Mold coil and method for manufacturing mold coil

Abstract

To provide a mold coil which prevents damages of a coating film on a bending surface of a coil and blocks inflow of resin to an exposure surface of the coil, and a method for manufacturing the coil.SOLUTION: A mold coil includes: a coil 1 having four flat surfaces of an upper surface, a lower surface, and a pair of side surfaces and four bending surfaces, the four flat surfaces and the four bending surfaces being alternately formed; and a lower surface cover 3 on the lower surface of the coil 1. At least a part of the coil 1 other than the lower surface of the coil 1 is coated by a mold resin. A lower surface cover 3 has a frame-like part 31 exposing the lower surface of the coil 1 and a wall part 32 standing from the frame-like part 31. The wall part 32 is in contact with a side surface 13 of the coil 1 and is not in contact with a bending surface 14 of the coil 1. The mold resin is ejected from above the wall part 32 in mold formations.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a molded coil to be molded and a method for manufacturing the molded coil.

Background Art

[0002] Coil components such as reactors are used in various applications such as OA equipment, solar power generation systems, and automobiles. The coil component is formed by winding a coil around a core made of a magnetic material. Also, a resin member is provided between the core and the coil to insulate the core and the coil.

[0003] In recent years, molded coils in which a coil alone or a coil and a core together are molded with resin of a resin member have been used everywhere. In molded molding, the coil and the core are arranged at predetermined positions in a mold, resin is injected into the mold, and solidified to produce a molded coil in which the inner peripheral surface and the outer peripheral surface of the coil and the core are covered with a resin member.

[0004] However, in order to enhance heat dissipation, the surface of the coil may not be covered with resin and may be exposed. In order to expose it, it is necessary to strongly press the mold against the exposed surface of the coil in order to prevent the resin from flowing into the exposed surface. On the other hand, if the mold is strongly pressed, the surface of the coil may be damaged and the coating such as enamel on the surface of the coil may be peeled off. Therefore, a method has been proposed in which a part of the surface of the coil is covered with a resin cover and this cover is interposed between the coil and the mold and pressed.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] The coil is formed by winding a single conductive member coated with a film such as enamel while shifting the winding position in the axial direction of the winding shaft in a cylindrical shape. Therefore, the film on the curved surface of the coil formed by bending the conductive member is thin. Therefore, regarding the curved surface of the coil, even when a resin cover is used, there is still a problem that the film is damaged and peeled off.

[0007] The present invention has been made to solve the above problems, and an object thereof is to provide a molded coil and a method for manufacturing a molded coil that can prevent damage to the film on the curved surface of the coil and prevent the resin from flowing into the exposed surface of the coil.

Means for Solving the Problems

[0008] The molded coil of the present invention includes a coil in which four flat surfaces and four curved surfaces, which are an upper surface, a lower surface, and a pair of side surfaces, are alternately formed, a lower cover disposed on the lower surface of the coil, and a molded resin that covers at least a part of the periphery of the coil except for the lower surface of the coil. The lower cover has a frame portion that exposes the lower surface of the coil and a wall portion that rises from the frame portion, and the wall portion is in contact with the side surface of the coil and not in contact with the curved surface of the coil.

[0009] The manufacturing method of the mold coil of the present invention is a manufacturing method of a mold coil that is injection-molded with the coil alone, and includes a mounting step of mounting a cover on the coil, and a step of housing the coil with the cover mounted therein in a mold, and injection-molding the mold resin to cover at least a part of the periphery of the coil except for the lower surface of the coil. The coil has four flat surfaces, namely an upper surface, a lower surface, and a pair of side surfaces, and four curved surfaces are alternately formed. The cover has a frame-shaped portion that exposes the lower surface of the coil and a wall portion that rises from the frame-shaped portion. The mold has a thick portion on the surface facing the coil that protrudes toward the coil. In the mounting step, the wall portion is mounted so as not to contact the curved surface of the coil and to contact the side surface of the coil. In the injection-molding step, the mold resin flowing toward the wall portion flows out toward the wall portion after passing through a narrow flow path between the coil and the thick portion.

[0010] Further, the manufacturing method of the mold coil of the present invention is a manufacturing method of a mold coil that injection-molds a coil and a core, and includes a mounting step of mounting a cover on the coil, an assembly step of producing an assembly in which the core is assembled to the coil, and a step of housing the assembly in a mold, and injection-molding the mold resin to cover at least a part of the periphery of the coil except for the lower surface of the coil. The coil has four flat surfaces, namely an upper surface, a lower surface, and a pair of side surfaces, and four curved surfaces are alternately formed. The cover has a frame-shaped portion that exposes the lower surface of the coil and a wall portion that rises from the frame-shaped portion. The core is covered with a core coating resin, and the core coating resin has a thick portion on the surface facing the coil that protrudes toward the coil. In the mounting step, the wall portion is mounted so as not to contact the curved surface of the coil and to contact the side surface of the coil. In the injection-molding step, the mold resin flowing toward the wall portion flows out toward the wall portion after passing through a narrow flow path between the coil and the thick portion.

Advantages of the Invention

[0011] According to the present invention, it is possible to obtain a molded coil and a method for manufacturing the molded coil that can prevent damage to the coating on the curved surface of the coil and block the inflow of resin to the exposed surface of the coil.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0013] (Embodiment) The molded coil according to the embodiment will be described with reference to the drawings. FIG. 1 is a perspective view showing the main constituent members of the molded coil 10. In each drawing, for ease of understanding, the thickness, dimensions, positional relationship, ratio, shape, etc. may be emphasized and shown, and the present invention is not limited to those emphasized.

[0014] As shown in Fig. 1, the molded coil 10 includes a coil 1, a core 5, and a core coating resin 6. The coil 1 is mounted on the core 5. The core 5 is coated with the core coating resin 6. That is, the core coating resin 6 is interposed between the coil 1 and the core 5. The core coating resin 6 insulates the coil 1 and the core 5. When power is supplied from an external device to the coil 1, a magnetic flux is generated. The core 5 forms a closed magnetic path through which the magnetic flux passes. In this way, the molded coil 10 is an electromagnetic component that converts electrical energy into magnetic energy for storage and release.

[0015] Fig. 2 is an exploded perspective view showing the state before various covers 2, 3, and 4 are mounted on the coil 1. Fig. 3 is a perspective view showing the state where various covers 2, 3, and 4 are mounted on the coil 1. The coil 1 is composed of a single conductive member insulated with enamel or the like. The coil 1 is formed by winding the conductive member in a cylindrical shape while shifting the winding position in the winding axis direction. The conductive member is, for example, a rectangular wire, and the coil 1 is an edgewise coil in which the wide surface of the conductive member extends in a direction orthogonal to the winding axis of the coil 1. Note that the coil 1 may be a flatwise coil. Also, a round wire may be used as the conductive member.

[0016] The coil 1 has four flat surfaces. The four flat surfaces are an upper surface 11, a lower surface 12 located on the opposite side of the upper surface 11, and a pair of side surfaces 13 located between the upper surface 11 and the lower surface 12. A curved surface 14 is interposed between each of the flat surfaces of the upper surface 11, the lower surface 12, and the pair of side surfaces 13. That is, the coil 1 has four curved surfaces 14. In this way, the coil 1 has a rounded shape in which curved surfaces 14 are provided between the four flat surfaces of the upper surface 11, the lower surface 12, and the pair of side surfaces 13, respectively. Note that the up-down direction is the up-down direction of the coil 1 when it is arranged in the mold during the molding process described later, and does not refer to the positional relationship when the molded coil 10 is installed on the object to be installed. Also, the flat surface is a surface that is relatively flat compared to the curved surface 14, and a state in which a large arc is drawn with a gentle curvature due to the swelling of the conductive member during winding is also included in the flat surface.

[0017] Coil 1 has two lead wires 15. The lead wires 15 are connected to a bus bar (not shown) by welding or the like. The bus bar is electrically connected to an external device. The molded coil 10 is electrically connected to the external device via the bus bar.

[0018] The periphery of the coil 1 is covered by an upper cover 2, a lower cover 3, and an end face cover 4. The upper cover 2, the lower cover 3, and the end face cover 4 prevent the mold, the pressing member, the jig, the resin to be injected, etc. from directly contacting the coil 1 during the molding process. The upper cover 2, the lower cover 3, and the end face cover 4 are formed as separate bodies respectively.

[0019] The upper cover 2, the lower cover 3, and the end face cover 4 are made of resin. Examples of the resin type include epoxy resin, unsaturated polyester resin, urethane resin, BMC (Bulk Molding Compound), PPS (Polyphenylene Sulfide), PBT (Polybutylene Terephthalate), etc.

[0020] The upper cover 2 covers the upper surface 11 of the coil 1. The upper cover 11 covers the entire upper surface 11 of the coil 1 and also covers a part of each curved surface 14 connected to the upper surface 11.

[0021] The lower cover 3 is disposed on the lower surface 12 of the coil 1. The lower cover 3 has a frame portion 31 and a wall portion 32. The frame portion 31 and the wall portion 32 are connected without a joint and are integrally formed.

[0022] The frame portion 31 is annular. The frame portion 31 is disposed on the lower surface 12 of the coil 1. Therefore, the lower surface 12 of the coil 1 is not covered by the lower cover 3 and is exposed. The frame portion 32 may expose not only the lower surface 12 of the coil 1 but also a part of the curved surface 14 connected to the lower surface 2. The frame portion 31 abuts against the mold during the molding process. The frame portion 31 prevents the resin from flowing into the lower surface 12 of the coil 1 during the molding process.

[0023] The wall portion 32 rises from the side of the frame-shaped portion 31 parallel to the scroll. More specifically, the wall portion 32 rises from the inner edge of the frame-shaped portion 31. The wall portion 32 faces the curved surface 14 connected to the lower surface 12 of the coil 1 and the side surface 13 of the coil 1.

[0024] The wall portion 32 rises up to a height above the boundary between the curved surface 14 connected to the lower surface 12 of the coil 1 and the side surface 13. However, the wall portion 32 does not reach the height of the thick portion 621 of the core coating resin 6 described later.

[0025] The wall portion 32 is thickest at the portion connected to the frame-shaped portion 31 and tapers towards the tip. Also, the outer peripheral surface 321 of the wall portion 32 is curved. The outer peripheral surface 321 is located on the opposite side of the inner peripheral surface of the wall portion 32 facing the coil 1 and faces the thin portion 622 of the core coating resin 6.

[0026] FIG. 4 is an enlarged view of the tip portion 323 of the wall portion 32. As shown in FIG. 4, the wall portion 32 has an R portion 322. The R portion 322 is curved. The R portion 322 is formed on the coil 1 side of the tip portion 323 of the wall portion 32. The wall portion 32 contacts the side surface 13 of the coil 1 by this R portion 322. That is, the R portion 322 contacts the coil 1 at a position above the boundary between the curved surface 14 connected to the lower surface 12 of the coil 1 and the side surface 13. In particular, it is preferable that the R portion 322 contacts the coil 1 at a position higher than the boundary between the curved surface 14 connected to the lower surface 12 of the coil 1 and the side surface 13.

[0027] Also, the inner peripheral surface of the wall portion 32 does not contact the curved surface 14 of the coil 1. Note that the inner peripheral surface of the wall portion 32 may contact the side surface 13 of the coil 1. That is, the wall portion 32 may contact the coil 1 other than the R portion 322. However, it is preferable that the inner peripheral surface of the wall portion 32 does not contact the side surface 13 of the coil 1 because it can prevent damage to the insulating film of the coil 1.

[0028] The end face cover 4 covers one end face that is orthogonal to the winding axis of the coil 1. The coil 1 is pressed during the molding process so that the length in the winding axis direction becomes the desired length. At this time, of the pair of end faces orthogonal to the winding axis of the coil 1, one is pressed and the other is fixed. The end face cover 4 covers the end face on the pressed side. The end face cover 4 is annular.

[0029] The core 5 contains a magnetic material. As the core 5, a compacted powder core, a ferrite core, a laminated steel plate, a metal composite core, etc. can be used. The metal composite core is a magnetic material formed by kneading magnetic powder and resin and curing the resin.

[0030] Figure 5 is an exploded perspective view of the mold core. As shown in Figure 5, the core 5 is composed of two E-shaped core members 51 and 52. By joining the E-shaped core members 51 and 52, the core 5 becomes annular.

[0031] The E-shaped core members 51 and 52 include a middle leg 53, a pair of outer legs 54, and a yoke portion 55. The middle leg 53 has the coil 1 mounted thereon. The pair of outer legs 54 extend parallel to the extending direction of the middle leg 53 and are respectively disposed with a gap between them on both sides of the middle leg 53. The extending lengths of the middle leg 53 and the pair of outer legs 54 are the same. The yoke portion 55 connects the middle leg 53 and the pair of outer legs 54.

[0032] Around the core 5, a core coating resin 6 is formed by molding. The core coating resin 6 has a middle leg coating portion 61, an outer leg coating portion 62, and a yoke coating portion 63. The middle leg coating portion 61 covers the middle leg 53. The outer leg coating portion 62 covers the outer leg 54. The yoke coating portion 63 covers the yoke portion 55.

[0033] FIG. 6 is an enlarged view of the outer leg covering portion 62. As shown in FIG. 6, the outer leg covering portion 62 has a thick portion 621 and a thin portion 622. The thick portion 621 and the thin portion 622 are formed in a portion covering the inside of the outer leg 54. The inside of the outer leg 54 refers to the surface facing the middle leg 53, that is, the surface facing the coil 1. The thick portion 621 is thicker than the thin portion 622. That is, the thick portion 621 protrudes toward the middle leg covering portion 61 side more than the thin portion 622, and the gap between the thick portion 621 and the middle leg covering portion 61 is larger than the gap between the thin portion 622 and the middle leg covering portion 61. The thick portion 621 is disposed above the thin portion 622. The boundary portion between the thick portion 621 and the thin portion 622, that is, the step portion, is formed at the central portion of the outer leg 54.

[0034] The core coating resin 6 is made of resin. Examples of the type of resin include epoxy resin, unsaturated polyester resin, urethane resin, BMC (Bulk Molding Compound), PPS (Polyphenylene Sulfide), PBT (Polybutylene Terephthalate), and the like.

[0035] FIG. 7 is a perspective view showing the overall configuration of the mold coil 10. As shown in FIG. 7, the mold coil 10 includes a mold resin 7. The mold resin 7 covers a part of the coil 1, the core 5, and the core coating resin 6. The mold resin 7 covers the wall portion 32, more specifically, the outer peripheral surface 321 of the wall portion 32. The coil 1, the core 5, and the core coating resin 6 are fixed by the mold resin 7. The mold resin 7 does not cover the lower surface 12 of the coil 1 and is exposed.

[0036] The mold resin 7 is made of resin. Examples of the type of resin include epoxy resin, unsaturated polyester resin, urethane resin, BMC (Bulk Molding Compound), PPS (Polyphenylene Sulfide), PBT (Polybutylene Terephthalate), and the like. Further, a heat conductive filler may be mixed into the mold resin 7.

[0037] (Manufacturing Method) Next, the manufacturing method of the mold coil 10 of the present embodiment will be described. The manufacturing method of the mold coil 10 of the present embodiment includes a cover mounting step, an assembly step, and a molding step.

[0038] The cover mounting step is a step of mounting the upper cover 2, the lower cover 3, and the end face cover 4 on the coil 1. First, the coil 1 is covered with the end face cover 4. Then, the lower cover 3 is mounted on the coil 1 covered with the end face cover 4. Even after the lower cover 3 is mounted, the inner peripheral surface of the wall portion 32 of the lower cover 3 does not contact the curved surface 14 of the coil 1, and the R portion 322 of the wall portion 32 contacts the side surface 13 of the coil 1. Finally, the upper cover 2 is placed over the upper surface 11 of the coil 1.

[0039] The assembly step is a step of mounting the coil 1 with the various covers 2, 3, 4 mounted thereon on the core 5. The core 5 is formed as a molded core in which the E-shaped core members 51, 52 are respectively covered with a core coating resin 6 by mold molding in advance. The coil 1 is mounted on the middle leg 53 of one of the E-shaped core members 51, and the other E-shaped core member 52 is inserted into the inner periphery of the coil 1, and the middle leg 53 and the pair of outer legs 54 are joined with an adhesive. In this way, an assembly in which the coil 1 and the core 5 are assembled is produced. At this time, the wall portion 32 is disposed at a position facing the thin portion 622, and the tip of the wall portion 32 does not reach the height of the thick portion 621. Note that the middle leg 53 and the pair of outer legs 54 do not have to be adhered with an adhesive. In this case, when the assembly is housed in a mold, the E-shaped core members 51, 52 may be held by a mold, a jig, or the like. Then, the core 5 is fixed in an annular shape by covering the periphery of the joint portion of the core 5 with the mold resin 7.

[0040] The molding step is a step of covering the assembly with the mold resin 7 by mold molding. First, the assembly is placed in the lower mold of the mold. At this time, the frame portion 31 of the lower cover 3 abuts against the lower mold. Then, the upper mold of the mold is pressed against the upper cover 2 so as to cover the upper cover 2 and fit it with the lower mold.

[0041] Then, the resin that constitutes the mold resin 7 is injected into the mold. The resin is injected from above the mold. FIG. 8 is a diagram showing the flow of the resin toward the wall portion 32. As shown in FIG. 8, the resin injected from above the mold goes from the upper surface side to the lower surface side of the coil 1. The outer leg covering portion 62 of the core covering resin 6 has a thick portion 621 and a thin portion 622, and the thick portion 621 is located above the thin portion 622. Therefore, the resin flowing toward the lower surface of the coil 1 first passes through a gap S1 between the coil 1 and the thick portion 621.

[0042] Here, since the thick portion 621 protrudes more toward the middle leg 53 side than the thin portion 622, the gap S1 between the thick portion 621 and the coil 1 is narrower than the gap S2 between the thin portion 622 and the coil 1. In other words, the wall portion 32 is disposed in a space wider than the gap S1 between the thick portion 621 and the coil 1. Therefore, when the resin passing through the gap S1 is discharged into the gap S2, it is ejected toward the wall portion 32 with increased momentum.

[0043] The wall portion 32 has a tapered shape, and the outer peripheral surface 321 of the wall portion 32 is curved. That is, a space is wider between the outer peripheral surface 321 of the wall portion 32 and the thin portion 622 at the tip portion 323 of the wall portion 32 than on the frame-shaped portion 31 side. Therefore, the resin ejected toward the wall portion 32 easily flows along the outer peripheral surface 321 of the wall portion 32 toward the lower surface 12 side of the coil 1. Further, as the resin flows on the outer peripheral surface 321 of the wall portion 32, the wall portion 32 is pressed by the resin against the side surface 13 of the coil 1, so that the R portion 322 of the wall portion 32 comes into closer contact with the side surface 13 of the coil 1.

[0044] Also, since the lower mold and the frame-shaped portion 31 are in contact with each other, the resin reaching the bottom surface of the lower mold is prevented from flowing into the lower surface 12 of the coil 1. Therefore, the mold resin 7 does not cover the lower surface 12 of the coil 1. In this way, the mold coil 10 in which the lower surface 12 of the coil 1 is exposed is manufactured.

[0045] (Effect) As described above, the molded coil 10 of the present embodiment includes a coil 1 in which four flat surfaces, i.e., an upper surface 11, a lower surface 12, and a pair of side surfaces 13, and four curved surfaces 14 are alternately formed, a lower cover 3 disposed on the lower surface 12 of the coil 1, and a molded resin 7 that covers at least a part of the periphery of the coil 1 except for the lower surface of the coil 1. The lower cover 3 has a frame-shaped portion 31 that exposes the lower surface of the coil 1 and a wall portion 32 that rises from the frame-shaped portion 31. The wall portion 32 is in contact with the side surface 13 of the coil 1 and not in contact with the curved surface 14 of the coil 1.

[0046] In this way, in the molded coil 10 of the present embodiment, since the lower cover 3 is not in contact with the curved portion 14 of the coil 1, it is possible to prevent the film of the curved portion 14 from being peeled off due to contact with the lower cover 3 and the conductive member from being exposed.

[0047] Further, since the wall portion 32 is in contact with the side surface of the coil 1, when the mold is formed, the resin constituting the molded resin 7 is prevented from flowing into the inner peripheral surface of the wall portion 32. Therefore, an exposed surface is formed without the resin flowing into the lower surface 12 of the coil 1.

[0048] In particular, in the present embodiment, since the resin is discharged from above the wall portion 32, the discharged resin 7 hits the wall portion 32 and presses the wall portion 32 in contact with the side surface 13 of the coil 1 in the direction of the coil 1. Therefore, since the wall portion 32 is more closely adhered to and in contact with the side surface of the coil 1, it is possible to effectively prevent the resin from flowing into the inner peripheral surface of the wall portion 32. Since the film on the side surface 13 of the coil 1 is not thinned, there is little risk of damaging the film even if it is pressed more strongly than the curved surface 14.

[0049] An R portion 322 is formed at the tip of the wall portion 32, and the wall portion 32 is in contact with the side surface 13 of the coil 1 by the R portion 322. If the contact surface of the wall portion 32 with the coil 1 is a right-angled shape, there is a risk that the edge portion will be chipped by the injected resin. If the edge portion is chipped, the resin will flow into the inner peripheral surface of the wall portion 32 from there. Therefore, by providing the R portion 322 on the wall portion 32 and bringing it into contact with the side surface 13 of the coil 1 by the R portion 322, it is possible to prevent the wall portion 32 from being chipped and continuously block the inflow of resin.

[0050] The wall portion 32 has a tapered shape, and the outer peripheral surface 321 of the wall portion 32 is curved. As a result, the resin injected from above the wall portion 32 is likely to flow to the outer peripheral surface 321 side of the wall portion 32. Therefore, it is possible to prevent the resin from flowing into the inner peripheral surface of the wall portion 32.

[0051] The wall portion 32 is in contact with the side surface 13 at a position higher than the boundary between the side surface 13 and the curved surface 14 of the coil 1. Since the coil 1 is formed by winding a single conductive member in a cylindrical shape while shifting the winding position in the winding axis direction, the dimensional tolerance of the curved surface 14 is likely to be larger than that of the side surface 13 which is a flat surface. And at the boundary portion between the side surface 13 and the curved surface 14, the influence may remain. When the wall portion 32 is brought into contact with the coil 1 at such a location, the wall portion 32 will contact the conductive member (coil 1) at the outermost periphery that bulges due to winding, and a gap is likely to be generated between the conductive member (coil 1) located inside, and the resin will flow into the inner peripheral surface of the wall portion 32 from the gap. Therefore, by bringing the wall portion 32 into contact with the coil 1 at a position higher than the boundary between the side surface 13 and the curved surface 14 of the coil 1, the possibility of generating a gap between the coil 1 and the wall portion 32 can be reduced, and the resin can be prevented from flowing into the inner peripheral surface of the wall portion 32.

[0052] The mold resin 7 covers the core 5 together with the coil 1. The core 5 is covered with a core covering resin 6, and the core covering resin 6 has a thin portion 622 and a thick portion 621 provided above the thin portion 622 and protruding toward the coil 1 side. The wall portion 32 does not reach the height of the thick portion 621 and faces the thin portion 622.

[0053] As described above, the resin is injected from above the wall portion 32. Above the wall portion 32, there is a thick portion 621, and the gap S1 between the thick portion 621 and the coil 1 is narrower than the gap S2 between the thin portion 622 and the coil 1. That is, during mold forming, the resin passes through the narrow flow path between the thick portion 621 and the coil 1 and is injected into the flow path of the gap S2 between the thin portion 622, which is wider than this flow path, and the coil 1. Since the resin injected into the gap S2 has an increased speed, it presses the wall portion 32 more strongly against the side surface 13 of the coil 1. Therefore, the wall portion 32 can be closely attached to the side surface 13 of the coil 1, and it is possible to more effectively prevent the resin from flowing into the inner peripheral surface of the wall portion 32.

[0054] (Modification example) The mold coil 10 according to the modification example will be described with reference to the drawings. Note that the same reference numerals are given to the same configurations and the same functions as those in the embodiment, and detailed descriptions thereof are omitted. In the above embodiment, the mold coil 10 in which the coil 1 is mold-formed with the mold resin 7 together with the core 5 has been described. However, the mold coil 10 according to the modification example coats the single coil 1 with the mold resin 7 by mold forming.

[0055] FIG. 9 is a diagram showing the flow of the resin toward the wall portion 32 in the mold coil 10 of the modification example. In the modification example, since there is no core 5 and the core coating resin 6 during mold forming, the gap S1 of the narrow flow path cannot be formed by the thick portion 621 and the thin portion 622 of the core coating resin 6.

[0056] Therefore, in the modification example, a flow path similar to that in the embodiment is formed by the mold M. Specifically, the mold M has a thick portion M1 on the surface facing the coil 1 that protrudes toward the coil 1 side, and the lower part of the thick portion M1 is a thin portion M2. And the height of the wall portion 32 does not reach the thick portion M1, and the wall portion 32 is arranged opposite to the thin portion M2. Therefore, when the coil 1 is accommodated in the mold M, the gap S1 between the thick portion M1 and the coil 1 becomes a flow path narrower than the gap S2 between the thin portion M2 and the coil 1.

[0057] Thus, even when the coil 1 is molded alone without being molded together with the core 5, a thin flow path can be formed by forming the thick portion M1 in the mold M. Therefore, since the resin forming the molded resin 7 is injected from the thin flow path into the wide flow path, the force pressing the wall portion 32 by the resin increases, and the wall portion 32 can be brought into close contact with the side surface 13 of the coil 1. As a result, it is possible to more effectively suppress the resin from flowing into the inner peripheral side of the wall portion 32.

[0058] (Other Embodiments) In this specification, embodiments of the present invention have been described, but these embodiments are presented as examples and are not intended to limit the scope of the invention. The above-described embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. Embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and its equivalent scope.

[0059] In the above embodiment, the core coating resin 6 covers the periphery of the core 5 by molding, but it may be molded as a separate body from the core 5 and then assembled to the core 5.

[0060] Further, in the above embodiment, the wall portion 32 has a tapered shape and the outer peripheral surface 321 of the wall portion 32 has a curved shape, but only one of them may be configured. Even in the case of having only one of the configurations, the resin injected from above the wall portion 32 easily flows to the outer peripheral surface 321 side of the wall portion 32, and it is possible to prevent the resin from flowing into the inner peripheral surface of the wall portion 32.

[0061] Further, the wall portion 32 does not have to have a tapered shape, and the outer peripheral surface 321 of the wall portion 32 does not have to be curved. As shown in FIG. 10, the wall portion 32 may extend vertically from the frame portion 31, bend in the direction of the coil 1 by 90 degrees, and its tip surface may contact the side surface 13 of the coil 1. Further, the bending angle is not limited to 90 degrees, and may be, for example, 45 degrees or 60 degrees as long as the tip portion 323 of the wall portion 32 contacts the side surface 13 of the coil 1.

Description of Symbols

[0062] 10 Mold Coil 1 Coil 11 Upper Surface 12 Lower Surface 13 Side Surface 14 Curved Surface 15 Lead Wire 2 Upper Cover 3 Lower Cover 31 Frame Portion 32 Wall Portion 321 Outer Peripheral Surface 322 R Portion 323 Tip Portion 4 End Face Cover 5 Core 51, 52 E-shaped Core Members 53 Middle Leg 54 Outer Leg 55 Yoke Portion 6 Core Coating Resin 61 Middle Leg Coating Portion 62 Outer Leg Coating Portion 621 Thick Portion 622 Thin Portion 63 Yoke Coating Portion 7 Mold Resin

Claims

1. A coil in which four flat surfaces and four curved surfaces, namely an upper surface, a lower surface, and a pair of side surfaces, are alternately formed; A lower cover disposed on the lower surface of the coil; A mold resin that covers at least a part of the periphery of the coil except for the lower surface of the coil; Comprising: The coil is formed by winding a conductive member coated with an insulating film layer; The lower cover: A frame portion that exposes the lower surface of the coil; A wall portion rising from the frame portion; Having: The tip of the wall portion contacts the side surface of the coil, and the wall portion does not contact the curved surface of the coil; A molded coil characterized by the above.

2. An R portion in which the tip of the wall portion is curved is formed on the wall portion; The wall portion is in contact with the side surface of the coil by the R portion; The molded coil according to claim 1, characterized by the above.

3. The wall portion has a tapered shape; The molded coil according to claim 1 or 2, characterized by the above.

4. The outer peripheral surface of the wall portion is curved; The molded coil according to claim 1 or 2, characterized by the above.

5. The wall portion is in contact with the side surface at a position higher than the boundary between the side surface and the curved surface of the coil; The molded coil according to claim 1 or 2, characterized by the above.

6. The mold resin covers a core together with the coil; The core is covered with a core covering resin; The core covering resin: A thin portion; A thick portion provided above the thin portion and protruding toward the coil side; Having: The wall portion does not reach the height of the thick portion and faces the thin portion; The molded coil according to claim 1 or 2, characterized by the above.

7. A method for manufacturing a molded coil by molding a single coil formed by winding a conductive member coated with an insulating film layer, A mounting step of mounting a cover on the coil; A molding step of housing the coil with the cover mounted in a mold and covering at least a part of the periphery of the coil except for the lower surface of the coil with a mold resin; Including: The coil has four flat surfaces and four curved surfaces, namely an upper surface, a lower surface, and a pair of side surfaces, alternately formed; The cover: A frame portion that exposes the lower surface of the coil; A wall portion rising from the frame portion; Having: The mold has a thick portion on the surface facing the coil that protrudes toward the coil. In the mounting step, the wall portion is mounted so as not to contact the curved surface of the coil and the tip of the wall portion contacts the side surface of the coil. In the mold forming step, the mold resin directed toward the wall portion flows out toward the wall portion after passing through a narrow flow path between the coil and the thick portion. A method for manufacturing a molded coil, characterized by the above.

8. A method for manufacturing a molded coil in which a coil formed by winding a conductive member coated with an insulating coating layer and a core are mold-formed, a mounting step of mounting a cover on the coil, an assembling step of producing an assembly in which the core is assembled to the coil, a mold forming step of housing the assembly in a mold and covering at least a part of the periphery of the coil with a mold resin except for the lower surface of the coil, including the coil has four flat surfaces, an upper surface, a lower surface and a pair of side surfaces, and four curved surfaces are alternately formed, the cover has a frame-shaped portion that exposes the lower surface of the coil, and a wall portion that rises from the frame-shaped portion, and has the core is coated with a core coating resin, the core coating resin has a thick portion in which the surface facing the coil protrudes toward the coil, In the mounting step, the wall portion is mounted so as not to contact the curved surface of the coil and the tip of the wall portion contacts the side surface of the coil. In the mold forming step, the mold resin directed toward the wall portion flows out toward the wall portion after passing through a narrow flow path between the coil and the thick portion. A method for manufacturing a molded coil, characterized by the above.

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