CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to German Patent Application No. 102018128122.6, filed Nov. 9, 2018, the disclosure of which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to an energy absorption device for a vehicle steering column and a vehicle steering column comprising said energy absorption device.

BACKGROUND

Vehicle steering columns have several characteristics. On the one hand, they must, except for cheaper cars, allow adjustment of the steering shaft in the axial and/or tilt direction, and on the other hand, they must absorb energy in the event of an accident. This energy absorption is possible due to an individual energy absorption device, which acts between two parts of the steering column moving relatively toward each other in the event of a crash. These parts are usually an outer tube and an inner tube extending into the outer tube, said inner tube receiving the steering shaft.

In the prior art such an energy absorption device, is provided by a metal band and an adjustable deformation unit, through which the metal band passes along a curved deformation section, and while absorbing energy it is moved through and along the deformation section, for said metal band to be plastically deformed. Consequently, this deformation provides the energy absorption.

From DE 600 06 815 T2 a generic energy absorption device is known, wherein two deflectors sit on a lever that can be pivoted. A deflector is attached concentrically to the pivot axis and the other is attached to the end of the lever. A metal band extends around the first deflecting element, obliquely backwards, then around the other deflecting element, to finally extend again in the opposite direction. By pivoting the lever, the wrap angle of the metal band can be varied on each deflecting element. Thus, the degree of deformation can be varied.

SUMMARY

The object of the present disclosure is to provide a deformation device for a steering column as well as a steering column, wherein the deformation unit is compactly constructed, and a high change of the amount of absorbed forces and energies by the deformation unit is possible due to high degree of adjustability. The energy absorption unit according to the present disclosure comprises a metal band and an adjustable deformation unit, through which the metal band passes along a curved deformation section, and while absorbing energy it is moved through said section, for said metal band to be plastically deformed. The deformation unit comprises a hollow roller rotatable around a central axis, wherein for the metal band to make contact, the deformation unit has a first convex contact surface located in the inner side of the roller in its interior, and a second contact surface located on the outer side of the roller, wherein the first and the second contact surface are each convex and curved in the opposite direction to form an S-shape, wherein the roller has an outlet slot for the metal band to pass through, and by said metal band the first and the second contact surface are separated from each other, and also an inlet slot positioned away from the outlet slot through which the metal band passes into the interior of the roller, to be supported against the first contact surface.

In the energy absorption device according to the present disclosure, the plastically deformable metal band passes through a deformation roller unit. Convex curved deformation surfaces are not only available on the outer face, but also in the hollow interior of the roller. For that reason, a very compact construction or assembly is possible. In addition, the roller is relatively stable in itself and can absorb high forces. The terms inlet slot and outlet slot are in no way limited to the effect that the metal band would be determined by the movement direction or the insertion direction. In fact, the different terms allow to identify them more easily.

Due to the rotability of the roller, the wrap angle of the metal band around both contact surfaces can be changed, as an option continuously, to adjust the required energy absorption amount. If a high energy absorption level is achieved, the roller is actively rotated by a drive in a manner that the wrap angle is large at both contact surfaces. If a low energy absorption level is achieved, the roller is actively rotated in the opposite direction and provides a smaller wrap angle for the metal band.

An embodiment of the invention provides that the energy absorption level is adjustable in stages. In the initial position, the roller is locked in a position in which a high energy absorption level is guaranteed. The locking takes place, for example, via a movable or destructible pin or, in other words, via a releasable pin. For example, it is provided a pyrotechnic device that adjusts or destroys the pin in a manner that said pin when detecting the state “belted” or “unbelted” or light person releases the movement of the roller. The roller can rotate freely and then will move into the position in which it opposes the least resistance, in a manner that it is possible to switch between two energy absorption levels.

An option of the invention also provides that one end of the metal band is fastened to the moving part while the opposite end is freely movable. The free end then moves toward the roller when the moving part of the vehicle steering column moves forward in the event of a crash.

The first and second contact surfaces should have a continuous curvature, which means surfaces without recesses or creases, against which the metal band is supported in each rotational position of the roller.

For ease of manufacturing, the first and the second contact surface preferably have the same curvature, that is, the curvatures are projected in opposite directions, but have the same dimensions. The outlet slot is located preferably in the region of the rotation axis, so that relatively small lever lengths are present in the event of a crash. Also, a movement under load is improved in this case. Preferably, the inlet slot should extend over a circumferential angle that corresponds at least to a rotational angle region of the roller. This is to prevent that the metal band may be supported against the edge of the slot on the roller especially if the roller rotates at specific angles.

The course of the metal band in the energy absorption device is determined in a manner that regardless of the rotational position of the roller, the metal band always extends tangentially to the two contact surfaces. This means that the part of the metal band that leads to the first contact surface, seen in axial view of the roller, forms a tangent to the first contact surface, as well as the part of the metal band that leads to the second contact surface. This part also extends tangentially to its associated surface, in this case, the second contact surface.

The roller is preferably a sheet metal bending part. The peripheral wall of this bent sheet metal part forming the first and the second contact surface may be a one-piece sheet section. The sheet metal bending part has a sheet metal strip, which forms the first and second contact surface and whose opposite ends are secured together, for example by flanging. In an axial view of the roller, this means a closed circumferential curve. Because of this, the stability of the roller is increased. The sheet metal strip may extend along a convex arched shape from the end of the second contact surface away from the outlet slot, toward the inlet slot until reaching its fastening end, to form a half-roller having a semi-circular shape. Thus, the sheet metal strip forms a half-roller spaced from the contact surfaces. From the inlet slot the sheet metal strip can also extend over the first contact surface until reaching the fastening end. In a preferred embodiment, it is designed in a manner that the two end portions of the sheet metal strip with respect to the fastening end form a double layer and lie on top of each other. This increases stability.

The first and second contact surfaces can be inscribed, seen in an axial view of the roller, to a circle enclosing the roller around the rotation axis Each contact surface Is located diagonally to each other in an associated quadrant with respect to the rotation axis of the roller. This increases the symmetry of the deformation element and the symmetry of force applications, A rotational position of the roller in which minimal or no deformation energy is generated, provides that the roller will allow the metal band to pass through with a wrap angle of less than 15 degrees. This 15 degree wrap is present in the region of the outlet slot.

The energy absorption device of the present disclosure may additionally have a deflector positioned away from the roller, with the metal band passing around said deflector. In particular, the metal band in this case extends constantly with a wrap angle of 180 degrees around the deflector.

The present disclosure also provides a vehicle steering column comprising an energy absorption device according to the present disclosure, which is characterized by an outer tube and an inner tube extending into the outer tube, with the steering shaft being inserted into the inner tube. The ends of the metal bands are attached, on the one hand, to the outer tube and, on the other, to the inner tube, wherein the outer and the inner tube in the event of a crash, are displaceable relative to each other. Due to this relative displacement, the metal band moves through the deformation unit, and also along the deflector, if present. The movement of the metal band and the deformation unit can be seen relative to each other. This means that the metal band must not necessarily be moved relative to the stationary deformation unit; reversely, the deformation unit can also be moved along the metal band. The deformation unit is preferably attached to either one of the two tubes or to another part of the vehicle.

