addition to the sliding bearing zones 14, which extend as planar surfaces parallel to the longitudinal axis 29, several press-fit zones 17, in this advantageous embodiment three press-fit zones 17. The press-fit zones 17 serve for an internal mounting of a magnetorheological brake 18, in particular the stator of a magnetorheological brake 18, see Fig. 2.

[0021] In the Fig. Figure 2 shows a steering system 10 for a motor vehicle in a sectional view, so that the components integrated into the pull-out sleeve 12 are visible. The magnetorheological brake 18 is arranged in the first longitudinal section 16 of the pull-out sleeve 12 and makes contact with its inner surface at the press-fit zones 17, so that the stator with the two coils is held in the pull-out sleeve 12. In this advantageous embodiment, the press-fit zones 17 are partially cylindrical. The stator of the magnetorheological brake 18 is rotationally fixed, which can be achieved by the press-fit pressure at the press-fit zones 17 and / or by a positive fit. In this advantageous embodiment, the press-fit zones 17 transition into intermediate zones 28 at the transition from the first longitudinal section 16 to the second longitudinal section 19.At the transition from the first longitudinal section 16 to the second longitudinal section 19, an inwardly directed step 24 is provided, which positions the magnetorheological brake 18 and fixes it in an axial direction.

[0022] Adjustable sliding bearings 15 are mounted in the extension carrier 13, which can be connected to a vehicle structure. In this advantageous embodiment, these bearings are supported on the upper sliding bearing zone 14, so that the extension sleeve tube 12 can be easily adjusted axially, i.e., parallel to the longitudinal axis 29, within the extension carrier. In this advantageous embodiment, two electric actuators 27 are provided for active longitudinal and vertical adjustment.

[0023] Furthermore, two steering shaft bearings 21 are visible, which rotatably support the steering shaft 11 in the extension tube 12 and fix it in its longitudinal axis. In this advantageous embodiment, an electric motor 23 is provided in addition to the magnetorheological brake 18, which can apply a torque to the steering shaft 11. An end stop 30 is also provided, which forms the corresponding end stops of the steering shaft 11.

[0024] Fig. Figure 3 shows another embodiment of a steering system 10. In addition to a different magnetorheological brake 18, a telescoping cable 32 and a rotation sensor 33 can be seen in this embodiment.

[0025] Fig. Figure 4 shows a section through an embodiment of a steering system 10. The various longitudinal sections 16, 19, 22 of the extension tube 12 are visible. The first longitudinal section 16 contains five possible sliding bearing zones 14, which extend axially to the end of the second longitudinal section 19. The flat surfaces of the sliding bearing zones 14 are visible. In addition, the first longitudinal section 16 provides three press-fit zones 17, which secure the magnetorheological brake 18 inside the extension tube 12. In alternative embodiments, the first longitudinal section 16 could, for example, also contain four press-fit zones 17 and four sliding bearing zones 14, or three press-fit zones 17 and three sliding bearing zones 14. Of the five sliding bearing zones 14, only three are used for mounting in the extension support 13 in this embodiment.Two sliding bearing zones 14 (the left and the right) are used to accommodate other components, such as crash elements, longitudinal sliding drives and / or adjustment locking devices.

[0026] The press-fit zones 17 transition into intermediate zones 28 at the transition to the second longitudinal section 19. Towards the free end 31 of the steering shaft 11, a third longitudinal section 22 adjoins the second longitudinal section 19, which has a bearing seat zone 22. In this embodiment, the bearing seat zone 22 is cylindrical.

[0027] In addition, a cable guidance channel 25 is visible, which enables the routing of a cable 32 between magnetorheological brake 18 and extension sleeve tube 12 through a geometric gap.

[0028] Fig. Figure 5 shows an embodiment of a steering system 11 in which the extension carrier 13 has been isolated. In this view, the connection points 26 are visible, which allow the displacement along the longitudinal axis 29 to be determined.

[0029] Fig. Figure 6 shows a cross-section through the representation of the Fig. 5, where the connection points 26 are visible in conjunction with the extension carrier 13. A crash energy absorber is advantageously provided in the area of ​​the connection point 26. Reference symbol list 10 Steering system 11 Steering shaft 12 Extraction sleeve tube 13 drawer slides 14 Displacement bearing zone 15 sliding bearings 16 first longitudinal section 17 Press-fit zone 18 magnetorheological brake 19 second longitudinal section 20 storage seating area 21 Steering shaft bearings 22 third longitudinal section 23 electric motor Paragraph 24 25 cable routing channels 26 Connection point 27 electric actuators 28 Intermediate zone 29 Longitudinal axis 30 End stop 31 free ending 32 cables 33 Rotation sensor

Claims

[1] Steering system (10) for a motor vehicle comprising a steering shaft (11), an extension tube (12) and an extension support (13), wherein the steering shaft (11) is rotatably mounted in the extension tube (12), wherein the extension tube (12) is longitudinally adjustable in the extension support (13), characterized by , that a magnetorheological brake (18) is arranged in the extension tube (12), which is designed to act between the extension tube (12) and the steering shaft (11), wherein the extension tube (12) has in a first longitudinal section (16) a plurality of outer sliding bearing zones (14) distributed around the circumference of the extension tube (12) for longitudinally sliding bearing of the extension tube (12) relative to the extension carrier (13) and a plurality of inner press-fit zones (17) distributed around the circumference of the extension tube (12) for retaining the magnetorheological brake (18). [2] Steering system (10) according to claim 1, characterized bythat the sliding bearing zones (14) have a flat or concave outer surface. [3] Steering system (10) according to claim 1 or 2, characterized by , that the press-fit zones (17) have a partially cylindrical, inner surface. [4] Steering system (10) according to any one of the preceding claims, characterized by , that the first longitudinal section (16) transitions in a longitudinal direction into a second longitudinal section (19), wherein at the transition of the first longitudinal section (16) into the second longitudinal section (19) radially inwardly directed shoulders (24), tabs and / or indentations are provided at the end of the press-fit zones (17). [5] Steering system (10) according to any one of the preceding claims, characterized by, that the first longitudinal section (16) transitions in a longitudinal direction into a second longitudinal section (19), wherein the sliding bearing zones (14) of the first longitudinal section (16) continue into the second longitudinal section (16), and wherein the press-in zones (17) transition into intermediate zones (28). [6] Steering system (10) according to claim 10 according to any of the preceding claims, characterized by , that the extension sleeve tube (12) has in a third longitudinal section (22) an inner cylindrical bearing seat zone (20) for a steering shaft bearing (21). [7] Steering system (10) according to any one of the preceding claims, characterized by , that at least one sliding bearing zone (14) has a connection point (26) for longitudinal adjustment of the extension sleeve tube (12) relative to the extension support (13), wherein at least one electric actuator (27) for longitudinal adjustment of the extension sleeve tube (12) relative to the extension support (13) is arranged on the extension support (13). [8] Steering system (10) according to any one of the preceding claims, characterized by , that several sliding bearings (15) for the support of the extension sleeve tube (12) are arranged on the sliding bearing zones (14) on the extension carrier (13). [9] Steering system (10) according to any one of the preceding claims, characterized by , that an electric motor (23) is arranged in the extension sleeve tube (12), which is connected to the steering shaft (11) and is configured to rotate the steering shaft (11) relative to the extension sleeve tube (12). [10] Steering system (10) according to any one of the preceding claims, characterized by , that the steering system (10) has a cable guide channel (25) formed between the extension sleeve tube (12) and the magnetorheological brake (18) for cable routing in the longitudinal direction.

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