GB2417929A

GB2417929A - Three-dimensional air-bag

Info

Publication number: GB2417929A
Application number: GB0420153A
Authority: GB
Inventors: Remi Baillivet; Adam Machnik
Original assignee: Autoliv Development AB
Current assignee: Autoliv Development AB
Priority date: 2004-09-10
Filing date: 2004-09-10
Publication date: 2006-03-15
Anticipated expiration: 2024-09-10
Also published as: WO2006041345A1; GB2417929B; GB0420153D0

Abstract

An air-bag (1) is of elongate substantially symmetrical rectangular form. The air-bag presents a central inflatable region (5) which has a central aperture (4) in one of the two identical superimposed layers that forms the air-bag for connection to a gas generator. Each end of the rectangular air-bag is provided with an inflatable chamber (6) which is connected to the central inflatable region by means of gas flow paths (8). The two end walls of the terminal inflatable chambers (6) which are remote from the central inflatable region (5) are secured together so that the two terminal chambers (6) form an integral cushion. The air-bag may be mounted on a steering-wheel of a vehicle and although the air-bag is formed from two superimposed identical sheets of fabric the air-bag has a thee-dimensional form when inflated (see figure 2).

Description

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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 for use in a motor vehicle to provide protection for an occupant of the vehicle in the event that an accident should occur. The preferred embodiment of the present invention is in the form of an air-bag to be incorporated in a steering-wheel to provide protection for the driver of the vehicle. However, the invention may also be applied to other types of air-bag.

It is known that, for an air-bag to provide optimum protection for the occupant of the vehicle, such as the driver of the vehicle, the air-bag should engage with, or couple with, the occupant of the vehicle as soon as possible after an accident situation has been detected. It has been proposed to provide an air-bag which provides such rapid coupling, the air-bag being formed in a three-dimensional manner. Thus the air-bag is not formed simply using two identically shaped super-imposed layers of fabric which are interconnected by seams, but instead utilises separate layers of fabric of non-identical shape which are assembled together to form an air-bag having the desired configuration.

However, such air-bags are relatively expensive to manufacture as they require a substantial quantity of fabric and relatively complicated sewing techniques.

In contrast a typical driver's air-bag is formed from two super-imposed sheets of material, typically of circular form with a peripheral seam. Gas is injected into the air-bag from an aperture provided at the centre of one of the sheets. The air-bag, when inflated, may present the form of a relatively flat circular cushion or may present the form of a spherical ball, depending upon the presence of any internal restraining straps and upon the pressure of gas supplied. Such an air-bag does not provide optimal early coupling with a driver, but, on the other hand, an air-bag of this type is relatively economic to produce.

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

According to this invention there is provided an air-bag, the air-bag being of elongate substantially symmetrical form and having a central inflatable region with a substantially central aperture for connection to a gas generator, each end of the air-bag being provided with an inflatable chamber which is connected to the central inflatable region of the air-bag by means of one or more gas flow paths, the end walls of the two terminal inflatable chambers remote from the central inflatable region being secured together so that the two terminal chambers form a cushion.

Preferably the air-bag is formed from two superimposed layers of fabric of substantially identical shape.

Conveniently the gas flow paths are formed as spaces between aligned seams.

Advantageously the air-bag is of rectangular form, and is provided with a cut-out in one side of the rectangle substantially aligned with the aperture provided to receive the gas generator.

Preferably each inflatable chamber is provided with a gas vent.

Conveniently each vent is directed away from an exposed face of the cushion.

Advantageously each inflatable chamber is provided with a seam forming an un-inflatable region substantially in alignment with a mid part of the end wall of the chamber which is remote from the central inflatable region, the said seams being abutted when the chambers are secured together to form the cushion, the seams forming a substantially central un-inflatable region of the 1 5 cushion.

Preferably the said seams forming the uninflatable region are each of rectangular form.

Conveniently one or more of the seams are tear-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 air-bag in accordance with the invention in an un-inflated state, and FIGRUE 2 is a view illustrating the air-bag of Figure 1 when inflated.

Referring initially to Figure 1 of the accompanying drawings, an air-bag in accordance with the present invention is formed from two super-imposed layers of fabric which are interconnected by means of appropriate seams. The seams may be stitched seams or both of the layers of fabric may be produced simultaneously, with the seams being produced by a one-pieceweaving technique. Some of the seams may be "tear" seams, that is to say seams which are intended to break when the gas pressure within the airbag reaches a predetermined threshold.

Although the air-bag is made using only two layers of fabric, because of the form of the air-bag, the air-bag, on inflation, presents a threedimensional shape, and part of the air-bag may be moved swiftly into engagement with the vehicle occupant to be protected by the air-bag.

Referring, in detail, to Figure 1, the air-bag 1 is formed from two superimposed layers of fabric of identical shape.

The air-bag 1 is of generally rectangular shape, being formed from two superimposed rectangular layers of fabric. The air-bag 1 is substantially symmetrical about a central axis 2, which intersects the long sides of the rectangle.

The lower-most edge of the rectangular air-bag, in the orientation illustrated, is provided with an arcuate or substantially triangular "cutout" 3, the centre of the cut-out being aligned with the said axis 2.

One sheet of fabric, just above the cut-out 3, in alignment with the axis 2, is provided with an opening 4, dimensioned to accommodate a gas generator. The aperture is shown, in Figure 1, as being square, but the aperture may have any appropriate shape or size. The gas generator will be provided to inject gas into the air-bag.

To each side of the axis 2, there is a relatively large inflatable region 5 defined within the air-bag. The region 5 is separated from two terminal inflatable chambers 6, which are located one at each end of the rectangular air- bag, by aligned seams 7, which may be tear-seams. The aligned seams are a plurality of seams, aligned on a common line, but separated from each other.

The aligned seams 7 serve to separate the terminal chamber 6 from the main central inflatable region 5 of the air-bag, and also define gas flow paths as indicated by the arrows 8 which connect the inflatable region 5 to each chamber 6. Each chamber 6 is provided, in one of the two layers of fabric, with an exhaust vent 9. Each chamber 6 is provided, in the central region of the end wall of the rectangular air-bag which is remote from the central space 5 with a rectangular seam 10.

The air-bag may be mounted in position, for example on a steering- wheel 11, with a gas generator mounted on the steering-wheel being connected to the air-bag by the aperture 4. The two end walls of the rectangular air-bag, that is to say the end walls that are associated with the rectangular seams 10, are sewn together, so that the rectangular seams 10 abut each other.

The air-bag, in this state, may be considered to be of triangular form, with the inflatable region on either side of the axis of symmetry 2 forming two sides of the triangle, and third side of the triangle being formed by the two parts

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of the air-bag which define the chambers 6. The vents 9 provided on the air bag will open towards the interior of the triangle rather than the exterior of the triangle.

On deployment of the air-bag gas from the gas generator flows through the aperture 4 into the inflatable regions 5 to either side of the line of symmetry 2. The regions 5 thus inflate to form substantially rigid "arms" 12 which extend generally forwardly from the steering-wheel 11, with the arms 12 diverging slightly. The forward-most ends of the arms 12 are interconnected by the parts of the air-bag which form the inflatable chambers 6.

During deployment of the air-bag gas will flow from the inflatable regions 5 through the gas flow paths 8 into the inflatable chambers 6. The rate of inflation of the inflatable chamber 6 is thus determined by the sizes of the flow paths 8 which, in turn, is determined by the sizes of, and the spacing between, the aligned seams 7. Thus, by selecting an appropriate size for each of the aligned seams 7, and by selecting the spacing between the seams, a desired inflation characteristic can be achieved for the air-bag.

As the chambers 6 inflate, to form a substantially rectangular "cushion" 13 which is aligned with the chest of the driver of the vehicle, the central square or rectangular region constituted by the two seams 10 remains un-inflated, and, of course, there is a line 14 of non-inflation where the two chambers 6 are sewn together. The cushion presents a face which is directed towards the occupant to be protected by the air-bag, the face thus being directed away from the arms 12 and the steering-wheel 11. Thus the cushion 13 provides a relatively strong cushioning effect to either side of the centre line 14, and has an un-inflated central area formed by the seams 10. This may help minimise injury and undesirable chest compression which can be caused if the restraining cushion is provided with a large volume at a central point.

It is to be understood that the seams 7 and the seams 10 may be tear seams. Thus, should pressure within the air-bag rise above a predetermined limit, the seams will tear. Such tearing of the seams 7 will increase the size of the gas flow paths extending from the inflatable region 5 to each of the chambers 6. Tearing of the seams 10 will enable the central part of the cushion 13 to become inflated.

The arcuate cut-out 3 has been found to improve the stability of the airbag during inflation. The stability of the air-bag may also be improved in other ways, for example by providing stabilising seams joining the two layers of fabric that form the air-bag in the region of the gas generator, or by providing cut-out holes in one or preferably both of the layers of fabric.

Because the vents 9 are open towards the "interior" of the triangular airbag, hot gases generated by the gas generator which are vented from the air-bag are directed away from the face of the cushion and thus away from the occupant being protected by the air-bag.

When used in this Specification and Claims, the terms "comprises" and "comprising" and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or components.

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 fonns thereof.

Claims

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CLAIMS: 1. An air-bag, the air-bag being of elongate substantially symmetrical form and having a central inflatable region with a substantially central aperture for connection to a gas generator, each end of the air-bag being provided with an inflatable chamber which is connected to the central inflatable region of the air bag by means of one or more gas flow paths, the end walls of the two terminal inflatable chambers remote from the central inflatable region being secured together so that the two terminal chambers form a cushion.
2. An air-bag according to Claim 1 wherein the air-bag is formed from two superimposed layers of fabric of substantially identical shape.
3. An air-bag according to Claim 1 or Claim 2 wherein the gas flow paths are formed as spaces between aligned seams.
4. An air-bag according to any one of the preceding Claims wherein the air-bag is of rectangular form, and is provided with a cut-out in one side of the rectangle substantially aligned with the aperture provided to receive the gas generator.
5. An air-bag according to any one of the preceding Claims wherein each inflatable chamber is provided with a gas vent.
6. An air-bag according to Claim 5 wherein each vent is directed away from an exposed face of the cushion.
7. An air-bag according to any one of the preceding Claims wherein each inflatable chamber is provided with a seam forming an un-inflatable region substantially in alignment with a mid part of the end wall of the chamber which is remote from the central inflatable region, the said seams being abutted when the chambers are secured together to form the cushion, the seams forming a substantially central un-inflatable region of the cushion.
8. An air-bag according to Claim 7 wherein the said seams forming the inflatable region are each of rectangular form.
9. An air-bag according to Claim 2 or Claim 6 or any Claim dependent thereon wherein one or more of the seams are tear-seams.
10. An air-bag substantially as herein described with reference to and as shown in the accompanying drawings.
11. Any novel feature or combination of features disclosed herein.