Reactor

Abstract

To provide a compact and lightweight reactor.SOLUTION: An annular core 3 includes a first leg 31 and a second leg 32 to which a coil 2 is mounted and in which a magnetic flux is generated, and a pair of yokes 33 that form a closed magnetic path together with these legs. Recesses 35a are formed at the four corners of the annular core 3 such that some of a magnetic flux generating portion and end faces 31a and 32a of the leg portion which is the end portion of the magnetic flux generating portion are exposed in the recess 35a.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. 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. Representative reactors include boost reactors incorporated in on-board boost circuits such as drive systems for hybrid and electric vehicles, 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 machines connected to them, 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 point and the ground to limit earth-fault current that flows in the event of an earth-fault in the power system, and arc-suppression reactors to automatically extinguish arcs that occur in the event of a single-line earth fault in a three-phase power system.

[0004] As electronic and electrical components become more integrated, there is a demand for these components to be made smaller and lighter. Of course, the performance of the components cannot be compromised in exchange for the smaller size and lighter weight. Therefore, a reactor has been proposed in which the part of the annular core through which almost no magnetic flux passes has been reduced (see, for example, Patent Document 1).

[0005] The annular core of this reactor has two wound sections arranged in parallel, with the end faces of the two wound sections sandwiched between a pair of non-wound sections so as to completely block them, forming a single ring shape. Almost no magnetic flux passes through the two corners of the non-wound sections that are far from the wound sections. For this reason, the two corners of the non-wound sections that are far from the wound sections have been shaved off to the extent that the end faces of the wound sections are not exposed. Because almost no magnetic flux passes through the shaved off areas, the performance of the reactor is less likely to deteriorate. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 4751266 Summary of the Invention [Problem to be solved by the invention]

[0007] In recent years, the integration of electronic components has progressed further, and there is a demand for electronic and electrical components to be made even smaller and lighter. It is desirable to make the reactor even smaller and lighter so that more space can be created inside the reactor and the components of the reactor and external components can be placed in this space.

[0008] The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to provide a reactor that is small and lightweight. [Means for solving the problem]

[0009] 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 to which the coil is attached to generate magnetic flux, a pair of yoke portions arranged separately on both end faces of the legs and forming a closed magnetic circuit together with the legs, and recesses formed at the four corners of the annular core, and a portion of the end faces of the two outermost legs are exposed in the recesses.

[0010] The yoke portion may have an inner circumferential surface in the annular core, the yoke portion may be connected to the leg portion at the inner circumferential surface, and the area on the end face of the leg portion exposed to the recess may be approximately flush with the inner circumferential surface of the yoke portion.

[0011] The yoke portion may have a total length in the direction in which the legs are arranged that is shorter than the distance from the outermost end of the end face of one of the two outermost legs to the outermost end of the other end face, and portions of the end faces of the two outermost legs may extend beyond the yoke portion, and the recess may be defined by the end faces of the yoke portion and the areas of the end faces of the two outermost legs that extend beyond the yoke portion.

[0012] The connector may have a bonding layer made of adhesive that bonds the end faces of the two outermost legs to the yoke portion.

[0013] The end faces of the two outermost legs may have an area of ​​5% to 30% both inclusive exposed from the yoke portion.

[0014] A current of 200 amperes or more may be passed, and 60% to 75% of the end faces of the two outermost legs may be exposed from the yoke portion, or a current of 250 amperes or more may be passed, and 45% to 75% of the end faces of the two outermost legs may be exposed from the yoke portion. Effect of the Invention

[0015] According to the present invention, a recess that has little effect on the inductance value in a large current region is formed, so that the reactor can be made smaller and lighter without degrading the performance of the reactor. [Brief description of the drawings]

[0016] [Figure 1] FIG. 2 is a plan view showing a main configuration of the reactor of the first embodiment. [Diagram 2]FIG. 2 is a plan view showing the configuration of an annular core according to the first embodiment. [Diagram 3] 1 is a plan view showing an overall configuration of a reactor according to a first embodiment. [Figure 4] 4 is a diagram showing magnetic flux distribution states outside the reactor of the first embodiment and a comparative reactor observed by simulation. FIG. [Diagram 5] FIG. 11 is a plan view showing the configuration of an annular core according to a second embodiment. [Figure 6] 4 is a graph showing the relationship between the current and the inductance value of the reactor according to the first embodiment and the reactor according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0018] (First embodiment) Fig. 1 shows the main configuration of a reactor. As shown in Fig. 1, the reactor 1 of the first embodiment 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, which generates magnetic flux according to the number of turns, and the annular core 3 becomes a closed magnetic circuit that passes the magnetic flux according to a magnetic permeability higher than that of a vacuum. In other words, this reactor 1 is a passive element that converts electric energy into magnetic energy and stores and releases it.

[0019] The coil 2 is a cylindrically wound body made of a conductive wire such as a copper wire. The 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 connected in parallel or in series by a bus bar or the like.

[0020] The annular core 3 is a magnetic body such as a dust core, a ferrite core, a metal composite core, or a laminated steel plate. The dust core is a powder compact obtained by compressing magnetic powder and annealing it. The magnetic powder is mainly composed of iron, and examples of the magnetic powder include pure iron powder, permalloy (Fe-Ni alloy) mainly composed of iron, Si-containing iron alloy (Fe-Si alloy), sendust alloy (Fe-Si-Al alloy), amorphous alloy, nanocrystalline alloy powder, and 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] 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 31, a second leg 32, and a pair of yoke portions 33. The first leg 31, the second leg 32, and the pair of yoke portions 33 are combined to form a ring-shaped closed magnetic circuit. The first leg 31 and the second leg 32 are fitted into the coil 2 (see Fig. 1), and are a magnetic flux generating portion that generates magnetic flux. The yoke portion 33 is a connecting portion that connects the first leg 31 and the second leg 32 with magnetic flux.

[0022] The first leg 31, the second leg 32, and the pair of yoke parts 33 are made of I-shaped cores in the shape of a rectangular prism extending linearly. A gap may be sandwiched between the first leg 31 and the second leg 32. When a gap is sandwiched, the first leg 31 and the second leg 32 are made of a plurality of short I-shaped cores connected together, and a gap is interposed between the short I-shaped cores. The gap is a magnetic gap whose magnetic permeability is orders of magnitude lower than that of the annular core 3, and is, for example, a plate-shaped spacer such as a ceramic or an air gap.

[0023] The first leg 31 and the second leg 32 are arranged in parallel. Hereinafter, the direction in which the first leg 31 and the second leg 32 extend is referred to as the vertical axis direction. The pair of yoke parts 33 are arranged in parallel and extend along the horizontal axis direction in which the first leg 31 and the second leg 32 are aligned. The horizontal axis direction is perpendicular to the vertical axis direction. The pair of yoke parts 33 are arranged separately so as to sandwich the first leg 31 and the second leg 32 from both end sides. Then, the end face 31a of the first leg 31 is butted against the inner peripheral surface 33a in the annular shape of the yoke part 33 and joined. The end face 32a of the second leg 32 is butted against the inner peripheral surface 33a of the yoke part 33 and joined.

[0024] This forms the annular core 3 into a closed ring shape. The end face 31a of the first leg 31 and the end face 32a of the second leg 32 are faces that extend perpendicular to the vertical axis direction among the six faces constituting the first leg 31 and the second leg 32. The inner peripheral surface 33a of the yoke portion 33 is a face that faces the end face 31a of the first leg 31 and the end face 32a of the second leg 32.

[0025] The first leg 31 and the yoke portion 33 are joined by an adhesive, and the second leg 32 and the yoke portion 33 are joined by an adhesive. Therefore, a bonding layer 34 made of an adhesive is interposed between the first leg 31 and the yoke portion 33, and between the second leg 32 and the yoke portion 33. The bonding layer 34 functions as an air gap according to the film thickness.

[0026] Here, the overall length Ly of the yoke portion 33 is set shorter than the distance Da between the first leg portion 31 and the second leg portion 32. The overall length Ly of the yoke portion 33 is the length along the horizontal axis direction. The distance Da between the first leg portion 31 and the second leg portion 32 is the distance along the horizontal axis direction, and is the separation distance from the far end of the end face 31a of the first leg portion 31 to the far end of the end face 32a of the second leg portion 32, including the entire end face 31a of the first leg portion 31 and the entire end face 32a of the second leg portion 32.

[0027] Therefore, end face 31a of first leg 31 and end face 32a of second leg 32 are divided into exposed regions 31c, 32c that protrude from yoke portion 33 and are exposed, and bonded regions 31d, 32d that are bonded to inner peripheral surface 33a of yoke portion 33 via bonding layer 34. End face 33b of yoke portion 33 is recessed from outer surface 31b of first leg 31 and outer surface 32b of second leg 32. End face 33b of yoke portion 33 is a surface that extends perpendicular to the horizontal axis direction, and outer surface 31b and outer surface 32b are surfaces that extend along the vertical axis direction and are away from the center of annular core 3.

[0028] That is, recesses 35a are formed at the four corners of the annular core 3. Two of the four recesses 35a are defined by the exposed area 31c on the end face 31a of the first leg 31 and the end face 33b of the yoke portion 33. The other two of the four recesses 35a are defined by the exposed area 32c on the end face 32a of the second leg 32 and the end face 33b of the yoke portion 33.

[0029] Exposed area 31c of end face 31a of first leg 31 and inner circumferential surface 33a of yoke portion 33 are aligned on the same plane except for bonding layer 34, and exposed area 32c of end face 32a of second leg 32 and inner circumferential surface 33a of yoke portion 33 are aligned on the same plane except for bonding layer 34. In other words, there is no magnetic path within annular core 3 through which magnetic flux generated near end face 31a or end face 32a can pass.

[0030] Here, the ratio of the width of the exposed regions 31c, 32c in the lateral direction to the width of the end faces 31a, 32a in the lateral direction is preferably 5% to 30%. If the ratio is within this range, there is no drop in the inductance value over the entire current range, or even if there is a drop, it is within 5% in the range of 100A or less, compared to the case where the recess 35a is not formed.

[0031] Furthermore, the ratio of the width of the exposed regions 31c, 32c in the lateral direction to the width of the end faces 31a, 32a in the lateral direction may be 60% or more and 75% or less when a current of 200 A or more is passed through the reactor 1. In this range, the inductance value when a current of 200 A or more is passed through the reactor 1 is improved compared to when the recess 35a is not formed. In the case where a current of 250 A or more is passed through the reactor 1, the ratio of the width of the exposed regions 31c, 32c in the lateral direction to the width of the end faces 31a, 32a in the lateral direction may be 45% or more and 75% or less. In this range, the inductance value when a current of 250 A or more is passed through the reactor 1 is improved compared to when the recess 35a is not formed. However, even if it is outside this range, an inductance value comparable to that when the recess 35a is not formed can be obtained.

[0032] 3 is a plan view showing the overall configuration of the reactor 1. The reactor 1 further includes a core coating resin 4. The core coating resin 4 coats the annular core 3. The coil 2 is fitted onto the core coating resin 4 and is electrically insulated from the annular core 3.

[0033] The core coating resin 4 is a molded product that maintains a certain shape and has insulating properties and heat resistance. For example, the core coating resin 4 is made of epoxy resin, unsaturated polyester resin, urethane resin, BMC (Bulk Molding Compound), PPS (Polyphenylene Sulfide), PBT (Polybutylene Terephthalate), or a composite of these.

[0034] The core coating resin 4 is formed with fastening parts 5 for fixing the reactor body 1a including the coil 2, the annular core 3, and the core coating resin 4. The reactor body 1a is fastened to, for example, a bathtub-shaped metal case that houses the reactor body 1a using the fastening parts 5. The fastening parts 5 have bolt holes that are aligned with bolt holes on a support such as a metal case, and bolts are inserted through the fastening parts 5. For example, the fastening parts 5 are installed in recesses 35a formed in the four corners of the annular core 3.

[0035] In such a reactor 1, the recess 35a exposes a part of the end face 31a of the first leg 31 and a part of the end face 32a of the second leg 32. The first leg 31 and the second leg 32 are magnetic flux generating parts around which the coil 2 is wound. The end face 31a of the first leg 31 and the end face 32a of the second leg 32 are either not spaced apart from the end of the coil 2 or are barely spaced apart from each other.

[0036] Moreover, exposed region 31c of end face 31a of first leg 31 and inner circumferential surface 33a of yoke portion 33 are aligned on the same plane except for bonding layer 34, and exposed region 32c of end face 32a of second leg 32 and inner circumferential surface 33a of yoke portion 33 are aligned on the same plane except for bonding layer 34. In other words, there is no magnetic path within annular core 3 through which magnetic flux generated near end face 31a or end face 32a can pass.

[0037] Therefore, the magnetic flux generated near exposed region 31c of first leg 31 or exposed region 32c of second leg 32 cannot reach joint regions 31d, 32d by intersecting at an angle close to a right angle with respect to the axis of coil 2, but leaks out from exposed region 31c of first leg 31 or exposed region 32c of second leg 32 into recess 35a before entering end face 33b of yoke portion 33.

[0038] Adjacent to the exposed region 31c of the first leg 31 is a junction region 31d, and adjacent to the exposed region 32c of the second leg 32 is a junction region 32d, and these junction regions 31d, 32d are joined to the yoke portion 33. However, a junction layer 34 exists in the junction regions 31d, 32d. The junction layer 34 has a high magnetic resistance. Therefore, the magnetic flux passing through the junction regions 31d, 32d is suppressed. Therefore, more magnetic flux leaks out from the exposed region 31c of the first leg 31 and the exposed region 32c of the second leg 32 before entering the end face 33b of the yoke portion 33.

[0039] In this case, the recess 35a formed so as to expose a part of the end face 31a of the first leg 31 and a part of the end face 32a of the second leg 32 functions as an air gap. Therefore, the recess 35a provides room for installing the fastening part 5 in the reactor 1 without significantly affecting the inductance value in the large current region.

[0040] 4(a) is a diagram showing the magnetic flux distribution state outside the reactor 1 observed by simulation, and FIG. 4(b) is a diagram showing the magnetic flux distribution state outside the comparison object observed by simulation. The comparison object has recesses 35a at the corners of the annular core 3. However, the depth of the recesses 35a in the vertical direction of the comparison object is shallower than the length of the yoke portion 33 in the vertical direction. In other words, the recesses 35a are missing only at two of the four corners of the yoke portion 33 that correspond to the corners of the reactor 1, and the end face 31a of the first leg 31 and the end face 32a of the second leg 32 are not exposed in the recesses 35a.

[0041] In the figure, the circled portion is the recess 35a. As can be seen by comparing (a) and (b) of FIG. 4, it can be seen that in this reactor 1, magnetic flux leaks from the recess 35a. On the other hand, it can be seen that in the comparative reactor, almost no magnetic flux leaks from the recess 35a. That is, it can be seen that the recess 35a formed so that a part of the end face 31a of the first leg 31 and the end face 32a of the second leg 32 are exposed functions as an air gap. It can also be seen that this recess 35a does not greatly affect the inductance value in the large current region, and provides room for installing the fastening part 5 in the reactor 1, for example.

[0042] Next, the relationship between the current and the inductance value in the reactor 1 of the first embodiment is shown in Table 1 below. The reactors 1 of Example 1, in which the ratio of the exposed regions 31c and 32c is 5%, Example 2, in which the ratio of the exposed regions 31c and 32c is 15%, Example 3, in which the ratio of the exposed regions 31c and 32c is 30%, Example 4, in which the ratio of the exposed regions 31c and 32c is 45%, Example 5, in which the ratio of the exposed regions 31c and 32c is 60%, and Example 6, in which the ratio of the exposed regions 31c and 32c is 75%, as well as the reactors of Comparative Example 1, in which the ratio of the exposed regions 31c and 32c is 0%, and Comparative Example 2, in which the ratio of the exposed regions 31c and 32c is 100%, were prepared. Currents up to 250 A were passed through the reactors 1 of Examples 1 to 6 and the reactors of Comparative Examples 1 and 2, and the inductance values ​​were measured. The reactors 1 of Examples 1 to 6 and the reactors of Comparative Examples 1 and 2 have end faces 31a and 31b with a total width in the horizontal axis direction of 13.5 mm.

[0043] (Table 1) TIFF0007603429000001.tif57159

[0044] In Table 1 above, the ratio of exposed areas 31c, 32c refers to the ratio of the width of exposed areas 31c, 32c in the lateral direction to the width of end faces 31a, 32a in the lateral direction. The ratios of exposed areas 31c and 32c are the same. A ratio of exposed areas 31c, 32c of 0% means that recess 35a is not formed, and a ratio of exposed areas 31c, 32c of 100% means that only the corners of first leg 31 and yoke portion 33 are in contact, and the corners of second leg 32 and yoke portion 33 are in contact.

[0045] Based on the values ​​in Table 1, the reduction rate of each inductance value of Examples 1 to 6 relative to each inductance value of Comparative Example 1 was calculated and shown in Table 2 below. In Table 2, positive values ​​indicate lower inductance values ​​than Comparative Example 1, and negative values ​​indicate higher inductance values ​​than Comparative Example 1.

[0046] (Table 2) TIFF0007603429000002.tif61158

[0047] As shown in Tables 1 and 2 above, compared to Comparative Example 1 in which the ratio of exposed regions 31c, 32c is 0%, Examples 1 to 6 in which the ratio of exposed regions 31c, 32c is 5 to 75% have low initial inductance values. The initial inductance value is the value when there is no superposition of DC current. The reason why the initial inductance value is low is because there are recesses 35a at the locations where magnetic flux passes through as magnetic paths. The initial inductance value is lower as the ratio of exposed regions 31c, 32c is larger. This is because the large locations where magnetic flux passes through as magnetic paths are cut away.

[0048] However, it can be seen that in Examples 1 to 3, in which the proportion of exposed regions 31c, 32c is 5 to 30%, there is no drop in inductance value over the entire current range including zero DC current superposition, or even if there is a drop, it is within 5% in the range of 100 A or less, when compared to Comparative Example 1, in which the proportion of exposed regions 31c, 32c is 0%.

[0049] When a current of 150 A is passed through the reactor 1, it can be confirmed that the difference in inductance value is reduced to a single digit percentage compared to the reactor of Comparative Example 1, not only for the reactors 1 of Examples 1 to 3 but also for the reactors 1 of Examples 4 to 6 in which the ratio of exposed regions 31c, 32c is 45% or more. Also, when a current of 200 A or more is passed through the reactor 1, it can be confirmed that the inductance values ​​of the reactors 1 of Examples 1 to 6 are almost the same as or higher than the inductance value of the reactor of Comparative Example 1.

[0050] That is, it can be confirmed that the recess 35a formed so as to expose a part of the end face 31a of the first leg 31 and a part of the end face 32a of the second leg 32 functions as an air gap and has little effect on the inductance value in the large current region. Therefore, if the recess 35a is formed so as to expose a part of the end face 31a of the first leg 31 and the end face 32a of the second leg 32, which are the magnetic flux generating parts, a large space can be secured without impairing the performance of the reactor 1 in the large current region, and further miniaturization and weight reduction of the reactor 1 can be achieved.

[0051] Moreover, when a current of 200 A or more is passed through the reactor 1, it is confirmed that the reactors 1 of Examples 5 and 6 in which the ratio of the exposed regions 31c, 32c is 60% or more and 75% or less have a higher inductance value than the reactor of Comparative Example 1. Also, when a current of 250 A or more is passed through the reactor 1, it is confirmed that the reactors 1 of Examples 4 to 6 in which the ratio of the exposed regions 31c, 32c is 45% or more and 75% or less have a higher inductance value than the reactor of Comparative Example 1. This shows that the performance of the reactor 1 is improved by forming the recesses 35a depending on the formation range of the recesses 35a and the large current region.

[0052] Comparative Example 2, in which the proportion of exposed areas 31c, 32c was 100%, had an inductance value in the high current region that was comparable to that of Examples 1 to 6. However, it was confirmed that the initial inductance value dropped significantly compared to Examples 1 to 6.

[0053] Furthermore, in the reactor 1 formed in this manner, the annular core 3 is made up of a rectangular prism-shaped I-shaped core consisting of the yoke portion 33, the first leg portion 31, and the second leg portion 32, so that it has good productivity and can also reduce the cost of the reactor 1.

[0054] Second embodiment FIG. 5 is a plan view showing a detailed configuration of the annular core 3 of the second embodiment. As shown in FIG. 5, the annular core 3 includes a pair of U-shaped blocks 36 and two leg blocks 37. The U-shaped core 36 has legs 36a and 36b protruding from both ends of the inner peripheral surface 33a of the yoke portion 33, forming a U-shape. The pair of U-shaped blocks 36 face each other so that the legs 36a face each other and the leg blocks 36b face each other, and the leg blocks 37 are interposed between the legs 36a and between the legs 36b. As a result, the annular core 3 has one closed magnetic circuit in a ring shape.

[0055] An end of the coil 2 covers the legs 36a and 36b of the U-shaped block 36. Therefore, the leg 36a of the U-shaped block 36 is part of the magnetic flux generating part and supports the end side of the first leg 31, and the leg 36b of the U-shaped block 36 is part of the magnetic flux generating part and supports the end side of the second leg 32.

[0056] The U-shaped block 36 has both corners cut away to form recesses 35b. The recesses 35b extend to the boundary B between the yoke portion 33 and the leg portion 36a and the boundary B between the yoke portion 33 and the leg portion 36b. That is, the end face 31a of the leg portion 36a and the end face 32a of the leg portion 36b have exposed areas 31c and 32c exposed in the recesses 35b. The exposed area 31c of the end face 31a of the leg portion 36a and the inner peripheral surface 33a of the yoke portion 33 are aligned on the same plane, and the exposed area 32c of the end face 32a of the leg portion 36b and the inner peripheral surface 33a of the yoke portion 33 are aligned on the same plane. In other words, there is no magnetic path in the annular core 3 through which the magnetic flux generated near the end face 31a or the end face 32a can pass.

[0057] Further, the recess 35b does not reach a plane formed by extending the inner surface 31e of the leg portion 36a and a plane formed by extending the inner surface 32e of the leg portion 36b. The inner surface 31e and the inner surface 32e are opposite to the outer surface 31b and the outer surface 32b.

[0058] In the reactor 1 of the second embodiment, the leg portion 36a and the yoke portion 33 are seamlessly connected, and there is no joining layer 34 next to the exposed region 31c. In addition, in the reactor 1, the leg portion 36b and the yoke portion 33 are seamlessly connected, and there is no joining layer 34 next to the exposed region 31c.

[0059] However, even in this reactor 1, recess 35b exposes end faces 31a and 32a of leg portion 36a and leg portion 36b, which are ends of the magnetic flux generating portion. Exposed area 31c of end face 31a of leg portion 36a and inner circumferential surface 33a of yoke portion 33 are aligned in the same plane, and exposed area 32c of end face 32a of leg portion 36b and inner circumferential surface 33a of yoke portion 33 are aligned in the same plane.

[0060] Therefore, the magnetic flux generated near exposed region 31c or exposed region 32c cannot reach yoke portion 33 within the annular core 3 by intersecting at an angle close to a right angle with respect to the axis of coil 2, but leaks out from exposed region 31c of first leg 31 or exposed region 32c of second leg 32 into recess 35b before entering end face 33b of yoke portion 33.

[0061] In this case, the recess 35b also functions as an air gap in this reactor 1. Therefore, the recess 35b has little effect on the inductance value in a large current region, and provides room for installing the fastening part 5 in the reactor 1 without degrading the performance of the reactor 1.

[0062] Here, the reactors 1 of Examples 7 to 11 were prepared in which the recess 35b was formed in the U-shaped block 36 and the exposed regions 31c, 32c were each in a different ratio. In the reactors 1 of Examples 7 to 11, the yoke portion 33 and the leg portion 36a, and the yoke portion 33 and the leg portion 36b were seamlessly connected. That is, the reactors 1 of Examples 7 to 11 are the reactors 1 of the second embodiment. In addition, the annular core 3 is formed by the U-shaped block 36, but the reactors of Comparative Examples 3 and 4 were prepared in which the ratios of the exposed regions 31c, 32c were 0% and 100%, respectively.

[0063] Currents up to 250 A were applied to the reactors 1 of Examples 7 to 11 and the reactors of Comparative Examples 3 and 4, and the inductance values ​​were measured. The results are shown in Table 3 below.

[0064] (Table 3) TIFF0007603429000003.tif61157

[0065] Based on the values ​​in Table 3, the percentage decrease in inductance of each of Examples 7 to 11 relative to the inductance of Comparative Example 3 was calculated and shown in Table 4 below. In Table 4, positive values ​​indicate lower inductance values ​​than Comparative Example 1, and negative values ​​indicate higher inductance values ​​than Comparative Example 1.

[0066] (Table 4) TIFF0007603429000004.tif61157

[0067] As shown in Tables 3 and 4 above, Examples 7 to 11, in which the ratio of exposed regions 31c, 32c is 15 to 75%, have lower initial inductance values ​​compared to Comparative Example 3, in which the ratio of exposed regions 31c, 32c is 0%. However, it can be seen that Examples 7 and 8, in which the ratio of exposed regions 31c, 32c is 30% or less, do not experience a drop in inductance value over the entire current range including zero DC current superposition, or even if there is a drop, it is within 4% in the range of 100 A or less, even when compared to Comparative Example 3, in which the ratio of exposed regions 31c, 32c is 0%.

[0068] When a current of 200 A is passed through the reactor 1, it can be confirmed that the difference in inductance value is reduced to a single digit percentage compared to the reactor of Comparative Example 3, not only for the reactors 1 of Examples 7 and 8 but also for the reactors 1 of Examples 9 to 11 in which the ratio of exposed regions 31c, 32c is 45% or more. Also, when a current of 250 A or more is passed through the reactor 1, it can be confirmed that the inductance values ​​of the reactors 1 of Examples 7 to 11 are almost the same as or higher than the inductance value of the reactor of Comparative Example 3.

[0069] Moreover, when a current of 250 A or more is passed through the reactor 1, it can be confirmed that the reactors 1 of Examples 10 and 11 in which the proportions of the exposed regions 31c, 32c are 60% or more and 75% or less have a higher inductance value than the reactor of Comparative Example 3. That is, this shows that even in the reactor 1 of embodiment 2, forming the recesses 35b improves the performance of the reactor 1 depending on the formation range of the recesses 35b and the large current region.

[0070] In this way, even if the legs 36a, 36b of the U-shaped block 36, which are the ends of the magnetic flux generating portion, are exposed in the recess 35b, the inductance value of the reactor 1 is not impaired in the large current region, and since the recess 35b can be made large, the reactor 1 can be made smaller and lighter.

[0071] Here, reactors 1 of Example 4 and Example 9 were prepared, in which the ratio of exposed regions 31c, 32c was 45%. The reactor 1 of Example 4 is the reactor 1 of the first embodiment, and a bonding layer 34 that becomes a magnetoresistance is disposed next to the exposed regions 31c, 32c of the end faces 31a, 32a. The reactor 1 of Example 9 is the reactor 1 of the second embodiment, and a bonding layer 34 that becomes a magnetoresistance is not disposed next to the exposed regions 31c, 32c of the end faces 31a, 32a.

[0072] Currents ranging from 0 A to 285 A in increments of 15 A were applied to the reactor 1 of Example 4 and Example 9, and the inductance values ​​were measured. The relationship between the current and the inductance value of the reactor 1 of Example 4 and Example 9 obtained by the measurement is shown in Table 5 below. The results of Table 5 below are shown in the graph of FIG. 6.

[0073] (Table 5) TIFF0007603429000005.tif241151

[0074] 6, when comparing the initial inductance value and the inductance value up to a current of 105 A, the reactor 1 of Example 4 is inferior to the reactor 1 of Example 9. However, in the current range of 120 A or more, the inductance value of the reactor 1 of Example 4 exceeds the inductance value of the reactor 1 of Example 9.

[0075] In addition, when comparing the reactor 1 of Example 2 and Example 7 in which the ratio of exposed regions 31c, 32c is 15%, the reactor 1 of Example 2 has an inductance value equivalent to that of Example 7 at 240 A, and an inductance value exceeding that of Example 7 at 255 A or more. When comparing the reactor 1 of Example 3 and Example 8 in which the ratio of exposed regions 31c, 32c is 30%, the reactor 1 of Example 3 has an inductance value equivalent to that of Example 8 at 210 A, and an inductance value exceeding that of Example 8 at 225 A or more.

[0076] Comparing the reactor 1 of Example 5 and Example 10 in which the ratio of the exposed regions 31c, 32c is 60%, the reactor 1 of Example 5 has an inductance value that exceeds that of Example 10 at 105 A or more. Comparing the reactor 1 of Example 6 and Example 11 in which the ratio of the exposed regions 31c, 32c is 75%, the reactor 1 of Example 6 has an inductance value that exceeds that of Example 11 at 75 A or more.

[0077] It has been confirmed that, when a joining layer 34 that becomes a magnetoresistance is disposed next to exposed regions 31c, 32c of end faces 31a, 32a, more magnetic flux leaks out from exposed region 31c of first leg 31 and exposed region 32c of second leg 32 before entering end face 33b of yoke portion 33. Therefore, this recess 35a does not further affect the inductance value in the large current region, and serves as a space for installing fastening portion 5 within reactor 1, etc.

[0078] (Action and effect) As described above, the reactor 1 of each embodiment has the annular core 3 and the coil 2. The annular core 3 has legs such as the first leg 31 and the second leg 32, on which the coil 2 is attached to generate magnetic flux, or the leg 36a and the leg 36b of the U-shaped block 36. The annular core 3 also has a pair of yoke parts 33 arranged separately on both end face sides of these legs and forming a closed magnetic circuit together with the legs. The recesses 35a and 35b are formed at the four corners of the annular core 3, and the end faces 31a and 32a of the legs, which are the magnetic flux generating part or the end of the magnetic flux generating part, are partially exposed in the recesses 35a and 35b. As a result, the effect of the recesses 35a and 35b on the inductance value is reduced in the large current region, so that the reactor 1 can be made smaller and lighter without degrading the performance of the reactor 1.

[0079] The yoke portion 33 has an inner peripheral surface 33a in the annular core 3, and the yoke portion 33 is connected to the leg portion at this inner peripheral surface 33a, and the exposed areas 31c, 32c on the end faces 31a, 32a of the leg portion exposed in the recess 35a or recess 35b are arranged to be substantially flush with the inner peripheral surface 33a of the yoke portion 33. As a result, there is no magnetic path in the annular core 3 through which the magnetic flux generated near the end faces 31a and 32a can pass, and the magnetic flux generated near the end faces 31a, 32a is forced to leak to the outside from the recesses 35a, 35b. Therefore, the recesses 35a, 35b function efficiently as air gaps.

[0080] In such a reactor 1, typically, the overall length Ly of the yoke portion 33 along the direction in which the legs are arranged may be shorter than the distance from the end of one end face 31a of the two legs to the end of the other end face 32a of the two legs, including the entire end faces 31a, 31b of the two outermost legs.

[0081] As a result, recesses 35a, 35b are defined by end face 33b of yoke portion 33 and exposed regions 31c, 32c of end faces 31a, 32a of the two outermost legs that protrude from yoke portion 33. Exposed regions 31c, 32c on end faces 31a, 32a of the legs that are exposed in recess 35a or recess 35b are substantially flush with inner circumferential surface 33a of yoke portion 33 except for bonding layer 34.

[0082] In the reactor 1 formed in this manner, the annular core 3 consists of a rectangular prism-shaped I-shaped core consisting of the yoke portion 33, the first leg portion 31, and the second leg portion 32, so that it has good productivity and can also reduce the cost of the reactor 1.

[0083] In each embodiment, the annular core 3 having two legs has been described as an example, but the present invention is not limited thereto, and may have three or more legs. For example, the annular core 3 may have a θ-shape in which a total of three legs, one center leg and two outer legs, are arranged in parallel, and two ring shapes are connected. In this θ-shape annular core 3, the recess 35a or the recess 35b is formed so that the end faces 31a, 32a of the two outer legs are exposed from the yoke portion 33. Even in the case of an annular core 3 having four or more legs, the recess 35a or the recess 35b may be formed so that the end faces 31a, 32a of the two outermost legs are exposed from the yoke portion 33.

[0084] Furthermore, the fastening portion 5 for fastening the reactor body 1a including the annular core 3 and the coil 2 to other portions is arranged in the recess 35a or 35b, thereby making the reactor 1 compact. In addition to the fastening portion 5, other structural components of the reactor 1, external electronic components other than the reactor 1, electronic circuits, mechanical elements, and components of other various structures may be arranged in the recess 35a or 35b.

[0085] In addition, a bonding layer 34 is provided that is made of an adhesive and bonds the end faces 31a, 32a of the two outermost legs to the yoke portion 33. This allows more magnetic flux to leak from the end faces 31a, 32a, improving the function of the recess 35a as an air gap. This reduces the effect of the recess 35a on the inductance value in the large current region.

[0086] Moreover, 5% to 30% of the end faces 31a, 32a of the two outermost legs are exposed from the yoke portion 33. In this case, the inductance value is not impaired over the entire current range, compared to when the recesses 35a and 35b are not formed. Moreover, not only the fastening portion 5 but also other structural components of the reactor 1, external electronic components other than the reactor 1, electronic circuits, mechanical elements, and other various structural components can be arranged in the recesses 35a and 35b, thereby achieving a reduction in size and weight of the reactor 1.

[0087] Moreover, 60% to 75% of the end faces 31a, 32a of the two outermost legs are exposed from the yoke portion 33. As a result, when a current of 200 amperes or more flows, the recesses 35a actually improve the inductance value of the reactor 1, while enabling the reactor 1 to be made smaller and lighter.

[0088] Furthermore, 45% to 75% of the end faces 31a, 32a of the two outermost legs are exposed from the yoke portion 33. As a result, when a current of 250 amperes or more flows, the recesses 35a actually improve the inductance value of the reactor 1, while enabling the reactor 1 to be made smaller and lighter.

[0089] The present invention is not limited to the above-described embodiment, but also includes other embodiments described below. The present invention also includes a combination of all or any of the above-described embodiment and the other embodiments described below. Furthermore, these embodiments can be omitted, replaced, or modified in various ways without departing from the scope of the invention, and such modifications are also included in the present invention. [Explanation of symbols]

[0090] 1 Reactor 1a Reactor body 2 Coil 3. Annular core 31 First leg 31a End face 31b External surface 31c exposed area 31d joining area 31e Inside surface 32 Second leg 32a End face 32b External surface 32c exposed area 32d joining area 32e inner surface 33 York 33a Inner surface 33b End face 34 Bonding layer 35a Recess 35b Recess 36 U-shaped block 36a Legs 36b Legs 37 Leg Block 4 Core coating resin 5 Fastening Part

Claims

1. A reactor having a ring-shaped core and a coil, through which a current of 200 amperes or more flows, The annular core is Two or more legs on which the coil is attached to generate magnetic flux; A pair of yoke portions arranged separately on both end surfaces of the leg portion and forming a closed magnetic circuit together with the leg portion; Recesses are formed at four corners of the annular core; a bonding layer made of an adhesive and bonding the end faces of the two outermost legs to the yoke portion; having a portion of the end surface of each of the two outermost legs is exposed in the recess; an area of ​​the end faces of the two outermost legs is exposed from the yoke portion by 60% or more and 75% or less; A reactor characterized by the above.

2. A reactor having a ring-shaped core and a coil, through which a current of 250 amperes or more flows, The annular core is Two or more legs on which the coil is attached to generate magnetic flux; A pair of yoke portions arranged separately on both end surfaces of the leg portion and forming a closed magnetic circuit together with the leg portion; Recesses are formed at four corners of the annular core; a bonding layer made of an adhesive and bonding the end faces of the two outermost legs to the yoke portion; having a portion of the end surface of each of the two outermost legs is exposed in the recess; an area of ​​the end faces of the two outermost legs is exposed from the yoke portion by 45% or more and 75% or less; A reactor characterized by the above.

3. the yoke portion has an inner circumferential surface of the annular core, the yoke portion is connected to the leg portion at the inner circumferential surface, an area on the end face of the leg portion exposed in the recess is substantially flush with an inner circumferential surface of the yoke portion; The reactor according to claim 1 or 2,

4. the yoke portion has an overall length along a direction in which the legs are arranged that is shorter than a distance from an outermost end of the end surface of one of the two outermost legs to an outermost end of the end surface of the other of the two outermost legs; The two outermost leg portions have end faces each extending beyond the yoke portion, the recess is defined by an end surface of the yoke portion and a region of the end surfaces of the two outermost legs that protrude from the yoke portion; The reactor according to any one of claims 1 to 3,

5. a main body including the annular core and the coil; A fastening portion disposed in the recess and fastening the main body to another portion; To have The reactor according to any one of claims 1 to 4,

Images