Retention Structure for a Flange Based Inflator of an Airbag Restraint Assembly

This invention relates to vehicle airbag restraint systems, and more particularly to a mounting structure for mounting an inflator which is shorter than a reaction can of an airbag restraint assembly in the reaction can of such an assembly.

A vehicular airbag restraint system generally includes a pyrotechnic inflator which may comprise a cylindrical housing which encloses some form of gas generating material which, when ignited, generates a non-toxic inert gas under pressure within the housing. The inflator, along with an uninflated, folded airbag which is to be inflated by the gas, is disposed in an internal cavity of a reaction can along with means to control deployment. In an emergency situation inert gas is generated in the inflator housing and the gas is directed rapidly through a plurality of nozzles formed in the inflator housing and into the airbag to force the airbag out of the reaction can to inflate the airbag. One location for such a vehicular airbag restraint system is in the instrument panel or dashboard on the passenger side of the vehicle for passive protection of a passenger in the vehicle.

Some inflators are constructed with a flanged base at one end of the cylindrical housing. In many cases, packaging and weight limitations may require airbag inflators to be shorter than the reaction cans in which they are housed. This situation requires an inflator to reaction can interface that is cost effective, durable and squeak- and rattle-free.

Accordingly, it is an object of this invention to provide a new and improved mounting structure for mounting a flange based inflator, which is shorter than a reaction can, in the reaction can of an airbag restraint system which structure produces a mounting interface that is squeak and rattle resistant and provides a seal against the escape of gas on deployment of an airbag of the assembly.

Another object of this invention is to provide a new and improved structure for mounting an inflator in a reaction can of a vehicle airbag restraint system which is easy to install, cost effective, and durable as well as squeak- and rattle-free.

In carrying out this invention in one illustrative embodiment thereof, a mounting structure is provided for mounting an inflator in a reaction can wherein the inflator is shorter than the reaction can of a airbag restraint system in which the inflator is mounted. The inflator, which is to be positioned in a cavity of a reaction can through an access opening in one end of said reaction can, has a flanged base on a first end thereof, generally the squib end of the inflator. A mounting means is located or positioned in the opening of the reaction can, said mounting means being a generally right circular cylindrical shaped, open tube, the sidewall of which terminates on one end thereof with a circular mounting flange extending radially outward from the sidewall and on the other end thereof terminates in an inwardly tapered conical flange, preferably, in a joggle terminating in said inwardly tapered conical flange. The mounting means is located or positioned in the access opening at one end of the reaction can with the mounting flange abutting the exterior side of the reaction can end wall having the access opening. The mounting means extends into the reaction can through the access opening in the reaction can end wall. As installed, the sidewall, joggle, and inwardly tapered conical flange extend into the cavity in the reaction can. On installation of the inflator, the end of the inflator opposite the flanged base is passed through the opening in the mounting means and through the joggle and inwardly tapered conical flange until the flanged base on the end of the inflator rests against the joggle. The inward taper of the conical flange provides a lead-in for press fit of the inflator housing to the conical flange, thereby providing an anti-rattle retention of the flanged based inflator in the reaction can cavity.

The invention, together with further objects, aspects, features and advantages thereof will be more clearly understood from the following description taken in connection with the accompanying drawings.

FIG. 1 is a front elevational view of a reaction can partly broken away, showing a flanged base inflator mounted therein in accordance with the present invention.

FIG. 2 is a side elevational view of FIG. 1 viewed from the right side of FIG. 1.

FIG. 3 is an enlarged cross-sectional view taken along lines 3--3 of FIG. 1 .

Referring to FIGS. 1 and 2, a reaction can 10 houses an inflator 12 therein along with a folded airbag (not shown) to form an airbag restraint system. The reaction can 10 houses the inflator in an internal cavity 14 formed therein. Reaction can 10 forms cavity 14 by means of sidewalls 16 and 18, generally parallel end walls 20 and 22 and bottom wall 24.

The present invention is directed to mounting the inflator 12 in the reaction can 10 in a manner such that the inflator is retained in the reaction can in an essentially shake- and rattle-free manner despite the fact that the inflator 12 is shorter in length than the length of the reaction can 10.

The inflator 12 includes a generally circular cylindrical housing 26 terminating at a first end in a flanged base 30 and terminating at the other end in a protruding threaded stud 32. The length of the inflator 12 is less than the distance between the end walls 20 and 22 of reaction can 10. Base flange 30 has a base shroud 28 element whereby the flange base 30 is attached to inflator housing 26.

The inflator is mounted in cavity 14 of reaction can 10 by mounting device or means 34. Mounting means 34 is an open generally cylindrical, circular tube having an opening or passage 36 therethrough formed by generally right circular cylindrical sidewall 38. The mounting device 34 has, at one end thereof, a cylindrical mounting flange 40 extending radially outward and at the other end an inwardly tapered conical flange 44, and preferably a formed joggle 42 terminating in said inwardly tapered conical flange 44, as best seen in FIG. 3. The radially inward (inboard) edge 46 of the tapered conical flange 44 forms a generally circular opening which is adapted to receive, engage and hold the inflator shroud 28 such that inflator flange base 30 tightly abuts joggle 42. The inside diameter of tapered conical flange 44 is slightly smaller than the outside diameter of shroud 28 so that a biased press fit is formed between tapered conical flange 44 and base shroud 28. The taper of the conical flange 44 provides a lead-in for the press fit of the tapered conical flange 44 to the inflator base shroud 28.

Mounting means 34 is placed in a suitable complimentary access opening in end wall 20 of reaction can 10 such that mounting flange 40 abuts against end wall 20, with sidewall 38, joggle 42 and conical flange 44 of mounting means 34 extending into cavity 14 of the reaction can 10. Mounting flange 40 is secured to end wall 20 by any suitable securing means, such as for example, with bolts, screws or by welding.

Although the mounting device 34 is being described as a discretely formed element that is inserted into the access opening in end wall 20 and suitably secured to said end wall 20, it will be appreciated that mounting device 34 can be formed as an integral, i.e. unitary, part of the end wall 20 of the reaction can 10.

On installation inflator 12 is inserted through opening 36 in mounting means 34 in a manner in which the end of the inflator axially opposite flanged base 30, i.e. the end of the inflator terminating in protruding threaded stud 32, is first longitudinally passed into and through the opening 36 and through conical flange 44 until inflator base flange 30 abuts and rests against joggle 42. Conical flange 44 receives and engages inflator base shroud 28 in such a manner that base flange 30 is kept in abutting relationship to joggle 42, thereby preventing any further forward movement of the inflator 12 into the cavity 14 of the reaction can 10, and the inner circumferential edge 46 of conical flange 44 grips and retains the inflator shroud 28 in a manner to prevent any substantial movement of the inflator in a rearward direction.

A secondary retention action occurs when any attempted rearward movement of the inflator 12 causes the inner edge 46 of the tapered conical flange 44 to dig into base shroud 28. The clamping face of the tapered conical flange 44 on base shroud 28 may be modified by adding cutting teeth or scallops to the inner edge 46 of the tapered conical flange 44. If desired, relief slots may be placed in tapered conical flange 44 to modify the binding force of inner edge 46 on shroud 28.

At the other end wall 22 of the reaction can 10 a cup mounting means 48 may be employed for longitudinal centering and primary retention of the inflator 12 in the reaction can 10. Cup mounting means 48 is placed in an access opening in end wall 22, with radially extending collar 50 of said cup means 48 abutting the outer surface of end wall 22. Cup means 48 has a flat bottom 52 with a shaped hole 54 thereto adapted to receive the threaded stud 32 and any index key on the threaded stud end of the inflator 12. A nut 56 is threaded onto the stud 32 thereby clamping the cup bottom 52 between the nut 56 and the end of the inflator 12. An indexing key (not shown) may be provided on the threaded stud end of the inflator to provide proper orientation of a plurality of nozzles (not shown) in the cylindrical outer housing 26 of the inflator 12 to permit proper inflation of a folded airbag (not shown) in the reaction can. Such indexing means are known in the art for achieving such proper orientation of the nozzles.

Although a mounting cup 48 may be employed at end wall 22 such a cup is not required. Rather, threaded stud 32 and any index key may simply be placed into complimentary shaped openings in end wall 22 and nut 56 is then threaded onto the stud 32 thereby clamping end wall 22 between nut 56 and the end of inflator 12. As with mounting means 34 it will be appreciated that cup means 48 may be a discretely formed element or may be formed as an integral, i.e. unitary, part of end wall 22.

The length of sidewall 38, joggle 42 and tapered conical flange 44 will be selected to securely engage the flange based inflator in the manner described, i.e. with inflator flange base 30 abutting joggle 42, tapered conical flange 44 engaging base shroud 28 and threaded stud 32 protruding through shaped hole 54 such that nut 56 can be threaded onto said stud 32.

Appropriate inward tapering of tapered conical flange 44 and the hoop stress produced by radial stretching of the circumference of inner edge 46 of tapered conical flange 44 will prevent or substantially eliminate any squeaks or rattles from occurring throughout the life of the installation.

The radial tensile strength or radially compressive forces of the inner edge 46 of the tapered conical flange 44 when the inflator is inserted therethrough, in the manner described hereinbefore, provides a reliable and long-lasting method of retaining a flange based inflator in a reaction can when the inflator is shorter in length than the length of the reaction can. In addition, the essentially 360.degree. contact between the inner edge 46 of tapered conical flange 44 against inflator base shroud 28 provides a seal against gross gas escape at deployment. A further significant advantage of the mounting means of this invention resides in the fact that the circular cylindrical configuration of the mounting device 34 is cost effective because it lends itself to low cost fabrication methods.

Accordingly, the mounting structure of the present invention provides an excellent centering and retaining device where the inflator has a flanged base and the inflator has a dimension that is shorter than that of the reaction can into which it is to be installed. Radial compressive forces of the inwardly tapered conical flanged end of the mounting device on the inflator shroud provides a reliable and long-lasting method of retaining the inflator in an essentially squeak- and rattle-proof arrangement. Also, the contact between the mounting device 34 and the inflator 12 is such that, in addition to the centering and retaining qualities, the contact provides a seal against gas escape at deployment of the airbag of the airbag restraint assembly. The mounting structure is simple to install and cost effective in fabrication.

Additionally, the recessed cup-like structure of mounting device 34 provides for wire protection around the flanged base end, i.e. squib end, of the inflator. Also, cup 48 permits stud 32 and nut 56 to be recessed from end wall 22 at the other end of inflator 12.

Since other changes and modifications to fit particular operating requirements and environments will be apparent to those skilled in the art, the invention is not considered limited to the examples chosen for purposes of illustration and includes all changes and modifications which do not constitute a departure from the true spirit and scope of this invention as claimed in the following claims and equivalents thereto.