LENGTH-ADJUSTABLE STEERING SHAFT FOR A MOTOR VEHICLE, AND PROFILED SLEEVE FOR A STEERING SHAFT

Abstract

A length-adjustable steering shaft for a motor vehicle may include a hollow outer shaft with an unround inner cross section, in which an inner shaft is received in a torque-locked and axially movable manner. A profiled sleeve may be arranged between the inner shaft and the outer shaft, and the profiled sleeve may have a fastening portion connected to the inner shaft. The inner shaft may be configured at least in part as a hollow shaft that has an interior that is open towards the end that is inserted into the outer shaft. To reduce the outlay in terms of production and assembly, the fastening portion may extend from the end into the interior of the inner shaft and is connected to an inner surface of the interior.

Claims

1.-11. (canceled)

12. A length-adjustable steering shaft for a motor vehicle, comprising: a hollow outer shaft with an unround inner cross section; an inner shaft that is received in a torque-locked and axially movable manner in the hollow outer shaft; and a profiled sleeve disposed between the inner shaft and the outer shaft, the profiled sleeve having a fastening portion that is connected to the inner shaft, wherein the inner shaft is configured at least in part as a hollow shaft that has an interior that is open towards an end that is inserted into the hollow outer shaft, wherein the fastening portion extends from the end into the interior of the inner shaft and is connected to an inner surface of the interior.

13. The length-adjustable steering shaft of claim 12 wherein the fastening portion has a radial outer surface that is connected to an inner surface that radially delimits the interior.

14. The length-adjustable steering shaft of claim 12 wherein the fastening portion is tubular.

15. The length-adjustable steering shaft of claim 12 comprising mutually corresponding connecting elements that are connected to one another and are disposed on the inner surface and on the fastening portion.

16. The length-adjustable steering shaft of claim 12 comprising a form-fitting element disposed on the inner shaft, the form-fitting element protruding radially inwards from the inner surface of the interior, wherein the form-fitting element is configured to be brought into form-fitting engagement with a form-fitting receiver of the fastening portion.

17. The length-adjustable steering shaft of claim 16 wherein the form-fitting element is caulking.

18. The length-adjustable steering shaft of claim 12 wherein the fastening portion is cup-shaped, with a cup base disposed axially spaced apart from an end face of the inner shaft.

19. The length-adjustable steering shaft of claim 12 wherein the profiled sleeve is comprised of plastic.

20. A method for producing a profiled sleeve, the method comprising: injecting a molten plastic melt through an injection channel into a mold cavity of an injection mold that has an axially extended hollow profile space with an end-face end; positioning a disk-shaped, radially extended sprue space inside the axially extended hollow profile space at a distance from the end-face end and at a radial distance, wherein the disk-shaped, radially extended sprue space is connected via mold channels, which are directed axially towards an end contrary to an axial direction of the axially extended hollow profile space, to a connecting space disposed at an end face, wherein the connecting space is connected to the axially extended hollow profile space; wherein the molten plastic melt is injected in the axial direction centrally into the disk-shaped, radially extended sprue space and is introduced axially into the axially extended hollow profile space via the mold channels and the connecting space.

21. The method of claim 20 wherein the molten plastic melt is backed up in the disk-shaped, radially extended sprue space before the molten plastic melt enters the axially extended hollow profile space.

22. The method of claim 20 wherein the molten plastic melt is backed up in the connecting space before the molten plastic melt enters the axially extended hollow profile space.

23. The method of claim 20 wherein the molten plastic melt is backed up in the disk-shaped, radially extended sprue space and the connecting space before the molten plastic melt enters the axially extended hollow profile space.

24. The length-adjustable steering shaft of claim 12 produced according to the method of claim 20.

Description

DESCRIPTION OF THE DRAWINGS

[0031] Advantageous embodiments of the invention will be explained in greater detail hereinbelow with reference to the drawings. Specifically:

[0032] FIG. 1 shows a steering shaft according to the invention in a schematic perspective view,

[0033] FIG. 2 shows a detail of the steering shaft from FIG. 1 in an exploded view,

[0034] FIG. 3 shows the inner shaft of the steering shaft according to FIGS. 1 and 2 and the profiled sleeve in an exploded view,

[0035] FIG. 4 shows a longitudinal section through the inner shaft according to FIGS. 2 and 3 in the assembled state,

[0036] FIG. 5 shows a longitudinal section similar to FIG. 4 in a second angular orientation,

[0037] FIG. 6 shows an injection mold for producing a profiled sleeve according to the invention in a first phase at the start of the injection molding operation,

[0038] FIG. 7 shows the injection mold according to FIG. 6 in a second phase of the injection molding operation,

[0039] FIG. 8 shows the injection mold according to FIG. 7 in a further phase at the end of the injection molding operation,

[0040] FIG. 9 is an axial view of a profiled sleeve according to the invention,

[0041] FIG. 10 shows a longitudinal section through a profiled sleeve according to FIG. 9.

EMBODIMENTS OF THE INVENTION

[0042] In the various figures, identical parts are always provided with the same reference signs and will therefore generally also be named or mentioned only once in each case.

[0043] FIG. 1 shows a length-adjustable steering shaft 1 which extends along an axis L (longitudinal axis) and has an inner shaft 2 and an outer shaft 3. The outer shaft 3 has at its outer end, which is on the right in the drawing, an attachment portion 31 for rotationally fixed connection to a vehicle steering system, not shown, for example to a steering spindle of a steering column. For example, a clampable fork can be used for this purpose. On its side facing the inner shaft 2, the outer shaft 3 is configured as a hollow shaft, which has in its opening 32 that is open towards the inner shaft 2 (see FIG. 2) an internal toothing with radially inwardly protruding teeth extended in the longitudinal direction. The teeth are formed in the outer shaft 3 by deformations introduced into the outer shaft 3 from the outside.

[0044] The inner shaft 2 has at its outer end remote from the outer shaft 3 an attachment portion 21, for example a fork for rotationally fixed connection to a further shaft of a vehicle steering system, not shown. The fork forms part of a universal joint, not shown.

[0045] At its end region facing the outer shaft 3, the inner shaft 2 has a toothing portion 22 which has an external toothing with teeth extended in the longitudinal direction, which can be seen in FIGS. 2, 3, 4 and 5. The toothing portion 22 preferably extends over a portion of the inner shaft 2. A profiled sleeve 4 according to the invention is fitted on the toothing portion 22. With a bearing portion 41, the profiled sleeve 4 encloses an end region of the toothing portion 22 from the outside, wherein the wall of the bearing portion 41 follows the contour of the teeth in cross section, that is to say is configured so as to correspond to the toothing profile of the toothing portion 22.

[0046] With the toothing portion 22 and the profiled sleeve 4 fitted thereon, the inner shaft 2, for assembly, is inserted axially into the opening 32 of the outer shaft 3, as indicated in FIG. 2 by the arrow. In the inserted state, the toothing portion 22 engages with the profiled sleeve 4 fitted thereon into the internal toothing of the outer shaft 3 in a rotationally fixed manner, wherein the bearing portion 41 is located between the toothing portion 22 and the internal toothing. The inner shaft 2 and the outer shaft 3 are thus rotationally fixed for the transmission of torque but axially movable between the attachment portions 21 and 31 for length adjustment, as indicated in FIG. 1 by the double arrow.

[0047] The inner shaft 2 and the outer shaft 3 are usually manufactured from steel, and the profiled sleeve 4 is usually manufactured from a plastics material, preferably from a thermoplastic polymer by the injection molding method, so that a smooth sliding bearing of the adjustment in the longitudinal direction is produced by the bearing portion 41. It is, however, also conceivable and possible to produce the inner shaft 2 and/or the outer shaft 3 from an aluminum alloy.

[0048] FIG. 3 shows the profiled sleeve 4 separated from the inner shaft 2. FIGS. 4 and 5 show the toothing portion 22 with the profiled sleeve 4 fixed thereto in different orientations with respect to the axis L.

[0049] The inner shaft 2 is configured as a hollow shaft in the region of the toothing portion 22, with an interior 23 which is open at the end and in the assembled state has an opening which is open towards the outer shaft 3.

[0050] It can be seen from the sections shown in FIGS. 4 and 5, which depict the assembled state of FIG. 2, that the bearing portion 41, lying against the outside, extends over the toothing portion 21. The profiled sleeve 4 has according to the invention a fastening portion 42, which is inserted through the end-face axial opening into the interior 23 of the inner shaft 2. The fastening portion 42 is connected to the bearing portion 41 via an end-face connecting portion 43.

[0051] In the embodiment shown, the fastening portion 42 is cup-shaped and has a tube portion 44 and a cup base 45. The tube portion 44 extends through the end-face opening along the inner wall into the interior 23, wherein the disk-shaped cup base 45 is located in the interior 23 at a distance from the end. The end region of the wall, having the toothing portion 21, of the inner shaft 2, which in this region is hollow, is located radially between the fastening portion 42 and the bearing portion 21. The fastening portion 42 engages around the end of the inner shaft 2.

[0052] The fastening portion 42 has on its outer circumference radial recesses 46, which can be in the form of openings in the tube portion 44. The inner shaft 2 has projections 24 protruding radially inwards into the interior. The projections 24 engage in a form-fitting manner into the radial recesses 46, so that a form-fitting connection that is effective in the axial direction is produced in that the projections 24 cooperate in a form-fitting manner in the axial direction, that is to say in the direction of the longitudinal axis L, with the base portion 45 and are in engagement therewith. Preferably a plurality of projections 24 and corresponding recesses 46—in the example shown four—are arranged distributed over the circumference, preferably arranged distributed uniformly over the circumference. Preferably two or three or four recesses 46 are provided, and projections 24 are provided in a correspondingly equal number matching the number of recesses 46.

[0053] The projections 24 can be in the form of plastic caulkings which can be cold formed into the end-face edge of the interior 23. The form of the projections 24 and the engagement into the recesses 46 can be seen particularly clearly in FIG. 5, which shows a section through form-fitting connections lying in the sectional plane.

[0054] The form-fitting connections formed in the interior 23 by the projections 24 and the recesses 46 effect a secure form-fitting connection of the profiled sleeve 4 to the inner shaft 2. It is advantageous thereby that there are no connecting means on the outside of the inner shaft 2, so that the bearing portion 41 can be made relatively longer and cannot be impaired by the fastening.

[0055] A profiled sleeve 2 according to the invention is shown separately in an axial view in FIG. 9 and in longitudinal section in FIG. 10. The cup-shaped fastening portion 42 with the tube portion 44 and the radial recesses 46 formed therein as openings are clearly visible therein. The recesses 46 can, as shown, preferably adjoin the cup base 45. As a result, the projections 24 can be supported axially against the cup base 45 in the assembled state and provide the form-fitting connection between the inner shaft 2 and the profiled sleeve 4.

[0056] A sprue 47 is located centrally on the cup base 45.

[0057] The plastics injection molding operation manufacture of a profiled sleeve 2 by the method according to the invention is shown schematically in FIGS. 6, 7 and 8, which show an injection mold 5 schematically in section in successive filling states. Between an outer mold 51 and a core 52 there is formed a mold cavity, which comprises a hollow profile space 53 for the bearing portion 21, which is connected to a connecting space 54 for molding the connecting portion 43. Mold channels 55 are thus connected at the end face, which mold channels delimit the tube portion 44. The mold channels 55 start from a sprue space 56, which is located inside the hollow profile space 53 and delimits the disk-shaped cup base 45. A sprue channel 57 opens centrally into the sprue space 56 from outside, through which sprue channel the molten plastics material is injected in a central sprue point.

[0058] The plastics melt is shown by crosshatching. At the start of the injection operation, the plastics material—as shown in FIG. 6—is injected via the sprue channel 57 centrally into the sprue space 56 and spreads radially outwards therein in all directions, as indicated by the arrows. From there, the plastics melt enters the mold channels 55 and, from there, the connecting space 54. As soon as the connecting space 54 is full, the flow front, which is closed over the circumference, moves in the axial direction into the hollow profile space 53, as is shown in FIG. 7, until this is completely full, as shown in FIG. 8. The core 52 can then be withdrawn axially from the outer mold 51 in the direction indicated by the arrow and, when the plastics melt has solidified, the finished profiled sleeve 4 can be removed.

[0059] Because the sprue space 55 has a flow cross section which is larger than that of the mold channels 54, and in particular is larger than the cross section of the hollow profile space 53, the plastics melt is backed up as it is injected, and it is ensured that a flow front that is closed in the circumferential direction forms, which effects uniform axial filling of the hollow profile space 53 without undesirable joint lines.

LIST OF REFERENCE SIGNS

[0060] 1 steering column [0061] 2 inner shaft [0062] 21 attachment portion [0063] 22 toothing portion [0064] 23 interior [0065] 24 projections [0066] 24 projections [0067] 3 outer shaft [0068] 31 attachment portion [0069] 32 opening [0070] 4 profiled sleeve [0071] 41 bearing portion [0072] 42 fastening portion [0073] 43 connecting portion [0074] 44 tube portion [0075] 45 cup base [0076] 46 recesses [0077] 47 sprue [0078] 5 injection mold [0079] 51 outer mold [0080] 52 core [0081] 53 hollow profile space [0082] 54 connecting space [0083] 55 mold channels [0084] 56 sprue space [0085] 57 sprue channel [0086] L axis (longitudinal axis)