GB2250241A

GB2250241A - Motor vehicle steering column assemblies

Info

Publication number: GB2250241A
Application number: GB9025831A
Authority: GB
Inventors: Roland John Hayward
Original assignee: MG Rover Group Ltd
Current assignee: MG Rover Group Ltd
Priority date: 1990-11-28
Filing date: 1990-11-28
Publication date: 1992-06-03
Anticipated expiration: 2010-11-28
Also published as: GB2250241B; GB9025831D0

Abstract

The assembly (11) includes an upper outer column (16) and a lower outer column (21). The lower outer column has two support members (22) hold by frangible couplings (23). A cable (25) forms a loop around the support members and is fixed to the upper outer column. In a vehicle collision involving movement of a forward body part (24) towards the driver, the lower outer column is moved in the same direction and causes a peg (27) to pass between the support members to tension the cable and pull the upper outer column and the steering wheel (13) away from the driver. <IMAGE>

Description

MOTOR VEHICLE STEERING COLUMN ASSEMBLIES This invention relates to motor vehicle steering column assemblies.

It is an object of the invention to provide a motor vehicle steering column assembly which minimises injury to a driver in the event of a vehicle impact.

According to the invention there is provided a motor vehicle steering column assembly comprising an upper shaft member for connection to a steering wheel, a lower shaft member for connection to a steering gear, the shaft members being coupled for rotation with each other but to allow relative axial movement, an upper outer column rotatably supporting the upper shaft member and having frangible mounting means for fixing to the vehicle body structure and to allow axial movement of the upper outer column and the upper shaft member away from the driver, a lower outer column encircling the lower shaft member and being in use positioned to be moved axially towards the driver in the event of a vehicle collision involving collapse of a forward part of the vehicle body and interconnecting means for acting between the upper and lower outer columns and for reacting against another part of the body which is spaced rearwardly from said forward part such that the upper outer column is moved away from the driver when the lower outer column is moved towards the driver by collapse of said forward part of the vehicle body.

The invention will now be described by way of example and with reference to the accompanying drawings, in which Fig 1 is a side elevation of a motor vehicle steering column assembly according to the invention; Fig 2 is a partial view on arrow A in Fig 1; Fig 3 is a view similar to Fig 1 showing the steering column assembly of Fig 1 after vehicle impact; and Fig 4 is a partial view on arrow B in Fig 3.

Referring to Figs 1 and 2, a motor vehicle steering column assembly 11 includes an upper shaft member 12 connected to a steering wheel 13 and a lower shaft member 14 connected to a steering gear 15 (eg a rack and pinion). The shaft members 12 and 14 are coupled for rotation with each other but allow relative axial movement (ie telescoping).

An upper outer column 16 rotatably supports the upper shaft member 12 by means of bearings (not shown) and is itself supported on the vehicle body structure 17 by a bracket 18 which has frangible mounting means 19 (usually referred to as a breakout capsule) which under the influence of a load down the steering column (away from the driver) can rupture to allow axial movement of the upper outer column 16 and the upper shaft member 12 away from the driver.

A lower outer column 21 encircles the lower shaft member 14 and is partially telescoped into the upper outer column 16. Two support members 22 are fixed to the body structure 17 and are connected to the lower outer column 21 by frangible couplings 23.

The steering gear 15 is attached to a forward part 24 of the vehicle body and this also extends close to the lower end of the lower outer column 21. In the event of a vehicle collision, particularly a head-on collision, the forward body part 24 moves rearwardly relative to the other body part 17 supporting the upper outer column. This results in the lower shaft member 14 and the lower outer column 21 moving upwards and rearwards towards the driver (as shown in Fig 3).

A cable 25 forms a loop which extends from a fixing 26 on the upper outer column 16 around the two support members 22. A member in the form of a peg 27 is fixed on the lower outer column 21 but as shown in Figs 1 and 2 is outside the loop of the cable 25.

During a head-on type collision as described above the peg moves between the support members 22 and tensions the cable 25 which then acts as interconnecting means to pull the upper outer column in the direction away from the driver in the downward and forward direction. This ruptures the frangible mounting means 19 as shown in Figs 3 and 4 and the steering wheel 13 moves down with the upper outer column to minimise injury to the driver.

The cable 25 and the support members 22 can be pre-assembled to the steering column assembly 11 before fitting to the vehicle, making a convenient package for assembly to the vehicle.

The support members 22 can be combined in a single U shaped bracket with a single break-out capsule connecting it to the lower outer column. Where the column is adequately supported by other means, the breakout capsule may be omitted, the bracket being provided with clearance with the lower outer column when the assembly is installed in the vehicle.

Instead of being connected directly to the steering gear, the lower shaft member 14 may be connected to a universal joint which is connected to the steering gear through an intermediate shaft. In this case there would be a thrust bearing which could transmit impact loads from the lower shaft member to the lower outer column.

Claims

1. A motor vehicle steering column assembly comprising an upper shaft member for connection to a steering wheel, a lower shaft member for connection to a steering gear, the shaft members being coupled for rotation with each other but to allow relative axial movement, an upper outer column rotatably supporting the upper shaft member and having frangible mounting means for fixing to the vehicle body structure and to allow axial movement of the upper outer column and the upper shaft member away from the driver, a lower outer column encircling the lower shaft member and being in use positioned to be moved axially towards the driver in the event of a vehicle collision involving collapse of a forward part of the vehicle body and interconnecting means for acting between the upper and lower outer columns and for reacting against another part of the body which is spaced rearwardly from said forward part such that the upper outer column is moved away from the driver when the lower outer column is moved towards the driver by collapse of said forward part of the vehicle body.

2. A steering column assembly according to Claim 1 wherein the interconnecting means comprises a cable.

3. A steering column assembly according to Claim 2 wherein the cable forms a loop which extends from the upper outer column around two support members arranged to be fixed to said other part of the body and a member on the lower outer column is movable between the two support members to tension the cable.

4. A steering column assembly according to Claim 3 wherein the two support members are attached to the lower outer column by means of a frangible coupling.

5. A steering column assembly according to Claim 3 or Claim 4 wherein the cable is fixed to the upper outer column.

6. A steering column assembly substantially as described herein with reference to the accompanying drawings.