Abstract:
A connector assembly including a connector body with a spring clip including a first free end for engaging an electrical cable received within the connector body and a second free end for engaging a side wall of an electrical box upon installation. During insertion of the connector body the second 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. A method of manufacturing a connector assembly via an orbital riveting process is also provided.

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. The spring steel collars typically have tangs protruding from their outer circumference. Snap-fit connectors may also have spring steel cable retainers which are fastened to the connector body via a rivet or other fastener. The rivet or other fastener are separate elements requiring additional manufacturing steps to fabricate the connector assembly. 
     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 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 to hold the connector assembly onto the electrical box. 
     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. 
     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. 
     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 incorporation of a boss into the connector body which captures the spring clip during an orbital riveting process. In this manner separate fasteners are no longer required and fabrication times can be decreased. 
     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. 
         FIGS. 4A-B  are cross sectional views of the electrical connector assembly of  FIG. 1 . 
         FIG. 5  is a perspective view of the electrical connector assembly of  FIG. 1  as being attached to an electrical junction box. 
         FIG. 6  is a top plan view of a blank of the electrical connector assembly of  FIG. 5  upon attachment. 
         FIG. 7  is a perspective view of the connector body of  FIG. 1 . 
         FIG. 8  depicts a manufacturing process by which the connector body is secured to the spring clip element via an orbital riveting process. 
         FIG. 9  is a perspective view of a second embodiment of an electrical connector of the present invention. 
         FIG. 10  is a perspective view of the spring clip of the connector of  FIG. 9 . 
         FIG. 11  is a perspective view of the connector body of the connector of  FIG. 9 . 
         FIG. 12  is a perspective view of the electrical connector assembly of  FIG. 9  in a disassembled form. 
         FIG. 13  is a perspective view of the connector of  FIG. 9  as being attached to an electrical box. 
         FIG. 14  is a cross-sectional view of the connector and electrical box of  FIG. 13 . 
         FIG. 15  is a cross-sectional view of the connector and electrical box of  FIG. 13 . 
         FIG. 16  is a top plan view of the connector and electrical box of  FIG. 13  upon attachment. 
     
    
    
     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 electric 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. 
     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. The head of rivet  42  is shown in a deformed state, such as after an orbital riveting process described hereinafter. 
     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. 
     The connector assembly  10  is especially useful for securing MC (metal clad) or armored cable to a panel or electrical box. MC or armored cables include a convoluted outer surface consisting of peaks and grooves such as shown in  FIGS. 4A-B . 
     As shown in  FIG. 4A , 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 . Again, insertion of cable  14  into the connector body  20  is limited by the insulator  24  held at the outlet end portion  28 . 
       FIG. 4A  is a cross-sectional view of connector assembly  10  shown as connected to electrical box  12 . 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 . As shown in  FIG. 4 , insulator  24  additionally functions as a cable stop to limit further introduction of cable  14  into electrical box  12 , as an outer covering of cable  14  engages portions of insulator  24  around a central bore. 
       FIG. 4B  is a cross-sectional view of connector assembly  10  shown as connected to electrical box  12  and a larger cable  14 , and illustrates the deflection of the spring clip  22  internally and the connector assembly&#39;s ability to accommodate a range of 0.420″ to 0.600″ diameter MC/AC cables. Together  FIGS. 4A-B  illustrate the relatively wide range of cable diameters suitable for use with the connector assembly  10  of the present invention 
       FIG. 5  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. 6 , spring clip  22  retracts and engages inner and outer surfaces of the electrical box  12 . 
       FIG. 5  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. 6  is a top plan view of the connector assembly  10  shown as connected to electrical box  12 . Electrical continuity is established by contact of spring end  52  at hook end  56 , tab  58 , wing portions  60 , and contact of body  20 , lug  45 , and ribs  62 . 
     The spring clip  22  is preferably constructed of spring steel which has a zinc or other metallic coating like tin, silver or copper, making it highly electrically conductive. In one embodiment, coating thickness is approximately 50 mils. Tests have shown that such conductive coatings on spring elements of prior art connector assemblies can reduced contact resistance over 25% as compared to uncoated spring elements. Constructing the connector body  20  of zinc alloy or other corrosion resistant alloys and the spring clip  22  of spring steel enables the connector assembly  10  to establish electrical continuity between the metallic-sheathed cable or conduit and the panel or electrical box to which it is attached. 
       FIG. 7  is a perspective view of connector body  20  showing boss  64  extending from planar surface  38  of bridge portion  32 . Boss  64  is cast-in-place and thus integral to the connector body  20 . Unitary boss  64  is generally cylindrical with a slight taper. Other shapes may be practicable. The diameter of boss  64  is slightly less than the diameter of the aperture in the spring clip  22 . Boss  64  is deformed via an orbital riveting process to securely fasten spring clip  22  to connector body  20 . 
       FIG. 8  depicts an orbital riveting process by which spring clip  22  is secured to connector body  20 . Orbital riveting is a cold-forming process used to join materials together. The orbital riveting process uses an orbital head  65  and forming tool  66  mounted, for example, at a 3 or 6° angle. The forming tool  66  engages boss  64  and then presses it while rotating to gradually form the material of boss  64  into a head that holds the assembly together. Importantly, without the need for a separate rivet or fastener, the time of the fabrication is dramatically decreased. Unlike conventional riveting, it is straightforward to quickly join materials. Unlike the use of separate threaded fasteners, there is no required drilling and/or tapping of the connector body. Unlike traditional stamped rivets or fasteners, there is no requirement for external support to resist relatively high deforming forces. 
       FIG. 9  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 the spring clip  22  of  FIGS. 1 through 6 , modified 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  76  and functions to maintain separation between the pair of cables  14 . 
     Spring  76  is illustrated in  FIG. 10  and includes a central portion  82  separating the free spring ends. Spring clip  76  includes first spring end  78  having a hook structure including a hook end  84  and a tab  86 . Cable engaging ends  88 ,  90  are adapted to engage cables  14 . A plurality of apertures  92  are formed in the central portion of spring clip  76  through which a plurality of fasteners  42  pass to secure spring clip  76  to connector body  72 . 
     As shown in  FIG. 11 , connector body  72  includes alignment ribs  94  which tend to center the electrical cables  14  within the connector body  72 . As the electrical cables  14  are inserted into the connector body  72 , ribs  94  engage the cables and tend to align and center the cables  14  within the connector body  72 . Ribs  94  provide further electrical continuity between connector  70  and electrical cables  14 . The connector assembly  10  of  FIGS. 1  though  6  also includes alignment ribs. 
     Connector body  72  further includes a cavity  96  for engagement with an end of cable divider  80 . Connector body  72  includes a bridge portion  100  defined between a pair of open portions  102 ,  104 . Bridge portion  100  includes a generally planar mount surface. Fasteners, shown as a rivets  42 , secure a central portion of spring clip  76  to the planar mount surface. A variety of different fasteners may be used to secure spring clip  76  to connector body  70 , including but not limited to threaded fasteners, rivets, etc. 
       FIG. 12  depicts the connector assembly of  FIG. 9  in an exploded, disassembled view. As shown, the free end of cable divider  80  is received into cavity  96 . 
       FIG. 13  depicts insertion of connector assembly  70  into electrical box  12 . Spring end  78  is shown engaging an upper edge of hole  16 . As spring end  78  is further inserted, spring end  78  initially deflects toward insulator  74  prior to engaging inner and outer surfaces of electrical box as shown in  FIG. 13 . 
       FIGS. 14 and 15  are cross-sectional views of the connector assembly  70  as secured to electrical box  12 .  FIG. 14  illustrates a cross-sectional view taken through spring end  86 .  FIG. 15  illustrates a cross-sectional view taken through cable divider  80 . As shown in  FIG. 15 , the free end of cable divider  80  is retained within cavity  96 , which in this embodiment is an aperture in connector body  72 . Ends of cable  14  engage an inner surface of connector body  72  to limit further introduction of cables into the assembly. In this embodiment, insulator  24  does not necessarily function as a cable stop. 
       FIG. 16  is a top plan view of the connector assembly  70  shown as attached to electrical box  12 . Witness holes  106  are provided through which visual inspection of the cable  14  end may be made. 
     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.