Hybrid inflator retention in automotive airbag module

Abstract: Vehicle airbag reaction canister assembly including a deep drawn canister (10) with opposed sidewalls (16, 18) and opposed endwalls (20, 22). A hybrid inflator with gas emission ports at one end and a substantially cylindrical body (28) is held against a curved floor (24) of the canister (10) by an apertured bent sheet metal diffuser (14) having first and second mounting edges (36, 38). The first mounting edge (36) is held against the first canister wall (18) by screws (46). The second mounting edge (38) is thereafter drawn towards and into engagement with the canister floor (24) by screws (48) thus tensioning the diffuser (14) against the inflator (12). A method of producing the assembly is also disclosed.

Description: This invention pertains to the field of automotive airbag installations. More particularly, it relates to passenger side modules employing hybrid inflators and a diffuser which is a separate element from the reaction canister. Currently there are three fundamentally different reaction canisters employed in passenger side airbag modules. These are the extruded (usually aluminum) can, the folded sheet metal can, and the deep drawn can. Another element which is widely used in passenger side airbag modules is the hybrid inflator. The hybrid inflator is characterized, in part, by the fact that it generally emits inflating gas from only one end. Because of this, a metal diffuser is required to ensure an even flow of gas from the inflator into the airbag. See for instance document US-A-5031932. In the case of extruded canisters, the diffusers may, although they need not necessarily, be extruded as an integral part of the canister extrusion. In the case of folded sheet metal canisters, diffusers are relatively easily installed. In both instances, suitable provisions are normally made for securely retaining the inflator in the canister to prevent rattles. These results are most easily achieved in the extruded and folded sheet metal canisters wherein the use of separate end plates simplifies the installation of both inflators and diffusers. In a deep drawn canister, on the other hand, there are no separate end plates. As a result, hybrid inflators have not been employed in combination with such canisters. Obviously, however, it would be desirable to reduce the number of parts and the assembly time which results from the use of extruded and folded sheet metal canisters. Accordingly, it is a primary object of the present invention to provide a passenger side airbag module assembly which includes both a deep drawn canister and a hybrid inflator. Another object is to provide such an assembly wherein a single element performs the dual functions of serving as a gas diffuser and a canister retainer. Other objects, features, and advantages will become apparent from the following description and appended claims. The invention relates to a reaction canister assembly with the features of claim 1, and a method for assembling said assembly with the steps of claim 10. The invention comprises a trough-shaped reaction canister within which is housed a hybrid inflator. A diffuser sheet is formed from a rectangular metallic plate. One of the longer edges of the rectangle is secured internally to one of the canister sidewalls. The diffuser sheet is stretched tightly over the body of the inflator and its opposite edge is drawn into engagement with the reaction canister to tightly secure and hold the inflator in position. The diffuser sheet includes gas diffusing openings along its length to permit gas from the inflator to flow evenly into the airbag. The invention will now be described by way of example only with reference to the accompanying drawings in which: FIG. 1 is an exploded isometric view of the three major elements of the invention; FIG. 2 is an end view of the partially assembled elements with a portion of the canister broken away to better illustrate the manner of assembly; and FIG. 3 is a view similar to FIG. 2 illustrating the elements fully assembled. Referring to the drawings, FIG. 1 illustrates the three basic components of the invention, namely: the reaction canister 10 ; a conventional hybrid inflator 12 ; and a metal diffuser 14 . The reaction canister 10 is formed by the deep drawing process. Consequently, it is in one piece. It is generally trough-shaped including first 16 and second 18 sidewalls, first 20 and second 22 endwalls, and a curved floor 24 . The open mouth of the reaction canister 10 is surrounded by a mounting flange 26 . As previously stated, the hybrid inflator 12 is conventional and includes a cylindrical body 28 having gas emission ports 30 at only one end. The length of the reaction canister 10 is such as to receive the inflator 12 therein with its cylindrical body lying on the curved floor 24 as illustrated in FIGS. 2 and 3 . The function of the diffuser 14 is to distribute the gas emitted from the ports 30 of the inflator 12 along the length of the reaction canister so as to evenly fill the airbag (not shown). The folded airbag is housed at least partially within the canister with its open mouth positioned to receive the gases from the diffuser 14 . As the airbag does not form a part of this invention, it is not illustrated and need not be further described. The diffuser 14 is a sheet metal plate 32 which extends the length of the canister 10 from one end wall 20 to the other end wall 22 . The plate 32 is essentially rectangular but is formed with a longitudinal bend 34 which is adapted to overlie the cylindrical body 28 of the inflator 12 . The longitudinal edges of the rectangular plate 32 are bent to provide a first 36 and a second 38 mounting edge. The plate 32 defines gas diffusing openings 40 along its length. These openings lie on either side of the bend 34 in order to provide a clear passage for gas flowing from the gas ports 30 in the inflator 12 . As the bend 34 portion of the plate 32 will lie flush against the cylindrical body 28 , openings are not required in that portion. Although not precluded, they would be blocked to gas flow and, thus, ineffectual. In addition to the distribution of inflating gas, the diffuser 14 serves an important second function. It clamps the inflator 12 securely against the floor 24 of the reaction canister 10 in the following fashion. The first mounting edge 36 of the diffuser 14 is provided with mounting holes 42 therealong. Similar holes 44 are provided along the length of the second mounting edge 38 . Corresponding holes are provided in the second sidewall 18 and a portion of the floor 24 of the reaction canister 10 . The diffuser 14 is positioned within the reaction canister 10 and over the cylindrical body 28 of the inflator 12 and its first mounting edge 36 is secured to the first sidewall 16 of the reaction canister by means of screws 46 . The size of the diffuser 14 is such that its second mounting edge 38 barely reaches that portion of the floor 24 containing its matching mounting holes. Screws 48 are extended through these holes and into threaded engagement with the mounting holes 44 of the second mounting edge 38 as illustrated in FIG. 2 . The screws (which may be sheet metal screws) are then tightened so as to pull the diffuser 14 downward and into tight engagement with the cylindrical body 28 of the inflator 12 as illustrated in FIG. 3 . In this fashion, the inflator 12 is held firmly in position to prevent rattling while simultaneously permitting the distribution of gas flow into the reaction canister 10 as illustrated by the arrows in FIG. 3 . 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 scope. Accordingly, the foregoing description is to be construed as illustrative only, rather than limiting.

Claims: A reaction canister assembly for use in a vehicle airbag module which comprises: a reaction canister (10) in the form of a trough having a floor (24) and spaced first and second sidewalls (16, 18) and first and second end walls (20, 22) defining an open mouth; an elongate inflator (12) positioned within the canister (10) below said open mouth, said inflator (12) having gas emission ports (30); a substantially rectangular diffuser sheet (14) positioned within the canister (10) and over said inflator (12), said diffuser sheet (14) having first and second mounting edges (36, 38) extending substantially the length of said trough, first and second ends located adjacent the respective first and second endwalls (20, 22) of said canister (10), said diffuser sheet (14) further including gas diffusing openings (40) therethrough; and means (42, 48, 44, 46) for securing the diffuser sheet (14) to the reaction canister (10), characterised in that said reaction canister (10) is a one-piece reaction canister and in that said means for securing the diffuser sheet (14) comprises: (a) securing means (42, 46) for securing the first mounting edge (36) of said diffuser sheet to the first sidewall (16) inside the canister (10) on one side of the inflator (14); and (b) tensioning means (44, 48) for bringing the second mounting edge (38) of said diffuser sheet (14) towards and into engagement with an inside portion of the reaction canister (10) on the opposite side of the inflator while simultaneously tensioning said diffuser sheet (14) to grip said inflator (12) while leaving the gas diffusing openings (40) free of blockage by the inflator (12). The assembly of claim 1 wherein said inflator (12) is substantially cylindrical and said gas emission ports (30) are located substantially solely at one end thereof, said first and second diffuser ends substantially abut the respective first and second canister endwalls (20, 22) and said securing means (42, 46) and tensioning means (44, 48) are situated on substantially opposite sides of said inflator (12) so as to tension the inflator (12) against said floor (24) of said reaction canister (10). The assembly of claim 1 or 2 wherein said tensioning means comprises screws (48) extending through said portion of the reaction canister (10) in threaded engagement with said second mounting edge (38) that barely reaches said portion of the reaction canister prior to said threaded engagement, said screws (48) being tightened so as to pull said diffuser sheet (14) downward into tensioned engagement over said inflator (12). The assembly of claim 1, 2 or 3 wherein said securing means and tensioning means comprise holes (42, 44) extending along said first and second mounting edges (36, 38). The assembly of any preceding claim wherein said reaction canister (10) is deep drawn. The assembly of any preceding claim wherein the portion of the reaction canister towards which the second mounting edge (38) of the diffuser sheet (14) is drawn is the floor (24). The assembly of any preceding claim wherein said inflator (12) is a hybrid inflator. The assembly of any preceding claim wherein said diffuser sheet (14) defines a bend (34) running substantially along its length for engagement with said inflator (12), said gas diffusing openings (40) being positioned on either side of said bend (34). The assembly of any preceding claim wherein said diffuser sheet (14) is metal. A method of assembling the assembly claimed in any one of claims 1 to 9 including the steps of: (a) inserting said inflator (12) into said reaction canister (10), (b) securing said first mounting edge (36) of said diffuser sheet (14) to said first sidewall (16) with said securing means (42, 46) and (c) bringing said second mounting edge (38) of said diffuser sheet (14) towards and into engagement with a portion of said reaction canister (10) with said tensioning means (44, 48) while simultaneously tensioning said diffuser sheet (14) to grip said inflator (12).

Inventors: GREEN DAVID J, PAXTON DONALD J, GREEN, DAVID J., PAXTON, DONALD J.
Applicants: MORTON INT INC, MORTON INTERNATIONAL, INC.
Application year: 1995
Main classification: B60R21
IPC codes: B60R21