STEERING COLUMN FOR A MOTOR VEHICLE

Abstract

An adjusting drive for a motor-adjustable steering column may include an outer threaded spindle that has an external thread that engages with a spindle nut and that has an internal thread that is engaged by an inner threaded spindle. The spindle nut, the outer threaded spindle, and the inner threaded spindle can be driven in rotation relative to one another about an axis by a motor-type drive unit. The adjusting drive may also include a blocking device that is switchable between a first position and a second position. In the first position the outer threaded spindle is locked together with the spindle nut for conjoint rotation. In the second position the outer threaded spindle is locked together with the inner threaded spindle for conjoint rotation.

Claims

1-15. (canceled)

16. An adjusting drive for a motor-adjustable steering column for a motor vehicle, comprising: an outer threaded spindle having an external thread that engages with a spindle nut, the outer threaded spindle having an internal thread that is engaged by an inner threaded spindle; a motor-type drive unit that is configured to drive the spindle nut, the outer threaded spindle, and the inner threaded spindle in rotation relative to one another about an axis; and a blocking device that is switchable between a first position and a second position, wherein in the first position the outer threaded spindle is locked together with the spindle nut for conjoint rotation, wherein in the second position the outer threaded spindle is locked together with the inner threaded spindle for conjoint rotation.

17. The adjusting drive of claim 16 wherein the blocking device interacts with the spindle nut, the outer threaded spindle, and the inner threaded spindle to be switched from the second position into the first position from a forward adjustment direction at a predetermined relative position and to be switched from the first position into the second position from a backward adjustment direction that is opposite the forward adjustment direction, at the relative position.

18. The adjusting drive of claim 16 wherein the blocking device includes a locking element that is movable between the first position and the second position.

19. The adjusting drive of claim 18 wherein the locking element is mounted movably on the outer threaded spindle and is selectively positionable in locking engagement with a locking receptacle of the spindle nut or with a locking receptacle of the inner threaded spindle.

20. The adjusting drive of claim 19 wherein the locking receptacle includes a depression formed in the spindle nut and/or in the inner threaded spindle.

21. The adjusting drive of claim 18 wherein the locking element is disposed in an aperture of the outer threaded spindle.

22. The adjusting drive of claim 18 wherein the spindle nut has a first actuating means that is configured to switch the locking element from the first position into the second position, wherein the inner threaded spindle has a second actuating means that is configured to switch the locking element from the second position into the first position.

23. The adjusting drive of claim 16 wherein the outer threaded spindle includes a delimiting means that is configured to abut in an axial direction against the spindle nut.

24. The adjusting drive of claim 16 wherein the external thread of the outer threaded spindle has a different pitch than the internal thread of the outer threaded spindle.

25. The adjusting drive of claim 24 wherein the internal thread has a greater pitch than the external thread.

26. The adjusting drive of claim 24 wherein at least one of the external thread or the internal thread is self-locking.

27. A steering column for a motor vehicle comprising the adjusting drive of claim 16, wherein the adjusting drive is at least one of: disposed between casing tubes of a casing unit that are adjustable axially relative to one another in telescopic fashion and that rotatably bear a steering spindle; or disposed between a supporting unit that is connectable to a bodyshell of the motor vehicle and a casing unit that rotatably receives a steering spindle.

28. A method for operating the adjusting drive of claim 16 wherein in a first range of adjustment the outer threaded spindle is locked together with the spindle nut for conjoint rotation and the outer threaded spindle is driven in rotation relative to the inner threaded spindle, wherein in a second range of adjustment the outer threaded spindle is locked together with the inner threaded spindle for conjoint rotation and the spindle nut is driven in rotation relative to the outer threaded spindle.

29. The method of claim 28 wherein for a transition between the first range of adjustment and the second range of adjustment the method comprises switching a locking device between a first position and a second position.

Description

DESCRIPTION OF THE DRAWINGS

[0033] Advantageous embodiments of the invention will be discussed in more detail below on the basis of the drawings. In the individual drawings:

[0034] FIG. 1 shows a steering column according to the invention in a schematic perspective view,

[0035] FIG. 2 shows an adjusting drive according to the invention of a steering column as per FIG. 1 in a schematic perspective view,

[0036] FIG. 3 shows a longitudinal section through the adjusting drive as per FIG. 2 along the axis (spindle axis),

[0037] FIG. 4 shows an enlarged detail view of FIG. 3 in a first position,

[0038] FIG. 5 shows a view as in FIG. 4 during the switch into the second position,

[0039] FIG. 6 shows a view similar to FIG. 5 in the second position.

EMBODIMENTS OF THE INVENTION

[0040] In the various figures, identical parts are always denoted by the same reference designations, and will therefore generally also be identified or mentioned only once.

[0041] FIG. 1 shows a steering column 1 according to the invention in a perspective view obliquely from the rear in relation to the direction of travel. Said steering column comprises a positioning unit 2 for the input of steering commands, which positioning unit has a casing unit 3 with three casing tubes 31, 32, 33, specifically an outer casing tube 31, an intermediate casing tube 32 and an inner tube 33. The casing tubes 31, 32 and 33 are arranged coaxially one inside the other and so as to be telescopically movable in a longitudinal direction, which corresponds to the axial direction of a longitudinal axis L, as indicated by the double arrow. Here, one adjusting direction, in which the casing tubes 31, 32, 33 are moved forward with respect to the direction of travel and collapsed into one another, that is to say are retracted, in order to shorten the positioning unit 2 into the stowage position, is referred to as the retraction direction E, which is referred to synonymously as forward adjustment direction E. Correspondingly, the adjusting direction that is opposite to this, in which the casing tubes 31, 32, 33 are moved apart in the direction of an operator control position from the stowage position, that is to say are deployed, is the deployment direction A or backward adjustment direction A, as indicated by the respective arrows.

[0042] A steering spindle 4 is mounted in the casing unit 3 so as to be rotatable about the longitudinal axis L, which steering spindle, at its rear end, has an attachment portion 41 for the attachment of a steering wheel (not illustrated). The steering spindle 4 is likewise designed to be telescopable in an axial direction for the purposes of longitudinal adjustment.

[0043] The casing unit 3 is held in a two-part supporting unit 5, which has fastening means 51 for attachment to a vehicle bodyshell (not illustrated).

[0044] An adjusting drive 6, which is shown on its own in FIG. 2, serves for the relative longitudinal adjustment of the casing tubes 31, 32 and 33 and has an inner threaded spindle 61 and an outer threaded spindle 62, which extend coaxially in the direction of an axis G, the spindle axis, and has a spindle nut 63. FIG. 3 shows a longitudinal section along said axis G, and FIGS. 4, 5 and 6 show enlarged detail views therefrom.

[0045] The outer threaded spindle 62 is designed as a tubular hollow spindle and has an external thread 620 and an internal thread 621 coaxial with respect to said external thread. The inner threaded spindle 61 has an external thread 611 by way of which said inner threaded spindle engages with the internal thread 621 and thus forms a first spindle mechanism with the outer threaded spindle 62.

[0046] The outer threaded spindle 62 is screwed by way of its external thread 620 into an internal thread 630 of the spindle nut 63, and together with the latter forms a second spindle mechanism which is nested and arranged operatively axially in series with said first spindle mechanism.

[0047] The spindle nut 63 is mounted rotatably in the housing of a drive unit 64 so as to be rotatable about the axis G and is fixedly connected to a gearwheel 65 which, for example, as in the example shown, has a toothed ring that is connected coaxially and fixedly to the spindle nut 63. The gearwheel 65 together with the spindle nut 63 can be driven in rotation about the axis G by an electric motor 66 for the purposes of realizing the motor-imparted drive of the spindle mechanisms.

[0048] The inner threaded spindle 61 is connected to the casing tube 33 fixedly with respect to rotation about the axis G, that is to say non-rotatably with respect to the adjusting drive 6.

[0049] A blocking device 7 according to the invention has a locking element which is configured as a ball 71 and which is received with play in a radial aperture 72 of the outer threaded spindle 62 and which is held so as to be movable transversely with respect to the axis G but so as to at the same time be supported axially. The aperture 72 may be configured as a circular bore with an 20 inner diameter greater than the diameter of the ball 71. The diameter of the ball 71 is dimensioned such that the ball 71 protrudes either radially inward or radially outward beyond the outer threaded spindle 62.

[0050] The inner threaded spindle 61 has, on the outside, a radial depression 74, which forms an inner locking receptacle with which the ball 71 can engage by being displaced inward, as can be seen in FIG. 4. The depression 74 is then connected in form-fitting fashion to the aperture 72 by means of the ball 71. The blocking device 7 thus assumes a second position, in which the inner threaded spindle 61 is locked together with the outer threaded spindle 62 for conjoint rotation, and connected thereto for conjoint rotation, by way of the form fit. The blocking device 7 thus assumes the second position (FIG. 4).

[0051] The spindle nut 63 has, on the inside, in the region of its internal thread 630, a radial depression 73, which forms an outer locking receptacle with which the ball 71 can engage in form-fitting fashion by being displaced outward, as can be seen in FIG. 4. The depression 73 is connected in form-fitting fashion to the aperture 72 by means of the ball 71. The blocking device 7 thus assumes a first position, in which the outer threaded spindle 62 is locked together with and connected to the spindle nut 63 for conjoint rotation by way of the form fit. The blocking device 7 thus assumes the first position (FIG. 6).

[0052] At one end, the outer threaded spindle 62 has a stop 622 in the form of a projection or collar which protrudes radially outward beyond the external thread and which can abut axially against the spindle nut 63 when the outer threaded spindle 62 has been retracted to a maximum extent in the retracting adjustment direction E (forward adjustment direction), see FIG. 6.

[0053] FIGS. 3 and 4 show, by way of example, an adjustment situation in which the steering column is situated in the comfort or operator control range in which the casing tubes 31, 32, 33 have been deployed in the longitudinal direction. If the spindle nut 63 is driven in rotation, the outer threaded spindle 62 is driven along linearly in the forward adjustment direction E. The adjustment speed is determined by the pitch of the internal thread 630 and of the corresponding external thread 620. Here, the inner threaded spindle 61 is, as shown in FIG. 4, locked by means of the locking device 7 for conjoint rotation in such a way that said inner threaded spindle is moved and adjusted linearly together with the outer threaded spindle 62.

[0054] At the end of the comfort range, the stop 622 abuts axially against the spindle nut 63 and stops the linear movement of the outer threaded spindle 62 relative to the spindle nut 63. Here, the switching position shown in FIG. 5 is reached, in which the two depressions 73 and 74 are situated radially opposite one another in the region of the aperture 72.

[0055] Thus, in the switching position, the ball 71 can move out of the inner depression 74 and, as indicated in FIG. 5 by the arrow, move outward in the aperture 72 until said ball engages in form-fitting fashion into the outer depression 73, as illustrated in FIG. 6. The locking for conjoint rotation between inner threaded spindle 61 and outer threaded spindle 62 is thus released, and the blocking device 7 is switched into a first position, in which the outer threaded spindle 62 is then locked together with the spindle nut 63 for conjoint rotation.

[0056] If the spindle nut 63 is driven in rotation further, the outer threaded spindle 62 rotates together with said spindle nut, and the inner threaded spindle 61 is adjusted linearly with respect to the outer threaded spindle. Here, the adjustment speed is determined by the pitch of the internal thread 621 and of the corresponding external thread 611. By virtue of the fact that this pitch can be greater than the pitch of the thread between outer threaded spindle 62 and spindle nut 63, it is possible, for a given rotational speed of the drive unit 64, to implement a faster adjustment in the stowage range until the front stowage position is reached.

[0057] 5 The depressions 73 and 74 may have actuating bevels that are inclined in an axial direction, such that the ball 71, as it passes through the switching position shown in FIG. 5, is automatically moved inward or outward in order to effect a switch between the first and the second position or vice versa in a manner dependent on the adjustment direction.

LIST OF REFERENCE DESIGNATIONS

[0058] 1 Steering column

[0059] 2 Positioning unit

[0060] 3 Casing unit

[0061] 31 Outer casing tube

[0062] 32 Intermediate casing tube

[0063] 33 Inner casing tube

[0064] 4 Steering spindle

[0065] 41 Attachment portion

[0066] 5 Supporting unit

[0067] 51 Fastening means

[0068] 6 Adjusting drive

[0069] 61 Inner threaded spindle

[0070] 610 External thread

[0071] 62 Outer threaded spindle

[0072] 620 External thread

[0073] 621 Internal thread

[0074] 622 Stop

[0075] 63 Spindle nut

[0076] 630 Internal thread

[0077] 64 Drive unit

[0078] 65 Gearwheel

[0079] 66 Motor

[0080] 7 Blocking device

[0081] 71 Ball (locking element)

[0082] 72 Aperture

[0083] 73, 74 Depression

[0084] L Longitudinal axis

[0085] G Axis (spindle axis)

[0086] E Forward adjustment direction (retraction adjustment direction)

[0087] A Backward adjustment direction (deployment adjustment direction)