Abstract:
Some embodiments are directed to an assembly for housing and covering a vehicle airbag in an un-deployed state. The assembly can include a hollow housing that defines an interior that is configured to house the airbag in the un-deployed state. The housing can include a door having a linearly extending primary weakened portion spanning longitudinally opposing ends of the housing. The housing door can also include a pair of angled seams that each extend proximate the primary weakened portion to a location adjacent opposing corners of the door. The assembly can also include an intermediate layer disposed over and joined to the housing door, and an exterior layer disposed over and joined to the intermediate layer.

Description:
BACKGROUND 
       [0001]    The disclosed subject matter relates to methods and apparatus for restraining vehicular passengers. More particularly, the disclosed subject matter relates to vehicular airbags and airbag systems, methods of inflating vehicular airbags, and methods of manufacturing vehicular airbags and airbag systems. 
         [0002]    Vehicles can be provided with various systems and apparatus for restraining vehicular passengers, such as in the event of a collision. For example, some related art vehicles are provided with airbags that inflate if forces are sensed or otherwise detected that indicate a collision or other event that may transmit potentially harmful forces to a vehicular passenger. Under these conditions, the airbag is rapidly inflated for the purpose of restraining the vehicular passenger to prevent or reduce injuries, such as by providing a buffer between the passenger and other objects, e.g., portions of the vehicle&#39;s interior. As one example, in the event of a vehicular front collision, the airbag is configured and oriented to deploy between the passenger and a portion of the vehicular interior immediately in front of the passenger. The forces resulting from the collision cause the passenger to move forward and contact the airbag instead of portions of the vehicular interior that would otherwise be contacted, thereby reducing, mitigating or preventing passenger injuries. 
       SUMMARY 
       [0003]    Typical airbag systems include an inflatable airbag disposed within an interior portion of a hollow housing or chute when the airbag is in an un-deployed or folded state. The interior portion of the housing can be defined by four sides, and a top chute door. Many of these housings are configured so that at least a portion of the airbag can exit the chute via the chute door so as to be deployed within the passenger compartment, e.g., to deploy between the passenger and a portion of the vehicle interior immediately in front of the passenger. 
         [0004]    In some airbag systems, the airbag is inflated while being disposed within the chute, and the chute door is configured to tear to allow the airbag to pass therethrough and thereby become deployed within the passenger compartment. It may therefore be beneficial for the chute door to be configured to effectively retain the airbag in its un-deployed and folded state, but to effectively and efficiently tear as the airbag is inflated. In some cases, it is beneficial for the chute door to be configured to provide reduced or minimal resistance or impedance of the airbag as it is in the act of deployment so that the chute door and airbag may open in a predetermined manner. 
         [0005]    Some chute doors include a longitudinally extending seam that extends from one longitudinal end of the chute door to the opposing longitudinal end, and that is configured to tear as the airbag is inflated. This tearing thereby divides the chute door into opposing sides with a gap therebetween, thereby allowing the inflating airbag to pass through the gap into the passenger compartment. Embodiments are intended to include any and all seam structures and seam locations to facilitate this separation. In some embodiments, the longitudinal seam extends at an angle relative to the direction of elongation of the chute door. For example, the longitudinal seam can extend diagonally across a rectangular chute door. In some of these embodiments, each end of the longitudinal seam terminates at or adjacent a corner of the chute door. 
         [0006]    In some embodiments, the chute door defines other seams or areas of weakness in addition to the longitudinal seam. For example, two smaller seams or areas of weakness (angled seams) can be provided to extend from the longitudinal seam to opposing corners of the chute door. In some of these embodiments, the smaller angled seams or areas of weakness each terminate at or adjacent a corner of the chute door. In some of these embodiments, the smaller angled seams or areas of weakness can be defined by a series of spaced perforations. In some of these cases, the spaced perforations can be generally elliptically shaped with opposing pointed longitudinal ends. 
         [0007]    The above structures of the longitudinal seam and smaller seams or areas of weakness may be beneficial for various reasons. For example, these structures may facilitate deployment of the airbag with reduced resistance or impedance so that the airbag may open in a predetermined manner. In addition, these seams or areas of weakness may interact with other airbag assembly components, such as other layers, to achieve the above and other advantages, such as to facilitate a smooth and more regular exterior appearance, e.g., for aesthetics. 
         [0008]    The airbag assembly may include other layers, including a layer disposed over or directly on the chute door. This layer may be an intermediate layer and can be formed of any material and fashioned into any configuration. In some embodiments, the intermediate layer is formed of fabric and can be termed a spacer fabric layer. The intermediate layer may be formed as a unitary sheet having perforations over the longitudinal seal of the chute door. Alternatively, the intermediate layer can be formed of two separate sheets that are separated at a location over the longitudinal seal of the chute door. In other words, the longitudinal seam can be contiguous with the perforations in the unitary sheet or the gap separating the two separate sheets of the intermediate layer. This layer may be advantageous for several reasons, such as to enhance aesthetics and/or haptics of the airbag assembly by facilitating a relatively smooth and regular exterior appearance and/or feel. 
         [0009]    The airbag assembly may also include an exterior layer that is disposed over or directly on the intermediate layer. This exterior layer may be exposed to the passenger compartment and be configured to enhance aesthetics. In some of these embodiments, the exterior layer includes an exterior seam that is disposed proximate the longitudinal seam of the chute door and the gap separating the separate sheets of the intermediate layer. For example, the exterior seam can extend directly over the longitudinal seam and the gap to thereby facilitate deployment of the airbag upon inflation. 
         [0010]    Embodiments are intended to include or otherwise cover any exterior seam configuration. In some embodiments, the seam includes a burst stitch, and a pair of backstitch portions disposed at opposing ends of the burst stitch. The burst stitch can be formed using a relatively weak thread, which allows the airbag to rip apart the burst stitch during deployment. The backstitch portions can be formed using a relatively stronger thread that stops or impedes further separation of the exterior layer, i.e., separation beyond the burst stitch. 
         [0011]    In some embodiments, the exterior layer is formed of a material and otherwise configured to enhance aesthetics. For example, the exterior layer can be formed of leather, and may not include other seams or similar structures over the smaller seams or areas of weakness (angled seams) of the chute door. Instead, the exterior layer can be formed of a material (leather) that is sufficiently weak over the smaller seams or areas of weakness (angled seams) to naturally tear and facilitate airbag deployment. This configuration may enhance aesthetics, such as by enhancing a relatively smooth and regular appearance. 
         [0012]    Some embodiments are therefore directed to an assembly for housing and covering a vehicle airbag in an un-deployed state. The assembly can include a hollow housing that defines an interior that is configured to house the airbag in the un-deployed state. The housing can include a door having a linearly extending primary weakened portion spanning longitudinally opposing ends of the housing. The housing door can also include a pair of angled seams that each extend proximate the primary weakened portion to a location adjacent opposing corners of the door. The assembly can also include an intermediate layer disposed over and joined to the housing door so that the intermediate layer is configured to separate along separation portions adjacent the primary weakened portion and the pair of angled seams, and an exterior layer disposed over and joined to the intermediate layer so that the exterior layer is configured to separate along separation portions of the intermediate layer. 
         [0013]    Some other embodiments are directed to a vehicle dashboard assembly that includes a center console, and a dashboard having a center dashboard portion disposed above the center console and a passenger dashboard portion. The passenger dashboard portion includes an airbag assembly having an airbag and a housing assembly that is configured to house and cover the airbag in an un-deployed state. The airbag assembly can include a hollow housing that defines an interior that is configured to house the airbag in the un-deployed state. The housing can include a door having a linearly extending primary weakened portion spanning longitudinally opposing ends of the housing. The housing door can also include a pair of angled seams that each extend proximate the primary weakened portion to a location adjacent opposing corners of the door. The airbag assembly can also include an intermediate layer disposed over and joined to the housing door so that the intermediate layer is configured to separate along separation portions adjacent the primary weakened portion and the pair of angled seams, and an exterior layer disposed over and joined to the intermediate layer so that the exterior layer is configured to separate along separation portions of the intermediate layer. 
         [0014]    Still other embodiments are directed to a method of manufacturing an assembly for housing and covering a vehicle airbag in an un-deployed state. The method can include: configuring a hollow housing to define an interior capable of housing the airbag in the un-deployed state; forming the housing to include a door having a linearly extending primary weakened portion spanning longitudinally opposing ends of the housing and extending at an angle relative to a longitudinal direction of the housing, and such that the housing door also includes a pair of angled seams that each extend proximate the primary weakened portion to a location adjacent opposing corners of the door; disposing an intermediate layer over the housing door; disposing an exterior layer over the intermediate layer; and forming a stitched portion in the exterior layer directly over at least a section of the primary weakened portion of the housing door. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    The disclosed subject matter of the present application will now be described in more detail with reference to exemplary embodiments of the apparatus and method, given by way of example, and with reference to the accompanying drawings, in which: 
           [0016]      FIG. 1  is a perspective view of part of a dashboard of an exemplary vehicle in accordance with the disclosed subject matter, the dashboard including a passenger airbag assembly therein. 
           [0017]      FIG. 2  is a side view of a cross section of the passenger airbag assembly of  FIG. 1 . 
           [0018]      FIG. 3  is a perspective view of a cover layer of the passenger airbag assembly of  FIG. 1 . 
           [0019]      FIG. 4  is a perspective view of a spacer layer of the passenger airbag assembly of  FIG. 1 . 
           [0020]      FIG. 5  is a perspective view of a substrate layer and a chute portion of the passenger airbag assembly of  FIG. 1 . 
           [0021]      FIG. 6  is a perspective view of the substrate layer of the passenger airbag assembly of  FIG. 5 . 
           [0022]      FIG. 7  is a perspective view of the chute portion of the passenger airbag assembly of  FIG. 5 . 
           [0023]      FIG. 8  is a bottom view of the substrate layer and the chute portion of the passenger airbag assembly. 
           [0024]      FIG. 9  is a side view a cross section of a part of the substrate layer and an adjacent part of the chute portion. 
           [0025]      FIG. 10  is a perspective view of the substrate layer and the chute portion of the passenger airbag assembly. 
           [0026]      FIG. 11  is a top view of the chute portion of the passenger airbag assembly of  FIG. 11 . 
           [0027]      FIG. 12  is a perspective view of an underside of part of the cover panel of the passenger airbag assembly. 
           [0028]      FIG. 13  is a perspective view of the substrate layer and the chute portion of the passenger airbag assembly, with the chute portion shown in a deployed state. 
           [0029]      FIG. 14  is a plan view of a bottom side of an airbag door of the chute portion. 
           [0030]      FIG. 15  is a plan view of the bottom side of the airbag door of  FIG. 14   
           [0031]      FIG. 16  is a plan view of a top side of the substrate layer and the chute portion of the passenger airbag assembly, the chute portion shown in a partially deployed state. 
           [0032]      FIG. 17  is a plan view of a top side of the spacer layer of the passenger airbag assembly. 
       
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0033]    A few inventive aspects of the disclosed embodiments are explained in detail below with reference to the various figures. Exemplary embodiments are described to illustrate the disclosed subject matter, not to limit its scope, which is defined by the claims. Those of ordinary skill in the art will recognize a number of equivalent variations of the various features provided in the description that follows. 
         [0034]    Certain embodiments of airbag assembly  40  are disclosed below, and  FIGS. 1-20  illustrate some of these embodiments. However, embodiments are intended to include or otherwise cover many different embodiments and structures for facilitating airbag deployment. 
         [0035]    The embodiments are disclosed below and in the context of an airbag assembly of an automobile. However, the embodiments are intended to be applicable to any automobile airbag assembly, any type of automobile, and any type of vehicle, and to further be applicable to non-vehicular safety systems. 
         [0036]    Embodiments are also disclosed below in the context of a passenger airbag (PAB) assembly, and specifically a dashboard airbag. However, embodiments are intended to include or otherwise cover any type of airbag assembly, including assemblies for front airbags such as steering wheel and other types of dashboard airbags, side curtain airbags, knee airbags, and other types of side airbags such as torso airbags. 
       I. Vehicle and Airbag Lid Assembly 
       [0037]      FIG. 1  is a partial perspective view of a vehicle  30  showing parts of a dashboard  32  and a center console  34 . The vehicle  30  shown in  FIG. 1  is primarily for use on paved roadways, and can be referred to as a passenger vehicle. However, as indicated above, the disclosed airbag assembly  40  can be used with any vehicle that is configured to travel along any one or combination of improved, unimproved, and unmarked roadways and paths constituted by gravel, dirt, sand, etc. For example, embodiments are intended to include or otherwise cover any other type of automobile, including passenger car, truck, ATV, etc. In fact, embodiments are intended to include or otherwise cover configurations of the airbag assembly  40  for use in any other type of vehicle, such as an aircraft, boat, ship, train, spacecraft, etc. Some other embodiments can be used in non-vehicular carrier applications, such as for amusement park rides or any other situation where airbag deployment can enhance outcomes subsequent to transmission of a force. 
         [0038]    The exemplary vehicle  30  can include the dashboard  32  having portions comprising a center dashboard portion  33  and a passenger dashboard portion  35  being provided adjacent each other. The center console  34  can be provided below the center dashboard portion  33 , and may extend between passenger and driver seats. The passenger dashboard portion  35  can include the airbag assembly  40 , as well as a glove compartment  36  or other storage means such as a shelf. The glove compartment  36  can be provided below the airbag assembly  40 , or may alternatively be provided in front of the airbag assembly  40 . In the embodiment shown in  FIG. 1 , the airbag assembly  40  is provided at an upper portion of the passenger dashboard portion  35  such that a top layer  42  of the airbag assembly  40  serves as an upper surface of the passenger dashboard portion  35 . 
         [0039]    However, the various embodiments are intended to include or otherwise cover any configuration or position of the airbag assembly  40 , such as but not limited to the airbag assembly  40  being included in the center dashboard portion  33 , a driver dashboard portion (not shown), the center console  34 , or driver or passenger side doors (not shown). The airbag assembly  40  may also be included in a steering wheel, a seat, vehicle pillars, a roof, or any other vehicle component capable of deploying an airbag. In other words, the airbag assembly  40  can be formed within any component of the vehicle  30  capable of deploying an airbag. 
         [0040]    The exemplary airbag assembly  40  can be configured as a passenger airbag assembly intended to protect occupants from frontal impacts in the event of a vehicular collision. For example the passenger airbag assembly may be especially beneficial to protect occupants from contacting a front portion of the interior of the vehicle, such as the dashboard  32 , in the event of a front of the vehicle colliding with an object (or in accordance with any other event that may create a force resulting in the occupant colliding with the front portion of the interior of the vehicle, such as the dashboard). 
         [0041]    As discussed in more detail below, some embodiments are intended to include panels and perforated seams that enable the airbag assembly  40  to tear at the seams and fold open via the panels to safely facilitate deployment of the airbag. 
       II. Airbag Assembly Structure 
       [0042]    As described above,  FIG. 1  shows the airbag assembly  40  provided in the dashboard  32  of the vehicle  30 . The top layer  42  of the airbag assembly  40  is defined around an exterior edge by a top layer perimeter  46 , the top layer perimeter  46  extending from a part of the passenger dashboard portion  35  adjacent the glove compartment  36  to a part of the passenger dashboard portion  35  proximate a windshield  38 . The top layer  42  may be clipped to secured structures of dashboard  32 , or to other components of the airbag assembly  40  that will be described below. The top layer perimeter  46  can include stitching for increased aesthetics. 
         [0043]    The top layer  42  also can also a top seam  44  extending through an interior portion of the top layer  42 , the top seam  44  defining a character line of the dashboard  32 . The top seam  44  can extend from a side of the top layer  42  to an opposite side, or may alternatively span any two edges of the top layer perimeter  46 . Additionally, the top seam  44  may separate two panels of the top layer  42 , with the panels being coplanar, or alternatively with the panels extending along distinct yet intersecting planes, with the top seam  44  defining the intersection between them. In the present embodiment, a lower panel is provided proximate the glove compartment  36  while an upper panel is provided proximate the windshield  38 , the top seam  44  extending between the two panels from a portion of the top layer  42  adjacent the center dashboard portion  33  to a portion adjacent the passenger door (not shown). In some embodiments, the top layer  42  includes sections weakened or perforated sections made of the same construction, rather than the top seam  44  and first and second angled lines  49 A,B, as shown and described below. 
         [0044]      FIG. 2  illustrates an embodiment of the airbag assembly  40  including the top layer  42 , a spacer layer  52 , and a substrate layer  62 . In the present embodiment, the top layer  42  is shown divided into a first top panel  43 A and a second top panel  43 B, the first and second top panels  43 A,B being adjacent to each other and joined at the top seam  44 . The first top panel  43 A is contoured to slope downward away from the seam  44 , while the second top panel  43 B is approximately planar. However, other configurations of the first and second top panels  43 A,B are possible, such as but not limited to configurations in which both the first and second top panels  43 A,B are planar, or both are contoured to slope. The second top panel  43 B may also be sloped while the first top panel  43 A is planar. The top layer  42  can be formed of leather material such as genuine leather, artificial leather, suede, artificial suede, etc., and can be applied by hand wrapping to the spacer layer  52 , which is described below. 
         [0045]    The top seam  44  of the present embodiment is defined by opposing ends of the first and second top panels  43 A,B that are folded so as to point downwards towards the spacer layer  52 . Since the first and second top panels  43 A,B are pointed downwards at opposing ends, portions of upper surfaces of each panel extending along the top seam  44  contact each other. The extent of contact between the portions of the first and second top panels  43 A,B extending along the top seam  44  can be relatively large or small, being dependent upon the method of bonding between the first and second top panels  43 A,B at the top seam  44 . Folded ends of the first and second top panels  43 A,B that form the top seam  44  may be stitched together by any appropriate stitching method such as burst stitching formed of relatively weak thread so that the stitching is configured to loosen and/or tear and separate from a predetermined force, or otherwise attached by alternate means having similar separation qualities. 
         [0046]    In the present embodiment, the spacer layer  52  is disposed underneath of and adjacent the top layer  42  such that an upper surface of the spacer layer  52  is contoured to a lower, touching surface of the top layer  42 . Similarly, the spacer layer  52  includes a first spacer panel  53 A and a second spacer panel  53 B contacting the first top panel  43 A and the second top panel  43 B, respectively. In this way, the first and second spacer panels  53 A,B can be planar or sloped so as to match the configuration of the first and second top panels  43 A,B that they contact. The first and second spacer panels  53 A,B are separated by a seam gap  54 , the seam gap  54  spanning a distance approximately equal to a distance the top seam  44  of the top layer  42  extends. In the present embodiment, the top seam  44  is disposed within the seam gap  54  when then top layer  42  is overlaid onto the spacer layer  54 . Particularly, the seam gap  54  defines an elongated space, or channel, through which the top seam  44  extends. 
         [0047]    The present embodiment also includes the substrate layer  62  disposed underneath of and adjacent the spacer layer  52  such that an upper surface of the substrate layer  52  is contoured to a lower, touching surface of the spacer layer  52 . The substrate layer  62  can be planar or sloped so as to match the configuration of the first and second spacer panels  53 A,B that it contacts. 
         [0048]    Specifically, and as shown in more detail in  FIG. 5 , the substrate layer  62  can include a chute  70  disposed within a substrate surround  64 , the chute  70  shown in  FIG. 2  and the substrate surround  64  described below. The chute  70  can include a chute seam  72  of decreased thickness such that the chute  70  is thinner at the chute seam  72  than at other surrounding portions of the chute  70 . In the present embodiment, the chute seam  72  defines a concave space open to a lower surface of the substrate layer  62 , particularly the chute  70 . However, other embodiments may include the chute seam  72  being a concave space open to an upper surface of the substrate layer  62 , or particularly the chute  70 . The chute seam  72  can be disposed at a portion of the chute  70  proximate the seam gap  54  and the top seam  44  contained within. 
         [0049]      FIG. 3  illustrates a perspective view of the top layer  42  of the airbag assembly  40  in accordance with principles of the disclosed subject matter. 
         [0050]      FIG. 4  illustrates a perspective view of the spacer layer  52  of the airbag assembly  40  in accordance with principles of the disclosed subject matter. In the present embodiment, the spacer layer  52  includes the first and second spacer panels  53 A,B separated by the seam gap  54 . 
         [0051]      FIG. 5  illustrates a perspective view of the substrate layer  62  of the airbag assembly  40  in accordance with the principles of the disclosed subject matter. The substrate layer  62  includes the chute  70  disposed within the substrate surround  64 . As described below, the chute  70  is defined by a chute perimeter  71  within which the chute seam  72  and first and second chute perforations  74 A,B are disposed. The chute  70  may be positioned at an intermediate part of the substrate layer  62  such that the chute perimeter  71  is spaced from exterior edges of the substrate surround  64 . In some embodiments, the chute  70  and the substrate layer  62  can be formed by dual injection molding. In other embodiments, the chute  70  is configured so as to be insertable and snugly fit within a substrate aperture  66  disposed at the intermediate part of the substrate layer  62 . 
         [0052]      FIG. 6  a perspective view of the substrate surround  64  of the substrate layer  62  in accordance with the principles of the disclosed subject matter. As shown in  FIG. 6 , the present embodiment includes the substrate aperture  66  disposed at the intermediate portion of the substrate layer  62  and spaced from a substrate perimeter  63  to define the substrate surround  64 . 
         [0053]      FIG. 7  illustrates a perspective view of the chute  70  of the substrate layer  62  in accordance with the principles of the disclosed subject matter, with the chute  70  shown removed from the substrate surround  64  into which the chute  70  is inserted. The chute  70  can be approximately box-like in shape, and include a chute door  76  defining an upper surface of the chute  70 . The chute  70  may include ribs or other structural features to ensure structural rigidity. In the present embodiment, the chute door  76  includes the chute seam  72  and the first and second chute perforations  74 A,B. Furthermore, the chute seam  72  and the first and second chute perforations  74 A,B partition the chute door  76  into four chute panels that are configured to open upward and outward upon deployment of the airbag (not shown), which is housed in the chute  70 . The chute seam  72  separates the first and second chute panels  75 A,B from the third and fourth chute panels  75 C,D, serving as an initial area of separation in the chute door  76  when the airbag is deployed. Meanwhile, the first chute perforation  74 A separates the first chute panel  75 A from the second chute panel  75 B, while the second chute perforation  74 B separates the third chute panel  75 C from the fourth chute panel  75 D, serving as secondary areas of separation in the chute door  76  when the airbag is deployed. The manner in which the chute door  76  opens during airbag deployment is described below. 
         [0054]    In the present embodiment, chute  70  also includes a stepped portion surrounding the chute door  76  so that a main chute flange  78  is formed around the chute perimeter  71 . The main chute flange  78  is configured to contact and engage an underside surface of the substrate surround  64  adjacent the substrate aperture  66  such that when the main chute flange  78  contacts the underside surface of the substrate surround  64 , the chute door  76  is flush with an upper surface of the substrate surround  64  adjacent the substrate aperture  66 , as shown in more detail in  FIG. 9 .  FIG. 8  illustrates a plan view of an underside of the substrate layer  62  in accordance with the principles of the disclosed subject matter, the substrate layer  62  including the substrate surround  64  and the chute  70  positioned therein. The main chute flange  78  abuts the underside of the substrate surround  64  adjacent the substrate aperture  66  so as to ensure proper fitment of the chute  70  within the substrate surround  64 . 
         [0055]    As previously described,  FIG. 9  illustrates a side cross section view of a portion of the substrate layer  62  of  FIG. 8 . Particularly,  FIG. 9  shows fitment between the chute  70  and the substrate surround  64  when the chute  70  is inserted through the substrate aperture  66  so as to engage the substrate surround  64 . In the inserted state, the main chute flange  78  abuts a portion of the lower surface of the substrate surround  64  adjacent the substrate aperture  66 , thereby aligning the chute door  76  with a portion of the upper surface of the substrate surround  64  adjacent the substrate aperture  66 . Therefore, the chute door  76  and the substrate surround  64  are flush, and a tight fit is created between the chute perimeter  71  and edges of the substrate aperture  66 . Fitment between the chute  70  and the substrate surround  64  is thus without gaps or steps at the chute door  76 . 
         [0056]      FIG. 10  illustrates a perspective view of the airbag assembly  10  in accordance with the principles of the disclosed subject matter, including a chute area  45  disposed at a portion of the top layer  42  proximate the chute  70 , and specifically the chute door  76 , when the airbag assembly  10  is in an assembled state. The chute area  45  of the present embodiment includes an approximately rectangular portion of the top layer  42  aligned with the chute door  76  such that a chute area perimeter  47  traces the chute perimeter  71  defining outside edges of the chute door  76 . As described above, the top seam  44  extends through the chute area  45 , including first and second reinforced seams  48 A,B disposed along the top seam  44 , the first and second reinforced seams  48 A,B being spaced from each other and further disposed at opposing sides of the chute area perimeter  47 . 
         [0057]    In the present embodiment, the first and second reinforced seams  48 A,B extend along respective portions of the top seam  44 , with the first and second reinforced seams  48 A,B each extending from a portion of the top seam  44  within the chute area  45  to a portion of the top seam  44  outside of the chute area  45 . The first and second reinforced seams  48 A,B may be formed in any appropriate manner to maintain attachment between the first and second top panels  43 A,B at the first and second reinforced seams  48 A,B during airbag deployment, such as stitching, and specifically backstitching. As described below, a portion of the top seam  44  separates upon airbag deployment, and the first and second reinforced seams  48 A,B ensure that the top seam  44  only separates at a portion within the chute area  45 , restricted at both ends by the first and second reinforced seams  48 A,B. 
         [0058]    The top layer  42  of the airbag assembly  40  can also include first and second angled lines  49 A,B that approximately trace the first and second chute perforations  74 A,B of the chute  70 , such that upon airbag deployment, the first and second angled lines  49 A,B tear similarly to the first and second chute perforations  74 A,B. Therefore, the first and second angled lines  49 A,B extend from opposing portions of the chute area perimeter  47  to the top seam  44 . The first and second angled lines  49 A,B may not correspond to weakened or perforated portions of the top layer  42 , but rather to portions adjacent those configure to tear in other layers. Thus, despite the top layer  42  not being weakened along the first and second angled lines  49 A,B, the top layer  42  is still configured to separate along the first and second angled lines  49 A,B due to tearing of adjacent attached layers. 
         [0059]      FIG. 11  illustrates a plan view of the chute area  45  in accordance with the principles of the disclosed subject matter. The chute area  45  of the present embodiment is partitioned by the top seam  44  extending through an intermediate portion of the chute area  45 , as well as the first and second angled lines  49 A,B extending from respective portions of the chute area perimeter  47  to the top seam  44 . As shown, the top seam  44  and first and second angled lines  49 A,B partition the chute area  45  into four approximately right-angled triangles that together form the rectangular shape of the chute area  45 . Alternatively, the chute area  45  may be partitioned into a greater or fewer number of triangles, and the triangles can also be acute or obtuse. 
         [0060]    As shown in more detail in  FIG. 13 , and described below, the chute area  45  partitions include first and second top sections  50 A,B which are separated by the top seam  44 , and third and fourth top sections  50 C,D which are separated from the first and second top sections  50 A,B, respectively, by the first and second angled lines  49 A,B. Upon airbag deployment, the top seam  44  is configured to tear before the first and second angled lines  49 A,B so that the first and third top sections  50 A,C separate from the second and fourth top sections  50 B,D along the top seam  44 . Following separation of the first and second top panels  43 A,B at the chute area  45 , the first and second angled lines  49 A,B tear so that the first and third top sections  50 A,C separate from one another, as do the second and fourth top sections  50 B,D. Once the top seam  44  and the first and second angled lines  49 A,B have torn, the first, second, third and fourth top sections  50 A,B,C,D become separated flaps that fold outward and away from the chute area  45 , the first, second, third and fourth top sections  50 A,B,C,D being hinged at respective portions of the chute area perimeter  47 . In this configuration, the hinged portions of the chute area perimeter  47  are living hinges, however other configurations of hinges may be appropriate. 
         [0061]      FIG. 12  illustrates a perspective cross section view of an underside of the first reinforced seam  48 A of the airbag assembly  40  of  FIG. 10 . The first reinforced seam  48 A of the present embodiment is disposed along opposing edges of the first and second top panels  43 A,B where the edges are brought together to be joined. The first reinforced seam  48 A may be backstitched with thread or any other appropriate stitching material, or may alternatively be stitched with another method. Additionally, other attachment methods such as use of adhesives or attachment fixtures may be used to attach the first and second top panels  43 A,B together at the first reinforced seam  48 A. Although not specifically shown, the second reinforced seam  48 B may be configured similar to the first reinforced seam  48 A including the application of backstitching. In the present embodiment, the backstitching at the first and second reinforced seams  48 A,B serves to prevent the first and second top panels  43 A,B from separating along the top seam  44  at the first and second reinforced seams  48 A,B. 
         [0062]      FIG. 13  illustrates a perspective view of the airbag assembly  40  in accordance with the principles of the disclosed subject matter. In  FIG. 13 , the chute area  45  is shown in a state following airbag deployment wherein the top seam  44  and the first and second angled lines  49 A,B have torn and the first, second, third and fourth top sections  50 A,B,C,D have folded outwards and away with the deployed chute door  76 . The aforementioned elements are shown in configurations prior to and after deployment of the airbag to illustrate how they transition between the two states (undeployed and deployed). The order in which the aforementioned elements tear and fold is described above, however alternate configurations of the elements may warrant a varied deployment order. 
         [0063]    In the present embodiment, airbag deployment initiates a force within the chute  70  outward against an inner surface of the chute door  76 . This force tears the chute seam  72 , followed by the first and second chute perforations  74 A,B, which thereby are pushed outward against a lower surface of the spacer layer  52 , which is described below. The spacer layer  52  is subsequently pushed outward by the expansion of the airbag such that the force is transferred to a lower surface of the top layer  42 . Once transferred to the top layer  42 , that force causes the top seam  44  and the first and second angled lines  49 A,B to tear as described above, and the first, second, third and fourth top sections  50 A,B,C,D to fold outwards and away from the deployed chute door  76 . In this way, airbag deployment facilitates the tearing and unfolding of various layers of the airbag assembly  40 , including the substrate layer  62 , the spacer layer  52 , and the top layer  42 . 
         [0064]      FIG. 14  illustrates a partial plan view of an underside of the chute  70  of the airbag assembly  40  in accordance with the principles of the disclosed subject matter. Specifically,  FIG. 14  shows an underside of the chute door  76 , including the chute seam  72  and the first chute perforation  74 A. The first chute perforation  74 A can be formed as pointed elliptical perforations  79  spaced along the first chute perforation  74 A so as to be configured to propagate tearing of the first chute perforation  74 A. The elliptical perforations  79  may be oriented lengthwise, with pointed ends aligned along the first chute perforation  74 A. Alternatively, the elliptical perforations  79  may be oriented widthwise. Diamond shaped perforations may instead be used in place of the elliptical perforations  79  in some embodiments. A number of elliptical perforations  79  may vary depending on the ease with which the first chute perforation  74 A can tear. The elliptical perforations  79  serve to provide surrounding elements, such as the spacer layer  52 , with enough structural support to prevent warping of portions adjacent the first chute perforation  74 A. Additionally, the elliptical perforations  79  described above may be included in the second chute perforation  74 B, as well as any other tear seams or lines meant to tear in response to airbag deployment. 
         [0065]      FIG. 15  illustrates a partial plan view of the chute door  76  in accordance with the principles of the disclosed subject matter. Specifically,  FIG. 15  shows part of the first chute perforation  74  A including the elliptical perforations  79  described above. Spacing between consecutive elliptical perforations  79  can vary or remain constant, and the length and width of each elliptical perforation  79  can also vary depending on the appropriate tear propensity of the first chute perforation  74 A. Additionally, configurations of the elliptical perforations  79  including dimensional variances can be applied to the second chute perforation  74 B, or any other tear seam or line included in the airbag assembly  40 . 
         [0066]      FIG. 16  illustrates a partial plan view of the airbag assembly  40  in accordance with the principles of the disclosed subject matter, with airbag assembly  40  shown in a partially deployed state. Specifically,  FIG. 16  shows initial tearing of the top seam  44  and the first and second angled lines  49 A,B of the top layer  42 , and corresponding separation of the first, second, third and fourth top sections  50 A,B,C,D from one another. As described above, airbag deployment causes the top seam  44  to tear, followed by the first and second angled lines  49 A,B. Consequently, the first and second top panels  43 A,B separate from each other first. Then, the first and third top sections  53 A,C separate from each other, as do the second and fourth top sections  53 B,D. Alternate separation configurations may be appropriate depending on varying airbag deployment. 
         [0067]      FIG. 17  illustrates a partial perspective view of the spacer layer  52  of the airbag assembly  40  in accordance with the principles of the disclosed subject matter. In the present embodiment, the spacer layer  52  includes a first spacer line  56 A and a second spacer line  56 B extending from respective portions of the seam gap  54 . In some embodiments, the first and second spacer lines  56 A,B may not correspond to weakened or perforated portions of the spacer layer  52 , but rather to portions adjacent those configured to tear in other layers. Thus, despite the spacer layer  52  not being weakened along the first and second spacer lines  56 A,B, the spacer layer  52  may still be configured to separate along the first and second spacer lines  56 A,B due to tearing of adjacent attached layers, as will be described below. 
         [0068]    In other embodiments, the first and second spacer lines  56 A,B further include spacer perforation holes  58 . The first and second spacer lines  56 A,B, including the spacer perforation holes  58 , serve to provide surrounding elements with enough structural support to prevent warping of portions adjacent the spacer layer  52 . The first and second spacer lines  56 A,B are configured to tear upon deployment of the airbag such that after the first and second spacer panels  53 A,B separate at the seam gap  54 , the spacer perforation holes  58  being configured to propagate tearing in an approximately linear manner of the first and second spacer lines  56 A,B. Particularly, the first and second spacer lines  56 A,B initially tear at the spacer perforation holes  58  nearest the seam gap  54 , with adjacent spacer perforation holes  58  propagating the tears up to the last spacer perforation holes  58  farthest from the seam gap  54 . The first and second spacer lines  56 A,B, in combination with the seam gap  54 , allow the spacer layer  52  to separate into panels similarly to both the chute door  76  and the top layer  42  as a result of the airbag deploying. The first and second spacer lines  56 A,B of the present embodiment therefore extend at similar angles from the seam gap  54  as corresponding tear seams/lines of adjacent layers of the airbag assembly  40  such as the top layer  42  and the substrate layer  62 . 
         [0069]    In the present embodiment, the spacer perforation holes  58  may be of varying dimensions in length, width and shape, and may be spaced apart by a multitude of distances. Also, the spacer perforation holes  58  can extend an entire or partial length of the first and second spacer lines  56 A,B. The spacer perforation holes  58  serve to initiate tearing of the first and second spacer lines  56 A,B while providing support for the spacer layer  62  so as to maintain its shape and structure. 
       III. Alternative Embodiments 
       [0070]    In the disclosed embodiment, various structures are applied to a passenger airbag (PAB) of a vehicle. However, the disclosed structures may alternatively be applied to or modified to cover any type of airbag assembly, including assemblies for other front airbags such as steering wheel airbags, knee airbags, and other types of side airbags such as torso airbags and side curtain airbags. 
         [0071]    As disclosed above, embodiments are intended to be used with any type of vehicle. The power source of the vehicle can be an internal combustion engine, an electric motor, or a hybrid of an internal combustion engine and an electric motor. The power source configured as an internal combustion engine or a hybrid power source can have the engine output axis oriented in the longitudinal direction or in the traverse direction of the vehicle. The engine can be mounted forward of the front axles, rearward of the rear axles, or intermediate the front and rear axles. 
         [0072]    In the disclosed exemplary embodiments, the airbag assembly is included in the dashboard of the vehicle. However, the airbag assembly can be included in any component of the vehicle capable of deploying an airbag, such as the steering wheel, door panels, ceiling liner, pillars, etc. 
         [0073]    Embodiments of the airbag assembly are also intended to cover material layers that are configured to separate and tear apart in a variety of ways, such as by the inclusion of weakened thread in burst stitching as disclosed. Specifically, the tear line so described can instead incorporate construction similar to that of the angled tear lines as described above. 
         [0074]    Embodiments are also intended to include or otherwise cover methods of using and methods of manufacturing any or all of the elements disclosed above. The methods of manufacturing include or otherwise cover processors and computer programs implemented by processors used to design various elements of the airbag assembly disclosed above. 
         [0075]    While the subject matter has been described in detail with reference to exemplary embodiments thereof, it will be apparent to one skilled in the art that various changes can be made, and equivalents employed, without departing from the scope of the invention. All related art references discussed in the above Background section are hereby incorporated by reference in their entirety.