GB2273471A

GB2273471A - Vehicle air bag arrangements

Info

Publication number: GB2273471A
Application number: GB9226399A
Authority: GB
Inventors: Stefan Nordin; Matti Niemi
Original assignee: Autoliv Development AB
Current assignee: Autoliv Development AB
Priority date: 1992-12-18
Filing date: 1992-12-18
Publication date: 1994-06-22
Anticipated expiration: 2012-12-18
Also published as: GB2273471B; KR940014015A; KR100306498B1; GB9226399D0

Abstract

A housing defining a gas outlet aperture 5 is provided with a peripheral outwardly directed flange 4, and contains a gas generator 8. Located above the housing is an air-bag 26 contained within a space 27 defined by a cover 10. The cover has side wall portions 15, 17 carrying lower inwardly directed flanges 19, 21 which are located beneath the outwardly directed flanges 4 provided on the housing 1 and secured thereto. The cover may have at least two side wall portions (16, 17, Figure 1) which are pivotable outwardly to facilitate mounting of the cover on the housing. <IMAGE>

Description

DESCRIPTION OF INVENTION "IMPROVEMENTS IN OR RELATING TO AN AIR-BAG ARRANGEMENT" THE PRESENT INVENTION relates to an air-bag arrangement and more particularly relates to an air-bag arrangement intended for use in a vehicle such as a motor car.

It has been proposed to provide a so-called airbag in a motor vehicle, adapted to be inflated in the event that an accident should arise, the inflated bag providing a cushioning effect for the driver of the vehicle or a passenger in the vehicle.

Many of the so-called air-bags are actually inflated by igniting a pyrotechnic charge, present in a gas generator, the gases from the pyrotechnic charge passing through an aperture formed in the housing of the gas generator to the interior of the air-bag, which then inflates.

DE-2330194C discloses an air-bag arrangement of this type. The pyrotechnic charge is in the form of a tubular cartridge which is mounted in a housing which has a hollow interior which communicates with a large gas outlet aperture, of rectangular form, the gas outlet aperture being surrounded by an outwardly directed rectangular flange provided with spaced-apart apertures.

Part of the air-bag surrounding a gas inlet opening in the air-bag is trapped between the flange on the housing and a corresponding outwardly directed flange formed on a cover for the air-bag. The flange on the cover for the air-bag is provided with apertures which become aligned with the apertures in the flange on the housing, to receive bolts or the like.

The top wall of the cover is provided with a line of mechanical weakness so that, when the bag is inflated, the top wall of the cover splits along the line of mechanical weakness, the various parts of the cover then moving to an open position to permit the air-bag to become fully inflated. During this initial part of the inflation of the air-bag a significant force is applied to the cover tending to separate the flange on the cover from the flange on the housing. Consequently reinforcement of the flanges is necessary to ensure that the components of the cover do not become separated from the housing.It is to be understood that it is very undesirable for parts of the cover to become separated from the housing during inflation of the air-bag, since if parts of the cover do become separate from the housing under those circumstances, the parts of the cover may move, within the interior of the car, at a significant speed, which might cause injury to an occupant of the car.

The present invention seeks to provide an improved air-bag arrangement.

According to one aspect of this invention there is provided an air-bag unit comprising a housing incorporating a source of gas, and having a gas outlet opening provided with a peripheral outwardly directed flange, the air-bag unit further comprising an air-bag and a cover, the air-bag and the cover both being fixed, by means of the same fixing elements, to the flange provided on the housing, the cover being provided with side wall portions carrying inwardly directed flanges, the flange on the housing being located adjacent those parts of the flanges carried by the side walls of the cover which are directed inwardly towards the interior of the cover.

Since the flange on the housing is located adjacent those parts of the flanges carried by the side walls of the cover which are directed inwardly towards the interior of the cover, effectively the inwardly directed flanges are located on the exterior of the flange carried by the housing. Consequently the flanges are better able to withstand the force applied to the cover during initial inflation of the bag.

Preferably the side wall portions comprise separate portions which each move hingedly relative to a top wall of the cover. This arrangement facilitates the connection of the cover and housing. The side wall portions may be hinged in an outward manner, thus enabling the cover to be positioned with the flange on the housing effectively inside the cover. Subsequently, the side wall portions may be hinged back to their initial position, allowing the flange on the housing to be brought into the position adjacent those parts of the flanges carried by the side walls of the cover which are directed inwardly towards the interior of the cover.

Preferably the fixing elements comprise bolts passing through aligned apertures in the flange on the housing and the flanges on the side wall portions.

Alternatively the fixing elements comprise snaplocking pegs passing through aligned apertures in the flange on the housing and the flanges on the side wall portions.

Conveniently the fixing elements comprise a frame which engages the parts of the flanges carried by the side walls of the cover which are directed outwardly away from the interior of the cover.

Conveniently the frame is provided with apertures aligned with the apertures in the flanges. The bolts or the snap-locking pegs may pass through the apertures in the frame.

Preferably the frame has a peripheral upstanding lip which engages the lower parts of the side wall portions adjacent said inwardly directed flanges. The upstanding lip engages the lower parts of the side walls, thus preventing the side walls from inadvertently hinging outwardly.

Preferably a part of the air-bag surrounding a gas inlet is trapped between the outwardly directed flange and the inwardly directed flanges. The air-bag is thus securely mounted in position.

Conveniently the cover is provided with a line of mechanical weakness, comprising a portion of reduced thickness between a side wall portion and a top wall of the cover. The cover of the air-bag may thus hinge to an open position, minimising any risk of separate parts of the air-bag becoming separated.

Conveniently the side wall portions are of different height. This enables the air-bag unit to be designed so that it will fit within a motor vehicle dashboard.

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 an exploded view of the housing for a gas generator and a cover to co-operate with the housing, together with a fixing flange, these elements comprising components of an air-bag arrangement in accordance with the invention; FIGURE 2 is a longitudinal sectional view of the arrangement of Figure 1, illustrating the air-bag in position; FIGURE 3 is a partial view of a modified embodiment of the invention, corresponding to part of Figure 2, and FIGURE 4 is a sectional view, corresponding to Figure 2, but illustrating a modified embodiment of the invention.

Referring initially to Figure 1 a housing 1 is provided to receive a gas generator. The housing 1 is provided with two opposed "gable" ends, only one of which 2 is visible, the gable ends being inter-connected by means of a portion of channel-like form, of substantially "U" cross-section 3. A substantially rectangular flange 4 is provided which extends outwardly from the periphery of a rectangular gas outlet aperture 5 defined by the housing 1, the flange 5 being provided, at spaced intervals, with apertures 6 adapted to receive fastening elements that will be described in greater detail.

The gable end 2 is provided with a substantially circular aperture 7 through which a gas generator cartridge 8, of generally cylindrical form, may be inserted into the housing 1. The interior of the housing is provided with a mesh or screen 9 which serves to divide a lower part of the housing, which receives the cartridge 8, from an upper part of the housing which defines the aperture 9. The mesh or screen 9 is provided with apertures therethrough.

A cover 10 is provided adapted to co-operate with the housing 1. The cover 10 comprises a substantially rectangular, slightly arched top wall*11, which consists of a relatively hard inner layer of plastic material 12, which has an outer covering of a relatively soft plastic material 13, having an outer resilient skin 14. The hard portion 12 of the top wall of the cover provides it with strength, the soft layer 13 provides a certain amount of "yield" so that a person will not be injured if brought into contact with the cover, and the outer skin 14 provides durability. Depending from the under-surface of the top wall 11 of the cover are four side wall portions, only three of which 15,16,17 are visible in the drawings.

The fourth side wall portion is not visible but corresponds to the portion 16. Each side wall portion is separate from the remaining side wall portions. In other words there is no connection between the adjacent side wall portions in the region of each corner of the top wall 11. This is illustrated most clearly at the corner region 18 indicated in Figure 1.

Each side wall portion carries, at its lower edge, an inwardly directed flange 19,20,21, each such flange being provided with apertures adapted, as will become clearer from the following description, to be aligned with the apertures 6 provided in the flange 4.

At least two of the side wall portions 16,17 can hinge, at least to a limited extent, relative to the top wall 11.

A frame member 22 is provided. The frame member 22 is of rectangular form, defining a central rectangular aperture 23, which is dimensioned to receive the main part of the housing 1, so that the frame can lie adjacent the under-surface of the flange 4. The frame 22 is provided with apertures 24 corresponding to the apertures 6 in the flange 4. The frame 22 has a peripheral upstanding lips 25.

An air-bag is provided to be located within the space defined by the cover 10 and the space defined by that part of the housing 3 above the mesh 9. If reference is made to Figure 2 parts of the air-bag 26 are illustrated, comprising those parts adjacent the gas inlet to the air-bag. The air-bag is folded to fill substantially the shaded space 27 illustrated in Figure 2.

When the housing is being assembled, initially the air-bag 26 is positioned so that peripheral parts of the air-bag surrounding the gas inlet aperture to the air-bag 26 lie underneath the outwardly directed flange 4 when the housing is in the orientation illustrated in Figure 1, whilst the main part of the air-bag lies above the housing 3, or in that part of the housing 3 which lies above the mesh 9. The cover 10 is then mounted in position. At least the side wall portions 16 and 17 are moved hingedly outwardly to the position illustrated in solid lines in Figure 1.The cover 10 may then be manouvered so that the flange 19 carried by the side wall portion 15 lies underneath the appropriate part of the outwardly directed flange 4 carried by the housing 3, and the side wall portions 16 and 17 may then be moved hingedly back to a position in which the flanges 20 and 21 carried by those side wall portions also lie under the corresponding parts of the flange 4. Thus the side wall portion 17, for example, is moved from the position shown in solid line in Figure 1 to the position shown in dotted line in Figure 1 or, in other words, from the position shown in dotted lines in Figure 2 to the position shown in solid lines in Figure 1.

It is to be appreciated that the upwardly directed flange 4 provided on the housing 1 is then located adjacent those parts of the inwardly directed flanges 19,20,21 carried by the side wall portion 15,16,17 of the cover which are directed upwardly and inwardly towards the interior of the cover.

The frame 22 may be moved upwardly to the position illustrated in Figure 2, with the main part of the frame engaging the parts of the flanges 19,20,21 carried by the side wall portions 15,16,17 of the cover which are directed downwardly and outwardly away from the interior of the cover. The peripheral lip 25 provided on the frame engages the lower parts of the side wall portions 15,16,17 which carry the inwardly directed flanges 19,20,21, thus preventing the lower parts of the side wall portions from inadvertently moving outwardly.

The upstanding lip 25 also provides a degree of rigidity to the frame 22 and a degree of rigidity to the entire part of the structure in the region of the frame 22.

The part of the air-bag 26 which surrounds the air inlet into the air-bag is trapped between the lower face of the radially outwardly directed flange 4 provided on the housing 3 and the parts of the flanges 19,20,21 carried by the side wall portions 15,16,17 which are directed upwardly and inwardly towards the interior of the cover.

The air-bag is then retained within the space 26.

Fastening means, such as bolts 27 pass through the coaligned apertures 6 in the flange 4, the apertures formed in the flanges 19,20,21 carried by the side walls 15,16,17, and the apertures 24 formedFin the frame 22.

It is to be noted that, in the described embodiment, the top part of the side wall 17 is of greatly reduced thickness in the region 28 where the side wall joins the top wall 11. This constitutes a lines of mechanical weakness.

When the cover 10 and the air-bag 25 have been connected to the housing 3 in the manner described above the gas generating cartridge 8 may be inserted into the housing 3 through the aperture 7 provided in the gable end 2. The air-bag arrangement is then in an operational condition.

When the pyrotechnic charge in the gas generator cartridge is activated, gas passes through the apertures formed in the mesh 9 to inflate the air-bag 25.

Initially a force is applied to the housing 10, tending to move the side wall portions 15,16,17 upwardly.

However, the flanges 19,20,21 carried by the side walls extend underneath the outwardly directed flange 4 of the housing 3, since the flange 4 is located adjacent that face of each flange 19,20,21 which is directed towards the interior of the housing. Consequently, the side walls 15,16,17 and the associated flanges 19,20,21 are well able to withstand the force applied to them during the initial stage of inflation of the air-bag 26. The line of mechanical weakness 28 fractures, and the top wall 11 of the cover 10 may then hinge to an open position, permitting the air-bag to inflate fully.

In the embodiment of Figure 2, bolts 27 are utilised to secure the flange 4 to the frame 22. In Figure 3, however, an alternative fastening means is used in the form of a resilient plastic peg 29 having an enlarged head 30 which abuts the top surface of the flange 4 and a split shank 31 having a head adapted to engage an aperture 24 formed in the frame 22, the head being such that it is resiliently deformed inwardly as it passes through the aperture 24 and then resiliently springs outwardly to provide a snap-lock effect.

Figure 4 illustrates an embodiment which is similar to the embodiment of Figure 2, and like references are used to identify like arts with the addition of a prime. The side wall portion 15' is of greatly reduced height as compared with the side wall portion 15 of Figure 2, so that the top wall 11' of the cover 10' is of more arcuate form and it can thus blend smoothly with a dashboard or the like when the airbag unit is mounted in position.

Claims

CLAIMS:

1. An air-bag unit comprising a housing incorporating a source of gas, and having a gas outlet opening provided with a peripheral outwardly directed flange, the air-bag unit further comprising an air-bag and a cover, the air-bag and the cover both being fixed, by means of the same fixing elements, to the flange provided on the housing, the cover being provided with side wall portions carrying inwardly directed flanges, the flange on the housing being located adjacent those parts of the flanges carried by the side walls of the cover which are directed inwardly towards the interior of the cover.

2. A unit according to Claim 1 wherein the side wall portions comprise separate portions which each move hingedly relative to a top wall of the cover.

3. A unit according to Claim 1 or Claim 2 wherein the fixing element comprise bolts passing through aligned apertures in the flange on the housing and flanges on the side wall portions.

4. A unit according to Claim 1 or Claim 2 wherein the fixing elements comprise snap-locking pegs passing through aligned apertures in the flange on the housing and the flanges on the side wall portions.

5. A unit according to any one of the preceding Claims wherein the fixing elements comprise a frame which engages the parts of the flanges carried by the side walls of the cover which are directed outwardly away from the interior of the cover.

6. A unit according to Claim 5 as dependent on Claim 3 or 4 wherein the frame is provided with apertures aligned with the apertures in the flanges.

7. A unit according to Claim 5 or 6 wherein the frame has a peripheral upstanding lip which engages the lower part of the side wall portions adjacent said inwardly directed flanges.

8. A unit according to any one of the preceding Claims wherein a part of the air-bag surrounding a gas inlet is trapped between the outwardly directed flange and the inwardly directed flanges.

9. A unit according to any one of the preceding Claims wherein the cover is provided with a line of mechanical weakness comprising a portion of reduced thickness between a side wall portion and a top wall of the cover.

10. A unit according to any one of the preceding Claims wherein the side wall portions are of different height.

11. An air-bag unit substantially as herein described with reference to and as shown in Figures 1 and 2 of the accompanying drawings.

12. An air-bag unit substantially as herein described with reference to and as shown in Figures 1 and 2 of the accompanying drawings as modified by Figure 3.

13. An air-bag unit substantially as herein described with reference to and as shown in Figures 1 and 2 of the accompanying drawings as modified by Figure 4.

14. Any novel feature or combination of features disclosed herein.

Amendments to the claims have been filed as follows 1. An air-bag unit comprising a housing incorporating a source of gas, and having a gas outlet opening provided with a peripheral outwardly directed flange, the air-bag unit further comprising an air-bag and a cover which are both located above the housing, the air-bag and the cover both being fixed, by means of the same fixing elements, to the flange provided on the housing, the cover being provided with side wall portions carrying inwardly directed flanges, the flange on the housing being located adjacent and above those parts of the flanges carried by the side walls of the cover which are directed inwardly towards the interior of the cover.