STEERING COLUMN FOR A MOTOR VEHICLE

Description

State of the art

[0001] The invention relates to a steering column for a motor vehicle, comprising a casing unit in which a steering spindle is mounted so as to be rotatable about a longitudinal axis running in the longitudinal direction, and which has at least one inner casing which is telescopically adjustable in the longitudinal direction in an outer casing tube, comprising a roller guide with at least one bearing carrier which is radially supported and displaceable on the inner casing, and in which at least one roller is mounted so as to be rotatable about a roller axis lying transversely to the longitudinal axis, and the roller can roll with its outer circumference on the inside of the casing tube in the longitudinal direction, wherein a pretensioning device cooperates with the bearing carrier in order to pretension the roller radially against the casing tube.

[0002] To input manual steering commands, a steering wheel or other manual steering handle is attached to the rear end of the steering spindle in the direction of travel, facing the driver. The spindle is mounted in a sleeve unit of the steering column so that it can rotate about its longitudinal axis. The sleeve unit has an outer sleeve tube, for example an outer sleeve held on the body or an intermediate sleeve accommodated therein. In this outer sleeve tube, an inner sleeve, in which the steering spindle is mounted, is accommodated so that it can telescopically adjust in the longitudinal direction defined by the longitudinal axis. The outer sleeve tube is held to the vehicle body by a support unit. By pushing the inner sleeve in or pulling it out relative to the outer sleeve tube, a longitudinal adjustment can be made to adapt the steering wheel position.

[0003] Simple telescopic arrangements are known which comprise the casing tube and the inner casing as telescopic elements, and also triple or multiple telescopic arrangements in which the casing tube is telescopically received in an outer casing or in one or more further casing tubes.

[0004] In order to enable smooth and low-backlash adjustment, it is known to provide a linear roller guide between the inner shell and the casing tube, as described, for example, in DE 10 2022 201 101 B3. This comprises a roller that is rotatably mounted relative to the inner shell about its roller axis lying transversely to the longitudinal axis and that can roll longitudinally on the inside of the casing tube. To ensure backlash-free rolling, the roller is mounted in a bearing carrier so that it can be displaced radially outwards relative to the inner shell. The bearing carrier is urged radially outwards by a preload device so that the radial preload can hold the roller in backlash-free rolling contact with the inside of the casing tube.

[0005] The well-known telescopic arrangement enables smooth, backlash-free adjustment with high rigidity. However, because the preload element is effectively axially aligned and supported, a relatively large axial length may be required. This can make adaptation to the available installation space difficult.

[0006] In view of the problems explained above, it is an object of the present invention to enable improved adaptation to an existing installation space. Description of the invention

[0007] This object is achieved according to the invention by the steering column having the features of claim 1. Advantageous further developments emerge from the subclaims.

[0008] In a steering column for a motor vehicle, comprising a casing unit in which a steering spindle is rotatably mounted about a longitudinal axis extending in the longitudinal direction, and which has at least one inner casing which is telescopically adjustable in the longitudinal direction in an outer casing tube, comprising a roller guide with at least one bearing carrier which is radially supported and displaceable on the inner casing, and in which at least one roller is rotatably mounted about a roller axis lying transversely to the longitudinal axis, and the roller can roll with its outer circumference on the inside of the casing tube in the longitudinal direction, wherein a pretensioning device cooperates with the bearing carrier in order to pretension the roller radially against the casing tube, the invention provides that the pretensioning device has wedge surfaces which are formed on the bearing carrier and a clamping wedge and which are inclined against a circumferential direction,wherein the clamping wedge is loaded relative to the bearing carrier in the circumferential direction by a clamping element.

[0009] The circumferential direction corresponds to the axial direction of the roller axis. The wedge surfaces are formed on the bearing support and / or on the clamping wedge and arranged such that they converge in the circumferential direction, which is directed from the clamping wedge toward the bearing support. The direction in which the wedge surfaces converge is also referred to as the wedge direction. If the clamping wedge is loaded by the clamping element in this wedge direction onto the bearing support, the bearing support is forced radially outward transversely to the circumferential direction by the wedge effect.

[0010] According to the invention, the clamping wedge is displaceable relative to the bearing support in the circumferential direction and is driven in its wedging direction between the bearing support and the inner casing such that a preload force transverse to the wedge direction and directed radially outward relative to the longitudinal axis is exerted on the bearing support via the wedge surfaces. The wedge arrangement or wedge device formed by the clamping wedge and the bearing support thus redirects the clamping force exerted in the circumferential direction by the clamping element on the clamping wedge. This force acts as a radially outward preload force on the bearing support and presses the roller in rolling contact from the inside against the outer casing tube.

[0011] The axial length of the preloading device according to the invention can be determined essentially by the longitudinal width of the clamping wedge and the bearing support. Because this dimension can be designed relatively freely and dimensioned accordingly, an advantageously smaller installation space and a shorter installation length are possible than in the prior art.

[0012] A further advantage is that the force transmission ratio between the clamping force applied by the clamping element to the clamping wedge in the circumferential direction and the radial preload force thus exerted on the roller can be determined in a structurally simple manner by the wedge angle enclosed between the wedge surfaces. A relatively flat, i.e., acute, wedge angle results in a high force transmission. The wedge angle can preferably be in a range between 5° and 30°, particularly preferably around 15°.

[0013] It is preferably provided that the clamping element comprises a spring element. The spring element forms a force-generating element that exerts an elastic clamping force on the clamping wedge in the circumferential direction, which, via the wedge device, elastically loads the roller in rolling contact. This ensures a uniform preload in a structurally simple and permanently reliable manner.

[0014] It is advantageous if the clamping wedge is guided on the inner casing in the circumferential direction and supported radially inwards. The circumferential guidance ensures reliable function of the wedge device under high loads, for example with high transverse forces. Because the clamping wedge is supported on the inner casing in the radial direction transverse to its wedge direction radially inwards, towards the longitudinal axis, the bearing carrier is pressed radially outwards in a defined manner when the clamping wedge is driven in the wedge direction by the clamping element between the bearing carrier and the inner casing. The guidance in the circumferential direction and the radial support can be implemented in a simple design using a sliding guide, for example a grooved guide in which the clamping wedge can slide along in the circumferential direction.

[0015] It is preferably possible for the clamping element to be arranged in the circumferential direction between an abutment of the inner casing and the clamping wedge. The clamping element, as a force-generating element, exerts a clamping force in the circumferential direction on the clamping wedge. It can comprise a compression spring, for example a coil spring, a disc spring assembly, or the like. The abutment and the clamping wedge are opposite one another in the circumferential direction, with the clamping element preferably being inserted between them under preload. For example, a compression spring can be inserted so far that the resilient restoring force corresponds to the required clamping force. The abutment can be designed in a simple manner on the inner casing, for example in the form of a radial surface, which can also be formed in a recess.

[0016] It can preferably be provided that two clamping wedges lie opposite one another in the circumferential direction and interact with corresponding wedge surfaces of the bearing support. The two clamping wedges point towards one another with their opposite wedge directions in the circumferential direction. The wedge arrangement can preferably be mirror-symmetrical to a radial plane that is perpendicular to the circumferential direction between the clamping wedges and in which the longitudinal axis lies. The corresponding wedge surfaces on the bearing support are at an obtuse angle to one another, the apex of which points inward toward the longitudinal axis. This symmetrical arrangement is advantageous for generating a uniform radial preload force.

[0017] In the aforementioned embodiment, it is advantageously possible for each of the two clamping wedges to be supported in a circumferentially preloaded manner against an abutment on the inner casing via a clamping element, for example, a spring element such as a compression spring or the like. The wedge device formed by the two clamping wedges and the bearing support can thus be held elastically in a quasi-floating manner in the circumferential direction between the two clamping elements. This allows external forces, for example, due to load changes or the like, to be absorbed elastically and without jamming by the roller guide.

[0018] It can be provided that the bearing carrier is guided along guide surfaces of the inner casing. For example, the bearing carrier can slide along the guide surfaces with at least one radially directed movement component of the guide. This provides a defined displacement of the bearing carrier relative to the inner casing along a radial guideway when the clamping wedge is driven in the circumferential direction between the inner casing and the bearing carrier. The bearing carrier can be guided, for example, in a sliding guide such that the preload force is introduced into the rollers in the direction defined by the guide.

[0019] It can preferably be provided that the bearing support is arranged in an opening in the inner shell. The opening can be designed as an outwardly through-opening or as a recess in the outer side of the inner shell. The opening can have guide surfaces on which the bearing support is guided in the radial direction. Furthermore, the opening can have abutments for supporting the clamping element(s) and / or the clamping wedge(s) in the circumferential direction, and / or for radially supporting the clamping wedge(s). In the circumferential direction, the opening or recess preferably extends over an angular section of less than 90°.

[0020] It can preferably be provided that the roller is arranged in a preload plane perpendicular to the longitudinal axis, in which at least two fixed support rollers are arranged distributed over the circumference. In the preload plane, the roller preloaded according to the invention and at least two support rollers, each mounted in a radially fixed bearing, are thus mounted on the inner casing distributed over the circumference. The preload force introduced into the preloaded roller also presses the support rollers against the outer casing tube from the inside. Preferably, exactly two support rollers spaced apart in the circumferential direction can be arranged in a circumferential region opposite the preloaded rollers with respect to the longitudinal axis. This creates a three-roller bearing in one preload plane, which is advantageous in terms of high rigidity and functional reliability.

[0021] Preferably, a mirror-symmetrical arrangement of the roller and the support rollers can be realized with respect to a radial plane between the rollers.

[0022] It is possible for the roller to be rotatably mounted in the bearing carrier in a plain bearing. The roller can be rotatably mounted on an axle, such as a bearing pin, which is housed in the bearing carrier. The plain bearing has the advantage of high rigidity and a high natural frequency of the bearing arrangement.

[0023] Alternatively, the roller can be rotatably mounted in the bearing carrier in a rolling bearing. The roller can be rotatably mounted on an axle, such as a bearing pin or the like, which is housed in the bearing carrier, via rolling elements that roll around the entire circumference, such as a needle roller and cage. Such a rolling bearing has the advantage of low bearing friction, which facilitates easy adjustment.

[0024] It is possible for the inner casing to have a polygonal outer cross-section. The inner casing can be designed as a polygonal profile with a polygonal cross-section and at least one polygonal outer profile, for example as a square, hexagon, eight, ten, or twelve-sided profile. The through-section of the outer casing tube, in which the inner casing is telescopically accommodated, corresponds to its polygonal outer profile. The rollers can roll between the edges on the preferably flat side surfaces of the polygonal profile, whereby the rolling contact between the rollers and the casing tube is wider than with a circular cross-section, which is advantageous in terms of high rigidity and lower surface pressure. A further advantage is the clearly defined, torsion-proof arrangement of the inner casing in the casing tube.

[0025] It can further be provided that the jacket tube is telescopically accommodated in an outer jacket. In this way, a multiple telescopic arrangement with at least three telescopic elements can be provided: the inner jacket, the jacket tube, and the outer jacket. Additional jacket tubes can be inserted between them if necessary. Multiple telescopic arrangements allow for a greater ratio between the maximum shortened and the maximum extended adjustment state of the steering column. Description of the drawings

[0026] Advantageous embodiments of the invention are explained in more detail below with reference to the drawings. In detail: Figure 1 shows a steering column according to the invention in a schematic perspective view, Figure 2 shows the steering column according to Figure 1 in a view from above, Figure 3 a section BB through the steering column according to Figure 1 , Figure 4 an enlarged detail view from Figure 3, Figure 5the inner casing of the steering column according to Figure 1 in a free-standing schematic perspective view, Figure 6 the inner casing of the steering column according to Figure 1 in another isolated schematic perspective view similar Figure 5 , Figure 7 a schematically isolated partial view of a pretensioning device according to the invention, Figure 8 a further view of a pretensioning device according to Figure 7 . Embodiments of the invention

[0027] In the various figures, identical parts are always provided with the same reference symbols and are therefore usually named or mentioned only once.

[0028] Fig. 1 shows a steering column 1 according to the invention with respect to the direction of travel in a side view, wherein the direction of travel points to the right. Figure 2 shows a view from above. In Figure 3 is a cross section BB of Figure 2 shown in Figure 3is shown in an enlarged detail.

[0029] The steering column 1 has a casing unit 2 comprising an outer casing 21 and an outer casing tube 22 accommodated therein for telescopic adjustment in the longitudinal direction of a longitudinal axis L, and an inner casing 23 accommodated in the casing tube 22 for telescopic adjustment in the longitudinal direction, as indicated by the double arrow. The outer casing 21, the casing tube 22, and the inner casing 23 can also be collectively referred to as the telescopic elements 21, 22, 23.

[0030] In the example shown, the casing tube 22 is designed as a polygonal hollow profile, specifically as a 12-edge tube. The inner casing 23 accommodated therein has a corresponding 12-edge outer cross-section.

[0031] In the casing unit 2, a steering spindle 3 is mounted so as to be rotatable about the longitudinal axis L. At an end section which is at the rear with respect to the direction of travel and is directed towards the driver's position in the installed position, the steering spindle 3 has a connecting section 31 for attaching a manual steering handle (not shown here), for example a steering wheel.

[0032] The jacket unit 2, specifically the outer jacket 21, is held by a support unit 4, which can be attached to a vehicle body not shown here.

[0033] Between the inner casing 21 and the outer casing 23, an electromotive adjustment drive 5 is arranged, which is designed as a spindle drive. This comprises a drive unit 51 fixed to the outer casing 23, which has a spindle nut - not explicitly shown here - which can be driven by an electric motor to rotate about its threaded axis, and into which a threaded spindle 52 engages. With its free end, the threaded spindle 52 is connected to the inner casing 23 in a rotationally fixed and longitudinally fixed manner. By rotating the spindle nut, the threaded spindle 52 can be moved forwards or backwards relative to the drive unit 51, depending on the direction of rotation, as indicated by the double arrow in Figure 1 is indicated. This allows the inner casing 23 and the casing tube 22 to be telescopically extended or retracted in the longitudinal direction relative to the outer casing 21.

[0034] A roller guide 8, which is in Figures 3 and 4, comprises a roller 81, which is rotatably mounted in a bearing support 83 about a roller axis 82 arranged transversely to the longitudinal axis. The bearing support 83 is supported on the inner casing 23 and is radially displaceable relative thereto. The roller 81 is preloaded radially outwardly against the inside of the casing tube 22 in rolling contact, as will be explained below.

[0035] A pretensioning device 9 according to the invention cooperates with the bearing support 83. This device has two clamping wedges 91, each of which has wedge surfaces 92 inclined relative to the circumferential direction, which corresponds to the axial direction of the roller axis 82. These wedge surfaces converge in the wedge direction K. The wedge directions K of the two clamping wedges 91 are directed relative to each other in the circumferential direction, as shown in Figure 4 is indicated by the arrows drawn into the clamping wedges 91.

[0036] The wedge surfaces 92 of the clamping wedges 91 slide against corresponding wedge surfaces 84 on the bearing carrier 83.

[0037] Each of the two clamping wedges 91 is supported in the circumferential direction against an abutment 27 on the inner casing 23 by a spring element 94, in the example a helical spring designed as a compression spring. At the other end, each spring element 94 is resiliently clamped in the circumferential direction against one of the clamping wedges 91. This applies an elastic clamping force to the clamping wedges 91 in the opposing wedge directions K - indicated by arrows. This drives the clamping wedges 91 in the circumferential direction between the outer side of the inner casing 32 and the wedge surfaces 84 of the bearing carrier 83. The latter is thereby forced radially outwards by the wedge effect, as shown in Figure 4is indicated by the upwardly directed arrow drawn into the roller 81, which indicates the preload force F with which the roller 81 is pressed in rolling contact against the inside of the casing tube 22.

[0038] The described generation and application of the preload force F is further illustrated by the schematic representations of the preload device 9. This shows how the clamping force (spring force) exerted in opposite wedge directions K by the spring elements 94 on the clamping wedges 91 is transmitted via the corresponding wedge surfaces 92 and 84 to the bearing support 83 and converted into a radial preload force F of the roller 81.

[0039] The cross section BB according to Figure 3 defines a prestressing plane. The axially offset arrangement of two prestressing devices 9 according to the invention on the inner shell 23 in two axially spaced prestressing planes is shown in Figure 5which are both designated BB because of their essentially similar design.

[0040] In addition to the roller 81 pre-tensioned according to the invention, the roller guide 8 has two support rollers 85 mounted on the inner casing 23 so as to be rotatable about fixed axes 86, which can also roll longitudinally on the inside of the casing tube 22. The support rollers 85 are arranged symmetrically on the circumference relative to the roller 81, offset by 120° in the example shown. Preferably, two support rollers 85 can be arranged together with a pre-tensioned roller 81 in a pre-tensioning plane BB, as shown in the Figures 5 and 6 is indicated. List of reference symbols

[0041] 1Steering system 2Shell unit 21Outer shell 22Shell tube 23Inner shell 27Abutment 3Steering spindle 31Connecting section 4Support unit 5Adjustment drive 51Drive unit 52Threaded spindle 8Roller guide 81Roller 82Roller axle 83Bearing carrier 84Wedge surface 85Support roller 86Axle 9Pre-tensioning device 91Clamping wedge 92Wedge surface 94Spring element LLongitudinal axis KKedge direction FPrestressing force B-BPrestressing plane

Claims

1. Steering column (1) for a motor vehicle, comprising a casing unit (2), in which a steering spindle (3) is mounted so as to be rotatable about a longitudinal axis (L) running in the longitudinal direction, and which has at least one inner casing (23) telescopically adjustable in the longitudinal direction in an outer casing tube (22), comprising a roller guide having at least one bearing support (83), which is radially supported and movable on the inner casing (23), and in which at least one roller (81) is mounted so as to be rotatable about a roller axis (82) which is transverse to the longitudinal axis (L), and the roller (81) can be rolled in the longitudinal direction with its outer circumference against the inside of the casing tube (22), wherein a preloading device (9) interacts with the bearing support (83) in order to preload the roller (81) radially against the casing tube (22), characterized in that the preloading device (9) has interacting wedge surfaces (84, 92) on the bearing support (83) and a biasing wedge (91), which surfaces are inclined with respect to a circumferential direction, wherein the biasing wedge (91) is loaded in the circumferential direction relative to the bearing support (83) by a biasing element (94).

2. Steering column according to Claim 1, characterized in that the biasing element (94) comprises a spring element.

3. Steering column according to any one of the preceding claims, characterized in that the biasing wedge (91) is guided in the circumferential direction on the inner casing (23) and is supported radially inwards.

4. Steering column according to any one of the preceding claims, characterized in that the biasing element (94) is arranged between an abutment (27) of the inner casing (23) and the biasing wedge (91) in the circumferential direction.

5. Steering column according to any one of the preceding claims, characterized in that two biasing wedges (91) lie opposite one another in the circumferential direction and interact with respective corresponding wedge surfaces (84) of the bearing support (83).

6. Steering column according to any one of the preceding claims, characterized in that the bearing support (83) is guided on guide surfaces of the inner casing (23).

7. Steering column according to any one of the preceding claims, characterized in that the bearing support (23) is arranged in an aperture of the inner casing (23).

8. Steering column according to any one of the preceding claims, characterized in that the roller (81) is arranged in a preloading plane (A-A) perpendicular to the longitudinal axis (L), in which at least two fixed supporting rollers (85) are arranged in a manner distributed over the circumference.

9. Steering column according to any one of the preceding claims, characterized in that the roller (81) is rotatably mounted in a plain bearing in the bearing support (83).

10. Steering column according to any one of the preceding claims, characterized in that the roller (81) is rotatably mounted in a rolling bearing in the bearing support (83).

11. Steering column according to any one of the preceding claims, characterized in that the inner casing (23) has a polygonal outer cross section.

12. Steering column according to any one of the preceding claims, characterized in that the casing tube (23) is accommodated telescopically in a further outer casing (21).