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 technology]

[0002] Some rotating electric machines, such as electric motors and generators, have a rotor rotatably arranged radially inside a circular stator. The stator includes a stator core and a coil (a rotating electric machine coil) wound around the stator core. The stator core is formed, for example, integrally with a cylindrical back yoke and a plurality of teeth protruding radially inward from the back yoke. A slot is formed between each of the plurality of teeth that are adjacent in the circumferential direction. The coil is wound around each tooth through the slots arranged on both sides of the tooth.

[0003] In this type of rotating electric machine, the coils become hot during use, so it is desirable to efficiently cool the coils. One known method for efficiently cooling the coils of a rotating electric machine is to flow a coolant around the coils (see, for example, Patent Document 1).

[0004] In the rotating electric machine described in Patent Document 1, the coils (rotating electric machine coils) wound around the teeth of the stator core are formed of rectangular wire. The coils have a generally arc-shaped groove formed on the side of the insertion portion (the side facing a direction intersecting the extension direction) of the coils that are inserted into the slots. Coolant introduced from one axial end of the stator core flows into this groove and then flows out to the other axial end. The coils are efficiently cooled by the coolant flowing through the groove. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 7139969 Summary of the Invention [Problem to be solved by the invention]

[0006] When forming the grooves on both opposing side surfaces of a coil, the coil is placed on a mounting table with one side facing upward, and in this state, a groove-forming male die is lowered to press-mold the groove into one side surface of the coil. After the press-mold of the groove on one side surface is completed, the coil is turned over so that the other side surface faces upward, and a groove is press-mold on the other side surface using the male die in the same way as on the one side surface.

[0007] By forming grooves in the two opposing side surfaces of the coil in this way, when a male mold is pressed against one side surface (the surface facing upward), a compressive load acts between the mountain-shaped pressing portion of the male mold, which presses against the top surface of the coil at approximately the center in the width direction, and the flat top surface of the mounting table. At this time, the other side surface of the coil (the surface facing downward) abuts against the top surface of the mounting table over a wide area in the width direction, so that a large stress acts on the cross section of the coil between the approximately center area in the width direction of the top surface where the male mold is pressed and the wide area in the width direction where the top surface of the mounting table abuts. In other words, the area where the large stress acts spreads out downward in a fan-like manner across the cross section of the coil, or is distributed in a bifurcated manner in the width direction.

[0008] Then, when the coil is flipped over so that the other side of the coil faces upward and a male mold is pressed against that side, a similar compressive load acts between the pressing portion of the upper male mold and the top surface of the mounting table. At this time, a large stress is distributed across the cross section of the coil between the approximately central region in the width direction of the top surface where the male mold is pressed and a wide region in the width direction where the top surface of the mounting table abuts. However, some of the stress generated when forming the groove on one side remains in the cross section of the coil. Therefore, the cross section of the coil after molding is completed will contain a combined stress generated when forming the groove on one side and a combined stress generated when forming the groove on the other side, both of which remain over a wide area. Therefore, when grooves are formed on two opposite side surfaces of the coil using the above-mentioned method, the coil is likely to be significantly distorted.

[0009] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a method for manufacturing a coil for a rotating electrical machine that is less likely to cause unnecessary distortion when forming grooves on side surfaces facing opposite directions. [Means for solving the problem]

[0010] In order to solve the above problems, the manufacturing method of a coil for a rotating electric machine according to the present invention employs the following configuration. That is, the manufacturing method of a coil for a rotating electric machine according to the present invention is a manufacturing method of a coil for a rotating electric machine having a first side surface (e.g., side surface s1 in the embodiment) and a second side surface (e.g., side surface s2 in the embodiment) facing in opposite directions, and a groove (e.g., groove 50 in the embodiment) along the longitudinal direction provided on each of the first side surface and the second side surface, and is characterized in that while the groove is being press-molded on one of the first side surface and the second side surface, press-molding of the groove on the other side is started.

[0011] In the method for manufacturing a coil for a rotating electric machine according to the present invention, the press-forming process for forming the grooves on the first side surface and the press-forming process for forming the grooves on the second side surface are performed in a time-overlapping manner. During this process, the direction of the load applied to the first side surface to form the grooves on the first side surface and the direction of the load applied to the second side surface to form the grooves on the second side surface face each other. Therefore, high stress is concentrated in a region of the coil that linearly connects the pressing portion for forming the grooves on the first side surface and the pressing portion for forming the grooves on the second side surface, and the high stress is less likely to spread to other regions. Therefore, after the grooves are formed, distortion is less likely to occur in unnecessary portions of the cross section of the coil. Furthermore, when this method is adopted, stress is less likely to occur in unnecessary parts of the cross section of the coil during processing, so the load required for processing can be reduced, enabling smooth processing of coils for rotating electric machines.

[0012] 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 may be made to coincide with each other.

[0013] In this case, if the start timing of press molding for the first side surface and the second side surface are synchronized, the deformation load that rapidly increases at the beginning of pressing can be concentrated between the pressed parts on both sides, preventing high-stress areas from diffusing to the surrounding area. Also, if the end timing of press molding for the first side surface and the second side surface are synchronized, even if there is some variation in deformation between the first side surface and the second side surface before the end of press molding, the variation in deformation can ultimately be corrected.

[0014] The start timing of the press molding for the first side surface and the second side surface may be set to coincide with the end timing of the press molding for the first side surface and the second side surface.

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

[0016] When performing the press molding 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 may be clamped by a support mold (e.g., support mold 74 in the embodiment).

[0017] In this case, by clamping the other pair of side surfaces with the support mold, it is possible to suppress rotation of the rotating electric coil during press molding, thereby enabling press molding of the rotating electric coil to be performed with high precision.

[0018] The support mold is preferably spring-biased so as to be displaceable when a load is input.

[0019] In this case, the support mold that holds the rotating electrical coil is spring-loaded to allow it to move, and the spring function can absorb the impact caused by the input of a large load during press molding. Therefore, when this method is adopted, it is possible to prevent the coil from falling off or shifting from the processing device and to perform coil processing stably. [Effects of the Invention]

[0020] In the manufacturing method of a coil for a rotating electric machine according to the present invention, while a groove is being press-molded into one of the first and second side surfaces, press-molding of the groove into the other side surface is initiated, so that the press-molding of the first side surface and the press-molding of the second side surface can be performed with a time overlap. Furthermore, 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. Therefore, when the manufacturing method of a coil for a rotating electric machine according to the present invention is employed, unnecessary distortion in the coil is less likely to occur when grooves are formed in side surfaces facing opposite directions. This further improves the product quality of the coil for a rotating electric machine. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a longitudinal sectional view of a rotating electric machine according to an embodiment; [Figure 2] 2 is a cross-sectional view of the rotating electric machine according to the embodiment taken along line II-II in FIG. 1. [Figure 3] 1 is a perspective view of a processing device for a coil for a rotating electric machine according to an embodiment; [Figure 4] 1 is a schematic cross-sectional view of a processing device for a coil for a rotating electric machine according to an embodiment; [Figure 5] 1A to 1D are diagrams showing the processing steps (A), (B), (C), and (D) of a comparative example and the pressure distribution inside the coil at those steps. [Figure 6] 3A and 3B are diagrams showing processing steps (A) and (B) of an embodiment and the pressure distribution inside the coil at those steps. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a vertical cross-sectional view of a rotating electrical machine 1 according to this embodiment. The rotating electric 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 electric machine case 12. The stator 10 is fixed inside the rotating electric 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 disposed radially inside the stator core 14 (stator 10). The coil 15 constitutes a coil for a rotating electrical machine in this embodiment.

[0023] A permanent magnet (not shown) is attached to the rotor 11 near its outer circumferential surface. The rotor 11 is supported by a rotating shaft 17 via a sleeve 16 so as to be rotatable together with the rotor 11. The rotating shaft 17 serves as an output shaft when the rotating electric machine 1 is used as a motor, and serves as a power input shaft when the rotating electric machine 1 is used as a generator. The rotating shaft 17 and the sleeve 16 are rotatably supported by the rotating electric machine case 12 via a bearing 18. In the following description, the direction parallel to the rotation axis 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 perpendicular to the axial and circumferential directions is referred to as the radial direction.

[0024] An annular first side case 19 and a second side case 20 are arranged on one and the other axial ends of the stator core 14. The main parts of the first side case 19 and the second side case 20 are formed by the rotating electric machine case 12.

[0025] The first side case 19 externally covers 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, together with the one axial end face of the stator core 14, forms a circular first liquid chamber 21. The first side case 19 is formed with an inlet port 24 for introducing coolant 23 into the first liquid chamber 21. The inlet port 24 is connected to a circulation circuit 25 for 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 axial end side of the stator core 14.

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

[0027] A feed pump P is connected midway through the circulation circuit 25. A heat exchanger OC that cools the coolant 23 by exchanging heat with outside air is connected to the upstream side of the feed pump P in the circulation circuit 25. The downstream side of the feed pump P is connected to the inlet port 24. Furthermore, the upstream side of the heat exchanger OC in the circulation circuit 25 is connected to the outlet port 26.

[0028] FIG. 2 is a cross-sectional view of the rotating electric machine 1 taken along line II-II in FIG. Stator core 14 is formed, for example, by stacking multiple electromagnetic steel sheets in the axial direction. As shown in Fig. 2, stator core 14 is formed by integrally molding a cylindrical back yoke 27 and multiple teeth 28 that protrude radially inward from the inner periphery of back yoke 27. Back yoke 27 is formed so that the center of the cylinder coincides with 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 in the axial direction. That is, the teeth 28 are integrally formed with tooth bodies 29 that protrude radially inward from the inner peripheral part of the back yoke 27 and flanges 30 that protrude on both circumferential sides from the radially inner ends of the tooth bodies 29.

[0030] A slot 31 that is open radially inward is formed between circumferentially adjacent teeth 28. The slot 31 is surrounded by the mutually opposing side walls of adjacent teeth 28 and the inner circumferential wall of the back yoke 27. The side wall of each tooth 28 is formed by the side of the tooth main body 29 and the side of the flange portion 30. The portion of the slot 31 formed by the side portions of the left and right tooth main bodies 29 has a substantially constant width. Furthermore, 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 main bodies 29. The radially inner openings 40 of each slot 31 are formed between the tip ends of the flanges 30 on the left and right (circumferential sides) of the slot 31. Each slot 31 also penetrates the stator core 14 in the axial direction.

[0031] The coil 15 is provided for three phases, for example, U phase, V phase, and W phase. The coil 15 is formed, for example, by interconnecting a plurality of segment coils. The coil 15 has a metal conductor 41 whose outer surface is covered with an insulating coating 42. The coil 15 is also formed of a rectangular wire. That is, the cross section of the coil 15 perpendicular to the extension direction is formed into a substantially rectangular shape.

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

[0033] As shown in Fig. 2, the insertion portions 15a of the coil 15 are inserted in multiple stages into each slot 31. The multiple insertion portions 15a inserted into the same slot 31 are arranged in a row along the radial direction. In this 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 set arbitrarily.

[0034] The multiple insertion portions 15a inserted into each slot 31 are bundled in a row in parallel, and are covered with a sheet of foamable insulating material 43. The foamable insulating material 43 can be, for example, an electrically insulating base sheet with a foamable adhesive applied to its surface (the surface facing outward when covering the insertion portions 15a) and a non-foamable adhesive applied to its back surface. The foamable insulating material 43, covering the peripheries of the multiple insertion portions 15a, is inserted into the corresponding slots 31 together with the insertion portions 15a. The foamable insulating material 43 is then foamed in the corresponding slot 31 by subsequent heating or other treatment. As a result, part of the outer surface of the foamable insulating material 43 is adhered to the inner wall of the slot 31.

[0035] Even after the insertion portion 15a of the coil 15 and the foam insulating member 43 are placed in the slot 31 as described above, a gap is maintained inside the slot 31 to connect one axial end side and the other axial end side of the stator core 14. This gap forms a coolant passage 44 for flowing the coolant introduced into the first liquid chamber 21 toward the second liquid chamber 22. Specifically, the gaps that form the coolant passage 44 include the gap between the inner surface of the foam insulating member 43 and the insertion portion 15a, the gap between adjacent insertion portions 15a, and the gap between the outer surface of the foam insulating member 43 and the inner wall of the slot 31. The coolant 23 flowing through the coolant passage 44 in the slot 31 absorbs heat from the insertion portion 15a of the coil 15.

[0036] A groove 50 extending along the axial direction of the stator core 14 is formed on the radially inward and radially outward side surfaces of each insertion portion 15a arranged in the slot 31. The groove 50 is formed to be recessed in a substantially arc shape toward the central region in the width direction of the insertion portion 15a. When multiple insertion portions 15a are arranged in the slot 31 together with the foamed insulation member 43, the groove 50 forms gaps (flow gaps) extending substantially along the axial direction between the mutually opposing side surfaces of radially adjacent insertion portions 15a and between the side surfaces of the insertion portions 15a and the inner surface of the foamed insulation member 43. In this embodiment, the coolant flow groove is formed by the groove 50 formed on the side surface of the coil 15. In this embodiment, a groove 50 is also formed in the lead-out portion 15b of the coil 15 so as to be continuous with the groove 50 of the insertion portion 15a.

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

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

[0039] An annular partition wall 37, which is a cylindrical cover member, is provided on 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. The annular partition wall 37 is formed, for example, from a resin material. However, the annular partition wall 37 can also be formed from other materials such as metal. The annular partition wall 37 has a first end portion 37f facing the first liquid chamber 21, a second end portion 37s facing the second liquid chamber 22, and a partition wall main body portion 37b located 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 to have the same inner diameter as the partition wall main body portion 37b. A midpoint of the second end portion 37s in the extension direction is stepped down in diameter relative to the partition wall main body portion 37b.

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

[0041] The inner peripheral surface of the reduced diameter portion of the second end 37s is slidably fitted onto the outer peripheral surface of the second inner peripheral wall 35. An annular groove 38s is formed in the outer peripheral surface of the second inner peripheral wall 35, and an annular sealing member 39s such as an O-ring is fitted into the annular groove 38s. The gap between the second inner peripheral wall 35 and the second end 37s (annular partition wall 37) is liquid-tightly sealed by the sealing member 39s.

[0042] As described above, the first end 37f of the annular partition wall 37 is liquid-tightly fitted to the first inner circumferential wall 32 of the first side case 19, and the second end 37s is liquid-tightly fitted to the second inner circumferential wall 35 of the second side case 20. The annular partition wall 37 separates the radially inner region of the stator core 14 attached inside the rotating electric machine case 12 from the outer circumferential surface of the rotor 11. Therefore, even if the coolant 23 leaks from the slots 31 of the stator core 14 into the radially inner region, the coolant 23 can be prevented from flowing toward the outer circumferential surface of the rotor 11.

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

[0044] 2, the outer peripheral surface of the partition wall main body 37b of the annular partition wall 37 is maintained in contact with the inner peripheral surface of the stator core 14. In addition, the inner peripheral surface of the partition wall main body 37b of the annular partition wall 37 faces the outer peripheral surface of the rotor 11 with a small gap therebetween so as to be out of contact with the outer peripheral surface of the rotor 11.

[0045] The foamable insulating member 43, which is housed and arranged in each slot 31 of the stator core 14 together with the multiple insertion portions 15a of the coils 15, penetrates into the openings 40 on the radially inner side of the slots 31 as the foamable adhesive on the outer surface thereof foams due to heating or the like. The foamable adhesive that has penetrated into the openings 40 is adhered to the outer peripheral surface of the annular partition wall 37 that is arranged on the outer side (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 foamable insulating member 43 on the inner side of the multiple slots 31 through the openings 40 of the slots 31.

[0046] In the rotating electric machine 1 having the above configuration, when a current flows continuously through the coil 15 during operation, the coil 15 generates heat and reaches a high temperature. At this time, the coolant 23 is introduced from the circulation circuit 25 through the inlet port 24 into the first liquid chamber 21 of the rotating electrical machine 1. The coolant 23 introduced into the first liquid chamber 21 flows within the first liquid chamber 21, thereby cooling a one-end region (the lead-out portion 15b) of the coil 15 exposed to the outside from one axial end side of the stator core 14. The coolant 23 also flows through the multiple slots 31 (the coolant passages 44 within the slots 31) of the stator core 14 from one axial end side to the other axial end side, and flows into the second liquid chamber 22. The coolant flowing within the slots 31 cools the insertion portion 15a of the coil 15 inserted within the slots 31. The coolant 23 that has flowed into the second liquid chamber 22 cools the other-end region of the coil 15 exposed to the outside from the other axial end side of the stator core 14, and is then returned to the circulation circuit 25 through the outlet port 26.

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

[0048] Next, a method for manufacturing coil 15 wound around stator core 14 as described above will be described with reference to FIGS. 3 to 6, the insulating coating 42 of the coil 15 shown in Fig. 2 is omitted for ease of understanding. In the following description, the "width direction" of the coil 15 refers to the direction perpendicular to the vertical direction in the cross section of the coil 15 (the cross section perpendicular to the extension direction).

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

[0050] As a preliminary step to forming the recessed grooves 50 on the side surfaces s1 and s2, the coil 15 is prepared by covering the outer surface of a conductor 41 (see FIG. 2) having a substantially rectangular cross section with an insulating coating 42 (see FIG. 2) and cutting the conductor 41 to a predetermined length beforehand. The 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 Figure 4) on which the coil 15 is placed with its side surface s2 facing downwards, a first male mold 72 for press-molding a groove 50 into the upper side surface s1 of the coil 15, a second male mold 73 for press-molding a groove 50 into the lower side surface s2 of the coil 15, and a pair of support molds 74 for clamping the left and right sides s3, s4 of the coil 15. 4, the mounting base 71 is formed with an escape hole 75 extending along the extension direction of the coil 15. The escape hole 75 is a hole for avoiding interference with the second male die 73, and penetrates the upper wall 71u of the mounting base 71 in the vertical direction.

[0052] The first male die 72 has an upper base connected to a lowering unit of a press device (not shown). A pressing portion 72a having a mountain-shaped cross section is formed at the lower end of the first male die 72. The pressing portion 72a bulges downward in an arc shape at the center in the width direction, and by pressing the bulging portion against the upper side surface s1 of the coil 15, it is possible to form a recessed groove 50 in the center in the width direction of the side surface s1.

[0053] The second male die 73 has a lower base connected to an elevation unit of a press device (not shown). A pressing portion 73a having a mountain-shaped cross section is formed at the upper end of the second male die 73. The pressing portion 73a bulges upward in an arc shape at the center in the width direction, and by pressing the bulging portion against the lower side surface s2 of the coil 15, it is possible to form a recessed groove 50 in the center in the width direction of the side surface s2.

[0054] The left and right support dies 74 are supported by clamping blocks 77 via spring members 76 (see FIG. 4). The portions of the support dies 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 dies 74, which are spring-biased by the spring members 76. The coil 15 sandwiched between the left and right support dies 74 is allowed to displace in accordance with a large load when a large load (impact) is applied from the outside during processing, because each support dies 74 is biased by a spring member 76. Each support dies 74 is biased by the spring member 76 so as to be displaceable when a load is applied.

[0055] When forming the grooves 50 on the side surfaces s1 and 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 dies 74 are pressed against the side surfaces s3 and s4 of the coil 15. As a result, the coil 15 is clamped and fixed between the left and right support dies 74 in a spring-biased state.

[0056] When the coil 15 is set in the processing device 70 in this manner, the first male die 72 of the processing device 70 descends and the pressing portion 72a of the first male die 72 presses against the upper side surface s1 of the coil 15, and the second male die 73 ascends and the pressing portion 73a of the second male die 73 presses against the lower side surface s2 of the coil 15. At this time, the timing at which the first male die 72 and the second male die 73 start pressing against the side surfaces s1 and s2 of the coil 15 may be simultaneous, or the start of pressing by the second male die 73 may be slightly later than the start of pressing by the first male die 72. In other words, when manufacturing the coil 15 using this processing device 70, while the groove 50 is being press-molded into the upper side surface s1 (one of the first and second side surfaces) of the coil 15, press-molding of the groove 50 into the lower side surface s2 (the other of the first and second side surfaces) of the coil 15 begins.

[0057] When the upper side surface s1 and the lower side surface s2 of the coil 15 are pressed by the first male die 72 and the second male die 73 in this manner, 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 die 72 and the pressing portion 73a of the second male die 73. This causes the region sandwiched between the pressing portion 72a of the first male die 72 and the pressing portion 73a of the second male die 73 to undergo compressive deformation, forming grooves 50 on the upper side surface s1 and the lower side surface s2 of the coil 15, respectively. Thereafter, the first male die 72 is raised and the second male die 73 is lowered, thereby completing the pressing of the coil 15 against the side surfaces s1 and s2. At this time, the timing at which the first male die 72 and the second male die 73 finish pressing the sides s1 and s2 of the coil 15 may be simultaneous, or the end of pressing by the first male die 72 (rising of the first male die 72) may be slightly later than the end of pressing by the second male die 73 (descending of the second male die 73).

[0058] As described above, in the manufacturing method of the coil 15 of this embodiment, while the groove 50 is being press-molded into the upper side surface s1 (one of the first and second side surfaces) of the coil 15, press-molding of the groove 50 into the lower side surface s2 (the other of the first and second side surfaces) of the coil 15 is started. Therefore, the press-molding for forming the groove 50 into one side surface s1 and the press-molding for forming the groove 50 into the other side surface s2 are performed in an overlapping manner. Furthermore, at this time, the direction of the load applied to the side surface s1 to form the groove 50 into one side surface s1 and the direction of the load applied to the side surface s2 to form the groove 50 into the other side surface s2 are opposite each other. Therefore, a high stress portion is concentrated in a region of the coil 15 that linearly connects the pressing portion 72a for forming the groove 50 into one side surface s1 and the pressing portion 73a for forming the groove 50 into the other side surface s2, and the high stress portion is less likely to spread to other portions.

[0059] This will be explained in detail with reference to FIGS. Fig. 5 shows processing steps (A), (B), (C), and (D) when press-molding is performed on each of the side surfaces s1 and s2 of the coil 15, which face in opposite directions, and the pressure distribution inside the coil 15 at that time. Fig. 6 shows processing steps (A) and (B) when press-molding is performed on both side surfaces s1 and s2 of the coil 15, which face in opposite directions, in a time-lapped manner, and the pressure distribution inside the coil 15 at that time. In Figs. 5 and 6, areas of the coil 15 with greater stress are shown with a darker density.

[0060] In the comparative example shown in FIG. 5, in step (A), the coil 15 is placed on a mounting table 71, and in the next step (B), a male mold is used from above to press one side surface s1 to form a recessed groove 50 on one side surface s1. In this step (B), a pressure load acts between the pressing portion of the male mold, which is pressed against the center of the width 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 dense areas in (B), the areas with high stress spread downward and outward in the width direction. In (B), the areas with high stress are bifurcated and spread outward in the width direction of the coil 15.

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

[0062] After this, in step (D), a male mold is used to press the other side surface s2 from above. This forms a recessed groove 50 in the other side surface s2. In this step (D), a pressure load acts between the pressing portion of the male mold, which is pressed against the center of the width 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 dense areas in (D), areas of high stress spread downward and outward in the width direction, and are combined with the stress that remained in the coil 15. As a result, areas of high stress remain in a wide region in the width direction of the coil 15. In other words, large stress acts on areas not directly related to the formation of the recessed groove 50, causing distortion in unnecessary areas. Furthermore, in the press molding process of (B) and (D), large stress is generated in unnecessary portions of the coil 15, so the load for pressing the male mold becomes correspondingly large.

[0063] In contrast, in the manufacturing method of this embodiment shown in FIG. 6, in step (A), the coil 15 is placed on a mounting table 71. In the next step (B), the side surfaces s1 and s2 are press-molded from above and below by male dies, respectively. That is, the press-molding of one side surface s1 and the press-molding of the other side surface s2 are overlapped in time, and the press-molding of one side surface s1 and the press-molding of the other side surface s2 are performed from opposite directions. In step (B), a pressure load acts between the central region of one side surface s1 in the width direction of the coil 15 and the central region of the other side surface s2 in the width direction. As a result, within the cross section of the coil 15, as shown by the densely shaded areas in (B), the area with high stress is concentrated in a narrow region connecting the central region of one side surface s1 in the width direction and the central region of the other side surface s2 in the width direction, and does not spread outward in the width direction. After the groove 50 has been formed in this manner, distortion is less likely to occur in unnecessary portions within the cross section of the coil 15.

[0064] Note that a load acts near the ends of the grooves 50 on the side surfaces s1 and s2 of the coil 15 in the extension direction, bending the ends of the coil 15 in the extension direction in the pressing direction. For this reason, if the grooves 50 are press-formed individually on the side surfaces s1 and s2 of the coil 15 without overlapping them in time, longitudinal bending strain is likely to remain at the ends of the coil 15 in the extension direction. However, in the manufacturing method for the coil 15 of this embodiment, press-forming is performed on the side surfaces s1 and s2 of the coil 15 facing opposite directions almost simultaneously from directions facing each other, so that longitudinal bending strain is hardly generated at the ends of the coil 15 in the extension direction.

[0065] Therefore, when the manufacturing method of the coil 15 of this embodiment is adopted, unnecessary distortion is less likely to occur in the coil 15 when forming the recessed grooves 50 on the side surfaces s1 and s2 of the coil 15 that face in 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 achieved.

[0066] Furthermore, when manufacturing the coil 15, it is desirable to synchronize at least one of the start timing of press-forming for one side surface s1 and the other side surface s2 and the end timing of press-forming for one side surface s1 and the other side surface s2. When the start timing of press-forming for one side surface s1 and the other side surface s2 is synchronized, the deformation load that rapidly increases at the beginning of pressing is concentrated between the pressed portions 72a and 73a of both side surfaces s1 and s2, preventing high-stress areas from diffusing to the surrounding area. Furthermore, when the end timing of press-forming for one side surface s1 and the other side surface s2 is synchronized, even if there is some variation in deformation between one side surface s1 and the other side surface s2 before the end of press-forming, the variation in deformation can ultimately be corrected.

[0067] It is more desirable to synchronize the start timing of press-forming on one side surface s1 and the other side surface s2 with the end timing of press-forming on one side surface s1 and the other side surface s2. In this case, the deformation load that increases rapidly at the beginning of pressing can be concentrated between the pressed portions of one side surface s1 and the other side surface s2, and variations in deformation between 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 groove 50 on the sides s1 and s2 of the coil 15 can be further improved.

[0068] Furthermore, in the manufacturing method of the coil 15 of this embodiment described above, when one side surface s1 and the other side surface s2 of the coil 15 are press-molded, the remaining pair of other side surfaces s3 and s4 are clamped by the support mold 74. In this case, by clamping the pair of other side surfaces s3 and s4 by the support mold 74, it is possible to suppress rotation of the coil 15 during press-molding. Therefore, when the manufacturing method of the coil 15 of this embodiment is adopted, the press-molding of the coil 15 can be performed with high precision.

[0069] Furthermore, in the manufacturing method of the coil 15 of this embodiment, the support mold 74 is biased by the spring member 76 so as to be displaceable when a load is applied. Therefore, when this method is employed, the impact caused by the application of a large load during press molding can be absorbed by the function of the spring member 76. Therefore, when this method is employed, the recessed grooves 50 can be stably and accurately formed on the side surfaces s1 and s2 of the coil 15 that face in opposite directions.

[0070] The present invention is not limited to the above-described embodiment, and various design modifications are possible without departing from the spirit of the present invention. For example, in the above-described embodiment, the grooves 50 formed on the side surfaces s1 and s2 of the coil 15 are recessed in an arc shape, but the shape of the grooves 50 is not limited to this. The grooves 50 may have a shape with corners on some parts, such as a triangle or a square.

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

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

[0073] Furthermore, in the above embodiment, the first male die 72 and the second male die 73 are raised and lowered in the vertical direction to press-mold the recessed groove 50 into the side surfaces s1 and s2 of the coil 15, but the pressing direction of the first male die 72 and the second male die 73 is not limited to the vertical direction. The pressing direction of the first male die 72 and the second male die 73 may be, for example, the horizontal direction. [Explanation of symbols]

[0074] 15...Coil (rotating electric machine coil) 50...Groove 74…support type s1…Side (1st side) s2...side (second side)

Claims

1. A method for manufacturing a coil for a rotating electric machine, the coil having a first side surface and a second side surface facing in mutually opposite directions, the first side surface and the second side surface each being provided with a recessed groove extending along a longitudinal direction, while the recessed groove is being press-molded in one of the first side surface and the second side surface, press-molding of the recessed groove in the other side surface is started; A method for manufacturing a coil for a rotating electric machine, characterized in that at least one of the start timing of the press molding for the first side and the second side and the end timing of the press molding for the first side and the second side is matched.

2. A method for manufacturing a coil for a rotating electric machine having a first side surface and a second side surface facing in opposite directions, the first side surface and the second side surface each having a groove extending along the longitudinal direction, while the recessed groove is being press-molded in one of the first side surface and the second side surface, press-molding of the recessed groove in the other side surface is started; A method for manufacturing a coil for a rotating electric machine, characterized in that when performing the press molding 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.

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

4. 2. The method for manufacturing a coil for a rotating electric machine according to claim 1, wherein the start timing of the press molding for the first side and the second side and the end timing of the press molding for the first side and the second side are respectively matched.

5. 3. The method for manufacturing a coil for a rotating electric machine according to claim 2, wherein the support mold is spring-biased so as to be displaceable when a load is input.

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