WO2004083006A1

WO2004083006A1 - An air-bag arrangement

Info

Publication number: WO2004083006A1
Application number: PCT/SE2004/000042
Authority: WO
Inventors: Gilles Garret; Frédéric CHARPENTIER
Original assignee: Autoliv Development Ab
Priority date: 2003-03-20
Filing date: 2004-01-16
Publication date: 2004-09-30
Also published as: GB2399548A; GB0306451D0; GB2399548B

Abstract

An air-bag arrangement is disclosed which comprises an air-bag (2) having a pair of superimposed layers of fabric. A gas-generator (25) is provided having a gas-deflector (31). The air-bag (2) defines a neck (22) formed between the two layers for fluid communication between the gas-generator (25) and an inflatable chamber defined between the two layers of the air-bag. The gas-deflector (31) extends at least partially across the neck (22) and has a notional axis which also extends across the neck (22), between the two layers defining the air-bag. The gas-deflector (31) has at least one flap which is pivotally moveable about a respective hinge axis, the or each hinge axis being transverse to the notional axis along which the gas-deflector (31) extends. The or each flap is initially located in a closed position but is configured to pivot about its hinge axis upon actuation of the gas-generator (25) so as to open towards the chamber of the air-bag (2) extending at least partly into the neck (22).

Description

"AN AIR-BAG ARRANGEMENT"

THIS INVENTION relates to an air-bag arrangement and more particularly relates to an air-bag arrangement for use in a motor vehicle to protect occupants of a vehicle in the event that an accident should arise.

It has been proposed to provide many types of air-bag in a motor vehicle to protect the occupants of the vehicle in the event that an accident should arise.

In recent years, it has become common to provide a specific type of air- bag, known as "an inflatable curtain" which is mounted in a motor vehicle to provide protection for the occupants of a vehicle in the event that a side impact or roll-over should occur. Such an inflatable curtain is an air-bag which typically is initially stored within the roof lining of a motor vehicle immediately above the door openings. The air-bag inflates, in response to a signal from an appropriate sensor, to form a "curtain" lying adjacent a side-window of the vehicle. Frequently, an air-bag of this type comprises two discrete chambers for inflation, one chamber being configured to lie adjacent to the front side- window of the vehicle, and the other chamber being configured to lie adjacent the rear side-window of the vehicle upon inflation of the air-bag. In order to use a single inflator or gas generator to inflate both discrete chambers of the air-bag, it is convenient to arrange the inflator or gas generator in the region of the "B-pillar" of a motor vehicle structure, i.e. the pillar extending vertically upwardly between the front and rear side-windows of the vehicle.

A typical inflatable curtain air-bag is provided with one or two mounting straps connected to the lower parts of the air-bag and positioned to extend forwardly and/or rearwardly to anchoring points in the vehicle. This arrangement is such that as the air-bag becomes inflated, a line of tension is created across the lower part of the air-bag, and which extends through the straps to the anchoring points so that the inflated air-bag is held substantially rigidly in position to provide the desired degree of protection.

Because an inflatable curtain-type air-bag must be inflated very rapidly if it is to be of value in a side impact situation, the gas generator must produce a very large volume of gas in a short period of time. The resultant flow of gas is therefore very aggressive and can damage the inflatable curtain if not carefully directed into the interior of the inflatable curtain.

WO 02/079008 Al discloses a "centre-filled" inflatable curtain where a gas generator is provided in the region of the B-pillar of a motor vehicle. In the arrangement of this document, the gas generator is elongate and is secured to the structure of a motor vehicle by a bracket arranged at one end of the gas generator. The other end of the gas generator extends into a gas-inlet portion of the air-bag and an inner bag is arranged over that part of the gas generator, within the inflatable curtain, so as to protect the delicate regions of the inflatable curtain around the gas inlet region from damage by gas flow generated by the gas generator. However, it has been found that this inner-bag arrangement can be inconvenient to assemble due to the need for the inner-bag to be carefully and properly arranged within the inflatable curtain. The arrangement of this prior art document also suffers from another disadvantage resulting from the manner in which the elongate gas generator is mounted to the structure of the motor vehicle only at one end of the gas generator. When the gas generator is actuated so as to produce a gas-flow through the opposite end of the gas generator, a significant moment force can result. Because the elongate gas generator is secured to the motor vehicle structure only at one end, this method of attachment can be insufficient to withstand the high momentum force generated.

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

Accordingly, the present invention provides an air-bag arrangement comprising: an air-bag having a pair of superimposed layers, a gas generator to inflate the air-bag, and a gas generator with a gas-deflector; the air-bag defining a neck formed between said layers for fluid communication between the gas- generator and an inflatable chamber defined between the layers; wherein the gas-deflector extends at least partially across the neck and has a notional axis extending across the neck between said layers; the gas-deflector having at least one flap pivotally moveable about a respective hinge axis, the or each hinge axis being transverse to said notional axis, and the or each said flap being initially located in a closed position but being configured to pivot about said hinge axis upon actuation of the gas-generator so as to open towards said chamber, extending at least partly into the neck.

Preferably, the or each flap is integral with a body-part of the deflector and wherein the or each respective said hinge axis is defined by a deformable web interconnecting the body-part and the respective flap. Advantageously, the or each said flap is each defined by a respective substantially C-shaped slot provided through part of the gas-deflector.

Conveniently, the or each said slot is substantially arcuate.

Advantageously, the air-bag comprises a pair of said flaps, wherein the hinge axis of one said flap is substantially parallel to the hinge axis of the other said flap, and said flaps are initially located between said hinge axes.

Preferably, said flaps are spaced from one another so as to define a region of the gas-deflector between the two flaps, said region of the gas- deflector being deformable and configured to deform upon actuation of the gas- generator so as to open towards at least one of said respective layers.

Advantageously, a slot is provided through said deformable region of the gas-deflector between the two flaps, said slot extending from the substantially C-shaped slot of one flap to the substantially C-shaped slot of the other flap to divide the deformable region of the gas-deflector into a pair of deformable parts.

Conveniently, said deformable parts are each configured to deform about a respective axis oriented so as to be substantially perpendicular to said hinge axes.

Preferably, the gas-deflector is of plastics material.

Advantageously, the gas-deflector is of metal. Conveniently, the gas-deflector is elongate and said hinge axes lie substantially perpendicular to the longitudinal axis of the gas-deflector.

Preferably, the gas-deflector has a uniform substantially arcuate cross- section.

Advantageously, the gas-deflector is elongate and the gas-deflector is substantially cylindrical, the gas-generator being located within the gas- deflector.

Conveniently, the gas-deflector is engaged with the gas-generator as an interference fit.

Preferably, said air-bag defines a gas-inlet portion and said gas-generator is located within said gas-inlet portion, the gas-inlet portion of the air-bag being secured to the gas-generator by a pair of clamps, the clamps being spaced from one another along the length of the gas-generator.

Advantageously, said gas-inlet portion of the air-bag is substantially T- shaped and defines a pair of opposed inlet ducts in communication with said neck, each said clamp being provided around a respective said inlet duct so as to clamp the inlet ducts to the gas-generator.

Conveniently, said gas-inlet portion of the air-bag is substantially L- shaped and defines a single inlet duct in communication with said neck, one of said clamps being provided around said inlet duct so as to clamp the inlet duct to the gas-generator, the other clamp passing through an aperture provided in the gas-inlet portion of the air-bag to clamp the air-bag to the gas-generator. Preferably, the gas-deflector is located between said clamps.

Advantageously, each said clamp is configured for securement to part of the structure of a motor vehicle.

Conveniently, the air-bag arrangement comprises first and second gas- deflectors, wherein said gas-deflector having at least one flap defines the first gas-deflector, the second gas-deflector initially being provided around at least part of the first gas-deflector in a folded configuration such that at least part of the second gas-deflector extends over the or each flap of the first gas-deflector, the second gas-deflector being configured to unfold so as to extend at least partly into the neck as the or each said flap opens upon actuation of the gas- generator.

Preferably, said second gas-deflector takes the form of a sleeve engaged over said first gas-deflector.

Advantageously, said second gas deflector is of fabric.

Alternatively, said second gas-deflector is of metal.

So that the invention may be more readily understood, and so that further features thereof may be appreciated, embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:

FIGURE 1 is a schematic side-view of an air-bag arrangement generally in accordance with the present invention; FIGURE 2 is an enlarged side-view of part of the arrangement illustrated in Figure 1, showing a gas-generator secured within a gas inlet portion of the air-bag

FIGURE 3 is a view corresponding generally to that of Figure 2, but illustrating an alternative configuration of the gas inlet portion;

FIGURE 4 is a perspective view from below of a gas-deflector provided as part of the present invention, illustrating the gas-deflector in an initial condition prior to actuation of the gas-generator;

FIGURE 5 is a perspective view from above of the gas-deflector illustrated in Figure 4, illustrating the gas-deflector in an alternate condition after actuation of the gas-generator;

FIGURE 6 is a schematic side-view of an alternative configuration of an inflatable curtain in accordance with the present invention;

FIGURE 7 is a schematic side-view of part of another alternative configuration of the air-bag of the present invention;

FIGURE 8 is a sectional view taken long line A-A of Figure 7; and

FIGURE 9 is a view corresponding generally to that of Figure 7, illustrating the arrangement in an alternate condition after actuation of the gas- generator. Referring initially to Figure 1, there is illustrated an air-bag arrangement in the form of an inflatable curtain, illustrated in its deployed condition. The air-bag arrangement comprises an inflatable air-bag 2 which is secured along its uppermost peripheral edge 3, via a plurality of mounting lugs 4, to the roof structure 5 of a motor vehicle.

The air-bag 2 comprises an inflatable curtain having two discrete inflatable chambers 6, 7. In the arrangement illustrated in Figure 1, the right- hand chamber 6 is configured for inflation so as to lie adjacent the front-side- window 8 of the vehicle, whilst the left-hand chamber 7 is configured for inflation to lie adjacent the rear-side-window 9 of the vehicle. The two discrete chambers 6, 7 are interconnected by a flow passage 10 located substantially adjacent the uppermost edge 3 of the inflatable air-bag 2.

In a manner known per se, the air-bag 2 is formed from two superimposed layers of fabric, which may be a single folded sheet, or two sheets which are interconnected by seams which may be stitched or formed by using a one-piece weaving technique in which two sheets of fabric are woven simultaneously, the sheets of fabric, in selected regions, being co-woven to form, in those selected regions, a single sheet of fabric. It will therefore be appreciated that each discrete chamber 6, 7 is defined between said two layers of fabric.

As illustrated in Figure 1, the interior volume of each discrete chamber 6, 7 is further sub-divided into a plurality of inflatable cells or zones 11. The zones 11 may, for example, be defined by lines 12 of stitching between the two layers of fabric forming the inflatable air-bag 2. Alternatively, the inflatable zones 11 could be defined by co-woven regions of the fabric by the one-piece weaving technique mentioned above. The air-bag 2 is provided with a pair of mounting straps 13, 14. The front mounting strap 13 is secured to the forwardmost edge 15 of the air-bag 2 and extends forwardly to an anchoring point 16 at which the mounting strap 13 is secured to the A-pillar 17 of the motor vehicle. In a similar way, the rear mounting strap 14 is secured to the rearmost edge 18 of the air-bag 2 and extends rearwardly to terminate at an anchoring point 19 at which the rear mounting strap 14 is secured to the C-pillar 20 of the motor vehicle. Of course, as indicated above, the air-bag arrangement is illustrated in Figure 1 in a deployed condition in which the inflatable air-bag 2 has been inflated. Prior to inflation, the air-bag 2 is folded, rolled or otherwise packed within a cavity provided in the roof structure 5 of the motor vehicle, and the two mounting straps 14,15 are held within the A-pillar 17 and the C-pillar 20 respectively of the motor vehicle.

At a substantially central point along the uppermost edge 3 of the air-bag 2, adjacent the point at which the B-pillar 21 of the motor vehicle joins the roof structure 5, the inflatable air-bag 2 is provided with a neck 22 defined between the two layers of fabric of the air-bag. The neck 22 is bounded on each side by a seam, and opens into a generally T-shaped gas-inlet portion 23 of the air-bag 2. The gas inlet portion 23 defines a pair of opposed inlet ducts 24 each of which is in fluid communication with the neck 22. The gas inlet portion 23 is located above the gas-inlet portion 23. The lower part of the gas-inlet portion 23 is in fluid communication with the two chambers 6,7.

As illustrated most clearly in Figure 2, an elongate cylindrical inflator 25 in the form of a gas-generator is provided within the gas inlet portion 23 of the air-bag 2 such that opposed ends of the gas-generator 25 are received through respective inlet ducts 24. The gas-generator 25 has a plurality of gas outlet apertures 26 substantially centrally along the length of the gas-generator 25 so as to be located above the neck 22 of the air-bag 2.

The gas-generator 25 is secured within the inlet portion 23 of the air-bag 2 by a pair of clamps 27 which are spaced apart from one another on either side of the neck 22 in the region of respective inlet ducts 24. Each clamp 27 circles a respective inlet duct 24 and clampingly secures the fabric of the respective inlet duct 24 against the gas-generator 25 extending therethrough. The clamps 27 preferably take the form of circular collars configured such that the diameter of the collars can be reduced so as to clamp the collars over the inlet ducts 24.

As illustrated schematically in Figure 2, each clamp 27 is provided with a respective mounting formation 28 which is configured for attachment by any convenient means (such as, for example, by a conventional nut and bolt arrangement) to the roof structure 5 of the motor vehicle in the region of the B- pillar 21.

Turning briefly to consider Figure 3, an alternative configuration of the gas inlet portion 23 of the air-bag 2 is illustrated. In this configuration, the gas inlet portion 23 is generally L-shaped rather than T-shaped, as it has a single inlet duct 24 arranged for fluid communication with the neck 22. At a position opposite from the single inlet duct 24, the gas inlet portion 23 is closed, but is provided with a seam or co-woven region between the two sheets of fabric of the air-bag, defining an aperture 29 formed completely through the air-bag 2.

The elongate gas-generator 25 is inserted through the inlet duct 24 so as to lie within the gas inlet portion 23 such that the forwardmost end 30 of the gas-generator 25 lies above and substantially adjacent the aperture 29 formed through the air-bag 2. In this position, it will be seen that the rearmost end of the gas-generator is located largely within the inlet duct 24 in the same way as in the arrangement illustrated in Figure 2. The rearmost end of the gas- generator 25 is secured to the inlet portion 23 by its associated clamp 27 in exactly the same manner as described above with reference to the arrangement in Figure 2. However, at its forwardmost end, the gas-generator 30 is secured to the gas inlet portion 23 by arranging the forward clamp 27 so as to extend over and around the regions of the air-bag fabric lying adjacent the gas- generator 30, but so as to pass through the aperture 29.

As illustrated schematically in both Figures 2 and 3, an elongate gas- deflector 31 is provided which extends across the neck 22 of the air-bag 2. As will be seen from Figures 4 and 5, the gas-deflector 31 is tubular and is mounted over and around the gas-generator 25 so as to lie between the gas outlet apertures 26 and the neck 22 of the air-bag 2. As illustrated most clearly in Figure 2, the gas-deflector 31 is positioned between the two layers of fabric defining the gas-inlet portion 23 of the air-bag. The longitudinal axis 31a of gas-deflector 31 (the axis 31a being shown in phantom in Figure 2) thus extends between the two layers of fabric of the air-bag. The gas-deflector thus defines a notional axis extending between the two layers of fabric and passing across the top of the neck 22.

The gas-deflector 31 is preferably sized and configured so as to be a push-fit or interference fit over the gas-generator 30, such that the gas-deflector 31 can simply and easily be mounted on the gas-generator 25 so as to remain in the position illustrated. However, it should be appreciated that in variants of the invention, the gas-deflector 31 may not be a push-fit or an interference fit, and could instead be held in position relative to the gas-generator 25 by some other convenient means. As illustrated most clearly in Figure 4, which is a perspective view from below, the gas-deflector 31 is elongate and cylindrical and has a generally uniform circular cross-section. The gas-deflector 31 may be moulded or extruded from plastics material or could be made from metal material either by rolling a sheet of metal into the cylindrical configuration illustrated, or by extrusion.

The underside of the gas-deflector 31 (illustrated on top in Figure 4) is provided with a pair of generally arcuate C-shaped slots 32 therethrough. The two C-shaped slots 32 are arranged with respect to one another so as to be "back-to-back" such that the two ends 33 of one slot are spaced from the two ends 33 of the other slot by a distance greater than the spacing between arcuate regions of the slots 32.

At each end 33 of the arcuate C-shaped slots 32, there is provided a short terminal slot 34 which is substantially linear and arranged to be perpendicular to the respective end parts of the C-shaped slots 32, and parallel to the longitudinal axis of the gas-deflector. Adjoining the C-shaped slots 32 is a longitudinal central slot 35 which also lies substantially parallel with the longitudinal axis of the gas-deflector 31.

It will be seen from Figure 4 that a web 36 is defined between the two terminal slots 34 carried at the ends of each C-shaped slot 32. Each web 36 is plastically deformable and, as will become clear, defines a respective hinge axis 36a (illustrated in phantom in Figure 4) extending between the two ends 33 of each C-shaped slot 32. The hinge axes thus lie substantially transverse to the longitudinal axis 3 la of the gas-deflector 31. Two C-shaped slots 32 each define a respective flap 37, the flaps 37 being pivotable, through plastic deformation of the webs 36, about the hinge axes 36a. Figure 4 illustrates, from below, the gas-deflector 31, in its initial configuration prior to actuation of the gas-generator 25 extending through the gas-deflector 31. In this initial configuration, the two flaps 37 are closed as also illustrated schematically in Figures 2 and 3.

Between the two flaps 37 a pair of deformable fingers 38 are defined which are separated by one another by the central slot 35.

As illustrated schematically in Figures 2 and 3, actuation of the gas- generator 25 causes gas to be expelled, at high velocity and pressure, through the gas outlet apertures 26 as illustrated by the arrows in Figures 2 and 3. Because the gas-deflector 31 is arranged between the gas outlet apertures 26 and the neck 22 of the air-bag 2, the significant gas pressure resulting from actuation of the gas-generator acts on the flaps 37 and urges the flaps 37 downwardly, into the neck region 22 of the air-bag 2, so that the two flaps 37 pivot around the hinge axes defined by the webs 36, hence allowing the flaps 37 move to a position as illustrated in Figure 5 in which they extend partly into the neck, thereby opening up a flow passage through the gas-deflector 31, through the neck 22 and into the inflatable chamber of the air-bag 2. This position of the flaps 37 is also illustrated in phantom in Figure 2, from which it will be seen that the two flaps 37 serve to protect the regions of the air-bag 2 defining the neck 22 from the high pressure and high velocity flow of gas.

As will also be seen from Figure 5, the two deformable fingers 38 which initially lay between the closed flaps 37 are also plastically deformed outwardly upon actuation of the gas-generator 25, and these deformable fingers 38 also serve a protective function by protecting regions of the fabric sheets forming the neck 22 of the air-bag 2.

It will therefore be seen that the above-described arrangement provides a gas-deflector configured specifically to protect the regions of the air-bag defining the inlet neck 22 from the aggressive inflow of gas. Also, the arrangement by which the gas-generator 25 is clamped to the inlet region 23 at its two ends by respective clamps 27 which can be secured directly to the structure of the motor vehicle, provides a secure arrangement in which there is less tendency for the gas-generator 25 to move relative to the structure of the motor vehicle upon actuation.

Whilst the present invention has been described above with reference to specific application to a "centre-fill" inflatable curtain-type air-bag in which the gas-generator is located centrally with respect to the air-bag, in the region of the B-pillar of a motor vehicle, the present invention could be applied to other configurations of air-bag. For example, an alternative configuration of inflatable curtain 40 is illustrated in Figure 6, in which the gas-generator 41 is located at one end of the inflatable curtain 40 and is provided in fluid communication with an elongate gas-fill duct 42 running substantially the entire length of the inflatable curtain 40 in the region of the uppermost edge of the inflatable curtain 40. The inflatable curtain 40 has an inflatable chamber 43 which is divided into a number of discrete inflatable zones 44, each being separated by a seam or co-woven region 45. Each inflatable zone 44 has a neck region 46 providing fluid communication between the zones 44 and the uppermost fill duct 42. Running along the length of the fill-duct 42, there is provided an elongate gas-deflector 47 provided with a plurality of pairs of flaps 48 of substantially identical configuration to the flaps 37 described with reference to Figures 4 and 5. In the initial configuration illustrated in Figure 6, each pair of flaps 48 are provided in an initial closed configuration and open upon actuation of the gas-generator 41 so as to extend into the neck regions 46 of each inflatable zone 44, thereby protecting the delicate regions of the air-bag defining the necks 46.

Figures 7 to 9 illustrate another alternative configuration of the air-bag arrangement according to the present invention. In this arrangement, the air- bag 50 has a gas inlet portion 51 which is generally L-shaped so as to define a single inlet duct 52 arranged for fluid communication with the neck 53 of the air-bag. In this respect, it will therefore be seen that the arrangement illustrated in Figure 7 is very similar to that illustrated in Figure 3.

An elongate gas-generator 54 is inserted through the inlet duct 52 so as to lie within the gas inlet portion 51 such that the forwardmost end 55 of the gas-generator 54, which is provided with a plurality of gas outlet apertures 56, lies above the open part of the neck 53. The rearmost end of the gas-generator 54 is secured to the inlet portion 51 by a clamp 57 in exactly the same manner as described above with reference to the arrangements of Figures 2 and 3.

A first elongate gas-deflector 58 is provided which extends substantially across the neck 53 of the air-bag 50. The gas-deflector 58 is again tubular and is mounted over and around the gas-generator 54 so as to lie between the gas outlet apertures 56 and the neck 53 of the air-bag 50. As in the previous embodiments, the first gas-deflector 58 is positioned between the two layers of fabric defining the gas inlet portion 51 of the air-bag. The longitudinal axis of the gas-deflector 58 thus extends between the two layers of fabric of the air-bag and the gas-deflector 58 thus defines a notional axis extending between the two layers of fabric and passing across the top of the neck 53.

The gas-deflector 58 is preferably sized and configured so as to be a push-fit or interference fit over the gas-generator 54, such that the gas-deflector 58 can simply and easily be mounted on the gas-generator 54 so as to remain in the position illustrated.

As in the previous embodiments described above, the first gas-deflector 58 is elongate and cylindrical and has a generally uniform circular cross- section. The gas-deflector 58 maybe moulded or extruded from plastics material or could be made from metal material either by rolling a sheet of metal into the cylindrical configuration illustrated, or by extrusion.

In this arrangement, the underside of the first gas-deflector 58 is provided with a single flap 59 having a generally identical configuration to the flaps of the above-described arrangements. In the configuration illustrated in Figure 7, the flap 59 is closed so as to extend between the gas outlet apertures 56 of the gas-generator 54 and the neck region 53 of the air-bag.

Positioned over the first gas-deflector 58 is a second gas-deflector 60 which takes the form of a sleeve of material. As illustrated most clearly in Figure 8, which is a sectional view of the arrangement illustrated in Figure 7, taken along line A-A, the second gas-deflector 60 is provided around the first gas-deflector 58 in a folded configuration. In particular, it will be seen that the sleeve of the second gas-deflector 60 extends over and around the upper part of the first gas-deflector 58, and extends downwardly and inwardly towards the central under-region of the first gas-deflector 58, at which point the sleeve turns outwardly about a pair of folds 61,62. From these folds, respective parts of the sleeve defining the second gas-deflector 60 extend outwardly and upwardly around adjacent sides of the first gas-deflector 58, to terminate at respective second folds 63,64. The lowermost part of the sleeve defining the second gas- deflector 60 passes around and below the first gas-deflector 58 from the two respective second folds 63, 64. It will therefore be appreciated that in the initial configuration illustrated in Figures 7 and 8, the second gas-deflector 60 is provided around the first gas-deflector 58 such that the second gas-deflector 60 descends over the flap 59 of the first gas-deflector 58.

Turning now to consider Figure 9, the arrangement is illustrated after actuation of the gas-generator 54. As the gas-generator 54 is actuated, it expels a volume of gas through the outlet apertures 56 which serves to deform and open the flap 59 as illustrated in Figure 9. The flap 59 opens pivotally about its hinge axis so as to extend into the neck portion 53 of the air-bag 50, thereby serving to protect the closed end of the gas inlet portion 51 through the aggressive flow of gas from the gas-generator 54. As the flap 59 opens, and gas flows through the first gas-deflector 58 and past the flap 59, the second gas- deflector 60 is caused to unfold so as to adopt the fully-extended position illustrated in Figure 9, in which it extends through the neck 53 and into the interior chamber of the air-bag 50. In this actuated configuration, it will therefore be appreciated that the second gas-deflector 60 serves to deflect the flow of gas passing through the first gas-deflector 58 so as to direct the gas flow both forwardly and rearwardly into the interior chamber of the air-bag as indicated by arrows 65 and 66 in Figure 9.

Of course, whilst the arrangement illustrated in Figures 7 to 9, incorporating the second gas-deflector 60 has been described being installed over a first gas-deflector 58 having a single flap 59, it should be appreciated that the second gas-deflector 60 could also be installed over the other gas- deflectors described hereinbefore having a pair of openable flaps.

Also, whilst the second gas-deflector of the arrangement illustrated in Figures 7 to 9 has been described taking the form of a sleeve of flexible fabric material, the sleeve could, in variance of the invention, be made from flexible or deformable metal.

In the present specification "comprises" means "includes or consists of and "comprising" means "including or consisting of.

Claims

CLAIMS:

1. An air-bag arrangement comprising: an air-bag having a pair of superimposed layers, a gas generator to inflate the air-bag, and a gas generator with a gas-deflector; the air-bag defining a neck formed between said layers for fluid communication between the gas generator and an inflatable chamber defined between the layers; wherein the gas-deflector extends at least partially across the neck and has a notional axis extending across the neck between said layers; the gas-deflector having at least one flap pivotally moveable about a respective hinge axis, the hinge or each hinge axis being transverse to said notional axis, the or each said flap being initially located in a closed position but being configured to pivot about said hinge axis upon actuation of the gas- generator so as to open towards said chamber, extending at least partly into the neck.

2. An air-bag arrangement according to claim 1, wherein the or each flap is integral with a body-part of the deflector and wherein the or each respective said hinge axis is defined by a deformable web interconnecting the body-part and the respective flap.

3. An air-bag arrangement according to claim 1 or 2, wherein the or each said flap is each defined by a respective substantially C-shaped slot provided through part of the gas-deflector.

4. An air-bag arrangement according to claim 3, wherein the or each said slot is substantially arcuate.

5. An air-bag arrangement according to any preceding claim, comprising a pair of said flaps, wherein the hinge axis of one said flap is substantially parallel to the hinge axis of the other said flap, and said flaps are initially located between said hinge axes.

6. An air-bag arrangement according to claim 5 wherein said flaps are spaced from one another so as to define a region of the gas-deflector between the two flaps, said region of the gas-deflector being deformable and configured to deform upon actuation of the gas-generator so as to open towards at least the respective layers of fabric.

7. An air-bag arrangement according to claim 6, as dependant upon claim 3 or claim 4, wherein a slot is provided through said deformable region of the gas-deflector between the two flaps, said slot extending from the substantially C-shaped slot of one flap to the substantially C-shaped slot of the other flap to divide the deformable region of the gas-deflector into a pair of deformable parts.

8. An air-bag arrangement according to claim 7, wherein said deformable parts are each configured to deform about a respective axis oriented so as to be substantially perpendicular to said hinge axes.

9. An air-bag arrangement according to any preceding claim, wherein the gas-deflector is of plastics material.

10. An air-bag arrangement according to any one of claim 1 to 8, wherein the gas-deflector is of metal.

11. An air-bag arrangement according to any preceding claim, wherein the gas-generator is elongate and the gas-deflector is substantially cylindrical, the gas-generator being located within the gas-deflector.

12. An air-bag arrangement according to claim 11, wherein the gas-deflector is engaged with the gas-generator as an interference fit.

13. An air-bag arrangement according to claim 11 or claim 12, wherein said air-bag defines a gas-inlet portion and said gas-generator is located within said gas-inlet portion, the gas-inlet portion of the air-bag being secured to the gas- generator by a pair of clamps, the clamps being spaced from one another along the length of the gas-generator.

14. An air-bag arrangement according to claim 13, wherein said gas-inlet portion of the air-bag is substantially T-shaped and defines a pair of opposed inlet ducts in communication with said neck, each said clamp being provided around a respective said inlet duct so as to clamp the inlet ducts to the gas- generator.

15. An air-bag arrangement according to claim 13, wherein said gas-inlet portion of the air-bag is substantially L-shaped and defines a single inlet duct in communication with said neck, one of said clamps being provided around said inlet duct so as to clamp the inlet duct to the gas-generator, the other clamp passing through an aperture provided in the gas-inlet portion of the air-bag to clamp the air-bag to the gas-generator.

16. An air-bag arrangement according to any one of claims 13 to 15, wherein each said clamp is configured for securement to part of the structure of a motor vehicle.

17. An air-bag arrangement according to any preceding claim, comprising first and second gas-deflectors, wherein said gas-deflector having at least one flap defines the first gas-deflector, the second gas-deflector initially being provided around at least part of the first gas-deflector in a folded configuration such that at least part of the second gas-deflector extends over the or each flap of the first gas-deflector, the second gas-deflector being configured to unfold so as to extend at least partly into the neck as the or each said flap opens upon actuation of the gas-generator.

18. An air-bag arrangement according to claim 17, wherein said second gas- deflector takes the form of a sleeve engaged over said first gas-deflector.

19. An air-bag arrangement according to claim 17 or 18, wherein said second gas-deflector is of fabric.

20. An air-bag arrangement according to claim 17 or 18, wherein said second gas-deflector is of metal.