Abstract:
An airbag assembly is disclosed for use in an automobile. The disclosed airbag assembly adaptively vents gas from the interior of the airbag depending on whether an obstruction is encountered during airbag deployment.

Description:
TECHNICAL FIELD  
       [0001]    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  
         [0002]    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. 
           [0003]      FIG. 1A  is a partial cutaway perspective view of one embodiment of an airbag assembly during initial cushion membrane deployment. 
           [0004]      FIG. 1B  is a partial cutaway perspective view of the airbag assembly of  FIG. 1A  during mid-cushion membrane deployment. 
           [0005]      FIG. 1C  is a partial cutaway perspective view of the airbag assembly of  FIG. 1A  during full cushion membrane deployment. 
           [0006]      FIG. 2A  is a side elevation view the airbag assembly of  FIG. 1A  during cushion membrane deployment in the presence of an out of position occupant. 
           [0007]      FIG. 2B  is a side elevation view the airbag assembly of  FIG. 1A  during unobstructed cushion membrane deployment in the presence of a normally seated occupant. 
           [0008]      FIG. 3A  is a side elevation cutaway view detailing some components of another embodiment of an airbag assembly during initial airbag deployment. 
           [0009]      FIG. 3B  is a side elevation cutaway view of the airbag assembly of  FIG. 3A  during mid-airbag deployment, or airbag deployment with obstruction. 
           [0010]      FIG. 3C  is a side elevation cutaway view of the airbag assembly of  FIG. 3A  during unobstructed airbag deployment. 
           [0011]      FIG. 4A  is a side elevation cutaway view detailing some components of another embodiment of an airbag assembly during initial deployment. 
           [0012]      FIG. 4B  is a side elevation cutaway view detailing the airbag assembly of  FIG. 4A  during mid-airbag deployment, or airbag deployment with obstruction. 
           [0013]      FIG. 4C  is a side elevation cutaway view of the airbag assembly of  FIG. 4A  during unobstructed deployment. 
       
    
    
       [0014]    Index of Elements Identified in the Drawings
     10  vehicle     20  instrument panel     40  windshield     50  occupant     100  airbag module     102  inflator housing     110  airbag cushion membrane     112  aperture     114  aperture cover     116  exhaust manifold     120  control tether     122  vent portion of tether     124  middle portion of tether     126  membrane portion of tether     130  diffuser     132  diffuser aperture     140  breakaway stitching     150  fixed vent     310  airbag cushion membrane     312  aperture     314  aperture cover     320  control tether     322  cover portion of control tether     324  middle portion of control tether     326  membrane portion of control tether     340  breakaway stitching     410  airbag cushion membrane     412  aperture     414  aperture cover     420  control tether     422  cover portion of control tether     424  middle portion of control tether     426  membrane portion of control tether     440  breakaway stitching     460  perforations   
 
       DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0050]    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. 
         [0051]    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. 
         [0052]    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 air bag 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. 
         [0053]    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, wherein the vent is initially deployed in an at least partially closed configuration. Each closeable vent may be opened 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. A diffuser may also be positioned in the cushion to optimize the flow of gas out of the closeable vents. Additionally fixed vents, which are not closeable may be incorporated into the inflatable cushion membrane. 
         [0054]    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 until the tether no longer opens 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. 
         [0055]      FIG. 1A  depicts one embodiment of an airbag assembly  100  from a partially cutaway perspective view during initial airbag deployment. Airbag assembly  100  may typically be housed in an instrument panel or steering wheel within a vehicle and may comprise an airbag membrane  110 , one or more control tethers  120 , an optional diffuser  130 , an optional fixed vent (not shown), and an optional exhaust manifold  116 . 
         [0056]    Cushion membrane  110  may comprise at least one aperture  112 , at least one aperture cover  114 , and at least one exhaust manifold  116 . Aperture  112  may be called a vent, and aperture cover  114  may be called a vent cover. Further, aperture  112  and aperture cover  114  may collectively be called a closeable vent. 
         [0057]    Cushion membrane  110  may be manufactured from a pliable woven material known to one skilled in the relevant art. Cushion membrane  110  may be attached to inflator housing  102 , which in turn may be anchored within a vehicle. 
         [0058]    Aperture  112  is formed in cushion membrane  110  and is in fluid communication with the interior of cushion membrane  110 , such that aperture  112  may vent inflation gas from the interior to the exterior of cushion membrane  110 .  FIG. 1A  depicts aperture  112  as being circular in shape and of a specific size, however, aperture  112  may be of any shape or size which is suitable for venting inflation gas such that in case of contact with an out of position occupant, cushion membrane  110  is sufficiently soft. Further the location of aperture  112  is purely illustrative and may vary depending on application. 
         [0059]    Aperture cover  114  may be formed from any suitable material, and in  FIG. 1A  it is depicted as being made from the same material as the cushion membrane. Cover  114  is attached to cushion membrane  110  on at least three sides of aperture  112 , and in a resting state, cover  114  completely covers aperture  112 . Cover  114  is not attached to membrane  110  on one side and it is this free side that may be pulled away from aperture  112  to allow inflation gas to be vented from the interior of membrane  110 . Cover  114  may be attached to membrane  110  via stitching, gluing, welding, or in any other suitable manner. 
         [0060]    Exhaust manifold  116  is an optional component of airbag assembly  100 . Manifold  116  is attached to the exterior surface of cushion membrane  110  and completely surrounds aperture  112 . Thus, manifold  116  forms a tube through which inflation gas may be directed. Exhaust manifold  116  may be formed from any suitable material and may be attached to membrane  110  via any suitable method such as stitching, gluing, and welding. 
         [0061]    Control tether  120  is configured to operate vent cover  114  by coupling the expansion of membrane  110  with pulling open vent cover  114 . Tether  120  may be formed from an elongated piece of woven nylon material or any other suitable material. Tether  120  may be releasably attached to vent cover  114  via break-away stitching or any other releasable attachment. Tether  120  further comprises an elongated middle portion which extends to a surface of cushion membrane  110 . The elongated middle portion is configured such that during initial airbag deployment, tether  120  is slack and does not open aperture cover  114 . In the depiction of  FIG. 1A  tether  120  is attached to an occupant-proximal surface of airbag cushion membrane  110 . In other embodiments, tether  120  may be coupled to any surface of cushion membrane  110 , including an instrument panel-proximal surface of membrane  110 , which expands sufficiently to allow tether  120  to operate aperture cover  114 . 
         [0062]      FIG. 1A  depicts two control tethers, each fixedly attached to membrane  110 . In other embodiments, one contiguous piece of material could be used to connect both vent covers to membrane  110 . That contiguous control tether may be fixedly attached to membrane  110 , or slideably attached via a loop of material protruding from membrane  110 , which slideably receives the contiguous control tether. Further, control tether  120  could comprise an integral extension of airbag membrane  110 , or of vent cover  114 . 
         [0063]    Diffuser  130  is an optional component of airbag assembly  100 , and may be of any suitable type known in the art, and in the embodiment of  FIG. 1A , it is depicted as a piece of pliable fabric with three apertures. During initial airbag deployment, inflation gas (depicted as arrows) exits inflator housing  102  and enters diffuser  130 , from which the inflation gas exits via the apertures. Diffuser  130  may be configured such that during initial airbag deployment the apertures of diffuser  130  do not align with vent apertures  112 . It is not necessary that diffuser  130  apertures be misaligned with vent apertures  112  because vent cover  114  completely covers vent aperture  112  during initial airbag deployment. Note that in other embodiments, the optional diffuser may have other shapes and the openings may have different sizes and numbers. Further, diffuser  130  may be a contiguous, integral extension of airbag cushion membrane  110 . 
         [0064]    During a collision event, inflation of airbag assembly  100  is triggered by vehicle sensors and inflation gas rapidly begins to fill airbag membrane  110 . During this initial stage of airbag deployment, control tethers  120  remain slack and vent covers  112  remains completely covering vent aperture  112 . 
         [0065]      FIG. 1B  is a partially cutaway perspective view of the airbag assembly of  FIG. 1A , wherein the airbag assembly is in mid-airbag deployment without obstruction. In the depiction of  FIG. 1B  airbag deployment has proceeded from initial airbag deployment, depicted in  FIG. 1A , to a state of deployment wherein the airbag cushion volume is greater than that of  FIG. 1A . 
         [0066]    Control tethers  120  are depicted as being under tension and tether middle portion is fully extended due to the expansion of the occupant-proximal surface of airbag membrane  110  away from the instrument panel. This tension is transmitted to the unstitched side of vent cover  114 , which results in vent cover  114  being pulled away from vent aperture  112 . Inflation gas (depicted as arrows) may be able to exit the interior of cushion membrane  110 . 
         [0067]    The amount of gas able to escape during airbag deployment without obstruction is minimal, for two reasons. First, this intermediate stage of airbag deployment without obstruction only exists for a very small fraction of a second. The other reason 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. Inflation gas that does escape exits via the optional exhaust manifolds  116 . 
         [0068]    Although tethers  120  are under tension during mid-airbag deployment, the amount of tension is not yet enough to tear breakaway stitching  140  from tether vent portion  122  from vent cover  114 . Membrane portion  126  of tether  120  remains securely attached to membrane  110 . 
         [0069]      FIG. 1C  is a partial cutaway perspective view of the airbag assembly of  FIG. 1A  wherein the airbag has been fully deployed without obstruction. In this depiction, inflation gas has continued to enter the interior of airbag membrane  110  through inflator housing  102  and diffuser  130 , and diffuser apertures  132 . Airbag membrane  110  has fully expanded which exerts sufficient tension on control tether  120  to cause breakaway stitching  140  to rupture, while membrane portion  126  remains fixedly attached to membrane  110 . 
         [0070]    Rupture of stitching  140  allows vent portion  122  of tether  120  to become separated from vent cover  114 . Since aperture cover  114  is no longer being pulled away from aperture  112 , aperture cover  114  completely covers aperture  112 . Expansion of airbag membrane  110  causes aperture cover  114  to tightly cover aperture  112 , such that very little inflation gas is able to escape the interior of membrane  110  through aperture  112 , resulting in a fully inflated airbag cushion which may sufficiently cushion an occupant properly seated in a vehicle. 
         [0071]      FIG. 2A  depicts a side elevation view of the airbag assembly of  FIG. 1A , wherein the airbag is in mid-deployment and has contacted an out of position occupant  50 . Out of position occupant  50  in vehicle  10  may also be a child, a child&#39;s car seat, an adult who is not wearing a restraining device, or an individual who is positioned too close to instrument panel  20 . 
         [0072]    Airbag membrane  110  is partially inflated, such that tension is applied to control tether  120 . Occupant  50  blocks further expansion of membrane  110  such that tether  120  remains taut, but vent portion  122  of tether  120  is not torn away from aperture cover  114 . Thus, vent cover  114  is pulled away from vent aperture  112  by tether  120 , and inflation gas may be vented through optional diffuser  130  and aperture  112 . The venting of inflation gas softens the cushion to provide appropriate cushioning for occupant  50 . 
         [0073]    Also visible in this view is one of two bilaterally disposed fixed vents  150 . Airbag assembly  100  may comprise at least one fixed vent  150 , which provide consistent venting of the airbag cushion membrane  110  and are not restricted by an occupant&#39;s position. In addition to remaining open, fixed vent  150  also differs from closeable vent (comprising vent aperture  112  and aperture cover  114 ) in that fixed vent  150  is typically smaller. Fixed vent  150  may be optional in certain cushion embodiments based on venting requirements. The location of fixed vent  150  may vary as does the number of fixed vents  150 . 
         [0074]      FIG. 2B  is a side elevation view of airbag assembly  100  of  FIGS. 1A-1C , wherein the airbag is fully deployed without obstruction. Occupant  50  is far enough away from instrument panel  20  that upon airbag deployment, cushion membrane  110  may fully expand without obstruction. Full expansion of cushion membrane  110  causes sufficient tension to be applied to control tether  120  that breakaway stitching attaching vent portion  122  of control tether  120  to vent cover  114  is ruptured. 
         [0075]    The expansion of membrane  110  coupled with the release of control tether  120  causes vent cover  114  to fully and tightly cover aperture  112 , limiting the exit of inflation gas through aperture  112 . Fixed vent  150  is still able to vent inflation gas from the interior of cushion membrane  110 . Diffuser  130  may still be positioned such that the diffuser apertures are still aligned with vent apertures  112 , or the diffuser may collapse within membrane  112 , since inflation gas is no longer entering membrane  112  via inflator housing  102  and diffuser  130 . 
         [0076]      FIGS. 3A-C  depict some components of another embodiment of an airbag assembly with adaptive venting for out of position occupants, wherein the airbag is in early deployment ( FIG. 3A ), mid-deployment, or deployment with obstruction ( FIG. 3B ) and full, unobstructed deployment ( FIG. 3C ). The airbag assembly of this embodiment is similar to that shown in  FIGS. 1A-1C , and may comprise an airbag membrane  310 , one or more control tethers  320 , a diffuser (not shown), a fixed vent (not shown), and an exhaust port (not shown). 
         [0077]    Airbag membrane  310  may comprise at least one aperture  312 , and at least one aperture cover  314 . The components of airbag assembly  300  are similar to those of airbag assembly  100 , except for the differences identified in the following description. 
         [0078]    Aperture  312  is formed in membrane  310  and is in fluid communication with the interior of membrane  310 . Aperture cover  314  is attached to membrane  310  on at least three sides and is disposed over aperture  312 . Control tether  320  comprises an aperture cover proximal portion  322 , and elongated middle portion  324 , and a membrane proximal portion  326 . The cover proximal portion  322  is fixedly attached to aperture cover  314 , whereas in airbag assembly  100 , the cover proximal portion  122  was attached using breakaway stitching. 
         [0079]    The elongated middle portion  324  is of sufficient length that during early airbag deployment (as in  FIG. 3A ) control tether  320  is slack and during mid-airbag deployment, or deployment with obstruction ( FIG. 3B ) it is taut. Membrane proximal portion  326  is releasably attached to membrane  310  using breakaway stitching  340  or some other suitable releasable attachment. In airbag assembly  100 , the membrane proximal portion of control tether  120  was fixedly attached to membrane  110 . During unobstructed airbag deployment, tension applied to control tether  320  increases until stitching  340  is ruptured, and membrane portion  326  is released from membrane  310 . 
         [0080]      FIGS. 4A-C  depict some components of another embodiment of an airbag assembly with adaptive venting for out of position occupants, wherein the airbag is in early deployment ( FIG. 4A ), mid-deployment, or deployment with obstruction ( FIG. 4B ) and full, unobstructed deployment ( FIG. 4C ). The airbag assembly of this embodiment is similar to that of airbag assembly  100 , and may comprise an airbag membrane  410 , one or more control tethers  420 , a diffuser (not shown), a fixed vent (not shown), and an exhaust port (not shown). 
         [0081]    In this embodiment, aperture cover  414  is sewn on all  4  sides, but one of the sides is sewn with breakaway stitching  440 . Additionally, control tether  420  is fixedly attached to both aperture cover  414  and membrane  410 . The elongated portion  424  of control tether  420  is perforated  460 . 
         [0082]    Upon mid-airbag deployment or deployment with obstruction, breakaway stitching  440  is ruptured and one side of aperture cover  414  is pulled away from aperture  412 , however perforations  460  do not rupture. Upon airbag deployment without obstruction, tension continues to be applied to control tether  420  until perforations  460  rupture, which severs control tether  420  and aperture cover  414  is released to completely cover aperture  412 . 
         [0083]    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 vent cover attached to the cushion membrane. Control tethers may extend from each of the respective vent covers to different portions of the airbag cushion body. As such, the length with which each of the control tethers extend from their respective vent covers to the airbag cushion body may differ in accordance with design specifications. 
         [0084]    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. 
         [0085]    Vent covers suitable for use in embodiments of the invention may be shaped and sized in a wide variety of ways as desired. Embodiments of the invention may also optionally include protruding features extending from the vent cover. Such features may be shaped and configured to interact with the gas flow and prevent “flutter” at high gas velocities. These protruding features need not be any particular shape or size. Instead, they may be shaped and sized in accordance with desired gas flow characteristics. 
         [0086]    Embodiments disclosed herein illustrate novel techniques for venting an airbag cushion, wherein the vent is initially closed, becomes open during the course of unobstructed airbag deployment, and then becomes closed during full airbag deployment, but may retain an open vent when an occupant obstructs the path of 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. 
         [0087]    Various embodiments for closeable vents have been disclosed herein. The closeable vents disclosed herein are examples of means for venting gas out of the airbag cushion. The vent covers, or aperture covers, disclosed herein are examples of means for selectively venting gas out of the airbag. 
         [0088]    A control tether, aperture cover tether, or vent tether, as disclosed herein, is an example of means for restricting gas venting by moving the selective gas venting means upon inflatable airbag deployment without obstruction and enabling the vent aperture to remain uncovered 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. 
         [0089]    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 cover 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. 
         [0090]    The breakaway stitching and the perforations disclosed herein, are examples of means for releasing the control tether (moving means). 
         [0091]    The diffusers disclosed herein are examples of means for diffusing gas within an airbag cushion by re-directing inflation gas received from an inflator. The diffusers 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. 
         [0092]    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.