Abstract:
A vehicular air bag assembly includes at least one rib extending from an air bag opening. The rib guides the air bag during deployment. The rib may also support an air bag door. Fingers extending from a panel into the air bag opening may be used to support the air bag door, either together with or instead of the rib. The rib then separates the fingers from the air bag during air bag deployment.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to air bag assemblies used to protect occupants in automotive vehicles. 
     2. Background Art 
     Air bags are being installed in automotive vehicles with increasing frequency. Air bag assemblies typically include an inflatable bag coupled to an inflating device which inflates the bag when appropriate conditions are detected. For example, a front impact of sufficient strength will inflate air bags to protect front seat occupants from head injury. Air bags are typically concealed behind a door built into a panel. The panel may be part of an instrument panel, a door panel, a steering wheel, a headliner, and the like. The panel and door are frequently covered with a skin which protects the air bag assembly and provides a decorative coating for the panel. When the air bag deploys, the air bag door is pushed through the skin. 
     One problem with air bag assemblies is preventing occupant damage to skins and panels by pressing on the skins in the area around the air bag door. This area is typically weaker than surrounding panel areas to permit the air bag door to open. 
     What is needed is an air bag assembly which provides increased support for panels, air bag doors, and covering skins. Such an air bag assembly should be capable of being constructed using typical manufacturing techniques. In addition, the air bag assembly must appropriately guide the air bag during deployment. 
     SUMMARY OF THE INVENTION 
     The present invention provides support for air bag doors and covering skins before air bag deployment. The present invention also guides the air bag through the panel during air bag deployment. 
     A vehicular air bag assembly is provided. At least one air bag deployment door is formed on a panel. A frame defining an air bag opening defined by opening edges is positioned behind the air bag deployment door. A rib extends from at least one opening edge to support the air bag deployment door when the door is in a closed position over the frame opening. An air bag is positioned to deploy through the air bag opening. 
     In an embodiment of the present invention, the rib is positioned to guide the air bag as the air bag deploys. The rib may be an extension of a chute positioned to guide air bag deployment. 
     In another embodiment of the present invention, the rib extends substantially around at least three sides of the air bag opening. 
     In still another embodiment of the present invention, the at least one air bag deployment door includes a metal backing plate on an inside portion of the door and a skin on an outside portion of the door. The deployment door may be part of a panel assembly such as an instrument panel, a door panel, or the like. The skin may be formed as part of the panel assembly. A spacer layer may be formed between the metal backing plate and the skin. 
     In a further embodiment of the present invention, fingers on the panel support the air bag door when the door is closed. The rib may separate the fingers from the air bag during air bag deployment. 
     A method of making a vehicular air bag assembly is also provided. A panel is formed to be part of the interior of a vehicle. The panel defines an air bag opening. A door assembly is fastened to the panel outer face. The door assembly includes an air bag door positioned over the air bag opening. An air bag chute is formed having a chute opening and a rib extending from the chute opening. The air bag chute is fastened to the panel inner face such that the chute opening aligns with the air bag opening and such that the rib supports the air bag door. An air bag module is fastened to the panel such that the air bag, when deployed, travels down the air bag chute, through the chute opening, through the air bag opening and through the air bag door. 
     Another method of making a vehicular air bag assembly provides for forming a panel defining at least one finger extending into the air bag opening. The door assembly is fastened to the panel outer face so as to be supported by the at least one finger. An air bag chute is formed having a chute opening and a rib extending from the chute opening. The air bag chute is fastened to the panel interface such that the chute aligns with the air bag opening and such that the rib separates the at least one finger from the chute opening. An air bag module is fastened to the panel such that the air bag, when deployed, travels down the air bag chute, through the chute opening, through the air bag opening, and through the air bag door without contacting the at least one finger. 
     The above objects and other objects, features, and advantages of the present invention are readily apparent from the following detailed description of the preferred embodiments when taken in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an air bag chute according to an embodiment of the present invention; 
         FIG. 2  is a perspective view of an air bag chute and module assembly according to an embodiment of the present invention; 
         FIG. 3  is an exploded view drawing of a panel assembly including an air bag chute according to an embodiment of the present invention; and 
         FIG. 4  is a cross-sectional drawing of an air bag assembly according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to  FIG. 1 , a perspective drawing of an air bag chute assembly according to an embodiment of the present invention is shown. An air bag chute assembly, shown generally by  20 , includes frame  22  defining an air bag opening  24 . Air bag opening  24  is defined by edges, one of which is indicated by  26 . In the embodiment shown, air bag opening  24  is rectangular in shape and is therefore defined by four edges  26 . However, any shape for air bag opening  24  falls within the spirit and scope of the present invention. 
     Air bag chute assembly  20  includes chute guide  28 . In the embodiment shown, chute guide  28  is U-shaped, extending around three edges  26  of air bag opening  24 . Chute guide  28  is attached to frame  22  so as to form lips  30  extending from edges  26  in air bag opening  24 . Alternatively, lips  30  may be formed independently of chute guide  28 . In the embodiment shown, three edges  26  of air bag opening  24  include lip  30 . 
     Frame  22 , chute guide  28  and lip  30  are preferably made from engineering material, such as steel. In the embodiment shown, chute guide  28  defining lips  30  is spot-welded to frame  22 . Holes, one of which is indicated by  32 , and slots, one of which is indicated by  34 , permit air bag chute assembly to be attached to other elements of a vehicular air bag assembly. 
     Referring now to  FIG. 2 , a perspective view of an air bag chute and module assembly according to an embodiment of the present invention is shown. An air bag chute and module assembly, shown generally by  40 , includes air bag chute assembly  20  and air bag module  42 . Air bag module  42  typically includes an air bag and a canister for inflating the air bag, both of which have been omitted for clarity. Air bag housing  44  encloses the air bag and canister. Air bag housing  44  includes canister portion  46  for holding the canister. Canister portion  46  defines access opening  48  accepting control signals for controlling the canister. Extending from canister portion  46  are air bag walls  50  holding the collapsed air bag. 
     Air bag module  42  slides into air bag chute assembly  20  so that air bag walls  50  extend partially along chute guide  28 . This allows chute guide  28  to channel the air bag when the air bag is deployed. Air bag housing  44  includes attachment plate  52  extending from one air bag wall  50 . Attachment plate  52  includes slots which align with air bag chute assembly slots  34  when air bag module  42  is slid into air bag chute assembly  20 . 
     Referring now to  FIG. 3 , an exploded view drawing of a panel assembly including an air bag chute according to an embodiment of the present invention is shown. A panel assembly, shown generally by  60 , includes panel  62  defining air bag opening  64 . Panel  62  shown in  FIG. 3  forms part of an instrument panel assembly. As will be recognized by one of ordinary skill in the art, the present invention applies to a wide variety of air bag applications including panels in doors, steering wheels, headliners, pillars, seat backs, and the like. 
     Panel assembly  60  also includes door assembly  66 . Door assembly  66  includes air bag door  68  connected to door support  70  by a plurality of hinges, one of which is indicated by  72 . Hinges  72  allow air bag door  68  to rotate or open relative to door support  70 . Door assembly  66  also includes reinforcement strip  74 . Door assembly  66  may be formed from any engineering material such as plastic or metal, but is preferably formed from stamped steel. 
     Panel assembly  60  further includes air bag chute and module assembly  40  positioned in air bag opening  64 . Door assembly  66  is positioned over panel  62  such that air bag door  68  is over air bag opening  64 . When the air bag deploys, the air bag expands through air bag opening  64  and pushes open air bag door  68 . 
     Reinforcement strip  74  defines a plurality of holes  76 . Similarly, panel  62  defines a plurality of corresponding holes  78 . Holes  76 ,  78  align with holes  32  in air bag chute assembly  20 . Fasteners  80  pass through holes  76 ,  78 ,  32  to attach reinforcement strip  74 , panel  62  and air bag chute and module assembly  40 . Door support  70  defines holes  82 . Panel  62  defines corresponding holes  84 . Holes  82 ,  84  each align with slot  34  on air bag chute assembly  20  and the mating slot on air bag module  42 . Fastener  86  passes through holes  82 ,  84  and corresponding slots in air bag chute and module assembly  40  to attach door support  70 , panel  62  and air bag chute and module assembly  40 . Fasteners  80 ,  86  are preferably bolts onto which nuts, not shown, are tightened. However, other forms of mechanical attachment are readily known in the art. 
     Lip  30  on air bag chute assembly  20  guides the air bag through panel  62  upon air bag deployment. In one embodiment, lip  30  also provides support for air bag door  68  when air bag door  68  is in the closed position. Alternatively, or in addition to lip  30 , one or more fingers  88  may be formed on panel  62  extending into air bag opening  64 . Air bag door  68  rests on each finger  88  when air bag door  68  is in the closed position. In this embodiment, lip  30  prevents the air bag from breaking finger  88  when the air bag deploys through air bag opening  64 . 
     Referring now to  FIG. 4 , a cross-sectional drawing of an air bag assembly according to an embodiment of the present invention is shown. An air bag assembly, shown generally by  100 , includes air bag canister  102  and air bag  104  within air bag module  42 . Air bag canister  102  sits in canister portion  46 . A typical air bag canister is model P4.4 inflation cylinder from TRW. Air bag  104  sits within air bag walls  50 . Air bag  104  may be attached to an inside surface of air bag door  68  or may be unattached to door  68 . 
     Air bag assembly  100  may include skin  106  covering air bag door  68  and panel  62 . Skin  106  protects panel  62  and provides decorative coating. Skin  106  may be constructed as a spray urethane aromatic. Foam layer  108  separates skin  106  from door  68  and panel  62 . Foam layer  108  may be formed with urethane foam. 
     In the embodiment illustrated in  FIG. 4 , door  68  is supported by lips  30  of air bag chute assembly  20  as well as fingers  88  extending from panel  62 . In addition, lips  30  separate fingers  88  from air bag  104 . When air bag  104  deploys through door  68 , air bag  104  will not break fingers  88  from panel  62 . 
     Panel  62  may be molded or stamped from any suitably rigid engineering material such as, for example, Dylark® from Nova Chemicals Corporation. The design of air bag module  42  depends upon the placement of air bag assembly  100  within a vehicle, the impacts expected on inflated air bag  104 , and the like. Air bag modules  42  are available from a variety of manufacturers, such as TRW, Autolive, Takata, and the like. 
     Fasteners  80 ,  86  are placed through door assembly  66  and panel  62 . Fasteners  80 ,  86  may be permanently attached to door assembly  66 , may be held by adhesive to door assembly  66 , or may include mechanical snap mechanisms to temporarily or permanently hold fasteners  80 ,  86  to door assembly  66 . Panel  62 , together with door assembly  66 , is placed in a fixture spaced apart from skin  106 . Foam layer  108  is then formed between skin  106  and panel  62  by a “foam-in-place” process as is well known in the art. Air bag chute assembly  20  is placed over fasteners  80 , 86 . Air bag module  42  is slid into chute guide  28  and onto fasteners  86 . Bolts are placed on fasteners  80 ,  86  to complete air bag assembly  100 . 
     While embodiments of the invention have been illustrated and described, it is not intended that these embodiments illustrate and describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention.