Patent Publication Number: US-2007096580-A1

Title: Stator of an electric machine

Description:
STATOR OF AN ELECTRIC MACHINE  
      This application claims priority from German Application Serial No. 10 2005 051 380.8 filed Oct. 27, 2005.  
     FIELD OF THE INVENTION  
      The invention concerns a stator of an electric machine and a method for producing such a stator.  
     BACKGROUND OF THE INVENTION  
      From DE 10 2004 001 842 A1 a stator with a winding support is known, which has a plurality of grooves and teeth. A several winding strands are inserted in the grooves. To enable the winding strands to be inserted, they are pre-wound in such manner that they can be moved over the teeth without problems.  
      From DE 103 61 670 A1, a stator with a winding support is known, in which several pre-wound winding strands are inserted in the initially flat winding support.  
      The winding support is then bent into a ring in order for a cylindrical stator with the windings.  
      To enable the pre-wound winding strands to be inserted into the grooves, they must fit over the teeth with a certain clearance. This results in winding head loops, which project in the axial direction far beyond the stator. This increases the amount of axial space needed for accommodating the stator. Furthermore, the winding strands overlap in the radial direction in the known designs. Accordingly, the radial space occupied by the stator is also disadvantageously increased.  
      The purpose of the present invention is to provide a stator which occupies little axis and radial space, and also to develop a method by which such a stator can be produced particularly simply and inexpensively.  
     SUMMARY OF THE INVENTION  
      According to the invention, the stator consists of a winding support having teeth and grooves. Furthermore, windings are arranged in the grooves. The winding support consists of a plurality of identical segments each having at least two teeth, which are individually wound with the windings. The individual segments are attached to one another in such manner that, together with the windings, they form a cylindrical stator. Advantageously, the stator is arranged in a housing.  
      The windings of the individual segments are electrically connected to one another. Advantageously, the connections are arranged inside the grooves of the winding support. As a result, there is no crossing over of the windings in the winding head loops so the winding head loops can be smaller than in the known designs. The windings of individual segments can be connected in parallel or preferably in series.  
      The magnetic properties of the stator can be influenced by the number of turns in the individual windings. Accordingly, the number of turns of the individual windings can be made the same or different. Likewise, the winding direction on the individual windings of a segment can be the same or different.  
      The stator has segments with more than one tooth. An advantageous design is for the stator to have individual segments each with three teeth. The windings of the segments can be connected in series, in parallel or even mixed, i.e., partly in series and partly in parallel.  
      The segments associated with a phase can be arranged in star or delta form, i.e., in a ring, one after the other.  
      According to the invention, the individual segments are flat before winding. This means that, the rear side of the segments is flat and the teeth are advantageously orientated parallel to one another. Since the shape of all the segments is the same, the windings can be positioned on them mechanically in large numbers and particularly simply and inexpensively. After winding, the segments are bent into circular arcs with the teeth on the inside of the circular segments. This gives a further advantage. Since the deformation reduces the space within the grooves, the turns inside them are pressed closer together. This enables the grooves to be filled with turns in a way not possible with normal winding methods. A high groove filling ratio directly increases the power density of the machine and thus acts to increase its power. To obtain a stator, the desired number of segments are arranged in a ring and connected together, whereby a cylindrical winding support is produced. This winding support is advantageously fitted into a cylindrical housing to increase the stability of the stator.  
      Furthermore, the ready-shaped cylindrical stator can be stabilized even more by way of a cast-in mass. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The invention will now be described, by way of example, with reference to the accompanying drawings in which:  
       FIG. 1  is a structure of a stator;  
       FIG. 2  is a structure of a segment;  
       FIG. 3  is a segment after winding and shaping;  
       FIG. 4  is a schematic representation of the winding of a segment, and  
      FIGS.  5  to  7  are representation of the arrangement of the segments and windings. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       FIG. 1  shows a stator  1  according to the invention. A winding support  2  consists of nine identical segments  6 . Each segment  6  has three teeth  4  and corresponding grooves  3  between the teeth  4 . Windings  5  with their turns  7  can be seen in the grooves  3 . For the sake of clearer representation only a small number of turns  7  are shown, which have not been pressed together by the shaping deformation. The stator  1  is of the type used for a three-phase current generator. For this, three segments  6  at a time are electrically connected in the manner of a star circuit. The segments  6  associated with the various phases are arranged directly adjacent to one another, so that in the circumferential direction every third segment  6  is associated with one phase of the stator  1 . Around the segments  6  of the winding support  2  is fitted a housing  9  to increase the stability of the stator  1 .  
       FIG. 2  shows the segment  6  before it has been deformed. In the Figure, a flat rear side  10  of the segment can be seen, the parallel teeth  4  and the turns  7  wound around the teeth  4 . There are V-shaped recesses  11  at the bottom of the grooves, which facilitate the shaping of the segment  6 .  
       FIG. 3  shows the fully-wound segment  6  which has been shaped after winding. The windings  5  are wound round the teeth  4  and have been pressed together by the deformation of the segment  6 . The rear side  10  of the segment  6  is shaped in a circular arc and the teeth  4  are on the radially inner side of the circular arc segment.  
       FIG. 4  shows the manner in which the turns  7  are wound round the teeth  4 . It can be seen that the winding direction alternates between adjacent teeth  4 . In addition, the sections of the turns  7  are shown, which constitute connections  8  by which the individual windings  5  are connected to one another. Advantageously, these connections  8  are arranged in the grooves  3 .  
       FIG. 5  shows thee segments, each with three windings, the individual windings  5  of the segment  6  being connected in series with one another. The segments  6  are again arranged in star connection.  
       FIG. 6  shows three segments, each with three windings, the individual windings  5  of the segment  6  being connected in parallel with one another. The segments are arranged in delta form.  
       FIG. 7  shows a mixed arrangement in which the windings  5  of the segment  6  are connected with one another partly in parallel and partly in series. The segments  6  are arranged partly in star and partly in delta connection.  
     REFERENCE NUMERALS  
     
         
           1  stator  
           2  winding support  
           3  groove  
           4  tooth  
           5  winding  
           6  segment  
           7  turn  
           8  connection  
           9  housing  
           10  rear side of a segment  
           11  recess