Patent Publication Number: US-2023155462-A1

Title: Coil insertion device and coil insertion method

Description:
This application is based on and claims the benefit of priority from Japanese Patent Application No. 2021-137290, filed on 17 Nov. 2021, the content of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a coil insertion device and a coil insertion method. 
     Related Art 
     There has been conventionally known a method of mounting a coil into slots of a stator core by inserting the coil wound in an annular shape inside the stator core and pressing the coil outward from the inside against the slots of the stator core by a roller arranged eccentrically inside the coil to expand the coil in diameter (for example, see Japanese Patent No. 6390772). 
     Patent Document 1: Japanese Patent No. 6390772 
     SUMMARY OF THE INVENTION 
       FIG.  16    shows a state in which one coil  300  of a coil assembly mounted in stator core  400  expands in diameter by being pressed outward from inside, and inserted into slots  401  from inside of the stator core  400 . By coil end portions  301  being pressed, the coil  300  moves outward from inside of the stator core  400  while expanding in diameter. Along therewith, pitch P between straight portions  302  of the coil  300  inserted into slots  401  is widened, and the coil end portions  301  also spread in the circumferential direction of the stator core  400 . 
     However, when insertion of the coil  300  into the slots  401  is completed, and the pressure is released, a phenomenon occurs that the coil end portions  301  expanded in diameter decrease in diameter, trying to return to the state before the diameter expansion, due to springback of the coil  300  as shown in  FIG.  17   . When the coil end portions  301  are reduced in diameter to the state before the diameter expansion, the pitch P between straight portions  302  changes in a direction of being reduced, and there is a possibility that the coil  300  inserted in the slots  401  moves inward in the radial direction and returns to the inside of the stator core  400 . To address this, it is necessary to, for example, repeatedly press the coil  300 , which causes a disadvantage that the workability of coil insertion work is poor. 
     An object of the present invention is to provide a coil insertion device and a coil insertion method capable of preventing a coil from returning inward due to springback of coil end portions after insertion into slots and improving the workability of coil insertion work. 
     A first aspect of the present invention is directed to a coil insertion device (for example, a coil insertion device  1  described later) including coil diameter expanders (for example, the coil diameter expansion devices  5  described later), the coil diameter expanders being configured to insert a coil assembly (for example, a strip-shaped coil  100  described later) in a wound state into slots (for example, slots  22  described later) of a stator core (for example, a stator core  2  described later) by expanding the coil assembly in diameter from inside of the stator core. Each of the coil diameter expanders includes: a coil presser (for example, a coil presser  53  described later) that is arranged inside the coil assembly and presses coil end portions (for example, coil end portions  103  described later) of the coil assembly outward from inside to expand the coil end portions in diameter; and a restrictor (for example, a restrictor  55  described later) that is arranged outside the coil assembly, restricts outward movement of the coil end portions expanded in diameter by the coil presser, and sandwiches the coil end portions of the coil assembly inserted in the slots with the coil presser. 
     A second aspect is an embodiment of the first aspect. In the coil insertion device according to the second aspect, the restrictor has an inner peripheral surface (for example, an inner peripheral surface  55   a  described later) that may be perpendicular to an end face (for example, an end face  2   a  described later) of the stator core. 
     A third aspect is an embodiment, of the first aspect. In the coil insertion device according to the third aspect, the restrictor has an inner peripheral surface (for example, an inner peripheral surface  55   a ) as an inclined surface that may be inclined outward in a radial direction with an increase in distance from an end face (for example, an end face  2   a  described later) of the stator core. 
     A fourth aspect of the present invention is directed to a coil insertion method for inserting a coil assembly (for example, the strip-shaped coil  100  described later) in a wound state into slots (for example, the slots  22  described later) of a stator core (for example, the stator core  2  described later) by expanding the coil assembly in diameter from inside of the stator core. The method includes: pressing coil end portions (for example, the coil end portions  103  described later) of the coil assembly outward from inside to expand the coil end portions in diameter by a coil presser (for example, the coil presser  53  described later) arranged inside the coil assembly, thereby inserting the coil assembly into the slots; and restricting, by a restrictor (for example, the restrictor  55  described later) arranged outside the coil assembly, outward movement of the coil end portions expanded in diameter by the coil presser, and sandwiching the coil end portions of the coil assembly inserted in the slots between the coil presser and the restrictor. 
     According to the above (1), by sandwiching the coil end portions of the coil assembly inserted in the slots between the coil presser and the restrictor, it is possible to offset springback that occurs on the coil end portions. Therefore, it is possible to prevent the coil from returning inward due to springback of the coil end portions after the coil is inserted into the slots and improve the workability of coil insertion work. By the coil end portions being sandwiched between the coil presser and the restrictor, gaps among the coils laminated in the slots  22  are also eliminated. 
     According to the above (2), it is possible to apply pressing force equally to the coil end portions and lay out the coil end portions on the end face of the stator core in good order. 
     According to (3) above, since it is possible to cause the coil end portions to be inclined outward in the radial direction, it is possible to control the height of protrusion of the coil end portions and easily secure space on the inner diameter side of the coil end portions. 
     According to the above (4), by sandwiching the coil end portions of the coil assembly inserted in the slots between the coil presser and the restrictor, it is possible to offset springback that occurs on the coil end portions. Therefore, it is possible to prevent the coil from returning inward due to springback of the coil end portions after the coil is inserted into the slots and improve the workability of coil insertion work. By the coil end portions being sandwiched between the coil presser and the restrictor, gaps among the coils laminated in the slots are also eliminated. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a perspective view showing a coil insertion device according to an embodiment of the present invention; 
         FIG.  2    is a perspective view showing a stator core fixing jig to which a stator core is fixed and a coil winding jig, in the coil insertion device, the stator core fixing jig and the coil winding jig being disassembled; 
         FIG.  3    is a perspective view showing pieces of insulating paper mounted in slots of the stator core; 
         FIG.  4    is a front view showing an embodiment of a coil assembly; 
         FIG.  5    is a sectional view of the coil insertion device showing a state in which a coil diameter expansion device is being mounted to the coil assembly; 
         FIG.  6    is a plan view showing the coil assembly and a restrictor in the stator core; 
         FIG.  7    is a perspective view showing a state in which the coil diameter expansion device is being inserted inside a coil; 
         FIG.  8    is a side view showing a presser oi: the coil diameter expansion device in a diameter reduced state; 
         FIG.  9    is a front view showing the presser of the coil diameter expansion device in the diameter reduced state; 
         FIG.  10    is a side view showing the presser of the coil diameter expansion device in a diameter expanded state; 
         FIG.  11    is a side view showing the presser of the coil diameter expansion device in the diameter expanded state; 
         FIG.  12 A  is a diagram illustrating a state in which the coil is being pressed by the presser and inserted into the slots; 
         FIG.  12 B  is a diagram illustrating a state in which the coil is being pressed against the restrictor by the presser; 
         FIG.  12 C  is a diagram illustrating the state in which the coil is being pressed against the restrictor by the presser; 
         FIG.  12 D  is a diagram illustrating the state in which the coil is being pressed against the restrictor by the presser; 
         FIG.  13    is a sectional view showing a state in which the coil inserted into the slots is sandwiched between the presser and the restrictor; 
         FIG.  14    is a perspective view showing a stator; 
         FIG.  15 A  is a diagram illustrating a state in which the coil is being pressed against the restrictor by the presser; 
         FIG.  15 B  is a diagram illustrating the state in which the coil is being pressed against the restrictor by the presser; 
         FIG.  16    is a plan view showing a state in which the coil is being inserted into the slots; and 
         FIG.  17    is a diagram illustrating a state in which return of the coil end portions occurs due to springback. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. As shown in  FIGS.  1  and  2   , a coil insertion device  1  includes a stator core  2 , a stator core fixing jig  3  for fixing the stator core  2 , a coil winding jig  4  that is insertable inside the stator core  2  and has a strip-shaped coil  100  wound therearound in an annular shape, and coil diameter expansion devices  5  that cause the strip-shaped coil  100  wound around the coil winding jig  4  to move and expand in diameter. 
     As shown in  FIGS.  2  and  3   , the stator core  2  includes an annular portion  21  consisting of, for example, a laminate in which a plurality of thin core plates are laminated. The annular portion  21  has a through-hole  20  penetrating therethrough in an axial direction at the center thereof. The stator core  2  has a plurality of slots  22  penetrating therethrough in the axial direction of the stator core  2 . The slots  22  are arranged radially at regular intervals along the circumferential direction of the annular portion  21 , and have opening portions  22   a  that are open to the through-hole  20 . The stator core  2  of the present embodiment has seventy-two slots  22 . On the outer circumference of the annular portion  21  of the stator core  2 , there are six tab portions  23  protruding at regular intervals. 
     In the stator core  2 , an X direction in which the slots  22  are arranged is the circumferential direction as shown in  FIG.  2   . A Y direction along a direction radial from the center of the through-hole  20  is the radial direction. A Z direction is the axial direction. 
     As shown in  FIG.  2   , the stator core fixing jig  3  has a hexagonal cylinder shape having a dimension in the axial direction which is substantially equal to the dimension in the axial direction of the stator core  2 , and has, at the center thereof, a stator core insertion hole  31  in which the stator core  2  can be inserted and arranged. In the coil insertion device  1  of the present embodiment, the stator core fixing jig  3  is fixed to a center portion of a base  11  of the coil insertion device  1  such that the axial direction of the stator core  2  fixed in the stator core insertion hole  31  is a horizontal direction. 
     The stator core fixing jig  3  fixes the stator core  2  in the stator core insertion hole  31  at a predetermined position and in a predetermined posture. Specifically, as shown in FIG.  2 , the stator core fixing jig  3  has six core holding blocks  32  that, can move to protrude into and retract from the inside of the stator core insertion hole  31 , corresponding to positions of the six tab portions  23  of the stator core  2 . After the stator core  2  is inserted into the stator core insertion hole  31 , the stator core fixing jig  3  causes each of the core holding blocks  32  to protrude into the stator core insertion hole  31  by driving of an actuator such as a cylinder (not shown). As a result, as shown in  FIG.  2   , the core holding blocks  32  grip the tab portions  23  of the stator core  2 , respectively, to fix the stator core  2  in the stator core insertion hole  31  at the predetermined position and in the predetermined posture. 
     As shown in  FIG.  3   , pieces of insulating paper  24  are mounted in the slots  22  of the stator core  2 , respectively, in advance. Each piece of insulating paper  24  is formed by being folded in a substantially U-shape so as to follow the substantially U-shaped inner surface of the slot  22  when the stator core  2  is viewed in the axial direction. As shown in  FIG.  3   , the pieces of insulating paper  24  mounted in the slots  22  have cuff portions  24   a  protruding from the slots  22  in the axial direction of the stator core  2  at a predetermined height. The cuff portions  24   a  protrude from the slots  22  to both outer sides of the stator core  2  in the axial direction. 
     As shown in  FIG.  2   , on both end faces  3   a  of the stator core fixing jig  3  in the axial direction, to which the stator core  2  is fixed, a plurality of cuff guides  33  are attached such that the cuff guides  33  are radially arranged at regular intervals along the circumferential direction. Each of the cuff guides  33  is provided being movable along the radial direction of the stator core  2  by driving of the actuator such as a cylinder (not shown). Each cuff guide  33  is formed in an elongated thin-plate shape along the radial direction of the stator core  2 . Each of the cuff guides  33  is open to the inside of the stator core fixing jig  3  and, by sandwiching the cuff portion  24   a  of a corresponding piece of insulating paper  24  from both sides, supports the piece of insulating paper  24  in the slot  22  at the time of inserting the strip-shaped coil  100 . 
     As shown in  FIG.  2   , the coil winding jig  4  includes a substantially cylindrical jig main body  41 , a plurality of comb tooth portions  42  radially protruding from the outer periphery of the jig main body  41 , and a plurality of comb-tooth-shaped grooves  43  each of which is formed between comb tooth portions  42  adjacent to each other in the circumferential direction, and a shaft hole  44  opened in the center of the jig main body  41 . The comb tooth portions  42  and the comb-tooth-shaped grooves  43  are provided on both end portions in the axial direction of the jig main body  41 . The phases of the comb tooth portions  42  and the comb-tooth-shaped grooves  43  on both end portions of the jig main body  41  are aligned in the axial direction. The number of comb-tooth-shaped grooves  43  arranged in the circumferential direction of the jig main body  41  matches the number of slots  22  provided in the stator core  2 . Therefore, the coil winding jig  4  of the present embodiment has seventy-two comb-tooth-shaped grooves  43 . In order that the coil winding jig  4  can be inserted inside the annular portion  21  of the stator core  2 , the coil winding jig  4  is formed so that the outer diameter of the coil winding jig  4  defined by the positions of the tips of the comb tooth portions  42  is smaller than the inner diameter of the stator core  2 . 
     The strip-shaped coil  100  is wound around the coil winding jig  4  in an annular shape. As shown in  FIG.  4   , the strip-shaped coil  100  is a coil assembly configured with an elongated strip-shaped continuous wave-wound coil formed by flat type conducting wires  101  made of copper, aluminum or the like each of which has a substantially rectangular section. As the coil assembly, a plurality of segment coils formed in a substantially U-shape can be used, in addition to the wave-wound coil. However, at the time of setting a coil into slots of a stator core, the continuous wave-wound coil does not require a common dominant technique for forming a plurality of coil segments and welding ends of the coil segments after insertion into the slots, thereby eliminating, for example, the need to use a high-purity copper material for the coil in order to cope with thermal processing of welded portions. Therefore, it becomes possible to use recycled copper material that includes impurities, and it is possible to contribute to realization of reuse of resources. Moreover, since the wave-wound coil does not require welding, weight reduction of the coil is possible, and it is possible to reduce the weight of a rotary electric machine using the coil. When the rotary electric machine is mounted on a hybrid car, it is possible to, by the vehicle weight being reduced, reduce carbon dioxide and reduce the harmful effect on the global environment. 
     The strip-shaped coil  100  has a plurality of straight portions  102  and a plurality of coil end portions  103 . The straight portions  102  are parts to be inserted into the slots  22  of the stator core  2 , and they extend substantially linearly and are arranged in parallel at regular intervals. The coil end portions  103  are arranged at positions nearer to the side ends of the strip-shaped coil  100  than the straight portions  102 , and alternately connect end portions on one side of adjacent straight portions  102  and end portions on the other side of adjacent straight portions  102  in chevron shapes. The coil end portions  103  are parts which are arranged so as to protrude from the slots  22  in the axial direction of the stator core  2  when the strip-shaped coil  100  is mounted in the slots  22  of the stator core  2 . The strip-shaped coil  100  of the present embodiment is formed in an elongated strip-shape by bundling six flat type conducting wires  101  with the plurality of straight portions  102  and the plurality of coil end portions  103  that are formed by folding, such that the straight portions  102  are arranged side by side in parallel at regular intervals. 
     The coil winding jig  4  winds the strip-shaped coil  100  in many layers by successively inserting the straight portions  102  of the strip-shaped coil  100  into the comb-tooth-shaped grooves  43  before being inserted inside the stator core  2 . As a result, as shown in  FIG.  2   , the coil winding jig  4  around which the strip-shaped coil  100  is wound in an annular shape is configured. 
     The coil winding jig  4  around which the strip-shaped coil  100  is wound in an annular shape is held in a predetermined posture at a predetermined position in the stator core insertion hole  31  by the coil diameter expansion devices  5  arranged on both sides of the stator core fixing jig  3  with the stator core fixing jig  3  being sandwiched therebetween. The coil diameter expansion device  5  of the present embodiment constitutes a coil diameter expander. As shown in  FIG.  1   , the coil diameter expansion devices  5  face the coil winding jig  4  inserted inside the stator core  2  in the axial direction. 
     As shown in  FIGS.  1  and  5   , the coil insertion device  1  is provided with a pair of support boards  12  which are erected on the base  11  fixing the stator core fixing jig  3  in a manner of facing each other, sandwiching the stator core fixing jig  3  therebetween. The coil diameter expansion devices  5  protrude in a horizontal direction from the support boards  12 , respectively, toward the coil winding jig  4  inserted inside the stator core  2 . Each of the coil insertion devices  5  is provided to be movable in directions of coining into contact with and being separated from the coil winding jig  4  by the support board  12  linearly moving on the base  11  by driving of a motor or the like not shown. 
     As shown in  FIGS.  5  and  7   , each coil diameter expansion device  5  has, in the center thereof, a main shaft portion  51  extending from the support board  12  toward the coil winding jig  4  inserted inside the stator core  2 . At the tip of the main shaft portion  51 , a holder  52  for holding the coil winding jig  4  at a predetermined position and in a predetermined posture inside the stator core  2  is provided. The holder  52  has a shaft protruding portion  522  protruding from the center of a circular end plate portion  521  arranged at the tip of the main shaft portion  51 , and a positioning protruding portion  523  protruding in the same direction as the shaft protruding portion  522  from the end plate portion  521  on the outside in the radial direction of the shaft protruding portion  522 . The shaft protruding portion  522  fits into the shaft hole  44  of the coil winding jig  4 . The positioning protruding portion  523  fits into one positioning hole  45  provided on the outside of the shaft hole  44  in the radial direction of the coil winding jig  4 . 
     The positioning hole  45  of the coil winding jig  4  and the positioning protruding portion  523  of the holder  52  are provided, being positioned in advance so that the phase of the slots  22  of the stator core  2  fixed to the stator core fixing jig  3  and the phase of the comb-tooth-shaped grooves  43  of the coil winding jig  4  inserted inside the stator core  2  match each other when the positioning hole  45  and the positioning protruding portion  523  are fitted to each other. Therefore, when the coil diameter expansion device  5  moves to the stator core fixing jig  3 , and the shaft protruding portion  522  and the positioning protruding portion  523  of the holder  52  are fitted into the shaft hole  44  and the positioning hole  45  of the coil winding jig  4 , respectively, the coil winding jig  4  is held in a state where the comb-tooth-shaped grooves  43  are in phase with the slots  22  of the stator core  2 , as shown in  FIG.  6   . As a result, the insides of the slots  22  of the stator core  2  communicate with the insides of the comb-tooth-shaped grooves  43  of the coil winding jig  4 , respectively, in the radial direction. 
     The coil diameter expansion device  5  has a coil presser  53  on the outer peripheral side of the main shaft portion  51 . The coil presser  53  includes a movable cylinder portion  531  that fits to the outer peripheral side of the main shaft portion  51 , a plurality of movable arm portions  532  arranged on the further outer peripheral side of the movable cylinder portion  531 , and a plurality of piece members  533  provided at the tips of the movable arm portions  532 , respectively. 
     The movable cylinder portion  531  has a length shorter than the length of the main shaft portion  51 , and is provided to be slidable along the axial direction of the main shaft portion  51  by driving of an actuator  54  such as a cylinder arranged behind the support board  12 . 
     The plurality of movable arm portions  532  extend along the axial direction of the main shaft portion  51 , and are arranged on the outer peripheral side of the movable cylinder portion  531  at regular intervals in the circumferential direction. The coil presser  53  of the present embodiment has twelve movable arm portions  532  arranged along the circumferential direction of the main shaft portion  51 . Twelve guide rails  121  radially arranged outward in the radial direction with the main shaft portion  51  as the center are provided on the surface of the support board  12 . Rear ends  532   b  of the movable arm portions  532  are attached so as to be movable along the guide rails  121 . The movable arm portions  532  bend from the guide rails along the axial direction of the movable cylinder portion  531  and extend to the vicinity of the outer periphery of the holder  52 . Tips  532   a  of the movable arm portions  532  are connected to the outer peripheral surface on the tip side of the movable cylinder portion  531  via every two link portions  534  which are rotatably attached. 
     As shown in  FIGS.  8  to  11   , the piece members  533 , each of which has a substantially fan shape, are provided at the tips of the movable arm portions  532 , respectively. Therefore, the coil presser  53  of the present embodiment has the twelve piece members  533  arranged in an annular shape. Each of the piece members  533  has a pair of fitting protrusions  533   a  at one end portion in the circumferential direction of the coil presser  53  (in the circumferential direction of the plurality of annular piece members  533 ) and has a pair of fitting grooves  533   b  to be fitted to an adjacent pair of fitting protrusions  533   a  at the other end portion in the circumferential direction. The paired fitting protrusions  533   a  are arranged in parallel in the axial direction of the coil presser  53 , and protrude in parallel in the circumferential direction, being continuous with the outer peripheral surface  530  of the coil presser  53 . The twelve piece members  533  are annularly arranged on the outer peripheral side of the holder  52  by the pair of fitting protrusions  533   a  and the pair of fitting grooves  533   b  of piece members  533  adjacent to each other in the circumferential direction being fitted to each other. The circumferential direction of the coil presser  53  is a C direction shown in  FIGS.  8  to  11   . 
       FIG.  5    shows a state in which the movable cylinder portion  531  is retracted to the rear end side (the support board  12  side) of the main shaft portion  51 . At this time, the movable arm portions  532  move to the inner end sides of the radial guide rails  121 , and are arranged so as to be closest to the outer, peripheral surface of the movable cylinder portion  531 . As a result, as shown in  FIGS.  8  and  9   , the coil presser  53  is into a state of being most reduced in diameter, causing the twelve piece members  533  to be in close contact with one another. The outer diameter of the coil presser  53  when the piece members  533  have been reduced in diameter is smaller than the inner diameter of the coil end portions  103  cylindrically protruding in the axial direction from the coil winding jig  4  around which the strip-shaped coil  100  is wound. The coil diameter expansion device  5  is inserted into the coil end portions  103  cylindrically protruding in the axial direction of the coil winding jig  4  while the plurality of piece members  533  of the coil presser  53  are reduced in diameter, and the coil winding jig  4  is held by the holder  52 . 
     When the movable cylinder portion  531  advances to the coil winding jig  4  along the main shaft portion  51  by driving of the actuator  54 , the link portions  534  connected to the movable cylinder portion  531  are turned so as to protrude outward in the radial direction of the movable cylinder portion  531 , thereby translating the movable arm portions  532  outward along the guide rails. As a result, the twelve movable arm portions  532  are separated from the movable cylinder portion  531  outward in the radial direction. At this time, as shown in  FIGS.  10  and  11   , the coil presser  53  causes adjacent piece members  533  to move to be separated from each other and is into a state of most, expanded in diameter. The outer diameter of the coil presser  53  expanded in diameter is larger than the outer diameter of the coil winding jig  4 . By the coil presser  53  expanding in diameter, the coil, end portions  103  are moved outward from inside. 
     As shown in  FIGS.  9  and  11   , when the coil presser  53  is most expanded in diameter, adjacent piece members  533  separate from each other, but a pair of fitting protrusions  533   a  protrude in the circumferential direction between the piece members  533 . The fitting protrusions  533   a  have not completely come out of the fitting grooves  533   b  of the adjacent piece member  533 , maintaining fitting in the fitting grooves  533   b.  Therefore, the plurality of piece members  533  in an annular shape expanded in diameter have a closed outer peripheral surface  530  that is continuous in the circumferential direction. Therefore, when the coil presser  53  is viewed in the circumferential direction, adjacent piece members  533  are continuous with each other by a pair of fitting protrusions  533   a,  and such a groove portion (a gap) that penetrates the coil presser  53  in the radial direction is not formed. 
     The coil diameter expansion device  5  further has a restrictor  55  as shown in  FIGS.  1 , and  5  to  7   . Though the restrictor  55  of the present embodiment is formed in a cylindrical shape, the restrictor  55  may be formed in a plate shape having a circular opening in the center. The restrictor  5   b  may be divided in a plurality of parts in the circumferential direction. In this case, the restrictor  55  may be provided so as to be movable in the radial direction relative to the stator core  2 . The restrictor  55  is omitted in  FIG.  2   . In  FIG.  6   , the stator core fixing gig  3  is omitted. 
     The restrictor  55  is arranged concentrically with the stator core  2  outside the coil end portions  103  of the strip-shaped coil  100 . Specifically, on both end faces  2   a  of the stator core  2  in the axial direction, the restrictors  55  are arranged concentrically with the strip-shaped coil  100  in a wound state of being wound around the coil winding jig  4  so as to surround the whole periphery of the outside of the annular strip-shaped coil  100  as shown in  FIGS.  5  and  6   . In the present embodiment, an inner peripheral surface  55   a  of the restrictor  55  is arranged on slightly outside the position of the slots  22  of the stator core  2  on the outer diameter side. 
     The restrictor  55  of the present embodiment is attached to each of the end faces  2   a  of the stator core  2  after the stator core  2  is attached to the stator core fixing jig  3  so as to sandwich the plurality of cuff guides  33  with the end face  2   a  for example, by a mounting mechanism not shown. Further, the restrictor  55  may be concentrically arranged on the outer circumference of the coil presser  53  of the coil diameter expansion device  5  and configured to, when the coil presser  53  is inserted inside the strip-shaped coil  100 , be simultaneously arranged outside the strip-shaped coil  100 , though it is not shown. 
     The restrictor  55  is arranged outside the slots  22  of the stator core  2  and, as described later, sandwiches the coil end portions  103  with the piece members  533  of the coil presser  53  when the strip-shaped coil  100  is inserted into the slots  22  by the coil presser  53  expanding in diameter. The inner peripheral surface  55   a  of the restrictor  55  of the present embodiment forms a surface perpendicular to the end face  2   a  of the stator core  2 . The inner peripheral surface  55   a  is a surface perpendicular to a moving direction of the strip-shaped coil  100  and a surface parallel to an axial direction Z of the stator core  2 . 
     Next, a method for inserting the strip-shaped coil  100  wound around the coil winding jig  4  into the slots  22  from the inside of the stator core  2  fixed to the stator core fixing jig  3 , in the coil insertion device  1  will be described with reference to  FIGS.  12 A to  12 D , and  FIG.  13   .  FIGS.  12 A to  12 D  show only one end face  2   a  side of the stator core  2 . 
     First, the coil winding jig  4  around which the strip-shaped coil  100  is annularly wound is inserted into the inside of the stator core  2  fixed to the stator core fixing jig  3 . After that, the cuff guides  33  move inward in the radial direction by driving of the actuator not shown, and sandwich and support the cuff portions  24   a  of the pieces of insulating paper  24  in the slots  22 . As a result, the pieces of insulating paper  24  are positioned at predetermined positions in the slots  22 , respectively. 
     As shown in  FIGS.  5  and  7   , by the pair of coil diameter expansion devices  5  moving to the coil winding jig  4 , the coil winding jig  4  inserted inside the stator core  2  is sandwiched and held by the holders  52  of the coil diameter expansion devices  5 . At this time, the piece members  533  of the coil presser  53  are in a state of being reduced in diameter more than the inner diameter of the annular strip-shaped coil  100  as shown in  FIGS.  3  and  9   , and are inserted inside the coil end portions  103  of the strip-shaped coil  100 . 
     After that, the piece members  533  of the coil presser  53  move in a manner of expanding in diameter from the diameter-reduced state by driving of the actuator  54  as shown in  FIGS.  10  and  11   . As a result, the coil end portions  103  of the strip-shaped coil  100  wound around the coil winding jig  4  are pressed outward from the inside by the piece members  533  of the coil presser  53 . The whole periphery of the strip-shaped coil  100  pressed by the coil presser  53  gradually expands. Along therewith, the straight portions  102  move to the slots  22  of the stator core  2  which communicate with the comb-tooth-shaped grooves  43 , being guided by the comb-tooth-shaped grooves  43  of the coil winding jig  4 . The straight portions  102  of the strip-shaped coil  100  are inserted into the slots  22  of the stator core  2  from the opening portions  22   a  of the slots  22  without interfering with the slots  22  ( FIG.  12 A ). 
     When the coil presser  53  further expands, the coil end portions  103  of the strip-shaped coil  100  are pressed by the piece members  533  of the coil presser  53  and come into contact with end portions of the slots  22  on the outer diameter side. Since the inner peripheral surface  55   a  of the restrictor  55  is arranged slightly outside the positions of the slots  22  on the outer diameter side, the coil end portions  103  and the inner peripheral surface  55   a  of the restrictor  55  are slightly separated from each other ( FIG.  12 B ). 
     When the coil end portions  103  are further pressed after coming into contact with the end portions of the slots  22  on the outer diameter side, the coil end portions  103  come into contact with the inner peripheral surface  55   a  of the restrictor  55  while being transformed to be tilted outward in the radial direction ( FIG.  12 C ). 
     After that, the coil end portions  103  are pressed against the inner peripheral surface of the restrictor  55  by pressing force of the piece members  533  of the coil presser  53  expanding in diameter. As a result, the coil end portions  103  are sandwiched between the piece members  533  and the restrictor  55  ( FIG.  12 D ). 
     When the coil end portions  103  are sandwiched between the piece members  533  and the restrictor  55 , as shown in  FIG.  13   , the position of the outer diameter side of the coil end portions  103  is restricted to an outer diameter restriction position Ya defined by the inner peripheral surface  55   a  of the restrictor  55 . Since the restrictor  55  is arranged in position outside the slots  22 , the coil end portions  103  are compressed against the inner peripheral surface  55   a  of the restrictor  55  on the outside in the radial direction by being sandwiched between the outer peripheral surface  530  of the piece members  533  of the coil presser  53  and the inner peripheral surface  55   a  of the restrictor  55 . The position of the compressed coil end portions  103  on the inner diameter side moves outside an inner diameter reference position Yb before the compression in the radial direction. 
     By the coil end portions  103  being compressed between the piece members  533  of the coil presser  53  expanding in diameter and the restrictor  55  for a predetermined time, stress over plastic deformation is applied to the coil end portions  103 . As a result, the direction of residual stress that occurs on the coil end portions  103  by diameter expansion changes, and springback is offset. As a result, the strip-shaped coil  100  inserted in the slots  22  is prevented from returning inward due to spring back. Further, since outward movement of the coil end portions  103  is restricted by the restrictor  55 , occurrence of looseness of the strip-shaped coil  100  on the front side in the movement direction is prevented, and gaps among the straight portions  102  laminated in the slots  22  are eliminated. Furthermore, since the straight portions  102  are prevented from excessively hitting a back portion  24   b  of the pieces of insulating paper  24  in the slots  22 , the pieces of insulating paper  24  are prevented from being crushed. 
     As a result, a stator  200  in which the strip-shaped coil  100  is prevented from returning is obtained as shown in  FIG.  14   . 
     Since the inner peripheral surface  55   a  of the restrictor  55  is a surface perpendicular to the end face  2   a  of the stator core  2 . It is possible to apply pressing force equally to the coil end portions  103  and lay out the coil end portions  103  on the end face  2   a  of the stator core  2  in good order. However, the inner peripheral surface  55   a  of the restrictor  55  is not limited to a perpendicular surface. The inner peripheral surface  55   a  may be an inclined surface that is inclined outward in the radial direction with an increase in distance from the end face  2   a  of the stator core  2  in the axial direction. 
       FIGS.  15 A and  15 B  show a state in which the coil end portions  103  are pressed against the restrictor  55  the inner peripheral surface  55   a  of which is an inclined surface. The coil end portions  103  pressed by the piece members  533  of the coil presser  53  come into contact with the bottom edge of the inclined inner peripheral surface  55   a  of the restrictor  55  (the edge on the end face  2   a  side of the stator core  2 ) ( FIG.  15 A ). After that, when the coil end portions  103  are further pressed, the coil end portions  103  are compressed while being inclined outward in the radial direction along the inclined inner peripheral surface  55   a  of the restrictor  55  ( FIG.  15 B ). The compressed coil end portions  103  are formed in a shape inclined outward in the radial direction as the coil end portions  103  are farther away from the end face  2   a  of the stator core  2  in the axial direction. Therefore, the height of protrusion of the coil end portions  103  is controlled, and space on the inner diameter side of the coil end portions  103  (such as space for inserting a rotor) can be easily secured. 
     In the case of such a restrictor  55 , the outer peripheral surface of the piece members  533  of the coil presser  53  may be also configured as an inclined surface that is inclined outward in the radial direction with an increase in distance from the end face  2   a  of the stator core  2  in the axial direction, similarly to the inner peripheral surface  55   a  of the restrictor  55 . 
     In other words, according to the coil insertion device  1  of the present embodiment, the following effects can be obtained. That is, the coil insertion device  1  of the present embodiment is a device including the coil diameter expansion device  5  that inserts the strip-shaped coil  100  in a wound state into the slots  22  of the stator core  2  by expanding the strip-shaped coil  100  in diameter from the inside of the stator core  2 . The coil diameter expansion device  5  is provided with the coil presser  53  arranged inside the strip-shaped coil  100 , the coil presser  53  pressing the coil end portions  103  of the strip-shaped coil  100  outward from inside to expand the coil end portions  103  in diameter and the restrictor  55  arranged outside the strip-shaped coil  100 , the restrictor  55  restricting outward movement of the coil end portions  103  expanded in diameter by the coil presser  53  and sandwiching the coil end portions  103  of the strip-shaped coil  100  inserted in the slots  22  with the coil presser  53 . According to the above, by sandwiching the coil end portions  103  of the strip-shaped coil  100  inserted in the slots  22  between the coil presser  53  and the restrictor  55 , it is possible to offset springback that occurs on the coil end portions  103 . Therefore, it is possible to prevent the strip-shaped coil  100  from returning inward due to springback of the coil end portions  103  after the strip-shaped coil  100  is inserted into the slots  22  and, therefore, improve workability of coil insertion work. By the coil end portions  103  being sandwiched between the coil presser  53  and the restrictor  55 , gaps among the straight portions  102  of the strip-shaped coil  100  laminated in the slots  22  are also eliminated. Since the straight portions  102  are prevented from excessively hitting a back portion  24   b  of the pieces of insulating paper  24  in the slots  22 , the pieces of insulating paper  24  are prevented from being crushed. 
     If the inner peripheral surface  55   a  of the restrictor  55  is a surface perpendicular to the end face  2   a  of the stator core  2 , it is possible to apply pressing force equally to the coil end portions  103  and lay out the coil end portions  103  on the end face  2   a  of the stator core  2  in good order. 
     If the inner peripheral surface  55   a  of the restrictor  55  is an inclined surface inclined outward in the radial direction with an increase in distance from the end face  2   a  of the stator core  2 , it is possible to control the height of protrusion of the coil end portions  103  and easily secure space on the inner diameter side of the coil end portions  103 . 
     Furthermore, according to the coil insertion method of the present embodiment, the following effects can be obtained. That is, the coil insertion method of the present embodiment is a method of inserting the strip-shaped coil  100  in a wound state into the slots  22  of the stator core  2  by expanding the strip-shaped coil  100  in diameter from the inside of the stator core  2 . The method includes: pressing the coil end portions  103  of the strip-shaped coil  100  outward from inside to expand the coil end portions  103  in diameter by the coil presser  53  arranged inside the strip-shaped coil  100  to insert the strip-shaped coil  100  into the slots  22 ; and restricting outward movement of the coil end portions  103  expanded in diameter by the coil presser  53 , by the restrictor  55  arranged outside the strip-shaped coil  100  and sandwiching the coil end portions  103  of the strip-shaped coil  100  inserted in the slots  22  between the coil presser  53  and the restrictor  55 . According to the above, by sandwiching the coil end portions  103  of the strip-shaped coil  100  inserted in the slots  22  between the coil presser  53  and the restrictor  55 , it is possible to offset springback that occurs on the coil end portions  103 . Therefore, it is possible to prevent the strip-shaped coil  100  from returning inward due to springback of the coil end portions  103  after the strip-shaped coil  100  is inserted into the slots  22  and, therefore, improve workability of coil insertion work. By the coil end portions  103  being sandwiched between the coil presser  53  and the restrictor  55 , gaps among the straight portions  102  of the strip-shaped coil  100  laminated in the slots  22  are also eliminated. Since the straight portions  102  are prevented from excessively hitting a back portion  24   b  of the pieces of insulating paper  24  in the slots  22 , the pieces of insulating paper  24  are prevented from being crushed. 
     The coil insertion device  1  of the embodiment described above is configured so that the axial directions of the stator core  2  and the coil winding jig  4  are set to a horizontal direction, but the coil insertion device  1  may be configured so that the axial directions of the stator core  2  and the coil winding jig  4  are set to any direction other than the horizontal direction, such as a vertical direction. 
     EXPLANATION OF REFERENCE NUMERALS 
       1 : Coil insertion device 
       2 : Stator core 
       2   a:  End face 
       22 : Slot 
       5 : Coil diameter expansion device (Coil diameter expander) 
       53 : Coil presser 
       55 : Restrictor 
       55   a:  Inner peripheral surface 
       100 : Strip-shaped coil (Coil assembly) 
       103 : Coil end portion