Abstract:
An air bag module comprises an air bag having an interior cavity. The air bag has an air bag opening in communication with the interior cavity. The air bag module has an air bag inflator with an outlet for inflating the air bag. At least one vane extends from the air bag opening into the interior cavity of the air bag.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to a passenger side air bag module. 
     An air bag module typically comprises an air bag and an air bag inflator. When a severe crash is detected by a vehicle&#39;s crash detection system, the system may instruct the air bag module to deploy. If this event occurs, the air bag inflator rapidly discharges an inflation gas at a very high temperature into the air bag. The high temperature of the gas causes its rapid expansion, thereby inflating the air bag to form a cushion against vehicle impact for a vehicle occupant. Preferably, the air bag should deploy towards the vehicle occupant to maximize cushioning. However, challenges arise in the design of an air bag module for a passenger side air bag. Specifically, due to the shape of passenger side air bag inflators, inflation gas from the air bag inflator may discharge toward the side of the vehicle occupant. As a consequence, the air bag may deploy toward the side of the vehicle occupant rather than in the direction of the occupant. 
     Manufacturers have sought to overcome this design challenge by using a vent to redistribute the flow of inflation gas across the mouth of the air bag through guide structures, such as holes or vanes, located between the air bag inflator and the air bag. Vent holes are not very effective in redistributing air flow. Moreover, the vanes that manufacturers currently use extend between the air bag inflator and the air bag and are located outside of the air bag. Applicant has discovered that these vanes draw heat away from the inflation gas and consequently reduce its ability to expand the air bag. 
     A need therefore exists for an air bag module that redirects the flow of inflation gas towards the vehicle occupant without significant heat loss. 
     SUMMARY OF THE INVENTION 
     The present invention comprises an air bag module, having an air bag and air bag inflator. The air bag has an interior cavity and an air bag opening leading into the interior cavity. In the event of air bag deployment, the air bag inflator discharges an inflation gas out of an outlet generally to the side of the vehicle occupant. A vane then redirects the flow of inflation gas so that the air bag may deploy toward the vehicle occupant. In contrast to existing air bag modules, however, the vane of the inventive air bag module extends from the air bag opening into the interior cavity of the air bag. In this way, the vane is located completely within the insulating confines of the air bag. This unique location for the vane reduces heat loss significantly. Accordingly, the vane allows the inflation gas to maintain its high temperature within the air bag while still redirecting the air bag towards the vehicle occupant. 
     The vane is located near the air bag opening. Moreover, to further reduce temperature loss, the vane is sized smaller than the air bag opening. The vane may have a dimension, such as a width, less than a dimension of the air bag opening, such as an opening width. By reducing the size of the vane relative to the air bag opening, the high temperature of the inflation gas is further maintained. 
     A support may be used to hold the vanes in place relative to the air bag. The support may comprise a number of vanes each spaced next to an air bag opening. To reduce heat loss, the air bag may be attached around the support. The support may be rectangular in shape. In addition, pressure relief holes may be provided in the support to adjust the distribution of inflation gas across the air bag opening. 
     The invention further encompasses an inventive manufacturing technique. A vane is placed next to an air bag opening on a support. Rather than placing the vane outside of the air bag, the vane is extended into the air bag. The air bag is then attached around the support. This technique thus permits inflation gas to be directed toward the vehicle occupant without a significant loss of heat. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the currently preferred embodiment. The drawings that accompany the detailed description can be briefly described as follows: 
         FIG. 1  illustrates a cross-sectional view of the inventive air bag module, including air bag, air bag inflator, and vanes extending from the air bag opening into the interior cavity. 
         FIG. 2  illustrates a perspective view of the vanes of FIG.  1 . 
         FIG. 3  illustrates a bottom view of the inventive air bag module of FIG.  1 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 1  illustrates inventive air bag module  10  comprising air bag  14  and air bag inflator  30 . Like existing air bag modules, air bag  14  has an exterior surface  22  that defines an interior cavity  18 . Moreover, air bag inflator  30  has outlets  34 , which, during deployment, direct inflation gas along the direction of path A. Path A may be at a 30° angle to an axis of inflator  30 , axis X. Without guide structures, air bag  18  would tend to deploy generally along the direction of path A. 
     To address this issue, air bag module  10  has support  46  to redirect the flow of inflation gas from air bag inflator  30 . Air bag support  46  has air bag openings  26  that permit the passage of inflation gas into interior cavity  18  from outlets  34  of air bag inflator  30 . In addition, support  46  has vanes  38  that extend at an angle relative to support  46  as shown. The disclosed angle is approximately 60° or a 120° angle relative to axis X. As further shown in  FIG. 1 , each vane  38  is located adjacent each air bag opening  26 . As a consequence of the location of vanes  38  relative to air bag openings  26 , inflation gas passes through air bag openings  26  along vanes  38  in the direction of path B, a path transverse to path A. The net effect is to cause air bag  14  to expand in the direction of path C towards a vehicle occupant. Because vanes  38  completely or entirely extend from air bag openings  26  into interior cavity  18  as illustrated, heat loss is significantly minimized. Air bag  14  and hot inflation gas within air bag  14  insulates vanes  38  and allows the inflation gas to maintain its high temperature to optimally expand air bag  14 . 
     In further contrast to existing air bag modules, the inventive air bag module  10  has vanes  38  sized smaller than air bag openings  26 . As shown in  FIG. 2 , support  46  comprises planar member  48  having air bag openings  26  located adjacent to vanes  38 . Vanes  38  have width V w  while air bag openings have air bag opening width O w . Here, V w  is preferably less than O w . Also, the length of vanes V L  is preferably less than the length of openings O L . In this way, heat loss through vanes  38  is further minimized by keeping vanes  38  smaller than air bag openings  26 . 
     In addition, support  46  has pressure relief holes  50 . As shown in  FIG. 1 , pressure relief holes  50  are located between outlets  34  and air bag interior  18 . Although not effective in redirecting inflation gas flow, pressure relief holes serve to improve the distribution of inflation gas around outlets  34 . The size and location of pressure relief valves will vary with the pressure from air bag inflator  30  and the location of outlets  34 . 
     In addition, support  46  has bolt holes  62  that receive bolts  58 . As shown in FIG.  1  and  FIG. 3 , air bag  14  is attached to support  46  by a bolt  58  and nut  66  connection. It should be noted that air bag  14  surrounds support  46  to prevent the leakage of inflation gas around support  46  as well as to maintain the high temperature of inflation gas within interior cavity  18  of air bag  14 . 
     Thus, air bag module  10  is made by placing vanes  38  adjacent to air bag openings  26 . Vanes  38  completely are extended into interior cavity  18  of air bag  14 . Air bag  14  is then attached around support  46 . Support  46  preferably comprises a metal to withstand the high temperature of the inflation gas. Support  46  may be produced by stamping, such as by a progressive die. Notch  54  may be provided to assist the movement of support  46  within the progressive die. 
     The aforementioned description is exemplary rather that limiting. Many modifications and variations of the present invention are possible in light of the above teachings. The preferred embodiments of this invention have been disclosed. However, one of ordinary skill in the art would recognize that certain modifications would come within the scope of this invention. Hence, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described. For this reason the following claims should be studied to determine the true scope and content of this invention.