Molded coil manufacturing method and reactor manufacturing method

Abstract

To prevent burrs from forming on a molded resin of a coil, which has a portion of its surface exposed.SOLUTION: A frame body 58a is disposed on the surface of a coil 5, and the coil 5 is covered with a molded resin 8 except for the inside of the frame body 58a. The frame body 58a has a pair of vertical side portions 72 extending in the coil vertical direction along the cylindrical axis of the coil 5. The pair of vertical side portions 72 sandwich a lower surface 52, which is a single flat surface, and have hooks 76 that are in close contact with the two lower curved surfaces 53 adjacent to the lower surface 52 and restrict movement of the vertical side portions 72. The hooks 76 restrict the vertical side portions 72 from shifting outward in the lateral direction of the coil.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a molded coil formed by molding a coil with resin, and to a reactor having this molded coil. [Background technology]

[0002] A reactor has a coil and a core. To electrically insulate the coil from the core, the core is usually covered with a resin material, and the wound coil is attached to the core from above the resin material. This reactor is a passive element that converts electrical energy into magnetic energy and stores and releases it.

[0003] Such reactors are used in a wide variety of applications. Typical examples include boost reactors incorporated in onboard boost circuits for hybrid and electric vehicle drive systems, series reactors connected in series to motor circuits to limit current during short circuits, parallel reactors to stabilize current sharing between parallel circuits, current-limiting reactors to limit current during short circuits and protect connected machinery, starting reactors connected in series to motor circuits to limit starting current, shunt reactors connected in parallel to transmission lines to compensate for leading reactive power and suppress abnormal voltages, neutral reactors connected between the neutral and ground to limit ground-fault current in the event of a ground fault in the power system, and arc-suppression reactors to automatically extinguish arcs that occur in single-phase ground faults in three-phase power systems.

[0004] Molded coils, in which the outer periphery of the coil is covered with resin, are widely used in such reactors. In this type of reactor, part of the coil surface is sometimes left exposed without being covered with molded resin to ensure heat dissipation. To expose the coil surface, a proposal has been made to fill the surrounding area with molded resin while pressing a mold against the coil surface (see Patent Documents 1 to 3). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5869518 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-130410 [Patent Document 3] Japanese Patent Application Publication No. 2018-011019 Summary of the Invention [Problem to be solved by the invention]

[0006] The coil is made into a cylindrical shape by spirally winding a conductive wire around a winding shaft, with the winding position shifted for each turn. The coil has an outer shape consisting of four flat surfaces and four curved surfaces arranged alternately. Due to manufacturing precision requirements, the coil surface has irregularities and is not necessarily smooth. Therefore, even when attempting to fit the coil into a mold, a gap occurs between the mold and the coil surface. This gap can allow resin to seep in, potentially creating burrs on the exposed surface.

[0007] To improve heat dissipation, it is useful to extend the exposed area to the curved surface of the coil, rather than just the flat surface. However, because the curved surface of the coil must maintain a constant curvature throughout each turn and the same curvature must be maintained for all turns, it is particularly prone to unevenness, and the unevenness can easily become large. For this reason, it is difficult to extend the exposed area from the molding resin to the curved surface when using a manufacturing method in which the coil is pressed against a mold.

[0008] One way to prevent burrs from forming is to press the mold firmly against the coil surface. By pressing the mold firmly against the coil surface, it is possible to eliminate any gaps between the mold and the coil surface and to straighten any twists on the coil surface. However, pressing the mold too hard against the coil surface can cause problems such as damaging the coil or damaging the coating of the coil's conductive wire, resulting in a loss of insulation.

[0009] In this way, in a reactor in which part of the coil surface is covered with molding resin and part of the surface is exposed from the molding resin, it is required to prevent the coil from being damaged and to prevent the occurrence of burrs, but the above-mentioned conventional technology could not meet this demand.

[0010] The present invention has been proposed to solve the problems of the prior art as described above, and an object of the present invention is to provide a method for manufacturing a molded coil that suppresses the formation of burrs in the molding resin on the surface of a coil with a partially exposed surface, and a method for manufacturing a reactor that includes this molded coil. [Means for solving the problem]

[0011] The molded coil of this embodiment comprises a cylindrical coil having an outer shape in which four flat surfaces and four curved surfaces are arranged alternately, a frame body placed on the surface of the coil, and molded resin covering part or all of the coil except for the inside of the frame body, wherein the frame body has a pair of vertical side portions extending along the cylindrical axis of the coil, the pair of vertical side portions sandwiching one of the flat surfaces and being in close contact with the two curved surfaces adjacent to the flat surface, and the pair of vertical side portions having hooks perpendicular to the vertical side portions and restricting movement of the vertical side portions in a horizontal direction parallel to the flat surfaces sandwiched between the pair of vertical side portions, and toward the outside of the coil.

[0012] The pair of vertical side portions may be spaced apart from the flat surface sandwiched between the pair of vertical side portions.

[0013] The frame body may be defined by a combination of horizontal side walls and a U-shaped frame, and the U-shaped frame may include a pair of vertical side portions and one horizontal side portion extending between the pair of vertical side portions, and may have a U-shaped shape with no opposing side of the horizontal side portion.

[0014] The hook may be provided closer to the flat surface sandwiched between the pair of vertical side portions than to a region in the curved surface where the pair of vertical side portions are in close contact with each other.

[0015] The hook may be provided at a tip of one of the pair of vertical side portions that extends from the horizontal side portion.

[0016] The hook may further include a first protrusion extending in an up-down direction perpendicular to the vertical and horizontal directions, and the hook may have a second protrusion extending in the up-down direction, the first protrusion and the second protrusion being aligned in the horizontal direction and in contact with each other on their sides, and the first protrusion may be positioned outside the coil relative to the second protrusion.

[0017] The hook may further include a plate body that is placed on another flat surface located opposite the flat surface sandwiched between the pair of vertical side portions, the first protrusion portion being directly or indirectly connected to the plate body, the hook having an arm portion extending laterally at its tip from which the second protrusion portion rises, and the first protrusion portion being in contact with the arm portion at its end surface.

[0018] The coil may further include an annular edge plate extending from the plate body and covering one end surface of the coil, and the first protrusion may be provided on the annular edge plate.

[0019] The hook may be located outside the coil relative to the annular edge plate in the longitudinal direction, and the hook and the annular edge plate may be in surface contact with each other.

[0020] A reactor including this molded coil and a core including a magnetic body to which the molded core is attached is also one aspect of the present invention. [Effects of the Invention]

[0021] According to the present invention, even if the exposed area of ​​the coil is expanded to the curved surface where burrs are likely to occur when the coil is directly pressed with a mold, the occurrence of burrs can be suppressed and heat dissipation is excellent. [Brief explanation of the drawings]

[0022] [Figure 1]FIG. 2 is a perspective view of the reactor, omitting members covering each portion. [Figure 2] FIG. 1 is a top perspective view showing a coated coil. [Figure 3] 1A is a perspective view showing the covering members of the coil, FIG. 1B is a perspective view showing the upper cover, FIG. 1C is a perspective view showing the molding resin. [Figure 4] FIG. 2 is a bottom perspective view showing the molded coil. [Figure 5] FIG. [Figure 6] FIG. [Figure 7] FIG. 10 is a transition diagram showing the assembly of the upper cover and the lower cover. [Figure 8] 1A and 1B show the state of the upper cover, lower cover, and coil inside the mold, where FIG. 1A is a cross-sectional perspective view of the lower curved surface of the coil, and FIG. 1B is a cross-sectional view of the lower curved surface of the coil. [Figure 9] 1A and 1B show the state of the upper cover, the lower cover, and the coil inside the mold, where FIG. 1A is a perspective view seen from the first end face side, and FIG. 1B is a plan view seen from the first end face side. [Figure 10] FIG. 10 is a bottom perspective view showing the state of the upper cover, the lower cover, and the coil inside the mold. [Figure 11] FIG. 10 is a perspective view showing another configuration of the reactor. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, reactors according to embodiments of the present invention will be described with reference to the drawings. In each drawing, thickness, dimensions, positional relationships, ratios, shapes, etc. may be exaggerated for ease of understanding, but the present invention is not limited to such exaggeration.

[0024] 1 is a perspective view showing the main configuration of a reactor of this embodiment, and for convenience of explanation, the members covering each part are omitted. The reactor 100 includes a reactor body 10. The reactor body 10 includes two coils 5, 5 and one annular core 1. The two coils 5, 5 are attached to the core 1.

[0025] When energized, the coils 5 generate magnetic flux according to the number of turns. The core 1 forms a closed magnetic circuit through which the magnetic flux generated by the coils 5 passes with a magnetic permeability higher than that of a vacuum. In other words, the reactor 100 is an electromagnetic component that converts electrical energy into magnetic energy and stores and releases it.

[0026] The core 1 contains a magnetic material such as a powder magnetic core, a ferrite magnetic core, a metal composite core, or a laminated steel plate. A powder magnetic core is an annealed compact made by compressing magnetic powder. The magnetic powder is primarily composed of iron, and examples thereof include pure iron powder, iron-based permalloy (Fe-Ni alloy), 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. A metal composite core is a core made by kneading and molding magnetic powder and resin.

[0027] The coil 5 is a cylindrically wound body of conductive wire 59, such as copper wire. The coil 5 is formed by winding the conductive wire 59 in a spiral shape along a winding axis while shifting the winding position for each turn. The conductive wire 59 extends from the beginning and end of each of the coils 5, 5. Each conductive wire 59 is electrically connected to a bus bar, so that the coils 5, 5 are electrically connected in parallel or in series.

[0028] The coil 5 has an outer shape formed by alternating four curved surfaces and four flat surfaces parallel to the cylindrical axis. That is, the coil 5 has a flat upper surface 51 parallel to the plane where the annular shape of the core 1 appears, and a flat lower surface 52 opposite the upper surface 51. The coil 5 has a flat side surface 54 perpendicular to the upper surface 51 and the lower surface 52. The coil 5 has a lower curved surface 53 between the lower surface 52 and the side surface 54, and an upper curved surface 56 between the upper surface 51 and the side surface 54. Furthermore, the coil 5 has annular first end surface 55 and second end surface 57 located at the start and end of the winding of the conductive wire 59 and perpendicular to the cylindrical axis.

[0029] The flat surface of the coil 5 refers to a surface that is flat relative to a curved surface, and also includes a surface that forms a large arc with a gentle curvature due to the bulging of the conductive wire 59. The top and bottom refer to the upper and lower molds that house the coils 5, 5 when covering the coils 5, 5 by molding, and do not refer to the positional relationship or direction when the reactor 100 is mounted on the actual device to be installed.

[0030] In the reactor body 10, the horizontal direction refers to the Y-axis direction, which is parallel to the bottom surface 52 of the coil 5 and perpendicular to the side surface 54 of the coil 5. The direction from the cylindrical axis of the coil 5 to the side surface 54 is referred to as the outer side in the horizontal direction. The opposite side of the outer side in the horizontal direction is referred to as the inner side in the horizontal direction. The vertical direction refers to the X-axis direction, which is perpendicular to the horizontal direction, parallel to the bottom surface 52, along the cylindrical axis, and parallel to the side surface 54. The direction from the center position equidistant between the first end surface 55 and the second end surface 57 to the first end surface 55 or the second end surface 57 is referred to as the outer side in the vertical direction. The opposite side of the outer side in the vertical direction is referred to as the inner side in the horizontal direction. The vertical direction refers to the Z-axis direction, which is perpendicular to the top surface 51 and the bottom surface 52. The direction from the bottom surface 52 toward the top surface 51 is referred to as the upper side, and the direction from the top surface 51 toward the bottom surface 52 is referred to as the lower side.

[0031] Fig. 2 is a top perspective view showing the covered coils 5, 5. As shown in Fig. 2, each of the two coils 5, 5 is a molded coil. That is, the coils 5, 5 are covered with an upper cover 6, a lower cover 7, and a molded resin 8, and together with these covering members, form a molded coil. In other words, the molded coil includes the coil 5, the upper cover 6, the lower cover 7, and the molded resin 8.

[0032] The upper cover 6, the lower cover 7 and the molded resin 8 are made of resin with insulating and heat-resistant properties, and the coils 5, 5 are covered by these upper cover 6, lower cover 7 and molded resin 8, so that they are electrically insulated from the core 1 and fitted into the core 1.

[0033] Examples of resins with insulating and heat-resistant properties include PPS (Polyphenylene Sulfide), epoxy resin, unsaturated polyester resin, urethane resin, BMC (Bulk Molding Compound), PPS (Polyphenylene Sulfide), PBT (Polybutylene Terephthalate), and composites of these. The upper cover 6, the lower cover 7, and the molded resin 8 may be made of the same material or different materials. A thermally conductive filler may be mixed into the materials of the upper cover 6, the lower cover 7, and the molded resin 8.

[0034] As shown in Figure 3(a), the upper cover 6 has an upper plate 61, side curved plates 62, and annular edge plate 63. The upper plate 61, side curved plates 62, and annular edge plate 63 are seamlessly connected together by integral molding or the like. The upper plate 61 is a solid, flat plate extending parallel to the upper surface 51 of the coil 5, and covers the upper surface 51 of the coil 5. The side curved plates 62 extend from both outer edges of the upper plate 61 in the lateral direction of the coil, and cover the upper curved surface 56 and the upper edge regions of the side surfaces 54 that are adjacent to the upper curved surface 56.

[0035] The edge annular plate 63 extends from the coil longitudinal end edge of the upper plate 61, extends downward perpendicular to the upper plate 61, and covers the conductive wires 59 appearing on the first end face 55 of the coil 5. A horizontal side wall 64 is formed at the lower end of the edge annular plate 63, which extends across the entire area of ​​the lower surface 52 of the coil 5 in the coil transverse direction and across both lower edge areas 53a of the lower curved surface 53 adjacent to the lower surface 52, and extends below the lower surface 52 in the vertical direction.

[0036] As shown in Figure 3(b), the lower cover 7 has a U-shaped frame 71 and an annular edge plate 74. The U-shaped frame 71 and the annular edge plate 74 are seamlessly connected together by integral molding or the like. The U-shaped frame 71 has a rectangular U-shaped frame shape with one side missing, and surrounds the entire area of ​​the lower surface 52 of the coil 5 and a lower edge area 53a of the lower curved surface 53 adjacent to the lower surface 52 on three sides. This U-shaped frame 71 extends downward below the lower surface 52.

[0037] On the other hand, in the upward direction, the U-shaped frame 71 expands to face and cover the lower curved surface 53 and the lower region of the side surface 54, excluding the lower edge region 53a. The edge annular plate 74 extends upward from the side of the U-shaped frame 71 that extends in the coil lateral direction, and extends upward perpendicular to the U-shaped frame 71, covering the conductive wire 59 that appears on the second end surface 57 of the coil 5.

[0038] The molding resin 8 is formed by placing the coil 5 on which the upper cover 6 and the lower cover 7 are installed in a mold, and injecting and solidifying the resin into the mold. In the mold, the upper cover 6 and the lower cover 7 come into contact with the mold, except for the outer surface of the annular edge plate 63 of the upper cover 6 that faces outward in the longitudinal direction of the coil, and the surface of the annular edge plate 74 of the lower cover 7 that faces outward in the longitudinal direction of the coil.

[0039] 3(c), the molded resin 8 covers the remaining portion of the side surface 54, which is the gap between the upper cover 6 and the lower cover 7, the first end surface 55, the second end surface 57, and the inner peripheral surface of the coil 5. The molded resin 8 covers the first end surface 55 from above the annular edge plate 63 of the upper cover 6, and covers the second end surface 57 from above the annular edge plate 74 of the lower cover 7.

[0040] 4 is a bottom perspective view showing the molded coil. The coil 5 is covered with an upper cover 6, a lower cover 7, and a molded resin 8, and an opening 58 is formed on part of the surface to improve heat dissipation. The opening 58 exposes the entire lower surface 52 of the coil 5 in the coil horizontal direction and a lower edge region 53a of the lower curved surface 53 adjacent to the lower surface 52. The opening 58 exposes the entire lower surface 52 in the coil vertical direction.

[0041] A frame body 58a is provided on the surface of the coil 5. The interior of this frame body 58a is the opening 58. The frame body 58a rises below the lower surface 52 along its entire periphery, and its lower edge is at the same height along its entire periphery. Therefore, the frame body 58a is seated in the mold without any gaps along its entire periphery. Inside the mold, the inside of the frame body 58a is sealed by the frame body 58a and the mold. Therefore, inside the mold, the molding resin 8 covers the coil 5 except for the interior of the frame body 58a, and the molding resin 8 does not flow into the frame body 58a, forming the opening 58.

[0042] This frame body 58a is defined by a combination of the U-shaped frame 71 of the lower cover 7 and the horizontal side wall 64 of the upper cover 6. The upper cover 6 and the lower cover 7 that define the opening 58 will be described in more detail below.

[0043] Fig. 5 is an enlarged perspective view of the upper cover 6. As shown in Fig. 5, the upper central region of the annular edge plate 63 is cut out toward the upper plate body 61, the annular edge plate 63 is discontinued, and an outlet 63a is formed for leading the conductive wire 59 of the coil 5 from the first end surface 55. The lower part of the annular edge plate 63 forms a horizontal side wall 64 that surrounds the opening 58.

[0044] The length of the horizontal side wall 64 along the coil horizontal direction extends from the outer end of one lower edge region 53a that fits into the opening 58 to the outer end of the other lower edge region 53a. The horizontal side wall 64 also extends from the upper limit of one lower edge region 53a that fits into the opening 58 or above this upper limit to below the lower surface 52 that fits into the opening 58. The lowest edge of the horizontal side wall 64 extends linearly at a constant height.

[0045] A pair of first protrusions 65 bulge from the horizontal side wall 64. Each first protrusion 65 bulges outward in the horizontal direction of the coil. The first protrusions 65 have a rectangular parallelepiped shape. A rear end 65c is continuous with the first protrusion 65 without any joint. The rear end 65c is formed continuously from the first protrusion 65 and curves upward to follow the edge of the annular edge plate 63 while following the lower curved surface 53.

[0046] Each first protrusion 65 has a protrusion end surface 65b and a protrusion side surface 65a. The protrusion side surface 65a faces inward in the lateral direction of the coil. This protrusion side surface 65a rises vertically from the lateral side wall 64 and extends perpendicular to the lateral direction of the coil and parallel to the up-down direction. The protrusion end surface 65b faces directly downward. This protrusion end surface 65b rises vertically from the lateral side wall 64 and extends perpendicular to the up-down direction and parallel to the lateral direction of the coil.

[0047] The first protrusion 65 bulges out so that the protrusion end surface 65b fits within the horizontal side wall 64. A protrusion surrounding region 66 adjacent to the protrusion side surface 65a and the protrusion end surface 65b extends around the first protrusion 65. The horizontal side wall 64 may bulge out to the same height as the first protrusion 65, leaving the protrusion surrounding region 66. In this case, the protrusion surrounding region 66 has an L-shape that follows the protrusion side surface 65a and the protrusion end surface 65b.

[0048] Fig. 6 is an enlarged perspective view of the lower cover 7. As shown in Fig. 6, the upper central region of the annular edge plate 74 is cut out, the ring of the annular edge plate 74 is interrupted, and an outlet 74a is formed for leading the conductive wire 59 of the coil 5 out from the second end surface 57. The U-shaped frame 71 of the lower cover 7 has a U-shape formed by a pair of vertical side portions 72 and one horizontal side portion 73.

[0049] The vertical side portion 72 extends in the longitudinal direction of the coil, in other words, along the cylindrical axis direction of the coil 5. The vertical side portion 72 has a curved portion 721 and a vertical portion 722. The curved inner surface of the curved portion 721 comes into close contact with the coil 5. The vertical portion 722 is part of the wall of the frame body 58a that rises around the opening 58.

[0050] The curved portions 721 are disposed across the lower surface 52 and are in close contact with the lower curved surface 53 of the coil 5, excluding the lower edge regions 53a. The lower end of the curved portion 721 on the inner circumferential surface side is located at the upper limit of the lower edge region 53a that fits within the opening 58, and does not reach the lower surface 52. The vertical portion 722 continues from the lower end of the curved portion 721 and extends perpendicular to the plane in which the lower surface 52 of the coil 5 extends. The vertical portions 722 of the pair of vertical side portions 72 are separated by a distance that is the total width of the lower surface 52 of the coil 5 plus the lower edge regions 53a of the lower curved surfaces 53 that are exposed through the opening 58. In other words, the vertical portions 722 extend away from the lower surface 52.

[0051] The vertical portion 722 extends downward below the lower surface 52 so that the lower surface 52 can be accommodated within the opening 58. The lowermost edge of the vertical portion 722 extends linearly at a constant height. Note that the vertical side portion 72 is set taking into consideration the vertical shrinkage of the coil 5 due to the injection pressure of the molding resin 8.

[0052] The horizontal side portion 73 extends in the coil horizontal direction, in other words, perpendicular to the cylindrical axis of the coil 5, and parallel to the lower surface 52 of the coil 5, and extends along the second end surface 57 of the coil 5, completely crossing the second end surface 57. The length of the horizontal side portion 73 in the coil horizontal direction extends from the outer end of one lower edge region 53a that fits within the opening 58 to the outer end of the other lower edge region 53a. The horizontal side portion 73 also extends downward below the lower surface 52 so that the lower surface 52 can fit within the opening 58. The lowest edge of the horizontal side portion 73 extends linearly at the same height as the vertical portion 722.

[0053] The horizontal side portion 73 is part of the wall of the frame body 58a that rises around the opening 58. The horizontal side wall 64 of the upper cover 6 fits between the vertical portions 722 of the vertical side portion 72, and the horizontal side wall 64 of the upper cover 6 and the horizontal side portion 73 become opposing sides, thereby forming the frame body 58a.

[0054] Furthermore, the vertical side portions 72 are provided with hooks 76 at the ends of their extensions opposite the horizontal side portions 73, i.e., at the ends of the first end faces 55. These hooks 76 catch on the first protrusions 65 of the upper cover 6, thereby restricting the vertical side portions 72 from moving apart and preventing the vertical side portions 72 from opening outward in the horizontal direction of the coil.

[0055] Hooks 76 extend from each vertical portion 722. In other words, vertical portion 722 is located below the region of lower curved surface 53 where curved portion 721 is in close contact, and abuts on the lower surface 52 side. In other words, hooks 76 are installed at positions close to opening 58 into which mold resin 8 must not enter.

[0056] The hook 76 has a horizontally laid L-shape and is seamlessly connected to an arm portion 77 and a second protrusion portion 78. The arm portion 77 extends from the outer end of the vertical portion 722 in the longitudinal direction of the coil and extends inward in the lateral direction of the coil. The second protrusion portion 78 extends from the inner end of the arm portion 77 in the lateral direction of the coil and extends upward.

[0057] The arm portion 77 has a rectangular parallelepiped shape and has an arm upper side surface 77a facing upward. When the upper cover 6 and the lower cover 7 are positioned relative to the coil 5, the arm upper side surface 77a and the protrusion end surface 65b of the first protrusion 65 formed on the upper cover 6 are positioned at the same height. Furthermore, when the upper cover 6 and the lower cover 7 are positioned relative to the coil 5, the arm upper side surface 77a and the protrusion end surface 65b of the first protrusion 65 are positioned and positioned in a range such that the protrusion end surface 65b of the first protrusion 65 fits within the range over which the arm upper side surface 77a extends.

[0058] The second protrusion 78 has a rectangular parallelepiped shape and has a protrusion side surface 78a facing outward in the lateral direction of the coil. The formation position of the protrusion side surface 78a of the hook 76 and the protrusion side surface 65a of the first protrusion 65 of the upper cover 6 are set so that when the upper cover 6 and the lower cover 7 are positioned relative to the coil 5, the positions of the protrusion side surface 78a of the hook 76 and the protrusion side surface 65a of the first protrusion 65 of the upper cover 6 are the same in the lateral direction of the coil. The formation position and range of the protrusion side surface 78a of the hook 76 and the protrusion side surface 65a of the first protrusion 65 of the upper cover 6 are set so that the extension range of the protrusion side surface 78a of the hook 76 fits within the protrusion side surface 65a of the upper cover 6.

[0059] Furthermore, when the upper cover 6 and the lower cover 7 are positioned relative to the coil 5, the hook 76 is located outside the protrusion surrounding region 66 of the upper cover 6 in the coil longitudinal direction, and the extending position of the hook 76 in the coil longitudinal direction is set so that the hook back surface 76a of the hook 76 and the protrusion surrounding region 66 of the upper cover 6 are in the same position in the coil longitudinal direction. The hook back surface 76a is the surface of the hook 76 facing inward in the coil longitudinal direction.

[0060] The assembly of the upper cover 6 and lower cover 7 to the coil 5 will now be described. As shown in Figure 7(a) , when the lower cover 7 is fitted onto the coil 5, the hooks 76 are positioned outward in the longitudinal direction of the coil from the first end face 55, separated by the thickness of the protrusion surrounding region 66 of the horizontal side wall 64 of the upper cover 6. The hooks 76 are also positioned so as to overlap the first end face 55 in the longitudinal direction of the coil. The upper cover 6 is placed on the coil 5 so that the upper plate body 61 lands on the top surface 51, while the conductive wires 59 drawn out from the first end face 55 are passed through the ring of the edge annular plate 63.

[0061] As shown in Fig. 7(b), the protrusion surrounding area 66 is slid between the first end surface 55 and the hook 76, and the protrusion end surface 65b of the first protrusion 65 of the upper cover 6 is butted against the arm upper surface 77a of the arm portion 77 of the hook 76. Then, as shown in Fig. 7(c), the second protrusion 78 of the hook 76 is positioned inside the first protrusion 65 of the upper cover 6 in the coil lateral direction.

[0062] The process of forming the mold resin 8 after the upper cover 6 and lower cover 7 are attached will be described. The coil 5 with the upper cover 6 and lower cover 7 attached is placed in a mold. Inside the mold, the frame 58a is placed on the flat surface of the lower mold, and the upper mold is placed over the upper cover 6.

[0063] 8(a) and 8(b), inside the mold, the upper plate 61 of the upper cover 6 is pressed downward by the upper mold. This downward force P1 is transmitted to the coil 5, and the lower curved surface 53 of the coil 5 is pressed against the curved portion 721 of the lower cover 7. A force P2 is generated from the lower curved surface 53 to the curved portion 721 in the normal direction to the lower curved surface 53 and the curved portion 721.

[0064] If the U-shaped frame 71 is stationary, the force P2 presses the curved portion 721 against the lower curved surface 53, correcting any irregularities or twists in the lower curved surface 53 and ensuring that the curved portion 721 and the lower curved surface 53 are tightly attached without any gaps. This prevents the resin of the mold resin 8 from entering the opening 58 and causing burrs.

[0065] However, this normal force P2 has a force component P3 that acts outward in the horizontal direction of the coil. This force component P3 tries to open the vertical side portions 72 of the U-shaped frame 71 outward in the horizontal direction of the coil. In other words, the vertical side portions 72 try to shift position so that the ends of the pair of vertical side portions 72 on the first end faces 55 side move apart. If the vertical side portions 72 open outward in the horizontal direction of the coil, the lower curved surface 53 of the coil 5 cannot be pressed against the curved portion 721.

[0066] 9(a) and 9(b), in this reactor 100, a hook 76 is formed on the outer end of the vertical side portion 72 in the coil vertical direction. The hook 76 is caught on the first protrusion 65 of the upper cover 6, which is held down by a mold and is immovable. Therefore, a force component P4 directed inward in the coil horizontal direction, which opposes the force component P3 directed outward in the coil horizontal direction, is applied from the protrusion side surface 65a of the first protrusion 65 to the protrusion side surface 78a of the hook 76, and the vertical side portion 72 having the hook 76 is prevented from opening outward in the coil horizontal direction.

[0067] In particular, the hook 76 is disposed between the upper limit of the lower edge region 53a of the lower curved surface 53 and the lowermost end of the vertical portion 722. This reduces the risk of the vertical side portion 72 twisting open at the opening 58.

[0068] Furthermore, the protrusion end surface 65b of the first protrusion 65 and the arm upper surface 77a of the hook 76 are in contact in the vertical direction. Therefore, the arm portion 77 of the hook 76 is sandwiched between the first protrusion 65 and the lower mold due to the force with which the upper mold presses the upper cover 6. Therefore, it is difficult for the hook 76 and the first protrusion 65 to be disengaged.

[0069] Here, if the vertical side portion 72 extends until it contacts the underside 52 of the coil 5, the vertical side portion 72 will be sandwiched between the underside 52 of the coil 5 and the mold. In this case, the downward force applied by the upper mold to the upper plate body 61 of the upper cover 6 makes it difficult for the vertical side portion 72 to come out from between the underside 52 and the mold, and the vertical side portion 72 is prevented from opening outward in the lateral direction of the coil.

[0070] However, in this reactor 100, in order to enlarge the opening 58 of the coil 5 in the coil lateral direction, the vertical side portion 72 defining the frame body 58a extends vertically downward from the upper limit of the lower edge region 53a of the lower curved surface 53 of the coil 5. In other words, the vertical side portion 72 does not extend until it contacts the lower surface 52 of the coil 5, but is spaced apart from the lower surface 52 and is not sandwiched between the lower surface 52 and the mold.

[0071] Furthermore, if the U-shaped frame 71 were a rectangular frame shape having four sides, specifically if the horizontal side walls 64 of the upper cover 6 were provided on the lower cover 7 and seamlessly connected to the U-shaped frame 71, the tension of the horizontal side walls 64 would prevent the vertical side portions 72 from opening outward in the lateral direction of the coil.

[0072] However, the injection pressure of the molding resin 8 in the mold causes a phenomenon in which the coil 5 is compressed so as to shorten the vertical length of the coil 5. If the horizontal side wall 64 is positioned on the first end surface 55 as part of the U-shaped frame 71 before the resin is injected, this compression of the coil 5 will create a gap between the first end surface 55 and the horizontal side wall 64. This will cause the resin to leak into the frame body 58a, resulting in burrs in the opening 58.

[0073] Therefore, in this reactor 100, in order to enlarge the opening 58 of the coil 5 in the coil longitudinal direction, the frame body 58a is separated into a U-shaped frame 71 and a horizontal side wall 64, and the horizontal side wall 64 is made movable in accordance with the compression of the coil 5. In response to the compression of the coil 5, the edge annular plate 63 of the upper cover 6 also moves inward in the coil longitudinal direction. As a result, the horizontal side wall 64 comes into close contact with the first end face 55 and fits into the open U-shaped portion of the U-shaped frame 71 of the lower cover 7. This defines the frame body 58a, which tightly surrounds the opening 58 on all four sides.

[0074] When the frame body 58a is separated into the U-shaped frame 71 and the horizontal side wall 64, another method for preventing the vertical side portion 72 from opening is to support the vertical side portion 72 of the lower cover 7 from the outside with a mold, rather than providing hooks 76. However, in this case, the vertical side portion 72 cannot be supported to prevent opening unless the degree of adhesion between the mold and the lower cover 7 is increased. On the other hand, if an attempt is made to increase the degree of adhesion between the mold and the lower cover 7, some lower covers 7 may not fit into the mold, depending on the dimensional accuracy of the mold and the lower cover 7. This could result in a decrease in the yield of lower covers 7.

[0075] However, in this reactor 100, hooks 76 are formed on the outer end of vertical side portion 72 in the longitudinal direction of the coil, so whether opening 58 is extended to lower curved surface 53 or to the entire longitudinal direction of the coil on lower surface 52, it is possible to prevent burrs from occurring in opening 58, and it is also possible to prevent the lower cover 7 from not being able to fit into the mold even if there are some individual differences in the lower cover 7, thereby reducing the yield of the lower cover 7.

[0076] 10, the hook back surface 76a of the hook 76 and the protrusion peripheral region 66 overlap, and the boundary between the horizontal side wall 64 of the upper cover 6 and the vertical side portion 72 of the U-shaped frame 71 of the lower cover 7 forms a labyrinth structure all the way to the opening 58. In other words, even if resin of the molded resin 8 seeps in between the hook 76 and the first protrusion 65, this resin will not reach the opening 58 unless it further passes between the hook back surface 76a and the protrusion peripheral region 66.

[0077] Moreover, the hook back surface 76a and the protrusion peripheral region 66 are aligned in the coil vertical direction and are pressed together by the injection pressure of the molded resin 8. This makes it difficult for the resin of the molded resin 8 to pass through the hook back surface 76a and the protrusion peripheral region 66 and reach the opening 58.

[0078] As a result, even if the area included in opening 58 is expanded to include not only the entire lower surface 52 but also the lower edge region 53a of the lower curved surface 53, opening 58 is formed in which burrs are suppressed, and this coil 5 has excellent heat dissipation properties.

[0079] 11(a), the reactor 100 may be provided with a sensor unit 3 such as a thermistor for detecting temperature, and as shown in FIG. 11(b), the coil 5 including the core 1 may be further covered with molded resin 4, except for the opening 58. The molded resin 4 has fastening holes 41 formed therein for fixing the reactor 100 to an installation target.

[0080] As described above, a molded coil was produced by placing a frame 58a on the surface of the coil 5 and covering the coil 5 with mold resin 8 except for the interior of the frame 58a. The frame 58a has a pair of vertical sides 72 extending in the coil longitudinal direction along the cylindrical axis of the coil 5. The pair of vertical sides 72 sandwich a lower surface 52, which is a single flat surface, and are in close contact with the two lower curved surfaces 53 adjacent to the lower surface 52. The pair of vertical sides 72 has hooks 76 that restrict movement of the vertical sides 72. The hooks 76 are perpendicular to the vertical sides 72 and restrict displacement of the vertical sides 72 outward in the lateral direction of the coil, i.e., in the lateral direction parallel to the lower surface 52 and toward the outside of the coil.

[0081] As a result, even if vertical side portions 72 attempt to shift position due to the force applied from lower curved surface 53 to the outside in the coil lateral direction, hooks 76 catch and prevent the position from shifting. Therefore, vertical side portions 72 do not open apart from each other, and molding resin 8 is prevented from flowing into the frame of frame body 58a, which would otherwise cause burrs. As a result, even if the range of opening 58 is expanded to include lower edge region 53a of lower curved surface 53, burrs can be prevented from occurring and heat dissipation is also excellent.

[0082] The hooks 76 are particularly effective when the pair of vertical side portions 72 are spaced apart from the underside 52. Furthermore, the frame body 58a is further effective when it is defined by a combination of the horizontal side wall 64 and a U-shaped frame 71, the U-shaped frame 71 including a pair of vertical side portions 72 and one horizontal side portion 73 extending between the pair of vertical side portions 72, and the horizontal side portion 73 has a U-shape with no opposing side. However, there is a risk that the vertical side portion 72 may slip out even if it is clamped between the underside 52 and the lower mold of the mold, and therefore the hooks 76 may be provided.

[0083] Furthermore, the hooks 76 are provided closer to the lower surface 52 than the area in the lower curved surface 53 where the pair of vertical side portions 72 are in close contact with each other. This reduces the risk of the vertical side portions 72 twisting open near the opening 58. If the vertical side portions 72 are highly rigid and the hooks 76 can be provided on either side, the hooks 76 may be provided on either side.

[0084] Furthermore, the hook 76 further includes a first protrusion 65, and has a second protrusion 78 extending in the vertical direction, the first protrusion 65 and the second protrusion 78 being aligned in the horizontal direction and contacting each other on their side surfaces, and the first protrusion 65 being positioned outside the coil relative to the second protrusion 78. This allows the hook 76 to prevent the vertical side portions 72 from opening. However, the shape of the hook 76 is not limited to this as long as it can prevent the vertical side portions 72 from opening.

[0085] The device further includes an upper plate 61 arranged on the upper surface 51 opposite the lower surface 52, the first protrusion 65 being directly or indirectly connected to the upper plate 61, the hook 76 having an arm 77 extending laterally and having a second protrusion 78 rising from its tip, and the first protrusion 65 being in contact with the arm 77 at the protrusion end surface 65b.

[0086] The upper plate 61 receives force from the upper mold of the metal mold. The first protrusion 65, which is directly or indirectly connected to the upper plate 61, also presses the arm portion 77 downward. This reduces the possibility that the engagement between the hook 76 and the first protrusion 65 will be released, reducing the risk of the vertical side portion 72 opening. In this manner, the edge annular plate 63 extends from the upper plate 61, and the first protrusion 65 is provided on this edge annular plate 63. However, this is not limiting, and the first protrusion 65 may be provided on the upper plate 61 and extended to the position of the arm portion 77.

[0087] Furthermore, the hooks 76 are positioned further outward in the coil longitudinal direction than the annular edge plate 63 having the horizontal side walls 64, and the hooks 76 and the horizontal side walls 64 of the annular edge plate 63 are in surface contact with each other via the hook back surfaces 76a and the protrusion peripheral regions 66. This creates a labyrinth structure at the boundary between the horizontal side walls 64 and the U-shaped frame 71, making it difficult for the molded resin 8 to enter the openings 58 even when the frame body 58a is separated into the horizontal side walls 64 and the U-shaped frame 71.

[0088] The above-described embodiments of the present invention are presented as examples, and the present invention is not limited to the above-described embodiments. The above-described embodiments 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 embodiments and their modifications are included in the scope of the present invention. [Explanation of symbols]

[0089] 100 reactor 10 Reactor body 1 core 3 Sensor section 4. Molding resin 41 Fastening hole 5 coils 51 Top side 52 Bottom surface 53 Lower curved surface 53a Lower edge area 54 Side 55 1st end face 56 Upper curved surface 57 Second end face 58 Aperture 58a frame 59 Conductive Wire 6 Upper cover 61 Upper plate 62 Side curved plate 63 Edge annular plate 63a outlet 64 Side wall 65 1st protrusion 65a Projection side 65b Projection end face 65c rear end 66 Area around protrusion 7 Lower cover 71 U-shaped frame 72 Vertical side 721 Curved section 722 Vertical section 73 Side part 74 Edge annular plate 74a outlet 76 Hook 76a Hook back 77 Arm section 77a Upper side of arm 78 Second protrusion 78a Projection side 8 Molding resin

Claims

1. A method for manufacturing a molded coil having a cylindrical coil with an outer shape in which four flat surfaces and four curved surfaces are alternately arranged, a first cover attachment step of placing a plate on one of the flat surfaces of the coil; a second cover attachment step of placing a frame on the flat surface opposite to the flat surface on which the plate is attached; a molding step of covering a part or all of the coil with a molding resin except for an inside of the frame of the frame body after the first cover attaching step and the second cover attaching step; Including, The frame body is defined by a combination of a horizontal wall and a U-shaped frame, The U-shaped frame includes a pair of vertical side portions extending along a cylindrical axis of the coil and a horizontal side portion extending between the pair of vertical side portions, and has a U-shape with no opposing side of the horizontal side portion, the pair of vertical side portions sandwich one of the flat surfaces and are in close contact with the two curved surfaces adjacent to the flat surface; The pair of vertical side portions have hooks that are hooked onto the horizontal side walls, In the molding step, The coil to which the plate body and the frame body are attached is placed in a mold having an upper mold and a lower mold, the frame body is placed on the lower mold, and the upper mold is placed on top of the plate body. The upper die presses the plate toward the lower die, thereby pressing the curved surface of the coil against the vertical side portion, the hooks restrict movement of the vertical side portions due to the pressure contact in a horizontal direction perpendicular to the vertical side portions, parallel to the flat surface sandwiched between the pair of vertical side portions, and toward the outside of the coil; A method for manufacturing a molded coil, characterized by:

2. In the molding step, the upper mold is brought into contact with the plate, so that a part or all of the plate is exposed from the molding resin.

2. The method for manufacturing a molded coil according to claim 1, wherein:

3. the pair of vertical side portions are spaced apart from the flat surface between the pair of vertical side portions; 3. The method for manufacturing a molded coil according to claim 1 or 2, wherein:

4. the hook is provided closer to the flat surface sandwiched between the pair of vertical side portions than to an area in the curved surface where the pair of vertical side portions are in close contact with each other; 4. The method for manufacturing a molded coil according to claim 1, wherein:

5. the hook is provided at a tip of one of the pair of vertical side portions extending from the horizontal side portion; 4. The method for manufacturing a molded coil according to claim 1, wherein:

6. The horizontal side wall further includes a first protrusion extending in a direction in which the vertical side portion extends and in an up-down direction perpendicular to the horizontal direction, The hook has a second protrusion extending in the vertical direction, the first protrusion and the second protrusion are aligned in the lateral direction and contact each other at their side surfaces, the first protrusion is located outside the coil relative to the second protrusion, in the molding step, the first protrusion and the second protrusion contact each other to restrict movement of the vertical side portion; 5. The method for manufacturing a molded coil according to claim 1, wherein:

7. The first protrusion is directly or indirectly connected to the plate body, the hook has an arm portion extending laterally and having the second protrusion rising from its tip, In the molding step, the arm portion is pressed downward by an end surface of the first protrusion portion.

7. The method for manufacturing a molded coil according to claim 6, wherein:

8. an edge annular plate extending from the plate body and covering one end surface of the coil; the first protrusion is provided on the edge annular plate, the hook is located outside the coil in the longitudinal direction relative to the edge annular plate, the hook and the edge annular plate are in surface contact with each other; 8. The method for manufacturing a molded coil according to claim 7, wherein:

9. A method for manufacturing a molded coil according to any one of claims 1 to 8; a core mounting step of mounting the molded coil on a core including a magnetic body; A method for manufacturing a reactor, comprising:

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