GB2326849A

GB2326849A - Vehicle steering column clamping device

Info

Publication number: GB2326849A
Application number: GB9714096A
Authority: GB
Inventors: Michael Thomas Hancock; Lee Christian Wright
Original assignee: Nastech Europe Ltd
Current assignee: Nastech Europe Ltd
Priority date: 1997-07-03
Filing date: 1997-07-03
Publication date: 1999-01-06
Also published as: GB9714096D0

Description

VKHICLH STHSRlNG COLUMN CLAMPING DEVICE This invention relates to a vehicle steering column clamping device to control separation of components of the steering column in the event of vehicle crash.

Various means are known to control vehicle steering column collapse by absorbing energy transmitted by the steering column upon collapse. Typical of this are devices such as those disclosed in EP-A-O 705 194, in which one embodiment comprises a deformable U-shaped wire engaged around a pair of pins. A skid member adjoins the wire intermediate the pins and is coupled to the steering column so that, upon collapse of the steering column, the skid member is urged to deform the wire by drawing it over the pins.

It is desirable to control the separation of the components during crash conditions.

According to the present invention, there is provided a vehicle steering column clamping device to control separation of components of the steering column in the event of vehicle crash, the device including first and second relatively slidable parts, one of the parts having means to clamp the other part in position, the clamping means incorporating an adjustment means to adjust the clamping load on the other part, and said first part being connectable to one steering column component and said second part being connectable to another steering column component.

The invention also extends to a vehicle steering column incorporating a vehicle steering column clamping device as just defined.

Preferably, said one part is a bracket comprising two runners in which said other part can slide. Preferably, said other part is a skid plate which can be of the type disclosed in EP-A-O 705 194.

The adjustment means can be one or more screws in said one part, the or each screw pressing down with a predetermined load onto said other part to provide friction to control the sliding movement.

Preferably, the or each screw can press onto an intermediate part interposed between the screw and said other part so that the intermediate part spreads the load of the or each screw along said other part.

Either part can be provided with one or more raised portions which interfere with the clamping means to provide further control.

The clamping device can be used in conjunction with, for example, the wire system of EP-A-O 705 194.

For a better understanding of the present invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which: Figure 1 is a diagrammatic plan view of a vehicle steering column clamping device to control separation of components of the steering column in the event of vehicle crash, Figure 2 is a diagrammatic perspective view of part of the clamping device shown in Figure 1, Figure 3 is a diagrammatic side view, partly in section, of the part shown in Figure 2, Figure 4 is a view similar to Figure 3 but showing a modification, and Figure 5 is a view similar to Figure 3 and showing a further modification.

Referring to the drawings, Figure 1 shows a vehicle steering column clamping device which includes a first part in the form of a skid bracket 1, effectively formed by two longitudinal bars each having a groove 2 slidably receive a skid plate 3. In the form illustrated in Figure 1, the skid plate 3 adjoins a wire 4 of a steering column crash energy absorption system such as that disclosed in EP-A-O 705 194, the wire 4 being wound around pins 5.

The skid bracket 1 is connected to one component of the steering column, such as a steering column bracket, or forms part thereof, whilst the skid bracket 3 is connected to another component of the steering column, such as an outer tube of the steering column itself.

In the event of vehicle crash, the two steering column components are designed to separate or collapse and in either case the skid plate 3 will be urged to slide in the slots 2, to the right as viewed in Figure 1, thereby having the effect of drawing the wire 4 over the pins 5, thereby to absorb energy.

In order more accurately to control this sliding movement, the skid bracket 1 is provided with clamping means incorporating an adjustment facility to adjust a clamping load on the skid plate 3. The clamping means as illustrated in Figure 1 includes four screws 6 (six in Figure 2), which are screwed down via the intermediary of respective longitudinal bars 7 in the grooves 2 onto the skid plate 3. The vertical arrows in Figures 2 to 6 illustrate the direction of clamping pressure on the longitudinal bars 7, which in turn spread the load along the edges of the skid plate 3. The arrows A in Figures 2 to 5 illustrate the movement of the skid plate 3 sliding in the grooves 2 in the event of vehicle crash. The torque of each screw 6 is predetermined and can be adjusted by various angular tightening degrees, for example, a 300 angle of twist once the base of the screw 6 has been tightened with a certain torque onto its bar 7. In the event of vehicle crash, the screws 6 bite into the bars 7.

The number of screws 6 is variable and depends on a number of factors including play.

As can be seen in Figure 3, the screws 6 bear directly on the bar 7, which in turn is flush with and bears on the adjacent edge of the skid member 3.

Figure 4 shows a modification in which two raised portions, in the form of pads 8 are provided on the upper edge surface of the skid member 8, directly beneath the adjacent ends of the screws 6. These pads 8 could instead be provided in the grooves 2 of the bracket 1. In the event of vehicle crash, with the pads 8, the load drops away to nzero" friction as soon as they pass beyond the bases of the screws 6. The configuration of the pads 8 can be designed also to control the energy absorption curve. The pads 8 along one edge of the skid member 3 can be offset in height so that the rear most pad 8 misses the screw(s) 6 in front of it as the skid member 3 slides.

In the embodiment shown in Figure 5, it will be seen that only one pad 8 is provided per groove 8, this again providing a different energy absorption curve.

With the bars 7, it will be appreciated that direct contact between the screws 6 and the moving face of the skid member 3 is avoided, thereby providing greater control of breakaway loads. The tightening of the screws by angle or torque allows tuning of the breakaway loads and energy absorption, whilst the raised pads 8, which retain clamping loads in normal use can provide no load travel after initial load separation, thereby providing an effectively free movement breakaway system, which can be used with or without the wire system illustrated in Figure 1.

The present device also avoids the need to use plastics shear pins in the breakaway system, whose resistance to breakaway cannot easily be checked prior to steering column assembly in a non-destructive manner. With the present device, the steering column breakaway loads can be much more accurately determined. For example, for assembly, the device can be clamped slightly out of position and then pushed with the aid of accurate measurement devices into the correctly loaded position. On the other hand, it is easy to re-work the assembled and clamped device by loosening the screws and re-tightening.

Claims

CLAIMS:

1. A vehicle steering column clamping device to control separation of components of the steering column in the event of vehicle crash, the device including first and second relatively slidable parts, one of the parts having means to clamp the other part in position, the clamping means incorporating an adjustment means to adjust the clamping load on the other part, and said first part being connectable to one steering column component and said second part being connectable to another steering column component.

2. A device according to claim 1, wherein said one part is a bracket comprising two runners in which said other part can slide.

3. A device according to claim 1 or 2, wherein said other part is in the form of a skid plate.

4. A device according to claim 1, 2 or 3, wherein the adjustment means is one or more screws in said one part, the or each screw pressing down with a predetermined load onto to said other part to provide friction to control the sliding movement.

5. A device according to claim 4, wherein the or each screw presses onto an intermediate part interposed between the screw and said other part so that the intermediate part spreads the load of the or each screw along said other part.

6. A device according to any one of the preceding claims, wherein either part is provided with one or more raised portions which interfere with the clamping means to provide further control.

7. A device according to any one of the preceding claims and incorporating an energy absorbing wire system according to EP-A-O 705 194.

8. A vehicle steering column clamping device, substantially as hereinbefore described, with reference to Figures 1 to 3, with or without the embodiment of Figure 4 or Figure 5 of the accompanying drawings.

9. A vehicle steering column incorporating a vehicle steering column clamping device according to any one of the preceding claims.