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 Art

[0002] A reactor has a coil and a core inserted through the coil. In order to achieve electrical insulation between the coil and the core, usually the core is coated with a resin member, and the wound coil is mounted on the core from above the resin member. This reactor is a passive element that converts electrical energy into magnetic energy for storage and release.

[0003] Such reactors are used in a wide variety of applications. Typical reactors include boost reactors incorporated into in-vehicle boost circuits such as drive systems of hybrid vehicles and electric vehicles, series reactors connected in series to a motor circuit to limit current during a short circuit, parallel reactors that stabilize current sharing between parallel circuits, current-limiting reactors that limit current during a short circuit and protect machines connected thereto, starting reactors connected in series to a motor circuit to limit starting current, shunt reactors connected in parallel to a transmission line to compensate for leading reactive power and suppress abnormal voltages, neutral point reactors used to connect between a neutral point and the ground to limit the ground fault current flowing during a ground fault accident in a power system, arc extinguishing reactors that automatically extinguish arcs generated during a single-phase-to-ground fault in a three-phase power system, and the like.

[0004] There is a risk of magnetic saturation in a reactor, where the magnetic flux density saturates as the magnetic field increases. When the reactor becomes magnetically saturated, the permeability becomes very low like that of an air core and the inductance drops rapidly. Therefore, when the reactor becomes magnetically saturated, there is a risk that an excessive current will flow through the reactor and the circuit in which the reactor is incorporated. Thus, 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 the magnetic flux density with respect to the strength of the magnetic field becomes gentle, and magnetic flux saturation of the reactor is suppressed.

[0005] There is a reactor with a θ-shaped core. The θ-shaped core has a middle leg, two outer legs, and a yoke section. The two outer legs are positioned on either side of the middle leg. The yoke section sandwiches the three legs from both sides. As a result, the θ-shaped core has a shape consisting of two connected ring shapes with the middle leg in common. Coils are inserted through each of the two outer legs and the middle leg.

[0006] In reactors with a θ-shaped core, magnetic path non-uniformity occurs. For the middle leg, magnetic flux generated at the outer leg and passing through a magnetic path of length L1 wraps around from both outer legs. For the outer leg, magnetic flux generated at the middle leg and passing through a magnetic path of length L1, and magnetic flux generated at the other outer leg, which is farther away from the middle leg and passing through a magnetic path of length L2, wrap around. 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 at the outer leg is different from the magnetic resistance of the core excluding the gap at the middle leg.

[0007] Therefore, in order to eliminate the difference between the magnetic resistance of the magnetic path passing through the outer leg and the magnetic resistance of the magnetic path passing through the middle leg, the total thickness of the gap provided in the outer leg and the total thickness of the gap provided in the middle leg are made different (see, for example, Patent Document 1). In other words, the difference in magnetic resistance due to the difference in magnetic path length is canceled out by the difference in magnetic resistance due to the difference in gap thickness.

[0008] Furthermore, there are reactors that have a single ring-shaped core. The core of this reactor has a single ring shape formed by sandwiching two legs from both sides with yoke sections. Even in reactors with a single ring-shaped core, the thickness of the gap between one leg and the other leg may be different. For example, if only one leg is enclosed in a case, the external leakage magnetic flux from the gaps of both legs will be different, and non-uniformity of the magnetic path will also occur. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 2018-26504 [Overview of the project] [Problems that the invention aims to solve]

[0010] Let La be the total length of the core's legs. A gap of thickness G1 is provided at one location on one leg, and a gap of thickness G2 is provided at one location on the other leg. In this case, one leg comprises two leg blocks with a total length of (La-G1) / 2 and a gap of thickness G1 interposed between the leg blocks. The other leg comprises two leg blocks with a total length of (La-G2) / 2 and a gap of thickness G2 interposed between the leg blocks. The pair of yoke sections sandwiching both legs are identical in shape and size.

[0011] Thus, if the thickness of the gaps in the two legs differs, the core requires a total of three core components: one type of yoke and two types of leg blocks. If the thickness of the gaps in all three legs differs, the core requires a total of three core components: one type of yoke and three types of leg blocks.

[0012] Therefore, if the gap thickness is varied, at least three types of molds and manufacturing equipment are required to produce the yoke section and two or more types of leg blocks. As a result, the manufacturing efficiency of the reactor decreases compared to reactors with a unified gap. In addition, there is a risk of incorrect assembly of the two types of leg blocks, which reduces the yield and further decreases the manufacturing efficiency of the reactor.

[0013] This invention was made to solve the above-mentioned problems, and its objective is to provide a reactor that offers excellent manufacturing 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 have a gap, and the two or more of the legs include a first leg and a second leg which differ in the presence or absence of the gap or the total thickness of the gaps, the yoke portions have joints which join with the end faces of the legs, and each joint includes a first joint which joins with the first leg and a second joint which joins with the second leg, the first joint and the second joint differ in height along the extension direction of the first leg and the second leg, and the height difference between the first joint and the second joint is half the difference in the total thickness of the gaps 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 consists of one type of yoke section and one type of leg block, resulting in a reactor with excellent manufacturing efficiency. [Brief explanation of the drawing]

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

Embodiments for Carrying out the Invention

[0017] Hereinafter, the reactors of each embodiment of the present invention will be described with reference to the drawings. In each drawing, for ease of understanding, the thickness, dimensions, positional relationship, ratio, shape, etc. may be emphasized and shown, and the present invention is not limited to those emphases.

[0018] FIG. 1 shows the overall configuration of the reactor according to the 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. A current is passed through the coil 2, and the coil 2 through which the current is passed generates magnetic flux according to the number of turns, and the annular core 3 forms a closed magnetic path and passes the magnetic flux generated by the coil 2 according to a magnetic permeability higher than that of a vacuum. That is, the reactor 1 becomes a passive element that converts electrical energy into magnetic energy and stores and releases it.

[0019] The coil 2 is a cylindrical winding body made of a conductive wire such as a copper wire. This coil 2 is formed by winding the conductive wire in a spiral shape while shifting the winding position by one turn along the 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 core, a ferrite core, a metal composite core, or a laminated steel sheet. The powder core is made by annealing a powder compact formed by compressing magnetic powder. Examples of magnetic powders include pure iron powder, permalloy (Fe-Ni alloy) with iron as the main component, 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 a core formed by kneading and molding magnetic powder and resin.

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

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

[0023] The first leg portion 31a is made up of two connected leg blocks 33a. A first gap 4a is interposed between the two leg blocks 33a. The second leg portion 31b is made up of two connected leg blocks 33b. 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 portion 31a and the second leg portion 31b. The total length Ba of the leg blocks 33a on both sides of the first gap 4a is the same length. The total length Bb of the leg blocks 33b on both sides of the second gap 4b is the same length.

[0024] The first gap 4a and the second gap 4b are magnetic gaps whose 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. Plate-shaped spacers are, for example, ceramic materials formed into a flat plate shape. They can be non-magnetic materials, ceramics such as alumina or zirconia, nonmetals, resins, carbon fibers, or composite materials of two or more of these formed into a flat plate shape, or gap paper. An air gap is a gap without 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 in order to eliminate non-uniformity of the magnetic path. The first gap 4a of the first leg 31a is thicker than the second gap 4b of the second leg 31b. As shown in equation (1) below, 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, the first gap 4a and the second gap 4b have a thickness difference D.

[0026] D = Ga - Gb ···(1)

[0027] The pair of yoke portions 32 are identical in shape and size, and are arranged symmetrically with respect to a line perpendicular to the extension directions of the first leg portion 31a and the second leg portion 31b. The second joint portion 32b on the second leg portion 31b side, which has a thin second gap 4b, is positioned opposite the second joint portion 32b of the other yoke portion 32, and the first gap 4a and the second gap 4b protrude from the first joint portion 32a by half the thickness difference D. The direction of protrusion of the second joint portion 32b is the direction in which the second leg portion 31b extends. On the other hand, the first joint portion 32a on the first leg portion 31a side, which has a thick first gap 4a, is flat and does not protrude. That is, as shown in equation (2) below, the distance Lb between the protruding second joints 32b is shorter than the distance La between the flat first joints 32a by the difference D in thickness between the first gap 4a and the second gap 4b.

[0028] Lb = La - D ···(2)

[0029] The distance La between the two flat first joints 32a accommodates the two leg blocks 33a and one first gap 4a of the first leg 31a. Therefore, as shown in equation (3) below, 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 equation (4) below, 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] The second joint 32b protrudes from the first joint 32a by half the thickness difference D, and the second joints 32b face each other. As shown in equation (2) above, 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. Thus, from equations (2) and (4) above, as shown in equation (5) below, 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.

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

[0035] As shown in equation (1) above, 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 is equal to the thickness Ga of the first gap 4a. Therefore, from equations (1) and (5) above, as shown in equation (6) below, 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 distance La between the flat first joint portions 32a.

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

[0037] That is, from equations (3) and (6) above, as shown in equation (7) below, 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 can be made to be of 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 portion 31a and the second joint 32b of the second leg portion 31b is equal to 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 composed of core members consisting of leg blocks 33a and 33b of the same shape and size, and a yoke portion 32 of the same shape and size. In other words, the annular core 3 can be composed of 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 direction in which the first leg portion 31a and the second leg portion 31b extend.

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

[0041] The first joint 32a on the first leg portion 31a side, which has a thick first gap 4a, is recessed from the second joint 32b by half the thickness difference D between the first gap 4a and the second gap 4b. The pair of yoke portions 32 are identical in 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 second joint 32b facing the second joint 32b of the other yoke portion 32. On the other hand, the second joint 32b on the second leg portion 31b side, which has a thin second gap 4b, is flat without protrusion or recess.

[0042] As a result, a thick first gap 4a is interposed between the recessed first joints 32a, but the distance La between the first joints 32a is longer than the distance Lb between the second joints 32b. The difference between the distance La and the distance Lb is equal to the difference in thickness D between the first gap 4a and the second gap 4b. That is, the difference in thickness D between the first gap 4a and the second gap 4b is canceled out by the recessing of the first joints 32a, which widens the distance La. Because of the presence of the thick first gap 4a, there is no need to reduce the size of the leg block 33a.

[0043] Therefore, by recessing the joint portion 32a that connects the annular core 3 to the first leg portion 31a which includes a thick first gap 4a by half the thickness difference D between the first gap 4a and the second gap 4b, and by creating a height difference of half the thickness difference D between the joint portion 32a and the joint portion 32b, it is possible to construct a total 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.

[0044] Figure 4 is a plan view showing the detailed configuration of the annular core 3 of a third embodiment. As shown in Figure 4, the first gap 4a of the first leg portion 31a is thicker than the second gap 4b of the second leg portion 31b, and the first gap 4a and the second gap 4b have a thickness difference D. The first joint portion 32a on the first leg portion 31a side, which has the thicker first gap 4a, and the second joint portion 32b on the second leg portion 31b side, which has the thinner second gap 4b, both protrude from the yoke portion 32. This yoke portion 32 has a generally C-shape or U-shape.

[0045] The pair of yoke sections 32 are identical in shape and size, and are arranged symmetrically with respect to a line perpendicular to the extension direction of the first leg section 31a and the second leg section 31b, with the first joint sections 32a and the second joint sections 32b facing each other.

[0046] However, the second joint 32b on the second leg portion 31b side, which has a thin second gap 4b, has a protruding length that is half the thickness difference D between the first gap 4a and the second gap 4b, longer than the first joint 32a. In other words, the first joint 32a on the first leg portion 31a side, which has a thick first gap 4a, has a protruding length that is half the thickness difference D between the first gap 4a and the second gap 4b, shorter than the second joint 32b, and is recessed by half the thickness difference D relative to the second joint 32b.

[0047] In this way, by making both the first joint 32a and the second joint 32b protrude, and by creating a height difference between the first joint 32a and the second joint 32b such 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 total 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 configuration in which both the first joint 32a and the second joint 32b protrude and are adjusted by the difference in protrusion is particularly suitable when the yoke portion 32, leg block 33a, and leg block 33b are compacted magnetic cores or metal composite cores. Compacted magnetic cores or metal composite cores are formed by placing magnetic powder or a mixture of magnetic powder and resin into a mold and compacting it. In press molding using a die, the dimensions of the yoke portion 32, leg block 33a, and leg block 33b are more precise when both the first joint 32a and the second joint 32b protrude.

[0049] If the dimensional accuracy of the yoke portion 32, leg block 33a, and leg block 33b is poor, vibration or heat may cause the yoke portion 32, leg block 33a, or leg block 33b to detach or crack. In other words, an unexpected air gap may occur in the annular core 3, and the non-uniformity of the magnetic path may recur. However, the configuration in which both the first joint portion 32a and the second joint portion 32b protrude allows for good dimensional accuracy of the yoke portion 32, leg block 33a, and leg block 33b in press molding using a die.

[0050] Figure 5 is a plan view showing the detailed configuration of the annular core 3 of a fourth embodiment. As shown in Figure 5, it is necessary to create minute protrusions and recesses, but the first joint portion 32a may be recessed and the second joint portion 32b may be made to protrude. The pair of yoke portions 32 are 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 32a and protruding the second joint 32b, the height difference between the first joint 32a and the second joint 32b can be matched to 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] Figure 6 is a plan view showing the detailed configuration of the annular core 3 of the fifth embodiment. In the annular core 3 of the fifth embodiment, the pair of yoke portions 32 are 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. Of the first leg portion 31a and the second leg portion 31b, only the first leg portion 31a may be provided with the first gap 4a. 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 becomes the thickness difference D, and this thickness difference D 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 composed of two types of core members: a yoke portion 32 of the same shape and size, and two leg blocks 33a and 33b of the same shape and size. The second leg portion 31b can be formed by joining the two leg blocks 33b with an adhesive or the like, without interposing the second gap 4b.

[0054] Figure 7 is a plan view showing the detailed configuration of the annular core 3 of the sixth embodiment. In the annular core 3 of the sixth embodiment, the pair of yoke portions 32 are 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.

[0055] If the first gap 4a and the second gap 4b are made thicker, there is a risk that magnetic flux will leak from the first gap 4a and the second gap 4b. Depending on the reactor 1, in order to adjust for magnetic flux leakage, multiple thin first gaps 4a may be provided on the first leg portion 31a and multiple thin second gaps 4b may be provided on the second leg portion 31b.

[0056] Multiple thin first gaps 4a are arranged at equal distances along the length of the first leg portion 31a. As a result, the leg blocks 33a aligned with the first leg portion 31a are identical in shape and size. Multiple thin second gaps 4b are arranged at equal distances along the length of the second leg portion 31b. As a result, the leg blocks 33b aligned with the second leg portion 31b are identical in shape and size.

[0057] Then, the difference between the sum of the thicknesses EGa of each first gap 4a, Ga, and the sum of the thicknesses EGb of each second gap 4b, Gb, 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. As a result, the leg blocks 33a and 33b are also identical in shape and size.

[0058] The above explanation has been based on an annular core 3 having a single ring shape, but an annular core 3 having two or more connected ring shapes can also be formed using a total 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.

[0059] Figure 8 is a plan view showing the overall configuration of the reactor 1 according to the seventh embodiment. Figure 9 is a plan view showing the configuration of the annular core 3 according to the seventh embodiment. As shown in Figures 8 and 9, this reactor 1 comprises an annular core 3 consisting of three connected ring shapes and four coils 2.

[0060] This annular core 3 is composed of two first legs 31a that form the middle legs, two second legs 31b that form the outer legs, and a pair of yoke sections 32. The two first legs 31a are arranged side by side, and the 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 in parallel. The pair of yoke sections 32 are sandwiched between the ends of the first legs 31a and the second legs 31b. The yoke sections 32 are arranged in parallel and extend perpendicular to the extension direction of the first legs 31a and the second legs 31b.

[0061] Each pair of yoke sections 32 has 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 sections 32 are identical in shape and size, and are arranged symmetrically with respect to a line perpendicular to the extension direction of the first leg section 31a and the second leg section 31b, with each first joint 32a and each second joint 32b facing each other. The two second joints 32b are joined to the two second leg sections 31b, and the two first joints 32a are joined to the two first leg sections 31a.

[0062] The first leg portion 31a of the middle leg is made up of a series of leg blocks 33a, with a first gap 4a interposed between the leg blocks 33a. The second leg portion 31b of the outer leg is made up of a series of leg blocks 33b, 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 incoming magnetic flux are different.

[0063] In the annular core 3, which consists of these two connected ring shapes, 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 32a and the second joint 32b. This makes it possible to make the leg blocks 33b that constitute the two outer legs of the second leg portions 31b and the leg block 33a that constitutes the single middle leg of the first leg portion 31a identical in shape and size. Thus, the annular core 3 can be formed by a total of two types of core members: a pair of identical yoke portions 32 and identical leg blocks 33a and 33b.

[0064] Figure 10 is a plan view showing the configuration of an annular core 3 according to the eighth embodiment. This annular core 3 has a θ shape formed by two connected ring shapes, consisting of a first middle leg portion 311, a second middle leg portion 312, a first outer leg portion 313, a second outer leg portion 314, and a pair of yoke portions 32. The yoke portion 32 includes a first middle leg joint portion 321 that connects to the first middle leg portion 311, a second middle leg joint portion 322 that connects to the second middle leg portion 312, a first outer leg joint portion 323 that connects to the first outer leg portion 313, and a second outer leg joint portion 324 that connects to the second outer leg portion 314.

[0065] The pair of yoke sections 32 are identical in shape and size, and are arranged symmetrically with respect to a line perpendicular to the extension direction of the first middle leg section 311, the second middle leg section 312, the first outer leg section 313, and the second outer leg section 314. 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 are arranged facing each other.

[0066] The first mid-leg section 311 is composed of a series of leg blocks 331, with a mid-leg internal gap 41 inserted between them. The second mid-leg section 312 is composed of a series of leg blocks 332, with a mid-leg internal gap 42 inserted between them. The first outer leg section 313 is composed of a series of leg blocks 333, with a first outer leg internal gap 43 inserted between them. The second outer leg section 314 is composed of a series of leg blocks 334, with a second outer leg internal gap 44 inserted between them. The thickness G1 of the first mid-leg internal gap 41, the thickness G2 of the second mid-leg internal gap 42, the thickness G3 of the first outer leg internal gap 43, and the thickness G4 of the second outer leg internal gap 44 are all different values.

[0067] In the case of this annular core 3, one leg is used as a reference. For example, the first middle leg portion 311 is used as a reference, and the first middle leg portion 311 is considered as the first leg portion 31a, and the first middle leg joint portion 321 is considered as the first joint portion 32a. First, the second middle leg portion 312 is designated as the second leg portion 31b, and the second outer leg joint portion 322 is designated as the second joint portion 32b. The second middle leg joint portion 322 is made to protrude or recess relative to the first middle leg joint portion 321 such that half of the thickness difference D1 between the thickness G1 of the middle leg inner gap 41 and the thickness G2 of the second middle leg inner gap 42 becomes the height difference between the first middle leg joint portion 321 and the second middle leg joint portion 322.

[0068] Next, the first outer leg portion 313 is designated as the second leg portion 31b, and the first outer leg joint portion 323 is designated as the second joint portion 32b. The first outer leg joint portion 323 is made to protrude or recess relative to the first middle leg joint portion 321 such 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 portion 321 and the first outer leg joint portion 323.

[0069] Next, the second outer leg portion 314 is designated as the second leg portion 31b, and the second outer leg joint portion 324 is designated as the second joint portion 32b. The second outer leg joint portion 324 is made to protrude or recess relative to the first middle leg joint portion 321 such that half of the thickness difference D3 between the thickness G1 of the middle leg inner gap 41 and the thickness G4 of the second outer leg inner gap 43 becomes the height difference between the first middle leg joint portion 321 and the second outer leg joint portion 324. This makes it possible to make the leg blocks 331, 332, and 333 the same shape and size, and together with a pair of yoke portions 32 of the same shape and size, an annular core 3 can be formed with a total of two types of core members.

[0070] Figure 11 is a plan view showing the configuration of the annular core 3 according to the ninth embodiment. Unlike the reactor 1 of the first to eighth embodiments, coils 2 are not attached to all legs. This annular core 3 has a single ring shape, but coils 2 are attached only to the first leg 31a, and not to the second leg 31b. Even with this annular core 3, by making the height difference between the first joint 32a and the second joint 32b half the thickness difference D between the first gap 4a and the second gap 4b, the leg blocks 33a and 33b can be made the same shape and size, and together with a pair of yoke portions 32 of the same shape and size, the annular core 3 can be formed with a total of two types of core members.

[0071] As described above, in reactor 1, the annular core 3 is composed of two or more legs, such as a first leg 31a and a second leg 31b. The first leg 31a and the second leg 31b differ in the presence or absence of a gap, such as a first gap 4a, in the combined thickness of the first gap 4a and the second gap 4b, or both. In this case, the first joint 32a that connects to the first leg 31a and the second joint 32b that connects to the second leg 31b have different protruding heights or recessed depths along the extension direction of the first leg 31a and the second leg 31b, and the difference in height is set to be half of the combined thickness difference D of the first gap 4a and the second gap 4b.

[0072] This allows the leg blocks 33a and 33b to be the same shape and size, and together with a pair of yoke sections 32 of the same shape and size, the annular core 3 can be formed with a total of two types of core members. Therefore, even if the thickness of the first gap 4a and the second gap 4b are different, the annular core 3 can be formed with a total of two types: one type of yoke section 32 and one type of leg blocks 33a and 33b. As a result, a reactor with superior manufacturing efficiency can be obtained by reducing the number of molds and decreasing the probability of assembly errors.

[0073] Furthermore, the thickness of the adhesive used to join the yoke portion 32 to the first leg portion 31a and the second leg portion 31b, and the thickness of the adhesive used to join 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. This is because the thickness of the adhesive can also function as an air gap.

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

[0075] As a result, when the yoke portion 32 is molded using a mold, the protruding lengths of the first joint portion 32a and the second joint portion 32b can be brought very close to the design dimensions with high precision. Therefore, the risk of the yoke portion 32, leg block 33a, or leg block 33b becoming detached or cracking due to vibration or heat, causing an unexpected air gap in the annular core 3, and recurring non-uniformity of the magnetic path can be reduced.

[0076] The present invention is not limited to the embodiments described above, but also includes other embodiments shown below. Furthermore, the present invention also includes forms that combine all or any of the embodiments described above and the other embodiments shown below. Moreover, these embodiments can be modified in various ways without departing from the scope of the invention, and such variations are also included in the present invention.

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

[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 also be constructed by stacking the same parts, further improving production efficiency. Alternatively, the first gap 4a and the second gap 4b may be provided 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. Ring core 31a First leg 31b Second leg 311 First midfoot 312 Second midleg section 313 First outer leg 314 Second outer leg 32 York section 32a First joint 32b Second joint 321 First mid-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 The first gap 4b The second gap 41. First mid-leg gap 42. Second mid-leg gap 43. First outer leg inner gap 44. Second outer leg inner 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 sections are separate from the leg sections and are positioned to sandwich the leg sections from both ends. All of the aforementioned legs have a gap, The two or more legs include a first leg and a second leg, each having a different total thickness of the gap. The yoke portion includes joints where the end faces of the leg portions abut against each other and join to the end faces, Each of the aforementioned joints includes a first joint that connects to the first leg and a second joint that connects to the second leg. The pair of yoke portions are arranged so that their first joints face each other via the legs, and their second joints face each other via the legs. The first joint and the second joint of the same yoke portion differ in height along the extending direction of the first leg and the second leg, with respect to one of the first joint or the second joint. The height difference between the first joint and the second joint is half the difference between the total thickness of the gaps of the first leg and the total thickness of the gaps of the second leg. All of the aforementioned legs consist of one or more leg blocks connected together. Both of the yoke portions that sandwich the aforementioned leg portion have the same shape and size. All of the leg blocks of all of the aforementioned legs are of the same shape and size. The annular core is formed by a total of two types of core members: one type of yoke portion and one type of leg block. A reactor characterized by the following.

2. The first joint and the second joint both protrude from the yoke portion toward the legs, with reference to the flat portion between the first leg and the second leg of the yoke portion. The protruding length of the first joint and the protruding length of the second joint are different. The reactor according to claim 1, characterized by the following:

3. With respect to the flat portion between the first leg and the second leg of the yoke portion, only one of the first joint portion and the second joint portion protrudes from the yoke portion or is recessed relative to the yoke portion, or the first joint portion protrudes from the yoke portion and the second joint portion is recessed relative to the yoke portion. The reactor according to claim 1, characterized by the following:

4. The annular core has a single ring shape with two legs, or a shape in which two ring shapes are joined together with three legs. A reactor according to any one of claims 1 to 3, characterized by the following:

5. The aforementioned annular core is a compacted magnetic core. A reactor according to any one of claims 1 to 4, characterized by the following:

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