WO2018105697A1

WO2018105697A1 - Method for producing reactor, method for producing core, core, reactor, soft magnetic composite material, magnetic core using soft magnetic composite material, and reactor using soft magnetic composite material

Info

Publication number: WO2018105697A1
Application number: PCT/JP2017/044027
Authority: WO
Inventors: 泰雄大島; 渡 ▲高▼橋
Original assignee: 株式会社タムラ製作所
Priority date: 2016-12-08
Filing date: 2017-12-07
Publication date: 2018-06-14
Also published as: CN110062948A; CN110062948B; CN112992453A

Abstract

Provided are: a method for producing a reactor, which is capable of improving the productivity and the density, while achieving an advantage in terms of moldability; a method for producing a core; a core; and a reactor. This method for producing a reactor, which is provided with a core that contains a magnetic powder and a resin and a coil that is fitted to the core, comprises: a mixing step wherein 3-5 wt% of a resin is mixed into a magnetic powder; a molding step wherein a mixture obtained in the mixing step and a coil are put into a specific container and are subsequently molded therein; a pressurizing step wherein the mixture is pressurized during the molding step; and a curing step wherein a molded body obtained in the molding step is cured.

Description

Reactor manufacturing method, core manufacturing method, core, reactor, soft magnetic composite material, magnetic core using soft magnetic composite material, and reactor using soft magnetic composite material

The present invention uses a reactor manufacturing method having a metal composite core made of magnetic powder and resin, a core manufacturing method, a soft magnetic composite material suitable for a reactor called a core, a reactor, and a metal composite type, and a soft magnetic composite material. The present invention relates to a reactor using a magnetic core and a soft magnetic composite material.

Reactors are used in various applications such as office automation equipment, solar power generation systems, automobiles, and uninterruptible power supplies. The reactor is used, for example, in a filter that prevents the harmonic current from flowing out to the output system, a voltage raising / lowering converter that raises or lowers the voltage, and the like.

Reactors are required to have magnetic properties such as magnetic permeability, inductance value, and iron loss according to the application. For example, a reactor used for a voltage raising / lowering converter is required to improve energy conversion efficiency, and thus is required to have a small iron loss as an energy loss.

There is also a desire to mold the core used in the reactor into any shape to accommodate various applications. As a reactor that meets such a demand, there is a reactor equipped with a core type called a metal composite core.

The metal composite core (hereinafter, also simply referred to as MC core) is a core formed by molding a material obtained by mixing metal magnetic powder and resin into a predetermined shape and solidifying it. The conventional MC core is in the form of a slurry, is easy to pour the material into a container, and has an advantage in moldability that can form a predetermined shape.

A reactor called a metal composite type is a reactor that is manufactured by integrally molding a magnetic core and a coil using a material in which soft magnetic powder and resin are mixed. This reactor is characterized in that it is less likely to be magnetically saturated in a high temperature range as compared with a multilayer reactor using ferrite as a magnetic core.

The magnetic core used in the metal composite type reactor is called a metal composite core. This is manufactured by mixing a soft magnetic powder and a resin to prepare a soft magnetic composite material and solidifying it. Patent Document 2 discloses a method of obtaining a soft magnetic composite material having a relatively low relative permeability and a high saturation magnetic flux density by using a soft magnetic powder having a predetermined density ratio.

JP 2012-33727 A JP 2014-160828 A

As described above, the conventional MC core has an advantage of good moldability because the material obtained by mixing magnetic powder and resin is in the form of slurry. However, on the other hand, when an operator pours the material into the container, the material is easily spilled.

In addition, since the conventional MC core material has a high resin content, the proportion of the magnetic powder in the material is reduced, leading to a decrease in core density, resulting in a decrease in magnetic properties.

Therefore, it is conceivable to increase the density of the magnetic powder contained in the material by reducing the amount of resin. However, if the amount of resin is reduced, it becomes difficult for the material to flow into every corner of the container, and the moldability that is an advantage of the MC core is impaired. Thus, it has been difficult to achieve all of moldability, productivity, and high density with the conventional MC core.

Also, the MC core has flat magnetic characteristics. That is, the MC core is less likely to be magnetically saturated than the ferrite core, and has a characteristic that the permeability is less likely to decrease even when the current flowing through the coil is increased. That is, 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.

By the way, as a technique for increasing the magnetic permeability, a technique for aligning the magnetic powder in the MC core by applying a magnetic field from the outside in the MC core manufacturing process is known (Patent Document 1).

In such a conventional technique, a conductive member for forming a current path is separately provided, a magnetic field is generated by energizing the conductive member, and a magnetic field is applied to the MC core material from the outside. Such a conductive member is provided, for example, outside the container containing the MC core material, and the installation position of the conductive member needs to be moved in order to obtain a desired orientation.

However, due to restrictions on the installation conditions of the conductive member, it is difficult to generate magnetic flux in the direction in which it is actually desired to be oriented. For this reason, the direction of actual orientation and the direction of the magnetic flux generated by the conductive member are inconsistent, and the effect of increasing the initial permeability may not be obtained.

Also, in the MC core, resin exists between the magnetic powders to prevent contact between the magnetic powders. In other words, the insulation between the magnetic powders is ensured by the resin. When such an MC core is used at a high temperature for a long time, the resin is decomposed, and a decrease in magnetic properties due to contact between magnetic powders is regarded as a problem.

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

A first object of the present invention is to provide a reactor manufacturing method, a core manufacturing method, a core, and a reactor capable of improving productivity and density while obtaining advantages of moldability.

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

The third object of the present invention is proposed to solve the above-mentioned problems of the prior art, and is a composite soft magnetic composite that suppresses deterioration of magnetic properties when used for a long time at high temperature. The object is to provide a material, a metal composite core, and a metal composite core manufacturing method.

In order to achieve the first object, 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 a resin, and a coil attached to the core. It is provided with.
(1) A mixing step of mixing 3 to 5 wt% resin with respect to the magnetic powder.
(2) A molding step of molding the mixture obtained in the mixing step and the coil in a predetermined container.
(3) A pressurizing step of pressing the mixture during the molding step.
(4) 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 magnetic powder and a resin,
The following configuration is provided.
(1) A mixing step of mixing 3 to 5 wt% resin with respect to the magnetic powder.
(2) A molding step of molding the mixture obtained in the mixing step in a predetermined container.
(3) A pressurizing step of pressing the mixture during the molding step.
(4) A curing step of curing the resin in the molded body obtained in the molding step.

The core of the present invention is a core made of magnetic powder and resin, and has the following configuration.
(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 to 80 wt%, and the second magnetic powder is 20 to 40 wt%.
(3) The first magnetic powder has an average particle size of 100 μm to 200 μm, and the second magnetic powder has an average particle size of 3 μm to 10 μm.
(4) The content of the resin with respect to the magnetic powder is 3 to 5 wt%.
(5) The ratio of the apparent density of the core to the true density of the magnetic powder is more than 76.47%.

The present invention can also be understood as a reactor having the above core.

In order to achieve the second object, a method for manufacturing a reactor according to the present invention is a method for manufacturing a reactor including a core containing magnetic powder and a resin, and a coil attached to the core, and has the following configuration It is provided with.
(1) A mixing step of mixing 3 to 5 wt% resin with respect to the magnetic powder.
(2) A molding step of molding the mixture obtained in the mixing step and the coil in a predetermined container.
(3) A curing step of curing the resin in the molded body obtained in the molding step.
(4) A magnetic field applying step of energizing the coil of the molded body and applying a magnetic field to the molded body during the curing step.

A reactor manufacturing method according to the present invention is a reactor manufacturing method including a core including magnetic powder and a resin, and a coil mounted on the core, and has the following configuration. .
(1) A mixing step of mixing 3 to 5 wt% resin with respect to the magnetic powder.
(2) A molding step of molding the mixture obtained in the mixing step in a predetermined container.
(3) A winding step of winding a conductive wire constituting the coil around the molded body obtained in the molding step.
(4) A curing step of curing the resin in the molded body around which the conductive wire is wound.
(5) A magnetic field applying step of energizing the conducting wire during the curing step and applying a magnetic field to the molded body.

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

The reduction rate may be 0.08% or less.

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

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

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

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

The resin may be a thermosetting resin.

The resin may be an epoxy resin.

A magnetic core composed of the soft magnetic composite material as described above is also an embodiment of the present invention. The magnetic core may have an iron loss change rate of 10% or less when exposed to an atmosphere at 155 ° C. for 500 hours or more.

Furthermore, a reactor including the magnetic core is also an aspect of the present invention.

According to the present invention, it is possible to provide a reactor manufacturing method, a core manufacturing method, a core, and a reactor capable of improving productivity and density while obtaining advantages of moldability.

According to the present invention, it is possible to provide a method for manufacturing a reactor capable of obtaining a reactor having a core having a high initial permeability.

According to the present invention, in the soft magnetic composite material, the reduction rate when the resin mixed with the magnetic powder is exposed at 220 ° C. for 40 hours is 0.1% or less. As a result, even when the magnetic core and the reactor composed of this soft magnetic composite material are exposed to a high temperature for a long time, it is possible to suppress the disappearance of the resin existing between the magnetic powders. In the magnetic core and the reactor, it is possible to suppress a decrease in magnetic properties when used at a high temperature for a long time.

5 is a flowchart for explaining a reactor manufacturing method according to embodiment I. It is a figure for demonstrating a formation process and a pressurization process. 3 is a graph of theoretical density versus surface pressure in Examples 1 to 3 and Comparative Examples 1 and 2. 4 is a SEM photograph (100 times) of a core cross section of Example 2. FIG. 4 is a SEM photograph (100 times) of a core cross section of Comparative Example 1. 3 is a graph of magnetic permeability with respect to surface pressure in Examples 1 to 3 and Comparative Examples 1 and 2; 6 is a graph of iron loss versus surface pressure in Examples 1 to 3 and Comparative Examples 1 and 2. 7 is a graph of magnetic permeability with respect to surface pressure in Examples 4 to 6 and Comparative Example 3. 6 is a graph of iron loss versus surface pressure in Examples 4 to 6 and Comparative Example 3. 6 is a graph of magnetic permeability with respect to surface pressure in Examples 9 to 11 and Comparative Example 6. 6 is a graph of iron loss versus surface pressure in Examples 9 to 11 and Comparative Example 6. It is a flowchart for demonstrating the manufacturing method of the reactor which concerns on Embodiment II. It is a graph of the initial permeability with respect to the resin amount when not applying a magnetic field. It is a graph of the change rate of the magnetic permeability with respect to the resin amount. It is a graph of the change rate of the initial inductance value with respect to a magnetic field. It is a graph of the initial inductance value of the reactor produced by each applied magnetic field in a hardening process as resin amount 3wt%. It is a graph which shows the change rate of the initial inductance value of the reactor produced by each applied magnetic field in a hardening process as resin amount 3wt%. It is a graph of the initial inductance value of the reactor produced by each applied magnetic field in a hardening process as resin amount 4wt%. It is a graph which shows the change rate of the initial inductance value of the reactor produced with each applied magnetic field in a hardening process as the resin amount of 4 wt%. It is a graph of the initial inductance value of the reactor produced by each applied magnetic field in a hardening process as resin amount 5wt%. It is a graph which shows the change rate of the initial inductance value of the reactor produced with each applied magnetic field in a hardening process as resin amount 5wt%. It is a flowchart for demonstrating the manufacturing method of the metal composite core which concerns on Embodiment III. It is a graph which shows the relationship between the leaving time in a high temperature leaving test, and the iron loss Pcv.

[1. Embodiment I]
[1-1. Constitution]
The reactor of this embodiment includes a core and a coil. The core is a metal composite core composed of magnetic powder and resin. A core can be made 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 can be various shapes such as a toroidal core, an I-type core, a U-type core, a θ-type core, an E-type core, and an EER-type core.

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 a mixed powder of two or more of these powders. Etc. 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 μm to 150 μm. In the present specification, the “average particle diameter” refers to D50, that is, the median diameter unless otherwise specified.

The magnetic powder may be composed of two or more kinds of magnetic powders having different average particle diameters. In this case, the magnetic powder is composed of the first magnetic powder and the second magnetic powder having an average particle diameter smaller than that of the first magnetic powder, and the weight ratio thereof is the first magnetic powder: second magnetic powder. The powder is preferably 80:20 to 60:40. By setting it in this range, the density is improved, the magnetic permeability is improved, and the iron loss can be reduced.

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

Note that the types of the first magnetic powder and the second magnetic powder may be the same or different. If different, three or more may be used. When the magnetic powder is composed of three or more types of powders, the average particle size may be different for each type.

The first magnetic powder is preferably pulverized. As the second magnetic powder, those produced by a water atomizing method, a gas atomizing method, or a water / gas atomizing method can be used, and those by a water atomizing method are particularly preferable. The reason is that the water atomization method rapidly cools during atomization, so that the powder is difficult to crystallize.

Resin is mixed with magnetic powder to hold the magnetic powder. When the magnetic powder is composed of different types of powders having different average particle sizes, each powder is held in a homogeneously mixed state. As the resin, a thermosetting resin, an ultraviolet curable resin, or a thermoplastic resin can be used. As the thermosetting resin, phenol resin, epoxy resin, unsaturated polyester resin, polyurethane, diallyl phthalate resin, silicone resin and the like can be used. As the ultraviolet curable resin, urethane acrylate, epoxy acrylate, acrylate, and epoxy resins can be used. As the thermoplastic resin, it is preferable to use a resin having excellent heat resistance such as polyimide or fluororesin. An epoxy resin that is cured by adding a curing agent is suitable for the present invention because its viscosity can be adjusted by the amount of the curing agent added. Thermoplastic acrylic resins and silicone resins can also be used.

The resin is preferably contained in an amount of 3 to 5 wt% with respect to the magnetic powder. When the resin content is less than 3 wt%, the bonding strength of the magnetic powder is insufficient and the mechanical strength of the core is lowered. Also, if the resin content is more than 5 wt%, the resin formed between the first magnetic powder enters, the second magnetic powder cannot fill the gap, and the core density decreases, Magnetic permeability decreases.

The viscosity of the resin is preferably 50 to 5000 mPa · s when mixed with the magnetic powder. When the viscosity is less than 50 mPa · s, the resin does not get entangled with the magnetic powder during mixing, the magnetic powder and the resin are easily separated in the container, and the density or strength of the core varies. When the viscosity exceeds 5000 mPa · s, the viscosity becomes too high. For example, the resin formed between the first magnetic powders enters, and the gap cannot be filled with the second magnetic powder. Decreases, and the magnetic permeability decreases.

For the resin, SiO ₂ , Al ₂ O ₃ , Fe ₂ O ₃ , BN, AlN, ZnO, TiO ₂ or the like can be used as a viscosity adjusting material. The average particle diameter of the filler as the viscosity adjusting material is not more than the average particle diameter of the second magnetic powder, preferably not more than 1/3 of the average particle diameter of the second magnetic powder. This is because when the average particle size of the filler is large, the density of the obtained core decreases. Further, a high thermal conductivity material such as Al ₂ O ₃ , BN, or AlN can be added to the resin.

The ratio of the apparent density of the core to the true density of the magnetic powder is preferably more than 76.47%, and more preferably 77.5% or more. When the ratio is more than 76.47%, the magnetic permeability can be increased. On the other hand, when the ratio is 76.47% or less, low permeability results in low magnetic permeability.

The coil is a conductive wire with an insulating coating, and a copper wire or an aluminum wire can be used as the wire. The coil is formed or mounted by winding a conductive wire around at least a part of the core, and is arranged around at least a part of the core. The method of winding the coil and the shape of the wire are not particularly limited.

[1-2. Reactor manufacturing method]
The manufacturing method of the reactor which concerns on this embodiment is demonstrated referring drawings. As shown in FIG. 1, the reactor manufacturing method includes (1) a mixing step, (2) a molding step, (3) a pressing step, and (4) a curing step.

(1) Mixing step The mixing step is a step of mixing magnetic powder and resin. When the magnetic powder is composed of two kinds of magnetic powders having different average particle diameters, the mixing step includes the first magnetic powder and the second magnetic powder having an average particle diameter smaller than that of the first magnetic powder. Are mixed to form a magnetic powder, and a resin mixing step of adding 3 to 5 wt% of the resin to the magnetic powder and mixing the magnetic powder and the resin.

The mixing in each mixing step can be performed automatically or manually using a predetermined mixer. The mixing time of each mixing step can be set as appropriate, and is not particularly limited.

By such a mixing step, a mixture of magnetic powder and 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 and mixed in a container for molding the composite magnetic material in the molding step. Thereby, it is not necessary to transfer a composite magnetic material to a container, and a manufacturing man-hour can be reduced.

(2) Molding process The molding process is a process in which the composite magnetic powder is put into a container having a predetermined shape and molded into a predetermined shape. In the molding step, a coil may be put together with the composite magnetic powder and molded.

* Containers with various shapes are used according to the shape of the core to be manufactured. When inserting a coil, the container uses a box-type container or a dish-shaped container with an open top so that the coil can be inserted from above. The container used in the molding process can also be used as it is as an outer case of a reactor that houses the core and the coil. If the container is used as an exterior case, there is an advantage that it is not necessary to take out the container after the composite magnetic powder is cured. When the container is not used as an exterior case, a plurality of reactors may be manufactured with one container. That is, a plurality of reactors may be manufactured by forming a plurality of recesses in the bottom of the container and putting a composite magnetic material and a coil in the recesses. By doing in this way, since a single shaping | molding process is enough with respect to several reactors, manufacturing efficiency can be improved.

As the container used for the molding process, all or a part thereof can be constituted by a resin molded product. By making the container made of resin, the manufacturing cost can be reduced, and the advantage that the MC core can have any shape can be utilized. That is, since the resin is a comparatively inexpensive material, the cost of manufacturing the container can be suppressed, and a core having an arbitrary shape can be formed by injection molding or the like. As a material of the resin molded product, for example, unsaturated polyester resin, urethane resin, epoxy resin, BMC (bulk molding compound), PPS (polyphenylene sulfide), PBT (polybutylene terephthalate), or the like can be used.

Further, all or part of the container may be made of a metal having high thermal conductivity such as aluminum or magnesium. This is because the composite magnetic material can be easily warmed in the pressurizing step, as will be described later.

(3) Pressurization step The pressurization step is a step of pressing the composite magnetic material with a pressing member during the molding step. By pressing the clay-like composite magnetic material contained in the container with the pressing member, the composite magnetic material is expanded to the shape of the container, and the voids contained in the composite magnetic material are reduced, and the apparent density and permeability are reduced. Improve magnetic susceptibility.

When the coil is not put in the container, the composite magnetic material becomes a shape inside the container by the process. That is, a molded body having a predetermined shape made of a composite magnetic material can be obtained.

When putting the coil in the container, as shown in FIG. 2, the composite magnetic material is put in the container, and the composite magnetic material is spread in the shape of the container by the pressing member. Thereafter, the coil is inserted into the space formed by pressing the composite magnetic material, and further filled with the composite magnetic material, and the composite magnetic material is pressed together with the coil from above by the pressing member. Alternatively, the composite magnetic material may be put in a container, and then the coil including the inner and outer circumferences may be embedded in the composite magnetic material, and the composite magnetic material may be pressed together with the coil. Thus, by pressing a composite magnetic material with a coil, the space | gap contained in the composite magnetic material can be reduced and an apparent density and a magnetic permeability can be improved. In addition, you may make it press only a composite magnetic material, avoiding the part in which a coil exists. In this way, a molded body of a composite magnetic material having a predetermined shape including a coil can be obtained by this process.

Thus, the pressurizing step may press the composite magnetic material with the pressing member to make the material into the shape of the container. In this case, the pressurizing step can be regarded as the pressurizing step and the molding step. .

The pressure for pressing the composite magnetic material is preferably 6.3 kg / cm ² or more. If it is less than this value, the pressure to press is small and the effect of improving the apparent density is small. Moreover, even if it is more than the said value, it is preferable that it is 15.7 kg / cm < ² > or less. This is because even if pressing exceeds this value, the effect of improving the apparent density is small. In addition, if the pressure exceeds this value, only the resin is pressed and the insulation between the magnetic powders deteriorates.

The time for pressing the composite magnetic material can be appropriately changed depending on the resin content and viscosity. For example, it can be 10 seconds.

The pressurizing step may be performed by setting the pressing member for pressing the container or the composite magnetic material to a temperature higher than normal temperature (for example, 25 ° C.). By raising the temperature of the container or the pressing member, the resin is warmed and softened. For this reason, the composite magnetic material can easily flow into the gap in the container and the moldability can be improved, and the material can easily flow into the voids in the composite magnetic material, and the density can be improved. The temperature of the pressing member that presses the container or 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 pressing member that presses the container or the composite magnetic material.

Further, in the pressurizing step, the temperature of the container or the pressing member may be raised, or the composite magnetic material itself may be warmed to press the composite magnetic material. The temperature of the pressing member that presses the container or the composite magnetic material may be maintained, and the composite magnetic material itself may be warmed and pressed.

(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 of curing by drying the resin in the molded body, the drying atmosphere can be an air atmosphere. The drying time can be appropriately changed according to the type, content, drying temperature, etc. of the resin, and can be, for example, 1 hour to 4 hours, but is not limited thereto. The drying temperature can be appropriately changed according to the type, content, drying time, etc. of the resin, and can be, for example, 85 ° C. to 150 ° C., but is not limited thereto. The drying temperature is the temperature of the drying atmosphere.

Also, the curing of the resin is not limited to drying, and the curing method varies depending on the type of resin. For example, if the resin is a thermosetting resin, the resin is cured by applying heat, and if the resin is an ultraviolet curable resin, the resin is cured by irradiating the molded body with ultraviolet rays.

In the curing step, the step of curing the molded body for a predetermined time at a predetermined temperature may be repeated a plurality of times. Further, for example, when the resin is cured by drying, the drying temperature or the drying time may be changed every time the resin is repeated a plurality of times.

[1-3. 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 a resin, and a coil attached to the core, and is 3 to 5 wt% with respect to the magnetic powder. Obtained in the mixing step of mixing the resin, a molding step in which the mixture and the coil obtained in the mixing step are molded in a predetermined container, a pressing step for pressing the mixture in the molding step, and a molding step And a curing step for curing the molded body.

This makes it possible to obtain a core with improved productivity and density while obtaining the advantage of moldability. That is, since the resin amount is 3 to 5 wt%, the composite magnetic material becomes clayy and easy to handle, and the productivity can be improved. Moreover, by having a pressurizing step, the advantage of the moldability that is the advantage of the MC core that the shape of the composite magnetic material can be formed into a predetermined shape can be secured, and the composite magnetic material is pressed. As a result, the material can easily enter the voids included in the composite magnetic material, and the apparent density of the core can be improved.

(2) In the pressing step, the pressure for pressing the mixture was set to 6.3 kg / cm ² or more. Thereby, the density of a core can be improved.

(3) The pressurizing step was performed by setting the member or container for pressing the mixture to a temperature higher than room temperature. Thereby, the resin in the composite magnetic material which is the mixture is warmed and softened. For this reason, the composite magnetic material can easily flow into every corner of the container and the moldability can be improved, and the material can easily flow into the voids in the composite magnetic material, and the density can be improved.

(4) The pressurizing step was performed by putting the mixture warmed to a temperature higher than normal temperature into the container. Thereby, the same effect as said (3) can be acquired.

(5) The magnetic powder was prepared by mixing two kinds of magnetic powders having different average particle diameters. In particular, the magnetic powder is a mixture of the first magnetic powder and the second magnetic powder having an average particle diameter smaller than that of the first magnetic powder. 80 wt% and the second magnetic powder was 20 to 40 wt%.

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

(6) The first magnetic powder has an average particle size of 20 to 150 μm, and the second magnetic powder has an average particle size of 5 to 20 μm. Thereby, the density and permeability of the core are improved, and the iron loss can be reduced.

(7) The resin was an epoxy resin, a silicone resin, or an acrylic resin. Thereby, a composite magnetic material can be made into a clay shape, it becomes easy to handle, and productivity can be improved.

[2. Embodiment II]
[2-1. Constitution]
Since the reactor of this embodiment is the same as the structure of the reactor of Embodiment I, description is abbreviate | omitted. That is, the core, coil, magnetic powder, and resin are the same as in Embodiment I.

[2-2. Reactor manufacturing method]
The manufacturing method of the reactor which concerns on this embodiment is demonstrated referring drawings. As shown in FIG. 12, the manufacturing method of the present reactor includes (1) a mixing step, (2) a molding step, (3) a pressurizing step, (4) a curing step, and (5) a magnetic field applying step. The steps (1) to (4) are basically the same as those of the reactor manufacturing method of Embodiment I, so the same portions are omitted and only different portions are described.

(3) Pressurization step The pressurization step is a step of pressing the composite magnetic material with a pressing member during the molding step. By pressing the clay-like composite magnetic material contained in the container with the pressing member, the composite magnetic material is expanded to the shape of the container, and the voids contained in the composite magnetic material are reduced. Improve permeability and initial inductance value. The initial inductance value is an inductance value when no current is passed through the reactor coil obtained by the present invention, that is, when the applied magnetic field during the curing process is 0 (kA / m).

(5) Magnetic field application process The magnetic field application process is a process in which a coil included in a molded body made of a composite magnetic material is energized and a magnetic field is applied to the molded body during the curing process. When the coil is embedded in the molded body, the coil is energized. After obtaining the molded body, when a coil is formed by winding a conducting wire around the molded body, the coil is energized.

The magnetic field application step may be performed until the resin in the molded body is solidified, and the magnetic field application step may be performed before the curing step. The magnetic field application step may be performed between the curing steps when the curing step is performed a plurality of times.

In the magnetic field application step, the magnetic powder in the molded body is aligned in the direction of the applied magnetic field, and as a result of having an orientation, a core with high initial permeability can be obtained. That is, since the magnetic field application step uses a coil provided as a reactor as a means for applying a magnetic field to the molded body during the curing step, the direction of the magnetic flux generated by the reactor product itself has orientation, so the reactor The magnetic flux generated by the product itself matches the orientation of the magnetic powder.

The degree of alignment is preferably such that the easy axis of magnetization of the magnetic powder matches the direction of the magnetic flux generated by the coil provided in the reactor (the direction of the lines of magnetic force). You may incline to about 45 degrees. Thus, a core with high initial permeability can be obtained by the magnetic field application step.

The magnetic field applied to the molded body is preferably 2 kA / m or more. This is because the effect of increasing the L0 value, which is more than half of the L0 value saturation increase rate, can be obtained as shown in the examples described later. The L0 value saturation increase rate is the rate of change of the L0 value obtained based on the following equation (5), and L0 (H) in the equation (5) indicates that the applied magnetic field during curing is an improvement in the L0 value. It is the initial inductance value of the reactor obtained by applying a saturated magnetic field.

Further, when the second magnetic powder is excited, there is an effect that the magnetization directions of the crystal grains in the magnetic powder are aligned, and the DC superposition characteristics are improved by exciting the second magnetic powder.

Also, it is considered that a reactor including a core made of a composite magnetic material that is magnetized and oriented has an effect of reducing eddy current loss and reducing heat generated from 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 a resin, and a coil attached to the core, and is 3 to 5 wt% with respect to the magnetic powder. Mixing step of mixing the resin, a molding step of molding the mixture and coil obtained in the mixing step into a predetermined container, a curing step of curing the resin in the molded body obtained in the molding step, and a curing step And a magnetic field application step of applying a magnetic field to the molded body at times by energizing the coil of the molded body.

This makes it possible to obtain a reactor having a core with a high initial permeability. That is, in the conventional MC core, the amount of resin added to the magnetic powder was more than 5 wt%, but by setting it to 3 to 5 wt%, the density and initial permeability can be improved. Furthermore, 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 of the reactor itself during the curing process, it can be oriented in the desired orientation. The initial permeability can be improved.

(2) In the magnetic field application step, the magnetic field is set to 2 kA / m or more. Thereby, most of the initial inductance value improving effect obtained by the magnetic field applying step can be obtained.

(3) A pressing step for pressing the mixture is provided during the molding step. Thereby, the density of a core can be improved.

(4) The pressurizing step was performed by setting the member that presses the container or the mixture to a temperature higher than room temperature. Thereby, the resin in the composite magnetic material which is the mixture is warmed and softened. For this reason, the composite magnetic material can easily flow into every corner of the container and the moldability can be improved, and the material can easily flow into the voids in the composite magnetic material, and the density can be improved.

(5) The pressurizing step was performed by putting the mixture warmed to a temperature higher than normal temperature into the container. Thereby, the same effect as said (4) can be acquired.

(6) The magnetic powder was prepared by mixing two kinds of magnetic powders having different average particle diameters. In particular, the magnetic powder is a mixture of the first magnetic powder and the second magnetic powder having an average particle diameter smaller than that of the first magnetic powder. 80 wt% and the second magnetic powder was 20 to 40 wt%.

(7) The first magnetic powder has an average particle size of 20 to 150 μm, and the second magnetic powder has an average particle size of 5 to 20 μm. Thereby, the density and permeability of the core are improved, and the iron loss can be reduced.

(8) The resin was an epoxy resin, a silicone resin, or an acrylic resin. Thereby, a composite magnetic material can be made into a clay shape, it becomes easy to handle, and productivity can be improved.

[3. Embodiment III]
[3-1. Constitution]
The soft magnetic composite material of this embodiment includes a magnetic powder and a resin. As the resin contained in the soft magnetic composite material, a resin having a reduction rate (hereinafter referred to as heating loss) of 0.1% or less when exposed to an atmosphere at 220 ° C. for 40 hours is used. Resin changes in volume and weight when exposed to a high temperature atmosphere for a long time. The loss on heating is a value indicating the rate of change in the weight or volume of the resin before and after being exposed to a high temperature, and the loss on heating is calculated based on the weight or volume of the resin before and after being exposed to a high temperature. In the following, the loss on heating is calculated based on a change in the weight of the resin, but may be calculated based on a change in volume. Even when the loss on heating is calculated on the basis of the change in weight and the change in volume, in this embodiment, a resin having a loss on heating of 0.1% or less when exposed to an atmosphere at 220 ° C. for 40 hours is used.

In this embodiment, a clay-like soft magnetic composite material is obtained by mixing magnetic powder and resin. Moreover, in this embodiment, a magnetic core is made into a predetermined shape by filling a predetermined container with clay-like soft magnetic composite material and pressurizing it. The shape of the magnetic core can be various shapes such as a toroidal core, an I-type core, a U-type core, a θ-type core, an E-type core, and an EER-type core.

(Magnetic powder)
A plurality of magnetic powders having different average particle diameters may be used as the magnetic powder. For example, you may comprise from two types of magnetic powder from which an average particle diameter differs. Below, the mixed powder which mixed the kind soft magnetic powder is demonstrated to an example. However, two kinds of powders are not necessarily mixed. For example, one kind of soft magnetic powder may be used, or three or more kinds of soft magnetic powders may be mixed.

When mixing two types of magnetic powder, the magnetic powder is composed of 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 and the second magnetic powder is preferably set to the first magnetic powder: second magnetic powder = 80: 20 to 60:40. By setting it as this range, a density improves, a magnetic permeability improves, and an iron loss can be made small.

The average particle diameter of the first magnetic powder is preferably 100 μm to 200 μm, and the second magnetic powder is preferably 5 μm 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. Thereby, improvement of density and magnetic permeability and reduction of iron loss can be achieved.

As the first magnetic powder and the second 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), these A mixed powder of two or more kinds of powders, an 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 μm to 150 μm. In the present specification, the “average particle diameter” refers to D50, that is, the median 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 powders is reduced and more second magnetic powder can easily enter through the gap, and the density and permeability can be improved.

Note that the types of the first magnetic powder and the second magnetic powder may be the same or different. When three or more kinds of soft magnetic powders are mixed, three or more kinds of different magnetic powders may be mixed.

As the first magnetic powder and the second magnetic powder, those produced by a gas atomizing method, a water atomizing method, or a water gas atomizing method can be used. 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, the average circularity of the particles is further increased. You may give the process which raises a degree. For example, the soft magnetic powder by the gas atomization method is a substantially spherical particle. Therefore, the powder formed by the gas atomization method can be used as it is without being processed. On the other hand, the soft magnetic powder produced by the water atomization method is non-spherical particles having irregularities formed on the surface thereof. In this case, the average circularity of the particles can be increased by leveling the surface irregularities using a ball mill, mechanical alloying, jet mill, attritor, or surface modification 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 homogeneously mixed state. The resin is mixed with the magnetic powder and holds the mixed magnetic powder. When the magnetic powder is composed of different types of powders having different average particle sizes, each powder is held in a homogeneously mixed state. As the resin, a resin having a weight loss of 0.1% or less, preferably 0.08% or less when heated at 220 ° C. for 40 hours is used. A curable resin can be used as the resin. If the loss on heating is 0.1% or less, the resin can be a thermosetting resin, an ultraviolet curable resin, or a thermoplastic resin. As the thermosetting resin, phenol resin, epoxy resin, unsaturated polyester resin, polyurethane, diallyl phthalate resin, silicone resin and the like can be used. As the ultraviolet curable resin, urethane acrylate, epoxy acrylate, acrylate, and epoxy resins can be used. As the thermoplastic resin, it is preferable to use a resin having excellent heat resistance such as polyimide or fluororesin. An epoxy resin that is cured by adding a curing agent is suitable for the present invention because its viscosity can be adjusted by the amount of the curing agent added. Thermoplastic acrylic resins and silicone resins can also be used.

The resin is preferably contained in an amount of 3 to 5 wt% with respect to the magnetic powder. When the resin content is less than 3 wt%, the bonding strength of the magnetic powder is insufficient and the mechanical strength of the core is lowered. Also, if the resin content is more than 5 wt%, the resin formed between the first magnetic powder enters, the second magnetic powder cannot fill the gap, and the core density decreases, The initial permeability μ0 decreases.

The viscosity of the resin is preferably 50 to 5000 mPa · s when mixed with the magnetic powder. When the viscosity is less than 50 mPa · s, the resin does not get entangled with the magnetic powder during mixing, the magnetic powder and the resin are easily separated in the container, and the density or strength of the core varies. When the viscosity exceeds 5000 mPa · s, the viscosity becomes too high. For example, the resin formed between the first magnetic powders enters, and the gap cannot be filled with the second magnetic powder. Decreases, and the initial permeability μ0 decreases.

For the resin, SiO2, Al2O3, Fe2O3, BN, AlN, ZnO, TiO2, or the like can be used as a viscosity adjusting material. The average particle diameter of the filler as the viscosity adjusting material is not more than the average particle diameter of the second magnetic powder, preferably not more than 1/3 of the average particle diameter of the second magnetic powder. This is because when the average particle size of the filler is large, the density of the obtained core decreases. Moreover, high thermal conductivity materials, such as Al2O3, BN, and AlN, can be added to the resin.

(coil)
The coil is a conducting wire with an insulating coating, and a copper wire or an aluminum wire can be used as the wire. The coil is formed or attached by winding a conductive wire around at least a part of the core, and is arranged around at least a part of the core. There are no particular limitations on the method of winding the coil and the material and shape of the wire.

[3-2. Manufacturing method of metal composite core]
The manufacturing method of the metal composite core which concerns on this embodiment is demonstrated referring drawings. As shown in FIG. 22, the manufacturing method of the present metal composite core includes (1) a mixing step, (2) a molding step, (3) a pressing step, and (4) a curing step.

(1) Mixing step The mixing step is a step of mixing magnetic powder and resin. In the mixing step, the first magnetic powder and the second magnetic powder having an average particle diameter smaller than that of the first magnetic powder are mixed, and the magnetic powder mixing step for forming the magnetic powder is performed. A resin mixing step of adding 5 wt% resin and mixing the magnetic powder and the resin.

* Containers with various shapes are used according to the shape of the core to be manufactured. When inserting a coil, the container uses a box-type container or a dish-shaped container with an open top so that the coil can be inserted from above. The container used in the molding process can also be used as an outer case of a metal composite core that accommodates the core and the coil as it is. If the container is used as an exterior case, there is an advantage that it is not necessary to take out the container after the composite magnetic powder is cured. When the container is not used as an exterior case, a plurality of metal composite cores may be manufactured with one container. That is, a plurality of recesses may be formed at the bottom of the container, and a plurality of metal composite cores may be manufactured by placing a composite magnetic material and a coil in the recesses. By doing in this way, since a single shaping | molding process may be sufficient with respect to a some metal composite core, manufacturing efficiency can be improved.

As the container used for the molding process, all or a part thereof can be constituted by a resin molded product. By making the container made of resin, the manufacturing cost can be reduced, and the advantage that the MC core can have any shape can be utilized. That is, since resin is a relatively inexpensive material, the cost of manufacturing a container can be suppressed, and a core having an arbitrary shape can be formed by injection molding or the like.

(3) Pressurizing step The pressing step is a step of pressing the composite magnetic material with a pressing member during the molding step. By pressing the clay-like composite magnetic material contained in the container with the pressing member, the composite magnetic material is expanded to the shape of the container, and the voids contained in the composite magnetic material are reduced, the apparent density, and Improve initial permeability.

When putting the coil in the container, as shown in FIG. 2, the composite magnetic material is put in the container, and the composite magnetic material is spread in the shape of the container by the pressing member. Thereafter, the coil is inserted into the space formed by pressing the composite magnetic material, and further filled with the composite magnetic material, and the composite magnetic material is pressed together with the coil from above by the pressing member. Alternatively, the composite magnetic material may be placed in a container, and then the coil may be embedded in the composite magnetic material, and the composite magnetic material may be pressed together with the coil from above. Thus, by pressing a composite magnetic material with a coil, the space | gap contained in the composite magnetic material can be reduced and an apparent density and a magnetic permeability can be improved. In addition, you may make it press only a composite magnetic material, avoiding the part in which a coil exists. In this way, a molded body of a composite magnetic material having a predetermined shape including a coil can be obtained by this process.

The pressure for pressing the composite magnetic material is preferably 2.0 kg / cm 2 or more. If it is less than this value, the pressure to press is small and the effect of improving the apparent density is small. Moreover, even if it is more than the said value, it is preferable that it is 10.0 kg / cm <2> or less. This is because even if pressing exceeds this value, the effect of improving the apparent density is small.

The pressurizing step may be performed by setting the pressing member that presses the container or the composite magnetic material to a temperature higher than room temperature (for example, 25 ° C.). By raising the temperature of the container or the pressing member, the resin is warmed and softened. Therefore, the composite magnetic material can easily flow into the gap in the container, and the moldability can be improved, and the material can easily flow into the voids in the composite magnetic material, and the apparent density can be improved. The temperature of the pressing member that presses the container or 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 pressing member that presses the container or 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 of curing by drying the resin in the molded body, the drying atmosphere can be an air atmosphere. In the curing step, the resin is cured by a drying profile that controls the drying temperature and time based on the dry state of the resin. The drying time can be appropriately changed according to the type, content, drying temperature, etc. of the resin, but can be, for example, 1 hour to 4 hours, but is not limited thereto. The drying temperature can be appropriately changed according to the type, content, drying time, etc. of the resin, but can be, for example, 85 ° C. to 150 ° C., but is not limited thereto. The drying temperature is the temperature of the drying atmosphere.

Also, the curing of the resin is not limited to drying, and the curing method varies depending on the type of resin. For example, if the resin is a thermosetting resin, the resin is crossed by applying heat, and if the resin is an ultraviolet curable resin, the resin is cured by irradiating the molded body with ultraviolet rays.

[3-3. Action / Effect]
(1) The resin used for the magnetic core of the present embodiment is a resin having a reduction rate of 0.1% or less, preferably 0.08% or less when the resin is exposed to an atmosphere at 220 ° C. for 40 hours. . The rate of decrease is the rate of decrease in weight when the resin is exposed to a high temperature atmosphere. In the magnetic core produced from the soft magnetic composite material of the present embodiment, contact between the magnetic powders inside the magnetic core can be suppressed even when used at a high temperature for a long time. In the magnetic core, an eddy current corresponding to the size of the soft magnetic powder contained therein is generated. When the magnetic core is exposed to a high temperature for a long time, the resin decomposes and disappears due to the influence of heat when the reduction rate of the resin contained in the magnetic core exceeds 0.1%. A larger eddy current is generated when the magnetic powders separated by the resin come into contact with each other due to the disappearance of the resin.

(2) As the magnetic powder of the present embodiment, a plurality of magnetic powders having different average particle diameters were used. For example, the average particle diameter of the first magnetic powder is 100 to 200 μm, and the average particle diameter of the second magnetic powder is 5 to 10 μm. Further, the ratio of the magnetic powder is 60-80 wt% for the first magnetic powder and 20-40 wt% for the second magnetic powder. 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) As the resin, a thermosetting resin, an ultraviolet curable resin, or a thermoplastic resin can be used, but the inside of the thermosetting resin can be used. Among these, it is preferable to use an epoxy resin. Epoxy resins not only have a high glass transition point and excellent heat resistance, but also do not produce volatile substances as a by-product during curing, so that there are few dimensional changes in the molded product. Further, since it has high fluidity and can be molded even at 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 keep the rate of change in iron loss small even when exposed to an atmosphere at 155 ° C. for a long time. More desirably, a soft magnetic composite material capable of producing a magnetic core having a change rate of iron loss of 10% or less when exposed to an atmosphere at 155 ° C. for 500 hours or more is used. Even if such a magnetic powder core is exposed to an atmosphere at 155 ° C. for 1000 hours or more, the resin does not decompose or disappear due to the influence of heat. In other words, the rate of change in iron loss after 1000 hours can be predicted by the rate of change in iron loss after 500 hours. Is also possible.

[4. Example]
[4-1. Example I]
Embodiment I of the present invention will be described below with reference to Tables 1 to 4 and FIGS. 3 to 11.
(1) Measurement items Measurement items are density, magnetic permeability, and iron loss. Reactors were prepared by winding 40 turns of copper cores with a diameter of 2.6 mm on the prepared core samples. The shape of each core sample was a toroidal shape having an outer diameter of 35 mm, an inner diameter of 20 mm, and a height of 11 mm. Moreover, the magnetic permeability and iron loss of the produced reactor were computed on condition of the following.

<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 the volume (cm ³ ) of the sample was calculated from these values based on π × (outer diameter ² −inner diameter ² ) × height. Then, the mass of the sample was measured, and the density of the core was calculated by dividing the measured mass by the calculated volume.

<Permeability and iron loss>
The measurement conditions for magnetic permeability and iron loss were a frequency of 20 kHz and a maximum magnetic flux density Bm = 30 mT. The magnetic permeability was the amplitude magnetic permeability when the maximum magnetic flux density Bm was set when measuring the iron loss Pcv. The iron loss was calculated using a BH analyzer (Iwatori Measurement Co., Ltd .: SY-8232), which is a magnetic measuring instrument. This calculation was performed by calculating the hysteresis loss coefficient and the eddy current loss coefficient of the iron loss frequency curve using the following formulas (1) to (3) by the least square method.

Pcv = Kh × f + Ke × f ² (1)
Phv = Kh × f (2)
Pev = Ke × f ² (3)
Pcv: Iron loss Kh: Hysteresis loss coefficient Ke: Eddy current loss coefficient f: Frequency Phv: Hysteresis loss Pev: Eddy current loss

In this example, the average particle diameter and the circularity of each powder are the average values of 3000 using the following apparatus, and the powder is dispersed on a glass substrate, and a powder photograph is taken with a microscope. It was measured automatically from the image every time.
Company name: Malvern
Device name: morphologic G3S
The specific surface area was measured by the BET method.

(2) Sample Preparation Method The core sample was prepared from the viewpoint of (a) press surface pressure in the pressing step, (b) resin amount, and (c) temperature difference of the container. These production methods and the results are shown below in order.

(a) Press surface pressure in the pressurizing step First, as a mixing step, Fe-6.5% Si alloy powder (circularity 0.943) having an average particle size of 123 μm and Fe-6. 5% Si alloy powder (circularity: 0.908) was mixed at a weight ratio of 70:30 with a V-type mixer for 30 minutes to form a magnetic powder. And the said magnetic powder was put into the aluminum cup, 3.5 wt% epoxy resin was added with respect to the said magnetic powder, and it mixed manually using the spatula for 2 minutes. This obtained the composite magnetic material which is a mixture of magnetic powder and resin.

Next, the composite magnetic material obtained in the mixing step is filled into a resin container having a toroidal-shaped space, and the composite magnetic material in the container is pressed with the press pressure of Table 1 for 10 seconds using a hydraulic press. A toroidal shaped molded body was produced. During this pressing, the temperature of the container was kept at 25 ° C.

The molded body thus obtained in the pressurizing step and the molding step is dried in the atmosphere at 85 ° C. for 2 hours, then dried at 120 ° C. for 1 hour, and further dried at 150 ° C. for 4 hours. A toroidal core was produced.

Table 1 and FIGS. 3 to 7 show the results of core density, magnetic permeability, and iron loss in Examples 1 to 3 and Comparative Examples 1 and 2 obtained at each pressing pressure. In Examples 1 to 3, the press pressure was 400 N, 600 N, and 1000 N, Comparative Example 1 was not pressed, and Comparative Example 2 was 100 N. The press surfaces are the same.

“Theoretical density” in Table 1 is a ratio calculated from the apparent density of the core / the true density of the magnetic powder. Here, both the first magnetic powder and the second magnetic powder use Fe-6.5% Si alloy powder, and the theoretical density is calculated by setting the true density to 7.63 g / cm ³ . .

FIG. 3 is a graph of theoretical density versus surface pressure in Examples 1 to 3 and Comparative Examples 1 and 2. As shown in Table 1 and FIG. 3, the theoretical density with respect to the surface pressure in Examples 1 to 3 and Comparative Examples 1 and 2 is Comparative Example 2 in which the pressurizing step was performed, compared to Comparative Example 1 in which the pressurizing step was not performed. It can also be seen that Examples 1 to 3 are higher and tend to increase as the surface pressure increases. In Comparative Example 2 where the surface pressure is 1.6 kg / cm ² , the theoretical density is not so different from Comparative Example 1 without pressure, but in Examples 1 to 3 where the surface pressure is 6.3 kg / cm ² or more, The theoretical density is 77.5% or higher, which is higher than Comparative Examples 1 and 2. That is, when the surface pressure is 6.3 kg / cm ² or more, it can be seen that the density is improved by spreading the material to the voids included in the composite magnetic material and every corner of the container. It can also be seen that the theoretical density is almost constant when the surface pressure is 6.3 kg / cm ² or more.

FIG. 4 is an SEM photograph (100 times) of the core cross section of Example 2. FIG. 5 is an SEM photograph (100 times) of the core cross section of Comparative Example 1. 4 and 5, reference numeral 1 indicates the first magnetic powder, and reference numeral 2 indicates the second magnetic powder. The code | symbol 3 shows resin and the code | symbol 4 has shown the space | gap. The void 4 is a portion represented by dark black in the SEM photograph, whereas the portion represented by relatively thin black is the resin 3. As apparent from FIGS. 4 and 5, the number of voids 4 in the composite magnetic material is smaller in Example 2 shown in FIG. 4 than in Comparative Example 1 shown in FIG. 5, and the size of the void 4 itself is also increased. You can see that it can be made smaller.

The magnetic permeability is an amplitude magnetic permeability, and was calculated from the inductance of the strength of each magnetic field at 20 kHz and 1.0 V by using the impedance analyzer described above. “Μ0” in Table 1 indicates the initial permeability when DC is not superimposed, that is, when the magnetic field strength is 0 H (A / m). “Μ12000” in Table 1 indicates the magnetic permeability when the magnetic field strength is 12 kH (kA / m).

FIG. 6 is a graph of magnetic permeability with respect to the surface pressure in Examples 1 to 3 and Comparative Examples 1 and 2. As shown in Table 1 and FIG. 6, it can be seen that the magnetic permeability is higher in Examples 1 to 3 in which pressure is applied than in Comparative Example 1 in which pressure is not applied. For example, it can be seen that the initial permeability μ0 of Example 1 is increased by about 8.7% as compared with Comparative Example 1. It can be seen that even in Comparative Example 2 where pressure is applied, the magnetic permeability is higher than in Comparative Example 1 where pressure is not applied, but the contribution to the increase in the density of the core is small.

FIG. 7 is a graph of iron loss versus surface pressure in Examples 1 to 3 and Comparative Examples 1 and 2. As shown in Table 1 and FIG. 7, it can be seen that the iron loss is lower in the pressurized examples 1 to 3 than in the comparative example 1 where no pressure is applied. In particular, it can be seen that the hysteresis loss (Phv) tends to decrease by increasing the surface pressure. In Comparative Example 2 in which pressurization is performed, the iron loss is reduced as compared with Comparative Example 1 in which pressurization is not performed, but it can be seen that Examples 1 to 3 further reduce the iron loss.

It can be seen that when the surface pressure is 6.3 kg / cm ² or more, both the magnetic permeability and the iron loss are almost constant, and the effect on the magnetic properties due to the pressurization tends to be saturated. In other words, when the surface pressure is in the range of 6.3 to 15.7 kg / cm ² , it can be seen that the effect of improving the density and magnetic permeability and reducing the iron loss can be obtained by having the pressing step.

(b) Resin Amount Core samples (Examples 4 to 8 and Comparative Examples 3 to 5) were prepared in the same procedure as in Example 2, with the resin amount in Example 2 shown in Table 2. Table 2 and FIGS. 8 and 9 show the results of density, magnetic permeability, and iron loss in Examples 4 to 8 and Comparative Examples 3 to 5. In Table 2, μ0 and μ12000 have the same meaning as in Table 1.

FIG. 8 is a graph of magnetic permeability with respect to the resin amounts of Examples 4 to 8 and Comparative Examples 3 to 5. FIG. 9 is a graph of the iron loss against the resin amount of Examples 4 to 8 and Comparative Examples 3 to 5. As shown in Table 2 and FIGS. 8 and 9, when the resin amount is less than 3 wt% with respect to the composite magnetic material, the voids included in the core increase and the density decreases. As a result, it causes a decrease in magnetic permeability and an increase in hysteresis loss. On the other hand, if the amount of resin is less than 3 wt%, the magnetic powders are easily brought into point contact with each other, which causes an increase in eddy current loss. On the other hand, when the amount of resin is more than 5 wt% with respect to the composite magnetic material, the density is significantly reduced. As a result, hysteresis loss increases.

(c) Container temperature Core samples were prepared by varying the container temperature. As described in (a) above, in Examples 1 to 3 and Comparative Example 1, the temperature of the container was 25 ° C. Samples obtained in the same manner as in the above step (a) except for the temperature of the container at 70 ° C. were used as Examples 9 to 11 and Comparative Example 6. Table 3, FIG. 10, and FIG. 11 show the results of density, magnetic permeability, and iron loss in Examples 1 to 3, 9 to 11, and Comparative Examples 1, 2, and 6. The theoretical density, μ0, and μ12000 in Table 3 have the same meaning as in Table 1.

FIG. 10 is a graph of magnetic permeability with respect to surface pressure in Examples 9 to 11 and Comparative Example 6. FIG. 11 is a graph of iron loss versus surface pressure in Examples 9 to 11 and Comparative Example 6. As shown in Table 3 and FIGS. 6, 7, 10, and 11, Examples 9 to 11 in which the container temperature was 70 ° C. and Comparative Examples 6 were examples 1 to 3 in which the container temperature was 25 ° C. It can be seen that the density and the theoretical density tend to increase as compared with Comparative Example 2, and the iron loss tends to decrease. The results showed that the permeability increased or decreased depending on the surface pressure.

In addition, even when the temperature of the container was set to 70 ° C. and the temperature was increased, Examples 9 to 11 had a theoretical density of 77.9% or higher, and were higher than Comparative Example 6 by increasing the surface pressure. I understand. Thus, by heating the container from room temperature (25 ° C.), the resin in the composite magnetic material becomes soft, and the material easily flows into the voids in the material, thereby improving the apparent density and the theoretical density. Is thought to improve. As a result, it was found that the effect of reducing iron loss can be obtained.

(d) Measurement of resin viscosity 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 sinking of the weight placed on the composite magnetic material as follows.

That is, first, a composite magnetic material was prepared in the same manner as in the mixing step (a) under the conditions shown in Table 4 where the amount of resin added was the same. Next, the obtained composite magnetic material was put into an aluminum container having a diameter of 5 mm so as to have a thickness of 3 mm, and a JIS standard 10 g weight was placed on the center of the composite magnetic material. Then, 10 seconds after the weight was placed, the weight was removed, and the depth of the recess of the composite magnetic material formed with the weight of the weight was measured. The results are shown in Table 4.

As shown in Table 4, it can be seen that the greater the amount of resin added, the deeper the recess, the lower the viscosity of the composite magnetic material, and the easier the sinking of the weight.

[4-2. Example II]
Embodiment II of the present invention will be described below with reference to Tables 5 to 11 and FIGS. 13 to 21.
(1) Measurement items Measurement items are density, magnetic permeability, iron loss, and inductance value (L value). Reactors were prepared by winding 40 turns of copper cores with a diameter of 2.6 mm on the prepared core samples. The shape of each core sample was a toroidal shape having an outer diameter of 35 mm, an inner diameter of 20 mm, and a height of 11 mm. Moreover, the magnetic permeability of the produced reactor, the iron loss, and the inductance value were computed on condition of the following.

<Inductance value>
The inductance value was measured by applying a primary winding (20 turns) to the manufactured core sample and using an impedance analyzer (Agilent Technology: 4294A) under the conditions of 20 kHz and 1.0 V.

In this example, the average particle diameter and the circularity of each powder are the average values of 3000 pieces using the following apparatus. The powder is dispersed on a glass substrate, and a powder photograph is taken with a microscope. Each shot was automatically measured from the image.
Company name: Malvern
Device name: morphologic G3S
The specific surface area was measured by the BET method.

(2) Sample preparation method The core sample was prepared from the viewpoint of (a) presence / absence of applied magnetic field, (b) magnitude of applied magnetic field, and (c) presence / absence of pressurization step, as described below. These production methods and the results are shown below in order.

(a) Presence / absence of applied magnetic field First, as a mixing step, Fe-6.5% Si alloy powder (circularity 0.943) having an average particle size of 123 μm and Fe-6.5% Si having an average particle size of 5.1 μm were used. Alloy powder (circularity: 0.908) was mixed at a weight ratio of 70:30 for 30 minutes with a V-type mixer to form a magnetic powder. And the said magnetic powder was put into the aluminum cup, the epoxy resin was added on the conditions shown in Table 5 with respect to the said magnetic powder, and it mixed manually using the spatula for 2 minutes. This obtained the composite magnetic material which is a mixture of magnetic powder and resin.

Next, the composite magnetic material obtained in the mixing step is filled into a resin container having a toroidal space, and the composite magnetic material in the container is pressed with a 600 N press pressure (surface pressure 9.4 kg) using a hydraulic press. / Cm ² ) for 10 seconds to produce a toroidal shaped molded body. During this pressing, the temperature of the container was kept at 25 ° C.

Thereafter, the obtained molded body was wound with the above copper wire for 40 turns to form a coil, and a reactor as a base was produced.

Then, the reactor was dried in the atmosphere at 85 ° C. for 2 hours, then dried at 120 ° C. for 1 hour, further dried at 150 ° C. for 4 hours to cure the resin, and a sample toroidal core was produced. At that time, the coil was energized so as to be 4.85 kA / m during the drying time at each temperature, and samples of Examples 12 to 16 were obtained. The difference between Examples 12 to 16 is the amount of resin added, which is 3.0 to 5.0 wt%, respectively. In addition, toroidal coils manufactured without applying a magnetic field during resin curing were prepared, and samples of Comparative Examples 7 to 11 were obtained.

FIG. 13 is a graph of initial permeability with respect to the amount of resin with and without application of a magnetic field. As shown in Table 5 and FIG. 13, it can be seen that the initial permeability is improved when a magnetic field is applied during the curing step in each resin amount.

FIG. 14 is a graph of the rate of change of magnetic permeability with respect to the amount of resin. The “change rate” shown in Table 5 and FIG. 14 is the change rate of the initial permeability μ0 when the magnetic field is applied and when the magnetic field is not applied in each resin amount, and is a value obtained by calculation using Expression (4). It is. The rate of change indicates the degree of effect of applying a magnetic field.
Rate of change = μ0 (H) / μ0 (0) −1 (4)
μ0 (H): Initial permeability when a magnetic field is applied μ0 (0): Initial permeability when a magnetic field is not applied

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

(b) The magnitude of the applied magnetic field The resin amount is 3 wt%, 4 wt%, and 5 wt% respectively, the applied magnetic field is as shown in Table 6, and the sample of the reactor is the same as the above (a) except for the resin amount and the applied magnetic field. Was made. Then, as shown in the above “(1) Measurement item”, the inductance value was measured for each sample. Further, the L0 value change rate was calculated from the measured inductance value L0 based on the equation (5). The results are shown in Table 6.

L0 value change rate = L0 (H) / L0 (0) −1 (5)
L0 (H): Initial inductance value of the reactor manufactured with each applied magnetic field H during the curing process L0 (0): Initial inductance value of the reactor manufactured with zero applied magnetic field during the curing process

FIG. 15 is a graph of the L0 value change rate with respect to the applied magnetic field during the curing process, and Table 6 is graphed. As shown in Table 6 and FIG. 15, it can be seen that the L0 value change rate tends to increase as the amount of resin increases. The L0 value change rate is likely to increase in a region where the magnetic field is small, and is difficult to increase in a region where the magnetic field is large. That is, the L0 value improvement starts to saturate when the applied magnetic field is around 10 kA / m.

Table 7 is a table | surface which shows the half value magnetic field of L value saturation increase rate and L value saturation increase rate about each resin amount. The L value saturation increase rate is the L0 value change rate of the sample produced with the applied magnetic field during the curing process being 14.56 kA / m, and the half value magnetic field of the L value saturation increase rate is the L value saturation increase rate. This is the value of the applied magnetic field during the curing process, at which half the L0 value change rate is obtained.

As shown in Table 7 and FIG. 15, when the resin amount is 3 wt%, a sufficient L0 value improvement effect can be obtained when the applied magnetic field is 3.0 kA / m or more. It was found that when the resin amount was 4 to 5 wt%, a sufficient L0 value improvement effect was obtained when the applied magnetic field was 2 kA / m or more. From these facts, by setting the applied magnetic field to 2 kA / m or more, it is possible to obtain an L0 value change rate of half or more when the effect of applying the magnetic field during curing is saturated.

(c) Presence / absence of pressurization process Samples were prepared as shown below for the amount of resin 3 to 5 wt% with and without pressing the composite magnetic material, and the difference in the obtained initial inductance value (L0) was investigated. It was.

(c-1) When the amount of resin is 3wt% <With pressurization process>
The amount of resin was 3 wt% with respect to the magnetic powder, and a reactor sample was prepared in the same process as in (a) above. However, the applied magnetic field during the curing process was as shown in Table 8.
<No pressurization process>
The amount of resin was 3 wt% with respect to the magnetic powder, and a reactor sample was prepared in the same process as in (a) above. However, the composite magnetic material is not pressed. That is, the composite magnetic material obtained in the mixing step was filled in a resin container having a toroidal-shaped space, and a toroidal-shaped molded body was produced without pressing. During this time, the temperature of the container was kept at 25 ° C.

Next, an initial inductance value (L0) was calculated for each of the prepared samples with and without the pressurization process. The rate of change was calculated from the calculated inductance value (L0) based on equation (5). The results are shown in Table 8 and FIGS.

FIG. 16 is a graph of the initial inductance value of the reactor manufactured with each applied magnetic field during the curing process. As shown in FIG. 16, it was found that L0 is higher when there is a pressurizing step. This is the result of pressing the composite magnetic material to crush the voids in the material, reducing the number of voids, or reducing the size of the voids, thereby improving the apparent density of the core. It is considered that the initial permeability is a factor.

FIG. 17 is a graph showing the rate of change of the initial inductance value of the reactor manufactured with each applied magnetic field during the curing process. As shown in FIG. 17, there is no difference in the presence or absence of the pressurizing step when the applied magnetic field during the curing step is as low as about 5 kA / m. It was found that the rate of change of L0 was high. In particular, it can be seen that when the pressure is 9.27 kA / m or more, the effect of the pressurizing step appears significantly.

(c-2) When the amount of resin is 4 wt% The above-mentioned (c-1) resin amount is 3 wt% except that the amount of resin is 4 wt% in the step of preparing the sample with and without the pressurizing step. Is the same as Further, the initial inductance value (L0) was calculated in the same manner as (c-1) above. The rate of change was calculated from the calculated inductance value (L0) based on equation (5). The results are shown in Table 9 and FIGS.

FIG. 18 is a graph of the initial inductance value of the reactor manufactured with each applied magnetic field during the curing process. As shown in FIG. 18, it was found that L0 is higher when there is a pressurizing step. This is the result of pressing the composite magnetic material to crush the voids in the material, reducing the number of voids, or reducing the size of the voids, thereby improving the apparent density of the core. It is considered that the initial permeability is a factor.

FIG. 19 is a graph showing the rate of change of the initial inductance value of the reactor manufactured with each applied magnetic field during the curing process. As shown in FIG. 19, also in the change rate of L0, it turned out that a change rate becomes high with a pressurization process.

(c-3) When the resin amount is 5 wt% The above-mentioned (c-1) resin amount is 3 wt% except that the resin amount is 5 wt% in the process of preparing the sample with and without the pressurizing step. Is the same as Further, the initial inductance value (L0) was calculated in the same manner as (c-1) above. The rate of change was calculated from the calculated inductance value (L0) based on equation (5). The results are shown in Table 10 and FIGS.

FIG. 20 is a graph of the initial inductance value of the reactor manufactured with each applied magnetic field during the curing process. FIG. 21 is a graph showing the rate of change of the initial inductance value of the reactor manufactured with each applied magnetic field during the curing process. As shown in FIGS. 20 and 21, it can be seen that both the initial inductance value and the rate of change thereof are higher when the pressurization process is performed than when the pressurization process is not performed. However, the difference is small. This is considered to be because the proportion of the resin in the composite magnetic material increases as the amount of the resin increases, and offsets the effect of improving the initial magnetic permeability due to the increase in the apparent density by pressurization.

As shown in FIG. 21, it can be seen that the rate of change of L0 is higher when the applied magnetic field is higher during the curing process than when the pressurized process is not performed. This is considered to be caused by the fact that the orientation of the magnetic powder is easily aligned by the applied magnetic field due to the presence of a large amount of resin.

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 as shown in Table 11. Next, the obtained composite magnetic material was put into an aluminum container having a diameter of 5 mm so as to have a thickness of 3 mm, and a JIS standard 10 g weight was placed on the center of the composite magnetic material. Then, 10 seconds after the weight was placed, the weight was removed, and the depth of the recess of the composite magnetic material formed with the weight of the weight was measured. The results are shown in Table 11.

As shown in Table 11, it can be seen that the greater the amount of resin added, the deeper the recess, the lower the viscosity of the composite magnetic material, and the easier the sinking of the weight.

[4-3. Example III]
Example III of the present invention will be described below with reference to Tables 12 to 14 and FIG.

<Resin (about loss on heating)>
Four types of resins A to D having different heating losses were prepared, test pieces serving as samples were prepared using the resins A to D, and the heating loss of each resin was measured. The loss on heating of the resin was measured by the following method. Since the loss on heating of the resin varies depending on the size of the sample, the size of the resin sample to be compared needs to be unified. In this example, the weight loss of the resins A to D was measured using a cylindrical sample of “diameter 40 × height 10 (mm)”.

(1) Measuring method of heat loss (a) Preparation of test piece First, a mold and a container having an inner diameter of a predetermined dimension were prepared. In this embodiment, the predetermined dimension is a mold having an inner diameter of “diameter 40 × height 10 (mm)”. A molding material, which is a material for resins A to D, was put into the mold, and the mold was heated to 150 ° C. The molding material is melted by the applied heat, and then a chemical reaction occurs to solidify in accordance with the shape of the mold. The heating time of the resins A to D during sample preparation is 4 hours.

(B) Mass measurement before heating Solidified resins A to D were taken out of the mold and used as test pieces A to D. The mass of these test pieces A to D was measured to 1 mg. This value was designated as M0.

(C) High temperature storage test The test pieces A to D are heated to 220 ° C. The heating time is 20 hours or 40 hours.

(D) Mass measurement after heating Test pieces A to D after a predetermined time were taken out, and after heat radiation, the mass was measured to 1 mg. This value was designated as M1.

(E) Calculation of heat loss Heat loss was calculated by the following equation.
(M0-M1) ÷ M0 × 100 = Heating loss (%)

Table 12 is a graph showing the loss on heating when the high temperature storage test is performed on the resins A to D in an atmosphere of 220 ° C. for 20 hours or 40 hours. As shown in Table 12, resin A has a heating loss of 0.09% when exposed to 20 hours, 0.12% of heat loss when exposed to 40 hours, and resin B has a heating loss when exposed to 20 hours. The weight loss is 0.07%, the heat loss when exposed for 40 hours is 0.08%, and the resin C has a heat loss of 0.05% when exposed for 20 hours, and the heat loss when exposed for 40 hours is 0.00. 05%, Resin D has a loss on heating of 0.08% when exposed to 20 hours, and a loss of heat of 0.10% when exposed to 40 hours.

[First characteristic comparison (comparison of effects on iron loss due to differences in heat loss)
In the first characteristic comparison, the characteristics of reactors made using resins A to D with different heating losses are compared.

(2) Measurement item The measurement item is iron loss. Reactors were prepared by applying 40 turns of the primary winding and 3 turns of the secondary winding to each of the core samples thus prepared with a copper wire of φ1.2 mm. The shape of each core sample was a toroidal shape having an outer diameter of 35 mm, an inner diameter of 20 mm, and a height of 11 mm. Moreover, the iron loss of the produced reactor was computed on condition of the following.

<Iron loss>
The iron loss measurement conditions were a frequency of 20 kHz and a maximum magnetic flux density Bm = 30 mT. The iron loss was calculated using a BH analyzer (Iwatori Measurement Co., Ltd .: SY-8232), which is a magnetic measuring instrument. This calculation was performed by calculating the hysteresis loss coefficient and the eddy current loss coefficient of the iron loss frequency curve using the following formulas (1) to (3) by the least square method.

Pcv = Kh × f + Ke × f2 (1)
Phv = Kh × f (2)
Pev = Ke × f2 (3)
Pcv: Iron loss Kh: Hysteresis loss coefficient Ke: Eddy current loss coefficient f: Frequency Phv: Hysteresis loss Pev: Eddy current loss

(3) Sample preparation method The core sample uses Fe6.5Si having an average particle size of 123 μm as the first magnetic powder. Next, Fe6.5Si having an average particle diameter of 5.1 μm is prepared as the second magnetic powder. Then, the first magnetic powder and the second magnetic powder are mixed at a weight ratio of 70:30 to obtain a mixture of two magnetic powders having different average particle diameters.

Then, the magnetic powder was put into an aluminum cup, and the resins A to D were added to the magnetic powder and mixed manually using a spatula for 2 minutes. This obtained the composite magnetic material which is a mixture of magnetic powder and resin.

Next, the composite magnetic material obtained in the mixing step is filled into a resin container having a toroidal space, and the composite magnetic material in the container is pressed with a 600 N press pressure (surface pressure 9.4 kg) using a hydraulic press. / Cm 2) for 10 seconds to produce a toroidal shaped molded body. During this pressing, the temperature of the container was kept at 25 ° C.

The molded body is dried in the atmosphere at 85 ° C. for 2 hours, then dried at 120 ° C. for 1 hour, further dried at 150 ° C. for 4 hours to cure the resin, and a toroidal core as a sample is produced. 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) are obtained. It was. Thereafter, the obtained toroidal core was wound with 40 turns of the primary winding and 3 turns of the secondary winding with the above-described copper wire, and the original reactor was produced.

(4) Heat resistance test Next, the samples of Examples 17 to 19 and Comparative Example 12 were subjected to a high temperature storage test. In the high temperature standing test, the samples of Examples 17 to 19 and Comparative Example 12 were exposed to an atmosphere of 155 ° C. for 24 hours to 1000 hours, and the iron loss Pcv thereafter was measured.

Table 13 is a table showing the rate of change in iron loss (Pcv) when the high temperature storage test is performed on the samples of Examples 17 to 19 and Comparative Example 12. The rate of change of iron loss (Pcv) was calculated by the following equation, with iron loss (Pcv0) at the start of the test and iron loss (Pcv1) after a predetermined time elapsed.
(Pcv1-Pcv0) ÷ Pcv0 × 100 = Pcv change rate (%)

FIG. 23 is a graph created based on Table 13. The vertical axis in FIG. 23 indicates the rate of change of iron loss (Pcv), and the horizontal axis indicates the elapsed time in the high temperature storage test.

As shown in FIG. 23, when the samples of Examples 17 to 19 and Comparative Example 12 were exposed to 155 ° C., the change rate of iron loss (Pcv) in all samples from the start of the test to 24 hours after the start of the test. Will rise significantly. In the samples of Examples 17 to 19 and Comparative Example 12, the rate of change in iron loss (Pcv) after 24 hours from the start of the test is 6.3 to 9.3%. This is a phenomenon that occurs regardless of the heat loss of the resin, and the resin is solidified again by heating the resin, and the stress generated at that time affects (Pcv).

During the period from the start of the test to 400 hours after the start of the test, the rate of change in iron loss (Pcv) does not change significantly in all samples. However, when 400 hours have elapsed after the start of the test, the rate of change in iron loss (Pcv) of the sample of Comparative Example 12 (resin A) increases. On the other hand, when 400 hours have elapsed after the start of the test, there is no significant change in the rate of change in iron loss (Pcv) of the samples (resins B to D) of Examples 17 to 19. This is because the resin contained in the sample of Comparative Example 12 decomposes or disappears due to heat, the magnetic powders come into contact with each other, and the eddy current loss Pev increases, whereas it is contained in the samples of Examples 17-19. This is because the resin does not decompose or disappear.

Furthermore, the change rate (%) of the iron loss (Pcv) of the sample (resin D) of Example 19 increases after 500 hours have elapsed since the start of the test. This is because the heat loss in Resin B with 0.08% loss on heating in 40 hours or Resin D with 0.05% loss on heating in 40 hours is slightly decomposed by heat. Or it may be due to the start of disappearance.

On the other hand, in the samples of Examples 17 and 18 using the resins B and C having a heating loss of 0.08% or less when heated at 155 ° C. for 40 hours, the iron loss (Pcv) ) The rate of change (%) does not change significantly. This is because the resin contained in the samples of Example 17 and Example 18 does not decompose or disappear due to heat and secures insulation between the magnetic powders, so that the eddy current loss Pev is suppressed from increasing. .

As mentioned above, even when the magnetic core is exposed to an atmosphere at 155 ° C. for more than 400 hours by using a resin having a weight loss of 0.1% or less when exposed to an atmosphere at 220 ° C. for 40 hours, iron loss (Pcv) Can be suppressed. Furthermore, by using a resin having a loss on heating of 0.08% or less when exposed to an atmosphere of 220 ° C. for 40 hours, even when the magnetic core is exposed to an atmosphere of 155 ° C. for more than 1000 hours, the iron loss (Pcv) Change can be suppressed.

(Detailed changes in iron loss Pcv)
The iron loss Pcv is a total value of the hysteresis loss Phv and the eddy current loss Pev. In the high temperature storage test in Table 12 and FIG. 23, eddy current loss Pev was cited as the cause of the increase in iron loss Pcv. Below, taking the samples of Comparative Example 12 and Example 18 using Resin A as examples, the increase in the change rate (%) of Pcv and the amount of change in hysteresis loss Phv and eddy current loss Pev will be verified.

Table 14 shows the 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 in the sample of Comparative Example 12 using Resin A and the sample of Example 18 for Resin C. It is a table | surface which shows the value of.

As shown in Table 14, in the sample of Comparative Example 12, the eddy current loss Pev after the lapse of 400 hours from the start of the test is 6.2, whereas the eddy current loss Pev after the start of the test is 1000 hours after the start of the test. The eddy current loss Pev is 9.0. The change rate of the eddy current loss Pev at this time is 45% from (9.0-6.2) /6.2×100. On the other hand, the hysteresis loss Phv after the lapse of 400 hours from the start of the test is 21.3, whereas the hysteresis loss Phv after the lapse of 1000 hours from the start of the test is 23.1. It can be seen that the change rate of hysteresis loss Phv at this time is about 8.5% from (23.1-21.3) /21.3×100. That is, in Table 14 and FIG. 23, it can be seen that when the rate of change of Pcv changes greatly, the eddy current loss Pev changes greatly.

On the other hand, in the sample of Example 18, the eddy current loss Pev after the lapse of 400 hours from the start of the test is 6.0, whereas the eddy current loss Pev after the lapse of 1000 hours from the start of the test. Becomes 6.1. The change rate of the eddy current loss Pev is 1.7% from (6.1-6.0) /6.0×100. On the other hand, the hysteresis loss Phv after the lapse of 400 hours from the start of the test is 20.1, whereas the hysteresis loss Phv after the lapse of 1000 hours from the start of the test is 20.2. The change rate of the hysteresis loss Phv is about 0.5% from (20.2-20.1) /20.1×100. In Table 14, in the sample of Example 18, both the eddy current loss Pev and the hysteresis loss Phv are not significantly changed. Therefore, it can be seen that the change rate (%) of the iron loss Pcv is also small in Table 14 and FIG.

(Conclusion)
From the above, a magnetic core made from a soft magnetic composite material containing a resin having a loss on heating of 0.1% or less when heated at 220 ° C. for 40 hours has an iron loss Pcv even when used at 155 ° C. for a long time. It can be seen that the rate of change (%) can be kept small. This is because a resin with a small loss on heating when heated at 220 ° C. for 40 hours does not decompose or disappear even when exposed to a high temperature atmosphere for a long time, so that contact between magnetic powders can be suppressed. Yes, this makes it possible to realize low eddy current loss.

[5. Other Embodiments]
The present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

For example, in Embodiment II, as a method of providing a coil in a reactor, a method of placing a coil in a container and embedding it in a composite magnetic material in a molding process has been described. In addition, a method including a winding step of winding a conductive wire constituting the coil around the molded body may be adopted.

In Embodiment III, as a method of providing a coil in a reactor, a method of placing a coil in a container and embedding it in a composite magnetic material in the molding process has been described. However, a molded body of a predetermined shape made of a composite magnetic material is molded in advance. In addition, a method including a winding step of winding a conductive wire constituting the coil around the molded body may be adopted.

In addition, in the present embodiment III, the magnetic core is formed by pouring a soft magnetic composite material in which soft magnetic powder and resin are mixed in advance into a container, but may be formed by the following method. After the mixed powder of the first powder and the second powder is filled in the container, the density of the mixed powder in the container is increased by vibrating the entire container. Thereafter, the resin is infiltrated into the mixed powder whose density is increased by vibration, and is cured by a curing method depending on the type of resin. As a vibration method, the whole container may be vibrated up and down or / and back and forth, and left and right using a motor, a cam, or the like, or a container may be tapped with a hammer-like member. The entire container may be vibrated with an ultrasonic pendulum.

Furthermore, in the present embodiment III, a pressing step of pressing the easily put composite magnetic material with 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 and resin used and the method of the molding process, it is possible to mold a magnetic core having excellent magnetic properties even if the pressing process is omitted. In this case, the pressurization step can be omitted for the purpose of reducing the number of steps and cost.

1 1st magnetic powder 2 2nd magnetic powder 3 Resin 4 Void

Claims

A reactor manufacturing method comprising a core including magnetic powder and resin, and a coil mounted on the core,
A mixing step of mixing 3 to 5 wt% 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 during the molding step;
A curing step of curing the resin in the molded body obtained in the molding step;
Providing
A method for manufacturing a reactor, characterized in that
In the pressing step, the pressure for pressing the mixture is 6.3 kg / cm 2 or more,
The manufacturing method of the reactor of Claim 1 characterized by these.
The pressurizing step is performed by setting the member or the container for pressing the mixture to a temperature higher than room temperature;
The manufacturing method of the reactor of Claim 1 or 2 characterized by these.
The pressurizing step is performed by putting the mixture heated to a temperature higher than room temperature into the container,
The method for producing a reactor according to any one of claims 1 to 3, wherein:
The magnetic powder is formed by mixing two kinds of magnetic powders having different average particle diameters,
The method for producing a reactor according to any one of claims 1 to 4, wherein:
The magnetic powder is a mixture of a first magnetic powder and a second magnetic powder having an average particle size smaller than that of the first magnetic powder,
The addition amount of the first magnetic powder in the magnetic powder is 60 to 80 wt%, and the second magnetic powder is 20 to 40 wt%.
The method for producing a reactor according to any one of claims 1 to 5, wherein:
The first magnetic powder has an average particle size of 100 μm to 200 μm,
The second magnetic powder has an average particle size of 3 μm to 10 μm;
The manufacturing method of the reactor of Claim 6 characterized by these.
The resin is an epoxy resin, a silicone resin, or an acrylic resin;
The method for producing a reactor according to any one of claims 1 to 7, wherein:
A method for producing a core comprising magnetic powder and resin,
A mixing step of mixing 3 to 5 wt% resin with respect to the magnetic powder;
A molding step of molding the mixture obtained in the mixing step into a predetermined container; and
A pressing step of pressing the mixture during the molding step;
A curing step of curing the resin in the molded body obtained in the molding step;
Providing
A method for producing a core characterized by the above.
In the pressing step, the pressure for pressing the mixture is 6.3 kg / cm 2 or more,
The core manufacturing method according to claim 9.
The pressurizing step is performed by setting the member or the container for pressing the mixture to a temperature higher than room temperature;
The method for producing a core according to claim 9 or 10, wherein:
The pressurizing step is performed by putting the mixture heated to a temperature higher than room temperature into the container,
The method for producing a core according to any one of claims 9 to 11, wherein:
The magnetic powder is formed by mixing two kinds of magnetic powders having different average particle diameters,
The method for producing a core according to any one of claims 9 to 12, wherein:
The magnetic powder is a mixture of a first magnetic powder and a second magnetic powder having an average particle size smaller than that of the first magnetic powder,
The addition amount of the first magnetic powder in the magnetic powder is 60 to 80 wt%, and the second magnetic powder is 20 to 40 wt%.
The method for producing a core according to any one of claims 9 to 13, wherein:
The first magnetic powder has an average particle size of 100 μm to 200 μm,
The second magnetic powder has an average particle size of 3 μm to 10 μm;
The method of manufacturing a core according to claim 14.
The resin is an epoxy resin, a silicone resin, or an acrylic resin;
The method for producing a core according to any one of claims 9 to 15, wherein:
A core made of magnetic powder and resin,
The magnetic powder has a first magnetic powder and a second magnetic powder having an average particle size smaller than that of the first magnetic powder,
The addition amount of the first magnetic powder in the magnetic powder is 60 to 80 wt%, the second magnetic powder is 20 to 40 wt%,
The first magnetic powder has an average particle size of 100 μm to 200 μm,
The second magnetic powder has an average particle size of 3 μm to 10 μm,
The content of the resin with respect to the magnetic powder is 3 to 5 wt%,
The ratio of the apparent density of the core to the true density of the magnetic powder is more than 76.47%;
Core characterized by
The ratio of the apparent density of the core to the true density of the magnetic powder is 77.5% or more,
The core according to claim 17.
The resin is an epoxy resin, a silicone resin, or an acrylic resin;
The core according to claim 17 or 18, characterized by the above.
A reactor comprising the core according to any one of claims 17 to 19 and a coil.
A reactor manufacturing method comprising a core including magnetic powder and resin, and a coil mounted on the core,
A mixing step of mixing 3 to 5 wt% 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 curing step of curing the resin in the molded body obtained in the molding step;
A magnetic field applying step of energizing the coil of the molded body during the curing step and applying a magnetic field to the molded body;
Providing
A method for manufacturing a reactor, characterized in that
A reactor manufacturing method comprising a core including magnetic powder and resin, and a coil mounted on the core,
A mixing step of mixing 3 to 5 wt% resin with respect to the magnetic powder;
A molding step of molding the mixture obtained in the mixing step into a predetermined container; and
A winding step of winding a conductive 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 conductive wire is wound;
A magnetic field application step of energizing the conducting wire during the curing step and applying a magnetic field to the molded body;
Providing
A method for manufacturing a reactor, characterized in that
In the magnetic field application step, the magnetic field is 2 kA / m or more,
The method for manufacturing a reactor according to claim 21 or 22, wherein:
Including a pressing step of pressing the mixture during the molding step;
The method for producing a reactor according to any one of claims 21 to 23.
The pressurizing step is performed by maintaining the member or the container for pressing the mixture at a temperature higher than room temperature;
The method for manufacturing a reactor according to claim 24.
The pressurizing step is performed by putting the mixture heated to a temperature higher than room temperature into the container,
The method for manufacturing a reactor according to claim 24 or 25.
The magnetic powder is formed by mixing two kinds of magnetic powders having different average particle diameters,
The method for producing a reactor according to any one of claims 21 to 26.
The magnetic powder is a mixture of a first magnetic powder and a second magnetic powder having an average particle size smaller than that of the first magnetic powder,
The addition amount of the first magnetic powder in the magnetic powder is 60 to 80 wt%, and the second magnetic powder is 20 to 40 wt%.
The method for producing a reactor according to any one of claims 21 to 27.
The first magnetic powder has an average particle size of 100 μm to 200 μm,
The second magnetic powder has an average particle size of 3 μm to 10 μm;
The method for manufacturing a reactor according to claim 28.
The resin is an epoxy resin, a silicone resin, or an acrylic resin;
The method for producing a reactor according to any one of claims 21 to 29.
A soft magnetic composite material obtained by mixing magnetic powder and resin,
A soft magnetic composite material having a reduction rate of 0.1% or less when the resin is exposed to an atmosphere of 220 ° C. for 40 hours.
The soft magnetic composite material according to claim 31, wherein the reduction rate is 0.08% or less.
The soft magnetic composite material according to claim 31 or 32, wherein the decreasing rate is a decreasing rate of the weight of the resin.
The magnetic powder is
A first magnetic powder having a predetermined average particle size;
A second magnetic powder having an average particle size smaller than the first magnetic powder;
The soft magnetic composite material according to any one of claims 31 to 33, comprising:
The average particle diameter of the first magnetic powder is 100 to 200 μm,
The soft magnetic composite material according to claim 34, wherein the second magnetic powder has an average particle size of 5 to 10 袖 m.
36. The soft magnetic composite material according to claim 34 or 35, wherein the addition amount of the first magnetic powder in the magnetic powder is 60 to 80 wt%, and the second magnetic powder is 20 to 40 wt%.
The soft magnetic composite material according to any one of claims 31 to 36, wherein the resin is a thermosetting resin.
The soft magnetic composite material according to any one of claims 31 to 37, wherein the resin is an epoxy resin.
A magnetic core made of the soft magnetic composite material according to any one of claims 31 to 38.
40. The magnetic core according to claim 39, wherein the rate of change in iron loss when the magnetic core is exposed to an atmosphere at 155 [deg.] C. for 500 hours or more is 10% or less.
A reactor comprising the magnetic core according to claim 39 or 40 and a coil.