ADJUSTING 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 that by way of an external thread engages in a spindle nut. The adjusting drive may also include a drive motor that is coupled to the threaded spindle or the spindle nut such that driving at least one of the threaded spindle or the spindle nut with the drive motor causes the threaded spindle and the spindle nut to rotate relative to one another. To reduce production complexity and improve functionality, the threaded spindle may have a core element that at least in portions is coaxially surrounded in a fixed manner by a threaded element that is configured from plastic and comprises the external thread.

Claims

1.-15. (canceled)

16. An adjusting drive for a steering column for a motor vehicle, the adjusting drive comprising: a threaded spindle with a core element that at least in portions is coaxially surrounded in a fixed manner by a threaded element that is comprised of plastic and includes an external thread; a spindle nut, wherein the external thread of the threaded spindle engages in the spindle nut; and a drive motor that is coupled to the threaded spindle or the spindle nut such that driving at least one of the threaded spindle or the spindle nut causes the threaded spindle and the spindle nut to rotate relative to one another.

17. The adjusting drive of claim 16 wherein the threaded element is sleeve-shaped and arranged on the core element.

18. The adjusting drive of claim 16 wherein the threaded element is an injection-molded overmold.

19. The adjusting drive of claim 16 wherein the core element comprises metal.

20. The adjusting drive of claim 16 wherein a material of the core element has a higher thermal conductivity than the plastic of the threaded element.

21. The adjusting drive of claim 16 wherein the core element includes a form-fitting element that is connected in a form-fitting manner to the threaded element.

22. The adjusting drive of claim 16 comprising a gear wheel that is at least partially configured conjointly with the threaded element.

23. The adjusting drive of claim 16 wherein the threaded element includes a preloading element that is elastically preloaded relative to a thread turn of the spindle nut.

24. The adjusting drive of claim 23 wherein the preloading element includes a spring element that on the threaded element is configured to project in a helically encircling thread turn of the external thread.

25. The adjusting drive of claim 16 wherein the core element is tubular at least in portions.

26. The adjusting drive of claim 16 wherein the threaded spindle includes an internal thread.

27. The adjusting drive of claim 26 wherein the internal thread is configured in the core element or in the threaded element.

28. The adjusting drive of claim 16 wherein the core element or the threaded element includes a detent element.

29. A steering column for a motor vehicle comprising: a support unit that is attachable to a body of the motor vehicle; an actuating unit in which a steering spindle is rotatably mounted, with the actuating unit being held via the support unit; an adjusting drive that includes a threaded spindle with a core element that at least in portions is coaxially surrounded in a fixed manner by a threaded element that is comprised of plastic and includes an external thread, wherein the external thread of the threaded spindle engages in a spindle nut, wherein the adjusting drive includes a coupling portion that is connected to the support unit or the actuating unit; and a drive motor that is coupled to the threaded spindle or the spindle nut such that driving at least one of the threaded spindle or the spindle nut causes the threaded spindle and the spindle nut to rotate relative to one another.

30. A method for producing an adjusting drive that comprises a threaded spindle with external threads that engage in a spindle nut, a drive motor that is coupled to the threaded spindle or the spindle nut such that driving at least one of the threaded spindle or the spindle nut causes the threaded spindle and spindle nut to rotate relative to one another, wherein the threaded spindle includes a coupling portion, the method comprising: providing a core element; attaching a threaded element comprised of plastic to the core element to form the threaded spindle; and screwing the threaded spindle into the spindle nut.

Description

DESCRIPTION OF THE DRAWINGS

[0049] Advantageous embodiments of the invention will be explained in more detail hereunder by means of the drawings in which:

[0050] FIG. 1 shows a schematic perspective view of a steering column according to the invention;

[0051] FIG. 2 shows a further perspective view of the steering column according to the invention according to FIG. 1, viewed from another angle;

[0052] FIG. 3 shows an adjusting drive according to the invention in a schematic perspective illustration;

[0053] FIG. 4 shows a longitudinal section through the adjusting drive according to FIG. 3, along the threaded spindle axis;

[0054] FIG. 5 shows a perspective view of a threaded spindle in a first embodiment;

[0055] FIG. 6 shows a detailed view of the external thread of the threaded spindle according to FIG. 5;

[0056] FIG. 7 shows a longitudinal section through the threaded spindle according to FIG. 5;

[0057] FIG. 8 shows the threaded spindle according to FIG. 5 in a schematically exploded illustration;

[0058] FIG. 9 shows a schematically exploded perspective view of a threaded spindle as in FIG. 8, in a second embodiment;

[0059] FIG. 10 shows a view of a detail of a second embodiment of the external thread of the threaded spindle as in FIG. 6

[0060] FIG. 11 shows a radial view of the detail of FIG. 10;

[0061] FIG. 12 shows a further embodiment of the external thread of the threaded spindle in a view as in FIG. 11;

[0062] FIG. 13 shows a longitudinal section as in FIG. 4 through a second embodiment of an adjusting drive;

[0063] FIG. 14 shows a perspective view of the spindle drive of the adjusting drive according to FIG. 13

[0064] FIG. 15 shows a longitudinal section as in FIG. 4 through an adjusting drive in a third embodiment;

[0065] FIG. 16 shows a longitudinal section as in FIG. 15 through an adjusting drive in a third embodiment;

[0066] FIG. 17 shows a longitudinal section through a threaded spindle and the spindle nut of an adjusting drive in a fourth embodiment;

[0067] FIG. 18 shows a perspective view of the core element according to FIG. 17; and

[0068] FIG. 19 shows a longitudinal section through a threaded spindle and a spindle nut of an adjusting drive in a fifth embodiment.

EMBODIMENTS OF THE INVENTION

[0069] The same parts are at all times provided with the same reference signs in the various figures and therefore are typically also referred to or mentioned, respectively, only once.

[0070] FIG. 1 shows a steering column 1 according to the invention in a schematic perspective view from top right obliquely onto the rear end in terms of the travel direction of a vehicle not illustrated, where a steering wheel not illustrated here is held in the operating region. FIG. 2 shows the steering column 1 in a view from the opposite side, thus seen from top right.

[0071] The steering column 1 comprises a support unit 2 which is configured as a console which has fastening means 21 in the form of fastening bores for attaching to a vehicle body not illustrated. An actuating unit 3 which is received in a casing unit 4, also referred to as a guide box or a boxed swing arm, is held by the support unit 2.

[0072] The actuating unit 3 has a casing tube 31 in which a steering spindle 32 is mounted so as to be rotatable about a longitudinal axis L which extends axially in the longitudinal direction, that is to say in the direction of the longitudinal axis L. A fastening portion 33 to which a steering wheel not illustrated is able to be attached is configured at the rear end on the steering spindle 32.

[0073] The actuating unit 3 for implementing a longitudinal adjustment is received in the casing unit 4 so as to be telescopically displaceable in the direction of the longitudinal axis L, in order to be able to position the steering wheel relative to the support unit 2 forward and backward in the longitudinal direction, said steering wheel being connected to the steering spindle 32, as is indicated by the double arrow parallel to the longitudinal axis L.

[0074] The casing unit 4 is mounted in a pivot bearing 22 on the support unit 2 so as to be pivotable about a horizontal pivot axis S which is transverse to the longitudinal axis L. In the rear region, the casing unit 4 is connected to the support unit 2 by way of an actuating lever 41. By way of a rotating movement of the actuating lever 41 by means of an illustrated actuating drive 6 (see FIG. 2), the casing unit 4 can be pivoted relative to the support unit 2 about the pivot axis S which in the installed state is horizontal, on account of which an adjustment of a steering wheel which is attached to the fastening portion 33 can be performed in the height direction H, this being indicated by the double arrow.

[0075] A first adjusting drive 5 for longitudinally adjusting the actuating unit 3 relative to the casing unit 4 in the direction of the longitudinal axis L has a spindle mechanism having a spindle nut 51 having an internal thread 74 which extends along an axis G and in which a threaded spindle 52 engages, the latter by way of the external thread thereof thus being screwed into the corresponding internal thread 74 of the spindle nut 51. The threaded spindle axis of the threaded spindle 52 is identical to the axis G and runs so as to be substantially parallel to the longitudinal axis L.

[0076] The spindle nut 51 is mounted in a bearing housing 53 so as to be rotatable about the axis G, said bearing housing 53 being fixedly connected to the casing unit 4. In the direction of the axis G, the spindle nut 51 is axially supported on the casing unit 4 by way of the bearing housing 53. Accordingly, the adjusting drive 5 is a so-called immersion spindle drive.

[0077] The threaded spindle 52 by way of a fastening element 54 configured on the rear end of said threaded spindle 52 is connected to the actuating unit 3 by way of a transmission element 34, specifically fixedly connected in the direction of the axis G, or the longitudinal axis L, respectively, and connected so as to be stationary in terms of the rotation about the axis G. A so-called immersion spindle drive is implemented on account of the spindle nut 51 being able to be driven in a rotating manner and the threaded spindle 52 which is stationary in terms of rotation.

[0078] The transmission element 34 extends from the actuating unit 3 through a slot-shaped passage opening 42 in the casing unit 4. For adjusting the steering column 1 in the longitudinal direction, the transmission element 34 can be freely moved along in the longitudinal direction in the passage opening 42.

[0079] The adjusting drive 5 has an electric drive motor 55 by way of which the spindle nut 51 in terms of the axis G is able to be driven so as to rotate relative to the stationary threaded spindle 52. Depending on the rotating direction of the drive motor 55, the threaded spindle 52 on account thereof can be repositioned in a translatory manner relative to the spindle nut 51 in the direction of the axis G such that the actuating installation 3 which is connected to the threaded spindle 52 is correspondingly adjusted in the direction of the longitudinal axis L relative to the casing unit 4 which is connected to the spindle nut 51. The drive of the spindle nut 51 and the support of the spindle nut 51 in the direction of the axis G on the casing unit 4 will be explained in detail hereunder.

[0080] It can be seen in FIG. 2, which shows a perspective view of the steering column 1 from that side which is at the rear in FIG. 1, how a second adjusting drive 6 for the adjustment in the height direction H is attached to the steering column 1. This adjusting drive 6 comprises a spindle nut 61, a threaded spindle 52 engaging in the internal thread 74 along an axis G of said spindle nut 61. The threaded spindle 52 is mounted in a bearing housing 63 which is fastened to the casing unit 4 so as to be rotatable about the axis G and is supported axially, in the direction of the axis G, on the casing unit 4, and is able to be driven so as to rotate, selectively in both directions of rotations, about the axis G by an electric drive motor 65. Accordingly, the adjusting drive 6 is a so-called rotary spindle drive.

[0081] The spindle nut 61 which may be formed from plastics material or from a nonferrous metal such as brass or the like, in terms of rotation about the axis G is attached so as to be stationary on an end of the twin-armed actuating lever 41 which is mounted on the support unit 22 so as to be rotatable about a pivot bearing 23, the other arm of said actuating lever 41 by way of the other end being connected to the casing unit 4.

[0082] Depending on the direction of rotation of the drive motor 65, the spindle nut 61 by rotating the threaded spindle 61 can be repositioned in a translatory manner in the direction of the axis G relative to the threaded spindle 52 such that the casing unit 4, which by way of the actuating lever 41 is connected to the spindle nut 41, including the actuating installation 3 received therein, can accordingly be adjusted up or down in the height direction H relative to the support unit 2, as is indicated by the double arrow. The drive of the threaded spindle 52 and the support of the threaded spindle 52 in the direction of the axis G on the casing unit 4 will be explained in more detail hereunder.

[0083] FIGS. 3 and 4 show the adjusting drive 5 configured as an immersion spindle drive in a stand-alone illustration.

[0084] The threaded spindle 52 according to the invention has a tubular, hollow-cylindrical core element 57, preferably from steel tubing, to which a threaded element 58 is non-releasably attached in a coaxial manner, said threaded element 58 having the external thread with a helically encircling thread tooth 581 and being potentially over molded by plastic injection molding.

[0085] In order for the fastening element 54 which serves as a coupling element to be formed, the tube of the core element 57, preferably by cold forming, is compressed transversely to the threaded spindle axis so as to be flat and perpendicularly to the compression has a continuous fastening bore 541. A fastening pin 542 for connecting in a rotationally fixed manner to the transmission element 34 is passed through this fastening bore 541, as can be seen in FIG. 1.

[0086] The threaded spindle 52 is screwed into a spindle nut 51 which is rotatable in the bearing housing 53 but fixedly supported therein in the direction of the threaded spindle axis G. The spindle nut 51 is configured as a gear wheel and on the external circumference thereof has a toothing 72, specifically a worm toothing. A worm 56 which meshes with a toothing such that the spindle nut 51 is able to be driven so as to rotate relative to the threaded spindle 52 is connected to the motor shaft of the drive motor 55.

[0087] The core element 57 at the end facing away from the fastening element 54 has a detent element 571 which is configured as a radially outward projecting encircling collar, preferably by enlarging the tubular core element 57 by cold forming.

[0088] The threaded element 58 at the end thereof that faces the fastening element 54 likewise has a detent element 580 which is configured as an encircling protrusion or collar and which by plastic injection molding is configured so as to be integral to the threaded element 58.

[0089] The detent elements 571 and 580 form axial detents which cannot be screwed through the spindle nut 51 and thus delimit the adjustment path.

[0090] FIG. 5 shows the threaded spindle 52 in a perspective stand-alone view. The threaded element 58 has an axially continuous flattening 582 which can be clearly seen in the enlarged fragment of FIG. 6. The thread tooth 581 in each turn has a gap in the region of this flattening 582, one preloading element 59 being in each case configured in said gap. The preloading elements 59 in the first embodiment of FIG. 6 are configured as radially projecting pads or blocks which in the axial direction may be slightly wider than the encircling cross section of the thread tooth 58. The preloading elements 59 can likewise preferably be configured by plastic injection molding so as to be integral to the threaded element 58. On account of the elastic deformation of the plastics material, the preloading elements 59 can be preloaded or tensioned, respectively, without play in a resilient manner in the thread turn of the internal thread of the spindle nut 51.

[0091] Gaps which are concavely molded in an integral manner in the injection-molded plastic part and serve as lubricant pockets 583 are present between the exposed preloading elements 59 and the windings of the thread tooth 581.

[0092] Further variants of preloading elements 59 are illustrated in FIGS. 10 and 11 as well as 12. The threaded element again has at least one, preferably two, mutually opposite flattenings 582 in which the thread tooth 581 has a gap in the circumference. In the second embodiment of FIGS. 10 and 11, each preloading element 59 has two radially projecting leaf-shaped or finger-shaped spring elements 591 which are spaced apart axially in the direction of the threaded spindle axis G and in the circumferential direction. Said spring elements 591 are elastically flexural in the axial direction and in the non-deformed state axially project slightly beyond the cross section of the thread tooth 581. On account thereof, said spring elements 591 in the screwed-in state in a thread turn are in each case tensioned between the thread flanks in the internal thread of the spindle nut 51.

[0093] The embodiment shown in FIG. 12 in a view as in FIG. 11 is of similar configuration, wherein each spring element 591 is configured as a Z-shaped spring leaf in that the spring elements which in FIG. 11 are in pairs are integrally combined.

[0094] All of the embodiments of spring elements 591 by plastic injection molding can be configured so as to be integral on the threaded element 58. The elasticity and the spring force exerted for preloading can be adapted and predefined according to requirements by way of the dimensions of said spring elements 591.

[0095] The available space between the spring elements 591 are used as a lubricant pocket 583.

[0096] FIGS. 8 and 9 schematically show the core element 57 and the threaded element 58 in an axially exploded illustration. While the tubular region in which the threaded element 58 is situated in the assembled state in FIG. 8 is configured so as to be cylindrical with a smooth surface, said tubular region in the embodiment according to FIG. 9 has form-fitting elements 584 which may be configured as concave moldings such as grooves, cutouts or protrusions and which are embedded in the plastics material during overmolding and generate a connection which is form-fitting in the axial direction and the circumferential direction.

[0097] FIGS. 13 and 14 show a refinement of an immersion spindle mechanism in which the threaded spindle 52 does not have the fastening element but an internal thread 521 into which a second threaded spindle 522 is screwed, said second threaded spindle 522 at the free end thereof being connected to the fastening element 54.

[0098] The internal thread 521 can be configured in a threaded bush 520 which is inserted into the core element 57 and/or connected to the threaded element 58, for example by the overmolding described above. It is likewise conceivable and possible for the internal thread 521 to be concavely molded by plastic injection molding so as to be integral in the threaded element 58.

[0099] FIG. 15 and FIG. 16 illustrate a longitudinal section through the bearing housing 62 of the adjusting drive 6 along the axis G in different variants of embodiment. In this construction mode of the rotary spindle drive the threaded spindle 52 rather than the spindle nut is rotatingly driven by the drive motor.

[0100] A gear wheel 7 which is designed so as to be rotationally fixed in terms of the threaded spindle axis G is fastened to the threaded spindle 52. The gear wheel 7 by injection molding is at least partially made from plastics material so as to be integral to the threaded element 58 and has a hub element 71. The gear wheel 7 on the external circumference thereof has a toothing 72 which coaxially encircles the axis G and in the example illustrated is configured as a worm toothing such that the gear wheel 7 forms a worm gear. A worm 66 which is able to be rotatingly driven by the drive motor 65 engages in the toothing 72.

[0101] In the embodiment of FIG. 15, the hub element 71 by plastic injection molding is configured so as to be integral to the threaded element 58.

[0102] Bearing rings 8 are fixedly connected to the hub element 71. Each bearing ring 8 has an annular bearing face 81 which is configured as a ball race and is coaxial with the axis G. The two bearing faces 81, when viewed from the hub element 71, at the end sides converge conically toward the outside. In other words, the ball races are oblique in relation to the axis G.

[0103] The bearing rings 8 have support portions 82 which are axially directed toward one another in the direction of the axis G and in the example shown lie directly against one another such that the bearing rings 8 are directly supported on one another in the direction of the axis G.

[0104] The bearing rings 8 are preferably configured as formed sheet-metal parts, particularly preferably as stamped/punched parts from steel sheet. In order to be connected to the gear wheel 7, the bearing rings 8 are overmolded with the plastics material of the threaded element 58 and, with the exception of the bearing faces 81 which at the end sides are externally exposed, are embedded in a substance-to-substance bonded and form-fitting manner in the hub element 71.

[0105] The bearing faces 81 form the inner rings of a roller bearing assembly which comprises balls 91 which are rotatably held in a ball cage 92 and are disposed so as to be able to roll in the axial bearing gap between said ball races of the bearing faces 81 and the corresponding ball races in the outer bearing rings 93. The outer bearing rings 93, when viewed from the gear wheel 7, are axially supported in relation to the outside on counter bearings 94 at both end sides.

[0106] In the embodiment according to FIG. 16, the gear wheel 7 including the hub element 71 and the toothing 72 is made from plastics material by injection molding so as to be integral to the threaded element 58.

[0107] A longitudinal section through a threaded spindle 52 and a spindle nut 51 in a fourth embodiment is illustrated in FIG. 17. The threaded spindle 52 according to the invention has a hollow corrugated core element 57, preferably of steel, on which a threaded element 58 is non-releasably attached in a coaxial manner, said threaded element 58 having the external thread having a helically encircling thread tooth 581 and potentially being overmolded by plastic injection molding.

[0108] It can be readily seen in this longitudinal section through the threaded spindle axis G that the core element 57 has an alternating disposal of convex and concave portions.

[0109] The core element 57 herein has a helically encircling groove 586 and a helically encircling protrusion 585. The thread tooth 581 preferably has a pitch, wherein the pitch of the thread tooth 581 is identical to that of the encircling groove 586, or identical to the pitch of the encircling protrusion 585, respectively. The thread tooth 581 herein is preferably configured in the region of the helically encircling protrusion 586 in the threaded element 58. In other words, the thread tooth 581 and the encircling protrusion are disposed so as to be mutually synchronous. The groove 586 and the protrusion 585 form form-fitting elements which when overmolding are embedded in the plastics material of the threaded element 58 and generate a connection which is form-fitting in the axial direction and the circumferential direction. A particularly stable and rigid assembly can thus be provided.

[0110] The core element 57 according to FIG. 17 is illustrated in a perspective illustration in FIG. 18, wherein the core element 57 has a helically encircling groove 586 and a helically encircling protrusion 585. The encircling groove 586 and the encircling protrusion 585 are preferably configured in such a manner that said groove 586 and said protrusion 585 form an Edison screw fitting (lightbulb fitting) according to DIN 40400.

[0111] FIG. 19 shows a longitudinal section through a threaded spindle 52 and a spindle nut 51 of an adjusting drive 5 along the threaded spindle axis G in a fifth embodiment. This embodiment shows a refinement of an immersion spindle mechanism similar to the embodiment according to FIG. 17, in which the threaded spindle 52 has a threaded bush 520 having an internal thread 521 into which a second threaded spindle 522 is screwed, said second threaded spindle 522 at the free end thereof being able to be connected to the fastening element 54, as is known from the embodiment of FIGS. 13 and 14.

[0112] The internal thread 521 is configured in the threaded bush 520 which is formed from plastics material and which is injection-molded in the core element 57. The thread tooth of the internal thread 521 herein is configured so as to be synchronous with the groove 586, wherein the groove 586 in terms of the internal thread 521, thus when viewed from the inside, forms a protrusion. In other words, a groove on the external shell face of the core element 57 forms a protrusion on the internal shell face, or vice versa.

LIST OF REFERENCE SIGNS

[0113] 1 Steering column [0114] 2 Support unit [0115] 21 Fastening means [0116] 22, 23 Pivot bearing [0117] 3 Actuating unit [0118] 31 Casing tube [0119] 32 Steering spindle [0120] 33 Fastening portion [0121] 34 Transmission element [0122] 4 Casing unit [0123] 41 Actuating lever [0124] 42 Passage opening [0125] 5, 6 Adjusting drive [0126] 51, 61 Spindle nut [0127] 52, 62 Threaded spindle [0128] 520 Threaded bush [0129] 521 Internal thread [0130] 522 Threaded spindle [0131] 53, 63 Bearing housing [0132] 54 Fastening element [0133] 541 Fastening bore [0134] 542 Fastening pin [0135] 55, 65 Drive motor [0136] 56, 66 Worm [0137] 57 Core element [0138] 571 Detent element [0139] 58 Threaded element [0140] 580 Detent element [0141] 581 Thread tooth [0142] 582 Flattening [0143] 583 Lubricant pockets [0144] 584 Form-fitting elements [0145] 59 Preloading element [0146] 591 Spring element [0147] 7 Gear wheel [0148] 71 Hub element [0149] 72 Toothing [0150] 73 Connecting portion [0151] 74 Internal thread [0152] 8 Bearing ring [0153] 81 Bearing face (Ball race) [0154] 91 Balls [0155] 92 Ball cage [0156] 93 Outer bearing rings [0157] 94 Counter bearing [0158] L Longitudinal axis [0159] H Height direction [0160] G Threaded spindle axis