Abstract:
A method of manufacturing a stator of a rotary electric machine is comprised of the following steps: providing a plurality of U-shaped basic conductor segments and a plurality of U-shaped connection conductor segments; forming the U-turn portions and straight portions into crossover portions, inserting the pair of straight portions of the basic and connection conductor segments into prescribed two slots of a stator core from one end thereof to extend from the other end, bending one of the pair of straight portions in the direction opposite to the other of the pair of extended straight portions so that the edges of straight portions extending from the prescribed slots can adjoin each other, connecting the adjoining edges to form a plurality of phase coils, and removing the U-turn portion of the connection conductor segments to form terminals of the phase coils.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present application is based on and claims priority from Japanese Patent Application Hei 11-96513 filed on Apr. 2, 1999, the contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a method of manufacturing a stator of a rotary electric machine. 
     2. Description of the Related Art 
     WO92/06527 (PCT/DE91/00738) discloses a method of manufacturing a stator, in which both U-shaped and I-shaped conductor segments are inserted into slots of a stator core from one or a first end of the stator core so that pairs of straight portions of the U-shaped conductor segments extend from the other or the second end of the stator core to be welded to one another, thereby forming a stator winding. One straight portion of each pair is inserted to a slot that is electric angle π radian spaced apart from the slots to which the other straight portion is inserted. The I-shaped conductor segments are inserted into slots separately to connect the straight portion of the U-shaped conductor segments at the second end of the stator and to extend from the first end of the stator. 
     However, it is difficult to retain the I-shaped conductor segments in the slots without additional retaining members because of the shape thereof. 
     SUMMARY OF THE INVENTION 
     A main object of the invention is to provide an improved method of manufacturing a stator of a rotary electric machine that solve the above-stated problem. 
     Another object of the invention is to provide a method of manufacturing such a stator without using the I-shaped conductor segments, in which connection work can be done easily. 
     According to a main feature of the invention, a method of manufacturing a stator of a rotary electric machine is comprised of the following steps: providing a plurality of U-shaped basic conductor segments and a plurality of U-shaped connection conductor segments; forming the U-turn portion and pair of straight portions of the basic and connection conductor segments into first crossover portions; inserting the pair of straight portions of the basic and connection conductor segments into prescribed two slots from one end of a stator core; bending each of the pair of straight portions of the basic and connection conductor segments extending from the other end in directions opposite to each other so that the edges of the straight portions extending from the prescribed two slots can adjoin each other; connecting the adjoining edges to form second crossover portions; and removing the U-turn portion of the connection conductor segments to respectively form terminals of the coils. 
     Thus, it is not necessary to insert I-shaped conductor segments in the slots. This can saves additional retaining members. In addition, the straight portions of the connection segments are extended to be connected on only one end of the stator core, so that connection work can be done easily. 
     According to an additional feature of the invention, each of the slots has outermost first slot layer, outer-middle second slot layer, inner-middle third slot layer, and innermost fourth slot layer. The basic conductor segments are comprised of comprise large segments having straight portions to be disposed in the first and fourth slot layers and small segments having the straight portions to be disposed in the second and third slot layers. The connection conductor segments are comprised of first connection segments having the U-turn portion to be removed and the straight portions to be disposed in the first and third slot layers and second connection segments having the straight portions to be disposed in the second and fourth slot layers. 
     This feature prevents each conductor segments from overlapping each other and reduces the number of specific segments. 
     According to another feature of the invention, the step of forming U-turn portion and the straight portions is comprised of a step of holding the straight portions to be disposed in the first and second slot layers by an outer ring and the straight portion to be disposed in the third and fourth slot layers by an inner ring coaxially rotatable within the outer ring and a step of rotating the outer and inner rings relative to each other in a prescribed angle. 
     This feature makes the forming step easy and reliable. 
     According to additional feature of the invention, the step of bending is comprised of a step of holding the edges of the straight portions extending from the four slot layers by separate four rings and a step of rotating the four rings relative to each other in a prescribed angle. 
     This feature also makes the bending step easy and reliable. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other objects, features and characteristics of the present invention as well as the functions of related parts of the present invention will become clear from a study of the following detailed description, the appended claims and the drawings. In the drawings: 
     FIG. 1 is a schematic diagram illustrating a method of manufacturing a stator core according to a preferred embodiment of the invention; 
     FIG. 2 is a fragmentary front view of a stator core having conductor segments in a slot; 
     FIG. 3 is a perspective view of conductor segments used in the method according to the preferred embodiment; 
     FIG. 4 is a schematic perspective view of a presser cylinder used in the method according to the preferred embodiment; 
     FIG. 5 is a schematic plan view of the presser cylinder shown in FIG. 4; 
     FIG. 6 is a schematic perspective view illustrating a step of the method according to the preferred embodiment; 
     FIG. 7A is a side view of the conductor segments in process, and 
     FIG. 7B s a cross-sectional view of the same viewed from radially outside; 
     FIG. 8 is a schematic diagram illustrating a step of the method according to the preferred embodiment; 
     FIG. 9 is a schematic diagram illustrating a step of the method according to the preferred embodiment; 
     FIG. 10 is a schematic diagram illustrating a step of the method according to the preferred embodiment; 
     FIG. 11 is a schematic diagram illustrating a step of the method according to the preferred embodiment; 
     FIG. 12 is a schematic diagram illustrating a step of the method according to the preferred embodiment; 
     FIG. 13 is a perspective view of a stator manufactured by the method according to the preferred embodiment; 
     FIG. 14 is a schematic diagram illustrating a step of the method according to the preferred embodiment; 
     FIG. 15 is a schematic diagram illustrating a step of the method according to the preferred embodiment; 
     FIG. 16 is a perspective view of the stator manufactured by the method according to the preferred embodiment; and 
     FIG. 17 is a schematic diagram illustrating connection of coils to form a stator winding. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A method of manufacturing a stator of a rotary machine according to a preferred embodiment of the invention is described with reference to the appended drawings. 
     As shown in FIG. 1, there are provided four kinds of U-shaped conductor segments having a pair of straight portions and a U-turn portion at the center thereof: basic large segments  310 , basic small segments  320 , first connection segments  330  and phase connection segments  340 . Then, the four kinds of the segments are inserted into rear twister  1 . 
     For instance, it is necessary for a three-phase stator having six phase coils and a stator core  200  having  96  slots  210  at the inner periphery thereof to provide  90  large segments  310 ,  90  small segments  320 , six first connection segments  330  and six second connection segments  340 . 
     Rear twister  1  is comprised of annular stationary frame  10 , outer ring  11  rotatably supported by the inner periphery of stationary frame  10  and inner ring  12  rotatably supported by outer ring  11 . Outer ring  11  and inner ring  12  respectively have  96  through holes  13  and  14 , which are coupled to correspond to  96  slots  210  of the stator core. That is, through holes  13  correspond to the radially outer half portions of slots  210 , and through holes  14  correspond to the radially inner half portions of the slots. 
     As shown in FIG. 2, each slot  210  is divided to four layers: first slot layer  211 , second slot layer  212 , third slot layer  213  and fourth slot layer  214 . The straight portions of the above stated segments are disposed at these four slot layers in the following manner: straight portions  311  of large segment  310  are respectively disposed in first and fourth slot layers  211  and  214 ; straight portions  321  of small segment are respectively disposed in second and third slot layers  212  and  213 ; straight portions  331  of first connection segment  330  are respectively disposed in first and third slot layers; and straight portions  341  of second connection segment  340  are respectively disposed in second and fourth slot layers  212 ,  214 . 
     As illustrated in FIG. 1, four kinds of segments  310 ,  320 ,  330  and  340  are respectively inserted into coupled through holes  13  and  14 . Each through hole  13  has a first hole layer that corresponds to first slot layer  211  and a second hole layer that corresponds to second slot layer  212 , and each through hole  14  has a third hole layer that corresponds to third slot layer  213  and a fourth hole layer that corresponds to fourth slot layer  214 . 
     As shown in FIG. 3, first and second connection segments are inserted into the same slots  210 . U-turn portion  342  of second connection segment  340  is bent in the circumferential direction so that one of straight portion  331  of first connection segment  330  can be inserted into through hole  14  (corresponding to third slot layer  213 ) without interference with U-turn portion  342 . 
     Each of first and second connection segments  330  and  340  is inserted between two of the six phase coils to connect both terminals thereof. Each first connection segment  330  will be cut at the U-turn portion  332  to form output leads of the two phase coils, which is described later. For this purpose, straight portions  331  of first connection segment  330  are longer than the other segments  310 ,  320  and  340 , as shown in FIGS. 1 and 3. 
     Subsequently, U-turn portion of each segment is pressed by presser cylinder  2 . Presser cylinder  2  has bottom  21 , which has four through holes  22 , one through hole  23  and a plurality of pairs of support poles  24 . Each through hole  22  passes one of first connection segments  330 . The circumferential sides of through hole  23  is twice as wide as that of through holes  22  so that it can pass circumferentially aligned two lead segments  330 , as shown in FIGS. 5 and 6. The pairs of support poles  24  extend downward from the peripheral portion of bottom  21  to support U-turn portions  312 ,  322 ,  332  and  342  of the respective segments. 
     As illustrated in FIGS. 6,  7 A and  7 B, presser cylinder  2  is put on the top of the U-turn portions  311 ,  321  and  341  so that  6  first connection segments  330  can project from through holes  22  and  23  and can be kept still. 
     Subsequently, outer ring  11  is turned in one direction and inner ring  12  is turned in the other direction, as illustrated in FIG. 8, to totally turn π radial in electric angle, so that U-turn portions  312  and  322  are formed into rear (upper end in FIG. 10) crossover portions as shown in FIGS. 9 and 10. On the other hand, U-turn portions  332  of first connection segments  330  are not deformed. 
     Then, the front end of stator  200  is put on front twister  4 . Front twister  4  is comprised of ring frame  40  and four coaxial rings  41 ,  42 ,  43  and  44 , as schematically illustrated in FIG.  11 . Four rings  41 - 44  are rotatably supported by ring frame, as shown in FIG.  10 . Ring  41  has a plurality of first through holes that correspond to first slot layers  211 , ring  42  has a plurality of second through holes that correspond to second slot layers  212 , ring  43  has a plurality of third through holes that correspond to third slot layers  213 , and ring  44  has a plurality of fourth through holes that correspond to fourth slot layers  214 . Rings  41 - 44  are set so that all the through holes are aligned with all the slots correctly. 
     Thereafter, a cluster of the formed segments  310 - 340  in the same order together with presser cylinder  2  are pulled out from rear twister  1 , so that they are inserted into the corresponding slots  210  of stator core  200  from the rear end thereof until the edges of straight portions  311 ,  321 ,  331  and  341  correctly extend from the front end of stator core  200  to be inserted into the corresponding through holes of rings  41 - 44 . 
     Subsequently, rings  41  and  43  are turned π/2 radian in electric angle in one direction, and rings  42  and  44  are turned π/2 radian in electric angle in the other direction to form the straight portions into front crossover portions, as illustrated in FIG.  11 . Presser cylinder  2  restricts the axial movement of the segment while they are bent. 
     As a result, the edge of straight portion  311  of large segment  310  disposed in the first slot layer  211  adjoins the edge of straight portion  321  of small segment  320  disposed in the second layer  212  that is π radian in electric angle shifted from the straight portion  311 , and the edge of straight portion  321  of large segment  320  disposed in the third slot layer  213  adjoins the edge of straight portion  311  of large segment  310  disposed in the fourth slot layer  214  that is π radian in electric angle shifted from the straight portion  321 . 
     The edge of straight portion  331  of first connection segment  330  disposed in the first slot layer  211  also adjoins the edge of straight portion  321  of small segment  320  disposed in the second layer  212  that is π radian in electric angle shifted from the straight portion  311 , and the edge of straight portion  331  of first connection segment  330  disposed in the third slot layer  213  adjoins the edge of straight portion  311  of large segment  310  disposed in the fourth slot layer  214  that is π radian in electric angle shifted from the straight portion  321 . Similarly, the edge of straight portion  341  of second connection segment  340  disposed in the second slot layer  212  adjoins the edge of straight portion  311  of large segment  310  disposed in the first slot layer  211  that is π radian in electric angle shifted from the straight portion  341 , and the edge of straight portion  341  of second connection segment  340  disposed in the fourth slot layer  214  adjoins the edge of straight portion  321  of small segment  320  disposed in the third slot layer  214  that is π radian in electric angle shifted from the straight portion  341 . 
     Then, the edges of the segments  310 - 340  are pulled out from rings  41 - 44 , and presser cylinder  2  is removed from segments  330 . 
     At the next step, the above-described adjoining edges of straight portions  311 ,  321 ,  331  and  341  are brought close to each other. 
     As illustrated in FIGS. 12 and 13, the adjoining edges are welded to form a nearly finished stator having three phase-windings. 
     Then, straight portions  331  of first connection segments  330  are cut at prescribed portion  333  and  334 , as illustrated in FIG.  14  and formed into lead members in a prescribed manner as illustrated in FIGS. 15 and 16. 
     Thus, a three-phase stator having terminals U and U′, V and V′, W and W′, X and X′, Y and Y′, and Z and Z′ connected in a parallel-star-connection are formed, as illustrated in FIG.  17 . 
     In the foregoing description of the present invention, the invention has been disclosed with reference to specific embodiments thereof. It will, however, be evident that various modifications and changes may be made to the specific embodiments of the present invention without departing from the broader spirit and scope of the invention as set forth in the appended claims. Accordingly, the description of the present invention in this document is to be regarded in an illustrative, rather than restrictive, sense.