Manufacturing method of molded coil and manufacturing method of reactor

Abstract

To provide a manufacturing method of a molded coil and a reactor in which resin leakage to a heat dissipation surface is suppressed.SOLUTION: A manufacturing method of a molded coil 1 includes a cover installation step and a mold forming step. In the cover installation step, a first end face cover 62 that covers one end face of a coil 2, a second end face cover 64 that covers the other end face of the coil 2, and a side cover that extends along the edge of a heat dissipation surface 23 are installed. In the mold forming step, the side cover is pressed against the coil 2 by a slide mold MS, and a molding resin 9 is injected into the mold while compressing the coil 2 in the direction of the winding shaft 26 via the end face cover. The side cover has a first side divided cover 63 that is molded integrally with the first end face cover 62, and a second side divided cover 65 that is molded integrally with the second end face cover 64. The first side divided cover 63 and the second side divided cover 65 extend while passing each other, and have a gap of a labyrinth structure 7 between them.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a molded coil obtained by molding a coil with resin, and a method for manufacturing a reactor including this molded coil. [Background technology]

[0002] When a current is passed through a coil, the coil generates a magnetic flux according to the number of turns. Therefore, coils are used as electromagnetic components that convert electrical energy into magnetic energy and store and release it. Coils are also called reactors and are used in a wide variety of applications. Applications of coils, also called reactors, include boost reactors, series reactors, parallel reactors, current limiting reactors, starting reactors, shunt reactors, neutral reactors, and arc suppression reactors.

[0003] Boost reactors are incorporated into on-board boost circuits such as those used in the drive systems of hybrid and electric vehicles. Series reactors are connected in series with motor circuits to limit the current during short circuits. Parallel reactors stabilize the current sharing between parallel circuits. Current-limiting reactors limit the current during short circuits. Starting reactors are connected in series with motor circuits to protect the machine and limit the starting current. Shunt reactors are connected in parallel with transmission lines to compensate for leading reactive power and suppress abnormal voltages. Neutral point reactors are connected between the neutral point and the ground to limit the ground fault current that flows in the event of a ground fault in the power system. Arc-suppression reactors automatically extinguish the arc that occurs when a single-line ground fault occurs in a three-phase power system.

[0004] Coils may be coated with resin. By coating the coil with resin, the core to which the coil is attached is electrically insulated from the coil. A coil coated with resin is called a molded coil. The resin around the coil is formed by molding to increase the adhesion between the coil and the resin. However, if the mold is pressed too hard against the coil surface to prevent the resin from leaking to the heat dissipation surface, the coil surface may be damaged and the enamel coating of the conductive wire may peel off.

[0005] Therefore, a part of the surface of the coil is covered with a resin cover, and the resin cover is interposed between the coil and the mold. This resin cover is pressed against the surface of the coil to prevent resin leakage to the heat dissipation surface, and may also play a role in correcting unevenness of the coil. In addition, in order to eliminate gaps between turns of the coil or to correct the length of the coil along the winding axis, pressure may be applied to the end surface of the coil in the mold that molds the resin to compress the coil. The resin cover may be placed on the end surface of the coil to prevent the end surface of the coil from being directly exposed to pressure. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2021-122964 A [Patent Document 2] Patent Publication No. 2021-61346 Summary of the Invention [Problem to be solved by the invention]

[0007] In this way, the molding process is complicated because resin is not simply injected into the mold, but the resin cover is pressed against the surface of the coil, and the coil is compressed through the resin cover. Furthermore, the shapes of the coil and the resin cover are also complicated. The shape of the mold corresponding to these is also complicated, and the number of divisions of the mold increases. This makes it easier for the resin to leak onto the heat dissipation surface.

[0008] The present invention has been made to solve the above-mentioned problems, and its object is to provide a manufacturing method for a molded coil and a reactor in which resin leakage to the heat dissipation surface is suppressed. [Means for solving the problem]

[0009] In order to solve the above-mentioned problems, the manufacturing method of a molded coil according to this embodiment is a manufacturing method of a molded coil in which a coil is covered with resin except for a heat dissipation surface extending along a winding axis, and includes a cover installation process in which an end face cover that covers an end face of the coil and a side cover that is integrally molded with the end face cover, extends along an edge of the heat dissipation surface, and covers a part of the circumferential surface of the coil are installed; a molding process in which the side cover is pressed against the coil with a slide die, and the resin is injected into the die while compressing the coil in the winding axis direction via the end face cover; the end cover has a first end cover covering one end surface of the coil and a second end cover covering the other end surface of the coil, the side cover has a first side divided cover that is integrally molded with the first end cover and extends from an edge of the first end cover along the winding shaft, and a second side divided cover that is integrally molded with the second end cover and extends from an edge of the second end cover along the winding shaft, the first side cover and the second side cover extend past each other, and there is a gap having a labyrinth structure between the first side cover and the second side cover.

[0010] The first side divided cover may have a long plate portion extending along the winding shaft, the second side divided cover may have a U-shaped plate into which the long plate portion is inserted, and the gap having the labyrinth structure may be a U-shaped gap between the long plate portion and the U-shaped plate.

[0011] The U-shaped gap may have two flow paths arranged on either side of the long plate portion and extending along the winding axis, and an expansion chamber extending between the tip of the long plate portion and the U-shaped bottom of the U-shaped plate, and the expansion chamber may be wider than the two flow paths.

[0012] The U-shaped plate extends along the winding shaft, sandwiching the long plate portion of the first side split cover, and has a heat dissipation surface side long plate portion closer to the heat dissipation surface than the long plate portion of the first side split cover, and a resin inflow side long plate portion on the opposite side to the heat dissipation surface side long plate portion across the long plate portion of the first side split cover, and the first side split cover may have a barrier plate facing the tip of the resin inflow side long plate portion.

[0013] The second side divided cover may have a cover plate that covers the U-shaped plate.

[0014] The cover installing process may include a first cover installing process of installing the first end surface cover and the first side surface divided cover, and a second cover installing process of installing the second end surface cover and the second side surface divided cover, and the molding process may include pressing the first side surface divided cover and the second side surface divided cover against the coil with the slide mold, and compressing the coil in the winding axis direction via one or both of the first end surface cover and the second end surface cover.

[0015] In order to solve the above-mentioned problems, the method for manufacturing the reactor according to this embodiment includes, after the method for manufacturing the molded coil, an assembly process of mounting the molded coil on a core including a magnetic body. Effect of the Invention

[0016] According to the present invention, even when the coil is compressed inside a mold, the labyrinth structure can prevent the flowing resin from reaching the heat dissipation surface, resulting in excellent heat dissipation properties of the molded coil. [Brief description of the drawings]

[0017] [Figure 1] FIG. [Diagram 2] FIG. 2 is a perspective view of the reactor excluding the secondary molding resin. [Diagram 3] FIG. [Figure 4]FIG. 2 is a perspective view of the heat dissipation surface side of the molded coil. [Diagram 5] FIG. 2 is a perspective view of the molded coil with the molding resin removed. [Figure 6] FIG. 11 is an exploded view of the molded coil, illustrating a cover installation process for attaching a resin cover. [Figure 7] FIG. 13 is an exploded view of the molded coil with the cover plate removed to expose the U-shaped plate. [Figure 8] 1 is a perspective view of the molded coil with the cover plate removed to expose the U-shaped plate. FIG. [Figure 9] 4 is a schematic diagram showing the relationship between a first side divided cover and a second side divided cover of a molded coil. FIG. [Figure 10] FIG. 11 is a perspective view showing a state in which the coil is compressed in a molding process. [Figure 11] FIG. 13 is a perspective view showing a state in which a slide die is pressed in a molding process. [Figure 12] 10 is a schematic diagram showing fluid resin flowing between a first side surface divided cover and a second side surface divided cover during a molding process. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, a molded coil and a reactor according to an embodiment of the present invention, and a manufacturing method thereof will be described with reference to the drawings. In each drawing, thickness, dimensions, positional relationship, ratio, shape, and the like may be emphasized for ease of understanding, but the present invention is not limited to such emphasis.

[0019] 1 is a perspective view of a reactor 100. The reactor 100 is an electromagnetic component that converts electric energy into magnetic energy and stores and releases the energy. A conductive wire 11 is drawn out from the reactor 100. Electrical energy is supplied to the reactor 100 by electrically connecting the conductive wire 11 to a mounting circuit board. The outer surface of the reactor 100 is covered with a secondary molded resin 120. The secondary molded resin 120 molds each component of the reactor 100, maintains the bonding state of each component, and integrates each component.

[0020] Fig. 2 is a perspective view of reactor 100 excluding secondary molded resin 120. As shown in Fig. 2, reactor 100 includes molded coil 1 and core 110. Secondary molded resin 120 integrates molded coil 1 and core 110. In addition, annular core 110 is formed by joining a plurality of divided parts, and secondary molded resin 120 maintains the joined state of core 110.

[0021] The molded coil 1 generates a magnetic flux by passing a current through the drawn conductive wire 11. The core 110 includes a magnetic material such as a dust core, a ferrite core, a metal composite core, or a laminated steel plate. The dust core is a powder compact obtained by compressing magnetic powder and annealing it. The magnetic powder is mainly composed of iron, and examples of the magnetic powder include pure iron powder, permalloy (Fe-Ni alloy) mainly composed of iron, Si-containing iron alloy (Fe-Si alloy), sendust alloy (Fe-Si-Al alloy), amorphous alloy, nanocrystalline alloy powder, and a mixture of two or more of these powders. The metal composite core is a core formed by kneading and molding magnetic powder and resin.

[0022] The molded coil 1 is fitted in the core 110. Therefore, the core 110 becomes a closed magnetic circuit that passes the magnetic flux generated by the molded coil 1 with a magnetic permeability higher than that of a vacuum. In this way, the reactor 100 converts electric energy into magnetic energy and stores and releases the magnetic energy.

[0023] 3 and 4 are perspective views of the molded coil 1. As shown in FIG. 3 and FIG. 4, the molded coil 1 includes a coil 2, a resin cover 6, and a molded resin 9. The coil 2 is a cylindrically wound body of a conductive wire 11 such as an enamel-coated copper wire. The coil 2 is produced by winding the conductive wire 11 in a spiral shape along a winding axis 26 while shifting the winding position for each turn. The coil 2 is, for example, a spiral edgewise coil. The spiral edgewise coil is formed by winding the rectangular conductive wire 11 so that the wide surface of the conductive wire 11 extends in a direction perpendicular to the winding axis 26. When the coil 2 is energized through the conductive wire 11, the molded coil 1 generates a magnetic flux according to the number of turns of the coil 2.

[0024] There is no limitation on the type of conductive wire 11, and other types of wire such as round wire may be used. There is also no limitation on the winding manner of coil 2, and the conductive wire may be a flatwise coil such that the wide surface of the conductive wire extends along winding axis 26. Although molded coil 1 has, for example, two coils 2 arranged side by side, there is no limitation on the number of coils 2, and molded coil 1 may include one coil 2 or three or more coils 2. The multiple coils 2 may be electrically connected in series within molded coil 1.

[0025] The resin cover 6 and the molded resin 9 cover the outer surface of the coil 2. By covering the outer surface of the coil 2, the resin cover 6 and the molded resin 9 insulate the core 110 from the coil 2 fitted in the core 110. That is, the resin cover 6 and the molded resin 9 are insulating materials. Examples of insulating materials include epoxy resin, unsaturated polyester resin, urethane resin, BMC (Bulk Molding Compound), PPS (Polyphenylene Sulfide), PBT (Polybutylene Terephthalate), and composites of these, and a thermally conductive filler may be mixed in.

[0026] Such molded coil 1 is manufactured through a winding process in which coil 2 is wound, a cover installation process in which resin cover 6 is installed, and a molding process in which molded resin 9 is formed. Then, through an assembly process in which molded coil 1 is mounted on core 110, and integrated with secondary molded resin 120, reactor 100 is manufactured.

[0027] In the molding process of the molded coil 1, the coil 2 is placed in a mold, and then molten fluid resin 8 (see FIG. 12) is injected and solidified to form molded resin 9 that covers part of the outer surface of the coil 2. However, as shown in FIG. 4, in order to ensure the heat dissipation of the coil 2, one surface of the coil 2 parallel to the winding axis 26 is exposed from the molded resin 9 as heat dissipation surface 23. In the molding process, measures are taken to prevent leakage of the fluid resin 8 so that the molded resin 9 is not formed on this heat dissipation surface 23, and then the fluid resin 8 is injected.

[0028] One of the purposes of the cover installation process prior to the molding process is to prevent leakage of the flowing resin 8 onto the heat dissipation surface 23, and in the cover installation process, a resin cover 6 is installed on the surface of the coil 2. The resin cover 6 is a molded product whose shape is determined before covering the coil 2. A part of the resin cover 6 is placed along the edge of the heat dissipation surface 23. The resin cover 6 placed along the edge of the heat dissipation surface 23 isolates the heat dissipation surface 23 from the area where the flowing resin 8 flows in.

[0029] Resin cover 6 is pressed against the surface of coil 2 to correct unevenness in coil 2. Resin cover 6 also applies pressure to coil 2 to compress the length of coil 2 along axis 26 in the molding process in order to eliminate gaps between turns of coil 2 and correct the length of coil 2 along axis 26.

[0030] 5 and 6 are schematic diagrams showing the cover installation step. Specifically, FIG. 5 is a perspective view of the molded coil 1 on which the resin cover 6 is installed, excluding the molded resin 9, and FIG. 6 is an exploded view of the molded coil 1 showing the cover installation step of attaching the resin cover 6. As shown in FIG. 5 and FIG. 6, in the cover installation step, the resin cover 6, which includes a top cover 61, a first end cover 62, a first side divided cover 63, a second end cover 64, a second side divided cover 65, an inner peripheral cylinder 66, and an inner cover 67, are arranged along the surface of the coil 2 to cover the coil 2.

[0031] The top cover 61 is disposed on the top surface 24 of the coil 2, and covers a part or all of the top surface 24. When multiple coils 2 are disposed side by side, the top covers 61 of each coil 2 may be a seamless, integrally molded product. Here, the top surface 24 of the coil 2 is a surface parallel to the winding axis 26 of the coil 2, and is a surface located on the opposite side of the winding axis 26 of the coil 2 from the heat dissipation surface 23 of the coil 2. The top and bottom are based on the top and bottom when the coil 2 is housed when the coil 2 is resin-coated by molding, and do not refer to the positional relationship or direction when the molded coil 1 is mounted on the actual device to be installed.

[0032] The first end surface cover 62, the first side surface divided cover 63 and the inner cover 67 are a seamless integrally molded product. The first end surface cover 62 is a ring-shaped plate that covers the first end surface 21 of the coil 2. The first side surface divided cover 63 is a plate that covers part of the outer surface 25a of the coil 2. The inner cover 67 is a plate that covers part of the opposing side surface 25b of the coil 2.

[0033] The first end surface 21 of the coil 2 is a flat surface extending perpendicular to the winding axis 26 of the coil 2, and is the surface to which either the winding start or the winding end of the conductive wire 11 belongs. The outer surface 25a and the opposing side surface 25b of the coil 2 are surfaces parallel to the winding axis 26 of the coil 2, and are sandwiched between and adjacent to both the top surface 24 and the heat dissipation surface 23. The opposing side surface 25b faces the adjacent coil 2, and the outer surface 25a faces in the opposite direction to the adjacent coil 2.

[0034] The second end surface cover 64, the second side surface divided cover 65 and the inner peripheral tube 66 are a seamless integrally molded product. The second end surface cover 64 is a ring-shaped plate that covers the second end surface 22 of the coil 2. The second end surface 22 is a flat surface that extends perpendicular to the winding axis 26 of the coil 2 and is on the opposite side to the first end surface 21. The second side surface divided cover 65, together with the first side surface divided cover 63, is a plate that covers part of the outer surface 25a of the coil 2. The inner peripheral tube 66 is a cylindrical plate that covers the inner peripheral surface of the coil 2.

[0035] In particular, the first side divided cover 63 and the second side divided cover 65 extend along the boundary between the heat dissipating surface 23 and the outer side 25a, and are in close contact with the area from the edge of the heat dissipating surface 23 to the outer side 25a. The inner cover 67 extends along the boundary between the heat dissipating surface 23 and the opposing side 25b, and are in close contact with the area from the edge of the heat dissipating surface 23 to the opposing side 25b. The first end cover 62 and the second end cover 64 extend along the boundary between the heat dissipating surface 23 and the first end face 21 and the boundary between the heat dissipating surface 23 and the second end face 22, and are in close contact with the area from the edge of the heat dissipating surface 23 to the first end face 21 and the second end face 22.

[0036] The first side divided cover 63 and the second side divided cover 65 are disposed on the same outer surface 25a. The second side divided cover 65 has a pocket structure with a cover plate 73b, and the first side divided cover 63 is inserted between the cover plate 73b and the outer surface 25a of the coil 2.

[0037] Fig. 7 is an exploded view of the molded coil 1 with the cover plate 73b removed, and Fig. 8 is a perspective view of the molded coil 1 with the cover plate 73b removed. Also, Fig. 9 is a schematic diagram showing the relationship between the first side divided cover 63 and the second side divided cover 65 of the molded coil 1.

[0038] As shown in Figs. 7 to 9, the first side divided cover 63 has an insertion long plate portion 71. The insertion long plate portion 71 is a long plate extending along the winding shaft 26 toward the second end face 22, and extends while being in close contact with the outer side face 25a. On the other hand, the second side divided cover 65 has a U-shaped plate 73a. The U-shaped plate 73a has a shape of a U turned on its side, and has a U-shaped bottom portion 74, a resin inflow side long plate portion 75, and a heat dissipation surface side long plate portion 76. The U-shaped bottom portion 74 is a long plate extending in a direction from the heat dissipation surface 23 toward the upper surface 24, and extends along the edge of the second end face cover 64. The resin inflow side long plate portion 75 and the heat dissipation surface side long plate portion 76 are disposed at both ends in the extension direction of the U-shaped bottom portion 74, and are long plates extending along the winding shaft 26 toward the first end face 21 with the U-shaped bottom portion 74 as a base end, and extend while being in close contact with the outer surface 25a.

[0039] The total length of the first side split cover 63 and the second side split cover 65 is longer than the length along the winding shaft 26 of the coil 2. However, the positions at which the first side split cover 63 and the second side split cover 65 extend are different, and the first side split cover 63 and the second side split cover 65 extend past each other so as not to interfere with each other.

[0040] In this example of the first side divided cover 63 and the second side divided cover 65, the insertion long plate portion 71, the resin inflow side long plate portion 75, and the heat dissipation surface side long plate portion 76 are parallel along the winding shaft 25, but the resin inflow side long plate portion 75 and the heat dissipation surface side long plate portion 76 pass on both sides of the insertion long plate portion 71, and the resin inflow side long plate portion 75 and the heat dissipation surface side long plate portion 76 pass each other. Specifically, the heat dissipation surface side long plate portion 76 extends along the edge of the heat dissipation surface 23. The insertion long plate portion 71 is extended toward the upper surface 24 side beyond the heat dissipation surface side long plate portion 76. The resin inflow side long plate portion 75 is extended toward the opposite side of the heat dissipation surface side long plate portion 76 across the insertion long plate portion 71, and extends toward the upper surface 24 side beyond the insertion long plate portion 71.

[0041] The insertion long plate portion 71 extends toward the U-shaped bottom portion 74 and enters the opening of the U-shaped plate 73a, but does not reach the U-shaped bottom portion 74. In addition, there are gaps between the resin inflow side long plate portion 75 and the insertion long plate portion 71, and between the heat dissipation surface side long plate portion 76 and the insertion long plate portion 71. Therefore, an inlet side flow path 77b, which is a gap along the resin inflow side long plate portion 75 and the insertion long plate portion 71, is provided between the resin inflow side long plate portion 75 and the insertion long plate portion 71. A gap is provided between the extension tip of the insertion long plate portion 71 and the U-shaped bottom portion 74, which is an expansion chamber 78 of the labyrinth structure 7. An outlet side flow path 79a, which is a gap along the heat dissipation surface side long plate portion 76 and the insertion long plate portion 71, is provided between the resin inflow side long plate portion 75 and the insertion long plate portion 71.

[0042] The inlet side flow passage 77b, the expansion chamber 78, and the outlet side flow passage 79a are connected to each other, and form a gap in the shape of a U-shape laid on its side between the first side divided cover 63 and the second side divided cover 65. That is, the inlet side flow passage 77b reaches above the expansion chamber 78, and the lower part of the expansion chamber 78 is connected to the outlet side flow passage 79a. The flow passage width of the inlet side flow passage 77b and the outlet side flow passage 79a is narrower than the horizontal width of the expansion chamber 78, in other words, the horizontal width of the expansion chamber 78 is wider than the width of the inlet side flow passage 77b and the outlet side flow passage 79a. The horizontal width of the expansion chamber 78 is the distance between the extension tip of the insertion long plate portion 71 and the U-shaped bottom portion 74.

[0043] Preferably, the flow path width of the inlet side flow path 77b and the outlet side flow path 79a is 0.1 mm or more and 2 mm or less, and the width of the expansion chamber 78 is 6 mm or more. This allows the first side divided cover 63 and the second side divided cover 65 to slide relatively easily even when manufacturing errors are taken into account, and also makes it easier to reduce the loss of the resin injection pressure in the molding process.

[0044] At the base of the insertion long plate portion 71, i.e., at the boundary between the first side divided cover 63 and the insertion long plate portion 71, a barrier plate 72 spreads along the outer side surface 25a. The barrier plate 72 spreads two-dimensionally on the outer side surface 25a toward the upper surface 24 and the second end surface 22. The end of the resin inflow side long plate portion 75 extends toward the barrier plate 72, and an inlet side gap 77a is provided between the resin inflow side long plate portion 75 and the barrier plate 72. The inlet side flow passage 77b starts from the inlet side gap 77a and extends toward the expansion chamber 78. An outlet side gap 79b is provided between the outlet side flow passage 79a and the heat dissipation surface 23.

[0045] FIG. 10 is a perspective view showing a state in which the coil 2 is compressed in the molding process after such a cover installation process. Here, depending on the winding accuracy of the coil 2, the coil 2 may deviate from the final dimensional tolerance and become long, which may cause problems in assembling the coil 2 into the reactor 100, problems in mounting the coil 2 on the circuit, or gaps between the turns, which may cause resin leakage. On the other hand, in the winding process, the coil 2 may be intentionally made longer so that the coil 2 does not deviate from the final dimensional tolerance and become short. Therefore, in the mold for molding, prior to the injection of the fluid resin 8, the coil 2 is pressed along the winding shaft 26, and the length of the coil 2 along the winding shaft 26 is adjusted by compression, up to the maximum compression distance possible by the manufacturing device.

[0046] In the mold, one of the first end surface cover 62 and the second end surface cover 64 is fixed, and pressure is applied to the other along the winding shaft 26. The pressure is generated by the injection pressure of the fluid resin 8 that becomes the molding resin 9, by pressing with a pressing rod, or by both. The coil 2 is compressed by this pressure. Here, the resin cover 6 covering the outer surface 25a is divided into a first side divided cover 63 and a second side divided cover 65. In addition, the first side divided cover 63 and the second side divided cover 65 extend so as to pass each other. Therefore, the distance from the end of the first side divided cover 63 to the end of the second side divided cover 65 becomes variable, and the length of the coil 2 can be compressed. In addition, the distance from the end of the first side divided cover 63 to the end of the second side divided cover 65 changes in accordance with the length of the coil 2, so that the resin cover 6 covering the outer surface 25a fits in without protruding from the coil 2.

[0047] After or in parallel with the compression of the coil 2, fluid resin 8 is injected into the die to form molded resin 9. Also, in the die, an upper die (not shown) presses down the upper surface 24 of the coil 2 via an upper cover 61. This pressing force corrects any irregularities on the peripheral surface of the coil 2 in accordance with the upper cover 61. After or in parallel with the correction of the irregularities, fluid resin 8 is injected into the die to form molded resin 9.

[0048] FIG. 11 is a perspective view showing a state where the slide mold MS is pressed in the molding process. In FIG. 11, the upper and lower molds are omitted for convenience of explanation. As shown in FIG. 11, when the fluid resin 8 is injected, the slide mold MS abuts against the first side divided cover 63 and the second side divided cover 65 and applies pressure to press the first side divided cover 63 and the second side divided cover 65 against the outer surface 25a of the coil 2. The pressing force of the slide mold MS causes the first side divided cover 63 and the second side divided cover 65 to come into close contact with the outer surface 25a, so that the fluid resin 8 injected into the mold penetrates between the first side divided cover 63 and the outer surface 25a and between the second side divided cover 65 and the outer surface 25a, and is prevented from flowing into the heat dissipation surface 23.

[0049] In addition, in the mold, the first end cover 62, the second end cover 64, and the inner cover 67 arranged on the coil 2 are tightly attached to the lower mold (not shown) by pressing the upper surface 24 of the coil 2 with the upper cover 61 interposed therebetween. In addition, the inner cover 67 is tightly attached to the opposing side surface 25b of the coil 2 by a reaction force against the pressing force of the upper mold. This prevents the fluid resin 8 injected into the mold from penetrating between the first end cover 62 and the lower mold, between the second end cover 64 and the lower mold, between the inner cover 67 and the lower mold, and between the inner cover 67 and the opposing side surface 25b, and from flowing into the heat dissipation surface 23.

[0050] The gate of the fluid resin 8 is located in the area opposite the heat dissipation surface 23 across the first side split cover 63, the second side split cover 65, and the inner cover 67, or outside the first end face cover 62 or the second end face cover 64, and the fluid resin 8 is injected outside the compartment of the heat dissipation surface 23. However, in order to compress the coil 2, the resin cover 6 on the outer surface 25a is divided into the first side split cover 63 and the second side split cover 65. Therefore, a gap is generated between the first side split cover 63 and the second side split cover 65 that reaches the heat dissipation surface 23.

[0051] 12 is a schematic diagram showing the flowing resin 8 flowing between the first side divided cover 63 and the second side divided cover 65 in the molding process, and a labyrinth structure 7 is formed between the first side divided cover 63 and the second side divided cover 65. That is, between the first side divided cover 63 and the second side divided cover 65, the resin passes through gaps in the order of an inlet side gap 77a, an inlet side flow path 77b, an expansion chamber 78, an outlet side flow path 79a, and an outlet side gap 79b before reaching the heat dissipation surface 23.

[0052] Inlet-side gap 77a has its width narrowed in the direction along winding shaft 26 by barrier plate 72, and thus becomes a flow path in the vertical direction from top surface 24 to heat dissipation surface 23. Meanwhile, inlet-side flow path 77b extending from inlet-side gap 77a extends in the direction along winding shaft 26. Therefore, the flow path of fluid resin 8 undergoes a 90-degree bend in order to enter inlet-side flow path 77b from inlet-side gap 77a.

[0053] Next, the expansion chamber 78 to which the inlet side flow passage 77b reaches extends between the inlet side flow passage 77b and the outlet side flow passage 79a in the vertical direction from the upper surface 24 to the heat dissipation surface 23. Therefore, in order to move from the inlet side flow passage 77b to the outlet side flow passage 79a within the expansion chamber 78, the flow passage of the fluid resin 8 undergoes a 90 degree bend. Then, in order to enter the outlet side flow passage 79a from the expansion chamber 78, the flow passage of the fluid resin 8 undergoes a 90 degree bend from the flow direction of the expansion chamber 78.

[0054] In this way, a U-shaped labyrinth structure 7 is formed between the first side divided cover 63 and the second side divided cover 65, and the pressure of the flowing resin 8 is lost at various points, resulting in a loss of flow speed. Therefore, even if the resin cover 6 that is in close contact with the outer surface 25a is divided into the first side divided cover 63 and the second side divided cover 65, leakage of the flowing resin 8 to the heat dissipation surface 23 is suppressed.

[0055] Furthermore, since the barrier plate 72 is provided opposite the extending tip of the resin inflow side long plate portion 75, the inlet side gap 77a is narrowed, and the flow rate of the fluid resin 8 toward the labyrinth structure 7 is restricted. Furthermore, entering the narrowed inlet side gap 77a generates a swirling turbulent flow, causing a pressure loss of the fluid resin 8 and decreasing the flow rate of the fluid resin 8 toward the labyrinth structure 7. Therefore, the momentum of the fluid resin 8 is reduced before it enters the labyrinth structure 7, and even if it is divided into the first side divided cover 63 and the second side divided cover 65, leakage of the fluid resin 8 to the heat dissipation surface 23 is further suppressed.

[0056] Moreover, the expansion chamber 78 has a wider flow path width than the inlet side flow path 77b and the outlet side flow path 79a. Therefore, the flow from the expansion chamber 78 to the outlet side flow path 79a deteriorates, and a swirling turbulent flow occurs in the expansion chamber 78, causing a pressure loss in the fluid resin 8. Therefore, the fluid resin 8 is less likely to flow toward the outlet side flow path 79a, and even if the resin is divided into the first side divided cover 63 and the second side divided cover 65, leakage of the fluid resin 8 to the heat dissipation surface 23 is further suppressed.

[0057] As described above, the molded coil 1 is formed by covering the coil 2 with resin except for the heat dissipation surface 23 that extends along the winding shaft 26. The molded coil 1 is manufactured by including a cover installation step and a mold forming step. In the cover installation step, a first end face cover 62 and a second end face cover 64 that cover the first end face 21 and the second end face 22 of the coil 2, and a first side divided cover 63 and a second side divided cover 65 that are integrally molded with the first end face cover 62 and the second end face cover 64, extend along the edge of the heat dissipation surface 23, and cover a part of the circumferential surface of the coil 2 are installed. In the mold forming step, the first side divided cover 63 and the second side divided cover 65 are pressed against the coil 2 by a slide mold MS, and resin is injected into the mold while compressing the coil 2 in the direction of the winding shaft 26 via the first end face cover 62 and the second end face cover 64.

[0058] The first side divided cover 63 is molded integrally with the first end cover 62 and extends from the edge of the first end cover 62 along the winding shaft 26, and the second side divided cover 65 is molded integrally with the second end cover 64 and extends from the edge of the second end cover 64 along the winding shaft 26. The first side divided cover 63 and the second side divided cover 65 extend while passing each other, and a gap having a labyrinth structure 7 is formed between the first side divided cover 63 and the second side divided cover 65.

[0059] In this way, by dividing the resin cover 6 that adheres to the outer surface 25a of the coil 2 into the first side divided cover 63 and the second side divided cover 65, it is possible to compress the coil 2 and correct the length in the direction of the winding shaft 26. In addition, the first side divided cover 63 and the second side divided cover 65 have a cantilever structure, which makes it easier to press them against the outer surface 25a with the slide die MS, improving the adhesion of the first side divided cover 63 and the second side divided cover 65 to the outer surface 25a.

[0060] However, a gap is generated between the first side divided cover 63 and the second side divided cover 65, leading to the heat dissipation surface 23. However, because this gap has a labyrinth structure 7, the fluid resin 8 for forming the molded resin 9 loses injection pressure while passing through the labyrinth structure 7, and leakage of the resin to the heat dissipation surface 23 is suppressed.

[0061] In this molded coil 1, the first side split cover 63 has an insertion long plate portion 71 extending along the winding shaft 26, the second side split cover 65 has a U-shaped plate 73a into which the insertion long plate portion 71 is inserted, and the labyrinth structure 7 is a U-shaped gap between the insertion long plate portion 71 and the U-shaped plate 73a.

[0062] As a result, even though the labyrinth structure 7 has two bends in the flow path and is divided into the first side divided cover 63 and the second side divided cover 65, leakage of the flowing resin 8 onto the heat dissipation surface 23 can be suppressed.

[0063] However, the labyrinth structure 7 between the first side divided cover 63 and the second side divided cover 65 is not limited to this U-shaped gap. Two or more long plates may extend from the first side divided cover 63 along the winding shaft 26, and one more long plate than the first side divided cover 63 may extend from the second side divided cover 65 along the winding shaft 26, so that they pass each other in a staggered manner, thereby forming a more complicated labyrinth structure 7. Conversely, two or more long plates may extend from the second side divided cover 65 along the winding shaft 26, and one more long plate than the second side divided cover 65 may extend from the first side divided cover 63 along the winding shaft 26, so that they pass each other in a staggered manner, thereby forming a more complicated labyrinth structure 7.

[0064] The U-shaped gap is arranged on either side of the insertion long plate portion 71 and has two inlet side flow paths 77b and outlet side flow paths 79a extending along the winding shaft 26, and an expansion chamber 78 extending between the tip of the insertion long plate portion 71 and the U-shaped bottom portion 74 of the U-shaped plate 73a, and the expansion chamber 78 is wider than the inlet side flow path 77b and the outlet side flow path 79a.

[0065] This generates a swirling turbulent flow of the fluid resin 8 in the expansion chamber 78, increasing the pressure loss of the fluid resin 8. This further prevents the fluid resin 8 from leaking out to the heat dissipation surface 23. The labyrinth structure 7 may be made more complex, with multiple expansion chambers 78 provided with narrow flow paths between them.

[0066] The U-shaped plate 73a extends along the winding shaft 26, sandwiching the insertion long plate portion 71 of the first side divided cover 63, and has a heat dissipation surface side long plate portion 76 closer to the heat dissipation surface 23 than the insertion long plate portion 71 of the first side divided cover 63, and a resin inflow side long plate portion 75 on the opposite side to the heat dissipation surface side long plate portion 76, sandwiching the insertion long plate portion 71 of the first side divided cover 63. The first side divided cover 63 has a barrier plate 72 facing the tip of the resin inflow side long plate portion 75.

[0067] As a result, the inlet side gap 77a, which is the entrance to the inlet side flow path 77b, becomes narrower, restricting the flow rate of the fluid resin 8 into the labyrinth structure 7, and a vortex-like turbulent flow occurs near the inlet side gap 77a, reducing the pressure of the fluid resin 8 toward the labyrinth structure 7. This further prevents the fluid resin 8 from leaking out to the heat dissipation surface 23.

[0068] The above-mentioned embodiment of the present invention is presented as an example, and is not limited to the above-mentioned embodiment. The above-mentioned embodiment can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the scope of the invention. The embodiment and its modifications are included in the scope of the present invention. [Explanation of symbols]

[0069] 1 Molded coil 11 Conductive wire 2 Coil 21 First end surface 22 Second end face 23 Heat radiation surface 24 Top 25a External surface 25b Opposite side 26 Reel 6 Resin cover 61 Top cover 62 First end cover 63 First side split cover 64 Second end cover 65 Second side split cover 66 Inner cylinder 67 Inner cover 7 Labyrinth structure 71 Insertion long plate section 72 Barrier Board 73a U-shaped board 73b Lid plate 74 U-shaped bottom 75 Resin inflow side long plate 76 Heat dissipation side long plate part 77a Inlet side gap 77b Inlet side flow path 78 Expansion chamber 79a Outlet side flow path 79b Exit gap 8. Fluid Resin 9. Mold Resin 100 Reactor 110 cores 120 Secondary molding resin MS Slide Mold

Claims

1. A method for manufacturing a molded coil in which a coil is covered with resin except for a heat dissipation surface extending along a winding axis, comprising the steps of: a cover installation process for installing an end cover for covering an end face of the coil and a side cover that is integrally formed with the end cover, extends along an edge of the heat dissipation surface, and covers a part of a circumferential surface of the coil; a molding process in which the side covers are pressed against the coil by a slide die, and the resin is injected into the die while compressing the coil in the winding axis direction via the end covers; Including, The end cover includes a first end cover that covers one end surface of the coil and a second end cover that covers the other end surface of the coil, the side cover includes a first side divided cover that is integrally molded with the first end cover and extends from an edge of the first end cover along the winding shaft, and a second side divided cover that is integrally molded with the second end cover and extends from an edge of the second end cover along the winding shaft, the first side split cover and the second side split cover extend while passing each other, and a gap having a labyrinth structure is formed between the first side split cover and the second side split cover; A method for manufacturing a molded coil, comprising the steps of:

2. The first side divided cover has a long plate portion extending along the winding shaft, the second side divided cover has a U-shaped plate into which the long plate portion is inserted, the gap having the labyrinth structure is a U-shaped gap between the long plate portion and the U-shaped plate; 2. The method for producing a molded coil according to claim 1, further comprising the steps of:

3. The U-shaped gap is Two flow paths are disposed on both sides of the long plate portion and extend along the winding shaft; an expansion chamber extending between a tip of the long plate portion and a U-shaped bottom portion of the U-shaped plate; having The expansion chamber is wider than the two flow paths; 3. The method for producing a molded coil according to claim 2, further comprising the steps of:

4. the U-shaped plate extends along the winding shaft with the long plate portion of the first side divided cover sandwiched therebetween, and has a heat dissipation surface side long plate portion that is closer to the heat dissipation surface than the long plate portion of the first side divided cover, and a resin inflow side long plate portion that is opposite the heat dissipation surface side long plate portion with the long plate portion of the first side divided cover sandwiched therebetween, the first side divided cover has a barrier plate facing a tip end of the resin inflow side long plate portion; 4. The method for producing a molded coil according to claim 2 or 3, characterized in that

5. the second side divided cover has a cover plate that covers the U-shaped plate; 3. The method for producing a molded coil according to claim 2, further comprising the steps of:

6. The cover installation step includes: a first cover installation step of installing the first end surface cover and the first side surface divided cover; a second cover installation step of installing the second end surface cover and the second side surface divided cover; Including, the molding step includes pressing the first side divided cover and the second side divided cover against the coil with the slide die, and compressing the coil in a winding axis direction via one or both of the first end surface cover and the second end surface cover; 2. The method for producing a molded coil according to claim 1, further comprising the steps of:

7. a step of assembling the molded coil to a core including a magnetic body after the molded coil manufacturing method according to claim 1 is included; A method for manufacturing a reactor, comprising the steps of:

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