Abstract:
An airbag assembly with a reduced-cost knee airbag cushion and internal tethers can be formed from a single rectangular panel of material so that there is very little material waste. A pleat can be formed in a rear face so that the combination of tethers and pleat help the cushion deploy with favorable characteristics and adopt an arced shape when inflated. The cushion can have apertures for inserting an inflator with mounting stems partially within the cushion so that the mounting stems can be used to couple the cushion to an airbag housing. The assembly can also have a bag strap formed from a single piece of fabric that can wrap around a rolled and/or folded cushion. The assembly can also have a stabilizer strap that can be coupled to the cushion and to the airbag housing so that during deployment, the cushion does not skew or twist.

Description:
TECHNICAL FIELD 
       [0001]    The present disclosure relates generally to the field of automotive protective systems. More specifically, the present disclosure relates to inflatable knee airbag cushion assemblies. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0002]    The present embodiments will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. Understanding that the accompanying drawings depict only typical embodiments, and are, therefore, not to be considered to be limiting of the disclosure&#39;s scope, the embodiments will be described and explained with specificity and detail in reference to the accompanying drawings. 
           [0003]      FIG. 1A  is a top elevation view of a panel of material from which a portion of an airbag cushion may be formed, which in turn, comprises a portion of an airbag assembly. 
           [0004]      FIG. 1B  is a top elevation view of the panel of material of  FIG. 1A  after portions of the panel have been removed. 
           [0005]      FIG. 2  is a bottom perspective view of a portion of an embodiment of an airbag assembly. 
           [0006]      FIG. 3  is a top perspective view of the airbag assembly of  FIG. 2  after the assembly has been rotated 180 degrees. 
           [0007]      FIG. 4  is a rear perspective view of the airbag assembly of  FIG. 2 . 
           [0008]      FIG. 5  is a side elevation view of the airbag assembly of  FIG. 2 . 
           [0009]      FIG. 6  is a close up side elevation view of a portion of the airbag assembly of  FIG. 2 . 
           [0010]      FIG. 7  is a close up side elevation view of a portion of the airbag assembly of  FIG. 2 . 
           [0011]      FIG. 8A  is a perspective view of a panel of material from which a bag strap can be formed. 
           [0012]      FIG. 8B  is a perspective view of the panel of material of  FIG. 8A  after a portion of the panel has been folded. 
           [0013]      FIG. 8C  is a perspective view of the panel of material of  FIG. 8B  after a loop has been formed in the panel of material. 
           [0014]      FIG. 9  is a close up top perspective view of a portion of the airbag assembly of  FIG. 2 . 
           [0015]      FIG. 10  is a close up bottom perspective view of a portion of the airbag assembly of  FIG. 2 . 
           [0016]      FIG. 11A  is a rear elevation view of the airbag assembly of  FIG. 2 , wherein the airbag cushion is in an extended configuration prior to being subjected to a method for folding an airbag cushion. 
           [0017]      FIG. 11B  is a rear elevation view of the airbag assembly of  FIG. 11A  after side portions of the airbag cushion have been tucked in accordance with a method for folding an airbag cushion. 
           [0018]      FIG. 11C  is a rear elevation view of the airbag assembly of  FIG. 11B  after a top portion of the airbag cushion has been folded in accordance with a method for folding an airbag cushion. 
           [0019]      FIG. 12A  is a side elevation view of the airbag cushion assembly of  FIG. 11C . 
           [0020]      FIG. 12B  is a side elevation view of the airbag cushion assembly of  FIG. 12A  after a top portion of the airbag cushion has begun to be rolled in accordance with a method for folding an airbag cushion. 
           [0021]      FIG. 12C  is a side elevation view of the airbag cushion assembly of  FIG. 12B , wherein the airbag cushion has continued to be rolled in accordance with a method for folding an airbag cushion. 
           [0022]      FIG. 12D  is a side elevation view of the airbag cushion assembly of  FIG. 12C  after the top portion of the airbag cushion has been rolled in accordance with a method for folding an airbag cushion. 
           [0023]      FIG. 13A  is a rear elevation view of the airbag assembly of  FIG. 12D . 
           [0024]      FIG. 13B  is a rear elevation view of the airbag assembly of  FIG. 13A  after a bag strap has been wrapped around the cushion in accordance with a method for folding an airbag cushion. 
           [0025]      FIG. 14  is a side elevation view of the airbag assembly of  FIG. 13B . 
           [0026]      FIG. 15  is a rear perspective view of an airbag housing into which a packaged airbag assembly of  FIG. 2  has been placed. 
           [0027]      FIG. 16  is a close up cutaway perspective view of a portion of another embodiment of an inflatable cushion airbag assembly. 
           [0028]      FIG. 17  is a top perspective of a portion of the airbag assembly of  FIG. 16 . 
           [0029]      FIG. 18  is a close up cutaway perspective view of a portion of the inflatable cushion airbag assembly of  FIG. 17  after another step in a method for attaching an inflator has been performed. 
           [0030]      FIG. 19A  is a close up cutaway perspective view of a portion of another embodiment of an inflatable cushion airbag assembly. 
           [0031]      FIG. 19B  is a close up cutaway perspective view of the inflatable cushion airbag assembly of  FIG. 19A  after a step in a method for attaching an inflator has been performed. 
           [0032]      FIG. 19C  is a close up cutaway perspective view of the inflatable cushion airbag assembly of  FIG. 19B  after another step in a method for attaching an inflator has been performed. 
           [0033]      FIG. 20  is a close up cutaway front perspective view of the inflatable cushion airbag assembly of  FIG. 19A   
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0034]    It will be readily understood that the components of the embodiments as generally described and illustrated in the figures herein could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of various embodiments, as represented in the figures, is not intended to limit the scope of the disclosure, as claimed, but is merely representative of various embodiments. While the various aspects of the embodiments are presented in drawings, the drawings are not necessarily drawn to scale unless specifically indicated. 
         [0035]    The phrases “connected to,” “coupled to” and “in communication with” refer to any form of interaction between two or more entities, including mechanical, electrical, magnetic, electromagnetic, fluid, and thermal interaction. Two components may be coupled to each other even though they are not in direct contact with each other. The term “abutting” refers to items that are in direct physical contact with each other, although the items may not necessarily be attached together. 
         [0036]    Inflatable airbag systems are widely used to minimize occupant injury in a collision scenario. Airbag modules have been installed at various locations within a vehicle, including, but not limited to, the steering wheel, the instrument panel, within the side doors or side seats, adjacent to roof rail of the vehicle, in an overhead position, or at the knee or leg position. In the following disclosure, “airbag” may refer to an inflatable curtain airbag, overhead airbag, front airbag, or any other airbag type. 
         [0037]    Front airbags are typically installed in the steering wheel and instrument panel of a vehicle. During installation, the airbags are rolled, folded, or both, and are retained in the rolled/folded state behind a cover. During a collision event, vehicle sensors trigger the activation of an inflator, which rapidly fills the airbag with inflation gas. Thus the airbag rapidly changes confirmations from the rolled/folded configuration to an expanded configuration. 
         [0038]      FIGS. 1A-1B  are a top elevation views of a panel of material  101  from which a portion of an airbag cushion may be formed. Panel  101  comprises a sheet of fabric that may comprise a woven nylon material, or any other material that is well known in the art. Panel  101  comprises a rectangular shape that is defined by a perimeter  105  and has a first portion  102 , a second portion  103 , and a middle portion  104 . First tether  130  and second tether  135  may be cut from the middle portion of panel  101  such that after being cut, panel  101  may be said to have an “I” or “H” shape. The length and/or width of panel  101  may be varied according to different embodiments. For example, width W 1  may be from about 400 mm to about 600 mm and length L 1  may be from about 600 mm to 900 mm. 
         [0039]      FIG. 1B  depicts panel  101  after first and second tethers  130  and  135  have been cut from panel  101 , after which a second width W 2  is defined by the middle portion  104 . W 2  may be from about 250 mm to about 550 mm. Width W 2  of middle portion  104  may comprise about 110% of the width of an airbag housing of airbag assembly  100 . An inflator insert aperture  123  and an inflator mounting stem aperture  124  may be formed in middle portion  104  by cutting, stamping, or as a result of the employment of a one-piece-weaving technique.  FIG. 1B  depicts the corners of panel  101  as being trimmed compared to the corners of the panel as shown in  FIG. 1A ; however, the corners may be trimmed or not. Embodiments of an inflatable airbag cushion formed from a panel that does not have trimmed corners may have a perimeter seam that angles across the panel&#39;s corners, as sown in  FIG. 1B , in which case an inflatable void of the cushion may comprise corners similar to those sown in  FIG. 1B . 
         [0040]      FIGS. 2-4  are perspective views of a portion of airbag assembly  100 , wherein  FIG. 2  is a bottom perspective view,  FIG. 3  is a top perspective view, and  FIG. 4  is a side perspective view. Assembly  100  may comprise a cushion  110 , a first tether  130 , a second tether  135 , reinforcements  140 , heat panels  145 , a bag strap  150 , and a stabilizer strap  170 . After the first and second tethers have been cut from panel of material  101  the panel may be folded at middle portion  104  to form a fold  109 . When panel  101  is folded, first portion  102  and second portion  103  are brought in close proximity such that the planes of the first and second portions are in a substantially parallel orientation. Fold  109  may comprise one or more discrete folds, or the fold may comprise a more general “U” shape. 
         [0041]    Once membrane  101  is folded, stitching  106  may be applied around perimeter  105  such that the first and second portions  102  and  103  are coupled together. After being folded and stitched together, it may be said that panel of material  101  has been configured as an inflatable airbag cushion membrane  110 . As such, the cushion membrane has an inflatable void  118 . For clarity in depicting various structures and characteristics of assembly  100 , in some of the following figures, cushion  110  is shown without the perimeter being sewn together. 
         [0042]    Cushion membrane  110  may described as having an upper portion  111 , a lower portion  112 , a front face  113 , and a rear face  114 . Upper portion  111  of cushion  110  is the portion of the cushion that is closest to the headliner of a vehicle when the cushion is in a deployed state. Lower portion  112  is below upper portion  111  when cushion  110  is in a deployed state, and is closest to a floor of the vehicle. The term “lower portion” is not necessarily limited to the portion of cushion  110  that is below a horizontal medial plane of the cushion, but may include less than half, more than half or exactly half of the bottom portion of the cushion. Likewise, the term “upper portion” is not necessarily limited to the portion of cushion  110  that is above a horizontal medial plane of the cushion, but may include less than half, more than half or exactly half of the top portion of the cushion. 
         [0043]    As will be appreciated by those skilled in the art, a variety of types and configurations of airbag cushion membranes can be utilized without departing from the scope and spirit of the present disclosure. For example, the size, shape, and proportions of the cushion membrane may vary according to its use in different vehicles or different locations within a vehicle. Also, the cushion membrane may comprise one or more pieces of any material well known in the art, such as a woven nylon fabric. Additionally, the airbag cushion may be manufactured using a variety of techniques such as one piece weaving, “cut and sew”, or a combination of the two techniques. Further, the cushion membrane may be manufactured using sealed or unsealed seams, wherein the seams are formed by stitching, adhesive, taping, radio frequency welding, heat sealing, or any other suitable technique or combination of techniques. 
         [0044]    Once the panel of material has been configured as an inflatable cushion  110 , the cushion may be coupled with additional components to form an inflatable airbag cushion assembly  100 , as depicted in  FIG. 2 . Bag strap  150 , stabilizer strap  170 , and first tether  130  have been coupled to membrane  101  at middle portion  104 . Second tether  135  is coupled to membrane  101  closer to upper portion  111  than first tether  130 . First and second tethers  130  and  135  are coupled to front face  113  and extend to, and are coupled to, rear face  114 . In other words, the first and second tethers are located between the front and rear faces such that the tethers may be said to be located within the inflatable void of the inflatable airbag cushion. First and second tethers  130  and  135  may be coupled to coupled to front and rear faces  113  and  114  by stitching, or any other suitable technique. 
         [0045]    Each tether may not be symmetrically attached to the cushion membrane on the front face and the rear face. For example, the portions of the first and second tethers that are coupled to the rear face of the membrane may be located between about 20 mm and 30 mm closer to fold  109  than the portions of the first and second tethers that are coupled to the front face of the membrane. In other words, the point at which the first and second tethers are coupled to the front face of the inflatable cushion membrane may be located more towards the upper portion of the cushion that the point at which the first and second tethers are coupled to the rear face of the inflatable cushion. 
         [0046]    First tether  130  may be located between middle portion  104  and first and second portions  102  and  103  and may be oriented such that the tether runs transversely across the middle portion of cushion  110 . In one embodiment, the first tether runs the entire width of the cushion, from perimeter to perimeter. First tether  130  may comprise one or more apertures ( 131 ), as depicted in  FIG. 1 , wherein the apertures are configured to allow inflation gas to pass from a first side of the first tether to a second side of the tether. First tether  130  may be described as running transversely across a majority of the width of cushion  110  and is coupled to front and rear faces  113  and  114  of the cushion. First tether  130  is positioned within cushion  110  such that when the cushion is deployed, the first tether is located outside the housing. The first tether may be located between about 100 mm and about 200 mm from the folded portion of cushion  110 , before a pleat has been formed. First tether  130  may be located between the inflator (not shown) and a portion of inflatable void  118 , such that the plurality of apertures may allow inflation gas to pass from an inflator-proximal side of the tether to an inflator distal side of the tether. As such, the apertures may allow inflation gas to flow from the inflator into the inflatable void. The apertures may each comprise a diameter of about 33 mm and may be sewn concentrically using a single needle lock stitch with about a 3 mm off-set. 
         [0047]    Second tether  135  may be located between about 33% to about 50% the distance from first tether  130  to a top edge of upper portion  111  of cushion  110 . Generally, the second tether may be about 50% the width as the airbag cushion. For example, in one embodiment, the second tether is about 250 mm wide and the inflatable airbag cushion is about 500 mm wide. 
         [0048]    Bag strap  150  may comprise a piece of woven fabric that is coupled to attachment portion  120  of cushion  110 . Attachment portion  120  is located on front face  113  at middle portion  104 . As such, bag strap  150  is coupled to front face  113  of cushion  110 , and may be coupled to the cushion via stitching or any other suitable technique. Bag strap  150  may aid in retaining cushion  110  in a packaged configuration; in obtaining favorable airbag cushion deployment characteristics; and in coupling the cushion to an airbag housing. 
         [0049]    One or more reinforcements  140  may be placed at high stress points in assembly  100 , wherein the reinforcements comprise one or more pieces of fabric that may the same or different than the fabric from which cushion  110  is formed. For example, one or more reinforcements may be sewn into perimeter seam  107  near where middle portion  104  of cushion  110  extends to become lower portion  112  of front and rear faces  113  and  114 . Additionally, one or more layers of reinforcement may be coupled to cushion  110  at an attachment area  120 , near inflator apertures  123  and  124 , wherein the reinforcement may comprise the same material or a different material than reinforcement  140 . 
         [0050]    Heat resistant fabric  145  may be coupled near the inflator attachment area  120  and may be employed in addition to or instead of reinforcements at inflator apertures  123  and  124 . The heat resistant fabric may comprise a plain woven fiberglass material with a silicone coating, wherein the fiberglass strands in the fabric comprise E-glass, S-glass, or S2-glass grades of fiberglass. If present, the silicone coating may be applied to one side of the fabric and the fabric oriented within assembly  100  such that the silicone coated side faces the inflator. 
         [0051]    One skilled in the art will recognize that a variety of types and configurations of heat resistant materials and coatings, as well as reinforcements may be employed without diverging from the spirit of the present disclosure. For example, the fabric need not be plain woven, but may have a more random fiber orientation of sun bond material. Also, the heat resistant material may comprise one or more of a variety of different fibers such as para-aramid synthetic fibers that are sold as Kevlar brand fibers, carbon, hemp, nylon, and polyester. Further, the heat resistant coating may comprise one or more materials such as neoprene, urethane, phenolic materials, and other flexible epoxies. In some embodiments, the reinforcement material and the heat resistant material may comprise the same material. 
         [0052]      FIG. 3  depicts a portion of airbag assembly  100  from a top perspective view, wherein the airbag assembly has been rotated 180° from the view of  FIG. 2 . In this view, front face  113  of cushion  110  is below rear face  114 , and the dashed outlines of first and second tethers  130  and  135  are visible. Also shown are inflator insert aperture  123 , inflator stem aperture  124 , and the dashed outline of reinforcement and/or heat shield  140 / 145 . 
         [0053]    A pleat  115  may be formed in rear panel  114 , such that the rear panel is not as long as front panel  113 . In other words, a distance from the upper portion  111  to the lower portion  112  is smaller for rear face  114  than front face  113 . Pleat  115  is located between first and second tethers  130  and  135  and may be formed by folding rear panel  114  back upon itself such that a fold of cushion membrane  110  is created that extends into inflatable void  118  in the direction of front panel  113 . Pleat  115  may retained by employing a double needle chain stitch. The pleat may be gradually formed and retained in cushion  110  by creating two arcs of stitching at each end of the pleat and a straight stitch in the middle of the pleat, or in another embodiment, the ends of the pleat may be stitched such that the pleat is tapered at its ends. In another embodiment, the stitch and pleat may form a single radius arc. 
         [0054]    The portion of the pleat that extends toward the front face may have a length of about 20 mm, in which case the rear panel is shortened about 40 mm. In another embodiment, the pleat extends about 50 mm such that the rear panel is shortened about 100 mm. The width of the full depth portion of pleat  115  may correspond to the width of first and second tethers  130  and  135  such that the portion of the pleat that is the full depth is about as wide as the tethers. In one embodiment, the airbag cushion is about 500 mm wide, the tethers are about 240 mm wide, and the full depth portion of the pleat is also about 240 mm wide, although the entire pleat extends about 400 mm. 
         [0055]    First tether  130 , second tether  135 , and pleat  115  are configured to aid the inflatable cushion membrane in following a predetermined deployment trajectory. Additionally, the tethers and the pleat may be configured such that the inflatable cushion adopts a predetermined shape during deployment and upon full or substantially full inflation. For example, when fully or substantially inflated, the inflatable cushion may be variously described as adopting an approximately “C” shape, a banana shape, or a crescent shape. 
         [0056]      FIG. 4  is a perspective view of a portion of airbag assembly  100 , which depicts cushion  110 , first tether  130 , second tether  135 , pleat  115 , and bag strap  150 . Portions of the first and second tethers are visible between front and rear faces  113  and  114 . Bag strap  150  is coupled to front face  113  of cushion  110  at middle portion  104  of the cushion. 
         [0057]      FIG. 5  is a side elevation view of a portion of airbag assembly  100 . As described herein, inflatable airbag cushion  110  comprises upper portion  111  and lower portion  112 . Upper portion  111  comprises upper edge  108  that may be defined by the ends of front face  113  and rear face  114 , or alternatively, the upper edge may be defined by a seam formed at the point at which the front face and the rear face are coupled. Lower portion  112  may comprise middle portion  104  at which fold  109  is formed, as well as one or more seam reinforcements  140 , one or more heat panels  145 , bag strap  150 , and stabilizer strap  170 . 
         [0058]    First tether  130  and second tether  135  are each coupled to front face  113  and rear face  114  such that they are located within inflatable void  118 . Forming pleat  115  in rear face  114  of the airbag cushion shortens the rear face, compared to the front face. As such, a top-most point  108  of rear face  114  is closer to bottom portion  112  of the airbag cushion, compared to a top-most point of front face  113 . Bag strap  150  may comprise bag strap loop  160  and engagement portion  155 . In the depicted embodiment, bag strap loop  160  comprises a fold or pleat of the bag strap material and engagement portion  155  comprises a roll or fold of the bag strap material. Stabilizer strap  170  may be coupled to cushion  110  at lower portion  112 . 
         [0059]      FIG. 6  is a close up side elevation view of a portion of inflatable airbag cushion  110 , wherein pleat  115  and first tether  130  are visible. Pleat  115  may be formed by drawing together two points on rear face  114 , and then coupling the two points together via stitching  133 . For clarity, the two points are neither touching each other or located directly adjacent each other, because seam reinforcement material may be used such that the pleat doesn&#39;t rupture during airbag deployment. If reinforcement material is not used, the portions that comprise the pleat may touch each other. Pleat  115  may project from rear face  114  into inflatable void  118  in the direction of front face  113 . A distance D 1  to which the pleat may project from the front face may be between about 20 mm and about 50 mm. First tether  130  has a first and second end, each of which may be rolled or folded before being coupled to front face  113  and rear face  114  of cushion  110 . First tether  130  may be asymmetrically coupled to the front and rear faces such that a tether attachment point on front face  113  may be located further from an inflator (not shown) or inflator attachment area (not shown) than the point at which the tether is attached to rear face  114 . Reinforcement and/or heat panel  140 / 145  may extend to first tether attachment points such that each of the first tether attachment points comprise 4 or more layers of material. First tether  130  may be coupled to cushion  110  via stitching  132 . 
         [0060]      FIG. 7  is a close up side elevation view of a portion of inflatable airbag cushion  110 , wherein second tether  135  is visible within inflatable void  118 . Second tether  135  may be coupled to cushion  110  at two attachment points, wherein one attachment point is located on front face  113  and the other attachment point is located on rear face  114 . In the depiction of  FIG. 7 , the two attachment points for the two tethers may be located approximately equal distances from an inflator. In another embodiment, the second tether  135  attachment point on front face  113  may be located closer to the inflator (not shown) than the rear face  114  attachment point, as depicted for first tether  130  in  FIG. 6 . Second tether  135  may be coupled to cushion  110  via stitching  136 , wherein the stitching crosses 3 layers of material at each attachment point. 
         [0061]      FIGS. 8A-8C  depict bag strap  150  from perspective views, wherein  FIG. 8A  depicts a full-length panel of material before it has been formed into a bag strap;  FIG. 8B  depicts the panel of material of  FIG. 8A  after a bottom portion of the bag strap has been rolled; and,  FIG. 8C  depicts the panel of material of  FIG. 8B  after the bag strap has had a loop formed in it.  FIG. 8A  depicts a panel of material  152  that has a predetermined length, and from which a bag strap may be formed. Panel  152  may comprise a piece of a woven nylon material similar to that which forms an inflatable airbag cushion. Panel  152  has a front face (not shown) and a rear face  164  and may comprise an airbag cushion portion  151 , an inflator insert aperture  153 , an inflator stem aperture  154 , an engagement portion  155 , engagement apertures  156 , stabilizer strap apertures  157 , and perforations  162 . The apertures and perforations in panel  152  are formed in predetermined locations and may also be described as forming three horizontal rows of apertures and three vertical columns of apertures. The rows of apertures comprise apertures that have different functions, and the columns of apertures comprise apertures that have the same function. 
         [0062]      FIG. 8B  depicts panel  152  of  FIG. 8A  after engagement portion  155  has been rolled to form a rolled engagement portion  158 . Rolled portion  158  is formed by folding a predetermined length of engagement portion  155  of panel  152  toward rear face  164  and in the direction of cushion portion  151 . The distance of the fold is of such a magnitude that apertures  156  align with each other, and likewise, apertures  157  align with each other. After being folded, bag strap  150  has a shortened length, L 2 . In another embodiment, the bag strap may not comprise a folded engagement portion. In such an embodiment, the panel of material from which the bag strap is formed may comprise two inflator stem apertures and one stabilizer strap aperture.  FIG. 8B  also depicts arrows that indicate the direction the panel of material may be folded to form a loop, which may be a step in a method for forming a bag strap. 
         [0063]      FIG. 8C  depicts panel  152  of  FIG. 8B  after a loop  160  has been formed such that the loop is located on rear face  164  and perforations  162  are incorporated within the loop. Loop  160  may also be described as a fold or a pleat in panel  152 , from which bag strap  150  is formed. Loop  160  has an apex  161  that may also be described as a fold. Loop  160  may be retained via tear stitching  166  or any other suitable technique or structure. Tear stitching  166  is configured to rupture during inflatable airbag deployment. In one embodiment, the tear stitching includes, about 25 threads per 100 millimeters, although one skilled in the art will appreciate that other thread counts may similarly allow the rupture of tear stitching  166  during inflatable airbag deployment without damaging bag strap  150 . Thus, tear stitching  166  is configured to rupture during deployment of the airbag cushion without damaging the bag strap and without retarding or altering cushion deployment. 
         [0064]    In the depicted embodiment, tear stitch  166  runs across bag strap  150 ; however in other embodiments, the tear stitch may only be formed in a portion of the width of the bag strap or may define one or more light tack stitches. Tear stitch  166  and perforations  162  are configured to rupture during airbag cushion  110  deployment, such that the tear stitch ruptures before the perforations. Perforations  162  may be configured to allow bag strap  150  to become severed into two pieces during deployment. Perforations  162  are depicted as being located within bag strap loop  160 ; however, in alternative embodiments, the perforations may be located along different portions of the bag strap. 
         [0065]    Panel  152  is of a predetermined length such that after the panel has been shortened by the formation of loop  160  and folded portion  158 , the resulting bag strap is of a predetermined length L 3  that is shorter than the full length of the panel of material. The shortest length (L 3 ) of bag strap  150  can be called a wrapping length. The wrapping length is also shorter than a deployment length L 2  (depicted in  FIG. 8B ). 
         [0066]    The wrapping length of the bag strap is configured to allow the bag strap to wrap around a rolled and/or folded inflatable airbag cushion and retain the cushion in this “packaged” or “folded” configuration. As discussed above, upon airbag deployment, the tear stitching that retains the bag strap in the wrapper length ruptures such that the bag strap adopts the deployment length. The deployment length of the bag strap is configured such that the airbag cushion can expand up to about 150 mm before it again begins to apply tension to the bag strap. As the airbag continues to expand, it is briefly retarded by the bag strap, until the perforations rupture and the airbag can continue to freely deploy. 
         [0067]      FIGS. 9-10  are close up perspective views of a portion of airbag assembly  100 , wherein  FIG. 10  is rotated 180° compared to the view of  FIG. 9 . As depicted in the figures, stitching  106  may be employed to couple front and rear faces  113  and  114 . Reinforcement and/or heat shield  140 / 145  can be seen as being coupled to cushion  110  near middle portion  104 . Bag strap  150  is coupled to front face  113 . Inflator aperture  153  of the bag strap is in alignment with inflator aperture  123  of cushion  110 , and likewise, inflator stem aperture  154  is aligned with inflator stem aperture  124  of the cushion. Bag strap loop  160 , tear stitch  166 , and perforations  162  are located between cushion portion  151  of bag strap  150  wherein the bag strap is coupled to cushion  110  and an engagement portion  155  of bag strap  150 . Loop  160  is configured such that it extends away from front face  163 . In other words, an apex  161  of loop  160  extends from rear face  164  because the loop is formed on the rear face. Engagement portion  155  may comprise a folded engagement portion  158 , inflator mounting stem engagement apertures  156 , and stabilizer strap aperture  157 . 
         [0068]    Stabilizer strap  170  may comprise a piece of webbing that is about 10 mm wide and is coupled to bag strap  150  and cushion  110  on front face  113 , near middle portion  104 . Stabilizer strap  170  may be coupled to cushion  110  via stitching  171 , such that the stitching is aligned with the centers of the inflator insert apertures  123 / 153  and inflator stem apertures  124 / 154 . In the depicted embodiment, stitching  171  comprises a single line of stitching; however, in another embodiment, the stitching may comprise a box stitch. If a box stitch is employed, the portion of the box stitch that is closed to the inflator or attachment area  120  of cushion  110  may be aligned with the centers of inflator apertures  123 / 153  and  124 / 154 . 
         [0069]    Inflatable airbag cushion  110  may be configured into a packaged configuration by employing a method for folding an airbag cushion, wherein the method may comprise obtaining an airbag cushion membrane as disclosed herein, tucking the sides of the cushion in toward the center until a width of the cushion is less than a width of an airbag housing to which the cushion may be attached; applying an optional tack or tear stitch; reverse rolling or reverse folding the tucked top portion of the cushion one time; continuing to reverse roll or reverse fold the tucked top portion; wrapping a bag strap around the folded cushion; securing the bag strap to at least one inflator mounting stem. In one embodiment, the folding method results in an airbag cushion that has been rolled or folded up to 5 times. 
         [0070]      FIGS. 11A-14  depict various views of airbag cushion assembly  100  during and after steps in a method for packaging an inflatable airbag cushion have been performed.  FIGS. 11A-11C  are front elevation views of assembly  100 , wherein  FIG. 11A  depicts the assembly in a pre-packaging configuration,  FIG. 11B  depicts the assembly after a first step in the method for packing an airbag cushion has been performed, and  FIG. 11C  depicts the assembly after another step has been performed. In the views of  FIGS. 11A-11C , various structures and features of assembly  100  are visible, including cushion  110 , which has upper and lower portions  111  and  112 , rear face  114 , a first half  116 , a second half  117 , inflator insert aperture  123 , and inflator mounting stem aperture  124 ; and bag strap  150 , which has cushion portion  151 , engagement portion  155 , inflator mounting stem engagement apertures  156 , stabilizer strap aperture  157 , rolled portion  158 , loop  160 , perforations  162 , and rear face  164 . 
         [0071]    In the depiction of  FIG. 11A , assembly  110  is in a flattened configuration, wherein any wrinkles or folds in cushion  110  have been removed and rear faces  114  and  164  can be said to be facing “up”. It can be said that providing an inflatable airbag cushion and flattening the cushion comprise first steps in a method for folding or packaging an inflatable airbag cushion. 
         [0072]      FIG. 11B  depicts cushion  110  after first and second halves  116  and  117  have been tucked in towards a midline of cushion  110 . The tucks may be performed by pushing each half of the cushion into the cushion, “outside-in”. In other words, first and second halves of the airbag cushion are each tucked into a middle portion of the airbag cushion such that the front and rear faces of each of the first and second halves are positioned in between the upper and lower panels of the middle portion. After the tucking steps have been performed, cushion  110  comprises a tucked upper portion  119 . 
         [0073]      FIG. 11C  depicts cushion  110  after a tucked upper portion  119  of cushion  100  is folded one time in the direction of rear face  114 , away from front face  113 . As such, tucked upper portion  119  is folded downward toward lower portion  112  and bag strap  150 . 
         [0074]      FIGS. 12A-12D  depict airbag assembly  100  from a side elevation view, wherein the assembly is being subjected to steps in a method for packaging an inflatable airbag cushion. Visible in the figures are cushion  110 , which has front face  113 , rear face  114 , attachment area  120 , and bag strap  150 , which has cushion portion  151 , folded engagement portion  158 , and loop  160 .  FIG. 12A  is a side elevation view that depicts assembly  100 , wherein the assembly is at the same stage of packaging as depicted in  FIG. 11C . Upper tucked portion  119  has been folded one time toward rear face  114 , in the direction of bag strap  150 , such that a fold  121  has been formed. 
         [0075]      FIG. 12B  depicts the airbag assembly  100  of  FIG. 12A  after fold  121  of upper tucked portion  119  has begun to be rolled in the direction of rear face  114 . Since the roll is made in the direction of the rear face, it may be described as being a “reverse” roll. In another embodiment, the airbag cushion may be folded, instead of rolled. However, it will be noted that as consecutive folds are made, they may begin to resemble rolls. 
         [0076]      FIGS. 12C-12D  depict the airbag assembly  100  of  FIG. 12B  after the folded portion of the upper tucked portion of the airbag cushion has continued to be rolled towards rear face  114  in the direction of bag strap  150 . As cushion  110  is rolled, the cushion comprises a rolled inflatable airbag cushion  122 . As noted previously, attachment area  120  is located on front face  113  of cushion  110 , and bag strap  150  is coupled to the cushion at cushion portion  151  of the bag strap. Cushion  110  may continue to be rolled in the direction of bag strap  150  until rolled cushion  122  is rolled to fold  109  of the cushion. As such, cushion portion  151  of bag strap  150  may be partially rolled with the cushion. A next step in the packaging method disclosed herein may comprise wrapping bag strap  150  around cushion  110  such that rear face  164  of the bag strap is on the inside of the wrap and front face  163  is on the outside of the packaged airbag assembly. 
         [0077]      FIGS. 13A-13B  depict airbag cushion assembly  100  from front elevation views. Visible in the figures are cushion  110 , and bag strap  150  that has cushion portion  151 , inflator insert aperture  153 , inflator stem aperture  154 , inflator engagement apertures  156 , strap aperture  157 , folded engagement portion  158 , loop  160 , perforations  162 , front face  163 , rear face  164 , and tear stitching  166 . 
         [0078]    In the depiction of  FIG. 13A  the assembly is at the same stage of packaging as depicted in  FIG. 12D . Cushion  110  has been rolled such that it comprises a rolled cushion  122  and rear face  164  of bag strap  150  is positioned such that it can be wrapped around the rolled airbag cushion. As noted herein, inflator insert aperture  153  is aligned with cushion  110  inflator insert aperture  123  and inflator mounting stem aperture  154  is aligned with inflator mounting stem aperture  124 . 
         [0079]      FIG. 13B  depicts a next step in the method for packaging the airbag cushion, which may comprise wrapping bag strap  150  around rolled cushion  122  such that inflator stem engagement apertures  156  are aligned with inflator insert apertures  123 / 153  and inflator mounting stem apertures  124 / 154 . Since the rear face of bag strap  150  is on the inside of the packaged airbag cushion, front face  163  is visible. If an optional stabilizer strap is present, it may protrude through strap aperture  157 . Prior to completing rolling cushion  110 , an inflator may be inserted in cushion  110  such that the inflator mounting stems protrude through apertures  123 / 153 , and apertures  156 , which are located in the folded engagement portion  158  of bag strap  150 . The length of bag strap  150  is configured such that loop  160  is located at a predetermined position on rolled cushion  122 . Since loop  160  is located at a predetermined location, perforations  162  and tear stitching  166  are also located at predetermined locations on rolled cushion  122 . 
         [0080]      FIG. 14  depicts a portion of airbag assembly  100  from a side elevation view after cushion  110  has been placed in a rolled configuration  122 , the rolled cushion has been wrapped by bag strap  150 , and an inflator  180  has been inserted into the cushion. Attachment area  120  of cushion  110  is the area to which inflator  180  can be attached as well as the area to which cushion portion  151  of the bag strap is coupled. In the packaged configuration, folded engagement portion  158  is adjacent to cushion portion  151 , rear face  164  is adjacent to the wrapped cushion  122 , and front face  163  is located on the outside of the packaged airbag assembly. First inflator mounting stem  182  and second Inflator mounting stem (not visible) may protrude through cushion  110  attachment area  120 , bag strap  150  cushion portion  151 , and folded engagement portion  158 . Bag strap loop  160  is located at a predetermined location on cushion  110 , and the loop is oriented such that the apex  161  of the loop is between the bag strap and the cushion. 
         [0081]      FIG. 15  is a perspective view of airbag assembly  100  after the airbag cushion has been folded and/or rolled into a folded configuration, wrapped by the bag strap, and placed into an airbag housing  190 . Housing  190  may comprise a metal or plastic container to which the inflatable airbag cushion may be fixedly attached. Housing  190  is configured to be mounted within a vehicle and serves to specifically position airbag assembly  100  so that the inflatable cushion may deploy with predetermined characteristics. Housing  190  is configured to fluidly couple inflator  180  with the inflatable void of the inflatable airbag cushion, as well as fixedly couple the airbag cushion to a vehicle structure. Housing  190  may comprise a stabilizer strap aperture  191 , through which stabilizer strap  170  protrudes. A mounting aperture  172  formed in stabilizer strap  170  may be received by a mounting component  192  on housing  190 . In the depicted embodiment, mounting component  192  comprises a mounting hook; however in other embodiments, the mounting component may comprise a tab, an aperture for receiving hardware, or a linear extension. Housing  190  may further comprise a plurality of apertures (not visible) through which first and second inflator mounting stems  182  and  183  can protrude. First and second inflator mounting stems  182  and  183  may receive mounting hardware  194 , such that the inflator, bag strap, and cushion may be fixedly coupled to the housing. 
         [0082]    Inflator  180  is configured to be activated in response to predetermined vehicle conditions as determined by vehicle sensors. Upon activation, the inflator rapidly generates or releases inflation gas, which forces the airbag cushion through a cosmetic cover and rapidly inflates the cushion. The inflator may be one of several types, such as pyrotechnic, stored gas, or a combination inflator. Additionally, the inflator may comprise a single or multistage inflator. As will be appreciated by those skilled in the art, one or more vehicle sensors of a variety of types and configurations can be utilized to configure a set of predetermined conditions that will dictate whether the inflator is activated. For example, in one embodiment, a seat rail sensor is utilized to detect how close or far away from an airbag deployment surface an occupant&#39;s seat is positioned. In another embodiment, a seat scale may be used to determine whether an occupant is occupying the seat and if so, ascertain an approximate weight of the occupant. In yet another embodiment an optical or infrared sensor may be used to determine an occupant&#39;s approximate surface area and/or distance from an airbag deployment surface. In another embodiment, an accelerometer is employed to measure the magnitude of negative acceleration experienced by a vehicle, which may indicate whether an accident has occurred and the severity of the accident. Additionally, a combination of these and other suitable sensor types may be used. 
         [0083]      FIGS. 16-20  are various views of portions of another embodiment of an inflatable cushion airbag assembly  200 , wherein the figures depict structures used in a method for coupling an inflator to an airbag cushion membrane and airbag housing. The figures also depict a stabilizer strap that aids the cushion in achieving predetermined deployment characteristics. Inflatable cushion airbag assembly  200  may be configured similarly and may function similarly as inflatable cushion airbag assembly  100 , described herein. Assembly  200  may comprise an inflatable cushion membrane, a stabilizer strap, an inflator, and an airbag housing. 
         [0084]      FIG. 16  is a close up cutaway perspective view of a portion of inflatable cushion airbag assembly  200 . Inflatable cushion membrane  210  may be configured like cushion membrane  110 , described herein, or cushion  210  may be configured differently. Cushion  210  defines and inflatable void that is formed by a seam  207  that comprises stitching  206 . Cushion  210  may comprise a stabilizer strap  270  that is formed by a loop of nylon webbing that defines a mounting aperture  272 . Strap  270  may be about 10 mm wide and has a predetermined length. Stitching  271  may be employed to couple strap  270  to cushion  210 . 
         [0085]      FIG. 17  is a top perspective view of airbag assembly  200 , wherein airbag cushion  210  is located adjacent to housing  290  prior to the cushion being coupled to the housing. Cushion  210  comprises a folded middle portion  204 , an inflator attachment area, an inflator insert aperture  223 , and an inflator stem aperture  224 . Strap  270  may be positioned on cushion  210  such that a lowest portion  273  of stitching  271  is aligned with the centers of apertures  223  and  224 . Mounting aperture  272  of strap  270  is configured to be received by a strap hook  292  located on housing  290 . Housing  290  also comprises apertures  293  that are configured to receive inflator mounting stems. 
         [0086]      FIG. 18  is a close up cutaway perspective view of assembly  200 , wherein cushion  210  and housing  290  have been rotated such that a strap aperture  291  is visible. Stabilizer strap  270  protrudes through strap aperture  291  and extends to strap hook  292 . Strap mounting aperture  272  is configured to fit over and be retained by strap hook  292 . 
         [0087]      FIGS. 19A-20  are perspective views of a portion of inflatable cushion airbag assembly  200 , wherein the figures depict a method and structures for coupling an inflator to an airbag cushion membrane and airbag housing. Inflator  280 , cushion  210 , and housing  290  are configured such that they may be employed in a method for coupling an airbag cushion to an airbag housing. 
         [0088]      FIG. 19A  is a close up cutaway perspective view of a portion inflatable cushion airbag assembly  200 , which depicts a first step in the method, wherein the step may comprise inserting first end  284  of inflator  280 . Also, first inflator stem  282  is inserted into inflator insert aperture  223  of cushion  210 . Cushion  210  comprises inflator insert aperture  223  and inflator stem aperture  224 , which have diameters D 3  and D 2 , respectively, which are of predetermined magnitudes. Diameter D 2  of inflator mounting stem aperture  224  is configured such that it can receive a mounting stem from an inflator. As such the diameter of the mounting stem aperture may be about equal to, or slightly larger than the diameter of the mounting stem. Diameter D 3  of aperture  223  is configured such that the aperture can accommodate the diameter D 4  of inflator  280 . As such, D 3  of aperture  223  may be greater than the diameter D 4  of inflator  280 , or the diameters may be of about equal magnitude. In some embodiments, the magnitude of D 2  may be from about 4.0 mm to about 8.0 mm. In one embodiment, D 2  has a magnitude of about 6.5 mm. In some embodiments, the magnitude of D 3  may be from about 20 mm to about 30 mm. In one embodiment, D 3  has a magnitude of about 25 mm. The inflator insert aperture and/or the inflator mounting stem aperture may be strengthened and/or reinforced by stitching or additional material. In some embodiments, the magnitude of inflator diameter D 4  may be from about 20 mm to about 30 mm. In one embodiment, D 4  has a magnitude of about 25 mm. 
         [0089]    Inflator  280  may comprises a pyrotechnic inflator with a tubular body  281 , from which first and second mounting stems  282  and  283  protrude perpendicularly from the inflator body. The inflator is defined by a first end  284  and a second end  285 , wherein the first end may have one or more vents  286  through which inflation gas can be expelled. Inflator  280  comprises a predetermined length L 4 . In some embodiments, the magnitude of inflator length L 4  may be from about 100 mm to about 120 mm. In one embodiment, L 4  has a magnitude of about 108 mm. A distance between mounting stems may be from about 70 mm to about 90 mm. In one embodiment, the distance between mounting stems is about 80 mm. As such, the distance between the inflator insert aperture and the inflator mounting stem aperture may be from about 100 mm to about 120 mm, and in one embodiment, the distance is about 80 mm. 
         [0090]      FIG. 19B  is a close up cutaway perspective view of the inflatable cushion airbag assembly of  FIG. 94A  after first end  284  and first mounting stem  282  of the inflator has been inserted into the inflator insert aperture. The method may further comprise pushing inflator  280  toward inflator stem aperture  224  of cushion  210 . Inflator  280  may continue to be pushed in the direction of inflator stem aperture  224  until first inflator stem  282  is approximately aligned with aperture  224 , but second end  285  has not been pushed through inflator insert aperture  223 . 
         [0091]      FIG. 19C  is a close up cutaway perspective view of the inflatable cushion airbag assembly  200  of  FIG. 19B . A method for coupling an airbag cushion to an airbag housing via an inflator may further comprise threading first mounting stem  282  through inflator stem aperture  224 . When inflator  280  is positioned properly, first end  284  is located within cushion  210 , inflator stem  282  protrudes through aperture  224 , and second inflator stem  283  and second end  285  protrude through aperture  223 . Stem  283  may abut cushion  210  at a rim of aperture  223 . The diameters of first inflator stem  282  and inflator stud aperture  224  may be configured such that during deployment, the junction between the stem and the aperture is substantially airtight. Likewise, the diameters of inflator body  281  and inflator insert aperture  223  may be configured such that during deployment, the junction between the inflator and the aperture is substantially airtight. 
         [0092]      FIG. 20  is a close up cutaway perspective view of the inflatable cushion airbag assembly  200  after another step in a method for attaching an inflator has been performed. The method may further comprise threading first and second inflator stems  282  and  283  of inflator  280  through corresponding housing mounting apertures  293 . Cushion  210  may then be fixedly attached to housing  290  by employing mounting hardware that matingly engages first and second inflator stems  282  and  283 , such as bolts  290 . The previous methods may be said to be methods for attaching an inflator or methods for attaching an airbag cushion to an airbag housing. 
         [0093]      FIG. 20  also depicts stabilizer strap  270  after the strap has been threaded through the strap aperture (not shown) and has been received by strap hook  292 . Stabilizer strap  270  may or may not be used in combination with the structures associated with the methods for coupling an airbag cushion to a housing via an inflator, as described above. Stabilizer strap  270  may be used in combination with cushion  210  and inflator  280 , so that during inflatable airbag cushion deployment, the cushion can not rotate around the inflator and cushion attachment points. As such, the stabilizer strap prohibits the airbag cushion from skewing during deployment. 
         [0094]    One skilled in the art will appreciate that a variety of inflators and airbag housings may be used without deviating from the sprit of the present disclosure. For example, the size and shape of the inflators may differ from those described herein. Further, the inflator mounting stems may not be integral to the inflator, but rather, in some embodiments, an inflator housing may be employed that provides the mounting stems. Additionally, the inflator and/or housing may comprise less than or more than two mounting stems and those mounting stems may be oriented axially to the inflator body, rather than perpendicularly as described herein. Airbag housing  290  may not comprise a complete housing, but rather may define a mounting structure that may or may not be a subcomponent of an airbag housing. 
         [0095]    The present disclosure is related to two U.S. patent applications entitled, “KNEE AIRBAG ASSEMBLIES CONFIGURED FOR INFLATOR INSERTION AND INFLATOR-MEDIATED COUPLING TO AN AIRBAG HOUSING,” and, “INFLATABLE KNEE AIRBAG ASSEMBLIES WITH BAG STRAPS FOR WRAPPING THE AIRBAGS AND OPTIMIZING DEPLOYMENT,” which were filed on the same day as the present disclosure and are hereby incorporated by reference. 
         [0096]    Any methods disclosed herein comprise one or more steps or actions for performing the described method. The method steps and/or actions may be interchanged with one another. In other words, unless a specific order of steps or actions is required for proper operation of the embodiment, the order and/or use of specific steps and/or actions may be modified. 
         [0097]    Without further elaboration, it is believed that one skilled in the art can use the preceding description to utilize the present disclosure to its fullest extent. The examples and embodiments disclosed herein are to be construed as merely illustrative and not a limitation to the scope of the present disclosure in any way. 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 disclosure described herein. In other words, various modifications and improvements of the embodiments specifically disclosed in the description above are within the scope of the appended claims. Note that elements recited in means-plus-function format are intended to be construed in accordance with 35 U.S.C. § 112¶6. The scope of the disclosure is therefore defined by the following claims.