Molded coil, reactor and manufacturing method thereof

Abstract

To provide a method for manufacturing a molded coil and a reactor that restrain resin leakage to a heat dissipation surface, and are excellent in heat dissipation, and a molded coil and a reactor.SOLUTION: In a winding step of a molded coil 1, an offset portion 51 is formed on a connecting side end face 23 so as to protrude outward beyond an outer surface 25 adjacent to a heat dissipation surface 27. In a cover set-up step, the outer surface 25 is covered with a side surface cover 66, and the connecting side end face 23 is covered with the connecting side end face cover 65. In a molding step, the side surface cover 66 is pressed against the outer surface 25 by a slide mold MS, and a first coil 2 is compressed in a winding axis direction via the connecting side end face cover 65. The connecting side end face cover 65 has an offset cover 7 that encases the offset portion 51. The side surface cover 66 has a protruding portion 8 that bulges from a surface of the side surface cover 66 and extends until one end is connected to the offset cover 7 and the other end contacts a heat dissipation side bottom surface MS2 of the slide mold MS.SELECTED DRAWING: Figure 7

Description

[Technical field]

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

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

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

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

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

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

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

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

[0009] In order to solve the above-mentioned problems, the manufacturing method of a molded coil according to this embodiment is a manufacturing method of a molded coil having a heat dissipation surface exposed from a coating resin along a winding axis, the manufacturing method including: a winding step of winding a coil while forming an offset portion on at least one end face perpendicular to the winding axis, the offset portion protruding outward from one side face that extends along the winding axis while adjacent to the heat dissipation surface; a cover installation step of covering the side face from which the offset portion protrudes with a side cover, and covering the end face having the offset portion with an end face cover integrally molded with the side cover; and a molding step of pressing the side cover against the side face with a slide die and injecting resin into the die while compressing the coil in the winding axis direction via the end face cover, the end face cover having an offset cover at a boundary with the side cover that protrudes outward from the side cover and envelops the offset portion, the side cover having a protrusion that is connected to the offset cover at one end and that extends up from a surface of the side cover until the other end contacts a bottom surface of the slide die.

[0010] The offset cover may be positioned at a distance from the slide mold before the compression and move closer to the slide mold in response to the compression, and resin injected into the mold may pass over the side cover and flow into between the offset cover and the slide mold, and the protrusion may slide along the bottom surface of the slide mold in response to the compression during the molding process, blocking the path to the heat dissipation surface between the slide mold and the offset cover.

[0011] In order to solve the above-mentioned problems, the method for manufacturing a reactor according to this embodiment includes, after the manufacturing method for a molded coil, an assembly process of mounting the molded coil on a core including a magnetic body.

[0012] In addition, in order to solve the above-mentioned problems, the molded coil according to this embodiment includes a coil which is a wound body of a conductive wire, and a coating resin which covers a surface of the coil, wherein the coil has a heat dissipation surface which extends along a winding axis and is exposed from the coating resin, one side which extends along the winding axis and is adjacent to the heat dissipation surface, an end face which is perpendicular to the winding axis, and an offset portion which is formed on at least one of the end faces and protrudes outward beyond the side face, and the coating resin has: a side cover which covers the side face from which the offset portion protrudes, an end face cover which is integrally molded with the side cover and covers the end face having the offset portion, an offset cover which is formed at the boundary between the end face cover and the side cover, which protrudes outward beyond the side cover and covers the offset portion, and a protrusion which protrudes from the surface of the side cover, extends along the winding axis of the coil, and has one end which is connected to the offset cover.

[0013] The coating resin may include a mold resin that extends until it abuts against the protrusion while contacting the offset cover, and whose width from the offset cover as an end does not reach the tip of the protrusion.

[0014] In order to solve the above-mentioned problems, the reactor according to this embodiment includes such a molded coil, and a core including a magnetic body and on which the molded coil is attached. Effect of the Invention

[0015] According to the present invention, an offset portion is formed on the side surface of the coil, and even when the coil is compressed in a mold, leakage of resin onto the heat dissipation surface can be suppressed, resulting in excellent heat dissipation of the molded coil. [Brief description of the drawings]

[0016] [Figure 1] FIG. [Diagram 2] FIG. 4 is a perspective view showing a coil in a winding process. [Diagram 3] FIG. 11 is an exploded view of the coil showing a cover installation process. [Figure 4] FIG. 11 is a perspective view showing the coil with the cover attached in the cover installation step. [Diagram 5] FIG. 11 is a side view showing the coil with the cover attached in the cover installation process. [Figure 6] FIG. 11 is a front view showing the coil placed in a mold during a molding process. [Figure 7] FIG. 13 is a perspective view showing a state in which a slide mold is disposed in a molding process. [Figure 8] FIG. 11 is a side view showing a state in which a slide mold is disposed in a molding process. [Figure 9] FIG. 11 is a side view showing a state in which resin has flowed in during a molding process. [Figure 10] FIG. 4 is a side view showing a state after a molding resin has been formed in a molding process. [Figure 11] FIG. [Figure 12] FIG. 2 is a perspective view of a reactor including a secondary molding resin. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, a method for manufacturing a molded coil according to an embodiment of the present invention will be described with reference to the drawings. In each drawing, thickness, dimensions, positional relationship, ratio, shape, and the like may be emphasized for ease of understanding, but the present invention is not limited to such emphasis.

[0018] 1 is a perspective view of a molded coil 1. The molded coil 1 includes a first coil 2 and a second coil 3. The first coil 2 and the second coil 3 are cylindrically wound bodies of conductive wire 11, such as enamel-coated copper wire. Lead wires 21 are drawn out from the first coil 2 and the second coil 3, and electricity is passed through the lead wires 21 to the first coil 2 and the second coil 3, generating magnetic flux according to the number of turns. Therefore, the molded coil 1 including the first coil 2 and the second coil 3 is used in electromagnetic components called reactors, which convert electric energy into magnetic energy and store and release the energy.

[0019] The reactor has an annular core containing a magnetic body, and the molded coil 1 is fitted onto this core. The molded coil 1 has a coating resin 6 to insulate the first coil 2 and the second coil 3 from the core. The coating resin 6 coats the first coil 2 and the second coil 3. However, to ensure the heat dissipation of the first coil 2 and the second coil 3, the first coil 2 and the second coil 3 have a heat dissipation surface 27, which is exposed from the coating resin 6. In other words, the coating resin 6 covers at least the portions of the core close to the first coil 2 and the second coil 3.

[0020] A part of the coating resin 6 is a molded resin 9. In the molding process, the first coil 2 and the second coil 3 are accommodated in a metal mold, and then molten resin is injected and solidified to form the molded resin 9 so as to cover a part of the first coil 2 and the second coil 3. The first coil 2 and the second coil 3 accommodated in the metal mold in the molding process are manufactured through a winding process. The winding process is a process in which the first coil 2 and the second coil 3 are produced by winding the conductive wire 11.

[0021] 2 is a perspective view showing the first coil 2 and the second coil 3 in the winding process. In the winding process, the conductive wire 11 is spirally wound around the winding axis 28 of the first coil 2 and the winding axis 31 of the second coil 3 while shifting the winding position for each turn, thereby producing the first coil 2 and the second coil 3.

[0022] The first coil 2 and the second coil 3 are, for example, spiral edgewise coils. The spiral edgewise coils are formed by winding the rectangular conductive wire 11 so that the wide surface of the conductive wire 11 extends in a direction perpendicular to the winding axes 28, 31. However, there is no limitation on the type of the conductive wire 11, and other types of wires such as round wires may be used. Furthermore, there is no limitation on the winding manner of the first coil 2 and the second coil 3, and the conductive wire may be a flatwise coil so that the wide surface of the conductive wire extends along the winding axes 28, 31.

[0023] A linked coil may be used for the molded coil 1. That is, the first coil 2 and the second coil 3 may be linked coils. The first coil 2 and the second coil 3, which are linked coils, are connected by a linking portion 4. The first coil 2 and the second coil 3 are arranged adjacent to each other so that their winding axes 28, 31 run parallel to each other. The winding axes 28, 31 are preferably parallel or approximately parallel to each other. The first coil 2 and the second coil 3 are arranged parallel to each other with a certain distance therebetween. When the first coil 2 and the second coil 3 are arranged parallel to each other, the winding directions of the first coil 2 and the second coil 3 are the same.

[0024] With respect to the first coil 2, the lead wire 21 is led out from a lead-out end face 22, which is one of the outermost turns of the wound conductive wire 11. The lead-out end face 22 is formed by the outermost turn of the lead-out side of the conductive wire 11, extends perpendicular to the winding axis 28, and is a ring-shaped end face. The surface opposite to the lead-out end face 22 is a connection-side end face 23, from which a connecting portion 4 connected to the second coil 3 extends. This connection-side end face 23 is formed by the outermost turn of the connection side of the conductive wire 11, extends perpendicular to the winding axis 28, and is a ring-shaped end face.

[0025] Between the draw-out side end face 22 and the connection side end face 23 of the first coil 2, the coil is wound into a cylindrical shape with rounded corners. That is, between the draw-out side end face 22 and the connection side end face 23 of the first coil 2, a rectangle is formed by connecting four flat surfaces parallel to the winding axis 28. The corners of each flat surface are curved, and the flat surfaces are connected by curved portions. The four flat surfaces are the heat dissipation surface 27, the top surface 24, the outer surface 25, and the opposing surface 26. Note that the flat surfaces are surfaces that are flat relative to the curved portions, and also include surfaces that form a large arc with a gentle curvature due to the bulging of the conductive wire 11 as it is wound.

[0026] Top surface 24 is an upper flat surface that is pressed by a mold during resin molding, and is parallel to winding axis 28. Heat dissipation surface 27 is a lower flat surface that is exposed, in part or entirely, even after resin molding for heat dissipation, and is parallel to winding axis 28 and located opposite top surface 24. Note that top and bottom refer to the top and bottom when first coil 2 and second coil 3 are housed when first coil 2 and second coil 3 are resin-coated by molding, and do not refer to the positional relationship or direction when molded coil 1 is mounted on the actual device to be installed.

[0027] The opposing surface 26 is a flat surface that faces the second coil 3 and is disposed inside the linked coil, is parallel to the winding axis 28, is adjacent to the top surface 24 and the heat dissipation surface 27, and extends perpendicular to the top surface 24 and the heat dissipation surface 27. The outer surface 25 is a flat surface that faces in the direction away from the second coil 3 and is disposed outside the linked coil, is parallel to the winding axis 28, is adjacent to the top surface 24 and the heat dissipation surface 27, and extends perpendicular to the top surface 24 and the heat dissipation surface 27, and is located opposite the opposing surface 26.

[0028] In such a molded coil 1, the first coil 2, the second coil 3, and the connecting portion 4 are formed by molding a single conductive wire 11. The first coil 2 is formed by winding one side area of ​​the single conductive wire 11. The second coil 3 is formed by winding the other side area of ​​the single conductive wire 11. The connecting portion 4 is formed between the first coil 2 and the second coil 3 of the single conductive wire 11.

[0029] The conductive wire 11 is made longer in advance to absorb wire feed errors during the formation of the first coil 2 and the second coil 3. The juxtaposed positions of the first coil 2 and the second coil 3 are adjusted using the excess length of the conductive wire 11. The remainder after absorbing wire feed errors during the formation of the first coil 2 and the second coil 3 becomes the offset portion 51 of the first coil 2.

[0030] The offset portion 51 is formed on the connecting side end surface 23. In other words, a portion of the outermost turn that forms the connecting side end surface 23 is wound so as to bulge outward more than the other turns, causing the offset portion 51 to protrude from the first coil 2. In this manner, the circumferential length of the outermost turn that forms the connecting side end surface 23 is increased, thereby absorbing the excess of the conductive wire 11.

[0031] The offset portion 51 is caused to protrude outward from the outer surface 25 of the first coil 2. Specifically, the offset portion 51 is caused to extend from the lower outer end 52 of the first coil 2 along the plane in which the connecting side end face 23 extends, in a direction perpendicular to the outer surface 25. The offset portion 51 extending from the lower outer end 52 is bent so as to extend along the outer surface 25. The straight portion 54 of the offset portion 51 is caused to extend parallel to the outer surface 25 while protruding outward from the outer surface 25. The straight portion 54 extends along the outer surface 25 while protruding outward from the outer surface 25 until it reaches the same height as the upper outer end 53. The offset portion 51 that has reached the same height as the upper outer end 53 is bent toward the upper outer end 53. Then, the offset portion 51 reaches the upper outer end 53.

[0032] In this way, the straight portion 54 of the offset portion 51 extends along the outer surface 25 while protruding from the outer surface 25. In other words, the offset portion 51 does not protrude from the top surface 24 and the heat dissipation surface 27. The top surface 24 and the heat dissipation surface 27 are flat and do not have the offset portion 51 protruding from the pull-out side end surface 22 to the connection side end surface 23, except for manufacturing variations between turns. Therefore, the molded coil 1 has a low profile in the size perpendicular to the top surface 24 and the heat dissipation surface 27.

[0033] Fig. 3 is an exploded view of the molded coil 1 showing the cover installation process. As shown in Fig. 3, in addition to the molded resin 9, the coating resin 6 includes a top cover 61, an extraction side end cover 62, an inner peripheral cylinder 63, side covers 64, 66, a connection side end cover 65, and an inner contact wall 67. Before the molding process, the process moves to a cover installation process, and the components other than the molded resin 9 are attached to the first coil 2 and the second coil 3 that have been through the winding process.

[0034] The top cover 61, the pull-out side end cover 62, the inner cylinder 63, the side covers 64, 66, the connection side end cover 65 and the inner contact wall 67 are insulating members that are preformed and have a fixed shape before covering the first coil 2 and the second coil 3. Examples of insulating members include epoxy resin, unsaturated polyester resin, urethane resin, BMC (Bulk Molding Compound), PPS (Polyphenylene Sulfide), PBT (Polybutylene Terephthalate), or a composite of these, and a thermally conductive filler may be mixed in.

[0035] Top cover 61 is placed on top surface 24 of first coil 2, and covers part or all of this top surface 24. When top surface 24 is pressed with a die for molding resin 9 to correct unevenness on top surface 24, top cover 61 is interposed between the die and top surface 24 to protect top surface 24. A cover similar to top cover 61 is also attached to second coil 3. Top covers 61 of first coil 2 and second coil 3 may be integrally molded products that are continuously connected without seams.

[0036] The pull-out side end cover 62, the inner peripheral cylinder 63 and the side cover 64 are a seamless integrally molded product. The pull-out side end cover 62 is a ring-shaped plate that encompasses the pull-out side end face 22 of the first coil 2. The inner peripheral cylinder 63 is a cylindrical body whose outer diameter matches the inner peripheral shape of the first coil 2. The side cover 64 is a plate that covers part or all of the outer surface 25 of the first coil 2.

[0037] This pull-out side end cover 62 abuts against the pull-out side end face 22, covering part or all of the pull-out side end face 22. The inner peripheral tube 63 is inserted into the inner circumference of the first coil 2, covering the inner peripheral surface of the first coil 2. The side cover 64 extends from the edge of the pull-out side end face 22 of the first coil 2 towards the opposite connecting side end face 23, covering part of the outer surface 25. However, the side cover 64 does not reach the connecting side end face 23. A cover similar to the pull-out side end cover 62, inner peripheral tube 63 and side cover 64 is also attached to the second coil 3.

[0038] The connection side end cover 65, side cover 66 and inner abutment wall 67 are a seamless integrally molded product. The connection side end cover 65 is a ring-shaped plate that encompasses the connection side end face 23 of the first coil 2. The side cover 66 is a plate that covers all or part of the outer surface 25 of the first coil 2. The inner abutment wall 67 is a wall that fits between the first coil 2 and the second coil 3. It covers the opposing surfaces 26 of the first coil 2 and the second coil 3.

[0039] The connection side end face cover 65 abuts against the connection side end face 23, covering part or all of the connection side end face 23. The inner abutment wall 67 is inserted between the first coil 2 and the second coil 3, covering the opposing faces 26 of the first coil 2 and the second coil 3. The side cover 66 extends from the edge of the connection side end face 23 of the first coil 2 towards the opposite pull-out side end face 22, and covers part of the outer surface 25. However, the side cover 66 does not reach the pull-out side end face 22.

[0040] The total length of the side cover 64 and the side cover 66 is longer than the distance between the pull-out side end face 22 and the connection side end face 23 of the first coil 2. One of the side cover 64 and the side cover 66 has an insertion plate 69a extending along the winding shaft 28, and the other of the side cover 64 and the side cover 66 has a pocket portion 69b. The opening of the pocket portion 69b is designed so that the insertion plate 69a can be inserted into it, and the pocket portion 69b is deep along the winding shaft 28. When the side cover 64 and the side cover 66 are arranged, the insertion plate 69a is brought into contact with the outer surface 25, and the pocket portion 69b is placed over the insertion plate 69a.

[0041] A cover similar to the connecting side end cover 65, side cover 66 and inner abutment wall 67 is also attached to the second coil 3, but this cover may be molded integrally with the connecting side end cover 65, side cover 66 and inner abutment wall 67 of the first coil 2.

[0042] Fig. 4 is a perspective view showing the first coil 2 with the cover attached in the cover installation process. Fig. 5 is a side view showing the first coil 2 with the cover attached in the cover installation process. As shown in Figs. 4 and 5, an offset cover 7 is formed at the boundary between the connecting side end cover 65 and the side cover 66. The offset cover 7 is an integrally molded product that is seamlessly connected to the connecting side end cover 65 and the side cover 66.

[0043] The offset cover 7 encloses the straight portion 54 of the offset part 51. In other words, the offset cover 7 is a U-shaped pillar that abuts against the front edge, side and back edge of the straight portion 54, and is formed along the side edge of the connecting side end face 23. The offset cover 7 protrudes outward beyond the side cover 66.

[0044] The offset cover 7 prevents resin from leaking out from around the offset portion 51 onto the heat dissipation surface 27 during molding. Therefore, the lower end 71 of the offset cover 7 is lowered to the vicinity of the heat dissipation surface 27. If the path toward the heat dissipation surface 27 is long, resin is less likely to leak, so the offset cover 7 should be extended upwards. The offset cover 7 encloses the offset portion 51 at least up to above the straight portion 54.

[0045] A protrusion 8 extends from the lower end of the offset cover 7. When viewed from a direction perpendicular to the outer surface 25 with the pull-out side end face 22 on the left and the connection side end face 23 on the right, the offset cover 7 and the protrusion 8 form an inverted L shape. That is, the protrusion 8 protrudes outward from the side cover 66 and extends from the lower end of the offset cover 7 to a tip 81 along the winding shaft 28 toward the pull-out side end face 22. The length of the protrusion 8 is equal to or greater than the maximum compression distance of the first coil 2 described below. A heat-dissipating side lower surface 82 of the protrusion 8 forms a boundary with the heat-dissipating surface 27. An upper surface 83 of the protrusion 8 is flat so that an object can slide relatively thereon.

[0046] Fig. 6 is a front view showing the coils placed in a metal mold in the molding process. For convenience of explanation, the upper mold is omitted in Fig. 6. As shown in Fig. 6, after the cover installation process, the first coil 2 and the second coil 3 are housed in a metal mold for forming a molding resin 9.

[0047] In the mold, the first coil 2 and the second coil 3 are pressed down by an upper die (not shown) via an upper cover 61. Here, the offset portion 51 protrudes outward from the outer surface 25, and there is no protrusion on the upper surface 24 from the drawing-side end surface 22 to the connecting-side end surface 23. Therefore, the upper die covers the entire area of ​​the first coil 2 from the edge surface of the drawing-side end surface 22 to the edge surface of the connecting-side end surface 23. Therefore, unevenness in the first coil 2 is corrected over the entire area.

[0048] The connecting side end cover 65 has a notch 68 formed by cutting out a part of the side edge below the offset cover 7. In addition, in the mold for molding, the lower die ML has a shape that matches the notch 68, and the notch 68 and the lower die ML fit together. The lower die ML and the notch 68 are tightly attached to each other by the reaction force generated when the upper die presses the first coil 2 from above. Therefore, leakage of resin from the lower end of the connecting side end cover 65 to the heat dissipation surface 27 during molding is suppressed.

[0049] Fig. 7 is a perspective view showing a state in which the slide die MS is arranged in the molding process. Fig. 8 is a side view showing a state in which the slide die MS is arranged in the molding process. In Figs. 7 and 8, the lower die ML on the offset portion 51 side is omitted for convenience of explanation. As shown in Figs. 7 and 8, in the die for molding, the first coil 2 and the second coil 3 are pressed from the outer surface 25 side by the slide die MS.

[0050] The slide mold MS presses the entire side cover 64 integrated with the pull-out side end face cover 62 and a part of the side cover 66 integrated with the offset portion 51 against the outer surface 25 of the first coil 2. The side cover 64 and the side cover 66 are in close contact with the outer surface 25, thereby preventing the molten resin injected into the mold from flowing along the surface of the outer surface 25 and onto the heat dissipation surface 27.

[0051] Depending on the winding accuracy of the first coil 2 and the second coil 3, the first coil 2 and the second coil 3 may deviate from the final dimensional tolerance and become too long, which may cause problems when assembled into a reactor, problems when mounted on a circuit, or gaps between turns that may cause resin leakage. On the other hand, in the winding process, the first coil 2 and the second coil 3 may be intentionally made longer so that they do not deviate from the final dimensional tolerance and become too short. Therefore, in the mold for molding, the first coil 2 and the second coil 3 are pressed along the winding axes 28 and 31, and the lengths of the first coil 2 and the second coil 3 along the winding axes 28 and 31 are adjusted by compression, with the maximum compression distance possible by the manufacturing device as the limit.

[0052] To compress the first coil 2, one of the pull-out side end cover 62 and the connecting side end cover 65 is fixed and pressure is applied to the other. The pressure is generated by the injection pressure of the molten resin that becomes the molded resin 9, by pressing with a pressing rod, or by both. When the first coil 2 is compressed, the connecting side end cover 65, the side cover 66, and the offset cover 7 also move relatively closer to the pull-out side end face 22.

[0053] In order to prevent the offset cover 7 from colliding with the slide mold MS during compression of the first coil 2, making it impossible to compress the first coil 2, when the first coil 2 that needs to be compressed is contained within the mold, a distance is maintained between the offset cover 7 and the offset opposing surface MS1 of the slide mold MS.

[0054] In this manner, inside the mold, unevenness on the surfaces of the first coil 2 and the second coil 3 is corrected, and the first coil 2 and the second coil 3 are compressed while the molten resin is injected to form the molding resin 9. At this time, in order to compress the first coil 2, a gap 93 extending toward the heat dissipation surface 27 is generated between the offset cover 7 and the offset opposing surface MS1 of the slide mold MS.

[0055] However, side cover 66 has protrusion 8, one end of which is connected to offset cover 7, and tip 81 of protrusion 8 extends until it comes into contact with heat-dissipating bottom surface MS2 of slide die MS. Therefore, the path passing between offset cover 7 and offset opposing surface MS1 of slide die MS and out to heat dissipation surface 27 is blocked by protrusion 8. Therefore, even for first coil 2 which has offset portion 51 protruding outward beyond outer surface 25 and which is compressed along winding shaft 28 within the die, resin leakage to heat dissipation surface 27 is suppressed.

[0056] This protrusion 8 slides on the heat dissipation side bottom surface MS2 of the slide die MS, and therefore always closes the gap 93 facing the heat dissipation surface 27 when the first coil 2 is compressed. Therefore, as shown in Fig. 9, which is a side view showing the state in which the resin has flowed in during the molding process, the protrusion 8 blocks the molten resin that has flowed into the gap 93, and a columnar portion 91 is formed between the offset opposing surface MS1 of the slide die MS and the offset cover 7.

[0057] Fig. 10 is a side view showing the state after the molded resin is formed in the molding process. As shown in Fig. 10, the columnar portion 91 is a part of the molded resin 9, and extends until the tip 92 hits the protrusion 8 while contacting the offset cover 7. The width of the columnar portion 91 from the offset cover 7 as the starting point does not reach the tip 81 of the protrusion 8.

[0058] As described above, the molded coil 1 is manufactured including the winding process, the cover installation process, and the molding process. In the winding process, the first coil 2 is wound while forming the offset portion 51 on the connecting side end face 23, the offset portion 51 protruding outward from the outer side face 25 adjacent to the heat dissipation surface 27 to be exposed from the coating resin 6. In the cover installation process, the outer side face 25 from which the offset portion 51 protrudes is covered with the side cover 66, and the connecting side end face 23 is covered with the connecting side end face cover 65 integrally molded with the side cover 66. In the molding process, the side cover 66 is pressed against the outer side face 25 by the slide mold MS, and resin is injected into the mold while compressing the first coil 2 in the winding axis direction via the connecting side end face cover 65.

[0059] The connecting side end face cover 65 has an offset cover 7 at the boundary with the side cover 66, which protrudes outward from the side cover 66 and encloses the offset portion 51. In this case, the side cover 66 has a protrusion 8 that protrudes from the surface of the side cover 66 until one end is connected to the offset cover 7 and the other end contacts the heat radiation side bottom surface MS2 of the slide die MS.

[0060] In such a manufacturing method that involves a winding process, a cover installation process, and a molding process, in order to make the first coil 2 compressible, a gap 93 extending toward the heat dissipation surface 27 is created between the slide mold MS and the offset cover 7. However, since the protrusion 8 blocks the path to the heat dissipation surface 27, it is possible to prevent resin from leaking onto the heat dissipation surface 27, thereby improving the heat dissipation properties of the molded coil 1.

[0061] That is, the offset cover 7 is positioned at a distance from the slide mold MS before compression, and moves closer to the slide mold MS as it is compressed. The resin injected into the mold climbs over the side cover 66 and flows into between the offset cover 7 and the slide mold MS. However, the protrusion 8 slides on the heat dissipation side bottom surface MS2 of the slide mold MS as it is compressed, blocking the path to the heat dissipation surface 27 between the slide mold MS and the offset cover 7.

[0062] As a result, the coating resin 6 has a side cover 66 that covers the outer surface 25 from which the offset portion 51 protrudes, a connecting side end face cover 65 that is molded integrally with the side cover 66 and covers the connecting side end face 23 having the offset portion 51, an offset cover 7 that is formed at the boundary between the connecting side end face cover 65 and the side cover 66, protrudes outward beyond the side cover 66 and covers the offset portion 51, and a protrusion 8 that protrudes from the surface of the side cover 66, extends along the winding axis of the first coil 2, and has one end connected to the offset cover 7.

[0063] In addition, the coating resin 6 extends until it hits the protrusion 8 while contacting the offset cover 7, and a columnar portion 91 of the molding resin 9 is created whose width starting from the offset cover 7 does not reach the tip 81 of the protrusion 8.

[0064] The first coil 2 and the second coil 3 may not be connected coils, but may be independent of each other. In order to adjust the pull-out position of the pull-out wire 21, an offset portion 51 may be formed in the first coil 2. In such a first coil 2, the offset portion 51 is formed in the pull-out side end surface 22, and an offset cover 7 is provided on the pull-out side end surface cover 62 that covers the pull-out side end surface 22. A distance is provided between the offset cover 7 on the pull-out side end surface cover 62 side and the slide mold MS, and the offset cover 7 is raised on the side cover 64 to form a protrusion 8. This also makes it possible to close the gap 93 between the offset cover 7 on the pull-out side end surface cover 62 side and the slide mold MS, and to suppress resin leakage to the heat dissipation surface 27.

[0065] Furthermore, if the first coil 2 and the second coil 3 are not connected coils but are independent of each other, the coating resin 6 that coats the second coil 3 may also be provided with an offset cover 7 and a protrusion 8 to block the gap 93 leading toward the heat dissipation surface 27 of the second coil 3.

[0066] In addition, the first coil 2 and the second coil 3 are formed in a rounded cylindrical shape, but may be formed in a rectangular or cylindrical shape. In the case of being formed in a cylindrical shape, the upper surface 24 refers to the area facing the heat dissipation surface 27, and the outer surface 25 and the facing surface 26 refer to the area sandwiched between the upper surface 24 and the heat dissipation surface 27.

[0067] FIG. 11 is a perspective view of the reactor 100. The above molded coil 1 is attached to a core in an assembly process during the manufacturing process of the reactor 100, and constitutes the reactor 100 together with the core 110. The core 110 includes a magnetic body such as a dust core, a ferrite core, a metal composite core, or a laminated steel plate. The dust core is a powder compact obtained by annealing a powder compact obtained by compressing magnetic powder. 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), and a mixed powder of two or more of these powders. The magnetic powder may be an amorphous alloy or a nanocrystalline alloy powder. The metal composite core is a core formed by kneading and molding a magnetic powder and a resin.

[0068] The core 110 may have a ring shape, and the magnetic material may be distributed in a ring shape without interruption. A magnetic gap for preventing a decrease in inductance may be provided in the middle of the core 110. The magnetic gap may be made of a non-magnetic material, ceramic, non-metal, resin, carbon fiber, or a composite material of two or more of these, gap paper, or an air gap.

[0069] 12 is a perspective view of reactor 100 including secondary molded resin 120. Reactor 100 may include secondary molded resin 120, and molded coil 1 and core 110 may be covered with secondary molded resin 120 except for heat dissipation surface 27.

[0070] The above-mentioned embodiment of the present invention is presented as an example, and is not limited to the above-mentioned embodiment. The above-mentioned embodiment can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the scope of the invention. The embodiment and its modifications are included in the scope of the present invention. [Explanation of symbols]

[0071] 1 Molded coil 11 Conductive wire 2. First coil 21 Leader 22 Drawer side end face 23 Connection side end face 24 Top side 25 External surface 26 Opposite Surface 27 Heat radiation surface 28 Roll 3 Second coil 31 Reel 4 Connecting part 51 Offset section 52 Lower outer edge 53 Upper outer edge 54 Straight section 6. Coating resin 61 Top cover 62 Drawer side end cover 63 Inner cylinder 64 Side cover 65 Connection side end cover 66 Side cover 67 Inner abutment wall 68 Notch 69a Insertion plate 69b Pocket 7 Offset Cover 71 Bottom end 8 Protrusion 81 Tip 82 Lower surface of heat radiation side 83 Top surface 9. Mold Resin 91 Columnar part 92 Tip 93 Gap 100 Reactor 110 cores 120 Secondary molding resin MS Slide Mold MS1 offset facing surface MS2 Heat dissipation bottom surface ML lower mold

Claims

1. A method for manufacturing a molded coil having a heat dissipation surface exposed from a coating resin along a winding axis, comprising the steps of: a winding process for winding the coil while forming an offset portion on at least one end face perpendicular to the winding axis, the offset portion being adjacent to the heat dissipation surface and extending along the winding axis and extending outward from the one side face; a cover installation process for covering the side surface from which the offset portion protrudes with a side cover and covering the end surface having the offset portion with an end surface cover integrally molded with the side cover; a molding process in which the side cover is pressed against the side surface by a slide die, and the coil is compressed in the winding axis direction via the end face cover while injecting resin into the die; having the end surface cover has an offset cover at a boundary with the side surface cover, the offset cover protruding outward from the side surface cover and enclosing the offset portion, the side cover has a protrusion extending from a surface of the side cover until one end of the side cover is connected to the offset cover and the other end of the side cover contacts the bottom surface of the slide die; A method for manufacturing a molded coil, comprising the steps of:

2. The offset cover is positioned at a distance from the slide die before the compression, and approaches the slide die in response to the compression, The resin injected into the mold passes over the side cover and flows into the gap between the offset cover and the slide mold, the protrusion portion, while sliding on a bottom surface of the slide die in response to the compression during the molding process, blocks a path to the heat dissipation surface between the slide die and the offset cover; 2. The method for producing a molded coil according to claim 1, further comprising the steps of:

3. 3. The method of claim 1, further comprising the step of assembling the molded coil to a core including a magnetic body after the molded coil is manufactured by the method of claim 1 or 2. A method for manufacturing a reactor, comprising the steps of:

4. A coil which is a wound body of conductive wire; A coating resin that covers the surface of the coil; Equipped with The coil is a heat dissipation surface extending along the winding axis and exposed from the coating resin; one side surface extending along the winding axis and adjacent to the heat dissipation surface; an end surface perpendicular to the winding axis; an offset portion formed on at least one of the end faces and protruding outward from the side face; having The coating resin is a side cover that covers the side surface from which the offset portion protrudes; an end face cover that is integrally formed with the side cover and covers the end face having the offset portion; an offset cover formed at a boundary between the end face cover and the side cover, protruding outward beyond the side cover, and covering the offset portion; a protrusion portion that protrudes from a surface of the side cover, extends along the winding axis of the coil, and has one end connected to the offset cover; having A molded coil characterized by:

5. The coating resin extends until it hits the protrusion while contacting the offset cover, and the width of the coating resin from the offset cover to the tip of the protrusion does not reach the tip of the protrusion. having 5. The molded coil according to claim 4, wherein

6. A molded coil according to claim 4 or 5, a core including a magnetic material and to which the molded coil is attached; A reactor comprising:

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