GB2113629A

GB2113629A - Mounting for an adjustable steering column

Info

Publication number: GB2113629A
Application number: GB08201106A
Authority: GB
Inventors: Derek William Strutt
Original assignee: Ford Motor Co
Current assignee: Ford Motor Co
Priority date: 1982-01-15
Filing date: 1982-01-15
Publication date: 1983-08-10
Also published as: GB2113629B; DE8300261U1

Abstract

A mounting for an adjustable steering column comprises a bracket member (20), a support member (5) mounted in the bracket member and having an axial passage for receiving a rotatable column part (1), a jacket (2) for the rotatable column part extending from the support member (5) and including an axially deformable portion (3), and clamping means (38, 15 etc.) for clamping the bracket member (20) to the support member (5) and having mutually engaging clamping surfaces (13, 28) which are provided with serrations (14, 29) or other interengaging formations which increase the frictional force resisting movement of the support member (5) relative to the bracket member (2) in the axial direction. <IMAGE>

Description

SPECIFICATION Mounting for an adjustable steering column This invention relates to mountings for adjustable steering columns.

Conventional inountings for adjustable steering columns comprise a bracket member, a support member mounted in the bracket member and having an axial passage therethrough for receiving a rotatable column part, and clamping means for clamping the members together.

In order to reduce the risk of injury to the vehicle drivers in the event of a front collision, the support can be provided with a jacket for the steering column which extends in the axial direction and which includes a deformable portion which absorbs axial impact loads applied to the steering column. In order to ensure that the maximum force is absorbed by the deformable portion, the clamping means must not allow the support member to move relative to the bracket member under impact loads.

According to the present invention, there is provided a mounting for an adjustable steering column comprising a bracket member, a support member mounted on the bracket member and having an axial passage for receiving a rotatable column part, a jacket for the rotatable column part extending from the support member and including an axially deformable portion, and clamping means for clamping the bracket member to the support member characterised in that mutually engaging clamping faces on the clamping means are provided with interengaging formations which increase the frictional force resisting movement of the support member relative to the bracket member in the axial direction.

By providing interengaging formations on the clamping faces of the clamping means which increase the frictional force resisting movement of the support member in the axial direction, the clamping means can be made sufficiently effective to resist movement of the support member under impact loads.

Any suitable formations may be provided on the clamping faces, for example teeth, grooves, knurls or, preferably serrations.

Preferably the support member and the bracket member include guide means for limiting the extent to which the support member can move relatively to the bracket member.

For example, the bracket member and the support member may each define slots, the slot in one member extending generally at right angles to the slot in the other member, and the members are connected together by a pin which passes through the slots in both members and is slidable therein.

It is convenient to arrange the slots so that the slot in one member extends generally parallel to the axial direction, and the slot in the other member extends generally perpendicular to the axial direction. In order to provide a compact construction, the axial slot is preferably formed in the support member.

Although the two slots are generally at right-angles to each other, it is preferred to arrange the slots with a relative angle of inclination rather less than 90 , e.g. 85 to 75 so that movement of the support member in the direction of one slot always results in a slight movement in the direction of the other slot, thereby providing a positive "feel" to the adjustment.

In the preferred embodiment of the invention, the clamping means comprises a slide block mounted on the pin and slidable in a slot in one of the members, e.g. the bracket member, and the clamping faces are formed on the slide block and on the other member, e.g. the support member.

A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a side view of part of a steering column assembly incorporating a mounting in accordance with the invention.

Figure 2 is a side view of part of the assembly of Fig. 1.

Figure 3 is a cross-sectional view taken along line Ill-Ill of Fig. 1.

Figure 4 is an enlarged view of part of the mounting of Figs. 1 to 3.

Figure 5 is a cross-sectional view taken along IineV-V of Fig. 4.

Referring to the drawings, an adjustable steering column assembly comprises a rotatable column part 1 carrying a steering wheel (not shown) at its upper end, which is towards the top of Figs. 1 and 2. A jacket 2 surrounds the column part 1 and is mounted thereon at its upper end by a thrust bearing (not shown).

The jacket 2 includes a deformable portion 3 consisting of a cylindrical unit carrying circumferential corrugations which allow the jacket 2 to collapse under axial loads. The lower end of the jacket 2 is fixed within the upper end of an inwardly tapered passage 4 in a die cast support member 5. The lower end of the passage 4 is formed into a downwardly-opening frusto-conical recess and receives a hollow frusto-conical spacer 7 which is slidably mounted on the column part 1. A compression spring 8 acting between the lower end of the spacer 7 and a ring 9 welded to the column part 1 urges the spacer 7 upwardly into the recess in the lower end of the passage 4, to retain the support member 5 and the jacket 2 in position around the column part 1 whilst allowing the column part 1 to rotate about its axis.

The support member 5 defines a transverse slot 1 2 which is elongated in a direction parallel to the axis of the column part 1. The ends of the slot are formed in two parallel end faces 1 3 of the support member 5 each of which is formed with a series of parallel serrations 14 which extend in a direction perpendicular to the axis of the column part 1. The slot 1 2 receives a pin 1 5 which is also received in two slots 1 6 formed in opposite side walls 1 8,1 9 of a generally U-shaped bracket member 20 which is itself secured to a structural part 21 of the motor vehicle body.

Although the slots 1 6 extends generally at right angles to the axis of the column part 1, they are inclined at an angle of 80 to the axis. The pin 1 5 therefore connects the support member 5 to the bracket member 20 and the slots 1 2,1 6 allow limited movement of the support member relative to the bracket member in directions parallel and perpendicular to the axis of the column part 1. Since the two slots 1 6 in the bracket are inclined at 80 to the axis of the column part 1, movement of the support member 5 in the direction of the slots 1 6 always produces a slight movement in the axial direction which gives a positive "feel" to the adjustment.

As best seen in Fig. 3, the bracket member 20 and the support member 5 may be clamped together by means of two similar clamping blocks 25,26 each of which is freely mounted on the pin 1 5 and has its flat outer face in abutment with respective inner surfaces of the side walls 1 8,1 9 of the bracket member 20. As best seen in Fig. 4 the inner faces of the clamping blocks 25, 26, which face the serrated end faces 1 3 of the support block are formed with a central circular recess 27, and a diametrical groove 28 which is shallower than the recess 27 and equal in width to the end faces 1 3 on the support member 6. The bottom surface of the groove 28 is formed with serrations 29 which extend across the groove 28.

The inner faces of the two clamping blocks 25,26 are each spaced from their respective end faces 1 3,14 of the support member 6 by two spring washers 30 (Fig. 3) and a flat washer 31 which lie in the central recess 27 of each clamping block.

The two clamping blocks 25,26 are supported by opposite ends of a wire spring 34, best seen in Fig. 5, which is secured to the bracket member 20.

The pin 1 5 is retained in position by a castellated nut 35 and a split pin at one end, and by a hexagonal head 37 at the other end.

Between the head 37 and the adjacent side wall 1 8 of the bracket member 20 are mounted a handle 38, which is freely rotatable on the pin 15, and a cylindrical cam block 40 which is also freely mounted on the pin 1 5 but which is restrained from rotation relative to the bracket member 20 by means of a diametrical projection on its inner end face which is a sliding fit in the slot 16. The outer face of the cam block 40 is provided with a cam face 41 having two diametrical grooves disposed at 90" to each other and set at different axial depths in the cam face, the two grooves being interconnected by a sloping cam surface.The handle 38 has a cam follower formed on its end face adjacent the cam face 41 of the cam block which includes a diametrical projection 43 complementary in shape to the grooves in the cam face 41.

Rotation of the handle 38 causes the projection 43 to move between the two grooves in the cam face 41, thereby increasing or decreasing the tension in the pin 1 5 and altering the compressive force between the side walls 1 8,1 9 of the bracket member 1 and therefore the clamping blocks 25,26.

The steering column is locked and unlocked for adjustment by moving the handle 38 between the positions illustrated in broken and solid lines in Fig. 1. When the handle is in the position illustrated in solid lines, the projection 43 is engaged in the deeper of the two grooves in the cam face 41 so that a relatively low compressive force is applied to the side walls 1 8,1 9 of the bracket member 20. The spring washers 30 disengage the serrations 29 on the bottoms of the grooves in the clamping blocks 25,26 from those on the end faces of the support member 6. The support member 6 can therefore move relative to the bracket member 20 within the limits permitted by the movement of the pin in the slots 12,16,17.The spring 34 biases the pin 1 5 towards the top of the slots 1 6 in the bracket member 20 and thus provides support for the support member 5 througnhout its movement. The range of movement of the spring 34 is indicated by the broken lines in Fig. 5.

When the lever 38 is rotated into the position illustrated in broken lines in Fig. 1, the projection 43 engages with the shallower of the two grooves in the cam face 41. The compressive force between the two side walls of the bracket 1 is increased, causing the clamping blocks to move inwardly against the bias of the spring washer 30 to clamp firmly between the end faces 1 3 of the support member 5 and the inner surfaces of the side walls 18,19 of the bracket member 20.

The frictional force between the flat outer faces of the clamping blocks and the surfaces of the side walls is sufficient to prevent movement of the support member in a direction perpendicular to the axis of the column part 1. The inter-engagement of the serrations 14, 29 on the inner faces of the clamping blocks 25,26 and the end faces 18,19 of the support member 5 increase the frictional force opposing relative movement in the axial direction to such an extent that the support member 5 will not move even when impact loads are applied to the column part 1.

Claims

1. A mounting for an adjustable steering column comprising a bracket member, a support member mounted on the bracket member and having an axial passage for receiving a rotatable column part, a jacket for the rotatable column part extending from the support member and including an axially deformable portion, and clamping means for clamping the bracket member to the support member characterised in that mutually engaging clamping faces on the clamping means are provided with interengaging formations which increase the frictional force resisting movement of the support member relative to the bracket member in the axial direction.

2. A mounting according to Claim 1 wherein the bracket member and the support member each define slots, the slot in one member extending generally at right angles to the slot in the other member, and the members are connected by a pin which passes through the slots in both members.

3. A mounting according to Claim 2 wherein the clamping means comprises a clamping block mounted on the pin, the clamping forces being formed on the slide block and one of the said members.

4. A mounting according to Claim 3 wherein the clamping block is received in a slot in the bracket member.

5. A mounting according to any one of claims 2 to 5 wherein the slot in one member extends generally parallel to the axial direction, and the slot in the other member extends generally perpendicular to the axial direction.

6. A mounting according to claim 5 wherein the slots are inclined to each other at an angle of less than 90 .

7. A mounting according to claim 5 or claim 6 wherein the said one member is the support member.

8. A mounting according to any one of claims 5 to 7 further comprising means for biasing the support member towards a position in which the pin lies at one end of the slot in the said other member.

9. A mounting according to any one of claims 1 to 8 wherein the formations comprise serrations.

10. A mounting substantially as hereinbefore described, and as illustrated in the drawings.