Patent Publication Number: US-7709743-B2

Title: Integrated insulator seal and shield assemblies

Description:
FIELD OF THE INVENTION 
   The present invention relates to a collar assembly for an integrated insulator sealing and shielding assembly. More particularly, the invention represents an integrated insulator sealing and shielding assembly with a rubber housing having a plurality of radial weathersheds and a tapered end adjacent to the endmost radial weathershed. A metal fitting is disposed adjacent to the endmost radial weathershed and receives the tapered end of the rubber housing. A collar assembly surrounds the connection between the metal fitting and the rubber housing. The collar assembly further includes two apertures between an outer surface thereof and the rubber housing for receiving a sealant. There are preferably multiple sealing surfaces disposed between the collar assembly and a bottom end of the rubber housing for securing the connection therebetween. 
   BACKGROUND OF THE INVENTION 
   Electrical polymer insulators are used in power transmission and distribution systems to provide mechanical support for 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 electrical stress. Additionally, eliminating the corona discharge reduces television and/or radio noise created by the corona discharge. 
   One of the problems with conventional corona protection devices is the number of parts required to assemble the corona protection device, thereby increasing the manufacturing costs. Additionally, an installer must transport more parts to a job site, which decreases the speed and efficiency with which the corona protection devices may be installed. Since existing corona protection devices require various parts in order to completely assemble the device, if one part is lost or missing, the device cannot be properly assembled. Thus, 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. Inadequate seals and connections to the insulators result in a highly ineffective corona protection device, often resulting in failure of the corona protection device. 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. 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. 
   Conventional external metal collars clamp down on a cylindrical polymer surface to create a void in the sealing system. Accordingly, a need exists for an improved insulator collar assembly having a metal fitting and a rubber housing forming a compression seal to an external stationary cylindrical metal element. 
   SUMMARY OF THE INVENTION 
   Accordingly, an object of the invention is to provide an improved insulator sealing and shielding assembly. 
   Another object of the invention is to provide an insulator shielding having a collar assembly disposed between a rubber housing and a metal fitting where the collar includes at least one opening for receiving a sealant. 
   A further object of the invention is to provide an insulator shielding with a rubber housing tapered into a metal fitting to increase the compression connection therebetween. 
   Still another object of the invention is to provide an insulator shielding with a plurality of equidistant radial weathersheds disposed along an exterior of the housing and the endmost weathershed adjacent to the collar assembly connected to the hardware. 
   The foregoing objects are basically attained by providing an insulator shielding having a rubber housing with a plurality of weathersheds and a tapered end adjacent the metal fitting. Four sealing surfaces between the counterbore of the collar assembly and the rubber housing secure the connection therebetween creating an integral metal fitting and rubber housing. The collar assembly comprises at least one aperture for receiving a sealant that creates a mold to help secure the connection. 
   By forming the insulator sealing and shielding assembly in this manner, a sealant can be dispensed into one of the apertures until the collar assembly is full of sealant to create a first seal. Three additional sealing surfaces protect the initial seal against moisture ingress and seal the flow channel to effectively bond the rubber housing and metal fitting. 
   As used in this application, the terms “top”, “bottom”, and “side” are intended to facilitate the description of the invention, and are not intended to limit the present invention to any particular orientation. 
   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 drawings that form a part of this disclosure: 
       FIG. 1  is a perspective view of the insulator sealing and shielding assembly according to an embodiment of the present invention; and 
       FIG. 2  is an enlarged perspective view of the end portion of the metal fitting and rubber housing of one end of the insulator sealing and shielding assembly shown in  FIG. 1 ; 
       FIG. 3  is a partial side elevational view in section of the insulator sealing and shielding assembly of  FIGS. 1 and 2 ; and 
       FIG. 4  is a partial elevational view in section of the insulator sealing and shielding assembly of  FIGS. 1-3 , specifically illustrating the four sealing surfaces. 
   

   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. 1-4 , an insulator sealing and shielding assembly  10  includes an annular collar assembly  12  disposed below a tubular rubber or polymer housing  14  with a plurality of weathersheds  16 , and a metal fitting  18  with a collar assembly  12  at each end of the rubber housing  14 . The rubber housing  14  includes a plurality of radial weathersheds  16  evenly disposed about the housing  14  in a columnar arrangement. The extended portion of each metal fitting  18  away from the weathershed housing is disposed on the opposite side of the collar assembly  12  relative to the rubber housing  14 . 
   Ultimately, the rubber housing  14  is adapted to be inserted into and connected to each metal fitting  18  under pressure. Since each metal fitting  18  and collar assembly  12  is identical, only one will be described in detail. 
   The weathersheds  16  are spaced apart equal distances from one another along the body of the insulator assembly  10 . All weathersheds  16  have the same diameter. At the outer edge of the axially endmost weathershed  16 ′, the end  30  of the rubber housing  14  tapers towards the side of the assembly  10  with the metal fitting  18 . The endmost weathershed  16 ′ is adjacent to and abuts the collar assembly  12 , further illustrated in  FIGS. 3 and 4 . 
   The collar assembly  12  surrounds the interface between the metal fitting  18  and the rubber housing  14 , as shown in  FIGS. 2 and 3 . Such collar assemblies are disclosed in U.S. Pat. No. 6,984,790 to Bernstorf, the subject matter of which is hereby incorporated by reference. The present invention creates a similar void by using a concentric cylindrical polymer surface to form compression seals adjacent to an external stationary cylindrical metal part. 
   Turning to  FIG. 2 , the collar assembly  12  has an outer surface  13  with a first aperture  20  and a second aperture  22  for receiving a material injected therein. First aperture  20  is drilled at the widest part of the diameter of the collar assembly  12 , and extends between the endmost extension or outer surface  13  of the collar assembly  12  and the tapered end  30  of the rubber housing  14 . Second aperture  22 , similarly shaped, is disposed on the opposite side of the first aperture  20 , and extends between the outer surface  13  of the collar assembly  12  to the tapered end  30  of the rubber housing  14 . 
   The collar assembly  12  also includes a counterbore  15  that receives the tapered end  30 . The counterbore  15  is a passage extending between the first and second apertures  20 ,  22  and adjacent to the tapered end  30  of the rubber housing  14 . This helps create the connection between the collar assembly  12  and the rubber housing  14 . 
   Each aperture  20 ,  22  makes up the counterbore  15  passing lengthwise along the diameter of the collar assembly  12 . The counterbore  15  is the main opening between the rubber housing  14  and the metal fitting  18 . 
   As seen in  FIGS. 3 and 4 , the tapered end  30  of the rubber housing  14  is coupled to the collar assembly  12  at a narrow junction  40  therebetween. This is the lowermost area of the counterbore  15 . The tapered end  30  is located adjacent, but spaced from, the lowermost point of the counterbore  15  for creating at least one sealing surface with the collar assembly  12 . This junction  40  between the tapered end  30  and the collar assembly  12  represents one of four sealing surfaces securing the assembly  10 . More specifically, the sealing surfaces are disposed between the collar assembly  12  and a bottom end  17  of the rubber housing  14 . Junction  40  helps to create a seal between the outer surface of the rubber housing  14  and the counterbore  15  of the metal fitting  18 . Specifically, the first seal or junction  40  is the joint between the end  38  of the counterbore  15  and the tapered end  30  of the rubber housing  14 . 
   As seen in  FIG. 4 , the second sealing surface  42  is located slightly above the first seal  40 . The second seal  42  is a radial compression seal created by pushing the frustum or first frustum  52  of the rubber housing  14  into the frustum or second frustum  54  of the counterbore  15 . Turning to  FIG. 3 , the counterbore frustum  54  includes first and second walls  56 ,  58  and the rubber housing frustum  52  includes first and second walls  60 ,  62 . The angles  57  between the walls  56 ,  58  of the counterbore&#39;s frustum are larger than the angles  61  between walls  60 ,  62  of the rubber housing  14 , imparting increasing compressing force between the rubber housing  14  and the counterbore  15 . 
   The third sealing surface  44  is located towards the intersection of the second aperture  22  and the rubber housing  14 . This is known as the room temperature vulcanizing (RTV) fill because material is injected into the first aperture  20  between the rubber housing  14  and the collar assembly  12 . Each aperture  20 ,  22  is defined by a perpendicular extension or projection  20 ′,  22 ′, respectively, that extends towards the plurality of weathersheds  16 . These extensions  20 ′,  22 ′ of the apertures  20 ,  22 , respectively connect the apertures  20 ,  22  to the tapered end  30  of the rubber housing  14 . This connection assists in creating a mold because the openings  20 ,  22  and  20 ′,  22 ′ receive the sealant material between the rubber housing  14  and the collar assembly  12  and shape the cast of the sealant material or RTV. RTV is preferred material because it bonds to silicone rubber and metals. 
   The material injected is a sealant which may be either a room temperature or high temperature vulcanizing material. Sealant is pumped into the fitting at the first aperture  20  until enough sealant is disposed or stored in both the first aperture  20  and the second aperture  22  and sealant overflows. When the maximum limit of sealant has been reached, excess sealant begins to emerge and overflows from the opposite aperture  22  so the installer knows a sealed fit has been formed within the interior of the metal fitting  18 , thus creating the third sealing surface  44 . 
   The fourth sealing surface  46  is located towards the top of the collar assembly  12  at the junction of the rubber housing  14  and the outer portion  64  of the counterbore  15 . This sealing surface  46  is the lip seal defined by the intersection of a raised rib  50  on the rubber housing  14  and the outer portion of the counterbore  15  to provide an initial seal against moisture ingress. It also seals the flow channel to keep the RTV adjacent to the rubber housing  14  until it cures. The raised rib  50  is the lowermost extension of the rubber housing  14  on the side of the endmost weathershed  16 ′ adjacent the collar assembly  12 . 
   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 can be made therein without departing from the scope of the invention as defined in the appended claims.