Patent Publication Number: US-7210947-B1

Title: Cable harness system, ground clips and method for electrically grounding a conductor of the cable harness system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   None 
   BACKGROUND OF THE INVENTION 
   The present invention generally relates to electrically grounded connectors, and more specifically, to a cable harness system, ground clips and a method for electrically grounding a conductor of the cable harness system. 
   Electric power systems are designed to generate, transmit and distribute electrical energy to loads. In order to accomplish this, power systems generally include a variety of power system elements such as electrical generators, electrical motors, power transformers, power transmission lines, buses and capacitors, to name a few. As a result, power systems typically include protective devices and associated procedures to protect the power system elements from abnormal conditions such as electrical short circuits, overloads, frequency excursions, voltage fluctuations, and the like. 
   Electric power systems also require communication and computer networks. For example, Supervisory Control and Data Acquisition (SCADA) systems are included to measure the voltages associated with a power system substation bus (i.e., bus voltages), to measure the current coming into the bus from a power transmission line (i.e., a line current), and to measure the status or position of numerous switches in the substation. The status measurements may include indications of circuit breaker positions and electrical power routing switch positions (e.g., open position, closed position). The SCADA system may also be configured to transmit the current, voltage and switch position measurements to a central control center (CC) via a SCADA communication network for review by an operator. The operator can then make decisions such as closing a circuit breaker to enable additional electric power to a particular load. In that case, a command from the operator delivered via the SCADA communication network results in closure of the circuit breaker. 
   Such communication and computer networks include the use of cabling, connectors and associated grounding methods. As a result, equipment manufacturers in the power system industry are engaged in manufacturing the cable/connector assemblies supporting the communication and computer networks. One typical method for manufacturing and connecting a cable having a number of conductors (e.g., a multi-conductor cable used with a DB-9 connector) includes stripping and soldering one of the cable conductors, designated as a ground wire, directly to a conductive shell, or body, of an associated connector. Besides being somewhat labor intensive, electrical grounding via use of a solder connection to the connector shell limits the type of conductor shells that can be used. Alternatively, another method for grounding a cable having a number of conductors includes use of metal backshells configured to provide grounding from the wire to the case. Unfortunately, such metal backshells are expensive and often labor intensive and complicated to assemble. 
   SUMMARY OF THE INVENTION 
   In accordance with an aspect of the invention, a cable harness system includes a cable having a number of individual conductors, and a connector to enable conductive coupling of the cable to a device. The connector includes an electrically conductive connector body configured for attachment to a chassis of the device. The cable harness system also includes a ground clip to facilitate an electrical ground path between one of the individual conductors and the chassis of the device. The ground clip includes a first portion configured for conductive coupling (e.g., a connection barrel having a bore formed therein) to the conductor, and a second portion configured for conductive contact (e.g., a contact flange) with the connector body. 
   In accordance with another aspect of the invention, a ground clip facilitates an electrical ground path between a conductor of a number of individual conductors of a cable and an electrically conductive connector body of a connector. The connector body is attached to a chassis of a device. The ground clip includes a first portion configured to conductively couple to the conductor, and a second portion configured to conductively contact with the connector body. The ground clip may be configured as a ground clip lug captured by a captive screw member compressively securing the ground clip lug against the connector body. The ground clip may also be a ground clip bracket configured for frictional engagement with the connector body. 
   In accordance with a further aspect of the invention, a method facilitates an electrical ground path between a conductor of a number of individual conductors of a cable and an electrically conductive connector body of a connector. The connector body is attached to a chassis of a device. The method includes conductively coupling the conductor to a ground clip via a first portion of the ground clip, and conductively connecting the second portion of the ground clip to the connector body. The method also includes securing the ground clip against the connector body. 
   It should be understood that the present invention includes a number of different aspects and/or features which may have utility alone and/or in combination with other aspects or features. Accordingly, this summary is not an exhaustive identification of each such aspect or feature that is now or may hereafter be claimed, but represents an overview of certain aspects of the present invention to assist in understanding the more detailed description that follows. The scope of the invention is not limited to the specific embodiments described below, but is set forth in the claims now or hereafter filed. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an exploded view of a typical cable harness system including a cable that is electrically grounded via a solder joint between an individual conductor of the cable and a grounded electrically conductive connector body. 
       FIG. 2A  is a perspective view of a cable harness system including a cable grounded via a connector contact conductively connecting an individual conductor of the cable to a conductive ground clip lug, according to an embodiment of the invention. 
       FIG. 2B  is an exploded perspective view of the cable harness system of  FIG. 2A , according to an embodiment of the invention. 
       FIG. 3A  is a detailed exploded view showing the connector contact conductively connecting the individual conductor to the ground clip lug of the cable harness system of  FIGS. 2A and 2B . 
       FIG. 3B  is detailed exploded view showing the individual conductor directly connected to the ground clip lug, according to another embodiment of the invention. 
       FIG. 4  is an exploded perspective view of another cable harness system including a cable grounded via a connector contact conductively connecting an individual conductor of the cable to a conductive ground clip bracket, according to an embodiment of the invention. 
       FIG. 5A  is a perspective view of the ground clip bracket of  FIG. 4 . 
       FIG. 5B  is a front view of the ground clip bracket of  FIG. 4 . 
       FIG. 5C  is a perspective view of another embodiment of the ground clip bracket of  FIG. 4 . 
       FIG. 6  is an exploded perspective view of yet another cable harness system including a cable grounded via a printed circuit board conductively connecting an individual conductor of the cable to the ground clip bracket, according to an embodiment of the invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  is an exploded view of a typical cable harness system  10   a  including a cable  20  that is electrically grounded via a solder joint  28  between an individual conductor  26  of the cable and a grounded conductive connector body  56  of a connector  50 . The cable  20  includes a number of individual conductors  22 . One of the individual conductors, illustrated as conductor  24 , is partially stripped of its insulation to expose its conductive material (e.g., wire). The remaining conductors  22  are fitted with respective conductor contacts  30  to enable easy insertion into connector contact holes  40  of the connector  50 . 
   In addition to the cable  20 , the typical cable harness system  10   a  includes a backshell  52  configured to house an extending portion of the connector  50  that includes the connector contact holes  40 . An opening in the backshell  52  accommodates placement of the cable  20  when the conductor contacts  30  are inserted into respective connector contact holes  40 . Although only a bottom portion is shown, it should be understood that the backshell  52  includes a corresponding top portion. 
   The conductive connector body  56  includes a connector flange  58  having dual device attachment holes  54  formed therein. The dual device attachment holes  54  in the connector flange are positioned to enable alignment and retainment of the connector  50  to its corresponding connection mate  62  on a device chassis  60 . 
   In the illustrated example, a captive screw member  36 , also know as a jackscrew, is inserted through a respective dual device attachment hole  54  and then screwed into a corresponding threaded nut  64  on the device chassis  60 , thereby compressively securing the connector  50  to the device chassis  60 . The cable  20  is therefore electrically grounded via the solder joint  28  between the stripped conductor  26  in contact with the conductive connector body  56  secured to the device chassis  60 . While providing an effective electrical ground path, construction of the solder joint is labor intensive and time consuming. In addition, the step of constructing the solder joint may not fit well within an associated manufacturing process. 
     FIG. 2A  is a perspective view of a cable harness system  10   b  including the cable  20  grounded via the connector contact  32  conductively coupling an individual conductor  24  to a conductive ground clip lug  70 , according to an embodiment of the invention.  FIG. 2B  is an exploded perspective view of the cable harness system  10   b  of  2 A. The ground clip lug  70  facilitates electrical grounding of the cable  20  without the solder joint  28  of  FIG. 1 . Although illustrated using a DB9 connector and associated cable, it is contemplated that the ground clip lug  70  may be used with other connectors and cables. 
   Referring to  FIGS. 2A and 2B , the ground clip lug  70  includes a first portion configured for electrically conductive coupling to the conductor  24 , and a second portion configured for electrically conductive contact with the conductive connector body  56 . Although preferably connected via a crimped connection, the conductor  24  may also be connected to the first portion of the ground clip lug  70  via a soldered connection. 
     FIG. 3A  is a detailed exploded view showing the connector contact  32  conductively coupling the conductor  26  to the ground clip lug  70  of  FIGS. 2A and 2B . Referring to  FIG. 3A  the first portion of the ground clip lug  70  includes a connection barrel  72  having a bore  78  formed therein. The bore  78  is sized to receive the connector contact  32 . The second portion of the ground clip lug  70  includes a contact member, in the illustrated example, a contact flange  74  having a flange opening  76  formed therein. The flange opening  76  is preferably sized and threaded to receive the captive screw member  36 . 
   The conductor  26  is conductively connected to a first end of the connector contact  32  using a solder connection or a crimped connection. A second end of the connector contact  32 , which may be configured as a male or female contact, is preferably held within the bore  78  via a friction fit. The second end of the connector contact  32  may also be held within the bore  78  via a solder connection or a crimped connection. 
   In some cases, it may be advantageous to insert the conductor  26  directly into the bore  78 .  FIG. 3B  is detailed exploded view illustrating the conductor  26  directly connected to the ground clip lug  70 , according to another embodiment of the invention. Although preferably held within the bore  78  via a crimped connection, the conductor  26  may be held via a soldered connection. 
     FIG. 4  is an exploded perspective view of another cable harness system  10   c  including the cable  20  grounded via the connector contact  32  conductively connecting the conductor  24  to a conductive ground clip bracket  80   a , according to an embodiment of the invention. The ground clip bracket  80   a  facilitates electrical grounding of the cable  20  without the solder joint  28  of  FIG. 1 . Although illustrated using a DB9 connector and associated cable, it is contemplated that the ground clip bracket  80   a  may be used with other connectors and cables. 
   The ground clip bracket  80   a  includes a first portion configured for electrically conductive coupling to the conductor  24 , and a second portion configured for electrically conductive contact with the conductive connector body  56 . Although preferably connected via a connector contact  32 , a crimped connection, the conductor  24  may also be connected to the first portion of the ground clip bracket  80   a  via a soldered connection. 
     FIG. 5A  is a perspective view of the ground clip bracket  80   a  of  FIG. 4 . Referring to  FIG. 5A  the first portion of the ground clip bracket  80   a  includes a connection barrel  82   a  having a bore  92   a  formed therein. The connection barrel  82   a  is substantially similarly configured and operable as described in connection with the connection barrel  72  of  FIGS. 3A and 3B . The bore  92   a  is sized to receive either the connector contact  32  or the conductor  24  as described in connection with  FIGS. 3A and 3B . The second portion of the ground clip bracket  80   a  includes a contact member, in this case, a pair of arms  84  extending from opposing edges of a bracket base  81 . As illustrated, the connection barrel  82   a  is preferably disposed on an edge of one of the pair of extending arms  84 , proximate to an end, to facilitate receipt of either the conductor  26  or the connector  32 . 
   The bracket base  81  includes an opening  90  formed therein to accommodate insertion of an extending portion of the connector  50 . Each of the pair of arms  84  is inclined towards the other arm to frictionally engage the extending portion of the connector  50  in order to enable electrical grounding of the cable when the connector body  56  is conductively attached to the device chassis  60 . Optionally included in the bracket base  81  is a pair of apertures  86 ,  88  configured to permit used of a corresponding pair of captive screw members  36  to compressively secure the connector body  56  against the device chassis  60 . 
     FIG. 5B  is a front view of the ground clip bracket  80   a .  FIG. 5C  is a perspective view of another embodiment of a ground clip bracket  80   b  where the connection barrel, in this case connection barrel  82   b , is disposed proximate to another end of the edge of one of the pair of extending arms  84 . Although two configurations of the ground clip bracket are shown, it is contemplated that other configurations may be used to provide a “solderless” ground path. 
   In some applications, it may be desirable to utilize a printed circuit board in the cable harness. Such applications may include cables used in signal processing applications such as those that adapt between communication standards.  FIG. 6  is an exploded perspective view of yet another cable harness system  10   d  including the cable  20  grounded via a printed circuit board  94  conductively coupling the conductor  26  to the ground clip bracket  80   b , according to a further embodiment of the invention. Although illustrated using the ground clip bracket  80   b , it is contemplated that other configuration of ground clips may also be used. The printed circuit board  94  includes a first terminal  98  configured to conductively connect to the conductor  26 , and a second terminal  96  configured for insertion into the bore  92   b  of the connection barrel  82   b . The first and second terminals  98 ,  96  are conductively coupled such that when the conductor  26  is connected to the first terminal  98 , it is electrically grounded via the second terminal  96  and the connector body  56  to the device chassis  60 . The second terminal is connected to the ground clip using one of a soldered connection, a crimped connection and a friction fit connection. 
   While this invention has been described with reference to certain illustrative aspects, it will be understood that this description shall not be construed in a limiting sense. Rather, various changes and modifications can be made to the illustrative embodiments without departing from the true spirit, central characteristics and scope of the invention, including those combinations of features that are individually disclosed or claimed herein. Furthermore, it will be appreciated that any such changes and modifications will be recognized by those skilled in the art as an equivalent to one or more elements of the following claims, and shall be covered by such claims to the fullest extent permitted by law.