STEERING COLUMN FOR A MOTOR VEHICLE

Abstract

A steering column for a motor vehicle may include a crash device that has at least two components that have mutually facing surfaces. The at least two components may be connected to each other by means of a shear element that is arranged in an opening passing at least partially through the components such that the shear element is broken in two if the components move relative to each other. To improve the predetermined breaking connection, the opening may have, in at least one edge region bounding one of the mutually facing surfaces, a widened portion that extends at least over a partial circumferential region and is open towards the respective other surface.

Claims

1.-11. (canceled)

12. A steering column for a motor vehicle comprising a crash device with at least two components that have mutually facing surfaces, wherein the at least two components are connected by a shear element that is disposed in an opening passing at least partially through the at least two components such that the shear element is configured to break in two if the at least two components move relative to each other, wherein the opening has in at least an edge region bounding a first of the mutually facing surfaces a widened portion that extends at least over a partial circumferential region and is open towards a second of the mutually facing surfaces.

13. The steering column of claim 12 wherein the mutually facing surfaces are configured as contact surfaces that lie against one another in a shear plane, wherein the opening passes at least partially through the at least two components transversely to the shear plane.

14. The steering column of claim 13 wherein the opening includes at least in some sections a substantially uniform passage cross section that is enlarged in the edge region of the widened portion towards the contact surfaces.

15. The steering column of claim 12 wherein the widened portion has at least one of a chamfer, a rounding, or a shoulder.

16. The steering column of claim 12 wherein the widened portion has a chamfer that encloses with an opening axis of the opening a chamfer angle that is greater than or equal to 20°.

17. The steering column of claim 12 wherein the opening is a bore with a circular cross section.

18. The steering column of claim 12 wherein the shear element is a shear rivet.

19. The steering column of claim 12 wherein a first of the at least two components is connected to a jacket unit rotatably mounting a steering spindle, wherein a second of the at least two components is connected to a support unit that bears the jacket unit and is connectable to a body of the motor vehicle.

20. The steering column of claim 12 wherein the mutually facing surfaces are configured as contact surfaces that lie against one another in a shear plane, wherein at least in a region of the shear plane the shear element is comprised of a material that has a lower strength than a material of at least one of the at least two components.

21. The steering column of claim 12 comprising an energy absorption element that is arranged between the at least two components.

22. A method of operating a steering column for a motor vehicle that includes a crash device with two components that have mutually facing surfaces and that are connected by a shear element that is disposed in an opening passing at least partially through the two components, the method comprising: shearing off the shear element and dividing the shear element into two shear element fragments upon application of a force between the two components that exceeds a predetermined crash force; and plastically shaping at least one of the two shear element fragments into a widened portion configured in at least an edge region of the opening bounding one of the mutually facing surfaces to form a retaining edge that produces a positive connection that acts in a direction of passage of the opening between the at least one of the shear element fragments and the respective component.

Description

DESCRIPTION OF THE DRAWINGS

[0038] Advantageous embodiments of the invention are described in more detail hereinafter with reference to the drawings. In detail:

[0039] FIG. 1 shows a steering column according to the invention in a perspective view,

[0040] FIG. 2 shows the steering column according to FIG. 1 in a further perspective view,

[0041] FIG. 3 shows a detailed view of the steering column according to FIG. 1 in an exploded view,

[0042] FIG. 4 shows a cross section through the steering column according to FIGS. 1 to 3,

[0043] FIG. 5 shows an enlarged detailed view of FIG. 4,

[0044] FIG. 6 shows an enlarged schematic view similar to FIG. 4 of a shear rivet connection according to the invention in a first embodiment in normal operation before being sheared off,

[0045] FIG. 7 shows a view of the shear rivet connection according to FIG. 6 after being sheared off,

[0046] FIG. 8 shows an enlarged schematic view as in FIG. 6 of a shear rivet connection according to the invention in a second embodiment in normal operation before being sheared off,

[0047] FIG. 9 shows a view of the shear rivet connection according to FIG. 8 after being sheared off,

[0048] FIG. 10 shows an enlarged schematic view as in FIG. 6 of a shear rivet connection according to the invention in a third embodiment,

[0049] FIG. 11 shows an enlarged schematic view as in FIG. 6 of a shear rivet connection according to the invention in a fourth embodiment,

[0050] FIG. 12 shows an enlarged schematic view as in FIG. 6 of a shear rivet connection according to the invention in a fifth embodiment,

[0051] FIG. 13 shows a schematic view of a contact surface in a direction of passage of the opening in a first embodiment,

[0052] FIG. 14 shows a schematic view of a contact surface in the direction of passage of the opening in a first embodiment.

EMBODIMENTS OF THE INVENTION

[0053] In the various figures the same parts are always provided with the same reference numerals and thus are generally cited and/or mentioned only once in each case.

[0054] FIG. 1 shows a steering column 1 according to the invention schematically in a perspective view obliquely from the rear (relative to the direction of travel of a motor vehicle, not shown).

[0055] The steering column 1 may be fastened to the body of a motor vehicle, not shown, by means of a support unit (bracket) 2. The support unit 2 comprises fastening means 21, for example fastening openings, for connecting to the body.

[0056] A steering spindle 30 is rotatably mounted in an inner jacket tube 31, also denoted as the internal jacket tube or jacket tube 31, about its longitudinal axis L which extends in the longitudinal direction. A fastening portion 32 is configured at the rear on the steering spindle 30 for fastening a steering wheel, not shown. The inner jacket tube 31 is retained in an outer jacket unit 33, also denoted as the external jacket unit 33 or the jacket unit 33 for short, so as to be displaceable in a telescopic manner in the longitudinal direction, as indicated by the double arrow parallel to the longitudinal axis L.

[0057] A motorized adjusting drive 4 comprises an electrical drive unit 41 with an electric motor which is supported on the outer jacket unit 33 in the longitudinal direction by means of a U-shaped support component 44 and by which a threaded spindle (spindle) 42 extending substantially in the longitudinal direction is rotatably drivable, said threaded spindle being screwed into a spindle nut 43 which is arranged fixedly in terms of rotation relative thereto and which is supported on the inner jacket tube 31 in the longitudinal direction via a support element 45. As a result, a so-called rotary spindle drive is implemented in which, by the threaded spindle 42 being rotatably driven by means of the drive unit 41, the spacing is adjustable in the longitudinal direction between the drive unit 41 and spindle nut 43. By activating the drive unit 41, the inner jacket tube 31 may be retracted or extended relative to the outer jacket unit 33 for the longitudinal adjustment of the steering column 1 in a telescopic manner, as indicated by a double arrow.

[0058] An energy absorption device 5 is arranged between the outer jacket unit 33 and the inner jacket tube 31, said energy absorption device being described in more detail hereinafter. This energy absorption device is able to be identified in FIG. 2 in which the support unit 2 and the outer jacket unit 33 are omitted for greater clarity, in the same perspective as in FIG. 1. FIG. 3 shows an exploded view of the arrangement of FIG. 2 exploded transversely to the longitudinal axis L.

[0059] The energy absorption device 5 has a housing 51, also denoted as the retaining profile 51, in the form of a C-shaped rail with a substantially rectangular cross section which is fixedly connected to the inner jacket tube 31 and extends in the longitudinal direction, wherein the open cross section is oriented towards the outer face of the inner jacket tube 31. By means of positive connecting elements 510 which engage in corresponding receiving openings 310 in the internal jacket tube 31, the housing 51 is fixedly connected to the jacket tube 31, for example by means of laser welding. On its radially outwardly oriented outer face, the housing 51 has a slot 52 extending parallel to the longitudinal axis L.

[0060] A first energy absorption element 54 and a second energy absorption element 56, which in each case are designed as a U-shaped bending wire and/or bending strip, with a first limb which is connected to a second limb via a portion bent-back by substantially 180°, are arranged spaced apart in the longitudinal direction in the housing 51. In each case, a driver hook 544 and/or 564 is configured at the end of the second limb. In each case, the energy absorption elements 54 and 56 are supported with their first limb counter to the longitudinal direction against abutments 546 and/or 566 which protrude inwardly into the cross section of the housing 51 and which in each case form a stop in the longitudinal direction.

[0061] The energy absorption elements 54 and 56 may be configured as stamped parts so that a cost-effective production is ensured.

[0062] The housing 51 forms a first component in the context of the present invention, which is fixedly connected to the inner jacket tube 31. The housing 51 has an external contact surface 58 relative to the inner jacket tube 31 parallel to the longitudinal axis L, which in FIG. 3 faces the observer.

[0063] A carrier plate 7 has a contact surface 78 which is parallel to the contact surface 58 and which in the mounted state lies flat against the contact surface 58 of the housing 51 in a shear plane S, as is described in more detail below.

[0064] The spindle nut 43 is connected via the support element 45 to the carrier plate 7 and is supported in the longitudinal direction.

[0065] A first coupling element 60 is supported in the longitudinal direction fixedly on the carrier plate 7 and extends through the slot 52 and is connected to the driver hook 564 of the energy absorption element 56.

[0066] A second coupling element 61 may be coupled by means of a pyroelectric actuator 62, which is fixedly connected to the carrier plate 7, through the slot 52 to the driver hook 544 of the energy absorption element 54.

[0067] A shear rivet 8 which forms a shear element according to the invention is guided through an opening 9 which passes transversely to the longitudinal axis L through the carrier plate 7 and the housing 51 and which is configured in the example as a bore with a circular passage cross section having a bore axis B. In normal operation, the carrier plate 7 is connected to the housing 51 by the shear rivet 8, wherein the contact surfaces 58 and 78 in the shear plane S lie against one another as may be identified in the cross-sectional views of FIGS. 4, 5, 6, 8, 10, 11 and 12.

[0068] FIG. 5 shows an enlarged part of the overall cross section of FIG. 4. In FIGS. 6 to 12 only the elements which are essential to the invention, the shear rivet 8, carrier plate 7 and housing 51 are schematic.

[0069] The shear rivet 8 has a rivet shaft 81, also denoted as the shaft for short, which extends through the opening 9 and which has a circular cylindrical rivet cross section substantially filling up the opening cross section, such that only a little play, which is only a fraction of the rivet shaft diameter and/or opening diameter, is present between the rivet shaft 81 and the inner surface of the opening 9.

[0070] By means of a first rivet head 82 the shear rivet 8 is supported outwardly against an outer surface 59 of the housing 51 remote from the contact surface 58, and by means of a second rivet head 83 the shear rivet is supported from outside against an outer surface 79 of the carrier plate 7 remote from the contact surface 78. The contact surface 58 of the housing 51 and the contact surface 78 of the carrier plate 7 are braced relative to one another in the shear plane by means of the shear rivet 8.

[0071] The shear rivet 8 may be designed as a hollow rivet or semi-hollow rivet as shown in FIGS. 6 to 11, or even as a solid rivet as shown in FIG. 12.

[0072] In the embodiment shown in FIG. 6 the opening 9 in the housing 51 has a circumferential chamfer in at least one edge region bounding a contact surface 58, so that a conical-funnel-shaped widened portion 91 which is open towards the contact surface is formed. The chamfer encloses with the bore axis B a chamfer angle a (alpha) preferably greater than or equal to 20°, preferably 30°. An annular free deformation space 92 is defined between the cylindrical outer face of the rivet shaft 81 and the conical inner face of the widened portion 91.

[0073] The carrier plate 7 is supported via the adjusting drive 4 and the outer jacket unit 33 by means of the support unit 2 on the body of the motor vehicle, and the housing 51 on the inner jacket tube 31. In the event of a crash, a high force peak, the so-called crash force F is transmitted in a pulsed manner via the steering spindle 30 to the inner jacket tube 31, said crash force acting as a shear force F parallel to the shear plane S between the housing 51 and the carrier plate 7 as shown in FIG. 7. In the event of a crash the inner jacket tube 31 together with the housing 51 are displaced relative to the carrier plate 7. As a result, the shear element 8 is subjected to shear force and is thereby deformed in the region of the widened portion 9. In practice, the material of the shear element 8 flows approximately in the direction of the shear plane S into the free deformation space 92—upwardly in the view of FIG. 7—and forms therein a plastically shaped retaining ridge 84 which fills up the deformation space 92 at least partially transversely to the bore axis B provided by the widened portion.

[0074] By the further relative movement, the shear element 8 is sheared off in the shear plane S and divided into two separate shear rivet fragments 85, 86, the fragments 85, 86 for short.

[0075] In FIG. 7 the shear rivet fragment 85 is fixed by the retaining ridge 84 protruding into the widened portion 91 transversely to the bore axis B in the direction of passage of the bore 9 and secured against dropping outwardly. The retaining ridge 84 forms a positive connection element which acts in the direction of passage of the opening 9 and which was generated during the shearing off process.

[0076] In order to secure the second shear rivet fragment against falling out of the opening 9 of the carrier plate 7, the opening 9 in the carrier plate 7 may also have a widened portion 91 in the form of a circumferential chamfer in at least one edge region bounding a contact surface 78, whereby in principle a deformation space 92 which is mirror-symmetrical to the deformation space 92 in the housing 51 relative to the shear plane S is formed in the carrier plate 7. This arrangement is shown as the second variant in FIG. 8 in the same view as in FIG. 6. However, a mirror-symmetrical configuration of the deformation space 92 is not essential for guaranteeing the functionality. This deformation space may also be smaller or larger than the other deformation space or may have a different geometry.

[0077] FIG. 9 shows in a similar manner to FIG. 7 the sheared off state. As in FIG. 7 the shear rivet fragment 85 has a retaining ridge 84, in the drawing at the upper edge of the rivet shaft 81. The shear rivet fragment 86—located to the right in the drawing—has also been plastically deformed before being sheared off, such that a retaining ridge 84 has been configured so as to protrude into the deformation space 92 defined by the widened portion 91—at the lower edge in the drawing. As a result, in the opening 9 the shear rivet fragment 86 is positively held and secured on the carrier plate 7.

[0078] The third variant shown in FIG. 10 differs from the embodiment according to FIG. 8 in that the widened portion 91 in the housing 51 is a stepped bore with a shoulder 93 protruding relative to the passage cross section. As a result, the deformation space 92 is annular-hollow cylindrical.

[0079] The fourth variant shown in FIG. 11 differs from the embodiment according to FIG. 8 in that the widened portion 91 in the carrier plate 7 is not configured as a conical chamfer as in FIG. 8 but so as to be in cross section as a rounding 94 of the edge, with a radius r greater than or equal to 0.5 mm.

[0080] The embodiment shown in FIG. 12 differs from the above variants in that the shear rivet 8 is designed as a solid rivet. Naturally the other variants of FIGS. 1 to 11 may be designed with a solid rivet instead of a hollow rivet. The person skilled in the art accordingly selects the rivet such that the shear force selected and predefined thereby is achieved by this selected rivet.

[0081] FIGS. 13 and 14 show views in the normal direction of the contact surfaces 58 or 78. In the embodiment of FIG. 13 the widened portion 91 circulates around the entire circumference of the opening 9, while in FIG. 14 the widened portion 91 is configured only partially in the circumferential region, in which during the crash the retaining ridge 84 on the shear rivet fragments 85 and/or 86 is plastically deformed by the crash force F. The variants shown in FIGS. 1 to 12 may be implemented both with a widened portion over the entire circumference and with a partial widened portion. The geometry of the widened portion is thus correspondingly configured over the entire circumference or partially over the circumference, wherein a combination thereof is also conceivable and possible, namely that the one widened portion of the one component is configured over the entire circumference and the widened portion of the other component is configured partially over the circumference.

LIST OF REFERENCE NUMERALS

[0082] 1 Steering column

[0083] 2 Support unit

[0084] 21 Fastening means

[0085] 30 Steering spindle

[0086] 31 Inner jacket tube

[0087] 310 Receiving openings

[0088] 32 Fastening portion

[0089] 33 Outer jacket unit

[0090] 4 Adjusting drive

[0091] 41 Drive unit

[0092] 42 Threaded spindle

[0093] 43 Spindle nut

[0094] 45 Support element

[0095] 5 Energy absorption device

[0096] 51 Housing

[0097] 510 Positive connection elements

[0098] 52 Slot

[0099] 54, 56 Energy absorption element

[0100] 544, 564 Driver hook

[0101] 546, 566 Abutment

[0102] 57 Opening

[0103] 58 Contact surface

[0104] 59 Outer surface

[0105] 60, 61 Coupling element

[0106] 62 Pyroelectric actuator

[0107] 7 Carrier plate

[0108] 78 Contact surface

[0109] 8 Shear rivet

[0110] 81 Rivet shaft

[0111] 82, 83 Rivet head

[0112] 84 Retaining ridge

[0113] 85, 86 Shear rivet fragments

[0114] 9 Opening

[0115] 91 Widened portion

[0116] 92 Deformation space

[0117] 93 Shoulder

[0118] L Longitudinal axis

[0119] H Vertical direction

[0120] S Shear plane

[0121] B Bore axis