reactor

Abstract

Provided is a small and light electric reactor. A ring-shaped core (3) has: first and second leg portions (31, 32) for mounting a coil (2) to generate a magnetic flux; and a pair of yoke portions (33) that form a closed magnetic path together with the leg portions. A recess (35a) is formed at each of four corners of the ring-shaped core (3), and a portion of an end surface (31a, 32a) of the leg portion that is a magnetic flux generating portion or an end portion of the magnetic flux generating portion is exposed to the recess (35a).

Description

[0001] This invention is a divisional application of the invention patent application filed on November 10, 2021, with application number 202111325423.7 and invention title "Reactor". Technical Field

[0002] This invention relates to a reactor having an iron core and a coil. Background Technology

[0003] A reactor consists of a coil and an iron core. To ensure electrical insulation between the coil and the iron core, the iron core is typically covered with a resin component, and the wound coil is mounted to the iron core from the resin component. The reactor is a passive component that converts electrical energy into magnetic energy for storage and release.

[0004] Such reactors are used for a wide variety of applications. Representative examples include boost reactors installed in the boost circuits of drive systems for hybrid or electric vehicles; series reactors connected in series with motor circuits to limit the current during short circuits; shunt reactors that stabilize the current sharing between parallel circuits; current-limiting reactors that limit the current during short circuits to protect connected machinery; starting reactors connected in series with motor circuits to limit the starting current; shunt reactors connected in parallel with transmission lines to compensate for leading reactive power or suppress abnormal voltages; neutral point reactors connected between the neutral point and the ground to limit the ground fault current flowing during ground faults in the power system; and arc-suppressing reactors that automatically extinguish arcs generated when a single-wire ground fault occurs in a three-phase power system.

[0005] The integration of electronic and electrical components is advancing, thus requiring these components to be miniaturized and lightweight. Of course, component performance cannot be sacrificed for miniaturization and lightweighting. Therefore, a reactor that eliminates the portion of the toroidal core through which magnetic flux hardly passes has been proposed (see, for example, Patent Document 1).

[0006] The reactor's annular core has two parallel wound sections, which are then enclosed by a pair of unwound sections, forming a ring shape. Magnetic flux passes almost entirely through the two corners of the unwound sections furthest from the wound sections. Therefore, the two corners of the unwound sections furthest from the wound sections are removed, within the area where the end faces of the wound sections are not exposed. Since the removed areas are where magnetic flux passes almost entirely, the reactor's performance is less likely to degrade.

[0007] [Existing technical documents]

[0008] [Patent Literature]

[0009] [Patent Document 1] Japanese Patent No. 4751266 Summary of the Invention

[0010] [The problem the invention aims to solve]

[0011] In recent years, the integration of electronic components has further developed, thus requiring further miniaturization and weight reduction of electronic and electrical components. There is a desire to further miniaturize and lighten reactors, so as to create more free space within the reactor, allowing for the placement of reactor structural elements or external component structural elements in those free spaces.

[0012] This invention was made to solve the problems described above, and its purpose is to provide a small and lightweight reactor.

[0013] [Technical means to solve the problem]

[0014] The reactor of the present invention is a reactor having a toroidal core and a coil, wherein the toroidal core has: two or more legs for mounting the coil to generate magnetic flux; a pair of magnetic yokes separately disposed on the end faces of the legs, forming a closed magnetic circuit together with the legs; recesses formed at the four corners of the toroidal core, exposing a portion of the end faces of the two outermost legs; a body comprising the toroidal core and the coil; and fastening portions disposed in the recesses to fasten the body to other parts.

[0015] Alternatively, the magnetic yoke may have an inner circumferential surface in the annular iron core, the magnetic yoke may be connected to the leg on the inner circumferential surface, and the area on the end face of the leg exposed to the recess may be in approximately the same plane as the inner circumferential surface of the magnetic yoke.

[0016] Alternatively, the total length of the magnetic yoke along the direction in which the legs are arranged may be shorter than the distance from the outermost end of the end face of one of the two outermost legs to the outermost end face of the other. A portion of the end face of the two outermost legs extends beyond the magnetic yoke, and the recess is defined by the area extending beyond the magnetic yoke from the end face of the magnetic yoke and the end face of the two outermost legs.

[0017] It may also have a bonding layer formed by an adhesive, which bonds the end faces of the two outermost legs to the magnetic yoke.

[0018] Alternatively, it may include a core-coating resin, wherein the core-coating resin coats the annular core, and the fastening portion is formed in the core-coating resin.

[0019] [The effects of the invention]

[0020] According to the present invention, a recess is formed in the high current region that has little impact on the inductance value, thus enabling the reactor to be miniaturized and lightweight without reducing the reactor's performance. Attached Figure Description

[0021] Figure 1 This is a plan view showing the main structure of the reactor in the first embodiment.

[0022] Figure 2 This is a plan view showing the structure of the annular core in the first embodiment.

[0023] Figure 3 This is a plan view showing the overall structure of the reactor according to the first embodiment.

[0024] Figure 4 (a) and Figure 4 (b) is a diagram showing the external magnetic flux distribution of the reactor of the first embodiment and the reactor of the comparison object observed by simulation.

[0025] Figure 5 This is a plan view showing the structure of the annular core in the second embodiment.

[0026] Figure 6 A graph showing the relationship between current and inductance values ​​for the reactor in the first embodiment and the reactor in the second embodiment.

[0027] [Explanation of Symbols]

[0028] 1: Reactor

[0029] 1a: Reactor body

[0030] 2: Coil

[0031] 3: Circular iron core

[0032] 31: First leg

[0033] 31a: End face

[0034] 31b: Outer surface

[0035] 31c: Exposed area

[0036] 31d: Joint area

[0037] 31e: Inner surface

[0038] 32: Second leg

[0039] 32a: End face

[0040] 32b: outer surface

[0041] 32c: Exposed area

[0042] 32d: Joint area

[0043] 32e: Inner surface

[0044] 33: Magnetic yoke

[0045] 33a: Inner circumferential surface

[0046] 33b: End face

[0047] 34: Bonding layer

[0048] 35a: concave part

[0049] 35b: concave part

[0050] 36: U-shaped block

[0051] 36a: Legs

[0052] 36b: Legs

[0053] 37: Leg block

[0054] 4: Resin coating on iron core

[0055] 5: Fastening parts Detailed Implementation

[0056] Hereinafter, an embodiment of the reactor of the present invention will be described with reference to the accompanying drawings. In the drawings, for ease of understanding, thickness, dimensions, positional relationships, ratios, or shapes are sometimes emphasized, but the present invention is not limited to these emphasis.

[0057] (First Implementation)

[0058] Figure 1 This indicates the main structure of the reactor. For example... Figure 1 As shown, the reactor 1 in the first embodiment includes two coils 2 and a toroidal core 3. The two coils 2 are mounted on the toroidal core 3. Current flows through the coils 2, and the coils 2 with current flowing through them generate magnetic flux according to the number of turns. The toroidal core 3 forms a closed magnetic circuit through which the magnetic flux passes, with a permeability higher than that of vacuum. That is, the reactor 1 is a passive element that converts electrical energy into magnetic energy and stores and releases it.

[0059] Coil 2 is a cylindrical winding formed from conductive wire such as copper wire. Coil 2 is formed by spirally winding the conductive wire, staggering the winding positions after each turn along the axis. Two coils 2 are connected in parallel or in series via a busbar or the like.

[0060] The annular core 3 can be a pressed powder core, ferrite core, metal composite core, or laminated steel plate, etc. Pressed powder cores are formed by pressing magnetic powder and annealing the resulting pressed powder molded body. The magnetic powder is mainly composed of iron, and examples include pure iron powder, permalloy (Fe-Ni alloy) mainly composed of iron, iron-containing iron alloy (Fe-Si alloy), iron-silicon-aluminum alloy (Fe-Si-Al alloy), amorphous alloy, nanocrystalline alloy powder, or a mixture of two or more of these powders. Metal composite cores are formed by mixing magnetic powder with resin and then molding them.

[0061] Figure 2 This is a plan view showing the detailed structure of the annular core 3 in the first embodiment. (See attached image.) Figure 2 As shown, the annular core 3 includes a first leg 31, a second leg 32, and a pair of magnetic yokes 33. A closed magnetic circuit in the shape of a ring is formed by combining the first leg 31, the second leg 32, and the pair of magnetic yokes 33. The first leg 31 and the second leg 32 are embedded in the coil 2 (see reference). Figure 1 The magnetic flux generating part (31) generates magnetic flux. The magnetic yoke part 33 is a connecting part that couples the first leg 31 and the second leg 32 using magnetic flux.

[0062] The first leg 31, the second leg 32, and a pair of magnetic yokes 33 are formed by I-shaped iron cores extending in a straight line in a quadrangular prism shape. The first leg 31 and the second leg 32 may also have gaps in between. In the case of gaps, the first leg 31 and the second leg 32 are formed by connecting multiple short I-shaped iron cores, with the gaps between the short I-shaped iron cores. These gaps are magnetic gaps with a permeability much lower than that of the annular iron core 3, such as plate-shaped spacers or air gaps made of ceramic.

[0063] 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 will be referred to as the longitudinal axis direction. A pair of magnetic yokes 33 are arranged in parallel and extend along the transverse axis direction along which the first leg 31 and the second leg 32 are arranged. The transverse axis direction is orthogonal to the longitudinal axis direction. The pair of magnetic yokes 33 are arranged separately such that they clamp the first leg 31 and the second leg 32 from both end sides. Then, on the annular shape of the magnetic yokes 33, the end face 31a of the first leg 31 is joined to the inner circumferential surface 33a. The end face 32a of the second leg 32 is joined to the inner circumferential surface 33a of the magnetic yokes 33.

[0064] Thus, the annular core 3 forms a closed ring shape. Furthermore, the end face 31a of the first leg 31 and the end face 32a of the second leg 32 are the faces that extend orthogonally to the longitudinal axis among the six faces constituting the first leg 31 and the second leg 32. The inner circumferential surface 33a of the magnetic yoke 33 is the face facing the end face 31a of the first leg 31 and the end face 32a of the second leg 32.

[0065] The first leg 31 and the yoke 33 are joined by an adhesive, and the second leg 32 and the yoke 33 are joined by an adhesive. Therefore, a bonding layer 34 formed by the adhesive is located between the first leg 31 and the yoke 33, and between the second leg 32 and the yoke 33. The bonding layer 34 functions as an air gap corresponding to the film thickness.

[0066] Here, the total length Ly of the yoke 33 is set to be shorter than the distance Da between the first leg 31 and the second leg 32. The total length Ly of the yoke 33 is the length along the horizontal axis. The distance Da between the first leg 31 and the second leg 32 is the distance along the horizontal axis, which includes the entire end face 31a of the first leg 31 and the entire end face 32a of the second leg 32, and extends from the far end of the end face 31a of the first leg 31 to the far end of the end face 32a of the second leg 32.

[0067] Therefore, the end face 31a of the first leg 31 and the end face 32a of the second leg 32 are divided into exposed regions 31c and 32c that extend beyond the yoke 33 and are exposed, and joint regions 31d and 32d that are joined to the inner peripheral surface 33a of the yoke 33 via the joint layer 34. The end face 33b of the yoke 33 is located in a recessed position relative to the outer surface 31b of the first leg 31 and the outer surface 32b of the second leg 32. The end face 33b of the yoke 33 is a surface that extends orthogonally to the transverse axis, while the outer surfaces 31b and 32b are surfaces that extend along the longitudinal axis and are away from the center of the annular core 3.

[0068] 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 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 33.

[0069] Furthermore, the exposed area 31c of the end face 31a of the first leg 31 and the inner peripheral surface 33a of the yoke 33 are arranged in the same plane, excluding the bonding layer 34; similarly, the exposed area 32c of the end face 32a of the second leg 32 and the inner peripheral surface 33a of the yoke 33 are arranged in the same plane, excluding the bonding layer 34. In other words, the magnetic circuit through which the magnetic flux generated near the end faces 31a and 32a can pass is not within the annular core 3.

[0070] Here, the ratio of the width of the exposed regions 31c and 32c in the lateral direction to the width of the end faces 31a and 32a in the lateral axis direction is preferably 5% or more and 30% or less. If this range is met, then even compared to the case where the recess 35a is not formed, there is no decrease in inductance value throughout the entire current range, or even if there is a decrease, it is controlled within 5% in the range of 100 A or less.

[0071] Furthermore, when a current of 200 A or more flows through the reactor 1, the ratio of the width of the exposed regions 31c and 32c in the lateral direction to the width of the end faces 31a and 32a in the lateral axis direction can be 60% or more and 75% or less. If this range is met, the inductance value when flowing with a current of 200 A or more is increased compared to the case where the recess 35a is not formed. When a current of 250 A or more flows through the reactor 1, the ratio of the width of the exposed regions 31c and 32c in the lateral direction to the width of the end faces 31a and 32a in the lateral axis direction can be 45% or more and 75% or less. If this range is met, the inductance value when flowing with a current of 250 A or more is increased compared to the case where the recess 35a is not formed. However, even outside this range, an inductance value comparable to that obtained without the recess 35a can still be achieved.

[0072] Figure 3 This is a plan view showing the overall structure of reactor 1. Reactor 1 also includes a core-coating resin 4. The core-coating resin 4 coats a ring-shaped core 3. The coil 2 is embedded in the core-coating resin 4 and is electrically insulated from the ring-shaped core 3.

[0073] The core-coated resin 4 is a molded product that maintains a certain shape and possesses insulation and heat resistance. For example, the core-coated resin 4 uses epoxy resin, unsaturated polyester resin, urethane resin, bulk molding compound (BMC), polyphenylene sulfide (PPS), polybutylene terephthalate (PBT), or a composite thereof as the material.

[0074] A fastening portion 5 is formed on the core-coating resin 4, which is used to fix the reactor body 1a, which includes 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 box that houses the reactor body 1a using the fastening portion 5. The fastening portion 5 has a screw hole, which is aligned with a screw hole on the side of a support such as the metal box, through which a bolt is inserted. The fastening portion 5 is provided, for example, in the recesses 35a formed at the four corners of the annular core 3.

[0075] In this reactor 1, the recess 35a exposes a portion of the end face 31a of the first leg 31 and a portion of the end face 32a of the second leg 32. The first leg 31 and the second leg 32 are flux generating portions to which the coil 2 is wound. Furthermore, the end face 31a of the first leg 31 and the end face 32a of the second leg 32 have little or no guaranteed distance to the end of the coil 2.

[0076] Furthermore, the exposed area 31c of the end face 31a of the first leg 31 and the inner peripheral surface 33a of the yoke 33 are arranged in the same plane, excluding the bonding layer 34; similarly, the exposed area 32c of the end face 32a of the second leg 32 and the inner peripheral surface 33a of the yoke 33 are arranged in the same plane, excluding the bonding layer 34. In other words, the magnetic circuit through which the magnetic flux generated near the end faces 31a and 32a can pass is not within the annular core 3.

[0077] Therefore, the magnetic flux generated near the exposed area 31c of the first leg 31 and the exposed area 32c of the second leg 32 is oblique to the axis of the coil 2 at an angle close to right angle and cannot reach the joint area 31d and the joint area 32d. Instead, it leaks outward from the exposed area 31c of the first leg 31 and the exposed area 32c of the second leg 32 into the recess 35a, and then enters the end face 33b of the yoke 33.

[0078] Next to the exposed area 31c of the first leg 31 is a joining area 31d, and next to the exposed area 32c of the second leg 32 is a joining area 32d. These joining areas 31d and 32d are joined to the magnetic yoke 33. However, a joining layer 34 exists within the joining areas 31d and 32d. The joining layer 34 has high magnetic resistance. Therefore, the magnetic flux through the joining areas 31d and 32d is suppressed. Consequently, more magnetic flux leaks outward from the exposed areas 31c of the first leg 31 and 32c of the second leg 32, and then enters the end face 33b of the magnetic yoke 33.

[0079] In this way, the recess 35a, which is formed as a part of the end face 31a of the first leg 31 and the end face 32a of the second leg 32, functions as an air gap. Therefore, the recess 35a becomes a spare position for the fastening part 5 and the like in the reactor 1 without having a significant impact on the inductance value in the high current region.

[0080] Here, Figure 4 (a) is a diagram showing the magnetic flux distribution outside the reactor 1 as observed through simulation. Figure 4(b) is a diagram showing the external magnetic flux distribution of the comparison object observed through simulation. The comparison object has a recess 35a at the corner of the toroidal core 3. However, the depth of the recess 35a in the longitudinal direction of the comparison object is shallower than the length in the longitudinal direction of the yoke 33. That is, the recess 35a is formed by punching notches at only two locations in the four corners of the yoke 33 corresponding 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 to the recess 35a.

[0081] In the diagram, the area enclosed by a circle is the recess 35a. (For example...) Figure 4 (a) and Figure 4 As can be seen from the comparison in (b), the magnetic flux in the reactor 1 leaks out from the recess 35a. On the other hand, it can be seen that the magnetic flux in the reactor of the comparison object hardly leaks out from the recess 35a. That is, it can be seen that the recess 35a, which is formed as a part of the end face 31a of the first leg 31 and the end face 32a of the second leg 32, functions as an air gap. Thus, it is known that the recess 35a becomes a spare position for the installation of fasteners 5, etc. in the reactor 1 without having a significant impact on the inductance value in the high current region.

[0082] Next, the relationship between the current and inductance value in the reactor 1 of the first embodiment is shown in Table 1 below. Reactors 1 of the following embodiments were prepared: Embodiment 1 with 5% exposed area 31c and 32c; Embodiment 2 with 15% exposed area 31c and 32c; Embodiment 3 with 30% exposed area 31c and 32c; Embodiment 4 with 45% exposed area 31c and 32c; Embodiment 5 with 60% exposed area 31c and 32c; and Embodiment 6 with 75% exposed area 31c and 32c. Comparative Example 1 with 0% exposed area 31c and 32c and Comparative Example 2 with 100% exposed area 31c and 32c were also prepared. Currents up to 250 A were passed through the reactors 1 of Embodiments 1 to 6 and the reactors of Comparative Examples 1 and 2, and the inductance values ​​were measured. Furthermore, the reactor 1 of Examples 1 to 6 and the reactor of Comparative Examples 1 and 2 have end faces 31a and 31b with a total width of 13.5 mm in the transverse direction.

[0083] (Table 1)

[0084]

[0085] In Table 1 above, the ratio of exposed area 31c and exposed area 32c refers to the ratio of the width of exposed area 31c and exposed area 32c in the horizontal direction to the width of end face 31a and end face 32a in the horizontal axis direction. The ratios of exposed area 31c and exposed area 32c are the same. A ratio of 0% for exposed area 31c and exposed area 32c indicates that the recess 35a is not formed. A ratio of 100% for exposed area 31c and exposed area 32c indicates that only the corner of the first leg 31 is in contact with the corner of the yoke 33, and only the corner of the second leg 32 is in contact with the corner of the yoke 33.

[0086] Furthermore, the percentage decrease in each inductance value of Examples 1 to 6 relative to the inductance value of Comparative Example 1 was calculated based on the values ​​in Table 1, and is shown in Table 2 below. In Table 2, positive values ​​indicate inductance values ​​lower than those of Comparative Example 1, and negative values ​​indicate inductance values ​​higher than those of Comparative Example 1.

[0087] (Table 2)

[0088]

[0089] As shown in Tables 1 and 2 above, compared to Comparative Example 1 where the proportion of exposed regions 31c and 32c is 0%, the initial inductance values ​​in Examples 1 to 6, where the proportion of exposed regions 31c and 32c is 5% to 75%, are lower. The initial inductance value is the value without overlap of direct current. The reason for the decrease in initial inductance value is that a recess 35a exists in the portion that forms a magnetic circuit through which magnetic flux passes. The larger the proportion of exposed regions 31c and 32c, the greater the decrease in initial inductance value. This is because a larger portion that forms a magnetic circuit through which magnetic flux passes is removed.

[0090] However, it can be confirmed that in Examples 1 to 3, where the ratio of exposed area 31c to exposed area 32c is 5 to 30%, even compared with Comparative Example 1, where the ratio of exposed area 31c to exposed area 32c is 0%, there is no decrease in inductance value in the entire current range, including the overlap of DC current being zero, or even if there is a decrease, it is controlled within 5% in the range of less than 100 A.

[0091] When a current of 150 A is passed through reactor 1, it can be confirmed that not only in Examples 1 to 3, but also in Examples 4 to 6, where the proportion of exposed areas 31c and 32c is 45% or more, the difference in inductance value compared to the reactor of Comparative Example 1 is reduced to a single-digit percentage. Furthermore, when a current of 200 A or more is passed through reactor 1, it can be confirmed that the inductance value of reactor 1 in Examples 1 to 6 is almost the same as or greater than the inductance value of the reactor of Comparative Example 1.

[0092] That is, the recess 35a, which is formed by exposing a portion of the end face 31a of the first leg 31 and a portion of the end face 32a of the second leg 32, functions as an air gap, and it can be confirmed that the influence on the inductance value is minimal in the high current region. Therefore, as long as the recess 35a is formed in such a way that a portion of the end face 31a of the first leg 31 and a portion of the end face 32a of the second leg 32, which are the flux generating parts, is exposed, a larger amount of free space can be used without impairing the performance of the reactor 1 in the high current region, thereby achieving further miniaturization and weight reduction of the reactor 1.

[0093] Furthermore, when a current of 200 A or more is passed through reactor 1, it can be confirmed that the inductance value of reactor 1 in Examples 5 and 6, where the ratio of exposed area 31c to exposed area 32c is 60% or more and 75% or less, exceeds the inductance value of reactor 1 in Comparative Example 1. Additionally, when a current of 250 A or more is passed through reactor 1, it can be confirmed that the inductance value of reactor 1 in Examples 4 to 6, where the ratio of exposed area 31c to exposed area 32c is 45% or more and 75% or less, exceeds the inductance value of reactor 1 in Comparative Example 1. This indicates that the formation of the recess 35a improves the performance of reactor 1 depending on the formation range of the recess 35a and the area with high current.

[0094] The following facts were confirmed: Comparative Example 2, in which the ratio of exposed area 31c to exposed area 32c is 100%, is no less effective than Examples 1 to 6 in terms of inductance value in the high current region, but the initial inductance value is significantly lower than that of Examples 1 to 6.

[0095] Furthermore, in the reactor 1 formed in this way, the annular core 3 is formed by a quadrangular prism-shaped I-shaped core, such as the magnetic yoke 33, the first leg 31 and the second leg 32, which results in high productivity and thus can also reduce the cost of the reactor 1.

[0096] (Second Implementation)

[0097] Figure 5 This is a plan view showing the detailed structure of the annular core 3 in the second embodiment. (See attached image.) Figure 5 As shown, the annular core 3 includes a pair of U-shaped blocks 36 and two leg blocks 37. In the U-shaped blocks 36, legs 36a and 36b protrude from both ends of the inner circumferential surface 33a of the yoke 33, thus forming a U-shape. The pair of U-shaped blocks 36 are positioned face-to-face with legs 36a facing each other and leg blocks 36b facing each other, and leg blocks 37 are positioned between legs 36a and between legs 36b. Therefore, the annular core 3 has a closed magnetic circuit in an annular shape.

[0098] The end of coil 2 is attached to the legs 36a and 36b of U-shaped block 36. Therefore, the leg 36a of U-shaped block 36 is part of the magnetic flux generating part and serves as the end side of the first leg 31, and the leg 36b of U-shaped block 36 is part of the magnetic flux generating part and serves as the end side of the second leg 32.

[0099] On the U-shaped block 36, two corners are removed to form recesses 35b. The recesses 35b reach the junction B between the yoke 33 and the leg 36a, and the junction B between the yoke 33 and the leg 36b. That is, the end face 31a of the leg 36a and the end face 32a of the leg 36b have exposed areas 31c and 32c that extend into the recesses 35b. Furthermore, the exposed area 31c of the end face 31a of the leg 36a is aligned with the inner circumferential surface 33a of the yoke 33, and the exposed area 32c of the end face 32a of the leg 36b is aligned with the inner circumferential surface 33a of the yoke 33. In other words, the magnetic circuit through which the magnetic flux generated near the end faces 31a and 32a can pass is not within the annular core 3.

[0100] Furthermore, the recess 35b does not reach the plane formed by extending the inner side surface 31e of the leg 36a and the plane formed by extending the inner side surface 32e of the leg 36b. Moreover, the inner side surface 31e and the inner side surface 32e are the opposite surfaces to the outer side surface 31b and the outer side surface 32b.

[0101] In the reactor 1 of the second embodiment, the leg 36a is seamlessly connected to the yoke 33, and there is no bonding layer 34 next to the exposed area 31c. Furthermore, in the reactor 1, the leg 36b is seamlessly connected to the yoke 33, and there is no bonding layer 34 next to the exposed area 32c.

[0102] However, in the reactor 1, the recess 35b also exposes the end faces 31a and 32a of the legs 36a and 36b, which are the ends of the magnetic flux generating part. Furthermore, the exposed area 31c of the end face 31a of the leg 36a is aligned with the inner peripheral surface 33a of the yoke 33, and the exposed area 32c of the end face 32a of the leg 36b is aligned with the inner peripheral surface 33a of the yoke 33.

[0103] Therefore, the magnetic flux generated near the exposed areas 31c and 32c is oblique to the axis of the coil 2 at an angle close to right angle and cannot reach the yoke 33 in the annular core 3. Instead, it leaks outward from the exposed areas 31c of the first leg 31 and the exposed areas 32c of the second leg 32 into the recess 35b, and then enters the end face 33b of the yoke 33.

[0104] In this way, the recess 35b in the reactor 1 also functions as an air gap. Therefore, the recess 35b becomes a spare position for setting the fastening part 5, etc. in the reactor 1, and has little impact on the inductance value in the high current region, and does not reduce the performance of the reactor 1.

[0105] Here, reactors 1 of embodiments 7 to 11 are prepared, with recesses 35b, exposed areas 31c, and exposed areas 32c formed on the U-shaped block 36 in proportions of each embodiment. In reactors 1 of embodiments 7 to 11, the yoke portion 33 and the leg portion 36a, as well as the yoke portion 33 and the leg portion 36b, are seamlessly connected as one unit. That is, reactors 1 of embodiments 7 to 11 are reactors 1 of the second embodiment. In addition, reactors of comparative examples 3 and 4 are prepared, in which an annular core 3 is formed by the U-shaped block 36 but the proportions of exposed areas 31c and exposed areas 32c are 0% and 100%, respectively.

[0106] The inductance values ​​were measured for each current flowing through reactor 1 of Examples 7 to 11, and reactors of Comparative Examples 3 and 4 up to 250 A. The results are shown in Table 3 below.

[0107] (Table 3)

[0108]

[0109] Furthermore, the percentage decrease in each inductance value of Examples 7 to 11 relative to the inductance value of Comparative Example 3 was calculated based on the values ​​in Table 3, and is shown in Table 4 below. In Table 4, positive values ​​indicate inductance values ​​lower than those of Comparative Example 1, and negative values ​​indicate inductance values ​​higher than those of Comparative Example 1.

[0110] (Table 4)

[0111]

[0112] As shown in Tables 3 and 4 above, compared with Comparative Example 3 where the proportion of exposed regions 31c and 32c is 0%, the initial inductance values ​​in Examples 7 to 11, where the proportion of exposed regions 31c and 32c is 15% to 75%, are lower. However, it can be confirmed that Examples 7 and 8, where the proportion of exposed regions 31c and 32c is 30% or less, do not show a decrease in inductance value over the entire current range, including when the overlap of DC current is zero, even compared with Comparative Example 3 where the proportion of exposed regions 31c and 32c is 0%, or even if there is a decrease, it is controlled within 4% of 100 A or less.

[0113] When a current of 200 A is passed through reactor 1, it can be confirmed that: not only in Examples 7 and 8, but also in Examples 9 to 11, where the proportion of exposed areas 31c and 32c is 45% or more, the difference in inductance value compared to the reactor of Comparative Example 3 is reduced to a single-digit percentage. Furthermore, when a current of 250 A or more is passed through reactor 1, it can be confirmed that: the inductance value of reactor 1 in Examples 7 to 11 is almost the same as or greater than the inductance value of the reactor of Comparative Example 3.

[0114] Furthermore, when a current of 250 A or more is passed through reactor 1, it can be confirmed that the inductance value of reactor 1 in Embodiments 10 and 11, where the ratio of exposed area 31c to exposed area 32c is 60% or more and 75% or less, exceeds the inductance value of reactor 1 in Comparative Example 3. That is, it indicates that in reactor 1 of Embodiment 2, the formation of recess 35b also improves the performance of reactor 1 depending on the formation range of recess 35b and the area with high current.

[0115] Thus, even if the legs 36a and 36b of the U-shaped block 36 at the end of the flux generating section are exposed to the recess 35b, the inductance value of the reactor 1 will not be damaged in the high current region, and the recess 35b can be made larger, thereby achieving miniaturization and weight reduction of the reactor 1.

[0116] Here, reactors 1 of Embodiments 4 and 9, where the exposed areas 31c and 32c account for 45%, are prepared. The reactor 1 of Embodiment 4 is the reactor 1 of the first embodiment, with a bonding layer 34 serving as a magnetic reluctance disposed next to the exposed areas 31c and 32c of end faces 31a and 32a. The reactor 1 of Embodiment 9 is the reactor 1 of the second embodiment, without the bonding layer 34 serving as a magnetic reluctance next to the exposed areas 31c and 32c of end faces 31a and 32a.

[0117] Currents ranging from 0 A to 285 A were passed through reactors 1 in Examples 4 and 9 in increments of 15 A, and the inductance values ​​were measured. The relationship between the current and inductance values ​​of reactors 1 in Examples 4 and 9 obtained through measurement is shown in Table 5 below. Furthermore, the results in Table 5 are shown in... Figure 6 In the chart.

[0118] (Table 5)

[0119]

[0120] As shown in Table 5 above and Figure 6As shown, 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 range of currents above 120 A, the inductance value of the reactor 1 of Example 4 exceeds the inductance value of the reactor 1 of Example 9.

[0121] Furthermore, comparing the reactors 1 of Embodiments 2 and 7, where the exposed areas 31c and 32c account for 15%, the reactor 1 of Embodiment 2 has the same inductance value as that of Embodiment 7 at 240 A, but its inductance value exceeds that of Embodiment 7 at 255 A and above. Comparing the reactors 1 of Embodiments 3 and 8, where the exposed areas 31c and 32c account for 30%, the reactor 1 of Embodiment 3 has the same inductance value as that of Embodiment 8 at 210 A, but its inductance value exceeds that of Embodiment 8 at 225 A and above.

[0122] Comparing the reactors 1 of Embodiments 5 and 10, where the exposed areas 31c and 32c account for 60%, the inductance value of reactor 1 in Embodiment 5 exceeds that of Embodiment 10 when the inductance is 105 A or higher. Comparing the reactors 1 of Embodiments 6 and 11, where the exposed areas 31c and 32c account for 75%, the inductance value of reactor 1 in Embodiment 6 exceeds that of Embodiment 11 when the inductance is 75 A or higher.

[0123] Therefore, it is confirmed that when the bonding layer 34, which serves as a magnetoresistive layer, is arranged next to the exposed areas 31c and 32c of end faces 31a and 32a, more magnetic flux leaks outward from the exposed areas 31c of the first leg 31 and 32c of the second leg 32, and then enters the end face 33b of the yoke portion 33. Therefore, the recess 35a becomes a space for providing the fastening portion 5, etc., within the reactor 1 without further affecting the inductance value in the high-current region.

[0124] (Effects)

[0125] As described above, the reactor 1 in each embodiment has a toroidal core 3 and a coil 2. The toroidal core 3 has legs such as a first leg 31 and a second leg 32 for mounting the coil 2 to generate magnetic flux, or legs 36a and 36b of a U-shaped block 36. Additionally, the toroidal core 3 has a pair of yokes 33 separately disposed on the end faces of these legs, forming a closed magnetic circuit together with the legs. Recesses 35a or 35b are formed at the four corners of the toroidal core 3, and a portion of the end face 31a or 32a of the magnetic flux generating part or the end of the leg serving as the magnetic flux generating part is exposed to the recesses 35a or 35b. Therefore, the influence of the recesses 35a and 35b on the inductance value is reduced in the high current region, allowing the reactor 1 to be miniaturized and lightweight without compromising its performance.

[0126] Furthermore, the yoke 33 has an inner circumferential surface 33a on the annular core 3. The yoke 33 connects to the leg on the inner circumferential surface 33a. The exposed areas 31a and 32a of the end faces of the legs exposed to the recesses 35a and 35b are approximately on the same plane as the inner circumferential surface 33a of the yoke 33. Therefore, the magnetic circuit through which the magnetic flux generated near the end faces 31a and 32a can pass is not within the annular core 3, and the magnetic flux generated near the end faces 31a and 32a must temporarily leak to the outside through the recesses 35a and 35b. Thus, the recesses 35a and 35b efficiently function as air gaps.

[0127] Typically, such a reactor 1 is designed such that the total length Ly of the yoke 33 along the direction in which the legs are arranged is shorter than the distance from the end face 31a to the end face 32a of one of the two legs, including the entire end face 31a and end face 31b of the two outermost legs. Thus, the two outermost legs are positioned such that a portion of the end face 31a and end face 32a extends beyond the yoke 33.

[0128] In this way, the recesses 35a and 35b are defined by the end face 33b of the yoke portion 33 and the exposed areas 31c and 32c extending beyond the yoke portion 33 in the end faces 31a and 32a of the two outermost legs. Furthermore, the exposed areas 31c and 32c on the end faces 31a and 32a of the legs of the recesses 35a or 35b, excluding the bonding layer 34, are substantially on the same plane as the inner peripheral surface 33a of the yoke portion 33.

[0129] In the reactor 1 formed in this way, the annular core 3 is formed by a quadrangular prism-shaped I-shaped core, such as the magnetic yoke 33, the first leg 31 and the second leg 32, which results in high productivity and can also reduce the cost of the reactor 1.

[0130] Furthermore, in each embodiment, an annular core 3 with two legs has been described as an example, but it is not limited to this; an annular core 3 with three or more legs may also be used. For example, an annular core 3 in the shape of θ, consisting of three legs (one middle leg and two outer legs) arranged in parallel and connected by two ring shapes, may also be used. In the θ-shaped annular core 3, a recess 35a or a recess 35b is formed such that the end faces 31a and 32a of the two outer legs protrude from the yoke portion 33. An annular core 3 with four or more legs may also be used, in which case a recess 35a or a recess 35b is formed such that the end faces 31a and 32a of the two outermost legs protrude from the yoke portion 33.

[0131] Furthermore, a fastening part 5 is provided within the recess 35a or 35b for fastening the reactor body 1a, which includes the annular core 3 and the coil 2, to other parts. This reduces the size of the reactor 1. Other structural parts of the reactor 1, external electronic components, electronic circuits, mechanical elements, and other components, not limited to the fastening part 5, may also be arranged within the recess 35a or 35b.

[0132] Furthermore, a bonding layer 34, formed by an adhesive, joins the end faces 31a and 32a of the two outermost legs to the yoke portion 33. This allows more magnetic flux to leak out from the end faces 31a and 32a, improving the function of the recess 35a as an air gap. Consequently, the influence of the recess 35a on the inductance value in the high-current region is further reduced.

[0133] Furthermore, 5% to 30% of the end faces 31a and 32a of the two outermost legs are exposed from the yoke portion 33. In this case, the inductance value is not impaired throughout the entire current range, even compared to the case where the recesses 35a and 35b are not formed. Moreover, other structural parts of the reactor 1, external electronic parts, electronic circuits, mechanical elements, and other various structural parts other than the reactor 1 can be arranged in the recesses 35a and 35b, not limited to the fastening portion 5, thereby achieving miniaturization and weight reduction of the reactor 1.

[0134] Furthermore, more than 60% and less than 75% of the end faces 31a and 32a of the two outermost legs are exposed from the yoke portion 33. As a result, when a current of 200 amperes or more is flowing through, the recess 35a can actually increase the inductance of the reactor 1, while also enabling the miniaturization and weight reduction of the reactor 1.

[0135] Furthermore, 45% to 75% of the end faces 31a and 32a of the two outermost legs are exposed from the yoke 33. As a result, when a current of 250 amperes or more is flowing through, the recess 35a can actually increase the inductance of the reactor 1, while also enabling the miniaturization and weight reduction of the reactor 1.

[0136] Furthermore, the present invention is not limited to the embodiments described herein, but also includes other embodiments shown below. Additionally, the present invention includes configurations that combine all or any of the embodiments described herein and other embodiments described below. Moreover, these embodiments can be omitted, substituted, or modified in various ways without departing from the scope of the invention, and such modifications are also included in the present invention.

Claims

1. A reactor having a toroidal core and a coil, characterized in that, The annular iron core has: Two or more legs are provided for mounting the coil to generate magnetic flux; A pair of magnetic yokes are separately disposed on both ends of the leg, forming a closed magnetic circuit together with the leg; Recesses are formed at the four corners of the annular core, exposing a portion of the end faces of the two outermost legs; The body comprises the annular iron core and the coil; and A fastening part is disposed within the recess to fasten the body to other parts.

2. The reactor according to claim 1, characterized in that, The magnetic yoke has an inner circumferential surface in the annular iron core. The magnetic yoke is connected to the leg on the inner circumferential surface. The area on the end face of the leg exposed to the recess is in the same plane as the inner circumferential surface of the magnetic yoke.

3. The reactor according to claim 1 or 2, characterized in that, The total length of the magnetic yoke along the direction in which the legs are arranged is shorter than the distance from the outermost end of one of the two outermost legs to the outermost end of the other leg. A portion of the end face of the two outermost legs extends beyond the magnetic yoke. The recess is defined by the end face of the magnetic yoke and the area extending beyond the magnetic yoke from the end faces of the two outermost legs.

4. The reactor according to claim 1 or 2, characterized in that, It has a bonding layer formed by an adhesive, which bonds the end faces of the two outermost legs to the magnetic yoke.

5. The reactor according to claim 1, characterized in that, Includes a core-coating resin, wherein the core-coating resin coats the annular core. The fastening portion is formed in the resin coating of the iron core.

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