Abstract:
A cradle receiving an airbag module is formed to slide within an instrument trim panel without the need for separate fasteners or installation steps. In a preferred embodiment, the cradle was formed of a rigid foam material and in a most preferred embodiment it was formed of expanded polypropylene to enclose the airbag module on all sides except the front activation surface of the airbag for deployment.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to a mounting system for a vehicle airbag module and particularly to an airbag module for mounting in the instrument panel or doors.  
           [0002]    Instrument panel mounted airbags for use on the passenger side of a vehicle are typically secured to the instrument trim panel by means of metal or plastic brackets. Three brackets are usually required, one extending across the top of the airbag module and two PAB (passenger airbag brackets) below the airbag module. Thus, three brackets with multiple fasteners are employed. As a result, the installation of the airbag module in a vehicle is somewhat labor intensive. With the additional cost of the brackets and fasteners, such installations can be relatively expensive. Further, the brackets and fasteners add undesirable weight to the vehicle. With open spaced-apart brackets mounting the airbag module, upon impact and deployment of the airbag, the airbag may have a tendency to deploy somewhat into the instrument panel area as opposed to outwardly into the passenger space. As a result, the spaced bracket mounting system may not be ideal for the mounting of airbags in an instrument panel or in other areas of a vehicle, such as the doors for side impact airbags. Also, the mounting system must be designed to absorb head impacts in situations where the airbag is not deployed.  
           [0003]    Accordingly, there exists a need for a less expensive, lighter weight airbag module mounting system which is less labor intensive for installation.  
         SUMMARY OF THE INVENTION  
         [0004]    The mounting system of the present invention satisfies this need by providing a cradle surrounding the airbag module which is preformed to slide within an instrument panel interlocking the combined airbag module and cradle to the instrument panel without the need for separate fasteners or installation steps. In a preferred embodiment of the invention, the cradle was formed of a foam polymeric material and in a most preferred embodiment of the invention it was formed of expanded polypropylene to enclose the airbag module on all sides, thereby leaving only the front activation surface of the airbag exposed for deployment upon impact. In some embodiments of the invention, the airbag module can be integrated with the foam polymeric cradle and sold as a single unit to the OEM manufacture for installation in a vehicle. In all embodiments, the cradle is shaped to receive an airbag module in close contact surrounding five of the sides thereof and includes mounting structure which interengages the instrument trim panel to mount the cradle to the trim panel and receive the airbag module within the cradle. With such a system, therefore, the mounting of an airbag, for example, in an instrument panel or a door panel of a vehicle is facilitated, and the airbag module is substantially continuously enclosed on all sides except the operational front deployment side. The cradle is made of an energy absorbing foam polymeric material to also absorb head impacts in the event the airbag does not deploy. Such a structure thereby enhances the performance of the airbag module while reducing the cost of installation, the weight of the vehicle, and results in an overall reduction of cost of the vehicle.  
           [0005]    These and other features, objects and advantages of the present invention will become apparent upon reading the following description thereof together with reference to the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]    [0006]FIG. 1 is an exploded fragmentary perspective view of a vehicle instrument trim panel showing an airbag module and mounting cradle of the present invention;  
         [0007]    [0007]FIG. 2 is an exploded perspective view of the airbag module and mounting cradle of the present invention; and  
         [0008]    [0008]FIG. 3 is a fragmentary perspective view of the trim panel. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0009]    Referring initially to FIGS. 1 and 3, there is shown an instrument trim panel  10  for a vehicle. The right or passenger side of the trim panel  10  is shown, which is made of a suitable polymeric material such as polypropylene, polycarbonate, or other conventional polymeric materials employed for instrument trim panels. Trim panel  10  is mounted to the sheet metal firewall of the vehicle during manufacture of the vehicle and is configured to include openings such as opening  12  for a glove compartment and openings, such as  14 , for HVAC ducts and outlets. In the upper section of the instrument trim panel  10  on the passenger side, there is a generally rectangular opening  16  for receiving a passenger side airbag module  20 , which is a generally rectangular commercially available unit.  
         [0010]    In the preferred embodiment of the invention, the opening  16  defines a socket for receiving a cradle  30  into which the airbag module  20  is mounted with the socket  16  including sidewalls  17  and  19  on opposite sides of the generally rectangular opening  16  (FIG. 3). The instrument trim panel  10  also integrally includes PAB door supports  18  for the cradle  30 , thus supporting the cradle on opposite sides and the bottom. Cradle  30 , with the nested airbag module as described below, is installed by sliding the structure into the socket  16  of instrument panel  10  during manufacture. Once installed, interlocking members  35 ,  36  of the cradle  30 , as described below, engage slots  17 ′ and  19 ′ in flexible sidewalls  17  and  19  of the instrument trim panel  10 , and the cradle  30  can be attached to panel  10  without the use of fasteners. A PAB door  40  of suitable material, such as vinyl, includes mounting tabs  42  at various spaced locations and encloses the passenger facing front side of the instrument trim panel  10  using suitable fasteners (not shown). The panel  40  includes a conventional breakaway area aligned with airbag module  20  to allow the airbag to deploy into the passenger compartment while holding the module  20  within cradle  30 .  
         [0011]    As seen in FIG. 2, the cradle  30  comprises, in one embodiment, an upper piece  32  and a lower piece  34  joined along opposed facing joining surfaces  31  and  33 . The opposite edges of upper and lower cradle pieces or sections  32  and  34  include interlocking members  35  and  36  on opposite sides which are configured to snap-fit within the mounting socket  16  by deflecting sidewalls  17  and  19  (FIG. 3), compressing the foam cradle  30  to interlock cradle  30  within apertures  17 ′ and  19 ′ of socket  16 . For any given vehicle, the exact configuration of socket  16  and cradle  30  will vary. As seen in FIG. 2, the left side of cradle  30  may be a generally longitudinal rectangular vertically extending member  35 , while right side members  36  are shorter rectangular blocks extending horizontally outwardly. Cradle pieces  32  and  34  are integrally molded of a suitable open or closed-cell foam material and preferably expanded polypropylene to provide an impact absorbing cradle which, as seen in the figures, defines sidewalls  37 , a floor  38 , top  41 , and back wall  39  which closely surrounds the sides  22  and  24  as well as the top  25 , bottom  27 , and rear wall  29  of airbag module  20 . The facing surfaces  31 ,  33  of cradle pieces  32  and  34  are configured with projections  43  and mating recesses  44  to interlock with one another. Depending upon the specific design of the vehicle and its instrument trim panel  10 , the configuration of the outer contours of the cradle  30  will vary in order to conform to and interlock with the instrument panel  10 .  
         [0012]    In a preferred embodiment, cradle  30  was made of two pieces joined together at contiguous surfaces  31  and  33  on opposite sides of airbag module  20 , although in other embodiments the cradle may be of unitary construction. In all embodiments, the cradle will surround the top, bottom, and sides and preferably the rear of the airbag module  20  in order to effectively hold the airbag module in position and allow the snap-fitting of the cradle  30 , by the interlocking brackets, into the instrument trim panel  10  without the need for threaded fasteners or the like. The system of the present invention contemplates either the mounting of the airbag module  20  to the cradle  30  during the manufacture of the airbag module  20 , such that the airbag module and cradle can be sold as a unit, or subsequently separately assembled during the manufacture of the vehicle.  
         [0013]    The cradle sections  32  and  34  define a central, generally rectangular opening  45  (FIG. 2) which will vary in shape depending upon a particular airbag module employed. Thus, the central opening  45  formed in the cradle can also vary depending upon the shape and configuration of an airbag module  20 . The airbag module may also be adhesively secured to the contacting surfaces of cradle sections  32  and  34  to adhere the contacting surfaces of the airbag module to the surrounding cradle. In some embodiments of the invention, it may be possible to mold the cradle directly to the airbag module. Although panel  10  is an instrument trim panel, similar panels are employed in vehicle doors and, thus, panel  10  could be a vehicle door panel which receives cradle  30  and airbag module  20  for side impact airbag installations.  
         [0014]    It will become apparent to those skilled in the art that these and various other modifications to the preferred embodiment of the invention as described herein can be made without departing from the spirit or scope of the invention as defined by the appended claims.