JP7633824B2 - Molded coils and reactors - Google Patents

Description

The present invention relates to a molded coil made by molding a coil with resin, and a reactor having this molded coil.

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.

Reactors are used in a wide variety of applications. Representative reactors include boost reactors that are incorporated into on-board boost circuits such as drive systems for hybrid and electric vehicles, series reactors that are connected in series to motor circuits to limit current during short circuits, parallel reactors that stabilize current sharing between parallel circuits, current-limiting reactors that limit current during short circuits to protect machines connected to them, starting reactors that are connected in series to motor circuits to limit starting current, shunt reactors that are connected in parallel to transmission lines to compensate for leading reactive power and suppress abnormal voltages, neutral reactors that are connected between the neutral point and the ground to limit the earth-fault current that flows in the event of an earth-fault in the power system, and arc-suppression reactors that automatically extinguish the arc that occurs when a single-line earth fault occurs in a three-phase power system.

Some reactors use molded coils, in which the outer circumference of the coil is covered with resin. In this type of reactor, part of the coil surface is left exposed, rather than covered with molded resin, to ensure heat dissipation. In order to expose the coil surface, a proposal has been made to press a mold against the coil surface and fill the area around it with molded resin (see Patent Documents 1 to 3).

Patent No. 5869518 JP 2015-130410 A JP 2018-011019 A

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. As a result, even if an attempt is made to closely contact the coil with a 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.

To prevent burrs from being generated, it is possible to press the die firmly against the surface of the coil. By pressing the die firmly against the surface of the coil, it is possible to eliminate the gap between the die and the coil surface, and to correct any twists in the coil surface using the die. However, pressing the die strongly against the surface of the coil may damage the coil or damage the coating on the coil's conductive wire, resulting in a loss of insulation. Therefore, it is possible to place a cover on the coil in advance, and press the coil with the die through the cover to eliminate any unevenness or twists in the coil surface. When using a die with an upper and lower die, a cover may be placed on the upper surface of the coil facing the upper die, and another cover may be placed on the lower surface of the coil facing the lower die.

When the underside of the coil is exposed, the cover placed on the underside of the coil is a rectangular frame. Here, the coil inside the mold is compressed by the injection pressure of the resin so as to reduce the length of the coil in the axial direction. In order to prevent a gap from occurring between the edge of the coil's underside and the frame even when the coil is compressed, the frame placed on the underside of the coil must have thick frame sides and cover the edge area from the edge of the coil's underside toward the inside in advance. The edge area is the range equivalent to the amount of compression of the coil plus a buffer.

By covering the edge region of the coil's underside with a frame, the end of the coil's underside maintains an overlap with the frame side, even if the coil is compressed. This prevents gaps from forming between the end of the coil's underside and the frame, reducing the risk of resin leaking from the gap and burrs being generated. However, because a buffer is required for the range of the edge region that is covered in advance by the frame side of the frame body, the overlap between the coil's underside and the frame body remains even after the resin is injected and molded. The underside of the coil cannot be exposed over the entire vertical width range in the axial direction of the cylinder.

In this way, in reactors where part of the coil surface is covered with molded resin and part of the surface is exposed from the molded resin, there is a need to prevent the coil from being damaged and to prevent the generation of burrs, but the above-mentioned conventional technology cannot meet this need.

The present invention has been proposed to solve the problems of the conventional technology as described above, and the object of the present invention is to provide a molded coil that expands the exposed area of the coil while suppressing the generation of burrs in the molded resin, and a reactor equipped with this molded coil.

The molded coil of the present invention has a cylindrical coil whose outer shape is defined by a pair of coil end faces and a side surface on which four flat surfaces and four curved surfaces are alternately arranged and which are perpendicular to the pair of coil end faces, a horizontal wall and a U-shaped frame, and is defined by combining the horizontal wall and the U-shaped frame into a rectangular shape, and has a frame body that is placed on the coil so that a first flat surface of the four flat surfaces is contained in part or in whole within the frame, a molded resin that covers part or in whole of the coil except for the inside of the frame body, a flat surface that covers one of the pair of coil end faces, and the horizontal wall, and in the absence of the molded resin, and an edge plate movable along the axial direction of the coil, the U-shaped frame having a pair of vertical side portions extending along the axial direction of the coil and in close contact with the coil, and a horizontal side portion extending between the pair of vertical side portions, the horizontal side wall being in close contact with the coil end surface covered by the flat surface of the edge plate, the horizontal side portion of the U-shaped frame being in close contact with the coil end surface opposite the edge plate, and the coil has the first flat surface exposed from the molded resin over the entire vertical width range from the coil end surface on one side to which the horizontal side wall is in close contact to the coil end surface on the other side to which the horizontal side portion is in close contact.

The pair of vertical side portions may sandwich the first flat surface and be in close contact with the two curved surfaces adjacent to the first flat surface, and the coil may be configured such that at least the first flat surface is exposed from the molded resin over the entire width range from one of the curved surfaces to which the pair of vertical side portions are in close contact to the other curved surface.

The vertical side portion has a contact surface that is in close contact with the coil, an end surface on the flat surface side that is adjacent to the contact surface, extends along the cylindrical axis of the coil, and expands in a direction away from the contact surface and is perpendicular to the first flat surface, and an outer surface that is adjacent to the end surface and is the opposite side to the contact surface, and the angle formed by the contact surface and the end surface may be approximately a right angle, and the angle formed by the end surface and the outer surface may also be approximately a right angle.

The contact surface may be configured to contact not only the curved surface adjacent to the first flat surface , but also the flat surface perpendicular to the first flat surface.

The horizontal side wall may extend equal to the distance between the opposing faces of the pair of vertical side portions, and the frame may be defined by fitting the horizontal side wall between the pair of vertical side portions.

The frame may include a plate body covering the flat surface located opposite the first flat surface, the plate body having an eave portion extending beyond the position of the end surface covered by the edge plate, and the eave portion of the frame body may be in contact with the side surface of the edge plate.

The pair of vertical side portions of the U-shaped frame and the horizontal side wall of the edge plate may have projections and recesses that restrict movement of the horizontal side wall toward the flat surface located opposite the first flat surface, and the projections and recesses may be engaged with each other.

The pair of vertical side portions may have a recessed portion among the projections and recesses and a groove portion extending from the recessed portion along the cylindrical axis of the coil, and the horizontal side wall may have a protruding portion among the projections and recesses, and the protruding portion may be fitted into the recessed portion and slide within the groove portion as the horizontal side wall moves.

A reactor having this molded coil and a core including a magnetic body to which a molded core is attached is also an aspect of the present invention.

According to the present invention, even if the exposed area of the coil is expanded, the occurrence of burrs is suppressed and heat dissipation is excellent.

FIG. 2 is a perspective view of the reactor, showing the reactor without the members covering each portion. FIG. 13 is a bottom perspective view showing the coated coil. 4A is a perspective view showing each covering member of the coil, in which FIG. 4A shows an upper cover, FIG. 4B shows an edge plate, FIG. 4C shows a lower cover, and FIG. 4D shows a molded resin. FIG. 4 is a bottom perspective view of the coil and the upper cover. 1A and 1B are perspective views of a coil and an edge plate, in which FIG. 1A is a perspective view seen from below on the front side, and FIG. FIG. 4 is a bottom perspective view of the coil and the lower cover. FIG. 4 is an enlarged partial cross-sectional view of the coil and vertical side portion. FIG. 2 is a transition diagram showing the formation of a coil coating resin. FIG. 13 is a front view showing the coil in the mold as viewed from the edge plate side. FIG. 4 is an enlarged partial cross-sectional view showing the forces acting on the coil and the vertical side portion within the die. FIG. 13 is a transition diagram showing compression of the coil within the die. 1A and 1B are bottom views showing the compression of a coil within a mold, where (a) is before compression, (b) is after compression of the molded coil of this embodiment, and (c) is after compression when the horizontal side wall and the U-shaped wall are connected.

The reactor according to the embodiment of the present invention will be described below with reference to the drawings. In each drawing, thickness, dimensions, positional relationships, ratios, shapes, etc. may be emphasized for ease of understanding, but the present invention is not limited to such emphasis.

Figure 1 is a perspective view showing the main configuration of the reactor of this embodiment, and for convenience of explanation, the materials covering each part are omitted. The reactor 100 has two coils 5, 5 and one annular core 1. The two coils 5, 5 are attached to the core 1. When current is passed through the coils 5, 5, they generate magnetic flux according to the number of turns. The core 1 becomes a closed magnetic circuit that passes the magnetic flux generated by the coils 5, 5 with a magnetic permeability higher than that of a vacuum. In other words, this reactor 100 is an electromagnetic component that converts electrical energy into magnetic energy and stores and releases it.

The core 1 includes a magnetic material such as a dust core, a ferrite core, a metal composite core, or a laminated steel plate. A dust core is a compact made 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. A metal composite core is a core made by kneading magnetic powder and resin and molding them.

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 the 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 the bus bar, so that the coils 5, 5 are electrically connected in parallel or in series.

The coil 5 is cylindrically defined by a first end face 55, a second end face 57, and a side face connecting the first end face 55 and the second end face 57. The first end face 55 and the second end face 57 are located at the start and end of the winding of the conductive wire 59, and are perpendicular to the cylindrical axis. The first end face 55 and the second end face 57 have a ring shape that matches the winding pattern of the conductive wire 59.

The side surface of the coil 5 is made up of four curved surfaces and four flat surfaces that are perpendicular to the first end surface 55 and the second end surface 57 and parallel to the cylindrical axis, and are alternately connected together. That is, the coil 5 has a flat upper surface 51 that is 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 two lateral surfaces 54 that are flat surfaces 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 lateral surface 54, and an upper curved surface 56 between the upper surface 51 and the lateral surface 54.

The flat surface of the coil 5 refers to a surface that is flat in comparison with a curved surface, and 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.

Hereinafter, 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 horizontal surface 54 of the coil 5. The direction from the cylinder axis of the coil 5 to the horizontal surface 54 is referred to as the outside in the horizontal direction of the coil. The opposite of the outside of the horizontal direction of the coil is referred to as the inside of the horizontal direction of the coil. The vertical direction refers to the X-axis direction, which is perpendicular to the horizontal direction, parallel to the bottom surface 52, along the cylinder axis, and parallel to the horizontal surface 54. The direction from the center position equidistant to 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 outside of the vertical direction of the coil. The opposite of the outside of the vertical direction of the coil is referred to as the inside of the vertical direction of the coil. The up-down 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.

Figure 2 is a bottom perspective view showing the coated coils 5, 5. As shown in Figure 2, each of the two coils 5, 5 is a molded coil 2. The molded coil 2 is formed by covering the coil 5 with coil coating resin 3. The coils 5, 5 are fitted into the core 1 while being electrically insulated from the core 1 by being coated with the coil coating resin 3. Furthermore, by being coated with the coil coating resin 3, the vibration of the coils 5, 5 is suppressed.

The coil coating resin 3 is preferably a resin with insulating properties and heat resistance, such as PPS (Polyphenyl Sulfide), epoxy resin, unsaturated polyester resin, urethane resin, BMC (Bulk Molding Compound), PPS (Polyphenyl Sulfide), PBT (Polybutylene Terephthalate), or a combination of these. A thermally conductive filler may be mixed into the material of the coil coating resin 3.

However, an opening 58 is formed in the coil coating resin 3 to improve the heat dissipation of the coil 5. The opening 58 exposes the entire lower surface 52 of the coil 5 in the coil horizontal direction and the lower edge region 53a of the lower curved surface 53 adjacent to the lower surface 52. The opening 58 also exposes the entire lower surface 52 of the coil 5 in the coil vertical direction from the boundary with the first end surface 55 to the boundary with the second end surface 57.

The opening 58 is defined by a frame body 58a that the coil coating resin 3 has. The inside of the frame body 58a forms the opening 58. The frame body 58a rises downward from the lower surface 52 along its entire circumference. The coil coating resin 3 is ultimately completed by resin injection molding, but the frame body 58a prevents resin from flowing into the frame, forming the opening 58.

Figure 3 is a perspective view showing each component of the coil coating resin 3 having such a frame body 58a. As shown in Figures 2 and 3(a) to (d), the coil coating resin 3 is composed of an upper cover 6 shown in Figures 2 and 3(a), an edge plate 8 shown in Figures 2 and 3(b), a lower cover 7 shown in Figures 2 and 3(c), and a molded resin 9 shown in Figures 2 and 3(d).

As shown in FIG. 3(a), the upper cover 6 has an upper plate 61 and a side curved plate 62. The upper plate 61 and the side curved plate 62 are seamlessly connected as a single 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 lateral surface 54 adjacent to the upper curved surface 56.

As shown in FIG. 3B, the edge plate 8 has a plane 83 that covers the conductive wire 59 that appears on the first end surface 55 of the coil 5. A horizontal wall 81 that extends in the same plane as the plane 83 is formed at the lower end of the edge plate 8. The plane 83 and the horizontal wall 81 are seamlessly connected to each other by integral molding or the like. The horizontal wall 81 extends across the entire area of the lower surface 52 of the coil 5 in the coil lateral direction and 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.

As shown in FIG. 3(c), 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 the 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.

On the other hand, in the upward direction, the U-shaped frame 71 extends to cover the lower curved surface 53 other than the lower edge region 53a, and the lower edge region 53a of the horizontal surface 54 adjacent to the lower curved surface 53. The edge annular plate 74 extends upward from the side of the U-shaped frame 71 that extends in the coil horizontal direction, extends upward perpendicular to the U-shaped frame 71, and covers the second end surface 57 of the coil 5.

The molded resin 9 is formed by placing the coil 5 with the upper cover 6, lower cover 7, and edge plate 8 in a mold, and injecting resin into the mold and allowing it to solidify. In the mold, the upper cover 6 and lower cover 7 come into contact with the mold, except for the outer surface of the edge plate 8 that faces outward in the longitudinal direction of the coil, and the surface of the edge annular plate 74 of the lower cover 7 that faces outward in the longitudinal direction of the coil.

Therefore, as shown in FIG. 3(d), the molded resin 9 covers the remaining portion of the lateral 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 9 covers the first end surface 55 from above the edge plate 8, and covers the second end surface 57 from above the edge annular plate 74 of the lower cover 7.

The frame body 58a surrounding the opening 58 is defined by combining the U-shaped frame 71 of the lower cover 7 and the side wall 81 of the edge plate 8. The side wall 81 fits into the U-shaped frame 71, and the side wall 81 and the U-shaped frame 71 define a rectangular frame body 58a having sides on all four sides. The upper cover 6, edge plate 8, and lower cover 7 are described in more detail below.

Figure 4 is an enlarged perspective view of the coil 5 and upper cover 6. As shown in Figure 4, the upper cover 6 has an overhang portion 63. This overhang portion 63 protrudes outward from the coil 5 by extending the ends of the upper plate body 61 and the side curved plate 62 beyond the first end face 55 of the coil 5 without changing the extending direction. Before resin injection molding, the overhang portion 63 protrudes by a length equivalent to the thickness of the flat surface 83 of the edge plate 8. However, since the coil 5 is compressed during resin injection molding, after resin injection molding, the overhang portion 63 protrudes by a length equivalent to the amount of compression of the coil 5.

The eaves portion 63 is folded so that its end is perpendicular to the cylindrical axis of the coil 5, and overlaps with a part of the edge of the first end face 55 in the coil vertical direction. In addition, the upper plate 61 has a notch 64 formed on both sides of the first end face 55 and the second end face 57, which cuts out the central edge of the upper plate 61, and the eaves portion 63 is divided in the coil horizontal direction by the notch 64.

Figure 5 is an enlarged perspective view of the coil 5 and edge plate 8, (a) being a perspective view seen from below the front, and (b) being a perspective view seen from the side of the back. The plane 83 of the edge plate 8 has a ring shape following the winding manner of the conductive wire 59 of the coil 5, and the cylindrical axis region is open. The horizontal side wall 81 extends without changing direction so as to extend the plane 83, and extends downward beyond the lower surface 52 of the coil 5. In other words, the horizontal side wall 81 extends from the upper limit or above the upper limit of one of the lower edge regions 53a that fits into the opening 58 to below the lower surface 52 that fits into the opening 58.

The length of the horizontal side wall 81 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 bottom edge of the horizontal side wall 81 extends linearly in the coil horizontal direction at a constant height. This horizontal side wall 81 has protrusions 82 formed on both sides in the coil horizontal direction. The protrusions 82 protrude from the horizontal side wall 81 in the coil horizontal direction.

Figure 6 is an enlarged perspective view of the coil 5 and the lower cover 7. As shown in Figure 6, the U-shaped frame 71 of the lower cover 7 has a U-shape with a pair of vertical side portions 72 and one horizontal side portion 73. The pair of vertical side portions 72 are arranged in parallel, and the one horizontal side portion 73 connects the aligned ends of the pair of vertical side portions 72.

The vertical side portion 72 has a vertical portion 722. This vertical portion 722 is part of the wall of the frame body 58a that rises around the opening 58. In the up-down direction, the vertical portion 722 starts in close contact with the upper limit position of the lower edge region 53a exposed from the opening 58, rises perpendicular to the plane on which the lower surface 52 of the coil 5 extends, and extends below the lower surface 52. In other words, 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 both lower curved surfaces 53 exposed from the opening 58.

The vertical portion 722 extends in the coil longitudinal direction, in other words, along the axial direction of the coil 5, and the lowermost edge of the vertical portion 722 extends linearly at a constant height in the coil longitudinal direction. The end of the vertical portion 722 on the first end face 55 side protrudes by the same amount as or more than the thickness of the horizontal wall 81 of the edge plate 8 beyond the coil 5 before it is compressed by the injection pressure of the molded resin 9.

The horizontal side portion 73 extends perpendicular to the coil horizontal direction, in other words, the cylindrical axis direction of the coil 5, and parallel to the lower surface 52 of the coil 5, and extends completely across the second end surface 57 of the coil 5 along 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 into the opening 58 to the outer end of the other lower edge region 53a. The horizontal side portion 73 also extends below the lower surface 52 so that the lower surface 52 can be contained within the opening 58. The lowest edge of the horizontal side portion 73 extends linearly at the same height as the vertical portion 722.

In such a U-shaped frame 71, the horizontal wall 81 of the edge plate 8 fits between the vertical portions 722 of the vertical side portions 72, and the horizontal wall 81 and the horizontal portion 73 of the edge plate 8 become opposing sides, so that the vertical portion 722 of the vertical side portion 72, the horizontal wall 81, and the horizontal portion 73 form a rectangular frame body 58a.

Figure 7 is an enlarged partial cross-sectional view of the coil 5 and the vertical side portion 72. As shown in Figures 6 and 7, the vertical side portion 72 has a contact portion 721 in addition to the vertical portion 722. The contact portion 721 extends seamlessly from the upper end of the vertical portion 722, and the vertical side portion 72 is in contact with the lower curved surface 53 at the contact portion 721. The contact portion 721 is defined by a contact surface 721a, an upper end surface 721b, and an outer surface 721c, except for the connection area with the vertical portion 722 and the connection area with the horizontal side portion 73. When going around the vertical side portion 72, there is the contact surface 721a, the contact surface 721a is followed by the upper end surface 721b, the upper end surface 721b is followed by the outer surface 721c, the outer surface 721c is followed by the vertical portion 722, and the vertical portion 722 is followed by the contact surface 721a.

The contact surface 721a is the inner peripheral surface of the contact portion 721. The contact surface 721a is curved to coincide with the arc range from the upper limit of the lower edge region 53a of the coil 5 to the upper limit of the lower curved surface 53, and further extends linearly along the lateral surface 54 of the coil 5. This contact surface 721a is in contact with the upper side from the upper limit of the lower edge region 53a of the lower curved surface 53 and the lower region of the lateral surface 54.

The upper end surface 721b is an upper end surface adjacent to the contact surface 721a. The upper end surface 721b is adjacent to the contact surface 721a and extends in a direction away from the side surface 54. The upper end surface 721b extends in a direction that is approximately perpendicular to the contact surface 721a and the side surface 54. The outer surface 721c is adjacent to the upper end surface 721b and forms the outer peripheral surface of the contact portion 721. The outer surface 721c is the opposite surface to the contact surface 721a. The outer surface 721c extends at an angle approximately perpendicular to the upper end surface 721b and is parallel to the side surface 54 and the contact surface 721a.

These roughly right angles are angles at which the external force acting on the boundary between the upper end surface 721b and the outer surface 721c is efficiently transmitted to the boundary between the contact surface 721a and the upper end surface 721b. In other words, roughly right angles refer to a predetermined angle range including 90 degrees, so long as the lower curved surface 53 of the coil 5 is corrected and the upper end of the vertical side portion 72 is not bent outward in the lateral direction of the coil by the injection pressure of the molded resin 9.

Returning to FIG. 6, the vertical side portion 72 has a recess 75 at the end of the vertical portion 722 on the first end surface 55 side. The recess 75 is formed on the side surface of the vertical portion 722 on the inner side in the coil horizontal direction, i.e., the side surface facing the inside of the U-shaped frame 71, and is deep in the coil horizontal direction outer direction. The recess 75 has walls at the top, bottom, and outer side in the coil horizontal direction. The recess 75 and the convex portion 82 formed on the horizontal side wall 81 of the edge plate 8 are the same in shape. Furthermore, a groove portion 76 is formed in the vertical side portion 72. The groove portion 76 continues from the recess 75 and extends along the coil vertical direction on the inner side of the vertical portion 722 in the coil horizontal direction. The cross section of the groove portion 76 at each position coincides with the recess 75.

Therefore, the recess 75 and the protrusion 82 can fit together. In addition, the protrusion 82 fitted into the recess 75 restricts the vertical position of the coil 5 because the recess 75 is deep in the coil horizontal direction, has walls above and below, and the protrusion 82 protrudes in the coil horizontal direction. On the other hand, the protrusion 82 fitted into the recess 75 can slide within the groove 76 along the coil vertical direction.

The method of forming the coil coating resin 3 using the upper cover 6, lower cover 7, edge plate 8, and molded resin 9 is as follows. Figure 8 is a transition diagram showing the formation of the coil coating resin 3. As shown in Figure 8 (a), with the lower cover 7 placed in the lower die, the coil 5 is accommodated in the lower die and the coil 5 is placed on the lower cover 7. The coil 5 is placed so as to be sandwiched between the contact parts 721 of the lower cover 7, and the lateral surface 54 and the lower curved surface 53 of the coil 5 are aligned with the contact surface 721a of the contact part 721. In addition, the second end surface 57 of the coil 5 is aligned with the edge annular plate 74 of the lower cover 7.

The lower cover 7 is attached to the lower die at the vertical portion 722. The coil 5 placed on the lower cover 7, which has the vertical portion 722 extending downward from the lower surface 52, is in a state where the lower surface 52 is floating above the lower die. In addition, the U-shaped frame 71 contains within its frame the entire lower surface 52 and the lower edge region 53a of the lower curved surface 53 in the coil horizontal direction.

As shown in FIG. 8(b), after placing the coil 5 on the lower cover 7, the edge plate 8 is installed so that the flat surface 83 contacts the first end surface 55. At this time, the convex portions 82 protruding outward on both sides of the horizontal side wall 81 in the coil horizontal direction are fitted into the concave portions 75 formed in the vertical side portion 72 of the lower cover 7 and deepening toward both sides of the coil horizontal direction. The horizontal side wall 81 is fitted inside the U-shaped frame 71 so that the end faces on both sides of the coil horizontal direction contact the side faces on both sides of the vertical side portion 72 in the coil horizontal direction.

As a result, the horizontal side wall 81 is located on the opposing side of the horizontal side portion 73 of the U-shaped frame 71, and the horizontal side wall 81 and the U-shaped frame 71 form a rectangular frame body 58a. This frame body 58a contains the entire lower surface 52 and the lower edge region 53a of the lower curved surface 53 in the coil horizontal direction. In addition, since the horizontal side wall 81 contacts the first end face 55 and the horizontal side portion 73 contacts the second end face 57, the frame body 58a contains the entire lower surface 52 from the boundary with the first end face 55 to the boundary with the second end face 57 in the coil vertical direction. And, since the downward extension amount is set so that the horizontal side wall 81 and the lowest end of the U-shaped frame 71 are at the same height, the frame body 58a lands on the lower mold without any gaps around the entire circumference.

As shown in FIG. 8(c), the edge plate 8 is placed along the first end surface 55 of the coil 5, and then the upper cover 6 is placed on the coil 5. The upper plate 61 of the upper cover 6 is aligned with the top surface 51 of the coil 5, and the side curved plate 62 is aligned with the upper curved surface 56 of the coil 5. At this time, the eaves portion 63 covers the upper side surface 83a of the edge plate 8. The upper side surface 83a of the edge plate 8 and the inner surface of the eaves portion 63 each have a position and shape that match the outer shape of the first end surface 55, so the eaves portion 63 comes into contact with the upper side surface 83a of the edge plate 8.

The procedure for placing the coil 5, upper cover 6, lower cover 7, and edge plate 8 in the lower die is not limited to this. For example, the coil 5 with the lower cover 7, edge plate 8, and upper cover 6 attached may be placed in the lower die. The attachment procedure may also be in the order of lower cover 7, edge plate 8, and upper cover 6, or a different attachment procedure may be used. If the coil 5 is attached with the coil coating resin 3 excluding the mold resin 9 before being placed in the lower die, the coil 5 is protected by the coil coating resin 3 excluding the mold resin 9, and it is possible to prevent the coil 5 from accidentally colliding with the die when it is placed in the die.

When the coil 5 is protected by the coil coating resin 3 (excluding the molding resin 9) and then attached to the mold, the eaves 63 of the upper cover 6 covers the edge plate 8 and the edge ring plate 74, which also serves to prevent the lower cover 7 and edge plate 8 from falling off, improving the transportability of the coil 5 to the mold.

After the coil 5, upper cover 6, lower cover 7, and edge plate 8 are placed in the lower die, the upper cover 6 is covered with the upper die, and molding resin 9 is injected into the die. Figure 9 shows the coil inside the die, and is a front view seen from the edge plate side. As shown in Figure 9, inside the die, the upper die presses the upper plate 61 of the upper cover 6, and a downward force P1 acts on the upper cover 6. The coil 5 covered by the upper cover 6 is also pressed downward through the upper cover 6.

The coil 5 is placed on the lower cover 7 inside the mold. Therefore, a force P2 acts on the lower cover 7 in the direction of the lower mold via the coil 5, and the U-shaped frame 71 of the lower cover 7 adheres closely to the lower mold. Therefore, inside the mold, the resin of the molded resin 9 is prevented from entering the frame body 58a between the U-shaped frame 71 and the lower mold.

The lower cover 7 and the edge plate 8 are fitted with the recess 75 on the lower cover 7 side and the protrusion 82 on the edge plate 8 side, and a downward force P3 is transmitted from the lower cover 7 to the edge plate 8 via the recess 75 and the protrusion 82, and a force P4 is generated on the side wall 81 of the edge plate 8, which presses the side wall 81 of the edge plate 8 against the lower die. This force P4 causes the side wall 81 of the edge plate 8 to adhere closely to the lower die. Therefore, although the side wall 81 is separated from the U-shaped frame 71, the side wall 81 is pressed against the lower die by the force P4 generated on the side wall 81 via the fitting portion of the recess 75 and the protrusion 82. Therefore, the resin of the molded resin 9 is prevented from entering the frame body 58a between the side wall 81 and the lower die.

Furthermore, the edge plate 8 is covered with the eaves portion 63 of the upper cover 6, and a force P5 is generated in which the eaves portion 63 presses the upper surface 83a of the edge plate 8 downward. This force P5 is added to the force P4 with which the side wall 81 is pressed against the lower die, so that the side wall 81 can be pressed against the lower die more reliably.

Figure 10 is an enlarged partial cross-sectional view showing the forces acting on the coil 5 and the vertical side portion 72 in the mold. In the mold, the outer surface 721c of the vertical side portion 72 of the lower cover 7 abuts against the lower mold. When the upper mold presses the upper cover 6, a force P6 is generated on the lower curved surface 53 of the coil 5, which presses it against the contact surface 721a of the vertical side portion 72. This vertical side portion 72 is supported by the lower mold at the outer surface 721c. Therefore, the lower curved surface 53 of the coil 5 is crushed between the coil 5 and the contact portion 721 of the vertical side portion 72.

Here, for reasons of manufacturing precision, the surface of the coil 5 has twists and unevenness, and is not necessarily smooth. In particular, the lower curved surface 53 of the coil 5 must maintain a constant curvature during one turn, and the curvature must be the same for all turns, so twists and unevenness are likely to occur, and the unevenness is likely to become large. However, the lower curved surface 53 of the coil 5 is pressed against the contact portion 721, which corrects the twists and unevenness, and the coil 5 is closely contacted with the vertical side portion 72 without any gaps. Therefore, the resin of the molded resin 9 is prevented from entering the frame body 58a through the gap between the vertical side portion 72 and the coil 5.

The angle between the contact surface 721a and the upper end surface 721b and the angle between the upper end surface 721b and the outer surface 721c are both right angles. Therefore, the force of the lower mold supporting the outer surface 721c efficiently generates a force P7 that brings the horizontal surface 54 and the vertical side portion 72 into contact with each other on the upper end surface 721b side. This force P7 firmly blocks the upper boundary between the vertical side portion 72 and the coil 5, which can be an entrance for the resin of the molded resin 9 to enter the frame body 58a. Note that it is most balanced and desirable for the angle between the contact surface 721a and the upper end surface 721b and the angle between the upper end surface 721b and the outer surface 721c to be right angles, but they may be obtuse angles or acute angles rather than strictly right angles depending on the injection pressure of the molded resin 9.

Moreover, the vertical side portion 72 is extended until the upper end surface 721b rests on the horizontal surface 54. Here, when the force P1 pressing the upper cover 6 is transmitted and the force of the coil 5 pressing the lower cover 7 is transmitted from the lower curved surface 53 to the vertical side portion 72, a component is generated in the outward direction of the coil. However, the horizontal surface 54 is perpendicular to the direction of the force P1 pressing the upper cover 6. Therefore, no force is applied from the horizontal surface 54 to the vertical side portion 72 in the outward direction of the coil. Therefore, the force with which the lower mold supports the outer surface 721c is not reduced by the force component in the outward direction of the coil near the upper end surface 721b, and is transformed into a force P7 that more efficiently brings the horizontal surface 54 and the vertical side portion 72 into close contact with each other.

Figure 11 is a transition diagram showing the compression of the coil in the mold. When the coil 5 is placed in the mold and the upper cover 6 is pressed by the upper die, the resin of the molding resin 9 is injected into the mold. The resin injection port of the molding resin 9 is provided at least in a position facing the first end face 55 of the coil 5, and the resin of the molding resin 9 is injected toward the first end face 55 of the coil 5 along the cylindrical axis direction of the coil 5. That is, the coil 5 is subjected to an injection pressure P8 directed toward the inside of the coil vertical direction.

The coil 5 is compressed by a length D1 due to the injection pressure P8 directed inward in the coil vertical direction, and the length of the coil 5 in the coil vertical direction is reduced from the length L1 before compression to the length L2 after compression. Here, the edge plate 8 covers the first end surface 55 of the coil 5, and the injection pressure P8 is applied to the flat surface 83 of the edge plate 8, and the coil 5 receives the injection pressure P8 via the edge plate 8.

The edge plate 8 is an independent member separate from the upper cover 6 and the lower cover 7, and is movable in the coil vertical direction. That is, the engagement between the convex portion 82 and the concave portion 75 restricts the movement of the edge plate 8 in the vertical direction, but does not restrict the movement of the edge plate 8 in the coil vertical direction. Therefore, when the coil 5 receives the injection pressure P8 through the edge plate 8 and the coil 5 is compressed by a length D1 due to this injection pressure P8, the edge plate 8 also moves inward in the coil vertical direction by the length D1 and continues to adhere to the first end surface 55 of the coil 5.

At this time, the convex portion 82 extending from the horizontal side wall 81 slides in the groove portion 76 continuing from the concave portion 75. Therefore, the horizontal side wall 81 of the edge plate 8 continues to be restricted in the up and down direction even during movement in the vertical direction of the coil due to the injection pressure P8, and maintains close contact with the lower die. Therefore, the resin of the molded resin 9 is prevented from entering the frame body 58a between the horizontal side wall 81 and the lower die, even during movement of the horizontal side wall 81 in the vertical direction of the coil due to the injection pressure P8.

Figure 12 is a bottom view showing the compression of the coil 5 in the mold, where (a) shows the state before compression, (b) shows the state after compression of the molded coil according to this embodiment, and (c) shows the state after compression when the side wall and the U-shaped wall are connected.

As shown in (a) and (b) of FIG. 12, the horizontal side wall 81 is separated from the U-shaped frame 71 and can move independently, so the length of the frame body 58a in the coil vertical direction changes according to the length of the coil 5 after compression, and the coil 5 and the frame body 58a continue to be in close contact all around. Therefore, even if the vertical length of the coil 5 changes, it is possible to prevent the resin of the mold resin 9 from entering the opening 58 and causing burrs.

In other words, as shown in (a) and (c) of FIG. 12, it is assumed that the horizontal side wall 81 and the U-shaped frame 71 are integral and the position of the horizontal side wall 81 is immovable. In this case, even if the length of the coil 5 after compression changes, the length of the frame body 58a in the coil vertical direction remains unchanged. In this case, a gap 58b is generated between the first end surface 55 of the coil 5 and the horizontal side wall 81, and the coil 5 and the frame body 58a cannot continue to be in close contact with each other all around.

In order to prevent the occurrence of this gap 58b, when the position of the horizontal side wall 81 is fixed, the lower part of the horizontal side wall 81 must be folded back along the underside 52 of the coil 5 by a length equal to or greater than the gap 58b, so that even if a gap 58b occurs, the horizontal side wall 81 must cover and hide the gap 58b. However, since the length of the gap 58b varies from one piece to another, a buffer is required for the folding back along the underside 52 of the horizontal side wall 81. Therefore, even after the coil 5 is compressed, this folding back will be on the underside 52 of the coil 5. Therefore, the entire underside 52 of the coil 5 cannot be exposed to the opening 58 in the coil vertical direction.

On the other hand, when the horizontal side wall 81 is separated from the U-shaped frame 71 and can move independently, there is no gap 58b, so there is no need to fold back the lower part of the horizontal side wall 81 along the lower surface 52, and the entire lower surface 52 of the coil 5 in the lower coil vertical direction is exposed to the opening 58. As a result, in this molded coil 2, the coil coating resin 3 consisting of the molded resin 9, upper cover 6, lower cover 7, and edge plate 8 exposes the entire lower surface 52 in the coil vertical direction, and the entire lower surface 52 and both lower edge regions 53a of both lower curved surfaces 53 in the coil horizontal direction, while suppressing the generation of burrs.

As described above, the molded coil 2 and reactor 100 include a frame body 58a that is placed on the coil 5, and a molded resin 9 that covers the coil 5 except for the frame body of the frame body 58a. The frame body 58a has a horizontal side wall 81 and a U-shaped frame 71, and is defined by combining the horizontal side wall 81 and the U-shaped frame 71 in a rectangular shape, and the lower surface 52, for example, is contained within the frame as the first flat surface of the four flat surfaces.

The horizontal wall 81 is provided on the edge plate 8, which has a flat surface 83 that covers the first end surface 55, and is movable along the axial direction of the coil 5 when the molded resin 9 is not present. On the other hand, the U-shaped frame 71 extends along the axial direction of the coil 5 and has a pair of vertical side portions 72 that are in close contact with the coil 5, and a horizontal side portion 73 that extends between the pair of vertical side portions 72.

The horizontal wall 81 is in close contact with the first end surface 55 covered by the flat surface 83 of the edge plate 8, and the horizontal portion 73 of the U-shaped frame 71 is in close contact with the second end surface 57 opposite the edge plate 8. The coil 5 has a first flat surface, such as the bottom surface 52, exposed from the molded resin 9 over the entire vertical width range from the first end surface 55 with which the horizontal wall 81 is in close contact to the second end surface 57 with which the horizontal portion 73 is in close contact.

As a result, even if the coil 5 is compressed in the coil vertical direction by the injection pressure P8, the horizontal side wall 81 follows and continues to adhere to the first end surface 55, so that the entire first flat surface, such as the lower surface 52, can be contained in the opening 58 in the coil vertical direction without generating burrs, thereby improving the heat dissipation effect of the molded coil 2 and the reactor 100.

The pair of vertical side portions 72 sandwich a first flat surface, such as the lower surface 52, and are in close contact with two curved surfaces, such as the lower curved surface 53, adjacent to the first flat surface. The coil 5 is configured so that at least the first flat surface is exposed from the molded resin 9 over the entire width range from one curved surface to which the pair of vertical side portions 72 are in close contact to the other curved surface. This makes it possible to correct any twists or unevenness that may occur in the coil 5 and to bring the coil 5 and the vertical side portions 72 into close contact. Therefore, a wider exposed area can be formed on the coil 5 without generating burrs, and the heat dissipation effect can be further improved.

In addition, in the vertical side portion 72, the angle between the contact surface 721a and the upper end surface 721b is approximately a right angle, and the angle between the upper end surface 721b and the outer surface 721c is approximately a right angle. The contact surface 721a is in contact with the curved surface adjacent to the first flat surface . The upper end surface 721b is adjacent to the contact surface 721a, extends along the cylindrical axis of the coil 5, expands in a direction away from the contact surface 721a, and is perpendicular to the first flat surface. The outer surface 721c is adjacent to the upper end surface 721b and is the opposite surface to the contact surface 721a. This allows the contact surface 721a to be strongly pressed against the coil 5, and the twists and unevenness generated in the coil 5 can be corrected with even greater precision, and the coil 5 and the vertical side portion 72 can be further in contact with each other. Therefore, the generation of burrs can be further suppressed.

In addition, the contact surface 721a is adapted to contact a flat surface such as the horizontal surface 54 that is perpendicular to a first flat surface such as the lower surface 52. This allows the force with which the lower mold supports the vertical side portion 72 to efficiently press the contact surface 721a against the coil 5, and allows the coil 5 and the vertical side portion 72 to be more efficiently brought into contact with each other. In other words, the force is not offset by the force component in the horizontal direction of the coil that is generated from the lower curved surface 53 of the coil 5 to the vertical side portion 72. Moreover, the entrance of the gap between the coil 5 and the vertical side portion 72 can be blocked.

In addition, a plate covering the flat surface located opposite the first flat surface, for example an upper plate 61 covering the top surface 51, is provided, and this plate has an eave portion 63 extending beyond the position of the first end surface 55 covered by the edge plate 8. As a result, the eave portion 63 comes into contact with the upper side surface 83a of the edge plate 8, and when the upper cover 6 is pressed by the upper mold, the edge plate 8 having the horizontal side wall 81 is pressed via the upper side surface 83a of the edge plate 8. Therefore, the horizontal side wall 81 continues to adhere to the lower mold even when separated from the U-shaped frame 71, and the resin of the molded resin 9 can be prevented from leaking into the frame body 58a from between the horizontal side wall 81 and the lower mold.

In addition, the pair of vertical side portions 72 of the U-shaped frame 71 and the horizontal side wall 81 of the edge plate 8 have recesses 75 and protrusions 82 that restrict the horizontal side wall 81 from moving toward the flat surface opposite the first flat surface, and the recesses 75 and protrusions 82 are fitted together. As a result, the recesses 75 and protrusions 82 press the horizontal side wall 81 downward even if it tries to move in the vertical direction. Therefore, the horizontal side wall 81 continues to adhere to the lower mold even when separated from the U-shaped frame 71, and it is possible to prevent the resin of the molded resin 9 from leaking into the frame body 58a from between the horizontal side wall 81 and the lower mold.

A groove 76 extends from the recess 75 along the cylindrical axis of the coil 5, and the horizontal wall 81 slides in the groove 76 at the protrusion 82. This allows the horizontal wall 81 to continue to adhere to the lower die while moving in response to the compression of the coil 5, preventing the resin of the molded resin 9 from leaking into the frame of the frame body 58a from between the horizontal wall 81 and the lower die.

The above-mentioned embodiments of the present invention are presented as examples, and the present invention is not limited to the above-mentioned embodiments. The above-mentioned 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.

First, the coil 5 may be covered by the coil coating resin 3 excluding the upper cover 6. In other words, the upper cover 6 may be eliminated. In this case, the upper die may be pressed directly against the edge plate 8 and the upper surface 51 of the coil 5. For example, the lower surface 52 of the coil 5 is in contact with a metal cooling plate or the like via a heat dissipation sheet, and scratches on the lower surface of the coil 5 may cause insulation failure. However, no metal members or the like are placed near the upper surface 51 of the coil 5, and there is no need to take measures to prevent scratches on the upper surface 51 of the coil 5 as with the lower surface 52. In such cases, the upper cover 6 is not essential.

In addition, the convex portion 82 of the edge plate 8 and the concave portion 75 and groove portion 76 of the vertical side portion 72 of the lower cover 7 may be eliminated. If the pressing force P1 from the upper die can be directly or indirectly transmitted to the edge plate 8, the horizontal side wall 81 can be brought into close contact with the lower die. By fitting the convex portion 82, the concave portion 75, and the groove portion 76, the horizontal side wall 81 can be brought into closer contact with the lower die more reliably, and can be more reliably held down downward even when moving due to the injection pressure. On the other hand, if the convex portion 82, the concave portion 75, and the groove portion 76 are not present, the horizontal side wall 81 will be more likely to move in accordance with the coil 5.

100 Reactor 1 Core 2 Molded coil 3 Coil coating resin 5 Coil 51 Upper surface 52 Lower surface 53 Lower curved surface 53a Lower edge region 54 Horizontal surface 55 First end surface 56 Upper curved surface 57 Second end surface 58 Opening 58a Frame body 58b Gap 59 Conductive wire 6 Upper cover 61 Upper plate body 62 Side curved plate 63 Eaves portion 64 Cutout 7 Lower cover 71 U-shaped frame 72 Vertical side portion 721 Contact portion 721a Contact surface 721b Upper end surface 721c Outer surface 722 Vertical portion 73 Horizontal side portion 74 Edge annular plate 75 Recess 76 Groove portion 8 Edge plate 81 Horizontal side wall 82 Convex portion 83 Flat surface 83a Upper surface 9 Molded resin

Claims (8)

a cylindrical coil whose outer shape is defined by a pair of coil end faces and a side surface having four flat surfaces and four curved surfaces arranged alternately and perpendicular to the pair of coil end faces;
A frame body having a horizontal side wall and a U-shaped frame, the horizontal side wall and the U-shaped frame being combined into a rectangular shape, the frame body being disposed on the coil so that a part or all of a first flat surface of the four flat surfaces is contained within the frame;
a molding resin that covers a part or all of the coil except for the inside of the frame of the frame body;
an edge plate having a flat surface covering one of the pair of coil end surfaces and the lateral side wall, the edge plate being movable along a cylindrical axis direction of the coil when the molding resin is not present;
A plate body covering the flat surface located opposite the first flat surface;
Equipped with
The U-shaped frame is
A pair of vertical side portions extending along a cylindrical axis of the coil and in close contact with the coil;
a horizontal side portion extending between the pair of vertical side portions;
having
the horizontal side wall is in intimate contact with the coil end surface that is covered by the flat surface of the edge plate,
The horizontal side of the U-shaped frame is in close contact with the coil end surface opposite to the edge plate,
the plate body has an overhanging portion extending beyond the position of the coil end surface covered by the edge plate,
The overhanging portion of the plate body contacts a side surface of the edge plate,
the coil has the first flat surface exposed from the molding resin over an entire vertical width range from one of the coil end faces with which the horizontal side wall is in close contact to the other of the coil end faces with which the horizontal side portion is in close contact;
A molded coil characterized by: The pair of vertical side portions sandwich the first flat surface and are in close contact with the two curved surfaces adjacent to the first flat surface,
the coil has at least the first flat surface exposed from the molding resin over an entire width range from one of the curved surfaces where the pair of vertical side portions are in close contact to the other of the curved surfaces;
2. The molded coil according to claim 1, The vertical side portion is
a contact surface adjacent to the first flat surface and in close contact with the curved surface;
An end surface on the flat surface side perpendicular to the first flat surface, the end surface being adjacent to the contact surface, extending along the cylindrical axis of the coil, and expanding in a direction away from the contact surface;
an outer surface adjacent to the end surface and opposite the contact surface;
having
The angle between the contact surface and the end surface is approximately a right angle,
The angle between the end surface and the outer surface is approximately a right angle;
3. The molded coil according to claim 2, wherein The contact surface is in contact with the curved surface adjacent to the first flat surface, as well as the flat surface perpendicular to the first flat surface;
4. The molded coil according to claim 3, The horizontal side wall extends equal to the distance between the opposing surfaces of the pair of vertical side portions,
the frame body is defined by fitting the horizontal side wall between the pair of vertical side portions;
5. The molded coil according to claim 1, wherein The pair of vertical side portions of the U-shaped frame and the horizontal side wall of the edge plate have projections and recesses that restrict the horizontal side wall from moving in the direction of the flat surface located opposite to the first flat surface, and the projections and recesses are engaged with each other;
6. The molded coil according to claim 1 , wherein The pair of vertical side portions each have a recess among the projections and recesses, and a groove portion extending from the recess along a cylindrical axis of the coil,
The horizontal side wall has a convex portion among the concave and convex portions,
the protrusion fits into the recess and slides within the groove in accordance with the movement of the horizontal side wall;
The molded coil according to claim 6 , A molded coil according to any one of claims 1 to 7 ;
a core including a magnetic body to which the molded coil is attached;
A reactor comprising:

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