Reaction can to cover joining method

Abstract: In a passenger side air bag module assembly (10), a reaction can (12) is attached and correctly positioned with reference to a module cover or chute (14) by providing a flange (36) on the can with apertures (32) into which protruberences (52) on the module cover may be inserted, thereby joining the can to the cover without the use of screws or rivets or welding.

Description: This invention relates to passenger side airbag modules. More particularly it relates to the assembly of a passenger side airbag reaction can to a passenger side airbag module cover or cushion chute without the use of screws, rivets or other fasteners and by means which positively define the relative location of the parts being assembled. Typical recently issued United States Patents describing air bag modules and their assembly from components include the following: Lauritzen et al US 4,941,678 issued July 17, 1990 Webber et al US 5,263,739 issued Nov. 23, 1993 Hansen et al US 5,322,324 issued June 21, 1994 Lauritzen et al US 5,332,256 issued July 26, 1994 Donegan et al US 5,351,987 issued Oct. 04, 1994 The disclosures of these patents are incorporated in this application by this reference. In Lauritzen et al 4,941,678 a structure is described in which the reaction can includes a body part which is formed by extrusion and has grooves into which a cover may be snapped. End plates are attached to the can/cover by screws. The assembling of the several parts involves carefully locating them with respect to one another. In Webber et al 5,263,739 a similar module is described, the assembled parts being held together by rods 32 and 34 and push nuts 24. In Hansen et al 5,322,324 rivets 24 and 46 are used to fasten the individual components of the module to one another. In Lauritzen et al 5,332,256 studs and nuts are utilized to secure the several parts of the module to one another. In Donegan et al 5,351,987 the parts are assembled by sliding one axially of the other. Screws and rivets are difficult to install and it is difficult to verify correct fastener engagement. Rivets and screws distribute deployment loads over a relatively small area. Slide-on covers require clearances on the ends to pass over the folded cushion and can be difficult to slide on to a canister. It will be seen that each of the above assemblies requires the use of some sort of fastener necessitating a supply of such with consequent increase in inventory cost and space. Therefore, there is a need for a simpler and less expensive means for assembling a passenger side air bag reaction module cover or chute. Research Disclosure No. 369, (Emsworth, GB, 1st January 1995) page 4, XP 000494436 discloses an air bag reaction canister and door assembly wherein a row of L-shaped flanges projecting from the canister pass through correspondingly shaped apertures in a bar on which a door is mounted. The flanges have respective axially aligned holes through which is passed a rod to secure the door in position on the canister. The present invention consists in a passenger side airbag module assembly adapted to be installed into an automotive vehicle, which comprises: a reaction canister having walls which terminate in an open mouth, said walls including two planar sidewalls and two planar endwalls, said sidewalls extending beyond the extremity of said endwalls, each of said sidewalls having an edge portion bent substantially normal to the planar portions of said sidewalls, thereby defining a flange extending outwardly from the mouth of said canister, apertures provided in portions of said sidewalls adjacent to the mouth of said canister, a module cover or chute having an inner end adapted to be installed in a recess in the dashboard of said vehicle and an outer end adapted to be inserted into the mouth of said canister; said cover or chute including two endwalls and two sidewalls, a web on an exterior surface of each of said sidewalls adjacent to the outer end of said cover/chute and integral with said sidewalls, blocks integral with said web and depending from said web, said blocks being shaped to be inserted into the apertures in the flanges of said reaction canister, and bores extending transversely through said blocks and a rod inserted through said bores to secure said blocks to said reaction canister, whereby the load during deployment of an airbag in said canister is distributed over a wide area defined by said reaction canister flange and said cover/chute web. The reaction can may be made of steel, aluminium or any other suitable material. The cover may be made of a molded polymer. A chute may also be produced from a molded polymer or steel. The blocks preferably have draft angles on their surfaces that enable simple assembly and provide positioning in the plane parallel to the reaction can mouth. Above the can flange the web preferably runs the full length of the cover or chute sides. This web provides a hard stop on assembly. This web can be eliminated between the blocks. In that case the blocks in the bottom of the can slots provide a hard stop during assembly. These features position the cover or chute in the correct position normal to the reaction can mouth and do not allow the cover/chute to slide too far into the can. Each of the cover/chute blocks has a hole in it that runs parallel to the adjacent reaction can side wall. After the cover/chute is placed in the appropriate position in the reaction can rods, which are preferably steel rods with a slight taper in one end, are pressed through the holes in bosses on the assembly sides. These rods transfer the deployment loads from the cover to the can distributing the load over a larger area than in the case of rivets or screws. They also cause a tight fit between the reaction can and the cover/chute. Another reaction can option is to bend the flange on the can all the way to the can wall, making a pocket for the joining rod. The edge of the can would still be slotted and fit up with the cover blocks in the same way. An advantage of this invention is that it does not require screws, nuts, rivets, or welds to attach a passenger airbag module cover to a reaction can. This invention also allows the cover to be placed directly on the mouth of the can without sliding it on from one side. This cover to can attachment method also provides features that position the cover in the correct location on the can. This invention allows a passenger airbag cover to be attached to a reaction can without the use of rivets or screws, thereby decreasing costs and minimizing quality problems. It also efficiently distributes the deployment loads across a large portion of the cover attachment walls. This invention also positions the cover both in the plane of the can mouth and normal to the plane. By means of the invention the assembly process can be simplified by avoiding the extra space required when the parts are assembled by sliding one part into the other from one end of the two parts (reaction can/cover or chute.) For a better understanding of the invention, reference is made to the accompanying drawings and description in which preferred embodiments of the invention are illustrated. In the accompanying drawings which form a part of this specification: Figure 1 is a perspective schematic view showing an assembled passenger side air bag module, according to one embodiment of the invention; Figure 2 is a sectional view taken on plane 2-2 of Figure 1; Figure 3 is a similar view taken on plane 3-3 of Figure 2; Figure 4 and 5 are fragmentary views in perspective showing details of the cover/chute and reaction can, respectively; and Figure 6 is a fragmentary sectional view of a second embodiment showing another connection between the cover and can in the assembled air bag module. In Figure 1, an air bag module 10 according to the present invention consists of a reaction can 12 and a module cover/chute 14 intended to be mounted in an instrument panel or dashboard on the passenger side of an automotive vehicle. The reaction canister 12 contains an inflator and a folded air bag as shown in any of the above noted patents. These components form no part of the present invention and therefore are not shown in the drawings. The manner in which the module cover 14 is attached to the reaction canister will become apparent from the fragmentary views in Figure 4 and 5, and the sectional views in Figures 2 and 3. As seen in the Figures, the reaction canister 12 includes a housing 20 having a side wall 22 and endwalls 24, which extend upwardly to define a mouth 26. The sidewalls 22 extend beyond the upper edge 28 of the endwalls. Extensions 30 in the upwardly extending sidewalls 22 are slotted, e.g. by punching or cutting suitably shaped openings 32 adjacent to the upper edge or rim 34 of sidewall 22. The extension 30 is bent to form a flange 36 on opposite sides of the mouth 26 of canister 12. Cover/chute comprises two sidewalls 42 and two endwalls 44 with the four walls defining a shape 46 complimentary to the shape of can mouth 26. Integral with sidewalls 42 are webs 48 shown in Figure 4. Webs 48 have an upper surface 50, substantially normal to the sidewalls 42 from which they protrude. Depending from the lower portion of the webs 48 are blocks 52. Each block 52 has a generally square bottom 54 and sides 56 extending between bottom 54 and web 48. A bore 58 extends through each individual block 52, below web 48 and parallel to it. The upper edge of each sidewall 22 is bent over to form flange 36 on reaction can. The recesses 32 in flange 36 are adapted to receive blocks 52. Blocks 52 are provided with draft surfaces or tapers to facilitate their insertion into recesses 32. It will be appreciated that the combinations of blocks 52 and recesses 32 locate the cover/chute 14 with reference to the reaction can 12. After the two have been assembled, a tapered rod 60 may be inserted into bores 58 in the cover blocks, securing the cover 14 to reaction can 12. In an alternative embodiment, can flange 36 may be bent so as to further confine rod 60, as shown in figure 6 supplementing the cooperation between rod 60 and bores 58.

Claims: A passenger side airbag module assembly (10) adapted to be installed into an automotive vehicle, which comprises: a reaction canister (12) having walls which terminate in an open mouth (26), said walls including two planar sidewalls (22) and two planar endwalls (24), said sidewalls extending beyond the extremity (28) of said endwalls, each of said sidewalls having an edge portion bent substantially normal to the planar portions of said sidewalls, thereby defining a flange (36) extending outwardly from the mouth of said canister, apertures (32) provided in portions (30) of said sidewalls adjacent to the mouth of said canister, a module cover or chute (14) having an inner end adapted to be installed in a recess in the dashboard of said vehicle and an outer end adapted to be inserted into the mouth (26) of said canister (12); said cover or chute including two endwalls (44) and two sidewalls (42), a web (48) on an exterior surface of each of said sidewalls adjacent to the outer end of said cover/chute and integral with said sidewalls (42), blocks (52) integral with said web and depending from said web, said blocks being shaped to be inserted into the apertures (32) in the flanges (36) of said reaction canister, and bores (58) extending transversely through said blocks (52) and a rod (60) inserted through said bores to secure said blocks to said reaction canister (12), whereby the load during deployment of an airbag in said canister is distributed over a wide area defined by said reaction canister flange and said cover/chute web. An airbag module assembly according to claim 1 wherein a bent portion of said canister flange (36) partially encircles said rod (60). An airbag module assembly according to claim 1 or claim 2 wherein draft surfaces are provided on said blocks (52) to facilitate insertion of said blocks into said apertures (32).

Inventors: GARNER BRETT R, LEE RUSSEL P, GARNER, BRETT R., LEE, RUSSEL P.
Applicants: AUTOLIV ASP INC, AUTOLIV ASP, INC.
Application year: 1996
Main classification: B60R21
IPC codes: B60R21