CN110062948B

CN110062948B - Method for manufacturing reactor

Info

Publication number: CN110062948B
Application number: CN201780075640.0A
Authority: CN
Inventors: 大岛泰雄; 髙桥渡
Original assignee: Tamura Corp
Current assignee: Tamura Corp
Priority date: 2016-12-08
Filing date: 2017-12-07
Publication date: 2021-11-09
Anticipated expiration: 2037-12-07
Also published as: CN110062948A; CN112992453A; WO2018105697A1

Abstract

Provided are a method for manufacturing a reactor, a method for manufacturing a core, a reactor, a soft magnetic composite material, and a magnetic core, which have the advantage of moldability and can improve productivity and density. The method for manufacturing a reactor includes a core including magnetic powder and resin, and a coil mounted on the core, and includes: a mixing step of mixing 3 to 5 wt% of a resin with respect to the magnetic powder; a molding step of molding the mixture obtained in the mixing step and the coil in a predetermined container; a pressing step of pressing the mixture in the molding step; and a curing step of curing the molded body obtained in the molding step.

Description

Method for manufacturing reactor

Technical Field

The present invention relates to a method for manufacturing a reactor (reactor) including a metal composite core containing magnetic powder and resin, a method for manufacturing a core, a reactor, a soft magnetic composite material suitable for a reactor called a metal composite type, a magnetic core using the soft magnetic composite material, and a reactor using the soft magnetic composite material.

Background

Reactors are used in various applications such as Office Automation (OA) equipment, Solar Power systems (Solar Power systems), automobiles, uninterruptible Power supplies (uninterruptible Power supplies), and the like. The reactor is used in, for example, a filter (filter) for preventing harmonic current from flowing into a power output system, a converter (converter) for voltage increase and decrease for increasing and decreasing voltage, and the like.

Magnetic characteristics such as magnetic permeability (magnetic permeability), inductance value (inductance value), and iron loss (iron loss) are required for a reactor according to the application. For example, since a reactor used in a converter for voltage increase and decrease is required to improve energy conversion efficiency, iron loss, which is an energy loss, is required to be small.

In order to meet various applications, it is also strongly required to mold the core used in the reactor into an arbitrary shape. A reactor that copes with such an urgent demand is a reactor including a core of a type called a metal composite core.

The metal composite core (hereinafter also referred to as MC core) is a core obtained by molding a material in which metal magnetic powder and resin are mixed into a predetermined shape and curing the molded material. The conventional MC core has a slurry-like material, and is advantageous in that the material can easily flow into a container and can be formed into a predetermined shape.

A reactor referred to as a metal composite type is a reactor manufactured by integrally molding a magnetic core and a coil (coil) using a material in which soft magnetic powder and resin are mixed. Among them, magnetic saturation is difficult in a high temperature region, and the like, as compared with a lamination type reactor using ferrite (ferrite) in a magnetic core.

A magnetic core used in a metal composite type reactor is referred to as a metal composite core. The soft magnetic composite material is produced by mixing soft magnetic powder with a resin to produce a soft magnetic composite material, and curing the soft magnetic composite material. Patent document 2 discloses the following method: by using soft magnetic powder having a predetermined density ratio, a soft magnetic composite material having a low relative permeability and a high saturation magnetic flux density to some extent can be obtained.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2012-33727

Patent document 2: japanese patent laid-open No. 2014-160828

Disclosure of Invention

Problems to be solved by the invention

As described above, since the material obtained by mixing the magnetic powder and the resin is in the form of slurry, the conventional MC core has an advantage of good moldability. However, when a worker flows the material into the container, the material is easily spilled, which makes handling difficult and causes a problem in productivity.

Further, since the conventional MC core material contains a large amount of resin, the proportion of the magnetic powder in the material decreases, which leads to a decrease in the core density and, as a result, a decrease in the magnetic properties.

Therefore, it is considered to increase the density of the magnetic powder contained in the material by reducing the amount of the resin. However, if the amount of resin is reduced, the material is less likely to flow into the corners of the container, and the MC core is less advantageous in terms of moldability. As described above, it is difficult to establish all of moldability, productivity, and high density in the conventional MC core.

In addition, the MC core has gentle magnetic characteristics. That is, the MC core is less likely to be magnetically saturated than the ferrite core, and has a characteristic that the magnetic permeability is less likely to decrease even if the current flowing through the coil is increased. In other words, the MC core has a characteristic that the initial permeability, that is, the permeability when no current flows through the coil tends to be low.

However, as a technique for improving the magnetic permeability, a technique is known in which a magnetic field is applied from the outside to align the orientation of magnetic powder in the MC core in the process of manufacturing the MC core (patent document 1).

In the conventional technique described above, a conductive member for forming a current path is separately provided, and a magnetic field is generated by applying a current to the conductive member, thereby applying a magnetic field to the material of the MC core from the outside. Such a conductive member is provided, for example, on the outer side of a container containing an MC core material, and the position of the conductive member must be moved to obtain a desired orientation.

However, due to the restrictions on the installation conditions of the conductive member, it is difficult to generate magnetic flux in a direction in which the conductive member is actually intended to be oriented. Therefore, the direction of the desired orientation and the direction of the magnetic flux generated by the conductive member do not match in practice, and the effect of improving the initial permeability may not be obtained.

In addition, in the MC core, the resin exists between the magnetic powders, preventing the magnetic powders from contacting each other. In other words, the resin ensures insulation between the magnetic powders. When such an MC core is used at a high temperature for a long time, the resin is decomposed, and the magnetic properties are degraded due to the contact between the magnetic powders.

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 method of manufacturing a reactor, a method of manufacturing a core, and a reactor, which can improve productivity and density while obtaining advantages in moldability.

A second object of the present invention is to provide a method of manufacturing a reactor capable of obtaining a reactor including a core having a high initial permeability.

A third object of the present invention is to solve the above-described problems of the prior art, and to provide a composite soft magnetic composite material, a metal composite core, and a method for producing a metal composite core, in which deterioration of magnetic properties during long-term use at high temperatures is suppressed.

Means for solving the problems

In order to achieve the first object, a method of manufacturing a reactor according to the present invention is a method of manufacturing a reactor including a core including magnetic powder and resin, and a coil mounted on the core, and includes the following configuration.

(1) A mixing step of mixing 3 to 5 wt% of a resin with respect to the magnetic powder.

(2) And a molding step of molding the mixture obtained in the mixing step and the coil by being put into a predetermined container.

(3) And a pressing step of pressing the mixture in the molding step.

(4) And a curing step of curing the resin in the molded body obtained in the molding step.

The method for producing a core of the present invention is a method for producing a core containing a magnetic powder and a resin,

includes the following structure.

(2) And a molding step of adding the mixture obtained in the mixing step to a predetermined container and molding the mixture.

(3) And a pressing step of pressing the mixture in the molding step.

The core of the present invention is a core containing magnetic powder and resin, and has the following structure.

(1) 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.

(2) The addition amount of the first magnetic powder in the magnetic powder is 60 wt% -80 wt%, and the addition amount of the second magnetic powder is 20 wt% -40 wt%.

(3) The first magnetic powder has an average particle diameter of 100 to 200 [ mu ] m, and the second magnetic powder has an average particle diameter of 3 to 10 [ mu ] m.

(4) The content of the resin is 3 to 5 wt% with respect to the magnetic powder.

(5) The proportion of the apparent density of the core relative to the true density of the magnetic powder is more than 76.47%.

The invention can also be understood as a reactor comprising said core.

In order to achieve the second object, a method of manufacturing a reactor according to the present invention is a method of manufacturing a reactor including a core including magnetic powder and resin, and a coil mounted on the core, and includes the following configuration.

(3) And a curing step of curing the resin in the molded body obtained in the molding step.

(4) And a magnetic field application step of applying a magnetic field to the molded body by energizing the coil of the molded body in the curing step.

Further, a method for manufacturing a reactor according to the present invention is a method for manufacturing a reactor including a core including magnetic powder and resin, and a coil mounted on the core, and includes the following configuration.

(3) And a winding step of winding a wire constituting the coil around the molded body obtained in the molding step.

(4) And a curing step of curing the resin in the molded body around which the lead wire is wound.

(5) And a magnetic field application step of applying a magnetic field to the molded body by applying current to the conductive wire in the curing step.

In order to achieve the third object, a soft magnetic composite material according to the present invention is a soft magnetic composite material obtained by mixing magnetic powder and a resin, wherein a reduction rate of the resin when exposed to an environment at 220 ℃ for 40 hours is 0.1% or less.

The reduction rate may be set to 0.08% or less.

The reduction rate may be a reduction rate of the weight of the resin.

The magnetic powder may include: the magnetic powder includes a first magnetic powder having a predetermined average particle diameter and a second magnetic powder having an average particle diameter smaller than that of the first magnetic powder.

The first magnetic powder may have an average particle diameter of 100 to 200 μm, and the second magnetic powder may have an average particle diameter of 5 to 10 μm.

The first magnetic powder may be added in an amount of 60 wt% to 80 wt%, and the second magnetic powder may be added in an amount of 20 wt% to 40 wt%.

The resin may be provided as a thermosetting resin.

The resin may be provided as an epoxy resin.

A magnetic core including the soft magnetic composite material described above is also an embodiment of the present invention. The magnetic core may have a rate of change in iron loss of 10% or less when exposed to an environment at 155 ℃ for 500 hours or more.

Further, a reactor including the magnetic core is also an embodiment of the present invention.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, it is possible to provide a method for manufacturing a reactor, a method for manufacturing a core, and a reactor, which can improve productivity and density while achieving the advantage of moldability.

According to the present invention, it is possible to provide a method of manufacturing a reactor that can obtain a reactor including a core having a high initial permeability.

According to the present invention, the reduction rate of the resin mixed in the magnetic powder in the soft magnetic composite material when exposed to 220 ℃ for 40 hours is 0.1% or less. As a result, even when the magnetic core and the reactor including the soft magnetic composite material are exposed to high temperatures for a long time, the disappearance of the resin existing between the magnetic powders can be suppressed, and as a result, the magnetic core and the reactor of the present invention can suppress the decline of the magnetic characteristics when used at high temperatures for a long time.

Drawings

Fig. 1 is a flowchart for explaining a method of manufacturing a reactor according to embodiment I.

Fig. 2 is a diagram for explaining the molding step and the pressing step.

Fig. 3 is a graph of theoretical densities with respect to surface pressure for examples 1 to 3 and comparative examples 1 and 2.

Fig. 4 is a Scanning Electron Microscope (SEM) photograph (100 x) of the core cross section of example 2.

FIG. 5 is an SEM photograph (magnification 100) of a core cross-section of comparative example 1.

Fig. 6 is a graph of magnetic permeability with respect to surface pressure for examples 1 to 3 and comparative examples 1 and 2.

Fig. 7 is a graph showing the iron loss with respect to the surface pressure in examples 1 to 3 and comparative examples 1 and 2.

Fig. 8 is a graph of magnetic permeability with respect to surface pressure for examples 4 to 6 and comparative example 3.

Fig. 9 is a graph of the iron loss with respect to the surface pressure in examples 4 to 6 and comparative example 3.

Fig. 10 is a graph of magnetic permeability against surface pressure for examples 9 to 11 and comparative example 6.

Fig. 11 is a graph showing the iron loss with respect to the surface pressure in examples 9 to 11 and comparative example 6.

Fig. 12 is a flowchart for explaining a method of manufacturing a reactor according to embodiment II.

Fig. 13 is a graph of initial permeability with respect to the amount of resin in the case where a magnetic field is applied and the case where no magnetic field is applied.

Fig. 14 is a graph of the rate of change in permeability with respect to the amount of resin.

Fig. 15 is a graph of the rate of change of the initial inductance value with respect to the magnetic field.

Fig. 16 is a graph showing the initial inductance values of the reactors fabricated in the respective applied magnetic fields in the curing step, assuming that the resin amount is 3 wt%.

Fig. 17 is a graph showing the change rate of the initial inductance value of the reactor fabricated in each applied magnetic field in the curing step assuming that the resin amount is 3 wt%.

Fig. 18 is a graph showing the initial inductance values of the reactors fabricated in the respective applied magnetic fields in the curing step, assuming that the resin amount is 4 wt%.

Fig. 19 is a graph showing the change rate of the initial inductance value of the reactor fabricated in each applied magnetic field in the curing step assuming that the resin amount is 4 wt%.

FIG. 20 is a graph showing the initial inductance values of the reactors prepared in the respective applied magnetic fields in the curing step, assuming that the resin amount is 5 wt%.

Fig. 21 is a graph showing the change rate of the initial inductance value of the reactor produced in each applied magnetic field in the curing step assuming that the resin amount is 5 wt%.

Fig. 22 is a flowchart for explaining a method of manufacturing the metal composite core according to embodiment III.

FIG. 23 is a graph showing the relationship between the leaving time and the iron loss Pcv in the high-temperature leaving test.

Description of the symbols

1: first magnetic powder

2: second magnetic powder

3: resin composition

4: voids

10: container with a lid

20: composite magnetic material

30. 32: extruded member

40: coil

Detailed Description

[1. embodiment I ]

[1-1. Structure ]

The reactor of the present embodiment includes a core and a coil. The core is a metal composite core including magnetic powder and resin. The core can be formed into a predetermined shape by filling a predetermined container with a clay-like mixture in which magnetic powder and resin are mixed and pressurizing the mixture. The shape of the core may be set, for example: various shapes such as a ring core, an I core, a U core, a theta core, an E core, an EER core, etc.

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), or 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 magnetic powder may contain 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 a smaller average particle diameter than the first magnetic powder, and the weight ratio thereof is preferably set to be: second magnetic powder 80: 20-60: 40. by setting the range, the density is increased, the magnetic permeability is also increased, 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 0.93 or more, and the circularity of the second magnetic powder is preferably 0.95 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. The number of the above-mentioned groups may be 3 or more in different cases. When the magnetic powder is constituted by 3 or more kinds of powder, the average particle diameters of the respective kinds may be different from each other.

The first magnetic powder is preferably a pulverized component. The second magnetic powder may be produced by a water atomization method, a gas atomization method, or a water/gas atomization method, and particularly preferably a powder formed by a water atomization method. The reason is that the water atomization method rapidly cools at the time of atomization, so that the powder is difficult to crystallize.

The resin mixes the magnetic powder and holds the magnetic powder. When the magnetic powder contains different kinds of powder having different average particle diameters, the respective powders are held in a uniformly mixed state. The resin may be a thermosetting resin, an ultraviolet-curable resin, or a thermoplastic resin. The thermosetting resin may be used: phenol resins, epoxy resins, unsaturated polyester resins, polyurethanes, diallyl phthalate resins, silicone resins, and the like. The ultraviolet curable resin may be used: acrylic urethane-based, acrylic epoxy-based, acrylic ester-based, and epoxy-based resins. The thermoplastic resin is preferably a resin having excellent heat resistance such as polyimide or fluororesin. The epoxy resin cured by adding the curing agent can be adjusted in viscosity by the amount of the curing agent added, and is therefore suitable for the present invention. Thermoplastic acrylic or silicone resins may also be used.

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. If the resin content is more than 5 wt%, the resin formed between the first magnetic powders enters, and the second magnetic powder cannot fill the gap, and the core density decreases, and the magnetic permeability decreases.

The viscosity of the resin is preferably 50 to 5000 mPas when mixed with the magnetic powder. 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.

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 filler as the viscosity adjusting material is preferably equal to or smaller than the average particle diameter of the second magnetic powder, and is preferably equal to or smaller than 1/3 of the average particle diameter of the second magnetic powder. This is because, if the average particle diameter of the filler is large, the density of the obtained core decreases. 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.

The coil is a wire that has been subjected to insulation coating, and a copper wire or an aluminum wire may be used as the wire. The coil is formed or attached by winding a wire around at least a part of the core, and is disposed around at least a part of the core. The winding form of the coil and the shape of the wire are not particularly limited.

[1-2. method for manufacturing reactor ]

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

(1) Mixing procedure

The mixing step is a step of mixing the magnetic powder with the resin. When the magnetic powder includes two types of magnetic powder having different average particle diameters, the mixing step includes: a magnetic powder mixing step of mixing a first magnetic powder with a second magnetic powder having a smaller average particle diameter than the first magnetic powder to form a magnetic powder; and a resin mixing step of adding 3 to 5 wt% of a resin to the magnetic powder to mix the magnetic powder with the resin.

The mixing in each mixing step can be performed automatically or manually using a predetermined mixer. The mixing time in each mixing step is not particularly limited, and may be, for example, 2 minutes.

By the mixing step described above, a mixture of the magnetic powder and the resin (hereinafter also referred to as a composite magnetic material) can be obtained. In the mixing step, the magnetic powder and the resin may be filled into a container for molding the composite magnetic material in the molding step, and the magnetic powder and the resin may be mixed. This eliminates the need to transfer the composite magnetic material to a container, and can reduce the number of manufacturing steps.

(2) Shaping step

The molding step is a step of adding the composite magnetic powder to a container having a predetermined shape and molding the composite magnetic powder into the container having the predetermined shape. In the molding step, the coil may be molded by adding the composite magnetic powder together.

As the container, containers of various shapes are used according to the shape of the core to be manufactured. In the case of incorporating a coil, a box-shaped or dish-shaped container having an open top surface is used to allow insertion of the coil from above. The container used in the molding process may be used as it is as a packaging case for a reactor that houses the core and the coil. If the container is used as a packaging box, there is an advantage that the container does not need to be taken out after the composite magnetic powder is cured. In the case where the container is not used as a packing case, a plurality of reactors can be manufactured by using one container. That is, a plurality of recesses may be formed in advance in the bottom of the container, and the composite magnetic material and the coil may be added to the recesses to manufacture a plurality of reactors. As described above, since a plurality of reactors are completed in one molding step, the manufacturing efficiency can be improved.

The container used in the molding step may be formed entirely or partially by a resin molded article. By making the container of resin, the manufacturing cost can be reduced, and the advantage of being able to form the MC core in any shape can be effectively utilized. That is, since the resin is a relatively inexpensive material, the manufacturing cost of the container can be suppressed, and the core having an arbitrary shape can be formed by injection molding or the like. Examples of the material for the resin molded article include: unsaturated polyester resin, urethane resin, epoxy resin, Bulk Molding Compound (BMC), polyphenylene sulfide (PPS), polybutylene terephthalate (PBT), and the like.

The container may be entirely or partially made of a metal having high thermal conductivity, such as aluminum or magnesium. This is because, as described later, the composite magnetic material is easily heated in the pressurizing step.

(3) Pressurizing step

The pressing step is a step of pressing the composite magnetic material with a pressing member in the molding step. The clay-like composite magnetic material charged into the container is extruded by the extrusion member to expand the composite magnetic material into the shape of the container, and voids contained in the composite magnetic material are reduced to improve the apparent density and magnetic permeability.

In the case where no coil is added to the container, the composite magnetic material is formed into the shape of the inside of the container by the above-described steps. That is, a molded article having a predetermined shape including the composite magnetic material can be obtained.

In the case of adding a coil to a container, as shown in fig. 2, a composite magnetic material 20 is added to the container 10, and the composite magnetic material 20 is expanded into the shape of the container 10 by a pressing member 30. Then, the coil 40 is inserted into the space formed by pressing the composite magnetic material 20, the composite magnetic material 20 is filled, and the composite magnetic material 20 is pressed together with the coil 40 from above by the pressing member 32. Alternatively, the composite magnetic material 20 may be put into the container 10, and then the coil 40 may be embedded in the composite magnetic material 20 including the inner and outer peripheries thereof, and the composite magnetic material 20 may be pressed from above together with the coil 40. As described above, by pressing the composite magnetic material 20 together with the coil 40, the voids contained in the composite magnetic material 20 can be reduced, and the apparent density and the magnetic permeability can be improved. Further, it is also possible to avoid the portion where the coil 40 exists and to press only the composite magnetic material 20. As described above, the composite magnetic material molded body having a predetermined shape including the coil can be obtained by the above-described steps.

As described above, in the pressurizing step, the composite magnetic material can be extruded by the extruding member to form the material into the shape of the container, and in this case, the pressurizing step can be understood as a pressurizing step and a molding step.

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. Even if the above value is not less than the above value, it is 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.

The time for extruding the composite magnetic material can be appropriately changed depending on the content or viscosity of the resin. For example, 10 seconds may be set.

The pressurizing step may be performed by setting the container or the pressing member for pressing the composite magnetic material to a temperature higher than normal temperature (e.g., 25 ℃). When the temperature of the container or the pressing member is increased, the resin is heated and softened. Therefore, the composite magnetic material easily flows into the gap in the container, the moldability can be improved, and the material easily flows into the void in the composite magnetic material, the density can be improved. The temperature of the container or the pressing member for pressing the composite magnetic material is preferably higher than the softening point of the resin contained in the composite magnetic material. This is because the resin can be effectively softened. The pressurizing step may be performed while maintaining the temperature of the container or the pressing member for pressing the composite magnetic material.

In addition, in the pressurizing step, the temperature of the container or the pressing member may be increased in advance, and the composite magnetic material itself may be heated in advance to press the composite magnetic material. The composite magnetic material itself may be heated and extruded in advance while maintaining the temperature of the container or the extrusion member that extrudes the composite magnetic material.

(4) Curing step

The curing step is a step of curing the resin in the molded body obtained in the molding step. In the case where the resin in the molded body 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 changed every time the resin is repeatedly dried.

[1-3. Effect ]

(1) A method for manufacturing a reactor according to the present embodiment is a method for manufacturing a reactor including a core including magnetic powder and resin, and a coil mounted on the core, the method including: a mixing step of mixing 3 to 5 wt% of a resin with respect to the magnetic powder; a molding step of molding the mixture obtained in the mixing step and the coil by being put into a predetermined container; a pressing step of pressing the mixture in the molding step; and a curing step of curing the molded body obtained in the molding step.

Thus, a core having not only the advantage of moldability but also improved productivity and density can be obtained. That is, since the amount of the resin is set to 3 to 5 wt%, the composite magnetic material is in a clay state and easy to handle, and productivity can be improved. Further, by including the pressing step, the advantage of the MC core that can mold the shape of the composite magnetic material into a predetermined shape, that is, the advantage of the moldability can be ensured, and by pressing the composite magnetic material, the material easily enters the voids contained in the composite magnetic material, and the apparent density of the core can be increased.

(2) AddingThe pressing step was carried out under a pressure of 6.3kg/cm for extruding the mixture²The above. This can increase the density of the core.

(3) The pressurizing step is performed by heating a member or a container for extruding the mixture to a temperature higher than the normal temperature. Thereby, the resin in the composite magnetic material as the mixture is heated and softened. Therefore, the composite magnetic material easily flows into the corners in the container, and moldability can be improved, and the material easily flows into the voids in the composite magnetic material, and density can be improved.

(4) The pressurizing step is performed by adding the mixture heated to a temperature higher than the normal temperature to the container. Thereby, the same action and effect as in (3) can be obtained.

(5) The magnetic powder is obtained by mixing two kinds of magnetic powder having different average particle diameters. In particular, the magnetic powder is obtained by mixing a first magnetic powder and a second magnetic powder having a smaller average particle size than the first magnetic powder, wherein the amount of the first magnetic powder added is 60 to 80 wt% and the amount of the second magnetic powder added is 20 to 40 wt%.

As a result, the second magnetic powder enters the gap between the first magnetic powders, and the density and permeability can be improved and the iron loss can be reduced.

(6) The first magnetic powder has an average particle diameter of 20 to 150 [ mu ] m, and the second magnetic powder has an average particle diameter of 5 to 20 [ mu ] m. This improves the density and permeability of the core, and reduces the iron loss.

(7) The resin is an epoxy resin, a silicone resin, or an acrylic resin. This makes it possible to make the composite magnetic material clay-like, to facilitate handling, and to improve productivity.

[2. embodiment II ]

[2-1. Structure ]

The reactor of the present embodiment has the same configuration as the reactor of embodiment I, and therefore, description thereof is omitted. That is, the core, the coil, the magnetic powder, and the resin are the same as those of embodiment I.

[2-2. method for manufacturing reactor ]

A method for manufacturing a reactor according to the present embodiment will be described with reference to the drawings. As shown in fig. 12, the method for manufacturing the reactor includes (1) a mixing step, (2) a molding step, (3) a pressing step, (4) a curing step, and (5) a magnetic field applying step. (1) Since the steps (a) to (4) are basically the same as the method for manufacturing the reactor according to embodiment I, the same portions will be omitted, and only different portions will be described.

(3) Pressurizing step

The pressing step is a step of pressing the composite magnetic material with a pressing member in the molding step. The clay-like composite magnetic material charged into the container is extruded by the extrusion member, whereby the composite magnetic material is expanded into the shape of the container, and voids contained in the composite magnetic material are reduced, thereby increasing the apparent density, initial permeability, and initial inductance value. The initial inductance value is an inductance value when no current flows through the coil of the reactor obtained by the present invention, that is, when the applied magnetic field in the curing step is 0 (kA/m).

(5) Magnetic field application step

The magnetic field applying step is a step of applying a magnetic field to a molded body including the composite magnetic material by energizing a coil included in the molded body in the curing step. When a coil is embedded in the molded body, the coil is energized. After the molded body is obtained, when a coil is formed by winding a wire around the molded body, the coil is energized.

The magnetic field application step may be performed until the resin in the molded article is cured, and may be performed before the curing step. In the case where the curing step is performed a plurality of times, the magnetic field application step may be performed between the curing steps.

In the magnetic field application step, the magnetic powder in the compact has orientation in accordance with the orientation of the applied magnetic field, and as a result, a core having high initial permeability can be obtained. That is, in the magnetic field applying step, since the coil included as the reactor is used as the element for applying the magnetic field to the molded body between the curing steps, the orientation of the magnetic flux generated by the reactor product itself has orientation, and therefore the magnetic flux generated by the reactor product itself coincides with the orientation of the magnetic powder.

The degree of the uniformity of the orientation is preferably such that the easy axis of magnetization of the magnetic powder coincides with the direction of magnetic flux (the direction of magnetic lines of force) generated by the coil included in the reactor, but the easy axis of magnetization may be inclined to about 45 ° with respect to the magnetic lines of force. As described above, the core having a high initial permeability can be obtained by the magnetic field application step.

The magnetic field applied to the molded article is preferably 2kA/m or more. This is because, as shown in the examples described later, the effect of increasing the L0 value by at least half of the saturation increase rate of the L0 value is obtained. The saturation increase rate of the L0 value is a change rate of the L0 value obtained based on the following formula (5), and L0(H) in the formula (5) is an initial inductance value of the reactor to which a magnetic field is applied during curing by applying a magnetic field of which the L0 value increases saturation.

When the second magnetic powder is excited, the magnetization directions of crystal grains in the magnetic powder are aligned, and the dc superimposition characteristics are improved by exciting the second magnetic powder.

Further, it is considered that a reactor including a core including a composite magnetic material oriented by excitation has an effect of reducing eddy current loss and heat generated by the core.

[2-3. action/Effect ]

(1) A method for manufacturing a reactor according to the present embodiment is a method for manufacturing a reactor including a core including magnetic powder and resin, and a coil mounted on the core, the method including: a mixing step of mixing 3 to 5 wt% of a resin with respect to the magnetic powder; a molding step of molding the mixture obtained in the mixing step and the coil by being put into a predetermined container; a curing step of curing the resin in the molded body obtained in the molding step; and a magnetic field application step of applying a magnetic field to the molded body by energizing the coil of the molded body in the curing step.

Thereby, a reactor including a core having a high initial permeability can be obtained. That is, in the conventional MC core, the amount of resin added to the magnetic powder exceeds 5 wt%, whereas the density and initial permeability can be improved by setting the amount to 3 wt% to 5 wt%. Further, since the magnetic powder in the molded body is oriented in the direction of the magnetic flux generated by the coil by energizing the coil included in the reactor itself at the time of the curing step, the magnetic powder can be oriented in the direction of the desired orientation, and therefore, the initial magnetic permeability can be improved.

(2) The magnetic field applying step sets the magnetic field to 2kA/m or more. This can provide a majority of the initial inductance improvement effect obtained in the magnetic field application step.

(3) Comprises a pressing step of pressing the mixture in a molding step. This can increase the density of the core.

(4) The pressurizing step is performed by setting the container or the member for pressing the mixture to a temperature higher than the normal temperature. This heats the resin in the mixture, i.e., the composite magnetic material, and softens it. Therefore, the composite magnetic material easily flows into the corners in the container, and moldability can be improved, and the material easily flows into the voids in the composite magnetic material, and density can be improved.

(5) The pressurizing step is performed by adding the mixture heated to a temperature higher than the normal temperature to the container. This can provide the same effects as those of (4).

(6) The magnetic powder is obtained by mixing two kinds of magnetic powder having different average particle diameters. In particular, the magnetic powder is obtained by mixing a first magnetic powder and a second magnetic powder having a smaller average particle size than the first magnetic powder, wherein the amount of the first magnetic powder added is 60 to 80 wt% and the amount of the second magnetic powder added is 20 to 40 wt%.

(7) The first magnetic powder has an average particle diameter of 20 to 150 [ mu ] m, and the second magnetic powder has an average particle diameter of 5 to 20 [ mu ] m. This improves the density and permeability of the core, and reduces the iron loss.

(8) The resin is an epoxy resin, a silicone resin, or an acrylic resin. This makes it possible to make the composite magnetic material clay-like, to facilitate handling, and to improve productivity.

[3. embodiment III ]

[3-1. Structure ]

The soft magnetic composite material according to the present embodiment is configured to include magnetic powder and resin. The resin contained in the soft magnetic composite material has a reduction rate (hereinafter referred to as heating loss) of 0.1% or less when exposed to an environment at 220 ℃ for 40 hours. The resin changes in volume or weight by prolonged exposure to high temperatures. The heating loss is a value indicating a rate of change in weight or volume of the resin before and after exposure to high temperature, and is calculated based on the weight or volume of the resin before and after exposure to high temperature. Hereinafter, the heating loss is calculated based on the change in weight of the resin, but may be calculated based on the change in volume. Even when the heating loss is calculated based on the weight change and the volume change, in the present embodiment, a resin having a heating loss of 0.1% or less when exposed to an environment at 220 ℃ for 40 hours is used.

In the present embodiment, a clay-like soft magnetic composite material is obtained by mixing magnetic powder and resin. In the present embodiment, the clay-like soft magnetic composite material is filled in a predetermined container and pressurized to form the magnetic core into a predetermined shape. The shape of the magnetic core may be various shapes such as a toroidal core, an I core, a U core, a θ core, an E core, and an EER core.

(magnetic powder)

A plurality of magnetic powders having different average particle diameters may be used as the magnetic powder. For example, two kinds of magnetic powders having different average particle diameters may be contained. Hereinafter, a mixed powder obtained by mixing two types of soft magnetic powders will be described as an example. However, the powder may not necessarily be a mixture of two kinds of powders. For example, 1 kind of soft magnetic powder may be used, and 3 or more kinds of soft magnetic powders may be mixed.

In the case of mixing two kinds of magnetic powders, 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. The weight ratio of the first magnetic powder to the second magnetic powder is preferably set to be: second magnetic powder 80: 20-60: 40. by setting the above range, the density is improved, the magnetic permeability is also 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 5 to 10 μm. By mixing two kinds of magnetic powders having different average particle diameters, the second magnetic powder having a small average particle diameter enters the gap between the first magnetic powders. This can improve the density and permeability and reduce the iron loss.

Soft magnetic powder can be used for the first magnetic powder and the second magnetic powder, and in particular, Fe powder, Fe — Si alloy powder, Fe — Al alloy powder, Fe — Si — Al alloy powder (sendust), a mixed powder of two or more of these powders, amorphous soft magnetic alloy powder, or the like can be used. 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 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 0.94 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. When 3 or more kinds of soft magnetic powders are mixed, 3 or more kinds of different magnetic powders may be mixed.

The first magnetic powder and the second magnetic powder may be produced by gas atomization, water atomization, or water gas atomization. The average circularity of the particles formed by these methods is preferably 0.90 or more, and when a powder having an average circularity of 0.90 or more cannot be formed only by various atomization methods, processing for increasing the average circularity of the particles may be further performed. For example, soft magnetic powder formed by a gas atomization method is substantially spherical particles. Therefore, the powder formed by the gas atomization method can be used as it is without processing. On the other hand, soft magnetic powder produced by the water atomization method is an aspherical particle having irregularities formed on the surface thereof. In this case, the average circularity of the particles can be increased by flattening the irregularities on the surface using a ball mill (ball mill), mechanical alloying (mechanical alloying), jet mill (jet mill), attritor (attritor), or a surface modifying device.

(resin)

The resin is mixed with the mixed powder, and has a function of holding the first powder and the second powder in a uniformly mixed state. The resin is mixed with the magnetic powder, and the mixed magnetic powder is retained. When the magnetic powder contains different kinds of powder having different average particle diameters, the respective powders are held in a uniformly mixed state. The resin has a heating loss of 0.1% or less, preferably 0.08% or less, when heated at 220 ℃ for 40 hours. The resin may be a curable resin. When the heating loss is 0.1% or less, a thermosetting resin, an ultraviolet-curable resin, or a thermoplastic resin can be used as the resin. As the thermosetting resin, phenol resin, epoxy resin, unsaturated polyester resin, polyurethane, diallyl phthalate resin, silicone resin, or the like can be used. As the ultraviolet-curable resin, acrylic urethane-based, acrylic epoxy-based, acrylic ester-based, or epoxy-based resins can be used. The thermoplastic resin is preferably a resin having excellent heat resistance such as polyimide or fluororesin. The epoxy resin cured by adding the curing agent can be adjusted in viscosity by the amount of the curing agent added, and is therefore suitable for the present invention. Thermoplastic acrylic or silicone resins may also be used.

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. If the resin content exceeds 5 wt%, the resin formed between the first magnetic powders enters, the second magnetic powder cannot fill the gap, and the like, and the density of the core decreases, and the initial permeability μ 0 decreases.

The viscosity of the resin is preferably 50 to 5000 mPas when mixed with the magnetic powder. When the viscosity is less than 50mPa · s, the resin does not become entangled with the magnetic powder during mixing, and the magnetic powder and the resin are easily separated from each other in the container, resulting in variation in the density and 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, the second magnetic powder cannot fill the gap, and the density of the core decreases, and the initial permeability μ 0 decreases.

(coil)

The coil is a wire that has been subjected to insulation coating, and a copper wire or an aluminum wire may be used as the wire. The coil is formed or attached by winding a wire around at least a part of the core, and is disposed around at least a part of the core. The winding method of the coil and the material and shape of the wire are not particularly limited.

[3-2. method for producing Metal composite core ]

A method for manufacturing a metal composite core according to the present embodiment will be described with reference to the drawings. As shown in fig. 22, the method for producing the metal composite core includes (1) a mixing step, (2) a molding step, (3) a pressing step, and (4) a curing step.

(1) Mixing procedure

The mixing step is a step of mixing the magnetic powder and the resin. The mixing process comprises the following steps: a magnetic powder mixing step of mixing a first magnetic powder with a second magnetic powder having an average particle diameter smaller than that of the first magnetic powder to form a magnetic powder; and a resin mixing step of adding 3 to 5 wt% of a resin to the magnetic powder to mix the magnetic powder and the resin.

By the mixing step described above, a mixture of the magnetic powder and the resin (hereinafter also referred to as a composite magnetic material) can be obtained. In the mixing step, the magnetic powder and the resin may be filled into a container for molding the composite magnetic material in the molding step and mixed. This eliminates the need to transfer the composite magnetic material to a container, and can reduce the number of manufacturing steps.

(2) Shaping step

As the container, containers of various shapes are used according to the shape of the core to be manufactured. In the case of incorporating a coil, a box-shaped or dish-shaped container having an open top surface is used to allow insertion of the coil from above. The container used in the molding process may be used as it is as a packaging box for the metal composite core containing the core and the coil. If the container is used as a packaging box, there is an advantage in that the container does not need to be taken out after the curing of the composite magnetic powder. Multiple metal composite cores may also be manufactured from one container without using the container as a packing box. That is, a plurality of metal composite cores may be manufactured by forming a plurality of recesses in advance in the bottom of the container, and adding the composite magnetic material and the coil to the recesses. As described above, since the plurality of metal composite cores are completed in one molding step, the manufacturing efficiency can be improved.

The container used in the molding step may be formed entirely or partially by a resin molded article. By making the container of resin, the manufacturing cost can be reduced, and the advantage of being able to form the MC core in any shape can be effectively utilized. That is, since the resin is a relatively inexpensive material, it is possible to form a core having an arbitrary shape by injection molding or the like while suppressing the manufacturing cost of the container.

In addition, the entire or a part of the container may be made of a metal having high thermal conductivity, such as aluminum or magnesium. This is because, as described later, the composite magnetic material is easily heated in the pressurizing step.

(3) Pressurizing step

The pressing step is a step of pressing the composite magnetic material with a pressing member in the molding step. The clay-like composite magnetic material charged into the container is extruded by the extrusion member, whereby the composite magnetic material is expanded into the shape of the container, and voids contained in the composite magnetic material are reduced, thereby increasing the apparent density and the initial permeability.

In the case of adding a coil to a container, as shown in fig. 2, a composite magnetic material 20 is added to the container 10, and the composite magnetic material 20 is expanded into the shape of the container 10 by a pressing member 30. Then, the coil 40 is inserted into the space formed by pressing the composite magnetic material 20, the composite magnetic material 20 is filled, and the composite magnetic material 20 is pressed together with the coil 40 from above by the pressing member 32. Alternatively, the composite magnetic material 20 may be put into the container 10, and then the coil 40 may be embedded in the composite magnetic material 20, and the composite magnetic material 20 may be pressed together with the coil 40 from above. As described above, by pressing the composite magnetic material 20 together with the coil 40, the voids contained in the composite magnetic material 20 can be reduced, and the apparent density and the magnetic permeability can be improved. Further, it is also possible to avoid the portion where the coil 40 exists and to press only the composite magnetic material 20. As described above, the composite magnetic material molded body having a predetermined shape including the coil can be obtained by the above-described steps.

As described above, the pressurizing step may be a step of extruding the composite magnetic material by the extrusion member to form the material into a container shape.

The pressure for extruding the composite magnetic material is preferably 2.0kg/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 10.0kg/cm²The following. This is because, even if the extrusion is performed beyond the above value, the effect of increasing the apparent density is small.

The time for extruding the composite magnetic material may be appropriately changed depending on the content or viscosity of the resin. For example, 10 seconds may be set.

The pressurizing step may be performed by setting the container or the pressing member for pressing the composite magnetic material to a temperature higher than normal temperature (e.g., 25 ℃). By raising the temperature of the container or the pressing member, the resin is warmed and becomes soft. Therefore, the composite magnetic material easily flows into the gap in the container, and moldability can be improved, and the material easily flows into the void in the composite magnetic material, and apparent density can be improved. The temperature of the container or the pressing member for pressing the composite magnetic material is preferably higher than the softening point of the resin contained in the composite magnetic material. This is because the resin can be effectively softened. The pressurizing step may be performed in a state where the temperature of the container or the pressing member for pressing the composite magnetic material is maintained.

In addition, in the pressurizing step, the composite magnetic material itself may be heated in advance to extrude the composite magnetic material, in addition to the temperature of the container or the extruding member being increased in advance. The composite magnetic material itself may be extruded while maintaining the temperature of the container or the extrusion member for extruding the composite magnetic material and heating the composite magnetic material itself in advance.

(4) Curing step

The curing step is a step of curing the resin in the molded body obtained in the molding step. When the resin in the molded body is cured by drying, the drying environment can be an atmospheric environment. In the curing step, the resin is cured by controlling the drying distribution of the drying temperature and time based on the dry state of the resin. The drying time may be appropriately changed depending on the kind, 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 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 or the drying time may be changed every time the resin is repeatedly dried.

[3-3. Effect ]

(1) The resin used for the magnetic core of the present embodiment has a reduction rate of 0.1% or less, preferably 0.08% or less, when the resin is exposed to an environment at 220 ℃ for 40 hours. The reduction rate is a reduction rate of the weight in the case where the resin is exposed to an environment at a high temperature. In the magnetic core produced from the soft magnetic composite material of the present embodiment, even when used at a high temperature for a long time, the magnetic powders in the magnetic core can be prevented from coming into contact with each other. In the magnetic core, eddy current according to the size of the soft magnetic powder contained therein is generated. When the core is exposed to a high temperature for a long time, if the reduction rate of the resin contained in the core exceeds 0.1%, the resin is decomposed and disappears due to the influence of heat. By the magnetic powders separated by the resin coming into contact with each other due to the disappearance of the resin, a larger eddy current is generated.

(2) The magnetic powder of the present embodiment uses a plurality of magnetic powders having different average particle diameters. For example, the average particle diameter of the first magnetic powder is set to 100 μm to 200 μm, and the average particle diameter of the second magnetic powder is set to 5 μm to 10 μm. In addition, the proportions of the magnetic powder were: the addition amount of the first magnetic powder is 60 wt% -80 wt%, and the addition amount of the second magnetic powder is 20 wt% -40 wt%. As a result, the second magnetic powder enters the gap between the first magnetic powders, and the density and permeability can be improved and the iron loss can be reduced.

(3) The resin may be a thermosetting resin, an ultraviolet-curable resin, or a thermoplastic resin, but a thermosetting resin may be used. Among them, epoxy resin is preferably used. The epoxy resin has a high glass transition point and excellent heat resistance, and does not produce volatile substances as a by-product during curing, so that the dimensional change of the molded article is small. Further, since the resin composition is rich in fluidity and can be molded even under a relatively low pressure, the process can be simplified.

(4) The magnetic core produced using the soft magnetic composite material of the present embodiment can suppress the rate of change in iron loss to a small value even when exposed to an environment of 155 ℃ for a long period of time. Further, it is preferable to use a soft magnetic composite material capable of producing a magnetic core in which the rate of change in iron loss when exposed to an environment at 155 ℃ for 500 hours or more is 10% or less. Even if the core of the magnetic powder is exposed to an environment of 155 ℃ for 1000 hours or more, the resin is not decomposed or lost by the influence of heat. In other words, this makes it possible to predict the rate of change in the iron loss at the time when 1000 hours have elapsed from the rate of change in the iron loss at the time when 500 hours have elapsed, and thus it is also possible to shorten the time for the high-temperature standing test.

[4. example ]

[4-1. example I ]

Hereinafter, example I of the present invention will be described with reference to tables 1 to 4 and fig. 3 to 11.

(1) Measurement items

The measurement items were density, magnetic permeability, and iron loss. For each core sample thus produced, a 40-turn winding was performed using a copper wire having a diameter of 2.6mm to produce a reactor. The shape of each sample of the core was a ring shape having an outer diameter of 35mm, an inner diameter of 20mm, and a height of 11 mm. The magnetic permeability and the iron loss of the reactor thus produced were calculated under the following conditions.

< Density >

The density of the core is the apparent density. That is, the outer diameter, inner diameter, and height of each core sample were measured, and based on pi × (outer diameter) from these values²Inner diameter²) X height to calculate the volume (cm) of the sample³). Then, the mass of the sample was measured, and the measured mass was divided by the calculated volume to calculate the density of the core.

< magnetic permeability and iron loss >

The permeability and the iron loss were measured under the conditions of a frequency of 20kHz and a maximum magnetic flux density Bm of 30 mT. The permeability is an amplitude permeability when the maximum magnetic flux density Bm is set at the time of measuring the iron loss Pcv. The iron loss was calculated by using a BH analyzer (SY-8232, manufactured by Citon instruments Co., Ltd.) as a magnetic measuring instrument. The calculation is performed by calculating a hysteresis loss coefficient and an eddy current loss coefficient by a least squares method from the frequency curve of the iron loss by the following expressions (1) to (3).

Pcv＝Kh×f+Ke×f²……(1)

Phv＝Kh×f……(2)

Pev＝Ke×f²……(3)

Pcv (Pcv): iron loss

Kh: coefficient of hysteresis loss

And Ke: coefficient of eddy current loss

f: frequency of

Phv: hysteresis loss

Pev: loss of eddy current

In this example, the average particle diameter and circularity of each powder were calculated as an average value of 3000 by using the following apparatus, and the powder was dispersed on a glass substrate, and a photograph of the powder was taken by a microscope, and each of the powder was automatically measured from an image.

Company name: malvern (Malvern)

Device name: particle size particle analyzer (morphologi) G3S

The specific surface area is measured by the Brunauer-EMMETT-Teller (BET) method.

(2) Method for preparing sample

The core sample was prepared from the viewpoints of (a) the pressing surface pressure in the pressing step, (b) the amount of resin, and (c) the difference in temperature of the container, as described below. These production methods and the results thereof are shown in the following order.

(a) Pressing surface pressure in the pressing step

First, as a mixing step, an Fe-6.5% Si alloy powder (circularity of 0.943) having an average particle size of 123 μm and an Fe-6.5% Si alloy powder (circularity of 0.908) having an average particle size of 5.1 μm were mixed in a weight ratio of 70: 30 in a V-blender for 30 minutes to form a magnetic powder. Then, the magnetic powder was added to an aluminum cup, 3.5 wt% of epoxy resin was added with respect to the magnetic powder, and mixed manually for 2 minutes using a spatula. Thereby, a composite magnetic material as a mixture of the magnetic powder and the resin is obtained.

Then, the composite magnetic material obtained in the mixing step was filled in a resin container having an annular space, and the composite magnetic material in the container was pressed for 10 seconds by a press of table 1 using a hydraulic press to prepare an annular molded body. During the extrusion, the temperature of the container was maintained at 25 ℃.

The molded body obtained by the pressing step and the molding step as described above was dried at 85 ℃ for 2 hours, then at 120 ℃ for 1 hour, and further at 150 ℃ for 4 hours in the air, to prepare a toroidal core as a sample.

[ Table 1]

Pcv[20kHz 30mT]

Table 1 and fig. 3 to 7 show the results of the density, permeability, and iron loss of the core in examples 1 to 3, comparative example 1, and comparative example 2 obtained by the respective press presses. Examples 1 to 3 set the pressing pressures to 400N, 600N, and 1000N, comparative example 1 set no pressing, and comparative example 2 set the pressing pressure to 100N. The pressed surfaces were all the same.

The "theoretical density" in table 1 is a ratio calculated from the apparent density of the core/the true density of the magnetic powder. Here, Fe-6.5% Si alloy powder was used as the first magnetic powder and the second magnetic powder, and the true density was set to 7.63g/cm³And the theoretical density was calculated.

Fig. 3 is a graph of theoretical densities with respect to surface pressure for examples 1 to 3 and comparative examples 1 and 2. As shown in table 1 and fig. 3, it is understood that the theoretical densities with respect to the surface pressure of examples 1 to 3, comparative examples 1 and 2 tend to be as follows: in comparison with comparative example 1 in which the pressurizing step was not performed, comparative example 2 and examples 1 to 3 in which the pressurizing step was performed had high theoretical densities and increased as the surface pressure increased. The surface pressure was 1.6kg/cm²Comparative example 2 (A) shows substantially no change in theoretical density as compared with comparative example 1 (B) having no pressurization, but has a surface pressure of 6.3kg/cm²In examples 1 to 3, the theoretical density reached 77.5% or more, which is higher than that in comparative examples 1 and 2. That is, it can be seen that the surface pressure was set to 6.3kg/cm²In the above, the material is spread over the gaps included in the composite magnetic material or the corners of the container, whereby the density is increased. In addition, it was found that the surface pressure became 6.3kg/cm²The theoretical density is substantially constant as described above.

Fig. 4 is an SEM photograph (100 x) of a core cross section of example 2. FIG. 5 is an SEM photograph (magnification 100) of a core cross-section of comparative example 1. In fig. 4 and 5, reference numeral 1 denotes a first magnetic powder, and reference numeral 2 denotes a second magnetic powder. The symbol 3 represents a resin, and the symbol 4 represents a void. The voids 4 are indicated by dark black in the SEM photograph, whereas the portions indicated by relatively light black are the resin 3. As is clear from fig. 4 and 5, in example 2 shown in fig. 4, the number of voids 4 in the composite magnetic material is reduced and the size of the voids 4 itself can be reduced as compared with comparative example 1 shown in fig. 5.

The magnetic permeability is amplitude magnetic permeability, and is calculated from the inductance of the intensity of each magnetic field of 20kHz and 1.0V using the impedance analyzer. "μ 0" in table 1 indicates the initial permeability in a state where no direct current is superimposed, that is, when the intensity of the magnetic field is 0H (a/m). "μ 12000" in Table 1 represents the magnetic permeability at a magnetic field strength of 12kH (kA/m).

Fig. 6 is a graph of magnetic permeability with respect to surface pressure for examples 1 to 3 and comparative examples 1 and 2. As shown in table 1 and fig. 6, it is understood that the magnetic permeability of the examples 1 to 3 under pressure is higher than that of the comparative example 1 under pressure. For example, it is found that the initial permeability μ 0 of example 1 is increased by about 8.7% as compared with comparative example 1. It is understood that in comparative example 2 in which pressure was applied, the permeability was also higher than that in comparative example 1 in which pressure was not applied, but the contribution to the increase in the density of the core was small.

Fig. 7 is a graph showing the iron loss with respect to the surface pressure in examples 1 to 3 and comparative examples 1 and 2. As shown in table 1 and fig. 7, it is understood that the iron loss is reduced in the examples 1 to 3 in which the pressure was applied, compared with the comparative example 1 in which the pressure was not applied. In particular, it is found that the hysteresis loss (Phv) tends to decrease by increasing the surface pressure. It is understood that in comparative example 2 in which the pressure was applied, the iron loss was reduced as compared with comparative example 1 in which the pressure was not applied, but the iron loss was further reduced in examples 1 to 3.

It can be seen that if the surface pressure reaches 6.3kg/cm²As described above, both the magnetic permeability and the iron loss are substantially constant, and the effect on the magnetic properties due to pressurization tends to be saturated. In other words, it was found that the surface pressure was 6.3kg/cm²～15.7kg/cm²In the range (b), the effects of improving the density and permeability and reducing the iron loss due to the inclusion of the pressing step can be obtained.

(b) Amount of resin

Samples of cores (examples 4 to 8 and comparative examples 3 to 5) were produced in the same procedure as in example 2, with the resin amounts in example 2 set to the conditions shown in table 2. Table 2, fig. 8, and fig. 9 show the results of density, permeability, and iron loss of examples 4 to 8 and comparative examples 3 to 5. In table 2, μ 0 and μ 12000 are the same as those in table 1.

[ Table 2]

Pcv[20kHz 30mT]

Fig. 8 is a graph of magnetic permeability with respect to the amount of resin for examples 4 to 8 and comparative examples 3 to 5. Fig. 9 is a graph showing the iron loss with respect to the amount of resin in examples 4 to 8 and comparative examples 3 to 5. As shown in table 2, fig. 8, and fig. 9, when the amount of the resin is less than 3 wt% with respect to the composite magnetic material, voids included in the core increase, and the density decreases. As a result, the permeability is decreased and the hysteresis loss is increased. If the amount of the resin is less than 3 wt%, the magnetic powders are likely to be in point contact with each other, which causes an increase in eddy current loss. On the other hand, if the amount of the resin exceeds 5 wt% with respect to the composite magnetic material, the decrease in density becomes remarkable. As a result, hysteresis loss increases.

(c) Temperature of the container

The temperature of the vessel was varied to make samples of the core. As described in (a), the temperature of the vessel was set to 25 ℃ in examples 1 to 3 and comparative example 1. The temperature of the vessel was set to 70 ℃ and the same procedure as in the above (a) was carried out except for the temperature of the vessel, and the samples thus obtained were set as examples 9 to 11 and comparative example 6. Table 3, fig. 10, and fig. 11 show the results of density, permeability, and iron loss of examples 1 to 3, examples 9 to 11, and comparative examples 1, 2, and 6. The theoretical densities μ 0 and μ 12000 in table 3 are the same as those in table 1.

[ Table 3]

Pcv[20kHz 30mT]

Fig. 10 is a graph of magnetic permeability against surface pressure for examples 9 to 11 and comparative example 6. Fig. 11 is a graph showing the iron loss with respect to the surface pressure in examples 9 to 11 and comparative example 6. As shown in table 3 and fig. 6, 7, 10, and 11, it is understood that, compared to examples 1 to 3 and comparative example 2 in which the temperature of the container is 25 ℃, examples 9 to 11 and comparative example 6 in which the temperature of the container is 70 ℃ tend to increase the density and the theoretical density, and also tend to decrease the iron loss. The magnetic permeability is increased or decreased according to the surface pressure.

It is also understood that the theoretical density of examples 9 to 11 was 77.9% or more while the temperature of the vessel was set to 70 ℃ and the surface pressure was increased to be higher than that of comparative example 6. As described above, by heating the container to above room temperature (25 ℃), the resin in the composite magnetic material becomes soft, and the material easily flows into the voids in the material, whereby it is considered that the apparent density increases and the theoretical density increases. As a result, it is understood that the effect of reducing the iron loss is obtained.

(d) Measurement of viscosity of resin

The viscosity of the resin used in this example will be described. The viscosity of the resin used in this example was determined as the viscosity of the resin by measuring the depth of penetration of a weight placed on the composite magnetic material, as described below.

That is, first, a composite magnetic material was produced in the same manner as in the mixing step (a) with the amount of resin added set to the conditions shown in table 4. Then, the obtained composite magnetic material was put into an aluminum container having a diameter of 5mm so that the thickness thereof became 3mm, and a 10g weight of Japanese Industrial Standard (JIS) was placed on the center of the composite magnetic material. After 10 seconds passed after the weight was placed, the weight was removed, and the depth of the pits in the composite magnetic material formed by the weight of the weight was measured. The results are shown in table 4.

[ Table 4]

The amount of resin [ wt.%]	Depth [ mm ]]
		3	0.264
4	0.489
		5	0.558

As shown in table 4, it was found that the greater the amount of resin added, the deeper the depth of the pits, the lower the viscosity of the composite magnetic material, and the weight easily sunk.

[4-2. example II ]

Hereinafter, example II of the present invention will be described with reference to tables 5 to 11 and fig. 13 to 21.

(1) Measurement items

The measurement items were density, permeability, iron loss, and inductance value (L value). For each core sample thus produced, a 40-turn winding was performed using a copper wire having a diameter of 2.6mm to produce a reactor. The shape of each sample of the core was a ring shape having an outer diameter of 35mm, an inner diameter of 20mm, and a height of 11 mm. The magnetic permeability, iron loss, and inductance value of the reactor were calculated under the following conditions.

< Density >

The density of the core is the apparent density. That is, the outer diameter, inner diameter, and height of each core sample were measured, and based on pi × (outer diameter) from these values²Inner diameter²) X height to calculate the volume (cm) of the sample³). Furthermore, the mass of the sample is measuredThe density of the core is calculated by dividing the measured mass by the calculated volume.

< magnetic permeability and iron loss >

Pcv＝Kh×f+Ke×f²……(1)

Phv＝Kh×f……(2)

Pev＝Ke×f²……(3)

Pcv (Pcv): iron loss

Kh: coefficient of hysteresis loss

And Ke: coefficient of eddy current loss

f: frequency of

Phv: hysteresis loss

Pev: loss of eddy current

< inductance value >

The inductance value was measured by winding a sample of the produced core 1 time (20 turns) at 20kHz and 1.0V using an impedance analyzer (Agilent Technology) 4294A.

In this example, the average particle diameter and circularity of each powder were calculated by using an average value of 3000 by using the following apparatus, the powder was dispersed on a glass substrate, a photograph of the powder was taken by a microscope, and each powder was automatically measured from an image.

Company name: malvern (Malvern)

Device name: particle size particle analyzer (morphologi) G3S

The specific surface area is measured by the BET method.

(2) Method for preparing sample

The core sample was prepared from the viewpoints of (a) presence/absence of an applied magnetic field, (b) magnitude of an applied magnetic field, and (c) presence/absence of a pressurizing step, as described below. These production methods and the results thereof are shown in the following order.

(a) Presence or absence of applied magnetic field

First, as a mixing step, a mixture of an Fe-6.5% Si alloy powder (circularity of 0.943) having an average particle size of 123 μm and an Fe-6.5% Si alloy powder (circularity of 0.908) having an average particle size of 5.1 μm was mixed in a weight ratio of 70: 30 in a V-blender for 30 minutes to form a magnetic powder. Then, the magnetic powder was added to an aluminum cup, and epoxy resin was added to the magnetic powder under the conditions shown in table 5, and the mixture was manually mixed for 2 minutes using a spatula. Thereby, a composite magnetic material as a mixture of the magnetic powder and the resin is obtained.

Then, the composite magnetic material obtained in the mixing step was filled in a resin container having an annular space, and the composite magnetic material in the container was pressed at 600N (surface pressure 9.4 kg/cm) using a hydraulic press²) The extrusion was carried out for 10 seconds to prepare a ring-shaped molded article. During the extrusion, the temperature of the container was maintained at 25 ℃.

Then, the obtained molded body was wound 40 times around the copper wire to form a coil, and a reactor as a base was manufactured.

Then, the reactor was dried at 85 ℃ for 2 hours, 120 ℃ for 1 hour, and 150 ℃ for 4 hours in the air to cure the resin, thereby preparing a toroidal core as a sample. At this time, the coil was energized so that the drying time at each temperature became 4.85kA/m, and samples of examples 12 to 16 were obtained. The difference between examples 12 and 16 is that the addition amount of the resin is 3.0 wt% to 5.0 wt%, respectively. In addition, toroidal coils were produced without applying a magnetic field during curing of the resin, and samples of comparative examples 7 to 11 were obtained.

[ Table 5]

Fig. 13 is a graph of initial permeability with respect to the amount of resin in the case where a magnetic field is applied and in the case where no magnetic field is applied. As shown in table 5 and fig. 13, it is understood that the initial permeability of the resin is increased for each amount of resin when a magnetic field is applied in the curing step.

Fig. 14 is a graph of the rate of change in permeability with respect to the amount of resin. The "rate of change" shown in table 5 and fig. 14 is the rate of change of initial permeability μ 0 between the case of applying a magnetic field and the case of not applying a magnetic field for each resin amount, and is a value calculated by equation (4). The rate of change is indicative of the extent of the effect of the applied magnetic field.

Rate of change μ 0(H)/μ 0(0) -1 … … (4)

μ 0 (H): initial permeability under applied magnetic field

μ 0 (0): initial permeability without application of magnetic field

As shown in fig. 14, the larger the amount of resin, the larger the rate of change. This is because the larger the amount of resin, the easier the magnetic powder is oriented by the applied magnetic field. It is found that the change rate is 10% or more in the range of 3.3 to 5.0 wt% of the resin amount, and the effect of improving the initial permeability is high.

(b) Magnitude of the applied magnetic field

Samples of the reactor were prepared by the same steps as in (a) except that the resin amount was set to 3 wt%, 4 wt%, and 5 wt%, the applied magnetic field was set to the same values as in table 6, and the applied magnetic field was set to the same values. Then, for each sample, the inductance value was measured as shown in the above "(1) measurement item". Further, from the measured inductance value L0, the rate of change in the L0 value was calculated based on equation (5). The results are shown in table 6.

[ Table 6]

Rate of change of L0 value L0(H)/L0(0) -1 … … (5)

L0 (H): initial inductance value of reactor manufactured in each applied magnetic field H in curing process

L0 (0): initial inductance value of reactor manufactured with applied magnetic field in curing step set to 0

Fig. 15 is a graph of the rate of change in L0 value with respect to the applied magnetic field in the curing step, and is obtained by plotting table 6. As shown in table 6 and fig. 15, it is found that the change rate of the L0 value tends to be larger as the resin amount is larger. The rate of change in the value of L0 is likely to increase in a region where the magnetic field is small, and is less likely to increase in a region where the magnetic field is large. That is, the L0 value increased before and after the applied magnetic field was 10kA/m, and saturation began.

Table 7 shows the L-value saturation increase rate and the half-value magnetic field of the L-value saturation increase rate for each resin amount. The L-value saturation increase rate is the rate of change in L0 value of a sample prepared with the applied magnetic field in the curing step set at 14.56kA/m, and the half-value magnetic field of the L-value saturation increase rate is the value of the applied magnetic field in the curing step at which the rate of change in L0 value is obtained, which is half the L-value saturation increase rate.

[ Table 7]

As shown in Table 7 and FIG. 15, it is understood that when the resin amount is 3 wt%, the applied magnetic field is 3.0kA/m or more, and a sufficient effect of improving the L0 value is obtained. When the amount of the resin is 4 to 5 wt%, the effect of sufficiently improving the L0 value is obtained by applying a magnetic field of 2kA/m or more. In these cases, by setting the applied magnetic field to 2kA/m or more, the rate of change in L0 value is equal to or more than half of the rate at which the effect of the magnetic field application during curing is saturated.

(c) Presence or absence of pressurization step

Samples were prepared as described below at a resin amount of 3 wt% to 5 wt% in the case of extrusion or non-extrusion of the composite magnetic material, and the difference in the obtained initial inductance value (L0) was examined.

(c-1) case where the amount of the resin is 3 wt%

< having a pressurizing step >

A sample of a reactor was produced in the same procedure as in (a) with the amount of the resin set to 3 wt% with respect to the magnetic powder. However, the applied magnetic field in the curing step is as shown in table 8.

< No pressurization Process >

A sample of a reactor was produced in the same procedure as in (a) with the amount of the resin set to 3 wt% with respect to the magnetic powder. However, the composite magnetic material was not pressed. That is, the composite magnetic material obtained in the mixing step is filled in a resin container having an annular space, and an annular molded body is produced without pressing. During this time, the temperature of the vessel was maintained at 25 ℃.

[ Table 8]

Then, with respect to the prepared samples, initial inductance values (L0) were calculated in the case where the pressurizing step was performed and in the case where the pressurizing step was not performed. Further, from the calculated inductance value (L0), the change rate is calculated based on the equation (5). The results are shown in table 8, fig. 16, and fig. 17.

Fig. 16 is a graph of the initial inductance values of the reactors fabricated in the respective applied magnetic fields in the curing step. As shown in fig. 16, L0 is high when the pressing step is performed. The main reason for this is considered to be that, by pressing the composite magnetic material, voids in the material are crushed, the number of voids is reduced, or the size of voids is reduced, whereby the apparent density of the core is increased, with the result that the initial permeability is increased.

Fig. 17 is a graph showing the change rate of the initial inductance value of the reactor produced in each applied magnetic field in the curing step. As shown in fig. 17, it is understood that when the applied magnetic field in the curing step is as low as about 5kA/m, no difference is observed in the presence or absence of the pressing step, but when the applied magnetic field is higher than this, the rate of change of L0 in the presence of the pressing step increases. In particular, it is found that when 9.27kA/m or more is obtained, the effect due to the pressing step remarkably appears.

(c-2) case where the amount of the resin is 4 wt%

The procedure for preparing samples in the case of the pressurized step and the case of the non-pressurized step was the same as the case of the (c-1) resin amount of 3 wt% except that the resin amount was set to 4 wt%. In addition, the initial inductance value (L0) was calculated in the same manner as in (c-1). From the calculated inductance value (L0), the change rate is calculated based on equation (5). The results are shown in table 9, fig. 18, and fig. 19.

[ Table 9]

Fig. 18 is a graph showing the initial inductance values of the reactors fabricated in the respective applied magnetic fields in the curing step. As shown in fig. 18, L0 was high in the case of the pressing step. The main reason for this is considered to be that, by pressing the composite magnetic material, voids in the material are crushed, the number of voids is reduced, or the size of voids is reduced, whereby the apparent density of the core is increased, with the result that the initial permeability is increased.

Fig. 19 is a graph showing the change rate of the initial inductance value of the reactor produced in each applied magnetic field in the curing step. As shown in fig. 19, it is understood that the rate of change of L0 is also higher in the case where the pressing step is performed.

(c-3) case where the amount of the resin is 5 wt%

The procedure for preparing samples in the case of the pressurized step and in the case of the non-pressurized step was the same as the case of the (c-1) resin amount of 3 wt% except that the resin amount was set to 5 wt%. In addition, the initial inductance value (L0) was calculated in the same manner as in (c-1). From the calculated inductance value (L0), the change rate is calculated based on equation (5). The results are shown in table 10, fig. 20, and fig. 21.

[ Table 10]

Fig. 20 is a graph showing the initial inductance values of the reactors fabricated in the respective applied magnetic fields in the curing step. Fig. 21 is a graph showing the change rate of the initial inductance value of the reactor produced in each applied magnetic field in the curing step. As shown in fig. 20 and 21, both the initial inductance value and the rate of change thereof are higher in the case where the pressurization step is present than in the case where the pressurization step is not present. But the difference is small. This is considered to offset the effect of increasing the initial permeability by increasing the proportion of resin in the composite magnetic material and increasing the apparent density by applying pressure.

As shown in fig. 21, it is understood that the higher the applied magnetic field in the curing step, the higher the rate of change of L0 in the case where the pressing step is present, as compared with the case where the pressing step is not present. The main reason for this is considered to be that the magnetic powder is likely to have uniform orientation by the applied magnetic field due to the large amount of resin contained.

(d) Measurement of viscosity of resin

The viscosity of the resin used in this example will be described. The viscosity of the resin used in this example was determined as the resin viscosity by measuring the depth of the weight placed on the composite magnetic material.

That is, first, composite magnetic materials were produced in the same manner as in the mixing step (a) with the amount of resin added set to the conditions shown in table 11. Then, the obtained composite magnetic material was put into an aluminum container having a diameter of 5mm so that the thickness thereof became 3mm, and a weight of 10g in accordance with JIS standard was placed on the center of the composite magnetic material. After 10 seconds passed after the weight was placed, the weight was removed, and the depth of the pits in the composite magnetic material formed by the weight of the weight was measured. The results are shown in table 11.

[ Table 11]

As shown in table 11, it is understood that the deeper the depth of the pits is, the lower the viscosity of the composite magnetic material is, and the weight easily sinks in, as the amount of the resin added is increased.

[4-3. example III ]

Hereinafter, example III of the present invention will be described with reference to tables 12 to 14 and fig. 23.

< resin (with respect to heating weight loss) >

4 kinds of resins A to D different in weight loss by heating were prepared, and test pieces to be samples were prepared using the resins A to D, and the weight loss by heating of each resin was measured. The heating loss of the resin was measured by the following method. Since the heating loss of the resin varies depending on the size of the sample, the sizes of the samples of the resins to be compared must be uniform. In this example, the heating loss of the resins a to D was measured using a cylindrical sample of "40 × 10(mm) in diameter".

(1) Method for measuring heating loss

(a) Preparation of test piece

First, a mold or a container having an inner diameter of a predetermined size is prepared. In this example, the predetermined size is a die having an inner diameter of "diameter 40 × height 10 (mm)". The molding material to be the material of the resins a to D was put into a mold, and the mold was heated to 150 ℃. By the applied heat, the molding material melts and then chemically reacts to solidify according to the shape of the mold. The heating time of the resins a to D at the time of sample preparation was set to 4 hours.

(b) Measurement of mass before heating

The cured resins a to D were taken out from the mold to obtain test pieces a to D. The mass of each of the test pieces A to D was measured to 1 mg. The value is set to M0.

(c) High temperature standing test

Test pieces A to D were heated to 220 ℃. The heating time was set to 20 hours or 40 hours.

(d) Measurement of mass after heating

The test pieces A to D after a predetermined period of time were taken out, and after heat dissipation, the mass was measured to 1 mg. The value is set to M1.

(e) Calculation of heating decrement

The heating loss was calculated by the following equation.

(M0-M1) ÷ M0 × 100 ═ heat loss (%)

[ Table 12]

Table 12 is a graph showing the heating loss in the high-temperature standing test of 20 hours or 40 hours in an environment of 220 ℃. As shown in table 12, the loss by heating at 20 hours of exposure of resin a was 0.09%, the loss by heating at 40 hours was 0.12%, the loss by heating at 20 hours of exposure of resin B was 0.07%, the loss by heating at 40 hours was 0.08%, the loss by heating at 20 hours of exposure of resin C was 0.05%, the loss by heating at 40 hours was 0.05%, the loss by heating at 20 hours of exposure of resin D was 0.08%, and the loss by heating at 40 hours was 0.10%.

[ first characteristic comparison (comparison of influence on iron loss due to difference in heating loss) ]

In the first characteristic comparison, characteristics of the reactor manufactured using the resins a to D different in heating weight loss were compared.

(2) Measurement items

The measurement item is the iron loss. For each core sample thus produced, a reactor was produced by winding a copper wire having a diameter of 1.2mm for 40 turns 1 time and for 3 turns 2 times. The shape of each sample of the core was a ring shape having an outer diameter of 35mm, an inner diameter of 20mm, and a height of 11 mm. The iron loss of the reactor thus produced was calculated under the following conditions.

< iron loss >

The iron loss was measured under the conditions of a frequency of 20kHz and a maximum magnetic flux density Bm of 30 mT. The iron loss was calculated using a BH analyzer (Shi-8232, manufactured by Citon instruments Co., Ltd.) as a magnetic measuring device. The calculation is performed by calculating a hysteresis loss coefficient and an eddy current loss coefficient by a least squares method from the frequency curve of the iron loss by the following expressions (1) to (3).

Pcv＝Kh×f+Ke×f2……(1)

Phv＝Kh×f……(2)

Pev＝Ke×f2……(3)

Pcv (Pcv): iron loss

Kh: coefficient of hysteresis loss

And Ke: coefficient of eddy current loss

f: frequency of

Phv: hysteresis loss

Pev: loss of eddy current

Company name: malvern (Malvern)

Device name: particle size particle analyzer (morphologi) G3S

The specific surface area is measured by the BET method.

(3) Method for preparing sample

The sample of the core used Fe 6.5Si with an average particle size of 123 μm as the first magnetic powder. Then, Fe 6.5Si having an average particle diameter of 5.1 μm was prepared as the second magnetic powder. Then, the first magnetic powder and the second magnetic powder were mixed in a weight ratio of 70: 30 to obtain a mixture of two magnetic powders having different average particle diameters.

Then, the magnetic powder was added to an aluminum cup, and resins a to D were added to the magnetic powder, followed by manual mixing for 2 minutes using a spatula. Thereby, a composite magnetic material as a mixture of the magnetic powder and the resin is obtained.

Then, the molded body was dried at 85 ℃ for 2 hours in the air, then dried at 120 ℃ for 1 hour, and further dried at 150 ℃ for 4 hours to cure the resin, thereby forming a toroidal core as a sample, and a sample using resin a (comparative example 12), a sample using resin B (example 17), a sample using resin C (example 18), and a sample using resin D (example 19) were obtained. Then, the obtained toroidal core was wound with the copper wire 1 time and 40 turns and 2 times and 3 turns to fabricate a reactor serving as a base.

(4) Heat resistance test

Then, the samples of examples 17 to 19 and comparative example 12 were used to perform a high temperature standing test. In the high temperature leaving test, the samples of examples 17 to 19 and comparative example 12 were exposed to an atmosphere of 155 ℃ for 24 to 1000 hours, and the iron loss Pcv was measured thereafter.

[ Table 13]

Pcv Change Rate (%)

Table 13 shows the rate of change of iron loss (Pcv) when the samples of examples 17 to 19 and comparative example 12 were subjected to the high-temperature leaving test. The rate of change of the iron loss (Pcv) is calculated by the following equation, taking the iron loss (Pcv0) at the start of the test and the iron loss (Pcv1) after a predetermined time has elapsed.

(Pcv 1-Pcv 0) ÷ Pcv0 × 100 ═ Pcv rate of change (%)

Fig. 23 is a table created based on table 13. In fig. 23, the vertical axis represents the rate of change in iron loss (Pcv), and the horizontal axis represents the elapsed time in the high-temperature standing test.

As shown in fig. 23, when the samples of examples 17 to 19 and comparative example 12 were exposed to 155 ℃, the rate of change in the iron loss (Pcv) was greatly increased in all the samples from the start of the test to 24 hours after the start of the test. The rate of change in iron loss (Pcv) of the samples of examples 17 to 19 and comparative example 12 after 24 hours from the start of the test was 6.3% to 9.3%. This is a phenomenon that occurs regardless of the heating loss of the resin, and the stress generated at this time affects (Pcv) by heating the resin to cure the resin again.

The rate of change of the iron loss (Pcv) did not change significantly in all samples from the start of the test to 400 hours after the start of the test. However, the rate of change in the iron loss (Pcv) of the sample (resin a) of comparative example 12 was large at the time when 400 hours had elapsed after the start of the test. On the other hand, the rate of change of the iron loss (Pcv) of the samples (resin B to resin D) of examples 17 to 19 did not change greatly when 400 hours elapsed after the start of the test. This is because the resin contained in the sample of comparative example 12 was decomposed or disappeared by heat, the magnetic powders were in contact with each other, and the eddy current loss Pev was increased, whereas the resin contained in the samples of examples 17 to 19 was not decomposed or disappeared.

Further, when 500 hours passed after the start of the test, the rate of change (%) in the iron loss (Pcv) of the sample (resin D) of example 19 was increased. This is considered to be because the resin D having a slightly higher heating loss at 40 hours started to decompose or disappear by heat as compared with the resin B having a heating loss at 40 hours of 0.08% or the resin D having a heating loss at 40 hours of 0.05%.

On the other hand, in the samples of example 17 and example 18 in which the weight loss by heating was 0.08% or less when the resin B and the resin C were heated at 155 ℃ for 40 hours, the rate of change (%) in the iron loss (Pcv) did not change greatly even after 1000 hours from the start of the test. This is because the resin contained in the samples of examples 17 and 18 was not decomposed or disappeared by heat, and the insulation between the magnetic powders was secured, and therefore, the increase of the eddy current loss Pev was suppressed.

From the above, by using a resin whose heating loss at the time of exposure to an environment at 220 ℃ for 40 hours is 0.1% or less, it is possible to suppress a change in iron loss (Pcv) even when the magnetic core is exposed to an environment at 155 ℃ for more than 400 hours. Further, by using a resin having a heating loss of 0.08% or less when exposed to an environment at 220 ℃ for 40 hours, it is possible to suppress a change in iron loss (Pcv) even when the magnetic core is exposed to an environment at 155 ℃ for more than 1000 hours.

(Change in iron loss Pcv in detail)

The iron loss Pcv is a total value of the hysteresis loss Phv and the eddy current loss Pev. In the high-temperature standing test in table 12 and fig. 23, the eddy current loss Pev is listed as a cause of the increase in the iron loss Pcv. Hereinafter, the rise in the change rate (%) of Pcv and the change amounts of the hysteresis loss Phv and the eddy current loss Pev were examined by taking the samples of comparative example 12 and example 18 using the resin a as examples.

Table 14 shows values of iron loss Pcv, hysteresis loss Phv, and eddy current loss Pev from the start of the test to 1000 hours after the start of the test for the sample of comparative example 12 using resin a and the sample of example 18 using resin C.

[ Table 14]

As shown in table 14, in the sample of comparative example 12, the eddy current loss Pev after the elapse of 400 hours from the start of the test was 6.2, whereas the eddy current loss Pev after the elapse of 1000 hours from the start of the test was 9.0. The rate of change of the eddy current loss Pev at this time was 45% in terms of (9.0-6.2)/6.2X 100. On the other hand, the hysteresis loss Phv after the lapse of 400 hours from the start of the test was 21.3, whereas the hysteresis loss Phv after the lapse of 1000 hours from the start of the test was 23.1. The rate of change of the hysteresis loss Phv at this time was found to be about 8.5% in terms of (23.1-21.3)/21.3X 100. That is, as is clear from table 14 and fig. 23, when the rate of change of Pcv greatly changes, eddy current loss Pev greatly changes.

On the other hand, in the sample of example 18, the eddy current loss Pev after the elapse of 400 hours from the start of the test was 6.0, whereas the eddy current loss Pev after the elapse of 1000 hours from the start of the test was 6.1. The rate of change of the eddy current loss Pev was 1.7% in terms of (6.1-6.0)/6.0X 100. On the other hand, the hysteresis loss Phv after the lapse of 400 hours from the start of the test was 20.1, whereas the hysteresis loss Phv after the lapse of 1000 hours from the start of the test was 20.2. The rate of change of the hysteresis loss Phv is about 0.5% in terms of (20.2-20.1)/20.1 × 100. In table 14, in the sample of example 18, neither the eddy current loss Pev nor the hysteresis loss Phv changed significantly. Therefore, it is also understood from table 14 and fig. 23 that the change rate (%) of the iron loss Pcv is small.

(conclusion)

From the above, it is understood that the change rate (%) of the iron loss Pcv can be suppressed to be small even when the magnetic core made of the soft magnetic composite material containing the resin of which the loss by heating is 0.1% or less when heated at 220 ℃ for 40 hours is used at 155 ℃ for a long time. This is because the resin having a small heating loss when heated at 220 ℃ for 40 hours is not decomposed or lost even when exposed to a high-temperature environment for a long time, and therefore, the contact between the magnetic powders can be suppressed, and low eddy current loss can be achieved.

[ 5] other embodiments ]

The present invention is not limited to the above-described embodiments, and constituent elements may be modified and embodied in the implementation stage without departing from the gist thereof. In addition, various inventions can be formed by appropriate combinations of a plurality of constituent elements disclosed in the above embodiments. For example, some of the components shown in the embodiments may be deleted. Further, the constituent elements in the different embodiments may be appropriately combined.

For example, in embodiment II, a method in which a coil is incorporated into a container and embedded in a composite magnetic material in a molding step has been described as a method for providing a coil in a reactor, but a method including a winding step in which a molded body having a predetermined shape and containing a composite magnetic material is molded in advance and a lead wire constituting the coil is wound around the molded body may be adopted.

In embodiment III, a method in which a coil is incorporated into a case and embedded in a composite magnetic material in a molding step has been described as a method for providing a coil in a reactor, but a method including a winding step in which a molded body having a predetermined shape and containing a composite magnetic material is molded in advance and a lead wire constituting the coil is wound around the molded body may be adopted.

In embodiment III, the magnetic core is produced by pouring a soft magnetic composite material in which soft magnetic powder and resin are mixed in advance into a container, but may be produced by the following method. After the mixed powder of the first powder and the second powder is filled in the container, the container is vibrated as a whole, thereby increasing the density of the mixed powder in the container. Then, the mixed powder whose density is increased by the vibration penetrates the resin, and is cured by a curing method according to the kind of the resin. As a method of vibration, the following method may be used: the entire container is vibrated vertically or/and back and forth and left and right by a motor, a cam, or the like, or tapped, or the container is tapped lightly by a hammer-like member. The entire container may be vibrated by the ultrasonic vibrator.

Further, in embodiment III, a pressing step of pressing the composite magnetic material which is easy to enter by a pressing member is included between the molding step and the curing step, but the pressing step may be omitted. Depending on the type of magnetic powder or resin used, or the method of the molding step, a magnetic core having excellent magnetic properties can be molded without the need for the pressing step. In this case, the pressing step can be omitted for the purpose of reducing the number of steps or cost.

Claims

1. A method for manufacturing a reactor including a core containing magnetic powder and resin, and a coil mounted on the core, the method comprising:

a mixing step of mixing 3 to 5 wt% of a resin with respect to the magnetic powder;

a molding step of molding the mixture obtained in the mixing step and the coil in a predetermined container;

a pressing step of pressing the mixture in the molding step; and

a curing step of curing the resin in the molded body obtained in the molding step,

the pressing step includes:

a step of adding the mixture to the container and expanding the mixture into the shape of the container by using a pressing member; and

and a step of filling the mixture into a coil inserted into a space formed by expanding the mixture, and pressing the mixture together with the coil from above by a pressing member.

2. The reactor manufacturing method according to claim 1, characterized in that,

the pressure for extruding the mixture in the pressurizing step was 6.3kg/cm²The above.

3. The reactor manufacturing method according to claim 1 or 2, characterized in that,

the pressurizing step is performed by heating a member for pressing the mixture or the container to a temperature higher than normal temperature.

4. The reactor manufacturing method according to claim 1 or 2, characterized in that,

the pressurizing step is performed by adding the mixture heated to a temperature higher than the normal temperature to the container.

5. The reactor manufacturing method according to claim 1 or 2, characterized in that,

the magnetic powder is formed by mixing two kinds of magnetic powder with different average grain diameters.

6. The reactor manufacturing method according to claim 5, characterized in that,

the magnetic powder is obtained by mixing a first magnetic powder and a second magnetic powder having a smaller average particle diameter than the first magnetic powder, and

the addition amount of the first magnetic powder in the magnetic powder is 60 wt% -80 wt%, and the addition amount of the second magnetic powder is 20 wt% -40 wt%.

7. The reactor manufacturing method according to claim 6, characterized in that,

the first magnetic powder has an average particle diameter of 100 to 200 [ mu ] m, and

the second magnetic powder has an average particle diameter of 3 to 10 μm.

8. The method of manufacturing a reactor according to claim 1, 2, 6, or 7, characterized in that,

the resin is epoxy resin, silicone resin, or acrylic resin.

9. A method for manufacturing a reactor including a core containing magnetic powder and resin, and a coil mounted on the core, the method comprising:

a molding step of adding the mixture obtained in the mixing step and the coil to a predetermined container to mold the mixture;

a pressing step of pressing the mixture in the molding step;

a curing step of curing the resin in the molded body obtained in the molding step; and

a magnetic field applying step of applying a magnetic field to the molded body by energizing the coil of the molded body in the curing step,

the pressing step includes:

10. A method for manufacturing a reactor including a core containing magnetic powder and resin, and a coil mounted on the core, the method comprising:

a molding step of adding the mixture obtained in the mixing step to a predetermined container to mold the mixture;

a winding step of winding a wire constituting the coil around the molded body obtained in the molding step;

a curing step of curing the resin in the molded body around which the lead wire is wound; and

a magnetic field applying step of applying a magnetic field to the molded body by applying a current to the conductive wire in the curing step,

the magnetic field in the magnetic field application step is 2kA/m or more and 10kA/m or less.

11. The method of manufacturing a reactor according to claim 10, characterized by comprising:

and a pressing step of pressing the mixture in the molding step.

12. The reactor manufacturing method according to claim 9 or 11, characterized in that,

the pressurizing step is performed by maintaining a member for pressing the mixture or the container at a temperature higher than normal temperature.

13. The reactor manufacturing method according to claim 9 or 11, characterized in that,

14. The reactor manufacturing method according to claim 9 or 10, characterized in that,

15. The reactor manufacturing method according to claim 14, characterized in that,

16. The reactor manufacturing method according to claim 15, characterized in that,

the second magnetic powder has an average particle diameter of 3 to 10 μm.

17. The method of manufacturing a reactor according to claim 9 to 11, 15, or 16,

the resin is epoxy resin, silicone resin, or acrylic resin.