Laminated core, noise filter, and magnetic core

Abstract

The laminated core according to the present invention is formed from a magnet formed by laminating soft magnetic metal ribbons, and has a resin between the layers of the soft magnetic metal ribbons. When the total of the interlayer distances d of the soft magnetic metal ribbons is S, the average of the interlayer distances d of the soft magnetic metal ribbons is dave, and the total of the interlayer distances of the following among the layers of the soft magnetic metal ribbons is S4, the interlayer distances between the layers are at least four times the average dave. The ratio R4 = S4 / S of the total S4 to the total S is 10.0% or less. The noise filter of the present invention and the magnetic core of the present invention use the laminated core.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Japanese Patent Application No. 2023-038113, filed in Japan on March 10, 2023, the disclosure of which is hereby incorporated by reference in its entirety. Technical Field

[0003] The present invention relates to a laminated core, and a noise filter and a magnetic core using the laminated core. Background Art

[0004] Laminated cores made of stacked soft magnetic metal strips are used as magnetic cores for noise filters, transformers, motors, and other applications. Typically, stacked cores made by simply stacking soft magnetic metal strips are weak and unable to maintain their shape. Therefore, resin is filled between the layers of soft magnetic metal strips as a binder and cured to improve strength.

[0005] Here, in Patent Document 1, in order to form gaps in the choke coil core, a wound core of a nanocrystalline alloy is impregnated with resin (hereinafter, such resin is also referred to as "impregnation resin"). Epoxy resin is used as the impregnation resin.

[0006] Furthermore, Patent Document 2 describes a noise filter in which a nanocrystalline alloy foil core is cut into segments, impregnated with resin, and cured. The patent explains that by specifying the thickness of the resin layer relative to the thickness of the nanocrystalline alloy foil, impedance reduction is minimized even during cutting. This patent also uses epoxy resin as the impregnation resin.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Laid-Open No. 9-027413;

[0010] Patent document 2: Japanese Patent Application Laid-Open No. 2021-163772. Summary of the Invention

[0011] Problems to be solved by the invention

[0012] However, in the laminated core described above, it has been found that the magnetic permeability may be lower than the desired value.

[0013] Therefore, an object of the present invention is to provide a laminated core having high magnetic permeability, a noise filter having a high noise suppression effect, and a high-efficiency magnetic core.

[0014] Solutions for solving problems

[0015] The inventors have conducted extensive research to solve the above-mentioned problem and have found that the thickness of the impregnated resin varies between layers, causing deformation during the curing process after impregnation, thereby reducing the magnetic permeability of the laminated core. They have also found that in a laminated core formed by impregnating the interlayers of soft magnetic metal strips with resin and curing them, the average interlayer distance d of the soft magnetic metal strips is d ave The ratio R4 of the total interlayer distance S4 of the soft magnetic metal strips more than 4 times of the total interlayer distance d of the soft magnetic metal strips is 10.0% or less, which can advantageously solve the above problems and complete the present invention.

[0016] The gist of the present invention is as follows.

[0017] (1) A laminated core characterized by being formed of a magnetic body composed of laminated soft magnetic metal strips,

[0018] There is resin between the layers of the soft magnetic metal strips.

[0019] When the total of the interlayer distances d of the soft magnetic metal strips is S and the average of the interlayer distances d of the soft magnetic metal strips is d ave When the sum of the interlayer distances between the following layers among the layers of the soft magnetic metal thin strip is S4, the interlayer distances between the above layers are the average d ave More than 4 times,

[0020] The ratio R4 = S4 / S of the total S4 to the total S is 10.0% or less.

[0021] Here, if Figure 3 As schematically shown, the "interlayer distance d of the soft magnetic metal strips" refers to the distance between each layer of three radial lines spaced 120° apart when the stacked core is viewed from the side. Figure 2 As schematically shown, the "interlayer distance d of the soft magnetic metal strip" is measured on each radial line based on each interlayer existing in the radial region of 90% of the total radial length. The radial region of 90% of the total radial length is composed of the following areas: the radial region of the laminated core located at 45% of the total radial length on the radial outside, and the radial region of the laminated core located at 45% of the total radial length on the radial inside, starting from the radial midpoint between the radial outer end and the radial inner end of the laminated core. It should be noted that the interlayers at the end of the radial region of 90% of the total radial length are not measured. Thus, the "total interlayer distance S", "average interlayer distance d" and the "average interlayer distance d" are calculated based on the "interlayer distance d of the soft magnetic metal strip" between all the layers in the radial region of 90% of the total radial length on the three radial lines. ave ” and “average d aveThe total of the above-mentioned interlayer distances S4" between layers is 4 times or more of the interlayer distance. In addition, the "interlayer distance d of the soft magnetic metal strip" can be measured using an optical microscope.

[0022] (2) The laminated core according to (1) above, wherein the glass transition temperature of the resin between the layers of the soft magnetic metal strips is 85° C. or higher.

[0023] (3) The laminated core according to (1) above, wherein the glass transition temperature of the resin between the layers of the soft magnetic metal strips is 125° C. or higher.

[0024] (4) The laminated core according to any one of (1) to (3) above, wherein the ratio R4=S4 / S is 10.0% or less.

[0025] (5) The laminated core according to any one of (1) to (4) above, wherein the soft magnetic metal strip is formed of a nanocrystalline alloy.

[0026] (6) The laminated core according to any one of (1) to (4) above, wherein the soft magnetic metal strip is formed of an amorphous alloy.

[0027] (7) The laminated core according to any one of (1) to (6) above, wherein the laminated core has an impedance relative permeability μrz of 10,000 or more at 100 kHz.

[0028] (8) The laminated core according to any one of (1) to (7) above, wherein

[0029] The laminated core is divided into at least two separate cores along the circumferential direction, or

[0030] The laminated core is formed by combining a plurality of annular laminated magnetic sheets having discontinuous portions interrupted in the circumferential direction.

[0031] (9) A noise filter using the laminated core according to any one of (1) to (8) above.

[0032] (10) A magnetic core for a transformer or a motor, using the laminated core according to any one of (1) to (8) above.

[0033] Effects of the Invention

[0034] According to the present invention, it is possible to provide a laminated core having high magnetic permeability, a noise filter having a high noise suppression effect, and a high-efficiency magnetic core. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a side view of a laminated core according to one embodiment of the present invention.

[0036] Figure 2 is used to illustrate the total interlayer distance S and the average interlayer distance d ave Schematic diagram of the measurement range.

[0037] Figure 3 It is a schematic diagram for explaining the method of measuring the interlayer distance d.

[0038] Figure 4 This figure shows one of the observation images obtained by measuring the distance between metal strip layers in Example 1.

[0039] Figure 5 This is a histogram of the distance between metal strip layers in Example 1.

[0040] Figure 6 This figure shows one of the observation images obtained by measuring the distance between metal strip layers in Comparative Example 1.

[0041] Figure 7 : is a histogram of the distance between metal strip layers of Comparative Example 1. DETAILED DESCRIPTION

[0042] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0043] <Laminated core>

[0044] Figure 1 FIG. 1 is a side view of a laminated core according to an embodiment of the present invention. Figure 1 As shown, the laminated core 1 is formed of a magnetic body composed of laminated soft magnetic metal strips 2. The laminated core 1 has a cylindrical shape. In addition, resin (impregnated resin) 3 is present between the layers of the soft magnetic metal strips 2. Figure 1 The diagram schematically shows a laminated core 1 which is a ring-shaped magnetic body in which soft magnetic metal strips 2 are wound into a roll and laminated in the radial direction, with resin 3 between the layers.

[0045] Although not particularly limited, the laminated core 1 can have an outer diameter of 15 to 250 mm, an inner diameter of 6 to 155 mm, and a height (height in the axial direction of the cylindrical shape) of 3 to 100 mm.

[0046] <<Soft magnetic metal strip>>

[0047] The soft magnetic metal strip 2 preferably has a low coercive force and a high magnetic permeability. Examples of the soft magnetic material of the soft magnetic metal strip 2 include soft magnetic metals such as Fe-Ni alloys (Permalloy) and Fe-Si alloys (silicon steel), amorphous alloys such as Co-based amorphous alloys and Fe-based amorphous alloys, and Fe-based nanocrystalline alloys. Specifically, the soft magnetic metal strip 2 is preferably formed from a nanocrystalline alloy or an amorphous alloy.

[0048] When an amorphous alloy or an Fe-based nanocrystalline alloy is used as the soft magnetic metal strip 2, for example, a metal alloy represented by the general formula: (Fe 1-a M a ) 100-x-y-z-b-c-d A x M' y M” z X b Si c B d (atomic %) (wherein, M represents at least one element selected from Co and Ni, A represents at least one element selected from Cu and Au, M' represents at least one element selected from Ti, V, Zr, Nb, Mo, Hf, Ta and W, M" represents at least one element selected from Cr, Mn, Sn, Zn, Ag, In, platinum group elements, Mg, N and S, X represents at least one element selected from C, Ge, Ga, Al and P, and a, x, y, z, b, c and d respectively satisfy 0≤a≤0.1, 0.1≤x≤3, 1≤y≤10, 0≤z≤10, 0≤b≤10, 11≤c≤17, 3≤d≤10 and 65≤100-xyzbcd≤85.) An alloy having a composition represented by

[0049] The composition of the Fe-based nanocrystalline alloy is not particularly limited, but is preferably composed of, in atomic percent, 0.5-2.0% Cu, 1.0-5.0% Nb, 11.0-15.0% Si, and 5.0-10.0% B, with the remainder essentially consisting of Fe. However, this is not a limitation as long as the characteristics of the present invention are met.

[0050] When using an amorphous alloy or an Fe-based nanocrystalline alloy as the soft magnetic metal strip 2, the thickness of the soft magnetic metal strip 2 is not particularly limited and can be, for example, 10 to 30 μm. By keeping the thickness of the soft magnetic metal strip 2 below 30 μm, the cooling rate can be sufficient to uniformly form the amorphous layer, preventing a decrease in magnetic permeability. On the other hand, by keeping the thickness of the soft magnetic metal strip 2 above 10 μm, the surface of the soft magnetic metal strip 2 can be free of voids and discontinuous portions, thereby suppressing a decrease in strength and preventing breakage during coiling, which would otherwise degrade workability. Furthermore, after lamination, the soft magnetic metal strip 2 is less likely to deform during impregnation and curing with the impregnation resin 3, preventing deformation of the soft magnetic metal strip 2 and thus suppressing a decrease in magnetic permeability. For similar reasons, the thickness of the soft magnetic metal strip 2 is more preferably 12 to 25 μm, and even more preferably 14 to 20 μm. By coiling the soft magnetic metal strip 2, it can be used as a radially stacked ring magnet. Furthermore, by cutting into a predetermined size and stacking them, it can also be used as a laminated magnet.

[0051] <<Impregnation resin>>

[0052] By impregnating the interlayers of the soft magnetic metal strips 2 in the heat-treated laminated core 1 with resin 3, the soft magnetic metal strips 2 can be fixed and their shape maintained. Examples of the impregnating resin 3 include acrylic resins, epoxy resins, polyimide resins, silicone resins, and silicone elastomers. The impregnating resin 3 preferably has a glass transition temperature of 85°C or higher. A glass transition temperature of 85°C or higher prevents dimensional changes and a decrease in adhesive strength of the impregnating resin 3 due to aging in high-temperature environments, allowing for easier fixation of the soft magnetic metal strips 2 and stable shape maintenance. Furthermore, this prevents deformation of the soft magnetic metal strips 2 over time, thereby suppressing a decrease in magnetic permeability. The glass transition temperature of the impregnating resin 3 is more preferably 125°C or higher, even more preferably 130°C or higher, and particularly preferably 150°C or higher. The impregnating resin 3 is preferably an epoxy resin whose glass transition temperature can be adjusted by changing the curing agent, has a low viscosity before curing, and exhibits high adhesion to the soft magnetic metal strips 2 after curing.

[0053] The viscosity of the impregnation resin 3 when impregnating the interlayers of the soft magnetic metal strip 2 is preferably 2000 mPa·s or less. Impregnation with such a low viscosity can prevent the formation of areas between the soft magnetic metal strip 2 where the impregnation resin 3 is insufficiently permeated, or areas where the interlayers of the soft magnetic metal strip 2 are excessively permeated due to expansion and deformation. This allows the ratio R4 = S4 / S, described below, to be maintained below 10.0%, thereby suppressing a decrease in magnetic permeability caused by deformation of the soft magnetic metal strip 2. When using an impregnation resin 3 with a high viscosity, it is preferable to adjust the viscosity by adjusting the temperature or adding a diluent such as an organic solvent. The viscosity of the impregnation resin 3 when impregnating the interlayers of the soft magnetic metal strip 2 is more preferably 550 mPa·s or less.

[0054] The impregnation of the impregnation resin 3 is preferably carried out as follows: the uncured impregnation resin 3 is heated to room temperature to 80°C, and then impregnated at an impregnation pressure of normal pressure to reduced pressure (-0.05 MPaG) for 10 minutes to 60 minutes. The temperature can be adjusted according to the viscosity of the impregnation resin 3 used. By making the impregnation pressure above -0.05 MPaG, it is possible to suppress the generation of excessively impregnated portions that expand and deform the interlayers of the soft magnetic metal strip 2, thereby making the ratio R4=S4 / S described later below 10.0%, which can suppress the deformation of the soft magnetic metal strip 2 and suppress the reduction in magnetic permeability. The impregnation pressure is more preferably normal pressure. In order to efficiently remove bubbles generated from the interlayers of the soft magnetic metal strip 2 during impregnation, the impregnation liquid can also be shaken, or the impregnation liquid can be convected, or vibration can be applied to the impregnation liquid. When impregnation with the impregnation resin 3 is difficult, it is preferable to apply an organic or inorganic adhesive to the surface before laminating the soft magnetic metal strip 2 (metal foil).

[0055] The laminated core 1 impregnated with the impregnation resin 3 is heat-treated to cure the impregnation resin 3. The heat treatment temperature and duration must be appropriately tailored to the resin used; for example, a heat treatment temperature of 50 to 200°C and a heat treatment time of 0.5 to 10 hours can be employed. The heat treatment can be performed in multiple stages, starting at a low temperature.

[0056] Returning to the description of the laminated core 1, the laminated core 1 can be manufactured by forming the raw metal foil into a specified size and shape and then bundling it or winding it into a roll. The filling rate of the metal foil can be adjusted by the restraining force when bundling the metal foil and the tension when winding it, and can be adjusted within a range of, for example, 65 vol% to 85 vol%. By setting the filling rate of the metal foil to, for example, 65 vol% or more, the proportion of magnets will not become too small, thereby not reducing the magnetic permeability and reducing the volume of the laminated core 1. On the other hand, by setting the filling rate of the metal foil to, for example, 85 vol% or less, the interlayer distance d of the soft magnetic metal strips 2 will not become too small, thereby allowing the impregnation resin 3 to fully penetrate the interlayers of the soft magnetic metal strips 2, making it easier to perform curing and molding.

[0057] The laminated metal foil is heat treated to eliminate deformation during molding. Furthermore, the amorphous alloy can precipitate nanocrystals within the amorphous alloy by heat treatment. The heat treatment temperature can be, for example, 350°C to 700°C. The heat treatment is preferably performed in an inert atmosphere such as nitrogen or argon, or in the air.

[0058] exist Figure 1 In the example shown, the laminated core 1 is integral, but in order to improve the installation performance on the cable, the laminated core 1 can also be divided into at least two or more parts along the circumferential direction to form a separate core. Alternatively, a plurality of annular laminated magnetic sheets having discontinuous parts along the circumferential direction can be combined, for example, in the axial direction to form the laminated core 1. In this case, the above-mentioned discontinuous parts adjacent in the axial direction preferably do not overlap when viewed in the axial direction (especially do not have overlapping parts). In the case of a separate core as described above, or a laminated core formed by a combination of a plurality of annular laminated magnetic sheets having discontinuous parts, the performance of the laminated core in which the contact surfaces of the magnetic sheets are not easily deformed over time is more stable. By using a resin with a high glass transition temperature when bonding the soft magnetic metal strip 2, the shape of the contact surface is stable, and the surface roughness is not easily deteriorated, especially in an environment of use exposed to high temperatures, so that stable performance can be maintained even at high temperatures.

[0059] As described above, the laminated core 1 of this embodiment is a laminated core formed of a magnetic body composed of laminated soft magnetic metal strips 2, and has an impregnation resin 3 impregnated between the layers of the soft magnetic metal strips 2. In the laminated core 1 of this embodiment, when the total distance d between the layers of the soft magnetic metal strips 2 is S and the average distance d between the layers of the soft magnetic metal strips 2 is d ave The interlayer distance between the soft magnetic metal strips 2 is an average d ave When the total of the interlayer distances between layers that are four times or more of the total is denoted as S4, the ratio R4 = S4 / S of the total S4 to the total S is 10.0% or less.

[0060] Hereinafter, the effects of the laminated core 1 of the present embodiment will be described.

[0061] According to the laminated core 1 of this embodiment, the impregnation resin 3 is impregnated between the layers of the soft magnetic metal strips 2, thereby fixing and maintaining the shape of the soft magnetic metal strips 2. Furthermore, by setting the ratio R4 = S4 / S to 10.0% or less, deformation in the soft magnetic metal strips 2 can be suppressed, thereby achieving high magnetic permeability of the laminated core 1.

[0062] For the same reason, the ratio R4=S4 / S is preferably 5.0% or less.

[0063] Here, the glass transition temperature of the impregnation resin 3 between the layers of the soft magnetic metal strip 2 is preferably 85°C or above. Recently, products using laminated cores have been widely used for electric vehicles, but due to high-speed operation and high output, the operating temperature environment has increased. Therefore, the impregnation resin that solidifies and molds the laminated core is also required to have high heat resistance. By setting the glass transition temperature, which is one of the indicators of heat resistance, to the above range, the heat resistance can be improved. For the same reason, the glass transition temperature of the impregnation resin 3 between the layers of the soft magnetic metal strip 2 is further preferably 125°C or above.

[0064] Generally, when a highly heat-resistant impregnation resin 3 (for example, an impregnation resin 3 having a glass transition temperature of 85°C or above) is impregnated into the laminated core 1, it is found that there is a tendency for the viscosity to be high as the glass transition temperature is high. This causes the soft magnetic metal strip 2 to be particularly prone to deformation due to the expansion and deformation between the layers, and the excessively impregnated parts, as well as the increased thermal shrinkage during curing. This results in a decrease in magnetic permeability.

[0065] According to the stacked core 1 of the present invention, even when the impregnation resin 3 with a high glass transition temperature as mentioned above is used in consideration of heat resistance, the deformation in the soft magnetic metal strip 2 is suppressed by making the above-mentioned ratio R4=S4 / S less than 10.0%, thereby achieving high magnetic permeability of the stacked core 1, thereby achieving both heat resistance and high magnetic permeability.

[0066] In this embodiment, the laminated core 1 preferably has an impedance relative permeability μrz of 100 kHz or greater. As shown in the examples described below, such a high impedance relative permeability μrz at 100 kHz can be achieved by setting the ratio R4 = S4 / S to 10.0% or less. This high impedance relative permeability μrz at 100 kHz can be achieved, in particular, even when using an impregnation resin 3 with high heat resistance (e.g., one with a glass transition temperature of 85°C or greater).

[0067] Noise Filter

[0068] A noise filter according to one embodiment of the present invention utilizes the laminated core 1 of the aforementioned embodiment. A noise filter utilizing such a laminated core 1 achieves a high noise suppression effect due to its high magnetic permeability. Consequently, the noise filter can be installed in power cables for electronic devices such as automobiles, power generation equipment, power supply equipment, communications devices, and office automation / factory equipment (OA / FA) devices, and used as a noise suppression core to suppress noise generated within these electronic devices or generated externally and conducted within the cables. In particular, when the impregnating resin 3 of the laminated core 1 has a high glass transition temperature (preferably above 85°C), heat resistance can be improved, achieving a balance between heat resistance and high noise suppression.

[0069] In the noise filter of the present invention, the ratio R4 of the total S4 (S4 / S) is 10.0% or less, preferably 5.0% or less. Furthermore, the glass transition temperature of the impregnating resin 3 between the layers of the soft magnetic metal strips 2 is preferably 85°C or greater, more preferably 125°C or greater. The soft magnetic metal strips 2 are preferably formed of a nanocrystalline alloy or an amorphous alloy. The laminated core 1 used in the noise filter of the present invention preferably has an impedance relative permeability μrz of 10,000 or greater at 100 kHz.

[0070] <Core>

[0071] A magnetic core according to one embodiment of the present invention utilizes the laminated core of the aforementioned embodiment. A magnetic core utilizing such a laminated core 1 achieves high efficiency due to its high magnetic permeability. For example, by winding a conductive wire around the laminated core 1 as a primary winding, the core can be mounted on an electronic substrate and used as a common-mode choke coil for noise suppression. Furthermore, by winding conductive wire around the laminated core 1 as a primary winding and a secondary winding, the core can be used as a transformer for power conversion.

[0072] In particular, when the glass transition temperature of the impregnation resin 3 of the laminated core 1 is high (preferably 85° C. or higher), heat resistance can be improved, and both heat resistance and high efficiency can be achieved.

[0073] In the magnetic core of the present invention, the ratio R4 of the total S4 (S4 / S) is 10.0% or less, preferably 5.0% or less. Furthermore, the glass transition temperature of the impregnating resin 3 between the layers of the soft magnetic metal strips 2 is preferably 85°C or greater, more preferably 125°C or greater. The soft magnetic metal strips 2 are preferably formed from a nanocrystalline alloy or an amorphous alloy. The laminated core 1 used in the magnetic core of the present invention preferably has an impedance relative permeability μrz of 10,000 or greater at 100 kHz.

[0074] Example

[0075] Hereinafter, examples of the present invention will be described, but the present invention is not limited to these examples.

[0076] (Examples 1 and 2)

[0077] A laminated core made of laminated soft magnetic metal strips was produced. First, a molten alloy consisting of, in atomic %, 1% Cu, 3% Nb, 13.5% Si, and 9% B, with the remainder essentially consisting of Fe, was quenched using a single-roll method to obtain a thin strip of Fe-based amorphous alloy with a width of 10 mm and a thickness of 15 μm. The Fe-based amorphous alloy was wound into a cylindrical shape with an outer diameter of 28.5 mm, an inner diameter of 18.0 mm, and a height of 10 mm. The cylindrical Fe-based amorphous alloy was inserted into a heat treatment furnace maintained at 490°C in an argon environment and heat treated for 10 minutes. Then, a ring magnet made of an Fe-based nanocrystalline alloy was produced. A solution was prepared by mixing epoxy resin and a curing agent in a specified quantitative ratio. The resulting ring magnet was immersed in the solution at 50°C at normal pressure for 20 minutes to impregnate the ring magnet with the resin. Thereafter, the ring magnet was kept in the air at 180° C. (in the case of Example 1) and 160° C. (in the case of Example 2) for 8 hours to cure the resin, thereby obtaining a laminated core.

[0078] The impedance relative permeability of the resulting laminated core at a frequency of 100 kHz was measured using a Keysight 4294A impedance analyzer. Using a conductor measurement fixture (16047E), a single-turn H-PCV, 0.5 mm Φ, single-strand conductor manufactured by Tanaka Electric Cable was passed through the laminated core. Impedance Z was converted to impedance relative permeability μrz using the formula μrz = Z × Lm / (2πμ0f × Ae). Here, μ0 is the vacuum permeability, Lm is the average magnetic path length, f is the measurement frequency, and Ae is the effective cross-sectional area. For a laminated core with an outer diameter (OD), an inner diameter (ID), and a height (HT), the calculation is: Lm = π(OD + ID) / 2, and Ae = (OD - ID) × HT / 2 × dr. dr is the magnet filling factor, which was 0.75 in this case.

[0079] The coercivity was measured using an automatic coercivity meter, model K-HC1000, manufactured by Tokyo Special Steel. The measurement mode was SLOW, and the measurement direction was the radial direction of the laminated core. A total of three measurements were performed at equal intervals of 120° along the circumference, and the average value was taken. The viscosity of the impregnated resin was measured using a Brookfield viscometer DV1M manufactured by Eikon Seiki Co., Ltd. The resin was preheated to a specified temperature, and the motor speed was adjusted to control the spindle torque at 10-90%. The glass transition temperature of the impregnated resin was measured using a differential scanning calorimeter DSC3500 manufactured by NETZSCH. A small piece of 4 mm × 4 mm × 1 mm was cut from the laminated core impregnated and cured with resin, placed in a Pt container, Ar gas was flowed at 20 mL / min, and the temperature was increased at a rate of 10°C / min from 20°C to 570°C. The glass transition temperature was determined from the starting point of the endothermic reaction. The glass transition temperature of the impregnated resin of the prepared laminated core was 150°C.

[0080] The interlayer distance of the soft magnetic metal strips in the laminated core is measured Figure 2 The side of the laminated core shown in FIG. The side is finely processed with sandpaper of #500 to #2000, and the interlayer distance of the soft magnetic metal strip is measured from the image obtained by observing with a 500x objective lens using a digital microscope RH-2000 manufactured by Hirox. Observe in a straight line along the thickness direction of the soft magnetic metal strip from the inner circumference of the laminated core toward the outer circumference, and take a range including 90% of the thickness w of the laminated core (45% located radially inside and 45% located radially outside from the radial center position). As shown Figure 3 As shown, the observation position is three straight lines (three radial lines) with equal intervals of 120° along the circumferential direction, and the average value d of the interlayer distance d of the soft magnetic metal strip is calculated. ave The sum is S. Based on the obtained interlayer distances of the soft magnetic metal strips, the average interlayer distance d of the soft magnetic metal strips is calculated. ave More than 4 times (4d ave The ratio of the total S4 of the interlayer distances of the soft magnetic metal strips (above) to the total S of the interlayer distances of the soft magnetic metal strips is S4 / S×100 (%).

[0081] The following Table 1 shows the production conditions and measurement results of the obtained laminated core. Figure 4 One of the observation images of the metal strip interlayer distance measurement in Example 1 is shown in FIG. Figure 5 A histogram of the distance between metal strip layers of Example 1 is shown in FIG.

[0082] (Example 3)

[0083] After producing a ring magnet in the same manner as in Example 1, a solution was prepared by mixing a base agent and a curing agent of epoxy resins with different glass transition temperatures in a predetermined ratio. The ring magnet was immersed in the solution at 50°C under normal pressure for 20 minutes to impregnate the ring magnet with the resin. The solution was then held at 150°C in air for 5 hours to cure the resin, resulting in a laminated core. The measurement method was the same as in Example 1. The glass transition temperature of the impregnated resin in the produced laminated core was 125°C. Table 1 shows the production conditions and measurement results for the resulting laminated core.

[0084] (Example 4)

[0085] After producing an annular magnet in the same manner as in Example 1, a solution was prepared by adding 0.5 wt% of a curing accelerator to a solution obtained by mixing epoxy resins with different glass transition temperatures and a curing agent at a predetermined ratio. The annular magnet was then immersed in the solution maintained at 25°C at normal pressure for one hour to impregnate the annular magnet with the resin. The resin was then cured by maintaining the solution at 80°C in air for three hours to obtain a laminated core. The measurement method was the same as in Example 1. The glass transition temperature of the impregnated resin in the produced laminated core was 85°C. Table 1 shows the production conditions and measurement results of the resulting laminated core.

[0086] (Examples 5 and 6)

[0087] After preparing a ring magnet in the same manner as in Example 1, a solution of epoxy resin and curing agent mixed in a predetermined ratio was prepared. The ring magnet was immersed in the solution, which was maintained at 30°C. The solution was then evacuated to -0.05 MPaG and held for 10 minutes. The solution was then released to the atmosphere to allow the resin to permeate the ring magnet. The resin was then cured by holding the solution in the atmosphere at 180°C (for Example 5) and 160°C (for Example 6) for 8 hours, yielding a laminated core. The measurement method was the same as in Example 1. Table 1 shows the production conditions and measurement results for the resulting laminated core.

[0088] (Examples 7 and 8)

[0089] After preparing a ring magnet in the same manner as in Example 1, a solution containing 1 wt% of a curing accelerator was added to a solution of epoxy resin and a curing agent mixed at a predetermined ratio. The ring magnet was immersed in this solution at 50°C for 20 minutes under normal pressure to impregnate the ring magnet with the resin. The resin was then cured by holding the solution in air at 180°C (for Example 7) and 160°C (for Example 8) for 8 hours, yielding a laminated core. The measurement method was the same as in Example 1. Table 1 shows the production conditions and measurement results for the resulting laminated core.

[0090] (Example 9)

[0091] After preparing a ring magnet in the same manner as in Example 1, a solution containing 1 wt% of a curing accelerator was prepared by adding it to a solution of epoxy resin and curing agent mixed at a predetermined ratio. The ring magnet was immersed in this solution, which was maintained at 50°C. The solution was then evacuated to -0.05 MPaG for 10 minutes and then released to the atmosphere to allow the resin to permeate the ring magnet. The resin was then cured by maintaining it in the atmosphere at 180°C for 8 hours, resulting in a laminated core. The measurement method was the same as in Example 1. Table 1 shows the production conditions and measurement results for the resulting laminated core.

[0092] (Examples 10 and 11)

[0093] After preparing a ring magnet in the same manner as in Example 1, a solution containing 1 wt% of a curing accelerator was added to a solution of epoxy resin and a curing agent mixed at a predetermined ratio. The ring magnet was immersed in this solution, maintained at 25°C, at atmospheric pressure for one hour to impregnate the ring magnet with the resin. The resin was then cured by maintaining the solution at 180°C (for Example 10) and 160°C (for Example 11) in air for eight hours, yielding a laminated core. The measurement method was the same as in Example 1. Table 1 shows the production conditions and measurement results for the resulting laminated core.

[0094] (Example 12)

[0095] After producing an annular magnet in the same manner as in Example 1, a solution was prepared by mixing epoxy resins with different glass transition temperatures and a curing agent in a specified quantitative ratio. The annular magnet was immersed in the solution, which was kept at 50°C. The solution was evacuated to -0.05 MPaG and held for 10 minutes. The solution was then opened to the atmosphere to allow the resin to impregnate the annular magnet. Subsequently, the resin was cured by holding the solution at 80°C in the atmosphere for 3 hours to obtain a laminated core. The measurement method was the same as in Example 1. The glass transition temperature of the impregnated resin of the produced laminated core was 50°C. Table 1 shows the production conditions and measurement results of the obtained laminated core.

[0096] (Example 13)

[0097] After producing an annular magnet in the same manner as in Example 1, a solution was prepared by mixing the same epoxy resin and curing agent as in Example 12 in a predetermined ratio. The annular magnet was immersed in the solution, which was maintained at 80°C. The solution was then evacuated to -0.05 MPaG and held for 10 minutes. The solution was then opened to the atmosphere to allow the resin to impregnate the annular magnet. The resin was then cured by maintaining the solution at 80°C in the atmosphere for 3 hours, resulting in a laminated core. The measurement method was the same as in Example 1. The glass transition temperature of the impregnated resin of the laminated core produced was 50°C. Table 1 shows the production conditions and measurement results of the resulting laminated core.

[0098] (Comparative Examples 1 and 2)

[0099] After making an annular magnet in the same manner as in Example 1, make a solution in which epoxy resin and curing agent are mixed in a specified quantitative ratio, immerse the annular magnet in the solution maintained at 25°C, evacuate to -0.10MPaG, hold for 10 minutes, and then open to the atmosphere to allow the resin to be impregnated in the annular magnet. Thereafter, keep the resin in the atmosphere at 180°C (in the case of Comparative Example 1) and 160°C (in the case of Comparative Example 2) for 8 hours to cure the resin and obtain a laminated core. The measurement method is the same as in Example 1. Table 1 shows the production conditions and measurement results of the obtained laminated core. In addition, Figure 6 One of the observation images for measuring the distance between metal strip layers of Comparative Example 1 is shown in FIG. Figure 7 A histogram of the metal strip interlayer distance of Comparative Example 1 is shown in FIG.

[0100] (Comparative Example 3)

[0101] After preparing a ring magnet in the same manner as in Example 1, a solution containing an epoxy resin and a curing agent in a predetermined ratio was prepared. The ring magnet was immersed in the solution, which was maintained at 30°C. The solution was then evacuated to -0.10 MPaG and held for 10 minutes before being released to the atmosphere to allow the resin to permeate the ring magnet. The resin was then cured by holding the solution at 180°C in the atmosphere for 8 hours, yielding a laminated core. The measurement method was the same as in Example 1. Table 1 shows the production conditions and measurement results for the resulting laminated core.

[0102] (Comparative Examples 4 and 5)

[0103] After preparing an annular magnet in the same manner as in Example 1, a solution was prepared by adding 1 wt% of a curing accelerator to a solution of epoxy resin and curing agent mixed at a predetermined ratio. The annular magnet was immersed in this solution maintained at 25°C, evacuated to -0.1 MPaG, and held for 10 minutes. The solution was then opened to the atmosphere to allow the resin to permeate the annular magnet. The resin was then cured by holding the solution in the atmosphere at 180°C (for Comparative Example 4) and 160°C (for Comparative Example 5) for 8 hours to obtain a laminated core. The measurement method was the same as in Example 1. Table 1 shows the production conditions and measurement results of the resulting laminated core.

[0104] (Comparative Example 6)

[0105] After preparing a ring magnet in the same manner as in Example 1, a solution containing 1 wt% of a curing accelerator was prepared by adding it to a solution of epoxy resin and curing agent mixed at a predetermined ratio. The ring magnet was immersed in this solution, which was maintained at 50°C. The solution was then evacuated to -0.1 MPaG and held for 10 minutes before being released to the atmosphere to allow the resin to permeate the ring magnet. The resin was then cured by holding the solution at 180°C in the atmosphere for 8 hours, yielding a laminated core. The measurement method was the same as in Example 1. Table 1 shows the production conditions and measurement results for the resulting laminated core.

[0106] [Table 1]

[0107]

[0108] When observing Figure 4 In the observation image of the interlayer distance of the soft magnetic metal strip of Example 1, the metal strip intervals (interlayer distances) are uniform. Figure 6 In the observation image of Comparative Example 1 shown, it is observed that the interlayer spacing of the soft magnetic metal strips is widened, and deformation occurs in the metal strips. Figure 7 The histogram of the interlayer distance of the soft magnetic metal strip of Comparative Example 1 shows that the soft magnetic metal strip has a large distribution of interlayer distances. As shown in Table 1, the average interlayer distance d of the soft magnetic metal strip of Example 1 is d ave The ratio R4 = S4 / S, which is the sum of the interlayer distances S4 of the soft magnetic metal strips four times or more of the thickness of the strips, to the sum of the interlayer distances d of the soft magnetic metal strips, is 2.2%. In contrast, the ratio R4 = S4 / S in Comparative Example 1 is larger, at 15.2%. The impedance relative permeability μrz of Example 1 is 12270, whereas the impedance relative permeability μrz of Comparative Example 1 is as low as 8048. It can be seen that the smaller the R4 = S4 / S ratio, the higher the μrz.

[0109] An examination of the other Examples and Comparative Examples reveals that even when using an impregnation resin with a high glass transition temperature, a laminated core with a μrz exceeding 10,000 can be obtained by setting R4 to 10% or less. Comparing the ratio R3 (= S3 / S × 100)% of the total interlayer distances (S3) of the soft magnetic metal strips 2 (three or more times the average of the interlayer distances) to the total interlayer distances (d) of the soft magnetic metal strips, the laminated core of Example 1, with a μrz exceeding 10,000, has an R3 of 10.4%, while the laminated core of Comparative Example 6, with a μrz of 10,000 or less, has an R3 of 10.3%, which is comparable, with no significant difference observed. Therefore, a laminated core with an R4 of 10% or less exhibits high magnetic permeability and stable operation even in high-temperature environments. This allows for high noise suppression in noise filters and reduced losses in magnetic cores for transformers and electric motors.

[0110] Industrial applicability

[0111] The laminated core of the present invention can be incorporated into power cables for electronic devices such as automobiles, power generation equipment, power supply equipment, communications devices, and office automation / facilitation equipment, serving as a noise suppression core to suppress noise generated within these electronic devices or generated externally and conducted through the cables. Furthermore, by winding a primary conductor around the laminated core of the present invention, it can be incorporated into an electronic substrate and used as a common-mode choke coil for noise suppression. Furthermore, by winding a primary conductor and a secondary conductor around the laminated core of the present invention, it can be used as a transformer for power conversion.

[0112] Description of Reference Numerals

[0113] 1: Laminated core;

[0114] 2: Soft magnetic metal strip;

[0115] 3: Resin (impregnated with resin).

Claims

1. A laminated core, characterized in that: It is a magnet composed of stacked soft magnetic metal strips. There is a resin between the layers of the soft magnetic metal strips, When the total of the interlayer distances d of the soft magnetic metal strips is S and the average of the interlayer distances d of the soft magnetic metal strips is d ave , when the total of the interlayer distances between the following layers among the layers of the soft magnetic metal thin strip is S4, the interlayer distances between the layers are the average d ave More than 4 times, The ratio R4 = S4 / S of the total S4 to the total S is 10.0% or less.

2. The laminated core according to claim 1, wherein The glass transition temperature of the resin between the layers of the soft magnetic metal strips is 85° C. or higher.

3. The laminated core according to claim 1, wherein The glass transition temperature of the resin between the layers of the soft magnetic metal strips is 125° C. or higher.

4. The laminated core according to any one of claims 1 to 3, wherein The ratio R4=S4 / S is 5.0% or less.

5. The laminated core according to any one of claims 1 to 3, wherein The soft magnetic metal strip is formed of a nanocrystalline alloy.

6. The laminated core according to any one of claims 1 to 3, wherein The soft magnetic metal strip is formed of an amorphous alloy.

7. The laminated core according to any one of claims 1 to 3, wherein The impedance relative permeability μrz at 100 kHz is 10,000 or more.

8. The laminated core according to any one of claims 1 to 3, wherein The laminated core is divided into at least two split cores along the circumferential direction, or The laminated core is formed by combining a plurality of annular laminated magnetic sheets having discontinuous portions along the circumferential direction. 9 . A noise filter using the laminated core according to claim 1 . 10 . A magnetic core for a transformer or a motor, comprising the laminated core according to claim 1 .

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