LOCKING DEVICE FOR AN ADJUSTABLE STEERING COLUMN FOR A MOTOR VEHICLE

Abstract

A locking device for an adjustable steering column for a motor vehicle may include an actuating shaft that is mounted such that it can be rotated about a rotational axis, that is connected to an operative element of a clamping device, and that is coupled to a rotor of a rotational damper. The rotor may be mounted rotatably in a housing and may be capable of being driven rotationally about a rotor axis by the actuating shaft. A rotational movement of the rotor may be damped in at least one rotational direction. The rotor may have at least one blade that projects radially with regard to the rotor axis and that has a contact face that makes frictional contact with a contact track on an inner face of the housing. Such a locking device has an improved rotational damper, is less complicated to manufacture, and has high acceptance in automotive engineering.

Claims

1.-10. (canceled)

11. A locking device for an adjustable steering column for a motor vehicle comprising: an actuating shaft that is mounted so as to be rotatable about a rotational axis; an operative element of a clamping device, wherein the actuating shaft is connected to the operative element; and a rotor of a dry rotational damper, with the actuating shaft being coupled to the rotor, wherein the rotor is mounted rotatably in a housing and is configured to be driven rotationally about a rotor axis by the actuating shaft, wherein the rotor comprises a blade that projects radially with respect to the rotor axis and that has a contact face that makes frictional contact with a contact track on an inner face of the housing, wherein a rotational movement of the rotor is damped in a rotational direction, wherein a damping action is based on dry friction of the contact face on the contact track.

12. The locking device of claim 11 wherein the inner face of the housing on which the contact track is disposed is an inner circumferential face that surrounds the rotor and has a substantially cylindrical shape that is coaxial with respect to the rotor axis.

13. The locking device of claim 11 wherein the inner face of the housing on which the contact track is disposed is an inner circumferential face that surrounds the rotor and has a conical shape that is coaxial with respect to the rotor axis.

14. The locking device of claim 11 wherein the blade comprises a spring element that prestresses the contact face against the contact track.

15. The locking device of claim 14 wherein the blade is configured as a leaf spring in a region between the rotor axis and the contact face, wherein the leaf spring extends at least in sections in an inclined manner in a first circumferential direction relative to a radial direction.

16. The locking device of claim 11 wherein a cross section of the contact face has an arcuate configuration, wherein an arc that corresponds to the arcuate configuration is open towards the rotor axis and has a bending radius that is smaller than a bending radius of the contact track.

17. The locking device of claim 11 further comprising structural elements disposed on the contact track.

18. The locking device of claim 11 wherein the structural elements are projections.

19. The locking device of claim 11 wherein the rotor is attached fixedly on the actuating shaft such that the rotor rotates with the actuating shaft.

20. The locking device of claim 11 further comprising: a first gearwheel; and a second gearwheel attached fixedly on the rotor such that the second gearwheel rotates with the rotor, wherein the second gearwheel is engaged with the first gearwheel, wherein the second gearwheel is drivable rotatably relative to the first gearwheel by the actuating shaft.

21. The locking device of claim 21 wherein at least one of the rotor, the housing, the first gearwheel, or the second gearwheel is a plastic injection-molded part.

22. The locking device of claim 11 wherein at least one of the rotor or the housing is a plastic injection-molded part.

Description

DESCRIPTION OF THE DRAWINGS

[0030] Advantageous embodiments of the invention will be described in greater detail in the following text using the drawings, in which, in detail:

[0031] FIG. 1 shows a steering column according to the invention in a side view, with a removed actuating lever,

[0032] FIG. 2 shows a partial view of an actuating lever,

[0033] FIG. 3 shows an axial view of a gearwheel according to FIG. 1,

[0034] FIG. 4 shows a perspective view of the gearwheel according to FIG. 4,

[0035] FIG. 5 shows a front view of a rotational damper according to the invention in the axial direction of the rotor axis,

[0036] FIG. 6 shows the rotational damper according to FIG. 5 in a dismantled state,

[0037] FIG. 7 shows a front view of the rotational damper in the axial direction of the rotor axis according to FIG. 5, with a removed housing cover,

[0038] FIG. 8 shows a diagrammatic enlarged view of the rotor with a removed gearwheel as in FIG. 7,

[0039] FIG. 9 shows a view as in FIG. 7 of a rotational damper in a second embodiment,

[0040] FIG. 10 shows a perspective view of the rotational damper according to FIG. 9,

[0041] FIG. 11 shows a perspective view of the rotor from FIG. 10,

[0042] FIG. 12 shows a perspective and exploded view of a clamping device with a rotational damper according to the invention in an alternative arrangement,

[0043] FIG. 13 shows a perspective view of the rotational damper according to FIG. 13.

EMBODIMENTS OF THE INVENTION

[0044] In the various figures, identical parts are always provided with the same designations and are therefore also as a rule named or mentioned in each case only once.

[0045] FIG. 1 shows a locking device 1 according to the invention on a steering column 2 in a side view.

[0046] The steering column 2 has a bracket part 16 which can be fastened by means of fastening lugs 23 to a body (not shown here) of a motor vehicle. A box section swingarm 25 (also called an outer casing unit 25) is arranged on the bracket part 16 via the pivoting joint 26. A vertical adjustment in the vertical adjustment direction 20 can be achieved by way of pivoting of the box section swingarm 25 relative to the bracket part 16 about the pivoting joint 26. The casing unit 13 is mounted in the box section swingarm 25. Said casing unit 13 can be displaced along the longitudinal axis 14 of a steering spindle 15 (that is to say, in the longitudinal adjustment directions 19) relative to the box section swingarm 25 and therefore to the bracket part 16. In the exemplary embodiment which is shown, both vertical and longitudinal adjustment of a steering wheel (not shown here) is therefore possible, which steering wheel can be mounted in the present illustration on the steering wheel connector 24 of the steering spindle 15. Apart from the crash case, an adjustment possibility exists in normal operation only, however, when the locking device 1 is situated in its open position or released position. If the locking device 1 is situated in its closed position or locked position, the position of the casing unit 13 relative to the bracket part 16 and therefore relative to the body of the vehicle is fixed. The steering spindle 15 is mounted in the casing unit 13 such that it can be rotated about its longitudinal axis 14. In its closed position, the locking device 1 can ensure corresponding fixing of the casing unit 13 relative to the bracket part 16 by means of a positively locking connection and/or else by means of a frictionally locking connection or non-positive connection. Corresponding positively locking and/or non-positive clamping systems are known in the prior art.

[0047] The locking device 1 which is shown here has an actuating shaft 21 which is known per se and can be seen here in cross section. Said actuating shaft 21 is guided through the opposite side cheeks 12 of the bracket part 16 in the direction perpendicularly with respect to the plane of the drawing according to FIG. 1, and is held on the bracket part 16 by means of a nut or the like on an opposite side (not visible here) of the bracket part 16. The first cam carrier 3 with its cams 4 is arranged on the actuating shaft 21 on the visible side. The second cam carrier 5 including its cams 6 and the actuating lever 9 is removed in FIG. 1 and is shown separately in FIG. 2. In the finally assembled position, the two said cam carriers 3 and 5 are arranged on the actuating shaft 21 in such a way that they can be rotated relative to one another about the rotational axis 7, and the cams 4 of the first cam carrier 3 interact with the cam or cams 6 of the further cam carrier 4 so as to slide along one another in the case of a rotation of the cam carriers 3 and 5 relative to one another about the rotational axis 7. On account of the fixed fastening of the cams 4 and 6 on the respective cam carrier 3 and 5, this is exclusively a sliding movement for the case where the cams of the two cam carriers 3 and 5 which can be rotated with respect to one another are in contact. Rolling or the like therefore does not occur. In the exemplary embodiment which is shown, the first cam carrier 3 is held fixedly on a side cheek 12 so as to rotate with it, which side cheek 12 is stationary with regard to the steering column 2 or the bracket part 16. In contrast, the second or further cam carrier 5 is attached fixedly on the actuating lever 9 so as to rotate with it. As a consequence, during pivoting of the actuating lever 9 about the rotational axis 7 which is arranged coaxially with respect to the actuating shaft 21, the cam carriers 3 and 5 are rotated relative to one another about said rotational axis 7. A stroke in the longitudinal direction of the rotational axis 7 occurs as a result of the corresponding interaction of their cams 4 and 6, as a result of which tensioning or closing or relieving or opening of the locking device 1 occurs depending on the stroke direction, as is known per se. In specific terms, the two side cheeks 12 which lie opposite one another are moved against one another during tensioning or closing, as is indicated in the exploded illustration of FIG. 12 by way of the two opposed arrows, with the result that the casing unit 13 or the box section swingarm 25 which is situated between the side cheeks 12 is clamped fixedly in position on the bracket part 16. In the released position of the locking device 1, the side cheeks 12 are relieved, that is to say are released counter to the arrow direction, and the adjustment possibilities which have already been mentioned at the outset are available.

[0048] Instead of the cam carriers 3 and 4, alternative locking devices (as described, for example, in DE 44 00 306 A1) have, for example, a gravity lock mechanism or the like which likewise converts a rotation of an actuating shaft 21 into a clamping movement.

[0049] In order to homogenize the movement of the locking device 1, said locking device 1 comprises according to the invention a rotational damper 8 which is fastened to the actuating lever 9 in the exemplary embodiment which is shown. In the exemplary embodiment which is shown, the actuating device 10 which interacts with the rotational damper 8 is configured as a gearwheel 10 which is fastened fixedly to the side cheek 12 and therefore to the bracket part 16 so as to rotate with them.

[0050] The construction of the rotational damper 8 will be described in greater detail in the following text using FIGS. 5, 6, 7 and 8. According to said figures, the rotational damper 8 has a housing 81 which can be fixed on fastening lugs 82 on the actuating lever 9.

[0051] The housing 81 has a conical interior 83 with an inner circumferential face 84 which surrounds a rotor axis R in a casing-shaped manner. The conical interior 83 is distinguished by the fact that the diameter of the inner circumferential face is greater on the side which faces the cover 87 than the diameter on the side which faces away from the cover 87. A rotor 800 is mounted in the interior 83 such that it can be rotated about the rotor axis R, to be precise on an axle journal 85. A second gearwheel 86 is coaxially attached fixedly on the rotor 800 so as to rotate with it. Said second gearwheel 86 projects axially to the outside out of the housing 81 through a cover 87. In the mounted state, said cover 87 holds the rotor 800 in the axial direction (in the direction of the rotor axis R) in the interior 83 of the housing. It is essential that the interior 83 is free from liquid, that is to say is not filled with liquid damping fluid.

[0052] The second gearwheel 86 is in engagement with the first gearwheel 10. If the actuating lever 9 is then pivoted in order to release or lock the locking device 1, the rotor axis R of the rotational damper 8 moves about the rotational axis 7, the second gearwheel 86 meshing with the toothing system 11 of the first gearwheel 10 which is stationary relative to said movement of the rotational damper 8. As a consequence, the second gearwheel 86 is driven rotationally about the rotor axis R, as a result of which the rotor 800 likewise rotates in the interior 83 of the housing 81 about the rotor axis R.

[0053] FIG. 7 shows a view in the direction of the rotor axis R as in FIG. 5, the cover 87 being omitted and it being possible for the arrangement of the rotor 800 to be recognized which is covered partially by the second gearwheel 86.

[0054] FIG. 8 shows a diagrammatic view which is similar to FIG. 7, the second gearwheel 86 also having been omitted for improved recognizability of details of the rotor 800.

[0055] In the embodiment which is shown, the rotor 800 has a total of six blades 801 which are distributed uniformly over the circumference and project radially from the rotor axis R in a star-shaped manner. As can be gathered from the perspective illustration of FIG. 6, the blades 801 are formed as flat strips, approximately in a leaf-shaped manner, which extend in a rectilinear manner axially in the direction of the rotor axis R and extend arcuately in the radial direction. The arcuate extent can be recognized using an illustrated radius r: The course of the blade 801 is angled away by an angle with respect to the radius r in a rotational direction D which is indicated by way of a curved arrow, being less than 180.

[0056] The blades 801 are dimensioned in the radial direction in such a way that they bear in a spring-loaded manner in each case by way of a contact face 802 from the inside against the inner circumferential face 84 of the housing 81. The contact faces 802 are configured on the outside with regard to the rotor axis R on end regions of the blades 801 which are likewise angled away in the rotational direction D, to be precise by an angle , being greater than 90, with the result that each contact face 802 bears against the inner circumferential face 84 in a manner which is directed radially outward. As a result, in the case of a rotation of the rotor 800, the contact faces 802 slide or grind along on a circumferential surface region of the inner circumferential face 84 in an uninterrupted manner, said surface region which is swept over by the contact faces forming what is known as the contact track 88, the width of which in the direction of the rotor axis R coincides with the width of the contact faces 802 on the blades 801. By virtue of the fact that the interior 83 is free from liquid, that is to say is not filled with liquid damping fluid, the damping action is determined exclusively by way of dry friction of the contact face 802 on the contact track 88.

[0057] In the relieved state, that is to say in the non-mounted state outside the housing 81, the rotor 800 preferably has a slight oversize relative to the internal diameter of the inner circumferential face 84 of the housing 81, that is to say the contact faces 802 project radially somewhat further than the radius r. As a result of the design of the blades 801 with regard to their cross section and the material which is used, for example plastic such as thermoplastic elastomer or the like, they are resiliently flexible in the manner of a leaf spring or a spring leaf. As a result of the arcuate course, the contact faces 802 can be compressed elastically in a radial manner in the direction of the rotor axis R, with the result that the rotor 800 can be introduced axially into the interior 83. In the inserted state, the contact faces 802 are pressed correspondingly with a spring force in the region of the contact track 88 against the inner circumferential face 84.

[0058] As has already been explained, in the case of a rotation of the rotor 800, the contact faces 802 move rubbingly along the contact track 88 of the inner circumferential face 84, the frictional force which occurs between the contact faces 802 and the circumferential face 84 braking the rotational movement of the rotor 800, in other words damping the rotor 800. The magnitude of the effective frictional force which acts here is first of all dependent, in a statistical observation, on the relative surface pressure which is dependent on the above-described spring force which is exerted by the elastic blades 801 on the contact faces 802.

[0059] In the case of the configuration according to the invention of the rotor 800, there is additionally also a dynamic frictional force: in the case of a rotation in the rotational direction D, a frictional force F.sub.reib acts on each contact face 802 in the opposite circumferential direction, as can be seen from the illustrated force vector. As a result of the angled-away attachment of the contact face 802, part of the frictional force F.sub.reib is converted by the blade 8 into a radial force component F.sub.radial which additionally presses the contact face 802 against the contact track 88 of the circumferential face 84 in the radial direction. As a consequence, the effective friction between the rotor 800 and the housing 81 is increased in the case of a rotation of the rotor 800 in the rotational direction D, which correspondingly leads to a braking action which is increased in a manner dependent on the speed and therefore to more pronounced damping.

[0060] In the case of a rotation in the reverse rotational direction (D) counter to the rotational direction D, the above-described dynamic boosting of the frictional force does not occur. The frictional forces which occur in the opposite direction even result in a relief of the contact face 802, that is to say the contact faces 802 slide more easily over the contact track 88, with the result that freewheeling in the reverse rotational direction is realized in practice.

[0061] A second embodiment of a rotational damper 8 according to the invention is shown in FIG. 9 in the same view as in FIG. 7. Here, in order to boost the braking action, projections 89 which project radially inward and are rounded in the manner of hills are arranged on the inner circumferential face 84 in the region of the contact track 88. In the case of a rotation, the contact faces 802 slide over the slotted guide face which is formed in this way, and have to overcome the projections 89. The braking moment or the damping action is boosted as a result.

[0062] It can be gathered from the illustration in FIGS. 10 and 11 that additional spring elements 804 are attached on an end side of the rotor 800 in the form of rib-like projections which at least in sections follow the angled-away shape of the blades 801. By means of said additional spring elements 804, the elasticity of the blades 801 can be defined and therefore the spring force, with which the contact faces 802 are pressed against the contact track 88, can optionally be boosted.

[0063] FIGS. 12 and 13 diagrammatically indicate an alternative embodiment of a locking device 1 according to the invention. Here, the actuating shaft 21 is arranged in a manner known per se with the actuating lever 9 which is attached fixedly so as to rotate with it and the cam carriers 3 and 5, the function of which has already been described above in detail. The actuating shaft 21 is guided through the two opposite side cheeks 12. On the opposite side, on the side cheek 12 which faces the observer in the drawing, the actuating shaft 21 is mounted in a bearing unit 27 which can be fixed at different heights on the side cheek 12 for vertical adjustment in the vertical adjustment direction 20, and is secured in the axial direction of the rotational axis 7 with a sliding ring 28 being positioned in between, by means of a fastening element 29, preferably a hexagon nut with an internal thread 29.

[0064] According to the invention, a rotational damper 8 is coupled to the actuating shaft 21. Here, unlike in the first example which was shown, the housing 81 is fastened fixedly on the bearing unit 27 so as to rotate with it by means of fastening elements 28, which bearing unit 27 for its part can be fastened fixedly on the side cheek 12 of the bracket part 16 so as to rotate with it. The fastening element (nut) 29 is connected in a torque-transmitting manner to the rotor 800 which is arranged in the interior of the housing 81 and is arranged coaxially with respect to the actuating shaft 21, that is to say its rotor axis R is identical to the rotational axis 7. The torque-transmitting connection can be effected, for example, by the fastening element being configured as a hexagon nut which engages into a corresponding hexagon socket opening 805 in the rotor 800 in a positively locking manner.

[0065] In principle, the function with regard to the damping action is identical to the embodiment which is described above, the coupling of the rotor 800 to the actuating shaft 21 not taking place via gearwheels 10 and 86 which are connected in between, in contrast to said above-described embodiment, but rather by way of direct fastening to the actuating shaft 21.

[0066] If applicable, all individual features which are shown in the individual exemplary embodiments can be combined with one another and/or exchanged for one another, without departing from the scope of the invention.

LIST OF DESIGNATIONS

[0067] 1 Locking device [0068] 2 Steering column [0069] 3 First cam carrier [0070] 4 Cam [0071] 5 Second cam carrier [0072] 6 Cam [0073] 7 Rotational axis [0074] 8 Rotational damper [0075] 9 Actuating lever [0076] 10 First gearwheel [0077] 11 Toothing system [0078] 12 Side cheek [0079] 13 Casing unit [0080] 14 Longitudinal axis [0081] 15 Steering spindle [0082] 16 Bracket part [0083] 19 Longitudinal adjustment direction [0084] 20 Vertical adjustment direction [0085] 21 Actuating shaft [0086] 23 Fastening lugs [0087] 24 Steering wheel connector [0088] 25 Box section swingarm [0089] 26 Pivoting joint [0090] 27 Bearing unit [0091] 28 Fastening element [0092] 29 Fastening element [0093] 81 Housing [0094] 82 Fastening lugs [0095] 83 Interior [0096] 84 Inner circumferential face [0097] 85 Axle journal [0098] 86 Second gearwheel [0099] 87 Cover [0100] 88 Contact track [0101] 89 Projection [0102] 800 Rotor [0103] 801 Blade [0104] 802 Contact face [0105] 803 End region [0106] 804 Spring element [0107] 805 Hexagonal socket opening