Abstract:
A one-piece, zinc die cast electrical connection fitting for a junction box characterized by snap-in locking fingers positioned 180° apart on the leading or the insertion end of the fitting and tensioning fingers on either side of the locking fingers.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to electrical connectors, and more specifically to a new and improved snap-in connector for electrical junction boxes and the like. 
     BACKGROUND OF THE INVENTION 
     Snap-in connectors have been used to connect flexible metallic conduit and metal clad cable to electrical junction boxes. These connectors are an improvement over the prior use of lock nuts that are threaded on the end of an electrical fitting extending through a hole into the interior of the box. 
     U.S. Pat. No. 5,171,164, dated Dec. 15, 1992, discloses a snap-in connector consisting of a zinc die cast fitting that carries a spring steel adaptor ring designed to secure the fitting to a junction box. The split ring spring steel adaptor is formed with three radially outwardly bent locking tabs and three radially outwardly bent tensioning fingers. In use, the end of the zinc die cast fitting carrying the spring steel adaptor is pushed through an opening in the junction box until the locking tabs clear the edge of the opening and spring outwardly against the inner wall surface of the box, thereby preventing the fitting from being withdrawn. The tensioning fingers press against the edge of the opening to exert tension between the spring steel adaptor and the inner circumference of the opening in the box. 
     As disclosed in U.S. Pat. No. 5,171,164, the spring steel adaptor ring requires separate manufacturing and assembly operations. A stamping is made with the outwardly bent tabs and fingers. The stamping is then bent into a split ring which must assembled onto the zinc die cast fitting. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a quick connect fitting for an electrical junction box consisting of a one-piece, zinc die cast fitting having the snap-in capability described in U.S. Pat. No. 5,171,164 without requiring a separately formed, split ring spring steel adaptor. 
     The invention is based on the discovery that it is possible to make a one-piece, zinc die cast fitting with flexible locking fingers or tabs and tensioning fingers by locating the locking fingers 180° apart and forming the tensioning fingers adjacent to and on either side of each locking finger. The one-piece construction of the invention eliminates the need for making a split ring steel adaptor in manufacturing operations separate from the zinc die casting and then assembling the ring onto the die cast fitting. 
     In a preferred and disclosed embodiment, the snap-in connector of this invention is a one-piece die cast member having a cylindrical end portion, an outer radial collar, two locking fingers or tabs spaced 180° apart that spread outwardly from the cylindrical end portion toward the collar, the locking fingers having free ends that are spaced from the collar and can be flexed radially inwardly, and tensioning fingers formed in the cylindrical leading end portion adjacent to and on each side of the locking fingers. The tensioning fingers spread outwardly from the leading end portion toward the collar and have free ends that can be flexed radially inwardly. In use, the locking and tensioning fingers are flexed radially inwardly by inserting the leading end portion of the die cast fitting through an opening in the wall of a junction box until the free ends of the locking fingers are completely through the opening end and flex outwardly to engage the inside wall surface of the box, thereby preventing the fitting from being withdrawn. The free ends of the tensioning fingers remain engaged with the edge of the box opening in order to center and form a firm connection between the fitting and the box. 
     Because of the placement of the locking and tensioning fingers, it is possible to form the fingers as integral parts of the zinc die casting. Even though they are an integral part of the die casting, the fingers have the flexibility necessary to provide a secure snap-in connection. Thus, the construction eliminates the need for a separately formed spring steel adaptor that heretofore has been considered necessary to achieve a snap-in connection. 
     Other advantages and a fuller understanding of the invention will be apparent to those skilled in the art from the following detailed description and the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view showing the die cast fitting of the invention assembled to a junction box. 
     FIG. 2 is a perspective view of the die cast fitting. 
     FIG. 3 is an end view of the die cast fitting. 
     FIG. 4 is a side elevational view taken in the plane of the lines  4 — 4  of FIG.  3 . 
     FIG. 5 is an elevational view taken in the plane of the lines  5 — 5  of FIG.  4 . 
     FIG. 6 is an enlarged, fragmentary sectional view showing the fitting of the invention assembled to the wall of the junction box. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENT 
     The snap-in connector of the invention is a one-piece, zinc die-cast fitting generally designated by reference numeral  10 . In FIG. 1, the fitting  10  is shown assembled to a junction box  11  through an opening  12  in a wall  13  of the junction box. 
     The die cast fitting  10  has a trailing end  14  adapted to be connected to flexible metallic conduit or metal clad cable, a cylindrical leading end portion  15  and a radial collar  16 . The trailing end  14  can be made to connect various metallic conduit/cable and non-metallic cable in any desired manner and does not form a part of the present invention. 
     The leading end portion  15  is uniquely formed with two locking fingers  20  spaced 180° apart and tensioning fingers  21  adjacent to and on each side of each locking finger  20 . As shown, the fingers  20 ,  21  are separated by notches  19  in the end portion  15  of the die cast fitting  10 . The locking fingers  20  spread radially axially outwardly from near the outboard end of the leading end portion  15  toward the collar  16 . The free ends  22  of the fingers  21  have exterior cam surfaces  23  that engage the edge of the box opening  12  when the fitting  10  is inserted into the opening. This causes the locking fingers  20  to flex radially inwardly during assembly of the fitting  10  to the junction box  11 . As shown in FIGS. 1 and 6, the free ends  22  of the locking fingers  20  are spaced from the face of the collar  16  so as to engage the inside surface of the box wall  13  when the fitting has been fully inserted, thereby capturing the box wall between the fingers  20  and the collar  16 . 
     The free ends  24  of the tensioning fingers  21  have cam surfaces  25  that engage the edge of the box opening  12  so that the fingers are flexed inwardly during insertion of the fitting  10 . The free ends  24  terminate closely adjacent the flange or collar  16 , whereby the tensioning fingers do not pass completely through the opening  12  of the box wall  13 . When the fitting  10  is inserted into the junction box opening with the collar  16  against the outer surface of the box wall  13 , as shown in FIG. 6, the fingers  21  are in engagement with the edge of the opening  12 . The engagement of the tensioning fingers  21  with the edge of the opening serves to provide firm contact between the fitting  10  and the box  11 , as well as keeping the fitting centered in the opening. 
     In use, the die cast fitting  10  has a snap-fit with the junction box  11  which is accomplished simply by pushing the leading edge  15  into an opening  12  of the junction box  11  which causes the fingers  20 ,  21  to flex inwardly. The assembly of the fitting to the junction box is facilitated by the outer cam surfaces  23 ,  25  of the fingers  20 ,  21 , respectively. When the collar  16  is adjacent the outer surface of the box wall  13 , the locking fingers  20  are through the opening of the box wall and engage its inner surface to prevent the fitting from being withdrawn. At the same time, the tensioning fingers  21  engage the edge of the opening  12 . 
     As described above, an important feature of the invention is the formation of the fitting as a one-piece die casting that includes flexible locking and tensioning fingers. The ability to die cast the fingers is accomplished by positioning the locking fingers 180° apart and locating the tensioning fingers on each side of the locking fingers. 
     Many modifications and variations of the invention will be apparent to those skilled in the art in light of the foregoing detailed disclosure. Therefore, it is to be understood that, within the scope of the appended claims, the invention can be practiced otherwise than as specifically shown and described.