Reactor

Abstract

To provide a reactor with excellent manufacturing efficiency even when a gap thickness is different.SOLUTION: Two or more legs of an annular core 3 of a reactor 1 include a first leg 31a and a second leg 31b that differ in the presence or absence of gaps or the total thickness of the gaps. A first joint portion 32a of a yoke portion 32 to be joined to a first leg portion 31a and a second joint portion 32b of a yoke portion 32 to be joined to a second leg portion 31b have different protruding heights or recessed depths, and a difference in height between the first joint portion 32a and the second joint portion 32b is half a difference in the total thickness of a first gap 4a and a second gap 4b of the first leg portion 31a and the second leg portion 31b.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a reactor having a core and a coil. [Background technology]

[0002] A reactor has a coil and a core that is inserted into the coil. To electrically insulate the coil from the core, the core is usually covered with a resin material, and the wound coil is attached to the core from above the resin material. This reactor is a passive element that converts electrical energy into magnetic energy and stores and releases it.

[0003] Such reactors are used in a wide variety of applications. Typical examples include boost reactors incorporated in onboard boost circuits for hybrid and electric vehicle drive systems, series reactors connected in series to motor circuits to limit current during short circuits, parallel reactors to stabilize current sharing between parallel circuits, current-limiting reactors to limit current during short circuits and protect connected machinery, starting reactors connected in series to motor circuits to limit starting current, shunt reactors connected in parallel to transmission lines to compensate for leading reactive power and suppress abnormal voltages, neutral reactors connected between the neutral and ground to limit ground-fault current in the event of a ground fault in the power system, and arc-suppression reactors to automatically extinguish arcs that occur in single-phase ground faults in three-phase power systems.

[0004] Reactors are susceptible to magnetic saturation, where the magnetic flux density becomes saturated as the magnetic field increases. When a reactor becomes magnetically saturated, the magnetic permeability becomes very low, just like an air core, and the inductance drops sharply. Therefore, when a reactor becomes magnetically saturated, there is a risk that excessive current will flow through the reactor and the circuit in which it is incorporated. For this reason, a gap is provided in the core. The gap increases the magnetic resistance of the core. When the magnetic resistance of the core increases, the increase in magnetic flux density relative to the strength of the magnetic field becomes more gradual, suppressing magnetic flux saturation of the reactor.

[0005] There is a reactor with a θ-shaped core. The θ-shaped core has a center leg, two outer legs, and a yoke. Two outer legs are placed on either side of the center leg. The yoke sandwiches the three legs from both sides. This gives the θ-shaped core a shape consisting of two connected rings with a common center leg. A coil is inserted into each of the outer legs and the center leg.

[0006] A reactor with a θ-shaped core has non-uniform magnetic paths. The magnetic flux generated in the outer legs and passing through a magnetic path with magnetic path length L1 flows around the center leg from both outer legs. The magnetic flux generated in the center leg and passing through a magnetic path with magnetic path length L1, and the magnetic flux generated in the other outer leg, located farther away from the center leg, and passing through a magnetic path length L2, flow around the outer leg. The magnetic resistance of the core excluding the gap is proportional to the magnetic path length. Therefore, the magnetic resistance of the core excluding the gap in the outer legs is different from the magnetic resistance of the core excluding the gap in the center leg.

[0007] Therefore, to eliminate the difference between the magnetic resistance of the magnetic path passing through the outer legs and the magnetic path passing through the center legs, the total thickness of the gaps provided in the outer legs is made different from the total thickness of the gaps provided in the center legs (see, for example, Patent Document 1). In other words, the difference in magnetic resistance due to the difference in magnetic path length is offset by the difference in magnetic resistance due to the difference in gap thickness.

[0008] There are also reactors with a single ring-shaped core. The core of this reactor has two legs sandwiched between yokes on both sides, forming a single ring shape. Even in reactors with a single ring-shaped core, the gaps between one leg and the other leg may have different thicknesses. For example, if only one leg is placed in the case, the external leakage magnetic flux from the gaps between the two legs will be different, and non-uniformity in the magnetic path will occur. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 2018-26504 Summary of the Invention [Problem to be solved by the invention]

[0010] The total length of the legs of the core is La, with a gap of thickness G1 provided at one location on one leg and a gap of thickness G2 provided at one location on the other leg. In this case, one leg has two leg blocks with a total length of (La - G1) / 2 and a gap of thickness G1 sandwiched between the leg blocks. The other leg has two leg blocks with a total length of (La - G2) / 2 and a gap of thickness G2 sandwiched between the leg blocks. The pair of yoke parts sandwiching both legs have the same shape and size.

[0011] In this way, when the gap thicknesses in the two legs are different, the core requires three types of core material: one type of yoke and two types of leg blocks.When the gap thicknesses in the three legs are all different, the core requires three types of core material: one type of yoke and three types of leg blocks.

[0012] Therefore, when the gap thickness is varied, at least three or more types of molds and manufacturing equipment are required to manufacture the yoke portion and two or more types of leg blocks. This reduces the manufacturing efficiency of the reactor compared to a reactor with a uniform gap. In addition, there is a risk of misassembly of the two types of leg blocks, which reduces the yield and also reduces the manufacturing efficiency of the reactor.

[0013] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a reactor that can be manufactured with excellent efficiency even when the gap thickness is varied. [Means for solving the problem]

[0014] The reactor of the present invention is a reactor having an annular core and a coil, wherein the annular core has two or more legs and a pair of yoke portions connecting the legs, one or more of the legs having a gap, and the two or more legs include a first leg and a second leg that differ in the presence or absence of the gap or the total thickness of the gap, the yoke portion has each joint portion that joins to the end surface of the leg, and each of the joint portions includes a first joint portion that joins to the first leg and a second joint portion that joins to the second leg, the first joint portion and the second joint portion have different heights along the extension direction of the first leg and the second leg, and the difference in height between the first joint portion and the second joint portion is half the difference in the total thickness of the gap between the first leg and the second leg. [Effects of the Invention]

[0015] According to the present invention, even if the gap thickness is varied, the core is made up of one type of yoke portion and one type of leg block, and a reactor with excellent manufacturing efficiency can be obtained. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a plan view showing the overall configuration of a reactor according to a first embodiment. [Figure 2] FIG. 2 is a plan view showing the configuration of the annular core according to the first embodiment. [Figure 3] FIG. 10 is a plan view showing the configuration of an annular core according to a second embodiment. [Figure 4] FIG. 10 is a plan view showing the configuration of an annular core according to a third embodiment. [Figure 5] FIG. 10 is a plan view showing the configuration of an annular core according to a fourth embodiment. [Figure 6] FIG. 10 is a plan view showing the configuration of an annular core according to a fifth embodiment. [Figure 7] FIG. 10 is a plan view showing the configuration of an annular core according to a sixth embodiment. [Figure 8] FIG. 13 is a plan view showing the overall configuration of a reactor according to a seventh embodiment. [Figure 9] FIG. 13 is a plan view showing the configuration of an annular core according to a seventh embodiment. [Figure 10] FIG. 13 is a plan view showing the overall configuration of a reactor according to an eighth embodiment. [Figure 11] FIG. 13 is a plan view showing the configuration of an annular core according to a ninth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, reactors according to embodiments of the present invention will be described with reference to the drawings. In the drawings, thicknesses, dimensions, positional relationships, ratios, shapes, and the like may be emphasized for ease of understanding, but the present invention is not limited to such emphasis.

[0018] FIG. 1 shows the overall configuration of a reactor according to a first embodiment. This reactor 1 includes two coils 2 and one annular core 3. The two coils 2 are attached to the annular core 3. When a current flows through the coils 2, the coils 2 generate magnetic flux according to the number of turns, and the annular core 3 forms a closed magnetic circuit, allowing the magnetic flux generated by the coils 2 to pass through with a magnetic permeability higher than that of a vacuum. In other words, the reactor 1 is a passive element that converts electrical energy into magnetic energy and stores and releases it.

[0019] The coil 2 is a cylindrically wound body made of conductive wire such as copper wire. This coil 2 is formed by winding the conductive wire in a spiral shape while shifting the winding position for each turn along a winding axis. The two coils 2 are attached to the annular core 3 via an insulating material (not shown) such as a resin member.

[0020] The annular core 3 is a magnetic material such as a powder magnetic core, a ferrite core, a metal composite core, or a laminated steel plate. A powder magnetic core is an annealed compact made by compressing magnetic powder. The magnetic powder is primarily composed of iron, and examples thereof include pure iron powder, iron-based permalloy (Fe-Ni alloy), Si-containing iron alloy (Fe-Si alloy), sendust alloy (Fe-Si-Al alloy), amorphous alloy, nanocrystalline alloy powder, and a mixture of two or more of these powders. A metal composite core is a core made by kneading and molding magnetic powder and resin.

[0021] Fig. 2 is a plan view showing a detailed configuration of the annular core 3 of the first embodiment. As shown in Fig. 2, the annular core 3 includes a first leg 31a, a second leg 31b, and a pair of yoke portions 32. The first leg 31a, the second leg 31b, and the pair of yoke portions 32 are combined to form the annular core 3, which is a ring-shaped closed magnetic circuit. The first leg 31a and the second leg 31b are fitted into the coil 2 and are magnetic flux generating portions that generate magnetic flux. The yoke portion 32 is a connecting portion that connects the first leg 31a and the second leg 31b with magnetic flux.

[0022] The first leg 31a and the second leg 31b are arranged in parallel. The pair of yoke portions 32 are also arranged in parallel and extend in a direction perpendicular to the first leg 31a and the second leg 31b. The pair of yoke portions 32 are arranged to sandwich the first leg 31a and the second leg 31b from both ends. Each of the yoke portions 32 has a first joint portion 32a that joins with the first leg 31a and a second joint portion 32b that joins with the second leg 31b. The end face of the first leg 31a is butted against the first joint portion 32a and joined with an adhesive. The end face of the second leg 31b is butted against the second joint portion 32b and joined with an adhesive. This allows the annular core 3 to have a closed ring shape.

[0023] The first leg 31a is made up of two leg blocks 33a connected together. A first gap 4a is interposed between the two leg blocks 33a. The second leg 31b is made up of two leg blocks 33b connected together. A second gap 4b is interposed between the two leg blocks 33b. The first gap 4a and the second gap 4b are located at the longitudinal center of the first leg 31a and the second leg 31b. The leg blocks 33a on both sides of the first gap 4a have the same overall length Ba. The leg blocks 33b on both sides of the second gap 4b have the same overall length Bb.

[0024] The first gap 4a and the second gap 4b are magnetic gaps whose magnetic permeability is orders of magnitude lower than that of the annular core 3. The first gap 4a and the second gap 4b are, for example, plate-shaped spacers or air gaps. The plate-shaped spacers are, for example, ceramic materials formed into a flat plate shape. They are non-magnetic materials, such as ceramics such as alumina or zirconia, non-metals, resins, carbon fibers, or composite materials of two or more of these formed into a flat plate shape, or gap paper. The air gap is a gap without a magnetic material.

[0025] The thickness Ga of the first gap 4a of the first leg 31a and the thickness Gb of the second gap 4b of the second leg 31b are different to eliminate non-uniformity of the magnetic path, etc. The first gap 4a of the first leg 31a is thicker than the second gap 4b of the second leg 31b. As shown in the following equation (1), when the thickness Gb of the second gap 4b of the second leg 31b is subtracted from the thickness Ga of the first gap 4a of the first leg 31a, there is a thickness difference D between the first gap 4a and the second gap 4b.

[0026] D = Ga - Gb (1)

[0027] The pair of yoke portions 32 are identical in shape and size and are arranged symmetrically about a line perpendicular to the extension direction of the first leg portion 31a and the second leg portion 31b. The second joint portion 32b on the side of the second leg portion 31b having the thin second gap 4b is arranged opposite the second joint portion 32b of the other yoke portion 32, and the first gap 4a and the second gap 4b protrude beyond the first joint portion 32a by half the thickness difference D. The protruding direction of the second joint portion 32b is the same as the extension direction of the second leg portion 31b. On the other hand, the first joint portion 32a on the side of the first leg 31a having the thick first gap 4a is flat and does not protrude. That is, as shown in the following formula (2), the distance Lb between the protruding second bonding portions 32b is shorter than the distance La between the flat first bonding portions 32a by the difference in thickness D between the first gap 4a and the second gap 4b.

[0028] Lb = La - D (2)

[0029] The two leg blocks 33a and one first gap 4a of the first leg 31a fit within the distance La between the flat first joints 32a. Therefore, as shown in the following formula (3), the total length Ba of the leg block 33a is half the value obtained by subtracting the thickness Ga of the first gap 4a from the distance La between the first joints 32a.

[0030] Ba = (La - Ga) / 2 (3)

[0031] The distance Lb between the protruding second joints 32b accommodates the two leg blocks 33b and one second gap 4b of the second leg 31b. Therefore, as shown in the following formula (4), the total length Bb of the leg block 33b is half the value obtained by subtracting the thickness Gb of the second gap 4b from the distance Lb between the second joints 32b.

[0032] Bb = (Lb - Gb) / 2 (4)

[0033] Because the second joints 32b protrude from the first joints 32a by half the thickness difference D and the second joints 32b face each other, the separation distance Lb is shorter than the separation distance La by the thickness difference D between the first gap 4a and the second gap 4b, as shown in the above formula (2). Therefore, from the above formulas (2) and (4), the total length Bb of the leg block 33b can be said to be half the value obtained by subtracting the sum of the thickness difference D between the first gap 4a and the second gap 4b and the thickness Gb of the second gap 4b from the separation distance La between the first joints 32a, as shown in the following formula (5).

[0034] Bb = [La - (D + Gb)] / 2 (5)

[0035] As shown in the above formula (1), the sum of the difference in thickness D between the first gap 4a and the second gap 4b and the thickness Gb of the second gap 4b is the thickness Ga of the first gap 4a. Therefore, from the above formulas (1) and (5), as shown in the following formula (6), the total length Bb of this leg block 33b can be said to be half the value obtained by subtracting the thickness Ga of the first gap 4a from the separation distance La between the flat first joint portions 32a.

[0036] Bb=(La-Ga) / 2 (6)

[0037] That is, from the above equations (3) and (6), as shown in the following equation (7), the total length Ba of each leg block 33a of the first leg 31a and the total length Bb of each leg block 33b of the second leg 31b are equal, and they can be made to have the same shape and size.

[0038] Ba=Bb (7)

[0039] Thus, in the annular core 3, the height difference between the first joint 32a of the first leg 31a and the second joint 32b of the second leg 31b is half the thickness difference D. Therefore, even if the thickness Ga of the first gap 4a and the thickness Gb of the second gap 4b are different, the annular core 3 can be constructed using core members for the leg blocks 33a and 33b and the yoke portion 32, which are identical in shape and size. In other words, the annular core 3 can be constructed using a total of two types of core members. The height difference between the first joint 32a and the second joint 32b is the distance between the ends of the first joint 32a and the second joint 32b measured along the extension direction of the first leg 31a and the second leg 31b.

[0040] Here, the height difference between the first joint 32a of the first leg 31a and the second joint 32b of the second leg 31b need only be relative and is not limited to one protruding from the other. Fig. 3 is a plan view showing a detailed configuration of the annular core 3 of the second embodiment. As shown in Fig. 3, the first gap 4a of the first leg 31a is thicker than the second gap 4b of the second leg 31b. When the thickness Gb of the second gap 4b is subtracted from the thickness Ga of the first gap 4a, the first gap 4a and the second gap 4b have a thickness difference D.

[0041] The first joint 32a on the side of the first leg 31a having the thick first gap 4a is recessed from the second joint 32b by half the difference in thickness D between the first gap 4a and the second gap 4b. The pair of yoke portions 32 have the same shape and size and are arranged symmetrically about a line perpendicular to the extension direction of the first leg 31a and the second leg 31b, and the second joint 32b is arranged opposite the second joint 32b of the other yoke portion 32. On the other hand, the second joint 32b on the side of the second leg 31b having the thin second gap 4b is flat without protruding or recessing.

[0042] As a result, thick first gaps 4a are present between the recessed first joints 32a, but the separation distance La between the first joints 32a is longer than the separation distance Lb between the second joints 32b. The difference between the separation distance La and the separation distance Lb is equal to the difference in thickness D between the first gaps 4a and the second gaps 4b. In other words, the difference in thickness D between the first gaps 4a and the second gaps 4b is offset by the recessed first joints 32a widening the separation distance La. There is no need to make the leg blocks 33a smaller to accommodate the thick first gaps 4a.

[0043] Therefore, by recessing the joint 32a, which joins the first leg 31a including the thick first gap 4a, by half the thickness difference D between the first gap 4a and the second gap 4b, and creating a height difference between the joints 32a and 32b by half the thickness difference D, the annular core 3 can be constructed from two types of core members: the yoke portion 32 of the same shape and size, and the leg blocks 33a and 33b of the same shape and size.

[0044] 4 is a plan view showing a detailed configuration of the annular core 3 of the third embodiment. As shown in FIG. 4, the first gap 4a of the first leg 31a is thicker than the second gap 4b of the second leg 31b, and there is a thickness difference D between the first gap 4a and the second gap 4b. A first joint 32a on the first leg 31a side having the thick first gap 4a and a second joint 32b on the second leg 31b side having the thin second gap 4b both protrude from the yoke portion 32. This yoke portion 32 has a roughly C- or U-shape.

[0045] The pair of yoke portions 32 are of the same shape and size and are arranged to be symmetrical about a line perpendicular to the extension direction of the first leg portion 31a and the second leg portion 31b, with the first joint portions 32a and the second joint portions 32b being arranged opposite each other.

[0046] However, the second joint 32b on the side of the second leg 31b having the thinner second gap 4b has a longer protrusion length than the first joint 32a by half the difference in thickness D between the first gap 4a and the second gap 4b. In other words, the first joint 32a on the side of the first leg 31a having the thicker first gap 4a has a shorter protrusion length than the second joint 32b by half the difference in thickness D between the first gap 4a and the second gap 4b, and is recessed by half the difference in thickness D with respect to the second joint 32b.

[0047] In this way, by making both the first joint 32a and the second joint 32b protrude and creating a difference in height between the first joint 32a and the second joint 32b so that the difference in protrusion length is half the thickness difference D between the first gap 4a and the second gap 4b, it is possible to construct a core member consisting of two types of core members: a yoke portion 32 of the same shape and size, and leg blocks 33a and 33b of the same shape and size.

[0048] The embodiment in which both the first joint portion 32a and the second joint portion 32b are protruding and the difference in protrusion is adjusted is particularly suitable when the yoke portion 32, the leg blocks 33a, and the leg blocks 33b are powder magnetic cores or metal composite cores. Powder magnetic cores or metal composite cores are molded by placing magnetic powder or a mixture of magnetic powder and resin in a mold and compressing it. In press molding using a mold, the dimensions of the yoke portion 32, the leg blocks 33a, and the leg blocks 33b are more accurate when both the first joint portion 32a and the second joint portion 32b are protruding.

[0049] If the dimensional accuracy of the yoke portion 32, the leg blocks 33a, and the leg blocks 33b is poor, the yoke portion 32, the leg blocks 33a, and the leg blocks 33b may come off or crack due to vibration or heat. That is, an unexpected air gap may occur in the annular core 3, causing the magnetic path to become non-uniform again. However, the embodiment in which both the first joint portion 32a and the second joint portion 32b protrude can achieve good dimensional accuracy of the yoke portion 32, the leg blocks 33a, and the leg blocks 33b during press molding using a mold.

[0050] Fig. 5 is a plan view showing a detailed configuration of the annular core 3 according to the fourth embodiment. As shown in Fig. 5, it is necessary to create small protrusions or recesses, but the first joint portion 32a may be recessed and the second joint portion 32b may be protruded. The pair of yoke portions 32 have the same shape and size and are arranged symmetrically with respect to a line perpendicular to the extension direction of the first leg portion 31a and the second leg portion 31b, with the first joint portions 32a and the second joint portions 32b facing each other.

[0051] By recessing the first joint portion 32a and protruding the second joint portion 32b, the height difference between the first joint portion 32a and the second joint portion 32b can be adjusted to match the thickness difference D between the first gap 4a and the second gap 4b. This annular core 3 can also be composed of two types of core members: a yoke portion 32 of the same shape and size, and leg blocks 33a and 33b of the same shape and size.

[0052] FIG. 6 is a plan view showing a detailed configuration of the annular core 3 according to the fifth embodiment. In the annular core 3 according to the fifth embodiment, the pair of yoke portions 32 are also identical in shape and size and are arranged symmetrically about a line perpendicular to the extension direction of the first leg portion 31a and the second leg portion 31b. The first joint portions 32a and the second joint portions 32b are arranged opposite each other. Of the first leg portion 31a and the second leg portion 31b, the first leg portion 31a may have the first gap 4a only. In this case, the thickness Gb of the second gap 4b of the second leg portion 31b is considered to be zero. The thickness Ga of the first gap 4a is the thickness difference D, which is absorbed by the height difference between the first joint portion 32a and the second joint portion 32b.

[0053] This annular core 3 can also be configured with two types of core members: a yoke portion 32 of the same shape and size, and leg blocks 33a and 33b of the same shape and size. The second leg portion 31b can be formed by joining two leg blocks 33b with an adhesive or the like without inserting a second gap 4b.

[0054] 7 is a plan view showing a detailed configuration of the annular core 3 according to the sixth embodiment. In the annular core 3 according to the sixth embodiment, the pair of yoke portions 32 also have the same shape and size and are arranged symmetrically with respect to a line perpendicular to the extension direction of the first leg portion 31 a and the second leg portion 31 b, with the first joint portions 32 a and the second joint portions 32 b arranged opposite each other.

[0055] Here, if the first gap 4a and the second gap 4b are made thick, there is a risk of magnetic flux leaking from the first gap 4a and the second gap 4b. Depending on the reactor 1, in order to adjust the magnetic flux leakage, multiple thin first gaps 4a may be provided in the first leg 31a and multiple thin second gaps 4b may be provided in the second leg 31b.

[0056] The plurality of thin first gaps 4a are spaced apart at equal distances along the length of the first leg 31a. This ensures that the leg blocks 33a aligned along the first leg 31a have the same shape and size. The plurality of thin second gaps 4b are spaced apart at equal distances along the length of the second leg 31b. This ensures that the leg blocks 33b aligned along the second leg 31b have the same shape and size.

[0057] The difference between the total thickness Ga of the first gaps 4a (EGa) and the total thickness Gb of the second gaps 4b (EGb) is defined as the thickness difference D, and the height difference between the first joint 32a and the second joint 33b is set to half of this thickness difference D. This makes the leg block 33a and the leg block 33b the same shape and size.

[0058] The above explanation has been based on the annular core 3 having one ring shape, but an annular core 3 having two or more connected ring shapes can also be formed using two types of core members: a yoke portion 32 of the same shape and size, and leg blocks 33a and 33b of the same shape and size.

[0059] Fig. 8 is a plan view showing the overall configuration of a reactor 1 according to a seventh embodiment. Fig. 9 is a plan view showing the configuration of an annular core 3 according to the seventh embodiment. As shown in Figs. 8 and 9, this reactor 1 includes an annular core 3 formed of three connected rings and four coils 2.

[0060] The annular core 3 is configured by combining two first legs 31a as center legs, two second legs 31b as outer legs, and a pair of yoke portions 32. The two first legs 31a are arranged next to each other, and two second legs 31b are arranged separately on either side of the two first legs 31a. The two first legs 31a and the two second legs 31b are arranged parallel to each other. A pair of yoke portions 32 is arranged between both ends of the first legs 31a and the second legs 31b. The yoke portions 32 are arranged parallel to each other and extend perpendicular to the extension direction of the first legs 31a and the second legs 31b.

[0061] The pair of yoke portions 32 have second joints 32b at both ends in the extension direction and two first joints 32a at the center in the extension direction. The pair of yoke portions 32 have the same shape and size and are arranged symmetrically with respect to a line perpendicular to the extension direction of the first leg portion 31a and the second leg portion 31b, with the first joints 32a and the second joints 32b arranged opposite each other. The pair of yoke portions 32 are joined to the two second legs 31b at two second joints 32b and to the two first legs 31a at two first joints 32a.

[0062] The first leg 31a of the center leg is made up of leg blocks 33a arranged in a row, with a first gap 4a interposed between the leg blocks 33a. The second leg 31b of the outer leg is made up of leg blocks 33b arranged in a row, with a second gap 4b interposed between the leg blocks 33b. The thickness Ga of the first gap 4a and the thickness Gb of the second gap 4b are different because the magnetic path lengths of the magnetic flux that flows around them are different.

[0063] In this annular core 3 in which two rings are connected, a height difference equal to half the thickness difference D between the thickness Ga of the first gap 4a and the thickness Gb of the second gap 4b is provided between the first joint portion 32a and the second joint portion 32b. This allows the leg blocks 33b constituting the two outer second legs 31b and the leg block 33a constituting the single center first leg 31a to be the same shape and size. Therefore, the annular core 3 can be formed using two types of core members: a pair of yoke portions 32 of the same shape and size, and leg blocks 33a and 33b of the same shape and size.

[0064] 10 is a plan view showing the configuration of an annular core 3 according to an eighth embodiment. The annular core 3 has a first center leg portion 311, a second center leg portion 312, a first outer leg portion 313, and a second outer leg portion 314, as well as a pair of yoke portions 32, forming a θ shape in which two ring shapes are connected together. The yoke portion 32 includes a first center leg joint portion 321 that joins with the first center leg portion 311, a second center leg joint portion 322 that joins with the second center leg portion 312, a first outer leg joint portion 323 that joins with the first outer leg portion 313, and a second outer leg joint portion 324 that joins with the second outer leg portion 314.

[0065] The pair of yoke portions 32 are of the same shape and size and are arranged so as to be symmetrical about a line perpendicular to the extension direction of the first middle leg portion 311, the second middle leg portion 312, the first outer leg portion 313 and the second outer leg portion 314, with the first middle leg joints 321, the second middle leg joints 322, the first outer leg joints 323 and the second outer leg joints 324 arranged opposite each other.

[0066] The first center leg portion 311 is formed by connecting leg blocks 331 and has a center leg gap 41 interposed therebetween. The second center leg portion 312 is formed by connecting leg blocks 332 and has a center leg gap 42 interposed therebetween. The first outer leg portion 313 is formed by connecting leg blocks 333 and has a first outer leg gap 43 interposed therebetween. The second outer leg portion 314 is formed by connecting leg blocks 334 and has a second outer leg gap 44 interposed therebetween. The thickness G1 of the first center leg gap 41, the thickness G2 of the second center leg gap 42, the thickness G3 of the first outer leg gap 43, and the thickness G4 of the second outer leg gap 44 are all different values.

[0067] In the case of this annular core 3, one leg is used as the reference. For example, the first center leg 311 is used as the reference, and the first center leg 311 is regarded as the first leg 31a, and the first center leg joint 321 is regarded as the first joint 32a. First, the second center leg 312 is regarded as the second leg 31b, and the second outer leg joint 322 is regarded as the second joint 32b. The second center leg joint 322 is protruded or recessed relative to the first center leg joint 321 so that half of the thickness difference D1 between the thickness G1 of the center leg inner gap 41 and the thickness G2 of the second center leg inner gap 42 is the height difference between the first center leg joint 321 and the second center leg joint 322.

[0068] Next, the first outer leg portion 313 is the second leg portion 31b, and the first outer leg joint 323 is the second joint 32b. The first outer leg joint 323 is protruded or recessed relative to the first middle leg joint 321 so that half of the thickness difference D2 between the thickness G1 of the middle leg inner gap 41 and the thickness G3 of the first outer leg inner gap 43 becomes the height difference between the first middle leg joint 321 and the first outer leg joint 323.

[0069] Next, the second outer leg portion 314 is defined as the second leg portion 31b, and the second outer leg joint portion 324 is defined as the second joint portion 32b. The second outer leg joint portion 324 is protruded or recessed relative to the first center leg joint portion 321 so that half of the thickness difference D3 between the thickness G1 of the center leg internal gap 41 and the thickness G4 of the second outer leg internal gap 43 is the height difference between the first center leg joint portion 321 and the second outer leg joint portion 324. This allows the leg block 331, the leg block 332, and the leg block 333 to have the same shape and size, and together with the pair of yoke portions 32 having the same shape and size, the annular core 3 can be formed using a total of two types of core members.

[0070] FIG. 11 is a plan view showing the configuration of an annular core 3 according to a ninth embodiment. Unlike the reactors 1 according to the first to eighth embodiments, the coil 2 does not necessarily have to be attached to all of the legs. This annular core 3 has a single ring shape, but the coil 2 is attached only to the first leg 31a, and the coil 2 is not attached to the second leg 31b. Even with this annular core 3, the leg blocks 33a and 33b can be made the same shape and size by setting the height difference between the first joint portion 32a and the second joint portion 32b to half the thickness difference D between the first gap 4a and the second gap 4b. This allows the annular core 3 to be formed using a total of two types of core material, including the pair of yoke portions 32 having the same shape and size.

[0071] As described above, in reactor 1, annular core 3 is composed of two or more legs, such as first leg 31a and second leg 31b. First leg 31a and second leg 31b differ in the presence or absence of a gap, such as first gap 4a, the total thickness of first gap 4a and second gap 4b, or both. First joint 32a, which joins first leg 31a, and second joint 32b, which joins second leg 31b, differ in their protruding height or recessed depth along the extension direction of first leg 31a and second leg 31b, and the difference in height is half the difference D in the total thickness of first gap 4a and second gap 4b.

[0072] This allows the leg blocks 33a and 33b to have the same shape and size, and together with the pair of yoke portions 32 having the same shape and size, the annular core 3 can be formed using a total of two types of core material. Therefore, even if the thicknesses of the first gap 4a and the second gap 4b are different, the annular core 3 can be formed using a total of two types: one type of yoke portion 32 and one type of leg blocks 33a and leg blocks 33b. This reduces the number of molds and the probability of assembly errors, resulting in a reactor with excellent manufacturing efficiency.

[0073] The thickness of the adhesive used to bond the yoke portion 32 to the first leg 31a and the second leg 31b, and the thickness of the adhesive used to bond the leg block 33a and the leg block 33b to the first gap 4a and the second gap 4b, may be included in the total thickness Ga of the first gap 4a and the total thickness Gb of the second gap 4b, because the thickness of the adhesive can also function as an air gap.

[0074] In addition, the first joint 32a and the second joint 32b both protrude toward the first leg 31a and the second leg 31b, and the protruding length of the first joint 32a and the protruding length of the second joint 32b are different.

[0075] This allows the protrusion lengths of the first and second joints 32a and 32b to approach the designed dimensions with high precision when molding the yoke 32 using a mold, thereby reducing the risk of the yoke 32, leg blocks 33a, or leg blocks 33b coming off or cracking due to vibration or heat, causing an unexpected air gap in the annular core 3, and causing the magnetic path to become non-uniform again.

[0076] The present invention is not limited to the above-described embodiments, but also includes other embodiments described below. The present invention also includes a combination of all or any of the above-described embodiments and the other embodiments described below. Furthermore, various omissions, substitutions, and modifications can be made to these embodiments without departing from the scope of the invention, and such modifications are also included in the present invention.

[0077] For example, the present invention has been described using examples of a single ring-shaped annular core 3 and an annular core 3 made up of three connected ring shapes, but the present invention is not limited to these and can be applied to an annular core 3 made up of multiple legs, such as a θ-shaped annular core 3 having three legs and made up of two connected ring shapes.

[0078] The first gap 4a and the second gap 4b may be formed by stacking multiple ultra-thin plates of the same thickness. This allows the first gap 4a and the second gap 4b to be formed by stacking the same parts, further improving production efficiency. The first gap 4a and the second gap 4b may also be formed between the yoke portion 32 and the first leg portion 31a or the second leg portion 31b. [Explanation of symbols]

[0079] 1 reactor 2 coils 3 Annular Core 31a First Leg 31b Second leg 311 First Middle Leg 312 Second Middle Leg 313 First outer leg 314 Second outer leg 32 York 32a First joint 32b Second joint 321 First middle leg joint 322 Second mid-leg joint 323 First outer leg joint 324 Second outer leg joint 33a Leg block 33b Leg block 331 Leg Block 332 Leg Block 333 Leg Block 334 Leg Block 4a First Gap 4b Second Gap 41 First mid-leg gap 42 Second mid-leg gap 43 First outer leg gap 44 Second outer leg gap

Claims

1. A reactor having an annular core and a coil, The annular core has two or more legs and a pair of yoke portions connecting the legs, The pair of yoke portions are separate from the leg portion and are arranged separately so as to sandwich the leg portion from both ends of the leg portion, one or more of the legs has a gap; The two or more legs include a first leg and a second leg that are different in the presence or absence of the gap or the total thickness of the gap, the yoke portion includes joint portions at which end faces of the leg portions are butted against and joined to the end faces, Each of the joints includes a first joint that is joined to the first leg portion and a second joint that is joined to the second leg portion; The pair of yoke portions are arranged so that the first joint portions face each other via the legs, and the second joint portions face each other via the legs, with respect to a flat portion between the first leg portion and the second leg portion, only one of the first joint portion and the second joint portion protrudes from the yoke portion or is recessed into the yoke portion, or the first joint portion protrudes from the yoke portion and the second joint portion is recessed into the yoke portion, so that heights of the first leg portion and the second leg portion along an extension direction differ, a height difference between the first joint portion and the second joint portion is half a difference between a total thickness of the gap of the first leg portion and a total thickness of the gap of the second leg portion; All of the legs are made up of one or more leg blocks connected together, The yoke portions sandwiching the leg portions have the same shape and size, All of the leg blocks of all the legs have the same shape and size; A reactor characterized by the above.

2. the annular core has one ring shape having two of the legs, or a shape in which two ring shapes are connected together and have three of the legs; The reactor according to claim 1 .

3. The annular core is a powder magnetic core; The reactor according to claim 1 or 2,

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