Abstract:
A connector assembly including a connector body with a spring clip including a first free end for engaging a side wall of an electrical box upon installation. During insertion of the connector body the first free end engages the knock-out hole perimeter and deforms so as to permit further insertion. Once the connector body is fully inserted, the spring clip cooperates with a lug on the connector body to hold the connector assembly onto the electrical box. The connector body includes one or more spiral indentations for engaging a convolution of a metal cable. The spring clip biases the cable toward engagement with the spiral indentation to yield improved performance characteristics.

Description:
TECHNICAL FIELD 
     The invention is directed to a further advancement in the field of electrical connector assemblies. More specifically, this application relates to a snap-fit electrical connector assembly having a construction for facilitating the connection of the connector assembly and associated cable, wire conductor and the like to an electrical box. 
     BACKGROUND OF THE INVENTION 
     Electrical connectors are commonly used for attaching electrical conductors, cables, wires, electrical metal tubing (EMT) or the like to an electric box, e.g. a junction box, outlet box, switch box, fuse box, or other similar type of electric box. Such known electrical connectors are either of a type that are secured to an electric box by a threaded lock nut or by means of a circular snap fit retaining ring of the type disclosed in U.S. Pat. Nos. 6,860,758; 6,444,907; 5,189,258; 5,266,050; and 5,171,164, for example. 
     So called “snap fit” connectors have been in use for some time, including connectors disclosed in Applicant&#39;s U.S. Pat. Nos. 7,064,272; 7,075,007; 7,205,489 and 7,214, 890. Such connectors have typically been coupled to the junction box by forcibly inserting one end of the connector into the knock-out hole of a junction box. Such connectors include a circular retaining ring which is deformed during insertion of the connector body into a knock-hole. In the past, a generally linear motion has been used to insert the connector end into the junction box. Using such a straight motion, the connector end is pushed into the knock out hole so as to deform a retaining ring as it passes through the knock-out hole. 
     The snap-fit connectors typically are constructed of several pieces including a barrel shaped body with separate sleeves or collars formed of spring steel. As the snap-type connectors are constructed of several pieces, the complexity of the connector is increased. A need exists for a simple, snap-in connector having fewer component parts. A need also exists for improved manufacturing processes to decrease fabrication time of connector assemblies. 
     SUMMARY OF THE INVENTION 
     The present invention provides a connector assembly including a connector body, a spring clip and an insulator. The spring clip is multi-purpose and functions in one embodiment to both retain the connector assembly upon an electrical box and also retain an electrical cable end received within the connector body. During insertion of the connector body a free end of the spring clip engages the knock-out hole and deforms so as to permit further insertion. Once the connector body is fully seated, the free end cooperates with a locking lug on the connector body to hold the connector assembly onto the electrical box. In a preferred embodiment, the spring clip functions to both retain the connector assembly upon an electrical box and also retain an electrical insulator at a front portion of the assembly. In another embodiment the spring clip additionally functions to retain an electrical cable received within the connector body. 
     The present invention is also directed to a connector body with a multi-function spring clip which cooperates with a spiral indentation defined on an interior surface of the connector body to yield improved performance characteristics. The spiral indentation may be an open spiral-shaped slot extending from an interior surface to an exterior surface of the connector body. Alternatively, the spiral indentation may be a closed slot structure, such as in the form of a spiral channel defined only in the interior of the connector body. In another embodiment, the spiral indentation may comprise multiple short linear indentations aligned in a spiral manner around the interior surface of the connector body. 
     The spiral indentation is preferably positioned generally opposite the spring clip so that the spring clip biases a cable, such as flexible metal clad cable, toward engagement with the spiral indentation. The spiral indentation may be defined with relatively sharp edges, for example a spiral channel with generally perpendicular walls (relative to the inner surface of the connector body). The spiral indentation is preferably aligned to correspond to the angled spiral convolutions of flexible metal clad cable, armor clad cable, or flexible metal conduit and the spring clip functions to bias the cable or conduit into engagement with the spiral indentation. 
     Engagement between the convolutions of the cable or conduit with the edges of the spiral indentation may yield a beneficial additional retention force as compared to a connector assembly without the spiral indentation. This additional retention force may contribute to the connector meeting or exceeding applicable UL pull-out force requirements. 
     The edges of the spiral indentation also provide a number of high-pressure contact points between the connector body and the armor cable, which results in a lower voltage drop (less electrical resistance) across the fitting when mated to a box. This mechanical engagement between the convolutions of the armor cable and the spiral indentation of the connector body may lower the voltage drop across the connector body and contribute to the connector meeting UL resistance drop requirements. 
     The present invention is also directed to a method of using a connector assembly, wherein the method includes inserting a nose end of the connector assembly into the knock-out hole with the free end of the spring clip initially deflecting from contact with a side wall of the junction box, then further inserting the connector assembly into the junction body to release the free end and lock the connector body in place. As the connector body is rotated during installation, the free end of the spring clip is initially deformed by contact with the side wall of the junction box and is then released after the spring clip end is within the junction box. When the armor cable or metal clad cable is inserted into the connector body the spiral convolutions of the cable are engaged against one or more spiral indentations in the interior of the connector body. The spring clip functions to bias the cable or conduit into engagement with the spiral indentation of the connector body. 
     An object of the present invention is to provide an electrical connector with a multi-function spring clip whereby the connector body is secured to an outlet box through simple insertion into an outlet box and whereby the cable convolutions are biased into engagement against a spiral indentation on the interior surface of the connector body. 
     Yet another object of the present invention is to provide an electrical connector with a spring clip having a first free end for cooperating with an edge of a knock-out hole of an outlet box to retain the electrical connector and a second free end for engaging an electrical wire. The spring clip generates a force tending to retain the connector body within the knock-out hole of the electrical box. 
     Yet another object of the present invention is the provision of a group of related electrical connectors having a unique front-end including a multi-function spring clip and retained insulator while providing a variety of back-ends adapted to a engage a variety of cable ends, including but not limited to MC (metal clad cable) or AC (armor clad cable) cables or flexible metal conduit (FMC). The flexible nature of an internal spring clip permits the connector assembly to be utilized across a range of cable diameters. 
     Yet another object of the present invention is the provision of a multi-function spring clip serving to limit pull-out of the electrical connector from an electrical box while retaining an electrical insulator against displacement. In some embodiments the multi-function spring clip also functions to secure electrical cable(s) within the connector and even define a cable divider for maintaining a separation between a pair of electrical cables. 
     The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims. The novel features which are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the present invention, reference is now made to the following descriptions taken in conjunction with the accompanying drawing, in which: 
         FIG. 1  is a perspective view of an electrical connector assembly in accordance with the present invention, depicted as being attached to an electrical junction box. 
         FIG. 2  is a perspective view of the electrical connector assembly of  FIG. 1 . 
         FIG. 3  is a perspective view of the electrical connector assembly of  FIG. 1  in a disassembled form. 
         FIG. 4  is another perspective view of the electrical connector assembly of  FIG. 1 . 
         FIG. 5  is a bottom plan view of the electrical connector assembly of  FIG. 4 . 
         FIG. 6  is a side elevational view of the electrical connector assembly of  FIG. 4 . 
         FIG. 7  is top plan view of the of the connector assembly of  FIG. 4 . 
         FIG. 8  is cross-sectional view of the connector assembly of  FIG. 7  taken along lines  8 - 8 . 
         FIG. 9  is a top plan view of the connector assembly of  FIG. 1  shown secured to an electrical junction box. 
         FIG. 10  is cross-sectional view of the connector assembly of  FIG. 9  taken along lines  10 - 10 . 
         FIG. 11  is a detailed view of a portion of  FIG. 10   
         FIG. 12  depicts a method of inserting a connector assembly of  FIG. 1  into an electrical junction box. 
         FIG. 13  is top plan view of the connector assembly of  FIG. 12  as being attached to an electrical box. 
         FIG. 14  is a perspective view of a second embodiment of an electrical connector assembly of the present invention. 
         FIG. 15  is a perspective view of the connector assembly of  FIG. 14 . 
         FIG. 16  is a bottom view of the connector assembly of  FIG. 14 . 
         FIG. 17  is a side view of the connector assembly of  FIG. 14 . 
         FIG. 18  is a cross-sectional view of the connector assembly of  FIG. 17  taken along lines  18 - 18 . 
         FIG. 19  is a top plan view of the connector assembly of  FIG. 14  attached to an electrical junction box. 
         FIG. 20  is a bottom plan view of the connector assembly of  FIG. 14 . 
         FIG. 21  is a cross-sectional view of the connector assembly of  FIG. 19  taken along lines  21 - 21 . 
         FIG. 22  is a detailed view of a portion of  FIG. 21 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to the drawings,  FIGS. 1 and 2  are perspective views of the first embodiment of an electrical connector assembly  10  in accordance with the present invention.  FIGS. 1 and 2  depict connector assembly  10  between junction box  12  and electrical cable  14 . As described hereinafter, connector assembly  10  is used to couple electrical cable  14  at knock-out hole  16  of electrical box  12 . 
     Connector assembly  10  includes connector body  20 , spring clip  22 , and insulator  24 . Connector body  20  is formed with an inlet end portion  26  and an outlet end portion  28  and a bore  30  extending therethrough. As described hereinafter, connector body  20  further includes a spiral indentation  61  on an interior surface adapted to engage a spiral convolution of cable  14 . 
     Referring to  FIG. 3 , connector assembly  10  is depicted in a disassembled form. Connector body  20  includes a bridge portion  32  defined between a pair of open portions  34 ,  36 . Bridge portion  32  includes a generally planar surface  38  separating a pair of longitudinally extending walls  40 . A fastener, shown as a rivet  42 , secures a central portion of spring clip  22  to the planar surface  38 . Walls  40  prevent spring clip  22  from rotation about rivet  42 . A variety of different fasteners may be used to secure spring clip  22  to connector body  20 , including but not limited to threaded fasteners, rivets, etc. 
     Intermediate the connector body  20 , in the illustrated embodiment between the inlet end portion  26  and outlet end portion  28 , there is provided radially outwardly extending flange  44  which functions as a stop to limit the degree to which connector body  20  may be inserted through the knock-out hole  16  of electrical box  12 . In the illustrated embodiment, stop flange  44  is unbroken, while in alternative embodiments stop flange  44  may comprise disjointed or separated elements, such as tabs on connector body  20  together functioning to limit the degree to which connector body  20  may be inserted into the electrical box  12 . 
     Outlet end portion  28  includes a wedge-shaped lug  45  adapted to engage a knock-out hole  16  perimeter during insertion of the connector body  20  into the knock-out hole. As described in more detail hereinafter, lug  45  is part of a positive locking mechanism by which the connector body  20  is secured to electrical box  12 . 
     Insulator  24  is of electrically insulative material and includes an annular groove  46  adapted to engage a corresponding tongue  48  within a receptacle  49  at the outlet end portion  28  of connector body  20 . In the illustrated embodiment, insulator  24  is inserted into a generally u-shaped receptacle  49  in a direction generally perpendicular to a longitudinal axis of connector body  20 . Insulator  24  is prevented from substantial movement along the longitudinal axis of connector body  20  by contact between tongue  48  and groove  46 . As described hereinafter, insulator  24  is held within connector body  20  by a forward free end of spring clip  22 . In another embodiment, the insulator  24  may be inserted into the connector body  20  along the longitudinal axis. For example, the insulator may be pressed into an open end of the connector body. 
     Spring clip  22  includes a central portion  50  and a pair of free ends  52 ,  54 . Spring free end  52  includes a hook structure including a hook end  56  and a tab  58 . A pair of tapered wing portions  60  provide additional electrical continuity between spring clip  22  and the electrical box  12 . Spring free end  54  defines a cable-engaging end which preferably engages the cable at the base of a convolution. 
     Referring to  FIG. 4 , connector body  20  includes spiral indentation  61  on an interior surface within bore  30 .  FIG. 5  is a bottom view of the connector assembly  10  showing spiral indentation  61  extending through the wall of the connector body  20 . 
     Connector assembly  10  is especially useful for securing MC (metal clad) or armored cable  14  to a panel or electrical box. MC or armored cable  14  include a convoluted outer surface consisting of peaks and grooves such as shown in  FIG. 1 . 
     Spiral indentation  61  is positioned at an angle, a, relative to the longitudinal axis, LA, of the connector assembly  10 . Angle, a, corresponds to a spiral convolution angle of cable  14  so that at least a portion of a spiral convolution of cable  14  engages with edges of spiral indentation  61 . The angle, a, is approximately equal to a common armor convolution pitch (helix angle of cable) of fifteen degrees (15°).  FIG. 6  is a side view of the connector assembly showing spiral indentation  61  position generally opposite the spring clip  22 . 
       FIG. 7  is a top plan view of the connector assembly  10 .  FIG. 8  is a cross-sectional view of the connector assembly  10  of  FIG. 7  taken along lines  8 - 8 . In operation, and with the cable  14  inserted into the connector assembly  10 , the free end  54  of spring clip  22  biases the cable  14  into engagement with the spiral indentation  61 . 
       FIG. 9  is a top plan view of the connector assembly  10  shown attached to a cable  14  and electrical box  12 .  FIG. 10  is a cross-sectional view of the assembly of  FIG. 9  taken along lines  10 - 10 . Cable  14  is inserted into the bore  30  of the connector body  20  and, as a result of the flexibility imparted to the free end  54  of spring clip  22  by the length and angle of the free end, is engaged by the cable-engaging end in one of the grooves of cable  14 . Insertion of cable  14  into the connector body  20  is limited by the insulator  24  held at the outlet end portion  28 . 
       FIG. 11  is a detailed view of a portion of  FIG. 10  showing engagement between the spiral convolution of cable  14  and the spiral indentation  61  of connector body  20 . Spring free end  52  extends from central portion  50 , spans across open portion  36  and across a portion of insulator  24 . Hook end  56  engages an inner surface of electrical box  12  and tab  58  engages an outer surface of electrical box  12 . Upon insertion of the outlet end portion  28  into electrical box  12 , the hook structure of spring end  52  initially deflects and then retracts to secure the connector assembly  10  to the electrical box. Spring end  54  engages cable  14 , preferably within a cable groove and provides a force tending to resist withdrawal of cable  14  from connector assembly  10 . Spring clip  22  can accommodate a range of MC/AC cables. 
       FIG. 12  depicts insertion of connector assembly  10  into electrical box  12 . Lug  45  is initially inserted to engage a lower edge portion of hole  16  and connector body  20  is then rotated generally about the lower edge portion. As spring end  52  engages an upper edge portion of hole  16 , spring clip  22  deflects into the open portion  36  of connector body  20 . Upon full insertion, as shown in  FIG. 13 , spring clip  22  retracts and engages inner and outer surfaces of the electrical box  12 . 
       FIG. 12  also illustrates a tapered contact rib  62  on outlet end portion  28 . Contact rib  62  functions to center connector body  20  within hole  16  during insertion. A portion of contact rib  62  is designed to be shaved away (by relatively sharp edges of hole  16 ) as the outlet end portion  28  of connector body  20  is inserted into hole  16 . In additional to this alignment feature, contact rib  62  increases electrical conductivity between connector body  20  and electrical box  12 . 
       FIG. 14  is a duplex version of connector assembly  70  for securing a pair of electrical cables  14  to an electrical box  12 . Connector assembly  70  includes connector body  72 , insulator  74 , and duplex spring clip  76 . Similar to single cable spring clip  22 , duplex spring clip  76  engages an electrical box  12  at one end  78  and engages a pair of cables  14  at its other ends. A cable divider  80  is defined by a portion of spring clip  76  and functions to maintain separation between the pair of cables  14 . A pair of cable-engaging spiral indentations  61  is provided in the connector body  72 . 
       FIG. 15  is an exploded perspective view of the connector assembly  70  of  FIG. 14 . Spring clip  76  includes a central portion  82  separating the free spring ends  84 ,  86  from spring end  88 . Spring clip  76  includes spring end  88  having a hook structure including a hook end  90  and a tab  92 . Cable engaging ends  84 ,  86  are adapted to engage cables  14 . A plurality of apertures  94  are formed in the central portion  82  of spring clip  76  through which a plurality of fasteners pass to secure spring clip  76  to connector body  72 . 
     As shown in  FIGS. 14 and 16 , connector body  72  further includes a cavity  96  for engagement with an end of cable divider  80 . Fasteners, shown as a rivets, secure a central portion of spring clip  76  to the planar mount surface of connector body  72 . A variety of different fasteners may be used to secure spring clip  76  to connector body  70 , including but not limited to threaded fasteners, other rivets, etc. 
       FIG. 16  also shows the pair of spiral indentations  61  as being generally parallel and preferably aligned relative to the spiral convolutions on a cable  14  as shown in  FIG. 20 . 
       FIG. 17  is an elevational view of the connector assembly of  FIG. 14 . 
       FIG. 18  is a cross-sectional view of the connector assembly taken along lines  18 - 18  in  FIG. 17 . As shown, the free ends of spring clip  76  are generally aligned above the spiral indentations  61  and the free end of cable divider  80  is received into cavity  96 . 
       FIG. 19  is a top plan view of the connector assembly  70  shown as attached to electrical box  12 .  FIG. 20  is a bottom plan view of the connector assembly of  FIG. 19 .  FIG. 21  is a cross-sectional view of connector assembly  70  taken along lines  21 - 21  in  FIG. 19 . 
       FIG. 22  is a detailed view of a portion of  FIG. 21 . The width of spiral indentation  61  is approximately the same as the peak-to-peak spacing of the spiral convolutions on cable  14 . In other words, only a portion of one spiral convolution engages spiral indentation  61 . 
     Embodiments of connector assemblies of the present invention are designed to secure MC (metal clad cable) or AC (armor clad cable) cables or ⅜″ flexible metal conduit (FMC) to an electrical box or enclosure. The connectors may accept multiple versions of these cables, for example 14/2 or 10/3, which may vary in outer diameter from 0.420″ to 0.600″. The flexible nature of the spring clip and internal guide ribs permit the connector assembly to be utilized across a range of cable diameters. In other embodiments of the present invention, other cable types and size may be utilized. 
     Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.