Abstract:
A fastening device for securing a panel to a frame is adapted to shear at a predetermined load to free the panel. A stud and an “S”-shaped receptacle cooperate to provide a predetermined breakpoint.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims the benefit of U.S. Provisional Application No. 60/167,775, filed Nov. 29, 1999. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates to the field of fastening devices, and particularly, to a fastening device which is utilized in the form of a stud and receptacle.  
           [0004]    2. Description of the Related Art  
           [0005]    Many types of fastening devices have been used for releasably securing one or more panels to a frame, or one panel to another. It is known to provide studs, such as, for example, quarter-turn fasteners which are received in a variety of associated receptacles. Some studs are provided to spread the receptacle to provide positive engagement against withdrawal of the stud and receptacle in order to retain a panel or other attaching member.  
           [0006]    A need exists for a fastening member which can be readily installed to hold a panel onto a frame or other member, and which has the ability to succumb to predetermined force loads so that the fastener can destruct, thereby permitting the panel to become free.  
           [0007]    It is particularly useful in the automotive industry to have members which can become disassociated and/or detached from other members upon the impact such as a crash. For example, where snow and ice are prevalent, often, noise panels, which are installed underneath the carriage of an automobile, can become jarred by their contact with snow and/or ice or other objects. Instead of having the panel damaged or ripped, it is more desirable that the panel fastening members, such as a fastening stud, release and then permit the panel to become detached as a whole rather than as a fragmented collection of pieces. This promotes reuse of the panel and minimizes further damage to the surfaces involved. Furthermore, it is useful if the receptacle can be reused, if it itself is not damaged.  
           [0008]    Furthermore, often noise panels are attached to other members, such as the bumper of a car, headlamps, fog lamps, grilles and other vehicle components, which are costly to replace, in the event that they would come off with the panel. Therefore, it is preferable to provide a means for fastening such a panel to a vehicle which will release itself from the vehicle, and the other vehicle components to which it is attached, while minimizing damage to further parts of the vehicle.  
         SUMMARY OF THE INVENTION  
         [0009]    The present invention provides a fastening device comprising a receptacle and a stud fastening member for use in connection therewith. The fastening device of the present invention is designed for high intermittent loads and has predetermined forced specifications for maintaining a static load and has a threshold peak working load. For example, the fastening device may operate under a steady state load of 50 Newtons (N) and may have a peak working load of 800 N. The fastening device preferably includes a receptacle and a stud. After exceeding the peak working load, the stud will shear, and therefore permit release of the panel or member which it is attaching.  
           [0010]    Preferably, the stud is made of a plastic and is composed to provide shearing at the desired operative peak or threshold load force. The plastic preferably, is a corrosion-resistant material which improves the durability of the fastening members.  
           [0011]    A clip-on type receptacle is preferably provided for use with the fastening stud member. Preferably, a wave-shaped configuration provides an interaction zone with a maximum load bearing area between the stud and receptacle surfaces. Preferably, the stud is configured with enlarged radial end portions to facilitate distribution of force loads so that stress concentrations at the lugs of the stud can be reduced. The receptacle and stud, together, cooperate to provide a predetermined breakpoint for predictable shear failure at predetermined operating/stress loads.  
           [0012]    The stud preferably has an enlarged end configuration with a wave shaped interaction zone. The receptacle is provided with a compatibly associated wave-shaped interaction zone to permit retention of the stud when the stud is turned, such as, a quarter-turn, to fasten the stud with the receptacle. Preferably, the receptacle is a clip-on type and can be clipped to the edge of a panel or frame. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    [0013]FIG. 1 is a perspective view of the fastening device according to a first embodiment of the present invention.  
         [0014]    [0014]FIG. 2 is a perspective view of the stud according to a first embodiment of the present invention.  
         [0015]    [0015]FIG. 3 is a perspective view of the receptacle according to a first embodiment of the present invention.  
         [0016]    [0016]FIG. 4 is a perspective view of the fastening device according to a second embodiment of the present invention.  
         [0017]    [0017]FIG. 5 is a perspective view of the receptacle according to a second embodiment of the present invention.  
         [0018]    [0018]FIG. 6 is a perspective view of the stud according to a second embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0019]    Referring to FIGS.  1 - 3 , a first alternate embodiment of a fastening device  10  according to the present invention is shown comprising a stud  11  for use in securing a first member, such as a panel  100  to a corresponding panel or frame  200 . A receptacle  12  is provided and is shown comprising a generally s-shaped configuration with means for attaching the receptacle  12  to a frame  200 . The means for attaching the receptacle  12  to the frame  200  includes a clip  13  formed as part of the generally s-shaped receptacle configuration and having an upper clip arm  14  and a lower clip arm  15  connected by a radiused portion  16 . Preferably, the upper clip arm  14  and lower clip arm  15  are deflectable so that they can be deflected by the frame  200  when the receptacle  12  is installed thereon. For example, the upper clip arm  14  and lower clip arm  15  with the connecting radiused portion  16  can function like a leaf spring. This can also provide a preload force for the stud  11 . In addition, while not shown, the underside of the upper arm  14  and/or top side of the lower arm  15  may contain barbs or other elements which facilitate attachment and/or holding of the receptacle  12  onto the frame  200 .  
         [0020]    The stud  11  is shown with a head  16  having a slot  17  therein. The slot  17  is provided to facilitate turning the stud  11  with a tool, such as, for example a slotted screwdriver. It is conceivable that other configurations for use with other tools, including Phillips head screwdrivers, specially configured tools, can also be utilized as an alternate to the slot  17  shown and described herein. The stud  11  is shown in FIG. 2 having an end  20  with lugs  21 ,  22  thereon for retention of the stud  11  in the receptacle  12 . Specifically, the end  20  of the stud  11  is shown in FIG. 1 extending below the base  23  of the receptacle  12 . On the underside of the base  23  are projections  25 ,  26  disposed on the edge of the receptacle bore  27 . The fastening stud  11  is configured to be inserted into the bore  27  of the receptacle  12  and rotated one-quarter turn to close. Similarly the stud  11  can be released by a counter-rotation of one-quarter turn.  
         [0021]    The receptacle further has a collar  30  extending upwardly from the base  23  for facilitating retention and alignment of the stud  11 . Referring to FIG. 2, the stud  11  is shown having an upper surrounding flange  32  and lower surrounding flange  33 . Preferably, the upper surrounding flange  32  and lower surrounding flange  33  can facilitate the maintenance of the stud  11  on a panel so that the stud  11  will not become detached from the panel  100  when not connected with the receptacle  12 .  
         [0022]    [0022]FIG. 3 shows a separate view of the receptacle  12  installed on a panel  200 . The receptacle preferably has an aperture  37  disposed in the upper arm  14  and an aperture  38  disposed in the lower arm portion  15 . Preferably, the panel  200  also has an aperture  201  which is provided to align with the apertures  37 ,  38  of the receptacle  12  so that the stud  11  can pass therethrough for connection of the stud end  20  with the receptacle bore  27 .  
         [0023]    Preferably, the stud end  20  will have a wave-shaped configuration, and the retaining bore  27  will be provided with a matingly associated wave-shaped configuration. The wave-shaped configuration provides an increased load-bearing area to provide increased distribution of the force load.  
         [0024]    A second alternate embodiment of a fastening device  110  is shown in FIG. 4 comprising a stud  111  and receptacle  112 . The stud  111  has a head  116  with a slot  117  therein, which, although shown as a slot  117  can comprise alternate configurations as described above in connection with the stud  11  of the first alternate embodiment. The stud  111  includes a neck  140  and a shaft  141  which join at a collar  142 . Preferably, for example, the collar  142  can comprise the designated shearing location. Alternately, the neck  140  can be joined with the shaft  141  without the collar  142  where a shearing portion is not called for.  
         [0025]    The receptacle  112  is shown best in FIG. 5 having a bore  127  for receiving the end  120  of the stud  111  therein. The bore  127  of the receptacle  112  is shown provided with a wave-like configured wall portion  150  forming the interior surface of the bore  127 . Preferably, the stud  111  is provided with a matingly associated wave configuration at the stud end  120 . The stud end  120  is provided with lugs  121 , 122  extending outwardly from the shaft  141 .  
         [0026]    Referring to FIG. 6, the stud  111  is shown in detail, showing the lugs  121 , 122 , each being provided with a wave-like configuration. The lugs  121 ,  122  provide a wide area over which to contact the receptacle  112 . While not shown, the stud  111  can also be provided with a retainer which facilitates retaining the stud on a panel, such as that  100 , so that the stud does not detach from the panel when not installed in the receptacle.  
         [0027]    The receptacle  112  is provided with an upper clip arm  114  and a lower clip arm  115  connected by a radiused connecting portion  116 . A first aperture  137  is provided in the upper clip arm  114 , and a second aperture  138  is disposed in the lower dip arm  115 . A receiving collar  147  is provided on the receptacle  112  to facilitate connection with the stud end  120  when it is inserted therein and turned one-quarter turn. The wave-like configuration of the inner wall of the collar wall  150  facilitates the fastening of the stud  111 .  
         [0028]    A pair of wings  160 ,  161  are disposed between the lower clip arm  115  and the collar  147 . The wings  160 ,  161  for example, can provide further support for the receptacle  112  when the stud end  120  is fastened. The wings can also provide a spring arrangement for providing a preload force for the fastened stud.  
         [0029]    The wave configuration of the stud end  120  and lugs  121 ,  122  is provided to align with the receptacle inner wall  150  in a locking position upon a quarter turn after insertion of the stud end  120  into the receptacle bore  138 .  
         [0030]    The invention provides an improved fastening device with improved contact area between the stud and receptacle with minimal stress concentration. Furthermore, the lug radii  157 ,  158 , which join the lugs  121 ,  122 , respectively with the shaft  141 , are increased to reduce the stress concentrations at those locations. In addition, the receptacle dip arms  114 ,  115  can be provided with a radiused leading edge portion  169 ,  170 , respectively for facilitating attachment of the receptacle on a panel member, such as that  200 .  
         [0031]    The shear design enables the fastening device to fail in a predictable way so that the integrity of the articles fastened by the device is preserved. The receptacles  12  and  112 , preferably provide leaf spring arrangements thereby providing a preload force for the fastened stud.  
         [0032]    It is to be understood that the invention is not limited to the preferred embodiments described herein, but encompasses all embodiments within the scope of the following claims.