Air bag retention system
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a new and improved air bag retention system designed to positively hold and retain the inlet or filling end of the air bag from movement down a deployment chute toward a panel opening during rapid inflation of the air bag when deployed in an emergency. 
     2. Background of the Prior Art 
     One of the problems associated with the rapid deployment of air bag safety cushions in motor vehicles is the fact that sometimes the inlet end or filling end of the air bag becomes loose or detached from the adjacent fixed member of the air bag system allowing the whole bag to move away from the source of filling gas so that the full and rapid inflation of the air bag does not take place. 
     Futile efforts have been made to find ways for retaining the inlet end of an air bag which are both operationally effective and also cost effective, but particularly in the latter case such retaining systems tend to greatly complicate the structures involved and the initial assembly process. 
     U.S. Pat. No. 5,326,131 discloses an air bag mounting structure which requires multiple fasteners, requires retaining projections to be struck from the wall of a retaining enclosure and which requires the formation of slots or openings in the air bag through which the projections must pass. 
     U.S. Pat. No. 4,842,300 discloses a vehicle air bag module with an internal reinforcing bar requiring holes in the air bag fabric and adjacent components to accommodate multiple fasteners. 
     U.S. Pat. No. 5,255,937 discloses a vehicle air bag with a continuous frame retainer requiring multiple fasteners in the form of rivets to be utilized along with the necessary rivet holes and installation procedures. 
     U.S. Pat. No. 5,195,775 discloses a vehicle air bag module employing a continuous inner frame that is riveted in place to hold the gas inlet end of an air bag in place. 
     Japanese patent publication 4-146840(A) discloses an air bag system having an air bag with an inlet end retained in place around an inflator canister with a flange and multiple fasteners. 
     OBJECTS OF THE INVENTION 
     It is an object of the present invention to provide a new and improved air bag retention system which does not require the use of separate fasteners to secure in place the inlet or gas filling end of the air bag during deployment. 
     Another object of the present invention to provide a new and improved air bag retention system which requires no holes, slots or apertures to be formed in the air bag itself and none in the surrounding structure for retaining the inlet or filling end of the air bag in place during deployment. 
     Still another object of the present invention to provide a new and improved air bag retention system which is exceptionally easy to assemble and install in a motor vehicle behind a panel opening therein. 
     A still further object of the present invention to provide a new and improved air bag retention system which employs at least one external pocket formed on the outside surface adjacent the inlet or filling end of an air bag which receives a retainer tab of a delivery chute for directing the inflating air bag toward a panel opening in the vehicle. 
     Another object of the present invention to provide a new and improved air bag retention system which is economical and relatively simple in construction and installation and which is extremely reliable in operation. 
     BRIEF SUMMARY OF THE PRESENT INVENTION 
     The foregoing and other objects and advantages of the present invention are accomplished in a new and improved air bag retention system for securing a gas inlet or filling end of an inflatable air bag cushion during deployment along a delivery chute extended toward a panel opening in a motor vehicle. The air bag includes at least one pocket on an outside surface opening toward the panel, and the delivery chute includes a cooperative retaining tab having a free end extending into the external pocket on the air bag, toward the inlet end for preventing the inlet end from moving out of said chute during rapid inflation thereof as the inflation gas flows rapidly in to fill the air bag cushion. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a better understanding of the present invention, reference should be had to the following detailed description taken in conjunction with the drawings, in which: 
     FIG. 1 is a longitudinal cross-sectional view taken through a panel in a motor vehicle in which is installed a new and improved air bag retention system in accordance with the features of the present invention; 
     FIG. 2 is a fragmentary view taken substantially along lines 2--2 of FIG. 1 illustrating the unique structure for positively holding and retaining movement of the air bag during rapid inflation thereof; 
     FIG. 3 is a back side perspective view of a diffuser wall and delivery chute of the system looking in the direction of Arrows 3--3 of FIG. 1; and 
     FIG. 4 is a cross-sectional view similar to FIG. 1, but illustrating the air bag of the system in an inflated condition for cushioning an occupant of a motor vehicle. 
    
    
     DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION 
     Referring now more particularly to the drawings in FIGS. 1 and 4 is illustrated a new and improved air bag retention system 10 constructed in accordance with the features of the present invention and designed for installation behind a panel opening 12 formed in a panel 14 of a passenger compartment 16 in a motor vehicle. The system 10 includes an inflatable air bag 20 formed of thin, flexible sheet material and designed to be rapidly inflated with gas (FIG. 4) for providing a protective resilient cushion for a vehicle occupant in an emergency. 
     The air bag 20 is normally retained in a folded-up condition (FIG. 1) inside a delivery chute 22 having a peripheral mounting flange 24 around an open, upwardly and rearwardly directed end facing an occupant in the passenger compartment sitting rearward of the panel opening 12 in the vehicle. The delivery chute 22 has a generally rectangular transverse cross-section on a plane parallel of the peripheral mounting flange 24 and is bounded by a pair of spaced apart, opposite side walls 26 and a pair of opposite, spaced apart, vertical end walls 28 integrally joined to the side walls at rounded corners 29 as shown in FIG. 3. 
     In accordance with the present invention, the delivery chute 22 is open at a forwardly and downwardly facing end in direct communication with a housing 30 that is fixedly mounted in the vehicle by fasteners 32 extending horizontally along opposite sides of the housing. The fasteners 32 are supported from brackets or other suitable supports (not shown) provided in the motor vehicle beneath the panel 14 at opposite ends of the air bag deployment opening 12. 
     The rearwardly and upwardly facing open end of the housing 30 is formed with a pair of mounting flanges 34 that provide strength and stiffness for the structure and these flanges are bent outwardly around the horizontal fasteners 32 to positively position and secure the housing in place as shown in FIGS. 1 and 4. A forwardly facing end portion of the housing 30 is closed off and is adapted to rearwardly deflect (Arrows &#34;A&#34;--FIG. 4) hot gas that is generated in an air bag inflator 36 mounted in the housing. When the inflator 36 is activated by an electrical signal during an emergency, gas generant material contained therein is ignited and hot gases flow rapidly out through ports 38 formed in a canister or body 40 of the inflator to rapidly inflate the air bag 20 for cushioning a vehicle occupant to reduce injury. 
     In order to more evenly distribute the flow of generated gas moving rapidly out to inflate the air bag 20, a diffuser 42 having a plurality of perforations 44 is provided to extend across the open end of the housing 30 between the inflator 36 and the air bag. The diffuser 42 has a generally flat, rectangular-shaped main wall 46 with integrally formed, flanged edge structures 48 extending horizontally along opposite edges providing a pair of rearwardly and upwardly facing edge recesses 50. Similar but shorter in length flanged end structures 52 are formed at opposite ends of the main perforated wall 46 providing rearwardly facing end recesses 54. The edge recesses 50 and end recesses 54 are generally U-shaped in transverse cross-section and each includes an inner flange wall 56 at right angles to the main wall 46 and a spaced apart outer flange wall 58 integrally joined by a curved bottom wall 60 forming the end or bottom of a recess 50 or 54 that is open at the opposite end facing the panel opening 12. 
     In accordance with the present invention, the air bag 20 has a closed outer end 20a and an open inlet or filling end 20b for receiving hot gas from the perforations 44 of the diffuser 42 when the inflator 36 is activated as shown by the Arrows &#34;B&#34; in FIG. 4. In order to positively secure and hold the open end 20b of the air bag 20 in place within the delivery chute 22 during air bag deployment, a plurality of pockets 62 of generally rectangular shape (FIG. 2) are formed on the outside surface of the air bag fabric by lines of stitching 64 or other fastening means. Each pocket 62 has a rearwardly and upwardly facing open end 66, side edges formed by stitching lines 64 and a closed bottom 68 formed by a fold line. 
     The delivery chute 22 is formed with a plurality of integral retaining tabs 70 along the lower edges of the side walls 26 spaced apart by grooves 72 (FIG. 2) so that each tab can fit into a pocket 62 on the inlet end 20b of the bag 20 and thereby insure that the inlet end of the bag does not collapse or close during rapid air bag inflation and that the inlet end of the bag is positively retained in the delivery chute upon air bag deployment. 
     In accordance with the present invention, the air bag system 10 does not require fasteners such as rivets, bolts, etc., to assemble the components thereof and in addition the unique design provides for easy and rapid installation in a motor vehicle. As illustrated in FIGS. 2 and 3, the tabs 70 of the delivery chute 22 are extended into the outer pockets 62 along the inlet end 20b of the air bag 20. The diffuser 42 is then assembled onto the chute 22 and the air bag 20 with the air bag pockets 62 receiving the tabs 70 and both projecting into the recesses 50. The inner and outer walls 56 and 58 of the flanged edge structures 48 and 52 are then crimped toward each other to pinch and hold the air bag 20, the diffuser 42 and the chute 22 together permanently. These assembled components are then moved into the open end of the housing 30 through the panel opening 12 until the outer walls 58 of the flanged edge structures are forced or press-fitted tightly against adjacent inside surfaces of the housing wall at the open end. 
     Installation of the assembled diffuser 42, air bag 20 and delivery chute 22 into the housing 30 as described is accomplished with a unidirectional thrust generally indicated by the Arrow &#34;C&#34; in FIG. 1, and the direction of thrust is parallel to the tabs 70. The outer perimeter flange 24 of the air bag delivery chute 22 is provided with a plurality of unidirectional, self-locking type, expandable fasteners 74 which extend through openings 76 in the flange and appropriately located openings in the panel 14 along the edges of the panel opening 12. Suitable, expandable, self-locking, unidirectional thrust-type fasteners 74 are disclosed in copending U.S. patent applications Ser. Nos. 08/505,592 and 08/505,793, both filed Jul. 21, 1995, which applications are both assigned to the assignee herein and which applications are incorporated herein by reference. 
     The air bag 20 is protected in the folded-up condition in the delivery chute 22 as shown in FIG. 1, by a frangible panel door or cover 80 which breaks open under the pressure of the rapidly inflating air bag 20 as shown in FIG. 4. The cover has inturned flanged edges 80a along upper and lower horizontal sides which are sandwiched between the perimeter flange 24 of the delivery chute 22 and the upper surface of the panel 14 along the edges of the panel opening 12. The expandable, self-locking, unidirectional fasteners 74 positively secure the cover 80, the delivery chute 22 and the air bag 20 in a protected position until air bag deployment occurs. 
     Obviously, many modifications and variations of the present invention are possible in light of the above teachings. Thus, it is to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described above.