GB2309943A

GB2309943A - Increased width catch straps in the region of the gas generator.

Info

Publication number: GB2309943A
Application number: GB9602436A
Authority: GB
Inventors: Leif Erixon
Original assignee: Airbags International Ltd
Current assignee: Airbags International Ltd
Priority date: 1996-02-07
Filing date: 1996-02-07
Publication date: 1997-08-13
Anticipated expiration: 2016-02-07
Also published as: GB9602436D0; GB2309943B

Abstract

An air-bag has straps 20 of a predetermined width with portions 24 of a greater width located adjacent the hot gas outlets of a gas generator to effectively form flaps which, when subjected to a stream of gas, fold back 27. This minimises the risk of the edges of the fabric being burnt or melted by the hot gas; the flaps are also non-load bearing to permit a degree of tolerance to burning should this occur. This enables relatively thin fabric to be utilised for the manufacture of the straps.

Description

DESCRIPTION OF INVENTION "INPROVEMENTS 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 to be utilised in a motor vehicle to provide protection for the driver or other occupant of the vehicle in the event that an accident should arise.

It has been proposed to provide an air-bag in a vehicle, the air-bag being associated with means adapted to inflate the air-bag in response to a signal generated by an impact or deceleration sensor mounted on the vehicle.

Typically such an air-bag is inflated by means of a gas generator, the gas generator incorporating a pyrotechnic charge. The air-bag can thus be inflated very rapidly.

The part of the air-bag that is intended to provide protection for the driver thus moves towards the driver with a substantial speed. It is possible for this part of the air-bag to continue its movement towards the driver, beyond its intended final position, as the bag inflates, due to the momentum of the fabric forming the bag. This part of the bag may thus inadvertently strike the driver or occupant of the vehicle in an undesirable manner.

It has been proposed, therefore, to provide straps within the interior of an air-bag to prevent the part of the air-bag that is intended to provide protection for the driver or other occupant of a vehicle inadvertently hitting the driver or occupant of a vehicle.

A typical air-bag is provided with an opening in the wall of the air-bag, which receives part of a gas generator. Typically, the gas generator includes a cylindrical housing that is inserted through the opening in the air-bag into the interior of the air-bag. A plurality of gas outlet openings are formed in the outer periphery of the cylindrical housing. When the gas generator is activated, hot gas flows in radially outwardly directed streams through the gas outlets.

The straps, as mentioned above, are normally fixed to a section of the air-bag close to the opening that receives the gas generator, and are also fixed to an opposed wall of the air-bag.

When the gas generator is activated, the hot streams of gas will flow close to the straps or will impinge on the straps, at least in the region where the straps are fixed to the air-bag close to the opening that receives the gas generator. The material that forms the straps may be damaged by the heat. If the straps are formed from cut fabric which has cut edges, then at least the edges of the fabric will be damaged. To maintain the strength in the straps, either the straps are made of relatively thick material or an element of heat-resistant material is provided to protect the straps. In either event, however, the cost of the air-bag is increased, and difficulties may be encountered in packing the air-bag in the relatively small space that is available.

The risk of this occurrence means that the strap 9 has to be made to be relatively thick and consequently, the material used to form the ring and the strap is relatively expensive.

The present invention seeks to provide an improved air-bag arrangement.

According to this invention there is provided an air-bag arrangement for use in a motor vehicle, the air-bag arrangement comprising a gas generator defining one or more outlets for hot gas, an air-bag adapted to be inflated by the gas generator, one or more straps extending from a position adjacent the gas generator to a position in the bag remote from the gas generator, the or each strap having a portion of predetermined width and having a further portion of greater width, the further portion of greater width being located so that, in use, the portion of greater width is located adjacent the aperture or selected apertures of the gas generator.

Preferably the said straps forms part of an element, the element comprising a ring-shaped region defining a central aperture adapted to be mounted on a gas generator, the said straps extending substantially radially from the ring portion, the portion of greater width of each strap being located adjacent the ring portion, the portion of predetermined width of each strap being adjacent the free end of each strap.

Conveniently the ring-shaped portion of the element is provided with a plurality of apertures, the ring-shaped portion being adapted to be brought into substantial alignment with a flange carried by a housing of the gas generator, rivets or other fastening means passing through apertures in the flange and the corresponding apertures in the ring portion.

Advantageously the portion of each strap of greater width is separated from the portion of each corresponding strap of the predetermined width by a shouldered region.

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 a priorproposed air-bag arrangement, FIGURE 2 is a view of part of the arrangement of Figure 1, FIGURE 3 is a plan view of an element forming part of an air-bag arrangement in accordance with the invention, and FIGURE 4 is a perspective view of the element of Figure 2 in the condition that it will occupy when incorporated in an inflated air-bag.

Referring to FIGURE 1 of the accompanying drawings, which is a part sectional view of a prior-proposed air-bag arrangement, a gas generator 1 is provided in the form of a cylindrical housing containing a pyrotechnic charge, the housing having a plurality of radially outwardly directed outlet apertures 2 in the side wall of the housing. When the pyrotechnic charge is activated, streams of hot gas flow radially outwardly through the apertures 2. The cylindrical housing is inserted into the interior of an air-bag through a hole formed in the air-bag.

The housing is provided with a radially outwardly extending flange 3. Rivets, such as the rivet 4, pass through the flange and also pass through a locking ring 5.

Sandwiched between the flange 3 and the locking ring 5 is part of a container 6 in which the gas generator and airbag are mounted, a peripheral part of the air-bag 7 (which surrounds the hole through which the housing is inserted into the air-bag), a ring 8 which is formed integrally with at least the lower parts of a plurality of straps 9 and an element of heat resistant material 10 adapted to provide protection for the straps 9. As shown in Figure 1, the straps 9 are secured by stitching 11 to further strap portions 12 which in turn are connected to a region 13 of the air-bag which is opposite the gas generator and which is adapted to provide protection for the driver or other occupant of the vehicle.

FIGURE 2 illustrates the ring 8, straps 9 and heatresistant elements 10.

It can be seen, from Figure 1, which shows the airbag in the inflated condition, that the strap 9 passes immediately in front of the apertures 2 through which the hot gas from the pyrotechnic charge within the housing 1 emerges. The hot gas may damage the material forming the strap 9, which is why the strap is associated with a heat resistant element 10. Even though the strap is associated with a heat resistant element 10, the edges of the strap 9 may be melted or ignited by the hot gas emerging from the housing 1.

Turning now to Figures 3 and 4 of the accompanying drawings, it is to be appreciated that in a preferred embodiment of the invention, an element is provided which replaces the element defining the ring 8 and straps 9 of the arrangement shown in Figures 1 and 2. The remaining parts of the arrangement shown in Figure 1 will remain unchanged. Thus, in the presently described embodiment of the invention an element is provided, made from fabric, which defines one or more straps 20 adapted to extend from a position adjacent a gas generator, equivalent to the gas generator 1 of Figure 1 at least towards region 13 of an air-bag.

Referring to Figure 3 of the accompanying drawings, the element, of an appropriate fabric or material, defines a substantially central ring-shaped region 21 defining a central aperture 22 which is adapted to pass over the upper part of the gas generator 1 that defines the apertures 2 through which hot gases may escape from the gas generator 1. The ring-shaped part of the element is provided with a plurality of apertures 23 adapted to accommodate the rivets 4.

Each strap portion 20 extends substantially radially outwardly from the ring 21. The free end of each strap has a width W. The portion of the strap adjacent the ring-shaped portion 21 has a greater width, X. It is to be appreciated that the portion of the strap 20 of the width W is separated from the portion 24 of width X by a shouldered region 25. The portion 24 of greater width can be considered to be an extension of the portion of the strap of width W provided with two additional side flaps. The flaps may fold, and it can be seen that if the flaps are forced downwardly out of the plane of the element as illustrated in Figure 3, the flaps will each fold along a respective substantially diagonally extending fold line 26.

It will be appreciated that when the element illustrated in Figure 3 is mounted on the gas generator, and the air-bag is inflated, the strap elements 20 will extend upwardly generally as shown in Figure 4. The portions 24 of the straps are therefore located adjacent the apertures 2 of the gas generator 1. Gas emerging through the apertures 2 will cause the flaps to fold away from the gas generator, as indicated by the arrows 27 in Figure 4, along the fold lines 26. Thus no free edge portions of the fabric are immediately accessible to the hot gas, consequently reducing any risk of the fabric being molten and/or any risk of the fabric being burnt. Even if the fabric at the edge of the flap is molten and/or burnt, it is to be appreciated that this part of the strap arrangement does not absorb any tension, but can be considered as an additional non-load-bearing flap.

The illustrated element maybe made of relatively thin material, since there is a substantially reduced risk of the material being burnt or melted by the hot gas.

Claims

CLAIMS:

1. An air-bag arrangement for use in a motor vehicle, the air-bag arrangement comprising a gas generator defining one or more outlets for hot gas, an air-bag adapted to be inflated by the gas generator, one or more straps extending from a position adjacent the gas generator to a position in the bag remote from the gas generator, the or each strap having a portion of predetermined width and having a further portion of greater width, the further portion of greater width being located so that, in use, the portion of greater width is located adjacent the aperture or selected apertures of the gas generator.

2. An air-bag arrangement arrangement according to Claim 1 wherein the said straps forms part of an element, the element comprising a ring-shaped region defining a central aperture adapted to be mounted on a gas generator, the said straps extending substantially radially from the ring portion, the portion of greater width of each strap being located adjacent the ring portion, the portion of predetermined width of each strap being adjacent the free end of each strap.

3. An air-bag arrangement according to Claim 2 wherein the ring-shaped portion of the element is provided with a plurality of apertures, the ring-shaped portion being adapted to be brought into substantial alignment with a flange carried by a housing of the gas generator, rivets or other fastening means passing through apertures in the flange and the corresponding apertures in the ring portion.

4. An air-bag arrangement according to any one of the preceding Claims wherein the portion of each strap of greater width is separated from the portion of each corresponding strap of the predetermined width by a shouldered region.

5. An air-bag arrangement substantially as herein described with reference to and as shown in Figure 1 of the accompanying drawings as modified by Figures 3 and 4 of the accompanying drawings.

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