GB2429438A

GB2429438A - Telescopic assembly, in particular a vehicle steering column assembly

Info

Publication number: GB2429438A
Application number: GB0517434A
Authority: GB
Inventors: Laurence George Herbert Barton; James Peter Bentley
Original assignee: NSK Steering Systems Europe Ltd
Current assignee: NSK Steering Systems Europe Ltd
Priority date: 2005-08-25
Filing date: 2005-08-25
Publication date: 2007-02-28
Also published as: GB0517434D0

Abstract

A telescopic assembly of two relatively slidable members (1, 2) such as an outer vehicle steering column tube and an inner shaft, has a low-friction bush (3) secured within the outer member (2). A part of the inner member (1) has a portion (6) with a profile that is an interference fit with the inner profile of that end of the outer member (2), or the inner profile of the bush (3) mounted within the outer member. Upon collapse of the two members (1, 2) together sufficiently far for the portion (6) to enter the outer member or bush causes absorption of energy between the two members.

Description

TELESCOPIC ASSEMBLY,

IN PARTICULAR A VEHICLE STEERING COLUMN ASSEMBLY

This invention relates to a telescopic assembly and in particular to a vehicle steering column assembly.

A vehicle steering column assembly is shown in GB-A-2 341 914. Here, to inhibit vibration between two relatively sliding members of the steering column, a bush is mounted between the two members to facilitate relative sliding between the members. An inner column member is mounted in an outer column member and a bush is mounted with a sliding fit on the inner member inside the outer member, the bush being secured within the outer member.

In GB-A-2 341 914, the bush is secured by means of adhesive that has been injected through at least one fill hole provided in the outer steering column member, the adhesive curing so as to retain the bush securely.

Removal of the bush from the inner steering column member can be prevented by a stop provided in the region of a free end of the inner steering column member, the stop being provided by deforming material of the inner member such as by peening.

It is now desired to add to this relative sliding facility of the two steering column members means whereby energy can be absorbed by collapse of the steering column assembly in the event of vehicle crash for example.

According to the present invention, there is provided a telescopic assembly of two relatively slidable members, a part of the inner member that protrudes beyond an end of the outer member having a portion with a profile that is an interference fit with the inner profile of that end of the outer member, or the inner profile of a bush mounted within the outer member, the arrangement being such that collapse of the two members together sufficiently far for said portion of the inner member to enter the outer member or bush causes absorption of energy between the two members.

Removal of the bush from the inner member can be prevented by a stop provided in the region of a free end of the inner member that is located within the outer member.

The two members may have non-circular profiles such as substantially triangular, with the bush being correspondingly profiled.

The bush can be a plastics moulded part arranged to have a good sliding fit with light interference on the inner slidable member.

The two members may be inner and outer steering column members, respectively, for a vehicle. The portion of the inner member that is to provide an interference fit with the inner profile of the outer member/bush may be produced by displacing material of the inner member, this portion of displaced material itself causing displacement or shear of the material of the outer member or bush upon collapse of the two members together, thereby absorbing energy.

The invention also extends to a reach adjustable steering column assembly for a vehicle incorporating a telescopic assembly that is essentially as defined above.

The steering column assembly may also be rake

adjustable.

For a better understanding of the 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:- Fig. 1 is a diagrammatic sectional side view through part of a telescopic assembly of two relatively slidable members forming, for example, part of a steering column for a vehicle, Fig. 2 is a diagrammatic view similar to Fig. 1 and illustrating collapse of the telescopic assembly, and Fig. 3 is a diagrammatic perspective view, partly cut-away, further to illustrate the assembly.

Fig. 1 shows part of a vehicle steering column assembly with an inner tube or shaft member 1 and an outer tube member 2. A plastics low- friction interface sleeve or bush 3 is secured within the outer tube member 2. Preferably, the bush 3 is secured by means of adhesive injected through holes 4 (Fig. 3) provided through the wall of the outer tube member 2 in the region over the inserted bush 3, the adhesive curing to secure the bush 3 in position, whilst allowing the inner shaft member 1 to slide freely within the bush 3. The bush 3 is provided with a light interference on the inner shaft member 1 in order to prevent free play in the assembly.

A stop 5 is provided to prevent the inner shaft member 1 from being removed from the bush 3 and therefore the outer tube member 2 in the direction of the arrow A. The stop 5 is produced conveniently by displacing material forming the inner shaft member 1 to a controlled height. The normal adjustment direction of the two steering column members is represented by the double arrow B, the normal adjustment being to facilitate the reach adjustment of a steering wheel for the driver.

In order to provide a facility to absorb energy between the two members 1, 2, in the event, for example, of vehicle crash, part of the inner shaft member 1 which protrudes beyond the end of the bush 3 and tube member 2 is provided with at least one portion 6 with a profile that is an interference fit with the inner profile of that end of the outer tube member 2 (if no bush 3 is provided) or with the bush 3 if so provided.

As can be seen in Fig. 2, telescopic collapse of the inner shaft member 1 in the direction of the arrow C beyond its normal adjustment range relative to the outer tube member 2, causes the portion 6 to displace material of the inner wall of the bush 3, this being illustrated diagrammatically in Fig. 2 by the form of a groove 7 which has been gouged out of the inner wall of the bush 3 by the portion 6.

The portion 6 is preferably produced by displacing 3D material of the inner shaft member 1. Naturally, the load required to allow such a collapse would be greater than under normal operating circumstances of the steering column, thereby creating a braking or energy-absorbing effect. The height of the material displacement of the or each portion 6 can be varied so as to increase or decrease the sliding load achieved. In the case where more than one portion of displaced material 6 is provided, these can be provided in one or more positions around and or along the inner shaft member 1. In the form shown, all of these portions 6 would lie beyond the mouth of the outer tube member 2.

Claims

Claims 1. A telescopic assembly of two relatively slidable members, a part

of the inner member that protrudes beyond an end of the outer member having a portion with a profile that is an interference fit with the inner profile of that end of the outer member, or the inner profile of a bush mounted within the outer member, the arrangement being such that collapse of the two members together sufficiently far for said portion of the inner member to enter the outer member or bush causes absorption of energy between the two members.
2. An assembly according to claim 1, wherein the bush is secured to the outer member.
3. An assembly according to claim 1 or 2, wherein a stop is provided in the region of a free end of the inner member that is located within the outer member to prevent removal of the bush from the inner member.
4. An assembly according to claim 1, 2 or 3, wherein the two members are of non-circular profile, with the bush being corresponding profiled.
5. An assembly according to claim 4, wherein the profile of the two members and bush is substantially triangular.
6. An assembly according to any one of the preceding claims, wherein the bush is a plastics moulded part arranged to have a good sliding fit with light interference on the inner member.
7. An assembly according to any one of the preceding claims, wherein the two members are inner and outer steering column members, respectively, for a vehicle.
8. An assembly according to any one of the preceding claims, wherein the portion of the inner member that is to provide the interference fit with the inner profile of the outer member/bush is produced by displacing material of the inner member, this portion of displaced material itself causing displacement or sheer of the material of the outer member or bush upon collapse of the two members together, thereby absorbing energy.
9. A telescopic assembly of two relatively slidable members, substantially as hereinbefore described with reference to the accompanying drawings.
10. A reach adjustable steering column assembly for a vehicle incorporating a telescopic assembly according to any one of the preceding claims.
11. A steering column assembly according to claim and being rake adjustable.