GB2383305A

GB2383305A - Air bag with adjacent asymmetrical chambers

Info

Publication number: GB2383305A
Application number: GB0130728A
Authority: GB
Inventors: Stefan Muller
Original assignee: Autoliv Development AB
Current assignee: Autoliv Development AB
Priority date: 2001-12-21
Filing date: 2001-12-21
Publication date: 2003-06-25
Anticipated expiration: 2021-12-21
Also published as: GB2383305B; GB0130728D0

Abstract

An air bag is formed from two super-imposed layers of fabric 31,32. The layers are interconnected by a plurality of parallel seams 33,35 to define a plurality of adjacent cells 41,42. One layer of fabric 32 extending between two adjacent seams has a substantially greater width than the other layer of fabric 31 extending between the seams. The fabric of greatest width may be provided with re-entrant tucks or folds 37,38 (44, figure 7). The air bag when inflated provides an enhanced cushioning effect due to the increased width of the air bag between an occupants head 25 and an object struck 24 compared to that of an air bag with equal widths of fabric 21. The present invention also provides a method of manufacturing such an air bag.

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 incorporating a plurality of adjacent cells or chambers.

It has been proposed to provide an air-bag in the form of an inflatable curtain to provide protection for occupants of a motor vehicle especially during a side impact or roll-over accident situation.

Such an inflatable curtain is usually stored in a recess or housing provided in the roof lining of the motor vehicle extending above the door openings of the vehicle. In the event that an accident should arise, the inflatable curtain is inflated and extends downwardly from the roof lining to form a relatively thin inflated curtain located between the windows in the motor vehicle and the head of an occupant of the vehicle sitting adjacent the window.

Typically such an inflatable curtain has one or more inflatable regions, with each inflatable region being formed from a plurality of cells or chambers. Each cell or chamber is of elongate form, and the cells or chambers are generally vertical, so that each cell or chamber has an axis which substantially intersects a line of tension which is created when the inflatable curtain is

deployed, that line of tension running from a front-most anchoring point provided towards the front of the vehicle to a rear-most anchoring point provided towards the rear of the vehicle. The line of tension assists in holding the inflatable curtain in a predetermined position, and minimises the risk of the inflatable curtain flapping in an undesirable manner.

Other air-bags, such as side air-bags, or air-bags to be located beneath the feet of vehicle occupants may also be provided with adjacent generally parallel cells.

Typically, an inflatable curtain, or other air-bags having parallel cells, is formed from two superimposed layers of fabric which are secured together at selected points, either using sewing or using a one-piece weaving technique to form seam lines between the adjacent cells. The cells, on inflation, may become substantially cylindrical but, due to the effect caused by the line of tension, it is more common for the cells to have an oval form, when viewed in cross-section, when inflated. The thickness of the inflatable curtain or air-bag in the region immediately adjacent a seam is therefore not great, and the inflatable curtain may therefore, in certain circumstances, fail to provide an optimum degree of protection.

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

According to one aspect of this invention there is provided an air-bag, the air-bag being formed from two superimposed layers of fabric, the layers of fabric being interconnected by a plurality of seams to define a plurality of adjacent cells or chambers, one layer of fabric extending between adjacent

seams defining a cell or chamber having a substantially greater width than the other layer of fabric extending between the seams.

Preferably the air-bag is in the form of an inflatable curtain.

Conveniently the seams are formed by stitching.

Alternatively the seams are formed by gluing or welding.

According to another aspect of this invention there is provided a method of manufacturing an air-bag, the method comprising the steps of taking a first layer of fabric and taking a second layer of fabric, folding the first layer of fabric with a plurality of adjacent re-entrant folds or tucks, and securing portions of the first layer of fabric between the re-entrant folds or tucks to the second layer of fabric to form seams, the seams interconnecting the two layers of fabric and forming, together with the layers of fabric, adjacent chambers or cells, the width of the first layer of fabric between two adjacent seams being substantially greater than the width of the second layer of fabric between the two adjacent seams.

Preferably the re-entrant folds are hot-ironed.

In one embodiment there is one re-entrant fold between each adjacent pair of seams.

In an alternative embodiment there are two oppositely directed re-entrant folds between two adjacent seams.

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 view of an inflatable curtain for purposes of explanation, FIGURE 2 is a diagrammatic cross-sectional view of a prior art inflatable curtain in an accident situation, FIGURE 3 is an elevational view of part of an inflatable curtain according to the invention, FIGURE 4 is a sectional view of part of the inflatable curtain as shown in Figure 3, FIGURE 5 is a view corresponding to Figure 2 illustrating the curtain of Figures 3 and 4, with part of the curtain of Figure 2 shown in phantom, FIGURE 6 is a view corresponding to Figure 3 showing a modified embodiment of the invention, FIGURE 7 is a view corresponding to Figure 4 illustrating the embodiment of Figure 6, and FIGURE 8 is a view corresponding to Figure 5 showing the embodiment of Figures 6 and 7.

Referring initially to Figure 1, an air-bag arrangement in the form of an inflatable curtain 1 is illustrated for purposes of explanation. The air-bag, as shown in Figure 1, may be a prior art arrangement or may be an embodiment of the invention.

Referring to Figure 1, an air-bag in the form of an inflatable curtain I is shown mounted in a motor vehicle 2, the motor vehicle 2 having an"A"-Post 3 which extends towards a roof line 4. The vehicle incorporates a"B"-Post 5 and a"C"-Post 6. A recess or housing 7 is provided which extends part-way up the "A"-Post 3, along the roof line 4, across the top of the"B"-Post 5, and part-way down the"C"-Post 6. Contained within the recess is an elongate gas supply duct 8 which is connected to a gas generator 9. The gas supply duct 8 is mounted within the upper part of the inflatable curtain 1. The inflatable curtain I is initially stored within the recess, but is shown in the inflated condition. The inflatable curtain 1 is formed of two superimposed layers of fabric, the layers of fabric being interconnected by means of seams 10 to form a plurality of spaced-apart inflatable cells or chambers 11. Each cell or chamber, in the illustrated embodiment, has a substantially vertical axis which intersects the lower-most edge 12 of the inflatable curtain 1. In the illustrated embodiment the inflatable curtain extends completely across the front door opening defined between the"B"-Post 5 and the"A"-Post 3, and the rear door opening defined between the"B"-Post 5 and the"C"-Post 6. The upper edge of the inflatable curtain 1 is secured to the recess or housing 7 at spaced-apart points which extend along the whole length of the recess or housing 7. The lower edge 12 of the inflatable curtain 1 is substantially horizontal.

The inflatable curtain 1 is configured to be stored within the recess or housing 7. Thus the lower edge of the inflatable curtain 1 is, in the uninflated

state, of greater length than the direct distance between the two opposed ends of the recess or housing 7. On inflation of the inflatable element, the individual cells or chambers distend, effectively reducing the length of the lower edge of the inflatable element and creating a line of tension.

In a prior proposed inflatable curtain, the curtain is formed simply by superimposing two layers of fabric and securing them together to form the seams, and, for any particular cell or chamber 11, the width of each of the two layers of fabric forming the cell of chamber, extending between the two seams which define the chamber, will be the same. It will be understood, therefore, that when the inflatable curtain 1 has inflated, and a line of tension has been created, the cells will adopt a generally oval form. If reference is made to Figure 2, two adjacent cells 21,22 are shown with a seam 23 between them, the cells being of oval form. Figure 2 also illustrates a solid object such as a tree 24 and illustrates the head 25 of an occupant of the vehicle, in positions they may adopt during an accident. It can be seen that in the particular situation illustrated in Figure 2, both the head of the occupant and the tree are co-aligned with the seam 23, and it will be understood that not much compression of the inflated chambers 21 and 22 is required for the head 25 to impact with the tree 24.

Referring now to Figures 3 and 4 of the accompanying drawings, part of an inflatable curtain in accordance with the invention is illustrated. The inflatable curtain may be an inflatable curtain of the design as shown in Figure 1, but many other designs of inflatable curtain exist, and an inflatable curtain in accordance with the invention may have many different designs or configurations.

Referring to Figure 3, part of an inflatable curtain 30 is shown. The inflatable curtain 30 is formed from two superimposed layers of fabric 31,32.

The superimposed layers of fabric are interconnected by evenly spaced parallel seams 33,34, 35 which interconnect the two layers of fabric 31,32, so that a plurality of evenly spaced chambers are defined. As can be seen most clearly in Figure 4, the layer of fabric 32 is configured so that the width of the fabric layer 32 between two adjacent seams defining a particular chamber or cell is significantly greater than the width of the other layer of fabric 31 between those two seams defining the cell or chamber. For example, the width of the fabric of the upper fabric layer 32 extending between the seams 33 and 34 is much greater than the width of the fabric layer 31 extending between the seams 33 and 34. The portions of the fabric layer 32 between each pair of adjacent seams is folded so that a central portion 36 of the fabric remains exposed on the exterior of the inflatable curtain, and the fabric forms two re-entrant tucks 37, 38 which extend back underneath this portion of fabric 36.

It is to be appreciated that in manufacturing an inflatable air-bag of the type shown in Figures 3 and 4, the fabric that is to form the upper-most layer 32 may initially be folded to have the various illustrated adjacent substantially parallel re-entrant folds or tucks, and may be hot-ironed or pressed so as to hold the folded configuration with the re-entrant folds or tucks, in the manner of a folded and pressed pleated fabric, thus facilitating a subsequent stitching operation in which the seams 33,34 and 35 are created. Of course, a different technique will be utilised if a one-piece weaving technique is used to create the inflatable curtain.

Turning now to Figure 5, it is to be observed that when an inflatable curtain of the type described with reference to Figures 3 and 4 is inflated, again a plurality of adjacent cells, such as the cells 41 and 42 will be defined, and also

a line of tension may be created due to a general contraction of the width of the lower-most part of the air-bag, but, in contrast with the prior art arrangement as shown in Figure 2 (and here it is to be noted that the configuration of the cells 21 and 22 of Figure 2 are shown in phantom in Figure 5 to facilitate a comparison), the chambers 41 and 42 have a much greater transverse extent than the prior art chambers, especially in the region of a seam 43 between adjacent chambers. Thus, in a situation where a tree 24 impacts one side of the inflatable curtain whilst the head 25 of an occupant impacts the other side, the tree and the head are maintained a substantial distance apart.

Figure 6 and 7 illustrate a modified embodiment of the invention. Many parts of this embodiment correspond directly with parts of the embodiment described with reference to Figures 3 and 4. These parts will be identified with the same reference numerals and will not be re-described in detail. It is to be noted that, in the embodiment, the fabric layer 32 extending between two seams 33 and 34 is folded to present a single re-entrant fold or tuck 44 which is tucked in beneath an exposed upper region 45. Figure 8 again shows that, on deployment of an inflatable curtain as shown in Figure 6 and 7, chambers 51, 52,53, 54 are provided which have a substantial transverse extent, similar to the chambers 41 and 42 as shown in Figure 5.

Whilst the invention has been described above with reference to an inflatable curtain in which two layers of fabric are stitched together to form seams between cells or chambers, it is to be appreciated that the two layers of fabric may be connected by gluing or welding to form a seam. It is to be appreciated that the ratio between the width of the upper layer of fabric between two seams as compared with the width of the lower layer of fabric between two seams may be selected in accordance with the desired properties of the inflatable curtain. The greater the ratio, the greater will be the transverse

thickness of the inflatable element when fully inflated. However, the greater the ratio the less will be the"shrinkage"of the inflatable curtain as it becomes inflated, and thus there will be an increasing difficulty in obtaining an appropriate line of tension, unless some auxiliary tension-creating means are utilised.

Whilst the invention has been described above solely in the context of an inflatable curtain, it is to be appreciated that air-bag arrangements incorporating a plurality of parallel chambers or cells may find other applications, such as in side-bags, knee-bags or even bags which are located beneath the floor covering of the vehicle beneath the feet of the occupant, and corresponding benefits may be obtained by utilising a cell-structure of the type described above, in which each cell is defined between two superimposed layers of fabric between two seams which interconnect those layers of fabric, the width of one layer of fabric between the seams being substantially greater than the width of the other layer of fabric between the seams. Thus the invention relates also to air-bags for use in contexts other than the context of an inflatable curtain.

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 being formed from two superimposed layers of fabric, the layers of fabric being interconnected by a plurality of seams to define a plurality of adjacent cells or chambers, one layer of fabric extending between adjacent seams defining a cell or chamber having a substantially greater width than the other layer of fabric extending between the seams.

2. An air-bag according to Claim 1 in the form of an inflatable curtain.

3. An air-bag according to Claim 1 or 2 wherein the seams are formed by stitching.

4. An air-bag according to Claim 1 or 2 wherein the seams are formed by gluing or welding.

5. A method of manufacturing an air-bag, the method comprising the steps of taking a first layer of fabric and taking a second layer of fabric, folding the first layer of fabric with a plurality of adjacent re-entrant folds or tucks, and securing portions of the first layer of fabric between the re-entrant folds or tucks to the second layer of fabric to form seams, the seams interconnecting the two layers of fabric and forming, together with the layers of fabric, adjacent chambers or cells, the width of the first layer of fabric between two adjacent seams being substantially greater than the width of the second layer of fabric between the two adjacent seams.

6. A method according to Claim 5 wherein the re-entrant folds are hotironed.

7. A method according to Claim 5 or 6 wherein there is one re-entrant fold between each adjacent pair of seams.

8. A method according to Claim 5 or 6 wherein there are two oppositely directed re-entrant folds between two adjacent seams.

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

10. An air-bag substantially as herein described with reference to and as shown in Figures 1,6, 7 and 8 of the accompanying drawings.

11. A method of manufacturing an air-bag substantially as herein described with reference to the accompanying drawings.

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