GB2231004A

GB2231004A - Steering column decoupler

Info

Publication number: GB2231004A
Application number: GB8909167A
Authority: GB
Inventors: Bryan Jones; Ronald Alan Cook
Original assignee: Ford Motor Co
Current assignee: Ford Motor Co
Priority date: 1989-04-21
Filing date: 1989-04-21
Publication date: 1990-11-07
Also published as: GB8909167D0; WO1990012722A1

Abstract

A decoupler for a steering column of a motor vehicle has a collar (40) on one part (26) which holds a neck (42) on the other part (32). A packing (44) is fitted between the two parts to prevent there being any play between them. The collar has a circumferential opening (48), and a shank (46) on the other part can pass through this opening to allow the two parts to completely separate from one another in the event of a crash.

Description

STEERING COLUMN DECOUPLER This invention relates to a decoupler for the steering column of a motor vehicle. The steering column decoupler normally provides a rigid joint between the upper and lower parts of the column, but is designed so as to release the upper part from the lower part in the event of a crash.

A steering column decoupler is known which comprises two facing flanges which lie parallel to one another and are angled relative to the axis of the column. The two flanges are normally secured together by shear pins. If there should be a crash however, one flange rides up on another and the shear pins are broken resulting in release of the two halves of the decoupler.

The problem with this decoupler is that it is only held together by the shear pins, and as a result, it is of relatively complex construction.

According to the invention, there is provided a steering column decoupler comprising a first end having a non-round collar portion, a second end having a neck fitted in the collar, a packing piece between the neck and the collar to prevent any play therebetween, and at least one shear pin securing the neck in the collar.

Because the collar is non-round, the form-fitting engagement between the collar and the neck transmits the normal, rotationally-acting, forces experienced by the decoupler. The shear pin or pins are only required to resist longitudinally acting forces which are normally relatively small.

The packing piece is preferably a plastics sleeve which can be fitted over the end of the neck before the neck is inserted in the collar. The cross-section of the collar is preferably generally oval in form and does not completely surround the neck.

The neck preferably is connected to a forked yoke (for attachment to another steering column component) by a shank. The width and length of the shank are related to the width and length of the open part of the collar such that the shank can escape radially from the collar.

The first component can be manufactured from metal plate or strip by pressing and folding. The second component can be manufacture by forging. The shear pins can be of metal or of a plastics material.

The invention will now be further described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a plan view of a steering column decoupler in accordance with the invention; Figure 2 is a side view of the decoupler of Figure 1; Figures 3, 4 and 5 are respectively sections through the decoupler on the lines III-III, IV-IV and V-V.

Figure 1 shows schematically the location of the decoupler 10 in a car which has a floor pan 12, a front bulkhead 14, a steering column 16 with a steering wheel 18, a steering gear 20 and road wheels 22 (only one is shown). The decoupler is fitted between the column 16 and the input member 24 of the steering gear 20. For example, this input member could be the pinion shaft of a rack and pinion steering gear.

The decoupler has a first part 26 which is to be connected at the bottom end of the steering column through a yoke 28, and a second part 30 which is to be connected to the input member 24 of the steering gear 20 through a yoke 32. Note that the yokes 28 and 32 are shown in the drawings as being at right angles to one another, but this is not essential.

The first part has a collar 34 which (as can be seen in Figure 3) does not completely surround a neck 36 of the second part. A plastics sleeve 38 acts as a packing between the collar and the neck to take up any play. Two shear pins 40 pass through the collar 34, the sleeve 38 and the neck 36 to secure these components together against relative axial movement under normal conditions. Under abnormal conditions as occur in a crash, the pins 38 will shear and the steering column will become disconnected from the steering gear, thus helping to avoid the possibility that the steering column will inflict an injury on the driver.

The dimensions of the shank 42 which connects the neck 36 with the yoke 32 need to be related to the dimensions of the collar 34 in order for the decoupler to be most effective. The width A of the shank 42 should be slightly narrower than the width A'of the gap 44 in the collar 34, and the length B of the straight shank should be greater than the length B' of the gap 44. As a result of these conditions, the two parts can be completely decoupled by the shank 42 moving in a radial direction out of the collar.

Two shear pins 40 are shown in the figures, but it is possible that the decoupler could operate with only one such pin.

Claims

1. A steering column decoupler comprising a first end having a non-round collar portion, a second end having a neck fitted in the collar, a packing piece between the neck and the collar to prevent any play therebetween, and at least one shear pin securing the neck in the collar.

2. A steering column decoupler as claimed in Claim 1, wherein the packing piece is a plastics sleeve which can be fitted over the end of the neck before the neck is inserted in the collar.

3. A steering column decoupler as claimed in Claim 2, wherein the cross-section of the collar is generally oval in form and does not Fompletely surround the neck.

4. A steering column decoupler as claimed in any preceding claim, wherein the neck is connected to a forke > dyoke (for attachment to another steering column component) by a shank, and the width and length of the shank are related to the width and length of the open part of the collar such that the shank can escape radially from the collar.

5. A steering column decoupler as claimed in any preceding claim, wherein the first component is manufactured from metal plate or strip by pressing and folding.

6. A steering column decoupler as claimed in any preceding claim, wherein the second component is manufactured by forging.

7. A steering column decoupler as claimed in any preceding claim, wherein the shear pins are of metal.

8. A steering column decoupler as claimed in any one of Claims 1 to 6, wherein the shear pins are of a plastics material.

9. A steering column decoupler substantially as herein described with reference to the accompanying drawings.