Patent Publication Number: US-6663431-B1

Title: Shielding in a power connector

Description:
BACKGROUND OF THE INVENTION 
     The present invention is related to providing shielding in an electrical connector, and is more particularly related to providing shielding in a power connector to provide for Electromagnetic Compatibility (EMC). 
     U.S. Pat. No. 5,647,765 issued Jul. 15, 1997 to Haas et al. For SHIELDED CONNECTOR WITH CONDUCTIVE GASKET INTERFACE and U.S. Pat. No. 5,735,712 issued Apr. 7, 1998 to Haas et al. for SHIELDED CONNECTOR CONDUCTIVE GASKET INTERFACE disclose a connector with a stamped metallic shield. About the edge of the face of the connector is an electrically conductive compliant member, the conductive member secured to the shield by a plurality of metallic hooks. When the assembly is mounted in place on a metal panel, the conductive compliant member makes electrical contact with the panel, and simultaneously makes electrical contact with the shield. 
     U.S. Pat. No. 5,112,251 issued May 12, 1992 to Cesar for ELECTRICAL CONNECTOR FOR CONNECTING A SHIELDED MULTICONDUCTOR CABLE TO AN ELECTRICAL ASSEMBLY LOCATED INSIDE A CHASSIS discloses a connector with electrically conductive sheets disposed in the inner space between the two insulating covers. The conductive sheets have a flexible part with an end portion for cooperating with the housing panel. 
     U.S. Pat. No. 5,035,651 issued Jul. 30, 1991 to Dixon et al. for MINIATURE CIRCULAR DIN CONNECTOR discloses a housing constructed to receive a conductive internal shield. An embodiment is disclosed having an internal shield with shield extensions. The extensions abut and electrically contact a conducting grounding chassis panel. 
     U.S. Pat. No. 4,889,497 issued Dec. 26, 1989 to Riches for SHIELDED ELECTRICAL CONNECTOR discloses a shielded connector assembly with an elastomeric conductive seal on the leading edge of a housing. The seal makes up any unevenness of fit between the housing and the cooperating connector in a second housing or in a metal panel. 
     U.S. Pat. No. 4,296,390 issued Oct. 21, 1981 to Vanderhayden et al. for SOLDERLESS FILTER MOUNTING FOR HEADER ASSEMBLIES discloses a conductive rubber gasket to assure electrical contact between filter pins and a ground plane. 
     U.S. Pat. Nos. 5,204,496; 5,246,387; 5,288,248; 5,317,105; 6,010,365; 6,093,058; 6,149,444; and 6,234,841 disclose examples of front-mounted metal members used to electrically connect a connector housing to a panel. 
     SUMMARY OF THE INVENTION 
     The present invention provides a method of grounding an internal shield of a plastic power connector to provide an EMC effective perimeter ground path. This is done by attaching a conductive foam gasket material to the exterior, front surface of the backshell of the connector that will be in electrical contact with the inner shield. The conductive foam gasket allows electrical contact between the mounting panel and the inner shield for varying distances between the backshell and the mounting panel and it will also accommodate irregular geometries in the panel face. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other objects will be apparent to one skilled in the art from the following detailed description of the invention taken in conjunction with the accompanying drawings in which: 
     FIG. 1 is a top view of a plastic power connector with the cover removed, the connector having shielding of the present invention; 
     FIG. 2 is a right hand edge view of the power connector of FIG. 1; 
     FIG. 3 is a bottom view of the connector of FIG. 1; and 
     FIG. 4 is a view of another configuration of the connector of FIG. 1 plugged into the front panel of a cabinet wherein the shield of the present invention is electrically connected to the front panel to provide EMC grounding. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT: 
     FIG. 1 is a top view of a connector  10  of the present invention and includes a plastic power connector core (referred further herein as the plastic connector  12 ) surrounded by a metal backshell  14 . The backshell  14  is made up of a top half  16 , a bottom half  18  which are fitted together around the plastic connector  12  and held together by a pair of clips  20  and  21 . The clips  20  and  21  are electrically connected by one or the other of the halfs  16  or  18  by dimples  23  and  24  (see FIG.  2 ). The clip  20  has tabs  30 A and  30 B, and the clip  21  has tabs  32 A and  32 B which are bent around the halts  16  and  18  to hold them together to form the backshell  14 . It will be understood that the halfs  16  and  18 , and the clips  20  and  21 , respectively, are identical to simplify construction of the backshell  14 . 
     The finger end  35  of the plastic connector  12  extends out of the front end  40  of the backshell  14  to be mated with connector receptacle in, for instance, a cabinet to supply electrical power to components within the cabinet. It will be understood that the finger end  35  of the plastic connector  12  includes electrical contacts which are connected to electrical conductors  53  in the power cord  50 . The contacts in the plastic connector  12  will come into electrical contact with contacts in the receptacle  75  of FIG. 4 when the connector  10  is seated into the receptacle  75 , as well understood by those of ordinary skill in the art. The back  42  of the backshell  14  has an opening  43  for an electrical power cable in an inline design (for instance, shown in FIG.  4 ), or openings  44  and  45  for either a right right-angle connection (shown in FIGS. 1-3) or a left right-angle connection of the power cord. 
     The power cord  50  includes an elastomeric covering  51 , a shield layer  52  made, for instance, of a metal braid, and a plurality of cables  53  for supplying electrical power to the connector  12 . The braid is welded or soldered to the top and bottom halfs  16  and  18  at  55  and  56 , respectively, to make an electrical connection from the shield layer  52  of the power cord  50  to the backshell  14 . The power cable  50  is connected to the backshell  14  by a strain relief member  58 . 
     The plastic connector  12  includes a latch mechanism  60  connected on one side, for example the bottom side, to latch the connector into place when the power connection is made. The latch  60  does not form part of the present invention so the details of the latch are not shown or explained further. 
     An Electromagnetic Interference (EMI) gasket  65  is placed around the plastic connector  12  for making electrical connection between the backshell  14  and, for instance, a cabinet when the connector  10  is plugged into a receptacle. The gasket  65  has a reduced portion  66  which is placed between the backshell  14  members and the plastic connector  12 , and an enlarged portion  68  which extends past beyond the backshell  14  and covers the plastic connector  12 . The enlarged portion  68  has a lip  69  on the outside face which stiffens the enlarged portion  68 . 
     The gasket  65  is, preferably, a conductive fabric clad open-celled polyether polyurethane foam in a high resiliency formula having minimal compression set characteristics. One preferred EMI shielding gasket material is available from Schlegel, Inc. 1555 Jefferson Road, Rochester, N.Y. 14623. The reduced portion  66  is adhesively secured to the plastic connector  12  before the backshell  14  is assembled over the plastic connector  12 . It will be understood that the adhesive is not required to be conductive since electrical connection between the backshell  14  and the gasket is made when the halves  16  and  18  are placed over the connector  12  and the tabs  30 A,  30 B,  32 A, and  32 B are folded over the reduced portions  66 . If desired, the gasket  65  may be cut into pieces to fit on each side of the latch  60 , as shown in FIG.  3 . 
     FIG. 4 is a diagram of another preferred power connector  10  connected to a receptacle in a panel  70  of a cabinet  72 . The receptacle may be the same as the receptacles  75  designed to mate with the plastic connector  12 . The connector  10  of FIG. 4 is an inline connector with the power cord  50  connected in the opening  43  of the backshell  14 , as previously discussed. When the connector  10  is seated in the receptacle  75 , the gasket  65  is pushed tightly into electrical contact with the panel  70 . The lip  69  stiffens the gasket  65  to keep the gasket  65  in tight engagement with the panel face, to make good electrical contact between the gasket  65  and the panel  70 , to accommodate varying distances between the backshell  14  and the mounting panel  70 , and to accommodate irregular geometries in the panel face. 
     While the preferred embodiment of the invention has been illustrated and described herein, it is to be understood that the invention is not limited to the precise construction herein disclosed, and the right is reserved to all changes and modifications coming within the scope of the invention as defined in the appended claims.