GB2270883A

GB2270883A - A steering wheel structure

Info

Publication number: GB2270883A
Application number: GB9220444A
Authority: GB
Inventors: Dan Persson
Original assignee: Autoliv Development AB
Current assignee: Autoliv Development AB
Priority date: 1992-09-28
Filing date: 1992-09-28
Publication date: 1994-03-30
Anticipated expiration: 2012-09-28
Also published as: GB9220444D0; GB2270883B

Abstract

A carrier 12 for an air bag is mounted on a support 10, 11 above the central hub of a steering wheel. Electrical contacts 19, 20 are provided on the carrier 12 and the support 10, 11 for activating a horn. If a moderate force is applied to the cover of the air bag carried by the carrier 12, the springs 18 will be depressed, the contacts 19, 20 will be brought into contact and the horn activated. If a large force is applied to the cover then the hook 7 will contact the bottom of the recess provided in the hub and, together with portions 8, 9 of the support, the hook 7 will deform to absorb energy. In the event of an upward force being applied to the carrier 12, upward movement of the carrier 12 will be prevented by bolts 15 and hook 7. <IMAGE>

Description

DESCRIPTION OF INVENTION "IMPROVEMENTS IN OR RELATING TO A STEERING WHEEL STRUCTURE" THE PRESENT INVENTION relates to a steering wheel structure and more particularly relates to a steering wheel structure for use in a motor vehicle such as a motor car.

It is known that the steering wheel frequently provides a major contribution to injuries received by the driver of a motor vehicle, such as a motor car, in an accident. In particular the driver of a car may often be thrown forwardly on to the hub of the steering wheel.

It is, therefore, quite common for at least the central part of the steering wheel to be mounted so that this part of the steering wheel will yield when a substantial force is applied to the steering wheel.

The central part or hub of a steering wheel may thus be resiliently mounted, by means of mounting springs or the like, the central part being mounted on guide bolts which guide the motion of the central part as the springs are compressed. The central part of a steering wheel of this type may be utilised to activate a horn or hooter with the application of manual pressure to the central part. Also, the central part of a steering wheel of this type may carry an air-bag intended to protect the driver of the vehicle.

The central part is mounted on an underlying support. It is conventional for this support also to be such that the support will yield when a very significant force is applied to the support. Consequently, when the support is made of sheet metal, the support has portions which, in cross-section, are folded to follow a serpentine path, or are provided with re-entrant bends or folds or are otherwise configured to collapse when a significant force is applied to the steering wheel.

When the central part of the steering wheel supports an air-bag or the like, should the air-bag be inflated, a very significant force is imparted on to the steering wheel as a consequence of the inflation of the air-bag. When the central part of the steering wheel is mounted on a support which is intended to yield when a significant force is applied to the steering wheel, the support may yield in an undesirable way during, or as a consequence of, inflation of the air-bag. This could lead to the air-bag being incorrectly positioned since, if the support has yielded or deformed, the central part of the steering wheel will not be in its originally intended position.

The present invention seeks to provide an improved steering wheel structure which reduces or obviates the disadvantages of the prior art as described above.

According to this invention there is provided a steering wheel arrangement, the steering wheel arrangement comprising a central hub adapted to be mounted on the steering shaft, a support structure associated with the hub supporting a portion overlying the hub, the said portion overlying the hub being adapted to move downwardly towards the hub from an initial position with a plastic deformation of part of the support structure, means being provided to prevent the said portion from moving outwardly away from the hub.

Preferably an air-bag unit is mounted on the said overlying portion.

Conveniently the said overlying portion is mounted on the support structure by resilient means, the resilient means being adapted to yield when the said portion is subjected to a force which is less than the force required to deform the support structure.

Advantageously electric contacts are provided on the sasid overlying portion and the support structure, the contacts forming part of an electric circuit controlling operation of a horn or hooter.

Conveniently the portion overlying the hub is provided with a hook element engaged in a recess formed in a lug provided on the support structure, the arrangement being such that the hook engages the lug if there is movement of the overlying portion away from the hub, the aperture receiving the hook being such that movement of the overlying portion towards the hub is permitted.

In order that the invention may be more readily understood, and so that further features thereof may be appreciated, the invention will now be described, by way of example, with reference to the accompanying drawings in which FIGURE 1 is a part-sectional view of part of a steering wheel assembly, taken on line I-I of Figure 2, and FIGURE 2 is a sectional view of the arrangement shown in Figure 1 taken on the line II-II of Figure 1.

A steering wheel assembly is provided with a central metal hub 1 adapted to receive a steering wheel shaft within a central passage-way 2. The upper part of the central passage-way 2 forms an upwardly projecting boss 3 which is received within an aperture 4 in the base of a support structure 5 formed of sheet metal. The support structure 5 is provided, at two opposed sides, with upwardly extending substantially rectangular lugs 6 each having a central rectangular aperture 7. The orthogonally disposed sides of the base 5 are provided with upwardly extending projections 8,9 which are provided with re-entrant bent portions providing each projection with a sinuous form. Thus, each projection, when viewed in side elevation or cross-section, is seen to be folded to follow a serpentine path.Each projection terminates with a substantially horizontally extending outwardly directed support portion 10,11. The nature of the sinuous form projections 8,9 is such that if a downward force is applied to the support portions 10 or 11 the sinuous form portions 8 or 9 will collapse or deform in a plastic manner. Thus, the deformation is not a resilient deformation, but a permanent deformation.

A carrier 12, adapted to carry an air-bag assembly (not shown) is mounted on the support portions 10,11. The carrier 12 is provided with two diametrically opposed support regions 13,14 which are substantially aligned with the support portions 10,11.

The support region 13 is provided with a bolt 15 extending through an aperture 16 and thence to a further aperture 17 formed in the support portion 10. A helical spring 18 surrounds the bolt to bias the support portion 10 and the support region 13 apart. However, it is to be noted that when a downward force is applied to the support region 13 that region will move downwardly, compressing the spring 18.

The support portion 10 and the support region 13 each carry a respective electrical contact 19,20 and the arrangement is such that when the spring 18 is compressed as described above the two contacts 19 and 20 will be brought into physical contact. Wires may extend from the contacts to a circuit including a battery and a horn or hooter. When the contacts 19 and 20 touch each other the circuit is completed and the horn or hooter is activated.

The support region 14 and the associated support portion 11 have the same structure as described above for the support region 13 and the support portion 10.

It is to be appreciated that the number of resilient supports, as described above in association with the reference numerals 15 to 20 may be selected to be 2, 3 or 4.

The central hub 1 of the steering wheel supports a plastics moulding 21 which defines spokes 22 of the steering wheel. The moulding 21 defines at predetermined positions a through bore, the upper part of which is of enlarged diameter to define an open-topped recess 23 of substantially cylindrical form. Located above the recess 23 is a screw 24, the head of which is accessible through the bore forming recess 23. The threaded shank 25 of the screw passes through the top part of a hook 26 and through a peripheral part of the carrier 12, shown as the part 27, and the protruding upper part of the screw, 28, may engage the base of an air-bag unit to mount the airbag unit in position on the carrier 12.

The hook 26 is provided with a depending arm 29 and a terminal inwardly directed hook portion 30 adapted to pass through the rectangular aperture 7 in the upwardly extending lug 6.

It is to be appreciated that an air-bag may be mounted on top of the structure illustrated, with the air-bag being connected to the terminal portions 28 of the threaded shanks 25 of the screws 24, access to the screws being obtained through the bores that define the recesses 23. The air-bag may be provided with an appropriate cover.

If a moderate downward force is applied to the cover of the air-bag initially the springs 18 will be compressed, bringing the terminals 19 and 20 into contact, thus activating the horn or hooter. During this movement of the carrier 12 the hook 30 will move downwards within the rectangular aperture 7. If a very large force, which is greater than the moderate force mentioned above is applied to the cover of the air-bag unit, the sinuous form projections 8 and 9 of the support structure 6 will deform. The hook 30 will engage the lower part of the rectangular apertures 6 and the central portion 29 of the hook will also deform. This deformation of both the support structure and the hook is a plastic deformation which provides an energy-absorbing function. During either movement the head of the screw 24 may be received within the recess 23.

If an upward force is applied to the air-bag carrier 12, for example as a consequence of inflation of the air-bag, the carrier 12 will not move upwardly relative to the support portions 10 and 11, since the head of the bolt 15 engages the carrier 12 and prevents such upward movement. If there is a significant upward force and the sinuous form projections 8 and 9 begin to deform in an upward sense, the hook 30 engages the upper part of the rectangular aperture 7, thus preventing any significant upward movement.

Consequently the described structure yields both resiliently (springs 18) and plastically (projections 8 and 9) when subjected to a significant downward force, but does not yield when subjected to an upward force.

Claims

CLAIMS:

1. A steering wheel arrangement, the steering wheel arrangement comprising a central hub adapted to be mounted on the steering shaft, a support structure associated with the hub supporting a portion overlying the hub, the said portion overlying the hub being adapted to move downwardly towards the hub from an initial position with a plastic deformation of part of the support structure, means being provided to prevent the said portion from moving outwardly away from the hub.

2. A steering wheel assembly according to Claim 1 wherein an air-bag unit is mounted on the said overlying portion.

3. A steering wheel arrangement according to Claim 1 or Claim 2 wherein the said overlying portion is mounted on the support structure by resilient means, the resilient means being adapted to yield when the said portion is subjected to a force which is less than the force required to deform the support structure.

4. A steering wheel arrangement according to Claim wherein electric contacts are provided on the said overlying portion and the support structure, the contacts forming part of an electric circuit controlling operation of a horn or hooter.

5. A steering wheel arrangement according to any one of the preceding Claims wherein the portion overlying the hub is provided with a hook element engaged in a recess formed in a lug provided on the support structure, the arrangement being such that the hook engages the lug if there is movement of the overlying portion away from the hub, the aperture receiving the hook being such that movement of the overlying portion towards the hub is permitted.

6. A steering wheel arrangement substantially as herein described with reference to and as shown in the accompanying drawings.

7. Any novel feature or combination of features disclosed herein.