Abstract:
An airbag cushion is disclosed for use in automotive protective systems. The airbag cushion includes at least one gas deflector which directs gas to a closeable vent to allow gas to be vented out of the cushion when an obstruction is encountered.

Description:
TECHNICAL FIELD 
     The present invention relates generally to the field of automotive protective systems. More specifically, the present invention relates to inflatable airbags for automobiles. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Understanding that drawings depict only typical embodiments of the invention and are not therefore to be considered to be limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings as listed below. 
         FIG. 1A  is a perspective view of a partially expanded airbag cushion with a partial cut-away to show the gas deflector, tethers, and the closeable vents (cinch vents). 
         FIG. 1B  is a perspective view of the airbag cushion, as shown in  FIG. 1A , after it has been fully expanded once the vents have been closed and the gas deflector has re-directed gas to the interior of the airbag. 
         FIG. 2A  is a cross-sectional view illustrating initial deployment of an airbag cushion for an occupant in a normal position. 
         FIG. 2B  is a cross-sectional view illustrating a deploying airbag cushion which is partially deployed as it encounters an occupant in a normal position. 
         FIG. 2C  is a cross-sectional view of an airbag cushion which has closed vents to enable the airbag cushion to fully deploy. 
         FIG. 3A  is a cross-sectional view illustrating initial deployment of an airbag cushion for an out-of-position occupant. 
         FIG. 3B  is a cross-sectional view illustrating a deploying airbag cushion which is only partially deployed as it has encountered an out-of-position occupant. 
         FIG. 3C  is a cross-sectional view of an airbag cushion which remains only partially deployed as the closeable vents remain open to prevent full deployment of the airbag cushion. 
         FIG. 4  is a diagram illustrating an airbag cushion venting graph in relation to an airbag cushion&#39;s deployment. 
         FIG. 5  is a perspective view of another embodiment of a deployed airbag cushion. 
         FIG. 6  is a cross-sectional view of the embodiment of the airbag cushion shown in  FIG. 5 . 
         FIG. 7A  is a perspective view of another embodiment of an airbag module. The airbag cushion is shown partially deployed with its vent open and with its tether and the gas deflector shown in phantom. 
         FIG. 7B  is a cross-sectional view of the airbag cushion shown in  FIG. 7A . 
         FIG. 8A  depicts the same embodiment shown in  FIGS. 7A-7B  and provides a perspective view of the fully deployed airbag cushion which shows in phantom the gas deflector, the tether and the closed vent. 
         FIG. 8B  is a cross-sectional view of the airbag cushion shown in  FIG. 8A . 
         FIG. 9A  is a perspective view of another embodiment of an airbag module. The airbag cushion is shown partially deployed with its vent open and with its tether and the gas deflector shown in phantom. 
         FIG. 9B  is a cross-sectional view of the airbag cushion shown in  FIG. 9A . 
         FIG. 10A  depicts the same embodiment shown in  FIGS. 9A-9B  and provides a perspective view of the fully deployed airbag cushion which shows in phantom the gas deflector, the tether and the closed vent. 
         FIG. 10B  is a cross-sectional view of the airbag cushion shown in  FIG. 10A . 
     
    
    
     INDEX OF ELEMENTS IDENTIFIED IN THE DRAWINGS 
       30  occupant 
       40  instrument panel 
       100  airbag module 
       101  airbag cushion 
       102  interior of the airbag cushion  101   
       102   f  front portion of interior  102   
       108  throat 
       110  membrane 
       111  interior surface of airbag cushion membrane 
       112  exterior surface of the airbag cushion membrane 
       113  face surface 
       116  seam 
       120  airbag module housing 
       130  gas deflector 
       131  material 
       132  opening 
       133  perimeter of direct opening  134   
       134  direct opening of gas deflector 
       135  side openings 
       136  perimeter of side openings  135   
       137  arms 
       138  seams 
       150  cinch vent, laced vent or other closeable vent 
       151  rim or diameter of cinch tube and sides edges of laced vent 
       152  tube of cinch vent and sides of laced vent 
       153  tether holder of vent such as a sleeve 
       154  holes in tether holder of cinch vent and holes of laced vent 
       156  ends of laced vent 
       158  vent apertures 
       160  fixed vent 
       170  control tether 
       171  stitching or retention knot 
       173  vent portion 
       179  tether attachment 
       200  airbag module 
       201  airbag cushion 
       202  interior of the airbag cushion  201   
       202   f  front portion of interior  202   
       210  airbag cushion membrane 
       211  interior surface of airbag cushion membrane 
       212  exterior surface of the airbag cushion membrane 
       213  face surface 
       220  airbag module housing 
       230  gas deflector 
       234  forward opening of gas deflector 
       235  openings 
       236  perimeter of openings  235   
       237  arms 
       238  seams 
       250  closeable flap vent 
       251  rim or diameter of edges of vent aperture 
       258  vent aperture 
       270  control tether 
       275  vent portion 
       279  tether attachment 
       280  tether holder 
       300  airbag module 
       301  airbag cushion 
       302  interior of the airbag cushion  301   
       302   f  front portion of interior  302   
       310  airbag cushion membrane 
       311  interior surface of airbag cushion membrane 
       312  exterior surface of the airbag cushion membrane 
       313  face surface 
       320  airbag module housing 
       330  gas deflector 
       334  forward opening of gas deflector 
       335  openings 
       336  perimeter of openings  335   
       337  arms 
       338  seams 
       350  closeable flap vent 
       351  rim or diameter of edges of vent aperture 
       358  vent aperture 
       370  control tether 
       375  vent portion 
       376  apertures 
       378  tack stitching 
       379  tether attachment 
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Described below are embodiments of an airbag cushion and venting mechanism. As those of skill in the art will appreciate, the principles of the invention may be applied to and used with a variety of airbag deployment systems including frontal driver and passenger airbags, knee airbags, overhead airbags, curtain airbags, and the like. Thus, the present invention is applicable to airbag cushions of various shapes and sizes. 
     Airbag cushions are frequently located in an instrument panel and directly in front of an occupant. During a collision, an airbag cushion inflates and deploys through a cosmetic cover. The airbag cushion deploys towards the occupant and provides a restraint. 
     Full inflation of an airbag is not always desired. For example, partial inflation offers optimal protection when the occupant being protected by the airbag cushion is a child, a baby in a rear facing car seat or an adult positioned too close to the airbag cushion. Such conditions are referred to as out-of-position conditions. Embodiments described below provide an airbag cushion that responds to an occupant&#39;s position and vents accordingly to avoid excessive deploying impact. 
     Embodiments disclosed herein permit response to occupant position and vents accordingly. Each embodiment has a closeable opening for venting gas referred to as an optionally closeable vent for out-of-position (OOP) conditions such as a cinch vent. Each embodiment also has a gas deflector or diffuser positioned in the cushion to optimize the flow of gas out of the closeable vents. The gas deflector enables the rapid escape of the gas out of the cushion via the closeable vents. 
     The gas deflector is positioned in the interior of the inflatable airbag cushion to direct inflation gas from an inflator and to optimize the flow of gas out of the closeable vents. The gas deflector has at least one arm configured to direct gas to a closeable vent to enable the rapid escape of the gas out of the cushion via the closeable vent. The arm has at least one opening to permit gas to be re-directed to the interior of the inflatable airbag cushion when the closeable vent is closed. The arm of the gas deflector and the closeable vent are configured to move together during expansion of the inflatable airbag cushion. 
     Some embodiments of the closeable vent may be closed via a component such as a control tether or cord. The tether may be connected at one end to a vent and at an opposing end elsewhere within or on the cushion. If an occupant is in close proximity to the deploying airbag and restricts normal inflation, the closeable vent remains open and allows gas to rapidly escape. If the occupant is in a normal position and inflation is unrestricted, the tension pulls on the tether to quickly close the closeable vent. Closure retains gas for normal occupant restraint. Thus, the closeable vent may be used as a variable feature in out-of-position conditions and in normal restraint conditions. In this manner, the airbag cushion is sensitive to obstructive expansion of the cushion. The control tethers may be optionally configured to incrementally close the vent. For example, the tether may have tabs or teeth which pass through a feature but can not pass back through the feature so that the tether incrementally cinches the vent closed in a deployment direction while restricting movement in the opposite direction such as during ride-down. 
     With reference now to the accompanying figures, particular embodiments of the invention will now be described in greater detail. One embodiment of airbag module  100  is shown in  FIGS. 1A-1B  comprising an airbag cushion  101  and a housing  120 .  FIG. 1A  is a perspective view which shows housing  120  of airbag module  100  having an inflator (not shown) delivering gas into airbag cushion  101  via a gas deflector  130  within airbag cushion  101  of airbag module  100 . In  FIG. 1A , the initially deploying airbag cushion  101  has a control tether  170  which is slack and the closeable cinch vent  150  remains open. If an occupant is not out-of-position, tether  170  is pulled taut and the closeable vent  150  begins to close.  FIG. 1B  shows closeable vents  150   a - b  after they have been closed as control tethers  170   a - b  have been pulled taut by expansion of the cushion due to the pressure of the gas in airbag cushion  101 . 
     Some of the structures of the airbag cushion  101  are best seen with reference to  FIGS. 1A-1B  while  FIGS. 2A-2C ,  FIGS. 3A-3C , and  FIG. 4  show only some components such as gas deflector  130 , closeable vents  150 , fixed vents  160  and tethers  170 . Airbag cushion  101  has an interior  102  with front portion  102   f . Airbag cushion  101  also has a membrane  110  with an interior surface  111  and exterior surface  112 . Vent apertures  158  in membrane  110  provides an opening for gas to exit interior  102  of airbag cushion  101  via closeable vents  150 . Gas enters interior  102  via another opening in the membrane  110 , throat  108 . 
     Gas deflector  130  is configured to create a pressure pocket and re-direct the inflation gas. The embodiment of the gas deflector shown in  FIG. 1A  at  130  comprises a material  131  which may be integral with a surface of cushion  101  or attached to cushion  101 . For example, gas deflector  130  may be sewn together with the cushion. Gas deflector  130  receives gas via throat  108  through opening  132 . Perimeter  133  defines direct opening  134 . Direct opening  134  assists with normal inflation of cushion  101  to assist in getting cushion  101  in position in time for dynamic loading purposes. 
     In addition to direct opening  134 , gas is also directed out of side openings  135   a - 135   b . Openings  135   a - b  are respectively defined by perimeters or rims  136   a - b  at the ends of each arm  137   a - b . In the embodiment shown in FIGS.  1 A- 1 B, a portion of each rim  136   a - b  is attached to the cushion membrane  110  so only a portion of the gas is directed out of the airbag cushion  101  via vents  150   a - b  while another portion of the gas is directed from gas deflector  130  into the interior  102  of airbag cushion  101 . Because each arm  137   a - b  is attached to the cushion membrane, each arm  137   a - b  is configured to move respectively with vents  150   a - b  during expansion of the inflatable airbag cushion. Movement together of each arm  137   a - b  of gas deflector  130  and the respective closeable vents  150   a - b  during expansion of the airbag cushion  101  enables gas exiting the arm to be continuously directed to the respective closeable vent. In addition to permitting gas to be re-directed into the interior  102  of airbag cushion  101  when the closeable vent  150   a - b  is closed, each opening  135   a - b  of each arm  137   a - b  also permits tether  170  to extend from closeable vent  150   a - b  to cushion membrane  110 . 
     Cushion  101  is depicted with each arm attached to cushion membrane at a seam. The seams are identified as vent aligners  138   a - b . Of course, each arm can also be attached to the vent tube. In other embodiments, a seam between gas deflector  130  and membrane  110  may not be necessary as the vent tube is an integral extension of the gas deflector. 
     While gas deflector  130  is T-shaped because arms  137   a - b  are directly opposite each other, other configurations may also be utilized. For example, the gas deflector may be rectangular, trapezoidal, hexagonal, round, etc. It may also have a portion which is round or elliptical while other portions are angled. As described below,  FIGS. 5-6  depict a gas deflector which is Y-shaped. 
     Not only are side openings  135   a - b  strategically located to redirect the gas flow generally toward closeable vents  150   a - b  and out of cushion  101  but side openings  135   a - b , are also sized for optimal gas flow. Side openings  135   a - b  are large enough to allow most of the gas to flow through them. Only in out-of-position conditions does the focused gas flow from gas deflector  130  to the aligned closeable vents  150   a - b  to allow a more rapid escape of the inflation gas as shown in  FIG. 1A . 
     As previously indicated, gas deflector  130  and closeable vents  150   a - b  are not independent of each other such that the flow remains aligned or focused with closeable vents  150   a - b . So if the occupant is in a normal position and inflation is unrestricted, gas deflector  130  functions as normal to re-direct the inflation gas generally toward the vent(s). The large vent(s) are quickly closed as the cushion fully expands retaining gas for normal occupant restraint. 
     In the embodiment depicted in  FIGS. 1A-1B , each closeable vent  150  is a cinch vent which is closed by tether  170  as rim  151  is drawn into the interior  102  of the inflatable airbag cushion  101 . Cinch vent  150  may comprises a cinch tube  152  with a rim  151 . A tether holder such as sleeve  153  with holes referred to as sleeve apertures  154  may be used to hold a vent portion  173  of tether  170 . Vent aperture  158  is defined by the inner diameter or rim  151  of tube  152 . As described below, cinch vent  150  is closed by tether  170  as rim  151  is drawn into the interior  102  of inflatable airbag cushion. 
     Cinch vent  150  may be embodied with a generally cylindrical shape. The cinch tube may be formed from a separate material that is sewn to the side of membrane  110  or it may be an integral extension. The cinch tube may have any suitable shape such as rectangular, triangular, or polygon shapes. The cinch tube may also have a taper such as a broad base which transitions to a relatively narrower rim. The cinch tube may be embodied with a height that is sufficient to achieve desired closure. In one embodiment, the cinch tube has height which is about half of its diameter. Selecting an appropriate height to diameter ratio permits the cinch tube to close during cinching without resistance from cushion membrane tension. The design permits the cinch tube to be a low-stress element in the cushion assembly which is helpful during unfolding of the cushion and pressurization. The cinch tube may comprise a nylon woven fabric-type or other suitable material known in the art. 
     An additional embodiment of a closeable vent is shown in  FIGS. 5-6  at  150   a ′ and  150   b ′ which is referred to as a laced vent. Laced vents are also disclosed in U.S. patent application Ser. No. 11/528,118 titled AIRBAG CUSHION WITH A LACED VENT TO OPTIONALLY VENT GAS FOR OUT-OF-POSITION CONDITIONS which was filed on Sep. 27, 2006. Cinch vents and other closeable vents are also disclosed in U.S. patent application Ser. No. 11/296,031 titled AIRBAG CUSHION WITH GAS DEFLECTOR AND CINCH TUBE TO VENT GAS FOR OUT-OF-POSITION CONDITIONS which was filed on Dec. 7, 2005; U.S. patent application Ser. No. 11/295,953 titled LOCKING MECHANISM FOR A CINCH TUBE TO VENT GAS OF AN AIRBAG CUSHION which was filed on Dec. 7, 2005; U.S. patent application Ser. No. 10/959,256 titled AIRBAG CUSHION WITH VENT FOR REDUCED OUT-OF-POSITION EFFECTS which was filed on Oct. 6, 2004; U.S. patent application Ser. No. 10/959,387 titled AIRBAG CUSHION WITH TETHER DEACTIVATED VENTING FOR REDUCED OUT-OF-POSITION EFFECTS which was filed on Oct. 6, 2004; and U.S. patent application Ser. No. 10/832,843 titled CUSHION VENTING DESIGN FOR OUT OF POSITION OCCUPANT PROTECTION which was filed on Apr. 27, 2004. Other examples of closeable vents referred to as flap vents are also disclosed in U.S. patent application Ser. No. 11/528,266 titled AIRBAG CUSHION WITH A FLAP VENT TO OPTIONALLY VENT GAS FOR OUT-OF-POSITION CONDITIONS which was filed on Sep. 27, 2006. An additional example of a closeable vent is disclosed in Ser. No. 11/031,394 titled AIRBAG CUSHION WITH ADAPTIVE VENTING FOR REDUCED OUT-OF-POSITION EFFECTS which was filed on Jan. 7, 2005. These applications are hereby incorporated by reference. 
     As described above, airbag cushion  101  includes a control tether  170 . Each tether has a vent portion  173  which is configured to actuate the closeable vent. Tether  170  is configured to move with the expansion of airbag cushion  101  to enable vent portion  173  to close closeable vent  150 . One end of tether  170  is connected to vent  170  via stitching  171  and the other end is connected to cushion membrane  110  via a tether attachment  179  which is part of or extends from membrane  110  of airbag cushion  101 . Tether attachment  179  serves as an anchor for an end of tether  170 . In another embodiment, the tether attachment is stitching between cushion membrane  110  and tether  170 . In another embodiment, tether  170  is an integral extension of either cushion membrane  110  or cinch tube  152 . Alternatively, tether  170  is not fixedly anchored but is moveably anchored to cushion membrane  110  via tether attachment  179 ′ as shown in  FIG. 5  which is essentially a loop that permits movement of tether  170 . Other components of another embodiment of a control tether are described with reference to  FIGS. 7A-7B  and  FIGS. 8A-8B . The tether attachment may be disposed elsewhere such as proximate to a different portion of interior surface  111 . Alternatively, the tether attachment may be a portion of exterior surface  112 . For example, the tether attachment may be at the bottom of the face surface  113 , which is the surface of the airbag cushion directed to the occupant. Thus, tether  170  may extend through the interior  102  of the airbag cushion  101  or may be positioned exterior to the airbag cushion  101 . The location of the tether attachment  179  depends on module deployment angle, vehicle interior geometry, and cushion fold type. The tether  170  may comprise a nylon material or other suitable material known in the art. 
       FIGS. 2A-C  illustrate three stages of airbag cushion  101  deploying without encountering obstruction in the deploying path. The depicted airbag cushion  101  includes gas deflector  130 , two closeable cinch vents  150   a - b  symmetrically disposed on cushion  101  and two optional fixed vents  160   a - b  symmetrically disposed on the cushion  101 . Fixed vents  160   a - b  provide consistent venting of the airbag cushion  101  and are not restricted by an occupant&#39;s position. In addition to remaining open, fixed vents  160   a - b  also differ from closeable vents  170   a - b  as fixed vents  160   a - b  are typically smaller. Fixed vents  160   a - b  may be optional in certain cushion embodiments based on venting requirements. The locations for closeable vents  150   a - b  and fixed vents  160   a - b  may vary as does the number of vents. An occupant  30  is in a normal seating position which will allow the airbag cushion  101  to fully expand before impacting the occupant. In this manner, the occupant  30  benefits from the full restraint capability of the airbag cushion  101 . 
     In  FIG. 2A , the initial breakout of the airbag cushion  101  occurs. The closeable cinch vents  150   a - b  are open and, in the depicted embodiment, extend from the airbag cushion  101 . Because cushion  101  is initially in a folded condition, at initial breakout (such as the initial 7 milliseconds), closeable cinch vents  150   a - b  are initially non-functional. Because an occupant is not positioned directly in front of the airbag cushion  101  in  FIG. 2A , cushion  101  unfolds and is allowed to pressurize normally. In  FIG. 2B , tethers  170   a - b  which respectively correspond with cinch vents  150   a - b  are pulled taut and gas flow through cinch vents  150   a - b  is restricted. In  FIG. 2C , cinch vents  150   a - b  are completely closed, the gas vents through the fixed vents  160   a - b , and normal restraint is provided to the occupant  30 . 
       FIGS. 3A-C  illustrate three stages of a deploying airbag cushion  101  with obstruction in the deploying path. An occupant  30  is out-of-position and obstructs the deploying airbag cushion  101  and prevents the airbag cushion  101  from fully inflating. In  FIG. 3A , airbag cushion  101  begins initial deployment as in  FIG. 2A  but encounters occupant  30  causing gas to be vented through fixed vents  160   a - b . Fixed vents  160   a - b  may be located in the side panels of cushion  101  near closeable vents  150   a - b , as shown. In  FIG. 3B , airbag cushion  101  impacts the occupant  30  and the tethers  170   a - b  remain slack. The closeable vents  150   a - b  remain open and venting rapidly occurs from cinch vents  150   a - b  and fixed vents  160   a - b . The cushion inflation is restricted and the occupant  30  receives less than the full deployment loading of the cushion  101 . In  FIG. 3C , cushion  101  is partially inflated and provides limited restraint. Venting continues through cinch vents  150   a - b  and fixed vents  160   a - b.    
     Referring to  FIG. 4 , a graph illustrating venting as a function of airbag cushion displacement is shown. For reference, an airbag cushion  101  is shown in various stages of deployment with gas deflector  130  and two symmetrically disposed cinch vents  150   a - b . During initial deployment, airbag cushion  101  is unfolding and cinch vents  150   a - b  provide little or no venting. Airbag cushion  101  expands into an out-of-position zone where, if obstructed, the cinch vents  150   a - b  will remain completely or nearly open and full venting occurs. In this zone an occupant does not receive the full restraint capability but does benefit from limited restraint. If unobstructed, airbag cushion  101  expands into a gray zone where partial closure of the cinch vents  150   a - b  begins and venting is limited. If further unobstructed, airbag cushion  101  fully expands to the restraint zone. At this zone, cinch vents  150   a - b  completely close and an occupant benefits from the full restraint capability of airbag cushion  101 . 
     Early in a normal inflation, gas loss through cinch vent  150   a - b  is minimal even with gas deflector  130 . This phenomenon is due to the Bernoulli effect—pressure is lower in a moving fluid than in a stationary fluid. For example, if the convex side of a spoon is placed into a smooth stream of water from a faucet, the spoon is pulled into the stream. The higher pressure outside the moving fluid pushes the spoon into the lower pressure water. In an airbag deployment, the high velocity stream of gas flowing into the cushion creates a similar effect for approximately 30 milliseconds, particularly in the area of throat  108 . Since pressure outside the cushion is still atmospheric, there is a pressure imbalance and gas flows into the cushion, not out of the cushion, when the vent is positioned alongside of the gas flow stream and not in its path. 
       FIGS. 5-6  depict another embodiment of an airbag cushion as designated by  101 ′ which has been fully deployed. Airbag cushion  101 ′ comprises another embodiment of a gas deflector as identified at  130 ′, another embodiment of a pair of closeable vents as identified at  150   a ′- 150   b ′ and another embodiment of a tether as identified at  170 ′. 
     Like gas deflector  130 , gas deflector  130 ′ is configured to create a pressure pocket and re-direct the inflation gas after gas after the gas enters via a gas deflector opening  132  which corresponds with the throat opening  108 . Also, arms  137   a ′-b′ move with vents  150   a ′-b′. However, arms  137   a ′-b′ are configured so that gas deflector  130 ′ is Y-shaped instead of T-shaped like gas deflector  130 . 
     Closeable laced vents  150   a ′- 150   b ′ comprise opposing vent sides  152   a ′- 152   b ′. Opposing sides  152   a ′- 152   b ′ have holes  154   a ′- 154   b ′ which receive the vent portion  173   a ′- 173   b ′ of tether  170   a ′- 170   b ′ in a single laced configuration. Opposing sides  152   a ′- 152   b ′ come together respectively at ends  156   a ′- 156   b ′. Sides  152   a ′- 152   b ′ are located around a vent aperture  158   a ′- 158   b ′ in the membrane  110  of the inflatable airbag cushion  101 . Vent aperture  158   a ′- 158   b ′ is defined by edges  151   a ′- 151   b ′ of sides  152   a ′- 152   b ′. The closeable laced vent may be reinforced as needed with a suitable material such as a nylon woven fabric-type or other material known in the art. For example, optional panel strips may also be used to reinforce sides  152   a ′- 152   b ′ or a sleeve may be formed to assist in reducing surface tension when under pressure. 
     Closeable laced vents  150   a ′- 150   b ′ may be formed by cutting a slit in membrane  110  or by removing a portion of membrane  110 . Closeable laced vents may also be formed which are co-linear with a seam of the airbag, such as seam  116  by not seaming the opposing portions of material together. The vent aperture of the closeable vent may have any suitable shape. Vent portions  173   a ′- 173   b ′ may also have other configurations. For example, vent portions  173   a ′- 173   b ′ may extend diagonally across vent apertures  158   a ′- 158   b ′ in a double laced configuration like a shoelace without retention knots  171   a ′- 171   b ′. Note that in such a double laced configuration, neither end of the control tether is necessarily attached to a closeable vent. 
     Symmetrical closeable vents  150   a ′-b′ of airbag cushion  101 ′, as shown in  FIGS. 5-6 , are linked by tether  170 ′ which comprises integral halves  170   a ′-b′. So a single cord or piece of material such as tether  170 ′ can be used instead of a tether corresponding to each closeable vent. Tether  170 ′ passes through a tether attachment  179 ′ which acts as a loop that is coupled to the interior surface  111  of airbag cushion  101 . Tether attachment  179 ′ may be formed of a fabric material similar or identical to that of the airbag cushion  101 ′. Tether  170 ′ may freely pass through tether attachment  179 ′ and may therefore be referred to as a “floating” tether” which is moveably anchored while tethers  170  are fixedly anchored. In an alternative embodiment, the tether may be disposed on the airbag cushion exterior and pass through a tether attachment coupled to an exterior surface  112  of the airbag cushion  101 ′. Note that upon deployment, the distance from the location of tether attachment  179 ′ to throat  108  is greater than the distance from throat  108  to either closeable vent  150   a ′ or  150   b′.    
       FIGS. 7A-7B  and  8 A- 8 B provide views of airbag module  200  after airbag cushion  201  has deployed. Airbag cushion  201  has a gas diffuser  230  which is identical to gas diffuser  130 . Airbag cushion  201  also features other embodiments of vents as identified at  250   a - b  and tethers as identified at  270   a - b.    
     In  FIGS. 7A-7B , airbag module  200  is shown during deployment with an out-of-position occupant  30  adjacent thereto as the out-of-position occupant&#39;s head has makes contact with airbag cushion  201 . The presence of the out-of-position occupant thus prevents control tethers  270   a - b  from fully extending and thereby prevents vents  250   a - b  from closing so inflation gas is free to exit therefrom and prevent full inflation of the airbag cushion  201 . In this manner, the pressure and inflation forces on the out-of-position occupant are lessened and the risk for injury from the airbag deployment is reduced accordingly.  FIGS. 8A-8B  show occupant  30  in a normal position and airbag cushion  201  fully deployed. 
     Gas diffuser  230  is T-shaped with arms  237   a - b  which respectively terminate at openings  235   a - b . The gas is directed out of direct opening  234  and openings  235   a - b . Each arm  237   a - b  terminates at opening  235   a - b  and each opening  235   a - b  is defined by rim  236   a - b . At least a portion of each rim  236   a - b  is attached to cushion membrane  210  while the remainder of each rim  236   a - b  is unattached to cushion membrane  210  so that gas can be re-directed out of gas deflector  230  and into the interior  202  of inflatable airbag cushion  201  when the respective closeable vent  250   a - b  is closed. Like the attached portion of each rim  136   a - b , each attached portion of rim  236   a - b  has a round configuration. Also, like the unattached portion of each rim  136   a - b , each unattached portion of rim  236   a - b  has a parabolic configuration. In the depicted embodiments, the attached portion of the rim is positioned and sized relative to the unattached portion so that when the closeable vent is open a majority of gas is directed out of the interior of the airbag cushion. The depicted embodiments also show the unattached portion of the rim positioned so that gas is directed toward a front portion  102   f  or  202   f  of the interior when the closeable vent is closed. 
     Each vent  250  has a rim  251  which defines the vent aperture  258 . Each vent  250  is closed by a vent flap  275 . In the depicted embodiment, the vent flap is a continuous extension of a strap or tether as identified at  270 . Vent flap  275  is coupled to an interior surface  211  of the cushion  201  and proximate to vent aperture  258 . 
     Tether  270  couples at one end to vent flap  275  and at an opposing end to the interior surface  211  opposite to face surface  213 . Tether  270  is coupled to the interior surface  211  at a location opposing the face surface  213  that contacts an occupant  30 . One or more loops  280  are coupled to the interior surface  211  and retain tether  270  in position. Vent flap  275  and tether  270  may be integrally formed or may be coupled to one another by stitches, bonds, or adhesives. Vent flap  275  and tether  270  may include a nylon fabric material or any other material suitable in the art. Vent flap  275  and tether  270  may each be coupled to the interior surface  211  by stitches, bond, or adhesives. Of course, tethers  270  can alternatively be moveably anchored to the cushion membrane instead of being fixed as depicted. The tether may alternatively be configured to have tabs or teeth which pass through one or more loops, such as loops  280 , without being able to pass back through the loops. Such a configuration permits the tether to incrementally cinch the vent closed in a deployment direction while restricting movement in the opposite direction such as during ride-down. 
     Before deployment of cushion  201 , vent flap  275  partially extends out of vent aperture  258  and then enters back into the vent aperture  258 . In so doing, vent flap  275  forms a U-shape outside of the vent aperture  258  and allows gas to exit through the vent  250 . 
     During deployment, tether  270  is initially slack and vent flap  275  remains partially outside of the cushion interior  202 . As the airbag cushion  201  deploys, the face surface  213  contacts the out-of-position occupant  30 . Because of the limited deployment, the tether  270  is not able to fully extend and the vent flap  275  remains extending through the vent aperture  258 . Gas freely vents through the vent aperture  258  and pushes against the vent flap  275  so that the vent aperture  258  is not obscured. The airbag cushion  201  builds up less pressure and avoids injuring an occupant  30  impeding the deployment. 
     Referring to  FIGS. 8A-8B , views of a deployed airbag cushion  201  are shown without the occupant  30  obstructing deployment. When an occupant is in position, this configuration also permits closeable vent  250  to be closed by blocking the flow of gas out of the vent aperture  258  by vent flap  275 . Airbag cushion  201  is able to fully deploy before contacting the occupant  30  thereby providing maximum restraint. As the airbag cushion  201  deploys, tether  270  is pulled until taut which forces the entire vent flap  275  into the cushion interior  202 . The vent flap  275  is pressed against the rim  251  of vent  250  by the interior gas pressure. The vent flap  275  is sized to extend through the vent aperture  258 , enter the cushion interior  202 , and close against the rim  251  without exiting through vent aperture  258 . 
     Vent flap  275  has a surface which is sufficient to press against and cover the vent aperture  258  without exiting through the vent aperture  258 . Vent flap  275  may be configured to not completely cover the vent aperture  258  when some limited venting is required. The vent flap may also includes a converging segment that converges to the tether or strap  270 . One of skill in the art will appreciate that the vent flap  275  may be configured in a variety of shapes, all of which are included within the scope of the invention. 
       FIGS. 9A-9B  and  10 A- 10 B depict another embodiment of an airbag cushion at  301 . Airbag cushion  301  is shown deployed with an out-of-position occupant in  FIGS. 9A-9B  and a normally positioned occupant in  10 A- 10 B like  FIGS. 7A-7B  and  8 A- 8 B. Airbag cushion  301  has a gas diffuser  330  which is similar to gas diffusers  130  and  230 . Airbag cushion  301  also features other embodiments of vents as identified at  350   a - b  and tethers as identified at  370   a - b.    
     Gas diffuser  330  is T-shaped with arms  337   a - b  which respectively terminate at openings  335   a - b . The gas is directed out of direct opening  334  and openings  335   a - b . Each arm  337   a - b  terminates at an opening  335   a - b  defined by rim  336   a - b . At least a portion of each rim  336   a - b  is attached to cushion membrane  310  while the remainder of each rim  336   a - b  is unattached to cushion membrane  310  so that gas can be re-directed out of gas deflector  330  and into the interior  302  of inflatable airbag cushion  301  when the respective closeable vent  350   a - b  is closed. 
     Each tether  370   a - b  has a vent flap  375   a - b  with a plurality of apertures  376   a - b  which are initially aligned with the plurality of vent apertures  358   a - b . In the depicted embodiment, the vent flap is a continuous extension of a tether. Each vent flap  375   a - b  is coupled to an interior surface  311  of the cushion  301  and proximate to the rims  351   a - b  which define the plurality of vent apertures  358   a - b . Vent flaps  375   a - b  may move under the unattached portion of the rim (not shown). In another embodiment, the vent flaps may move through an opening or slot in each respective arm near the openings at the end of each arm. 
     Tethers  370   a - b  couples at one end to the respective vent flaps  375   a - b  and at an opposing end to the interior surface  311  along the side of the airbag cushion. Of course, Tethers  370   a - b  can also be moveably or fixedly connected together, like the embodiments discussed above, to other surfaces such as the interior surface  311  opposite face surface  313 . Of course, tethers  370   a - b  may be separately attached elsewhere in a moveable or fixed configuration. If tether  370   a - b  is coupled to the interior surface  311  opposite face surface  313  it may be advantageous for tether  370   a - b  to pass through a loop attached to the interior surface along the side of the airbag cushion. 
     Tack stitches  378   a - b  of vent flaps  375   a - b  retain vent flaps  375   a - b  so that upon deployment with an out-of-position occupant as shown in  FIGS. 9A-9B  vent flaps  375   a - b  remain in place. Tack stitches  378   a - b  also prevent inadvertent closing of vents  350   a - b  during shipping and handling. Such tack stitching is designed to be easily broken. 
       FIGS. 10A-10B  show airbag cushion after deploying when an occupant is in a normal position. Tack stitches  378   a - b  have been ruptured due to the pressure of vent flaps  375   a - b  being pulled by the sides of airbag cushion  301 . The plurality of apertures  376   a - b  of vent flap  375   a - b  have become misaligned with the plurality of vent apertures  358   a - b  so that the flow of gas out of vent apertures  358   a - b  is blocked and diverted toward the front portion  302   f  of interior  302 . 
     Embodiments disclosed herein illustrate novel techniques for venting an airbag cushion to retain an open vent when an occupant obstructs the path of a deploying cushion and a closed vent when an occupant does not obstruct a deploying cushion. Airbag cushions provide improved safety by deploying with less pressure when an occupant is obstructing deployment. The airbag cushions deploy with more pressure when an occupant is not obstructing deployment and when high pressure is required to provide the necessary restraint. The airbag cushions described herein have application to both driver and passenger positions. Furthermore, the airbag cushions may be configured in a variety of sizes based on design constraints. 
     Many design variations are possible and should be considered within the scope of the invention. For example, the airbag cushion body may have a plurality of cushion vents formed therein and each of the cushion vents may have an associated arm of the gas diffuser. Accordingly, the design could be tailored to adjust or fine tune the deployment and deployment forces in accordance with various occupant positions. The design could be tailored, for instance, to allow a small number of cushion vents to remain open in the event that an occupant is only slightly out of position, allow a greater number of cushion vents to remain open in the event that an occupant is further out of position, and allow most or all cushion vents to remain open in the event that an occupant is positioned very close to the airbag at the time of deployment. The design could also be tailored to account for a passenger being out of position laterally with respect to the airbag by configuring the control tethers to allow primarily the cushion vents on one side of the airbag cushion body or the other to remain open in accordance with the position of the out-of-position occupant. 
     Embodiments disclosed herein illustrate novel techniques for venting an airbag cushion to retain an open vent when an occupant obstructs the path of a deploying cushion and to close and remain closed when an occupant does not obstruct a deploying cushion. Airbag cushions provide improved safety by deploying with less pressure when an occupant is obstructing deployment. The airbag cushions deploy with more pressure when an occupant is not obstructing deployment and when high pressure is required to provide the necessary restraint. The airbag cushions described herein have application to both driver and passenger positions. Furthermore, the airbag cushions may be configured in a variety of sizes based on design constraints. 
     Various embodiments for closeable vents have been disclosed herein. The closeable vents disclosed herein are examples of means for selectively venting gas out of the airbag. 
     A control cord or control tether, as disclosed herein, is an example of means for restricting gas venting by moving the selectively venting means upon inflatable airbag deployment without obstruction and enabling the vent aperture to remain open upon inflatable airbag deployment with obstruction. The control tether is also an example of means for restricting gas venting by closing the venting means upon inflatable airbag deployment without obstruction and enabling the venting means to remain open upon inflatable airbag deployment with obstruction. 
     The combination of a closeable vent and a control tether, as disclosed herein, is an example of means for restricting gas venting by closing the venting means to reduce the aperture of the venting means upon inflatable airbag deployment without obstruction and enabling the venting means to remain open upon inflatable airbag deployment with obstruction. 
     The gas deflectors disclosed herein are examples of means for diffusing gas within an airbag cushion by re-directing inflation gas received from an inflator. The gas deflectors disclosed herein are also examples of means for diffusing gas by re-directing inflation gas to the venting means from an inflator such that the gas rapidly exits the inflatable airbag cushion via the venting means when deployment of the airbag is obstructed. 
     It will be apparent to those having skill in the art that changes may be made to the details of the above-described embodiments without departing from the underlying principles of the invention. Embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows. Note that elements recited in means-plus-function format are intended to be construed in accordance with 35 U.S.C. § 112 ¶6.