Abstract:
A method and device for producing wave windings for an electrical machine, especially for a three-phase generator, is described in which each phase has a wave winding ( 12 ) divided into two winding halves ( 12   a   ,12   b ), which are first deformed into a wavy star shape, are offset from one another by one pole pitch, and are finally inserted jointly into the grooves of a stator lamination packet. A simple and reliable method for production of this wave winding includes first winding a first winding half ( 12   a ) in a first winding direction in a circular or polygonal shape, and then switching over the continuous winding wire ( 15 ) in a winding loop ( 21 ) into the opposite winding direction, then winding the second winding half ( 12   b ) in the opposite winding direction and deforming both winding halves simultaneously into a star shape, offsetting both winding halves ( 12   a   , 12   b ) with respect to each other by one pole pitch (p) so that the winding loop ( 21 ) between the winding halves transitions into the star shape.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a method and device for producing wave windings for electrical machines, especially for a stator of a three-phase generator. 
     2. Prior Art 
     The invention is based on a method and a device for producing wave windings for electric machines according to U.S. Pat. No. 4,857,787. In that instance, the winding for each phase of a three-phase generator is first wound onto a drum or a polygon with the necessary number of windings and is then deformed into a star shape. After this, the winding is folded into two halves so that the two halves are disposed next to one another. Then the two halves are pivoted in such a way that the gaps of the star-shaped loops or waves of one winding half have a loop of the other winding half disposed in them. The wave winding of the one phase that is prepared in this manner is then inserted axially in a known manner into the slots of a stator lamination packet. In the same manner, the winding of the second and third phase of the three-phase generator are then successively preformed, divided, pivoted in relation to each other so that they are offset from one another, and inserted into the stator lamination packet. 
     The division of each phase winding into two parts and the pivoting in relation to one another is relatively costly in this method and can be produced by means of commercially available robots for a large-scale mass production only with a multitude of malfunction-prone manufacturing steps. 
     The automatic large-scale mass production of two-part wave windings with waves of that are offset from one another should be simplified and improved with the current embodiment. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide an improved method for producing wave windings for electrical machines, especially for a stator of a three-phase generator, which is simpler than the current method. 
     It is another object of the present invention to provide an improved device for producing wave windings for electrical machines, especially for a stator of a three-phase generator. 
     According to the invention the method provides a wave winding for a stator of a three-phase generator, which is divided into two winding halves, each consisting of at least one continuous winding wire. Each winding half is in a circular or polygonal shape or deformed into a star shape. They are offset from each other by one pole pitch (p). The wave winding is arranged in grooves provided in a stator lamination packet so that alternating winding heads of the two winding halves are formed on both sides of the stator lamination packet around a circumference of the stator lamination packet. The method comprises the steps of: 
     a) winding the at least one continuous winding wire in a first winding direction to form a first winding half in the circular or polygonal shape; 
     b) switching over the at least one continuous winding wire into an opposite winding direction in a winding loop; 
     c) after the switching over of the at least one continuous winding wire, winding the at least one continuous winding wire in the opposite winding direction to form a second winding half in the circular or polygonal shape; 
     d) simultaneously deforming both the first winding half and the second winding half into a star shape; and 
     e) after the deforming of step d) rotating the first winding half and the second winding half with respect to each other by one pole pitch, so that the winding loop between the first winding half and second winding half transitions into the star shape. 
     The device according to the invention comprises means for winding the at least one continuous winding wire in a first winding direction to form a first winding half in the circular or polygonal shape; means for switching over the at least one continuous winding wire into an opposite winding direction in a winding loop after the formation of the first winding half; means for winding the at least one continuous winding wire in the opposite winding direction to form a second winding half in the circular or polygonal shape after the switching over; means for simultaneously deforming both first winding half and the second winding half into a star shape and means for rotating the first winding half and second winding half with respect to each other by one pole pitch after the deforming so that the winding loop between the first winding half and second winding half transitions into the star shape. 
     The means for winding the at least one continuous winding wire to form the first winding half and the second winding half in the device according to the invention comprises a winding bell rotatable in either of two rotation directions, a plurality of radially movable forming clamps connected to the winding bell and arranged around its circumference, so that the at least one continuous winding wire is wound around the forming clamps. 
     The means for switching over comprises a loop puller for forming the winding loop and the means for deforming both first winding half and second winding half comprises forming levers and means for moving the forming levers radially inward to engage with the first winding half and the second winding half wound around the forming clamps. 
     The method according to the invention and the provided device for producing wave winding halves that are offset from one another, according to the characterizing features of the invention has the advantage that on a winding bell, the two continuous winding halves that are wound one after the other are already wound in an opposite winding direction to one another and deformed into a star shape. By way of a winding loop that is formed between the two winding halves, the two winding halves can then be rotated to the left or right in relation to each other by one pole pitch so that the waves of the two winding halves, which are embodied as star-shaped, are then offset in relation to each other by one pole pitch. Subsequently, the wave winding that is preformed in this fashion is inserted in a known manner into a stator lamination packet of a generator. In the same manner, all three-phase windings of the three-phase generators are produced separately as wave windings and are inserted one after the other into the stator lamination packet. In this manner, the wave windings, with winding halves that are offset from one another, can be produced in a simple and reliable manner in a few work steps in one winding station, and can be transferred to an insertion station. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     The objects, features and advantages of the invention will now be illustrated in more detail with the aid of the following description of the preferred embodiments, with reference to the accompanying figures in which: 
     FIGS.  1 ( a ) and  1 ( b ) are, respectively, schematic action plan views showing the winding of a first coil half; 
     FIGS.  2 ( a ) and  2 ( b ) are, respectively, schematic action plan views showing the winding of a loop with reversal of winding direction; 
     FIGS.  3 ( a ),  3 ( b ) and  3 ( c ) are, respectively, schematic action plan views showing the winding of a second winding half; 
     FIG. 4 is a perspective view of a winding device with an insertion tool under it; 
     FIG. 5 is a diagrammatic plan view of a star-shaped, previously formed winding; 
     FIG. 6 is a diagrammatic cutaway perspective view of a wave winding, whose one half has been stripped into the insertion tool; 
     FIG. 7 is a diagrammatic cutaway perspective similar to FIG. 6, showing rotation of the upper winding half; 
     FIG. 8 is a plan view of a finished wave winding arranged in the insertion tool; 
     FIG. 9 is a cutaway longitudinal cross-sectional view showing the wave winding and the insertion tool after insertion of the wave winding; 
     FIG. 10 is a perspective view of a stator lamination packet with one divided wave winding shown; and 
     FIG. 11 is a perspective view of the finished stator with three phase windings. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In order to produce a stator  10  according to FIG. 11, with a three-phase wave winding  11 , each of the three-phase strands is produced in advance on a winding device  13  according to FIG. 4 by means of a wave winding  12  with winding halves  12   a  and  12   b  that are offset from one another. FIGS. 1 to  3  schematically depict the production of such a wave winding  12  from FIG. 10. A wire clamp  14  secures one end  15   a  of a winding wire  15  according to FIG. 1 b  at the lower end of a forming clamp  16 . According to FIG. 1 a , six of these forming clamps are arranged in a star shape in the winding device  13 . The winding wire  15  is withdrawn from a storage drum, not shown, by way of a wire orifice  17 . The forming clamps  16  are disposed so that they can move radially in a winding bell  18  of the winding device  13  according to FIG.  4 . In order to produce the first winding half  12   a , the forming clamps  16  are rotated clockwise with the winding bell  18  so that the first winding half  12   a  is produced with four complete windings in a polygonal form. 
     Now the winding device is stopped, wherein the forming clamp  16   a  stays at the level of the wire orifice  17 . It is clear from FIG. 2 that in its front region, the forming clamp  16   a  has a segment-shaped recess  19 , in the front of which an axially extending, strut-shaped loop puller  20  remains. The wire orifice  17  is now conveyed to this loop puller and the winding wire  15  from the wire orifice  17  is now conveyed up from the bottom around the loop puller  20 , wherein the forming clamps  16  and  16   a  are moved axially downward together with the winding bell  18 . 
     Now the winding bell  18  is slowly rotated further counter-clockwise and the wire orifice  17  is moved back into its outer position. This produces a winding loop  21  on the loop puller  20  as can be seen in FIG. 2 b.    
     According to FIG. 3, the second winding half  12   b  is now produced in the opposite winding direction by means of a corresponding number of rotations of the winding bell  18 . 
     FIG. 4 is a three-dimensional depiction of the winding device  13  for producing the wave winding  12 . It is clear from this figure that on the underside of the winding bell  18 , the six forming clamps  16  are disposed in a polygonal arrangement so that they can be moved on inwardly extending on axles  22 , wherein the drive  16   b  is supplied pneumatically, via Bowden cables, or via other means. Forming levers  23  are respectively disposed between the forming clamps  16  and can likewise be respectively moved by way of a drive mechanism  23   a  on radially disposed axles  24  by pneumatic means, a Bowden cable, or the like. The six forming levers  23  are depicted in FIG. 4 in their outer position, pivoted up and in so that during the winding of the first and second winding halves  12   a  and  12   b , they cannot protruding into the winding region. On the back side of the forming clamps  16 , a stripper  25  is disposed so that it can be moved axially, which stripper protrudes above the first winding half  12   a  with a stripper arm  25   a  and protrudes above the second winding half  12   b  with another stripper arm  25   b , as can be seen in FIGS. 1 b  to  3   b . The winding bell  18  can be rotated by a drive mechanism  26  in the direction of the arrows in both rotation directions, and can also be moved in the axial direction. 
     Beneath the winding bell  18  an insertion tool  27  is disposed, which has a receiving crown  28  and insertion needles  29  disposed radially inside them (visible in FIG.  8 ). The receiving crown  28  is provided with longitudinal slots  30  between the insertion needles  29 . The insertion tool  27  rests on a tool table  31  that can be pivoted and can likewise be adjusted with regard to its height. 
     In another process step, the upper and lower winding halves  12   a  and  12   b  are now simultaneously deformed into a star shape according to FIG. 5, in which the six forming clamps  23  are first folded outward in a perpendicular fashion by their drive mechanism  23   a  and are then moved radially inward via the axles  24 , as indicated by the arrows in FIG.  5 . Simultaneous to this, the forming clamps  16  are slid radially inward in a yielding fashion on their axles  22 , which is likewise indicated in FIG. 5 by means of corresponding arrows. Both winding halves  12   a  and  12   b  are now disposed in a star shape spaced one above the other on the forming clamps  16  and the forming levers  23 . 
     In other steps, the forming clamps  16  are then moved by 3 mm in the arrow direction according to FIG. 5, the coil  12  is released, the wire clamp  14  is opened, and then the lower winding half  12   a  is stripped from the forming clamps  16  by the strippers  25  according to FIG. 6, wherein these winding halves are received with their star-shaped legs into longitudinal slots  30  of the receiving crown  18  of the insertion tool  27 . The upper winding half  12   b  is likewise slid downward by the strippers  25   b , but remains in the lower region of the forming clamps. The upper and lower winding halves  12   a  and  12   b  are now connected to one another only by way of the winding loop  21 . 
     In the subsequent process step, the winding bell  18  is then rotated back to the left by one pole pitch p of the twelve-polled wave winding  12 , i.e. by 30 ° in the direction of the arrow, so that the star-shaped waves of the two winding halves  12   a  and  12   b  are now offset in relation to one another. The winding loop  21  is moved to the left so that it likewise follows the course of the upper winding half  12   b.    
     In another process step, the upper winding half  12   b  is also stripped from the forming clamps  16  by the stripper  25  and is inserted into the longitudinal slots  30  of the receiving crown  28  of the insertion tool. As shown by FIG. 8, the waves of the two winding halves  12   a  and  12   b  are now disposed symmetrically offset from one another in the longitudinal slots  30  of the receiving crown  28 . In this state, the strippers  25  are lifted up again. The forming levers are now returned back into the outer position and thereby pivoted back into their initial position according to FIG. 4, and the winding bell  18  moves upward. A stator lamination packets  32  is fixed to the upper part  28   a  (FIG. 4) of the receiving crown  28 . Then the tool table  31  pivots in relation to an insertion station  34  that is schematically depicted in FIG.  9 . The preformed wave winding  12  is inserted in a known manner into the grooves of the stator lamination packet  32  by means of an insertion die  33 , and the upper winding heads  12   c  are pressed radially outward into the position shown in FIG. 10 by means of press-back clamps  35 . A groove closure is also carried out in this station. In this manner, alternating winding heads  12   c  are formed from the two winding halves on both sides over the circumference of the stator lamination packet  32 . In this connection, the stator lamination packet  32  is secured on the receiving crown  28  by a packet clamping ring  36 . 
     In the manner described above, another wave winding is now produced on the winding device according to FIG.  4  and is deformed into a star shape. Then the two winding halves are rotated in relation to each other by one pole pitch in the above-described manner, are then taken by the insertion tool and finally inserted into the stator lamination packet next to the first wave winding, in the grooves provided for this purpose. The production and insertion of the third wave winding also occurs in the same manner so that in the end, a finished stator according to FIG. 11 is produced, which has a three-phase wave winding  11 . The beginnings and ends of the three phases of the three-phase wave winding are labeled there with the letters U, V, W and X, Y, Z. 
     With these wave windings which are respectively offset from one another in opposite directions, the groove-filling factor in the stator lamination packet  32  can be increased by up to 10% in comparison to a one-piece wave windings. In generators with higher outputs, the groove-filling factor can also be increased further by virtue of the fact that instead of one winding wire with a relatively large cross-section, two or more winding wires with correspondingly smaller cross sections can be wound and connected parallel to one another. 
     The pivoting of the two winding halves  12   a  and  12   b  in relation to each other in the winding device according to FIG. 4 can also occur in the same manner by means of rotating the upper winding half  12   b  toward the right in relation to the lower winding half  12   a . In this instance, the winding loop  21  would not be folded toward the upper winding half  12   b  in accordance with FIG. 7, but would be folded toward the lower winding half  12   a . In this instance, the winding beginning of the lower winding half  12   a  and the winding end of the upper winding half  12   b  have to be correspondingly positioned so that the lower winding half  12   a  does not become longer and so that the upper winding half  12   b  does not become shorter. In the same manner, the two winding halves  12   a  and  12   b  can alternatively also be wound in the opposite winding direction onto the forming clamps—i.e. the first half toward the right and the second half toward the left. In this instance, the loop puller must be disposed on the right side on the forming clamp  16   a . With a disposition of the loop puller  21  in the center of the forming clamp  16   a , the winding device can be used for both winding directions. 
     In any case, the current flow in the winding sections of the two winding halves inside the grooves of the lamination packet always remains the same through the rotation by 30°, i.e. by one pole pitch. 
     Since the wave winding is also divided into two halves in both directions at the groove outlet, the three winding strands on the coil heads only ever intersect with half the number of line wires of a neighboring phase winding. In comparison to an undivided winding, this results in a flatter winding head with a more uniform wire routing, along with a current noise reduction and improved cooling.