JP7699441B2 - Reactor - Google Patents

Description

The present invention relates to a reactor having a core and a coil.

A reactor mainly consists of a coil and a core. When electricity is passed through the coil, it generates magnetic flux according to the number of turns. The core acts as a closed magnetic circuit that allows the magnetic flux generated by the coil to pass through with a magnetic permeability higher than that of a vacuum. In other words, a reactor is an electromagnetic component that converts electrical energy into magnetic energy and stores and releases it.

Such reactors are used in a wide variety of applications. Representative reactors include boost reactors, series reactors, parallel reactors, current limiting reactors, starting reactors, shunt reactors, neutral point reactors, and arc suppression reactors.

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 to 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 and are connected to them. Starting reactors are connected in series to motor circuits that protect the machine and limit the starting current. Shunt reactors are connected in parallel to 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.

The core is formed by connecting multiple core blocks in a ring shape, and each core block may be individually covered with a core coating resin by molding it with resin (see, for example, Patent Document 1). When molding the core block with resin, both end faces of the core block are expected to be abutted against a metal mold.

However, due to manufacturing errors in the core block, there is a risk that the end face of the core block will not reach the mold by a small amount. If the end face of the core block does not reach the mold, pieces of resin will appear on the end face of the core block in places that were not intended to be covered with resin, known as burrs. If these burrs appear, an additional manufacturing process will be required to remove the burrs, which increases the number of manufacturing steps.

Therefore, a reactor has been proposed in which the end faces of the core block are also covered with core coating resin (see, for example, Patent Document 2). If the end faces of the core block are also covered with resin and the thickness of the resin covering the end faces is designed to be a gap, the process of removing burrs itself becomes unnecessary. Reducing the exposure of the core block also has the effect of reducing noise caused by magnetostriction of the core.

JP 2010-238798 A Patent No. 5951969

When molding a core block with resin, in order to hold the core block within the mold, it is not possible to completely mold the entire end face of the core block with resin, and a contact point that is supported by the mold is required on part of the end face of the core block. At this contact point, a hole is formed in the core coating resin.

Because this hole is an undercut, at least three types of dies are required to mold the core block with resin: an upper die that faces one of the sides perpendicular to the end face of the core block, a lower die positioned opposite the upper die, and a slide die that can move in a direction away from the end face of the core block. This increases the manufacturing cost of the reactor, and the more complex the dies are, the greater the manufacturing error of the reactor will be, which may result in a decrease in yield.

The present invention has been proposed to solve the above problems, and its purpose is to provide a reactor that does not require a slide die that can move in a direction away from the end face of the core block.

In order to achieve the above object, a reactor according to an embodiment of the present invention comprises a plurality of core blocks, a plurality of core coating resins that individually coat each of the core blocks, a core that forms a ring-shaped closed magnetic circuit by combining the core blocks coated with the core coating resin, and a coil that is attached to the core blocks from above the core coating resin, and the core coating resin has a resin end face that coats the end face of the core block, and the resin end face has a notch that extends from the face center side of the resin end face toward the face edge, cutting the face edge, exposing the end face of the core block, and has an opening on the resin side that is perpendicular to the resin end face.

The core coating resin may have a hole that exposes the core block at a position directly opposite the notch in a direction perpendicular to the resin end face.

A second resin may be provided to integrally cover the coil and the core, and the second resin may flow from the opening into the notch and solidify.

The notch may have a tapered shape that gradually widens from the center of the resin end face toward the edge of the face.

The core coating resin may cover one end face of the core block with the resin end face having the notch, and cover the side of the core block until it is flush with the other end face of the core block, exposing the entire other end face.

The core block may be a single, seamless block, a composite of smaller blocks, or a composite of smaller blocks with gaps between them.

According to the present invention, the die can be removed from the center of the resin end face of the core coating resin toward the edge of the face, eliminating the need for a slide die that can move away from the end face of the core block.

FIG. 2 is a perspective view of the reactor with the resin omitted. FIG. FIG. FIG. 2 is a perspective view of an end surface side of a core coating resin. FIG. 2 is a rear perspective view of the core coating resin. 1A and 1B are diagrams showing the transition of molding a core-coating resin, in which FIG. 1A shows the injection molding stage and FIG. 1B shows the mold release stage. FIG. 11 is a perspective view showing a reactor in which a second resin is formed. FIG. 4 is a perspective view showing the core-coating resin when the second resin is being injection molded.

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 10 has one annular core 1 and two coils 2, 2. The two coils 2, 2 are fitted side-by-side into one core 1. When current is passed through the coils 2, 2, 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 2, 2 with a magnetic permeability higher than that of a vacuum. In other words, the reactor 10 is an electromagnetic component that converts electrical energy into magnetic energy and stores and releases it.

The two coils 2, 2 are formed as linked coils made by winding two separate points of a single conductive wire 21, such as a copper wire, separately without separating them. Each coil 2 is formed by winding the conductive wire 21 in a spiral shape while shifting the winding position for each turn along the winding axis. The two coils 2, 2 are arranged side by side with their axes parallel to each other and with the currents flowing through the two coils 2, 2 in opposite directions. When the two coils 2 are arranged side by side, the winding directions of the two coils 2, 2 are the same.

The wire in one conductive wire 21 at the end closer to the coils 2, 2 is pulled out from one end face of each coil 2. The pulled out conductive wire 21 is connected to an electric circuit, allowing electricity to flow through the coils 2. In addition, the wire between the coils 2, 2 in one conductive wire 21 forms a connecting wire 22 that connects the two coils 2, 2.

Figure 2 is a perspective view of the core 1, and Figure 3 is an exploded view of the core 1. The core 1 is formed by linking core blocks 3 in a ring shape. Each core block 3 has various shapes, such as U-shaped, linear, J-shaped, or E-shaped, and is linked in a ring shape by, for example, combining two U-shaped core blocks 3 facing each other, combining two J-shaped core blocks 3 arranged in a point-symmetric relationship, combining two E-shaped core blocks 3 facing each other, or combining a pair of U-shaped, J-shaped, or E-shaped core blocks 3 with a linear shape included between them.

Each core block 3 is a seamless integrally molded magnetic body, a composite in which smaller magnetic body blocks are connected with adhesive, or a composite in which gaps are inserted between smaller magnetic body blocks. The magnetic body may be, for example, a dust core, a ferrite core, a metal composite core, or a laminated steel plate. The dust core is made by annealing a powder compact made by compressing magnetic powder. The magnetic powder is mainly composed of iron, and examples of the 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, or a mixture of two or more of these powders. The metal composite core is made by kneading and molding magnetic powder and resin.

Each core block 3 is individually coated with core coating resin 4 to electrically insulate it from the coil 2, and then connected in a ring shape. The core coating resin 4 is a molded product that maintains a certain shape and has insulating and heat resistance properties. Materials for the core coating resin 4 include epoxy resin, unsaturated polyester resin, urethane resin, BMC (Bulk Molding Compound), PPS (Polyphenyl Sulfide), PBT (Polybutylene Terephthalate), or a composite of these, and a thermally conductive filler may be mixed in.

The core coating resin 4 is molded to cover the core block 3 by placing the core block 3 individually in a mold and injecting the resin. Within the mold, each core coating resin 4 not only covers the periphery of the core block 3, but also the first block end face 31, which is one end face of the core block 3 through which magnetic flux passes. In other words, each core coating resin 4 has not only a resin side surface 42 that covers the periphery of the core block 3, but also a resin end face 41 that covers the first block end face 31.

The second block end face 32, which is the other end face of the core block 3 through which the magnetic flux passes, is exposed from the core coating resin 4. This exposure is formed by the resin side face 42 extending until it is flush with the second block end face 32 of the core block 3. On the other hand, the resin end face 41 covers the first block end face 31 of the core block 3 in a continuous manner with no seams connected to the resin side face 42.

When two core blocks 3 coated with core coating resin 4 are joined together, a ring-shaped core 1 is formed by connecting the resin end face 41 of the core coating resin 4 coating one core block 3 with the second block end face 32 exposed from the core coating resin 4 of the other core block 3. Therefore, the resin end face 41 coating the first block end face 31 of the core block 3 is closely attached to and covered by the second block end face 32 of the core block 3.

Figure 4 is an oblique view of the end face side of the core coating resin 4. As shown in Figure 4, a notch 5 is formed in this resin end face 41. The notch 5 is a rectangular hole that extends from the center side of the surface of the resin end face 41 toward the surface edge, cutting the surface edge. The notch 5 penetrates the front and back of the resin end face 41, exposing a part of the first block end face 31 of the core block 3. Since the notch 5 cuts the surface edge of one side of the resin end face 41, the resin side face 42 adjacent to the resin end face 41 with the cut-out surface edge as the boundary has an opening 51 that leads into the notch 5.

Figure 5 is a rear perspective view of the core coating resin 4. When the core block 3 is U-shaped or J-shaped, the core coating resin 4 has a resin rear surface 43, which is the surface directly opposite the resin end surface 41. The resin rear surface 43 covers the yoke portion of the U-shaped or J-shaped core block 3. In this resin rear surface 43, a hole 6 opens at a position directly opposite the notch 5 in a direction perpendicular to the resin end surface 41, exposing the core block 3.

Figure 6 shows the molding process of the core coating resin 4 of this shape, where (a) shows the injection molding process and (b) shows the mold release process. This Figure 6 shows the molding process in a plan view of the U-shaped core block 3 as seen from a direction perpendicular to the resin end surface 41, where the core block 3 is projected onto a rectangle.

As shown in FIG. 6(a), the core block 3 is housed in an enclosed space defined by a lower die K1, an upper die K2, and a block back support die K3. The lower die K1 supports the surface of the U-shaped core block 3 where the U-shape is visible, and the upper die K2 presses against the core block 3 from a position directly opposite the lower die K1. The block back support die K3 slides toward and away from the position and range where the hole 6 of the core block 3 is to be formed, and presses against the core block 3.

The lower die K1 is equipped with a first block end face support piece K11. The first block end face support piece K11 is pressed against the first block end face 31 of the core block 3 at the position and range of the notch 5. The block back face support die K3 extends to a position directly opposite the first block end face support piece K11 and is pressed against the core block 3 at the position and range of the hole portion 6. The core block 3 is clamped by this first block end face support piece K11 and the block back face support die K3.

The lower die K1 also has a support piece that is in pressure contact with the entire second block end face 32. The upper die K2 may have this support piece that is in pressure contact with the second block end face 32. The lower die K1 also supports the core block 3 from below, and is supported from below by an ejection pin for releasing the core block 3 on which the core coating resin 4 has been formed from the lower die 1.

As shown in FIG. 6(b), when resin is injected into the mold and the core coating resin 4 is formed on the core block 3, the core block 3 is released from the lower mold K1, the upper mold K2, and the block back support mold K3. Since the notch 5 is not an undercut surrounded entirely by resin, the core block 3 with the core coating resin 4 formed thereon can be pushed out of the lower mold K1 along the direction in which the first block end face support piece K11 extends.

In this way, the notch 5 extends from the center of the resin end face 41 toward the edge of the face, cutting the edge, so that it does not form an undercut. Therefore, the first block end face support piece K11 that supports the first block end face 31 can be extended from the lower mold K1. In this way, in the process of forming this core coating resin 4, it is not necessary to separately prepare a slide mold that moves in and out in a direction perpendicular to the first block end face 31.

Figure 7 is a perspective view showing a reactor 10 in which a second resin 8 is formed. As shown in Figure 7, the core 1, which is made up of a series of core blocks 3 coated with a core coating resin 4, and the coil 2 are molded and integrated with the second resin 8. Like the core coating resin 4, this second resin 8 is also a molded product that retains a certain shape and has insulating properties and heat resistance.

The material of the second resin 8 may be epoxy resin, unsaturated polyester resin, urethane resin, BMC (Bulk Molding Compound), PPS (Polyphenyl Sulfide), PBT (Polybutylene Terephthalate), or a combination of these, and may contain a thermally conductive filler. The core coating resin 4 and the second resin 8 may be made of different materials.

Figure 8 is a perspective view showing the core coating resin 4 when the second resin 8 is being injection molded. For convenience of explanation, the adjacent core coating resin 4 is omitted in Figure 8, but the resin end surface 41 in which the notch 5 is formed is connected over the entire area to the second block end surface 32 of the core block 3 coated with the other core coating resin 4, and the notch 5 is covered from a direction perpendicular to the resin end surface 41.

However, the notch 5 extends from the center of the resin end face 41 toward the edge of the face, cutting the edge. Therefore, an opening 51 that communicates with the notch 5 is generated on the resin side face 42 that is continuous with the resin end face 41 across the edge cut by the notch 5. Therefore, when the second resin 8 is also filled in the space between the inner peripheral surface of the core 1 and the outer surface of the core 1, the second resin 8 flows in from the opening 51, fills the notch 5, and solidifies. In addition, when the first block end face 31 is pressed by another core coating resin 4, air is easily released from the opening 51. Therefore, air escapes from the notch 5, and the notch 5 becomes solid with the second resin 8.

If air remains in the notch 5, heat will be trapped inside the notch 5 due to the low thermal conductivity of air, but since the notch 5 is filled with the second resin 8, the heat inside the notch 5 can be released.

As described above, the reactor 10 includes a plurality of core blocks 3, a plurality of core coating resins 4 that individually coat each of the core blocks 3, a core 1 that is formed by combining the core blocks 3 coated with the core coating resin 4 to form a ring-shaped closed magnetic circuit, and a coil 2 that is attached to the core blocks 3 from above the core coating resin 4. The core coating resin 4 has a resin end face 41 that coats the first block end face 31 of the core block 3. This resin end face 41 is formed with a notch 5. The notch 5 extends from the face center side of the resin end face 41 toward the face edge, cutting through the face edge, exposing the first block end face 31 of the core block 3, and has an opening 51 in the resin side face 42 that is perpendicular to the resin end face 41.

As a result, when the core coating resin 4 is molded, the notch 5 does not become an undercut, and the first block end face support piece K11 that supports the first block end face 31 of the core block 3 can be extended from the lower mold K1. Therefore, even if the first block end face 31 is covered with the resin end face 41, there is no need to prepare a slide mold or the like, and the reactor 10 can be manufactured inexpensively and with high precision.

The core coating resin 4 also has a hole 6 that exposes the core block 3 at a position directly opposite the notch 5 in the direction perpendicular to the resin end surface 41. This allows the core block 3 to be stably installed in the mold against the injection pressure of the core coating resin 4, and allows the core block 3 to be coated with the core coating resin 4 with high precision.

The coil 2 and the core 1 are integrally coated with a second resin 8, which flows from the opening 51 into the notch 5 and solidifies. This prevents air from remaining in the notch 5, and increases the thermal conductivity in the notch 5.

Note that this embodiment is presented as an example, and is not limited to the above embodiment. The above 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 embodiments and their modifications are included within the scope of the present invention.

For example, if the notch 5 is provided, the two coils 2, 2 can be manufactured separately and attached to the reactor 10 instead of being connected coils, thereby reducing the cost of the mold and preventing the mold from becoming more complicated, and allowing the reactor 10 to be manufactured inexpensively and with high precision. Also, three or more coils 2, 2, 2 can be mounted on one core 1 side by side.

The notch 5 may have a tapered shape that gradually widens from the center of the resin end surface 41 toward the edge of the surface. The tapered shape guides the second resin 8 into the notch 5, so that the second resin 8 flows sufficiently into the notch 5, making it easier to prevent voids from remaining in the notch 5. The second resin 8 may be injection molded by placing an assembly of the core block 3 and the coil 2 covered with the core coating resin 4 in a mold, or it may be a filler that is filled in the case of the reactor 10, which contains the assembly in the case.

The first block end face 31 is provided by a first block end face support piece K11 provided on the lower die K1 in the mold. This is not limiting, and the first block end face support piece K11 may be provided on the upper die K2. When the first block end face support piece K11 is provided on the upper die K2, the notch 5 extends from the face center side of the first block end face 31 toward the face edge on the upper die K2 side, and cuts off this face edge.

Preferably, the first block end face support piece K11 is provided on the lower die K1, and the notch 5 extends from the face center side of the first block end face 31 toward the face edge on the lower die K1 side, and is formed so as to cut this face edge. When forming the notch 5 extending toward the lower die K1 side, the alignment of the first block end face support piece K11 and the first block end face 31 can be completed at the same time as the core block 3 is installed on the lower die K1. On the other hand, when the first block end face support piece K11 is provided on the upper die K2, the first block end face support piece K11 descends toward the core block 3 when the upper die K2 and the lower die K1 are closed, so that the positions of the lower die K1 and the core block 3 must be adjusted in advance so that the first block end face support piece K11 does not collide with the core block 3. Therefore, when the first block end face support piece K11 is provided on the lower die K1, the productivity of the reactor 10 is improved compared to when it is provided on the upper die K2.

In this embodiment, as an example, one resin end face 41 is sandwiched between adjacent core blocks 3. To achieve this, the first block end face 31 covered with the resin end face 41 of one core block 3 and the exposed second block end face 32 of the other core block 3 are arranged to face each other. In addition, to achieve a mode in which one resin end face 41 is sandwiched between adjacent core blocks 3, both end faces of one core block 3 may be covered with the resin end faces 41, and notches 5 may be formed in the resin end faces 41 of both end faces to expose both end faces of the other core block 3.

That is, it is not essential that all core coating resins 4 that coat all core blocks 3 have resin end faces 41. The reactor 10 may have two types of core coating resins 4: one with resin end faces 41 at both ends, and the other with the core blocks 3 exposed from both ends. For example, the core 1 is formed by combining two U-shaped core blocks 3. The core coating resin 4 that coats one U-shaped core block 3 has resin end faces 41 at both ends. Notches 5 are formed in the resin end faces 41 at both ends. The core coating resin 4 that coats the other U-shaped core block 3 exposes the entire area of both end faces of the core block 3. When these U-shaped core blocks 3 are arranged opposite each other, one resin end face 41 is sandwiched between the adjacent core blocks 3.

Reference Signs List 1 Core 2 Coil 21 Conductive wire 22 Connecting wire 3 Core block 31 First block end face 32 Second block end face 4 Core coating resin 41 Resin end face 42 Resin side face 43 Resin back face 5 Notch 51 Opening 6 Hole 8 Second resin 10 Reactor K1 Lower die K11 First block end face support piece K2 Upper die K3 Block back face support die

Claims (6)

A plurality of core blocks;
a plurality of core coating resins each individually coating each of the core blocks;
a core that configures an annular closed magnetic circuit by combining the core blocks coated with the core coating resin;
a coil attached to the core block from above the core coating resin;
Equipped with
the core coating resin has a resin end surface that coats the end surface of the core block,
an end face of each of the core blocks is a face that approaches the adjacent core block when the annular closed magnetic circuit is formed,
a notch is formed in the resin end surface, the notch extending from a surface center side of the resin end surface toward the surface edge while cutting through the surface edge, exposing the end surface of the core block, and having an opening in a resin side surface perpendicular to the resin end surface;
A reactor characterized by the above. the core coating resin has a hole portion exposing the core block at a position directly opposite to the notch in a direction perpendicular to the resin end surface;
The reactor according to claim 1 . a second resin integrally covering the coil and the core;
the second resin flows into the notch from the opening and solidifies;
The reactor according to claim 1 or 2, the notch has a tapered shape that gradually becomes wider from the center side of the resin end face toward the edge of the face;
The reactor according to claim 3 . The core coating resin is
one end face of the core block is covered with the resin end face having the notch;
the side surface of the core block is covered until it is flush with the other end surface of the core block, exposing the entire area of the other end surface;
The reactor according to any one of claims 1 to 4, The core block is a single block that is continuous without joints, a composite of smaller blocks that are further connected, or a composite in which gaps are interposed between the smaller blocks;
The reactor according to any one of claims 1 to 5,

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