Abstract:
A dual stage fastener for securing a vehicle interior trim component to a vehicle body component to cover an air curtain during storage. The fastener includes a pin tethered to a grommet. During deployment of the air curtain, the pin disengages from the grommet and the tether restrains the pin and the associated trim component to reduce the length of travel of the trim component within the passenger compartment of the vehicle.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a dual stage fastener for securing a vehicle interior trim component to a vehicle body component to cover a stored air curtain and more particularly to a fastener including a pin and a grommet wherein the pin is tethered to the grommet to secure the trim component to the body component when the air curtain is deployed to limit the travel length of the trim component within the vehicle passenger compartment. 
     BACKGROUND OF THE INVENTION 
     Most passenger vehicle are equipped with one or more air bag or air curtain modules located at selected areas of the vehicle passenger compartment, for example, in the steering wheel housing in front of the driver of the vehicle. Air curtains are typically housed in a recess formed in a vehicle body component, such as the steering wheel housing or a fixed structural member of the vehicle. A detachable trim component, such as a cover or panel, covers the opening of the recess to hide the folded air curtain from view. Upon certain vehicle impact conditions, the air curtain is deployed from a folded condition behind the trim component to an unfolded and expanded condition out from the recess to help cushion and immobilize an occupant of the vehicle to reduce injury thereto. Expansion of the air curtain during deployment forces the trim component, such as a cover or panel, to be detached from the vehicle component permitting the air curtain to expand outwardly from the recess. 
     Various fasteners have been used to secure the trim component to the vehicle component. Air curtain covers and associated trim components used in a vehicle present a unique fastening challenge due to the large forces exerted on such components within a short period of time when the air curtain is deployed. It is desirable to limit the length of travel and direction of travel of the air curtain trim component. Some prior art structures have used a tether fastened to the cover itself as is disclosed in U.S. Patent No.  5 , 651 , 562 . The direction the air curtain cover is propelled cannot be adequately controlled where the cover is tethered, however. 
     SUMMARY OF THE INVENTION 
     The above, as well as other objects of the invention, may be readily achieved by a fastener for fastening a vehicle interior trim component to an associated vehicle component comprising: a grommet adapted to be attached to the vehicle component, the grommet having an aperture formed therein; and a pin tethered to the grommet, the pin adapted to be attached to the trim component and releasably inserted through the aperture formed in the grommet to releasably secure the trim component to an associated vehicle component. 
     Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an elevational side view of a dual stage fastener with the head of the grommet in section incorporating the features of the invention and shown disassembled; 
     FIG. 2 is a top plan view of the dual stage fastener illustrated in FIG. 1; 
     FIG. 3 is an elevational side sectional view of the dual stage fastener illustrated in FIGS. 1 and 2 showing the dual stage fastener unassembled and the trim component and the vehicle component attached to the dual stage fastener; and 
     FIG. 4 is an elevational side view of the dual stage fastener illustrated in FIGS. 1 and 2 showing the dual stage fastener assembled and the trim component and the vehicle component attached to the dual stage fastener. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings, and particularly FIG. 1, there is shown generally at  10  a dual stage fastener incorporating the features of the invention. The dual stage fastener  10  generally includes a hollow grommet  12  and a pin  14  which are connected together by a strap or tether  42 . 
     The grommet  12  includes a hollow cylindrical shaft  16  having a plurality of axially aligned slits  17  formed therein. A substantially radially outwardly extending annular head  18  is disposed at one end of the shaft  16 . The head  18  is dish shaped with an outer peripheral edge and two oppositely facing surfaces. The first surface  20  of the head  18  is preferably flat to permit the head  18  be placed against a vehicle component or part  22 , as clearly illustrated in FIGS. 3 and 4. The second surface of the head  18  has a centrally disposed flat portion  24  and a beveled portion  26  disposed radially outwardly of the flat portion  24 . Resilient detents  28  are disposed to extend radially outward of the outer wall of the shaft  16 . The detents  28  are spaced apart from the first surface  20  of the head  18  to permit the vehicle component  22  to be interposed between the first surface  20  and the detents  28 . 
     The pin  14  includes a cylindrical shaft  30  which terminates in a beveled end  32 . Adjacent the beveled end  32 , the shaft  30  has an enlarged portion  34 . A plurality of raised pads  35  are disposed on an axially central portion of the shaft  30 . A radially outwardly extending annular head  36  is disposed at the distal end of the pin  14 . A second outwardly extending annular flange  38  is disposed in adjacent spaced relation to the annular head  36 . Ribs  40  are disposed on the side of the flange  38  opposite the head  36 . 
     A flexible tether  42  joins the flange  38  of the pin  14  with the head  18  of the grommet  12 . The grommet  12 , the pin  14 , and the tether  42  can be made of any suitable material, such as plastic. Preferably, the grommet  12 , the pin  14 , and the tether  42  are formed as one integral part, for example, by an injection molding process. By forming the fastener into one part, manufacturing and assembly costs are reduced, compared to securing a separate tether to separate fastening structures. 
     As illustrated in FIGS. 3 and 4, the dual stage fastener  10  may function to releasably fasten a cover or trim component  44  to the vehicle component  22  to cover an air curtain  50  in a stored and folded position in a vehicle passenger compartment, for example. The trim component  44  and the vehicle component  22  can be any suitable structures for covering and mounting the air curtain  50 . In use, the grommet  12  is inserted into an aperture  52  formed in the vehicle component  22 . Detents  28  are deflected inwardly during insertion of the grommet  12  and are urged outwardly to their original position once the vehicle component  22  has passed to the space between the detents  28  and the flat portion  24  of the head  18 . The detents  28  hold the grommet  12  securely within the aperture of the vehicle component  22 . 
     As the pin  14  is then inserted into the hollow portion of the grommet  12 , the enlarged portion  34  of the pin  14  causes the slits  17  of the shaft  16  to separate slightly permitting the walls of the shaft  16  to be expanded. The enlarged portion  34  of the pin  14  is allowed to pass through the shaft  16  of the grommet  12 , and the walls of the shaft  16  resiliently and frictionally maintain the pin  14  in place within the grommet  12 . The pads  35  cooperate with the walls of the shaft  16  to allow the pin  14  to be releasably held in place. The pin  14  is releasably held in the grommet  12  until deployment of the air curtain. Of course, the pin  14  could be releasably held in the grommet  12  by any suitable manner. 
     When the air curtain is deployed and expands, the pin  14  is caused to be released from the grommet  12 , as shown in FIG.  3 . The tether  42 , cooperating with the securely held grommet  12 , prevents the trim component  44  from becoming a projectile within the vehicle passenger compartment. Thus, the tether  42  limits the amount of travel of the trim component  44  within the vehicle passenger compartment of the vehicle. The direction the trim component  44  when propelled upon deployment of the air curtain can be controlled through strategic placement of the dual stage fasteners  10 . 
     Installation and assembly of the dual stage fastener  10  is simplified over prior art fasteners. The number of steps is reduced for an assembly worker since the dual stage fastener  10  is preferably a single integral piece, requiring only one step to procure the dual stage fastener  10 . Two piece fasteners require a worker to procure two pieces, thereby requiring two steps. If desired, the dual stage fastener  10  can be pre-attached to the trim component  44 . The grommet  12  can then be inserted into an aperture formed in the vehicle component  22  and the pin  14  inserted into the hollow portion of the grommet  12  to accomplish installation of the trim component  44 , thereby providing for simple installation of the trim component  44 . 
     Although the dual stage fastener  10  is shown and described as the grommet  12  being secured to the vehicle component  22  and the pin  14  being secured to the trim component  44 , alternatively, the grommet  12  can be installed in the trim component  44  and the pin  14  can be installed in the vehicle component  22  to accomplish the same objective. 
     It should be understood that the grommet  12  and the pin  14  can have any suitable cooperating shapes and structures, other than the illustrated embodiment, for fastening the trim component  44  to the vehicle component  22 . 
     The principle and mode of operation of this invention have been explained and illustrated in its preferred embodiment. However, it must be understood that this invention may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope.