Steering shaft for a motor vehicle

Abstract

A steering shaft for a motor vehicle includes a hollow outer shaft with a longitudinal axis. An inner shaft is arranged coaxially within the outer shaft. The inner shaft telescopes longitudinally relative to the outer shaft and is connected in a torque-transmitting manner to the outer shaft via a rolling body. The rolling body can roll in the direction of the longitudinal axis and the rolling body bearing in a positively locking manner in the circumferential direction about the longitudinal axis between rolling body raceways on the inner and outer shaft. The steering shaft includes a securing element with a supporting body arranged between supporting faces configured on the inner shaft and on the outer shaft, which at least one supporting body can be supported in a positively locking manner in the circumferential direction. The supporting body is spaced apart in the circumferential direction from the supporting faces.

Claims

1. A steering shaft for a motor vehicle, comprising: a hollow outer shaft; an inner shaft arranged coaxially in the outer shaft; the inner shaft configured to telescope relative to the outer shaft in the direction of a longitudinal axis of the steering shaft, the inner shaft connected in a torque-transmitting manner to the outer shaft via rolling bodies, wherein the steering shaft is configured to permit the rolling bodies to roll in the direction of the longitudinal axis, wherein the rolling bodies bear in a positively locking manner in the circumferential direction with regard to a rotation about the longitudinal axis between rolling body raceways formed on the inner shaft and on the outer shaft; and a securing element including a supporting body arranged between supporting faces configured on the inner shaft and on the outer shaft and supported in a positively locking manner in the circumferential direction, wherein the securing element is clamped fixedly and directly to the supporting faces of the inner shaft, wherein the supporting body is spaced apart in the circumferential direction from the supporting faces on the outer shaft.

2. The steering shaft of claim 1, wherein the supporting body is arranged between the rolling body raceways, the supporting faces being configured in the region of the rolling body raceways.

3. The steering shaft of claim 1, wherein the supporting body has a smaller dimension in the circumferential direction between rolling faces of the rolling bodies on at least one of the rolling body raceways than a rolling body.

4. The steering shaft of claim 1, wherein the securing element has a carrier part, to which the supporting body is attached.

5. The steering shaft of claim 4, wherein the carrier part extends in a laminar manner in a cross-sectional plane perpendicularly with respect to the longitudinal axis, and the supporting body projects from the carrier part in the direction of the longitudinal axis.

6. The steering shaft of claim 4, wherein at least two supporting bodies are arranged in a mirror-symmetrical manner relative to the longitudinal axis.

7. The steering shaft of claim 4, wherein at least two supporting bodies are pressed by the carrier part with respect to one another in a sprung manner against the inner shaft or the outer shaft.

8. The steering shaft of claim 1, wherein the securing element is a single-piece shaped sheet metal construction, the supporting body being configured as a bent portion.

9. The steering shaft of claim 1 wherein the supporting faces are supporting faces of the rolling body raceways.

10. The steering shaft of claim 1 wherein the securing element comprises a planar carrier part to which the supporting body is attached, wherein the planar carrier part is cross-shaped.

11. A steering shaft for a motor vehicle comprising: a hollow outer shaft; an inner shaft arranged coaxially in the outer shaft, wherein the inner shaft is configured to telescope relative to the outer shaft in a direction of a longitudinal axis of the steering shaft, wherein the inner shaft is connected in a torque-transmitting manner to the outer shaft via rolling bodies, wherein the rolling bodies are configured to roll in the direction of the longitudinal axis, wherein the rolling bodies bear in a positively locking manner in a circumferential direction with regard to a rotation about the longitudinal axis between rolling body raceways formed on the inner shaft and on the outer shaft; and a securing element including a supporting body arranged between supporting faces configured on the inner shaft and on the outer shaft and supported in a positively locking manner in the circumferential direction, wherein the securing element is attached to a longitudinal end of the outer shaft and protrudes longitudinally from the outer shaft, wherein the supporting body is spaced apart from the supporting faces of the inner shaft, wherein the securing element is comprised of a first securing element and a second securing element, wherein the first securing element is circumferentially spaced apart from the second securing element and is only indirectly connected to the second securing element, wherein the first and second securing elements are indirectly connected via the outer shaft.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 is a diagram view of a steering shaft.

(2) FIG. 2 is a diagram view of a part of a steering shaft in accordance with FIG. 1 in the dismantled state.

(3) FIG. 3 is a cross-sectional view of a steering shaft in accordance with the preceding figures.

(4) FIG. 4 is a partial perspective view of a diagram of a cross section A-A through a steering shaft in accordance with FIG. 1.

(5) FIG. 4a is a cross-sectional view of a detailed part of the steering shaft in accordance with the preceding figures.

(6) FIG. 5 is a perspective view of the steering shaft in accordance with FIG. 4 in the dismantled state.

(7) FIG. 6 is a perspective view of the steering shaft in accordance with FIG. 5 in the further dismantled state.

(8) FIG. 7 is a perspective view of a second embodiment of a steering shaft in a similar illustration to FIG. 6.

(9) FIG. 8 is a perspective view of a securing element of the steering shaft in accordance with FIG. 7.

(10) FIG. 9 is a perspective view of an inner shaft of a steering shaft in a third embodiment.

(11) FIG. 10 is a perspective view of an inner shaft of a steering shaft in a fourth embodiment.

(12) FIG. 11 is a partial perspective diagram of a steering shaft in a fifth embodiment.

(13) FIG. 12 is a cross-sectional view of the steering column in accordance with FIG. 11.

(14) FIG. 13 is a perspective view of still another example securing element that can be secured to a longitudinal end of an outer shaft and can permit an inner shaft to pass through its central opening.

(15) FIG. 14 is another perspective view of the securing element shown in FIG. 13.

(16) FIG. 15 is a detail perspective view of the example cage shown in FIG. 2.

DETAILED DESCRIPTION

(17) Although certain example methods and apparatus have been described herein, the scope of coverage of this patent is not limited thereto. On the contrary, this patent covers all methods, apparatus, and articles of manufacture fairly falling within the scope of the appended claims either literally or under the doctrine of equivalents. Moreover, those having ordinary skill in the art will understand that reciting “a” element or “an” element in the appended claims does not restrict those claims to articles, apparatuses, systems, methods, or the like having only one of that element, even where other elements in the same claim or different claims are preceded by “at least one” or similar language. Similarly, it should be understood that the steps of any method claims need not necessarily be performed in the order in which they are recited, unless so required by the context of the claims. In addition, all references to one skilled in the art shall be understood to refer to one having ordinary skill in the art.

(18) FIG. 1 shows a perspective view of a diagrammatically shown steering shaft 10 which has an outer shaft 20 (also called an outer hollow shaft) and an inner shaft 30 (also called an inner hollow shaft) which can be telescoped relative to one another in the direction of the longitudinal axis L, that is to say in the longitudinal direction which is indicated by way of the double arrow.

(19) At its outer free end which faces away from the inner shaft 30 in the longitudinal direction, the outer shaft 20 has a fork 21 which forms a part of a universal joint, by way of which the steering shaft 10 is connected to the steering train in a torque-transmitting manner. Correspondingly, at its free end which faces away from the outer shaft 20 in the longitudinal direction, the inner shaft 30 has a fork 31 which forms a part of a further universal joint, by way of which the steering shaft 10 is connected to the steering train in a torque-transmitting manner. The inner shaft 20 and the outer shaft 30 are preferably manufactured from steel which can be cold worked satisfactorily.

(20) A stop element 70 which acts in the direction of the longitudinal axis of the steering shaft 10 is inserted into the opening of the outer shaft 20. The inner shaft 30 is guided through such that it can be displaced by way of the stop element 70.

(21) FIG. 2 shows a part of the steering shaft 1 in accordance with FIG. 1 in an exploded illustration, in the case of which the individual constituent parts are shown in the dismantled state. It is apparent from this that the outer shaft 20 is profiled in its circumferential region which faces the inner shaft 30 and into which the inner shaft 30 can be pushed in a telescoping manner in the longitudinal direction. The profiling of the outer shaft 20 comprises grooves 22 which extend in the longitudinal direction in the inner casing surface 23. Convexly projecting bead-like shaped-out formations 24 are configured in the outer casing surface 25 so as to lie opposite the grooves 22 on the outside with regard to the wall of the outer shaft 20. In the embodiment which is shown, both the inner shaft 30 and the outer shaft 20 are configured as hollow profiles with a substantially square cross-sectional basic shape. Here, a total of four grooves 22 are arranged distributed uniformly over the circumference of the outer shaft 20, namely in each case in the center of one of the sides of said square cross section. The grooves 22 are configured as rolling body raceways, specifically as ball raceways.

(22) That end section of the inner shaft 30 which faces the outer shaft 20 and can be pushed into the latter in a telescoping manner (as shown in FIG. 1) is likewise profiled. The profiling comprises grooves 32 which extend from the end which can be plugged into the outer shaft 20 in the outer casing surface 33 of the inner shaft 30 in the longitudinal direction, that is to say in the direction of the longitudinal axis L. The grooves 32 extend over that part section of the inner shaft 30 which can be pushed into the outer shaft 20 in the longitudinal direction.

(23) A securing element 9 according to the invention which will be described in greater detail further below is arranged on the inner shaft 30 in the region of its end side 33 which faces the end side 26 of the outer shaft 20 and is situated within the outer shaft 20 in the assembled state.

(24) It can be seen clearly from FIG. 2 in combination with the cross-sectional illustration in FIG. 3 how rolling bodies, namely balls 40, are arranged radially between the grooves 22 and 32. A plurality of balls 40 are arranged behind one another in the longitudinal direction in each case in the grooves 22 and 32. Here, they can be rotated freely in a sleeve-shaped rolling body cage or ball cage 80, as shown in FIG. 2 and more closely in FIG. 15, such that they are held at a defined spacing relative to one another. A ball or balls 40 may be secured such that it/they can roll in the cage 80, which is movable relative to the inner shaft 30 and to the outer shaft 20 in the direction of the longitudinal axis L.

(25) The embodiment which is shown in FIG. 3 shows a rectangular, specifically a square, base cross section of the shafts 20 and 30. The grooves 22 and 32 are arranged in each case centrally in one side of the square symmetrically with respect to the longitudinal axis L.

(26) The balls 40 have a diameter D and are received in each case between grooves 22 and 32 which lie opposite one another in pairs such that said balls 40 can roll in the longitudinal direction. The balls 40 bear substantially without play by way of their circular cross section against contact faces 220 and 320 in the grooves 22 and 32. As a result, the balls 40 form positively locking elements which establish a positively locking connection which acts in the circumferential direction between the grooves 22 and 32 and which, as a result, connect the inner shaft 30 and the outer shaft 20 to one another in a positively locking manner with regard to a rotation about the longitudinal axis L.

(27) The configuration of a securing element 9 in a first embodiment is shown in FIG. 4. In said figure, the outer shaft 20 is cut away in the cross section A-A in the assembled state in accordance with FIG. 1, and reveals a view of the end side 33 of the inner shaft 30. FIG. 4 shows the securing element 9 in the installed position within the steering column 10, FIG. 4a shows a detailed part of a cross-sectional view of the steering shaft, FIG. 5 shows a perspective illustration in the dismantled state in accordance with FIG. 2, and FIG. 6 shows said securing element 9 on its own in the state, in which it has been removed from the inner shaft 30.

(28) The securing element 9 has a strip-shaped, flat carrier part 91 which extends radially over the end side 33 in a manner which bears against said end side 33 transversely with respect to the longitudinal axis L, that is to say said carrier part 91 is arranged parallel to a cross-sectional area. Supporting bodies 92 are attached to the carrier part 91 at the end regions which lie opposite one another with regard to the longitudinal axis L. The supporting bodies 92 project from the carrier part 91 in the longitudinal direction against the end side 33, and are shaped in the example which is shown as bent portions about bending axes U which lie in each case transversely with respect to the longitudinal axis L and with respect to the radial extent of the carrier part 91, that is to say in the circumferential direction. As a result, the securing element 9 has a bracket-shaped basic shape.

(29) The supporting bodies 92 have free end regions 93 which are bent over by approximately 180° in relation to the radial extent of the carrier part 91, to be precise so as to point counter to one another in the direction of the spring force F which is indicated by way of the arrows in FIG. 6 and will be described further below.

(30) In the installed position in accordance with FIGS. 4 and 5, the end regions 93 which lie radially opposite one another engage into opposite grooves 32 of the inner shaft 30. By virtue of the fact that the carrier element 91 and/or the bent portions of the supporting bodies 92 are/is configured in a spring-elastic manner and the free spacing of the end regions 93 is smaller than the diameter of the inner shaft 30 in the region of the grooves 32 which lie opposite one another, the inner shaft 30 is clamped in between the supporting bodies 92 by way of the spring force F, the free end regions 93 being pressed with their outer edges against the outer surface of the inner shaft 30. In other words, the securing element 9 is clamped fixedly and directly on the inner shaft 30 on the end side, as shown in FIGS. 4 and 5 amongst others. The holding strength of the clamped connection can be increased by virtue of the fact that the end regions 93 have fixing means on their regions which bear against the surface of the inner shaft 30, for example blade-shaped or mandrel-shaped sharp edges which dig into the surface of the inner shaft 30 and ensure a secure seat of the fixing element on the inner shaft 30.

(31) The securing element 9 is preferably configured as a single-piece shaped sheet metal part, to be precise preferably as a stamped bent part made from steel sheet or spring steel sheet. As a result, the supporting bodies 92 are inherently resiliently flexible and are connected to the carrier part 91 in a sprung manner.

(32) In the supporting region 94 which projects beyond the open cross section of the groove 32 and extends into the grooves 22 of the outer shaft 20, the supporting body 92 has a width d which is smaller than the diameter D of the balls 40. As a result, the supporting body 92 is at a spacing a in the circumferential direction from the inner face of the groove 22, as shown in FIG. 4a.

(33) The end region 93 of the supporting body 92 can preferably be formed in such a way that it is inserted in a positively locking manner in the circumferential direction from the outside into the open cross section of a groove 32 of the inner shaft 30, with the result that the securing element 9 is seated fixedly on the end side 33 so as to rotate with it relative to the longitudinal axis L. This ensures that the spacing a between the supporting body 92 and the outer shaft 20 is maintained, with the result that the supporting body 92 is arranged without contact and, in normal operation during the adjustment of the inner shaft 30 in the longitudinal direction, no undesired friction occurs between the supporting body 92 and the outer shaft 20.

(34) If a steering command is introduced via a steering wheel (not shown) into the inner shaft 30 as a torque about the longitudinal axis L, said command is transmitted in normal operation (in the case of intact balls 40 which are situated in the grooves 22 and 32) as a force in the circumferential direction from the inner shaft 30 via the contact faces 320 to the balls 40, and from said balls 40 via the contact faces 220 to the outer shaft 20. In the case of an emergency, if the balls 40 are destroyed or have been removed from the grooves 32 and 22, the supporting bodies 92 come into contact with the inner faces of the grooves 32 which then serve as supporting faces within the context of the invention, for example in the region of the contact faces 220 and 320. Only then do the supporting bodies 92 at the same time come into positively locking contact between the inner shaft 30 and the outer shaft 20, and take the place of the balls 40 which are no longer intact in the case of an emergency. The transmission of torque then takes place from the inner shaft 30 via the supporting body or the supporting bodies 92 and the inner faces of the grooves to the outer shaft 20.

(35) The advantageous effects which have been described can likewise be achieved by way of the embodiment (shown in FIGS. 7 and 8) of another example securing element 1000. Like the first embodiment, this embodiment is likewise manufactured as a single-piece stamped bent part preferably made from steel sheet or spring steel sheet. In contrast to the first embodiment, the carrier part 1002 is narrower, on which the supporting bodies 1004 are integrally formed via additional offsets 95. As a result, the supporting bodies 1004 are offset in the longitudinal direction from the carrier part 1002, and engage into the groove 32 twice, that is to say on both sides.

(36) One alternative embodiment of a securing element 2000 is shown in FIG. 9. Said securing element 2000 has a plate-shaped, flat (or “planar”) carrier part 2002 which is of cross-shaped configuration with four radially projecting arms. Substantially cylindrical supporting bodies 921, which are shown as complete cylinders in FIG. 9, are attached to the arms, the axial directions of which supporting bodies 921 lie parallel to the longitudinal axis L. As in the case of the above-described embodiments, the carrier part 2002 is arranged parallel to the end side 33 of the inner shaft 30. Likewise as described, the securing element 2000 can be clamped fixedly between the supporting bodies 921 on the inner shaft 30. The diameter d of the supporting bodies 921 is once again smaller than the diameter D of the balls 40, with the result that, in the case of intact balls 40, the supporting bodies 921 are at a spacing from the contact faces 220 of the grooves 22 and are therefore at a spacing in the circumferential direction from supporting faces of the outer shaft 20.

(37) The carrier part 2002 can be configured, for example, as a plastic part, for example as an injection molded plastic part, or as an alternative as a stamped sheet metal part. The supporting bodies 921 which can preferably consist of a resistant, durable material such as steel can be integrally molded on the carrier part 2002, or can be connected in an integrally joined, positively locking and/or non-positive manner. It can be provided in one embodiment (not shown) that the carrier part 2002 is fixed on the inner shaft by means of a screw. To this end, a threaded bore is provided in the end side 33 of the inner shaft 30, into which threaded bore the screw is screwed. As an alternative, it can also be provided that the carrier part 2002 is fixed on the end side 33 of the inner shaft 30 by means of a spot welding operation.

(38) A further alternative embodiment is shown in FIG. 10. This example securing element 3000 is a bent part made from profile material, from a wire with a round cross section in the example which is shown, which has a diameter d which is smaller than the diameter D of the balls 40. The supporting bodies 3002, connected by a carrier part 3004, are once again formed by way of simple bent portions which engage into the grooves 32 on the end side 33 of the inner shaft 30.

(39) One alternative embodiment of the invention is shown in FIGS. 11 and 12. This design has a carrier part 910 and a supporting body 920. A holding slot is delimited by the carrier part 910 and the section which is bent back substantially by 180° in a U-shaped manner, by way of which holding slot the securing element 90 is plugged in a clip-like manner onto the wall in the end-side region of the opening of the outer shaft 20, with the result that the carrier part 910 extends on the outside on the outer shaft 20, and the bent-over section which forms the supporting body 920 dips into the opening cross section of the outer shaft 20. In other words, as shown in FIGS. 11 and 12, the securing element or elements 90 may be attached to a longitudinal end of the outer shaft 20 and may protrude longitudinally from the outer shaft 20. The carrier part 910 has spring-elastic holding sections 28 which bear from the outside against the outer shaft 20 in a sprung manner and, as a result, clamp the securing element 90 fixedly.

(40) The inner shaft 30 has a polygonal cross section with a square basic shape, with grooves 32 which run in the edge regions. Supporting faces 27 are situated along the grooves 32. In the operating state which is shown, the supporting faces 27 are at the spacing a from the supporting bodies 920, and therefore do not establish a connection between the inner shaft 30 and the outer shaft 20. Furthermore, FIGS. 11 and 12 show that multiple securing elements 90 may be circumferentially spaced apart and only indirectly connected to one another, in some cases, by the outer shaft 20.

(41) Only in the case of the failure of the rolling bodies in an emergency, a relative rotation of the inner shaft 30 within the outer shaft 20 can occur. The supporting faces 27 then come into contact with a force component in the circumferential direction against the supporting body or the supporting bodies 920, with the result that a transmission of torque can take place from the inner shaft 30 via the securing elements 90 to the outer shaft 20.

(42) The design which is shown in FIGS. 13 and 14 functions in principle in the same way as the above-described embodiment, the securing element 900 having a total of four supporting bodies 4000 which are arranged on a single annular carrier part 911 which is coaxial with respect to the longitudinal axis L. The carrier part 911 is fastened in a cap-like manner on the open end of the outer shaft 20 such that it is secured against rotation, as a result of which the assembly is simplified.

(43) The securing elements 90 and 900 can preferably be manufactured as stamped bent parts made from metal sheet, preferably from steel sheet or spring steel sheet.

LIST OF DESIGNATIONS

(44) 10 Steering shaft 20 Outer shaft 21 Fork 22 Groove 26 End side 220 Contact face 23 Inner casing surface 24 Shaped-out formations 25 Outer casing surface 27 Supporting faces 28 Spring-elastic holding sections 30 Inner shaft 31 Fork 32 Groove 320 Contact face 33 Outer casing surface 33 End side 40 Ball 70 Stop element 80 Rolling body cage 9, 90, 1000, 2000, 3000 Securing element 91, 910, 911, 1002, 2002 Carrier part 92, 920, 921, 1004, 3002, 4000 Supporting body 94 Supporting region 95 Offset a Spacing D Diameter d Width of the supporting element L Longitudinal axis