Mechanism for Absorbing Energy Transmitted Through a Vehicle Steering Column

This invention relates generally to a mechanism for absorbing energy transmitted through a vehicle steering column in a crash or impact situation and, more particularly, to an energy absorbing mechanism for an adjustable steering column.

In one aspect of the present invention, a mechanism is provided for absorbing energy transmitted through a vehicle steering column in an impact situation, the mechanism comprising a steering column support member and a bolt arrangement coupling the steering column with the support member, while allowing means to absorb energy transmitted to the bolt arrangement from the steering column upon impact.

The foregoing and other aspects will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawing figures.

FIG. 1 is a schematic side view of a vehicle steering column with an energy absorbing mechanism according to the present invention;

FIG. 2A is an end view of the present mechanism;

FIG. 2B a corresponding side view;

FIG. 3 is a detailed cross-sectional view of one embodiment of the present invention;

FIG. 4 is a view similar to FIG. 3 of another embodiment; and

FIG. 5 a view similar to FIG. 3 of yet another embodiment.

Referring to the drawings, FIG. 1 illustrates a vehicle steering column 1 with steering wheel IA. The steering column 1 is supported by a steering column support member in the form of a support bracket 2 which allows rotational movement of the column about its longitudinal axis.

A clamp bolt arrangement is provided to allow for positional adjustment of the steering wheel 1A. The clamp bolt arrangement includes a clamp handle 3 coupled to a clamp handle bolt 4 passing through the support bracket 2. At least one, and in the embodiment shown in FIG. 2A, two plastic cam/spacers 5 are provided which serve to locate the bolt 4 in a clamping block 6. Each cam/spacer 5 is located in a respective slot 8 (FIG. 2B) in opposed walls of the support bracket 2.

Each slot 8 has an expanded aperture at the bottom end in which the cam/spacer 5 is located with slot 8 constituting an energy absorption means to absorb energy transmitted to the bolt arrangement from the steering column 1 upon impact.

The mechanism functions in this way. Normal rake/reach adjustment is achieved by unclamping the clamp handle 5 and sliding the upper end of the steering column along slot 7. This process does not absorb energy and is only a means of adjustment. When the steering column is subjected to a crash situation, the steering column telescopes due to the action of the driver imparting a large axial force on the steering wheel IA, and the clamp block 6 is forced to the end of its travel via the slot 7. At this point, the clamp bolt 4 will be forced to travel down the slots 8. The diameter of the clamp bolt 4 is greater than the width of each slot 8 and this forces the steering column support bracket 2 to deform. The deformation of the support bracket 2 permits the energy transmitted from the steering column 1 to be absorbed.

FIG. 1 shows at 4A the location of the bolt before impact and at 4B the location of the bolt after impact.

In the embodiment illustrated in FIG. 3, the energy absorption mean is the simple slot 8 just described and there is one of these one each side of the support bracket 2 (see FIG. 2B). The support bracket 2 deforms around the perimeter of the slot 8 when the bolt is forced down the slot due to chest impact of the driver. The direction of the force of this impact is indicated by the arrow X in FIGS. 3, 4, and 5. Note that the slot 8 is slanted relative to the direction of applied force.

In the embodiment of FIG. 4, the or each slot 8A is provided with a plurality of opposed tangs 9 along the slot(s) which impede the movement of the sliding clamp bolt 4. The tangs, therefore, act in such a way as to absorb energy as they yield to the force.

In the embodiment shown in FIG. 5, a plurality of holes 10 are provided in a row in the walls of the bracket 2. The holes 10 are spaced closely together and are positioned in the path of the clamp bolt 4, there being only a thin wall 11 separating adjacent holes 10. As the steering column 1 collapses, the clamp bolt 4 applies a force to the thin walls 11 which separate the holes. As the thin walls yield, they absorb energy.