Abstract:
An example airbag assembly includes an airbag and a duct. The duct has a duct opening for venting gas. The duct is moveable between a first position where the duct opening is outside the airbag and a second position where the duct opening is inside the airbag. Inflating the airbag moves the duct between the first position and the second position. The airbag is configured to be inflated by a first stream of gas moving from the duct opening to an interior of the airbag and by a second stream of gas moving from an airbag inflator to the interior of the airbag. The first stream of gas is separate from the second stream of gas.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 11/961,465, which was filed on 20 Dec. 2007, and is incorporated herein by reference. 
    
    
     BACKGROUND 
     This invention relates to changing airbag venting as the airbag inflates. 
     Known airbag systems protect vehicle occupants by absorbing forces generated during collisions, for example. Many airbag systems are used in conjunction with other vehicle safety systems, such as seatbelts. Safety systems protect occupants located in various positions within the vehicle. 
     In particular, airbag designs within some safety systems protect both “in-position” occupants and “out-of-position” occupants. Typically, during a collision, an “in-position” occupant directly strikes a contact face portion of the airbag, whereas an “out-of-position” occupant does not directly strike the contact face. Balancing protection of “in-position” occupants with protect of “out-of-position” occupants is often challenging. Through the contact face, the airbag absorbs forces from the occupant that are generated during the collision. 
     Generally, it is desirable to provide a softer airbag during the initial stages of airbag deployment. It is also often desirable to provide a harder airbag when the airbag is fully deployed and when the occupant is an “in-position” occupant. As known, occupants may move between the “out-of-position” occupant position and the “in-position” occupant position. Many airbags include vents for changing the softness or the hardness of the airbag as the airbag deploys, but the occupant position does not affect airflow through the vents. 
     SUMMARY 
     An example airbag assembly includes an airbag and a duct. The duct has a duct opening for venting gas. The duct is moveable between a first position where the duct opening is outside the airbag and a second position where the duct opening is inside the airbag. Inflating the airbag moves the duct between the first position and the second position. The airbag is configured to be inflated by a first stream of gas moving from the duct opening to an interior of the airbag and by a second stream of gas moving from an airbag inflator to the interior of the airbag. The first stream of gas is separate from the second stream of gas. 
     Another example airbag assembly includes an airbag and a duct adjacent an airbag opening in the airbag. The duct has a duct vent for venting gas from the duct. The duct is moveable between a first arrangement that provides a first flow from the duct through the airbag opening and a second arrangement that provides a second flow from the duct through the airbag opening. The first flow is greater than the second flow. The airbag is configured to be at least partially inflated with gas that does not move through the duct. 
     Yet another airbag assembly includes an airbag and a duct. A portion of the duct is moveable relative to at least a portion of the airbag from a first position to a second position. The duct directs gas out of the airbag in the first position. The duct directs less gas out of the airbag in the second position. An interior of the airbag outside the duct is configured to receive a first flow of gas that does not move through the duct and a second flow of gas that does move through the duct. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description: 
         FIG. 1A  shows a side view of example “out-of-position” occupants within a vehicle. 
         FIG. 1B  shows a side view of an example “in-position” occupant within a vehicle. 
         FIG. 2A  shows a partially schematic top view of an example airbag assembly having an airbag in a partially expanded position. 
         FIG. 2B  shows another partially schematic top view of the  FIG. 2A  airbag assembly having the airbag in a fully expanded position. 
         FIG. 3  shows a perspective view of a duct portion of the  FIG. 2A  airbag assembly. 
         FIG. 4A  shows a partially schematic top view of another example airbag assembly having an airbag in a partially expanded position. 
         FIG. 4B  shows a partially schematic top view of the  FIG. 4A  airbag assembly having the airbag in a fully expanded position. 
         FIG. 5A  shows a partially schematic top view of yet another example airbag assembly having an airbag in a partially expanded position. 
         FIG. 5B  shows a partially schematic top view of the  FIG. 5A  airbag assembly having the airbag in a fully expanded position. 
         FIG. 6  shows a partially schematic top view of yet another example airbag assembly having an airbag in a fully expanded position. 
         FIG. 7  shows a partially schematic top view of yet another example airbag assembly having an airbag in a fully expanded position. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 1A  illustrates “out-of-position” occupants  20  within a vehicle  28 . As known, “out-of-position” occupants  20  can tend to crowd the airbag deployment area  32  more than an “in-position” occupant  24  shown in  FIG. 1B . 
     In this example, the “out-of-position” occupants  20  are undesirably located near an airbag deployment area  32 . By contrast, the “in-position” occupant  24  desirably provides clearance for an airbag to expand from the airbag deployment area  32 . As generally known, providing a harder airbag is often desired for the “in-position” occupant  24 , but not desired for the “out-of-position” occupants  20 . 
     Referring now to  FIGS. 2A and 2B , an example airbag assembly  50  includes an airbag  54  having at least one duct  58 . A duct opening  62  or duct vent at an end of the duct  58  permits gas  78  movement from the duct  58 . An airbag inflator  66 , represented schematically here, generates gas  78 , which is moved into another end of the duct  58  and into the interior portion of the airbag  54 . Accordingly, the airbag inflator  66  moves gas  78  that both inflates the airbag  54 , and gas  78  that escapes outside of the airbag  54  through the duct opening  62 . The duct  58  and the airbag  54  are secured adjacent the airbag inflator  66 . 
     The duct opening  62  extends outside the airbag  54  through the duct opening  62  when the airbag  54  is partially deployed, but not when the airbag  54  is fully deployed. As the airbag  54  inflates, the duct opening  62  moves inside the airbag  54 . Distance d 1  in  FIG. 2A  and greater distance D 1  in  FIG. 2B  represent example distances between an airbag opening  82  and the attachment points of the duct  58  and the airbag  54  near the airbag inflator  66 . The duct  58  is too short to extend the duct opening  62  outside the airbag  54  through the airbag opening  82  after the airbag  54  is inflated some amount. 
     Moving the duct  58  within the interior of the airbag  54  changes the location of the duct opening  62 . In this example, filling the airbag  54  with gas  78  from the duct opening  62  hardens the airbag  54 . As known, hardening the airbag  54  is generally desired during the later stages of deployment, not when the airbag  54  initially deploys. Accordingly, the example assembly  50  pulls the duct opening  62  within the airbag  54  as the airbag  54  approaches the fully deployed position of  FIG. 2B , which ensures that the gas  78  moving from the duct opening  62  does not contribute to expanding the airbag  54  during initial deployment of the airbag  54  or when the “out-of-position” occupant of  FIG. 1A  limits movement of a contact face  74  portion of the airbag  54 . 
     The airbag  54  has softer characteristics during the earlier stages of deployment, say the first 20 milliseconds of deployment, because some of the gas  78  vents to the outside environment through the duct opening  62 . As known, softer characteristics of the airbag  54  are desired for “out-of-position” occupants  20  and during initial stages of airbag deployment. Associating the position of the contact face  74  with the characteristics of the airbag  54  facilitates accommodating the “out-of-position” occupant  20  and the “in-position” occupant  24 . 
     Referring now to  FIG. 3 , the duct  58  includes a duct mouth  68  for receiving gas  78  from the airbag inflator  66  ( FIG. 2A ). The shape of the duct  58  tends to direct air from the mouth  68  toward the duct opening  62 . The duct  58  is flexible and foldable with the airbag  54  in the airbag deployment area  32  ( FIG. 1A ) when the airbag  54  is not inflated. A person skilled in this art would know how to direct gas  78  into both the duct  58  and the interior portion of the airbag  54  and how to design a suitable duct  58  for incorporation into the airbag assembly  50 . 
     In the example of  FIGS. 4A and 4B , the duct  58  attaches directly to an interior surface of the airbag  54 , which closes the duct opening  62  ( FIG. 3 ) to prevent venting gas  78  from the duct  58  outside the airbag  54 . Instead, gas  78  fills the duct  58  forcing the sides of the airbag  54  outward in directions Y. Filling the duct  58  forces the sides of the airbag  54  outward during the early stages of airbag  54  deployment. Without the duct  58 , the sides of the airbag  54  move outward as the interior of the airbag  54  fills, rather than as the interior of the duct  58  fills. In this example, the airbag  54  may include discrete vents  64  for venting gas  78  directly from the interior of the airbag  54 . As known, discrete vents  64  help soften the deploying airbag  54 . 
     Referring now to  FIGS. 5A and 5B  in another example, the interior of the airbag  54  may include at least one tether  70  for moving the duct  58  relative the airbag  54 . As shown, the tether  70  secures the duct  58  to an interior surface  72  of the airbag  54 . In this example, one end of the tether  70  attaches to the interior surface  72  of the airbag near a contact face  74  of the airbag  54  opposing the airbag inflator  66 , and another end of the tether  70  attaches directly to the duct  58 . The ends of the tether  70  are respectively sewn to the interior surface  72  of the airbag  54  and the duct  58 , for example. Accordingly, moving the interior surface  72  of the airbag  54  moves the tether  70 , which moves the duct  58 . 
     The airbag opening  82  within the airbag  54  facilitates moving the duct  58  relative other portion of the airbag  54 . In this example, moving the contact face  74  moves the tether  70 , which pulls the duct  58  inside the airbag  54 . Ordinarily, the contact face  74  is the portion of the airbag  54  for contacting an occupant  20 ,  24  ( FIGS. 1A-1B ). Thus, in this example, the tether  70  does not pull the duct  58  fully inside the airbag  54  until the contact face  74  extends sufficiently away from the airbag deployment area  32 . Distance d 2  in  FIG. 5A  and greater distance D 2  in  FIG. 5B  represent example distances between the airbag opening  82  and the attachment location of the tether adjacent the contact face  74 . 
     The contact face  74  of the airbag  54  moves further as the airbag  54  deploys. As known, during deployment of the airbag  54 , the “out-of-position” occupant  20  of  FIG. 1A  would strike the contact face  74  of the airbag  54  sooner than the “in-position” occupant  24  of  FIG. 1B . Moving the contact face  74  increases the distance between the contact face  74  and the attachment point of the tether  70  to the duct  58 . Limiting movement of the contact face  74 , such as with the “out-of-position” occupant  20  of  FIG. 1A , would prevent or otherwise limit movement of the tether  70  and the duct  58 , and would cause the duct  58  to continue to vent outside of the airbag  54  until the occupant  20  moves to permit expansion of the contact face  74 . 
     Moving the duct  58  within the airbag  54  does permit some gas  78  to escape from the airbag  54  through the airbag opening  82 . However, the duct  58  provides a more direct path between the gas  78  from the airbag inflator  66  and the outside of the airbag  54 . Thus the amount of the gas  78  moving from the airbag inflator  66  and through the duct opening  62 , is greater than the amount of gas  78  moving from the airbag inflator  66  to the interior of the airbag  54  and through the airbag opening  82  when the duct  58  is fully within the airbag  54 . 
     In the  FIG. 6  example, the airbag assembly  50  include at least one clamping tether  86  that closes the duct  58  to restrict flow of gas  78  through the duct opening  62  during the latter stages of airbag  54  deployment. In such an example, the clamping tether  86  kinks the duct  58  as the contact face  74  moves away from the airbag deployment area  32 . As previously described, moving the airbag contact face  74  away from the airbag deployment area  32  moves the tether  86 , which, in this example, causes the tether  86  to kink the duct  58 . In this example, the duct  58  does not move within the airbag opening  82 . Stitches  87  may secure the duct  58  relative the airbag  54 . 
     Kinking the duct  58  with the tether  86  restricts flow through the duct  58 . As a result, gas  78  that would formerly move outside the airbag  54  through the duct opening  62  stays within the airbag  54 . As previously described, providing more air or more gas  78  to the interior of the airbag  54  hardens the airbag  54 . As flow through the duct  58  is blocked, the airbag inflator  66  directs gas  78  formerly directly through the duct  58  directly into the interior of the airbag  54 . 
     In the example of  FIG. 7 , the tether  86  pulls a flap  94  on the duct  58 , which permits gas  78  to escape through an aperture  98  within the duct  58  into the interior of the airbag  54 . Accordingly, as the contact face  74  expands, the tether  86  opens the aperture to direct more gas  78  into the interior of the airbag  54 . A hook and loop fastener may secure the flap  94  over the aperture  98  until the tether  86  opens the flap  94 . 
     Although a preferred embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.