Patent Description:
It is now very widely known to provide airbags in motor vehicles to provide protection to the occupants of the vehicle in the event of an accident, and more recently also to provide airbags arranged to inflate over a region of the outside of a vehicle in order to provide protection to pedestrians in the event that they are stuck by the vehicle. Airbags of all types have become rather sophisticated over the years, and many now have particular and somewhat complicated shapes dictated by their specific function, their required inflation characteristics, and the shape and configuration of the part of the vehicle to which they are to be mounted or into or across which they are intended to inflate. Such airbags are initially provided in the form of a tightly folded and/or rolled package provided within an airbag module mounted to the motor vehicle.

Conventionally, airbags are manufactured from woven fabric, and typically comprise two or more layers of fabric which are interconnected by seams. In many cases the layers of fabric are woven separately and then stitched together to provide stitched seams, but in some cases the layers may be adhesively bonded to one another to form bonded seams, or may be heat-fused together to form fused seams. In some cases, however, two layers of fabric may be woven simultaneously via a so-called one-piece-weaving technique in which the yarns of one fabric layer are interwoven with the yarns of the other fabric layer in some areas to thereby create woven seams in those areas which are integral to the weave of the airbag fabric.

Airbags generally have an inlet, which is typically connected directly to an inflator such as a gas generator, and which permits the inflow of inflating gas from the inflator to inflate the airbag. Such inflators are configured to produce a large volume and aggressive flow of inflating gas, and so the forces applied to the region of the airbag in which the inlet is provided are can be extremely high. In some circumstances this can make it difficult to achieve a desirable inflation characteristic for the airbag in the event that there are limitations on the possible location of the inflator. Additionally, inflators can present an injury risk to a vehicle occupant in the event that they must be located in close proximity to the occupant; for example through impact with the inflator in the event of a crash. Inflators can also become very hot during operation, which can present a burn risk to an occupant in close proximity to the inflator. It has thus been found that for some airbag installations it can be difficult to locate the inflator appropriately so as to ensure correct inflation characteristics whilst also ensuring that a vehicle occupant in close proximity to the inflator is adequately protected from the risk of injury arising from contact or impact with the inflator.

<CIT> discloses an inflatable airbag for a motor vehicle safety arrangement. <CIT> discloses a pedestrian-protecting air bag arrangement and a method of folding and storing a pedestrian-protecting air bag arrangement.

According to the present invention, there is provided an inflatable airbag for a motor vehicle; the airbag comprising a pair of superimposed layers of fabric interconnected by a peripheral seam extending around and defining the bounds of a single inflatable chamber between said layers; said inflatable chamber having an inlet region comprising a fluid inlet connected to an inflator; wherein first and second peripherally spaced-apart regions of said peripheral seam are interconnected and secured to one another such that said inlet region is superimposed with at least one other region of the inflatable chamber to thereby induce an inflated shape to said chamber upon inflation of the airbag by a flow of gas from said inflator, said inflated shape having at least one said other region of the inflatable chamber lying adjacent said inflator upon inflation of the airbag. Optionally, said inflated shape is further characterised by at least one said other region of the inflatable chamber bearing against said inflator upon inflation of the airbag.

In some embodiments, said inflated shape optionally has a two-tiered configuration in which said inlet region bears against at least one said other region.

Conveniently, said pair of superimposed fabric layers comprise an upper fabric layer and a lower fabric layer, and wherein said inlet region of the inflatable chamber is superimposed with the or each said other region such that said lower fabric layer of the inlet region bears against said upper fabric layer of the or each other region when the airbag is inflated. Optionally, said first and second regions of said peripheral seam are interconnected and secured to one another such that said inlet region of said inflatable chamber is superimposed with two discrete other regions of said inflatable chamber.

Said inlet region of the inflatable chamber may overly said first and second regions of the peripheral seam.

According to a second aspect of the present disclosure there is provided an inflatable airbag for a motor vehicle; the airbag comprising a pair of superimposed layers of fabric interconnected by a peripheral seam extending around and defining the bounds of a single inflatable chamber between said layers; wherein first and second peripherally spaced-apart regions of said peripheral seam are interconnected and secured to one another to thereby induce a three-dimensional inflated shape to said chamber upon inflation of the airbag such that said peripheral seam follows a non-planar path.

In some embodiments of said second aspect of the present disclosure said first and second regions of said peripheral seam are spaced-apart and interconnected and secured to one another such that a first region of said inflatable chamber is superimposed with at least one other region of said inflatable chamber to thereby impart a two-tiered inflated configuration to at least part of said inflatable chamber upon inflation of the airbag.

Optionally, said first region of the inflatable chamber overlies said first and second regions of the peripheral seam.

Conveniently, said first region of said inflatable chamber may define an inlet to said inflatable chamber, the inlet being configured for engagement with an inflator.

In some embodiments of said second aspect of the disclosure said pair of superimposed fabric layers comprise an upper fabric layer and a lower fabric layer, and said first region of the inflatable chamber is superimposed with the or each said other region such that said lower fabric layer of the first region bears against said upper fabric layer of the or each other region when the airbag is inflated.

Optionally, said first and second regions of said peripheral seam are interconnected and secured to one another such that said first region of said inflatable chamber is superimposed with two discrete other regions of said inflatable chamber.

In embodiments of either said first or second aspects having two discrete other regions of said inflatable chamber, those regions may be of substantially identical shape and configuration.

In some embodiments of both aspects said first region of the peripheral seam bounds part of one said discrete other region of the inflatable chamber, said second region of the peripheral seam bounds part of the other said discrete other region of the inflatable chamber, and said two discrete other regions of the inflatable chamber are interconnected by connection of said first and second regions of the peripheral seam to one another.

Optionally, said two discrete other regions of said inflatable chamber may be substantially mirror symmetrical about said connection between the first and second regions of the peripheral seam.

Embodiments in accordance with both the first aspect and the second aspect may be configured such that said peripheral seam has an interconnection width across which said layers of fabric are interconnected, and wherein said first and second regions of the peripheral seam are interconnected and secured to one another by a connection formed wholly within said interconnection width.

Optionally, said interconnection width varies along said peripheral seam and is greater at said first and second regions of the peripheral seam than elsewhere along the seam. Alternatively, said interconnection width varies along said peripheral seam and is narrower at said first and second regions of the peripheral seam than elsewhere along the seam.

Said connection may comprise stitching. Alternatively, or additionally, said connection may comprise adhesive, or may be formed via the application of heat to fuse said first and second regions of the peripheral seam together. Alternatively, or additionally, said connection may comprise one or more rivets or other mechanical fasteners to secure said first and second regions of the peripheral seam together.

Optionally, said first and second regions of the peripheral seam are interconnected and secured to one another by stitching. Alternatively, or additionally, said first and second regions of the peripheral seam may be interconnected and secured to one another by one or more rivets or other mechanical fasteners.

Said first and second regions of the peripheral seam may be superimposed.

Embodiments in accordance with both the first and second aspects may be configured such that each said layer of fabric is woven and comprises a plurality of yarns, at least some of the yarns of one said layer of fabric being interwoven with at least some of the yarns of the other said layer to define said peripheral seam, the peripheral seam thereby being woven and integral to the structure of said layers.

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:.

The invention disclosed herein is suitable for implementation in airbags of various and wide ranging different types such as, for example, driver airbags, front passenger airbags, rear passenger airbags, knee airbags, thorax airbags, side airbags, inflatable side curtains, and pedestrian airbags of a type intended to inflate across part of the exterior of a motor vehicle in order to offer protection to a pedestrian in the event of being struck by the motor vehicle.

In <FIG>, there is illustrated a partially constructed airbag <NUM> in accordance with the present invention, the airbag being shown in an uniflated condition and laid out flat.

The airbag <NUM> is formed from two layers of flexible fabric <NUM>, <NUM> which are of substantially identical shape. The layers <NUM>, <NUM> are shown arranged in superimposition in <FIG>, with the upper layer <NUM> extending across the lower layer <NUM>. The upper and lower layers <NUM>, <NUM> are interconnected by a peripheral seam <NUM> which extends around and defines the bounds <NUM> of a single inflatable chamber <NUM> between the two layers.

In preferred embodiments of the invention, it is proposed that the interconnected layers <NUM>, <NUM> of the airbag <NUM> will be woven simultaneously on a single loom, via a so-called 'one-piece weaving' technique in which yarns of one of the layers are interwoven with yarns of the other layer in specific areas to define the peripheral seam <NUM>. In such embodiments, the resulting peripheral seam <NUM> is thus woven as an integral and part of both layers <NUM>, <NUM> of fabric, whilst the layers remain separate from one another inside the bounds of the peripheral seam <NUM> to thereby define the inflatable chamber <NUM>. As illustrated in <FIG>, the yarns of the two layers <NUM>, <NUM> may also be interwoven in other areas <NUM> so as to interconnect the two layers <NUM>, <NUM> inside the bounds <NUM> of the peripheral seam <NUM>. In the airbag illustrated in <FIG>, the other interwoven areas <NUM> define an array of internal seams to thereby create a series of generally parallel inflatable cells <NUM> within the inflatable chamber <NUM> formed between the layers <NUM>, <NUM>.

It is to be appreciated, however, that whilst the airbag of the present invention may be particularly suited to fabrication via the type of one-piece weaving technique described above, it is not restricted to the use of such a technique. Indeed, it is envisaged that in other embodiments the peripheral seam <NUM>, and also any required internal seams such as those indicated in areas <NUM> in <FIG>, may be formed in other convenient ways apparent to those of skill in the art. For example, it is envisaged that in some embodiments the fabric layers <NUM>, <NUM> may be formed entirely separately from one another as separate sheets and thereafter interconnected by seams which may be formed by conventional stitching to interconnect the fabric layers <NUM>, <NUM>, and/or may be created using adhesive to bond the fabric layers <NUM>, <NUM> together, or which may even be formed by the application of heat to fuse the fabric layers <NUM>, <NUM> together.

In the embodiment illustrated in <FIG>, in which the peripheral seam <NUM> is formed via the one-piece weaving technique described above, it will be observed that the peripheral seam <NUM> has a transverse interconnection width w across which the yarns of the two layers <NUM>, <NUM> are interwoven to thereby interconnect the layers <NUM>, <NUM>. As will be observed, the interconnection width w may vary somewhat along the peripheral seam <NUM>, such that some regions of the peripheral seam <NUM> are wider than other regions.

It will be observed that in the case of the particular airbag <NUM> illustrated in <FIG>, the interconnected fabric layers <NUM>, <NUM> have a very approximately elongate rectangular shape. In more detail it will be observed that at one end (the left-hand end in <FIG>), the fabric layers <NUM>, <NUM> are each shaped to define a centrally located and somewhat L-shaped formation 11a, 12a which is positioned between a pair of substantially identically-shaped projecting wings 11b, 12b. The peripheral seam <NUM> interconnects the two fabric layers <NUM>, <NUM> around their entire peripheral extent, including the wings 11b, 12b and the L-shaped formations, except for a short length along the aligned L-shaped formations 11a, 12a which remain unconnected to thereby define a fluid inlet <NUM> to the inflatable chamber <NUM>. The aligned and interconnected L-shaped formations 11a, 12a of the two fabric layers <NUM>, <NUM> cooperate to define a first region <NUM> of the inflatable chamber <NUM>, whilst the aligned and interconnected wings 11b, 12b of the two fabric layers <NUM>, <NUM> cooperate to define respective discrete wing regions <NUM> of the inflatable chamber <NUM>. More particularly, the first region of the inflatable chamber <NUM> defines an inlet region of the inflatable chamber <NUM> which is configured for connection to an inflator, as will be described in more detail below.

It will be observed in <FIG> that one pair of wings 11b, 12b of the fabric layers are interconnected by a first straight region <NUM> of the peripheral seam <NUM>, whilst the other pair of wings 11b, 12b are interconnected by a second straight region <NUM> of the peripheral seam <NUM>. The first and second straight regions <NUM>, <NUM> of the peripheral seam <NUM> may be of equal length to one another, and each bound part of a respective wing region <NUM> of the inflatable chamber <NUM>. As will be appreciated, the first and second regions <NUM>, <NUM> of the peripheral seam <NUM> are peripherally spaced-apart from one another, in the sense that they are each located at respective spaced-apart positions around the seam <NUM>. Furthermore, it will be noted that in the particular airbag configuration illustrated in <FIG>, the aforementioned first and second straight regions <NUM>, <NUM> of the peripheral seam <NUM> each have an interconnection width w which is greater than elsewhere along the seam <NUM>, such as the regions indicated by reference number <NUM> along the sides of the main central area of the inflatable chamber <NUM> which have a relatively narrow interconnection width w. However, this is not considered an essential aspect of the proposal, and in other embodiments it is envisaged that the first and second straight regions <NUM>, <NUM> of the peripheral seam <NUM> may have an interconnection width w which is smaller than elsewhere along the seam <NUM>. For example, embodiments are envisaged in which the interconnection width w of the peripheral seam <NUM> varies around the seam as a function of distance from a datum point. An example datum point X is shown in <FIG>, which is located along the peripheral seam <NUM> in a generally longitudinally central position along the length of the airbag <NUM>, where the width of the airbag <NUM> is narrowest. It is envisaged that the interconnection width w will be greater in regions of the peripheral seam distal to the datum point X than in regions of the peripheral seam proximal to the datum point X. Embodiments are therefore possible, for example in the case of particularly large airbags, in which regions of the peripheral seam <NUM> remote from the datum point X may have an interconnection width w which is in fact greater than the interconnection width of the first and second regions <NUM>, <NUM>.

Turning now to consider <FIG>, the airbag <NUM> is illustrated following a subsequent step in its construction. In particular, <FIG> shows the airbag <NUM> after the two wing regions <NUM> of the inflatable chamber <NUM> have been manipulated and moved underneath the inlet region <NUM> such that their respective first and second straight regions <NUM>, <NUM> of the peripheral seam <NUM> overlie one another in superimposition. The superimposed relationship of the first and second straight regions <NUM>, <NUM> of the peripheral seam <NUM> is illustrated most clearly in the cross-sectional view of <FIG>. In this configuration, it will be observed that part of the inlet region <NUM> of the inflatable chamber <NUM> becomes superimposed across the top of part of each wing region <NUM>. Furthermore, it is to be noted that in this configuration the two wing regions <NUM> of the inflatable chamber <NUM> are not turned or folded over on themselves, and so the lower fabric layer <NUM> of the inlet region <NUM> lies across the top of the upper fabric layer <NUM> of each wing region <NUM>.

The superimposed first and second straight regions <NUM>, <NUM> of the peripheral seam <NUM> are then secured to one another. In preferred embodiments this is achieved by the creation of one or more lines of stitching <NUM> to form a connection interconnecting the first and second regions <NUM>, <NUM> of the peripheral seam <NUM>. This is illustrated most clearly in <FIG> which shows the end region of the airbag <NUM> as viewed from below. The connection of the first and second regions <NUM>, <NUM> of the peripheral seam <NUM> to one another thereby also interconnects the two wing regions <NUM> of the inflatable chamber <NUM>. It is to be noted, however, that in alternative embodiments it is envisaged that the regions <NUM>, <NUM> of the peripheral seam <NUM> may be secured to one another in other convenient ways apparent to those of skill in the art. For example, it is envisaged that in some embodiments the regions <NUM>, <NUM> may be secured to one another by using adhesive to bond the regions <NUM>, <NUM> together, or may even be fused together using the application of heat. In other embodiments it is envisaged that the regions <NUM>, <NUM> may be secured to one another via the use of rivets or other such fasteners.

It is to be appreciated at this juncture that <FIG> shows a pair of optional mounting tabs <NUM> of the airbag <NUM> which are not illustrated in <FIG> and <FIG>. Each mounting tab <NUM> projects outwardly from a respective wing region <NUM>. The mounting tabs <NUM> may be provided to facilitate fixture of the airbag <NUM> to the structure of a motor vehicle. As will be appreciated, in other embodiments the mounting tabs <NUM> may be provided at other positions around the airbag.

It is considered preferable for the or each line of stitching <NUM> securing the first and second regions <NUM>, <NUM> of the peripheral seam <NUM> to one another to be formed wholly within the interconnection width w of the peripheral seam in those regions.

Having regard to <FIG>, it will be noted that in the illustrated embodiment the two wing regions <NUM> of the inflatable chamber <NUM> are substantially mirror symmetrical about the connection formed by the stitching <NUM> interconnecting the first and second regions <NUM>, <NUM> of the peripheral seam.

Turning now to consider <FIG>, the completed airbag <NUM> is illustrated in combination with an inflator <NUM> which may be, for example, a gas generator of a type known per se. The inflator <NUM> is elongate and generally cylindrical in form and is connected to the fluid inlet <NUM> of the airbag <NUM> by insertion therethrough such that the majority of the inflator's length sits inside the inlet region <NUM> of the inflatable chamber <NUM>. A clamp <NUM> is provided around the fabric of the inlet region <NUM> proximate the fluid inlet <NUM>, to thereby secure the inflator to the airbag <NUM>. As will be appreciated by those of skill in the art, the inflator <NUM> comprises a series of gas outlets which are thus positioned inside the inlet region <NUM> of the inflatable chamber <NUM>, whilst the exposed end of the inflator comprises an electrical connector <NUM> for connection to circuitry, which will typically comprise a crash sensor and an electronic control unit, and which is operable to detect the occurrence of an impact or crash, and thereupon send an actuation signal to the inflator to actuate the inflator. Actuation of the inflator is effective to direct a flow if inflating gas into the inlet region <NUM> of the inflatable chamber <NUM>, the inflating gas being directed from there into the main region of the inflatable chamber <NUM> in order to inflate the airbag <NUM>, and from there into the two wing regions <NUM>, as indicated generally by the arrows in <FIG>.

Turning now to consider <FIG>, the above-described airbag <NUM> is illustrated in an inflated condition, representative of its shape and configuration following actuation of the inflator <NUM> and thus inflation of the inflatable chamber <NUM>. As illustrated, both the inlet region <NUM> and the two wing regions <NUM> achieve an inflated configuration in which the fabric layers <NUM>, <NUM> are urged apart by the inflating gas from the inflator <NUM>.

As will be appreciated, were the peripherally spaced-apart regions <NUM>, <NUM> of the peripheral seam <NUM> not interconnected and secured as described above, with the two wing regions <NUM> of the inflatable chamber <NUM> interconnected beneath the inlet region <NUM>, then the airbag <NUM> would naturally achieve a generally flat two-dimensional inflated shape upon inflation, in which the peripheral seam <NUM> would follow a generally planar path around the airbag <NUM>. However, because of the manner in which the peripherally spaced-apart regions <NUM>, <NUM> of the peripheral seam <NUM> are in fact interconnected and secured to one another adjacent the inlet region <NUM>, the effect of their interconnection is to induce a three-dimensional inflated shape to the inflatable chamber <NUM> upon inflation of the airbag, in which the peripheral seam <NUM> instead follows a non-planar path. This is illustrated most clearly in <FIG>, where it can be seen that the inlet region <NUM> of the inflatable chamber <NUM> bears against the wing regions <NUM> in their inflated configurations, which thereby i) urges the wing regions <NUM> slightly downwardly, and ii) urges the inlet region <NUM> slightly upwardly, such that regions of the peripheral seam extending around and bounding the wing regions <NUM> of the inflatable chamber extend out of plane with regions of the peripheral seam extending around and bounding the inlet region <NUM>. The inflated shape of the inflatable chamber <NUM> thereby achieves a two-tiered configuration in the area of the inflator <NUM>, the inlet region <NUM> and the wing regions <NUM>, with the inflated shape of the inlet region <NUM> representing an upper tier, and the inflated shape of the wing regions <NUM> representing a lower tier. Furthermore, because the inflated inlet region <NUM> bears against the inflated wing regions <NUM>, the inlet region <NUM> may offer some support to the wing regions <NUM> and vice-versa.

As will also be appreciated from <FIG>, when the airbag <NUM> is inflated, the inlet region <NUM> of the inflatable chamber overlies the interconnected first and second regions <NUM>, <NUM> of the peripheral seam <NUM>, and is superimposed with the two wing regions <NUM> such that the lower layer of fabric <NUM> of the inlet region <NUM> bears against the upper layer of fabric <NUM> of the wing regions <NUM>. Furthermore, having regard to <FIG>, it should also be appreciated that when the airbag <NUM> is inflated, one of the wing regions <NUM> of the inflatable chamber <NUM> will adopt an inflated configuration in which it lies adjacent and bears against the inflator <NUM>, thereby offering the possibility of supporting the inflator <NUM> and providing a cushioning effect to provide protection for a vehicle occupant (or a pedestrian in the case of a pedestrian airbag) against potentially injurious impact with the inflator <NUM> in an accident. The fact that the wing region <NUM> lies adjacent the inflator <NUM> also offers some protection to the occupant (or pedestrian) from the risk of burning, as it will help to prevent contact with the inflator <NUM> which can become very hot upon actuation.

While the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when given this disclosure. Accordingly, the exemplary embodiments of the invention set forth above are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the scope of the invention, according to the appended claims.

Claim 1:
An inflatable airbag (<NUM>) for a motor vehicle; the airbag (<NUM>) comprising a pair of superimposed layers of fabric (<NUM>, <NUM>) interconnected by a peripheral seam (<NUM>) extending around and defining the bounds (<NUM>) of a single inflatable chamber (<NUM>) between said layers (<NUM>, <NUM>); said inflatable chamber (<NUM>) having an inlet region (<NUM>) comprising a fluid inlet (<NUM>) connected to an inflator (<NUM>); wherein first and second peripherally spaced-apart regions (<NUM>, <NUM>) of said peripheral seam (<NUM>) are interconnected and secured to one another such that said inlet region (<NUM>) is superimposed with at least one other region (<NUM>) of the inflatable chamber (<NUM>) to thereby induce an inflated shape to said chamber (<NUM>) upon inflation of the airbag (<NUM>) by a flow of gas from said inflator (<NUM>), said inflated shape having at least one said other region (<NUM>) of the inflatable chamber (<NUM>) lying adjacent said inflator (<NUM>) upon inflation of the airbag (<NUM>).