Patent Publication Number: US-7708606-B2

Title: Knurled inner sleeve for a cable connector

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This is a continuation patent application of U.S. patent application Ser. No. 12/017,736 filed on Jan. 22, 2008. This application also claims priority under 35 U.S.C. §119(e) to U.S. provisional patent application No. 60/901,771 filed Feb. 16, 2007 which is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to an electrical cable connector and, more particularly, to an inner sleeve for an electrical cable connector for power lines. 
     2. Brief Description of Prior Developments 
     Electrical connectors for connecting power lines are designed to provide reliable connections in power distribution networks. As electric utility operating environments become more severe and demanding, there is an increasing demand to improve the efficiency of the electrical connectors. One method to improve the efficiency of an electrical connector is to reduce the electrical resistance between mating connector components. Improved electrical connector efficiency leads to reduced costs and improved power transmission capabilities. 
     Accordingly, there is a need for an electrical connector having reduced electrical contact resistance. 
     SUMMARY OF THE INVENTION 
     In accordance with one aspect of the invention, an electrical connector assembly is disclosed. The electrical connector assembly includes a connector member, a wedge sleeve, a wedge, and outer sleeve, and an inner sleeve. The connector member has a first end section and a second end section. The wedge sleeve has a general tube shape. The wedge sleeve includes a front end and a rear end. The front end of the wedge sleeve is mounted onto the second end section of the connector member. The wedge is configured to be located between the wedge sleeve and a core member of a cable. The outer sleeve is located around the wedge sleeve. The outer sleeve has a front end which is attached onto the connector member. The inner sleeve is configured to be fitted between the outer sleeve and the cable. An outer surface of the inner sleeve comprises a first knurled area. 
     In accordance with another aspect of the invention, a dead end electrical connector assembly is disclosed. The dead end electrical connector assembly includes a dead end connector member, a wedge sleeve, an outer sleeve, and an inner sleeve. The dead end connector member has a first end section and a second end section. The second end section includes a threaded section. The first end section is adapted to be connected to another member. The wedge sleeve has a general tube shape. The wedge sleeve includes a front end and a rear end. The front end of the wedge sleeve includes a threaded section engaged with the threaded section of the dead end connector member. The outer sleeve is located around the wedge sleeve. The outer sleeve has a front end which is connected to the dead end connector member. The inner sleeve is adjacent the wedge sleeve. The inner sleeve includes raised ridges on an outer surface of the inner sleeve. The raised ridges are in contact with an inner surface of the outer sleeve. 
     In accordance with another aspect of the invention, a splice electrical connector assembly is disclosed. The splice electrical connector assembly includes a middle connector, a first section, a second section, at least one outer sleeve, and at least one inner sleeve. The middle connector member has a first end with a first threaded section and an opposite second end with a second threaded section. The first section includes a first wedge sleeve and a first wedge. The first wedge sleeve has a general tube shape. The first wedge sleeve includes a first end with a threaded section engaged with the first threaded section of the middle connector member. The first wedge is configured to be disposed between the first wedge sleeve and a core member of a first cable. The second section includes a second wedge sleeve and a second wedge. The second wedge sleeve has a general tube shape. The second wedge sleeve includes a first end with a threaded section engaged with the second threaded section of the middle connector member. The second wedge is configured to be disposed between the second wedge sleeve and a core member of a second cable. The at least one outer sleeve is located around the first and/or the second wedge sleeve. The at least one outer sleeve is connected to the middle connector member. The at least one inner sleeve is configured to be fitted between the at least one outer sleeve and the first and/or the second cable. An outer surface of the at least one inner sleeve comprises a first knurled area. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing aspects and other features of the invention are explained in the following description, taken in connection with the accompanying drawings, wherein: 
         FIG. 1  is a perspective view of a connector and cable assembly; 
         FIG. 2  is an exploded view of the connector and cable assembly shown in  FIG. 1 ; 
         FIG. 3  is a cross sectional view of the connector and cable assembly shown in  FIG. 1 ; 
         FIG. 4  is an enlarged cross section view of the inner sleeve shown in  FIG. 3 ; 
         FIG. 5  is a perspective view of the inner sleeve shown in  FIG. 3 ; 
         FIG. 6  is a side view of an outer sleeve and an inner sleeve of the connector of  FIG. 1  located onto the cable during assembly; 
         FIG. 7  is a side view or the cable shown in  FIG. 2  with the wire conductors removed from a length at the end of the core; 
         FIG. 8  is a perspective view of the cable as shown in  FIG. 7  and showing the outer sleeve and inner sleeve of  FIG. 6 ; 
         FIG. 9  is a preassembly view of the members shown in  FIG. 8  and the other members of the connector shown in  FIGS. 2 and 3 ; 
         FIG. 10  is a side view showing the collet housing and wedges initially mounted onto the core of the cable; 
         FIG. 11  is a perspective view of an end of the collet housing, wedges and core shown in  FIG. 10 ; 
         FIG. 12  is a perspective view of the dead end connector member being located against the ends of the wedges shown in  FIG. 11 ; 
         FIG. 13  is a perspective view of the dead end connector member being screwed into the collet housing shown in  FIG. 12 ; 
         FIG. 14  is a side view of the final installed position of the collet housing, wedges and dead end connector member to the cable; 
         FIG. 15  is a side view of the temporary cable tie being removed and the outer sleeve being located to be positioned onto the collet housing and the dead end connector member; and 
         FIG. 16  is a cross sectional view of an electrical splice connector incorporating features of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to  FIG. 1 , there is shown a perspective view of an electrical cable connector assembly  10  incorporating features of the invention. Although the invention will be described with reference to the exemplary embodiments shown in the drawings, it should be understood that the invention can be embodied in many alternate forms of embodiments. In addition, any suitable size, shape or type of elements or materials could be used. 
     The assembly  10  includes a cable  12  and an electrical connector  14 . The connector  14  is a dead end connector adapted to mechanically connect an end of the cable  12  to another member, such as a transmission tower. Referring also to  FIGS. 2 and 3 , the connector  14  generally comprises a dead end connector member  16 , a collet housing  18 , wedges  20  and an outer sleeve  22 . As shown in  FIGS. 2 and 3  the outer sleeve  22  may comprise an integral tap or connection plate  24  for electrically connecting a connector  26  of another cable assembly  28  to the assembly  10 . However, as seen in  FIG. 1 , the connection plate  24  need not be provided. 
     The cable  12  generally comprises a core  15  around which one or more layers (or strands)  17  of conductor wires  19 , such as made of aluminum, are wrapped. The disclosed connector  14  may be used with any suitable power line, such as composite core or steel core power transmission lines for example. 
     The dead end connector member  16  comprises a one-piece metal member, such as steel or aluminum, having an eyelet  34  at a first end section and an opposite second end section  36  with a threaded section  38 . The dead end connector member  16  also comprises a ridge section  40 . The eyelet  34  is adapted to be connected to another member, such as a transmission tower. The collet housing (or wedge sleeve)  18  is preferably a one piece metal member, such as a steel conduit. The collet housing  18  has a general tube shape with an inner channel  42  having a threaded section  44  at a first end and a tapered section  46  extending away from the threaded section  44 . 
     The wedges  20  comprise two wedges each having a general C shaped cross-section. However, in alternate embodiments, more than two wedges could be provided. As another alternate embodiment, only a single wedge might be provided which has slots forming multiple deflectable arms. The outer sides of the wedges are smooth to be able to slide against the inside surface of the tapered section  46 . The inner sides of the wedges are adapted to grip onto the exterior surface of the core  15  of the cable  12 . The wedges  20  may be adapted to contact each other when fully inserted into the collet housing  18 . The wedges  20  have a suitable length, such as about 11 inches in one example, to provide a large contact area with the core  15  to provide a good friction grip which will not come loose at high tensile force, such as about 21 tons. 
     The outer sleeve  22  is made of electrically conductive metal, such as aluminum. The outer sleeve  22  has a general tube shape. The outer sleeve  22  is located around the collet housing  18 . A first end  48  of the outer sleeve  22  is located over the ridge section  40  of the dead end connector member  16  and crimped or compressed onto the ridge section  40  to form a primarily mechanical connection between the outer sleeve  22  and the dead end connector member  16 . A second end  50  of the outer sleeve  22  is located over the wires  19  of the cable  12  and crimped or compressed onto the wires  19  to form a mechanical and electrical connection with the wires  19 . An inner sleeve  52 , which may be a one-piece member fabricated from a conductive material such as aluminum for example, is disposed between the outer sleeve  22  and the cable  12 . 
     The inner sleeve  52  (best illustrated in  FIGS. 4 and 5 ) is a generally tubular component that makes up the difference between the conductor cable  12  and the standard diameter outer sleeve  22  of the connector  14  within a particular “family” or range of conductor sizes. The inner sleeve  52  comprises a hole  53  extending along an entire length of the inner sleeve  52  which is sized and shaped to accommodate the cable  12  therein. The inner sleeve  52  comprises a first knurl area or zone  54  proximate a first end  56  of the inner sleeve  52 . The inner sleeve  52  also comprises a second knurl zone  58  between a middle portion  60  of the inner sleeve  52  and a second end  62  of the inner sleeve  52 . The knurl zones  54 ,  58  comprise a pattern of indentations  64  along outer surfaces of the inner sleeve  52 . The knurl zones  54 ,  58  may be straight lines or diagonal cross-hatch indentations. Additionally, the knurl zones  54 ,  58  may be formed by a process which forces the areas between the indentations  64  outward in a radial manner from the axis of the knurled part, which enlarges the surface area. 
     Knurl zones are generally specified on many machine parts and are used for finger grips on cylindrical nuts and knobs, for holding an insert in a plastic or molded material, or for an interference fit within a mating piece. The disclosed inner sleeve  52  may provide an interference fit between the roughly textured knurled inner sleeve  52  and the outer sleeve  22 . An inner surface  23  of the outer sleeve  22  may comprise a smoother surface than the roughly textured surface (or knurl zone  54 ,  58 ) of the inner sleeve  52 . One advantage to the disclosed knurled inner sleeve  52  is a reduction of electrical contact resistance between the textured inner sleeve  52  and the outer sleeve  22 . The reduction in electrical contact resistance is provided as the electrical contact surfaces between inner sleeve  52  and the outer sleeve  22  is at the knurl zones  54 ,  58 . The knurl zones  54 ,  58  provide for defined areas of contact between the outer surface of the inner sleeve  52  and the inner surface  23  of the outer sleeve  22 . In one embodiment the electrical contact resistance of the interface between the disclosed knurled inner sleeve  52  and the outer sleeve  22  is reduced by a factor of 3, as compared to conventional tube combinations with smooth surfaces. The reduced resistance between the inner sleeve  52  and the outer sleeve  22  provides for overall improved connector  14  efficiency and reduced operating costs. The knurl displaces surface oxides, inhibitor, protective coating (wax) at points of true electrical contact. The knurl also traps pockets of inhibitor creating near water tight seals resulting in improved reliability and long term performance. 
     It should be noted that although the figures illustrate the inner sleeve  52  as having two knurl zones  54 ,  58 , any number of knurl zones may be provided. For example, one continuous knurl zone could be provided, or more than two knurl zones could be provided. Additionally, it should be understood that although the knurl zones  54 ,  58  are described as comprising straight lines or diagonal cross-hatch indentations  64 , any suitable knurl pattern forming raised ridges and/or indentations may be provided. It should also be noted that any dimensions provided in the description are for exemplary purposes only. 
     Referring now also to  FIGS. 6-15 , one method of attaching the connector  14  to the cable  12  will be described. As seen in  FIG. 6 , the inner sleeve  52  is installed or slid over the cable  12 . The outer sleeve  22  is then a slid over the cable  12 . As seen in  FIG. 7 , the strands  17  of the wires  19  are cut to expose a length  68  of the core  15 . The length  68  may be about 12 inches for example. The strands  17  may be cut by any suitable method, such as using a pipe cutter or hacksaw for example. The installer may also install a cable tie to keep the strands together.  FIG. 8  shows the cable and sleeves ready for installation with the rest of the assembly. 
       FIG. 9  shows the connector member  16 , wedges  20 , and collet housing (or wedge sleeve)  18  ready for installation onto the exposed core  15 . As seen in  FIGS. 10 and 11 , the collet housing  18  is located over the exposed end of the core  15  and the wedges  20  are inserted into the collet housing  18  with the exposed core  15  being located between the wedges  20 . In the preferred method, a gap  70  is provided between the rear end  72  of the collet housing  18  and the front end of the wires  19 . When the wedges  20  are inserted between the collet housing  18  and the core  15 , a small portion of the core  15  extends past the front end of the wedges, such as about ¼ inch for example. 
     As seen in  FIG. 12 , the dead end connector member  16  is positioned on the end of the exposed core  15  with the second end  36  located against the front end of the wedges  20 . The collet housing  18  is then pulled or slid towards the dead end connector member  16  as illustrated by arrow  74 . This helps to push the wedges  20  inside the collet housing  18  and readies the assembly for threading of the collet housing  18  to the threaded section  38  of the dead end connector member  16 . As seen in  FIG. 13 , the dead end connector member  16  can be screwed together with the collet housing  18 . A tool can be placed inside the eyelet  34  and a wrench can be attached to the flat sections  76  (see  FIG. 10 ) of the collet housing to rotate the two members  16 ,  18  relative to each other. This tightens the dead end connector member  16  to the collet housing  18  to set the wedges  20 . In a preferred embodiment, the dead end connector member will bottom out at a predetermined distance of the threaded section  38 , such as about 1 inch for example. 
     As seen in  FIG. 14 , with the collet housing  18  threaded onto the dead end connector member  16 , the wedges  20  extend slightly past the rear end of the collet housing  18 . The gap  70  provides a space for the ends of the wedges  20  to move into without encountering interference from the wires  19 . The gap  70  also provides a space for aluminum sleeve compression/expansion of the wires  19  during crimping of the outer sleeve  22  and inner sleeve  52  to the wires. Referring to  FIG. 15 , the cable tie can be cut away from the wires  19 . The outer sleeve  22  and inner sleeve  52  can be slid forward with the outer sleeve  22  stopping against a butt stop on the dead end connector member  16  and the inner sleeve  52  stopping against a stop in the outer sleeve. This places the knurl zones  54 ,  58  in a desired location for contact with the inner surface  23  of the outer sleeve  22 . Referring also to  FIG. 1 , the front end  78  of the outer sleeve  22  can be crimped onto the dead end connector member  16 . The rear end  80  of the outer sleeve  22  can be crimped with the inner sleeve  52  onto the wires  19  of the cable  12 . This completes assembly of the electrical connector  14  with the cable  12 . The outer sleeve  22  provides an electrical connection of the wires  19  to another member. The connector member  16 , collet housing  18  and wedges  20  provide a mechanical connection of the core  15  to another member. 
     Although the figures and discussion have been with respect to a dead end connector, it should be understood that the disclosed knurled inner sleeve  52  may be provided for use in other suitable type of connector. For example, the disclosed inner sleeve  52  may be used with a splice electrical connector as described below. 
     Referring now to  FIG. 16 , a cross sectional view of a splice electrical connector  82  for connecting two of the cables  12 ,  13  to each other is shown. The electrical connector  82  generally comprises a middle connector member  84  having a first end  86  with a first threaded section  88  and an opposite second end  90  with a second threaded section  92 . The electrical connector  82  also comprises a first section  94  and a second section  96 . 
     The first section  94  generally comprises a first collet housing  98  and a first set of wedges  100 . The first collet housing (or first wedge sleeve)  98  has a general tube shape. The first collet housing  98  comprises a first end  102  with a threaded section adapted to be threaded onto the first threaded section  88  of the middle connector member  84 . The first wedges  100  are adapted to be inserted directly between the first collet housing  98  and a core member of a first cable conductor  12 . The first end  86  of the middle connector member  84  is adapted to push the first wedges  100  into the first collet housing  98  as the middle connector member and the first collet housing are threaded with each other. 
     The second section  96  generally comprises a second collet housing  104  and a second set of wedges  106 . The second collet housing (or second wedge sleeve)  104  has a general tube shape. The second collet housing  104  comprises a first end  108  with a threaded section adapted to be threaded onto the second threaded section  92  of the middle connector member  84 . The second wedges  106  are adapted to be inserted directly between the second collet housing  104  and a core member of a second cable conductor  13 . The second end  90  of the middle connector member is adapted to push the second wedges  106  into the second collet housing  104  as the middle connector member and the second collet housing are threaded with each other. The second collet housing  104  and the second set of wedges  106  are identical to the first collet housing  98  and the first set of wedges  100 . However, in alternate embodiments they could be different. 
     As shown in  FIG. 16 , each section  94 ,  96  also comprises an inner sleeve  52 . As illustrated in  FIGS. 4 and 5 , the inner sleeve  52  comprises a first knurl area or zone  54  proximate a first end  56  of the inner sleeve  52 . The inner sleeve  52  also comprises a second knurl zone  58  between a middle portion  60  of the inner sleeve  52  and a second end  62  of the inner sleeve  52 . The splice connector  82  also comprises two outer sleeves  22 ; one at each of the sections  94 ,  96 . The knurl zones  54 ,  58  provide for defined areas of contact between the outer surface of the inner sleeve  52  and the inner surface  23  of the outer sleeve  22 . The inner sleeves  52  disposed within the splice electrical connector  82  provide the same advantages of reduced electrical contact resistance and improved efficiency as described above for the dead end connector  14 . Assembly of the splice connector  82  with the two cables  12 ,  13  and the two inner sleeves  52  is the same as noted above with reference to the dead end connector. The outer sleeves  22  are crimped onto the ridge sections  40  of the middle connector member  84 , and crimped onto the wires of the cables at the inner sleeves  52 . Thus, the two cables are mechanically connected to each other for high tension by the members  84 ,  98 ,  100 ,  104  and  106 , and electrically connected to each other by the outer sleeves  22 , inner sleeves  52  and middle member  84  which could be aluminum. In an alternate embodiment, a single outer sleeve could be provided for both sections  94 ,  96 . 
     It should be understood that the foregoing description is only illustrative of the invention. Various alternatives and modifications can be devised by those skilled in the art without departing from the invention. Accordingly, the invention is intended to embrace all such alternatives, modifications and variances which fall within the scope of the appended claims.