HEIGHT ADJUSTING DEVICE OF A STEERING COLUMN OF A MOTOR VEHICLE WITH A SPRING ELEMENT

Abstract

A height adjustment device of a steering column of a motor vehicle includes an electric motor and a reduction gear. The electric motor drives a threaded spindle to raise and lower a steering assembly connected to the steering column. The threaded spindle is engaged with a spindle nut, a rotational movement of the threaded spindle is converted into a translational movement of the spindle nut in a direction of a longitudinal axis of the threaded spindle, and the threaded spindle is surrounded on a circumferential side by at least one spring that exerts a spring force on the spindle nut to counteract a weight force of the steering assembly acting in the direction of the axis of rotation of the threaded spindle. The at least one spring includes a compression spring between the reduction gear and the spindle nut and tensioned when the steering assembly is lowered.

Claims

1-13. (canceled)

14: A height adjustment device of a steering column of a motor vehicle, the height adjustment device comprising: an electric motor; and a reduction gear; wherein the electric motor drives a threaded spindle to raise and lower a steering assembly connected to the steering column; the threaded spindle is engaged with a spindle nut; a rotational movement of the threaded spindle is converted into a translational movement of the spindle nut in a direction of a longitudinal axis of the threaded spindle; the threaded spindle is surrounded on a circumferential side by at least one spring that is capable of exerting a spring force on the spindle nut to counteract a weight force acting in the direction of the longitudinal axis of the threaded spindle; and the at least one spring including a compression spring which is between the reduction gear and the spindle nut and is tensioned when the steering assembly is lowered.

15: The height adjustment device according to claim 14, wherein the at least one spring includes a helical spring.

16: The height adjustment device according to claim 14, wherein the compression spring has a linear spring characteristic.

17: The height adjustment device according to claim 15, wherein the helical spring includes a helical axis which is identical to the longitudinal axis of the threaded spindle.

18: The height adjustment device according to claim 14, wherein the compression spring exerts a preloading force on the spindle nut in an end position of the spindle nut on the threaded spindle which is spaced away from the reduction gear.

19: The height adjustment device according to claim 14, wherein the at least one spring applies the spring force in a range from about 40N to about 100N when the height adjustment device is assembled.

20: The height adjustment device according to claim 14, wherein the at least one spring has a spring characteristic such that, at least at a midpoint between the two end stops of the spindle nut on the threaded spindle, the weight force acting in the direction of the axis of rotation of the threaded spindle is compensated.

21: A steering column of a motor vehicle including the height adjustment device according to claim 14.

22: The steering column according to claim 21, wherein the steering column includes a steering shaft which is rotatably mounted in a jacket tube mounted in an axially adjustable manner in a guide bracket which is mounted in a holder to be pivotable about a pivot axis, the holder being connectable to a body of the motor vehicle, and the height-adjusting device pivoting the guide bracket with respect to the holder in order to raise and lower the steering assembly.

23: The steering column according to claim 22, wherein a lever is held pivotably in a joint axis on the holder and in a joint axis on the guide bracket, and the electric motor effects pivoting of the guide bracket by the lever.

24: The steering column according to claim 23, wherein the spindle nut is connected to the lever to pivot the guide bracket.

25: The steering column according to claim 23, wherein the spring characteristic of the at least one spring is matched to a change, caused by the lever, in a weight force acting on the spindle nut in the direction of the longitudinal axis of the threaded spindle.

26: The steering column according to claim 25, wherein the spring force of the at least one spring is identical or substantially identical in magnitude to the weight force acting in the direction of the longitudinal axis of the threaded spindle over a predominant portion of travel of the height adjustment device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In the following, an example embodiment of the present disclosure will be described with reference to the drawings. Identical or comparable components in different drawings bear the same reference numerals. They show:

[0022] FIG. 1 is a schematic representation of a portion of a height adjustment device of a steering column according to an example embodiment of the present disclosure when the steering wheel is raised.

[0023] FIG. 2 is a schematic representation of the portion of the height adjustment device of FIG. 1 when the steering wheel is lowered.

[0024] FIG. 3 is a load characteristic of a spring element of the height adjustment device.

DETAILED DESCRIPTION

[0025] FIGS. 1 and 2 show a spatial representation of an actuator 1 with an electric motor 2 and a reduction gear 3 of a height adjustment device of a steering column. The electric motor 2 drives, via the reduction gear 3, a threaded spindle 4 which is engaged with a spindle nut 5. The spindle nut 5 is moved on the threaded spindle 4 along a longitudinal axis 100 by the electric motor 2, wherein the interaction of the threaded spindle 4 and the spindle nut 5 converts the rotational movement of the threaded spindle 4 into a translational movement of the spindle nut 5 in the direction of the longitudinal axis 100 of the threaded spindle 4. The spindle nut 5 is indirectly connected to a steering assembly not shown, in particular a steering wheel, so that a movement of the spindle nut 5 along the longitudinal axis 100 of the threaded spindle 4 results in a height adjustment of the steering wheel. In an example embodiment, a steering shaft connected to the steering wheel is rotatably mounted in a jacket tube. The jacket tube is slidably guided in a guide clamp along the longitudinal axis of the steering shaft. The guide clamp is pivotally mounted about a pivot axis in a bracket or, more generally, a retaining member. The retaining member may be secured in mounting points on a body of a motor vehicle. The spindle nut is connected to the guide bracket, which in turn is connected to the holding portion by a lever, so that movement of the spindle nut along the longitudinal axis of the threaded spindle leads to pivoting of the guide bracket relative to the holding portion and to adjustment of the steering wheel in the height adjustment direction. In the two figures, the weight 6 acting on the height adjustment device or the spindle nut is shown purely schematically. The threaded spindle 4 is at least partially surrounded by a spring 7. The spring 7 is a helical spring with a helical axis. The coils of the helical spring 7 surround the threaded spindle 4 on the circumferential side and the helical axis is preferably identical to the axis of rotation of the threaded spindle 100. The helical spring 7 is supported at one end, in the direction of the helical spring axis, on a housing 8 of the transmission 3 and at the other end on an end face 9, close to the housing, of the spindle nut 5. The spring 7 is a compression spring which is tensioned when the steering wheel is lowered in order to counteract the weight force of the steering wheel.

[0026] FIG. 1 shows the actuator 1 and illustrates the lifting of the steering wheel. The direction of adjustment of the spindle nut 10 is indicated schematically by an arrow. The weight force of the steering wheel and the adjustable steering column components, in particular the guide bracket and the jacket tube, counteracts with its vector component F.sub.G the force applied by the electric motor for height adjustment and the spring force F.sub.F. The spring is relieved by this movement, whereby the spring force F.sub.F of the spring at least partially compensates for the load on the spindle nut 5.

[0027] FIG. 2 shows the lowering of the steering wheel. The weight force of the steering wheel and the steering column components with their vector component F.sub.G supports the electric motor during the height adjustment. In other words, the electric motor has to apply less torque to achieve the same adjustment speed as during lifting. The spring is thereby tensioned, increasing the spring force F.sub.F of the spring and increasing the load on the electric motor 2.

[0028] The spring force of the spring F.sub.F is dimensioned such that a permanent one-sided load on the spindle nut 5 can be prevented. Preferably, the spring 7 has a linear spring characteristic. Preferably, the spring constant is thereby selected such that the weight force F.sub.G acting on the spindle nut 5 in the middle between the two end positions of the spindle nut 5 on the threaded spindle 4, which correspond to the end positions of the height adjustment of the steering wheel, is compensated by the spring force.

[0029] FIG. 3 shows a preferred spring characteristic of a compression spring in the arrangement described above. In the uppermost position of the height adjustment device or the end position of the spindle nut s.sub.1 on the threaded spindle remote from the actuator, the compression spring is preloaded with a force F.sub.F,1. When the height adjustment device is moved to the lower position s.sub.2, i.e. when the steering wheel is lowered, the compression spring is tensioned. The spring force increases linearly up to a value F.sub.F,2.

[0030] In the example shown in FIG. 3, the spring constant is adapted to a variation of the weight force along the adjustment path. This change in the weight force acting on the spindle nut in the direction of the axis of rotation of the threaded spindle is brought about by a lever which, as described above, is preferably arranged between the guide clamp and the retaining part. The changing lever ratio is preferably in a range between 1.3 and 1.6. Preferably, the spring compensates the weight force to a predominant part along the whole adjustment path, in both directions. For an approximate weight of 4 kg of the steering wheel, the spring force .sub.FF is preferably between 40N and 100N in the assembled state of the height adjustment device. In the example shown in FIG. 3, the spring force in the upper end position F.sub.F,1 is in a range between 20N and 50N, preferably about 40N and the spring force in the lower end position F.sub.F,2 is in a range between 80N and 120N, preferably about 100N.

[0031] While example embodiments of the present disclosure have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present disclosure. The scope of the present disclosure, therefore, is to be determined solely by the following claims.