Patent Publication Number: US-6984790-B1

Title: Insulator sealing and shielding collar assembly

Description:
FIELD OF THE INVENTION 
   The present invention relates to a collar assembly for an insulator. More specifically, the present invention relates to an insulator sealing and shielding collar assembly. Still more particularly, the present invention relates to a collar assembly having two members, and a sealant injectable in one member after both members of the collar assembly have been secured to an insulator. The collar assembly is easily installed, provides a seal for the insulator, and substantially eliminates corona discharge. 
   BACKGROUND OF THE INVENTION 
   Electrical polymer insulators are used in power transmission and distribution systems to provide mechanical support for the conductors and provide electrical insulation between the high voltage conductors and grounded tower structures. A corona protection device is located at the line end and/or the ground end of the insulator and eliminates the corona discharge from the insulator. Elimination of the corona discharge protects the surface of the insulator from polymeric material deterioration caused by electric stress. Additionally, eliminating the corona discharge reduces television and/or radio noise created by the corona discharge. 
   A problem with existing corona protection devices is the number of parts required to assemble the corona protection device, thereby increasing the manufacturing costs. Additionally, more parts must be carried to a job site by an installer, which decreases the speed and efficiency with which the corona protection devices may be installed. Since existing corona protection devices require various parts to completely assemble the device, if one part is lost or missing the device cannot be properly assembled and an installer must make a return trip to finish installation of the corona discharge device. A need then exists for a collar assembly having few parts, thereby reducing manufacturing costs and providing quick installation. 
   Other problems with existing corona protection devices involve poor seals being formed between the corona protection device and the insulator, as well as the corona protection device being poorly secured to the insulator. Poor seals with and connections to the insulators result in a highly ineffective corona protection device, and often results in the corona protection device failing. Thus, a need exists for a collar assembly having a good seal and connection to the insulator. 
   Examples of conventional corona protection devices include U.S. Pat. No. 2,867,682 to Smith et al.; U.S. Pat. No. 3,239,600 to Bethea, Jr.; U.S. Pat. No. 4,198,538 to Lusk; U.S. Pat. No. 5,488,199 to Selsing et al.; U.S. Pat. No. 6,265,669 to Richards; U.S. Pat. No. 6,388,197 to Zhao et al.; the subject matter of each of which is hereby incorporated by reference. 
   A need exists for an improved insulator collar assembly. 
   SUMMARY OF THE INVENTION 
   Accordingly, an object of the present invention is to provide an improved collar assembly for an insulator. 
   Another object of the present invention is to provide a collar assembly that is quickly and easily connected to an insulator. 
   Another further object of the present invention is to provide a collar assembly having fewer parts, thereby reducing manufacturing costs and increasing installation efficiency. 
   Yet another object of the present invention is to provide a collar assembly in which a strong seal and connection are formed between the collar assembly and insulator. 
   The foregoing objects are basically attained by providing a collar assembly for an insulator assembly having first and second members secured together on the insulator assembly. The first member has first and second fastener holes and a first opening. The second member is connected to the first member, and has third and fourth fastener holes aligned with the first and second fastener holes, respectively. A second opening is formed in the second member. The first and second openings are adapted to receive a sealant. A first fastener is inserted through the first and third fastener holes and a second fastener is inserted through the fourth and second fastener holes to secure the first member to the second member on the insulator assembly. 
   The foregoing objects are further attained by providing a method of installing a collar assembly on an insulator assembly. A first member having first and second fastener holes and a first opening is disposed on the insulator assembly. A second member is connected to the first member on the insulator assembly. The second member has third and fourth fastener holes aligned with the first and second fastener holes, respectively, and a second opening. A first fastener is inserted through the second and third fastener holes of the first and second members on the insulator assembly. A second fastener is inserted through the fourth and first fastener holes of the first and second members on the insulator assembly. A sealant is injected through the first opening to fill the cavity formed between inner surfaces of the first and second members and an outer surface of the insulator assembly. The first and second openings are in fluid communication with the cavity. 
   The foregoing objects are also attained by providing an insulator assembly having a rubber housing, a metal fitting and a collar assembly. The rubber housing has a first end. The metal fitting has a first end. The first end of the rubber housing is disposed in the first end of the metal fitting. A collar assembly is disposed over the first ends of the rubber housing and the metal fitting. The collar assembly has an annular rib engaging a groove proximal the first end of the metal fitting and a lip engaging the rubber housing proximal the first end thereof. A cavity is defined by an inner surface of the collar assembly and an outer surface of the metal fitting and the rubber housing between the annular rib and the lip. A sealant is injected through the collar assembly to fill the cavity to create a seal between the collar assembly, the metal fitting and the rubber housing. 
   Other objects, advantages and salient features of the invention will become apparent from the following detailed description, which, taken in conjunction with annexed drawings, discloses a preferred embodiment of the present invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Referring to the drawings that form a part of this disclosure: 
       FIG. 1  is a perspective view of a collar assembly secured to an insulator assembly according to an embodiment of the present invention; 
       FIG. 2  is a perspective view of a first member of a collar assembly of  FIG. 1  disposed on an insulator assembly; 
       FIG. 3  is a perspective view of a collar assembly disposed on an insulator assembly in which a sealant has been injected and a second member of the collar assembly has been removed thereafter; 
       FIG. 4  is a perspective view of a first member of a collar assembly of  FIG. 2 ; 
       FIG. 5  is a perspective view of a second member of a collar assembly of  FIG. 1 ; 
       FIG. 6  is a front perspective view of a first member of a collar assembly; 
       FIG. 7  is a top plan view in cross section of a first member of a collar assembly taken along a longitudinal line through first and second fastener holes of  FIG. 6 ; and 
       FIG. 8  is a front elevational view of the first member of the collar assembly of  FIG. 6 . 
   

   Throughout the drawings, like reference numerals will be understood to refer to like parts, components and structures. 
   DETAILED DESCRIPTION OF THE INVENTION 
   Referring to  FIGS. 1–8 , a collar assembly  31  is provided for an insulator assembly  11 . The collar assembly has first and second members  41  and  51  secured together on the insulator assembly  11 . The first member  41  has first and second fastener holes  43  and  45  and a first opening  47 . The second member  51  is connected to the first member  41 , and has third and fourth fastener holes  53  and  55  aligned with the first and second fastener holes  43  and  45 , respectively. A second opening  57  is formed in the second member  51 . The first and second openings  47  and  57  are adapted to receive a sealant  61 . A first fastener  81  is inserted through the first and third fastener holes  43  and  53  and a second fastener  83  is inserted through the fourth and second fastener holes  55  and  45  to secure the first member  41  to the second member  51  on the insulator assembly  11 . 
   A conventional metal fitting  21  has an opening  27  at a first end  25 , as shown in  FIG. 2 . A groove  23  is disposed in an outer surface  29  of the metal fitting proximal the first end  25 . 
   A conventional rubber housing  13  having a plurality of weathersheds  17  is adapted to be inserted in the opening  27  in the first end  25  of the metal fitting  21 , as shown in  FIG. 2 . A first end  15  of the rubber housing  13  is preferably tapered to facilitate a compression fit with the metal fitting  21 . Preferably, an O-ring (not shown) is disposed on the tapered end of the rubber housing  13  to create a seal between an outer surface  19  of the rubber housing and an inner surface of the metal fitting  21 . 
   The collar assembly  31  is disposed over the interface between the metal fitting  21  and the rubber housing  13 , as shown in  FIGS. 1–3 . The collar assembly  31  is preferably substantially annular, as shown in  FIG. 1 . First and second members  41  and  51  are secured together to form the collar assembly  31 . An aperture  35  in the collar assembly is adapted to receive the insulator assembly  11 . 
   The first member  41 , as shown in  FIGS. 2–4  and  6 – 8 , is preferably substantially arcuate. Preferably, the second member  51  is substantially similar to the first member  41 , as shown in  FIG. 5 . First and second end faces  42  and  44  of the first member are substantially planar and are adapted to abut corresponding third and fourth end faces  52  and  54  of the second member  51 . An inner surface  46  extends between the inner edges of the first and second faces  42  and  44 . An outer surface  48  extends between the outer edges of the first and end second faces  42  and  44 . A first rib  71  extends outwardly from the inner surface  46  between the inner edges of the first and second end faces  42  and  44  of the first member  41 . The first rib  71  is adapted to be received by the groove  23  in the metal fitting, as shown in  FIG. 2 . A first lip  73  extends outwardly from the inner surface  46  between the first and second end faces  42  and  44 . The first lip  73  is adapted to engage the outer surface  19  of the rubber housing  13 , as shown in  FIG. 2 . Preferably, the first lip  73  is flush with an upper portion of the outer surface  48  of the first member, as shown in  FIGS. 6 and 8 . 
   A first fastener hole  43  is disposed in the first end face  42 . Preferably, the first fastener hole  43  is threaded and ends within the first member such that the first fastener hole is inaccessible from the outer surface  48  of the first member, as shown in  FIG. 7 . 
   A second fastener hole  45  is disposed in the second end face  44 . Preferably, the second fastener hole  45  is counter-bored, as shown in  FIG. 7 . The second fastener hole  45  has an opening in the outer surface  48  and in the second end face  44  such that the second fastener hole is accessible with a fastener when the first and second members  41  and  51  are disposed on an insulator assembly. The counter-bore limits insertion of the fastener in the second fastener hole. 
   A first opening  47  in the first member  41  extends from an outer surface  48  to the inner surface  46 , as shown in  FIG. 7 . The first opening  47  is adapted to receive a sealant to fill a cavity  33  formed when the first and second members are connected on an insulator assembly  11 . 
   Preferably, the second member  51  is substantially similar to the first member  41 . Therefore, a description of the second member  51  is omitted. 
   The cavity  33 , as shown in  FIG. 2 , is formed when the first member  41  is connected to the second member  51  with the insulator assembly  11  received therebetween. The cavity  33  is defined by the outer surface  29  of the metal fitting and the outer surface  19  of the rubber housing  13  and the inner surfaces  46  and  56  of the first and second members  41  and  51 . An upper boundary of the cavity  33  is defined by the intersection between the first and second lips  73  and  74  of the first and second members  41  and  51  with the outer surface  19  of the rubber housing  13 . A lower boundary of the cavity  33  is defined by the intersection between the first and second ribs  71  and  73  of the first and second members  41  and  51  with the groove  23  of the metal fitting  21 . Sealant  61  is injected through one of the first and second openings  47  and  57  to fill the cavity, thereby creating a seal between the collar assembly  31 , rubber housing  13  and metal fitting  11 . 
   Preferably, the first and second members  41  and  51  are made of a metal, which is preferably conductive, such as ductile iron or aluminum. Preferably, the sealant  61  is a room temperature or high temperature vulcanizing material. 
   Assembly and Operation 
   Referring to  FIGS. 1–8 , the first and second members  41  and  51  are secured together to form a collar assembly  31  having an aperture therethrough, which is adapted to receive an insulator assembly  11 , as shown in  FIGS. 1–3 . The preferably arcuate first and second members form a substantially donut-shaped (or annular or toroidal) member when secured together having an aperture  35  therethrough. The aperture  35  is adapted to receive the insulator assembly  11 . 
   The first end  15  of the rubber housing  13  is inserted in the open first end  25  of the metal fitting, as shown in  FIG. 2 . A gasket (not shown) may be disposed on a portion of the first end  15  of the rubber housing  13  received within the metal fitting  21  to create a seal therebetween. 
   The first member  41  is disposed on the insulator assembly  11  such that the first rib  71  is received by the groove  23  in the metal fitting  21 . The second member  51  is disposed on the insulator assembly  11  adjacent the first member  41  such that the second rib  72  is received by the groove  23  in the metal fitting. The first end face  42  of the first member  41  abuts the fourth end face  54  of the second member  51 . The second end face  44  of the first member  41  abuts the third end face  52  of the second member  51 . The first and second ribs  71  and  72  form a substantially annular rib received in the circumferential groove  23  in the metal fitting  21 . The first and second lips  73  and  74  form an annular lip encircling the outer surface  19  of the rubber housing  13 . 
   A first fastener  81  is inserted through the second fastener hole  45  in the first member  41  and into the third fastener hole  53  in the second member  51 . Preferably, the third fastener hole  53  is threaded to securely receive the first fastener  81  therein. Preferably, the second fastener hole  45  is counter-bored to limit insertion of the first fastener  81 . 
   A second fastener  83  is inserted through the fourth fastener hole  55  in the second member  51  and into the first fastener hole  43  in the first member  41 . Preferably, the first fastener hole  43  is threaded to securely receive the second fastener  83  therein. Preferably, the fourth fastener hole  55  is counter-bored to limit insertion of the second fastener  83 . The collar assembly  11  is then tightened in place on the insulator assembly  11  with the first and second fasteners  81  and  81  accessed through the second and fourth fastener holes accessible through the outer surfaces  48  and  58  of the first and second members  41  and  51 . 
   Once the first and second members  41  and  51  have been secured on the insulator assembly  11 , sealant  61  may be injected through either the first or second openings  47  and  57  to fill the cavity  33  with the sealant. Preferably, the sealant is injected in the first opening  47  until the sealant emerges from the second opening  57 , which is preferably diametrically opposed to the first opening. The first and second lips  73  and  74  and the first and second ribs  71  and  72  form upper and lower boundaries to prevent passage of the sealant thereby. Disposing a gasket on the outer surface of the rubber housing received within the metal fitting prevents the sealant from leaking into the metal fitting. The collar assembly  11  acts like a mold, thereby creating a seal between the collar assembly  11 , rubber housing  13  and metal fitting  21  once the sealant sets. The assembled corona assembly on the insulator assembly substantially eliminates corona discharge. 
   While a particular embodiment has been chosen to illustrate the invention, it will be understood by those skilled in the art that various changes and modifications may be made therein without departing from the scope of the invention as defined in the appended claims.