Abstract:
A retaining structure and fastener assembly for securing a resin panel to a vehicle body. The panel has an inner surface and a retaining structure extending outwardly from the inner surface. The retaining structure has a retaining wall with a slot for receiving a shoulder of a bolt therethrough, so that a head of the bolt is retained between the inner surface and a washer for securing the panel to the body of the vehicle. The slot is oversized relative to the shoulder of the bolt so as to define a predetermined gap therebetween to accommodate thermal expansion and contraction of the panel, thereby preventing building of the panel relative to the vehicle.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The invention relates to a fastener arrangement for coupling a resin part to a steel part. More particularly, the invention relates to a fastener arrangement for attaching a resin panel to a vehicle, which accommodates thermal expansion of the panel relative to the vehicle. 
         [0003]    2. Description of the Related Art 
         [0004]    Vehicles have panels for concealing a frame and for providing the general outer appearance of the vehicle. It is common to have vehicles with panels made from different materials and, therefore, different expansion coefficients. For example, a vehicle typically includes a resin grill positioned adjacent a metal hood or side panel. Grills, being attached to the front of the vehicle near the radiator, expand due to direct heat from the sun, secondary heat from the surrounding parts, such as the hood or the radiator. This expansion may lead to a bowing or buckling of the grill, which may, in turn, result in an unsightly gap between the grill and adjoining body panels. As a secondary effect, this expansion may also lead to formation of cracks at the attachment locations of the grille due to the increased stress/bowing/building. 
         [0005]    Thus, it remains desirable to provide a fastener that securely fastens a resin panel to a vehicle body and accommodates thermal expansion and contraction of the panel relative to the vehicle body. 
       SUMMARY OF THE INVENTION 
       [0006]    According to one aspect of the invention, a vehicle includes a body, a fastener assembly and a panel. The body has a hole for securing the fastener assembly thereto. The fastener assembly includes a bolt, a nut and a washer. The bolt has a head and a threaded portion formed at opposite ends thereof. The bolt has an annular shoulder formed adjacent the head. The bolt also has a reduced diameter portion disposed between the shoulder and the threaded portion. The nut is assembled to the threaded portion of the bolt. The washer is axially retained between the shoulder and the threaded portion of the bolt. A panel has an inner surface and a retaining structure extending outwardly from the inner surface. The retaining structure has a retaining wall with a slot for receiving the shoulder of the bolt therethrough during assembly of the panel to the body. The head of the bolt is retained between the inner surface of the panel and washer. The slot is oversized relative to the shoulder of the bolt to define a predetermined gap therebetween to accommodate thermal expansion and contraction of the panel. 
         [0007]    According to another aspect of the invention, a vehicle includes a body, a fastener assembly and a panel. The body has a hole for securing the fastener assembly thereto. The fastener assembly includes a bolt, a nut and a washer. The bolt has a head and a threaded portion formed at opposite ends thereof. The bolt has an annular shoulder formed adjacent the bead. The bolt also has a reduced diameter portion disposed between the shoulder and the threaded portion. The nut is assembled to the threaded portion of the bolt. The washer is axially retained between the shoulder and the threaded portion of the bolt. The panel has a retaining structure extending outwardly from an inner surface thereof. The retaining structure is configured to retain the head of the bolt and allow a predetermined amount of relative movement between the bolt and the panel to accommodate thermal expansion and contraction of the panel. 
         [0008]    According to another aspect of the invention, a fastener assembly is provided for coupling a panel to a wall of a vehicle, wherein the wall includes a hole for receiving the fastener assembly therethrough. The fastener assembly includes a bolt, nut and a washer. The bolt has a head and a threaded portion. The bolt has an annular shoulder adjacent the head. The shoulder has a diameter that is smaller than the hole in the wall of the vehicle. The bolt further includes a reduced diameter portion disposed between the shoulder and the threaded portion. The nut is assembled to the threaded portion of the bolt. The washer has a diameter that is larger than the hole in the wall of the body. The washer is seated on the reduced diameter portion of the nut and retained axially between the shoulder and the threaded portion of the bolt. Opposing and spaced apart first and second bearing surfaces are defined on the washer and nut, respectively, for retaining the wall of the vehicle therebetween. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    Advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawing, wherein: 
           [0010]      FIG. 1  is an exploded environmental view of a radiator grill coupled to the front end of a vehicle, according to one embodiment of the invention; 
           [0011]      FIG. 2  is an enlarged perspective view of a fastener for fastening the radiator grill to the vehicle according to the invention; and 
           [0012]      FIG. 3  is a cross sectional view of the fastener of  FIG. 2  shown in assembly with the radiator grill and the vehicle. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0013]    A fastener arrangement is provided for securing a body panel to a vehicle. The fastener arrangement is shown illustratively in  FIG. 1  fastening a body panel in the form of a radiator grill  20  to a front end  7  of the vehicle  5 , though it should be readily appreciated by those skilled in the art that the fastener arrangement may be used to fasten other types of body panels to other areas of the vehicle. The fastener arrangement securely fastens the grill  20  to the vehicle  5  and at the same time accommodates expansion of the grill  20  relative to the vehicle  5 , so as to prevent bowing or buckling of the grill  20  during expansion when exposed to heat from the sun, secondary heat from surrounding sheet metal, and/or heat emitted by the radiator. 
         [0014]    Referring to  FIGS. 2 and 3 , the fastener arrangement includes a fastener assembly  10  having a bolt  11  and a washer  50 . The bolt  11  includes a rectangular or square-shaped head  12  and an annular shoulder  14 . The shoulder  14  is disposed adjacent to the head  12 . As shown in the cross sectional view of  FIG. 3 , the diameter of the shoulder  14  is smaller than the width or length of the head  12 . The bolt  11  also includes a threaded portion  18  for threadingly engaging a nut  60 . An unthreaded reduced-diameter portion  16  is positioned between the shoulder  14  and the threaded portion  18 . The washer  50  is seated on the reduced-diameter portion  16 . The diameter of the hole on washer  50  exceeds the reduced-diameter portion  16  and is less than the diameter of the threaded portion  18 . The purpose of the reduced-diameter portion  16  is to enable the washer  50  to be axially retained between the shoulder  14  and the threaded portion  18  and thereby allow the bolt  11  and washer  50  to be combined into the fastener assembly  10  prior to sub-assembly to the grill  20  or to the body  5 . Alternatively, if a reduced-diameter portion  16  is not provided, the diameter of the hole on washer  50  will have to exceed the diameter of the threaded portion  18  which will allow the washer  50  to be separately inserted over the threaded portion  18  after sub-assembly of the bolt  11  either to the grill  20  or to the body  5 . 
         [0015]    The fastener arrangement also includes a “dog-house” or fastener retaining structure  30  formed on the grill  20 . Preferably, at least a pair of retaining structures  30  is provided on opposite sides of the grill  20 . The retaining structure  30  is adapted to secure the fastener assembly  10  to the grill  20 . More specifically, the retaining structure  30  includes a main wall  36  having an inner surface  37  that faces the vehicle  5 . A plurality of connecting walls  31 ,  32 ,  33  extends orthogonally from the inner surface  37 . The connecting walls  31 ,  32 ,  33  are arranged orthogonally relatively to each other. A retaining wall  34  is generally parallel and spaced apart from the main wall  36 . The connecting wall  32 ,  33  extends between and connect the main wall  36  and the retaining wall  34  to form an open ended box-like structure. 
         [0016]    The square or rectangular shaped bolt head  12  and the conforming shape of the orthogonal connecting walls  31 ,  32 ,  33  of the retaining structure together prevent rotation of the bolt  11 . 
         [0017]    The retaining wall  34  includes an open end  39  spaced apart and generally parallel with one of the connecting walls  32 . A slot  40  is formed along the open end  39  of the retaining wall  34 . The slot  40  extends to a middle portion of the retaining wall  34 . The slot  40  has an entrance portion defined by a pair of generally parallel side edges  41 ,  43 . The side edges  41 ,  43  of the slot  40  are spaced apart to receive the shoulder  14  of the bolt  11  therethrough. A pair of tabs  42  extends inwardly toward each other from respective side edges  41 ,  43 . The ends of the tabs  42  are spaced apart by a distance that is slightly less than the diameter of the shoulder  14 , so as to form a press fit with the bolt  11  when the shoulder  14  is inserted therethrough. In one embodiment of the invention, the tabs  42  extend at least 1 mm from the side edges  41 ,  43 . An end portion of the slot  40  is defined by a circular edge  38  that extends between the side edges  41 ,  43  and defines a circular aperture adjacent the entrance portion. The diameter of the circular aperture is wider than the distance between the side edges  41 ,  43 . 
         [0018]    In use, the fastener assembly  10  is first inserted into the fastener retaining structure  30  in the direction illustrated by the arrow in  FIG. 2 . Specifically, the bolt head  12  is aligned with the open side of the retaining structure  30 . Simultaneously, the shoulder  14  is aligned with the slot  40  and pushed past the tabs  42  to be seated within the circular aperture defined by the edge  38 . As shown in  FIG. 3 , the head  12  and shoulder  14  protrude outwardly from the inner surface  37 . The sides of the head  12  are aligned with and positioned adjacent respective connecting walls  32 , so as to prevent rotation of the bolt  11  relative to the grill  20 . The grille  20  is assembled to the vehicle by aligning the bolt axis  61  with the hole on the body  5 . As shown in  FIG. 3 , the washer  50  and retainer wall  34  are aligned parallel to the sheet metal wall  5 . The sheet metal wall  5  is retained between a first bearing surface  51  on the washer  50  and a second bearing surface  81  on the nut  60 . The thickness of the retaining wall  34  is slightly less than the distance between the head  12  and the washer  50 , so as to allow the shoulder  14  to act as a spacer and thereby enable transverse and axial movement of the grill  20  relative to the fastener  11 . By this arrangement, the grill  20  is able to thermally expand and contract without budding along the seams defined between the grill  20  and adjacent body panels. 
         [0019]    In an alternative embodiment, the head  12  and shoulder  14  of the fastener assembly  10  may be insert-molded, heat-staked, or threaded into the fastener retaining structure  30  rather than providing a slot  40  in the retaining wall  34  for inserting the bolt  11  into the structure  30 . The shoulder  14  and threaded portion  18  in this embodiment would extend through a hole formed in the retaining wall  34 . In the threaded embodiment, the shoulder  14  will be threaded to enable the bolt  11  to be installed to the retaining structure by a tapping operation. Furthermore, the shoulder  14  would be extended to replace the bolt head  12 . 
         [0020]    In another embodiment, the bolt  11  is first inserted through a hole in a sheet metal wall of the vehicle body  5 . As shown in  FIG. 3 , the sheet metal wall  5  is retained between a first bearing surface  51  on the washer  50  and a second bearing surface  81  on the nut  60 . The head  12  and shoulder  14  protrude outwardly from the sheet metal wall  5 . The grill  20  is assembled to the vehicle by aligning the retainer wall  34  against the metal wall  5  or washer  50 , and positioning the slot  40  in alignment with the shoulder  14  of the bolt. The grill  20  is pushed in a transverse direction relative to the bolt  11 , such that the shoulder  14  is pushed passed the tabs  42  and seated in the circular aperture defined by the edge  38 . 
         [0021]    The invention has been described in an illustrative manner. It is, therefore, to be understood that the terminology used is intended to be in the nature of words of description rather than of limitation. Many modifications and variations of the invention are possible in light of the above teachings. Thus, within the scope of the appended claims, the invention may be practiced other than as specifically described.