GB2242871A

GB2242871A - An air-bag arrangement

Info

Publication number: GB2242871A
Application number: GB9008464A
Authority: GB
Inventors: Lars-Gunnar Skotte; Stig-Hakan Nilsson
Original assignee: Autoliv Development AB
Current assignee: Autoliv Development AB
Priority date: 1990-04-12
Filing date: 1990-04-12
Publication date: 1991-10-16
Anticipated expiration: 2010-04-12
Also published as: DE4111883A1; JPH068785A; GB2242871B; GB9008464D0

Abstract

in an air-bag arrangement for a motor vehicle, the air-bag is contained within the hub 3 of the steering wheel, together with means to inflate the air-bag and associated electronic circuitry. The circuitry is contained within a chamber which is surrounded by a material which shields the circuitry from spurious electric signals thus preventing inadvertent inflation of the bag. The steering wheel is designed so that an air-bag module containing the air-bag, and the means to inflate the air-bag can be mounted on the steering wheel after the steering wheel has been mounted in position in the motor vehicle and after the electronic circuitry has been tested or checked. <IMAGE>

Description

:2::. -i-:2 t521 17.1 DESCRIPTION OF INVENTION "Improvements in or

relating to an air-bag arrangement" THE PRESENT INVENTION relates to an air-bag arrangement and more particularly relates to an air-bag arrangement intended for use in a motor vehicle.

It has been proposed previously to provide an air-bag mounted within a motor vehicle, the air-bag being provided with 'means adapted to inflate the bag whenever accident conditions are detected. Such accident conditions may be detected by means of a sensor arrangement responsive to rapid deceleration of the vehicle.

The air-bag, when inflated, forms a "cushion" located in front of the driver of the motor vehicle or a passenger in the motor vehicle, and serves to minimise the risk of the driver or passenger injuring themselves during the accident.

It has been proposed previously to mount an air-bag intended to protect the driver of a vehicle within the hub of the steering wheel of the vehicle. Previously proposed arrangements of this type have been relatively complex.

nor example, DE-C-3817481 discloses an air-bag mounted in the hub of a steering wheel. The arrangement f is such that the entire air-bag assembly, including the sensor and the associated electric circuitry, must be removed if the steering wheel is to be adjusted relative to the steering shaft. Alsot it is to be noted that all the component parts of the air-bag arrangement have to be fixed to the steering wheel after the steering wheel has been fixed to the steering shaft In the motor vehicle.

According to this invention there is provided an air-bag arrangement within a motor vehicle, said arrangement comprising a steering wheel having a hollow hub, the hub containing an air-bag and means to inflate the air-bag, and containing electronic circuitry adapted to initiate inflation of the air-bag, the circuitry being contained within a chamber or recess, substantially surrounded by material on which shields the circuitry from spurious signals.

Preferably said chamber or recess if formed by a first hub element having upstanding walls and a cover mounted in position on the walls, the walls and the cover defining the chamber.

Conveniently the walls comprise two concentric flanges of circular or part-circular form.

Preferably the walls include radially extending wall portions.

Conveniently one flange is a peripheral upstanding flange provided on a disc-shaped hub element of the steering wheel, and the second flange is a concentric flange, the cover not inhibiting access to a recess defined by the inner flange, the recess being located to accommodate an end portion of the steering shaft of the vehicle and means which mount the hub on the steering shaft.

Preferably the circuitry Is mounted on the under-side of the cover.

Advantageously contact pins on the circuitry engage a power supply socket in the hub.

Preferably the cover and the hub are formed of metal.

Advantageously the air-bag and the means to Inflate the airbag comprise replaceable module.

The Invention also relates to an air-bag arrangement for a motor vehicle, said arrangement comprising a steering wheel, the steering wheel defining a first recess adapted to accommodate a replaceable module, the replaceable module containing an air-bag, and means to inflate the airbag, and a second recess adapted to contain electric circuitry adapted to initiate operation of the air-bag.

The invention also relates to a method of assembling a steering wheel incorporating an air-bag arrangement comprising the steps of mounting controlling electronic circuitry in the steering wheel, mounting the steering wheel on the steering shaft, and finally mounting an air-bag module containing the air-bag and means to inflate the air-bag on the steering wheel.

In order that the invention may be more readily understood, and so that further features thereof may be appreciated, the invention will now be describe, by way of example, with reference to the accompanying drawings in which FIGURE 1 Is an exploded partly cut-away view of a steering wheel and an air-bag module.

FIGURE 2 Is an exploded and cut-away view of part of the steering wheel of Figure 1, showing the steering shaft, FIGURE 3 Is a sectional view through the hub of Figure 2, with parts cut away, and FIGURE 4 is a top plan view of the hub of Figure 3, with parts cut away.

Referring Initially to Figures 1 and 2 of the accompanying drawings a steering wheel for a motor vehicle, such as a car, comprises a substantially circular outer periphery 1 connected by means of radially extending spokes 2 to a hub assembly 3. The hub assembly comprises a generally tubular housing 4 formed Integrally with the spokes, the tubular housing converging towards its lower end. Securely mounted in the lower end of the housing 4 is a disc-shaped hub 5 of metal, such as a die casting, the outer radius of the hub corresponding to the inner radius of the lower part of the converging tubular housing 4. The hub 5 is provided with a peripheral upstanding flange 6 which engages the lower part of the housing 4. The hub 5 is also provided with a semi-circular upstanding inner flange 7, which is_ concentric with the outer flange, the semicircular flange 7 being connected by means of two substantially diametrically opposed radially extending wall portions 8,9 to the outer flange 6. The flanges 6 and 7 and the wall portions 8 and 9 are of the same height above the disc that forms the hub 5. A recess 10 is defined within the semi-circular inner flange 7. The base of the recess is provided with a tapering bore 11 extending through the disc that forms the hub 5. The tap- -1 ering bore 11 may be splined and Is adapted to co-operate with a tapering splined portion 12 adjacent one end of the steering shaft 13 of the vehicle. The steering shaft 13 terminates with a screw-threaded portion 14 adapted to co-operate with a nut 15. The nut 15 Is to be located within the recess 10.

A further radially extending wall 16 extends between the inner flange 7 and the outer flange 6. This wall is of lesser height than the wall portions 8 and 9 and the flanges 6 and 7. A notch 17 Is formed In the top of the wall 9.

A wire or cable 18, such as a power supply cable, passes through an aperture formed in the hub 5 and extends to a connector socket 19 located in the space bounded by the walls 9 and 16 and the outer flange 6 together with the inner flange 7.

The inner and outer flanges 6,7, of the hub 5 define a plurality of bores 20, which extend vertically and have open upper ends, which may be internally threaded, adapted to receive fastening screws.

A metal cover 21 of arcuate form Is provided having such a configuration that it may over-lie the walls 8 and 9 and the portions of the inner flange 7 and the outer flange 6 extending between the walls 8 and 9. The cover 21 has apertures 22 therein which, when the cover is in place, are co-aligned with the bores 20. Fastening screws 23 are provided to secure the cover 21 in place. Part of the cover carries a plurality of downwardly directed pins 24 which are dimensioned and positioned so that when the cover is in place the pins are received within the connector socket 19. Mounted on the cover is encapsulated electric circuitry 25, which is connected to the pins 24 and which is adapted to in- -6 Itiate the firing sequence of an inflatable air-bag. The circuitry may be encapsulated In a plastics material or a resinous material. The encapsulation Is Illustrated as being located beneath the cover 21, and Is thus located within the chamber which is surrounded by the walls 8 and 16, together with the inner flange 7 and the outer flange 6 extending between those walls. It Is to be appreciated that the circuitry 25 is, when the described assembly has been put together, totally surrounded by a metal "Faraday" cage constituted by the hub 5 and the cover 21,, both of which are formed of metal. Thus the circuitry is substantially isolated from any spurious signals.

A wire or cable 26 emerges from the encapsulated circuitry 25 and Is located to pass through the notch or recess 17 formed in the top of the wall 9.

The wire or cable 26 may extend to an air-bag module, such as the air-bag module 27 shown in Figure 1. The air-bag module is adapted to substantially fill the recess defined within the housing 4 above the described hub 5 and the associated cover 21. The air-bag module 27 is provided with a covering element 28 having a substantially circular form, with two opposed radially outwardly extending lugs 29 substantially aligned with the spokes 2 of the wheel 1. Pins 30 are provided which extend upwardly through apertures 31 formed in recessed portions provided at the radially inner ends of the spokes 2, the pins 30 being adpated to be received within corresponding apertures formed in the under-sides of the radially outwardly extending lugs 29. The lugs rest in the recessed portions provided at the inner ends of the spokes 2.

It is to be appreciated that the air-bag module may readily be removed from the described position, simply by easing the air-bag module away from the retaining pins 30, and then easy access Is obtained to the nut 15. enabling the steering wheel to be re-positioned on the splines on the steering shaft 13 without undue difficulty arising.

It Is to be understood that In building a motor vehicle Incorporating the described air-bag arrangement, the air-bag module 27 may be mounted in the vehicle after the other assembly operations have been completed, thus minimising the risk of Inadvertent Inflation of the air-bag during assembly.

It is to be appreciated that the air-bag module will contain an appropriate Initiator or Ignitor to initiate or ignite a pyrotechnic charge contained within the air-bag module which, when Ignited, creates a sufficient quantity of gas to inflate the air-bag module. The air-bag module will be caused to inflate whenever an accident situation is detected. Such an accident situation may be detected by an appropriate acceleration-sensitive device. The acceleration-sensitive device may form part of the encapsulated circuitry 25 located beneath the cover 21. The acceleration sensor must be firmly connected to the vehicle to sense vibrations and deceleration of the vehicle. It has been found that an ideal place for the acceleration sensitive device is In mechanical contact with the steering column. In any event, the cable 18 will provide power to the described arrangement.

If an accident situation has arisen, and the air-bag has been inflated, the air-bag module may be removed from the steering wheel and may easily be replaced by a fresh air-bag module after, of course, the electric circuitry has been checked and tested.

In a modified embodiment of the Invention the air-bag module may be mounted on the hub of the steering wheel In such a way that the air-bag module may be moved, against a spring bias, to effect operation of the horn or hooter present on the motor vehicle.

Only one specific example of the Invention has been described In detail. It is to be appreciated that the precise design of the steering arrangement of any motor vehicle is Individual to that vehicle. It is thus envisaged that in modified embodiments of the Invention the design of the air-bag module may change significantly, and the module may not have the outwardly projecting lugs 29. Whilst the module has been described as being retained in position by means of pins 30, any appropriate fastening means may be used, such as screws, clips or the like. Also, while reference has been made to screws being provided to secure the cover in position, again any appropriate fastening element may be used.

In the described embodiment of the invention a nut is mounted on the top of the steering shaft to secure the hub in position. Again, an alternative fastening or securing device may be used If desired.

In the described embodiment of the invention, both the hub and the cover are made of metal, so that the chamber or recess defined by the combination of the hub and the cover which receives the electric circuitry is effectively totally surrounded by metal, which provides an ideal 'Tarradayll cage. However, in modified embodiments of the invention the hub and the cover may be made of different materials, such as, for example, a plastic or resinus material, the material being provIded with a coating of metal. Alternatively, metal mesh may be utilised to surround the chamber or recess to provide 1 the desired shielding effect.

Claims

CLAIMS:

1. An air-bag arrangement within a motor vehicle, said arrangement comprising a steering wheel having a hollow hub. the hub containing an air-bag and means to Inflate the air-bag. and containing electronic circuit ry adapted to initiate inflation of the air-bag, the circuitry being contained within a chamber or recess, substantially surrounded by a material which shields the circuitry from spurious signals.

2. An arrangement according to Claim 1 wherein said chamber or recess if formed by a first hub element having upstanding'walls and a cover mounted in position on the walls, the walls and the cover defining the chamber.

3. An arrangement according to Claim 2 wherein the walls comprise two concentric flanges of circular or part-circular form.

4. An arrangement according to Claim 3 wherein the walls include radially extending wall portions.

5. An arrangement according to Claim 4 wherein one flange is a peripheral upstanding flange provided on a disc-shaped hub element of the steering wheel, and the second flange is a concentric flange, the cover not in hibiting access to a recess defined by the Inner flange, the recess being located to accommodate an end portion of the steering shaft of the vehicle and means which mount the hub on the steering shaft.

6. An arrangement according to Claim 5 wherein the circuitry is mounted on the under-side of the cover.

4.0 1

7. An arrangement according to Claim 6 wherein contact pins on the circuitry engage a powersupply socket in the hub.

8. An arrangement according to any one of Claims 2 to 7 wherein the cover and the hub are formed of metal.

g. An arrangement according to any one of the pre ceding Claims wherein the air-bag and the means to re place the air-bag comprise a replaceable module.

10. An air -bag arrangement for a motor vehicle, said arrangement comprising a steering wheel, the steerIng wheel defining a first recess adapted to accommodate a replaceable module, the replaceable module containing an air-bag, and means to inflate the air-bag, and. a second recess adapted to contain electric circuitry adapted to initiate operation of the air-bag.

11. A method of assembling a steering wheel incorporating an air-bag arrangement comprising the steps of mounting controlling electronic circuitry in the steering wheel, mounting the steering wheel on the steering shaft, and finally mounting an air-bag module containing the airbag and means to inflate the air-bag on the steering wheel.

12. A method of assembling a steering wheel incorporating an air-bag arrangement substantially as herein described with reference to the accompanying drawings.

Published 1991 at The Patent Office. Concept House. Cardifr Road. Newport. Gwent NP9 I RH. Further copies may. be obtained frorn Sales Branch. Unit 6. Nine Mile Point. Cm-mfelinfach. Cross Kevs. Newport. NP1 7HZ. Printed by Multiplex techniques ltd. St Marv Cray. Kent.

12. An air-bag arrangement substantially as herein described with reference to and as shown in the accompanying drawings.

13. A method of assembling a steering wheel incorporating an air-bag arrangement substantially as herein described with reference to the accompanying drawings.

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

11 ' AMENDMENTS TO THE CLAIMS HAVE BEEN FLED AS FOLLOWS 7. An arrangement according to Claim 6 wherein contact pins on the circuitry engage a powersupply socket in the hub.

9. An arrangement according to any one of the pre ceding Claims wherein the air-bag and the means to in flate the air-bag comprise a replaceable module.

10. A method of assembling a steering wheel incorporating an air-bag arrangement comprising the steps of mounting controlling electronic circuitry in the steering wheel, mounting the steering wheel on the steering shaft, and finally mounting an air-bag module containing the airbag and means to inflate the air-bag on the steering wheel.

11. An air-bag arrangement substantially as herein described with reference to and as shown in the accompanying drawings.