Previously it has been proposed to fold an air-bag by taking a flat, deflated air-bag having two adjacent layers of fabric and effecting a series of folds of both layers of fabric simultaneously about linear fold-lines. Often co-operating folding"swords"are utilised, which approach the air-bag from opposite sides to effect linear folds. The bag is thus folded in a very"tidy"fashion, and can be fitted within an appropriate housing.

A problem that arises when an air-bag is folded in this way is that the air-bag, when uninflated, essentially comprises two adjacent layers of fabric which are adapted, on inflation of the bag, to become separated. The two layers of fabric are folded simultaneously, and thus two adjacent layers of fabric are folded together about a common linear fold-line. This effectively prevents the flow of any gas past that fold until the fold has been unfolded. This can lead to unpredictable inflation of an air-bag.

Another problem that is difficult to solve when using a folding machine incorporating swords is the folding of the air-bag around the gas generator, which is often round or cylindrical.

It has been proposed to fold an air-bag using a technique in which parts of the air- bag are merely pressed towards each other, becoming crushed or crumpled with a so-called "scrunching"effect.

DE 195 35 564 discloses an arrangement in which an air-bag is initially laid out, substantially flat, on a folding table. The particularly described air-bag is of a trapezoidal form and, when laid out flat on the table, comprises two super-imposed layers of fabric. A plurality of pushers are provided which push portions of the bag radially inwardly, thus crumpling or scrunching the bag. However, as the bag is crumpled or scrunched, the two layers of fabric are crumpled or scrunched together, and the layers are not crumpled or scrunched individually. Thus, using this technique, plurality of folds of adjacent layers of fabric are achieved, with the two layers of fabric being folded simultaneously about the same fold-line. These folds tend to prevent the flow of gas past the folds when the gas generator is actuated.

DE 195 38 625 discloses another arrangement in which a circular air-bag to be inflated is first of all stretched out substantially flat, and then the central part of the air-bag is drawn upwardly into an annular chamber defined between a hollow cylindrical housing and a central rod. An annular member, having the same cross-section as the chamber, is then pressed into the chamber causing the air-bag to crumple or scrunch. The arrangement disclosed can only be used for air-bags of a round shape, and is relatively complex with several procedural steps that need to be followed, and with a final transference of the folded bag into a housing.

The present invention seeks to provide an improved method of folding an air-bag, apparatus for performing the method and consequently an improved air-bag folded by the method.

According to one aspect of this invention there is provided a method of folding an air-bag, the method comprising the steps of taking an air-bag connected to a housing dimensioned to receive the air-bag when folded, inserting the air-bag, to hang down in loose folds, into a recess, applying a first upward compressing force to the air-bag along a first substantially vertical predetermined axis in order to crumple or scrunch the air-bag, subsequently applying a compressional force to the air-bag along a substantially horizontal axis to crumple or scrunch the air-bag, and finally moving the crumpled or scrunched air- bag upwardly into the housing.

Preferably, when the air-bag is introduced into the recess in loose folds, part of the air-bag is caused to lie at a predetermined position adjacent the housing, the rest of the air- bag hanging in loose folds within the recess.

Conveniently, before the first force is applied to the air-bag, closure panels are located to close the originally open part of the recess in order to close the recess.

Advantageously, the first compressional force is applied to the air-bag by means forming the base of the recess, which means are driven upwardly towards the originally open part of the recess, the second force is applied by opposed transversely moving elements and the crumpled or scrunched air-bag is moved upwardly into the housing by a plunger member forming part of the element applying the first force to the air-bag.

The invention also relates to an apparatus for folding an air-bag, the apparatus comprising a housing defining a recess. the base of the recess comprising at least first plunger member adapted to move upwardly towards the open mouth of the recess along a first substantially vertical axis, the recess being provided, adjacent the open end thereof, with at least one plunger adapted to move substantially horizontally, covering panels being provided adapted to be moved from a first position in which the upper part of the recess is open to a second position in which the upper part of the recess is closed.

Preferably, a central guide element is provided within the recess.

Conveniently, the guide element is a guide rod.

Alternatively, the guide element is a guide wall.

Conveniently, the base of the recess comprise two plungers, an outer plunger having an outer configuration corresponding to the cross-section of the recess, and an inner plunger, the inner plunger being initially co-planar with the outer plunger, the inner plunger being adapted to move upwardly relative to the outer plunger to insert a crumpled and scrunched air-bag into a housing dimensioned to receive the folded air-bag.

The invention also relates to a folded and packaged air-bag whenever folded by compressing means which apply a first upward compressional force to a loosely hanging air-bag to crumple or scrunch the air-bag, and second compressing means adapted to apply a second substantially horizontal compressing force, to the initially crumpled or scrunched air-bag, and when packaged by means which move the air-bag upwardly into a housing.

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 perspective view of an apparatus in accordance with the invention, FIGURE 2 is a sectional view through part of the apparatus of Figure 1 in an initial condition, FIGURE 3 is a view corresponding to Figure 2 showing a subsequent condition of the apparatus, FIGURE 4 is a view corresponding to Figure 3 showing a further subsequent condition of the apparatus, FIGURE 5 is a view corresponding to Figure 4 showing a further subsequent condition of the apparatus, FIGURE 6 is a view corresponding to Figure 5 showing the further subsequent condition of the apparatus, FIGURE 7 is a view corresponding to Figure 6 showing a further subsequent condition of the apparatus, and FIGURE 8 is a view corresponding to Figure 7 illustrating a further subsequent condition of the apparatus, and FIGURE 9 is a view corresponding to Figure 1 of an alternative apparatus.

Referring initially to Figures I and 2, an apparatus 1 in accordance with the invention is intended for use in folding an air-bag 2 as shown in Figure 2. The air-bag 2 is intended to be supplied to the apparatus 1 with the air-bag being connected to a housing 3 and having an internal gas generator 4 within the air-bag. The housing 3 may be of any appropriate shape, for example of rectangular form. Some housings are of a trapezoidal form. The housing having a length 1 as shown in Figure 2, and having a width w measured in a direction extending transversely to the axis of length 1. The housing 3 is provided to accommodate the air-bag when it is folded. Such a housing, gas generator and air-bag are known per se.

The apparatus 1 comprises a housing 5. The housing 5 defines a centrally located substantially rectangular recess 6 which has a length L which is greater than the length I of the housing 3 as shown in Figure 2, and a width W which is substantially equal to the width w of the housing 3 shown in Figure 2.

Upstanding in the centre of the recess 6 is a cylindrical guide rod 7. Surrounding the guide rod 7 is a first upwardly movable plunger element 8. This plunger element 8 has a size and configuration equivalent to that of the housing 3 associated with the air-bag.

Surrounding the plunger element 8 is a second plunger member 9 which extends, from the outer part of the plunger element 8 to the periphery of the rectangular recess 6.

Mechanisms, not shown, are provided for moving the plungers upwardly from an initial lowered position, as shown in Figure 2. The plungers are movable independently of each other. However, in the initial position as shown in Figure 2, the plungers are co-aligned and define the bottom of the recess 6.

Provided adjacent the upper edge of the recess 6, at two opposed ends thereof, are opposed horizontally movable plungers 10,11. The plungers 10,11 are adapted to move horizontally towards the central guide rod 7. The horizontally movable plungers 10,11 have a width W equal to the width W of the recess 6.

Mounted above the horizontal plungers 10,11 are a pair of slidably mounted closure panels 12,13 which are also movable towards the centre of the upper part of the recess 6.

The closure panels 12,13 each have a width which is slightly greater than the width W of the recess 6. The closure panels are movable from a first position, in which the upper part of the recess 6 is open, to a closed position in which the closure panels extend over the upper part of the recess.

In an initial stage in the folding of an air-bag, as shown in Figure 2, the air-bag 2, depending from the housing 3, is suspended above the cavity 6. The housing 3 is carried by a support fixture 14 carried on a support arm 15. The air-bag 2 comprises two super- imposed layers of fabric, and the air-bag is located so that the two layers of fabric extend generally axially relative to the recess 6. An operator may tease out the air-bag slightly while it is suspended above the cavity 6 so that the air-bag presents a flat under-surface which, when the air-bag is lowered (as will be described hereinafter), rests on the flat upper part of the guide rod 7. Thus, a single layer of fabric rests on the guide rod, with a"skirt" of teased out air-bag falling into the recess.

Subsequently, as shown in Figure 3, the housing 3 is lowered, by lowering the support arm 15 so that the air-bag 2 falls into the cavity 6 with the central lower part of the air-bag being supported on top of the guide rod 7. Thus, the housing 3 is lowered to such an extent that the under-surface of the gas generator 4 is located immediately above the upper part of the guide rod 7, being separated therefrom by part of the fabric forming the bag 2. The part of the fabric that separates the gas generator and the upper part of the guide rod is a single layer of fabric and part of the air-bag which, when the air-bag is fully inflated at a position spaced away from the gas generator. Thus part of the air-bag 2 lies at a predetermined position relative to the housing 3. The rest of the bag falls in loose folds into the recess 6.

Subsequently, the slidable closure panels 12,13 are moved inwardly until they substantially touch the exterior of the housing 3, as shown in Figure 4.

Both of the plunger members 8 and 9 that form the base of the recess 6 are then moved upwardly in synchronism towards the originally open part of the recess applying a first compressing force to the air-bag. The loose folds of the bag are thus scrunched upwardly. Because in the bag is in loose folds, and not lying flat, each of the two layers of fabric is scrunched independently of the other layer, and thus a large number of fold-lines are formed in one layer of fabric which are not aligned with fold-lines in the other layer of fabric.

The two plunger members 8,9, continue to move upwardly, applying the first compressing force to the air-bag along a first vertical axis with a resultant scrunching of the air-bag 2, along the first vertical axis until the upper surfaces of the plunger members are substantially aligned with the lower surface of the opposed horizontally moving plungers 10,11. This is the condition of the apparatus shown in Figure 6. The horizontally moving plungers 10,11 then move inwardly towards each other, applying a second compressing force perpendicular to the first compressing force, crumpling or scrunching the fabric of the air-bags along a second horizontal axis, which is perpendicular to the first vertical axis.

The horizontally moving plungers 10,11 move inwardly until they are substantially aligned with the end walls of the housing 3. The air-bag 2 is thus crumpled or scrunched into a relatively small volume.

After folding the air-bag is packaged in the housing 3. The central plunger member 8 is moved upwardly, parallel to the first compressive force, inserting the folded air-bag into the housing 3. The air-bag is retained within the housing 3 by frictional forces, at least for a period long enough to enable the housing 3 to be raised by raising the support arm 15, and for a retaining cover to be snapped, or otherwise mounted in position, on the housing.

The assembled unit, comprising the air-bag in its housing, is then removed from the support fixture 14.

Figure 9 shows a modified embodiment in which the central guide rod 7 is replaced by a central axially extending vertical guide wall 16 which is located in the recess 6. The plunger element 8 in this embodiment is formed of two plunger components, one on each side of the wall 16. Also the plunger element 9 is formed from two plunger components, one on each side of the wall. the wall is shown having a central raised part 17. In other respects the apparatus of Figure 9 is the same as that of Figure 1.

In use of the apparatus shown in Figure 9 the air-bag is initially lowered, as previously described, into the recess 6 with parts of the air-bag 2 on each side of the wall 16. A single layer of fabric rests on the central raised part 17 of the wall 16. The housing 3 is lowered so that this single layer of fabric is trapped between the raised part 7 of the wall 16 and the gas generator 4. The folding packaging process then continues as described above with reference to Figures 2 to 8.

It is to be appreciated that by using the method described above, the air-bag is initially scrunched with a force applied along a first axis to loose folds of air-bag when the air-bag is in an initial condition, and is subsequently scrunched or crumpled to the compressive force that is applied along an axis which is transverse to the first axis. This crumpling of the air-bag where force is applied in two orthogonal directions tends to ensure that throughout all areas of the air-bag fold patterns exist that permit the flow of gas. Thus, on inflation of the air-bag, the air-bag may inflate more uniformly than has hereto for been the case.

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

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.