Patent Publication Number: US-2011072652-A1

Title: Method of winding a plurality of stator teeth of a segmented stator core

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional application of U.S. Ser. No. 12/478,901, filed Jun. 5, 2009, the contents of which are incorporated by reference herein in their entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     The subject matter disclosed herein relates to the art of electric machines having segmented stator cores and, more particularly, to a segmented stator core winding apparatus and a method of winding a segmented stator core of an electric machine. 
     At present, stator cores are wound with round wire. The stator core is held stationary and the round wire is fed through a winding needle that is rotated about a stator tooth. Once the stator tooth is wound, the wire is advanced to a subsequent stator tooth. At each tooth, the winding needle not only travels along a circular path but also moves in and out to layer the wire. Upon exiting the winding needle, the wire twists as a result of the rotation created when wrapping the stator tooth. 
     In order to avoid twisting, a segmented stator core is employed. A segmented stator core includes a plurality of individual stator teeth that are joined together to form a stator core. Each tooth is individually wound, and placed in a particular order in a fixture. At this point each tooth is connected to a common bus bar. In the case of a 24 pole stator, as many as 96 connections are required. 
     BRIEF DESCRIPTION OF THE INVENTION 
     According to one aspect of the exemplary embodiment, a winding apparatus for a segmented core having a plurality of stator teeth includes a mounting fixture configured to support select ones of the plurality of stator teeth. The mounting fixture is configured to rotate about an axis defined by each of the plurality of stator teeth. A plurality of stator tooth holding elements are operatively connected to the mounting fixture. Each of the plurality of stator tooth holding elements are configured to retain a select one of the plurality of stator teeth relative to the mounting fixture. The mounting fixture is selectively rotated about the central axis of at least one of the plurality of teeth to apply wraps of wire to the one of the plurality of stator teeth while at the same time rotating others of the plurality of stator teeth. At least one wire guiding member is supported by the mounting fixture. The at least one wire guiding member is configured and disposed to establish a desired length of wire between adjacent ones of the plurality of stator teeth. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       The above, as well as other advantages of the present invention, will become readily apparent to those skilled in the art from the following detailed description when considered in light of the accompanying drawings in which: 
         FIG. 1  is plan view of a winding apparatus for applying rectangular wire to one of a plurality of stator tooth segments without twisting; 
         FIG. 2  is a plan view of the winding apparatus of  FIG. 1  show applying the rectangular wire to another of the plurality of stator teeth segments; 
         FIG. 3  is a plan view of the winding apparatus of  FIG. 1  rotated clockwise ninety (90) degrees shown applying the rectangular wire to yet another of the plurality of stator teeth segments; 
         FIG. 4  is an elevational view of a plurality of wound stator teeth segments connected to form a segmented stator core; 
         FIG. 5  is a front elevational view of one of the plurality of stator teeth illustrating the rectangular wire passing through a channel of a cover member. 
     
    
    
     The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings. 
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to  FIGS. 1-3 , a winding apparatus for applying an uninterrupted, continuous and untwisted length of wire to a plurality of stator teeth in accordance with an exemplary embodiment is indicated generally at  2 . Winding apparatus  2  includes a mounting fixture  4  having a main body  6 . As shown, main body  6  includes a substantially planar surface  8  having a central axis  10 . In addition, winding apparatus  2  includes a plurality of stator tooth holding elements  14 - 17 . While only four stator tooth holding elements are shown, it should be understood that the number of stator tooth winding elements provided on winding apparatus  2  can vary. Winding apparatus  2  is also shown to include a plurality of post members  24 - 27  arranged between adjacent ones of stator tooth holding elements  14 - 17 . 
     In further accordance with an exemplary embodiment, winding apparatus  2  is configured to receive a plurality of stator teeth  37 - 40  that are retained by stator tooth holding elements  14 - 17 , respectively. Stator teeth  37 - 40  represent one pole identified as A 1 -A 4  of a segmented stator core. Winding apparatus  2  selectively positions each of the plurality of stator teeth proximate to a winding member  45  loaded with an amount of wire  50 . In one exemplary embodiment shown, wire  52  includes a plurality of surfaces that collectively define a rectangular cross-section. Wire  50  is initially attached to stator tooth  37 . At this point, mounting fixture  4  rotates about a central axis (not separately labeled) of stator tooth  37 . In this manner, wire  50  is applied to stator tooth  37  with few if any twists. That is, stator tooth  37  is wrapped with a number of wraps of wire, with the wire having fewer twists than the total number of wraps. In accordance with one aspect of the invention, the number of twists will be one fewer than the total number of wraps. In accordance with another aspect of the invention, the number of twists will be between one fewer and half the total number of wraps. In accordance with yet another aspect, the number of twists will be fewer than half of the total number of wraps. In accordance with still another aspect of the invention, the wire will remain untwisted. 
     In addition to rotation, stator tooth  37  oscillates along a liner path defined by the central axis in order to provide proper layering of wire  50 . The oscillation is achieved by moving at least one of main body  6 , stator tooth holding element  14 , and winding member  45 . Once applied to stator tooth  37 , wire  50  is passed over post  24 , main body  6  rotates approximately ninety (90) degrees to position stator tooth  38 . ( FIG. 2 ) proximate to winding member  45 . Wire  50  is passed from stator tooth  37  around post  24  to stator tooth  38  through a manipulation of mounting fixture  4  and/or winding member  45 . 
     Once wire  50  is positioned at stator tooth  38 , mounting fixture  4  begins to rotate about a central axis (not separately labeled) of stator tooth  38 . With this arrangement, both stator tooth  37  and stator tooth  38  rotate simultaneously. In a manner similar to that described above, wire  50  is applied to stator tooth  38  with minimal if any twisting. In addition to rotation, stator tooth  38  oscillates along a liner path defined by the central axis in order to provide proper layering of wire  50 . The oscillation is achieved by moving at least one of main body  6 , stator tooth holding element  15 , and winding member  45 . Once applied to stator tooth  38 , mounting fixture  4  is rotated clockwise approximately ninety (90) degrees to position stator tooth  39  proximate to winding member  45 . ( FIG. 3 ) 
     In addition to rotation, mounting fixture  4  and/or winding member  45  is manipulated to pass wire  50  around post  25 . At this point, mounting fixture  4  rotates all of the wrapped stator teeth, e.g., stator teeth  37  and  38  about a central axis (not separately labeled) of stator tooth  39 . In this manner, wire  50  is applied to stator tooth  39  with minimal, if any, twisting. In addition to rotation, stator tooth  39  oscillates along a liner path defined by the central axis in order to provide proper layering of wire  50 . The oscillation is achieved by moving at least one of the main body  6 , stator tooth holding element  14  and winding member  45 . Once applied, mounting fixture  4  rotates to position stator tooth  40  proximate to winding member  45 . The winding and positioning continues until all teeth for a particular phase or i.e., poles A 1 -A 4  as well as poles, i.e., teeth B 1 -B 4  for pole B, and teeth C 1 -C 4  for any additional phases B and C are wound with a continuous, uninterrupted lengths of untwisted wire. 
     At this point, the plurality of stator teeth  37 - 40  or poles for phase A as well as the stator teeth or poles for phases B and C are arranged in a particular order and joined to a ring member  65  to form a segmented stator core  68  such as shown in  FIG. 4 . A cover member  70  ( FIG. 5 ) is positioned on ring member  65  to form a final segmented core member As each phase is wound with a continuous, uninterrupted length of untwisted wire, only two connections are required for each phase, namely a phase connection and a neutral connection. The leads for each pole pass between teeth along respective channels  73 - 75  that provide any necessary electrical isolation between poles. 
     In accordance with another aspect, prior to winding the plurality of stator teeth  37 - 40 , cover member  70  is installed around the respective stator teeth  37 - 40  to provide electrical isolation between the wire  50  and the stator teeth. In addition to providing electrical isolation between the wire  50  and each stator tooth  37 - 40 , cover member  70  is configured to provide electrical isolation between various phases. The electrical isolation is provided by channels  73 - 75  projecting away from a surface of the stator tooth. During the winding process, wire  50  is placed into an appropriate one of channels  73 - 75 . That is, phase winding A placed in channel  75 , phase winding B placed in channel  74 , and phase winding C placed in channel  73 . Upon completion of winding all desired phase segments, A 1 -A 4 , B 1 -B 4 , and C 1 -C 4  the phase segments are nested together in a desired pattern. 
     With this arrangement, the stator teeth for each phase are wound with continuous lengths of untwisted wire. By using a continuous length of wire for each phase, the number of final connections is greatly reduced. That is, segmented stators that utilize individually wrapped stator teeth can require more than 96 connections before assembly is final. Also, by eliminating twists, the use of wire having a rectangular cross section is possible. Wire having a round cross section that twists during application creates a great deal of bulk for each stator tooth. Wire having a rectangular cross section minimizes an overall form factor for each stator tooth allowing for the construction of small electrical machine. 
     While exemplary embodiments of the invention have been described above, it will be understood that those skilled in the art, both now and in the future, may make various improvements and enhancements which fall within the scope of the claims which follow. These claims should be construed to maintain the proper protection for the invention first described.