Abstract:
An insulator for an electric fence of the type having posts, electric wire, and insulators mounted on the posts for supporting the wire, the insulator including a body portion having a closed end opposite an open end to define a blind bore having a substantially continuous sidewall; a support extending from the body for supporting the wire, and a plurality of ribs radially disposed within the blind bore and extending away from the sidewall toward a central portion of the bore.

Description:
FIELD OF THE INVENTION 
     This invention relates generally to insulators for electric fences. More particularly, this invention relates to insulators mountable on a post for supporting conductors of an electric fence. 
     BACKGROUND AND SUMMARY OF THE INVENTION 
     Electric fences typically include posts, electric wire, and insulators mounted on the posts for supporting the wire. Improvements are needed in the construction of insulators. 
     The invention relates to an insulator for an electric fence of the type having posts, electric wire, and insulators mounted on the posts. 
     In a preferred embodiment, the insulator includes a body portion having a closed end opposite an open end to define a blind bore having a substantially continuous sidewall; a support extending from the body for supporting the wire, and a plurality of ribs radially disposed within the blind bore and extending away from the sidewall toward a central portion of the bore. 
     Each rib preferably has an angled profile defined by a first sector and a second sector, with the first sector located nearer the open end of the bore than the second sector. The first sector has a first post contact edge disposed at a first angle relative to a plane perpendicular to a centerline of the blind bore. The second sector has a second post contact edge disposed at a second angle relative to a plane perpendicular the centerline of the blind bore. The first angle is preferably greater than the second angle. 
     The invention advantageously provides an insulator that is readily and securely mountable to a round support post and which covers the exposed end of the support post. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further features of preferred embodiments of the invention will become apparent by reference to the detailed description of preferred embodiments when considered in conjunction with the figures, which are not to scale, wherein like reference numbers, indicate like elements through the several views, and wherein, 
     FIG. 1 is a front perspective view of an insulator in accordance with a preferred embodiment of the invention installed on a post and supporting a wire. 
     FIG. 2 is a front perspective view of the insulator of FIG.  1 . 
     FIG. 3 is a bottom perspective view of the insulator of FIG.  2 . 
     FIG. 4 is a bottom plan view of the insulator of FIG.  2 . 
     FIG. 5 is a top plan view of the insulator of FIG.  2 . 
     FIG. 6 is a cross-sectional side view taken along line  6 — 6  of FIG.  5 . 
     FIG. 7 is a cross-sectional view of the insulator of FIG. 2 showing preferred dimensions. 
     FIG. 8 is a cross-sectional side view of an insulator in accordance with an alternative embodiment. 
    
    
     DETAILED DESCRIPTION 
     With initial reference to FIG. 1, the invention relates to an insulator  10  for an electric fence. The insulator  10  is mountable on a support post  12  for supporting a wire  14  to which an electrical current is applied. The post  12  is preferably reinforcing bar, i.e., a round steel member having a plurality of serrations  16 . It will be understood that the post may me of any rigid material, such as wood, metal, and plastic. 
     With additional reference to FIGS. 2-6, the insulator  10  is preferably of one-piece molded plastic construction and includes a body  20  having a closed end  22  opposite an open end  24  to define a blind bore  26  (FIG.  6 ). The bore  26  is preferably substantially cylindrical and includes a plurality of ribs  28 , preferably four ribs, disposed radially in the open area of the bore  26  toward the center of the bore  26  and connected to an inner sidewall  30  of the bore  26  (FIGS. 3,  4  and  6 ). For example, while the insulator  10  is shown in a preferred embodiment with four ribs, it will be understood that other even or odd numbers of ribs may be used, such as  2 ,  3 ,  5 ,  6  or more. 
     The body  20  preferably has a substantially cylindrical external shape, however, it will be understood that the external configuration of the body  20  may be rectangular or of other geometry. 
     The ribs  28  are preferably substantially uniformly spaced apart from one another and configured for receiving and frictionally retaining the steel post  12 . Each rib  28  preferably has a plurality of sectors having different slopes relative to planes  31  and  33  that are perpendicular to a centerline C of the bore  26 . For example, rib  28  preferably has sectors  32 ,  34  and  36 , with sector  34  having a post contacting edge  35  and sector  36  having a post contacting edge  39 . The edges  35  and  39  are positioned so that at least a portion of the edge  35  or the edge  39  or both are available for bearing against the post  12 , depending upon the diameter of the post, when the insulator  10  is installed on the post  12 . 
     The insulator  10  preferably has the following preferred dimensions for use with posts having a diameter of from about {fraction (5/16)} to about {fraction (13/32)} inches.: 
     
       
         
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 Dimension 
                 Degrees 
                 Distance (in) 
               
               
                   
                   
               
             
             
               
                   
                 α 
                 88.5 
                 — 
               
               
                   
                 (angle of Sector 34) 
               
               
                   
                 β 
                 85.5 
                 — 
               
               
                   
                 (angle of Sector 36) 
               
               
                   
                 W1 
                 — 
                 0.73 
               
               
                   
                 (opening width of bore 26) 
               
               
                   
                 W2 
                 — 
                 0.50 
               
               
                   
                 (Opening width of bore at 
               
               
                   
                 beginning of Sector 34) 
               
               
                   
                 W3 
                 — 
                 0.45 
               
               
                   
                 (Opening width of bore at 
               
               
                   
                 beginning of Sector 36) 
               
               
                   
                 W4 
                   
                 0.25 
               
               
                   
                 (end width of Sector 36) 
               
               
                   
                 H1 
                 — 
                 0.10 
               
               
                   
                 (height of Sector 32) 
               
               
                   
                 H2 
                 — 
                 0.90 
               
               
                   
                 (height of Sector 34) 
               
               
                   
                 H3 
                 — 
                 1.24 
               
               
                   
                 (height of Sector 36) 
               
               
                   
                 L1 
                 — 
                 0.14 
               
               
                   
                 (length of Sector 32) 
               
               
                   
                 L2 
                 — 
                 0.93 
               
               
                   
                 (length of Sector 34) 
               
               
                   
                 L3 
                 — 
                 1.24 
               
               
                   
                 (length of Sector 36) 
               
               
                   
                   
               
             
          
         
       
     
     The configuration of the sector  32  facilitates placement of the insulator  10  onto the post  12 . The angled profile of the sectors  34  and  36  facilitates frictional retention of the insulator  10  on the post  12  and enables the insulator  10  to accommodate a relatively wide range of post diameters. Accordingly, it is preferred that the angle a be greater than the angle β. 
     The insulator  10  may be installed onto the post  12  by placing the open end  24  of the bore  26  onto the top of the post  12  and pressing or otherwise urging the insulator  10  downwardly, as by hammering, so that the post  12  is urged toward the end  22 . The ribs  28  tend to deform and compress against the post  12  to provide a friction fit of the insulator  10  onto the post  12 . Top portion  40  of the insulator  10  is preferably rounded so as to provide a relatively smooth surface. As will be appreciated, the top portion  40  of the insulator provides a protective cap over the top of the post. 
     An electric fence may be constructed by setting a plurality of the posts  12  in the ground, positioning one of the insulators  10  over each post  12 , stringing the wire  14  so that it is supported by each of the insulators  10 , and connecting the wire  14  to a source of electricity. Each insulator  10  preferably includes a wire support  42  for supporting the wire  14 . 
     The support  42  preferably includes a pair of lugs  44  and  46  projecting outwardly from an outer surface  48  of a plate  50 . A pair of legs  52  and  54  extend between an exterior portion of the body  20  and an inner surface  56  of the plate  50 . The lugs  44  and  46  may be configured to extend directly from the body  20 , however, the preferred construction utilizing the plate enables the lugs  44  and  46  to be advantageously positioned further from the body  20  and further apart from one another, thereby offering improved strength characteristics. The lug  44  has a downwardly facing recess  58  and the lug  44  has an upwardly facing recess  60 . The recesses  58  and  60  are configured for engaging and retaining the wire  14  in a strung orientation. 
     With reference now to FIG. 8, there is shown an alternate embodiment of an insulator  70  for an electric fence. The insulator  70  is substantially identical to the insulator  10 , except it includes a plurality of ribs  72  which differ from the ribs  28 . The ribs  72  are preferably substantially uniformly spaced apart from one another and configured for receiving and frictionally retaining the steel post  12 . Each rib  72  preferably includes a post contacting edge  74  having a substantially constant slope relative to a plane perpendicular to a centerline C of the bore  26 , with each edge having a substantially similar slope. 
     The foregoing description of certain exemplary embodiments of the present invention has been provided for purposes of illustration only, and it is understood that numerous modifications or alterations may be made in and to the illustrated embodiments without departing from the spirit and scope of the invention as defined in the following claims.