GB2372483A

GB2372483A - An air bag cover comprising a rupturable fabric layer

Info

Publication number: GB2372483A
Application number: GB0104715A
Authority: GB
Inventors: Andreas Bauditz
Original assignee: Autoliv Development AB
Current assignee: Autoliv Development AB
Priority date: 2001-02-26
Filing date: 2001-02-26
Publication date: 2002-08-28
Anticipated expiration: 2021-02-26
Also published as: DE10206754A1; GB2372483B; GB0104715D0

Abstract

A cover for an air bag 1 is formed of two elements. The first element 5 is a relatively strong fabric and forms a substantial part of a sleeve which receives the folded air bag. The second element 9 is formed of relatively weak material which engages the fabric 5. In a first embodiment (as shown) the strong fabric has opposing edges 7,8 and the second element overlies these edges and is secured thereto. The second element may be located inside or outside (figure 2) of the opposing edges, and may be secured by means of adhesive, heat treating, or by welding. In a second embodiment (figure 3) the weak element may completely enclose the strong fabric and be secured in place by means of mounting tabs 2 on the air bag. The weak layer of material is adapted to rupture on inflation of the air bag to permit the air bag to emerge from the sleeve.

Description

DESCRIPTION OF INVENTION "IMPROVEMENTS IN OR RELATING TO A COVER FOR AN AIR BAG" THE PRESENT INVENTION relates to a cover for an air-bag, and more particularly relates to a cover for an air-bag which is adapted to be initially located above a door or window opening in a motor vehicle and which is also adapted, when inflated, to lie adjacent the door or window opening to constitute an inflatable curtain.

It is desirable to provide a cover for an air-bag when the air-bag has been manufactured and is in the folded state, so that subsequently the air-bag can be easily mounted in position within a motor vehicle. Sometimes the cover for an air-bag is in the form of a rigid housing, which may be appropriate if the air-bag is to be mounted in position in a dashboard or in a steering wheel. However, when an air-bag is to be mounted in a recess or housing which extends above a window or door opening in a motor vehicle, it has been found convenient to provide a cover made of fabric. The fabric is wrapped around the air-bag which, when folded, has an elongate substantially cylindrical form, and the adjacent edges of the cover are stitched together. The combination of the air-bag and the cover is slightly flexible, which facilitates mounting the air-bag in position.

The cover must, of course, open in an appropriate manner when the airbag is inflated. It has been proposed, therefore, that the stitching that holds the adjacent edges of the cover together may be designed to tear or break when the air-bag inflates. The thread that is used in the stitching process may be selected to be weak so that the thread breaks. Alternatively the fabric where the stitching is provided may be so weakened by the stitching process that the fabric breaks.

It is desirable to provide a consistent tearing or opening characteristic for the cover, and none of the expedients outlined above meets this objective.

According to this invention there is provided a cover for an air-bag, the cover comprising two elements, a first said element being formed of relatively strong fabric and forming at least a substantial part of a sleeve which receives the air-bag, the second element comprising an element of relatively weak material which engages the fabric forming the sleeve and retains the fabric forming the sleeve in the sleeve condition, the relatively weak layer of fabric being adapted to rupture on inflation of the air-bag to permit the air-bag to emerge from the sleeve.

Since it is the relatively weak layer of fabric that is adaptive to rupture on inflation of the air-bag, the tearing or opening characteristic of the cover may be consistent. This helps ensure that the air-bag is deployed in a desirable and predictable manner when the air-bag is actuated.

In one embodiment the first element is positioned to at least partially embrace the folded air-bag, the second element being secured to opposed side edges of the first element to maintain those opposed side edges in predetermined relative positions.

Preferably, the two opposed side edges are spaced apart and the strip bridges across the spaced apart side edges.

Advantageously, overlapping areas of the strip and the adjacent side i edges of the first element are secured together by an adhesive, by heat-treating or by a welding seam.

In an alternative embodiment the second element surrounds the first element, overlapping side edges of the second element being retained in position relative to each other.

Conveniently the overlapping side edges are secured in position relative to each other by means of mounting tabs present on the air-bag which pass through co-aligned apertures formed in the first element, and in the opposed side edges of the second element.

Advantageously, the first element is provided with printing thereon.

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 perspective view, with part cut away, of one embodiment of the invention, FIGURE 2 is a corresponding perspective view, with part cut away, of a second embodiment, and FIGURE 3 is a further corresponding perspective view, with part cut away, of a third embodiment of the invention.

Referring initially to Figure 1 of the accompanying drawing, an air-bag 1 is shown which may, when inflated, form an inflatable curtain which is located adjacent the side windows of a vehicle in which the air-bag is fitted.

The air-bag is provided, along the edge which, when the air-bag is inflated, will be the upper edge, with a plurality of mounting tabs 2,3 each in the form of a protruding tab having an aperture therein.

The air-bag 1 is shown, schematically, in a folded condition. The airbag is totally un-inflated which means that two layers of fabric which form the front and rear of the air-bag appear, in Figure 1 as if a single layer of fabric.

The air-bag 1 is stored within a sleeve 4. The sleeve 4 is manufactured in such a way that the sleeve may readily rupture, upon inflation of the air-bag, whilst still providing the air-bag with the desired degree of protection before inflation of the air-bag.

The sleeve 4, as shown in Figure 1, is constituted by two separate elements.

The first element, 5, is an elongate element which defines, at appropriate spacings, apertures 6, through which the mounting tabs 2,3 etc. may protrude. The apertures 6 are located at positions which are equidistantly spaced between two opposed side edges 7,8 of the element 5. The element 5 is formed from a fabric or cloth which has a relatively high strength. The fabric or cloth may be woven or knitted or may be a non-woven fabric. Printing, with specific information relating to the air-bag contained within the sleeve 4 and/or with the name of a car manufacturer or air-bag manufacturer is applied, in this embodiment, to the exterior of the fabric or cloth that forms the element 5, for example by using a roller. Instead of using roller applied printing, a laminate carrying printing may be applied to one surface of the fabric or cloth thus further enhancing the strength of the element 5.

The second element is an elongate strip 9 of material. The material of the strip 9 is weaker than fabric or cloth of the element 5.

In the described embodiment the element 5 is folded to partially embrace the folded air-bag 6 and the strip 9 bridges across the gap between the opposed side edges 7,8 of the strip 9. The strip 9 is adjacent the inner faces of the side edges of the strip, so as to be in the interior of the sleeve 4. The overlapping areas of the strip 9 and the adjacent side edges of the element 5 are secured together by an adhesive, by heat treating or by a welding seam. Alternatively stitching could be utilised, but stitching may serve to increase the manufacturing cost. It is envisaged that the printing step and the connecting step between the two elements 5 and 9 forming the sleeve 4 may be effected simultaneously or may be effected separately. The strip 9 serves to maintain the opposed side edges 7,8 in a predetermined relative position, and thus the element 5 and strip 9 together form a tubular sleeve.

It is envisaged that initially the sleeve 4 will be fabricated and the sleeve 4 will then be mounted on to the folded air-bag or the folded air-bag will be inserted into the sleeve 4.

On deployment of the air-bag the relatively weak strip 9 will tear or rupture, thus allowing the opposed edges 7,8 of the element 5 to move apart, and permitting the inflating air-bag to emerge from the sleeve 4 to adopt a desired final position.

Figure 2 illustrates an embodiment which is extremely similar to the embodiment of Figure I save that the strip 9 of relatively weak material is on the exterior of the sleeve formed by the element 5.

In the embodiment of Figure 3, the element 5 of relatively strong fabric or cloth is totally surrounded by a relatively wide strip 10 formed of the relatively weak material. The opposed edges of the strip 10 actually overlap each other in the region of the mounting tabs 2 etc. and each mounting tab passes through three apertures, namely an aperture 6 formed in the element 5 of relatively strong fabric or cloth and apertures 11 formed in one edge part of the element 10 of relatively weak material and a further aperture 12 formed in the other, opposed, edge part of the element of relatively weak material 10. The three apertures are co-aligned. The tabs 2 etc. thus serve to maintain the strip 10 of relatively weak material in position, with the overlapping side edges of the strip being retained in position relative to each other.

On deployment of the air-bag the strip 10 of relatively weak material will rupture.

Claims

CLAIMS: 1. A cover for an air-bag, the cover comprising two elements, a first said element being formed of relatively strong fabric and forming at least a substantial part of a sleeve which receives the air-bag, the second element comprising an element of relatively weak material which engages the fabric forming the sleeve and retains the fabric forming the sleeve in the sleeve condition, the relatively weak layer of fabric being adapted to rupture on inflation of the air-bag to permit the air-bag to emerge from the sleeve.
2. A cover according to Claim 1 wherein the first element is positioned to at least partially embrace the folded air-bag, the second element being secured to opposed side edges of the first element to maintain those opposed side edges in predetermined relative positions.
3. A cover according to Claim 2 wherein the two opposed side edges are spaced apart and the strip bridges across the spaced apart side edges.
4. A cover according to Claim 3 wherein overlapping areas of the strip and the adjacent side edges of the first element are secured together by an adhesive, by heat-treating or by a welding seam.
5. A cover according to Claim 1 wherein the second element surrounds the first element, overlapping side edges of the second element being retained in position relative to each other.
6. A cover according to Claim 5 wherein the overlapping side edges are secured in position relative to each other by means of mounting tabs present on