WO2002055344A1

WO2002055344A1 - A method of and apparatus for folding an air-bag

Info

Publication number: WO2002055344A1
Application number: PCT/SE2001/002871
Authority: WO
Inventors: Michel Moreau; Jérôme WITTER; Jörgen Persson
Original assignee: Autoliv Development Ab
Priority date: 2001-01-12
Filing date: 2001-12-21
Publication date: 2002-07-18
Also published as: GB0100917D0; GB2371025A; GB2371025B

Abstract

A method of folding an air-bag (1) comprising the steps of retaining a first part (9) of the air-bag (1), grabbing a second part (2) of the air-bag (1) and separating the retaining part (9) of the air-bag (1) and the grabbed part (2) of the air-bag (1) so that the air-bag (1) extends substantially vertically upwardly within a retaining element (60), subsequently releasing the grabber (61) from the air-bag (1) to permit the air-bag (1) to fall and pressing the air-bag (1) downwardly within the retaining element (60) to form a folded air-bag (1) having a plurality of separate crumpled and folded air-bag as a package.

Description

"AMETHOD OFANDAPPARATUS FORFOLDING ANAIR-BAG"

THE PRESENT INVENTION relates to a method of and apparatus for folding an air-bag, such as an air-bag intended for use to provide protection for an occupant of a motor vehicle in the event that an accident should arise.

It has been proposed previously to provide an air-bag mounted in a motor vehicle, the air-bag being adapted to be inflated in the event that an accident should occur, the inflated air-bag being located in front of an occupant of the vehicle in order to provide protection for that vehicle occupant.

A conventional air-bag comprises a fabric bag which is initially stored within a housing. Typically the air-bag is initially laid out substantially flat, with two superimposed layers of fabric lying immediately adjacent each other, and then the air-bag is folded to be inserted into the housing. In a conventional folding technique, the two layers of fabric are folded together simultaneously about a single fold-line when each fold is created. This has the effect of creating, within the air-bag, regions where no gas may flow since the simultaneous fold of two adjacent layers of fabric is such that no gas may flow past the fold. This may be undesirable, in that the air-bag may possess an undesirable inflation characteristic.

It is now proposed, therefore, to fold an air-bag into such a way that the different layers of fabric are folded or crumpled, the layers preferably being folded or crumpled at different locations, so that there is an air-flow through the entire air-bag during initial inflation thereof.

When an air-bag is folded it is necessary to retain the folded air-bag within some sort of package.

The present invention seeks to provide a method of and apparatus for folding an air-bag.

According to one aspect of this invention there is provided a method of folding an air-bag comprising the steps of retaining a first part of the air-bag, grabbing a second part of the air-bag and separating the retaining part of the air-bag and the grabbed part of the air-bag so that the air-bag extends substantially vertically upwardly within a retaining element, subsequently releasing the grabber from the air-bag to permit the air-bag to fall and pressing the air-bag downwardly within the retaining element to form a folded air-bag having a plurality of separate crumpled folds, the method comprising the subsequent step of securing the crumpled and folded air-bag as a package.

Preferably the air-bag is initially folded substantially flat on a table, part of the air-bag connected to the gas generator retained in position by engaging the gas generator. Conveniently the retaining element is in the form of a chimney, and wherein a recess is provided, into which the air-bag is to be compressed, the chimney being aligned with the recess.

Advantageously, in a compression step, the air-bag is pressed downwardly through the chimney into the recess by a compressor which compresses the crumple-folded air-bag.

Conveniently following the compression step, the retaining elements are moved from an initial position adjacent the recess to a position at least partially overlying the recess to retain the air-bag in the compressed state.

Preferably as the said elements are moved inwardly, so retaining straps initially secured to the air-bag are moved to a position in which they at least partially embrace the compressed crumple-folded air-bag.

Conveniently the step of securing the crumpled and folded air-bag as a package comprises the step of effecting relative movement between the air-bag an elongate securing strap, one end of which is secured to the air-bag, so that the elongate securing element surrounds the air-bag to retain the air-bag in a compressed crumple-folded state.

Advantageously the elongate securing element is in the form of a strap provided with means adapted to engage projections provided on the gas generator to secure the elongate element to the gas generator.

According to another aspect of this invention there is provided a method of folding an air-bag, the method comprising the steps of providing an air-bag having two elongate securing flaps, each secured, at one end, to the fabric of the bag, folding the bag in a recess, with the securing flaps extending adjacent side walls of the recess extending beyond the side walls out of the recess, moving elements into engagement with the projecting parts of the securing flaps to move the securing flaps across the top of the folded bag within the recess, and subsequently securing the folding flaps in position.

Preferably the step of securing the folding straps in position is achieved by wrapping an elongate securing element around the package.

Advantageously the folded air-bag is compressed into the recess and is retained in the recess by elements which move from an initial position located to the side of the recess to a position in which the elements extend at least partially across the top of the recess, these elements being the elements which engage the projecting parts of the securing flaps to move the securing flaps across the top of the folded bag.

Conveniently a relative movement is effected between the air-bag and the elongate securing element so that the elongate securing element is wrapped around the folded air-bag passing across the ends of the securing flaps to retain the securing flaps in position, with the end of the elongate securing element being secured to part of the folded air-bag.

Preferably the end of the elongate securing element is secured to the gas generator of the air-bag.

Advantageously the relative movement between the air-bag and the elongate securing element is effected by rotating the recess, in which the air- bag has been folded and compressed, in a rotational manner. The invention also relates to an apparatus for performing a method as described above, the apparatus including a grabbing mechanism and a retaining element, and also a compressing element for pressing the air-bag downwardly within the retaining element.

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 plan view, with parts shown in phantom, of an air-bag to be folded by the method of, and with the apparatus of, the invention,

FIGURE 2 is a side sectional view illustrating an apparatus for use in performing the method of the invention, with the apparatus in a first state,

FIGURE 3 is a view corresponding to Figure 2, but taken orthogonally to the view of Figure 2,

FIGURE 4 is a view corresponding to Figure 2 showing a subsequent stage in the method of the invention,

FIGURE 5 is a view corresponding to Figure 4 showing a subsequent stage in the method of the invention,

FIGURE 6 is a view corresponding to Figure 5 showing a subsequent stage in the method of the invention, FIGURE 7 is an enlarged view of part of the view of Figure 6,

FIGURE 8 is a view corresponding to Figure 6 showing a subsequent stage in the method of the invention,

FIGURE 9 is a view corresponding to Figure 8 showing a subsequent stage in the method of the invention,

FIGURE 10 is a view showing the folded and packaged air-bag when prepared by the method described with reference to Figures 1 to 10, and

FIGURE 11 is an underneath view of the package of Figure 10.

Referring initially to Figure 1 of the accompanying drawings, an air-bag, to be folded, is a conventional substantially circular air-bag 1 comprising an upper layer of fabric 2 and a lower layer of fabric 3. The lower layer of fabric is provided with a substantially cylindrical aperture adapted to be connected to a gas generator 4. The gas generator has two projecting pegs - not shown in Figure 1. The lower layer of fabric is provided, at diametrically opposed positions relative to the gas generator 4, with two securing flaps 5, 6. Each securing flap has the end thereof closest to the gas generator 4 stitched, by stitching 7, 8, to the lower layer of fabric 3. Extending perpendicularly to a notional line joining the flaps 5 and 6, there is a further securing strap 9. The strap 9 is of elongate form and has one end 10 stitched to the lower fabric layer 3 of the bag 1. The strap 9 is of elongate form thus being longer than the flaps 5 or 6, and at its free end is provided with two apertures 11 adapted to engage the pegs of the gas generator. Figure 2 illustrates components of an apparatus 20 for use in folding the air-bag.

The apparatus 20 comprises a base 21. At one end of the base there is an upstanding arm 22 and provided, at the upper end of the upstanding arm 22 is a bearing 23 which supports a horizontally extending shaft 24. The inner end of the shaft 24 engages a support frame 25. The part of the shaft extending beyond the bearing 23 away from the base 21 carries a pulley wheel 26 which is associated with a pulley drive-belt 26.

At the other end of the base 21 there is a second upstanding arm 27 corresponding with the arm 22. The arm 27 has a bearing 28 supporting a shaft 29 associated with a pulley 30 which is engaged by pulley drive-belt. The inner end of the shaft 29 engages the support frame 25. It is to be appreciated, therefore, that the support frame 25 is mounted for rotation about a horizontal axis defined by the co-aligned shafts 24, 29. The pulley drive-belts may be driven appropriately to effect this rotation.

The support frame 25 is initially in the position illustrated in Figure 2. The support frame 25 is in the form of a tray having a base 31 with upstanding end walls 32, 33. The upstanding end walls are the parts of the tray engaged by the shafts 24 and 29.

The base 31 of the tray is provided with a plurality of apertures, such as the aperture 34. Located beneath each aperture 34 and supported beneath the base 31 of the tray 25 is a housing 35. Each housing 35 contains a cylinder 36 which contains a piston, the piston being associated with a plunger 37 which extends upwardly above the housing. Each plunger may be driven to extend from the housing 35 as will be described hereinafter.

The base 31 of the tray 25 is provided with a relatively large central aperture 38, this central aperture 38 being surrounded by a plurality of the above-described apertures 34 each associated with a respective housing 35, and with a respective piston, cylinder and plunger combination.

The plungers 37 serve to support an inner tray 40 which is received within the tray 25. The inner tray 40 has a base 41 that is secured fast to the plungers 37 so that the tray 40 can be moved in synchronism with the plungers. The tray is provided with upstanding end walls 42, 43.

The central region of the inner tray is provided with further upstanding inner walls 44, 45 which define between them a chamber 46 into which an air- bag 1 is to be folded.

The chamber 46 is provided with an aperture 47 in its base, that aperture being aligned with the aperture 38 formed in the base 31 of the tray 25.

The base 21, which supports the described apparatus, is provided with a central aperture 50, and mounted beneath the aperture 50 is a housing 51 containing a cylinder and piston arrangement, the cylinder and piston supporting a plunger 52, the plunger 52 carrying a grabber element 53 adapted to grab the two pegs provided on the gas generator 4 of the air-bag to be folded, and a support 54 defining, in its upper region, a recess adapted to receive the gas generator 4. The upper part of the support, which defines the recess, also defines an aperture extending into the hollow centre of the support 54. The pegs provided on the gas generator 4, which are grabbed by the grabber 53, extend through the aperture in the support 54 into the hollow interior of the support, and the grabber 53 is located within the hollow interior of the support 54.

Mounted on each end wall 42, 43 of the inner tray 40 is a cylinder, such as the cylinder 55. The cylinder is mounted to extend horizontally. Contained within the cylinder is a piston which is associated with a plunger 56 which extends from the housing 55. The upper side of the plunger 56 supports a plate or sheet 57 which is located at a level just above the top of the adjacent end wall 42, and just above the top of the inner wall 44 that forms part of the boundary of the chamber 46. The metal sheet 57 may be moved, on operation of the piston and cylinder arrangement, from an initial position, as shown, in which the plate extends from the end wall 42 to the inner wall 44, to a position in which part of the plate is moved to extend over the inner wall 44, so that part of the plate extends over the inner chamber 46.

It is to be appreciated that the plurality of the described piston and cylinder arrangements 55, 56, and associated sheets 57 are provided at positions spaced radially about the folding cavity 46. The combination of the plates thus presents a substantially horizontal table surrounding the cavity 46. Received within the cavity 46, in an initial position of the apparatus as shown in Figure 2, is the support 54. An air-bag, such as the air-bag 1 described in Figure 1, is located in position with the gas generator 4 being received on the support 54, with the peg on the gas generator passing through an aperture in the support 54 to be grabbed by the grabber 53 within the hollow interior of the support 54. The air-bag 1 may be spread out on the table constituted by the sheets 57.

As shown in Figure 3, a grabber 58 may be provided substantially in alignment with the plates 57, the grabber engaging the free end of the long fixing strap 9. The grabber applies a horizontal tension to the fixing strap 9 so that the strap 9 extends substantially horizontally.

Referring again to Figure 2 located above the previously described components of the apparatus are a generally cylindrical chimney 60, of circular cross-section, adapted to be moved upwardly and downwardly in a vertical sense, and a grabber 61 illustrated within the chimney which also is adapted to move upwardly and downwardly. It is to be appreciated that the chimney 60 could also be of alternative cross-section, for example a quadrilateral cross- section. A further component is a compressor assembly 62 which, as will become clear from the following description, may be moved to be inserted into the chimney 60 in place of the grabber 61. The compressor assembly 62 comprises an outer generally cylindrical hollow housing 63 which is open at its lower end. Contained within the upper part of the housing 63 is a cylinder 64 having contained within it an associated piston. The piston is connected to a plunger assembly 65 which is provided at the lower end of the housing 63. The lower end of the housing 63 is provided with a plurality of axially extending slots 66. The upper edge of each slot 66 is provided with an inwardly directed chamfer 67. The plunger 65 carries a plurality of radially outwardly spring- biased shoes 68 each aligned with a respective slot 66. Each shoe is provided with a chamfered ramp 69 at its outer upper edge.

The plunger 65 is initially in a retracted position, as shown in Figure 2.

The folding apparatus 20 and the air-bag 1 to be folded have been described in the position that they will occupy at the commencement of a folding cycle. The first step in the folding operation (see Figure 4) is to lower the grabber 61 and cause the grabber 61 to grab a central part of the upper layer 2 of the fabric of the air-bag 1, with the grabber then being raised upwardly so as to pull the fabric of the air-bag upwardly. The fabric of the air-bag is thus pulled upwardly, and as a consequence the upper layer of fabric is separated from the lower layer of fabric. The securing strap 9 is held in the horizontal position by the tension applied to it by the grabber 58 as shown in Figure 3. The flaps 5 and 6 tend to occupy a flat position on the table.

During a subsequent step in the folding procedure, the chimney 60 is lowered from its initial elevated position past the grabber 61 until the lower edge of the chimney is substantially aligned with the top of the chamber 46 into which the air-bag is to be folded. The lower end of the chimney may be designed to be received as a sliding telescopic fit within the upper part of the chamber or, alternatively, the chimney may be adapted to abut the upper edges of the walls 44, 45 bounding the chamber. In any event, the chimney is substantially aligned with the chamber. Subsequently, (see Figure 6) the plungers 37 raise the inner tray 40 so that the upper surface of the support 54 becomes substantially aligned with the upper surface of the base 41 of the inner tray 40. Alternatively, the plunger 52, carrying the support and the grabber 53 may be lowered so that the upper surface of the support 54 becomes substantially aligned with the upper surface of the base 41 of the inner tray 40.

The chimney, in the illustrated embodiment, is lowered so that the lower part of the chimney is received within the chamber 46 into which the air-bag is to be folded. The fabric of the bag is released by the grabber 61, and thus the bag falls in loose folds downwardly within the chimney, with part of the bag forming a gently crumpled heap within the folding chamber 46 and the other part of the bag remaining within the chimney. The grabber 61 is then moved upwardly and laterally so that it is disengaged from the chimney, and the compressor assembly is moved laterally and vertically downwardly so that the compressor assembly is received within the chimney. As the compressor assembly moves downwardly, the compressor assembly begins to compress the loose crumpled folds of fabric. Subsequently the plunger 65 within the compressor assembly 62 is driven downwardly by the piston and cylinder arrangement 64. As the plunger 65 moves downwardly, so the spring-biased shoes 68 move radially outwardly into the slot 66. Thus, a downward pressure is applied to the loosely crumpled air-bag over virtually all of the cross-sectional area of the interior of the chimney. Thus the air-bag 1 is compressed, in a crumpled form, into the chamber 46.

Figure 7, which is an enlarged view of part of Figure 6, illustrates how the lower part of the chimney 60 is received within the chamber 46, but the folding flaps 5, 6, which were initially laid out substantially flat on the table constituted by the plates 57, as a consequence of the engagement between the lower end of the chimney 60 and the chamber 46, now extend across the base of the chamber 46, and up adjacent the side walls 44, 45, being trapped between those side walls and the lower part of the chimney 60. The free ends of the folding flaps 5, 6 extend out horizontally on top of the plates 57.

Subsequently, the chimney 60 and the compression assembly 62 are pulled up slightly so that the lower end of the chimney is disengaged with the chamber 46. The shoes 68 remain in their outer position to ensure that, during this upward movement, the compressor assembly 62 and the chimney 60 move upwardly together. As the compressor begins to move upwardly the plungers 56 are caused to move inwardly towards the recess 46, thus moving the plates 57 to a position in which the plates extend over the open top of the recess 46 to retain the air- bag in a compressed condition. As the plates move inwardly, the folding flaps 5 and 6 are moved inwardly so that the folding flaps 5 and 6 almost totally surround the folded and crumpled air-bag.

In a modified embodiment of the invention, the compressor presents a substantially "FT-shaped foot print which serves to compress the air-bag, and the plates that are moved inwardly by the pistons are adapted to move into the recesses defined on opposite sides of the cross-bar of the "H" between the side arms of the H. Thus the plates may be moved to a position in which they engage part of the air-bag before the compressor is removed, thus ensuring that the air-bag does not inadvertently become decompressed as the compressor is removed and before the plates have moved into position.

Returning to the description of the present embodiment the chimney and the compressor are then moved upwardly completely away from the inner tray.

The grabber 53 is then disengaged from the pegs provided on the gas generator 4 and the grabber 53, together with the support 54 are lowered away from the chamber 46.

The support frame 25, and, of course, the inner tray 40, are then rotated by 180° about the axis defined by the shafts 24, 29. Simultaneously the grabber 58, which is holding the strap 9, is caused to pay-out the strap or release the strap so that, as the table rotates, the strap 9 is substantially wound around the crumpled compressed air-bag with the inwardly folded flaps 5 and 6. The free end of the strap 9, provided with the apertures 11, is then engaged with the two pegs on the gas generator.

In the modified embodiment, in which the compressor has the "FT- shaped foot print, the strap 9 would pass between the inwardly directed plates, thus engaging the part of the compressed air-bag that was initially compressed by the "cross-bar" of the "H".

Finally the plates 57 may be withdrawn to their initial position by retracting the plungers 56 back into the housing 55, the support frame 25 and the inner tray may be rotated back to their initial position, and the complete package may then be removed from the apparatus 20.

It is to be understood that in the method described above, the fabric of an air-bag is pulled up the chimney and is then released and pressed down the chimney, thus ensuring a desired crumpling or scrunching of the fabric, so that the fabric of the bag is not folded with the great proportion of folds constituting a fold formed from two super-imposed layers of fabric folded simultaneously about immediately adjacent co-extensive fold-lines. Following the steps of pulling the fabric up the chimney and releasing the fabric compressing the fabric downwardly, the crumpled fabric is secured into a package.

In the described embodiment, it is to be understood that following the folding steps, two moveable elements move two folding flaps into position partially embracing the folded bag, and subsequently the folding flaps are secured in position. The folding flaps are secured in position by means of the securing strap which is wound around the package constituted by the folded bag and the inwardly directed folding flaps, with the free end of the securing strap itself being secured in position. Whilst reference has been made to the securing strap being held in position by engagement of apertures provided at the end of the strap with pegs provided on the gas generator, it is to be understood that elements of hook and loop material, such as that sold under the Registered Trade Mark VELCRO may be utilised instead.

Instead of having the gas generator provided with pegs, a separate holding plate or tube could be provided which carries the pegs.

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

Claims

CLAIMS:

1. A method of folding an air-bag comprising the steps of retaining a first part of the air-bag, grabbing a second part of the air-bag and separating the retained part of the air-bag and the grabbed part of the air-bag so that the air- bag extends substantially vertically upwardly within a retaining element, subsequently releasing the air-bag from the grabber to permit the air-bag to fall and pressing the air-bag downwardly within the retaining element to form a folded air-bag having a plurality of separate crumpled folds, the method comprising the subsequent step of securing the crumpled and folded air-bag as a package.

2. A method according to Claim 1 wherein the air-bag is initially folded substantially flat on a table, part of the air-bag connected to the gas generator retained in position by engaging the gas generator.

3. A method according to Claim 1 or Claim 2 wherein the retaining element is in the form of a chimney, and wherein a recess is provided, into which the air-bag is to be compressed, the chimney being aligned with the recess.

4. A method according to Claim 3 wherein, in a compression step, the air- bag is pressed downwardly through the chimney into the recess by a compressor which compresses the crumple-folded air-bag.

5. A method according to Claim 4 wherein following the compression step, the retaining elements are moved from an initial position adjacent the recess to a position at least partially overlying the recess to retain the air-bag in the compressed state.

6. A method according to Claim 5 wherein, as the said elements are moved inwardly, so retaining straps initially secured to the air-bag are moved to a position in which they at least partially embrace the compressed crumple-folded air-bag.

7. A method according to any one of the preceding Claims wherein the step of securing the crumpled and folded air-bag as a package comprises the step of effecting relative movement between the air-bag an elongate securing strap, one end of which is secured to the air-bag, so that the elongate securing element surrounds the air-bag to retain the air-bag in a compressed crumple-folded state.

8. A method according to Claim 7 wherein the elongate securing element is in the form of a strap provided with means adapted to engage projections provided on the gas generator to secure the elongate element to the gas generator.

9. A method of folding an air-bag, the method comprising the steps of providing an air-bag having two elongate securing flaps, each secured, at one end, to the fabric of the bag, folding the bag in a recess, with the securing flaps extending adjacent side walls of the recess extending beyond the side walls out of the recess, moving elements into engagement with the projecting parts of the securing flaps to move the securing flaps across the top of the folded bag within the recess, and subsequently securing the folding flaps in position.

10. A method according to Claim 9 wherein the step of securing the folding straps in position is achieved by wrapping an elongate securing element around the package.

11. A method according to Claim 9 or 10 wherein the folded air-bag is compressed into the recess and is retained in the recess by elements which move from an initial position located to the side of the recess to a position in which the elements extend at least partially across the top of the recess, these elements being the elements which engage the projecting parts of the securing flaps to move the securing flaps across the top of the folded bag.

12. A method according to Claim 11 wherein a relative movement is effected between the air-bag and the elongate securing element so that the elongate securing element is wrapped around the folded air-bag passing across the ends of the securing flaps to retain the securing flaps in position, with the end of the elongate securing element being secured to part of the folded air-bag.

13. A method according to Claim 12 wherein the end of the elongate securing element is secured to the gas generator of the air-bag.

14. A method according to any one of Claims 9 to 13 wherein the relative movement between the air-bag and the elongate securing element is effected by rotating the recess, in which the air-bag has been folded and compressed, in a rotational manner.

15. A method of folding an air-bag substantially as herein described with reference to and as shown in the accompanying drawings.

16. An apparatus for folding an air-bag according to any one of the preceding Claims, the apparatus comprising grabber means adapted to grab part of the air-bag, a retaining element, a compressing element adapted to press the air-bag downwardly within the retaining element and a mechanism for securing a crumpled and folded air-bag as a package.

17. An apparatus substantially as herein described with reference to and as shown in the accompanying drawings.