JP2018098261A - Method for manufacturing reactor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a reactor, which makes possible to obtain a reactor with a core having a high initial magnetic permeability.SOLUTION: A method for manufacturing a reactor including a core including magnetic powder and a resin, and a coil mounted on the core comprises: a mixing step of mixing the magnetic powder with 3-5 wt.% of the resin; a shaping step of putting a mixture obtained by the mixing step and the coil in a predetermined container, followed by shaping; a curing step of curing the resin in a resultant shape obtained by the shaping step; and a magnetic field-applying step of applying a magnetic field to the resultant shape by causing an electric current to pass through the coil in the shape during the curing step.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for manufacturing a reactor including a core made of magnetic powder and resin, and a coil.

  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.

  The reactor is required to have magnetic characteristics 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.

  Moreover, in order to respond | correspond to various uses, there exists a request to shape | mold the core used for a reactor in arbitrary shapes. As a reactor that meets such a demand, there is a reactor equipped with a core type called a metal composite core.

  A 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.

JP 2012-33727 A

  The MC core has a flat magnetic characteristic. 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 is known in which, in the MC core manufacturing process, a magnetic field is externally applied to align the magnetic powder in the MC core (Patent Document 1).

  In such a conventional technique, a conductive member for forming a current path is separately installed, 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, it is difficult to generate a magnetic flux in the direction in which it is desired to be actually oriented due to restrictions on the installation conditions of the conductive member. 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.

  The objective of this invention is providing the manufacturing method of the reactor which can obtain the reactor provided with the core with high initial permeability.

In order to achieve the above 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, and has the following configuration. It is characterized by that.
(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.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the reactor which can obtain the reactor provided with the core with high initial permeability can be provided.

It is a flowchart for demonstrating the manufacturing method of the reactor which concerns on embodiment. It is a figure for demonstrating a formation process and a pressurization process. 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%.

[1. Embodiment]
[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.

  The resin is mixed with magnetic powder and holds 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.

  It is preferable that 3-5 wt% of resin is contained 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, Initial 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 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 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. There are no particular limitations on the method of winding the coil and the material and shape of the wire.

[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 pressurizing step, (4) a curing step, and (5) a magnetic field applying 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, and a magnetic powder mixing step for forming the magnetic powder and a resin mixing step for adding 3 to 5 wt% of the resin to the magnetic powder and mixing the magnetic powder and the resin are included.

  The mixing in each mixing step can be performed automatically using a predetermined mixer or manually. 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.

  As a container, the thing of various shapes is used according to the shape of the core to manufacture. 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 a container used for a 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.

  Moreover, you may comprise all or one part of a container with metals with high heat conductivity, such as aluminum and 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. 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).

  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 a coil in a container, as shown in FIG. 2, a composite magnetic material is put in a container, and a composite magnetic material is spread in the shape of a container by a 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 pressing step may be performed by setting the pressing member that presses 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. 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.

  In the pressurizing step, the temperature of the container or the pressing member may be raised, or the composite magnetic material itself may be heated 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, and the like of the resin. For example, the drying time can be 1 to 4 hours, but is not limited thereto. The drying temperature can be appropriately changed according to the type, content, drying time, and the like of the resin. For example, the drying temperature can be 85 ° C to 150 ° C, but is not limited thereto. The drying temperature is the temperature of the drying atmosphere.

  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.

(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.

  By 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 the 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 of aligning the magnetization directions of the crystal grains in the magnetic powder, and the DC superposition characteristics are improved by exciting the second magnetic powder.

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

[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 containing 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.

  Thereby, the reactor provided with the core with high initial permeability can be obtained. That is, in the conventional MC core, the amount of resin added to the magnetic powder was more than 5 wt%, but the density and initial permeability can be improved by setting the amount to 3 to 5 wt%. 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, and the added amount of the first magnetic powder in the magnetic powder is 60 to 60. 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.

(7) The first magnetic powder has an average particle diameter of 20 to 150 μm, and the second magnetic powder has an average particle diameter 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.

[1-4. Example]
Examples of the present invention will be described below with reference to Tables 1 to 3 and FIGS.
(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.

<Density>
The density of the core is the apparent density. That is, the outer diameter, inner diameter, and height of the sample of each core 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 measurement device. This calculation was performed by calculating the hysteresis loss coefficient and the eddy current loss coefficient of the iron loss frequency curve by the following method (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

<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 diameter of 123 μm and Fe-6.5% Si having an average particle diameter of 5.1 μm. 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 1 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 base reactor 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. In that case, it supplied with electricity so that it might become 4.85 kA / m during the drying time in each temperature, and the sample of Examples 1-5 was obtained. The difference between Examples 1 to 5 is the amount of resin added, which is 3.0 to 5.0 wt%, respectively. Moreover, the toroidal coil produced without applying a magnetic field during resin hardening was produced, and the samples of Comparative Examples 1-5 were obtained.

  FIG. 3 is a graph of initial permeability with respect to the amount of resin with and without the application of a magnetic field. As shown in Table 1 and FIG. 3, 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. 4 is a graph of the rate of change of magnetic permeability with respect to the amount of resin. The “change rate” shown in Table 1 and FIG. 4 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. 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. 4, 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 2, and the reactor sample is processed in the same process as (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 2.

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. 5 is a graph of the L0 value change rate with respect to the applied magnetic field during the curing process, and Table 2 is graphed. As shown in Table 2 and FIG. 5, 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 3 is a table showing the L value saturation increase rate and the half value magnetic field of the L value saturation increase rate for each resin amount. The L value saturation increase rate is the 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 3 and FIG. 5, 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 improving 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 follows and examined for the difference in the initial inductance value (L0) when the composite magnetic material was pressed and when the resin amount was 3 to 5 wt%. 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 4.
<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, initial inductance values (L0) were calculated for the prepared samples with and without the pressurization process, respectively. The rate of change was calculated from the calculated inductance value (L0) based on equation (5). The results are shown in Table 4 and FIGS.

  FIG. 6 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. 6, 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. 7 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. 7, 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 5 and FIGS.

  FIG. 8 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. 8, 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. 9 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. 9, it was found that the rate of change in the L0 change rate is higher when the pressurization process is performed.

(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 6 and FIGS.

  FIG. 10 is a graph of the initial inductance value of the reactor manufactured with each applied magnetic field during the curing process. FIG. 11 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. 10 and 11, 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. 11, 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 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.

(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 produced in the same manner as in the mixing step (a) under the conditions shown in Table 7 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 7.

  As shown in Table 7, 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.

[3. 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 the embodiment, 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. Alternatively, a method including a winding step of winding a conducting wire constituting the coil around the molded body may be adopted.

Claims (10)

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 manufacturing method of the reactor of Claim 1 or 2 characterized by these. Including a pressing step of pressing the mixture during the molding step;
The manufacturing method of the reactor in any one of Claims 1-3 characterized by these. The pressurizing step is performed by maintaining the member or the container for pressing the mixture at a temperature higher than room temperature;
The manufacturing method of the reactor of Claim 4 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 claim 4 or 5. 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 6. 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 7. 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 8 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 9.

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