STEERING SHAFT FOR A MOTOR VEHICLE

Abstract

A steering shaft for a motor vehicle may include a first shaft part and a second shaft part. The first and second shaft parts may be connected in a way such that torques are transferred. A damping element can be disposed between the first and second shaft parts for damping oscillations and/or vibrations. The damping element may contact a carrier along a contact area. The damping element may be coupled to the carrier at only a portion of the contact area. The carrier may be, for example, the first shaft part, the second shaft part, a sleeve, or a bushing.

Claims

1.-10. (canceled)

11. A steering shaft for a motor vehicle comprising: a first shaft part connected to a second shaft part for transferring torques between the first and second shaft parts; and a damping element disposed between the first shaft part and the second shaft part, the damping element for damping at least one of oscillations or vibrations, wherein the damping element contacts a carrier along a contact area and is coupled to the carrier only at a fixing region, wherein the fixing region occupies only a portion of the contact area.

12. The steering shaft of claim 11 wherein the carrier to which the damping element is connected is one of the first shaft part, the second shaft part, a bushing, or a sleeve.

13. The steering shaft of claim 11 wherein friction between the carrier and the damping element exists in a region of the contact area outside of the fixing region.

14. The steering shaft of claim 11 wherein the carrier is the first shaft part, the second shaft part, a sleeve disposed between the first shaft part and the second shaft part, or one of two or more sleeves disposed between the first shaft part and the second shaft part.

15. The steering shaft of claim 11 further comprising an inner sleeve and an outer sleeve, the inner and outer sleeves disposed between the first and second shaft parts, wherein the damping element is disposed between the inner and outer sleeves, wherein the carrier is the first shaft part, the second shaft part, the inner sleeve, or the outer sleeve.

16. The steering shaft of claim 11 wherein in the fixing region the damping element is coupled to the carrier by at least one of an adhesive or a material bond.

17. The steering shaft of claim 11 wherein the damping element is disposed under a radial pre-stress between the first and second shaft parts, between the first shaft part or the second shaft part and a sleeve, or between a first sleeve and a second sleeve.

18. The steering shaft of claim 11 wherein the damping element provides an elastic connection between the first and second shaft parts.

19. The steering shaft of claim 18 wherein the first shaft part is positively connected loosely with the second shaft part for transferring a torque.

20. The steering shaft of claim 19 wherein the damping element is disposed between an inner sleeve and an outer sleeve, with the inner sleeve being in non-rotatable contact with the second shaft part and the outer sleeve being in non-rotatable contact with the first shaft part, wherein the loose positive connection is between the outer sleeve and the inner sleeve.

21. The steering shaft of claim 11 wherein the fixing region is in a form of at least one strip that extends in a peripheral direction about an entire perimeter of either the damping element or the carrier.

22. The steering shaft of claim 11 wherein the fixing region occupies 5% to 95% of the contact area.

23. The steering shaft of claim 11 wherein the fixing region occupies 5% to 40% of the contact area.

24. The steering shaft of claim 11 wherein the fixing region occupies 5% to 70% of the contact area.

25. A steering shaft for a motor vehicle comprising: a first shaft part connected to a second shaft part in a way such that torques are transferred between the first and second shaft parts; and a damping element disposed between the first shaft part and the second shaft part, the damping element for damping at least one of oscillations or vibrations, wherein the damping element is coupled to the carrier only at a first fixing region and a second fixing region, wherein at a location between the first and second fixing regions a radial gap exists between the carrier and the damping element.

26. The steering shaft of claim 25 wherein the carrier to which the damping element is connected is one of the first shaft part, the second shaft part, a bushing, or a sleeve.

27. The steering shaft of claim 25 wherein the carrier is the first shaft part, wherein the carrier comprises transition ramps between the first and second fixing regions and a portion of the first shaft part that is aligned with the radial gap between the carrier and the damping element.

28. The steering shaft of claim 25 further comprising an inner sleeve and an outer sleeve, the inner and outer sleeves disposed between the first and second shaft parts, wherein the damping element is disposed between the inner and outer sleeves, wherein the carrier is the first shaft part, the second shaft part, the inner sleeve, or the outer sleeve.

29. The steering shaft of claim 25 wherein in the fixing region the damping element is coupled to the carrier by at least one of an adhesive or a material bond.

Description

SHORT DESCRIPTION OF THE FIGURES

[0023] Preferred further embodiments and aspects of the present invention are described in greater detail by the following description of the Figures, in which

[0024] FIG. 1 shows a steering shaft with a first shaft part and a second shaft part, between which a first example of a damping element is disposed;

[0025] FIG. 2 shows a diagrammatic sectional view of a steering shaft for a motor vehicle in a longitudinal section in a second example;

[0026] FIG. 3 shows a transverse section of the steering shaft of FIG. 2 along the section B-B; and

[0027] FIG. 4 shows a diagrammatic view of a further embodiment of the invention analogous to FIG. 1.

DETAILED DESCRIPTION OF PREFERRED EXAMPLES

[0028] In the following, preferred examples are described by means of the Figures. Identical, similar or equivalent elements in the different Figures have identical reference numbers and a repeated description of these elements is partly omitted in the following description, in order to avoid redundancies.

[0029] In FIG. 1, a steering shaft 1 is shown, which comprises a first shaft part 2 and a second shaft part 3. Between the first shaft part 2 and the second shaft part 3, a damping element 4 is disposed, which has a first contact area of 40, which lies against an inner wall 20 of the first shaft part 2. Furthermore, the damping element 4 has a second contact area 42, which lies against an outer wall 30 of the second shaft part 3.

[0030] In the example shown, the damping element 4 is provided in the form of an elastomeric layer, which is disposed between the first shaft part 2 and the second shaft part 3. However, the damping element 4 may also have any other design and materials as long as it provides the desired damping properties. In this connection, damping elements of rubber and elastic plastics, especially of elastomeric plastics, are preferred.

[0031] The damping element 4 is firmly connected with the first shaft part 2 in two partial regions 44, 46 of the contact area 40. In order to produce this firm connection, a bonding agent is applied, by means of which a substance-to-substance connection between the damping element 4 and a first shaft part 2 is attained by vulcanization only in the fixing regions 44, 46 of the contact area 40.

[0032] In the example shown, the carrier is formed by the first shaft part 2. However, as can be seen in the following, the carrier, to which the damping element 4 is attached, may also be formed by the second shaft part 3, by a first sleeve 5 (see FIG. 3), which is disposed between the first shaft part 2 and the second shaft part 3, and/or by a second sleeve 6, which is disposed between the first shaft part 2 and the second shaft part 3.

[0033] On the other hand, in the region 48 of the first contact area 40 of the damping element 4, which is disposed between the connected fixing regions 44, 46 of the contact area 40 and not connected with the shaft part 2, the damping element 4 is not firmly connected with the first shaft part 2. In this region 48, the damping element 4 only lies in contact with the inner wall 20 of the first shaft part 2. This contact may vary from a loose contact with clearance up to a press fit.

[0034] With that, the damping element 4 may be shifted with respect to the carrier, that is, in the first shaft part 2 in the not connected region 48. Depending on the respective surface nature or material nature of the inner wall 20 of the first shaft part 2 and of the contact area 40 of the damping element 4, corresponding friction, which dampens the displaceability of the damping element 4 with respect to the first shaft part 2, is also present in the region 48, which is not connected.

[0035] Depending on the thickness of the damping element 4, the latter may be disposed under a radial pre-stressing between the first shaft part 2 and the second shaft part 3. Correspondingly, in the partial region 48 of the first contact area 40 of the damping element 4, which is not connected with the first shaft part 2, there admittedly is a radial pre-stressing of the damping element 4, but no firm connection. Rather, in this not connected region 48 of the contact area 40, the damping element 4 can move at least in the axial direction X to a certain extent with respect to the carrier or with respect to the first shaft part 2. Correspondingly, for movement of the region 48, which is not connected with the shaft part 2, with respect to the first shaft part 2, it is only necessary to overcome the friction between the first contact area 40 of the damping element 4 and the inner wall 20 of the first shaft part 2.

[0036] Correspondingly, the damping element 4 in the two firmly connecting fixing regions 44, 46 of the contact area 40 is connected firmly or immovably in the axial direction X with the first shaft part 2 forming the carrier. In the region 48 of the contact area 40, which is not connected with the first shaft part 2, the damping element 4 is, however, movable with respect to the first shaft part 2 at least in the axial direction of the steering shaft 1.

[0037] By dimensioning and disposing the fixing regions 44, 46 of the contact area 40, in which the damping element 4 is firmly connected with the first shaft part 2 formed as the carrier, the damping properties of the damping element 4 can be varied at least in the axial direction X and adapted to the particular objective.

[0038] The connection of the damping element 4 with the first shaft part 2 may be provided as connected fixing regions 44, 46, which extend over the whole periphery of the damping element 4 and are then formed correspondingly as peripheral strips. Advantageously, at least two strips, which are at a distance from one another in the longitudinal direction X (=axial direction X) are provided as a fixing region 44, 46 viewed in the axial direction X. Preferably, the two fixing regions 44, 46 are disposed at the ends of the damping element 4. Advantageously, the strips are formed as closed areas.

[0039] In formations, which are not shown here, firmly connected fixing regions can also be provided as strips, which extend in the axial direction X or diagonally, or as spots, points or as at least two fixing regions, which are not connected with one another, for example, as sectors. Furthermore, the fixing region 44, 46 of the contact area 40, in which the damping element 4 is connected firmly with the carrier, may be constructed in the form of at least one strip, at least one peripheral strip, at least one strip extending in the axial direction X, at least one strip extending diagonally or helically, at least one spot, at least one point or at least two fixing regions, which are not connected with one another.

[0040] The damping element 4 may also be connected firmly with the first shaft part 2 in only a single firmly connected fixing region, such as the fixing region 44, and then, in the remaining not connected region 48, not lie against the first shaft part 2. This may be achieved, for example, by dimensioning the damping element 4 and/or providing an appropriate adhesive, which provides a gap.

[0041] In a further development, which is not shown, the fixing region, in which the damping element 4 is connected firmly with the first shaft part 2, may also extend in the axial direction X, the fixing regions in that case being formed as strips extending in the axial direction, which are not connected with one another or at least leave one region 48 free, in which the damping element 4 is not connected with the first shaft part 2. Any other variations of the fixing regions, in which the damping element 4 is connected with the first shaft part 2, are conceivable, for example, a plurality of fixing regions, which are connected distributed over the contact area 40, in which a connection between the damping element 4 and the first shaft part 2 is produced, or any other arrangements.

[0042] The selective connection of the damping element 4 with the carrier, which does not take place over the entire surface but only in the fixing regions 44, 46, is attained owing to the fact that only the fixing regions 44, 46, in which a firm connection with the carrier is to be produced, are provided with an appropriate bonding agent or an appropriate adhesive, so that the firm connection while gluing or vulcanizing the damping element 4 to the first shaft part 2 is attained correspondingly only in these fixing regions. This can also be attained simply by covering regions of the surface with a template, during the surface treatment for forming the bonding agent. The surface treatment may then be carried out simply by applying the bonding agent on the surface or by a plasma treatment of the surface.

[0043] This firm connection between the damping element 4 and the respective carrier may be attained only on one side of the damping element 4, namely the contact area 40, or also on both sides of the damping element 4, namely on the first contact area 40 as well as on the second contact area 42.

[0044] In FIGS. 2 and 3, a further example of a steering shaft 1 is shown, FIG. 2 showing a sectional view along the axial direction X and FIG. 3 showing a cross-sectional view perpendicular to the axial direction X and along the section B-B of FIG. 2.

[0045] Once again, a first shaft part 2 and a second shaft part 3 are provided. Between the first shaft part 2 and the second shaft part 3, a damping element 4 is shown, which again is constructed as an elastomeric layer. In the example shown, the damping element 4 is taken up between an outer sleeve 5 and an inner sleeve 6, which is radial thereto. In the example shown, the outer sleeve 5 is constructed as the carrier. A connection of the damping element 4 by the first contact area 40 thereof with the outer sleeve 5 takes place in two partial regions 44, 46 of the contact area 40. The intermediate, not connected region 48 of the first contact area 40 of the damping element 4 is not connected with the outer sleeve 5, so that there is displaceability here, at least in the axial direction X of the steering shaft 1.

[0046] As can be seen in FIG. 3, the arrangement of the first shaft part 2, the outer sleeve 5, the inner sleeve 6 and the second shaft part 3 forms a loose positive connection, so that the transfer of a torque from the second shaft part 3 to the first shaft part 2 with clearance would be possible even without the presence of the damping element 4. For this purpose, protrusions 22 are provided at the inner wall 20 of the first shaft part 2 and engage corresponding recesses 52 in the outer wall 50 of the outer sleeve 5. Protrusions 54 in the inner wall 56 of the outer sleeve 5 engage recesses 62 in the outer wall 60 of the inner sleeve 6. The inner sleeve 6 is also connected positively with the second shaft part 3 owing to the fact that protrusions 32 are provided in the outer wall 30 of the second shaft part 3, which engage complementary recesses 64 in the inner wall 66 of the inner sleeve 6.

[0047] The loose positive connection also exists correspondingly, if the damping element 4 is not present or was destroyed by wear.

[0048] The damping element 4 is disposed in the space between the inner wall 56 of the outer sleeve 6 and the outer wall 60 of the inner sleeve 6 and follows the contours of the respective elements. Depending on the dimensioning of the damping element 4, the latter is pre-tensioned at least radially to the outside, so that a clearance-free but elastic transfer of a torque can be attained between the first shaft part 2 and the second shaft part 3.

[0049] A further embodiment of the invention is shown in FIG. 4. In contrast to the embodiment in FIG. 1, a space 49 is disposed between the fixing regions 44, 46 between the inner surface of the first shaft part 2 and the damping element. In this region, there is therefore no contact between the damping element 4 and the shaft part 2. A transition to the respective fixing regions is created by ramps 201 in the inner wall 20. In this way, the partial fixing of the damping element can also be prepared with a simple press fit. However, this variation is less flexible and therefore less preferred.

[0050] The damping properties of the system, especially in relation to the damping properties in the axial direction X, can be adjusted by the dimensioning or the variation of the dimensioning of the fixing regions 44, 46 of the contact area 40, in which the damping element 4 is firmly connected with the outer sleeve 5, in relation to the in-between region 48 of the contact area 40, in which such a firm connection is not present.

[0051] The arrangement of the outer sleeve 5, the damping element 4 and the inner sleeve 6 can also be provided separately and installed as a bearing bushing.

[0052] In so far as is applicable, all individual features, which are presented in the individual examples, can be combined with one another and/or exchanged, without leaving the scope of the invention.

LIST OF REFERENCE NUMBERS

[0053] 1 steering shaft [0054] 2 first shaft part [0055] 20 inner wall [0056] 201 ramp [0057] 22 protrusion [0058] 3 second shaft part [0059] 30 outer wall [0060] 32 protrusion [0061] 4 damping element [0062] 40 first contact area [0063] 42 second contact area [0064] 44 fixing region or firmly connected partial region [0065] 46 fixing region or firmly connected partial region [0066] 48 not connected region [0067] 49 space [0068] 5 outer sleeve [0069] 50 outer wall [0070] 52 recess [0071] 54 protrusion [0072] 56 inner wall [0073] 6 inner sleeve [0074] 60 outer wall [0075] 62 recess [0076] 64 recess [0077] 66 inner wall [0078] X axial direction