Method and apparatus for retaining an airbag within a passenger-side airbag module

A one-piece molded plastic retainer is employed to hold each of two opposed edges of an airbag mouth in engagement with a reaction canister. The retainer is sewn, or otherwise secured, in the airbag mouth and includes a rod carrying a pair of integral discs which snap-fit into rails in a diffuser plate. The rails are thereafter slid into channels in the reaction canister. The rod includes a stiffening rib to resist stresses imposed during assembly and during bag deployment.

TECHNICAL FIELD 
This invention relates to the field of vehicle airbag modules. More 
specifically, it relates to the field of retaining airbags within a 
passenger-side airbag module. 
BACKGROUND ART 
The housing structure of a passenger-side vehicle airbag module provides 
protection for the gas generator and the inflatable bag until the time of 
deployment of the latter. This structure includes means for mechanically 
coupling the mouth of the airbag to the reaction canister. The load 
resulting from airbag deployment is large and, accordingly, it has been 
necessary in the past to use relatively heavy metal parts for performing 
the coupling function. In addition, the need for multiple parts has 
increased the complexity of assembly. 
Accordingly, it is a primary object of the present invention to provide a 
lightweight, one piece retainer for securing an airbag within a 
passenger-side module. Another object is to provide a simplified method of 
assembly. Other objects, features, and advantages will become apparent 
from the following description and appended claims. 
DISCLOSURE OF INVENTION 
A one piece retainer rod, including flanges and a stiffening rib, is sewn 
into the edge of a passenger-side airbag. Two such edges on opposite sides 
of the airbag mouth permit the retainer rod to be snapped into engagement 
with the U-shaped rails of the diffuser plate. The rails of the diffuser 
plate are thereafter inserted into channels formed along the open trough 
of the reaction canister.

BEST MODE FOR CARRYING OUT THE INVENTION 
Referring first to FIG. 1, the upper portions of the sidewalls 10, 12 of a 
trough-shaped reaction canister are illustrated, the end plates of the 
canister being removed. Typically the canister may be extruded of aluminum 
and each sidewall carries upon its inner surface a mounting channel 14, 16 
into which extend longitudinal openings 18, 20. The mouth of the reaction 
canister is spanned by a diffuser plate 22. The function of the diffuser 
22 is to evenly spread the gases from an inflator (not shown) to the 
airbag 24 which is schematically shown in collapsed and folded form. 
One such diffuser plate is illustrated and described in detail in copending 
application Ser. No. 08/181,897 filed Jan. 14, 1994 by D. R. Lauritzen et 
al. and assigned to the same assignee as the present invention. The 
disclosure of that application is incorporated by reference and made a 
part hereof. The edges of the metal diffuser plate 22 are curved 
downwardly and bent to form a pair of U-shaped rails 26, 28 which are 
arranged to slide within the open ends of the respective channels 14, 16. 
FIGS. 2 and 3 illustrate the retainer rod of this invention. Two such rods 
are employed in the invention on opposite sides of the mouth of the airbag 
24. However, since they are identical, only one need be described. 
The retainer is preferably molded from any suitable plastic such as, for 
example, nylon or polyethylene. It comprises a cylindrical rod 30 which, 
in the FIG. 2 embodiment, has a length greater than that of one edge of 
the airbag mouth. In one embodiment, this length was approximately 250 mm. 
At each end of the rod is an integral, disc-shaped flange 32, 34. In the 
illustrated embodiment, the spacing between the flanges 32, 34 is 
sufficient to span the length of the edge of the airbag 24 which is 
indicated in phantom in FIG. 2. In the referenced embodiment, the rod 30 
had a diameter of 5 mm and each flange had a diameter of approximately 11 
mm and a thickness of 0.3 mm. Also integral with the rod 30 is a 
substantially planar rib 36 which extends longitudinally along and 
radially outward from the rod 30 between the two flanges 32, 34. The rib 
36 is substantially rectangular and in the described embodiment was 
approximately 0.3 mm in width. Extending inwardly from the outermost edge 
of the rib 36 is a rectangular recess 38. The ends of the recess 38 form a 
pair of stops 40, 42. 
The retainers are sewn into opposed edges of the mouth of the airbag 24. 
The airbag sidewall material is wrapped around the respective rod 30 such 
that its edge 44 substantially covers the stiffening rib 36. A line of 
stitching 46 connects the two layers of bag material and extends between 
the stops 40, 42. The stops serve the dual functions of preventing the 
retainer from separating from the airbag prior to installation and of 
keeping the retainer centered along the edge of the airbag mouth. While 
stitching has been described and illustrated, it will be understood that 
other means may be employed for adhering the bag material upon itself. 
These means include, but are not limited, to the use of adhesives and 
plastic welding techniques. 
In assembling the module, the airbag 24 with the retainers in place is 
first assembled to the diffuser plate 22. The diffuser plate is made of 
sheet metal and, accordingly, its U-shaped rails 26, 28 have a certain 
amount of resiliency. As a result, the flanges 32, 34 may be forced into 
the rails by snap-fit engagement. Thereafter, the diffuser 22 with the 
airbag 24 attached is assembled to the reaction canister by merely sliding 
the rails 26, 28 into the respective channels 14, 16 as illustrated in 
FIG. 1. 
The depiction of the retainer and airbag is reversed as between FIG. 1 on 
the one hand and FIGS. 2 and 3 on the other. Referring particularly to 
FIG. 1, it will be noted that, when installed on a reaction canister, the 
stiffening ribs 36 extend in the direction of airbag deployment. This 
results in substantial stiffening of the rod 30 against bending forces in 
that direction. Not only does this serve to absorb the load resulting from 
airbag deployment, but it also makes it easier to insert the reinforced 
edge of the airbag mouth into the channel during assembly of the module. 
FIG. 4 illustrates a modified form of the invention wherein the rod 30 is 
wholly contained within the material of the airbag 24'. The airbag is 
provided with slots 48, 50 through which the flanges 32, 34 respectively, 
extend. In other respects, the FIG. 4 version is essentially identical 
and, accordingly, similar reference numerals have been retained. 
It will now be noted that the major important features of this invention 
have been incorporated into one molded part, thereby simplifying 
production. In addition, the one-piece molded plastic retainer is much 
cheaper than any combination of materials or parts and is also much 
lighter than alternate materials such as aluminum or steel. The retainer 
design results in ease of assembly and also helps to insure that parts are 
not lost during shipping and handling. The rod is easily sewn into the 
airbag and does not threaten airbag integrity by occasioning any 
additional stress in the bag. 
It is believed that the many advantages of this invention will now be 
apparent to those skilled in the art. It will also be apparent that a 
number of modifications may be made therein without departing from its 
spirit and scope. Accordingly, the foregoing description is to be 
construed as illustrative only, rather than limiting. This invention is 
limited only by the scope of the following claims.