Abstract:
A side airbag extends along a side of an interior roof of a vehicle and is configured to restrain a head of a vehicle occupant when the airbag is deployed. The airbag includes an inboard panel, an outboard panel, and one or more seams configured to join the inboard panel and the outboard panel. The at least one or more seams include first seam portions and second seam portions. The first seam portions are subject to higher stress than the second seam portions when the airbag inflates. The first seam portions are reinforced by sewing or by at least one bead of energy absorbent sealant or adhesive.

Description:
BACKGROUND 
     The present disclosure relates generally to an airbag configured to deploy along an interior side of a vehicle. When inflated, the airbag is configured in the shape of a curtain. The present application is directed to a curtain airbag configured to more effectively restrain an occupant inside the vehicle when the vehicle is involved in a rollover or side impact type event. 
     The majority of airbag cushions are fabricated by a cut and sew process using linear fabrics or by a one-piece woven (OPW) process. In some cases, a sealant is placed between two layers of fabric prior to sewing in order to prevent leakage out of the cushion through the sewn seam. Reducing leakage provides for longer gas retention time. The sewing is typically applied along the entire seam throughout the cushion. The fabric may be coated to minimize gas leaking through the fabric. In the OPW cushions, the coating is typically applied on the outside because the inside is not accessible once the cushion is woven. Sewing of a large cushion, for example a head side airbag (inflatable curtain) can be time consuming. 
     It would be advantageous to provide a curtain airbag that takes less time to manufacture while also providing increased air tightness or gas retention time. It would also be advantageous to provide a curtain airbag with increased air tightness or gas retention time while costing less to fabricate and while using less thread material. In sum, it would be advantageous to provide a curtain airbag and airbag module that effectively restrains an occupant and is easier and less costly to manufacture. 
     SUMMARY 
     One embodiment of the disclosure relates to an airbag module for use in a vehicle to restrain an occupant of the vehicle in a side impact type collision. The airbag module includes an inflator configured to generate gas and an airbag coupled to the inflator and configured to deploy upon receiving gas from the inflator. The airbag includes a main chamber extending along a side of an interior roof of the vehicle and configured to restrain a head of a vehicle occupant when the airbag is deployed. The main chamber includes an inboard panel and an outboard panel joined together by seams. The seams include first seam portions and second seam portions. The first seam portions are subject to higher stress than the second seam portions when the airbag inflates. The first seam portions are reinforced by sewing or by at least one bead of energy absorbent sealant or adhesive. 
     Another embodiment of the disclosure relates to a side curtain airbag for use in a vehicle. The airbag includes a main chamber extending along a side of an interior roof of the vehicle and configured to restrain a head of a vehicle occupant when the airbag is deployed. The main chamber includes an inboard panel, an outboard panel, and one or more seams configured to join the inboard panel and the outboard panel. The at least one seams includes first seam portions and second seam portions. The first seam portions are subject to higher stress than the second seam portions when the airbag inflates. The first seam portions are reinforced by sewing or by at least one bead of energy absorbent sealant or adhesive. 
     Another embodiment of the disclosure relates to a side airbag extending along a side of an interior roof of a vehicle and configured to restrain a head of a vehicle occupant when the airbag is deployed. The airbag includes an inboard panel, an outboard panel, and one or more seams configured to join the inboard panel and the outboard panel. The at least one seams include first seam portions and second seam portions. The first seam portions are subject to higher stress than the second seam portions when the airbag inflates. The first seam portions are reinforced by sewing or by at least one bead of energy absorbent sealant or adhesive. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only, and are not restrictive of the invention as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features, aspects, and advantages of the present invention will become apparent from the following description, appended claims, and the accompanying exemplary embodiments shown in the drawings, which are briefly described below. 
         FIG. 1  is an isometric view of a vehicle including a side curtain airbag according to an exemplary embodiment. 
         FIG. 2  is a side view of a side curtain airbag with reinforcing sewing lines according to an exemplary embodiment. 
         FIG. 3  is a side view of a side curtain airbag with reinforcing sewing lines according to another exemplary embodiment. 
         FIG. 4  is a side view of a side curtain airbag including reinforcing sealant or adhesive beads according to an exemplary embodiment. 
         FIG. 5  is a side view of a side curtain airbag including reinforcing sealant or adhesive beads according to another exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , a vehicle  10  is shown including a side curtain airbag module  20  according to an exemplary embodiment. The side curtain airbag module  20  is provided to help restrain the occupants of the vehicle  10  in a side impact. The airbag module  20  includes an inflator or gas generator  22 , such as a conventional stored gas or gas generating inflator, and an inflatable cushion or airbag  24 . The curtain airbag  24  (shown unfolded) is preferably stored along the roof of the associated vehicle, for example along the vehicle roof side rail  12  above a window opening  16  in a conventional manner. The curtain airbag  24  is preferably secured in a folded state beneath a trim panel (not shown). The trim panel may be snapped, screwed, or otherwise secured in place over the inflator  22  and the packed, folded curtain airbag  24 . 
     The inflator  22  supplies gas for inflation/deployment of the restraint curtain airbag. The inflator  22  may be mounted along the vehicle roof side rail or in one of pillars of the vehicle frame (e.g., the B, C, or A pillar). Thus, the inflator may be considered an end or mid mount inflator depending on vehicle configuration and desired airbag deployment characteristics. During a vehicle side impact crash or rollover event, the inflator  22  is activated to supply pressurized gas to inflate the curtain airbag  24 . The inflation gas enters the curtain airbag  24  and drives the curtain airbag  24  away from a storage position and downward into a deployed position. 
     Referring to  FIGS. 2 and 3 , according to an exemplary embodiment, a curtain airbag  124 ,  224  includes a main chamber  130 ,  230  generally formed from a first panel  132 ,  232  (e.g., inboard panel, inner panel, front panel, etc.) and a second panel  134 ,  234  (e.g., outboard panel, outer panel, rear panel, etc.) that are coupled together by a plurality of seams  136 ,  236 . According to an exemplary embodiment, the first panel  132 ,  232  and the second panel  134 ,  234  may be a coated or uncoated nylon or polyester fabric or a polymeric film. The first panel  132 ,  232  and second panel  134 ,  234  may be joined or coupled together by an energy source (e.g., heat sealing or welding without another medium) or a sealant or adhesive, for example a silicone, polyurethane, rubber cement, etc. that has low enough ductility to be a structural sealant or adhesive (a non-energy or low-energy absorbent sealant or adhesive) and hold the panels together without much stretch. A gas generator or inflator  122 ,  222  is coupled to the airbag  124 ,  224  to introduce gas into the main chamber  130 ,  230  for inflation. 
     The curtain airbag  124 ,  224  has an inflation zone  140 ,  240  that is near or in proximity to the inflator  122 ,  222 . The pressure of inflowing gas from inflator  122 ,  222  in the inflation or sudden inflation zone  140 ,  240  is generally significantly higher than in the other areas of the airbag  124 ,  224 , especially at the initial stage of deployment. According to an exemplary embodiment, the portions of the seams  136 ,  236  that are located in the inflation zone  140 ,  240  are reinforced with sewing at sewn portions  144 ,  244 . According to some exemplary embodiments, the distance from the inflator  122 ,  222  (or opening leading to the inflator) to an edge of the inflation zone  140 ,  240  (the radius of the inflation zone  140 ,  240 ) may be at least about 250 mm. According to other exemplary embodiments, the distance from the inflator  122 ,  222  to an edge of the inflation zone  140 ,  240  may be of sufficient distance to include the first curvature of one of the seams  136 ,  236 . According to still other exemplary embodiments, the distance from the inflator  122 ,  222  to an edge of the inflation zone  140 ,  240  may be at least about 250 mm if the first curvature is within the 250 mm or may be greater than 250 mm to include the first curvature of one of the seams  136 ,  236  if the curvature is greater than 250 mm from the inflator  122 ,  222 . 
     The curtain airbag  124 ,  224  also has a high pressure/stress zone  142 ,  242  extending longitudinally across an upper portion of the airbag  124 ,  224 . The pressure of inflowing gas from inflator  122 ,  222  in the high pressure/stress zone  142 ,  242  is generally higher than in the lower area of the airbag  124 ,  224 . According to an exemplary embodiment, portions of the seams  136 ,  236  in high pressure/stress zone  142 ,  242  that have convex curvatures with respect to or facing towards the inflowing gas (pressure on the opposite side of the center of the curvature) are reinforced with sewing at sewing portions  144 ,  244 . According to another exemplary embodiment, portions of the seams  136 ,  236  in high pressure/stress zone  142 ,  242  that have convex curvatures of less than about 100 mm are reinforced with sewing. 
     Referring to  FIGS. 4 and 5 , the sewing reinforced portions of the seams  136 ,  236  in the inflation zone  140 ,  240  and in the high pressure/stress zone  142 ,  242  are reinforced with at least one bead of an energy absorbent sealant or adhesive  146 ,  246  instead of by sewing. The at least one bead of energy absorbent sealant or adhesive  146 ,  246  is applied along a high pressure side of the seams  136 ,  236 , for example on the side of the convex curvatures of the seams  136 ,  236  in the inflation zone  140 ,  240  and the high pressure/stress zone  142 ,  242 . The inner bead or beads of sealant or adhesive has a peel strength of less than or equal to that of the non-energy absorbent structural sealant or adhesive. According to various exemplary embodiments, the energy absorbent sealant may include a silicone, a polyurethane, a rubber cement, etc. that has higher ductility than the structural sealant or adhesive. The energy absorbent sealant may be the same material as the structural sealant but with a higher ductility or may be a different material with a higher ductility. For example, both the structural sealant and the energy absorbent material may be a silicone material, however the silicone material of the energy absorbent sealant is formulated or synthesized (e.g., via polymerization) to have a higher ductility or lower peel strength than the silicone material of the structural sealant. 
     According to various exemplary embodiments, the sewing reinforced portions of the seams  136 ,  236  in the inflation zone  140 ,  240  and in the high pressure/stress zone  142 ,  242  are the only portions of seams  136 ,  236  that are reinforced and the remaining portions of the seams are joined with a structural sealant or adhesive that is not as energy absorbent. According to other exemplary embodiments, only the portions of the seams  136 ,  236  in the inflation zone  140 ,  240  may be reinforced. According to still other exemplary embodiments, only the portions of the seams  136 ,  236  in the high pressure/stress zone  142 ,  242  may be reinforced. Because not all of the seams  136 ,  236  or all of the portions of the seams  136 ,  236  are reinforced, the airbag  124 ,  224  may be manufactured quicker and may cost less to produce, for example because of less or no usage of thread and because of less time to fabricate. 
     According to other exemplary embodiments, the curtain airbag  124 ,  224  may be divided into two or more compartments or chambers. Passages or ports may be provided between individual chambers such that the chambers are in fluid communication with each other. The various chambers, passages, and ports may also include inflation zones and/or high pressure/stress areas that can be reinforced by sewing and/or an energy absorbent sealant or adhesive. The curtain airbag  124 ,  224  may also include a plurality of un-inflated portions such as un-inflated portions that generally separate the chambers. 
     For purposes of this disclosure, the term “coupled” means the joining of two members directly or indirectly to one another. Such joining may be stationary in nature or moveable in nature and/or such joining may allow for the flow of fluids, electricity, electrical signals, or other types of signals or communication between the two members. Such joining may be achieved with the two members or the two members and any additional intermediate members being integrally formed as a single unitary body with one another or with the two members or the two members and any additional intermediate members being attached to one another. Such joining may be permanent or releasable in nature. 
     The construction and arrangement of the elements of the curtain airbag as shown in the various exemplary embodiments is illustrative only. Although only a few embodiments have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter recited herein. For example, elements shown as integrally formed may be constructed of multiple parts or elements, the position of elements may be reversed or otherwise varied, and the nature or number of discrete elements or positions may be altered or varied. It should be noted that the elements and/or assemblies of the system may be constructed from any of a wide variety of materials that provide sufficient strength or durability, including any of a wide variety of moldable plastic materials in any of a wide variety of colors, textures and combinations. Other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the exemplary embodiments.