Abstract:
An electrical connector for transformer studs accommodates two different size transformer studs, at different times, in a slip-fit blind bore. A large circular bore is threaded and over-sized for a slip fit of a stud of the largest size with ample clearance space to facilitate placement of the large stud in the bore. A smaller threaded recess is created by an arc formed in a periphery of the large circular bore and is sized to fit a smallest stud. A set screw holds the smaller stud in the threaded recess or the larger stud in the large circular bore. The matching threads provide an effective, efficient, long-lasting, and sturdy electrical transformer connection.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to electrical connectors for transformers. More particularly, it relates to a slip fit electrical connector that is compatible with transformer studs having different diameters. 
   2. Description of the Prior Art 
   Conventional multiple stud transformer connections that can accommodate only two (2) studs require multiple machining operations. Thus there is a need for a transformer connection that accommodates two (2) studs of different sizes but which requires fewer manufacturing operations to manufacture. 
   U.S. Pat. No. 6,579,131 to Ashcroft discloses a small stud seat within a small bore having a first center, and a larger stud seat within a medium-sized bore having a second center that is offset from the first center. A third bore is larger in diameter than the small and medium-size bores and has a third center offset from the first and second centers of the two (2) smaller bores. The sole function of the large bore is to provide clearance space. The large bore is unthreaded to permit a connector to be quickly slipped over a threaded stud regardless of size when jam screws are retracted. In other words, the Ashcroft structure can accommodate two (2) stud sizes but such accommodation requires the machining of three (3) eccentric bores, two (2) of which are threaded. 
   What is needed, then, is a slip fit electrical connector that can accommodate two (2) stud sizes but which does not require the machining of three (3) eccentric bores of progressively larger sizes. 
   However, in view of the art considered as a whole at the time the present invention was made, it was not obvious to those of ordinary skill in this art how the identified needs could be met. 
   SUMMARY OF INVENTION 
   The long-standing but heretofore unfulfilled need for a slip fit electrical connector that can handle two (2) studs of differing diameters at different times but which requires fewer machining steps than the connectors of the prior art is now met by a new, useful, and nonobvious invention. 
   The novel stud mount transformer connector includes an elongate lug of solid construction. A plurality of conductor channels is formed in the elongate lug in transverse relation to a longitudinal axis of the elongate lug. The conductor channels are longitudinally spaced apart with respect to one another. A plurality of set screw channels are also formed in the elongate lug. The set screw channels are also longitudinally spaced apart with respect to one another and the number of set screw channels matches the number of conductor channels. The set screw channels are disposed in intersecting relation to the conductor channels. 
   An internally threaded, longitudinally-extending circular blind bore is also formed in the elongate lug. 
   A threaded recess is formed in a periphery of the circular blind bore. This threaded recess or circular arc has a radius that corresponds to a radius of a first transformer stud. The externally threaded first transformer stud screw-threadedly engages the internally threaded circular arc along the bottom of the first transformer stud. A jam or set screw bears down on the top of the first transformer stud to hold it in its operative engagement with the circular arc. An imaginary longitudinal axis of the set screw bisects the circular arc, i.e., the longitudinal axis of the set screw and the mid-point of the circular arc are diametrically opposed to one another. 
   The circular blind bore intersects the circular arc at a first end of the circular arc and at a second end of the circular arc. The circular blind bore has a diameter sufficient to accommodate a second transformer stud having a diameter greater than a diameter of the first transformer stud and to have excess space around said second transformer stud so that the second transformer stud may be easily positioned in the bore when the set screws are retracted. 
   The external threads of the second transformer stud screw-threadedly engage the internal threads of the circular blind bore where said internal threads meet the first and second ends of the circular arc. The external threads of the second transformer stud gradually disengage therefrom because the circular blind bore has a diameter greater than the diameter of the second transformer stud. The second transformer stud does not contact or screw threadedly engage the circular blind bore at any points other than near said first and second ends of the circular arc. 
   The second transformer stud is held in registration with said first and second ends of said circular arc by a set screw disposed in a set screw channel that intersects the circular blind bore. The longitudinal axis of the set screw bisects the circular arc. 
   Accordingly, only two machining steps are required to form the circular blind bore. The two machining steps include a first step to form the circular blind bore and a second step to form the circular arc or threaded recess in the periphery of the circular blind bore. The first externally threaded stud screw threadedly engages the threaded recess or circular arc and the opposite ends of the circular arc forms a stud seat for the second externally threaded stud having a diameter greater than that of the first stud. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a fuller understanding of the invention, reference should be made to the following detailed description, taken in connection with the accompanying drawings, in which: 
       FIG. 1  is a perspective view of a first illustrative embodiment of the invention; 
       FIG. 2  is a perspective view of a second illustrative embodiment of the invention; 
       FIG. 3  is a perspective view of a third illustrative embodiment of the invention; 
       FIG. 4  is a sectional view depicting a large stud seated in a first non-circular bore and held in position by a first jam screw; and 
       FIG. 5  is a sectional view depicting a small stud seated in an arc formed by a circular bore and held in position by a second jam screw. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring now to  FIG. 1 , it will there be seen that the novel stud connector is denoted as a whole by the reference numeral  10 . 
   In the embodiment of  FIG. 1 , lug body  12  has a straight configuration. A plurality of conductor-receiving channels having a common diameter, collectively denoted  14 , are formed in a sidewall  16  of said lug body  12  in equidistantly spaced relation to one another along the extent thereof. A plurality of set or jam screw-receiving channels having a common diameter, collectively denoted  18 , are formed in a top wall  20  of said lug body  12  in intersecting relation with said conductor-receiving channels. Both the conductor-receiving channels and the set screw-receiving channels are formed transversely relative to the longitudinal axis of lug body  12 . 
   An elongate circular blind bore that is internally threaded, not depicted in  FIG. 1 , is formed in coincidence with the longitudinal axis of lug body  12 . It has a diameter greater than externally threaded transformer stud  22 . Therefore, transformer stud  22  may be inserted into said blind bore in the absence of screwthreaded engagement. Transformer stud  22  is secured at its base by boss  24  which mounts to a part of a transformer, not shown. It is therefore understood that transformer stud  22  cannot rotate and that lug body  12  is rotated relative to transformer stud  22  to tighten a screwthreaded connection between said transformer stud  22  and connector  10 . Said screwrhreaded connection is made after said transformer stud  22  is inserted into the blind bore in said absence of screwthreaded engagement. 
     FIG. 2  also depicts a stud-mounted transformer connector, but this particular embodiment has a two-tier arrangement to double the amount of conductors that may be accommodated without increasing the length of lug body  12 . 
   The stud-mounted transformer connector of  FIG. 3  has a “T”-shaped lug main body so that conductors may be attached to a left side and to a right side thereof, thereby enhancing the versatility of the device. The “T”-shape also provides another way of increasing conductor-accommodating capacity without increasing the length of lug  12 . 
   The elongate blind bore is depicted in the transverse sectional views of  FIGS. 4 and 5  and is generally denoted  30  as a whole. Blind bore  30 , unlike prior art bores, is not formed by machining a plurality of circular bores where each circular bore has a center spaced apart from the respective centers of the other circular bores. 
   After blind bore  30  is formed in lug  12 , a threaded recess or circular arc is machined into the periphery of blind bore  30 . The machining process removes material from lug body  12  and therefore creates an empty space in open communication with blind bore  30 . The circular arc is formed by a small diameter bore of which only a short arc  32  at the bottom thereof has a physical existence when the machining process is completed. The remainder of said small diameter bore is imaginary because it is subsumed by larger blind bore  30  having a center that is eccentric relative to the center of said small diameter bore. 
   Short arc  32  is internally threaded and is therefore adapted to screw-theadedly receive externally threaded transformer stud  22 . Such stud  22  is a small diameter stud. 
   As best understood in connection with  FIG. 4 , internally threaded circular arc  32  accommodates small diameter transformer stud  22 , hereinafter to as the first externally threaded transformer stud and elongate set screw  36  secures said first externally threaded transformer stud  22  into its seated position with said internally threaded circular arc. An imaginary longitudinal axis of elongate set screw  36  bisects internally threaded circular arc  32 . 
   As best understood in connection with  FIG. 5 , large bore  30  accommodates large diameter externally threaded transformer stud  44  and truncate set screw  46  secures said stud  44  into its seated position as depicted. depicted in  FIG. 5 . the diameter of large bore  30  is greater than the diameter of transformer stud  44 . Therefore, transformer stud  44  may be inserted into said blind bore in the absence of screwthreaded engagement. However, after said non-screwthreaded insertion is accomplished. externally threaded transformer stud  44  is then brought into screwthreadcd engagement with said internally threaded blind bore. As best understood in connection with  FIG. 5 . after said non-screwthreaded insertion is accomplished, transformer stud  44  enters partially into the empty space created by the removal of material during the formation of circular arc  32 . This partial entry or nesting of transformer stud  44  into said empty space increases die stability of the connection between connector  10  and transformer stud  44 . More particularly. the nesting increases the amount of screwthreaded engagement between externally threaded transformer stud  44  and internally threaded blind bore  30 . In the absence of the empty space. full screwthreaded engagement between transformer stud  44  and circular bore  30  would occur only at a point in the  6 : 00  position. With the empty space. as depicted in  FIG. 5  full screwthreaded engagement occurs at circumiferentially spaced apart points  32   a  .  32   b  . Therefore, when an installer tightens connector  10  by rotating it relative to non-rotating transformer stud  44 . such rotation can cause displacement of transformer stud  44  if it contacts blind bore  30  only at said  6 : 00  position but such rotation will not cause displacement of said transformer stud if it contacts blind bore  30  at said points  32   a  ,  32   b  . Accordingly, said empty space increases the stability of the connection between connector  10  and transformer stud  44  as aforesaid. 
   Significantly , large diameter transformer stud  44  makes full screw-threaded engagement with large circular bore  30  only at two ( 2 ) points are endpoints  32   a  and  32   b  of short arc  32 . The amount of screw-threaded engagement gradually reduces from said respective points of full engagement and disengagement occurs at the points denoted  33   a ,  33   b , in  fig. 5 . The second transformer stud gradually disengages from the internal threads of the large bore due to the larger diameter of said large bore. 
   The bottom arc of large diameter stud  44  is unsupported between said points  32   a  and  32   b  as depicted in  FIG. 5 . The top or twelve o&#39;clock position of said large diameter stud is contacted by the leading end or bottom of set screw  46 . Thus, large diameter stud  44  is held securely in place by a triangulation of forces. 
   This is the first lug having a machined bore that includes only two circular parts and which is adapted to accommodate two transformer studs of differing diameters. Only two (2) machining steps are needed to create a large diameter circular bore for receiving a large stud and providing ample clearance space for insertion of said large stud into said large bore. The large bore has a circular arc formed in its periphery that creates a recess for receiving a small stud. 
   It will be seen that the advantages set forth above, and those made apparent from the foregoing description, are efficiently attained and since certain changes may be made in the above construction without departing from the scope of the invention, it is intended that all matters contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. 
   It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween. Now that the invention has been described,