Manufacturing method of coil for rotating electric machine

Abstract

To provide a manufacturing method of a coil for a rotating electric machine that is less likely to cause unnecessary distortion when forming grooves on side surfaces facing in opposite directions.SOLUTION: A coil for a rotating electric machine has a first side surface and a second side surface facing in mutually opposite directions, and the first side surface and the second side surface are each provided with a groove 50 along the longitudinal direction. In manufacturing such a coil for a rotating electric machine, while the groove 50 is being press-molded into one of the first side surface and the second side surface, press-molding of the groove 50 into the other side surface is started.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a coil for a rotating electrical machine.

Background Art

[0002] As a rotating electrical machine such as an electric motor or a generator, there is one in which a rotor is rotatably disposed inside the radial direction of an annular stator. The stator includes a stator core and a coil (coil for a rotating electrical machine) wound around the stator core. The stator core is integrally formed, for example, of a cylindrical back yoke and a plurality of teeth protruding radially inward from the back yoke. Slots are formed between a plurality of adjacent teeth in the circumferential direction. The coil is wound around each tooth through slots disposed on both sides of the teeth.

[0003] In this type of rotating electrical machine, since the coil becomes hot during use, it is desired to efficiently cool the coil. As a method for efficiently cooling the coil of a rotating electrical machine, a method of flowing a coolant around the coil is known (see, for example, Patent Document 1).

[0004] In the rotating electrical machine described in Patent Document 1, a coil (coil for a rotating electrical machine) wound around the teeth of a stator core is formed by a rectangular wire. And, on the side surface (the side surface facing the direction intersecting the extending direction) of the insertion portion inserted into the slot of the coil, a substantially arc-shaped concave groove is formed. Coolant introduced from one end side in the axial direction of the stator core flows into this concave groove, and the coolant flows out to the other end side in the axial direction. The coil is efficiently cooled by the coolant flowing through the concave groove at this time.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] By the way, when forming the concave grooves on both side surfaces facing the opposite directions of the coil as described above, the coil is placed on the mounting table with one side surface facing upward, and in this state, the male mold for groove formation is lowered to press-mold the concave groove on one side surface of the coil. Then, after completing the press-molding of the concave groove on one side surface, the coil is inverted so that the other side surface of the coil faces upward, and the concave groove is press-molded by the male mold in the same manner as on the one side surface with respect to the other side surface.

[0007] When forming concave grooves on two side surfaces facing the opposite directions of the coil in this way, when pressing the male mold against one side surface (the surface facing upward), a compressive load acts between the mountain-shaped pressing portion of the male mold pressed against the upper surface at approximately the center in the width direction of the coil and the flat upper surface of the mounting table. At this time, since the other side surface of the coil (the surface facing downward) abuts against the upper surface of the mounting table in a wide area in the width direction, a large stress acts between the approximately central region in the width direction of the upper surface where the male mold is pressed and the wide area in the width direction where the upper surface of the mounting table abuts in the cross section of the coil. That is, the portion where the large stress acts spreads in a tapered shape downward in the cross section of the coil, or branches into two in the width direction and is distributed.

[0008] Then, after inverting the coil so that the other side surface of the coil faces upward and pressing the male mold against that surface, a compressive load similarly acts between the pressing portion of the upper male mold and the upper surface of the mounting table. At this time, in the cross section of the coil, a portion where a large stress acts will be distributed between the approximately central region in the width direction of the upper surface where the male mold is pressed and the wide area in the width direction where the upper surface of the mounting table abuts, but a part of the stress generated when forming the concave groove on one side surface remains in the cross section of the coil. For this reason, in the cross section of the coil after the molding is completed, the stress generated when forming the concave groove on one side surface and the stress generated when forming the concave groove on the other side surface remain widely in a combined form. Therefore, when forming concave grooves on two side surfaces facing the opposite directions of the coil by the above method, the coil is likely to generate a large strain.

[0009] Therefore, the present invention aims to provide a method for manufacturing a rotating electrical machine coil in which unnecessary distortion is less likely to occur when forming concave grooves on side surfaces facing in opposite directions.

Means for Solving the Problems

[0010] In order to solve the above problems, the method for manufacturing a rotating electrical machine coil according to the present invention employs the following configuration. That is, the method for manufacturing a rotating electrical machine coil according to the present invention has a first side surface (for example, side surface s1 in the embodiment) and a second side surface (for example, side surface s2 in the embodiment) facing in opposite directions to each other, and concave grooves (for example, concave groove 50 in the embodiment) along the longitudinal direction are provided on the first side surface and the second side surface, respectively. The method is characterized in that when pressing and molding the concave groove on one of the first side surface and the second side surface, the pressing and molding of the concave groove on the other side surface is started.

[0011] In the method for manufacturing a rotating electrical machine coil according to the present invention, the pressing and molding for forming the concave groove on the first side surface and the pressing and molding for forming the concave groove on the second side surface are performed in a temporally overlapping manner. At this time, the direction of the load applied to the first side surface to form the concave groove on the first side surface and the direction of the load applied to the second side surface to form the concave groove on the second side surface are opposite to each other. Therefore, a portion with high stress is concentrated in the region within the coil that linearly connects the pressing portion for forming the concave groove on the first side surface and the pressing portion for forming the concave groove on the second side surface, and it is difficult for the portion with high stress to spread to other portions. Therefore, after the processing of the concave groove is completed, unnecessary distortion is less likely to occur in the unnecessary portions within the cross-section of the coil. Further, when this method is adopted, stress is less likely to occur in the unnecessary portions within the cross-section of the coil during processing, so the load required for processing can be reduced, and smooth processing of the rotating electrical machine coil can be realized.

[0012] It is also possible to make at least one of the start timing of the pressing and molding for the first side surface and the second side surface and the end timing of the pressing and molding for the first side surface and the second side surface coincide.

[0013] In this case, when the start timing of the pressing forming for the first side surface and the second side surface is made to coincide, the deformation load that rapidly increases at the initial stage of the start of pressing can be concentrated between the pressing portions of both side surfaces, and the diffusion of the high-stress portion to the surroundings can be prevented. Further, when the end timing of the pressing forming for the first side surface and the second side surface is made to coincide, even if there is some variation in deformation between the first side surface and the second side surface before the end of the pressing forming, the variation in deformation can ultimately be corrected.

[0014] The start timing of the pressing forming for the first side surface and the second side surface and the end timing of the pressing forming for the first side surface and the second side surface may be made to coincide with each other.

[0015] In this case, the deformation load that rapidly increases at the initial stage of pressing can be concentrated between the pressing portions of the first and second side surfaces, and the variation in deformation between the first side surface and the second side surface can ultimately be corrected.

[0016] When performing the pressing forming on the first side surface and the second side surface, the pair of other side surfaces facing in the opposite direction other than the first side surface and the second side surface may be clamped by a support die (for example, the support die 74 of the embodiment).

[0017] In this case, by clamping the pair of other side surfaces by the support die, the rotation of the rotating electrical machine coil during the pressing forming can be suppressed. Therefore, the pressing forming of the rotating electrical machine coil can be performed with high accuracy.

[0018] It is desirable that the support die is spring-biased so as to be displaceable when a load is input.

[0019] In this case, since the support die that clamps the rotating electrical machine coil is spring-biased so as to be displaceable, the impact associated with the input of a large load during the pressing forming can be absorbed by the function of the spring. Therefore, when this method is adopted, the dropping and displacement of the coil from the processing device can be eliminated, and the processing of the coil can be stably performed.

Advantages of the Invention

[0020] In the method for manufacturing a coil for a rotating electrical machine according to the present invention, when a concave groove is press-molded on one of the first side surface and the second side surface, the press-molding of the concave groove on the other side surface is started. Therefore, the press-molding of the first side surface and the press-molding of the second side surface can be executed with temporal overlap. And the press-molding of the first side surface and the press-molding of the second side surface can be performed from directions facing each other. Accordingly, when the method for manufacturing a coil for a rotating electrical machine according to the present invention is adopted, unnecessary strain is less likely to occur in the coil when forming concave grooves on side surfaces facing in opposite directions. Thus, the product quality of the coil for a rotating electrical machine can be further improved.

Brief Description of the Drawings

[0021]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0022] Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of a rotating electrical machine 1 of the present embodiment. The rotating electrical machine 1 of this embodiment includes a stator 10 and a rotor 11. The stator 10 and the rotor 11 are housed inside a rotating electrical machine case 12. The stator 10 is fixed inside the rotating electrical machine case 12 by fastening with bolts 13 or the like. The stator 10 includes a cylindrical stator core 14 and a plurality of coils 15 wound around the stator core 14. The rotor 11 is rotatably arranged on the radially inner side of the stator core 14 (stator 10). Note that the coil 15 constitutes a rotating electrical machine coil in this embodiment.

[0023] The rotor 11 has a permanent magnet (not shown) attached in the vicinity of its outer peripheral surface. Also, the rotor 11 is integrally rotatably supported on a rotating shaft 17 via a sleeve 16. The rotating shaft 17 serves as an output shaft when the rotating electrical machine 1 is used as a motor, and serves as a power input shaft when the rotating electrical machine 1 is used as a generator. The rotating shaft 17 and the sleeve 16 are rotatably supported on the rotating electrical machine case 12 via bearings 18. In the following description, the direction parallel to the rotation axis line C of the rotor 11 is referred to as the axial direction, the rotation direction of the rotor 11 is referred to as the circumferential direction, and the radial direction of the rotor 11 orthogonal to the axial direction and the circumferential direction is referred to as the radial direction.

[0024] Annular first side cases 19 and second side cases 20 are arranged on one end side and the other end side in the axial direction of the stator core 14. The main parts of the first side cases 19 and the second side cases 20 are formed by the rotating electrical machine case 12.

[0025] The first side case 19 covers, from the outside, one axial end face of the stator core 14 and the exposed portion of the coil 15 protruding from that end face. The first side case 19 forms an annular first liquid chamber 21 together with one axial end face of the stator core 14. An introduction port 24 for introducing the coolant 23 into the first liquid chamber 21 is formed in the first side case 19. The introduction port 24 is connected to the circulation circuit 25 of the coolant 23. The coolant 23 introduced into the first liquid chamber 21 cools the exposed portion of the coil 15 protruding from one end face of the stator core 14, and then passes through the inside of the stator core 14 and flows into the other end side in the axial direction of the stator core 14.

[0026] The second side case 20 covers, from the outside, the other axial end face of the stator core 14 and the exposed portion of the coil 15 protruding from that end face. The second side case 20 forms an annular second liquid chamber 22 together with the other axial end face of the stator core 14. The coolant 23 introduced into the first liquid chamber 21 flows into the second liquid chamber 22 through the inside of the stator core 14. The coolant 23 introduced into the second liquid chamber 22 cools the exposed portion of the coil 15 protruding from the other end face of the stator core 14. A discharge port 26 for discharging the coolant 23 in the second liquid chamber 22 to the outside is formed in the second side case 20. The discharge port 26 is connected to the circulation circuit 25 of the coolant 23. The coolant 23 that has cooled the coil 15 in the second liquid chamber 22 is returned from the discharge port 26 to the circulation circuit 25.

[0027] A feed pump P is connected in the middle of the circulation circuit 25. A heat exchanger OC that cools the coolant 23 by heat exchange with the outside air is connected upstream of the feed pump P in the circulation circuit 25. The downstream side of the feed pump P is connected to the introduction port 24. Also, the upstream side of the heat exchanger OC in the circulation circuit 25 is connected to the discharge port 26.

[0028] Figure 2 is a cross-sectional view of the rotating electrical machine 1 taken along line II-II in Figure 1. The stator core 14 is formed, for example, by axially laminating a plurality of electromagnetic steel sheets. As shown in FIG. 2, the stator core 14 is integrally formed with a cylindrical back yoke 27 and a plurality of teeth 28 that project radially inward from the inner peripheral portion of the back yoke 27. The back yoke 27 is formed such that the center of the cylinder coincides with the rotation axis C.

[0029] The teeth 28 are arranged at intervals in the circumferential direction. The teeth 28 are formed in a T shape when viewed from the axial direction. That is, the teeth 28 are integrally formed with a tooth body 29 that projects radially inward from the inner peripheral portion of the back yoke 27 and a flange portion 30 that projects from the inner radial end of the tooth body 29 to both sides in the circumferential direction.

[0030] A slot 31 with an open inner diameter is formed between the teeth 28 adjacent to each other in the circumferential direction. The slot 31 is formed surrounded by the opposing side walls of the adjacent teeth 28 and the inner peripheral wall of the back yoke 27. The side walls of each tooth 28 are formed by the side portion of the tooth body 29 and the side portion of the flange portion 30. The portion of the slot 31 formed by the side portions of the left and right tooth bodies 29 has a substantially constant width. Also, the width of the portion of the slot 31 formed by the side portions of the left and right flange portions 30 is narrower than the width of the portion formed by the side portions of the left and right tooth bodies 29. Note that the inner diameter opening 40 of each slot 31 is formed sandwiched between the tip portions of the flange portions 30 on the left and right (both sides in the circumferential direction) of the slot 31. Also, each slot 31 penetrates the stator core 14 in the axial direction.

[0031] The coils 15 are provided, for example, in three phases of U-phase, V-phase, and W-phase. The coils 15 are configured, for example, by connecting a plurality of segment coils to each other. The outer surface of the metal conductor 41 of the coil 15 is covered by an insulating film 42. Also, the coil 15 is formed by a flat wire. That is, the shape of the cross section orthogonal to the extending direction of the coil 15 is formed in a substantially rectangular shape.

[0032] Each coil 15 is inserted axially into the slot 31 of the stator core 14 and wound around the corresponding tooth 28 in that state. Hereinafter, the portion of the coil 15 inserted into the slot 31 will be referred to as the "insertion portion 15a", and the portion exposed outside the slot 31 and routed in the direction of the other slot 31 will be referred to as the "routing portion 15b".

[0033] As shown in FIG. 2, in each slot 31, the insertion portions 15a of the coil 15 are inserted in multiple stages. The plurality of insertion portions 15a inserted into the same slot 31 are arranged in a row along the radial direction. In the present embodiment, for example, five insertion portions 15a are inserted into the same slot 31. However, the number of insertion portions 15a inserted into the same slot 31 is not limited to this and can be arbitrarily set.

[0034] The plurality of insertion portions 15a inserted and arranged in each slot 31 are bundled so as to be arranged in a row in parallel, and their surroundings are covered by a sheet of the foamable insulating member 43. The foamable insulating member 43 can be, for example, one in which a foamable adhesive is arranged (applied) on the surface of an electrically insulating base sheet (the surface facing outward in the state of covering the insertion portion 15a), and a non-foamable adhesive is arranged (applied) on the back surface of the base sheet. The foamable insulating member 43 is inserted and arranged in the corresponding slot 31 together with these insertion portions 15a in a state of covering the surroundings of the plurality of insertion portions 15a. The foamable insulating member 43 foams in the corresponding slot 31 by performing heat treatment or the like later. As a result, a part of the outer surface of the foamable insulating member 43 is adhered to the inner wall of the slot 31.

[0035] Even after the insertion portion 15a of the coil 15 and the foamable insulating member 43 are arranged in the slot 31 as described above, a gap for communicating the one axial end side and the other end side of the stator core 14 is secured inside the slot 31. This gap constitutes a coolant passage 44 for flowing the coolant introduced into the first liquid chamber 21 toward the second liquid chamber 22 side. Specifically, the gap constituting the coolant passage 44 is, for example, a gap between the inner surface of the foamable insulating member 43 and the insertion portion 15a, a gap between adjacent insertion portions 15a, a gap between the outer surface of the foamable insulating member 43 and the inner wall of the slot 31, and the like. The coolant 23 flowing through the coolant passage 44 in the slot 31 absorbs the heat of the insertion portion 15a of the coil 15.

[0036] On the side surfaces of each insertion portion 15a arranged in the slot 31 that face the radially inner side and the radially outer side, concave grooves 50 extending along the axial direction of the stator core 14 are formed. The concave grooves 50 are formed to be recessed in a substantially arc shape toward the central region in the width direction of the insertion portion 15a. When a plurality of insertion portions 15a are arranged in the slot 31 together with the foamable insulating member 43, the concave grooves 50 form gaps (flow-through gaps) extending substantially along the axial direction between the opposing side surfaces of the insertion portions 15a adjacent in the radial direction and between the side surface of the insertion portion 15a and the inner surface of the foamable insulating member 43. In this embodiment, the concave grooves 50 formed on the side surface of the coil 15 constitute coolant flow grooves. Also, in this embodiment, the concave grooves 50 are formed in the lead portion 15b of the coil 15 so as to be continuous with the concave grooves 50 of the insertion portion 15a.

[0037] Also, as shown in FIG. 1, the first side case 19 on one end side in the axial direction of the stator core 14 includes a first inner peripheral wall 32 facing the first liquid chamber 21. The first inner peripheral wall 32 protrudes cylindrically from the radially inner end of the end side wall 33 of the first side case 19 located at the outer end in the axial direction of the first liquid chamber 21 toward one end face in the axial direction of the rotor 11. In the case of this embodiment, the first inner peripheral wall 32 is composed of a peripheral wall main body portion 12a integrally formed with the rotating electrical machine case 12 (end side wall 33) and a separate cylindrical member 34 attached to the outer peripheral surface on the extending end side of the peripheral wall main body portion 12a. The space between the peripheral wall main body portion 12a and the cylindrical member 34 is sealed by an annular seal member 60. However, the first inner peripheral wall 32 may be entirely integrally formed with the rotating electrical machine case 12 (end side wall 33).

[0038] Further, the second side case 20 on the other end side in the axial direction of the stator core 14 includes a second inner peripheral wall 35 facing the second liquid chamber 22. The second inner peripheral wall 35 protrudes cylindrically from the radially inner end of the end side wall 36 of the second side case 20 located at the outer end in the axial direction of the second liquid chamber 22 toward the other end face in the axial direction of the rotor 11. In the case of this embodiment, the second inner peripheral wall 35 is integrally formed with the rotating electrical machine case 12 (end side wall 36). However, the second inner peripheral wall 35 may be configured by a peripheral wall main body portion integral with the rotating electrical machine case 12 (end side wall 36) and a separate cylindrical member, similar to the first inner peripheral wall 32.

[0039] On the outer peripheral surfaces of the outer peripheral surface of the first inner peripheral wall 32 of the first side case 19 and the outer peripheral surface of the second inner peripheral wall 35 of the second side case 20, an annular partition wall 37, which is a cylindrical cover member, is installed. The annular partition wall 37 is formed of, for example, a resin material. However, the annular partition wall 37 can also be formed of other materials such as a metal material. The annular partition wall 37 has a first end portion 37f facing the inside of the first liquid chamber 21, a second end portion 37s facing the inside of the second liquid chamber 22, and a partition wall main body portion 37b between the first end portion 37f and the second end portion 37s and facing the inner peripheral surface of the stator core 14. The first end portion 37f is formed with the same inner diameter as the partition wall main body portion 37b. The second end portion 37s has a reduced diameter in a stepped manner with respect to the partition wall main body portion 37b at an intermediate portion in the extending direction.

[0040] The inner peripheral surface of the first end portion 37f is slidably fitted to the outer peripheral surface of the cylindrical member 34 of the first inner peripheral wall 32. An annular groove 38f is formed on the outer peripheral surface of the cylindrical member 34, and an annular seal member 39f such as an O-ring is mounted in the annular groove 38f. The space between the cylindrical member 34 (first inner peripheral wall 32) and the first end portion 37f (annular partition wall 37) is hermetically sealed by the seal member 39f. In the present embodiment, the first end portion 37f constitutes a guide member that guides the coolant in the first liquid chamber 21 to the slot 31 on one axial end side of the stator core 14 inside the first liquid chamber 21.

[0041] The inner peripheral surface of the reduced diameter portion of the second end portion 37s is slidably fitted to the outer peripheral surface of the second inner peripheral wall 35. An annular groove 38s is formed on the outer peripheral surface of the second inner peripheral wall 35, and an annular seal member 39s such as an O-ring is mounted in the annular groove 38s. The space between the second inner peripheral wall 35 and the second end portion 37s (annular partition wall 37) is hermetically sealed by the seal member 39s.

[0042] As described above, the first end portion 37f of the annular partition wall 37 is liquid-tightly fitted to the first inner peripheral wall 32 of the first side case 19, and the second end portion 37s is liquid-tightly fitted to the second inner peripheral wall 35 of the second side case 20. The annular partition wall 37 partitions the radially inner region of the stator core 14 attached inside the rotating electrical machine case 12 from the outer peripheral surface of the rotor 11. Therefore, even if the coolant 23 leaks from the slot 31 of the stator core 14 into the radially inner region, it is possible to prevent the coolant 23 from flowing into the outer peripheral surface side of the rotor 11.

[0043] Further, on the outer peripheral surface of the first end portion 37f of the annular partition wall 37, a bulging portion that bulges radially outward from the outer peripheral surface of the partition wall main body portion 37b is provided. The end portion of this bulging portion on the stator core 14 side stands radially outward in a stepped manner with respect to the outer peripheral surface of the partition wall main body portion 37b. This standing end face is in contact with the end face on one axial end side of the stator core 14.

[0044] As shown in FIG. 2, the outer peripheral surface of the partition wall main body portion 37b of the annular partition wall 37 is maintained in contact with the inner peripheral surface of the stator core 14. Further, the inner peripheral surface of the partition wall main body portion 37b of the annular partition wall 37 faces the outer peripheral surface of the rotor 11 with a minute gap therebetween so as not to be in contact with the outer peripheral surface of the rotor 11.

[0045] The foamed insulating member 43 accommodated and disposed in each slot 31 of the stator core 14 together with the plurality of insertion portions 15a of the coil 15 enters the opening 40 on the radially inner side of the slot 31 when the foamed adhesive on the outer surface side foams due to heating or the like. The foamed adhesive that has entered the opening 40 adheres to the outer peripheral surface of the annular partition wall 37 disposed outside (radially inner side) of the opening 40. As a result, the peripheral wall main body portion 12a of the annular partition wall 37 is adhesively fixed to the foamed insulating member 43 inside the plurality of slots 31 through the opening 40 of the slot 31.

[0046] When a current continuously flows through the coil 15 during operation of the rotating electrical machine 1 having the above configuration, the coil 15 generates heat and becomes high temperature. At this time, the coolant 23 is introduced into the first liquid chamber 21 of the rotating electrical machine 1 from the circulation circuit 25 through the introduction port 24. The coolant 23 introduced into the first liquid chamber 21 cools one end side region (the routed portion 15b) of the coil 15 exposed to the outside from one axial end side of the stator core 14 by flowing in the first liquid chamber 21. Further, the coolant 23 flows from one axial end side to the other end side through the plurality of slots 31 (coolant passages 44 in the slots 31) of the stator core 14 and flows into the second liquid chamber 22. The coolant flowing in the slot 31 cools the inserted portion 15a of the coil 15 inserted in the slot 31. Further, the coolant 23 that has flowed into the second liquid chamber 22 cools the other end side region of the coil 15 exposed to the outside from the other axial end side of the stator core 14, and then is returned to the circulation circuit 25 through the discharge port 26.

[0047] As described above, the stator 10 of the rotating electrical machine 1 is always immersed in the coolant 23 in the rotating electrical machine case 12, and in this state, the coolant 23 in the rotating electrical machine case 12 is replaced through the circulation circuit 25. Therefore, the coil 15 of the stator 10 is efficiently cooled by the coolant 23.

[0048] Next, a method for manufacturing the coil 15 wound around the stator core 14 as described above will be described with reference to FIGS. 3 to 6. In FIGS. 3 to 6, the insulating film 42 of the coil 15 shown in FIG. 2 for easy understanding is omitted. Further, in the following description, the "width direction" of the coil 15 means the direction orthogonal to the vertical direction in the cross section (cross section in the direction orthogonal to the extending direction) of the coil 15.

[0049] FIG. 3 is a perspective view of a processing device 70 for forming concave grooves 50 in the side surfaces s1 and s2 of the coil 15, and FIG. 4 is a schematic cross-sectional view of the processing device 70. The coil 15 has four side surfaces s1, s2, s3, and s4 that are orthogonal to the extending direction (longitudinal direction). Two side surfaces s1 and s2 are arranged facing opposite directions to each other, and the remaining two side surfaces s3 and s4 face in a direction orthogonal to the side surfaces s1 and s2 and are arranged facing opposite directions to each other. The concave grooves 50 are respectively formed on the side surfaces s1 and s2 that face opposite directions to each other. In the present embodiment, the side surface s1 constitutes the first side surface, and the side surface s2 constitutes the second side surface. Also, the side surfaces s3 and s4 constitute a pair of other side surfaces that face opposite directions other than the first side surface and the second side surface.

[0050] As a pre-step for forming the concave grooves 50 on the side surfaces s1 and s2 of the coil 15, an insulating coating 42 (see FIG. 2) is coated on the outer surface of a conducting wire 41 (see FIG. 2) whose cross-section is shaped into a substantially rectangular shape, and it is pre-cut into a predetermined length to be used. This cut coil 15 is set in a processing device 70 shown in FIGS. 3 and 4.

[0051] The processing device 70 includes a mounting table 71 (see FIG. 4) for mounting the coil 15 with the side surface s2 facing downwards, a first male mold 72 for press-forming the concave groove 50 on the upper side surface s1 of the coil 15, a second male mold 73 for press-forming the concave groove 50 on the lower side surface s2 of the coil 15, and a pair of support molds 74 for clamping the left and right side surfaces s3 and s4 of the coil 15. As shown in FIG. 4, a relief hole 75 extending along the extending direction of the coil 15 is formed in the mounting table 71. The relief hole 75 is a hole for avoiding interference with the second male mold 73 and penetrates the upper wall 71u of the mounting table 71 in the vertical direction.

[0052] The upper base of the first male mold 72 is connected to a descending operation part of a press device (not shown). A pressing part 72a with a mountain-shaped cross-section is formed at the lower end of the first male mold 72. The pressing part 72a has a central part in the width direction bulging downward in an arc shape, and by pressing the bulging part against the upper side surface s1 of the coil 15, it is possible to form the concave groove 50 in the central part in the width direction of the side surface s1.

[0053] The second male mold 73 has its lower base connected to the ascending operation part of a press device (not shown). At the upper end of the second male mold 73, a pressing part 73a with a mountain-shaped cross section is formed. The pressing part 73a has the central part in the width direction bulging upward in an arc shape, and by pressing the bulging part against the lower side surface s2 of the coil 15, a concave groove 50 can be formed in the central part in the width direction of the side surface s2.

[0054] Each of the left and right support molds 74 is supported by a clamping block 77 via a spring member 76 (see Fig. 4). The parts of the support mold 74 facing the left and right side surfaces s3, s4 of the coil 15 are support surfaces 74a for clamping the coil 15. The coil 15 placed on the upper wall 71u of the mounting table 71 is clamped and fixed by the left and right support molds 74 spring-biased by the spring member 76. The coil 15 clamped by the left and right support molds 74 allows displacement corresponding to the load because each support mold 74 is spring-biased by the spring member 76, when a large load (impact) is input from the outside during processing. Each support mold 74 is biased by the spring member 76 so as to be displaceable when a load is input.

[0055] When forming the concave groove 50 on the side surfaces s1, s2 of the coil 15 using this processing device 70, the coil 15 is placed on the upper wall 71u of the mounting table 71, and in this state, the support surfaces 74a of the left and right support molds 74 are pressed against the side surfaces s3, s4 of the coil 15. Thereby, the coil 15 is clamped and fixed in a state of being spring-biased by the left and right support molds 74.

[0056] When the coil 15 is set in the processing device 70 in this way, the first male mold 72 of the processing device 70 descends and the pressing part 72a of the first male mold 72 is pressed against the upper side surface s1 of the coil 15, and at the same time, the second male mold 73 ascends and the pressing part 73a of the second male mold 73 is pressed against the lower side surface s2 of the coil 15. The start timing of the pressing of the side surfaces s1, s2 of the coil 15 by the first male mold 72 and the second male mold 73 may be simultaneous, or the start of the pressing by the second male mold 73 may be slightly later than the start of the pressing by the first male mold 72. That is, when manufacturing the coil 15 by this processing device 70, when the concave groove 50 is press-molded on the upper side surface s1 (one of the first side surface and the second side surface) of the coil 15, the press-molding of the concave groove 50 on the lower side surface s2 (the other of the first side surface and the second side surface) of the coil 15 is started.

[0057] In this way, when the upper side surface s1 and the lower side surface s2 of the coil 15 are pressed by the first male mold 72 and the second male mold 73, a compressive load acts on the region of the cross-section of the coil 15 that is sandwiched between the pressing portion 72a of the first male mold 72 and the pressing portion 73a of the second male mold 73. As a result, the region sandwiched between the pressing portion 72a of the first male mold 72 and the pressing portion 73a of the second male mold 73 is compressed and deformed, and the concave grooves 50 are respectively formed on the upper side surface s1 and the lower side surface s2 of the coil 15. After that, the pressing on the side surfaces s1 and s2 of the coil 15 is terminated by raising the first male mold 72 and lowering the second male mold 73. The timing of the termination of the pressing on the side surfaces s1 and s2 of the coil 15 by the first male mold 72 and the second male mold 73 at this time may be simultaneous, or the termination of the pressing by the first male mold 72 (the raising of the first male mold 72) may be slightly later than the termination of the pressing by the second male mold 73 (the lowering of the second male mold 73).

[0058] As described above, in the method for manufacturing the coil 15 of the present embodiment, when the concave groove 50 is press-molded on the upper side surface s1 (one of the first side surface and the second side surface) of the coil 15, the press-molding of the concave groove 50 on the lower side surface s2 (the other of the first side surface and the second side surface) of the coil 15 is started. Therefore, the press-molding for forming the concave groove 50 on one side surface s1 and the press-molding for forming the concave groove 50 on the other side surface s2 are performed in a time-overlapping manner. Also, at this time, the direction of the load applied to the side surface s1 to form the concave groove 50 on one side surface s1 and the direction of the load applied to the side surface s2 to form the concave groove 50 on the other side surface s2 are opposite to each other. Therefore, a high-stress portion concentrates in the region within the coil 15 that linearly connects the pressing portion 72a for forming the concave groove 50 on one side surface s1 and the pressing portion 73a for forming the concave groove 50 on the other side surface s2, and it becomes difficult for the high-stress portion to spread to other portions.

[0059] This will be described in detail with reference to FIGS. 5 and 6. FIG. 5 is a diagram showing the processing steps (A), (B), (C), and (D) when pressing and molding are performed on the side surfaces s1 and s2 of the coil 15 facing in opposite directions one by one, and the internal pressure distribution of the coil 15 at that time. FIG. 6 is a diagram showing the processing steps (A) and (B) when pressing and molding are performed by wrapping the side surfaces s1 and s2 of the coil 15 facing in opposite directions over time, and the internal pressure distribution of the coil 15 at that time. In FIGS. 5 and 6, the larger the stress inside the coil 15, the darker the concentration is shown.

[0060] In the comparative example shown in FIG. 5, in the step (A), the coil 15 is placed on the mounting table 71, and in the next step (B), pressing and molding are performed on one side surface s1 by a male mold from above. As a result, a concave groove 50 is formed in one side surface s1. In this step (B), a pressing load acts between the pressing portion of the male mold pressed against the center in the width direction of the side surface s1 of the coil 15 and the flat upper surface of the mounting table 71. As a result, within the cross section of the coil 15, as shown by the darker portion of the concentration in (B), the portion with a large stress spreads outward in the width direction downward in a fan shape. In (B), the portion with a large stress is bifurcated and spreads outward in the width direction of the coil 15.

[0061] In the subsequent step (C), the coil 15 is turned upside down so that the other side surface s2 faces upward, and the side surface s1 side is placed on the mounting table 71. In this state, the stress that has spread in a fan shape in the width direction toward the side surface s2 side remains in the cross section of the coil 15.

[0062] After this, in step (D), pressing and molding is performed on the other side surface s2 from above using a male mold. As a result, a concave groove 50 is formed in the other side surface s2. In this step (D), a pressing load acts between the pressing portion of the male mold pressed against the center in the width direction of the side surface s2 of the coil 15 and the flat upper surface of the mounting table 71. As a result, within the cross-section of the coil 15, as shown by the portion with a high concentration in (D), the portion with a large stress spreads outward in the width direction downward in a fan-like manner and is combined with the stress remaining in the coil 15. As a result, a portion with a high stress remains in a wide region in the width direction of the coil 15. That is, a large stress acts on a region not directly related to the formation of the concave groove 50, and distortion occurs in an unnecessary portion. Also, in the process of pressing and molding in (B) and (D), in order to generate a large stress in an unnecessary portion of the coil 15, the load for pressing the male mold becomes correspondingly large.

[0063] On the other hand, in the manufacturing method of the present embodiment shown in FIG. 6, in step (A), the coil 15 is placed on the mounting table 71, and in the next step (B), pressing and molding is performed on the side surfaces s1 and s2 from above and below using male molds respectively. That is, the pressing and molding for one side surface s1 and the pressing and molding for the other side surface s2 are temporally overlapped, and the pressing and molding for one side surface s1 and the pressing and molding for the other side surface s2 are performed from directions facing each other. In this step (B), a pressing load acts between the central region in the width direction of one side surface s1 of the coil 15 and the central region in the width direction of the other side surface s2. As a result, within the cross-section of the coil 15, as shown by the portion with a high concentration in (B), the portion with a large stress concentrates in a narrow region connecting the central region in the width direction of one side surface s1 and the central region in the width direction of the other side surface s2 and does not spread to the outside in the width direction. After completing the processing of the concave groove 50 in this way, it becomes difficult for distortion to occur in unnecessary portions within the cross-section of the coil 15.

[0064] Note that a load that bends the end portion of the coil 15 in the extending direction in the pressing direction acts near the end portion in the extending direction of the concave grooves 50 on the side surfaces s1 and s2 of the coil 15. For this reason, when the concave grooves 50 are press-formed individually on the side surfaces s1 and s2 of the coil 15 without temporally wrapping the side surfaces s1 and s2, longitudinal bending strain tends to remain in the end portion of the coil 15 in the extending direction. However, in the manufacturing method of the coil 15 of the present embodiment, since the press molding is performed on the side surfaces s1 and s2 facing the opposite directions of the coil 15 almost simultaneously from the directions facing each other, longitudinal bending strain hardly occurs in the end portion of the coil 15 in the extending direction.

[0065] Therefore, when the manufacturing method of the coil 15 of the present embodiment is adopted, unnecessary strain is less likely to occur in the coil 15 when the concave grooves 50 are formed on the side surfaces s1 and s2 of the coil 15 facing the opposite directions. Therefore, when this manufacturing method of the coil 15 is adopted, the product quality of the coil 15 can be further improved, the input load required for processing can be reduced, and smooth processing of the coil 15 can be realized.

[0066] Also, when manufacturing the coil 15, it is desirable to match at least one of the start timing of the press molding for one side surface s1 and the other side surface s2 and the end timing of the press molding for one side surface s1 and the other side surface s2. When the start timing of the press molding for one side surface s1 and the other side surface s2 is matched, the deformation load that rapidly increases at the initial stage of the start of the pressing can be concentrated between the pressing portions 72a and 73a of both side surfaces s1 and s2, and the diffusion of the high-stress portion to the surroundings can be prevented. Also, when the end timing of the press molding for one side surface s1 and the other side surface s2 is matched, even if there is some variation in deformation between one side surface s1 and the other side surface s2 before the end of the press molding, the variation in deformation can be finally corrected.

[0067] Incidentally, it is more desirable that the start timing of the pressing forming for one side surface s1 and the other side surface s2, and the end timing of the pressing forming for one side surface s1 and the other side surface s2 both coincide. In this case, the deformation load that rapidly increases at the initial stage of the start of pressing can be concentrated between the pressing portions of one side surface s1 and the other side surface s2, and the variation in the deformation of one side surface s1 and the other side surface s2 can ultimately be corrected. Therefore, when this method is adopted, the processing accuracy of the concave groove 50 for the side surfaces s1, s2 of the coil 15 can be further improved.

[0068] Furthermore, in the manufacturing method of the coil 15 of the present embodiment described above, when performing pressing forming on one side surface s1 and the other side surface s2 of the coil 15, the pair of the remaining other side surfaces s3, s4 is clamped by the support mold 74. In this case, by clamping the pair of the other side surfaces s3, s4 by the support mold 74, the rotation of the coil 15 during pressing forming can be suppressed. Therefore, when the manufacturing method of the coil 15 of the present embodiment is adopted, the pressing forming of the coil 15 can be performed with high accuracy.

[0069] Also, in the manufacturing method of the coil 15 of the present embodiment, the support mold 74 is biased by a spring member 76 so as to be displaceable when a load is input. For this reason, when this method is adopted, the impact associated with the input of a large load during pressing forming can be absorbed by the function of the spring member 76. Therefore, when this method is adopted, the concave groove 50 can be stably and accurately formed on the side surfaces s1, s2 facing the opposite directions of the coil 15.

[0070] Note that the present invention is not limited to the above-described embodiment, and various design changes are possible without departing from the gist thereof. For example, in the above-described embodiment, the concave groove 50 formed on the side surfaces s1, s2 of the coil 15 is formed to be recessed in an arc shape, but the shape of the concave groove 50 is not limited to this shape. The concave groove 50 may be, for example, a shape having a corner portion in a part such as a triangle or a square.

[0071] In the above-described embodiment, the cross-sectional shape of the coil 15 (rotating electrical machine coil) is substantially rectangular, but the cross-sectional shape of the coil 15 is not limited to a substantially rectangular shape. As long as the cross-sectional shape of the coil 15 has a first side surface and a second side surface facing in opposite directions, it may be a non-square even-sided polygon such as a hexagon or an octagon.

[0072] Also, in the above-described embodiment, the coil 15 (rotating electrical machine coil) having the concave groove 50 is used for the stator 10 portion of the rotating electrical machine 1, but this coil 15 can also be applied to portions other than the stator 10. For example, in a rotating electrical machine having a coil winding portion in the rotor portion, it can also be applied to the rotor portion.

[0073] Furthermore, in the above-described embodiment, the first male mold 72 and the second male mold 73 are moved up and down in the vertical direction to press-mold the concave groove 50 on the side surfaces s1, s2 of the coil 15, but the pressing direction of the first male mold 72 and the second male mold 73 is not limited to the vertical direction. The pressing direction of the first male mold 72 and the second male mold 73 may be, for example, the horizontal direction.

Explanation of Reference Numerals

[0074] 15... Coil (rotating electrical machine coil) 50... Concave groove 74... Support mold s1... Side surface (first side surface) s2... Side surface (second side surface)

Claims

1. A method for manufacturing a rotating electrical machine coil having a first side surface and a second side surface facing in opposite directions, wherein concave grooves are provided along the longitudinal direction on the first side surface and the second side surface respectively, A method for manufacturing a rotating electrical machine coil, characterized in that when the concave groove is press-molded on one of the first side surface and the second side surface, the press-molding of the concave groove on the other side surface is started.

2. The method for manufacturing a rotating electrical machine coil according to claim 1, characterized in that at least one of the start timing of the press molding for the first side surface and the second side surface and the end timing of the press molding for the first side surface and the second side surface is made to coincide.

3. The method for manufacturing a rotating electrical machine coil according to claim 2, characterized in that the start timing of the press molding for the first side surface and the second side surface and the end timing of the press molding for the first side surface and the second side surface are respectively made to coincide.

4. The method for manufacturing a rotating electrical machine coil according to claim 1 or 2, characterized in that when the press molding is performed on the first side surface and the second side surface, a pair of other side surfaces facing in opposite directions other than the first side surface and the second side surface are clamped by a support mold.

5. The method for manufacturing a rotating electrical machine coil according to claim 4, characterized in that the support mold is spring-biased to be displaceable when a load is input.

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