Abstract:
A method of manufacturing coils that includes forming a predetermined number of U-shaped conductor segments. The U-shaped conductor segments are twisted using first twisting formation jig composed of a first inside ring and a first outside ring and a second twisting formation jig composed of a second inside ring and a second outside ring. The U-shaped conductor segments that are twist formed in radially inward directions are radially compressed. The U-shaped conductor segments are twist formed by holding one of each pair of straight portions by holding slots that are circumferentially formed in each of a first and second inside rings and first and second outside rings. Next, first and second inside rings and the first and second outside rings are coaxially rotated.

Description:
[0001]     This is a Division of application. Ser. No. 11/036,353 filed Jan. 18, 2005. The disclosure of the prior application is hereby incorporated by reference herein in its entirety. 
     
    
     CROSS REFERENCE TO RELATED APPLICATION  
       [0002]     The present application is based on and claims priority from Japanese Patent Application 2004-22976, filed Jan. 30, 2004, the contents of which are incorporated herein by reference.  
       BACKGROUND OF THE INVENTION  
       [0003]     1. Field of the Invention  
         [0004]     The present invention relates to a coil forming apparatus which forms coils to be mounted in slots of a stator core of a rotary electric machine from U-shaped conductor segments and a method of forming such coils.  
         [0005]     2. Description of the Related Art  
         [0006]     In a rotary electric machine such as a generator or a motor, a plurality of conductor segments is mounted into slots of a stator core to form a stator coil through a step of welding the respective ends of conductor segments in a well-known manner.  
         [0007]     As shown in  FIG. 11A , a hairpin-like conductor segment  100  having a U-turn portion and a pair of parallelly extending flat straight portions  120 ,  130  are preliminarily formed. Subsequently, the straight portions  120 ,  130  are twisted and pulled away from each other so that flat and wider surfaces become parallel to each other, as shown in  FIG. 11B . Thereafter, the straight portions  120 ,  130  are inserted into a pair of slots of a stator core  310 , as shown in  FIG. 14 .  
         [0008]     U.S. Pat. No. 6,425,175 B1 discloses a pair of U-shaped conductor segments  100   a,    100   b,  which are shown in  FIG. 12  of this application and a twisting formation apparatus that twists a turn portion  110  of the conductor segments  100   a,    100   b,  as shown in  FIG. 13 . The twisting formation apparatus has coaxially coupled inside ring  210  and an outside ring  220 . Each of the rings  210 ,  220  has a plurality of circumferentially disposed holding slots whose cross-section is rectangular. The number of the holding slots of the inside and outside rings is the same as the number of slots of a stator core  310 , which is shown in  FIG. 14 .  
         [0009]     Although the above twisting formation apparatus is good for manufacturing a stator having four conductors each slot, it can not be applied to manufacturing a stator having six or more conductors each slot because the outermost turn portion of threefold U-shaped conductor segments excessively projects from a stator core, resulting in a stator having a very large axial size and a very heavy weight.  
       SUMMARY OF THE INVENTION  
       [0010]     It is an object of the invention to provide a coil forming apparatus that can manufacture a stator having six or more conductors each slot that is not very large in axial size or in weight.  
         [0011]     According to a feature of the invention, a coil forming apparatus for manufacturing coils of a stator of a rotary electric machine having a predetermined number of stator slots includes a twisting formation unit for twist-forming a predetermined number of U-shaped conductor segments each of which has a pair of parallelly extending straight portions and a turn portion connecting the straight portion. The twisting formation unit includes a first twisting formation jig composed of a first inside ring and a first outside ring and a second twisting formation jig composed of a second inside ring and a second outside ring. Each of the first and second inside rings has the same number of circumferentially disposed holding slots as the stator slots to hold one of each pair of straight portions. Each of the first and second outside rings also has the same number of circumferentially disposed holding slots as the stator slots to hold the other of each pair of straight portions. The first and second inside rings and the first and second outside rings are coaxially coupled to shift relative circumferential position between the inside rings and the outside rings by a predetermined angle to twist the turn portions.  
         [0012]     In addition to the above feature, at least one of the first and second twisting formation jigs can twist pairs of U-shaped conductor segments that have different-sized turn portions. The twisting formation unit may include knocking bars for discharging the conductor segments from the first and second twisting formation jigs, and the first and second twisting formation jigs are preferably movable relative to the knocking bars when discharging the conductor segments from the first and second twisting formation jigs.  
         [0013]     The coil forming apparatus may further include a compressing formation unit for radially compressing the U-shaped conductor segment that are twist-formed by the twisting formation unit in radially inward directions. The formation unit of this coil forming apparatus may include a metal core having a cylindrical outer periphery for setting a diameter of an inscribed circle of the conductor segments, a plurality of guiding arrow members respectively disposed in radial directions at equal intervals to form guide spaces between the guiding arrow members, a plurality of thrusting arrow members respectively disposed in the guide spaces to compress the conductor members in radially inner directions when straight portions of the conductor segments are disposed in the guide spaces, means for radially moving the thrusting arrow members to provide a cylindrical space for accommodating straight portions of the conductor segments around the cylindrical outer periphery of the metal core when moving the thrusting arrow members radially outward. In this coil forming apparatus the means for radially moving may include spring members each of which is disposed between one of the thrusting arrow members and one of said guiding arrow members.  
         [0014]     Another object of the invention is to provide a method of forming coils of a stator of a rotary electric machine.  
         [0015]     According to another feature of the invention, a method includes a step of twist-forming all the straight portions by the first and second twisting formation units that are described above, a step of discharging all the straight portions from the first and second twisting formation units, a step of sending all the straight portions from the first and second twisting formation units to the guide spaces and a step of pushing all the straight portions into the cylindrical space and pushing at least a radially outside portion of the straight portions to radially inside portion thereof to be close to each other. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]     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:  
         [0017]      FIG. 1  is a longitudinally cross-sectional view illustrating a coil forming apparatus according to the preferred embodiment of the invention; forming apparatus according to the preferred embodiment of the invention;  
         [0018]      FIG. 2  is a longitudinally cross-sectional view illustrating a stator manufactured by the coil forming apparatus according to a preferred embodiment of the invention and a rotor;  
         [0019]      FIG. 3  is a perspective view illustrating a conductor segment to be inserted in a slot of the stator shown in  FIG. 2 ;  
         [0020]      FIG. 4  is a longitudinally cross-sectional longitudinal view of a twisting formation unit of the coil forming apparatus according to the preferred embodiment;  
         [0021]      FIG. 5  is a fragmentary plan view illustrating a portion of the twisting formation unit;  
         [0022]      FIG. 6  is a schematic diagram illustrating a step of twisting formation;  
         [0023]      FIG. 7  is a longitudinally cross-sectional view illustrating the twisting formation jig;  
         [0024]      FIG. 8  is a schematic cross-sectional plan view illustrating a portion of a compressing formation unit;  
         [0025]      FIG. 9  is a plan view illustrating a cam mechanism;  
         [0026]      FIG. 10  is a side view illustrating a stator core holder;  
         [0027]      FIGS. 11A and 11B  are perspective views illustrating a prior art step of manufacturing a conductor segment;  
         [0028]      FIGS. 12A and 12B  are perspective views illustrating a prior art step of manufacturing a pair of conductor segments;  
         [0029]      FIG. 13  is a perspective view illustrating a prior art twisting formation unit; and  
         [0030]      FIG. 14  is a longitudinally cross-sectional view illustrating a stator manufactured by the prior art coil forming apparatus.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0031]     A coil forming apparatus  1  according to a preferred embodiment of the present invention will be described with reference to the appended drawings.  
         [0032]     As shown in  FIG. 1 , the coil forming apparatus  1  is to form a stator coil  3  mounted in a stator core  2  of a generator or a motor and includes a twisting formation unit  4  and a compressing formation unit  5 .  
         [0033]     The stator coil  3  is composed of a first group of first conductor segments  60 , a second group of second conductor segments  61  and a third group of third conductor segments  62 .  
         [0034]     As shown in  FIG. 3 , a U-shaped conductor segment  6  ( 60 ,  61  or  62 ) before forming has a pair of parallelly extending straight portions  6   a,    6   b  and a turn portion  6   c  that connects the straight portions  6   a,    6   b.  As shown in  FIG. 7 , the turn portion  6   c  of the first conductor segment  60  is different in radius from the second conductor segments  60  and same as the third conductor segment  62 .  
         [0035]     The twisting formation unit  4  includes a first twisting formation jig  7  that forms the first group of the first conductor segments  60  and the second group of the second conductor segments  61 , a second twisting formation jig  8  that forms the third group of the third conductor segments  62 , a twisting lever  9  that causes the first and second twisting formation jigs  7 ,  8  twisting operation, knocking bars  10  that discharge the conductor segments  60 - 62  from the twisting formation jigs  7 ,  8 , etc. The twisting formation unit  4  is fixed to a base plate  11  and supported by a supporting post  12  so that it can move up and down.  
         [0036]     The first twisting formation jig  7  has a coaxially coupled pair of an inside ring  7   a  and an outside ring  7   b,  and the second twisting formation jigs  8  has a coaxially coupled pair of inside ring  8   a  and an outside ring  8   b.  The inside ring  8   a  of the second twisting formation jig  8  is also coaxially disposed around the outside ring  7   b  of the first twisting formation jig  7 , so that all the rings  7   a,    7   b,    8   a,    8   b  are coaxially disposed, as shown in  FIG. 5 . In other words, the second twisting formation jig  8  is disposed around the first twisting formation jig  7 .  
         [0037]     The inside ring  7   a  of the first twisting formation jig  7  has as many outwardly open inside holding slots  7   c  in the circumferential direction thereof at equal intervals as the slots of the stator core to which the conductor segments  6  are mounted, and the outside ring  7   b  of the first twisting formation jig  7  has the same number of inwardly open outside holding slots  7   d  to correspond to the holding slots  7   c.  The inside ring  8   a  of the second twisting formation jig  8  has the same number of outwardly open inside holding slots  8   c  as the holding slots  7   c,  and the outside ring  8   b  of the second twisting formation jig  8  has the same number of inwardly open outside holding slots  8   d  to correspond to the holding slots  8   c.    
         [0038]     The inside holding slot  7   c  of the first twisting formation jig  7  has a rectangular cross-section whose radial sides (or depth) are long enough to accommodate the straight portions  6   a  of radially aligned two conductor segments  60 ,  61 . The outside holding slot  7   d  of the first twisting formation jig  7  has a rectangular cross-section whose radial sides are long enough to accommodate the straight portions  6   b  of the radially aligned first and second conductor segments  60 ,  61 .  
         [0039]     The inside holding slot  8   c  of the second twisting formation jig  8  has a rectangular cross-section whose radial sides are long enough to accommodate the straight portion  6   a  of the third conductor segments  62 . The outside holding slot  7   d  of the second twisting formation jig  8  has a rectangular cross-section whose radial sides are long enough to accommodate the straight portion  6   b  of the conductor segments  62 . Therefore, the radial depth of the holding slots  8   c,    8   d  of the second twisting formation jig  8  is about a half the radial depth of the holding slots  7   c,    7   d  of the first twisting formation jig  7 .  
         [0040]     The first and the second twisting formation jigs  7 ,  8  are adjusted so that all the holding slots  7   c,    7   b,    8   c,    8   d  can be disposed at the same angular or circumferential position. Then, the first and second conductor segments  60 ,  61 , which are coupled so that the second conductor segment  61  mounts on the first conductor segment  60 , are set to the first twisting formation jig  8 , and the third conductor segments  62  are set to the second twisting formation jig  8 , as shown in  FIG. 7 .  
         [0041]     The twisting lever  9  is linked with the outside ring  7   b  of the first twisting formation jig  7  and the outside ring  8   b  of the second twisting formation jig  8  to turn the outside rings  7   b,    8   b  in the same direction. On the other hand, the inside ring  7   a  of the first twisting formation jig  7  and the inside ring  8   a  of the second twisting formation jig  8  are fixed to the supporting post  12 . Therefore, the inside ring  7   a  of the first twisting formation jig  7  turns relative to the outside ring  7   b  of the same, and the inside ring  8   a  of the second twisting formation jig  7  turns relative to the outside ring  8   b  of the same.  
         [0042]     The knocking bars  10  are disposed under the first and second twisting formation jigs  7 ,  8  at positions opposite the respective holding slots  7   c,    7   d,    8   c,    8   d.    
         [0043]     The first and second twisting formation jigs  7 ,  8  are supported by the supporting post  12  so that they can be moved by an up-down lever  13  up and down relative to the knocking bars  10 . When the first and second twisting formation jigs  7 ,  8  are moved down, the first, second and third conductor segments are knocked by the knocking bars to move upward from the first and second twisting formation jigs  7 ,  8 .  
         [0044]     The compression formation unit  5  is supported by supporting poles  23 , as shown in  FIG. 1 , to eliminate gaps G formed between the second conductor segments  61  and the third conductor segments  62 , as shown in  FIG. 8 . The compression formation unit  5  includes a metal core  14 , a plurality of coil springs  15 , a plurality of guiding arrow members  16 , a plurality of thrusting arrow members  18 , a cam plate  19 , etc.  
         [0045]     The metal core  14  is a cylindrical member that has an outer periphery for setting the diameter of the inscribed circle of the first group of the first conductor segments  60 .  
         [0046]     The plurality of guiding arrow members  16  is disposed around the metal core  14  in radial directions at equal intervals so as to provide guide spaces  17  between guiding arrow members  16  and to radially move back and forth, as shown in  FIG. 9 . When the guiding arrow members  16  move back, a cylindrical space S is provided around the metal core  14  to take the first—third conductor segments  60 - 62  therein, as shown in  FIG. 1 .  
         [0047]     The plurality of thrusting arrow members  18  is moved by the cam plate  19  in radial directions. As shown in  FIG. 9 , the cam plate  19  has a plurality of cam grooves  20  and a plurality of cam pins  21 , each of which engages one of the cam groove and links with the thrusting arrow members  18 . The cam grooves  20  are formed straight but slantingly disposed in two ring zones of the cam plate  19  so that the cam pins  21  and the thrusting arrow members  18  can move back and forth in radial directions of the cam plate  19  when the cam plate  19  turns back and forth.  
         [0048]     Each coil spring  15  is disposed between one of the thrusting arrow members  18  and one of the guiding arrow members  16 , as shown in  FIG. 8 , to push the guiding arrow member  16  radially inward when the thrusting arrow member  18  moves radially inward.  
         [0049]     With the above described coil forming apparatus, a stator coil  3  is formed as follows.  
         [0050]     a) At first, the first conductor segment  60  and the second conductor segment  61  are set together so that the second conductor segment  61  mounts on the first conductor segment  60 . Then sets of the first and second conductor segments  60 ,  61  are mounted in the first twisting formation unit  7  so that the inside straight portions (e.g.  6   a ) are inserted into the inside holding slots  7   c  and the outside straight portions (e.g.  6   b ) are inserted into the outside holding slots  7   d.  In the same manner, the third conductor segments  62  are mounted in the second twisting formation unit  8  so that the inside straight portions (e.g.  6   a ) are inserted into the inside holding slots  8   c  and the outside straight portions (e.g.  6   b ) are inserted into the outside holding slots  8   d.    
         [0051]     b) Thereafter, the twisting lever  9  is turned right, as indicated by an arrow in  FIG. 1 , to turn the outside ring  7   b  of the first twisting formation jig  7  and the outside ring  8   b  of the second twisting formation jig  8  relative to the inside ring  7   a  of the first twisting formation jig  7  and the inside ring  8   a  of the second twisting formation jig  8 . Therefore, turn portions  6   c  are twisted.  
         [0052]     c) The up-down lever  13  is moved down as indicated by an arrow in  FIG. 1  to move down the first and second twisting formation jigs  7 ,  8 . Therefore, the knocking bars  10  are moved up relative to the twisting formation jigs  7 ,  8  to almost discharge the first, second and third conductor segments  60 - 62  except the lower end thereof.  
         [0053]     d) The compressing formation unit  5  with the cylindrical space S being provided is moved down to take the conductor segments  60 - 62  into the cylindrical space S. At this time, the guiding arrow members  16  are retracted to avoid interference with the third conductor segments  62 .  
         [0054]     e) The cam plate  19  is turned by a turning lever  22  to move the thrusting arrow members  18  in radially inner directions, so that the guiding arrow members  16  are pushed by the coil springs radially inward to insert the straight portions  6   a,    6   b  of the conductor segments  60 - 62  into the respective guide spaces  17 .  
         [0055]     f) The up-down lever  13  is further moved down to completely discharge the first, second and third conductor segments  60 - 62  from the first and second twisting formation jigs  7 ,  8  and take the same into the guide spaces  17 , as shown in  FIG. 8 .  
         [0056]     g) The thrusting arrow members  18  are further moved to push the third conductor segments  62  to eliminate the gaps G and bring the conductor segments  62  to be close to the second conductor segments  61 , so that six straight portions  6   a,    6   b  of the conductor segments are aligned in each guide space  17  in a radial direction.  
         [0057]     h) The compressing formation unit  5  is moved up while the first, second and third conductor segments  60 - 62  stay in the guide spaces.  
         [0058]     i) The twisting formation unit  4  is removed from the base plate  11 , and a stator core holder  24  is fixed to the base plate  11 , to which a stator core  2  is set as shown in  FIG. 10 .  
         [0059]     j) The first, second and third conductor segments  60 - 62  in the guide spaces  17  are pushed out, so that six straight portions  6   a,    6   b  of the conductor segments  60 - 62  are inserted into each slot  6  of the stator core  2 .  
         [0060]     Thus it is not necessary to twist three folded conductor segments at the same time, so that the coil ends do not become excessively long in the axial direction.  
         [0061]     It is possible to add fourth conductor segments to the third conductor segments  62  in the same manner as described above. It is also possible to add the third twisting formation unit to form six and seven conductor segments in the same manner as described above.  
         [0062]     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 scope of the invention as set forth in the appended claims. Accordingly, the description of the present invention is to be regarded in an illustrative, rather than a restrictive, sense.