ADJUSTMENT DRIVE FOR A STEERING COLUMN, AND STEERING COLUMN FOR A MOTOR VEHICLE

Abstract

An adjusting drive for a steering column for a motor vehicle may include a threaded spindle with an external thread that engages in a spindle nut and a drive unit that is coupled to the threaded spindle or the spindle nut such that the threaded spindle and the spindle nut are able to be rotatably driven relative to one another by overcoming a screw resistance. To permit an optimized adjustment over the entire adjusting region, the threaded spindle includes at least one actuator portion and at least one transition portion. The transition portion is configured such that the screw resistance of the spindle nut is lower in the transition portion than in the actuator portion.

Claims

1.-15. (canceled)

16. An adjusting drive for a steering column for a motor vehicle, comprising: a threaded spindle with an external thread that engages in a spindle nut, wherein the threaded spindle has an actuator portion and a transition portion; and a drive unit that is coupled to the threaded spindle or the spindle nut such that the threaded spindle and the spindle nut are able to be rotatably driven relative to one another by overcoming a screw resistance, wherein the transition portion is configured such that the screw resistance of the spindle nut is lower in the transition portion than in the actuator portion.

17. The adjusting drive of claim 16 wherein the actuator portion is disposed in an end region of the threaded spindle.

18. The adjusting drive of claim 16 wherein the actuator portion is a first actuator portion, wherein the threaded spindle comprises a second actuator portion, with the transition portion being arranged between the first and second actuator portions.

19. The adjusting drive of claim 16 wherein a thread clearance in the transition portion is greater than in the actuator portion.

20. The adjusting drive of claim 16 wherein the actuator portion includes a pretensioning element that is pretensioned against a thread of the spindle nut, wherein the transition portion is free of any pretensioning element or has a transition pretensioning element that is pretensioned against the thread of the spindle nut less than the pretensioning element is pretensioned against the thread of the spindle nut.

21. The adjusting drive of claim 20 wherein the pretensioning element is disposed in a tooth profile of a helically circulating thread tooth of the external thread.

22. The adjusting drive of claim 20 wherein the pretensioning element includes a spring element.

23. The adjusting drive of claim 20 wherein the pretensioning element includes a lubricant scraper.

24. The adjusting drive of claim 16 wherein the external thread is configured to at least one of reduce friction in the transition portion or increase friction in the actuator portion.

25. The adjusting drive of claim 16 wherein the threaded spindle includes a core element that is fixedly surrounded at least in some portions in a coaxial direction by a threaded element that comprises the external thread.

26. The adjusting drive of claim 25 wherein the threaded element is comprised of plastic.

27. The adjusting drive of claim 25 wherein the threaded element is an injection-molded part that is disposed on the core element by plastic injection-molding.

28. The adjusting drive of claim 25 wherein the core element is comprised of metal.

29. The adjusting drive of claim 25 wherein the core element includes a positive connection that is positively connected to the threaded element.

30. A steering column for a motor vehicle, comprising: a supporting unit that is attachable to a vehicle body and by which an actuating unit is held, with a steering spindle being rotatably mounted therein; and an adjusting drive that comprises: a threaded spindle with an external thread that engages in a spindle nut, wherein the threaded spindle has an actuator portion and a transition portion, and a drive unit that is coupled to the threaded spindle or the spindle nut such that the threaded spindle and the spindle nut are able to be rotatably driven relative to one another by overcoming a screw resistance, wherein the transition portion is configured such that the screw resistance of the spindle nut is lower in the transition portion than in the actuator portion.

Description

DESCRIPTION OF THE DRAWINGS

[0053] Advantageous embodiments of the invention are described in more detail hereinafter with reference to the drawings. In detail:

[0054] FIG. 1 shows a schematic perspective view of a steering column according to the invention,

[0055] FIG. 2 shows a further perspective view of the steering column according to the invention according to FIG. 1,

[0056] FIG. 3 shows an adjusting drive according to the invention in a schematic perspective view,

[0057] FIG. 4 shows an enlarged detailed view of the threaded spindle of the adjusting drive according to FIG. 3,

[0058] FIG. 5 shows a longitudinal section through the adjusting drive according to FIG. 3 along the spindle axis,

[0059] FIG. 6 shows an enlarged detailed view of FIG. 5,

[0060] FIG. 7 shows a detailed view of a second embodiment of the external thread of the threaded spindle in a view as in FIG. 4,

[0061] FIG. 8 shows a detailed view of a third embodiment of the external thread of the threaded spindle.

EMBODIMENTS OF THE INVENTION

[0062] In the various figures the same parts are always provided with the same reference numerals and thus are generally only named or mentioned once in each case.

[0063] FIG. 1 shows a steering column 1 according to the invention in a schematic perspective view from top left, obliquely to the rear end, relative to the direction of travel of a vehicle, not shown, where a steering wheel, not shown here, is held in the operating region. FIG. 2 shows the steering column 1 in a view from the opposing side, i.e. viewed from top right.

[0064] The steering column 1 comprises a jacket unit 3 which has an outer jacket tube 31, an intermediate jacket tube 32 and an inner jacket tube 33. The jacket tubes 31, 32 and 33 are axially arranged so as to be adjustable in a telescopic manner coaxially in one another in the axial direction of a longitudinal axis L, as indicated by a double arrow.

[0065] A stop 34 is attached to the outer jacket tube 31 on the rear end, said stop at the open end protruding inwardly into the intermediate space between the outer jacket tube 31 and intermediate jacket tube 32. When extended, the intermediate jacket tube 32 strikes axially against the stop 34 and is secured against separation from the outer jacket tube 31. A stop 35 protruding inwardly into the intermediate space between the intermediate jacket tube 32 and the inner jacket tube 33 is attached to the rear end of the intermediate jacket tube 32, said stop securing the inner jacket tube 33 from being pulled out of the intermediate jacket tube 32.

[0066] In the jacket unit 3 a steering spindle 37 is rotatably mounted about the longitudinal axis L, said steering spindle having a connecting portion 38 at the rear end thereof for attaching a steering wheel, not shown. The steering spindle 37 is also configured to be telescopable in the longitudinal direction, in the same manner as the jacket unit 3. An actuating unit 2 encompasses the inner jacket tube 33 together with the steering spindle 37 mounted therein. This actuating unit 2 is received so as to be displaceable in a telescopic manner in the outer jacket tube 31 in the direction of the longitudinal axis L for implementing a longitudinal adjustment relative to the jacket unit 3, in order to be able to position the steering wheel connected to the steering spindle 37 forward and back relative to the supporting unit 4 in the longitudinal direction, as indicated by the double arrow parallel to the longitudinal axis L.

[0067] The jacket unit 3 is held in a two-part supporting unit 4 which has fastening means 41 for attaching to a vehicle body, not shown.

[0068] The jacket unit 3 in its front region is pivotably mounted relative to the vehicle body about a horizontal pivot axis S located transversely to the longitudinal axis L and shown schematically. To this end, a pivot bearing, not shown, is arranged in the supporting unit 4 or between this supporting unit 4 and the vehicle body. In the rear region, the jacket unit 3 is connected via an actuating lever 42 to the supporting unit 2. By a rotational movement of the actuating lever 42 by means of an adjusting drive 6 (see FIG. 2) the jacket unit 3 may be pivoted together with the actuating unit 2 relative to the supporting unit 4 about the pivot axis S located horizontally in the installed state, whereby an adjustment of a steering wheel attached to the fastening portion 38 may be undertaken in the vertical direction H, which is indicated by the double arrow.

[0069] A first adjusting drive 5 for the longitudinal adjustment of the actuating unit 2 relative to the jacket unit 3 in the direction of the longitudinal axis L has a spindle drive with a spindle nut 51 with an internal thread 74 extending along a spindle axis G, in which a threaded spindle 52 engages, i.e. is screwed with its external thread in the corresponding internal thread 74 of the spindle nut 51. The threaded spindle axis of the threaded spindle 52 is identical to the spindle axis G and runs substantially parallel to the longitudinal axis L.

[0070] The spindle nut 51 is rotatably mounted about the spindle axis G in a bearing housing 53 which is fixedly connected to the outer jacket tube 31 of the jacket unit 4. In the direction of the spindle axis G, the spindle nut 51 is axially supported via the bearing housing 53 on the jacket unit 4. The adjusting drive 5 is accordingly a so-called plunger spindle drive.

[0071] The threaded spindle 52 is connected to the inner jacket tube 33 and supported fixedly in terms of rotation and axially fixedly at its free end on an arm 36, and the spindle nut 51 is axially supported via the drive unit 53, i.e. in the longitudinal direction, on the outer jacket tube 31. The longitudinal direction corresponds to the direction of the longitudinal axis L. By a relative rotation by means of the motor 55, which is configured as an electric motor, the threaded spindle 52 and the spindle nut 51 are moved together or apart depending on the rotational direction, whereby the inner jacket tube 33 is axially retracted into the intermediate jacket tube 32 and this intermediate jacket tube is retracted or extended into the outer jacket tube 31, as indicated by the double arrow. As a result, a steering wheel which may be attached to the connecting portion 38 may be moved to the front into a stowed position, in which the inner jacket tube 33 and the intermediate jacket tube 32 are retracted into the outer jacket tube 31, i.e. immersed at the front, or extended into an operating position in the operating region in which the jacket tubes 31, 32 and 33 are extended out of one another in a telescopic manner.

[0072] In FIG. 2 which shows a perspective view of the steering column 1 from the side located to the rear in FIG. 1, it may be identified how a second adjusting drive 6 is attached to the steering column 1 for adjusting in the vertical direction H. This adjusting drive 6 is constructed in principle to act in the same manner as the adjusting drive 5. This adjusting drive also comprises a spindle nut 61, a threaded spindle 62 engaging in the internal thread thereof along a spindle axis G. The threaded spindle 62 is mounted in a bearing housing 63, which is fastened to the jacket unit 3, rotatably about the axis G and axially supported in the direction of the axis G on the jacket unit 3, and is able to be driven by an electric drive motor 65 selectively in both rotational directions about the axis G.

[0073] In the embodiment shown, the adjusting drives 5 and 6 are so-called plunger spindle drives. Alternatively, a rotary spindle drive may also be configured, in which the spindle nut 51 is held relative to rotation on the steering column 1 and the threaded spindle 52 is able to be rotatably driven by the motor 55.

[0074] The adjusting drive 6 acts on the end of the two-arm actuating lever 42 which is rotatably mounted on the supporting unit 4 about a pivot bearing 43, and the other arm thereof is connected to the jacket unit 3 by the other end in a further pivot bearing 44.

[0075] The adjusting drive 5 is shown individually in FIG. 3 in a perspective view and in FIG. 5 in a longitudinal section along the spindle axis G.

[0076] The threaded spindle 52 according to the invention has a preferably tubular core element 57, preferably made of steel tube, on which coaxially a sleeve-shaped threaded element 58 is unreleasably attached, said threaded element having the external thread with a helically encircling thread tooth 581, and being able to be injection-molded by plastics injection-molding.

[0077] For forming a coupling element 54, which serves as such, the tube of the core element 57 is crimped flat, transversely to the spindle axis G, preferably by cold forming, and has a continuous fastening bore 541 perpendicular to the crimping. A fastening bolt 542 is guided through this fastening bore 541 for connecting fixedly in terms of rotation to the transmission element 34, as may be identified in FIG. 1.

[0078] At the end remote from the fastening element 54, the core element 57 has a stop element 571 which is configured as a radially outwardly protruding peripheral collar, preferably by widening the tubular core element 57 by cold forming.

[0079] At its end facing the fastening element 54, the threaded element 58 also has a stop element 580 which is configured as a peripheral projection or collar, which is configured in one piece with the threaded element by plastics injection-molding.

[0080] According to the invention the threaded spindle 52 has a first actuator portion A which, as may be identified in FIG. 3, extends over a longitudinal portion of the external thread. The actuator portion A is located in an end region of the threaded spindle. A longitudinal portion configured as a transition portion B adjoins thereto. Arranged at the other end region of the threaded spindle 52, opposing the actuator portion A, is a second actuator portion C which in principle may be configured in the same manner, wherein the lengths of the actuator portion A and the actuator portion C may be different. Hereinafter, therefore, only the actuator portion A is referred to.

[0081] The threaded element 58 has an axially continuous flattened portion 582 of the external thread, which may be identified clearly in FIG. 4, which shows an enlarged detail of FIG. 3. In the region of this flattened portion 582, the thread tooth 581 in each peripheral portion has a gap in which in each case a pretensioning element 59 is configured in the actuator portion A. The pretensioning elements 59 in the first embodiment of FIG. 4 are configured as radially protruding projections, pads or blocks which in the axial direction (longitudinal direction) may be slightly wider than the peripheral cross section of the thread tooth 581, i.e. wider than the axial width of the thread tooth 581. The pretensioning elements 59 may preferably be configured in one piece by plastics injection-molding with the threaded element 58. By elastic deformation of the plastics material, the pretensioning elements 59 may be resiliently pretensioned or tensioned without clearance in the thread of the internal thread of the spindle nut 51. Pretensioning elements 59 are also arranged in the second actuator portion C, said pretensioning elements being able to be configured to act in the same manner as those in the actuator portion A.

[0082] According to the invention, no pretensioning elements 59 are arranged in the transition region B in the embodiment shown, in other words the transition portion B is configured without pretensioning elements. The gap formed by the flattened portion 582 remains free. This is also able to be identified in the enlarged sectional view of FIG. 6. In the region of the flattened portion 582 the pretensioning elements 59 engage with axial pretensioning in the threads of the internal thread 74 of the spindle nut 61, whereby the threaded spindle 52 is pretensioned in the spindle nut 51. This results in an increased screw resistance, which is greater than in the transition region B in which there is no tensioning or less tensioning due to the lack of pretensioning elements there.

[0083] In FIGS. 7 and 8 further variants of pretensioning elements 59 are shown. The threaded element 58 has in turn at least one, preferably two, opposing flattened portions 582, in which the thread tooth 581 has a gap in the peripheral portion. In the second embodiment of FIG. 7, each pretensioning element 59 has two radially protruding leaf-shaped or finger-shaped spring elements 591 axially spaced apart in the direction of the threaded spindle axis G and in the peripheral direction. These spring elements are able to be elastically bent in the axial direction and in the undeformed state protrude slightly axially over the cross section of the thread tooth 581. As a result, in the screwed-in state in each case they are tensioned in a thread between the thread flanks in the internal thread of the spindle nut 51.

[0084] The embodiment shown in a lateral (radial) view in FIG. 8 is configured in a similar manner, wherein each spring element 591 is configured as Z-shaped spring leaf, in which the spring elements 591 in pairs in FIG. 7 are combined in one piece.

[0085] All of the embodiments of the spring elements 59, 591 may be configured in one piece on the threaded element 58 by plastics injection-molding. Due to their dimensions, the resilience and the spring force exerted for the pretensioning may be adapted and predetermined, if required. As a result, the size of the screw resistance in the actuator portion A and C may be predetermined in a defined manner.

[0086] The free space between the spring elements 591 may be used as a lubricant pocket.

[0087] The pretensioning elements 59, 591 may be combined together in any manner. For example, the actuator portions A and C may have pretensioning elements 59, 591 which are different from one another. It is also conceivable and possible that different pretensioning elements 59, 591 may be combined in one actuator portion A, C.

[0088] Due to the pretensioning elements 59, 591 an elastic tensioning of the threaded spindle 52 may be generated without clearance in the spindle nut 51, when the spindle nut is located in one of the actuator regions A or C, which correspond to the operating region or the stowing region of the steering column. When stowed, the spindle nut 51 is moved out of the actuator region A. When passing the transition region B the screw resistance due to the lack of tensioning is lower and a greater adjusting speed may be implemented with the same drive power. When reaching the second actuator region C, an increased screw resistance acts once again in the vicinity of the stowed position, as in the actuator region A. A stowage which is safe and without clearance may be carried out at lower adjusting speed. The sequence is correspondingly reversed during deployment from the actuator region C to the actuator region A.

[0089] For the rotating drive by the motor 55, a gear wheel 7 may be attached coaxially on the spindle nut 51, as may be identified in FIGS. 5 and 6. The gear wheel 7 may be, for example, a worm wheel which is in engagement with a worm shaft driven by the motor 55. Alternatively to the design of a plunger spindle drive shown in FIGS. 3 to 6, in which the spindle nut 51 is rotatably driven, in the design of a rotary spindle drive the threaded spindle 52 may be rotatably driven relative to the gear housing 53. Then the gear wheel 7 is fastened fixedly in terms of rotation and coaxially to the threaded spindle 52.

[0090] The gear wheel 7 may preferably be configured from plastics, and preferably injection-molded by plastics injection-molding on the spindle nut 51 or the threaded spindle 52.

LIST OF REFERENCE NUMERALS

[0091] 1 Steering column

[0092] 2 Actuating unit

[0093] 21 Fastening means

[0094] 22, 23 Pivot bearing

[0095] 3 Jacket unit

[0096] 31 Outer jacket tube

[0097] 32 Intermediate jacket tube

[0098] 33 Inner jacket tube

[0099] 34, 35 Stop

[0100] 36 Arm

[0101] 37 Steering spindle

[0102] 38 Connecting portion

[0103] 4 Supporting unit

[0104] 41 Fastening means

[0105] 42 Actuating lever

[0106] 43, 44 Pivot bearing

[0107] 5, 6 Adjusting drive

[0108] 51, 61 Spindle nut

[0109] 52, 62 Threaded spindle

[0110] 53, 63 Bearing housing

[0111] 54 Coupling element

[0112] 541 Fastening bore

[0113] 542 Fastening bolt

[0114] 55, 65 Drive motor

[0115] 57 Core element

[0116] 571 Stop element

[0117] 58 Threaded element

[0118] 580 Stop element

[0119] 581 Thread tooth

[0120] 582 Flattened portion

[0121] 583 Lubricant pocket

[0122] 59 Pretensioning element

[0123] 591 Spring element

[0124] 7 Gear wheel

[0125] 74 Internal thread

[0126] A, C Actuator portion

[0127] B Transition portion

[0128] L Longitudinal axis

[0129] S Pivot axis

[0130] H Vertical direction

[0131] G Spindle axis (threaded spindle axis)