Abstract:
An airbag module includes a retainer, diffuser, inflatable airbag, and an inflator to inflate the airbag. The diffuser is configured to disperse inflation gas from the inflator into the inflatable airbag. The retainer and/or diffuser comprise a glass-filled polymer material. The retainer includes a projection extending from a base wall. The projection couples to a hole in the diffuser flange and prevents the diffuser from rotating relative to the retainer. The inflator is coupled to the retainer by trapping an inflator flange under an overhang in a retainer cavity.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
     This application claims priority to U.S. Provisional Application No. 60/929,349, filed Jun. 22, 2007, which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     The present disclosure relates generally to the field of airbags. More specifically, the disclosure relates to a diffuser and a retainer for a steering wheel airbag module that are formed from a glass-polymer composite. The retainer and diffuser are configured to be coupled together without additional fastening members. 
     It is known to provide inflatable airbags in a vehicle. Inflatable airbags are inflated by gas directed into the airbag in response to a vehicle experiencing a sudden deceleration above a predetermined threshold or in response to other factors. The inflated airbag absorbs energy resulting from the movement of an occupant within the vehicle compartment against the airbag. The energy absorbed by the airbag is dissipated to minimize rebounding of the occupant from the airbag. Airbags 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. The steering wheel airbag assembly generally includes an inflator, an airbag that is inflated by the inflator, a diffuser, and a retainer that mechanically couples the airbag assembly to the vehicle, such as with threaded studs. 
     Referring to  FIG. 2 , a steering wheel airbag assembly  120  is shown according to prior art. Airbag assembly  120  includes an inflator  122 , a diffuser  150 , a retainer  130 , and an airbag  160  (sometimes referred to as a “cushion”). Inflator  122  generates a gas that rapidly inflates airbag  160  in an impact. As the gas enters airbag  160 , airbag  160  bursts through outer skin  16  and inflates between the driver  18  of vehicle  10  and steering wheel  12 . Diffuser  150  is provided between inflator  122  and airbag  160 . Diffuser  150  is a thin-walled metallic member that includes a multitude of slots or openings  158  and mounting studs  155 . Openings  158  are configured to allow the gas produced by inflator  122  to expand into airbag  160 . Mounting studs  155  are received by openings in retainer  130  and openings in inflator  122 . The edges of airbag  160  are trapped between diffuser  150  and retainer  130 . Nuts  174  are threaded onto studs  155  to couple retainer  130  to inflator  122 , airbag  160 , and diffuser  150 . However, the bolted connection requires nuts  174 , increasing the number of components in the assembly and the time needed to assemble airbag module  120 . 
     It would be desirable to provide an airbag assembly that is less expensive and easier to assemble. 
     SUMMARY 
     One embodiment provides an airbag module. The airbag module comprises a retainer comprising a glass-filled polymer material, a diffuser coupled to the retainer and comprising a glass-filled polymer material, an inflatable airbag, and an inflator to inflate the airbag. The diffuser is configured to disperse inflation gas from the inflator into the inflatable airbag. 
     According to yet another embodiment, an airbag module is provided. The airbag module comprises a retainer, a diffuser with at least one flange, an inflatable airbag, and an inflator to inflate the airbag. The diffuser is configured to disperse inflation gas from the inflator into the inflatable airbag. The retainer includes at least one projection extending from a base wall. The at least one projection is configured to couple to a hole in the at least one flange of the diffuser and is configured to prevent the diffuser from rotating relative to the retainer. The inflator is configured to be coupled to the retainer by trapping at least one inflator flange under an overhang in at least one retainer cavity. The at least one retainer cavity being positioned about a periphery of a central opening of the retainer. 
     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 and the accompanying exemplary embodiments shown in the drawings, which are briefly described below. 
         FIG. 1  is a side view of a vehicle interior including an airbag assembly according to an exemplary embodiment. 
         FIG. 2  is a cross section of an airbag assembly according to prior art. 
         FIG. 3  is an isometric view of a portion of an airbag assembly according to an exemplary embodiment. 
         FIG. 4  is an exploded front view of the airbag assembly of  FIG. 3 . 
         FIG. 5  is an exploded rear view of the airbag assembly of  FIG. 3 . 
         FIG. 6  is an isometric view of a portion of the airbag assembly of  FIG. 3  showing the diffuser coupled to the retainer according to one exemplary embodiment. 
         FIG. 7  is an isometric view of a portion of the airbag assembly of  FIG. 3  showing the inflator before being coupled to the retainer according to one exemplary embodiment. 
         FIG. 8  is an isometric view of a portion of the airbag assembly of  FIG. 3  showing the inflator coupled to the retainer according to one exemplary embodiment. 
         FIG. 9  is a cross section of the airbag assembly of  FIG. 8  taken along line  9 - 9 . 
     
    
    
     DETAILED DESCRIPTION 
     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 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. 
     Referring to  FIG. 1 , a vehicle  10  is shown according to an exemplary embodiment. Vehicle  10  includes one or more seats that are configured to receive an occupant  18  and are coupled to vehicle  10 . Airbags may be provided at a variety of places within vehicle  10  to protect an occupant  18  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. A steering wheel airbag assembly  20  is coupled to the steering column  14  and is configured to deploy through the outer skin or cover  16  (see  FIG. 2 ) of the center of the steering wheel  12 . 
     Referring in general to  FIGS. 3-9 , a portion of a steering wheel airbag module or assembly  20  is shown according to an exemplary embodiment. Airbag module  20  includes an inflator  22 , a retainer  30 , a diffuser  50 , and an airbag or cushion  60  (shown in  FIG. 9 ). Airbag module  20  does not require threaded studs and nuts or other separate components to couple it together. The steering wheel airbag assembly  20  may further include a retaining ring to couple the airbag  60  to the retainer  30 . 
     Inflator  22  may be similar to inflator  122  of  FIG. 2  and is a generally cylindrical body that includes outwardly extending flanges  24 . According to an exemplary embodiment, inflator  22  includes four flanges  24  that are spaced symmetrically about the periphery of inflator  22 . Alternatively, the inflator  22  can have a single rectangular flange, or any other number, size, or shape of flanges. Inflator  22  also includes plugs  28  on the back that are configured to be coupled to a sensor (not shown) that activates airbag module  20 . 
     Diffuser  50  includes a domed portion  52 , and outwardly extending flanges  54 . According to one exemplary embodiment, diffuser  50  is formed from a reinforced polymer. Diffuser  50  is configured to nest with inflator  22 . Diffuser  50  includes a multitude of vents or openings  56  formed in domed portion  52 . According to various exemplary embodiments, the openings  56  may be larger or smaller and more or fewer openings  56  may be provided in diffuser  50 . Diffuser  50  may include ribs or other strengthening features. The manufacturing costs of manufacturing composite diffuser  50  can be less than the manufacturing of metal diffuser  150  of  FIG. 2 . 
     Retainer  30  is a generally annular body that is configured to receive diffuser  50  and inflator  22  and to couple airbag module  20  to steering column  14 . Retainer  30  couples airbag module  20  to steering column  14 . According to an exemplary embodiment, retainer  30  includes two clips or latches  32  extending from a base wall  36 . Clips  32  include enlarged or barbed heads  34  that are received by receiving sockets (not shown) provided on steering column  14 , steering wheel  12 , and/or cover  16 . The receiving sockets may be, for example, spring-loaded. According to other exemplary embodiments, retainer  30  may include three or more clips  32 . While the two clips  32  are shown generally on opposite sides of a central opening  38 , according to other exemplary embodiments, they may be otherwise arranged. The clips  32  can snap into the receiving sockets on the steering column  14 , steering wheel  12 , and/or cover  16 . Alternatively, the retainer  30  can couple to the steering column  14 , steering wheel  12 , and/or cover  16  by any suitable mechanism, such as by rivets, screws, glue, etc. 
     Central opening  38  in base wall  36  receives diffuser  50  and inflator  22 . A multitude of posts  46  (e.g., studs, protrusions, projections, etc.) extend away from base wall  36  to provide locating features for diffuser  50 . Slots or cavities  42  are provided symmetrically about the periphery of central opening  38  and are configured to receive inflator  22 . Cavities  42  are defined by overhangs  40  (e.g., walls, flanges, ledges, etc.) integrally formed with the main body of retainer  30 . The overhangs  40  may include a wall or stop  44  opposite of the open end. 
     To assemble airbag module  20 , domed portion  52  of diffuser  50  is inserted into central opening  38  of retainer  30 , as shown in  FIG. 6 . Diffuser  50  is positioned so posts  46  are aligned with holes  58  in flanges  54 . Holes  58  receive posts  46  to position diffuser  50  relative to retainer  30  and prevent diffuser  50  from rotating relative to retainer  30  when airbag module  20  is assembled. According to other exemplary embodiments, posts  46  may not be included and diffuser  50  may be located and retained by other features (e.g., flange geometry, bosses, ledges, etc.). The ends  62  of airbag cushion  60  are trapped between diffuser  50  and retainer  30  ( FIG. 9 ). 
     After diffuser  50  is seated in retainer  30 , inflator  22  is nested within diffuser  50 , with flanges  24  of inflator  22  generally aligned with flanges  54  of diffuser  50  as shown in  FIG. 7 . Inflator  22  is rotated to slide flanges  24  into cavities  42  as shown in  FIG. 8 . Stops  44  prevent inflator  22  from being over-rotated and help to retain flanges  24  in cavities  42 . Inflator  22  is coupled to retainer  30  by flanges  24  trapped under overhangs  40 . Diffuser  50  is, in turn, trapped between inflator  22  and retainer  30 . In this way, airbag module  20  does not need threaded studs or other separate mechanical fasteners. Airbag module  20  of  FIG. 3  can be assembled more quickly and includes fewer components compared to traditional airbag modules (such as module  120  of  FIG. 2 ), reducing assembly costs. 
     According to one exemplary embodiment, retainer  30  and diffuser  50  are formed from a glass-filled polymer composite, or any other suitable polymer. Glass fibers are introduced into the plastic during an injection molding process. In one embodiment, the glass filled plastic material may be, for example, nylon. One exemplary nylon material is commercially available under the name Zytel™ by DuPont. According to other exemplary embodiments, the polymer may be any other suitable type of plastic material. 
     In one embodiment, the plastic material comprises a range of 10% to 70% glass. In a preferred embodiment, the plastic material comprises a range of 10% to 60% glass. Alternatively, the plastic material comprises a range of 10% to 50% glass. In a particularly preferred embodiment, the glass filled plastic material comprises 40% glass. For example, the material may be 40% glass reinforced nylon PA 6. In yet another embodiment, the plastic material comprises a range of 10% or higher of glass. In yet another embodiment, the plastic material comprises a range of 10% to 30% glass. According to still other exemplary embodiments, retainer  30  and diffuser  50  may be formed from another comparable composite material. It will be recognized that the diffuser  50  and retainer  30  need not comprise the same material. The diffuser  50  and retainer  30  may contain a glass filled polymer with different compositions of glass, or different polymers, or non-plastic materials. 
     Alternatively, retainer  30  and diffuser  50  may comprise a non plastic material, such as an aluminum alloy or magnesium alloy. The aluminum or magnesium alloys may be die cast to form retainer  30  and diffuser  50 . In yet another embodiment, retainer  30  and diffuser  50  may be formed by a stamping process. 
     Conventionally, plastic was not considered to be a useful material for diffuser  50 . Generally, a plastic diffuser was not used because the plastic was considered to be likely to fracture due to the hot inflation gases. However, diffuser  50  does not fracture and is able to withstand the hot inflation gases from the inflator. 
     Diffuser  50  formed from the composite is lighter than the comparable metal diffuser  150  of  FIG. 2 . Additionally, according to some embodiments, by using retainer  30  and diffuser  50  described above, no nut or fastener is needed to attach diffuser  50  to retainer  30 . 
     Yet another advantage of diffuser  50  is that adjustments may be made to diffuser  50  and/or retainer  30  quickly, efficiently, and inexpensively by making only slight adjustments to the tooling process. For example, the size, position, and type of diffuser openings  56  and/or shape of retainer  30  can be changed easily, quickly, and inexpensively depending on the desired inflation results. Conventionally, changing the design of a metal diffuser was costly and time consuming. 
     The construction and arrangement of the elements of the airbag assembly as shown in the preferred and other exemplary embodiments is illustrative only. Although only a few embodiments of the present airbag assembly 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, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter recited in this disclosure. 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 preferred and other exemplary embodiments without departing from the spirit of the present application.