Mechanical lock assembly for a driver side inflator

Abstract: Airbag inflator module assembly (10) including a module housing (14) with a circular aperture having radially extending slots (38) and an inflator (12) with tapered flanges (26) which engage the housing slots (38) upon rotation of the inflator with respect to the housing to clamp an aperture bounding portion of the housing (14) between a radially extending flange of the inflator and the flanges (26). A recess engaging bump may be provided on the flange (26) or the housing (14) to resist counter-rotation of the inflator. The bump may alternatively engage a trailing edge of the flange. A separate bracket may provide rotational engagement with the housing in place of flanges formed integrally with the inflator.

Description: This invention relates generally to inflatable-type modular occupant restraint systems for passenger vehicles or, as they are more commonly known, air bag restraint systems. More particularly, this invention relates to an improved means for quickly securing a driver side inflator to an air bag module. An air bag restraint system typically includes a canister, which has an open side and encloses an inflator and at least part of an air bag, and a cover which conceals the module from view. A driver side air bag module is typically mounted in the center of the steering wheel behind a protective cover. When the air bag module is designed for the passenger side of a vehicle, the container may be located just behind the vehicle dashboard, cosmetic cover, or passenger side instrument panel (hereinafter referred to as "dashboard") and the cover may form an integral part of the vehicle dashboard. When the vehicle is involved in a collision, a crash signal initiates operation of the inflator to cause the air bag to deploy. The inflator produces an inert gas (e.g., nitrogen) which is directed under pressure into the air bag to force the air bag out of the canister incorporated in the module and into the passenger compartment of the vehicle. As the air bag is forced out of the module the pressure exerted on the driver side cover or dashboard causes selected portions of the cover or dashboard to separate, in a predetermined manner along tear seams or breakaway seams (hereinafter referred to as "tear seams" ) to enable the air bag to be directed into the passenger compartment. In the conventional mounting of a driver side air bag inflator to a module housing, the air bag cushion is attached to one side of a module housing with a retainer ring. The air bag inflator is attached to the opposite side of the module housing from the air bag cushion with bolts secured with nuts. The installation of the inflator in an air bag module requires a number of fastening steps and machine steps to secure the inflator, which installation step increases the cycle time for the manufacture of a module. Further, the use of fasteners to attach the inflator to an air bag module is a major cause of reworking of the inflator module assembly due to the necessity of replacing broken or unsecured fasteners. Reworking of the inflator module is not always possible. In these situations the defective modules must be discarded, resulting in lost production and increased manufacturing costs. The elimination of fasteners in the manufacture of the air bag module assembly would eliminate a major cause for reworking and disposal of defective inflator modules. Further, a simplified attachment system which would permit easy removal of the inflator without the need for special tools would reduce the cost and time associated with reworking of the module should removal become necessary. A typical prior art driver side air bag module assembly is described in GB-A-2192841 (on which the pre-characterising of claim 1 is based). This assembly is arranged as described above and utilizes rivets to connect the inflator to other parts of the module assembly. It is an object of this invention to overcome one or more of the problems noted hereinabove. These and other objectives of the invention, which will become apparent from the following description, have been achieved by a novel device for securing an air bag inflator to a module housing as set out in claim 1. The leading edge of the flange may be beveled or angled so as to more easily move against the module housing. A bump or raised portion may be formed in the module housing to prevent the flange and thereby the inflator from rotating backward and becoming disengaged from the module housing. Alternatively, a bump or raised section can be formed on the flange with a corresponding depression in the module housing to lock the inflator in place once rotated into position. In one embodiment of this invention, a number of flanges are attached to the top section of the inflator near the bottom edge. A number of cuts are made radially outward of the inflator-side edge of the module housing and the body of the module housing adjacent to the cut is bent away from the plane of the module housing body in order to form cups or pockets into which the flanges of the inflator may be moved. When the inflator is placed onto the module housing and rotated the flanges engage with the pockets, thereby holding the inflator in place. The pocket may have a bump or raised portion which will engage with the flange to prevent it from moving out of position. In another embodiment of this invention, an L-shaped tab may be attached to or formed from the body of the module housing. A flange, attached to a mounting bracket, which is inserted over the inflator and which secures the inflator, can be rotated in such a manner that the flange on the bracket engages with the L-shaped tab to hold the inflator onto the module housing. In a similar manner an L-shaped tab attached to the edge of the mounting bracket can engage with corresponding slots or apertures formed in the module housing. With this description of the invention, a detailed description follows with reference being made to the accompanying figures of drawings which form part of the specification related thereto, in which like parts are designated by the same reference numbers, and of which: Fig. 1 is a fragmented bottom plan view of the first embodiment of this invention illustrating an inflator locked into position on a module housing; Figs. 2a and 2b are side and top plan views illustrating the inflator of Fig. 1 (Note: Fig. 2a has been simplified to show only one extending flange); Fig. 3 is a cross-sectional view taken along line 3-3 of Fig. 1 illustrating an inflator locked into position on a module housing; Fig. 4 is a fragmented top plan view illustrating the second embodiment of this invention for securing an inflator to a module housing; Fig. 5 is a top plan view of the inflator of Fig. 4; Fig. 6a is a cross-sectional view taken along line 6-6 of Fig. 4 illustrating the flange engaged in the underside of a pocket formed into the module housing at the inflator side edge; Fig. 6b is a cross-sectional view similar to that of Fig. 6a illustrating a tapered flange; Fig. 7 is a top plan view of the third embodiment of the invention illustrating a bracket for holding the inflator onto the module housing; Fig. 8 is a partial view illustrating the third embodiment of this invention; and Fig. 9 is a partial view illustrating the fourth embodiment of this invention. Referring to Figs. 1, 2a, 2b, and 3, a driver side inflator module (with air bag and cover removed) is shown generally at 10 . The driver side module 10 comprises a driver side inflator 12 attached to a module housing 14 . The inflator 12 is composed of a top section 16 with a base plate 18 formed radially outward from the top section side wall 20 adjacent to the bottom edge 22 , and a bottom section 24 with a number of flanges 26 attached thereto and extending radially outward from the bottom section side wall 28 . The module housing 14 has an inflator-side edge 32 formed generally in the center of the module housing body 34 , the inflator-side edge 32 defining an aperture 36 for receiving the bottom section 24 of the inflator 12 . A number of slots 38 formed in the module housing body 34 radially outward of the inflator-side edge 32 and continuous to the aperture 36 . A mounting edge 40 is formed into the module housing 14 for securing the steering wheel cover (not shown). The inflator bottom section 24 is inserted through aperture 36 so that flanges 26 pass through slots 38 in the module housing. The inflator 12 is then rotated thereby clamping the inflator-side edge 32 of the module housing 14 between the flanges 26 and the base plate 18 of top section 16 . To better lock the inflator 12 into position bumps 42 formed onto inflator flanges 26 engage with second apertures 44 formed in the module housing 14 . In a second embodiment as shown in Figs. 4, 5, 6a and 6b, a number of second flanges 46 are attached to the inflator top section 16 adjacent to the bottom edge 22 . The module housing 14 adjacent the inflator-side edge 32 is bent out of the plane 48 of the module housing body 34 to form a pocket 50 having an opening 52 to permit flange 46 to be inserted. The leading edge 54 of second flanges 46 is moved into the pocket 50 when inflator 12 is rotated about its center axis 56 . A second bump 58 on the underside 60 of pocket 50 prevents the second flange 46 from moving backward after the trailing edge 62 of the flange 46 has moved past the second bump 58 . The flange 46 may be tapered as shown in Fig. 6b and the leading edge 54 may becurved 64 as shown in Fig. 5 to better engage with the front edge 66 of pocket 50 . In a third embodiment, as shown in Figs. 7, 8 and 9 a tab 68 with an end section 70 at an angle from the base 72 of tab 68 may be formed in module housing 14 . A retention bracket 74 which is inserted over inflator 12 has a number of bracket flanges 76 attached thereto. The flanges 76 engage with the tab 68 when the retention bracket 74 is rotated into position. Alternately, a bracket tab 78 , as shown in Fig. 9, may be formed into the edge of the retention bracket 74 . The end section 80 of the bracket tab 78 engages with a second slot 82 in the module housing 14 . The module housing 14 can be formed from aluminum, regular carbon steel or heat treated steel. The retention bracket 74 can be formed from regular carbon steel or heat treated steel. To install the inflator 12 of the first embodiment of this invention onto a module housing 14 , the inflator 12 is pressed into place and rotated to engage the flange 26 with the module housing body 34 thereby clamping the module housing 14 between the flanges 24 and base plate 18 . A similar procedure will lock the inflator 12 of the second embodiment onto the module housing 14 . Alternatively, a retention bracket 74 may be used as discussed under the third embodiment. Thus, in accordance with the invention, there has been provided a quick and efficient locking mechanism for securing the inflator onto an air bag module housing without the need of fasteners or special tools.

Claims: An airbag inflator module assembly (10) comprising: an airbag inflator (12) having a first section (16) and a second section (24), each having a substantially circular cross-section, with a base plate (18) extending radially outwardly from a side wall of one of the sections; a module housing comprising a mounting edge (40), a body (14) defining a plane (48) with a top surface and a bottom surface, and an inflator-side edge (32) which defines an aperture (36) for receiving the second section of the inflator which aperture (36) corresponds substantially to the circular cross-section of the second section (24) of the inflator; and engagement means for connecting the inflator (12) to the module housing, characterised in that said engagement means comprises: (a) a plurality of flanges (24, 46) extending radially outwardly from the inflator second section (24) and either a plurality of slots (38) extending radially outwardly from the inflator-side edge (32) of the module housing body (14) or a plurality of pockets (50) formed by bending the module housing body (14) adjacent the inflator-side edge (32) away from the plane of the module housing body (14); or (b) a separate retention bracket (74) inserted over the inflator and comprising a plurality of radially outwardly extending flanges and either a plurality of tabs (68) formed in the module housing body (14) or a plurality of slots (82) formed in the module housing body (14); wherein the inflator (12) is engageable with the module housing body (14) by inserting the inflator second section (24) through the aperture (36) in the module housing body (14) and rotating the engagement means and wherein in the case of engagement means "a" the module housing body (14) adjacent said inflator-side edge (32) is clamped between said flanges (26, 46) and said base plate (18) and in the case of engagement means "b" said base plate (18) is clamped between said retention bracket (74) and said module housing body (14). The assembly (10) as claimed in claim 1 wherein said flanges (26) extend radially outwardly from said inflator second section (24), and said slots (38) extend radially outwardly and continuously from said inflator-side edge (32) such that engagement of said inflator (12) with said housing body (14) causes said flanges (26) to pass through said slots (38) and engage said module housing body (14). The assembly (10) of claim 2 wherein when said inflator (12) is engaged with said housing body (14) each said flange (26) passes through a corresponding one of said slots (38). The assembly (10) of any one of claims 1 to 3 further comprising a bump (42) and depression (44) each formed on one of the bottom of said module housing body (14) adjacent to at least one slot (38) and on a corresponding flange (26), the bump (42) engaging with the depression (44) to lock the inflator (12) in position when said inflator is engaged with said module housing body (14). The assembly (10) of claim 1 wherein a bump (58) is formed on the bottom surface of said module housing body (14) in close proximity to one pocket (50) and wherein after one flange (46) passes the bump (58), its trailing edge (62), which trails upon rotation of the inflator (12), engages with said bump (58) thereby stopping counter rotation of said inflator (12). The assembly (10) of claim 1 or claim 5 wherein each said pocket (50) is open to the inflator-side edge (32). The assembly (10) of claim 1 wherein said engagement means includes said bracket (74) which has an inner aperture which corresponds substantially to the circular cross section of said inflator first section (16), wherein said inflator first section (16) is inserted through the bracket aperture and said bracket (74) is placed in contact with the air bag inflator base plate (18) prior to rotation of said bracket (74) to effect engagement of said bracket (74) with said module housing body (14). The assembly (10) claimed in claim 7 wherein upon rotation of said engagement means said bracket flanges (76) pass under said tabs (70) which are L-shaped and engage therewith to hold said inflator (12) between said bracket (74) and said module housing body (14). The assembly (10) claimed in claim 7 wherein said bracket (74) includes a plurality of L-shaped bracket tabs (78) extending outwardly from a bracket outer edge each of which passes through one said slot (82) in said module housing body (14) upon rotation of said bracket (74) to hold said inflator (12) between said bracket (74) and said module housing body (14). The assembly (10) claimed in claim 1 or claim 5 wherein said engagement means includes said plurality of pockets (50) and each said flange (46) tapers towards its leading edge (54) which leads upon rotation of said inflator (12).

Inventors: JONES DAVID V, JONES, DAVID V, JONES, DAVID V, MORTON INTERNATIONAL, INC.
Applicants: AUTOLIV ASP INC, AUTOLIV ASP, INC.
Application year: 1995
Main classification: B60R21
IPC codes: B60R21