CN110942902A

CN110942902A - Reactor and method for manufacturing same

Info

Publication number: CN110942902A
Application number: CN201910898877.XA
Authority: CN
Inventors: 大岛泰雄; 有间浩; 近藤润二; 莲正利; 伊藤清太; 高城直辉
Original assignee: Tamura Corp
Current assignee: Tamura Corp
Priority date: 2018-09-25
Filing date: 2019-09-23
Publication date: 2020-03-31

Abstract

The invention provides a reactor capable of suppressing leakage magnetic flux from a joint portion between a leg portion and a yoke portion of a core, and a manufacturing method thereof. The reactor of the present invention includes: a core (2) having a plurality of legs (21) and a pair of yokes (22) disposed at both ends of the legs (21); and a coil (3) wound around the leg (21). At least either the leg (21) or the yoke (22) comprises a composite magnetic material containing magnetic powder and resin, and the leg (21) and the yoke (22) are joined by the resin of the composite magnetic material.

Description

Reactor and method for manufacturing same

Technical Field

The present invention relates to a reactor including a core containing magnetic powder and resin, and a method for manufacturing the same.

Background

Reactors are used in various applications, such as Office Automation (OA) equipment, solar power generation systems, drive systems for hybrid vehicles, electric vehicles, and fuel cell vehicles. This reactor includes: an annular core including a magnetic material; a resin member covering an outer periphery of the annular core; and a coil wound around a part of an outer periphery of the annular core via the resin member. The annular core includes, for example: a pair of legs extending in a straight line; and a pair of yokes arranged at both ends of the leg portions and connecting the pair of leg portions. The annular core is formed by joining the pair of legs to the pair of yokes. When electric power is supplied from an external power supply, a current flows through the coil to generate magnetic flux, thereby forming a magnetic circuit in the annular core.

[ Prior art documents ]

[ patent document ]

[ patent document 1] Japanese patent No. 5408272 publication

Disclosure of Invention

[ problems to be solved by the invention ]

A magnetic gap of a predetermined width may be provided at a joint portion between the leg portion and the yoke portion forming the annular core. The gap prevents a decrease in the inductance of the reactor on the high current side. Examples of the gap include a case where a gap material such as a spacer is used, and a case where an air gap is provided. However, if there is a gap, leakage magnetic flux is generated from the gap. If the leakage magnetic flux is generated, there is a problem that the leakage magnetic flux adversely affects peripheral devices of the reactor.

Therefore, there is a method of joining the leg portion and the yoke portion directly with an adhesive without providing a gap member or an air gap. However, even when the leg portion and the yoke portion are joined directly by the adhesive, joining without generating any gap is impossible, and when viewed from a microscopic level, a gap is generated, thereby generating a leakage magnetic flux.

Further, when the leg portion and the yoke portion of the annular core are molded using materials having different magnetic permeability, magnetic flux is easily concentrated at the joint portion between the leg portion and the yoke portion. That is, the magnetic flux is easily saturated at the joint between the leg and the yoke, and the possibility of generating the leakage magnetic flux is high. The coil is wound around the leg portion and thus exists in the vicinity of the joint portion. The leakage magnetic flux is induced current to the coil, and increases ac loss of the reactor.

Therefore, by separating the joint portion of the coil, the leg portion, and the yoke portion, an increase in ac loss can be reduced. As a method of separating the joint from the coil, it is also conceivable to separate the coil from the joint by making the leg of the wound coil longer than the coil. However, in the case of this method, the leg portion needs to be longer than the coil, which leads to an increase in size of the reactor.

In addition, in the conventional reactor, since a part of the pot core, the PQ core, the E core, or the like is made of resin, there is a problem that heat of the coil is easily accumulated in the core. Therefore, a reactor having improved heat dissipation has been required.

The present invention has at least one of the following first, second, and third objects.

A first object of the present invention is to provide a reactor that can suppress leakage magnetic flux from a joint portion between a leg portion of a core and a yoke portion, and a method for manufacturing the same.

A second object of the present invention is to provide a reactor that can reduce ac loss while maintaining miniaturization.

A third object of the present invention is to provide a reactor having improved heat dissipation.

[ means for solving problems ]

In order to achieve the first object, a reactor of the present invention includes: a core having a plurality of legs and a pair of yokes arranged at both ends of the plurality of legs; and a coil wound around the leg, wherein at least one of the leg and the yoke includes a composite magnetic material containing magnetic powder and resin, and the leg and the yoke are joined by the resin of the composite magnetic material.

In a method of manufacturing a reactor according to the present invention, the reactor includes a core including a plurality of leg portions and yoke portions arranged at both end portions of the plurality of leg portions, and either the leg portion or the yoke portion includes a composite magnetic material including magnetic powder and resin, and the method includes: a mounting step of mounting the coil on the resin member; a filling step of filling the resin member with the clay-like composite magnetic material; a pressurizing step of pressurizing the composite magnetic material injected into the resin member; and a curing step of curing the resin.

In order to achieve the second object, a reactor of the present invention includes: a core having a plurality of legs and a pair of yokes arranged at both ends of the plurality of legs; and a coil wound around the leg portion, the leg portion including a composite magnetic material containing a magnetic powder and a resin, the yoke portion having: a first member comprising the composite magnetic material; and a second member made of a material different from the composite magnetic material, wherein the first member is disposed on a side where the leg portion is disposed, is integrally formed with the leg portion, is joined to the second member, and has a magnetic permeability greater than that of the leg portion and the first member.

In order to achieve the third object, a reactor of the present invention includes: and a core having a center leg around which a coil is wound, outer legs disposed outside the center leg, and yoke portions disposed at both end portions of the center leg and both end portions of the outer legs, wherein the center leg and the outer legs include a composite resin material containing magnetic powder and resin, and form an opening portion for exposing the coil from the core, and the opening ratio of the opening portion is set to be more than 60% when the entire circumference of the coil is housed in the core and 0% when the entire circumference of the coil is exposed from the core and 100%.

[ Effect of the invention ]

According to the present invention, it is possible to provide a reactor that can suppress leakage magnetic flux from a joint portion between a leg portion of a core and a yoke portion.

According to the present invention, a reactor can be provided which can reduce ac loss while maintaining miniaturization.

According to the present invention, it is possible to provide a reactor in which heat of a coil is suppressed from being accumulated inside a core by setting the aperture ratio of an opening for exposing the coil from the core to be more than 60%, thereby improving heat dissipation.

Drawings

Fig. 1 is a perspective view showing the entire configuration of a reactor according to a first embodiment.

Fig. 2 is an exploded perspective view showing the entire configuration of the reactor of the first embodiment.

Fig. 3 is a flowchart for explaining a method of manufacturing the reactor of the first embodiment.

Fig. 4 is a perspective view showing the entire configuration of a reactor according to modification 1.

Fig. 5 is an exploded perspective view showing the entire configuration of a reactor according to modification 1.

Fig. 6 is an exploded perspective view showing the entire configuration of a reactor according to a second embodiment.

Fig. 7 is a plan view of the core of the second embodiment enlarged.

Fig. 8 is an exploded perspective view showing the entire configuration of a reactor according to modification 2.

Fig. 9 is a perspective view of the third embodiment.

Fig. 10 is an exploded perspective view of the third embodiment.

Fig. 11 is a side sectional view with the resin member omitted in the third embodiment.

Fig. 12 is a side view for explaining the effect of the third embodiment.

Fig. 13 is a perspective view of the fourth embodiment.

Fig. 14 is an exploded perspective view of the fourth embodiment.

Fig. 15 is a side sectional view in which the resin member is omitted in the fourth embodiment.

Fig. 16 is a diagram for explaining the shape of a yoke according to the fourth embodiment.

Fig. 17 is a diagram for explaining the shape of a yoke according to the fourth embodiment.

Fig. 18 is a diagram for explaining the shape of a yoke according to the fourth embodiment.

Fig. 19 is a diagram for explaining the shape of a yoke according to the fourth embodiment.

Fig. 20 is a diagram for explaining the shape of a yoke according to the fourth embodiment.

Fig. 21 is a perspective view of the fifth embodiment.

Fig. 22 is an exploded perspective view of the fifth embodiment.

Fig. 23 is a main part perspective view of a modification of the fifth embodiment.

Fig. 24 is an exploded perspective view of a main part of a modification of the fifth embodiment.

Fig. 25 is a main part perspective view of a modification of the fifth embodiment.

Fig. 26 is a main-part exploded perspective view of a modification of the fifth embodiment.

Fig. 27 is a graph showing inductance values of example 4, comparative example 5, and comparative example 6.

Fig. 28 is a graph of the ac loss when the thickness of the first member is changed with respect to the entire yoke portion.

Fig. 29 is a graph of inductance values when the thickness of the first member is changed with respect to the entire yoke portion.

[ description of symbols ]

1: electric reactor

2: core

21: foot part

22 a: first member

22 b: second member

22: yoke part

23: middle foot

24: outer foot

25: yoke part

25 a: extension part

25b, 25 c: chamfered part

26. 28, 30: opening part

27a, 27b, 27 c: yoke (X shape)

29: opening part

3: coil

4: resin member

41: straight line part

42: connecting part

5: dead space

Detailed Description

(first embodiment)

(constitution)

Hereinafter, a reactor according to the present embodiment will be described with reference to the drawings. Fig. 1 is a perspective view showing the entire configuration of a reactor according to a first embodiment. Fig. 2 is an exploded perspective view showing the entire configuration of the reactor of the first embodiment. The positional relationship of the respective constituent elements described here does not reflect the positional relationship when the reactor 1 is mounted on an actual machine.

The reactor 1 is an electromagnetic component that converts electric energy into magnetic energy and stores and discharges the magnetic energy, and is used for voltage increase and decrease, and the like. The reactor 1 of the present embodiment includes: core 2, coil 3, resin member 4.

The core 2 includes a plurality of leg portions 21 and a pair of yoke portions 22 arranged at both end portions of the plurality of leg portions 21. In the present embodiment, the number of the leg portions 21 is two, and the shape thereof is a cylindrical shape. The outer peripheral surface of the leg portion 21 is covered with the resin member 4. The two leg portions 21 are arranged such that the cylindrical axes are parallel. At least one of the leg portion 21 and the yoke portion 22 is a metal composite core (MC core) including a composite magnetic material containing magnetic powder and resin. In the present embodiment, the leg portion 21 includes a composite magnetic material.

The outer surfaces of the MC core are all non-sliding surfaces. The MC core is formed by placing a composite magnetic material containing magnetic powder and resin in a container having a predetermined shape and curing the resin. In other words, pressing as in the molding of the powder magnetic core is not an essential condition in the molding of the MC core. Further, even in the case of pressing, unlike a powder magnetic core in which magnetic powder covered with an insulating film is press-molded by several tons (ton) to several tens tons, pressing force is sufficient to apply a low pressure of several kg to several tens kg in order to increase the density of the MC core.

Since the MC core is not pressurized or pressurized at a low pressure in this manner, the sliding surface having a plurality of linear traces formed on the core surface cannot be formed by the movement of the die and the core while rubbing against each other. Therefore, the entire outer peripheral surface of the MC core becomes a non-sliding surface. In addition, although the magnetic powder is deformed by the powder magnetic core because the magnetic powder is pressurized by several tons to several tens tons, the magnetic powder is not deformed because the MC core is also pressurized by several kg to several tens kg at the time of pressurization.

As the magnetic powder, soft magnetic powder can be used, and in particular: fe powder, Fe — Si alloy powder, Fe — Al alloy powder, Fe — Si — Al alloy powder (sendust), amorphous metal powder (amorphous powder), or a mixed powder of two or more of these powders. As the Fe-Si alloy powder, for example, Fe-6.5% Si alloy powder and Fe-3.5% Si alloy powder can be used. The average particle diameter (D50) of the soft magnetic powder is preferably 20 to 150. mu.m. In the present specification, the "average particle diameter" refers to D50, i.e., a median particle diameter, unless otherwise specified.

The resin is mixed with the magnetic powder, and the magnetic powder is retained. The resin may be a thermosetting resin, an ultraviolet-curable resin, or a thermoplastic resin. The thermosetting resin may be used: phenol (phenol) resins, epoxy resins, unsaturated polyester resins, polyurethane (polyurethane), diallyl phthalate (diallyl phthalate) resins, silicone resins, and the like. The ultraviolet curable resin may be: urethane acrylate (urethane acrylate), epoxy acrylate (epoxy acrylate), acrylate, and epoxy resins. The thermoplastic resin is preferably a resin having excellent heat resistance such as polyimide (polyimide) or fluororesin. The viscosity of the epoxy resin cured by adding the curing agent can be adjusted by the amount of the curing agent added.

The resin is preferably contained in an amount of 3 to 5 wt% based on the magnetic powder. If the content of the resin is less than 3 wt%, the bonding force of the magnetic powder is insufficient and the mechanical strength of the core is lowered. When the content of the resin is more than 5 wt%, magnetic powder or the like cannot be held without a gap, and the density of the core is lowered and the magnetic permeability is lowered.

The yoke 22 may be a powder magnetic core, a ferrite (ferrite) magnetic core, or a laminated steel plate. In the present embodiment, a dust core is used as the yoke portion 22. The yoke 22 is a block-shaped core. The end surface of the yoke 22 opposite to the leg 21 is preferably flat. As will be described later, the powder magnetic core constituting the yoke portion 22 serves as an extrusion member for extruding the composite magnetic material. Therefore, the reason for this is that the composite magnetic material can be pressed with a uniform force by flattening the end surface of the yoke portion 22 on the side opposite to the leg portion 21.

The yoke 22 preferably has a magnetic permeability greater than that of the leg 21. Since the yoke 22 has a magnetic permeability greater than that of the leg 21, the magnetic flux generated by the leg 21 around which the coil 3 is wound can be captured more.

The yokes 22 are disposed at both ends of the leg 21. The yoke 22 is joined to the end of the leg 21 by the resin of the composite magnetic material of the leg 21. In other words, the leg 21 and the yoke 22 are joined without using an adhesive or the like. The yoke 22 is seamlessly and continuously joined with the leg 21. The yoke 22 is impregnated with the resin of the composite magnetic material constituting the leg 21. Specifically, the resin of the composite magnetic material is impregnated into the powder magnetic core. Further, the end surface of the yoke 22 joined to the leg 21 has a plurality of fine irregularities. The size of the irregularities is, for example, about several tens of micrometers.

The irregularities may be irregularities formed by powder such as magnetic powder when a compact such as a dust core or ferrite is press-molded or may be irregularities formed by roughening the surface of the compact by filing or sandblasting after molding. In the case of laminated steel sheets, the irregularities may be formed by a step caused by lamination, or may be formed on the surface of the laminated formed body. The resin of the composite magnetic material enters the concave portion of the unevenness.

As shown in fig. 2, the coil 3 has two. The coil 3 includes two conductive members insulated and coated with enamel (enamel) or the like. The conductive member may use a copper wire or an aluminum wire. In this embodiment, a copper wire is used. The coil 3 has a cylindrical shape with both ends of a copper wire wound therearound open. Lead wires are led out from both end portions of the coil 3. The two coils 3 are arranged such that the winding directions of the coils 3 are parallel. The inner peripheral surface of the coil 3 is covered with a resin member 4. That is, the coil 3 is wound around the leg 21 via the resin member 4.

In the present embodiment, the coil 3 has a cylindrical shape, but the shape of the coil 3 is not limited thereto, and may have a rectangular shape. The number of coils 3 is not limited to two, and may be one or three or more.

The resin member 4 covers the periphery of the core 2 and insulates the core 2 from the coil 3. Examples of the resin constituting the resin member 4 include an epoxy resin, an unsaturated polyester resin, a urethane resin, a Bulk Molding Compound (BMC), a Polyphenylene Sulfide (PPS), a Polybutylene Terephthalate (PBT), and the like.

As shown in fig. 2, the resin member 4 is divided into two parts. The resin member 4 divided into two parts has a substantially U-shape. The resin member 4 includes a pair of linear portions 41 on which the coil 3 is mounted, and a coupling portion 42 that couples the pair of linear portions 41. In the resin member 4, the ends of the straight portions 41 are joined together with an adhesive or the like to integrally form the resin member 4 divided into two parts.

The linear portion 41 has a cylindrical shape. Leg portions 21 are disposed on the inner peripheral surface of linear portion 41. The leg portion 21 including the composite magnetic material and the linear portion 41 are integrally molded with a resin of the composite magnetic material. That is, the leg portion 21 and the linear portion 41 contact each other without a gap therebetween. Further, the coil 3 is wound around the outer peripheral surface of the linear portion 41. The coupling portion 42 has two openings having substantially the same diameter as the inner periphery of the linear portion 41 at the end surface connecting the linear portions 41. In the coupling portion 42, an end surface opposite to the end surface connecting the linear portions 41 is open. The shaped yoke 22 is inserted from the opening. That is, the size of the opening is substantially the same as the yoke 22.

(method of manufacturing reactor)

A method for manufacturing the reactor 1 according to the present embodiment will be described with reference to the drawings. As shown in fig. 3, the method for manufacturing a reactor according to the present embodiment includes (1) a mounting step, (2) a filling step, (3) a pressing step, and (4) a curing step.

(1) Mounting process (step S01)

The mounting step is a step of mounting the coil 3 on the resin member 4. The linear portions 41 of the resin member 4 are inserted from openings at both ends of the coil 3. An adhesive is applied to the end portions of the linear portions 41, and the linear portions 41 of the resin members 4 inserted from the opening of the coil are joined in the coil 3. That is, the resin member 4 divided into two parts is integrated.

(2) Filling process (step S02)

The filling step is a step of filling the inside of the linear portion 41 with a composite magnetic material containing magnetic powder and resin. In this step, first, a clay-like composite magnetic material is produced by mixing a magnetic powder with a resin. The clay-like composite magnetic material attains a desired viscosity by the viscosity of the added resin. The viscosity of the resin added when mixing with the magnetic powder is preferably 50 to 5000 mPas. When the viscosity is less than 50mPa · s, the resin does not entangle with the magnetic powder during mixing, the magnetic powder and the resin are easily separated in the container, and unevenness occurs in the density or strength of the core. If the viscosity exceeds 5000mPa · s, the viscosity excessively increases, and for example, the resin formed between the first magnetic powder enters, and the second magnetic powder cannot fill the gap, and the density of the core decreases, and the magnetic permeability decreases.

The mixing of the magnetic powder and the resin may be performed automatically using a prescribed mixer, or manually. The mixing time is not particularly limited, and may be, for example, 2 minutes. By mixing the magnetic powder with the resin in this manner, a clay-like composite magnetic material can be obtained. The clay-like composite magnetic material is filled from the opening of the coupling portion 42 into the linear portion 41 by a predetermined amount.

(3) Pressing step (step S03)

The pressing step is a step of pressing the composite magnetic material with the powder magnetic core constituting the yoke portion 22. The powder magnetic core is formed into a block shape in advance. The powder magnetic core is formed by providing unevenness on the surface where the composite magnetic material constituting the yoke portion 22 is joined. The powder magnetic core is inserted into each of the coupling portions 42 so that the surface having the irregularities is in contact with the composite magnetic material. Then, the composite magnetic material filled in the linear portion 41 is pressed by the powder magnetic core inserted into each coupling portion 42. That is, the dust core constituting the yoke portion 22 functions as a pressing member. The composite magnetic material is pressed from both ends of the linear portion 41. The time for pressing the composite magnetic material may be appropriately changed depending on the content or viscosity of the resin, and is, for example, 10 seconds. By pressing with the dust core, the composite magnetic material is expanded into the internal shape of the linear portion 41, and voids contained in the composite magnetic material are reduced, thereby increasing the apparent density.

The pressure for extruding the composite magnetic material is preferably 6.3kg/cm²The above. If the value is less than the above range, the extrusion pressure is small and the effect of increasing the apparent density is small. In addition, even if the value is above, preferably 15.7kg/cm²The following. This is because, even if the extrusion is performed beyond the above value, the effect of increasing the apparent density is small. When the pressing force exceeds the above value, only the resin is pressed, and the insulation between the magnetic powders is deteriorated.

(4) Curing step (step S04)

The curing step is a step of curing the resin contained in the composite magnetic material filled into the leg portion 21 in the filling step. When the resin filled in the leg portion 21 is cured by drying, the drying environment may be an atmospheric environment. The drying time may be appropriately changed depending on the type, content, drying temperature, and the like of the resin, and may be, for example, 1 to 4 hours, but is not limited thereto. The drying temperature may be appropriately changed depending on the kind, content, drying time, and the like of the resin, and may be, for example, 85 to 150 ℃. Further, the drying temperature is the temperature of the drying environment.

The curing of the resin is not limited to drying, and the curing method differs depending on the type of the resin. For example, if the resin is a thermosetting resin, the resin is cured by heating, and if the resin is an ultraviolet-curable resin, the resin is cured by irradiating the molded body with ultraviolet rays.

The curing step may be repeated a plurality of times to cure the molded article at a predetermined temperature for a predetermined time. For example, in the case where the resin is cured by drying, the drying temperature and the drying time may be varied for each repetition of plural times.

In the present embodiment, the leg portion 21 is made of a composite magnetic material, but the yoke portion 22 may be made of a composite magnetic material. In this case, the core constituting the leg portion 21 is molded in advance, and in the mounting step, the linear portion 41 is inserted into the coil 3, and the molded leg portion 21 is inserted into the linear portion 41. In the filling step, the clay-like composite magnetic material is filled from the opening of the coupling portion 42. Thereafter, in the pressing step, the composite magnetic material filled in the coupling portion 42 is pressed by using a pressing member, and the resin contained in the composite magnetic material is cured in the curing step.

(Effect)

The reactor 1 of the present embodiment includes: a core 2 having a plurality of legs 21 and a pair of yokes 22 disposed at both ends of the plurality of legs 21; and a coil 3 wound around the core 2, wherein either the leg portion 21 or the yoke portion 22 comprises a composite magnetic material containing magnetic powder and resin, and the leg portion 21 and the yoke portion 22 are joined to each other by the resin of the composite magnetic material. Accordingly, since the leg portions 21 and the yoke portion 22 are joined together seamlessly and continuously, there is no gap at the joint portion, and leakage magnetic flux generated from the joint portion between the leg portions 21 and the yoke portion 22 can be suppressed.

The leg 21 and the yoke 22 are bonded to each other by a resin composite magnetic material. In other words, the resin replaces an adhesive or the like, and there is no need to use an adhesive or the like for joining the leg portion 21 and the yoke portion 22. Therefore, the step of joining the leg portion 21 and the yoke portion 22 with an adhesive or the like can be reduced, and the cost of the portion not using an adhesive or the like can be reduced.

The yoke portion 22 has a magnetic permeability greater than that of the leg portion 21. This allows the yoke 22 to capture more magnetic flux generated by the leg 21 around which the coil 3 is wound. Therefore, leakage magnetic flux from the yoke 22 can be suppressed.

In the leg portion 21 or the yoke portion 22 not including the composite magnetic material, there are irregularities on the end surface where the leg portion 21 and the yoke portion 22 are joined. Thus, the resin contained in the composite magnetic material enters the irregularities, and therefore, the leg portion 21 and the yoke portion 22 can be more firmly joined by the anchor effect. Therefore, since the joining is made more tight, leakage magnetic flux can be suppressed.

The leg portion 21 and the linear portion 41 are integrally formed without a gap by the composite magnetic material constituting the leg portion 21. Accordingly, since the inner periphery of the linear portion 41 is formed larger than the leg portion 21 without considering the dimensional tolerance between the leg portion 21 and the linear portion 41, the reactor 1 can be downsized. In addition, the leg portion 21, that is, the core 2 can be increased by an amount corresponding to the gap between the leg portion 21 and the linear portion 41, which is a portion where the linear portion 41 is formed larger than the leg portion 21 in consideration of dimensional tolerance, so that the characteristics of the reactor 1 can be improved.

The method for manufacturing a reactor according to the present embodiment includes: a mounting step of mounting the coil 3 on the resin member 4; a filling step of filling the resin member 4 having the coil 3 mounted thereon with a composite magnetic material; a pressurizing step of pressurizing the composite magnetic material injected into the resin member 4 via the yoke portion 22; and a curing step of curing the resin. That is, the composite magnetic material constituting the leg portion 21 is pressurized using the core 2 constituting the yoke portion 22 as a pressing member.

This eliminates the need to separately prepare a pressing member, and reduces the number of parts for manufacturing the reactor 1. In addition, the joining of the leg portions 21 and the yoke portion 22 is performed by the resin contained in the composite magnetic material, and a step of applying an adhesive is not required for joining the leg portions 21 and the yoke portion 22, so that the manufacturing process of the reactor 1 can be reduced.

(modification 1)

A reactor according to modification 1 will be described with reference to the drawings. Fig. 4 is a perspective view showing the entire configuration of a reactor according to modification 1. Fig. 5 is an exploded perspective view showing the entire configuration of a reactor according to modification 1. As shown in fig. 4 and 5, in the first embodiment, the coil is wound around all the leg portions, but in modification 1, the leg portions 21 around which the coil 3 is not wound are provided.

Specifically, there are three legs 21. The three leg portions 21 are arranged in parallel to the winding axis direction of the coil 3. Of the three legs 21 arranged in parallel, arranged in the middle is a middle leg 23 around which the coil 3 is wound. Disposed on both sides of the center leg 23 are outer legs 24 around which the coil 3 is not wound. The middle leg 23 and the two outer legs 24 are MC cores.

The yoke 22 connects the middle leg 23 and the two outer legs 24. The yoke 22 is a dust core. Yoke 22 is joined to the ends of middle leg 23 and outer leg 24 by a resin of a composite magnetic material of middle leg 23 and outer leg 24. The yoke 22, the middle leg 23 and the outer leg 24 are joined seamlessly and continuously.

As described above, in modification 1, the number of joint portions between the yoke portion 22 and the leg portion 21 is two more than that in the first embodiment. That is, in the first embodiment, there are four joint portions in total at both ends of the two leg portions 21. On the other hand, in modification 1, there are six joint portions in total, at both ends of the center leg 23 and at both ends of the two outer legs 24.

When these six joint portions are joined by an adhesive or the like, a gap is generated in each joint portion, and a large amount of leakage magnetic flux is generated. However, in the present modification, the middle leg 23 and the outer leg 24 are joined to the yoke 22 by a resin composite magnetic material. That is, the joint portions of the middle leg 23, the outer leg 24 and the yoke 22 are joined together seamlessly and continuously without any gap. Therefore, the leakage magnetic flux generated from the respective joint portions of the center leg 23, the outer leg 24, and the yoke 22 can be suppressed. In this way, when the number of joining portions between the leg portions 21 and the yoke portion 22 is large, leakage magnetic flux can be more significantly suppressed.

(second embodiment)

A reactor 1 of a second embodiment is explained with reference to the drawings. Fig. 6 is an exploded perspective view showing the entire configuration of a reactor according to a second embodiment. In the present embodiment, the yoke 22 is different from the first embodiment in that it includes two kinds of members, and the entire configuration of the reactor is the same as that of fig. 1. Note that the same configurations and the same functions as those of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

The yokes 22 are disposed at both ends of the leg 21. The yoke 22 captures and passes through the magnetic flux generated by the leg. The yoke 22 comprises two components. Namely, the first member 22a and the second member 22b are provided. The end surfaces of the first member 22a and the second member 22b perpendicular to the winding axis direction of the coil 3 have substantially the same shape. The end surface of the first member 22a having the substantially same shape is joined to the end surface of the second member 22b to form the yoke 22.

The first member 22a is provided on the side where the leg portion 21 is arranged, and is integrally formed with the leg portion 21. The first member 22a includes a composite magnetic material constituting the leg portion 21. That is, the leg portion 21 is integrally formed with a part of the yoke portion 22. In this way, the first member 22a constituting the yoke 22 connects the pair of legs 21. The second member 22b comprises a material different from the composite magnetic material. The second member 22b may be made of a powder magnetic core, ferrite, or laminated steel plate. In the present embodiment, the second member 22b uses a dust core.

Fig. 7 is a plan view of the core 2 enlarged. As shown in fig. 7, the thickness L1 in the reel direction of the coil 3 of the first member is smaller than the thickness in the reel direction of the second member 22 b. The ratio of the thickness L1 in the winding axis direction of the coil of the first member 22a to the thickness L2 in the winding axis direction of the coil of the entire yoke 22 may be 0.5 or less. In other words, the thickness in the reel direction of the coil of the first member 22a may be equal to or less than the thickness in the reel direction of the coil 3 of the second member 22 b. If the ratio exceeds 0.5, the inductance at a low current value becomes low, and the ripple of the current at the time of low current operation becomes large. Therefore, if the ratio exceeds 0.5, the iron loss of the reactor may increase or the rotating operation may become unstable.

The first member 22a and the second member 22b are joined by the resin of the composite magnetic material of the first member 22 a. That is, the resin of the clay-like composite magnetic material is cured, and the first member 22a and the second member 22b are joined to each other. In other words, the first member 22a and the second member 22b are joined without using an adhesive or the like. The first member 22a is seamlessly and continuously joined with the second member 22 b. The resin of the composite magnetic material constituting the first member 22a is impregnated into the second member 22 b.

The end surface of the second member 22b on the opposite side to the first member is preferably flat. In the present embodiment, the second member 22b is a block-shaped core. As described later, the second member 22b is a pressing member that presses the composite magnetic material. Therefore, the reason for this is that the composite magnetic material can be pressed with a uniform force by flattening the end surface of the second member 22b on the opposite side to the first member 22 a.

Further, a plurality of fine irregularities are present on the end surface of the second member 22b joined to the first member 22 a. The size of the irregularities is, for example, about several tens of micrometers. The irregularities may be irregularities formed by powder such as magnetic powder when a compact such as a powder magnetic core or ferrite is press-molded or may be irregularities formed by roughening the surface of the compact by filing or sandblasting after molding. In the case of laminated steel sheets, the irregularities may be formed by a step caused by lamination, or may be formed on the surface of the laminated formed body. The resin of the composite magnetic material enters the concave portion of the unevenness.

The second member 22b preferably has a magnetic permeability larger than the magnetic permeability of the first member 22a and the leg 21. By making the magnetic permeability of the second member 22b larger than the magnetic permeability of the first member 22a and the leg portion 21, it is possible to capture more magnetic flux generated by the leg portion 21 around which the coil 3 is wound.

(method of manufacturing reactor)

A method for manufacturing the reactor 1 of the present embodiment will be described. In the method of manufacturing the reactor 1 of the present embodiment, (1) the mounting step, (3) the pressing step, and (4) the curing step are basically the same as those of the first embodiment, and therefore, description thereof will be omitted, and only the different (2) filling step will be described.

(2) Filling process

The filling step is a step of filling the inside of the linear portion 41 with a composite magnetic material containing magnetic powder and resin. In this step, first, a clay-like composite magnetic material is produced by mixing magnetic powder with a resin. The clay-like composite magnetic material attains a desired viscosity by the viscosity of the added resin. The viscosity of the resin added when mixing with the magnetic powder is preferably 50 to 5000 mPas. When the viscosity is less than 50mPa · s, the resin does not entangle with the magnetic powder during mixing, the magnetic powder and the resin are easily separated in the container, and unevenness occurs in the density or strength of the core. If the viscosity exceeds 5000mPa · s, the viscosity excessively increases, and for example, the resin formed between the first magnetic powder enters, and the second magnetic powder cannot fill the gap, and the density of the core decreases, and the magnetic permeability decreases.

The mixing can be performed automatically using a prescribed mixer, or manually. The mixing time is not particularly limited, and may be, for example, 2 minutes. By mixing the magnetic powder with the resin in this manner, a clay-like composite magnetic material can be obtained. The clay-like composite magnetic material is filled from the opening of the coupling portion 42 into the linear portion 41 by a predetermined amount. At this time, the volume of the linear portion 41 is larger than that of the connection portion 42. The thickness of the first member 22a in the direction of the winding axis of the coil 3 is determined according to the amount of the composite magnetic material filled in the coupling portion 42. In this way, the leg portion 21 is integrally formed with the first member 22 a.

(action)

Next, the flow of magnetic flux will be described. When a current flows through the coil 3, a magnetic flux is generated from the coil 3. The generated magnetic flux flows through the leg 21 containing the magnetic powder. The magnetic flux flowing through the leg 21 passes through the yoke 22 connected to the leg 21, thereby forming a magnetic circuit closed in the annular core 3.

Here, for example, in the case where the first member is not present, the magnetic flux will flow at the shortest distance, and thus, more flows to the inner peripheral side of the annular core. Therefore, the core is magnetically saturated on the inner peripheral side of the annular core. When the core is magnetically saturated, the magnetic permeability becomes 1 as in the air, and therefore a part of the magnetic flux leaks to the coil side. The leakage of magnetic flux through the coil causes ac losses in the coil.

However, in the present embodiment, since the first member 22a is disposed, even if the second member 22b is saturated and generates the leakage magnetic flux, the first member 22a can serve as a passage of the leakage magnetic flux, and the leakage magnetic flux can be prevented from passing through the coil 3. In particular, the magnetic flux flows according to the one having the higher magnetic permeability. That is, by making the magnetic permeability of the second member 22b larger than that of the first member 22a, the second member 22b is saturated first. Then, the leakage magnetic flux generated by the saturation of the second member 22b passes through the first member 22a joined to the second member 22 b. In this way, the first member functions as: the leakage magnetic flux generated from the second member 22b is prevented from passing through the coil 3 to generate the alternating current loss of the coil 3.

In the present embodiment, the core 2 is formed by joining the first member 22a and the second member 22 b. That is, the distance from the joint to the coil 3 is separated by the thickness L1 of the first member 22 a. Even if leakage magnetic flux occurs from the joint portion, the distance from the joint portion to the coil 3 is increased, and therefore, the influence of the leakage magnetic flux on the coil 3 can be suppressed. Further, the joint portion of the first member 22a and the second member 22b is joined by the resin of the composite magnetic material, and is joined seamlessly and continuously. Therefore, the joint portions are joined without a gap, and therefore generation of leakage magnetic flux itself can be suppressed.

In addition, the magnetic permeability of the second member 22b is larger than that of the first member 22 a. That is, the second member 22b flows more magnetic flux than the first member 22 a. In other words, the magnetic flux flowing through the first member 22a disposed near the coil 3 is small. By reducing the magnetic flux flowing through the first member 22a, it is possible to suppress generation of leakage magnetic flux from the first member 22a arranged in the vicinity of the coil 3. Further, since the distance between the joint of the first member 22a and the second member 22b and the coil is increased, the influence on the coil 3 can be reduced.

(Effect)

As described above, the reactor 1 of the present embodiment includes: a core 2 having a plurality of legs 21 and a pair of yokes 22 disposed at both ends of the plurality of legs 21; and a coil 3 wound around the leg 21. The leg 21 includes a composite magnetic material containing magnetic powder and resin. The yoke 22 has: a first member 22a containing the same composite magnetic material as the leg portion 21; and a second member 22b comprising a material different from the composite magnetic material. The first member 22a is disposed on the side where the leg portion 21 is disposed, and is integrally molded with the leg portion 21, and the first member 22a and the second member 22b are joined. The magnetic permeability of the second member 22b is greater than the magnetic permeability of the leg 21 and the first member 22 a.

As a result, the magnetic flux flowing through the second member 22b increases, and the second member 22b is magnetically saturated before the first member 22 a. Then, the leakage magnetic flux generated by the magnetic saturation of the second member 22b passes through the first member 22a, and thus the first member 22a prevents the leakage magnetic flux from passing through the coil. Therefore, the influence of the leakage magnetic flux on the coil 3 can be suppressed, and the ac loss of the reactor 1 can be reduced. Further, the coil 3 can be separated from the joint portion between the first member 22a and the second member 22b without extending the length of the leg portion 21 in the reel direction of the coil 3, and therefore, miniaturization can be maintained.

The coil 3 is wound around the leg 21, and the ratio of the thickness L1 in the winding axis direction of the coil 3 of the first member 22a to the thickness L2 in the winding axis direction of the coil 3 of the entire yoke 22 is 0.5 or less. This can reduce the ac loss and maintain the initial inductance value (L value) satisfactorily.

The second member 22b has a magnetic permeability greater than that of the leg 21 and the first member 22 a. Thus, the second member 22b flows magnetic flux more easily than the first member 22a, and thus the magnetic flux flows more through the second member 22 b. That is, the magnetic flux flowing through the first member 22a provided on the side where the coil 3 is arranged can be reduced. Therefore, the magnetic flux is suppressed from being saturated at the first member 22 a. As a result, leakage magnetic flux generated from the first member 22a can be suppressed, and ac loss of the reactor 1 can be reduced.

Further, since the distance between the coil 3 and the joint portion of the first member 22a and the second member 22b is increased, even if leakage magnetic flux is generated from the joint portion, the influence on the coil 3 can be reduced, and the ac loss of the reactor 1 can be reduced.

In the yoke 22, the first member 22a and the second member 22b are joined by the resin of the composite magnetic material of the first member 22 a. That is, the first member 22a and the second member 22b are joined seamlessly and continuously. Accordingly, the first member 22a and the second member 22b can be joined without a gap, and therefore leakage magnetic flux from the joint portion can be suppressed, and the ac loss of the reactor 1 can be reduced.

(modification 2)

A reactor according to modification 2 will be described with reference to the drawings. The overall configuration diagram of the reactor of modification 2 is the same as that of fig. 4. Fig. 8 is an exploded perspective view showing the entire configuration of a reactor according to modification 2. As shown in fig. 4 and 8, in the second embodiment, the coil 3 is wound around all the leg portions, but in modification 2, there are leg portions 21 around which the coil 3 is not wound.

Specifically, there are three legs 21. The three leg portions 21 are arranged in parallel to the winding axis direction of the coil 3. Of the three legs 21 arranged in parallel, arranged in the middle is a middle leg 23 around which the coil 3 is wound. Disposed on both sides of the center leg 23 are outer legs 24 around which the coil 3 is not wound. The middle leg 23 and the two outer legs 24 are MC cores comprising a composite magnetic material.

The first member 22a is integrally formed with the middle leg 23 and the two outer legs 24. The second member 22b is joined to the first member 22a by the resin of the composite magnetic material of the first member 22 a. That is, the first member 22a and the second member 22b are joined seamlessly and continuously.

As described above, modification 2 has the middle leg 23 and the two outer legs 24, and includes three legs 21, one more than the second embodiment. When the number of the leg portions 21 is increased, the joint portion between the leg portion 21 and the yoke 22 is increased, and there is a possibility that a larger amount of leakage magnetic flux is generated.

However, in the present modification, the middle leg 23, the outer leg 24, and the first member 22a are integrally formed of a composite magnetic material. Then, the first member 22a is joined to the second member 22b by the resin of the composite magnetic material. That is, the joint of the first member 22a and the second member 22b, which are different in material, is separated from the coil 3. Therefore, the influence of the leakage magnetic flux generated from the joint portion on the coil 3 can be reduced. In this way, when the number of the leg portions 21 is increased and the joint portions of the leg portions 21 and the yoke portion 22 are increased, the ac loss of the reactor 1 can be reduced more significantly.

(third embodiment)

A reactor 1 of a third embodiment is explained with reference to the drawings. Fig. 9 is a perspective view showing the entire configuration of the reactor 1 of the third embodiment, and fig. 10 is an exploded perspective view showing the entire configuration of the reactor 1 of the third embodiment.

(outline of constitution)

The reactor 1 is an electromagnetic component that converts electric energy into magnetic energy and stores and discharges the magnetic energy, and is used for voltage increase and decrease, and the like. As shown in fig. 9 and 10, a reactor 1 according to the present embodiment includes: core 2, coil 3, resin member 4. The core 2 includes a middle leg 21A and an outer leg 21B as two legs 21, and a pair of yokes 22 disposed at both ends of the legs 21. The core 2 is covered with the resin member 4, and the coil 3 is mounted so as to be sandwiched between the middle leg 21A and the outer leg 21B of the core 2 in a state where the core 2 and the coil 3 are insulated from each other by the resin member 4.

As shown in fig. 10, the leg portions 21 include a middle leg 21A and an outer leg 21B disposed on the outer side (lower side in the drawing) of the middle leg 21A. The middle leg 21A and the outer leg 21B are disposed to face each other in the vertical direction in fig. 10 so that the central axes thereof are parallel to each other. As shown in fig. 11, the middle leg 21A is disposed on the upper side, and the outer leg 21B is disposed on the lower side. The leg 21 is covered with the resin member 4. The leg 21 is a metal composite core (MC core) made of a composite magnetic material containing magnetic powder and resin.

The center leg 21A includes a cylindrical member having a circular or elliptical cross section, but is not limited thereto. When the cross-sectional shape of the middle leg 21A is an ellipse, the diameter of the ellipse is a diameter orthogonal to the arrangement direction of the middle leg 21A and the outer leg 21B arranged in parallel. That is, as shown in fig. 10, when the middle leg 21A and the outer leg 21B are disposed to face each other in the vertical direction, the diameter of the ellipse of the middle leg 21A is a diameter extending in the left-right direction. The coil 3 is wound around the center leg 21A via the resin member 4. In the reactor 1, the center leg 21A around which the coil 3 is wound serves as a magnetic flux generating portion. The outer leg 21B includes the following members: has a width dimension greater than the diameter of the middle leg 21A and equal to or less than the diameter of the outer peripheral portion of the coil 3.

In the outer leg 21B, an end surface (upper surface side in fig. 10) facing the middle leg 21A is a curved surface recessed downward in the drawing, and an opposite surface (lower surface side in fig. 10) is a flat surface. When the reactor 1 is placed horizontally, the flat surface side of the outer leg 21B serves as a mounting surface of the reactor 1. Further, when the reactor 1 is placed vertically, an end surface facing the outside of the yoke portion 22 becomes an installation surface of the reactor 1.

Fig. 11 is a side sectional view in which the resin member 4 is omitted in the third embodiment. As shown in fig. 11, the coil 3 is attached to the center leg 21A of the core 2, and at this time, an opening 29 (shown by a broken line) for exposing the coil 3 from the outer leg 21B of the core 2 is formed. The aperture ratio of the opening 29 is 0% when the entire circumference of the coil 3 is housed inside the core 2, and is 100% when the entire circumference of the coil 3 is exposed from the core 2, in this case, the aperture ratio of the opening 29 is set to exceed 60% in the present embodiment, and more preferably, the aperture ratio of the opening 29 is set to 67% or more.

As shown in fig. 9 and 10, the yokes 22 are disposed at both ends of the leg 21. The yoke 22 captures and passes through the magnetic flux generated by the leg 21. The yoke 22 is disposed so that its vertical direction is orthogonal to the longitudinal direction of the leg 21. The end surface of the yoke 22 facing outward is exposed and not covered with the resin member 4, and the outer circumferential surface of the yoke 22 is covered with the resin member 4.

As shown in fig. 10, the yoke 22 includes two members. Namely, the first member 22a and the second member 22b are provided. The end surfaces of the first member 22a and the second member 22b perpendicular to the winding axis direction of the coil 3 have substantially the same shape. The end surface of the first member 22a having the substantially same shape is joined to the end surface of the second member 22b to form the yoke 22.

The first member 22a is provided on the side where the leg portion 21 is arranged, and is integrally formed with the leg portion 21. The first member 22a includes a composite magnetic material constituting the leg portion 21. That is, the core 2 of the present embodiment is a block-shaped core in which the leg portions 21 are integrally formed with a part of the yoke portion 22. In this way, the first member 22a constituting the yoke 22 connects the pair of legs 21, i.e., the middle leg 21A and the outer leg 21B. The second member 22b comprises a material different from the composite magnetic material. As the second member 22b, a powder magnetic core, ferrite, or laminated steel plate can be used. In the present embodiment, the second member 22b uses a dust core and ferrite.

The yoke 22 includes a substantially hexagonal member in which the following are combined: a semi-circular portion connected to a diameter portion of the middle leg 21A; a trapezoidal portion having a diameter portion of the middle leg 21A as a short side; and a rectangular portion connected to the trapezoidal portion with a long side opposite to the short side. The diameter of the upper semicircular portion of the yoke 22 is the same as the diameter of the center leg 21A. The yoke 22 is joined to an end surface of the leg 21 perpendicular to the winding axis direction of the coil 3. As described above, in the core 2, (the first member 22a of) the yoke 22 is connected to the middle leg 21A and the outer leg 21B, but at this time, the semicircular portion of the yoke 22 coincides with the circumferential portion of the middle leg 21A, and the rectangular portion of the yoke 22 coincides with the cross section of the outer leg 21B.

(action and Effect)

The operation and effect of the third embodiment are as follows.

(1) The reactor 1 of the third embodiment includes a core 2, the core 2 including a middle leg 21A around which the coil 3 is wound, an outer leg 21B disposed outside the middle leg 21A, and yoke portions 22 disposed at both ends of the middle leg 21A and both ends of the outer leg 21B, and including a composite resin material containing magnetic powder and resin, and forming an opening 29 for exposing the coil 3 from the core 2. The aperture ratio is 0% when the entire circumference of the coil 3 is housed inside the core 2, and is 100% when the entire circumference of the coil 3 is exposed from the core 2, and the aperture ratio of the opening 29 is 67%. In the third embodiment, since the core 2 includes the composite resin material containing the magnetic powder and the resin, the shape of the core 2 in which the aperture ratio of the opening 29 is increased can be easily manufactured.

According to the third embodiment described above, when the coil 3 is attached to the core 2, the area of the coil 3 exposed from the core 2 is increased by setting the aperture ratio of the opening 29 of the core 2 to 67%. Therefore, the heat of the coil 3 is hard to gather inside the core 2, and the heat is easily dissipated into the air. Therefore, the reactor 1 can exert excellent heat dissipation performance. Here, the temperature of the coil 3 in example 1 to which the present embodiment is applied is compared with those in comparative examples 1 to 3.

As shown in table 1, the materials of the cores of comparative examples 1 to 3 and example 1 are as follows. All legs were MC cores (Fe-Si alloy), the yoke portions were magnetic powder cores (Fe-Si-Al alloy) in comparative examples 1 and 2, and ferrite (Mn-Zn system) in comparative examples 3 and 1. That is, the core 2 of comparative example 3 and example 1 is the same in type and material. The aperture ratios of the openings 29 of the cores 2 of comparative example 1, comparative example 2, comparative example 3, and example 1 were 50%, 60%, and 67%, respectively.

[ Table 1]

For example, the heat of the coil 3 in comparative examples 1 to 3 and example 1 was measured by setting the energization condition to current 27A and frequency 20kHz and the cooling condition to natural cooling without forced cooling. In this case, the temperatures of the coil 3 in comparative examples 1 to 3 were 85.9 ℃, 76.9 ℃ and 68.7 ℃. In contrast, in example 1 to which the third embodiment is applied, the temperature of the coil 3 was 58.9 ℃. That is, in comparative example 3 and example 1 in which the type and material of the core 2 are the same, in example 1 in which the aperture ratio of the opening 29 is increased to 67% when only the aperture ratio of the opening 29 of the core 2 is different, the temperature of the coil 3 can be decreased by 9.8 ℃.

(2) In the third embodiment, the first member 22a of the yoke 22 is integrally molded with the leg portion 21, and the composite resin material of the first member 22a and the composite resin materials of the middle leg 21A and the outer leg 21B serve as adhesives for connecting the yoke 22 and the leg portion 21. That is, the leg 21 and the yoke 22 are joined by the composite magnetic material. In other words, the composite magnetic material does not need to use an adhesive or the like for joining the leg portion 21 and the yoke portion 22, instead of an adhesive or the like. Therefore, the step of joining the leg portion 21 and the yoke portion 22 with an adhesive or the like can be reduced, and the cost of the portion not using an adhesive or the like can be reduced.

(3) The yoke 22 of the third embodiment includes: a first member 22a including a composite magnetic material constituting the leg portion 21; and a second member 22b containing a material having a magnetic permeability greater than that of the composite magnetic material, such as a dust core. That is, in the yoke 22, the second member 22b has a magnetic permeability greater than that of the leg 21 and the first member 22a, and therefore the second member 22b flows magnetic flux more easily than the first member 22a, and the magnetic flux flows more through the second member 22 b. Therefore, the magnetic flux flowing through the first member 22a provided on the side where the coil 3 is arranged can be reduced. Therefore, the magnetic flux is suppressed from being saturated at the first member 22 a. As a result, the leakage magnetic flux generated from the first member 22a can be suppressed, and the ac loss generated in the coil 3 can be reduced. This can suppress heat generation of the coil 3 in accordance with heat dissipation from the opening 29 having a high aperture ratio.

(4) When the core 2 is entirely composed of a block-shaped core, the inductance characteristic is good, but the gap is increased, which may cause deterioration of the loss. On the other hand, if the core 2 is entirely composed of MC cores, the gap becomes small, but the permeability of the core becomes low, and the inductance characteristic may deteriorate.

In contrast, in the core 2 of the third embodiment, the leg portion 21 is an MC core including a composite magnetic material, and is a block-shaped core including the second member 22b as a dust core in the yoke portion 22. Therefore, a good inductance characteristic can be obtained while realizing no gap.

(5) In the third embodiment, the core 2 has one middle leg 21A and one outer leg 21B, respectively, the cross-sectional shape of the middle leg 21A is circular or elliptical, and the outer leg 21B is set to be larger than the diameter of the middle leg 21A and to be a width dimension equal to or smaller than the diameter of the outer peripheral portion of the coil 3. In such a core 2, by making the width dimension of the outer leg 21B larger than the diameter of the middle leg 21A, the thickness dimension (the dimension in the vertical direction orthogonal to the width dimension) of the outer leg 21B can be suppressed while securing the cross-sectional area of the yoke portion.

This can contribute to downsizing of the core 2 in the thickness dimension of the outer leg 21B. In addition, since the width of the outer leg 21B of the core 2 is set to be equal to or smaller than the diameter of the outer peripheral portion of the coil 3, the core 2 can be limited to the projected area of the coil 3 (the area when the coil 3 is viewed from directly above), and the core 2 can be prevented from being increased in size. Further, the outer leg 21B is larger than the diameter of the middle leg 21A and has a width equal to or smaller than the diameter of the outer peripheral portion of the coil 3, so that the outer leg 21B can be disposed on the installation surface with a sufficient installation area.

(6) In the third embodiment, the yoke 22 having a substantially hexagonal shape is expanded outward from the diameter portion of the center leg 21A, and the outer leg 21B is aligned with the bottom surface portion (portion including the long side portion on the lower side of the horizontally long rectangle) of the yoke 22. Therefore, the sectional area of the yoke 22 can be sufficiently ensured while maintaining the compactness of the core 2, and excellent inductance characteristics can be obtained.

That is, in the present embodiment, as shown in fig. 12, the core 2 can be formed by effectively using dead spaces (dead spaces) 5 (portions surrounded by broken lines) on both the left and right sides of the core 2 when the coil 3 protrudes in the left-right direction from the core 2. This can achieve both miniaturization of the core 2 and improvement of the inductance value.

In the yoke 22 having a substantially hexagonal shape, magnetic flux hardly passes through the vicinity of the corner portion having a trapezoidal outer shape near the diameter of the center leg 21A. Therefore, even if the yoke 22 is rectangular, the "outer shape is near the corners of the trapezoid", and the influence on the inductance value is small. Therefore, in the present embodiment, even if the yoke 22 is formed in a substantially hexagonal shape to reduce the cross-sectional area, there is no fear of a decrease in inductance. As a result, the yoke 22 can be reduced to reduce the weight, and excellent inductance characteristics can be ensured.

(fourth embodiment)

A reactor 1 according to a fourth embodiment will be described with reference to fig. 13 to 20. Fig. 13 is a perspective view showing the entire configuration of the reactor 1 of the fourth embodiment, and fig. 14 is an exploded perspective view showing the entire configuration of the reactor 1 of the fourth embodiment. As shown in fig. 13 and 14, the core 2 of the fourth embodiment is also the same as the third embodiment in that the leg portion 21 is a block-shaped core including the MC core made of the composite magnetic material and the second member 22b as the ferrite core in the yoke portion 25.

The yoke 25 of the fourth embodiment is disposed at both ends of the leg 21, as in the yoke 22, but has a characteristic cross-sectional shape. In the third embodiment, the yoke 22 having a substantially hexagonal shape is used, but in the yoke 25 of the fourth embodiment, the substantially hexagonal shape is elongated in the vertical direction and has a shape in which straight portions are cut off.

Before explaining the shape of the yoke 25, the leg 21 will be explained. As shown in fig. 14, the center leg 21A includes a columnar member having a circular cross section, as in the third embodiment. In the outer leg 21B, an end surface (upper surface side in fig. 14) facing the middle leg 21A is a curved surface recessed downward in the drawing, and an opposite surface (lower surface side in fig. 14) is a flat surface. When the reactor 1 is placed horizontally, the flat surface side of the outer leg 21B serves as a mounting surface of the reactor 1.

As shown in fig. 15, in the fourth embodiment, similarly to the third embodiment, when the coil 3 is mounted on the core 2, an opening 29 (shown by a broken line) for exposing the coil 3 from the core 2 is formed in the reactor 1. In the fourth embodiment, the aperture ratio of the opening 29 is also set to 67%.

Next, the shape of the yoke 25 will be described in detail with reference to fig. 16 to 20. As shown in fig. 16, the yoke portion 25 has a shape in which the corner on the side of the center leg 21A (the upper side in fig. 16) is cut into a substantially triangular shape. In the yoke portion 25, when the width dimension of the yoke portion 25 is 46.0mm and the height dimension is 41.7mm, the area of a triangle (a portion surrounded by a broken line) surrounded by a × B is cut off with the width dimension a being 10mm and the height dimension B being 30 mm. The ratio of the width dimension a to the width dimension of the yoke portion 25 is 10/46-21.7%, and the ratio of the height dimension B to the height dimension of the yoke portion 25 is 30/41.7-71.9%.

As shown in fig. 17, yoke portion 25 has an extension portion 25a extending outward from the outer diameter of middle leg 21A. When the radius of the outer diameter of the center leg 21A is set to 28mm, the length of the extended portion 25a extends outward in the range of 3mm to 5 mm. The ratio of the length of the extension portion 25a to the radius of the outer diameter of the center leg 21A is in the range from 3/28 × 100 to 5/28 × 100 to 17.6%.

Further, as shown in fig. 18, in the yoke portion 25, the corner portion on the outer leg 21B side is formed in an R shape. The R-shaped portion of the yoke portion 25 at the corner on the outer leg 21B side includes a chamfered portion 25B. In the chamfered portion 25b, R is 7(mm) or less. The chamfered portion 25b is provided by chamfering ferrite constituting the second member 22 b. The bottom surface (lower surface in the figure) of the yoke 25 conforms to the shape of the outer leg 21B. Therefore, the corner of the outer leg 21B is also formed into an R-shape according to the R-shape of the chamfered portion 25B of the yoke portion 25 (see fig. 14 and 15).

As shown in fig. 19 and 20, the yoke 25 also has an R-shaped corner portion at a portion facing the end face of the coil 3. The R-shaped portion of the yoke portion 25 at the corner of the portion facing the end face of the coil 3 includes a chamfered portion 25 c. In the chamfered portion 25c, R is 6(mm) or less. The chamfered portion 25c is also provided by chamfering the ferrite constituting the second member 22b, similarly to the chamfered portion 25 b.

(action and Effect)

In the fourth embodiment, as in the third embodiment, the opening ratio of the opening 29 of the core 2 is set to 67%, and thus when the coil 3 is attached to the core 2, the area of the coil 3 exposed from the core 2 increases. Therefore, the heat of the coil 3 is hard to gather inside the core 2, and the heat is easily dissipated into the air. Therefore, the reactor 1 can exert excellent heat dissipation performance. In addition to these actions and effects, the fourth embodiment also has actions and effects derived from the shape of the yoke 25.

(1) In the yoke portion 25, when the corner portion on the side of the leg 21A is removed, the applicant has tried to study the inductance reduction rate of the reactor by setting the width a and the height B to the same value. First, the inductance reduction rate (%) was examined by changing the width a and the height B to 5mm and then to 10mm to 17mm in units of 1mm (see table 2).

[ Table 2]

As a result, the inductance reduction (%) became 1% at 5mm, 11mm and 12mm, and increased to 2% or more after 13 mm. On the other hand, the inductance value was 0% at 10mm, and was not decreased. When the reduction amount of the width dimension a is increased, the sectional area of the middle leg 21A must be reduced by a reduction amount smaller than the height dimension B. Therefore, the height dimension B with a relatively large reduction in size is reduced.

Therefore, the applicant fixed the width dimension a to 10mm having no influence on the inductance, changed only the height dimension B, and studied the inductance reduction rate. The results are shown in Table 3. As is clear from table 3, even if the height dimension B is reduced to 30mm, the inductance reduction rate is still 1%, and the influence on the inductance characteristic is small. When the height dimension of the yoke portion 25 is 41.7mm, it is considered difficult to secure the width dimension of the outer leg 21B if the height dimension B is 30mm or more.

[ Table 3]

As described above, in the reactor 1 according to the fourth embodiment, the inductance reduction ratio can be reduced by cutting the width dimension a by 10mm and the height dimension B by 30mm out of the substantially triangular dimensions cut out in the yoke portion 25. This can suppress the influence on the inductance characteristic. In addition, by removing a part of the yoke portion 25, the volume of the core 2 can be reduced, and the weight of the reactor 1 can be reduced.

(2) In the fourth embodiment, the yoke portion 25 is provided with the extension portion 25a extending from the outer diameter of the center leg 21A with respect to the outer diameter of the core 2, but the variation of the inductance reduction rate when the length of the extension portion 25a is changed is as follows (see table 4). That is, when the radius of the outer diameter of the core 2 is 28mm and the length of the extension portion 25a is 1mm, 2mm, and 2.5mm, the inductance reduction rates are 11%, 8%, and 4%, respectively.

[ Table 4]

When the length of the extension portion 25a is set to 3mm, 3.5mm, 4mm, 5mm, the inductance reduction rate is 1%, 2%, 1%, respectively. That is, when the length of the extension portion 25a is 3mm to 5mm, the inductance reduction rate can be suppressed to 2% or less. Therefore, in the fourth embodiment, even if the yoke portion 25 is cut, the influence on the inductance characteristic can be suppressed by providing the extension portion 25 a.

(3) In the fourth embodiment, not only the corner portion of the yoke portion 25 on the outer leg 21B side but also the corner portion on the outer leg 21B side is cut off, thereby forming the chamfered portion 25B having an R-shape. When the yoke 25 is reduced in the corner portion on the outer leg 21B side, the outer leg 21B itself must be reduced correspondingly, and therefore, the influence on the inductance value is increased. However, in the fourth embodiment, the reduction rate of inductance can be suppressed by defining R of the chamfered portion 25b to be 7mm or less.

[ Table 5]

The change in the inductance reduction rate when R of the chamfered portion 25b is changed is shown in table 5. That is, when R of the chamfered portion 25b is 2mm, 4mm, 6mm, 7mm, the inductance reduction rate is 2.9%, 2.5%, 1.9%, respectively. On the other hand, when R exceeds 7mm and becomes 8mm or 10mm, the inductance reduction rate becomes 3.4%, and when R becomes 15mm, the inductance reduction rate becomes 3.8%.

If the inductance reduction rate is within 3%, the inductance characteristic can be sufficiently satisfied. Therefore, in the fourth embodiment, the reduction rate of inductance can be suppressed to within 3% by setting R of the corner portion on the outer leg 21B side of the yoke portion 25 to 7mm or less. Thus, in the fourth embodiment, weight reduction is achieved by reduction of the core 2 while maintaining good inductance characteristics.

(4) Further, in the yoke portion 25 of the fourth embodiment, a chamfered portion 25c having an R shape is provided at a corner portion of a portion facing an end face of the coil 3. Therefore, the coil 3 is exposed from the core 2, and thus the aperture ratio of the opening 29 can be secured. The inductance reduction rate varied depending on the size of R of the chamfered portion 25c of the yoke portion 25, as shown in table 6 below.

[ Table 6]

When R of the chamfered portion 25c is 6mm, the inductance reduction rate is 1.3% which is the lowest, and when R is 1mm, 2mm, 3mm, 4mm, or 5mm, the inductance reduction rates are 1.7%, 2.1%, 1.7%, and 2.1%, respectively. On the other hand, when R is 7mm, the inductance reduction rate is 3.5%, and when R is 10mm, the inductance reduction rate is 5.0%.

As described above, since the inductance characteristic can be sufficiently satisfied when the inductance reduction rate is a change in inductance value within 3%, in the fourth embodiment, the reduction rate of inductance can be suppressed within 3% by setting R of the chamfered portion 25c to 6mm or less, and the maintenance of the inductance characteristic and the reduction of the core 2 can be achieved at the same time.

(fifth embodiment)

A reactor 1 according to a fifth embodiment will be described with reference to fig. 21 and 22. Fig. 21 is a perspective view showing the entire configuration of the reactor 1 of the fifth embodiment, and fig. 22 is an exploded perspective view showing the entire configuration of the reactor 1 of the fifth embodiment. As shown in fig. 21 and 22, in the core 2 of the fifth embodiment, as in the third embodiment, the leg portion 21 is also an MC core including a composite magnetic material, and is a block-shaped core including the second member 22b which is a ferrite core in the yoke portion 27 a.

As shown in fig. 22, the fifth embodiment includes an X-shaped core 2, and the core 2 is configured to have a cylindrical center leg 21A as a center, and four outer legs 21C surrounding the center leg 21A. The four outer legs 21C are all of the same shape and are arranged with a uniform interval kept. In the X-shaped core 2, since the magnetic flux is concentrated and flows through the yoke portion 27a connecting the center leg 21A and the four outer legs 21C, the magnetic flux is less likely to flow through the reduced portion, and the reduction does not largely affect the characteristics. That is, the core 2 cuts a portion through which magnetic flux hardly flows, and as a result, the core becomes X-shaped.

In the outer leg 21C, the surface facing the middle leg 21A is a concave curved surface, and the other surfaces are flat surfaces perpendicular to each other. When the reactor 1 is placed horizontally, the flat surface side of the outer leg 21C serves as a mounting surface of the reactor 1. However, fig. 21 shows a case where the reactor 1 is placed vertically, and in this case, the end surface of the yoke portion 27a facing outward serves as a mounting surface for the reactor 1.

The yokes 27a of the fifth embodiment are arranged at both ends of the leg 21, similarly to the

yokes

22 and 25, but the yokes 27a include X-shaped core members. In the X-shaped yoke 27a, the intersecting side portions are formed so as to be orthogonal to each other. Further, outer legs 21C are disposed at the distal end portions of the side portions of the X-shaped yoke portion 27 a. Therefore, the front end of each side portion of the yoke portion 27a is formed at a right angle to the flat surface of the outer leg 21C.

As shown in fig. 21, when the coil 3 is mounted on the core 2, the reactor 1 is formed with an opening 26 for exposing the coil 3 from the core 2. The opening 26 is disposed between the four outer legs 21C. That is, the opening 26 is provided in four places, and the total of the four places of the opening ratio is 67%. The opening 26 is formed to have a right-angled corner portion near the center of the coil 3 when viewed from above in fig. 21, and to extend in a fan shape from the corner portion.

(action and Effect)

(1) In the fifth embodiment, the X-shaped core 2 can increase the aperture ratio. In the fifth embodiment, heat dissipation is improved by providing the openings 26 to be 67%. For example, as example 2 to which the fifth embodiment is applied, a core 2 was produced from a leg portion 21 of an MC core (Fe — Si alloy) and a yoke portion 27a of ferrite (Mn — Zn system), and heat of the coil 3 of example 2 was measured. The current 27A was applied as the conduction condition, the frequency was 20kHz, and the cooling condition was natural cooling (see table 7).

[ Table 7]

As a result, the temperature of the coil 3 was 57.8 ℃, which was 1.1 ℃ lower than the temperature of the coil of example 1 to which the third embodiment was applied. This is considered to be because, in the fifth embodiment, the opening 26 is provided in four parts, and heat dissipation can be uniformly performed over the entire circumference of the coil 3. According to the fifth embodiment as described above, a higher heat radiation effect can be obtained.

(2) In the fifth embodiment, since the flat surface of the outer leg 21C is a right angle, the reactor 11 is highly stable when placed horizontally.

(modification 3)

Modification 3 of core 2 of the fifth embodiment has the following configuration. For example, in the X-shaped yoke 27b shown in fig. 23 and 24, the tip of the intersecting side portion is pointed. Therefore, in the opening 26 shown in fig. 21, a right-angled corner is formed near the center of the coil 3, and in the opening 28 shown in fig. 23 and 24, an acute-angled corner is formed near the center of the coil 3.

In the X-shaped yoke 27c shown in fig. 25 and 26, a circular portion having a shape corresponding to the center leg 21A is provided in the center portion, and side portions are provided so as to extend in four directions from the circular portion. As shown in fig. 26, the front end of each side portion of the yoke portion 27c has a substantially trapezoidal shape. Therefore, the cross section of each of the four outer legs 21D conforming to the outer shape of the yoke portion 27c has a substantially hexagonal shape. In contrast to the opening 28 shown in fig. 23 and 24, which forms an acute corner near the center of the coil 3, the opening 30 shown in fig. 25 and 26 forms an obtuse corner near the center of the coil 3.

In modification 3 of the fifth embodiment as described above, the desired aperture ratio can be obtained by changing the corner portions of the

openings

28 and 30 in the vicinity of the center of the coil 3. Therefore, excellent heat dissipation can be obtained while ensuring inductance characteristics according to the needs of the user.

[ example 3]

Examples of the present invention are explained with reference to table 8. In example 3, three samples of the cores of example 3 and comparative example 4 were prepared under the same conditions, and the shear strength of each sample was measured. The samples of example 3 and comparative example 4 were prepared as follows. Example 3 differs from comparative example 4 in that in example 3, a powder magnetic core and an MC core containing a composite magnetic material are joined by a resin of the composite magnetic material, and in comparative example 4, a molded body of the MC core is prepared and the powder magnetic core and the MC core are joined by an adhesive. In addition, the three samples of example 3 were the same, and the three samples of comparative example 4 were the same.

(method of preparing sample of example 3)

In the method of preparing the sample of example 3, first, a frame filled with a composite magnetic material was disposed on a molded powder magnetic core (NPS series, POCO). Next, the frame is filled with a clay-like composite magnetic material. The composite magnetic material is obtained by adding 4 wt% of epoxy resin to Fe-6.5% of Si as magnetic powder. The filled composite magnetic material was pressed at 400N toward the powder magnetic core. Thereafter, the resin was cured by heating at 150 ℃ for 8 hours in the air, and bonded to the powder magnetic core. In this manner, in the sample of example 3, the dust core and the MC core are bonded by the resin of the composite magnetic material.

(method of preparing sample of comparative example 4)

In the method of manufacturing the sample of comparative example 4, first, a compact of the powder magnetic core and the MC core was prepared. The compact of the powder magnetic core was the same as in example 3. The MC core molded body is produced as follows. The magnetic powder, the kind of resin, and the amount of resin added of the composite magnetic material were the same as those of example 3. First, a predetermined container was filled with a clay-like composite magnetic material, and the resin was cured by heating at 150 ℃ for 8 hours in the air to obtain a molded body of MC core. Then, the dust core and the MC core are joined by an adhesive. For the adhesive, an epoxy resin was used, heated at 120 ℃ for 1 hour, and cured.

The shear strength of the samples of example 3 and comparative example 4 was measured at 5mm/min using the following apparatus as the measurement condition. The measurement results are shown in table 8.

Company name: japanese measurement System (stock)

Device name: MAX-20

[ Table 8]

As shown in table 8, the results showed that the shear strength was higher in all of samples 1 to 3 of example 3 than in sample 3 of comparative example 4, which had the highest shear strength. In samples 1 to 3 of comparative example 4, cohesive failure of the adhesive occurred. Namely, the joint portion between the leg portion and the yoke portion is cut. On the other hand, in samples 1 to 3 of example 3, base material breakage occurred in the powder magnetic core of the yoke portion 22. That is, the yoke 22 and the leg 21 are not cut at the joint.

This is presumably because, when the adhesive is used for bonding as in comparative example 4, a gap is formed at the bonding portion, and therefore, the adhesive is broken by aggregation starting from this gap. On the other hand, in example 3, the bonding was performed without using an adhesive, and the bonding was performed by the resin of the composite magnetic material constituting the MC core, and thus the bonding was performed without a gap. That is, the dust core and the MC core are bonded more tightly than bonding with an adhesive. Therefore, in example 3, the joining was performed without a gap, so that the strength of the joined portion was improved, and the base material of the powder magnetic core was broken without being cut from the joined portion.

In this manner, in example 3, the leg portions 21 and the yoke portion 22 are joined by the resin of the MC core, and thus the leg portions 21 and the yoke portion 22 can be firmly joined without generating a gap. Therefore, the leakage magnetic flux generated by the gap can be suppressed.

(example 4)

Example 4 of the present invention is described with reference to table 9, table 10 and fig. 27. In example 4, the reactors of example 4, comparative example 5, and comparative example 6 were produced, and the loss and the inductance value (L value) were measured. In the reactors of example 4, comparative example 5, and comparative example 6, the sectional area of the core, the number of windings of the coil, the size of the reactor, and the like are the same, only the material of the core and the joining method are different.

In the core 2 of example 4, an MC core (magnetic permeability μ 30) was used for the leg portion 21, a powder magnetic core (magnetic permeability μ 147) was used for the yoke portion 22, and the leg portion 21 and the yoke portion 22 were bonded by the resin of the MC core. In comparative example 5, a dust core (magnetic permeability μ 60) was used for the leg portion, a dust core (magnetic permeability μ 147) was used for the yoke portion, and the leg portion and the yoke portion were bonded by an adhesive. In comparative example 6, an MC core (magnetic permeability μ 30) was used for the leg portion, an MC core (magnetic permeability μ 30) was used for the yoke portion, and the leg portion and the yoke portion were joined by an adhesive. In comparative examples 5 and 6, which were bonded with an adhesive, there were gaps in which the adhesive film thickness was 50 μm at four locations.

The results of the loss and inductance values of the reactors of example 4, comparative example 5, and comparative example 6 are shown in tables 9 and 10, and fig. 27.

[ Table 9]

[ Table 10]

As shown in table 9, the iron loss and the copper loss, which are losses, of example 4 were also values that did not change much compared to the values of comparative examples 5 and 6. That is, example 4 has the same low loss characteristics as comparative examples 5 and 6. As shown in table 10 and fig. 27, the inductance values of example 4 were not much changed from those of comparative examples 5 and 6. In particular, the inductance values of 30A to 40A were almost the same as those of comparative examples 5 and 6 in example 4, and the reactor of example 4 was shown to have good dc superimposition characteristics.

As described in the above examples 3 and 4, the leg portions 21 and the yoke portion 22 can be joined together without a gap by joining the leg portions 21 and the yoke portion 22 with the resin composite magnetic material as in the present invention, and therefore generation of leakage magnetic flux can be suppressed. In addition, even if the leg portion 21 and the yoke portion 22 are joined by the resin of the composite magnetic material as in the present invention, the loss characteristic and the dc bias characteristic are maintained at good values. That is, the present invention can suppress the generation of leakage magnetic flux while maintaining good loss characteristics and dc superimposition characteristics.

(example 5)

Example 5 is described with reference to table 11, fig. 28, and fig. 29. In the present embodiment, the inductance value (L value) and the ac loss were measured by changing the thickness L1 of the first member 22a of the yoke 22 while setting the entire thickness L2 of the yoke 22 at 14.0 mm. In this embodiment, the same composite magnetic material (magnetic permeability μ 30) as that of the leg portion 21 is used for the first member 22a, and a powder magnetic core (magnetic permeability μ 147) of Fe — Si — Al is used for the second member 22 b. The measurement results are shown in table 11, fig. 28, and fig. 29.

[ Table 11]

As shown in table 11 and fig. 28, it is understood that the ac loss decreases as the thickness L1 of the first member 22a increases. This is because the larger the thickness L1 of the first member 22a, the further the distance between the coil 3 and the joint between the first member 22a and the second member 22b becomes, and therefore the influence of the leakage magnetic flux on the coil can be reduced, and the ac loss can be reduced.

On the other hand, referring to table 11 and fig. 29, the thicker the thickness of the first member 22a, the lower the initial inductance value. When the inductance value at a low current value decreases, the ripple of the current during the low current operation increases. Therefore, if the ratio exceeds 0.5, the iron loss of the reactor may increase or the rotating operation may become unstable. When the ratio of the thickness L1 of the first member 22a to the entire thickness L2 of the yoke 22 is set to 0.5 or less, the ac loss can be reduced while maintaining the initial inductance value.

(other embodiments)

In the present specification, the embodiments of the present invention have been described, but the embodiments are presented as examples and are not intended to limit the scope of the invention. The above-described embodiments may be implemented in various other ways, and various omissions, substitutions, and changes may be made without departing from the scope of the invention. The embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalent scope thereof.

The magnetic powder of the composite magnetic material may include two or more kinds of magnetic powder having different average particle diameters. In this case, the magnetic powder includes a first magnetic powder and a second magnetic powder having an average particle diameter smaller than that of the first magnetic powder, and the weight ratio thereof is preferably set to the first magnetic powder: second magnetic powder 80: 20-60: 40. by setting the above range, the density and the magnetic permeability can be improved, and the iron loss can be reduced.

The average particle diameter of the first magnetic powder is preferably 100 to 200 μm, and the average particle diameter of the second magnetic powder is preferably 3 to 10 μm. This is because the second magnetic powder having a small average particle diameter enters the gap between the first magnetic powders, and the density and permeability can be improved and the iron loss can be reduced.

The first magnetic powder and the second magnetic powder are preferably spherical. The circularity of the first magnetic powder is preferably 0.90 or more, and the circularity of the second magnetic powder is preferably 0.90 or more. This is because the gap between the first magnetic powder is reduced, and more second magnetic powder easily enters the gap, thereby improving the density and the magnetic permeability.

The first magnetic powder and the second magnetic powder may be the same or different in kind. Three or more kinds may be used in different cases. When the magnetic powder is constituted by three or more kinds of powder, the average particle diameters of the respective kinds may be different from each other.

Among the resins, SiO can be used₂、Al₂O₃、Fe₂O₃、BN、AlN、ZnO、TiO₂And the like as the viscosity adjusting material. The average particle diameter of the viscosity adjusting material is preferably equal to or less than the average particle diameter of the second magnetic powder, and is preferably equal to or less than 1/3 of the average particle diameter of the second magnetic powder. This is because, if the average particle diameter of the viscosity adjusting material is large, the magnetic powder cannot be held without a gap, and the density of the obtained core is reduced. In addition, Al may be added to the resin₂O₃High thermal conductivity materials such as BN and AlN.

The proportion of the apparent density of the core to the true density of the magnetic powder is preferably more than 76.47%, more preferably 77.5% or more. If the ratio exceeds 76.47%, the magnetic permeability can be improved. Conversely, when the ratio is 76.47% or less, the magnetic permeability becomes low due to low density.

In the first embodiment, the MC core is used for the leg portion 21 and the powder magnetic core is used for the yoke portion 22, but the MC core is not limited thereto, and may be used for both the leg portion 21 and the yoke portion 22. In this case, first, the MC core of either the leg portion 21 or the yoke portion 22 is made into a cured molded body. Then, the molded body may be joined by another resin of the clay-like composite magnetic material serving as the MC core.

In the present embodiment, as shown in fig. 2, the yoke portion 22 is joined to the end surface of the leg portion 21 perpendicular to the winding axis direction of the coil 3, but the present invention is not limited to this, and various forms can be applied as long as the core 2 can be joined by the resin of the composite magnetic material. For example, the two leg portions 21 formed in a block shape may be arranged so that the longitudinal directions thereof are parallel to each other, and a pair of yoke portions 22 made of a composite magnetic material may be provided between the leg portions 21. Specifically, the leg portions 21 may have portions where the coil 3 is not wound at both ends, the yoke portion 22 may be provided between the leg portions 21 where the coil 3 is not wound, and the leg portions 21 and the yoke portion 22 may be joined by a resin composite magnetic material.

For example, the aperture ratio of the opening for exposing the coil 3 from the core 2 can be appropriately selected as long as it exceeds 60%. The upper limit of the aperture ratio may be determined by the sectional area of the outer leg that satisfies the required inductance characteristic. Further, in the yoke portion 22 having a substantially hexagonal shape in the third embodiment, the corner portion is linear, but a protruding portion protruding outward from the outer diameter of the middle leg 21A may be provided similarly to the yoke portion 25 in the fourth embodiment, and the corner portion on the outer leg 21B side may be R-shaped. Further, in the yoke portion 22 having a substantially hexagonal shape, the corner of the portion facing the end face of the coil 3 may be formed in an R shape. In the fifth embodiment, four outer legs are provided, but the number of outer legs can be changed as appropriate.

Claims

1. A reactor, characterized by comprising:

a core having a plurality of legs and a pair of yokes arranged at both ends of the plurality of legs; and

a coil wound around the leg portion,

at least either the leg portion or the yoke portion includes a composite magnetic material containing a magnetic powder and a resin,

the leg portion and the yoke portion are joined by a resin of the composite magnetic material.

2. The reactor according to claim 1,

the foot portion seamlessly and continuously engages with the yoke portion.

3. The reactor according to claim 1 or 2,

the leg portion or the yoke portion not including the composite magnetic material has an unevenness on an end surface where the leg portion and the yoke portion are joined,

the composite magnetic material enters the concave portion of the concave-convex.

4. The reactor according to any one of claims 1 to 3,

further comprising a resin member covering the periphery of the core,

the leg portion or the yoke portion including the composite magnetic material is integrally molded with the resin member without a gap by the resin of the composite magnetic material.

5. The reactor according to any one of claims 1 to 4,

the entire outer peripheral surface of the leg portion or the yoke portion including the composite magnetic material is a non-sliding surface.

6. The reactor according to any one of claims 1 to 5,

the foot portion includes the composite magnetic material.

7. The reactor according to any one of claims 1 to 6,

the yoke portion has a magnetic permeability greater than that of the leg portion.

8. A method for manufacturing a reactor including a core including a plurality of legs and yoke portions arranged at both ends of the legs, at least either one of the legs or the yoke portions including a composite magnetic material containing magnetic powder and resin, the method comprising:

a mounting step of mounting the coil on the resin member;

a filling step of filling the resin member with the clay-like composite magnetic material;

a pressurizing step of pressurizing the composite magnetic material injected into the resin member; and

and a curing step of curing the resin.

9. The method of manufacturing a reactor according to claim 8, being a method of manufacturing a reactor including the leg portion including the composite magnetic material, characterized in that,

in the filling step, a resin member covering the leg portion is filled with a clay-like composite magnetic material,

in the pressing step, the composite magnetic material is pressed by a core constituting the yoke.

10. The method of manufacturing a reactor according to claim 8, being a method of manufacturing a reactor including the yoke portion including the composite magnetic material, characterized in that,

in the mounting step, the leg portion formed in advance into a molded body is inserted into the resin member,

in the filling step, the resin member covering the yoke is filled with the clay-like composite magnetic material,

in the pressing step, the composite magnetic material is pressed by a pressing member.

11. The reactor manufacturing method according to any one of claims 8 to 10, characterized in that,

12. The reactor manufacturing method according to any one of claims 8 to 11, characterized in that,

the leg portion or the yoke portion, which is not molded from the clay-like composite magnetic material, has an irregularity on an end surface where the leg portion and the yoke portion are joined.

13. A reactor, characterized by comprising:

a coil wound around the leg portion,

the leg portion includes a composite magnetic material containing magnetic powder and resin,

the yoke portion has:

a first member comprising the composite magnetic material; and

a second member comprising a material different from the composite magnetic material,

the first member is disposed on a side where the leg portion is disposed, and is integrally formed with the leg portion,

the first member is engaged with the second member,

the magnetic permeability of the second member is greater than the magnetic permeability of the leg portion and the first member.

14. The reactor according to claim 13,

the ratio of the thickness of the coil of the first member in the reel direction to the thickness of the yoke as a whole in the reel direction is 0.5 or less.

15. The reactor according to claim 13 or 14,

the outer peripheral surfaces of the leg portion and the first member including the composite magnetic material are all non-sliding surfaces.

16. The reactor according to any one of claims 13 to 15,

in the yoke portion, the first member and the second member are joined by the resin of the composite magnetic material of the first member.

17. The reactor according to any one of claims 13 to 16,

in the yoke, the first member and the second member are seamlessly and continuously joined.

18. A reactor, characterized by comprising:

a core having a center leg around which a coil is wound, outer legs disposed outside the center leg, and yoke portions disposed at both ends of the center leg and both ends of the outer legs,

the middle leg and the outer leg include a composite resin material containing magnetic powder and resin, and

an opening portion for exposing the coil from the core is formed, and the opening ratio of the opening portion is set to be more than 60% when the opening ratio is 0% when the entire circumference of the coil is housed in the core and 100% when the entire circumference of the coil is exposed from the core.

19. The reactor according to claim 18,

the aperture ratio of the opening is 67% or more.

20. The reactor according to claim 18 or 19,

the yoke includes a first member including the composite magnetic material and a second member including a material having a magnetic permeability greater than that of the composite magnetic material.

21. The reactor according to claim 20,

the yoke portion and the middle leg and the yoke portion and the outer leg are joined by a composite resin material of the first member.

22. The reactor according to claim 20 or 21,

the magnetic permeability of the second member is greater than the magnetic permeability of the first member.

23. The reactor according to claim 22,

the second member includes at least a powder magnetic core, a ferrite, and a laminated steel plate.

24. The reactor according to any one of claims 18 to 23,

the middle foot and the outer foot are respectively one,

the cross-sectional shape of the midfoot is circular or elliptical,

the outer leg is larger than the middle leg in diameter and has a width dimension equal to or smaller than the diameter of the outer peripheral portion of the coil.

25. The reactor according to claim 24,

the yoke is substantially hexagonal in shape combining: a semi-circular portion connected to a diameter portion of the middle leg; a trapezoidal portion having a short side defined by a diameter portion of the middle leg; and a rectangular portion connected to the trapezoidal portion with a long side opposite to the short side.

26. The reactor according to claim 24 or 25, characterized in that,

the yoke has a substantially triangular shape formed by cutting the corner of the leg.

27. The reactor according to any one of claims 24 to 26,

the yoke has a protruding portion protruding outward from an outer diameter of the center leg.

28. The reactor according to any one of claims 24 to 27,

in the yoke, a corner portion on the outer leg side is formed in an R shape.

29. The reactor according to any one of claims 24 to 28,

in the yoke, a corner of a portion facing an end face of the coil is formed in an R shape.

30. The reactor according to any one of claims 18 to 29,

the outer leg has a chamfered portion.

31. The reactor according to any one of claims 18 to 23,

the core is configured such that the plurality of outer legs surrounds the center leg.

32. The reactor according to claim 31,

the yoke portions disposed at both end portions of the plurality of outer legs are configured to be equally radially expanded.