GB2247652A

GB2247652A - Motor vehicle steering column assemblies

Info

Publication number: GB2247652A
Application number: GB9019370A
Authority: GB
Inventors: Roland John Hayward
Original assignee: MG Rover Group Ltd
Current assignee: MG Rover Group Ltd
Priority date: 1990-09-05
Filing date: 1990-09-05
Publication date: 1992-03-11
Anticipated expiration: 2010-09-05
Also published as: GB9019370D0; GB2247652B

Abstract

The assembly comprises a tubular outer column (11) and rotatable inner column (12). A connection 17 for mounting the assembly to the vehicle body structure (13) comprises a flange 18 and a strap member (19), formed integrally with the outer column and connected to the outer column by frangible sections (21). On impact, deformation of the vehicle body structure causes progressive peeling back of the strap member and breaking of the frangible sections 21 instead of driving the steering column assembly upwards towards the driver. In another embodiment, the steering column assembly is guided for substantially rectilinear movement during vehicle impact. <IMAGE>

Description

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

It is an object of the invention to provide installation of the steering column assembly in the motor vehicle which will allow distortion of the vehicle structure under vehicle impact conditions without undue movement of the steering column assembly within the driver's compartment.

According to one aspect of the invention there is provided a motor vehicle steering column assembly comprising a tubular outer column encircling and supporting a rotatable shaft, the outer column including a mounting member for fixing to the vehicle structure and a deformable strap member having one end connected to the outer column and the other end connected to the mounting member, the strap member being further connected to the outer column by frangible sections along its length.

Preferably the strap member is integral with the outer column or with the mounting member. Where at least the strap member is integral with the outer column the outer column is preferably made from metal strip, wrapped and joined to form a tube, and the strap member is defined by apertures or slits formed in the support prior to wrapping.

The outer column may include a portion of reduced section which allows bending of the column assembly under impact, in which case the said portion may be formed where the mounting member is in the metal strip prior to wrapping as described immediately above.

The steering column assembly may be guided for substantially rectilinear movement during vehicle impact and according to a further aspect of the invention there is provided a motor vehicle steering column assembly comprising a tubular outer column encircling and supporting a rotatable shaft, wherein the column assembly is guided for substantially rectilinear movement during vehicle impact.

The outer column may be guided by a sleeve mounted on the vehicle structure. Alternatively or additionally the outer column may be mounted on two or more spaced connections, each connection being designed to allow substantially rectilinear movement of the tubular support under impact and provide lateral guidance. One of said connections may include a strap connecting the outer column to the vehicle structure and may include a breakout capsule. The lower connection may comprise two mountings on respective parts of the vehicle structure which move relative to each other during vehicle impact and cause upward movement of the outer column in the region of the lower connection.

The invention will now be described by way of example with reference to the accompanying drawings, of which Fig 1 is a side view of a first example of a motor vehicle steering column assembly according to the invention; Fig 2 is an enlarged view of part of Fig 1; Fig 3 is a view on arrow A in Fig 2: Fig 4 is a view of part of the outer column shown in Figs 1 to 3 prior to wrapping; Fig 5 is a view similar to Fig 2 showing the steering column assembly of Figs 1 to 4 after vehicle impact.

Fig 6 is a view similar to Fig 2 showing a modification; Fig 7 is a view similar to fig 4 showing part of the outer column showing Fig 6 prior to wrapping; Fig 8 is a side view of a second example of a motor vehicle steering column assembly according to the invention; Fig 9 is a view similar to Fig 8 showing the steering column assembly of Fig 8 after vehicle impact; Fig 10 is a side view of a third example of a motor vehicle steering column assembly according to the invention; Fig 11 is a cross-section on the line XI - XI in Fig 10; Fig 12 is a side view of a fourth example of a motor vehicle steering column assembly according to the invention; Fig 13 is a view similar to Fig 12 showing the steering column assembly of Fig 10 after a first stage of vehicle impact;; Fig 14 is a view similar to Fig 12 showing the steering column assembly of Fig 12 after a second stage of vehicle impact; Fig 15 is a side view of a modified version of the steering column assembly shown in Fig 12; and Fig 16 is a view similar to Fig 12 showing the steering column assembly of Fig 15 after vehicle impact.

Referring to Figs 1 to 4, a motor vehicle steering column assembly comprises a tubular outer column 11 which encircles a rotatable shaft or inner column 12. The outer column 11 supports the inner column 12 by journal bearings (not shown). The outer column 11 is mounted on a vehicle body structure 13 by an upper mounting connection 14 comprising a bracket 15 and U shaped strap 16 and by a lower mounting connection 17 shown in greater detail in Figs 2 and 3.

The lower mounting connection 17 comprises a mounting member in the form of a flange 18 fixed to the vehicle body structure 13 by two bolts (not shown). A deformable strap member 19 is formed integral with the outer column 11 and the flange 18 and has one end connected to the flange and the other end connected to the outer column. The strap member 19 is further connected to the outer column 11 by frangible sections 21 along its length.

The frangible sections 21 are defined in the outer column 11 by apertures 22.

These apertures 22 are formed in the outer column 11 by making the outer column from metal strip which is wrapped and joined to form a tube. Fig 4 shows the strip before wrapping, the edges 23 being joined by welding after wrapping. A longer aperture 24 defines the flange 18 and the adjacent portion of strap member 19.

On vehicle impact the body structure adjacent the lower mounting connection 17 tends to move towards the body structure adjacent the upper mounting connection 14. The strap member progressively peels back and breaks the frangible sections 21 to prevent the steering column assembly and steering wheel 25 from being driven upwards and imparting unnecessary injury to the driver.

Figs 6 and 7 show a modification whereby the strap l9A is formed in the outer column 11A before wrapping and a separate mounting connection 17A including a flange 18A is welded to the strap.

In a further modification (not shown) the apertures 22 and 24 are formed (eg) punched in a tube rather than in strip material prior to wrapping.

In Figs 8 and 9 a steering column assembly comprises a tubular outer column 31 and an inner column 32 similar in many respects to the assembly described above with reference to Figs 1 to 5.

An upper mounting connection 34 is similar to upper mounting connection 14 and is supplemented by a further connection comprising an integral strap member 39 substantially similar to strap member 19 but arranged to peel back as the outer column 31 is pushed upward on vehicle impact by deformation of the vehicle body structure 33 near the lower part of the steering column assembly.

The region corresponding to aperture 24 in Fig 4 forms a portion of reduced section which, on vehicle impact is pushed through the upper mounting connection 34. If the driver impacts the steering wheel 35 the steering column can deform relatively easily in this region of reduced section and help reduce driver injury.

The steering column assembly shown in Figs 10 and 11 comprises a tubular outer column 41 encircling and supporting an inner column 42 and includes a mounting connection 44 which during vehicle impact guides the column assembly for substantially rectilinear movement during vehicle impact. This is achieved by making a mounting bracket 45 and a lower strap 46 which surround the outer column over a substantial length to act as a guide sleeve.

Other mountings of the steering column assembly may be as described above with reference to Figs 1 to 5, Figs 6 and 7 or Figs 8 and 9 may include conventional breakout capsules.

By guiding the steering column, the steering wheel 43 remains in front of the driver and helps to prevent impact with the facia and instrument binnacle.

The steering column assembly shown in Figs 12 to 14 again comprises a tubular outer column 51 encircling and supporting an inner column 52. The outer column 51 is mounted on an upper mounting connection 54 which includes a breakout capsule of known design and a lower mounting connection 57 also including a breakout capsule of known design. Each breakout capsule in the mounting connections 54 and 57 is designed to rupture at a given load applied axially down the column in the direction of arrow B The lower mounting connection incorporates a deformable bracket 55 fixed to a part of the vehicle body structure which tends not to be pushed back on frontal impact.

A strut 56 connects the bracket 55 to part of the vehicle structure which is pushed bank on initial frontal impact.

Fig 13 shows the result of initial frontal impact. The strut 56 is pushed back and ruptures the breakout capsule of the lower mounting 57 and deforms the bracket 55. At this stage the load on the upper mounting 54 is in the wrong direction to rupture the breakout capsule, but the force of the driver impacting the steering wheel 53 in the direction of arrow B (Fig 13) results in this rupturing and the steering column moves forward as shown in Fig 14.

The ruptured breakout capsules are shown at 58 to illustrate the column movement.

The mountings 54 and 57 also incorporate U shaped straps 56 which help to guide the steering column for substantially rectilinear movement when the breakout capsules rupture.

In the modification shown in Figs 15 and 16 a secondary column is represented diagrammatically by its axis 61 which intersects the axis 62 of the inner column 52 at a universal joint at 63.

On vehicle impact the secondary shaft exerts a force in the direction of arrow C in Fig 15 which results in the steering column being displaced upwards, axis 62 being tilted to position 62A in Fig 16.

This counteracts the normal tendency for the steering wheel 53 to move upward during vehicle impact and puts the steering wheel in a better position to minimise injury to the driver.

Claims

1. A motor vehicle steering column assembly comprising a tubular outer column encircling and supporting a rotatable shaft, the outer column including a mounting member for fixing to the vehicle structure and a deformable strap member having one end connected to the outer column and the other end connected to the mounting member, the strap member being further connected to the outer column by frangible sections along its length.

2. An assembly according to Claim 1 wherein the strap member is integral with the outer column.

3. An assembly according to any preceding claim wherein the strap member is integral with the mounting member.

4. An assembly according to Claim 2 or Claim 3 when dependent on Claim 2 wherein the outer column is made from metal strip, wrapped and joined to form a tube, and the strap member is defined by apertures or slits formed in the outer column prior to wrapping.

5. An assembly according to any preceding claim wherein the outer column includes a portion of reduced section which allows bending of the column assembly under impact.

6. An assembly according to Claim 5 when dependent upon Claim 4 wherein the portion of reduced section is formed where the mounting member is in the metal strip prior to wrapping.

7. An assembly according to any preceding claim wherein the column assembly is guided for substantially rectilinear movement during vehicle impact.

8. A motor vehicle steering column assembly comprising a tubular outer column encircling and supporting a rotatable shaft, wherein the column assembly is guided for substantially rectilinear movement during vehicle impact.

9. An assembly according to Claim 7 or Claim 8 wherein the outer column is surrounded by a guide sleeve mounted on the vehicle structure.

10. An assembly according to Claim 7 or Claim 8 wherein the outer column is mounted on two or more spaced connections each connection being designed to allow substantially rectilinear movement of the outer column under impact and provide lateral guidance.

11. An assembly according to Claim 10 wherein at least one of said connections includes a strap connecting the tubular member to the vehicle structure.

12. An assembly according to Claim 10 or Claim 11 wherein at least one of said connections includes a breakout capsule.

13. An assembly according to any of Claims 10 to 12 wherein the lower connection comprise two mountings on respective parts of the vehicle structure which move relative to. each other during vehicle impact and cause upward movement of the outer column in the region of the lower connection.

14. A motor vehicle steering column assembly substantially as described herein with reference to Figs 1 to 5, Figs 1 to 5 modified as described with reference to Figs 6 and 7, Figs 8 and 9, Figs 10 and 11, Figs 12 to 13 or Figs 12 to 14 modified as described with reference to Figs 15 and 16 of the accompanying drawings.