WO1999046151A1

WO1999046151A1 - Attachment of airbag to housing

Info

Publication number: WO1999046151A1
Application number: PCT/US1999/002257
Authority: WO
Inventors: Rainer Schmidt; Staub Andreas
Original assignee: Breed Automotive Technology, Inc.
Priority date: 1998-03-11
Filing date: 1999-02-02
Publication date: 1999-09-16

Abstract

An airbag (6) is attached to an airbag housing (4). The airbag (6) has, in the region of the edge of a gas inlet opening (12), at least one recess into which a corresponding projection (16, 20, 28) of the airbag housing can engage. An additional securing means is provided between the airbag and the airbag housing to prevent loosening of the airbag (6) from the projection.

Description

ATTACHMENT OF AIRBAG TO HOUSING

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention relates to an attachment of an airbag to an airbag housing.

In known airbag modules, the attachment_, of an airbag to the airbag housing requires a large number of parts . A typical prior art airbag has an opening through which inflation gases can be introduced into the airbag. The airbag is fastened to the airbag housing m the region of the periphery of the opening by additional flanges and screws or clamping devices. The source of inflation gas, typically a gas generator, is also fastened to the airbag housing by means of screws or clamping devices.

One such airbag module is known, for instance, from WO 94/25311. That airbag module has an airbag, a gas generator, and additional fastening elements for fastening the airbag to the gas generator. The airbag has an opening througn which the gas generator extends into the inside of the airbag. The edge of the opening is clamped in an additional airbag holding ring. A portion of the airbag by the airbag holding ring is fastened jointly by a flange arranged on the gas generator between an additional fastening plate and a housing part. In this connection, clamping elements, coming from the housing part, extend through the flange of the gas generator and the airbag and hold the additional holding plate Thus, the gas generator and the airbag are clamped fast between the holding plate and the housing part. The known attachments of an airbag to an airbag housing therefore require a large number of individual parts, resulting in a large manufacturing effort and high production costs. Furthermore, the attachment of the airbag to the airbag housing is expensive and time consuming. In addition, a large number of individual parts result in increased weight of the entire airbag module .

The object of the invention is to create an improved attachment of an airbag to an airbag housing, which is easy and inexpensive to manufacture and extremely safe.

This object is achieved by an attachment having the features indicated in Claim 1. Advantageous further embodiments can be noted from the dependent claims .

For the attachment of the airbag to an airbag housing in accordance with the invention, the airbag has, in the region of the edge of the gas inlet opening, at least one, but preferably several, recesses into which corresponding projections of an airbag housing can engage. This permits an extremely simple mounting of the airbag on the airbag housing. The airbag is suspended by its recesses on the projections of the airbag housing, which advantageously are formed as hooks. Furthermore, an additional securing means is provided which prevents the airbag and, in particular the recess, from detaching from the corresponding projection of the airbag housing. Such an attachment is extremely simple and inexpensive to produce and provides assurance that the airbag is held reliably on the airbag housing. A cover over the airbag is provided that has at least one recess into which a projection of the airbag housing can engage. Thus the cover on the airbag housing is assured against loosening from the projection by the additional securing means against detachment of the airbag and/or by a further securing means . Such a cover can be provided to cover an airbag module on the side facing the occupant. Due to the cover being suspended on the same projections as the airbag, the mounting of the cover is extremely simple and inexpensive. The cover also is assured against loosening from the airbag housing. Thus, it is impossible for the cover by error to loosen from the airbag housing upon transportation or upon installation of the airbag module. The cover advantageously is secured by the same securing means as that securing the airbag to the airbag housing. Thus, the secure attachment of the airbag and the cover can be effected in a single operation, whereby an extremely time- reducing and cost-saving installation is obtained.

However, it is also possible to separately secure the cover to make it possible for the cover to be mounted later than the airbag.

The additional securing of the airbag to the airbag housing is effected advantageously by welding or bonding. If the airbag housing and the airbag are made of weldable materials, it is extremely simple to connect the airbag to the airbag housing for instance by vibration, ultrasonic or thermal welding. Such a method of fastening is extremely simple to employ and does not require any additional parts upon the mounting of the airbag on the airbag housing. Therefore, the additional securing means of the airbag on the airbag

3 housing can be effected extremely rapidly and reliably. A bonding of the airbag and airbag housing is particularly meaningful when the material of the airbag and the material of the airbag housing are not weldable to each other. Thus bonding provides a simple and rapidly applied securing of the airbag on the airbag housing is possible also in this case.

The additional securing of the airbag to the airbag housing preferably is achieved by reshaping the projection on the airbag housing. This reshaping can be effected, for instance, mechanically, i.e. by bending or pressing together, or thermally, i.e. by melting the material. A combining of thermal and mechanical reshaping is also possible. Such an additional securing is extremely space saving, since it is arranged directly in the region of the attachment of the airbag to the airbag housing. Furthermore, in this case it is assured in an extremely reliable fashion that the airbag cannot loosen itself from the projections on the airbag housing.

The airbag preferably is secured by an additional mechanical fastener to the projection on the airbag housing. For example, such a mechanical fastener may be a rivet or a plug that is inserted into a recess in the airbag into the hole in the airbag housing. The plug or rivet then is, reshaped after insertion for securing the plug or rivet. Alternatively the plug or rivet may have detent means which hold the rivet or plug reliably in the hole in the airbag housing. Such a rivet or plug advantageously extends through the recess in the airbag with which the latter is attached to the airbag housing. The hole in the airbag housing is provided directly in the region of the projection

4 for the attachment of the airbag. Such an arrangement or securing means permits a very strong and reliable connection between airbag and airbag housing, the detachment of which is prevented reliably. The airbag housing advantageously is comprised of plastic. The plastic may be a glass- fiber-reinforced polyamide. Plastic permits a very simple, rapid and inexpensive production of even airbag housings of complicated shape, for instance by injection molding. Fiber reinforcement of the plastic assures in this connection sufficient stability and strength of the housing.

The airbag preferably consists of a plastic fabric. For such fabrics either polyamide 6 or polyamide 6.6 is preferably employed. Under certain circumstances, a heat-protection layer, for instance, silicone or neoprene, can be applied to the plastic fabric in order to protect the fabric from hot gases upon the inflation of the airbag. The use of plastic fabric for the airbag affords the advantage of great strength with at the same time inexpensive manufacture. Furthermore, plastic fabrics are extremely resistant and scarcely age, as a result of which sufficient strength of the airbag is assured even after many years. The production of the airbag from the plastic fabric can also be carried out extremely favorably since a welding together of individual layers and sections is possible. This welding together is substantially faster and more economical than sewing, for instance. Furthermore, an airbag of plastic fabric, particularly if the airbag housing is also made of plastic, permits easy welding of the airbag to the airbag housing for the additional securing of the attachment of the airbag. By such a welding, a permanent connection between the airbag housing and the airbag is created which prevents the airbag, and in particular the recesses in the airbag, from becoming detached from the corresponding projections on the airbag housing.

The cover also advantageously is comprised of plastic. Such a plastic cover can be made, for instance by injection molding, in practically any desired shape, whereby an optimal adaptation to the development of the interior of a motor vehicle can be obtained. Furthermore, such a cover can be made of relatively soft plastics in order to permit an easy tearing open of the cover upon the inflation of the airbag and thereby to minimize the risk of injury to the occupants of the vehicle. Such a plastic cover can, in the same way as the airbag, be welded particularly easily and rapidly, in particular to an airbag housing of plastic, whereby the cover can also be secured very easily against unintended detachment from the airbag housing. Both the cover and airbag are advantageously connected by one weld to the airbag housing. In this way, the securing of cover and airbag against detachment from the projections can be applied rapidly and inexpensively in a single step.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described below in further detail with reference to the accompanying drawings, in which:

Fig. 1 is a cross section through a passenger seat airbag module with a first embodiment of the attachment of the invention;

Fig. 2 shows a second embodiment of the attachment in accordance with the invention;

Fig. 3 shows a third embodiment of the attachment in accordance with the invention; and

Fig. 4 shows two further embodiments of the attachment in accordance with the invention.

DETAILED DESCRIPTION OF THE INVENTION

The airbag module 2 shown in Fig. 1 has an airbag housing 4 of substantially U-shaped cross section. The airbag 6 is fastened to the end regions of the opening of the airbag housing 4, i.e. on the free ends of the U-shaped cross section. The gas generator 8 is substantially tubular and extends in the interior along the closed bottom of the airbag housing 4 by screws. The airbag 6 is arranged in a deflated state within the airbag housing 4 between the gas generator 8 and the opening of the airbag housing 4. The opening of the airbag housing 4 is closed by the cover 10. The airbag 6 has a gas inlet opening 12 into which the airbag housing 4 with the gas generator 8 extends. In the region of the edge of the gas inlet opening 12 of the airbag 6, recesses 14 are provided into which hooks 16 of the airbag housing 4 engage. The hooks 16 are arranged on the outside circumference of the opening of the airbag housing 4 and extend outwardly substantially perpendicular to the sidewalls of the airbag housing 4. The airbag 6 is suspended by its recesses 14 upon the installation on the hooks 16 of the airbag housing 4. There thus results a simple, form-locked connection that is capable of transmitting the forces occurring upon the inflation of the airbag from the airbag to the airbag housing 4. A cover 10 closes the opening of the airbag housing 4 from the inside of the motor vehicle. The cover 10 is bent over in the region of its edge and has recesses that are arranged, corresponding to the hooks 16, on the airbag housing 4. The recesses in the region of the cover 10 also are suspended in form- locked manner on the hooks 16. To prevent a loosening of the airbag 6 and the cover 10, for instance, upon the transportation or the installation of the airbag module 2, an attachment in the form of a weld 18 preferably is provided in addition to the hooks 16. The weld 18 connects the cover 10 and the airbag 6 in inseparable manner with the airbag housing 4. In this way, the cover 10 and the airbag 6 are prevented from sliding off from the hooks 16. Furthermore, if the weld 18 is a continuous weld seam, it can function as continuous weld seam of the airbag 6. The weld 18 can also be in the form of individual spot welds without impairing its securing function. The weld 18 is effected after the suspending of the airbag 6 and the cover 10 on the hooks 16, for instance by ultrasonic welding. Instead of ultrasonic welding, any other welding methods suitable for the welding of the material used can be employed.

The airbag module 2 shown here is a passenger airbag module, but the attachment in accordance with the invention can also be used for other airbag modules, such as, for instance, a driver airbag module or a side airbag module.

Fig. 2 shows a second embodiment of the invention. In place of the hooks 16, outwardly directed pins 20 are provided on the sidewalls 22 of the airbag housing in the region of its opening. The airbag 6 is attached to the airbag housing 4 so that the pins 20 extend through the recesses 14 of the airbag 6. In this way, a form-locked connection is obtained between the airbag 6 and the airbag housing 4. The pins 20 have, within them, a hole 24 to permit an easier reshaping of the pin. After fastening the airbag 6 on the pins 20, the pins 20 are reshaped in a second step so that they form

9 a head 24 which extends beyond the recess 14 in the airbag 6, i.e. the outside dimension of the head 24 of the pin 20 is greater than the dimensions of the recesses 14. The airbag is fastened in a permanent manner to the pin 20 thus it is no longer possible to detach the airbag 6 from the pin 2. When the airbag housing 4 and thus also the pins 20 consist of metal, the reshaping of the pins 20 can be effected by the simple action of pressure, for instance by means of a press or a vice. If the airbag housing 4 and the pins made of plastic, then the reshaping of the pins is advantageously effected by the action of pressure with simultaneous heating in order to obtain a suitable softening or melting of the material and thus easier reshaping.

A third embodiment of the invention is shown in Fig. 3 and is substantially similar to the second embodiment that was shown in Fig. 2. The first step in this third embodiment corresponds to the first step in the second embodiment, and includes fastening the airbag 6 in the airbag housing 4 by means of the recesses 14 provided in the airbag 6 and the pins 20 provided on the side walls 22 of the airbag housing 4. In this third embodiment, both the airbag and the airbag housing are comprised of plastic. After placing the airbag 6 on the pins 20, the pins are reshaped for the additional securing of the airbag on the airbag housing. To achieve this reshaping, the pins are heated and at the same time pressed in the direction of their longitudinal axis onto the sidewall 22 of the airbag housing 4. In this way, each pin widens in such a manner that it extends beyond the circumference of the recess 14 in the airbag. Simultaneously the heat

10 achieves a welding between the reshaped pin 20 and the plastic fabric of the airbag 6 in the vicinity of the recess 14. The heating or welding in this third embodiment takes place advantageously by means of ultrasonic welding, but can be carried out by any other suitable method of welding. The weld between the pin and the airbag reliably and permanently secures the airbag in place.

Fig . 4 shows two further embodiments of the invention. In both of these embodiments, the airbag 6 is hooked by on the projections 28 of the airbag housing 4. The projections extend substantially perpendicularly outwardly from the sidewalls of the airbag housing in the region of the opening thereof, in much the same manner as the pins 20 in Figs. 2 and 3 and the hooks 16 in Fig. 1. The projections 28 each have a hole 30 in their center that extends through the entire sidewall of the airbag housing 4. In the example shown to the left in Fig. 4, a plug 32 is inserted in each said opening 30 after suspending the airbag 6. The plugs 32 function to secure the airbag 6 on the projection 28. At one end the plug 32 has a head 34, the surface of which is larger than the recesses 14 in the airbag 6. On its opposite end, the plug 32 has detent lips 36 that, upon the pushing of the plug 34 into the hole 30, come against the plug 32. The detent lips 36 unfold after leaving the hole 30 on the rear of the sidewall 22 of the airbag housing 4 and thus permanently hold the plug fast in the hole 30 in the manner of a barb. In the example shown on the right in Fig. 4, a rivet 38 is inserted in the hole 30. One end of the rivet 38 has a head 40 that extends beyond the recess 14 in the airbag 6, and thus prevents

11 the airbag 6, from loosening from the projection 28. The other end of the rivet 38 is reshaped, i.e. pressed flat, after insertion of the rivet 38 into the hole 30. A second head 42 is formed which has a larger diameter than the hole 30 and thereby holds the rivet 38 in the hole 30 in a permanent manner.

A cover can additionally be fastened to the housing in the embodiments shown in Figs. 2 to 4 , in much the same manner as in the embodiment shown in Fig. 1. The cover is provided in the region of its edge with recesses that are complementary to the pins 20 or the projections 28 and are pushed together with recesses 14 of the airbag 6 onto the pins or the projections. By reshaping the pins or by inserting the plugs or rivets, the airbag 6 as well as the cover then are secured on the airbag housing 4.

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Claims

1. The assembly of an airbag (6) and an airbag housing (4) in which the airbag has in the region of the edge of a gas inlet opening (12) at least one recess (14) into which there can engage in a corresponding projection (16, 20, 28) of the airbag housing, and an additional securing means against detachment of the airbag (6) from the projection is provided between the airbag and the airbag housing.

2. The assembly of an airbag (6) and an airbag housing (4) according to Claim 1 in which a cover (10) over the airbag is provided which has at least one recess into which the projection (16, 20, 28) of the airbag housing can engage, the cover (10) is secured on the airbag housing against detachment from the projection by the additional securing against loosening of the airbag and/or further securing means he assembly of an airbag (6) and an airbag housing (4), and the airbag is secured to the projection (28) of the airbag housing by an additional mechanical fastening element (32, 38) .

3. The assembly of an airbag (6) and an airbag housing (4) according to either of the preceding claims, in which the airbag is further secured to the airbag housing by welding or bonding.

4. The assembly of an airbag (6) and an airbag housing (4) according to any of the preceding claims, in which the additional securing of the airbag to the

13 airbag housing is attained by reshaping the projection (16; 20; 28) on the airbag housing.

5. The assembly of an airbag (6) and an airbag housing (4) according to any of the preceding claims in which the airbag housing comprises plastic.

6. The assembly of an airbag (6) and an airbag housing (4) according to any of the preceding claims in which the airbag comprises a plastic fabric.

7. The assembly of an airbag (6) and an airbag housing (4) according to any of the preceding claims in which the cover (10) comprises plastic.

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