Adjustment drive for a motor-adjustable steering column and steering column for a motor vehicle

Abstract

The invention relates to a motor-adjustable adjusting drive (5) for a motor vehicle steering column (1), comprising a spindle unit (6) having a lead screw (62) with a spindle axis (S) which engages into a spindle nut (61), and a drive unit (7) having a drive wheel (81) which can be driven by an electric motor (71) to rotate about a drive axis (A), the drive wheel being configured as a belt wheel, wherein a transmission wheel (82) which is coupled in a driving manner to the drive wheel (81) via a looped belt (83) is connected to the spindle nut (61) or the lead screw (62). In order to be able to achieve improved operating characteristics, the invention proposes that a pretensioning device is arranged between the drive unit (7) and the spindle unit (6).

Description

TECHNICAL FIELD

[0001] The invention relates to a motor-adjustable steering column adjustment drive for a motor vehicle, comprising a spindle unit having a screw spindle with a spindle axis which engages into a spindle nut, and a drive unit having a drive wheel which can be driven in rotation about a drive axis by an electric motor, the drive wheel being configured as a belt pulley, wherein a transmission wheel which is coupled in a driving manner to the drive wheel by means of a surrounding belt is connected to the spindle nut or to the screw spindle. A steering column having such an adjustment drive is likewise the subject of the invention. BACKGROUND

[0002] A steering column for a motor vehicle has a steering shaft which has a steering spindle to which a steering wheel is attached at a driver-facing rear end in the direction of travel for the introduction of steering commands by the driver. The steering spindle is mounted in a rotationally fixed manner about its longitudinal axis in a servo unit which is held on the vehicle body by a support unit. A longitudinal adjustment can be carried out by the servo unit being accommodated in a telescopable manner in a housing unit, also referred to as a guide box or a box-shaped swing arm, which is connected to the support unit. A height adjustment can be achieved by the servo unit or the housing unit accommodating the servo unit being supported in a pivotable manner on the support unit in the height direction. An adjustment of the servo unit in the longitudinal direction or in the height direction enables the setting of an ergonomic, comfortable steering wheel position in relation to the driver's position in the operating state, also referred to as the driving or operating position, in which manual steering interventions can be carried out.

[0003] It is known from the prior art that, for the adjustment of the servo unit relative to the support unit, a motor-adjustable adjustment drive having a drive unit is provided, the drive unit comprising an electric motor which is connected to a spindle drive, the spindle drive comprising a spindle unit having a screw spindle which is screwed into a spindle nut, the screw spindle extending in the direction of the spindle axis. By means of the drive unit, the screw spindle and the spindle nut can be driven in rotation relative to one another about the spindle axis, as a result of which the screw spindle and the spindle nut can be moved translationally towards or away from one another depending on the direction of rotation. In one embodiment, the screw spindle is driven in rotation by the drive unit which is fixedly connected to the servo unit or to the support unit, and engages into the spindle nut which is fixedly mounted in terms of rotation about the screw spindle axis to the support unit or, alternatively, to the servo unit. In the direction of the screw spindle axis, the screw spindle is supported on the support unit or on the servo unit, and the spindle nut is correspondingly supported on the servo unit or, alternatively, on the support unit, so that a rotational drive of the screw spindle results in a translational adjustment of the support unit and the servo unit relative to one another in the direction of the screw spindle axis. This embodiment is also referred to as a rotational spindle drive.

[0004] In an alternative embodiment, the spindle is non-rotatably coupled with respect to its rotation about the spindle axis to the support unit or alternatively to the servo unit and the spindle nut is rotatable but is correspondingly fixedly supported in the direction of the spindle axis on the servo unit or alternatively on the support unit. As in the first embodiment, in the direction of the spindle axis the spindle is supported on the support unit or on the servo unit and the spindle nut is correspondingly supported on the servo unit or on the support unit, such that the spindle can be moved translationally in the direction of the spindle axis in such a way that the spindle nut is driven rotationally by the drive unit. This embodiment is referred to as a sink-in spindle drive.

[0005] By rotational driving of the spindle, as in the first described embodiment, an adjustment of the translation of the support unit and the servo unit relative to one another in the direction of the spindle axis is produced. In both embodiments, the spindle drive constitutes a motor adjustment drive acting between the support unit and the servo unit, by means of which the servo unit can be adjusted relative to the support unit.

[0006] In adjustment drives of the type mentioned at the outset, the spindle drive is driven by means of a belt drive, wherein a drive wheel, which can be driven in rotation about a drive axis by a motor, is configured as a belt wheel, which is coupled in a drive manner by means of a looped belt to a transmission wheel, which is also configured as a belt wheel and is rotatable about the spindle axis, the transmission wheel being connected in a torque-proof manner to the spindle nut or to the spindle depending on the embodiment of the spindle drive. Such a belt-driven adjustment drive is known, for example, from DE 10 2017 218 894 Al. The advantage of such a belt drive is a high smoothness of operation and a relatively low weight. However, due to tolerances during assembly and during operation, the belt tension can change, which can lead to drive slip and operating noise. SUMMARY

[0007] The object of the present application is to achieve an improved operating behavior of the adjustment drive.

[0008] According to the application, this object is achieved by the adjustment drive and the steering column according to the application.

[0009] An adjustment drive for a motor-adjustable steering column of a motor vehicle, comprising a spindle unit having a spindle with a spindle axis engaged in a spindle nut and a drive unit having a drive wheel which can be driven in rotation about a drive axis by an electric motor, the drive wheel being configured as a belt wheel, wherein a transmission wheel which is coupled in a drive manner via a looped belt to the drive wheel is connected to the spindle nut or to the spindle, it is provided according to the application that a pretensioning device is arranged between the drive unit and the spindle unit.

[0010] The pre-tensioning device according to the application constitutes a belt tensioning device which, in interaction with a drive unit and a spindle unit, exerts a pre-tensioning force in order to exert a defined belt tension on the belt. The belt tension can thus be predetermined and kept within an optimum range throughout the entire service life, substantially independently of component and assembly tolerances and variations in operating conditions. Correspondingly, the running smoothness can be improved in an advantageous manner and the operating safety is improved.

[0011] A further advantage is that the installation can be simplified and the functional requirements on the belt drive can be reduced, so that, for example, simple flat belts or wedge belts can be used without the occurrence of undesirable drive slip as a result of too low a belt tension.

[0012] Advantageously, the pre-tensioning device is configured to push the drive unit away from the spindle unit with the pre-tensioning force. The pre-tensioning force has a force-generating device which couples the pre-tensioning force in between the drive unit and the spindle unit, so that the drive wheel and the transmission wheel are loaded with the pre-tensioning force in the direction of the belt free section (Riementrume) running therebetween, so that the belt is correspondingly tensioned. The pre-tensioning force is thus able to act directly and without additional tensioning mechanisms as a belt tension. An advantageously simple and compact construction, a low assembly outlay and a high functional and operating reliability are achieved.

[0013] The pre-tensioning force is preferably directed from the spindle axis to the drive axis, preferably perpendicular to both axes.

[0014] It can be provided that the spindle unit has a spindle housing in which the transmission wheel is rotatably mounted, and the drive unit has a drive device housing in which the drive wheel is rotatably mounted. The spindle housing serves, depending on the configuration as a sunken spindle drive or a rotary spindle drive, as a rotatable bearing of the transmission wheel about the spindle axis, which is connected to the spindle nut or the spindle screw in a torque-proof manner, and at the same time as an axial support of the transmission wheel in the direction of the spindle axis. Preferably, the spindle housing can be fixed on the steering column on the drive side and the spindle screw or the spindle nut, which is axially linearly adjustable with respect thereto by means of the spindle drive, can be fixed on a component of the steering column which is adjustable by means of an adjustment drive, remote from the drive device. Correspondingly, the spindle housing can preferably have a fixing means for attachment to the steering column.

[0015] The drive device housing serves to support a drive wheel about a drive axis, which is preferably parallel to the spindle axis, and is fixed relative to the spindle housing in the axial direction of the spindle axis. An electric motor can be connected with the drive device housing, so that the motor shaft is coupled in positive rotation with the drive wheel. Here, the motor can be flange-connected directly axially, and the drive wheel can be connected directly with the motor shaft. It is also possible for a transmission to be installed in the drive device housing, which is incorporated between the motor and the drive wheel. By means of the two housings, a modular structure can be achieved, wherein the drive device housing forms a drive module arranged on the input side or motor side of the belt drive, and the spindle housing accordingly forms an output module on the output side or spindle side. This functional division is advantageous for implementing the pretensioning device according to the application.

[0016] It can be provided with advantage that the pretensioning device has a pretensioning element which is arranged effectively between the drive unit and the spindle unit. A force-generating element or a force-storing element can be used as the pretensioning element between the drive unit and the spindle unit, which predefines the pretensioning force in a defined manner, which pushes the drive wheel and the transmission wheel away from one another. That is to say, the pretensioning force is directed in the direction in which the spacing between the drive wheel and the transmission wheel is expanded, in order to tension the belt. Such a pretensioning element can be provided and installed at low cost in the desired specification in terms of the pretensioning force. It is advantageous here that the pretensioning force and thus the belt tension can be maintained constantly and permanently without an external energy supply or actuation.

[0017] The pretensioning element can preferably have an elastic mechanism or be configured as such, which can be mechanically pretensioned to produce an elastic pretensioning force. Preferably, the pretensioning element can be arranged between the drive device housing and the spindle housing, in order to push them away from one another with the pretensioning force.

[0018] It can be provided that the pretensioning device has a spring element. The spring element forms an elastically springy pretensioning element, so that an elastic pretensioning force can be produced by its spring force. This can be provided easily and at low cost with a metal compression spring, tension spring or bending spring at little outlay. The spring element can be used with simple construction and is supported in such a way that its spring force, which is adjusted by a predefined mechanical tension, acts as a pretensioning force between the spindle unit and the drive unit.

[0019] An advantageous embodiment is achieved by the drive unit being movably supported in the guide device relative to the spindle unit. The drive unit is preferably displaceably held and guided in the guide device relative to the spindle unit in the direction of the pretensioning force, preferably in the direction of the free section of the belt running between the drive wheel and the transmission wheel. Preferably, the guide device is configured as a positive guide device with one degree of freedom of movement, so that only the distance between the drive wheel and the transmission wheel transverse to the drive axis and the spindle axis can be changed by the guide in order to adjust the belt tension, without axial displacement or tilting being allowed, which could impair the function of the belt drive. In this way, the running smoothness can be improved and wear reduced in an advantageous manner.

[0020] It is advantageous if the guide device is configured such that the drive device housing can be guidedly displaced relative to the spindle housing. The advantage is that, as mentioned above, the two housings can be realized in a modular structure. In order to implement the application, it is structurally advantageous if the housings can be moved relative to one another in a defined and only in a direction predetermined by the guide. This makes it possible to use simpler and less costly pretensioning elements or spring elements without particular requirements being placed on the defined spatial stiffness.

[0021] A further advantage is that, by means of the guide device, the relative displacement of the drive wheel and the transmission wheel can be limited by the length of the guide.

[0022] It can be advantageously provided that the guide device has a sliding guide. The sliding guide, for example, can comprise a slide guide which allows linear displacement in the direction of the pretensioning force. The displacement can only be effected in a predefined guide direction, which is also referred to as movement direction. The sliding guide can preferably be configured between the spindle housing of the spindle unit and the drive device housing of the drive unit. The pretensioning element can accordingly exert the pretensioning force only in the guide direction predetermined by the sliding guide, in which the drive unit and the spindle unit are pushed away from one another. The advantage of the sliding guide is that it can be provided in a simple and reliable manner by guide elements which engage with one another in a form-fit manner, which can only be moved relative to one another in the degree of freedom defined by the guide direction and are held in a form-fit manner at least partially in other directions. The slide guide, for example, can be constituted by a slide which can be guided along in a corresponding guide groove or the like.

[0023] The guide device can have a hinge. In order to form a hinged guide device, the hinge is arranged between the drive unit and the spindle unit such that the drive unit is supported pivotably about a hinge axis of the hinge relative to the spindle unit and can thereby be pivoted away, i.e. moved in the direction of the pretensioning force, in order to expand the distance to the spindle unit. The hinge axis can preferably be arranged substantially parallel to the spindle axis or the drive axis. Preferably, the hinge can be mounted between the spindle housing of the spindle unit and the drive device housing of the drive unit. A pretensioning element can act between the units hingedly connected to one another, which exerts a pretensioning torque as a pivoting torque in the direction of rotation of the hinge, so that the spindle unit and the drive unit are pushed away from one another. The advantage of the hinged guide is that, inter alia, a simple, compact construction and a relatively small friction can be achieved, thereby ensuring a reliable operation.

[0024] The hinge can be spring-loaded. Preferably, an elastic pretensioning torque as a pivoting torque can be exerted on the hinge by means of a spring element. The pretensioning torque acts on the hinge in order to pivot the drive unit about the hinge axis away from the spindle unit, so that a pretensioning is produced. The spring element can be realized by means of a bending spring, which can be provided and assembled at low outlay.

[0025] In an advantageous embodiment it can be provided that the hinge has an elastic bending hinge. The bending hinge, also referred to as a film hinge, preferably has a hinge element which can be flexibly bent, preferably a bending-elastic spring element, which provides an elastically bendable, elastic connection between the spindle unit and the drive unit. Such a bending hinge can have, for example, a leaf spring, for example a spring steel leaf. This makes a relative movement possible and at the same time forms a bending-elastic spring element. The elastic element is elastically tensioned when pivoted and exerts a pretensioning force on the hinge by means of its elastic return force. Preferably, the spring element can be mounted between the spindle housing of the spindle unit. Advantageously, a bending hinge can be provided at low outlay and with a small and constant hinge friction and virtually no maintenance.

[0026] The belt can be configured as a flat belt, a wedge belt, a wedge-ribbed belt or a toothed belt. Toothed belt drives provide a particularly high torque transmission as a form-fit traction mechanism. Flat belts or wedge belts can be realized at low cost and are also capable of achieving a high operating safety by virtue of the design according to the application.

[0027] The present invention also relates to a motor-adjustable steering column for a motor vehicle, the steering column having a support unit that can be mounted on the vehicle body and a servo unit held by the support unit, the steering spindle being rotatably mounted in the servo unit about a longitudinal axis; and having an adjustment drive device connected to the support unit and the servo unit, the servo unit being adjustable by the adjustment drive device relative to the support unit, wherein, according to the present invention, the adjustment drive device is formed according to one or a combination of the foregoing embodiments.

[0028] To achieve longitudinal adjustment of the steering column along the longitudinal axis of the steering spindle, an adjustment drive can be arranged between the servo unit and the housing unit (also referred to as the guide box or box arm), which houses the servo unit in an axially longitudinally movable manner and is connected to a support unit, wherein the lead screw axis can be oriented substantially parallel to the longitudinal axis. The adjustment drive can be arranged between sleeves of the servo unit that are longitudinally telescopically adjustable relative to each other for longitudinal adjustment.

[0029] For height adjustment, the spindle drive can be arranged between the support unit and the servo unit, which is height-adjustably supported thereon, or the housing unit that houses the servo unit.

[0030] Motor-type longitudinal and height adjustments can be configured individually or in combination on the steering column. Attached Figure Description

[0031] Advantageous embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Wherein:

[0032] Figure 1 A schematic perspective view of a motor-adjustable steering column according to the present invention is shown.

[0033] Figure 2 A different perspective view shows the results based on Figure 1 The steering column,

[0034] Figure 3 A schematic perspective view of a first embodiment of the regulating drive device according to the present invention is shown.

[0035] Figure 4 Shown in another view according to Figure 3 The adjustment drive device,

[0036] Figure 5 Shown in another view according to Figure 3 or Figure 4 The adjustment drive device,

[0037] Figure 6A schematic perspective view of a second embodiment of an adjustment drive according to the application is shown,

[0038] Figure 7 A schematic perspective view of a third embodiment of an adjustment drive according to the application is shown. DETAILED DESCRIPTION

[0039] Figure 1 A schematic perspective view of a steering column 1 according to the application is shown from an obliquely top view from behind with respect to the driving direction of a not shown vehicle in which a not shown steering wheel is held in an operating region. Figure 2 A view of the same steering column 1 is shown from an oblique lower view.

[0040] The steering column 1 comprises a support unit 2 which is configured as a bracket with a fixing mechanism 21 in the form of a fixing hole to be attached to a not shown vehicle body. A servo unit 3 is held by the support unit 2 which is accommodated in a housing unit 4 which is also referred to as a guide box or box-shaped swing arm.

[0041] The servo unit 3 has a sleeve 31 in which a steering spindle 32 is supported in a rotatable manner about a longitudinal axis L which extends axially in a longitudinal direction. At a rear end of the steering spindle 32 a fixing portion 33 is configured to which a not shown steering wheel can be attached. On a front end the steering spindle 32 is torque- fittingly connected with a fork 351 of a universal joint 35.

[0042] For the realization of a longitudinal adjustment the servo unit 3 is accommodated in the housing unit 4 in a displaceable manner in the direction of the longitudinal axis L so that the steering wheel connected to the steering spindle 32 can be positioned in front of and behind the support unit 2 in the longitudinal direction as indicated by the double arrow parallel to the longitudinal axis L.

[0043] A first adjustment drive 5 designed according to the application for the longitudinal adjustment of the servo unit 3 in the direction of the longitudinal axis L relative to the housing unit 4 has a spindle unit 6 and a drive unit 7.

[0044] The spindle unit 6 comprises a spindle drive and has a spindle nut 61 with an internal thread into which a lead screw 62, also referred to simply as spindle 62, extending along a spindle axis S engages, i.e. with its external thread into the corresponding internal thread of the spindle nut 61. The spindle axis S extends substantially parallel to the longitudinal axis L.

[0045] The spindle nut 61 is rotatably supported in the spindle housing 63 about the axis S and is axially supported on the spindle housing 63 in the direction of the axis S here. The spindle housing 63 is connected with the housing unit 4 and is axially supported.

[0046] The spindle 62 is connected with the servo unit 3 via the transmission element 34 by means of a fixing element 51 which is configured at the rear end of the spindle 62 remote from the drive device, more precisely fixedly in axial direction, i.e. in the direction of the spindle axis S or longitudinal axis L and fixed with respect to rotation about the axis S. The so-called plunge spindle drive is realized by the rotationally driven spindle nut 61 and the spindle 62 which is fixed with respect to rotation about the axis S.

[0047] The transmission element 34 extends from the servo unit 3 through a slot-shaped through-hole 41 in the housing unit 4. In order to adjust the steering column 1 in longitudinal direction, the transmission element 34 is freely movable in longitudinal direction in the through-hole 41 along its movement.

[0048] The drive unit 7 has an electric motor 71 with a motor shaft 72 which extends along a drive axis A. By means of a belt drive 8, the spindle nut 61 is rotationally drivable about the spindle axis S by the motor 71, the belt drive being designated by Figures 3 to 7 further below. Thereby, depending on the direction of rotation of the motor 71, the spindle 52 can be axially displaced relative to the spindle nut 61 in the direction of the spindle axis S, so that the servo unit 3 connected with the spindle 62 is correspondingly adjusted relative to the housing unit 4 connected with the spindle nut 61 in the direction of the longitudinal axis L. The drive of the spindle nut 61 is explained in detail further below.

[0049] It can also be seen in Figure 2 that the second adjustment drive 50 for adjustment in height direction H is mounted on the steering column 1.

[0050] The housing unit 4 is pivotably mounted on the support unit 2 about a height adjustment axis 22 on the support unit 2 in height direction H.

[0051] The height adjustment drive 50 comprises a spindle nut 52 into the inner thread of which a spindle 53 engages. The spindle 53 is rotationally drivable about its axis by a drive unit 54.

[0052] The spindle nut 52 is fixedly mounted in terms of rotation about its axis on one end of a double-armed lever 42 which is pivotably supported on the support unit 2 about a swivel bearing 23 and whose other arm is connected with the other end with the housing unit 4.

[0053] By rotation of the spindle 53, the spindle nut 52 can be axially displaced relative to the spindle 53, depending on the direction of rotation of the drive, so that the housing unit 4 connected with the spindle nut 52 by means of the lever 42 can be correspondingly adjusted up and down relative to the support unit 2 in height direction H together with the servo unit 3 accommodated therein, as indicated by the double arrow.

[0054] The so-called rotary spindle drive, also called rotating spindle drive, is realized by means of the rotatably driven spindle 53 and the rotationally fixed spindle nut 52.

[0055] The application relates to a height adjustment drive 5. It is shown in detail in a first embodiment in Figures 3 to 5 , and in a second embodiment in Figure 6 , and in a third embodiment in Figure 7 , wherein the same reference numerals are used for elements that have the same effect. The height adjustment drive 50 can be configured in principle analogously to the adjustment drive 5.

[0056] The belt drive 8 has a drive wheel 81 which is rotatably driven by the motor 71, which is configured as a belt wheel and is connected to the motor shaft 72. A transmission wheel 82 is configured coaxially to the spindle nut 61 and is connected in a rotationally fixed manner, which is likewise configured as a belt wheel. A belt 83 is wound around the drive wheel 81 and the transmission wheel 82 as a traction means.

[0057] In the first embodiment, the drive device housing 73 is formed by the motor housing of the motor 71. In the drive device housing 73, the drive wheel 81 is rotatably driveably supported about the drive axis A.

[0058] The drive unit 7 is displaceable relative to the spindle unit 6 in a pretensioning direction F, which is schematically depicted in Figure 4 on the drive axis A. The pretensioning direction F points perpendicularly to the spindle axis S to the drive axis A and is preferably identical to the guide direction of the guide device 80.

[0059] In the first embodiment according to Figures 3 to 5 , the guide device 80 comprises a linear push travel guide. The push travel guide has a base plate 84 which is fixedly connected to the spindle housing 63 and extends plane-parallel to the drive axis A. The motor 71 is held on the base plate 84, wherein the motor shaft 72 projects through the base plate. The base plate 84 has a guide slot 841 which is elongated in the adjustment direction F, in which a guide pin 842 which projects axially from the drive device housing 73 of the motor 71 in the direction of the drive axis A is slidably guided in the pretensioning direction F, as indicated by the arrow. Thereby, the drive unit 7 can be moved away from the spindle unit 6 pointing transversely to the spindle axis S, whereby the distance between the drive wheel 81 and the transmission wheel 82 is increased.

[0060] The pretensioning element in the form of a curved leaf spring 85 is elastically pretensioned in the pretensioning direction F on the drive device housing 71 and the spindle housing 63. By means of the spring force, the drive device housing 71 is loaded together with the drive wheel 81 pointing away from the spindle housing 63 and is guidedly displaced in the guide device 80, wherein the belt 83 is tensioned with the pretensioning force generated by the tensioning of the spring element 85. In this way, the belt tension can be predetermined by the pretensioning of the spring element 85. Here, the spring force and thus the belt tension can be kept virtually constant in operation.

[0061] In a second embodiment according to Figure 6 the motor 71 is connected with the drive device housing 73, in which the drive wheel 81 is supported.

[0062] Instead of the push-through guide according to the first embodiment, the guide and pretensioning device is configured as a hinge guide. This hinge guide consists of a spring-elastic curved hinge 86, which, as shown by way of example, can have a spring steel band, which is fixed between the drive device housing 73 and the spindle housing 63. By means of the elastic bending of the curved hinge 86, a guided arc-shaped movement B of the drive device housing 73 relative to the spindle housing 63 about a hinge axis parallel to the spindle axis S is achieved, as indicated by the curved arrow. Thereby, the drive device housing 73 and the spindle housing 63 can be swung relative to each other, whereby the distance between the drive axis A and the spindle axis S can be changed. The curved hinge consists of two tab-like parts, which are connected to each other by a flexurally flexible part. Here, the curved hinge 86 itself generates an elastic pretensioning force when it is flexurally deformed, which acts as a bending or swinging moment and elastically loads the drive device housing 73 and the spindle housing 63 transversely to the spindle axis S and pushes them away from each other. Accordingly, the belt can be tensioned by the spring force of the curved hinge 86.

[0063] A third embodiment according to Figure 7 is similar to the previously described embodiments in terms of the configuration and arrangement of the drive device housing 73 and the spindle housing 63. One difference is that, in addition to or instead of the curved hinge 86 shown therein, a spring element 85 can be provided, which pushes the drive device housing 73 and the spindle housing 63 away from each other by means of a spring force, as in the first embodiment, and thereby generates the belt tension of the belt 83. Here, a curved hinge 86 similar to that according to the first embodiment can be used, or else another conventional hinge with a hinge pin between the tab-like parts can also be used, which, however, does not generate a pretensioning force or only a part of the pretensioning force, which can then be provided by the additional spring element 85. Figure 6

[0064] Legend of the Figures​

[0065] 1 steering column

[0066] 2 support unit

[0067] 21 fixing means

[0068] 22 height adjustment axis

[0069] 23 oscillation bearing

[0070] 3 servo unit

[0071] 31 sleeve

[0072] 32 steering spindle

[0073] 33 fixing portion

[0074] 34 transmission element

[0075] 35 universal joint

[0076] 4 housing unit

[0077] 41 through hole

[0078] 42 joystick

[0079] 5, 50 adjustment drive

[0080] 51 fixing element

[0081] 52 spindle nut

[0082] 53, 62 screw

[0083] 54 drive unit

[0084] 56, 66 motor shaft

[0085] 6 spindle unit

[0086] 61 spindle nut

[0087] 62 screw

[0088] 63 spindle housing

[0089] 7 drive unit

[0090] 71 motor

[0091] 72 motor shaft

[0092] 73 drive housing

[0093] 8 belt drive

[0094] 80 guide

[0095] 81 drive wheel

[0096] 82 transmission wheel

[0097] 83 toothed belt

[0098] 84 base plate

[0099] 841 guide groove

[0100] 842 guide pin

[0101] 85 spring element

[0102] 86 flexure hinge

[0103] L longitudinal axis

[0104] A drive axis

[0105] S spindle axis

[0106] H height direction

[0107] F pretensioning direction

Claims

1. Adjusting drive (5) for a motor-adjustable steering column (1) of a motor vehicle, comprising a spindle unit (6) having a lead screw (62) with a spindle axis (S) engaged into a spindle nut (61) and a drive unit (7) having a drive wheel (81) which is configured as a belt pulley and which is drivable by an electric motor (71) to rotate about a drive axis (A), wherein A drive wheel (82) which is coupled in a driving manner to the drive wheel (81) via a looped belt (83) is connected to the spindle nut (61) or the spindle screw (62), characterized in that a pretensioning device is provided between the drive unit (7) and the spindle unit (6); the pretensioning device has a pretensioning element (85, 86) which is arranged effectively between the drive unit (7) and the spindle unit (6); the pretensioning device is configured to push the drive unit (7) away from the spindle unit (6) by a pretensioning force; the pretensioning device is configured as a hinge guide which consists of a spring-elastic curved hinge (86) which itself generates an elastic pretensioning force when it is curvedly deformed; the curved hinge consists of two tab-like parts which are connected to one another by a curvedly flexible part.

2. Adjusting drive according to the preceding claim 1, characterized in that The spindle unit (6) has a spindle housing (63) in which the drive wheel (82) is rotatably mounted, and the drive unit (7) has a drive device housing (73) in which the drive wheel (81) is rotatably mounted.

3. Adjusting drive according to any of the preceding claims 1-2, characterized in that, The pretensioning device has a spring element (85, 86).

4. The adjustment drive according to any of the preceding claims 1 - 2, characterized in that The drive unit (7) is movably mounted in a guide device (80) relative to the spindle unit (6).

5. The adjustment drive according to any of the preceding claims 1-2, characterized in that The belt (83) is configured as a flat belt, a wedge belt, a wedge-ribbed belt or a toothed belt.

6. Motor-adjustable steering column (1) for a motor vehicle, having a support unit (2) which can be attached to the vehicle body and which holds a servo unit (3) in which a steering spindle (32) is rotatably mounted about a longitudinal axis (L), and having an adjustment drive (5) which is connected to the support unit (2) and to the servo unit (3) and by means of which the servo unit (3) can be adjusted relative to the support unit (2), characterized in that the adjustment drive (5) is designed in accordance with any one of the preceding claims 1 to 5.

7. A column according to claim 6, wherein The adjustment drive (5) for the longitudinal adjustment is arranged between the sleeves (31, 4) which can be adjusted relative to one another in a telescoping manner along the longitudinal direction.

8. A steering column according to any one of claims 6-7, characterised in that, The adjustment drive (5) for the height adjustment transverse to the longitudinal axis (L) is arranged between the servo unit (3) and the support unit (2). The adjustment drive (5) for the height adjustment transverse to the longitudinal axis (L) is arranged between the servo unit (3) and the support unit (2).

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