WO2008054266A1

WO2008054266A1 - An air-bag arrangement

Info

Publication number: WO2008054266A1
Application number: PCT/SE2006/001239
Authority: WO
Inventors: Laurent Hellot; Adam Machnik
Original assignee: Autoliv Development Ab
Priority date: 2006-11-02
Filing date: 2006-11-02
Publication date: 2008-05-08

Abstract

An air-bag arrangement (1) which comprises a housing (9) which houses an air-bag (10). The air-bag (10) has an inlet (21) and a body-contacting portion (28). A restriction arrangement (29) is attached to the air-bag (10) at a location between the inlet (21) and the body-contacting portion (28) to restrict the cross-section of the air-bag (10). The arrangement is configured so that, following normal inflation of the air-bag (1), a first part of the restriction arrangement (29) is positioned inside the housing (9) and a second part of the restriction arrangement (29) is positioned outside the housing (9).

Description

AN AIR-BAG ARRANGEMENT

Description of Invention

THE PRESENT INVENTION relates to an air-bag arrangement, and more particularly relates to an air-bag arrangement to be installed in a motor vehicle to protect an occupant of the vehicle in the event that an accident situation occurs.

Conventional air-bag arrangements usually comprise an air-bag which is folded initially within a housing and configured to inflate outwardly from the housing in the event that an accident situation occurs. It is desirable for the housing to be as small as possible so that the housing occupies as little space as possible within a motor vehicle.

A small housing is especially important in the case of an overhead air-bag arrangement in which the housing is to be mounted to the interior of the roof of a motor vehicle so as to be above and in front of an occupant of the vehicle. The housing of an overhead air-bag arrangement must be as thin as possible so that the housing does not obstruct the vision of the occupant.

As the size of an air-bag housing is reduced there is an increase in the possibility of the housing becoming deformed by the air-bag as the air-bag inflates, resulting in bell-mouthing of an opening in the housing from which the air-bag protrudes as it inflates. Such deformation of the housing is undesirable because it can increase the thickness of the housing which can make the housing more likely to be struck by the head of a tall occupant in the event of an accident situation. The present invention seeks to provide an improved air-bag arrangement.

According to the present invention, there is provided an air-bag arrangement comprising a housing which houses at least part of an air-bag, the air-bag having a body-contacting portion configured to be contacted by the body of a vehicle occupant during use, and being configured to be inflated by a source of gas so that gas is introduced into an interior of the air-bag via an inlet and part of the air-bag moves outwardly from the housing, wherein the arrangement further comprises a restriction arrangement which reduces the cross-section of the air-bag when inflated and is attached to the air-bag at a location between the inlet and the body-contacting portion, the arrangement being configured so that, following normal inflation of the air-bag a first part of the restriction arrangement is positioned inside the housing and a second part of the restriction arrangement is positioned outside the housing.

Preferably the air-bag comprises a first portion and a second portion which are interconnected by an elongate connecting portion, the first portion being fixed within the housing and the second portion defining the body contacting portion, the restriction arrangement being provided at the connecting portion.

Conveniently the connecting portion) is formed integrally with the first portion and the second portion.

Advantageously the restriction arrangement extends along substantially the entire length of the connecting portion to increase the rigidity of the connecting portion.

Preferably the restriction arrangement extends around substantially the entire periphery of the connecting portion to increase the rigidity of the connecting portion. Conveniently the restriction arrangement comprises stitching applied to the air- bag.

Advantageously the restriction arrangement comprises adhesive applied to the air-ba.

Preferably the restriction arrangement comprises at least one tether which is attached to the air-bag.

Conveniently the housing comprises an upper panel) which is spaced apart from a lower panel, the upper panel carrying at least one mounting element for mounting the housing to the roof of a motor vehicle, the upper panel and the lower panel being interconnected by at least one side wall) which is configured to provide an opening out of which the body contacting part of the air-bag can move when the air-bag is inflated.

Advantageously the at least one side wall incorporates at least one line of mechanical weakness which is configured to be ruptured by the air-bag as the air-bag inflates to provides the opening in the housing.

Preferably the arrangement further comprises a cover element which at least partly covers the part of the air-bag which is housed within the housing to retain the part of the air-bag in a desired position within the housing.

In order 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 diagrammatic view of an air-bag arrangement in accordance with a preferred embodiment of the invention, installed in a motor vehicle and in an unactuated condition, FIGURE 2 is a diagrammatic sectional view of the air-bag arrangement of Figure 1 ,

FIGURE 3 is a diagrammatic perspective view of components of the air-bag arrangement of Figure 1 ,

FIGURE 4 is a view corresponding to Figure 2, showing part of the air-bag arrangement in an actuated condition, and

FIGURE 5 is a view corresponding to Figure 1 with the air-bag arrangement in an actuated condition.

Referring initially to Figure 1 , an air-bag arrangement 1 in accordance with a preferred embodiment of the invention is installed in a motor vehicle 2. The air-bag arrangement 1 is mounted to the roof 3 of the vehicle 2 adjacent the upper part of the windscreen 4 of the vehicle 2. The air-bag arrangement 1 is positioned so as to be above and in front of an occupant 5 who is seated in the vehicle 2. It is to be appreciated that the air-bag arrangement 1 of this preferred embodiment is an overhead air-bag arrangement which is mounted in the vehicle 2 to protect the occupant 5 in the event that the vehicle 2 is involved in an accident.

An actuation arrangement 6 is connected to the air-bag arrangement 1 to supply an actuating signal to the air-bag arrangement 1 in the event that an accident situation occurs. The actuation arrangement 6 incorporates a crash sensor 7 which is installed within the vehicle 2 to sense a crash situation or anticipated crash and to supply a crash signal to a control unit 8. The control unit 8 processes the crash signal and determines whether it is appropriate to actuate the air-bag arrangement. If the control unit 8 determines that it is appropriate to actuate the air-bag arrangement 1 , the control unit 8 transmits an actuation signal to the air-bag arrangement 1 to actuate the air-bag arrangement 1 to protect the occupant 5.

It is to be appreciated that, whilst the actuation arrangement 6 described above incorporates only one accident sensor and one control unit, other embodiments may incorporate more complex actuation arrangements with a greater number of sensors and/or control units.

Referring now to Figures 2 and 3, the air-bag arrangement 1 comprises a housing 9 which houses an air-bag 10 that is folded initially within the housing 9. It is to be understood that, for the purposes of explanation, Figure 2 does not show the air-bag 10 to be folded.

The housing 9 is of generally elongate rectangular cross-section and comprises an upper panel 11 which is superimposed and spaced apart from a lower panel 12. The upper panel 11 and the lower panel 12 are interconnected by a front side wall 13, a rear side wall 14 and left and right side walls (not shown). The upper panel 11 carries four mounting elements in the form of bolts 15 (only two of which can be seen in Figure 2) to mount the housing 9 to the roof 3 of the vehicle 2.

A line of mechanical weakness 16 is formed down each side and along the lower edge of the front side wall 13 of the housing 9. As will become clear from the description below, the line of mechanical weakness 16 is configured to be ruptured by the air-bag 10 when the air-bag 10 is inflated to provide an opening in the housing 9 out of which part of the air-bag 10 can protrude.

The rear side wall 14 of the housing 9 incorporates an aperture 17 and a source of gas in the form of a gas generator 18 is held within a holder 19. The holder 19 is mounted to the rear side wall 14 so that gas from the gas generator 18 can pass through the aperture 17 and into the air-bag 10. A first portion 20 of the air-bag 10 which incorporates an inlet 21 is fixed to the rear side wall 14 by a diffuser plate 22 so that the inlet 21 is aligned with the aperture 17 in the rear side wall 14. The diffuser plate 22 is positioned within the first portion 20 of the air-bag 10 and is mounted by lugs 23 to the rear side wall 14. Material surrounding the inlet 21 of the air-bag 10 is trapped between the diffuser plate 22 and the rear side wall 14 to form a substantially gas tight seal and to attach the air-bag 10 to the rear side wall 14.

A central part of the diffuser plate 22 which is of a shape corresponding to the shape of the aperture 17 is provided with a plurality of small diffusion apertures 24. As will become clear from the description below, upon actuation of the gas generator 18, gas passes from the gas generator 18 through the diffusion apertures 24 and into the interior of the air-bag 10 to inflate the air- bag 10.

An air-bag cover 25, which defines a cover element in the form of a sheet of material, covers the air-bag 10 and is fixed to the rear side wall 14 by being trapped between the diffuser plate 22 and the rear side wall 14. The function of the air-bag cover 25 is to retain the folded air-bag 10 in a desired position within the housing 9. The air-bag cover 25 is provided with a split line 26 at a position which is adjacent the front side wall 13 of the housing 9. As will become clear from the description below, the air-bag cover 25 is configured to split along the split line 26 when the air-bag 10 is inflated.

The air-bag 10 incorporates a connecting portion 27 which connects the first portion 20 of the air-bag 10 with a second portion 28 of the air-bag 10. In this preferred embodiment the first and second portions 20,28 and the connecting portion 27 are formed integrally with one another. It is to be understood that the second portion 28 defines the main bulk of the air-bag 10 which, upon actuation of the arrangement, inflates out from the housing 9 and which has a body-contacting portion which is configured to be contacted by the occupant 5. The connecting portion 27 is reinforced by stitching 29 which is applied to the air-bag 10 and which extends substantially along the entire length of the connecting portion 27 and substantially around the entire periphery of the connecting portion 27. The stitching 29 defines a restriction arrangement which is attached to the air-bag 10 at a location between the inlet 21 and the body-contacting portion to reduce the cross-section of the air-bag 10 when the air-bag 10 is inflated.

In the event that the air-bag arrangement 1 is actuated, the gas generator 18 generates gas which is injected through the diffuser plate 22 into the air- bag 10. As gas is injected into the air-bag 10, the air-bag expands and exerts a force on the cover 25 and the walls of the housing 9. The force exerted by the air-bag 10 causes the split line 26 in the cover 25 to split and also the line of mechanical weakness 16 in the front side wall 13 of the housing 9 to rupture. Once the line of mechanical weakness 16 has ruptured, the front side wall 13 of the housing 9 pivots outwardly about its upper edge to provide an opening in the housing 9 out of which the second portion 28 of the air-bag 10 inflates, as shown in Figure 4. The second portion 28 of the air-bag 10 thus inflates outwardly from the side of the housing 9 in a direction towards the windscreen 4 of the vehicle. The second portion 28 contacts the windscreen 4 and continues to inflate into the vehicle to a position in front of the occupant 5 so that the second portion 28 may be contacted by the occupant 5 to cushion the occupant 5, as shown in Figure 5.

It is to be appreciated that, during normal inflation of air-bag 10, a first part of the connecting portion 27 is positioned inside the housing 9 and a second part of the connecting portion 27 is positioned outside the housing 9. The connecting portion 27 thus defines a part of the air-bag 10 which protrudes out of the opening provided in the housing as the air-bag 10 inflates. The connecting portion 27 incorporates the restriction arrangement in the form of the stitching 29 and thus, following normal inflation of the air-bag 10, a first part of the restriction arrangement is positioned inside the housing 9 and a second part of the restriction arrangement is positioned outside the housing 9.

The stitching 29 applied to the connecting portion 27 restricts the expansion of the connecting portion 27 and thus reduces the cross-section of the connecting portion 27 when the air-bag 10 is inflated. The stitching 29 restricts the cross-section of the connecting portion 27 to a diameter which is less than the size of the opening provided in the housing 9 through which the connecting portion 27 protrudes as the air-bag 10 inflates. The stitching 29 thus prevents the connecting portion 27 from expanding and exerting a force on the housing

9 around the opening which might otherwise deform the opening to result in bell-mouthing.

The reduced cross-section of the connecting portion 27 reduces the size of the connecting portion 27 which results in the connecting portion 27 defining a relatively thin elongate part of the air-bag 10. The connecting portion 27 is the part of the air-bag 1 which will be close to the head of a tall occupant 5, and minimising the inflated size of the connecting portion 27 reduces the risk of the head of a tall occupant 5 contacting the connecting portion 27 before the second portion 28 has inflated fully. The chances of the head or neck of a tall occupant 5 being injured as a result of the head of the occupant 5 contacting part of the air-bag 10 before the body contacting portion of the air-bag 10 are thus minimised.

In addition to reducing the cross-section of the connecting portion 27 the stitching 29 also serves to increase the rigidity of the connecting portion 27. The increased rigidity of the connection portion 27 allows the connecting portion 27 to act as a support which supports the second portion 28 of the air- bag 10 as it inflates.

Whilst in the embodiment described above, the air-bag 10 has a first portion 20 positioned between the inlet 21 and the connecting portion 27, in other embodiments the inlet 21 is defined by an opening in the end of the connecting portion 27. In such embodiments, the restriction arrangement which may be stitching 29 applied to the connecting portion 27 is still attached to the air-bag at a location between the inlet 21 and the second portion 28 which defines a body contacting portion of the air-bag 10. A first part of the restriction arrangement is thus still positioned inside the housing 9 and a second part of the restriction arrangement is still positioned outside the housing 9 following normal inflation of the air-bag.

Whilst in the embodiment described above the first portion 20, the connection portion 27 and the second portion 28 are formed integrally with one another, in other embodiments the portions 20,27,28 of the air-bag 10 may be separate portions which are attached to one another, for instance by stitching.

Whilst in the embodiment described above, the restriction arrangement is in the form of stitching applied to the air-bag 10, in further embodiments the restriction arrangement may comprise stitching and/or adhesive applied to the air-bag and/or one or more tethers which are attached to the air-bag 10.

Whilst in the embodiment described above, the air-bag 10 is retained in position within the housing 9 by the cover 25, in other embodiments the cover 25 may be omitted.

Whilst the air-bag arrangement 1 of the preferred embodiment described above is an overhead air-bag arrangement, in other embodiments the air-bag arrangement may be a different type of air-bag arrangement, for instance a front or side air-bag arrangement.

When used in this specification and claims, the terms "comprises" and "comprising" and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or components.

Claims

1. An air-bag arrangement comprising a housing (9) which houses at least part of an air-bag (10), the air-bag (10) having a body-contacting portion (28) configured to be contacted by the body of a vehicle occupant (5) during use, and being configured to be inflated by a source of gas (18) so that gas is introduced into an interior of the air-bag (10) via an inlet (21 ) and part of the air-bag (10) moves outwardly from the housing (9), characterised in that the arrangement further comprises a restriction arrangement (29) which reduces the cross-section of the air-bag (10) when inflated and is attached to the air- bag (10) at a location between the inlet (21 ) and the body-contacting portion (28), the arrangement being configured so that, following normal inflation of the air-bag (10) a first part of the restriction arrangement (29) is positioned inside the housing (9) and a second part of the restriction arrangement (29) is positioned outside the housing (9).

2. An air-bag arrangement according to claim 1 , wherein the air-bag (10) comprises a first portion (20) and a second portion (28) which are interconnected by an elongate connecting portion (27), the first portion (20) being fixed within the housing (9) and the second portion (28) defining the body contacting portion, the restriction arrangement (29) being provided at the connecting portion.

3. An air-bag arrangement according to claim 2, wherein the connecting portion (27) is formed integrally with the first portion (20) and the second portion (28).

4. An air-bag arrangement according to claim 2 or 3, wherein the restriction arrangement (29) extends along substantially the entire length of the connecting portion (27) to increase the rigidity of the connecting portion (27).

5. An air-bag arrangement according to any one of claims 2 to 4, wherein the restriction arrangement (29) extends around substantially the entire periphery of the connecting portion (27) to increase the rigidity of the connecting portion (27).

6. An air-bag arrangement according to any one of the preceding claims, wherein the restriction arrangement (29) comprises stitching applied to the air- bag (10).

7. An air-bag arrangement according to any one of the preceding claims, wherein the restriction arrangement (29) comprises adhesive applied to the air-bag (10).

8. An air-bag arrangement according to any one of the preceding claims, wherein the restriction arrangement (29) comprises at least one tether which is attached to the air-bag (10).

9. An air-bag arrangement according to any one of the preceding claims, wherein the housing (9) comprises an upper panel (11 ) which is spaced apart from a lower panel (12), the upper panel (11) carrying at least one mounting element (15) for mounting the housing (9) to the roof (3) of a motor vehicle, the upper panel (11) and the lower panel (12) being interconnected by at least one side wall (14) which is configured to provide an opening out of which the body contacting part (28) of the air-bag (10) can move when the air-bag (10) is inflated.

10. An air-bag arrangement according to claim 9, wherein the at least one side wall (14) incorporates at least one line of mechanical weakness (16) which is configured to be ruptured by the air-bag (10) as the air-bag (10) inflates to provides the opening in the housing (9).

11. An air-bag arrangement according to any one of the preceding claims, wherein the arrangement further comprises a cover element (25) which at least partly covers the part of the air-bag (10) which is housed within the housing (9) to retain the part of the air-bag (10) in a desired position within the housing (9).