Abstract:
An airbag module for protecting an occupant of a vehicle. The module includes an inflatable airbag. The airbag includes a front panel configured to contact the occupant when the airbag is deployed and a rear panel including an opening. The front panel and the rear panel may be connected together along the periphery of each of the panels. The module includes an inflator for providing gas to inflate the airbag. The inflator being positioned in the opening so that inflation gas escapes the inflator into the airbag. The tether includes a strap connected at a second end to the front panel and at a first end at a location proximate to the inflator. The tether is connected to the front panel by a curved seam elongated in one direction.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    The present application claims priority to and the benefit of U.S. Provisional Patent Application No. 62/031,349, filed Jul. 31, 2014. The foregoing provisional application is incorporated by reference herein in its entirety. 
     
    
     BACKGROUND 
       [0002]    The present application relates generally to the field of airbag modules. More specifically, the present application relates to a driver side front airbag (DAB) module having a tether connected to a panel of the cushion with an improved stitched seam. 
         [0003]    An inflatable airbag that uses an inflation device that generates gas through pyrotechnic ignition, stored gas or combination thereof typically requires diffusion of the gas into an airbag cushion to properly inflate the cushion and preserve the integrity of the cushion fabric. In a typical inflatable airbag, the inflation device ignites to burn a solid propellant, which turns to gas in order to inflate the airbag cushion. The airbag may include an internal tether that is configured to limit the rearward expansion (e.g., in a direction towards a driver of a vehicle) of the airbag cushion. 
         [0004]    Current airbags include a tether that is coupled to the front panel with a circular sewn seam. A reinforcement panel may be provided such that the circular sewn seam couples together three layers of fabric. The inflation forces on the airbag cushion during deployment can result in stress concentrations at the circular sewn seam, which could potentially degrade airbag performance. 
       SUMMARY 
       [0005]    An embodiment of an airbag module is disclosed herein. The airbag module is configured for protecting an occupant of a vehicle and includes an inflatable airbag. The airbag may include a front panel configured to contact the occupant when the airbag is deployed and a rear panel. The rear panel may include an opening for receiving inflation gas and or an inflator. The front panel and the rear panel may be integrally formed or connected together along the periphery of each of the panels by a seam such as a stitched seam. The module includes an inflator for providing gas to inflate the airbag. A tether for restraining the deployment of the airbag is provide in the interior of the inflatable chamber of the airbag. The tether includes a strap connected at a first end at a location proximate to the inflator and at a second end to the front panel. 
         [0006]    The tether is connected to the front panel by a curved seam elongated in one direction. The elongated seam reduces the stress concentrations from those associated with circular seams. The seam connecting the tether to the front face may be a closed curve that is elongated in one direction. The airbag may include a reinforcement panel positioned between the second end of the tether and the front panel. The reinforcement panel may be integrally formed with the second end of the tether and the tether may be folded over between the second end and the reinforcement panel so that the reinforcement panel is positioned between the second end and the front face. The reinforcement panel may be connected to the front panel by the same seam as the tether. 
         [0007]    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 
         [0008]    Features, aspects and advantages of the present invention will become apparent from the following description and the accompanying exemplary embodiments shown in the drawings, which are briefly described below. 
           [0009]      FIG. 1  is a schematic perspective view of a vehicle interior. 
           [0010]      FIG. 2  is a schematic side view of a vehicle interior, illustrating an inflated driver front airbag module, according to an exemplary embodiment. 
           [0011]      FIG. 3  is a schematic side cross-section view of the airbag module of  FIG. 2 . 
           [0012]      FIG. 4  is a view of the exterior of the airbag cushion, showing a pair of elongated seams configured to couple tethers to the airbag cushion. 
           [0013]      FIG. 5  is a top view of the elongated seam of  FIG. 4 . 
           [0014]      FIG. 6  is a view of the interior of the airbag cushion, showing the elongated seams of  FIG. 4 . 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    Referring to  FIGS. 1 and 2 , a vehicle  10  is shown according to an exemplary embodiment. The vehicle  10  includes one or more seats that are configured to receive an occupant  12  and are coupled to the vehicle. Airbags and airbag modules  20  may be provided at a variety of places within the vehicle to protect an occupant of the vehicle in a variety of impact scenarios. For example, airbags may be provided in the dashboard, proximate to the steering wheel, in the vehicle seats, in the door trim panels, in the headliner, etc. According to one exemplary embodiment, shown in  FIG. 1 , the airbag module  20  is a driver front airbag that is coupled to the steering column  14 . However, the airbag module, as described below, may be adapted to be provided at a variety of different locations within the interior of the vehicle such as a passenger front airbag, a side curtain airbag, a knee airbag, a center side-impact airbag, etc. 
         [0016]    According to an exemplary embodiment, the airbag module  20  of  FIG. 2  includes an inflator (e.g., gas generator)  24  and an airbag cushion  22  that is contained in an uninflated state in a housing  26 . The airbag module  20  further includes one or more tethers  30  that are coupled to the cushion in such a way as to control deployment of the cushion  22 , such as in the rearward direction. The inflator  24 , such as a pyrotechnic gas generator, generates a gas that rapidly inflates the airbag cushion  22  in an impact or vehicle collision. The gas may be generated through pyrotechnic ignition, stored gas or combination thereof. A diffuser (not shown) may be provided to diffuse the gas into the airbag cushion  22  to properly inflate the cushion and preserve the integrity of the cushion fabric. The diffuser is configured to diffuse the inflating gas and trap any particulate byproduct generated by the inflator  24 . 
         [0017]    According to one exemplary embodiment, as an inflating gas enters the airbag cushion  22 , the airbag cushion  22  bursts through an outer skin or cover of the airbag module  20  and inflates between the occupant  12  of the vehicle and the steering wheel, dashboard, or other structural member of the vehicle. For instance, the airbag cushion  22  may emerge from below the outer covering of the steering wheel, through a cutaway in a trim panel, from behind a trim panel, from a seam between two panels or coverings, etc. According to various embodiments, the airbag module  20  may be configured within a glove box assembly or in other locations within the vehicle, such as beneath trim panels along the roof rail, trim panels along the vertical pillars (e.g., the A-pillar, B-pillar, and C-pillar), with the seat assembly, etc. The airbag module  20  is flexibly configurable for use in varying package requirements, and may be tailored to satisfy specific needs of the vehicle manufacturer. 
         [0018]    Referring now to  FIG. 3 , the airbag cushion  22  is shown in more detail. The airbag cushion  22  may be formed of a fabric, such as a woven or non-woven textile (e.g., nylon). The airbag cushion  22  includes a first panel  32  and a second panel  34 . The cushion  22  is formed by overlapping the first panel  32  onto the second panel  34  and sewing the periphery of the panels  32  and  34  together, forming an outer seam  35 . An interior chamber is formed between the panels  32  and  34  by the seam  35 . An aperture formed in the first panel  32 , allows inflation gas to enter the interior chamber from the inflator  24 . The airbag cushion  22  may be coupled to the inflator  24  and/or the housing  26 , such as with bolts passing through the first panel  32  around the periphery of the aperture. One or more vent holes may be formed on the upper portion of the airbag cushion  22  to discharge gas from inside the airbag cushion  22 . 
         [0019]    The tether  30  extends generally between the first panel  32  and the second panel  34 . The tether  30  may be formed of a similar fabric as the cushion  22 . According to an exemplary embodiment, airbag module  20  includes a pair of tethers  30  of equal length, each of which includes a first end portion  42  that is coupled to the first panel  32  and a second end portion  44  that is coupled to the second panel  34 . The tethers  30  have a length that is less than the untethered depth of the airbag cushion  22 . The tethers  30  therefore reduce the depth of the cushion  22  when inflated, reducing the ingress of the cushion  22  into the space occupied by the occupant  12 . 
         [0020]    The first end portion  42  may be coupled directly to the first panel  32 , or may be secured to the inflator retainer. For example, the first end portion  42  may include one or more openings for the same bolts that secure the first panel to the retainer. In addition, the first end portion  42  may be connected directly to the first panel by a seam, for example. 
         [0021]    According to an exemplary embodiment, the airbag cushion  22 , further includes a reinforcement layer  38  coupled together with the second end  44  of the tether  30  and the second panel  34  of the airbag cushion  22  (e.g., sandwiched between the second panel  34  and the second end portion  44 ). The reinforcement layer  38  may be formed of a similar fabric as the cushion  22 . The reinforcement layer  38  is smaller than the second panel  34 . The reinforcement layer  38  is configured to reinforce the second panel  34 , to reduce deformation of the expanding airbag cushion  22  caused by the high pressure of the gas injected by the inflator  24 , thereby improving the deployment of the airbag module  20 . 
         [0022]    Referring now to  FIGS. 4-6 , the second end portion  44  of the tether  30  is shown coupled to the second panel  34  with a sewn seam  50 . As shown, the second end portion  44  may have a width that is larger than the width of the main body  45  of the tether  30  that extends between the first end portion  42  and the second end portion  44 . According to an exemplary embodiment, the sewn seam  50  is formed by two parallel stitches  52 . The seam  50  passes through the second panel  34 , the reinforcement panel  38 , and the second end portion  44 . 
         [0023]    The seam  50  is an elongated along an axis  54  (e.g., a vertical axis). As shown in  FIG. 4 , when the cushion is inflated the elongated axis  54  of the seams  50  extend in the vertical direction of the vehicle and inflated airbag. Preferably, the direction of the axis  54  is parallel to the axis of the spine occupant as shown in  FIG. 2 . When the airbag cushion  22  is inflated, the tether  30  applies a force pulling on the second panel  34  that opposes an outward pressure applied to the second panel  34  by the inflation gasses. The elongated shape of the seam  50  improves the stress distribution in the second panel  34 , reducing stress concentrations that may cause the second panel  34  to rupture during inflation of the cushion  22 . In one embodiment, the seam  50  is elongated such that it includes a pair of curved ends  56  that are joined by a pair of parallel sides  58 . In other embodiments, the seam  50  may be elongated and otherwise shaped, such as an ellipsoid shape, oval or other closed curve. The seam  50  is preferably symmetrical about its elongated axis in order to reduce the stress concentrations on the seam. Such preferential symmetrical shapes include substantially oval an ellipsoid shapes. 
         [0024]    According to an exemplary embodiment, the reinforcing panel  38  is integrally formed with the tether  50  as an extended portion of the second end portion  44 . As shown in  FIG. 5 , the second end portion  44  is folded over on itself. In other embodiments, the reinforcing panel  38  may be formed as a separate panel that is aligned with the second end portion  44  and coupled to the second end portion  44  and the second panel  34  with the seam  50 . 
         [0025]    The elongated shape of the seam  50  allows the second end portion  44  to be smaller compared to the end portion of the tether configured to be coupled to the second panel  34  with a circular seam. Additionally, the elongated seam  50  and the relatively narrow second end portion  44  of the tether  30  allows for a more efficient packaging of the cushion  22  in an uninflated state (e.g., inside the housing  26 ). 
         [0026]    In other embodiments, the airbag module  20  may have a single tether  30  or more than two tethers  30 . The shape and position of the tether  30 , as shown in  FIGS. 2 and 3 , is exemplary only. In other embodiments, the elongated shaped seam  50  may be advantageously utilized to couple tethers of other configurations to the airbag cushion  22 . The elongated seam  50  may be utilized for airbag modules having dual stage inflators or single stage inflators. 
         [0027]    For purposes of this disclosure, the term “coupled” means the joining of two components (electrical or mechanical) directly or indirectly to one another. Such joining may be stationary in nature or movable in nature. Such joining may be achieved with the two components (electrical or mechanical) and any additional intermediate members being integrally formed as a single unitary body with one another or with interaction the two components or the two components and any additional member being attached to one another. Such joining may be permanent in nature or alternatively may be removable or releasable in nature. 
         [0028]    It is important to note that the construction and arrangement of the airbag module 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 disclosure 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. Accordingly, all such modifications are intended to be included within the scope of the present application. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. Other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the exemplary embodiments.