Steering column arrangement

A steering column arrangement having a steering spindle (2) which is mounted in a casing tube (3, 5) so as to be rotationally movable, and having a switch module (7) which is held immovably with respect to the steering spindle (2). The switch module (7) is fixed radially and axially on the casing tube (3), the switch module (7) being supported on a bearing (12) which is arranged on the steering spindle. The Switch module comprises a centering device (8) which, under action of a force (F) which is oriented coaxially with respect to the longitudinal axis (L) of the steering spindle (2), fixes the switch module (7) on the casing tube (3).

BACKGROUND AND SUMMARY OF THE INVENTION

This invention relates to a steering column arrangement.

DE 197 00 175 A1 discloses a steering column arrangement which comprises a steering spindle mounted in a casing tube so as to be rotationally movable. A switch module is fixed radially and axially on the casing tube at that end of the steering spindle which protrudes into the vehicle interior. As a result, the switch module is held immovable with regard to the steering spindle. For this purpose, the switch module is supported on a bearing which is arranged on the steering spindle.

The switch module is secured axially on the casing tube via a bayonet closure, while the radial fixing is effected via a clip which surrounds the casing tube.

The mounting of the switch module thus requires two steps, and even small tolerance deviations of the components can make it impossible to connect contacts of electronic components which are integrated in the switch module, such as a steering angle sensor, correctly to the steering wheel.

It is an object of the invention to provide a steering column arrangement which simplifies the mounting of a switch module and ensures reliable connection of the switch module to the steering wheel.

According to the invention, the object is achieved by a steering column arrangement that includes a steering spindle mounted in a casing tube so as to be rotationally movable, and a switch module which is held immovably with respect to the rotational movement of the steering spindle and is fixed radially and axially on the casing tube. The switch module is supported on a bearing which is arranged on the steering spindle, and comprises a centering device which, under a force which is oriented coaxially with respect to the longitudinal axis of the steering spindle, fixes the switch module on the casing tube and clamps it radially.

The steering column arrangement comprises a steering spindle which is mounted in a casing tube so as to be rotationally movable and a switch module which is held immovably with respect to the steering spindle and is fastened to the casing tube. According to the invention, the switch module is equipped with a centering device and a bearing, and is supported on the steering spindle via the bearing. The action of a force which is oriented coaxially with respect to the longitudinal axis of the steering spindle on the centering device makes it possible for the switch module to be moved during mounting in the axial position as far as an end position, such that it is oriented radially automatically in the process. Here, it is of advantage that only one step, the application of a coaxially acting force, is sufficient to fasten the switch module to the casing tube. At the same time, the switch module is pulled to the steering wheel by the application of the axial force, so that there can be no axial movement between the switch module and the steering wheel. In addition, it is possible to virtually preclude rotation or tilting of the switch module, so that the steering angle sensor which is integrated, for example, in the switch module is thus mounted in a faultfree manner.

In one refinement, the centering device comprises a stator and clamping jaws which interact during application of the axial force, in such a way that the switch module is centered automatically on the casing tube.

The stator can be connected to the bearing in order to support the switch module on the steering spindle, such that the switch module is held immovably during rotation of the steering wheel.

For uniform introduction of the axially acting force to the clamping jaws, the stator can be connected to each clamping jaw via a spring element in one preferred embodiment.

As each clamping jaw is pulled fixedly to the casing tube by way of a support, the switch module can be secured axially on the casing tube under the action of the axial force.

That face of the clamping jaw which faces the stator advantageously extends obliquely with regard to the longitudinal axis of the steering spindle, so that the stator which is moved in the opposite direction to the clamping jaw brings the clamping jaw into contact with the casing tube.

This effect can be reinforced if the inner face of the stator extends parallel to the oblique face of the clamping jaw.

An elevation which protrudes from that face of the clamping jaw which faces the casing tube can be pressed to a more or less pronounced extent into the casing tube during mounting, as a function of the force which is acting on it, ensuring reliable holding of the switch module on the casing tube.

The axial force can advantageously be applied by means of a steering wheel bolt. This has the advantage that, using a method step which is necessary in any case (the fixing of the steering wheel to the steering spindle), the switch module can be fixed at the same time.

A leaf spring which engages in a cut-out of the casing tube is provided on the stator as a radial securing means of the switch module, which radial securing means can at the same time serve during mounting as a captive securing means.

DETAILED DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2show a longitudinal section through a steering column arrangement1having a steering spindle2and an inner casing tube3which is arranged coaxially with respect to the steering spindle2. For comfort adjustment of a steering wheel (of which only a steering wheel hub4is shown here), an outer casing tube5is mounted so as to be movable relative to the inner casing tube3.

The steering wheel hub4is fit coaxially with respect to the steering spindle2onto its end6which faces the vehicle interior. The end6of the steering spindle2is provided with straight external toothing which engages in corresponding internal toothing of the steering wheel hub4, so that a rotational movement of the steering wheel can be transmitted to the steering spindle2.

A switch module7is fastened to the inner casing tube3. The switch module7serves, for example, to accommodate an angle sensor or for the mounting of gearshift levers. For this purpose, it is necessary for the switch module7to be held immovably with regard to the rotational movement of the steering wheel and the steering spindle2.

FIGS. 1 and 2show the switch module7with its centering device8. The centering device8comprises a stator9which is configured as a hollow cylinder and the internal diameter of which is adapted to the external diameter of the inner casing tube3.

An outer ring11of an axial bearing12is fastened to that end10of the centering device8which points toward the steering wheel hub4, while the inner ring13of said axial bearing12is supported on the steering spindle2. As a result that the stator9remains immovable when the steering spindle2rotates.

Clamping jaws14are provided in the stator9, which are distributed over the circumference of the casing tube3and are in contact with the front end side16of the casing tube3by way of an angular support15. One end17of the clamping jaws14is mounted on the stator9via spring elements18in such a way that, when an axial force according to the arrow F acts on the stator9, the force F is introduced into the clamping jaws14via the spring elements18which are recessed into the stator9. The clamping jaws14are pulled in uniformly over the circumference of the casing tube3by means of the angular support15, so that all the clamping jaws14are centered over the circumference of the casing tube3.

As can be seen, in particular, from the detailed illustration inFIG. 1b, that face14aof the clamping jaw14which faces the stator9extends obliquely to the longitudinal axis L of the steering spindle2, so that the stator9which is moved in the opposite direction to the clamping jaw14brings the clamping jaw14into contact with the casing tube3. This effect is reinforced if the inner face9aof the stator9extends parallel to the oblique face14aof the clamping jaw14. An elevation14cis provided on that face14bwhich faces the casing tube3, which elevation14cis pressed onto the casing tube3by the contact of the oblique faces9aand14a, depending on how far the stator9is moved forward according to the direction of the arrow F, and as a result brings about automatic centering of the entire switch module7.

A leaf spring20is fastened in the inner wall19of the stator9for tangential securing of the switch module7. A cut-out21is provided in the casing tube3so as to correspond with this, as emerges fromFIGS. 3aand3b.

The center region of the leaf spring20is of concave configuration, so that the leaf spring20is centered automatically in the cut-out21, in order to prevent any tolerances in the radial rotation of the switch module7. If the leaf spring21is prestressed appropriately, it always extends through the cut-out until its flanks24come into contact with the edges25of the cut-out21.

A control pin22which is guided in a trim panel23of the steering column arrangement1is fastened to the underside of the leaf spring20. Depending on the position of the leaf spring20, the control pin22protrudes through the trim panel23or ends flush with the trim panel23, so that the correct position of the leaf spring20in the cut-out23can be determined by a visual check.

The switch module7is fit coaxially onto the casing tube3until the leaf spring20engages with the cut-out21. Subsequently, the steering wheel is mounted with the steering wheel hub4onto the front end6of the steering spindle2. The steering wheel can be aligned with the steering spindle, for example, via a blocking tooth in the straight external toothing of the steering spindle2which corresponds with a removed tooth of the internal toothing of the steering wheel hub4. A contact plug which is provided on the steering wheel will always engage into a plug of the switch module7reliably in terms of mounting, as a result of the clear radial alignment between the steering wheel, the steering spindle and the switch module7. The steering wheel is pulled on with a defined force F by a steering wheel bolt (not shown) which is arranged coaxially with respect to the longitudinal axis L of the steering spindle2and penetrates the steering wheel hub4. This force F causes the stator9of the switch module7to be acted on via the axial bearing12and the force F to be introduced to the clamping jaws14. The force which acts as a result on the support15of the clamping jaws14, and the interaction of the oblique faces between the clamping jaws14in the stator9, makes automatic centering and radial clamping of the clamping jaws14onto the casing tube3possible, with the result that the switch module is secured axially. At the same time as the switch module7is pulled in the axial direction, the leaf spring20is centered in the cut-out21, so that radial securing is effected. The control pin22is moved, as soon as the leaf spring2enters the cut-out21, from an elevated position which projects beyond the trim panel23into a lowered position. The fitter can thus check whether the switch module7has latched correctly with the leaf spring20in the cut-out21. After the steering wheel and switch module7have been mounted, the cabling of an airbag which is accommodated in the steering wheel is laid.

The number of clamping jaws14can be selected freely, three clamping jaws being sufficient to secure the switch module7axially on the casing tube3. Each clamping jaw14should be assigned a spring element15. A plurality of leaf springs20can also be provided for radial securing.