Manufacturing method of molded coil and manufacturing method of reactor

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. Representative reactors include boost reactors incorporated in on-board boost circuits such as drive systems for hybrid and electric vehicles, 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 machines connected to them, 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 point and the ground to limit earth-fault current that flows in the event of an earth-fault in the power system, and arc-suppression reactors to automatically extinguish arcs that occur in the event of a single-line earth fault in a three-phase power system.

[0004] As such reactors, molded coils, in which the outer circumference of the coil is covered with resin, are used in various places. In this type of reactor, in order to ensure heat dissipation, a part of the coil surface may be left exposed without being covered with molded resin. In order to expose the coil surface, a proposal has been made to fill the surrounding area with molded resin while pressing a die 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] JP 2015-130410 A [Patent Document 3] JP 2018-011019 A Summary of the Invention [Problem to be solved by the invention]

[0006] The coil is made into a cylindrical shape by winding a conductive wire in a spiral shape while shifting the winding position for each turn along the winding axis, and has an outer shape in which four flat surfaces and four curved surfaces are arranged alternately. For reasons of manufacturing precision, the surface of the coil has irregularities and is not necessarily smooth. Therefore, even if the coil is to be closely attached to the mold, a gap will occur between the mold and the surface of the coil. If this happens, resin may seep in through this gap and cause burrs to form on the surface that is to be exposed.

[0007] In order to improve heat dissipation, it is useful to expand the exposed area to the curved surface of the coil, not just the flat surface. However, the curved surface of the coil needs to maintain a constant curvature within one turn, and the same curvature must be maintained for all turns, so it is particularly prone to unevenness, and the unevenness can easily become large. Therefore, in the manufacturing method in which the coil is pressed against a mold, it is difficult to extend the exposure from the molded resin to the curved surface.

[0008] One way to prevent burrs from occurring is to press the die firmly against the coil surface. By pressing the die firmly against the coil surface, it is possible to eliminate any gaps between the die and the coil surface and to straighten out any twists in the coil surface using the die. However, pressing the die firmly against the coil surface can cause problems such as scratching 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 occurrence of burrs without damaging the coil, but the above-mentioned conventional technology cannot meet such a demand.

[0010] The present invention has been proposed to solve the problems of the conventional technology as described above, and an object of the present invention is to provide a method for manufacturing a molded coil that suppresses the occurrence of burrs of molding resin on the surface of a coil with a portion of the surface exposed, and a method for manufacturing a reactor including 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 within the frame 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 two of the curved surfaces adjacent to the flat surfaces, the pair of vertical side portions having hooks that are perpendicular to the vertical side portions and restrict movement of the vertical side portions in a horizontal direction parallel to the flat surfaces sandwiched by 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 a horizontal wall 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 sides than to a region in the curved surface where the pair of vertical sides are in close contact with each other.

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

[0016] The hook may further include a first protrusion extending in an up-down direction perpendicular to the vertical and horizontal directions, the hook having 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 being positioned outside the coil relative to the second protrusion.

[0017] The hook may further include a plate body that is arranged on another flat surface located opposite the flat surface sandwiched between the pair of vertical sides, the first protrusion portion being directly or indirectly connected to the plate body, the hook having an arm portion extending laterally from an end of 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 face 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 edge annular plate in the longitudinal direction, and the hook and the edge annular 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. Effect of the Invention

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

[0022] [Figure 1]FIG. 2 is a perspective view of the reactor, showing the reactor without the members covering each portion. [Diagram 2] FIG. 2 is a top perspective view showing the coated coil. [Diagram 3] 3A is a perspective view showing each covering member of the coil, in which FIG. 3A shows an upper cover, FIG. 3B shows a lower cover, and FIG. 3C shows a molded resin. [Figure 4] FIG. 4 is a bottom perspective view showing the molded coil. [Diagram 5] FIG. [Figure 6] FIG. [Figure 7] FIG. 4 is a transition diagram showing the assembly of the upper cover and the lower cover. [Figure 8] 4A and 4B show the state of the upper cover, the lower cover, and the coil within the mold, and FIG. 4A is a cross-sectional perspective view of the lower curved surface of the coil, and FIG. 4B is a cross-sectional view of the lower curved surface of the coil. [Figure 9] 4A and 4B show the state of the upper cover, the lower cover, and the coil within the mold, where FIG. 4A is a perspective view seen from the first end face side, and FIG. 4B is a plan view seen from the first end face side. [Figure 10] FIG. 4 is a bottom perspective view showing the state of the upper cover, the lower cover, and the coil within the mold. [Figure 11] FIG. 11 is a perspective view showing another configuration of the reactor. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Hereinafter, a reactor according to an embodiment of the present invention 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.

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

[0026] The core 1 includes a magnetic body 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 magnetic powder and resin and molding them.

[0027] The coil 5 is a wound body in which a conductive wire 59 such as a copper wire is wound into a cylindrical shape. The coil 5 is formed by winding the conductive wire 59 in a spiral shape while shifting the winding position for each turn along a winding axis. The conductive wire 59 is drawn out from the start 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 in which four curved surfaces and four flat surfaces parallel to the cylindrical axis are alternately connected. That is, the coil 5 has an upper surface 51 which is a flat surface parallel to the surface on which the annular shape of the core 1 appears, and a flat lower surface 52 on the opposite side to the upper surface 51. The coil 5 has a side surface 54 which is a flat surface 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 an annular first end surface 55 and a second end surface 57 which are 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 coil 5 refers to a surface that is flat in relative comparison with a curved surface, and also includes a surface that describes a large arc with a gentle curvature due to the swelling of conductive wire 59. The top and bottom refer to the upper and lower molds that house coils 5, 5 when covering coils 5, 5 by molding, and do not refer to the positional relationship or direction when reactor 100 is mounted on an actual device to be installed.

[0030] In the following description, the horizontal direction in the reactor body 10 refers to the Y-axis direction, which is parallel to the lower surface 52 of the coil 5 and perpendicular to the side surface 54 of the coil 5. The direction from the cylinder axis of the coil 5 to the side surface 54 is referred to as the outer side in the coil horizontal direction. The opposite side of the outer side in the coil horizontal direction is referred to as the inner side in the coil horizontal direction. The vertical direction refers to the X-axis direction, which is perpendicular to the horizontal direction, parallel to the lower surface 52, along the cylinder 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 coil vertical direction. The opposite side of the outer side in the coil vertical direction is referred to as the inner side in the coil horizontal direction. The vertical direction refers to the Z-axis direction, which is perpendicular to the upper surface 51 and the lower surface 52. The direction from the lower surface 52 toward the upper surface 51 is referred to as the upper side, and the direction from the upper surface 51 toward the lower 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 form a molded coil together with these covering members. 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 are fitted into the core 1.

[0033] Examples of resins having 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 a combination 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] 3(a), the upper cover 6 has an upper plate 61, a side curved plate 62, and an edge annular plate 63. The upper plate 61, the side curved plate 62, and the edge annular plate 63 are seamlessly connected into one piece 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 region of the side surface 54 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 lateral 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 Fig. 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 to each other by integral molding or the like. The U-shaped frame 71 has a rectangular 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. The 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 extending in the coil lateral direction, and extends upward perpendicular to the U-shaped frame 71 to cover the conductive wire 59 appearing 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 the resin into the mold and solidifying it. 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 edge annular plate 63 of the upper cover 6 facing outward in the longitudinal direction of the coil, and the surface of the edge annular plate 74 of the lower cover 7 facing 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 molded resin 8, and an opening 58 is formed on a portion 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 inside of the frame body 58a is the opening 58. The frame body 58a rises below the lower surface 52 around the entire circumference, and the lower edge is at the same height around the entire circumference. Therefore, the frame body 58a is seated on the mold without any gaps around the entire circumference. 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 mold resin 8 covers the coil 5 except for the inside of the frame body 58a, and the opening 58 is formed without the mold resin 8 flowing into the frame body 58a.

[0042] This frame body 58a is defined by combining 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 which 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 edge annular plate 63 is cut out toward the upper plate body 61, the ring of the edge annular plate 63 is interrupted, and an outlet 63a is formed for leading the conductive wire 59 of the coil 5 from the first end face 55. The lower part of the edge annular plate 63 forms a horizontal side wall 64 surrounding 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 out from the horizontal side wall 64. Each first protrusion 65 bulges outward on both sides in the horizontal direction of the coil. The first protrusion 65 has a rectangular parallelepiped shape. The first protrusion 65 is connected to a rear end 65c that is seamlessly connected to the first protrusion 65. The rear end 65c is formed continuously from the first protrusion 65, curves along the lower curved surface 53, and extends upward to crawl along the edge of the edge annular plate 63.

[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 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 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 face 65b fits within the horizontal wall 64. A protrusion surrounding region 66 adjacent to the protrusion side surface 65a and the protrusion end face 65b extends around the first protrusion 65. The horizontal 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 face 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 edge annular plate 74 is cut out, the ring of the edge annular plate 74 is interrupted, and an outlet 74a is formed for leading the conductive wire 59 of the coil 5 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] Vertical side portion 72 extends in the coil vertical direction, in other words, along the cylindrical axis direction of coil 5. Vertical side portion 72 has curved portion 721 and vertical portion 722. Curved portion 721 comes into close contact with coil 5 at its curved inner circumferential surface. Vertical portion 722 is a part of the wall of frame body 58a that rises around 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 region 53a. The lower end of the inner circumferential surface of the curved portion 721 is located at the upper limit of the lower edge region 53a that fits into 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 on 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 equal to the total width of the lower surface 52 of the coil 5 plus the lower edge regions 53a of the lower curved surfaces 53 exposed from the opening 58. That is, the vertical portion 722 extends away from the lower surface 52.

[0051] The vertical portion 722 extends downward beyond 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 along 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. In addition, the horizontal side portion 73 extends downward beyond the lower surface 52 so that the lower surface 52 can be accommodated 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 a part of the wall of the frame body 58a rising 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. The hooks 76 are hooked onto the first protrusions 65 of the upper cover 6, thereby restricting the vertical side portions 72 from moving apart from each other, 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 below the region of lower curved surface 53 where curved portion 721 is in close contact, and abuts on the lower surface 52 side. That is, hooks 76 are provided at positions close to opening 58 into which molded resin 8 must not enter.

[0056] The hook 76 has an L-shape that is laid down on its side and includes an arm portion 77 and a second protrusion portion 78 that are seamlessly connected together. 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 portion 65 formed on the upper cover 6 are formed at the same height, and the arm upper side surface 77a and the protrusion end surface 65b of the first protrusion portion 65 are formed at the same height and in the same range, when the upper cover 6 and the lower cover 7 are positioned relative to the coil 5. 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 portion 65 are formed at the same height and in the same range, such that the arm upper side surface 77a extends within the range in which the arm upper side surface 77a extends.

[0058] Moreover, 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 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 set so that, when the upper cover 6 and the lower cover 7 are positioned relative to the coil 5, the positions in the lateral direction of the coil are the same. Furthermore, the formation positions and ranges 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 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 protrusion side surface 65a of the upper cover 6 fits within the range in which the protrusion side surface 78a of the hook 76 extends.

[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 area 66 of the upper cover 6 in the coil vertical direction, and the hook back surface 76a of the hook 76 and the protrusion surrounding area 66 of the upper cover 6 are in the same position in the coil vertical direction, so that the hook back surface 76a is the surface of the hook 76 that faces inward in the coil vertical direction.

[0060] The assembly of the upper cover 6 and the lower cover 7 to the coil 5 will now be described. As shown in Fig. 7(a) , when the lower cover 7 is fitted to the coil 5, the hook 76 is located outside the first end face 55 in the longitudinal direction of the coil, separated by the thickness of the protrusion surrounding region 66 of the horizontal side wall 64 of the upper cover 6. The hook 76 is also located 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 wire 59 drawn out from the first end face 55 passes through the ring of the edge annular plate 63.

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

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

[0063] 8(a) and 8(b), in 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 of 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 unevenness or twists in the lower curved surface 53, and the curved portion 721 and the lower curved surface 53 come into close contact with each other 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 directed outward in the lateral 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 lateral direction of the coil. In other words, the vertical side portions 72 try to shift in position so that the ends of the pair of vertical side portions 72 on the first end surface 55 side move apart. If the vertical side portions 72 open outward in the lateral 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 by the first protrusion 65 of the upper cover 6, which is held down by a mold and is in a fixed position. Therefore, a force component P4 directed toward the inside in the coil horizontal direction, which opposes a force component P3 directed toward the outside 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 in the up-down direction. Therefore, the risk of the vertical side portion 72 being opened while twisting at the opening 58 is also reduced.

[0068] Furthermore, the protrusion end surface 65b of the first protrusion 65 and the arm upper side surface 77a of the hook 76 are in contact with each other in the vertical direction. Therefore, the arm portion 77 of the hook 76 is sandwiched between the first protrusion 65 and the lower die by the force with which the upper die presses the upper cover 6. Therefore, the engagement between the hook 76 and the first protrusion 65 is difficult to release.

[0069] Here, if the vertical side portion 72 extends until it contacts the underside 52 of the coil 5, the vertical side portion 72 is 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 slip 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 expand the opening 58 of the coil 5 in the coil lateral direction, the vertical side portion 72 that defines 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, is separated 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 wall 64 of the upper cover 6 was provided on the lower cover 7 and seamlessly connected to the U-shaped frame 71, the tension of the horizontal side wall 64 would prevent the vertical side portion 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 reduce the vertical length of the coil 5. If the horizontal side wall 64 is positioned at the first end face 55 before the resin is injected as part of the U-shaped frame 71, this compression phenomenon of the coil 5 causes a gap to be formed between the first end face 55 and the horizontal side wall 64. This causes the resin to leak into the frame body 58a, resulting in the generation of 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 vertical 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. Following the compression of the coil 5, the edge annular plate 63 of the upper cover 6 also moves inward in the coil vertical 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. Thus, the frame body 58a is defined, surrounding the opening 58 on all four sides without any gaps.

[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 can be to support the vertical side portion 72 of the lower cover 7 from the outside with a mold, instead of providing the hook 76. However, in this case, the vertical side portion 72 cannot be supported so as not to open 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 may result in a decrease in the yield of the 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 that even if opening 58 is expanded to lower curved surface 53 or to the entire longitudinal direction of the coil on lower surface 52, the occurrence of burrs in opening 58 can be suppressed. Also, even if there are some individual differences in lower covers 7, it is possible to prevent the lower covers 7 from not being able to fit into the mold, and the yield of lower covers 7 can be suppressed.

[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 until it reaches 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 surrounding region 66 are aligned in the coil vertical direction and are pressed against each other by the injection pressure of the molded resin 8. Therefore, it is difficult for the resin of the molded resin 8 to pass through the hook back surface 76a and the protrusion surrounding region 66 to reach the opening 58.

[0078] As a result, even if the area included in opening 58 is expanded to include the lower edge region 53a of lower curved surface 53 in addition to the entire lower surface 52, opening 58 is formed in which the generation of burrs is suppressed, and this coil 5 has excellent heat dissipation properties.

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

[0080] As described above, the frame body 58a is disposed on the surface of the coil 5, and the coil 5 is covered with the molded resin 8 except for the inside of the frame body 58a, to produce a molded coil. 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 the lower surface 52, which is a flat surface, and are in close contact with the two lower curved surfaces 53 adjacent to the lower surface 52. The pair of vertical side portions 72 has hooks 76 that restrict the movement of the vertical side portions 72. The hooks 76 are perpendicular to the vertical side portions 72 and restrict the positional displacement of the vertical side portions 72 toward the outside of the coil horizontal direction, that is, toward the horizontal direction parallel to the lower surface 52 and toward the outside of the coil.

[0081] As a result, even if the vertical side portions 72 are about to shift in position due to the force exerted by the lower curved surface 53 toward the outside in the lateral direction of the coil, the hooks 76 catch and prevent the position from shifting. Therefore, the vertical side portions 72 do not open so as to move apart from each other, and it is possible to prevent the molding resin 8 from flowing into the frame of the frame body 58a and causing burrs. Thus, even if the range of the opening 58 is expanded to include the lower edge region 53a of the lower curved surface 53, it is possible to prevent burrs from occurring and the 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. The frame body 58a is further effective when it is defined by combining the horizontal side wall 64 and the 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 through even if it is sandwiched between the underside 52 and the lower part of the mold, so the hooks 76 may be provided.

[0083] Furthermore, the hook 76 is provided on the lower surface 52 side of the region in the lower curved surface 53 where the pair of vertical side portions 72 are in close contact with each other. This makes it possible to prevent the vertical side portions 72 from twisting open near the opening 58. If the vertical side portions 72 are highly rigid and the opening of the vertical side portions 72 near the opening 58 can be prevented regardless of where the hook 76 is provided, the hook 76 may be provided on either side.

[0084] Moreover, the hook 76 further includes the first protrusion 65 and has a second protrusion 78 extending in the up-down direction, the first protrusion 65 and the second protrusion 78 are arranged in the horizontal direction and contact each other on their side surfaces, and the first protrusion 65 is located outside the coil relative to the second protrusion 78. This allows the hook 76 to prevent the vertical side portion 72 from opening. However, the shape of the hook 76 is not limited to this as long as it can prevent the vertical side portion 72 from opening.

[0085] It 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 extending laterally and having an arm portion 77 from whose tip a second protrusion 78 rises, and the first protrusion 65 is in contact with the arm portion 77 at the protrusion end surface 65b.

[0086] The upper plate 61 receives a force from the upper die of the metal mold. The first protrusion 65 directly or indirectly connected to the upper plate 61 also presses the arm 77 downward. This reduces the possibility that the hook 76 and the first protrusion 65 will be disengaged, and the risk of the vertical side 72 opening can be reduced. In this manner, the edge annular plate 63 extends from the upper plate 61, and the first protrusion 65 is provided on the 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 77.

[0087] In addition, the hook 76 is located outside the edge annular plate 63 having the horizontal side wall 64 in the coil vertical direction, and the hook 76 and the horizontal side wall 64 of the edge annular plate 63 are in surface contact with each other through the hook back surface 76a and the protrusion peripheral region 66. This forms a labyrinth structure at the boundary between the horizontal side wall 64 and the U-shaped frame 71, making it difficult for the molded resin 8 to enter the opening 58 even when the frame body 58a is separated into the horizontal side wall 64 and the U-shaped frame 71.

[0088] The above-mentioned embodiment of the present invention is presented as an example, and the present invention 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]

[0089] 100 Reactor 10 Reactor body 1 core 3 Sensor section 4. Mold Resin 41 Fastening hole 5 Coil 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 having an outer shape in which four flat surfaces and four curved surfaces are alternately arranged, comprising: 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 the whole 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 has a pair of vertical side portions extending along a cylindrical axis of the coil, 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, 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 landed on the lower mold, and the upper mold is placed over the plate body, The upper die presses the plate toward the lower die to press the curved surface and the vertical side portion of the coil together, the hook regulates the movement of the vertical side portion due to the pressure contact in a lateral direction perpendicular to the vertical side portion, 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, comprising the steps of:

2. In the molding step, the upper mold is brought into contact with the plate body, so that a part or the whole of the plate body is exposed from the molding resin; 2. The method for producing a molded coil according to claim 1, further comprising the steps of:

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 producing a molded coil according to claim 1 or 2, characterized in that

4. The frame body is defined by combining a horizontal wall and a U-shaped frame, The U-shaped frame includes the pair of vertical side portions and one 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; 4. The method for manufacturing a molded coil according to claim 1, further comprising the steps of:

5. the hook is provided on the flat surface side sandwiched between the pair of vertical side portions rather than on a region in the curved surface where the pair of vertical side portions are in close contact with each other; 5. The method for manufacturing a molded coil according to claim 1, further comprising the steps of:

6. the hook is provided at a tip of one of the pair of vertical sides extending from the horizontal side; 5. The method for producing a molded coil according to claim 4, further comprising the steps of:

7. The molded coil further includes a first protrusion extending in an up-down direction perpendicular to the direction in which the vertical side portion extends and the horizontal direction, The hook has a second protrusion extending in the vertical direction, the first protrusion and the second protrusion are arranged side by side in the lateral direction and in contact with 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 are brought into contact with each other to restrict movement of the vertical side portion; 6. The method for manufacturing a molded coil according to claim 1, further comprising the steps of:

8. 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 a tip end thereof, In the molding step, an end surface of the first protrusion is pressed downward by the arm portion; 8. The method for producing a molded coil according to claim 7, further comprising the steps of:

9. 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 relative to the edge annular plate along the longitudinal direction; the hook and the edge annular plate are in surface contact with each other; 9. The method for producing a molded coil according to claim 8, further comprising the steps of:

10. A method for manufacturing a molded coil according to any one of claims 1 to 9; 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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