GB2399058A

GB2399058A - Airbag formed from a single sheet of folded fabric forming first and second superimposed layers

Info

Publication number: GB2399058A
Application number: GB0304922A
Authority: GB
Inventors: Jack Johansson; David Stow; Olivier Bastien
Original assignee: Autoliv Development AB
Current assignee: Autoliv Development AB
Priority date: 2003-03-04
Filing date: 2003-03-04
Publication date: 2004-09-08
Anticipated expiration: 2023-03-04
Also published as: WO2004078534A1; GB0304922D0; GB2399058B

Abstract

An air-bag is provided which is formed from first and second superimposed layers of fabric (7,8). The first layer (7) has a first edge region 4 and a plurality of other edge regions, and said second layer (8) has a second edge region (5) and a plurality of other edge regions. The first layer (7) is connected along its said other edge regions to respective said edge regions of the second layer (8) so as to define respective lines of interconnection (9,10,11) between the two layers (7,8). The first edge region (4) is traversed by a fold line (12) in said first layer (7) which defines a boundary between a pair of superimposed and interconnected parts of said first edge region (4). The second edge region (5) is also traversed by at least one fold line (20) in the second layer of fabric (8) which defines a boundary between a respective pair of superimposed and interconnected parts of said second edge region (5).

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 inflatable air-bag for use in a motor vehicle as a safety device.

It is known to provide motor vehicles with safety devices incorporating one or more inflatable air-bags configured to be inflated in the event of a crash situation. A known type of air-bag arrangement comprises a "frontmounted" air-bag which can, for example, be provided in an initially packed condition inside the housing of a steering wheel or dashboard of the motor vehicle. Air bags of this type are configured to inflate so as to have a significant depth when fully inflated to engage and receive the head and torso of an occupant of the motor vehicle in the event of a crash situation, as the head and torso of the occupant moves forwardly under its inertia. The thickness of the inflated air- bag must be sufficient to prevent the head or torso of the occupant from hitting the structural part of the steering wheel or dashboard as it moves forwardly and is decelerated by the air-bag.

It has therefore been proposed previously to provide air-bags made from superimposed sheets of fabric, sewn together to define a threedimensional shape to be inflated. However, it has been found to be often complicated and expensive to construct three-dimensional air-bags in this manner and it has been found to be more convenient firstly to make a twodimensional bag and subsequently manipulate it into a three-dimensional shape, thereby simplifying the manufacturing process.

It is therefore an object of the present invention to provide an improved air-bag.

According to the present invention, there is provided an air-bag formed from first and second superimposed layers of fabric, said first layer having a first edge region and a plurality of other edge regions, and said second layer having a second edge region and a plurality of other edge regions, the first layer being connected along its said other edge regions to respective said edge IS regions of the second layer, so as to define respective lines of interconnection between the two layers, said first edge region being traversed by a fold line in said first layer which defines a boundary between a pair of superimposed and interconnected parts of said first edge region, and said second edge region also being traversed by at least one fold line in said second layer which defines a boundary between a respective pair of superimposed and interconnected parts of said second edge region.

Preferably, said lines of interconnection all lie in substantially the same plane and wherein said superimposed and interconnected parts of the first edge region lie substantially orthogonal to said plane.

Advantageously, said second edge region is traversed by one fold line in said second layer.

Conveniently, said fold line in said first layer and said one fold line in said second layer are each located substantially centrally along each said respective edge region. s

Advantageously, said superimposed and interconnected parts of said second edge region are aligned with the superimposed and interconnected parts of said first edge region.

Conveniently, said second edge region is traversed by two spaced-apart fold lines in the second layer of fabric.

- Preferably, said two spaced-apart fold lines each define a boundary between a central part of said second edge region located between the fold lines and a respective one of a pair of other parts of the second edge region, each said other part of the second edge region being superimposed and interconnected with a respective portion of said central part.

Preferably, one end part of said second edge region is superimposed and interconnected with the opposite end part of said second edge region.

Advantageously, said interconnected end parts of said second edge region are aligned with said interconnected parts of said first edge region.

Conveniently, the air-bag is formed from a single sheet of fabric folded along a fold line to define said first and second superimposed layers, the fold line defining one of said lines of interconnection.

Preferably, said first and second layers of fabric are both substantially rectangular.

Advantageously, said single sheet of fabric is substantially rectangular and is folded substantially in half such that said fold line extends transversely across the sheet, and said first and second layers are of substantially equal size.

Conveniently, said air-bag is formed from two sheets of fabric, each said sheet forming a respective one of said first and second layers.

Alternatively, said first and second layers of fabric are co-woven and wherein said lines of interconnection are defined by regions where the yarns of said first layer inter-engage with the yarns of said second layer.

So that the invention may be more readily understood, and so that further features thereof may be appreciated, embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: FIGURE 1 is a plan view from above of a single sheet of fabric material I from which an air-bag in accordance with the present invention can be made; FIGURE 2 is a perspective view illustrating the sheet of fabric being folded to define two superimposed layers; FIGURE 3 is a top plan view of the fabric illustrated in Figure 2, showing the two layers of fabric interconnected along opposed side edges; FIGURE 4 is a perspective view of the partially formed air-bag illustrated in Figure 3, viewed from one end, showing the end of the air- bag being sealed; FIGURE 5 is a view corresponding generally to that of Figure 4, but illustrating the opened end of the air-bag being sealed; FIGURE 6 is a top plan view of the completed air-bag; FIGURE 7 is a schematic side view illustrating the air-bag of Figure 6 in position within a motor vehicle, having been inflated in a crash situation; FIGURE 8 is a view corresponding generally to that of Figure 6, but illustrating an alternative intermediate step during the construction of the air- bag; FIGURE 9 is a view corresponding generally to that of Figure 8, illustrating the completed air-bag having an alternative configuration to that illustrated in Figure 6; FIGURE 10 is a side view of an alternative air-bag arrangement; FIGURE 11 is a front view of the air-bag arrangement illustrated in Figure 10; FIGURE 12 is a plan view from above, illustrating an intermediate step during the construction of an alternative configuration of an air-bag in accordance with the present invention; and FIGURE 13 is a perspective view of the completed air-bag illustrated in Figure 12.

Referring initially to Figure 1 of the accompanying drawings, there is illustrated, in plan view, a single sheet of woven fabric material 1 which is used to manufacture an air-bag in accordance with the present invention. The sheet of fabric 1 is rectangular in configuration, having a pair of opposed longitudinal side edges 2, 3 and a pair of opposed first and second end edges 4, 5. At one end of the sheet of fabric 1, there is provided a gas inlet aperture 6 which is formed completely through the fabric and which is substantially equi-spaced from each longitudinal side edge 2, 3. The gas inlet aperture is configured to fit over an inflator when the air-bag is installed in a motor vehicle, as will be described in more detail hereinafter.

Figure 2 illustrates the right-hand end of the sheet 1 as illustrated in Figure 1, having been lifted and turned over so that the second edge region 5 becomes substantially aligned with the first side edge region 4, thereby effectively folding the sheet I in half to define a first, lower layer of fabric 7 which is superimposed with a second, upper layer of fabric 8. The folded sheet of fabric l is pressed flat from the configuration illustrated in Figure 2 so as to define a clear crease or fold line 9 as illustrated in Figure 3.

As will be seen from Figure 3, the two layers of fabric 7, 8 defined by folding the single sheet 1 each have a generally rectangular configuration defined, at one end, by the fold line 9 and at the other end by the respective first and second side edges 4,5.

The superimposed layers of fabric 7,8 are then interconnected with one another along the regions of their superimposed longitudinal edges such as, for example, by seams or lines of stitching 10, 11 as illustrated in Figure 3. It will therefore be understood that in the configuration illustrated in Figure 3, the two I layers of fabric 7, 8 are effectively interconnected along their superimposed longitudinal edges and along the fold line 9. The lines of stitching 10, l l and the fold line 9 therefore each define lines of interconnection between the two layers of fabric 7, 8. The superimposed and interconnected longitudinal edges of the fabric layers 7, 8 and the fold line 9 all lie in substantially the same plane.

Whilst the lines of interconnection between the two layers of fabric 7, 8 along their longitudinal edges are described above as comprising lines of stitching 10, 11, these lines of interconnection could take other forms. For example, the two layers of fabric 7,8 could be co-woven simultaneously such that the yarns of one layer of fabric are inter- engaged with those of the other layer of fabric along the regions of the longitudinal edges and to replace the fold 9 described above. s

Because the two superimposed side edges 4, 5 of the fabric are not, at this stage, interconnected, then the folded fabric illustrated in Figure 3 effectively defines a rectangular pocket which is open at one end.

Figure 4 illustrates a subsequent stage during the manufacture of the airbag in which the central regions of the first and second side edges 4,5 are pulled apart from one another as illustrated by arrows A, in respective directions substantially orthogonal to the plane in which the lines of interconnection represented by the seams 10, 11 and the fold 9 lie. This manipulation of the open end of the pocket defined by the fabric continues until the first edge 4 of the lower layer of fabric 7 is folded in half to define a fold 12 traversing the first edge region 4 and defining a boundary between the two parts of the region 4 located on each side of the fold 12. These two parts of the first edge region 4 thus become superimposed with one another. Similarly, the second edge 5 of the upper layer of fabric 8 is also folded to define two superimposed parts which are aligned with those of the first edge region 4 of the lower layer 7. Effectively, the two ends of the seams 10, 11 located adjacent the open end of the pocket defined in Figure 3 are moved towards one another whereupon the fabric defines a closed air-bag as illustrated in Figure 5.

The two superimposed parts of the first edge region 4 of the lower sheet of fabric 7 are then interconnected with one another via a line of stitching 13 and the two superimposed parts of the second edge regions of the upper layer of fabric 8 are similarly interconnected with one another by another line of stitching 14.

It will therefore be appreciated that the substantially two-dimensional flat pocket of fabric material illustrated in Figure 3 is manipulated and stitched closed so as to define a three-dimensional air-bag having the configuration illustrated in Figure 5 which is closed, apart from its gas inlet aperture 6. As illustrated, the superimposed and interconnected regions of each edge region 4,5 of the fabric are substantially orthogonal to the plane in which the fold 9 and the longitudinal seams 10,11 lie.

The three-dimensional air-bag is illustrated again in Figure 6, viewed from above, and is illustrated from the side in Figure 7, showing the airbag in a deployed condition within a motor vehicle. It will be seen from Figure 7 in particular that a gas generator 15 secured to part of the vehicle's dashboard 16 is received within the gas inlet aperture 6 in a manner known per se. When installed in this way, the inflated air-bag presents a generally triangular shaped "receiving" face 17 which is configured to engage the head 18 and torso 19 of an occupant of a motor vehicle in the event of a crash situation.

Referring now to Figure 8, an alternative configuration of threedimensional air-bag can be created from the pocket of fabric material illustrated in Figure 3. The arrangement illustrated in Figures 8 and 9 is created by again pulling apart the free edges 4, 5 of the layers of fabric 7,8 defining the pocket illustrated in Figure 3, in the directions indicated by arrows A in Figure 4. The first edge 4 of the lower sheet of fabric 7 is again folded in half so that the parts of the edge region 4 located on each side of the resulting fold 12 traversing the edge region become superimposed with one another. The superimposed regions of the first edge region 4 of the lower sheet of fabric 7 are then interconnected with one another via a line of stitching 13 in substantially the same way as described above with reference to the arrangement illustrated in Figures 5 and 6. However, the second edge region 5 of the upper sheet of fabric 8 is manipulated in a slightly different way, instead of being folded in half as was done to achieve the air-bag configuration illustrated in Figure 6.

Figure 8 shows the second edge region 5 of the upper sheet of fabric 8 being folded twice to produce two separate folds 20, 21 traversing the second edge region which are each spaced to a respective side of the centre of the second edge 5. A central part of the second edge region 5 is thus defined between the two folds 20, 21 and a pair of other, spacedapart edge parts 22, 23 are defined on the other side of each respective fold 20, 21. These two spaced apart parts 22, 23 are, as illustrated in Figure 8, superimposed with respective portions of the central part, and interconnected with said respective portions of the central part of the second edge region 5 by lines of stitching. The two end parts 24, 25 of the second edge region 5 are also superimposed and interconnected by a line of stitching so as to be aligned with the interconnected halves of the first edge region 4. This manipulation of the edge 4 creates a generally "T"-shaped seam at the top of the resulting air-bag as shown in Figure 9.

The effect of providing this T-shaped seam at the top of the air-bag is that the upper region of the receiving face 17 is made to be wider than the rather more pointed top region of the receiving face of the arrangement illustrated in Figure 6. This is illustrated most clearly in Figure 11 which is a view of the receiving face 17 from the front. The other effect of folding the second edge region 5 of the upper sheet of fabric 8 twice to create the T-shaped seam illustrated in Figure 9 is that the top region of the receiving face 17 moves closer to the apex of the air-bag defined by the fold 12 which traverses the first edge region 4 of the lower sheet of fabric 7. This is illustrated, for example, in Figure 10. When such an arrangement is inflated within a motor vehicle, the upper region of the receiving face 17 is thus located further away from the vehicle occupant than the lower region of the receiving face 17. This type of arrangement can therefore be configured so that the top, wider, part of the receiving face 17 will be engaged by the head 18 of the occupant in a front impact crash situation, whilst the lower part of the receiving face 17 which is located closer to the occupant, is engaged by the part ofthe occupant's torso l9.

Because the upper part of the receiving face 17 is located further away from the occupant than the lower part, it allows the occupant's head to move slightly; further forwards than the torso 19 as the occupant gauges and is cushioned by the inflated air-bag. This therefore reduces the tendency of the air-bag to cause the occupant's head 18 to be rolled backwardly relative to the occupant's torso i 19 which can cause serious neck injury to the occupant.

Each of the above-described air-bags require a small vent-hole to be provided through the fabric of the air-bag. This is to allow the gas used to inflate the air-bag to vent out of the air-bag as the passenger's head and torso engage the air-bag. Allowing the gas to flow through the venthole in this way ensures that the air-bag properly absorbs energy from the forwardly-moving passenger. If no vent-hole were provided, then the passenger's head and torso would not be properly cushioned by the air-bag and instead, would tend to bounce-back away from the inflated air-bag after initially engaging the air-bag which can clearly cause significant injury. However, an alternative arrangement is illustrated in Figures 12 and 13 in which no vent-hole is required.

Referring now to Figure 12, there is illustrated a sheet of fabric material in a folded condition so as to define a pair of superimposed fabric layers 7, 8 which are interconnected with one another via a fold line 9. In this arrangement, the two layers of fabric 7, 8 each have a substantially identical trapezoidal shape such that their respective longitudinal edges diverge as they move away from the fold line 9 towards the end edges 4, 5 of each layer 7, 8.

Each said longitudinal edge of one of the layers 7, 8 is superimposed upon a respective longitudinal edge of the other layer and each pair of superimposed S edge regions are interconnected by a respective seam 10, 11 in the form of a line of stitching.

In regions adjacent the seams 10, 11 and the fold line 9, the two layers of fabric 7, 8 are also interconnected via a plurality of stitches 26 having a relatively weak tensile strength when compared to the strength of the warp and weft yarns of each layer of fabric 7, 8. The plurality of stitches 26 thus define an interconnected zone between the two layers of fabric 7, 8 which is shaped to define a rectangular pocket between the two layers 7, 8 which is open at its end defined by the edges 4, 5 of the two layers of fabric 7, 8.

The pocket illustrated in Figure 12 is then manipulated in substantially the same way as described above in connection with the manipulation of the pocket illustrated in Figure 3 so as to form a three-dimensional air- bag as illustrated in Figure 13. Because of the interconnected zones of the two layers of fabric 7,8 defined by the plurality of stitches 26, the resulting air-bag, whilst having a configuration largely similar to that of the above-described arrangement illustrated in Figures S and 6, has a number of regions 27, 28, 29 where the two layers of fabric are interconnected by the plurality of stitches 26.

Because of the relative mechanical weakness of the stitches 26, these zones 27, 28, 29 of the resulting air-bag define "tear-seams" on the outside of an internal chamber 30 of the air-bag.

During inflation of the air-bag, gas is supplied through the gas inlet aperture 6 into the chamber 30 of the air-bag so as to inflate the airbag. The plurality of stitches 26 have a strength sufficient to remain intact as the predetermined inflating volume of gas is injected into the chamber 30.

However, as the head and torso of a passenger engage the air-bag in a crash situation, the effect is that the inflated air-bag is deformed, thereby reducing its volume and increasing its internal gas pressure. The plurality of stitches 26 are configured to break in such a situation so that as the head and torso of the passenger engage the air-bag and deform it under their inertia, the tear-seams 27, 28, 29 tear apart so that the two layers of fabric initially interconnected by those seams become free to move apart from one another. As will be seen from Figure 13, because of the configuration of the tear- seams 27, 28, 29 on the outside of the inner chamber 30, tearing these seams apart increases the effective volume of the air-bag, thereby allowing the head and torso of the passenger to be properly cushioned by the air-bag, without causing the head and torso to bounce-back away from the air-bag.

In the present specification "comprises" 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 formed from first and second superimposed layers of

fabric, said first layer having a first edge region and a plurality of other edge regions, and said second layer having a second edge region and a plurality of other edge regions, the first layer being connected along its said other edge regions to respective said edge regions of the second layer, so as to define respective lines of interconnection between the two layers, said first edge region being traversed by a fold line in said first layer which defines a boundary between a pair of superimposed and interconnected parts of said first edge region, and said second edge region also being traversed by at least one fold line in said second layer which defines a boundary between a respective pair of superimposed and interconnected parts of said second edge region.
2. An air-bag according to claim 1, wherein said lines of interconnection all lie in substantially the same plane and wherein said superimposed and interconnected parts of the first edge region lie substantially orthogonal to said plane.
3. An air-bag according to any preceding claim, wherein said second edge region is traversed by one fold line in said second layer.
4. An air-bag according to claim 3, wherein said fold line in said first layer and said one fold line in said second layer are each located substantially centrally along each said respective edge region.
5. An air-bag according to claim 3 or claim 4, wherein said superimposed and interconnected parts of said second edge region are aligned with the superimposed and interconnected parts of said first edge region.
6. An air-bag according to claim 1 or 2, wherein said second edge region is traversed by two spaced-apart fold lines in the second layer of fabric.
7. An air-bag according to claim 6, wherein said two spaced-apart fold lines each define a boundary between a central part of said second edge region located between the fold lines and a respective one of a pair of other parts of the second edge region, each said other part of the second edge region being I superimposed and interconnected with a respective portion of said central part.
8. An air-bag according to claim 7, wherein one end part of said second edge region is superimposed and interconnected with the opposite end part of said second edge region.
9. An air-bag according to claim 8 wherein said interconnected end parts of said further edge region are aligned with said interconnected parts of said first edge region.
10. An air-bag according to any preceding claim formed from a single sheet of fabric folded along a fold line to define said first and second superimposed layers, the fold line defining one of said lines of interconnection.
ll. An air-bag according to any preceding claim, wherein said first and second layers of fabric are both substantially rectangular.
12. An air-bag according to claim 11 as dependent upon claim 10, wherein said single sheet of fabric is substantially rectangular and is folded substantially in half such that said fold line extends transversely across the sheet, and said first and second layers are of substantially equal size.
13. An air-bag according to any one of claims l to 9, formed from two sheets of fabric, each said sheet forming a respective one of said first and second layers.

lO
14. An air-bag according to any one of claims l to 9, wherein said first and second layers of fabric are co-woven and wherein said lines of interconnection I are defined by regions where the yarns of said first layer inter-engage with the yarns of said second layer.
15. An air-bag substantially as hereinbefore described with reference to and as shown in the accompanying representations.
16. Any novel feature or combination of features disclosed herein.