GB2352286A

GB2352286A - Clamping device for a steering column

Info

Publication number: GB2352286A
Application number: GB9916923A
Authority: GB
Inventors: Daniel Boberra; Philippe Gayrard
Original assignee: Delphi Technologies Inc
Current assignee: Delphi Technologies Inc
Priority date: 1999-07-19
Filing date: 1999-07-19
Publication date: 2001-01-24
Also published as: GB9916923D0

Abstract

A clamping device 10 for the steering column of a motor vehicle comprises a first bracket 12 having a pair of spaced arms 24, each arm having an elongate aperture 28, the apertures being substantially aligned; a second bracket 14 having a pair of spaced arms 18, each arm having an elongate aperture 22, the apertures being substantially aligned; each arm of the first bracket being positioned adjacent one of the arms of the second bracket; and a clamping mechanism 30 including a bolt member 78 having an enlarged head 84 and a threaded shank 82 extending through the apertures in the arms of the first and second brackets. A nut 80 is threaded on the shank and a pivotable member 42,44 having a cam surface 52 is mounted on the shank. A cam 46 is rotatably mounted on the shank and has a cam surface in engagement with the cam surface on the pivotable member, the pivotable member being rotatable relative to the cam between a clamped position of the clamping mechanism in which the arms of the bracket frictionally engage, and a release position in which the arms are frictionally disengaged. The clamping mechanism further includes a toothed surface on one of the arms of one of the brackets and having an aperture aligned with the aperture in the arm; and ball means 56,60 rotatably mounted on the shank, engaging the cam and being adjacent the toothed surface, the ball means having movable balls engaged with the toothed surface in the clamped position; and a spring 54 acting on the ball means to bias the balls away from the toothed surface in the release position.

Description

2352286 CLAMPING DEVICE FOR A STEERING COLUMN

Technical Field

The present invention relates to a clamping device for the steering column of a motor vehicle, and in particular to a clamping device which allows the steering column to rake and telescope relative to the vehicle body.

Background of the Invention

It is known to provide a clamping device for a steering column which allows the steering column to rake and telescope relative to the vehicle body. The clamping device generally comprises a first bracket which is secured to the vehicle body, and a second bracket which is secured to the steering column. The first and second brackets are secured together by a clamping mechanism including a bolt and a nut, with the bolt passing through aligned apertures in the first and second brackets. The apertures in the first bracket are shaped to allow the steering column to have a rake movement (height adjustment or tilt) when the clamping mechanism is loose. The apertures in the second bracket are shaped to allow the steering column to telescope (move in an axial direction) when the clamping mechanism is loose.

Summary of the Invention

The object of the present invention is to provide an improvement to this previously known arrangement.

A clamping device in accordance with the present invention for the steering column of a motor vehicle, comprises a first bracket securable to the vehicle, the first bracket having a pair of spaced arms, each arm having an elongate aperture, the apertures being substantially aligned; a second bracket securable to the steering column, the second bracket having a pair of spaced arms, each arm having an elongate aperture, the apertures being substantially 2 aligned; each arm of the first bracket being positioned adjacent one of the arms of the second bracket, with the apertures in the arms of the first bracket being at an angle to the apertures in the arms of the second bracket; and a clamping mechanism including a bolt member having an enlarged head and a threaded shank extending through the apertures in the arms of the first and second brackets; a nut threaded on the shank; a pivotable member having a cam surface mounted on the shank; a cam rotatably mounted on the shank and having a cam surface in engagement with the cam surface on the pivotable member, the pivotable member being rotatable relative to the cam between a clamped position of the clamping mechanism in which the arms of the bracket frictionally engage, and a release position in which the arms are frictionally disengaged; the clamping mechanism further including a toothed surface on one of the arms of one of the brackets and having an aperture aligned with the aperture in the arm; ball means rotatably mounted on the shank, engaging the cam and being adjacent the toothed surface, the ball means having movable balls engaged with the toothed surface in the clamped position; and a spring acting on the ball means to bias the balls away from the toothed surface in the release position.

The present invention provides a clamping device in which the holding load of the clamping mechanism is increased simply and cheaply, and which has the ability to provide infinite lock positions.

Brief Description of the Drawinjzs

The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:- Figure 1 is an exploded view of a clamping device in accordance with the present invention; and Figure 2 is a cross-sectional view of the clamping device of Figure 1 when assembled.

Description of the Preferred Embodiment

3 Referring to the drawings, the clamping device 10 of the present invention is for use with a steering column (not shown) of a motor vehicle. The clamping device 10 is such as to allow the steering column to rake and/or telescope relative to the vehicle body (not shown) on which the 5 column is mounted.

The clamping device 10 comprises a first bracket 12 which, in use, is secured to the vehicle body in any suitable arrangement; and a second bracket 14 which is secured (in any suitable manner) to a portion of the steering column.

The second bracket 14 includes a pair of spaced arms 18 which are normally positioned on either side of the steering column and are connected by a base member 20. Each arm 18 of the second bracket 14 has an elongate aperture 22 formed therein which extends in a direction substantially parallel to the steering column. The apertures 22 in each arm 18 are substantially aligned.

The first bracket 12 includes a pair of spaced arms 24, each of which is positioned adjacent one of the arms 18 of the second bracket 14. The arms 24 of the first bracket 12 are preferably connected by a bridge member 26. Each arm 24 of the first bracket 12 has an elongate aperture 28 formed therein which extends in a direction at an angle to, and substantially perpendicular to, the aperture 22 in the adjacent arm 18 of the second bracket 14. The apertures 28 in the arms 24 are substantially aligned. The apertures 28 may be slightly curved.

A clamping mechanism 30 is used to releasably clamp the first and second brackets 12,14. The clamping mechanism 30 comprises a toothed plate 32 which is positioned on the outer surface 34 of one of the arms 24 of the first bracket 12. The toothed plate 32 comprises rows 36 of substantially parallel ridges 38. The toothed plate 32 has an aperture 40 therethrough which aligns with, and is substantially identical to, the aperture 28 in the arm 24 on which the toothed plate is mounted.

4 The clamping mechanism 30 further comprises a lever 42 which can pivot about an axis B which extends through the apertures 28, 22, 40 in the arms 24, 18 of the first and second brackets 12, 14, and the toothed plate 32. The lever 42 is secured to a cam follower 44 which is rotatable about the pivot axis B. A cam 46 is positioned next to the cam follower 44. The cam 46 has a first surface 48 and a second surface 50. The first surface 48 of the cam 46 is a cam surface, and the adjacent surface 52 on the cam follower 44 is a corresponding cam surface. The cam surfaces 48, 52 are in substantially continuous engagement due to the bias of a coil spring 54, as will be explained in greater detail below.

Positioned between the cam 46 and the toothed plate 32 are a ball cage 56, balls 58, a resilient ball retainer 60, and, optionally, a cam adaptor 62. The ball cage 56 has a surface 64 adjacent the toothed plate 32 with a number of slots 66 formed therein. Each slot 66 receives one of the balls 58, and the slots are sized to allow the ball to protrude through, but not pass through, the slot. The slots 66 preferably have angled edges 68 to assist in the protrusion of the balls 58. The balls 58 protrude through the slots 66 to be located between adjacent ridges 38 in the toothed plate 32. The ball retainer 60 retains the balls 58 in the slots 66 in the ball cage 56, but allows the balls to rotate within, and roll along, the slots. The ball retainer 60 may have corresponding ball slots 70 formed therein.

The cam adaptor 62 is secured to the ball cage 56 by a spring clip 72 and positioned between the ball retainer 60 and the second surface 50 on the cam 46. The cam adaptor 62, resilient ball retainer 60, and ball cage 56 each have a non-circular aperture 74, 75, 77 respectively which receive a corresponding peg 76 formed on the second surface 50 of the cam 46. The peg 76 extends through the aperture 40 in the toothed plate 32 and into the aperture 28 in the arm 24. The peg 76 is sized and shaped to make a sliding fit in the aperture 28 but to substantially prevent rotation of the cam 46 (and hence the cam adaptor 62 and ball cage 56) about the pivot axis B. The clamping mechanism 30 is secured together and in place on the brackets 12, 14 by a bolt 78 and nut 80. The bolt 78 has a shank 82 which extends along the pivot axis B through the cam follower 44, the cam 46, the cam adapter 62, the ball retainer 60, the ball cage 56, the aperture 40 in the toothed plate 32, and the apertures 22, 28 in the brackets 12,14. The bolt 78 has an enlarged head 84 at one end of the shank 82, and the nut 80 is threaded on the other end of the shank. A washer 86 may be positioned adjacent the nut 80. The washer 86 engages the arm 24 of the first bracket 12 on which the toothed plate 32 is not secured. The head 84 of the bolt 78 engages the lever 42. The coil spring 54 is positioned around the shank 82 of the bolt 78 and extends between (and engages) the washer 86 and the surface 64 of the ball cage 56. The spring 54 acts to bias the balls 58 away from the toothed plate 32, and to bias the cam surfaces 48,52 into substantially continuous engagement.

In the clamped position of the clamping mechanism 30, as shown in Figure 2, the adjacent arms 24, 18 of the first and second brackets 12, 14 frictionally engage one another to secure the first bracket 12 relative to the second bracket 14. Additionally, the balls 58 are located between adjacent ridges 38 on the toothed plate 32 to increase the clamping or holding load between the first bracket 12 and the second bracket 14.

In order to move the clamping mechanism 30 to a release position, the lever 42 is rotated in a first direction about the pivot axis B. Such rotation of the lever 42 rotates the cam surface 52 on the cam follower 44, about the pivot axis B, relative to the cam surface 48 on the cam 46. As the cam surfaces 48,52 rotate relative to one another, the coil spring 54 acts on the cam 46 and on the ball cage 56 to move the cam and the ball cage along the pivot axis B towards the bolt head 84. The movement of the ball cage 56 is such that the balls 58 become disengaged from the toothed plate 32. In the release position of the clamping mechanism 30, the second bracket 14 is capable of telescopic and/or rake movement relative to the first bracket 12.

6 In order to move the clamping mechanism 30 back to the clamped position, the lever 42 is rotated in the opposite direction to the first direction about the pivot axis B. Such action has the reverse effect to that described above during release, and the cam 46 and the ball cage 56 move towards the nut 80 against the bias of the spring 54 to bring the arms 24, 18 back into frictional engagement, and to bring the balls 58 back into engagement with the toothed plate 32 and between adjacent ridges 38. The ability of the balls 58 to move within the slots 66 in the ball cages 56 provides a form of self-centring during clamping to ensure that the balls 58 are fully positioned in between the ridges 38. Such self-centring provides the required increase in clamping force between the first and second brackets 12,14, and provides infinite lock positions for the clamping device 10.

The present invention provides a clamping device with a clamping mechanism which is simple and easy to assemble, which is capable of providing an increase in clamping force over previously known arrangements, and which is capable of providing infinite lock positions. The increase in clamping force can be altered by changing the profile and/or the dimensions of the toothed plate 32 and the dimensions of the balls 58.

In the above described arrangement, the increase in clamping load is in the rake direction, but may be made in the telescope direction by altering the direction of the rows 36 of ridges 38. In an alternative arrangement, the increase in clamping load may be made in both the telescope direction and the rake direction by providing first and second rows of ridges on the toothed plate (with the rows at an angle to one another), or by providing a second toothed plate (on another arm of one of the brackets), ball cage, ball retainer and balls, with the rows on the second plate being at an angle to the rows on the first plate.

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Claims

1. A clamping device for the steering column of a motor vehicle comprising a first bracket securable to the vehicle, the first bracket having a pair of spaced arms, each arm having an elongate aperture, the apertures being substantially aligned; a second bracket securable to the steering column, the second bracket having a pair of spaced arms, each arm having an elongate aperture, the apertures being substantially aligned; each arm of the first bracket being positioned adjacent one of the arms of the second bracket, with the apertures in the arms of the first bracket being at an angle to the apertures in the arms of the second bracket; and a clamping mechanism including a bolt member having an enlarged head and a threaded shank extending through the apertures in the arms of the first and second brackets; a nut threaded on the shank; a pivotable member having a cam surface mounted on the shank; a cam rotatably mounted on the shank and having a cam surface in engagement with the cam surface on the pivotable member, the pivotable member being rotatable relative to the cam between a clamped position of the clamping mechanism in which the arms of the bracket frictionally engage, and a release position in which the arms are frictionally disengaged; the clamping mechanism further including a toothed surface on one of the arms of one of the brackets and having an aperture aligned with the aperture in the arm; ball means rotatably mounted on the shank, engaging the cam and being adjacent the toothed surface, the ball means having movable balls engaged with the toothed surface in the clamped position; and a spring acting on the ball means to bias the balls away from the toothed surface in the release position.

2. A clamping device as claimed in Claim 1, wherein the spring acts on the cam to bias the cam surface on the cam into engagement with the cam surface on the pivotable member.

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3. A clamping device as claimed in Claim I or Claim 2, wherein the spring is a coil spring which is mounted on the shank of the bolt member.

4. A clamping device as claimed in any one of Claims I to 3, wherein the arms of the first bracket are positioned outside the arms of the second bracket with the toothed surface on one of the arms of the first bracket.

5. A clamping device as claimed in any one of Claims I to 4, wherein the toothed surface is defined by a toothed plate having rows of ridges.

6. A clamping device as claimed in any one of Claims 1 to 5, wherein the ball means comprises a ball cage and a ball retainer, the balls being positioned between the ball cage and the ball retainer and protruding through, and movable in, slots formed in the ball cage.

7. A clamping device as claimed in Claim 6, wherein the slots have angled edges.

8. A clamping device as claimed any one of claims 1 to 7, wherein a cam adaptor is positioned between and secured to the ball means and the cam.

9. A clamping device as claimed in any one of Claims I to 8, wherein the pivotable member comprises a lever and a cam follower, the cam follower having the cam surface engaged with the cam.

10. A clamping device as claimed in any one of Claims 1 to 9, wherein the cam has a peg which extends through the ball means and into the aperture in said one arm, the peg being sized and shaped to allow the cam to 9 slide in the aperture but substantially prevent rotation of the cam relative to said arm.

11. A clamping device substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.