Patent Publication Number: US-2007107174-A1

Title: Methods and apparatus for fastening panels

Description:
BACKGROUND OF THE INVENTION  
      The present invention relates to methods and apparatus for fastening panels together, such as for securing a door trim panel to a door module of a vehicle.  
      Door trim panels are employed as interior components on automotive vehicles. One of the purposes of such interior trim panels is to present an aesthetically pleasing appearance. Door trim panels are typically mounted to structural support members on the door module. For example, door trim panels are mounted to an inner door sheet metal panel or to a door module (or frame) which replaces the traditional inner door sheet metal of the automotive vehicle.  
      There exist a variety of conventional fasteners for attaching panels to support members in the automotive industry. A common problem with assembling such panels has been that the fasteners are difficult to align with mating fasteners in the sheet metal of the frame. As a result, misaligned fasteners sometimes result in a mallet being employed to attach the door panel to the frame, often resulting in the fracture the fastener. Additionally, poor fastener design will subject the fasteners to overstressing during assembly or use (i.e., shutting door) and may cause the fastener to break or fatigue or otherwise result in a loss in retention strength for holding the door trim panel in place. As a result, some conventional door trim panels frequently become loose.  
      Many conventional fasteners are of two-piece construction: the door trim panel includes a socket often referred to as a “doghouse” and the frame includes a pin (e.g., head and shaft) arrangement. The pin secures to the frame and may be snap-fit into the doghouse to secure the door trim panel to the frame. A plurality of such fasteners are usually employed to secure the door trim panel to the frame. The heads of the pins may be preassembled into the respective doghouses. Once a desired number of pins have been secured to the door trim panel via the doghouses, the panel may be secured to the frame by inserting the shaft (or shank) ends of the pins into respective bores formed through the frame. The benefit of using the doghouses to secure the pins to the door trim panel is that a blind connection may be made between the panel and frame, i.e., there is no externally visible fastener present in the door trim panel once the connection between the panel and the frame has been made.  
      Of significant concern in a two-piece fastener design are the degree to which the pins are easily aligned and inserted into the doghouses, and the degree to which the pins are retained in the doghouses once snapped in.  
      U.S. Pat. No. 6,594,870 discloses a conventional two-piece fastener for coupling a door trim panel to a frame, the entire disclosure of which is hereby incorporated by reference. A doghouse  15  includes a wall  16  and an aperture  25  therethrough, the aperture  25  having a generally circular opening with an open edge  27  for lockably receiving a grommet  40  of a pin  60 . The doghouse  15  includes inclined surfaces  26  and  28  for camming the grommet  40  into the aperture  25 . A pair of resilient arms  30 ,  32  extend from a leading edge of the wall  16  toward the aperture  25 . The arms  30 ,  32  have tips  31 ,  33 , respectively, which engage and lock the grommet  40  in place once inserted into the keyed aperture  25 . The tips  31 ,  33  of arms  30 ,  32 , respectively, have inclined camming surfaces  34  to assist in deflecting the arms  30 ,  32  as the grommet  40  is snap-locked into the aperture  25 . The socket  15  may be integrally molded of a polymeric material and integrally formed with the door panel  10  or otherwise suitably attached thereto by ultrasonic welding, adhesive bonding, or the like.  
      Among the problems that the inventors herein have discovered with the doghouse design employed in U.S. Pat. No. 6,594,870 and by others is that an overall depth dimension of the doghouse must be relatively large to accommodate the resilient arm(s), e.g. the arms  30 ,  32  of U.S. Pat. No. 6,594,870 that extend from the leading edge of the wall  16  toward the aperture  25 .  
      Another conventional two-piece fastener includes bumps or ridges to achieve the snap-fit connection of the pin and doghouse as opposed to using resilient arms as in U.S. Pat. No. 6,594,870. The bumps are disposed around the slot/aperture to retain the grommet in the aperture. While the use of bumps may reduce the depth dimension of the doghouse somewhat, it does not reduce such dimension as much as would be desirable and it increases the likelihood that the pin will disengage from the doghouse.  
      As a result of all the difficulties with existing fasteners for attaching, e.g., vehicle trim panels to vehicle sheet metal, and particularly door panels to the sheet metal structure of a door, warranty claims for loose panels and broken fasteners are one of the major concerns in the automotive interior trim field.  
      Thus, there are needs in the art for a new approach to securing a panel to a frame, preferably which reduces the depth dimension of the doghouse and/or improves the ability of the pin to remain locked in the doghouse.  
     SUMMARY OF THE INVENTION  
      In accordance with one or more embodiments of the present invention, a fastener system for attaching, e.g., an interior door trim panel to a metal frame of the door (or door module), may include a plurality of fasteners (or pins) and doghouses. Some or all of the fasteners may each include a shaft with a head sized and shaped to snap-fit into the doghouse. The shaft of the fastener may connect to the metal door frame by resistance or interference fit. The doghouses are preferably integrally molded with the interior door panel. The doghouses may each include an insertion area that slideably receives a head of one of the fasteners, such that it is clipped in. The insertion area preferably includes a keyhole-shaped aperture for receiving the head and a clip that is located under the aperture. More specifically, the clip preferably includes a pivotable arm that extends from a first end at a rear of the aperture to a second end terminating toward (and/or forward) of the aperture. The clip may include an angle snap at the second end to engage the head of the fastener. The doghouse may include one or more guides (or ribs) below the aperture to prevent the head from moving downward through the clip (e.g., longitudinally with respect to the pin).  
      Among the advantages of the embodiments of the invention includes the ability to reduce the depth dimension of the doghouse as compared with some conventional designs without sacrificing retention of the pin in the doghouse. In particular, the doghouse depth may be reduced at least in part because the clip extends from the first end at a rear of the aperture to the second end terminating toward (and/or forward) of the aperture. Thus, additional structural footprint need not be employed to accommodate a clip extending from the opposite direction.  
      The door panel can be assembled to the door module in two ways: (1) with the shafts of the fasteners already inserted in the door module and the heads of the fasteners elevated somewhat, the door panel is slid into position such that the doghouses slide over the heads and capture them; or (2) with the heads of the fasteners already slid into the doghouses, the door panel is pressed against the door module such that the shafts of the fasteners are inserted into respective bores the door module.  
      In accordance with one or more aspects of the present invention, an apparatus for coupling a panel to a frame includes: a support plate coupled to the panel; an engagement plate extending transversely from the support plate and having an aperture extending therethrough; and a clip having a pivotable arm extending from the support plate at a first end, and at least partially under the aperture to a second end. The plate, aperture and clip are preferably sized and shaped to slideably receive a head and shaft of a mating fastener, coupled to the frame, toward the support plate such that the second end of the pivotable arm engages the head when the shaft is fully received in the aperture. It is noted that in some embodiments, the support plate may be an integral part of the panel.  
      The clip preferably includes an angle snap at the second end thereof, the angle snap being operable to retain the head of the mating fastener after it is received in the aperture. For example, the angle snap may include a sloping surface from the second end of the clip toward the engagement plate for slideably engaging the head of the mating fastener and pivoting the clip away from the aperture during insertion thereof toward the support plate. Alternatively or in addition, the angle snap may include a hook element adjacent to the sloping surface, the hook element being operable to retain the mating fastener within the aperture when the head thereof slides off of the sloping surface toward the support plate and the clip pivots back toward the engagement plate. For example, the hook element may include a surface extending transversely from the pivotable arm of the clip substantially toward the engagement plate, the surface of the hook element engaging the head of the mating fastener to retain same in the aperture.  
      The engagement plate preferably includes a slot extending from a leading edge thereof to the aperture, the slot including inwardly directed side surfaces operable to guide the head and shaft of the mating fastener toward the support plate and into the aperture. The second end of the clip may be positioned proximate to the slot. The second end of the clip may extend short of, at, or past the leading edge of the engagement plate.  
      The apparatus may further include at least one guide rib having at least a portion of a surface sloping toward the engagement plate to guide the head and shaft of the mating fastener into the aperture. For example, the at least one guide rib may include a respective guide rib disposed on opposite sides of the aperture, each guide rib having at least a portion of a surface sloping toward the engagement plate to guide the head and shaft of the mating fastener into the aperture. The guide rib(s) prevent the head from moving downward through the aperture and placing excessive pressure the clip (which might damage the clip and other structures).  
      In accordance with one or more aspects of the present invention, a method for coupling a panel to a frame includes: coupling an engagement plate substantially parallel to the panel, the engagement plate having an aperture extending therethrough which is oriented transversely to the panel, and a slot extending from a leading edge of the engagement plate to the aperture, the slot including inwardly directed side surfaces operable to guide a head and shaft of a mating fastener into the aperture; providing a clip having a pivotable arm extending from a first end at least partially under the aperture and at least toward the leading edge of the engagement plate to a second end; slideably receiving the head and shaft of the mating fastener into the aperture; and preventing the head and shaft of the mating fastener from sliding out of the aperture through the slot using the clip in tension.  
      Other aspects, features, advantages, etc. will become apparent to one skilled in the art when the description of the preferred embodiments of the invention herein is taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      For the purposes of illustrating the various aspects of the invention, there are shown in the drawings forms that are presently preferred, it being understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown.  
       FIG. 1  is a perspective view of a two-piece fastening system for coupling a panel to a frame in accordance with one or more embodiments of the present invention;  
       FIG. 2  is an elevational view (e.g., side view) of the fastening system of  FIG. 1 ;  
       FIG. 3  is plan view (e.g., top view) of the fastening system of  FIG. 1 ;  
       FIG. 4  is a perspective view of a clip of the fastening system of  FIG. 1 ; and  
       FIG. 5  is a sectional view of the fastening system of  FIG. 2  taken through line  4 - 4 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      With reference to the drawings, wherein like numerals indicate like elements, there is shown in  FIG. 1 a  perspective view of a fastening system  100  for connecting a panel  102  to a frame  104  in accordance with one or more embodiments of the present invention. It will be appreciated by those skilled in the art that the panel  102  and frame  104  may be employed in any number of different mechanical contexts. By way of example, and not by limitation, the panel  102  may be a door trim panel  102  for the interior of an automobile and the frame  104  may be the door module  104  of the automobile to which the panel  102  is to be secured. The door module  104  preferably represents one or more structural elements of the door of a vehicle and the door trim panel  102  represents an aesthetically pleasing panel that covers the less aesthetically pleasing components of the door module  104 . The door trim panel  102  is preferably coupled to the door module  104  by way of one or more fastening systems  100 , one such system  100  being shown for brevity and clarity. In a preferred embodiment, numerous fastening systems  100  would be utilized in different locations to ensure that the door trim panel  102  is securely attached to the door module  104 .  
      The fastening system  100  includes a doghouse  106  and a mating fastener (or pin)  108 . The doghouse  106  includes a support plate  110  extending transversely (e.g., perpendicularly) from the panel  102 , and an engagement plate  112  extending transversely from the support plate  110 . Although not required, it is preferred that the engagement plate  112  extends substantially perpendicularly from the support plate  110  and substantially parallel with the panel  102 . The engagement plate  112  preferably includes an aperture  114  extending therethrough, preferably with its axis oriented transversely with respect to the panel  102 . The engagement plate  112  also preferably includes a slot  116  extending from a leading edge  118  of the engagement plate  112  to the aperture  114 . In this regard, although not required the aperture  114  and slot  116  may assume a keyhole shape. Preferably, the slot  116  includes inwardly directed side surfaces  120 ,  122  that taper from the leading edge  118  toward the aperture  114 .  
      Preferably, the doghouse  106  is integrally formed of injection moldable plastic material so as to be of a one-piece construction. Most preferably, the doghouse  106  is integrally molded with the panel  102  using suitable polymeric materials.  
      Although the pin  108  may take on any number of features and characteristics known to those skilled in the art, or apparent to those skilled in the art from the description herein. By way of example, the pin  108  may include a shaft  124  that extends through a bore  126  in the door module  104 , e.g., by way of fins  128 . At a distal end of the shaft  124 , the pin  108  preferably includes a head  130  that defines a mating mechanism for the doghouse  106 . For example, the head  130  may include a grommet formed by first and second disks  132 ,  134  separated by a portion of the shaft  124 .  
      Preferably, the engagement plate  112 , slot  116 , and aperture  114  are sized and shaped to slideably receive the head  130  of the mating fastener  108  and retain same therein in order to securely couple the panel  102  to the door module  104 .  
      In accordance with one or more embodiments of the invention, the fastening system  100  may include further features to accomplish the snap-fit connection of the mating fastener  108  in the doghouse  106 . In this regard, reference will now be made to  FIGS. 2-5 . For example, the doghouse  106  may optionally include a clip  140  having a pivotable arm  142  extending from the support plate  110  at a first end  144 . The clip  140  preferably extends from the first end  144  at least partially under the aperture  114  to a second end  146 . As best seen in  FIG. 5 , the engagement plate  112 , aperture  114 , and clip  140  are preferably sized and shaped such that the head  130  of the mating fastener  108  slideably enters the doghouse  106  and is retained therein by the second end  146  of the pivotable arm  142 .  
      By way of example, the clip  140  may include an angle snap at the second end  146  thereof, where the angle snap is operable to retain the head  130  of the mating fastener  108  after it is received in the aperture  114 . More particularly, the angle snap may include a sloping surface  148  from the second end  146  of the clip  140  toward the engagement plate  112 . The sloping surface  148  is operable to slideably engage the head  108  (e.g., the disk  134  thereof) of the mating fastener  108  and to cause the arm  142  to pivot about the first end  144  and to cause the angle snap of the clip  140  to move away from the engagement plate  112  as the head  130  slides through the slot  116  into the aperture  114 .  
      As best seen in  FIGS. 2-4 , the support plate  110  may optionally include a slot  150  to assist in achieving the pivotable action of the clip  140 . In particular, the slot  150  provides relief to the first end  144  of the pivotable arm  142  such that the torsional forces generated at the first end  144  of the arm  142  in response to the engagement of the head  130  with the sloping surface  148  may be distributed along a portion  152  of the support plate  110 . Those skilled in the art will appreciate that the length of the portion  152  may be adjusted from zero to some maximum length depending on desired amounts of flexibility and of distribution of the torsional forces desired by the designer. Alternatively and/or in addition, the clip  140  may include an undercut  154  (shown in dashed lines) at the first end  144  of the pivotable arm  142  to assist in pivotable movement of the clip  140 . Alternative embodiments of the invention may omit the slot  150  and the clip may depend from the support plate  100  directly as a simple lever arm.  
      The clip  140  preferably includes a hook element  160  adjacent to the sloping surface  148 . The hook element  160  is preferably operable to retain the head  130  of the mating fastener  108  within the aperture  114  when the head  130  slides off the sloping surface  148  toward the support plate  110  and the clip  140  pivots back toward the engagement plate  112 . In this regard, the hook element  160  preferably includes a surface  162  extending transversely from an upper surface  164  of the pivotable arm  142  and toward the engagement plate  112 . Thus, the surfaces  162 ,  164  of the clip  140  preferably retain the head  130  of the mating fastener  108  (e.g., the disk  134  thereof) from moving downward (vis-à-vis surface  164 ) or out through the slot  116  (vis-à-vis surface  162 ). Indeed, once the clip  140  pivots back into its resting position, the disk  134  is preferably trapped against a lower surface of the engagement plate  112  on the one hand, and by the surfaces  162 ,  164  on the other hand.  
      Preferably, the second end  146  of the clip  140  is positioned proximate to the slot  116 . Indeed, those skilled in the art will appreciate that the second end  146  of the clip  140  may terminate short of the leading edge  118  of the engagement plate  112 , at the leading edge  118 , or past the leading edge  118 .  
      As best seen in  FIG. 2 , the sloping surface  148  and the side edges  120 ,  122  preferably define a conical guide feature that guides the head  130  of the mating fastening  108  into the aperture  114 . The aperture is preferably slightly larger than the shaft  124  portion of the head  130  to assist in ensuring that the head  130  may engage the doghouse. In a preferred embodiment, the aperture  114  also includes a tapered edge  166 , such as at a 5 degree angle for tooling and ease of manufacturing purposes.  
      The panel  102  can be assembled to the door module  104  in a number of ways, such as: (1) with the shafts  124  of the fasteners  108  already inserted in the door module  104  and the heads  130  of the fasteners  108  elevated somewhat, the door panel  102  is slid into position such that the doghouses  106  slide over the heads  130  and capture them; or (2) with the heads  130  of the fasteners  108  already slid into the doghouses  106 , the panel  102  is pressed against the door module  104  such that the shafts  124  of the fasteners  108  are inserted into respective bores  126  the door module  104 .  
      The doghouse  106  may also include at least one guide rib  170  having at least a portion  172  thereof sloping toward the engagement plate  112  to guide the head  130  of the mating fastener  108  into the aperture  114 . In a preferred embodiment, a first guide rib  170  and a second guide rib  174  are disposed on opposite sides of the aperture  114 , where each guide rib includes a surface that at least partially slopes toward the engagement plate  112 . Advantageously, the guide ribs  170 ,  174  assist in guiding the head  130  into the doghouse  106  as well as preventing the mating fastener  108  from moving downward (e.g., longitudinally with respect to the shaft  124  direction) into the doghouse  106  and potentially damaging same.  
      Advantageously, the clip  140  permits serviceability of the panel  102 , e.g., the panel  102  may be disconnected from the frame  104  numerous times without damaging the doghouse  106  or the fastener  108 . Another advantage of the design of the clip  140  is the ability to reduce the depth dimension of the doghouse  106  as compared with some conventional designs without sacrificing retention of the mating fastener  108  in the doghouse  106 . Further advantages include improved guiding of the head  108  into the doghouse, for example, resulting from employing one or more of the features of the clip  140 , the slot  116  and the rib(s)  170 ,  174 .  
      Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims.