GB2372237A

GB2372237A - A substantially gas tight air bag

Info

Publication number: GB2372237A
Application number: GB0103912A
Authority: GB
Inventors: Norbert Drossler; Stefan Muller
Original assignee: Autoliv Development AB
Current assignee: Autoliv Development AB
Priority date: 2001-02-16
Filing date: 2001-02-16
Publication date: 2002-08-21
Anticipated expiration: 2021-02-16
Also published as: GB0103912D0; GB2372237B

Abstract

An air bag comprises an outer covering formed from two layers of fabric 1,2 which cover an inner unit 9 formed from two foil layers 10,11 of gas tight plastics material which is superimposed and secured together in a substantially gas tight way 14, at least around an exterior border of an area adapted to be inflated. The gas tight layers 10,11 may be secured together by means of welding or adhesive, and the outer fabric layers may be stitched together 23 in such a way that the stitching is located outside of the inflatable area of the gas tight layers. The gas tight layers may be secured together to form a plurality of separate inflatable zones thus forming an inflatable curtain (figure 4) for protecting the occupant of a vehicle in a side impact collision. The present invention seeks to provide an air bag which may remain inflated for several seconds.

Description

DESCRIPTION OF INVENTION "IMPROVEMENTS IN OR RELATING TO AN AIR-BAG" THE PRESENT INVENTION relates to an air-bag, and more particularly relates to an air-bag, such as a so-called inflatable curtain, adapted to be inflated to protect the occupant of a motor vehicle in the event that an accident should arise.

It has been proposed to provide an air-bag, known as an inflatable curtain, which is initially stored in a recess in the roof of a motor vehicle at a position above a door or window opening, and which is adapted, on inflation, to form a so-called inflatable curtain located between the occupant of the vehicle and the adjacent side windows. An inflatable curtain of this type may be particularly advantageous in the event of a side impact, or roll-over situation. In a roll-over accident, the inflatable curtain may need to remain inflated for a relatively long period of time, as compared with the conventional air-bags, if an appropriate degree of protection is to be provided to the occupant of the vehicle.

The present invention seeks to provide an air-bag which can remain inflated for a relatively long period of time. It is to be understood that a conventional air-bag may only be inflated for a period measured in terms of milliseconds, or other small fractions of a second, but the present invention seeks to provide an air-bag where the inflation time may be measured in terms of seconds.

According to this invention there is provided an air-bag, the air-bag comprising an outer covering formed of fabric, which covers an inner unit formed from two foil layers of gas-tight plastics material which are superimposed and secured together in a substantially gas-tight way, at least around the exterior border of an area adapted to be inflated.

Conveniently the outer covering if formed from two super-imposed layers of fabric of substantially the same size and shape, and the inner unit, and the inner unit is formed of two foil layers also of substantially the same size and shape.

The foils may be secured together by an adhesive, or may be secured together by welding.

Conveniently the foils are secured together to define a plurality of separate zones adapted to be inflated.

Advantageously the foils define a plurality of said zones which, when inflated, form discrete chambers or cells, the axes of which are substantially parallel.

Preferably the fabric cover comprises two layers of fabric, the foils being sandwiched between the two layers of fabric, the two layers of fabric being secured together by stitching, the stitching being located outside the inflatable area.

Conveniently the stitching passes through a peripheral part of the foil layers on the outside of the inflatable area.

Advantageously the stitching passes through a region where the foil layers are secured together in a gas-tight way.

Preferably the stitching passes through the foil layers in one or more areas where the foil layers are secured together to form said zones.

Advantageously a further foil or cloth is provided on the interior of the inner unit.

Conveniently an air-bag in accordance with the invention is in the form of an inflatable curtain.

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 an exploded view of the component parts of an air-bag in accordance with the invention, FIGURE 2 is a section view of the air-bag taken on the line A-A of Figure 1, FIGURE 3 is a section view of an air-bag in accordance with an alternative embodiment of the invention, as if taken on the line A-A of Figure 1, FIGURE 4 is a perspective view of a completed air-bag in accordance with the first embodiment of the invention, FIGURE 5 is a sectional view taken as if on the line B-B of Figure 4, but showing a modified embodiment of the invention, and FIGURE 6 is a view, corresponding to Figure 5, showing a further modified embodiment of the invention.

Referring initially to Figure 1, the components of an air-bag are illustrated, and those components, as will become clear from the following description, form an air-bag which, when inflated, may be used as an inflatable curtain.

The components of the air-bag comprise a first outer fabric layer 1, and a second outer fabric layer 2. The fabric layers 1 and 2 are of substantially the same shape. The first layer I defines a relatively large rectangular area 3 and, extending therefrom, a relatively narrow extension piece 4. The extension piece 4 is aligned with one long side edge of the rectangular area 3. The upper edge of the layer 1, as illustrated, is provided with a plurality of spaced-apart apertured projecting lugs 5 which are used as mounting lugs to mount the airbag in position.

The lower fabric layer 2 has a rectangular area 6 corresponding to the rectangular area 3, and an extension piece 7 corresponding to the extension piece 4. The lower layer, in this embodiment of the invention has projecting lugs 8 which correspond with the lugs 5.

An inner unit 9 is provided, which is formed from the two foil layers, namely an upper foil layer 10 and a lower foil layer 11. The foil layers are not formed of a conventional air-bag fabric, but instead are formed of a plastics material. The plastics material is chosen to be substantially gas-tight, and may be a thermoplastic material, such as polypropylene or polyethylene, or may be made from a silicone material.

The upper foil layer 10 and the lower foil layer 11 both have exactly the same configuration. In the described embodiment of the invention the upper foil layer 10 and the lower foil layer 11 are two separate layers which are super-imposed, but in a modified embodiment of the invention, which will be described in greater detail with reference to Figure 6, a single layer of foil may be folded, along a fold-line, to produce the necessary upper foil layer and lower foil layer. The superimposed foil layers have a rectangular region 12 which generally corresponds with the above-described rectangular regions 3 and 6. However, the rectangular region 12 may have slightly smaller dimensions than the rectangular regions 3 and 6. The foil layers 10 and 11 also have extension pieces 13 which correspond with extension pieces 4 and 7 described above.

Again the dimensions of the extension pieces 13 may be slightly less than the dimensions of the extension pieces 4 and 7.

Shown on the upper foil layer 10 is a region 14 of complex shape, which is a region where the upper foil layer 10 is secured to the lower foil layer 11 in a substantially gas-tight manner. The upper foil layer 10 may, for example, be adhered to the lower foil layer 11 by applying adhesive to the appropriate face of one of the foil layers in the region 14, and by then pressing the two foils together. Alternatively, the foil layers may be interconnected using a sonic welding or a thermal welding technique, or by using any other appropriate mechanism to secure the two foil layers together.

The region 14 extends substantially around the periphery of the superimposed foil layers 10 and 11, except at the relatively narrow end of the extension piece 13, and thus the region 14 substantially surrounds an area 15 that surrounds a substantially gas-tight volume which is adapted to be inflated, that area communicating with a passage or gas duct 16 defined within the extension piece 13. The region 14 also includes linear portions 17 which extend into the general area 15 dividing the area 15 into separate zones, such as zone 18. The zones are such that, when the air-bag is inflated, the zones form discrete chambers or cells. Typically the chambers or cells may be cylindrical, but the chambers or cells may have other shapes. In the described embodiment the cells have axes which are substantially parallel and which extend substantially perpendicularly to the lower edge of the air-bag.

Referring to Figure 2, it is to be appreciated that the upper foil layer 10 is secured to the lower foil 11 within the whole of the region 14. The region 14 is relatively broad to provide the necessary gas-tight seal.

In an alternative embodiment of the invention, as shown with reference to Figure 3, the upper foil layer 10 is secured to the lower foil layer 11, not within the whole of the relatively wide region 14, but by two slightly spacedapart generally co-extensive lines 20, 21 of securement. The lines may be lines of adhesive or lines of welding. Each of the lines 20,21 constitutes a substantially gas-tight seal. The lines 20, 21 together trace the boundary of the region 14.

When the inner unit 9 has been fabricated, the inner unit is located between the upper outer fabric layer 1 and the lower outer fabric layer 2. The fabric layers 1, 2 and the inner unit 9 may be manually aligned, or alignment may be effected by using a plurality of registering pins which pass through registering apertures formed, for that purpose, in the outer layers of fabric and the inner unit.

When the outer layers of fabric and the inner unit have been co-aligned, the outer layers of fabric are stitched together with stitching 22, as shown in Figure 4. The stitching, as shown in Figure 4, passes through the region 14 where the upper foil 10 is secured to the lower foil 11 in a substantially gastight manner. Thus the stitching 22 does not penetrate the inflatable area 15 of the foil, but instead, penetrates part of the foil which is on the exterior of the inflatable area. In the embodiment shown in Figure 4, the stitching 22 does not only extend around the periphery of the inflatable area 15, but also extends along the linear portions 17 of the region 14, so that the outer fabric layers will themselves take the form of inflated cells when the air-bag is inflated. It is to be appreciated that the stitch line passes through the foils at a position outside the inflatable area so that the integrity of the inflatable area 15 is not damaged.

In a first modified embodiment of the invention, as shown in Figure 5, the inner element 9 is shown in position between the outer layers of fabric 1, 2.

The stitching 23 in this embodiment of the invention extends through the superimposed layers of fabric 1, 2 and also the portions of the inner unit 9 which extend beyond the region 14 where the foil layers 10 and 11 are secured together. Thus, the stitching 23 does not penetrate the region 14 where the foil layers are secured together in a substantially gas-tight manner, but penetrates the foil layers at a location which is outward of the region 14, and thus spaced away from the inflatable area 15. Again, the integrity of the inflatable area 15 is not damaged.

Referring now to Figure 6, in a further modified embodiment of the invention, the two outer layers of the fabric are formed from a single fabric layer 24, which is folded about a fold region or fold-line 25. The superimposed edges of the fabric layer 24, at a position remote from the fold-line 25, are secured together by stitching 26. In this embodiment, the inner element comprises a single sheet of foil 27 which is folded about a fold region or foldline 28. The super-imposed edges of the sheet 27 are secured together in a region 29 in a substantially gas-tight manner. Mounted on the interior of the inner element, adjacent the fold-line 28, is an inner foil or cloth 30. The cloth 30 is provided on the interior of the inner element formed by the foil 27 in order to enhance the strength of the inner element and prevent the inner element being damaged. It is to be understood that a lance or gas diffuser forming part of a gas supply arrangement will typically be inserted into the inner element, and will occupy the position as exemplified by the gas duct 31 shown in Figure 6. As the lance or gas diffuser, or gas duct is inserted into the inner unit, the foil constituting the inner unit may inadvertently be damaged, and when the air-bag is deployed an aggressive stream of gas may impinge on the interior of the inner element 9 adjacent the lance or gas diffuser, which also may damage the inner unit. The additional foil or fabric 30 is intended to minimise the risk of damage occurring.

The entire assembly may be utilised in the manner of a conventional inflatable curtain. The passage 16 may be connected to a gas generator which is controlled by a crash sensor so that the gas generator generates gas in the event that a side impact or roll-over situation occurs. The gas will flow through the passage 16 into the main inflatable area 15 between the foil layers, and will cause the separate zones, as exemplified by the zone 18, to inflate. As the zones inflate to form discrete cells or chambers, the overall width of the airbag, as shown, will reduce. The lower left-hand comer of the air-bag, in the orientation shown in Figure 1 will be connected to an anchoring point and, as the overall width of the air-bag reduces, a line of tension will consequently be created extending from the anchor point to one of the lugs 8, connecting the airbag to the vehicle, which will help maintain the inflated inflatable curtain in the appropriate position.

It is to be understood that in an embodiment of the invention, the gas is injected into an area which is bounded by the foils, which are substantially gastight, the foils themselves being interconnected by a substantially gas-tight bonding in the region 14. The air-bag, therefore, is able to remain inflated for a substantial period of time, as compared with a conventional air-bag. Because the foils are contained within the fabric outer layers, the foils may not be damaged if the inflating air-bag encounters, for example, broken glass from a window. Thus the outer fabric layers provide inherent strength whilst the inner foil layers provide the desirable gas-tightness. The fabric layers serve to restrain the foil layers of the inner unit on deployment of the air-bag, to prevent over-inflation of the inner unit 9. As the inner unit is inflated, the inner unit effectively serves to inflate the bag constituted by the outer layers. The bag constituted by the outer layers has a defined volume, and the outer layers thus prevent the inner unit from over-inflating. The outer fabric layers thus prevent substantial forces being applied to the region 14 of the inner unit where the foil layers are secured together.

The properties of the foil layers of embodiments of the invention are preferably related to the properties of the fabric. For example, if a fine mesh fabric is used, only a thin foil layer is necessary, whereas, if an open weave or net-like fabric is used, a much thicker foil layer should be utilised.

The foil layers of the inner unit 9 may be connected to the outer fabric layers, for example with adhesive, at selected points (in addition to the stitching 22) in order to minimise the risk of the foil layers vibrating or wrinkling on deployment of the air-bag.

In the present Specification"comprise"means"includes or consists of' and"comprising"means"including or consisting of.

The features disclosed in the foregoing description, or the following Claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

CLAIMS: 1. An air-bag, the air-bag comprising an outer covering formed of fabric, which covers an inner unit formed from two foil layers of gas-tight plastics material which are super-imposed and secured together in a substantially gastight way, at least around the exterior border of an area adapted to be inflated.
2. An air-bag according to Claim 1 wherein the outer covering if formed from two super-imposed layers of fabric of substantially the same size and shape, and the inner unit, and the inner unit is formed of two foil layers also of substantially the same size and shape.
3. An air-bag according to Claim 1 or 2 wherein the foil layers are secured together by an adhesive.
4. An air-bag according to Claim 1 or 2 wherein the foil layers are secured together by welding.
5. An air-bag according to any one of the preceding Claims wherein the foils are secured together to define a plurality of separate zones adapted to be inflated.
6. An air-bag according to Claim 5 wherein the foils define a plurality of said zones which, when inflated, form discrete chambers or cells, the axes of which are substantially parallel.
7. An air-bag according to any one of the preceding Claims wherein the fabric cover comprises two layers of fabric, the foils being sandwiched between the two layers of fabric, the two layers of fabric being secured together by stitching, the stitching being located outside the inflatable area.
8. An air-bag according to Claim 6 wherein the stitching passes through a peripheral part of the foil layers on the outside of the inflatable area.
9. An air-bag according to Claim 6 or 7 wherein the stitching passes through a region where the foil layers are secured together in a gas-tight way.
10. An air-bag according to Claim 9 as dependent upon Claim 5 or 6 wherein the stitching passes through the foil layers in one or more areas where the foil layers are secured together to form said zones.
11. An air-bag according to any one of the preceding Claims wherein a further foil or cloth is provided on the interior of the inner unit.
12. An air-bag according to any one of the preceding claims in the form of an inflatable curtain.
13. An air-bag substantially as herein described with reference to and as shown in Figures 1, 2 and 4 of the accompanying drawings.
14. An air-bag substantially as herein described with reference to and as shown in Figures 1 and 4 as modified by Figure 2 of the accompanying drawings.
15. An air-bag substantially as herein described with reference to and as shown in Figures 1 and 4 as modified by Figure 5 of the accompanying drawings.
16. An air-bag substantially as herein described with reference to and as shown in Figures 1 and 4 as modified by Figure 6 of the accompanying drawings.
17. Any novel feature or combination of features disclosed herein.