GB2287305A

GB2287305A - Steering wheel with air-bag unit

Info

Publication number: GB2287305A
Application number: GB9404116A
Authority: GB
Inventors: Michael Kozyreff
Original assignee: Autoliv Development AB
Current assignee: Autoliv Development AB
Priority date: 1994-03-03
Filing date: 1994-03-03
Publication date: 1995-09-13
Anticipated expiration: 2014-03-03
Also published as: GB2287305B; GB9404116D0

Abstract

The steering wheel comprises a metal framework (1) surrounded by an integrally formed moulding (6) which surrounds the framework and which also has a portion (9) extending across the central part of the steering wheel and defining a recess (10) adapted to receive the air-bag unit (25). Separate moulding stages for the steering wheel and the air-bag cover are thus not required. <IMAGE>

Description

DESCRIPTION OF INVENTION "INPROVEMENTS IN OR RELATING TO A STEERING WHEEL ARRANGEMENT" THE PRESENT INVENTION relates to a steering wheel arrangement for use in a motor vehicle.

A conventional steering wheel, for use in a motor vehicle, comprises an inner metal framework defining the outer rim of the wheel and at least one substantially radially extending spoke, the framework being provided with a moulded outer coating of a plastics material of a resilient nature, so that the steering wheel is not unpleasant to grip.

It has been proposed to provide an air-bag unit within the central hub of a steering wheel, the air-bag unit being present in a housing which is located in position within the hub of the steering wheel at a final stage during the manufacture of the motor vehicle.

The air-bag unit is mounted in position in a recess within the hub of the steering wheel so as to "float". The entire air-bag unit may thus be pressed inwardly, usually against a spring bias, to actuate a horn on the motor vehicle. Alternatively, the air-bag unit may be fixed in position.

The air-bag unit is provided with a moulded plastic cover, designed to blend with the plastic moulding provided on the framework defining the steering wheel.

Disadvantages with the prior arrangement are firstly that two separate moulding processes have to be carried out, to provide, respectively, the moulding on the framework and the cover for the air-bag unit, and secondly that the cover for the air-bag unit always has the appearance of being a separate element.

The present invention seeks to provide an improved steering wheel arrangement.

According to this invention there is provided a steering wheel, the steering wheel comprising an inner framework adapted to define the rim of the steering wheel and at least one substantially radially inwardly directed spoke, and a moulding substantially surrounding the framework, the moulding defining a portion extending across a central part of the steering wheel, and defining beneath it a recess adapted to receive an air-bag unit.

Preferably the recess defines an inwardly directed projection adapted to form part of a snap joint.

A steering wheel as described above may be provided in combination with an air-bag unit, the air-bag unit being connected to the steering wheel.

Conveniently the air-bag unit comprises a housing defining a portion to be received within the recess, that portion of the housing having a projection adapted to cooperate with the projection provided within the recess to retain the housing within the recess as a snap-fit, the snap-fit comprising at least part of the means to connect the air-bag unit to the steering wheel.

Advantageously the air-bag unit defines a substantially radially outwardly directed flange, the flange defining apertures, fastening means passing through the apertures to secure the framework to the flange.

Conveniently the fastening means comprise studs carried by the frame, nuts being provided to co-operate with the studs.

Preferably the framework defines a depending portion defining at least one aperture, the housing of the air-bag unit defining a substantially cylindrical wall adapted to abut the depending means, fastening means being provided to connect the depending means with the wall of the air-bag unit.

Advantageously the depending means defines an aperture and the wall of the air-bag unit defines an aperture, fastening means passing through the apertures when co-aligned.

Conveniently the fastening means which fasten the framework to the air-bag unit housing also fasten the combination of the framework and the air-bag unit to a mounting frame which is connected to a steering shaft.

Preferably the mounting frame is substantially rigidly connected to the steering column of a motor vehicle and a crash sensor is provided mounted directly on the mounting frame, adapted to trigger the air-bag unit.

Advantageously the mounting frame is adapted to be connected to the steering column of a motor vehicle after the steering wheel and air-bag unit have been fully assembled.

Conveniently the air-bag unit defines a tubular spigot which is received on a steering column.

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 diagrammatic cross-sectional view of part of one embodiment of a steering wheel arrangement in accordance with the invention, FIGURE 2 is a diagrammatic cross-sectional view of part of an alternative steering wheel arrangement in accordance with the present invention, and FIGURE 3 is a diagrammatic cross-sectional view of part of another embodiment of a steering wheel arrangement in accordance with the invention.

Referring initially to Figure 1 of the drawings, a steering wheel comprises a metal frame 1 defining a peripheral outer ring 2, which is to define the core of the rim of the steering wheel, and a plurality of substantially radially extending spokes 3 which, in this embodiment, terminate at their inner ends with an inner ring 4.

A plurality of threaded studs 5 depend upon from the ring 4 at spaced intervals.

A plastics moulding 6 is formed on the framework 1, part of the moulding 7, surrounding the metal ring 2, forming the outer rim of the steering wheel. The moulding also has a part 8 which covers the radial spoke 3, and the moulding comprises a further portion 9 extending substantially across the central aperture defined by the ring 4, the ring 4 defining the mouth of a recess 10 which is located (in the orientation of Figure 1) below the portion 9 of the moulding 6. The under-surface of the portion 9 is provided with a notch 11, which forms a line of mechanical weakness or a "split line".

The recess 10 is provided with an inwardly directed projection 12 on the side wall of the recess.

A steering wheel, with the integral moulding, as thus described, can be manufactured in a straightforward manner, initially by preparing the metal framework 1 and subsequently by using conventional moulding techniques to add the moulding 6.

The steering wheel is adapted to be mounted on a steering column, whilst being provided with an air-bag unit located in the recess 10.

As can be seen from Figure 1, a steering column 15 is provided which terminates at its upper end with an upwardly directed threaded stud 16.

A mounting frame 17 is provided comprising a central ring 18 defining an aperture 19 therein which is received over the threaded stud 16. The mounting frame 17 has radially extending arms 19 which terminate in an outer ring 20 of substantially the same outer diameter as that of the ring 4. A plurality of apertures 21 are formed in the ring 20 adapted to be co-aligned with the depending studs 5 carried on the ring 4.

The mounting frame 17 is mounted on the stud 16, with the stud 16 passing through the aperture 19, and a nut 22 engages the threaded stud 16 to retain the mounting frame 17 in position.

An air-bag unit 25 is provided comprising a housing 26 having a horizontal base 27 defining a central aperture 28 surrounded by a peripheral of small apertures 29. The housing has an upstanding wall 30 of circular form and the base 27 defines a radially outwardly extending flange 31 which extends beyond the wall 30, the flange 31 having therein apertures 32 adapted to be co-aligned with the depending studs 5 provided on the ring 4 of the metal frame 1.

Bolts or rivets 33 pass through the small apertures 29 and through apertures 34 in a flange 35 provided on a gas generator unit 36. The bolts or rivets 33 also serve to secure, to the upper surface of the base 27 of the housing, the mouth of an air-bag 37.

A cover 38, which comprises a transport cover extends above the air-bag 37, the cover 38 being connected to the upper part of the upstanding wall 30.

A projection 39 is provided on the exterior of the wall 30.

The upstanding wall 30 of the housing 26 is dimensioned to be received within the recess 10 defined by the moulding 6. The projection 39 is adapted to co-operate with the projection 12 to form a snap joint in order temporarily to retain the air-bag unit 25 within the recess 10. As the gas generator is mounted in position, the studs 5 are passed through the apertures 32 provided in the flange 31. The combination of the steering wheel and the air-bag unit is then lowered into position on the mounting frame 17, with the studs 5 passing through the apertures 21, and finally nuts 40 are mounted in position on the lower projecting ends of the studs 5 and are tightened to secure the combination of the steering wheel and the air-bag unit to the mounting frame.

It is to be appreciated that when a vehicle is being manufactured, if a steering wheel as described with Figure 1 is utilised, as a final stage in the manufacture of the vehicle the air-bag unit may be connected to the steering wheel, and the combination of the air-bag and the steering wheel may then be mounted on the steering column.

In this way, the air-bag unit is only present in the motor vehicle at the final stage of manufacture.

Referring now to Figure 2 of the accompanying drawings, in a modified embodiment of the invention, the steering wheel comprises a framework 1 and a moulding 6 substantially as described above with reference to Figure 1, although the recess 10 provided in the moulding 6 does not, in this embodiment, have the inwardly directed projection 12, and the design of the ring 4 is slightly modified.

In this embodiment there is no separate mounting frame, but the housing of the air-bag unit 50 is designed to be connected directly to the steering column and also to the steering wheel.

As can be seen from Figure 2 in this embodiment, the air-bag unit 50 comprises a housing 51 which defines a base 52 having a central aperture 53. A tubular spigot 54 extends downwardly from the base 52 in alignment with the aperture s3, the spigot 54 having an inwardly directed flange 55 intermediate its ends. An aperture 56 is provided towards the lower end of the spigot 54 which receives a grub screw 57, and a further aperture 58 is provided just beneath the base 52, which receives a further grub screw 59.

The base 52 carries an upstanding wall 60 and terminates with a radially outwardly directed flange 61 having a plurality of apertures 62 therein adapted to receive the depending studs 5 present on the ring 4 of the metal framework 1.

A gas generator housing 60 is received within the upper part of the depending spigot 54, resting on the inwardly directed flange 55. The open mouth of an airbag 61 surrounds the gas generator 60 and is trapped between the gas generator and the inner wall of the depending spigot 54. The grub screw 59 serves to retain the gas generator in position.

A transport cover 62 may be provided extending across the open upper mouth defined by the upstanding wall 60 to retain the air-bag in position.

The air-bag unit 50, as thus described, may be mounted in position on a steering column 63, which steering column defines a recess 64 adapted to receive the grub screw 57. Thus the grub screw 57 may be tightened to secure the air-bag unit 50 firmly in position. The steering wheel may then be mounted in position, with the studs 5 passing through the aperture 62 in the flange 61, a nut 40 then being mounted on each stud 5 and tightened to secure the steering wheel in position.

Figure 3 illustrates another embodiment in which the steering wheel is provided with a framework 1' which has an outer ring 2' and at least one radially inwardly directed spoke 3'. However, the inner ends of the spoke or spokes terminate in a ring 70 which is of substantially tubular form.

A moulding 6' is provided which is substantially identical with the moulding 6 of the embodiment of Figure 1, save that there is no inwardly directed projection 12 within the recess 10. The tubular ring 70 is provided with a plurality of apertures 71 each of which receives a grub screw 72.

The steering wheel of Figure 3 is intended for use with an air-bag unit 75 which comprises a housing 76 having a base 77 which defines the central aperture 78, that aperture being surrounded by a plurality of smaller apertures 79. The base 77 terminates with a peripheral wall 80 of tubular form which extends above the base 77 and below the base 77. The part of the wall 80 depending below the base 77 is provided with a plurality of apertures 81.

The size of the wall 80 and the location of the apertures 81 is that the housing 76 may be inserted within the tubular ring 70 with the apertures 81 aligned with the grub screws 72, the apertures 81 being dimensioned to receive the grub screws 72.

A gas generator 82 is provided having a peripheral flange 83 with apertures 84 therein adapted to be aligned with the small apertures 79. Bolts or studs 85 pass through the co-aligned apertures and serve to trap part of an air-bag 86 defining the mouth of the air-bag. The airbag 86 is located within the part of the housing 76 defined by the upstanding part of the wall 80. A transport cover 87 may be provided located across the top of the upstanding part of the wall 80.

The complete air-bag unit 75 as described above may be inserted into the recess 10' defined by the moulding 6' and the grub screws 72 may be moved inwardly to engage the apertures 81. The air-bag unit 75 and the rest of the steering wheel may then be handled as a single component.

In the arrangement of Figure 3 the steering column 90 of a motor vehicle terminates at its upper end with a radially outwardly directed flange 91 which defines a plurality of apertures 92, each of which receives a downwardly directly stud 93 which is connected to a planar base of a mounting frame 94.

The mounting frame has a peripheral upstanding ring of tubular form 95 provided with a plurality of apertures 96. A respective nut 97 is secured in position on the inner part of the ring 95 in alignment with each of the apertures 96.

The ring 95 is dimensioned to be received within the lower part of the depending tubular wall 80, and the apertures 95 are located to be aligned with the grub screws 72. The grub screw 72 may then be moved radially inwardly so that the inner ends of the grub screws pass through the apertures 96 and engage the nuts 97. The grub screws may be heightened to secure the steering wheel in position on the mounting frame 94.

Mounted on the base of the mounting frame 94 is a crash sensor element 98 which is connected to a trigger mechanism 99 mounted on the gas generator 82.

It is to be appreciated that when the steering wheel has been assembled together with the air-bag unit and the mounting frame 94, the entire unit may, in the last stages of the manufacture of a motor vehicle, be mounted on the steering column 90 by inserting the studs 93 through the apertures 92 and by locating lock nuts 100 on the studs 93, and then tightening the lock nuts. The mounting frame is then securely connected to the steering column 90 and the steering wheel is thus securely fixed in place.

Since the mounting frame 94 is securely connected to the steering column 90 and since the crash sensor 98 is securely connected to the base of the mounting frame, any shock travelling up the steering column during an accident is transferred directly to the crash sensor 98, thus enabling the crash sensor to operate at an efficient and reliable manner.

In each of the embodiments described above, when the air-bag is inflated the portion 9 of the moulding 6 splits along the line of mechanical weakness defined by the notch 11, the portion 9 thus forming two doors which open as the air-bag becomes fully inflated.

Claims

CLAIMS:

1. A steering wheel, the steering wheel comprising an inner framework adapted to define the rim of the steering wheel and at least one substantially radially inwardly directed spoke, and a moulding substantially surrounding the framework, the moulding defining a portion extending across a central part of the steering wheel, and defining beneath it a recess adapted to receive an air-bag unit.

2. A steering wheel according to Claim 1 wherein the recess defines an inwardly directed projection adapted to form part of a snap joint.

3. A steering wheel according to Claim 1 in combination with an air-bag unit, the air-bag unit being connected to the steering wheel.

4. A steering wheel according to Claim 2 wherein the air-bag unit comprises a housing defining a portion to be received within the recess, that portion of the housing having a projection adapted to co-operate with the projection provided within the recess to retain the housing within the recess as a snap-fit, the snap-fit comprising at least part of the means to connect the air-bag unit to the steering wheel.

5. A steering wheel according to Claim 3 or any Claim dependent thereon wherein the air-bag unit defines a substantially radially outwardly directed flange, the flange defining apertures, fastening means passing through the apertures to secure the framework to the flange.

6. A steering wheel according to Claim 5 wherein the fastening means comprise studs carried by the frame, nuts being provided to co-operate with the studs.

7. An arrangement according to Claim 3 or 4 to wherein the framework defines a depending portion defining at least one aperture, the housing of the air-bag unit defining a substantially cylindrical wall adapted to abut the depending means, fastening means being provided to connect the depending means with the wall of the air-bag unit.

8. A steering wheel according to Claim 7 wherein the depending means defines an aperture and the wall of the air-bag unit defines an aperture, fastening means passing through the apertures when co-aligned.

9. A steering wheel according to any one of the Claims 5 to 8 wherein the fastening means which fasten the framework to the air-bag unit housing also fasten the combination of the framework and the air-bag unit to a mounting frame which is connected to a steering shaft.

10. A steering wheel according to Claim 9 wherein the mounting frame is substantially rigidly connected to the steering column of a motor vehicle and a crash sensor is provided mounted directly on the mounting frame, adapted to trigger the air-bag unit.

11. A steering wheel according to Claim 9 or 10 wherein the mounting frame is adapted to be connected to the steering column of a motor vehicle after the steering wheel and air-bag have been fully assembled.

12. An arrangement according to Claim 3 or any claim dependent thereon wherein the air-bag unit defines a tubular spigot which is received on a steering column.

13. A steering wheel substantially as herein described with reference to and as shown in Figure 1.

14. A steering wheel substantially as herein described with reference to and as shown in Figure 2.

15. A steering wheel substantially as herein described with reference to and as shown in Figure 3.

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