Abstract:
The present invention relates to a method of manufacturing an improved comb for a disk wound transformer. The method comprises the steps of providing a web of cellulose material; removing a portion of the cellulose material to create a plurality of longitudinal slits along the length of the web, wherein the longitudinal slits have a fixed length and width; and folding the web along a line proximate the midpoint of the length of each of the longitudinal slits such that the cellulose material adjacent the longitudinal slits defines a plurality of tooth members.

Description:
TECHNICAL FIELD  
         [0001]    The present invention relates generally to electrical transformers and winding structures for the transformers. More particularly, the present invention relates to a comb used within the winding structures of transformers to maintain the integrity of the windings and the winding structures during and after the manufacturing process.  
         BACKGROUND OF THE INVENTION  
         [0002]    The transformer is a known electrical component which contains at least two electrical windings formed into a coil or coils mounted on a core of magnetic material by means of which AC electrical energy is coupled from one winding to the other, respectively termed the “primary” and the “secondary.” Generally each of those windings are formed of a large number of turns of electrical enamel or paper covered wire fabricated in the form of a coil by means of conventional coil-winding machinery.  
           [0003]    In the past, disk wound transformers have been manufactured using molded combs, cut combs, or use key spacers between winding segments. Each of these alternatives is typically expensive and require set-up procedures requiring time and labor.  
           [0004]    The present invention is provided to solve these and other problems and to provide other advantages. Specifically, The present invention will provide, among other things, greater design flexibility, lower cost, a higher thermal rating on the comb and greater stability during the winding process. Preferred embodiments will be disclosed and the novel aspects of the present invention will be particularly identified and discussed herein.  
         SUMMARY OF THE INVENTION  
         [0005]    It is an object of the present invention to provide a comb for a disk wound transformer and method for manufacturing the same.  
           [0006]    According to one aspect of the present invention, a comb for winding coils of a disk wound transformer is disclosed. The comb comprises a first row comprising a plurality of first tooth members, wherein each first tooth member forms an apex proximate a respective midpoint of each of the respective first tooth members. The comb further comprises a second row comprising a plurality of second tooth members adjacent the row of first tooth members. Each second tooth member forms an apex proximate a respective midpoint of each of the respective second tooth members. The first and second rows of tooth members are formed from a single web of cellulose material.  
           [0007]    According to another aspect of the present invention, a method for creating a comb is disclosed. The method comprises the steps of providing a web of cellulose material and removing a portion of the cellulose material to create a plurality of longitudinal slits along the length of the web, wherein the longitudinal slits have a fixed length and width. The method further comprises the step of folding the web along a line proximate the midpoint of the length of the longitudinal slits, wherein the cellulose material adjacent the longitudinal slits defines a plurality of tooth members for receiving transformer coil therebetween.  
           [0008]    According to yet another aspect of the present invention, a method of winding coil on a transformer core is disclosed. The method comprising the steps of providing a winding structure and providing a comb of the type described above; attaching the comb to the winding structure; and winding coil between the teeth of the comb.  
           [0009]    According to another aspect of the present invention, a second embodiment of a comb for winding coils of a disk wound transformer is disclosed. The second embodiment comprises a plurality of first longitudinal members formed from cellulose material. Each of the plurality of first longitudinal members has either a male or female portion at its distal end. The comb also comprises a plurality of second longitudinal members formed from cellulose material. Each of the plurality of second longitudinal members has a male or female portion at its distal end. Each of the male portions of first and second longitudinal members is received by a corresponding female portion of the other longitudinal members such that an apex is formed by the distal ends of the first and second plurality of longitudinal members. Thus, a plurality of tooth members for receiving coil windings of a transformer is formed.  
           [0010]    According to still another aspect of the present invention, a method of making the second embodiment of a comb for a disk wound transformer described above is disclosed.  
           [0011]    Other features and advantages of the invention will be apparent from the following specification taken in conjunction with the following drawings.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    In order that the present invention may be more fully understood, it will now be described by way of example, with reference to the accompanying drawings in which:  
         [0013]    [0013]FIG. 1 is a partial perspective view of a prior art molded comb;  
         [0014]    [0014]FIG. 2 is a perspective view of a prior art winding structure incorporating the prior art molded combs of FIG. 1;  
         [0015]    [0015]FIG. 3 is a partial front perspective view of a section of a comb of the present invention; and  
         [0016]    [0016]FIG. 4 is a front view of the comb of FIG. 3;  
         [0017]    [0017]FIG. 5 is a top view of the comb of FIG. 3 after the holes have been punched out and the fold lines have been placed on the rigid paper;  
         [0018]    [0018]FIG. 6 is a perspective view of the present invention in a continuous folded piece encircling a disk wound transformer structure;  
         [0019]    [0019]FIG. 7 is a top view of a second embodiment of a comb of the present invention; and,  
         [0020]    [0020]FIG. 8 is a partial perspective view of a section of the second embodiment of a comb of the present invention; 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0021]    While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail preferred embodiments of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the broad aspect of the invention to the embodiments illustrated.  
         [0022]    With reference to FIGS.  3 - 5 , illustrated are various views of a comb  1  for a disk wound transformer according to the present invention. The comb  1  comprises a first row  2  having a plurality of first tooth members  10 , wherein each first tooth member  10  forms an apex  34  proximate a respective midpoint of each of the respective first tooth members  10 . The comb  1  further comprises a second row  4  comprising a plurality of second tooth members  12  adjacent the first row  2  of first tooth members  10 . Each second tooth member  12  forms an apex  34  proximate a respective midpoint of each of the respective second tooth members  12 . The rows  2 ,  4  of first and second tooth members  10 ,  12  are formed from a single web  14  of cellulose material.  
         [0023]    Specifically, the comb  1  is made from a web  14  of rigid paper material, preferably a high temperature paper, such as NOMEX sold by DuPont, or a thin, rigid material such as GLASTIC FHT sold by Glastic Co. The paper web  14  has a plurality of longitudinal slits  16  along its length. Each longitudinal slit  16  is approximately one-half inch wide and approximately six inches long, with an approximate one-half inch of web  14  between each longitudinal slit  16 . However, it is known that the longitudinal slit  16  dimensions can vary depending upon the size and type of transformer with which the comb  1  is being employed.  
         [0024]    A series of fold lines are impressed laterally across the paper web  14 . The first fold line A-A is placed equidistant along the length of the row of longitudinal slits  16 . The second fold line B-B is placed inward of the row of longitudinal slits  16 , approximately five-eighths inch from the end of the longitudinal slit  16 . The third fold line C-C is placed outward of the row of longitudinal slits  16 , approximately five-eighths inch away from the opposed end of the each of the longitudinal slits  16 . Where more than one row of longitudinal slits  16  is created in the paper web  14 , the fold lines B-B and C-C are impressed approximately two inches apart. However, it is known that this dimension can vary according to the size and design of the transformer with which the comb is used. To complete production of the comb  1 , the paper web  14  is folded along fold lines A-A, B-B and C-C.  
         [0025]    The comb  1  of the present invention will preferably be manufactured using a steel rule die. The actual size and length of the comb  1  may vary, depending on several factors, including voltage rating. Likewise, the size of the web  14  of rigid paper material is determined by the such factors, as well as by the specific diameter of the coil (not shown) being wound. The number of rows of combs is typically a function of the coil diameter.  
         [0026]    [0026]FIGS. 7 and 8 illustrate another embodiment of a comb  22  according to the present invention. Like the embodiment described above, the comb  22  illustrated in FIGS. 7 and 8 is made from a rigid paper material; preferably a high temperature paper, such as NOMEX or a thin, rigid material such as GLASTIC FHT. However, it is contemplated that the comb  22  be made from any rigid paper material capable of maintaining the integrity of coil windings and winding structures  18  during the winding of electrical transformers.  
         [0027]    As shown in FIGS. 7 and 8, a first and second plurality of a longitudinal members  24 ,  26  is formed from cellulose material. Each of the longitudinal members comprising the first and second plurality of longitudinal members  24 ,  26  has either a male  28  or female  30  portion extending from a distal end. Each of the male  28  or female  30  portions of the first and second longitudinal members  24 ,  26  is received by a corresponding male  28  or female  30  portion of the other of the first and second longitudinal members  24 ,  26  such that an apex  32  is formed by the distal ends of the first and second longitudinal members  24 ,  26 . Accordingly, a plurality of tooth members for receiving coil windings of a transformer is formed.  
         [0028]    In manufacturing the comb  22  illustrated in FIGS. 7 and 8, material is removed from first and second webs of cellulose  34 ,  36  such that the first and second plurality of longitudinal members  24 ,  26 , including their respective male  28  and female  30  portions, are defined. The respective male  28  and female  30  portions of the longitudinal members  24 ,  26  are then interlocked and the webs  34 ,  36  are folded at a distance from the distal end of the length of the first and second plurality of longitudinal members  24 ,  26  such that an apex  32  is formed by the distal ends of the first and second plurality of longitudinal members  24 ,  26 . Accordingly, a plurality of tooth members of the comb  22  is defined.  
         [0029]    Either of the combs  1 ,  22  described above may be affixed to the inner winding in a number of different ways. As seen in FIG. 6, one preferred method of assembly is to place individual combs  1 ,  22  between longitudinally placed rods secured to the inner winding. These rods also serve the function of providing the proper radial space between the high voltage and low voltage windings. This method allows fewer combs  1 ,  22  to be used if placed between every other set of rods. Generally, the combs  1 ,  22  described herein are suitable for use in transformers having voltage ratings of between 75 kVA and 750 kVA. However, it is contemplated that these combs  1 ,  22  are suitable for use with any size transformer.  
         [0030]    Another preferred method of assembly illustrated in FIG. 6 is to continuously fold the combs  1 ,  22  (as in an accordion or bellows) into a stack and then fan them over the perimeter of the inner winding. This allows for rapid placement of the comb, which is an advantage over the previously disclosed method.  
         [0031]    While the specific embodiments have been illustrated and described, numerous modifications come to mind without significantly departing from the spirit of the invention and the scope of protection is only limited by the scope of the accompanying claims.