Magnetic core and noise filter

Abstract

To provide a magnetic core having high impedance relative permeability in a high frequency area.SOLUTION: A magnetic core has a plurality of magnetic laminated pieces. The magnetic laminated piece is composed of laminated soft magnetic metal thin strips, and has a height corresponding to a short direction length of the soft magnetic metal thin strips. Each of the magnetic laminated pieces is arranged at intervals in the height direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a magnetic core and a noise filter. [Background technology]

[0002] Magnetic cores made of soft magnetic materials are used as noise filters and magnetic cores for transformers, motors, etc. Examples of soft magnetic materials include sintered ferrite, which is an oxide magnetic material; electromagnetic steel sheets; and wound or laminated ribbons of soft magnetic metals such as amorphous and nanocrystalline materials.

[0003] For example, Patent Document 1 describes that by using a core made by directly stacking and integrating multiple oxide magnetic bodies (sintered bodies) that are obtained by dividing a closed magnetic circuit core parallel to the magnetic path direction, the resonant frequency of the geometric resonance effect is increased, thereby improving characteristics in the high frequency range.

[0004] Furthermore, for example, Patent Document 2 describes that in a core made by winding a ribbon of Fe-based nanocrystals, applying a magnetic field in the ribbon width direction during heat treatment improves the characteristics in the high frequency range. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 3814776 [Patent Document 2] Patent No. 7028290 Summary of the Invention [Problem to be solved by the invention]

[0006] The core described in Patent Document 1 uses a metal material with low resistance, which causes a large amount of eddy current to flow, and there is a risk that high frequency characteristics will deteriorate.

[0007] Furthermore, with the technology described in Patent Document 2, if the core is enlarged, particularly if the width of the ribbon is increased, the impedance characteristics in the high frequency range of the MHz band may be degraded. Therefore, depending on the core dimensions, there is a risk that the characteristics in the high frequency range may not be improved.

[0008] On the other hand, in a magnetic core made by winding a soft magnetic metal ribbon, the impedance relative permeability in the high frequency range decreases as the dimension in the short-side length direction of the ribbon (height direction of the magnetic core) increases. Therefore, in order to obtain good high frequency characteristics for a magnetic core with a large height dimension, it was necessary to increase the external dimensions of the magnetic core.

[0009] Therefore, an object of the present invention is to provide a magnetic core having a high impedance relative permeability in the high frequency range. Another object of the present invention is to provide a noise filter that has a high noise suppression effect in the high frequency range. [Means for solving the problem]

[0010] As a result of intensive research by the inventors to solve the above-mentioned problems, it was found that by using a plurality of laminated cores (magnetic laminated pieces) with small height dimensions as a magnetic core having a constant height dimension formed by laminating soft magnetic metal thin ribbons and arranging each laminated core at intervals in the height direction, it is possible to have a high impedance relative permeability in a frequency band of 1 MHz or more, and further that the above-mentioned high impedance relative permeability can be ensured even if the height dimension of the magnetic core is increased. The present invention has been made based on the above findings. That is, the gist and configuration of the present invention are as follows.

[0011] [1] A magnetic core having a plurality of magnetic laminations, the magnetic laminated piece is formed by laminating soft magnetic metal ribbons, and has a height corresponding to the length of the soft magnetic metal ribbons in the short side direction, A magnetic core, characterized in that the magnetic laminated pieces are arranged side by side at intervals in the height direction.

[0012] [2] The magnetic core according to [1], wherein the interval between adjacent magnetic laminated pieces is 0.02 mm or more.

[0013] [3] The magnetic core according to [1] or [2], wherein the height of each of the plurality of magnetic laminated pieces is 0.5 mm or more and 20 mm or less.

[0014] [4] Each of the plurality of magnetic laminations has a circular structure and an average magnetic path length L m (mm), height is h (mm), and radial thickness is t (mm), L m The coefficient Cs calculated by / (h·t) is 90.0 mm -1 The magnetic core according to any one of [1] to [3] below.

[0015] [5] The magnetic core according to any one of [1] to [4], wherein the soft magnetic metal ribbon contains an Fe-based nanocrystalline alloy.

[0016] [6] The magnetic core according to any one of [1] to [5], which is used in a frequency band of 1 MHz or more.

[0017] [7] A noise filter comprising the magnetic core according to any one of [1] to [6]. [Effects of the Invention]

[0018] According to the present invention, it is possible to provide a magnetic core having a high impedance relative permeability in the high frequency range. Furthermore, according to the present invention, it is possible to provide a noise filter that has a high noise suppression effect in the high frequency range. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a schematic diagram illustrating a magnetic core according to an embodiment of the present invention and a magnetic laminate piece used in the magnetic core. [Figure 2]2 is a schematic diagram of a surface (a surface formed by the longitudinal sides of a soft magnetic metal ribbon) of a magnetic laminate piece used in a magnetic core according to one embodiment of the present invention. FIG. [Figure 3] FIG. 10 is a schematic diagram for explaining the measurement range of the total interlayer distance S and the average dave of the interlayer distances d. [Figure 4] FIG. 2 is a schematic diagram for explaining a method for measuring the interlayer distance d. [Figure 5] 1 is a plot of Zmeas / Zsum at each frequency versus the spacing between magnetic laminated pieces, as measured in the examples. [Figure 6] FIG. 10 is a diagram showing the frequency characteristics of impedance Z for a magnetic core according to an example of the present invention and a magnetic core according to a comparative example, measured in an example. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, embodiments of the magnetic core and noise filter of the present invention will be described. However, the description is intended to be an example of the present invention and does not limit the present invention in any way.

[0021] (magnetic core) A magnetic core according to one embodiment of the present invention (hereinafter sometimes referred to as "the magnetic core of this embodiment") is a magnetic core comprising a plurality of magnetic laminated pieces, each of which is formed by laminating soft magnetic metal ribbons and has a height corresponding to the short-side length (i.e., width) of the soft magnetic metal ribbons, and each of which is arranged side by side at intervals in the height direction.

[0022] That is, the magnetic core of this embodiment is configured by stacking multiple individually manufactured magnetic lamination pieces (laminated cores) in the height direction, with the magnetic lamination pieces spaced apart. This configuration reduces eddy currents generated inside the core, allowing high magnetic permeability to be maintained even in high-frequency bands of 1 MHz or higher. This configuration also blocks magnetic interactions between the magnetic lamination pieces, further suppressing impedance reduction in the high-frequency range. Therefore, the magnetic core of this embodiment has a high impedance-to-permeability ratio in the high-frequency range, even when the height dimension is increased, without the need for an increase in overall size.

[0023] Furthermore, due to the above-described effects, the magnetic core of this embodiment can be suitably used in the high frequency range, specifically in a frequency band of 1 MHz or higher. In other words, the frequency of the usage environment of the magnetic core of this embodiment is suitably 1 MHz or higher. In particular, when the magnetic core of this embodiment is used in a frequency band of 10 MHz or higher, even greater effects are achieved.

[0024] The magnetic core of this embodiment (or the multiple magnetic laminate pieces that make up the magnetic core) may be housed in a core case. The material of the core case is not particularly limited, and examples include PBT (polybutylene terephthalate), PA (polyamide), PPS (polyphenylene sulfide), ABS (acrylonitrile butadiene styrene), ASA (acrylonitrile styrene acrylic rubber), silicone resin, and silicone elastomer. By housing the magnetic core in the core case, it is possible to protect the magnetic core from external factors such as vibration, impact, and water exposure.

[0025] In the magnetic core of this embodiment, adjacent magnetic lamination pieces may be spaced apart by providing a gap therebetween, or by the interposition of any member. Simply providing a gap can be considered as the presence of an air layer with high electrical resistance, and high magnetic permeability can be maintained in the high frequency band. On the other hand, when providing a gap by the interposition of any member, for example, a resin material may be applied to the opposing surfaces of each magnetic lamination piece (surfaces formed by the longitudinal sides of the soft magnetic metal ribbon), or a plate material may be inserted between each magnetic lamination piece. Furthermore, adjacent magnetic lamination pieces may be integrated by being fixed with a fixture or adhesive, or may be independent without being fixed.

[0026] Furthermore, when spacing is achieved by using an optional intervening member, it is preferable to use a material with high electrical resistance as the member. By spacing each magnetic laminated piece using a material with high electrical resistance, eddy currents generated inside the core are effectively reduced, allowing high magnetic permeability to be maintained even in the high frequency band. Examples of such materials include resin materials such as acrylic resins, epoxy resins, polyethylene resins, polyimide resins, silicone resins, and silicone elastomers. The resin materials may also contain fibers such as glass or cellulose, or particles such as beads. The member may also be insulating paper made of cellulose fibers or the like.

[0027] Alternatively, when resin is impregnated between layers of the soft magnetic metal ribbons of the magnetic laminated pieces (as described later), the resin may be attached to the surface of the magnetic laminated pieces (the surface formed by the longitudinal sides of the soft magnetic metal ribbons) and then solidified and molded in that state to form the above-mentioned gap. In the magnetic core using the magnetic laminated pieces obtained in this case, a gap is formed between adjacent magnetic laminated pieces due to the presence of the resin used for impregnation.

[0028] Alternatively, to form the above-mentioned gaps, the core case may be provided with partitions or protrusions, and the magnetic lamination pieces may be housed in the core case. In this case, the adjacent magnetic lamination pieces in the magnetic core are spaced apart by the partitions or protrusions of the core case.

[0029] In the magnetic core of this embodiment, the spacing (p) between adjacent magnetic lamination pieces may be greater than 0, but is preferably 0.02 mm or greater. If the spacing (p) is 0.02 mm or greater, the magnetic lamination pieces are sufficiently insulated, more effectively suppressing eddy currents generated inside the core. Furthermore, the magnetic interactions between the magnetic lamination pieces are more effectively blocked, suppressing a decrease in impedance relative permeability in the high-frequency range of 1 MHz or greater. From the same perspective, the spacing (p) between adjacent magnetic lamination pieces is more preferably 0.1 mm or greater, and even more preferably 1.0 mm or greater. In particular, if the spacing is 0.1 mm or greater, a decrease in impedance in the high-frequency range of 100 MHz or greater can be more effectively suppressed. On the other hand, while there is no particular upper limit for the spacing, an excessively large spacing increases the overall dimensions of the magnetic core, so there is no need to leave an unnecessary spacing. From this perspective, the spacing is preferably, for example, 20 mm or less.

[0030] The magnetic core of this embodiment includes a plurality of magnetic lamination pieces, i.e., the number of magnetic lamination pieces may be two or more. In particular, the number of magnetic lamination pieces may be, for example, three or more, five or more, or eight or more. Meanwhile, the upper limit of the number of magnetic lamination pieces is not particularly limited, but may be, for example, 120 or less, 100 or less, or 80 or less.

[0031] <Soft magnetic metal ribbon> The soft magnetic metal ribbon is a component constituting the magnetic laminated piece. In this embodiment, a soft magnetic metal ribbon having a length (width) in the short side direction corresponding to the height (h) of the magnetic laminated piece to be fabricated can be used.

[0032] Examples of soft magnetic metals include Fe-Ni based alloys (permalloys), Fe-Si based alloys (silicon steel), amorphous alloys such as Co-based amorphous alloys and Fe-based amorphous alloys, and Fe-based nanocrystalline alloys. In particular, the soft magnetic metal ribbon preferably contains an Fe-based nanocrystalline alloy. Note that the Fe-based nanocrystalline alloy can be obtained, for example, by heat-treating an Fe-based amorphous alloy to precipitate nanocrystals inside.

[0033] When the soft magnetic metal ribbon contains an amorphous alloy or an Fe-based nanocrystalline alloy, such an alloy may be, for example, an 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 metal 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 satisfy the following relationships: 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, respectively.

[0034] The composition of the Fe-based nanocrystalline alloy is not particularly limited, but is preferably, in atomic percent, Cu: 0.5-2.0%, Nb: 1.0-5.0%, Si: 11.0-15.0%, B: 5.0-10.0%, with the remainder being substantially Fe, provided that the properties of the present disclosure can be satisfied.

[0035] When the soft magnetic metal ribbon includes an amorphous alloy or an Fe-based nanocrystalline alloy, the thickness of the soft magnetic metal ribbon can be, for example, 10 μm or more and 30 μm or less. If the thickness of the soft magnetic metal ribbon is 10 μm or more, it is possible to suppress a decrease in strength due to the occurrence of voids or discontinuous portions on the ribbon surface, and to suppress the occurrence of deformation or breakage during lamination or winding, thereby suppressing a decrease in magnetic permeability. Furthermore, if the thickness of the soft magnetic metal ribbon is 30 μm or less, it is possible to achieve a sufficient cooling rate to form a uniform amorphous layer and prevent a decrease in magnetic permeability. From the same viewpoint, the thickness of the soft magnetic metal ribbon is more preferably 12 μm or more, even more preferably 14 μm or more, more preferably 25 μm or less, and even more preferably 20 μm or less.

[0036] <Magnetic laminate piece> The magnetic laminated piece is formed by laminating soft magnetic metal ribbons. The magnetic laminated piece has a height (h) corresponding to the length of the soft magnetic metal ribbons in the short-side direction. Such a magnetic laminated piece can be produced, for example, by bundling or winding up soft magnetic metal ribbons (metal foils) having a substantially constant length (width) in the short-side direction in a predetermined size and shape into a roll (cylindrical shape).

[0037] The laminated soft magnetic metal ribbons 2 (metal foils) are preferably heat-treated to remove distortions that may occur during molding. In other words, the magnetic laminated pieces are preferably obtained by heat-treating laminated soft magnetic metal ribbons. When using soft magnetic metal ribbons containing an amorphous alloy, nanocrystals can be precipitated inside 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.

[0038] Each magnetic laminate used in this embodiment may have, for example, an annular structure. Such an annular structure can also be referred to as a "tubular structure," especially when the magnetic laminate has a certain height (h) or more. By arranging magnetic laminate pieces having an annular structure side by side at intervals in the height direction, the magnetic core can also have an annular structure and a central axis. Furthermore, in such a magnetic core, the height direction of the magnetic laminate pieces and the direction parallel to the central axis of the annular structure are approximately the same. Examples of annular structures include a circular annular structure (the cross section perpendicular to the central axis direction is circular) or a structure substantially equivalent thereto, a rounded polygonal annular structure (the cross section perpendicular to the central axis direction is rounded polygonal) or a structure substantially equivalent thereto, etc. Furthermore, examples of the annular structure include a perfect circular annular structure (the cross section perpendicular to the central axis direction is perfect circular) and an elliptical annular structure (the cross section perpendicular to the central axis direction is elliptical). Another example is a "racetrack shape," which is similar to the "elliptical ring structure" but differs from the "elliptical ring structure" in that it includes straight portions.

[0039] The magnetic laminated piece having an annular structure can be produced by winding a soft magnetic metal ribbon. When the magnetic laminated piece having an annular structure is produced by winding a soft magnetic metal ribbon, the soft magnetic metal ribbons are stacked in the radial direction in the magnetic laminated piece.

[0040] Alternatively, each magnetic laminated piece used in this embodiment may have a structure in which a part of the above-mentioned annular structure is cut out, or may have a U-shaped structure.

[0041] Each magnetic lamination piece used in this embodiment preferably has a height (h) of 0.5 mm or more and 20 mm or less. In other words, the short-side length (width) of the soft magnetic metal ribbon used in each magnetic lamination piece is preferably 0.5 mm or more and 20 mm or less. If the height (h) of each magnetic lamination piece is 0.5 mm or more, the soft magnetic metal ribbon and, by extension, each magnetic lamination piece can be manufactured more easily. Furthermore, the proportion of the processed surface in the entire ribbon is reduced, thereby suppressing a decrease in impedance relative permeability due to stress and distortion caused by processing, and coarsening of the structure caused by processing heat generated during processing. Furthermore, if the height (h) of each magnetic lamination piece is 20 mm or less, eddy currents generated inside the core can be more effectively suppressed, thereby suppressing a decrease in impedance relative permeability in the high-frequency range of 1 MHz or more. In particular, if the height (h) of each magnetic lamination piece is 15 mm or less, a decrease in impedance in the high-frequency range of 100 MHz or more can be more effectively suppressed. Furthermore, when resin is impregnated between the layers of the soft magnetic metal ribbons of the magnetic laminated pieces (described later), if the height (h) of each magnetic laminated piece is 20 mm or less, the resin can easily penetrate deep into the core, effectively suppressing distortion of the ribbons inside the core and, ultimately, a decrease in the impedance relative permeability. From the same perspective, it is even more preferable that the height (h) of each magnetic laminated piece is 10 mm or less.

[0042] When each magnetic lamination piece used in this embodiment has a circular structure, each magnetic lamination piece 1 has an average magnetic path length L m (mm), height is h (mm), and radial thickness is t (mm), L m The coefficient Cs calculated by / (h·t) is 90.0 mm -1 It is preferable that the coefficient Cs is 90.0 mm or less. -1 If the coefficient Cs is less than 50.0 mm, the rigidity of the magnetic core is maintained and deformation due to its own weight or handling is unlikely to occur, so that the decrease in impedance relative permeability can be effectively suppressed. -1 It is more preferable that it is 10.0 mm or less. -1On the other hand, the lower limit of the coefficient Cs is set to 1.5 mm in order to reduce the height h and increase the impedance relative permeability in the high frequency range. -1 It is preferable that it is 2.6 mm or more. -1 More preferably, it is equal to or greater than this. In addition, the average magnetic path length L m is the outer diameter of the magnetic core, OD is the inner diameter, ID is the height, and h is the m =π(OD+ID) / 2.

[0043] Each magnetic laminate piece used in this embodiment may be an integrated piece as shown in Fig. 1. Alternatively, each magnetic laminate piece used in this embodiment may be configured as a split magnetic laminate piece made up of two or more laminate parts (not shown). Specifically, for example, when the magnetic laminate piece has an annular structure, the magnetic laminate piece may be configured as a split core (split magnetic laminate piece) split into at least two or more pieces in the circumferential direction to improve ease of attachment to a cable.

[0044] Furthermore, for example, when the magnetic lamination pieces have an annular structure, the magnetic lamination pieces may be configured to have discontinuous portions that are interrupted in the circumferential direction (not shown). Furthermore, in a magnetic core using a plurality of magnetic lamination pieces having such discontinuous portions, it is preferable that the discontinuous portions of adjacent magnetic lamination pieces do not overlap when viewed in the central axis direction (particularly, that they do not have overlapping portions).

[0045] 2, the magnetic laminated piece used in the magnetic core of this embodiment preferably has resin (impregnated resin in an impregnated state) 3 between the layers of the soft magnetic metal ribbons 2. By impregnating the resin 3 between the layers of the soft magnetic metal ribbons 2 of the magnetic laminated piece 1, the soft magnetic metal ribbons 2 can be fixed and their shape can be maintained.

[0046] Examples of the impregnating resin 3 that can be used include acrylic resins, epoxy resins, polyimide resins, silicone resins, and silicone elastomers. The glass transition temperature of the impregnating resin 3 is preferably 85°C or higher. Recently, products using magnetic cores have become increasingly popular for electric vehicles, and the operating temperature environment is becoming higher due to increased speed and power output. Therefore, the impregnating resin used to solidify and mold the magnetic laminated pieces is also required to have high heat resistance. In this regard, a glass transition temperature of 85°C or higher, which is one indicator of heat resistance, can improve heat resistance. Furthermore, a glass transition temperature of 85°C or higher can prevent dimensional changes and a decrease in adhesive strength of the impregnating resin 3 due to aging in a high-temperature environment, thereby facilitating the fixation of the soft magnetic metal ribbon 2 and maintaining a stable shape. Furthermore, time-dependent distortion within the soft magnetic metal ribbon 2 can be prevented, thereby suppressing a decrease in magnetic permeability. From the same viewpoint, the glass transition temperature of the impregnating resin 3 is more preferably 125° C. or higher, even more preferably 130° C. or higher, and even more preferably 150° C. or higher. In particular, the impregnating resin 3 is preferably an epoxy resin, which can adjust the glass transition temperature by changing the curing agent, has low viscosity before curing, and has high adhesive strength with the soft magnetic metal ribbon 2 after curing.

[0047] When the magnetic laminated piece 1 has resin (impregnated resin in an impregnated state) 3 between the layers of the soft magnetic metal ribbons 2, the filling rate of the soft magnetic metal ribbons in the magnetic laminated piece can be adjusted by the binding force when bundling the soft magnetic metal ribbons and the tension when winding them up, and can be adjusted to a range of 65 vol% to 85 vol%, for example. If the filling rate of the soft magnetic metal ribbons in the magnetic laminated piece is 65 vol% or more, the proportion of the magnetic material does not become too small, which effectively prevents a decrease in magnetic permeability and allows the volume of the magnetic laminated piece 1 to be reduced. On the other hand, if the filling rate of the soft magnetic metal ribbons in the magnetic laminated piece is 85 vol% or less, which prevents the interlayer distance d of the soft magnetic metal ribbons 2 from becoming too small, which allows the impregnated resin 3 to sufficiently penetrate between the layers of the soft magnetic metal ribbons 2, making it easier to solidify and mold.

[0048] In the case where the magnetic laminated piece 1 has resin (impregnated resin) 3 between the layers of the soft magnetic metal ribbons 2, the total interlayer distance d of the soft magnetic metal ribbons 2 is S, and the average interlayer distance d of the soft magnetic metal ribbons 2 is d ave The average interlayer distance between the layers of the soft magnetic metal ribbon 2 is d ave When the total interlayer distance between layers is S4, which is four or more times the total distance between layers, the ratio R4 = S4 / S of the total S to the total S is preferably 10.0% or less. When a highly heat-resistant impregnating resin 3 (e.g., an impregnating resin 3 having a glass transition temperature of 85°C or higher) is impregnated into a magnetic laminate piece (before impregnation), if the glass transition temperature of the resin is high, the viscosity generally tends to be high. In this case, there is a concern that the soft magnetic metal ribbon 2 is particularly susceptible to distortion due to expansion and deformation of the interlayer spaces between the soft magnetic metal ribbons 2, resulting in large thermal shrinkage during curing, and as a result, the magnetic permeability is reduced. In this regard, in consideration of heat resistance, even when an impregnating resin 3 having a high glass transition temperature as described above is used, distortion of the soft magnetic metal ribbons 2 can be suppressed by setting the ratio R4 = S4 / S to 10.0% or less, thereby achieving high magnetic permeability of the magnetic laminate piece 1. That is, by setting the ratio R4=S4 / S to 10.0% or less, it is possible to achieve both good heat resistance and good magnetic permeability. From the same viewpoint, it is more preferable that the ratio R4=S4 / S is 5.0% or less.

[0049] The interlayer distance of the soft magnetic metal ribbons 2 in the magnetic lamination piece 1 can be measured using an optical microscope by observing the surface (the surface formed by the longitudinal sides of the soft magnetic metal ribbons) of the magnetic lamination piece 1. Specifically, the measurement can be performed according to the procedures described in the Examples.

[0050] The viscosity of the impregnating resin 3 when impregnating the spaces between the layers of the soft magnetic metal ribbon 2 is preferably 2000 mPa·s or less. By impregnating the resin 3 at a relatively low viscosity as described above, it is possible to prevent the impregnating resin 3 from insufficiently penetrating between the layers of the soft magnetic metal ribbon 2 or from excessively penetrating between the layers of the soft magnetic metal ribbon 2, thereby suppressing a decrease in magnetic permeability due to distortion of the soft magnetic metal ribbon 2. Furthermore, by impregnating the resin at a relatively low viscosity as described above, it is possible to achieve a favorable ratio R4 = S4 / S. When using a highly viscous impregnating resin 3, it is preferable to adjust the viscosity by adjusting the temperature or adding a diluent such as an organic solvent. From the same viewpoint, it is more preferable that the viscosity of the impregnating resin 3 when impregnating the spaces between the layers of the soft magnetic metal ribbon 2 be 550 mPa·s or less.

[0051] The impregnation with the impregnation resin 3 is preferably performed by heating the uncured impregnation resin 3 to room temperature to 80°C, setting the impregnation pressure to normal pressure or reduced pressure (-0.05 MPaG), and immersing the magnetic laminate piece before impregnation for 10 to 60 minutes. The temperature can be adjusted depending on the viscosity of the impregnation resin 3 used. By setting the impregnation pressure to -0.05 MPaG or higher, the interlayer spaces of the soft magnetic metal ribbon 2 are expanded or deformed, preventing excessive penetration, thereby suppressing distortion of the soft magnetic metal ribbon 2 and reducing the magnetic permeability. Furthermore, by setting the impregnation pressure to -0.05 MPaG or higher, the ratio R4 = S4 / S can be made favorable. It is more preferable to set the impregnation pressure to normal pressure. During the immersion, the impregnation liquid can be swung, convected, or vibrated to efficiently remove air bubbles generated between the layers of the soft magnetic metal ribbon 2. Furthermore, if it is difficult to impregnate the soft magnetic metal ribbon 2 (metal foil), it is preferable to apply an organic or inorganic adhesive to the surface before laminating the soft magnetic metal ribbon 2 (metal foil).

[0052] After being impregnated with the impregnating resin 3, the magnetic laminated piece 1 can be subjected to a heat treatment to harden the impregnating resin 3. The temperature and time of the heat treatment must be set to appropriate conditions depending on the resin used, but for example, the heat treatment temperature can be 50 to 200°C and the heat treatment time can be 0.5 to 10 hours. Alternatively, the heat treatment can be performed stepwise in multiple steps starting from a low temperature.

[0053] (Noise filter) A noise filter according to one embodiment of the present invention (hereinafter sometimes referred to as the "noise filter of this embodiment") is characterized by including the magnetic core of the above embodiment. The noise filter of this embodiment uses a magnetic core that has a high impedance relative permeability in the high frequency range, and therefore has a high noise suppression effect in the high frequency range. As a result, it can be attached to power cables or bus bars of electronic devices such as automobiles, power generation and power supply equipment, communication equipment, and office automation / factory automation equipment, and can be used as a noise filter to suppress noise generated within these electronic devices or noise generated externally and propagating within the cables or bus bars. [Example]

[0054] The present invention will be described in more detail below with reference to examples. However, these examples are intended to illustrate the present invention and are not intended to limit the present invention in any way.

[0055] Example 1: Magnetic Laminate Spacing Data A magnetic laminated piece was produced by laminating soft magnetic metal ribbons according to the following procedure. First, a molten alloy containing, in atomic percent, 1% Cu, 3% Nb, 13.5% Si, and 9% B, with the remainder essentially composed of Fe, was quenched by a single-roll process to obtain a ribbon-shaped Fe-based amorphous alloy (Fe-based amorphous alloy ribbon) having a width (short length) of 15 mm and a thickness of 15 μm. Next, the Fe-based amorphous alloy ribbon was wound (laminated) into a cylindrical shape to obtain a ring-shaped Fe-based amorphous alloy having an outer diameter of 37.0 mm, an inner diameter of 25.0 mm, and a height of 15 mm. The ring-shaped Fe-based amorphous alloy was placed in a heat treatment furnace maintained at 600°C under an argon atmosphere and heat-treated for 30 minutes to precipitate nanocrystals inside the Fe-based amorphous alloy, producing a magnetic laminated piece (before impregnation) in which the soft magnetic metal ribbon contained an Fe-based nanocrystalline alloy. The obtained magnetic laminated piece (before impregnation) was immersed for 20 minutes under normal pressure in a solution of epoxy resin base and curing agent mixed in a specified ratio and kept at 50°C, thereby impregnating the magnetic laminated piece (before impregnation) with the resin.The resin was then hardened by heat treatment in air at 180°C for 8 hours, producing magnetic laminated pieces (magnetic laminated piece 1A and magnetic laminated piece 1B) with a height of 15 mm and having a circular ring structure.

[0056] For the fabricated magnetic laminated pieces, the interlayer distance of the soft magnetic metal ribbon (Fe-based nanocrystalline alloy ribbon) was measured on the surface of the magnetic laminated piece (the surface formed by the longitudinal edges of the soft magnetic metal ribbon). Specifically, the surface of the fabricated magnetic laminated piece was polished with #500 to #2000 abrasive paper, and the interlayer distance of the soft magnetic metal ribbon was measured from an image observed at 500x objective magnification using a Hirox digital microscope RH-2000. The measurement of the interlayer distance of the soft magnetic metal ribbon was performed by observing in one line in the thickness direction of the soft magnetic metal ribbon from the inner periphery to the outer periphery of the magnetic laminated piece, covering 90% of the thickness t of the magnetic laminated piece (45% radially inward and 45% radially outward from the radial center position) (see Figure 3). The observation locations were three lines (three radial lines) equally spaced 120° circumferentially (see Figure 4), and the average interlayer distance d of the soft magnetic metal ribbon was measured. ave Based on the obtained interlayer distances of the soft magnetic metal ribbons, the average interlayer distance d of the soft magnetic metal ribbons with respect to the total interlayer distance S of the soft magnetic metal ribbons was calculated.ave More than four times (4d ave The ratio S4 / S×100(%) of the total interlayer distance S4 of the soft magnetic metal ribbons (above) was calculated. As a result, the ratio R4=S4 / S was 10.0% or less for all of the produced magnetic laminate pieces.

[0057] Furthermore, the impedance Z1 of the magnetic laminate piece 1A was measured at frequencies of 1 MHz, 10 MHz, and 100 MHz. Similarly, the impedance Z2 of the magnetic laminate piece 1B was measured at frequencies of 1 MHz, 10 MHz, and 100 MHz. The impedance measurements were performed using a Keysight 4294A impedance analyzer. Using a lead wire measurement fixture (16047E), a Tanaka Electric Wire H-PCV, 0.5 mm diameter, single lead wire was passed through the magnetic laminate piece, and the impedances Z1 and Z2 were measured in one turn. Furthermore, the sum of Z1 and Z2, Z, was measured at frequencies of 1 MHz, 10 MHz, and 100 MHz. sum asked for.

[0058] Next, magnetic laminate pieces 1A and 1B were arranged in contact with each other in the height direction (0 mm spacing) or at predetermined intervals (0.02 mm, 0.04 mm, 0.10 mm, 0.20 mm, 0.50 mm, 1.00 mm, 2.00 mm) (8 points in total) to prepare a magnetic core. The impedance Z of the magnetic core at frequencies of 1 MHz, 10 MHz, and 100 MHz was measured. meas was measured in the same manner as above. meas / Z sum (%) was calculated.

[0059] Figure 5 shows the Z at each frequency as a function of the spacing between the magnetic laminations. meas / Z sum The plot of Z is shown. meas is the sum of Z of each magnetic laminated piece, Z sumIdeally, the impedance should be equal to the impedance of the magnetic laminated pieces. However, when the magnetic laminated pieces were in contact with each other without any spacing, the impedance remained at around 80-85%. This is thought to be due to the increase in eddy currents and magnetic coupling caused by the contact between the two magnetic laminated pieces in the height direction. Since the loss due to eddy currents increases with frequency, the impedance is lower at 100 MHz compared to 1 MHz and 10 MHz. In contrast, when the magnetic laminated pieces were spaced apart in the height direction, specifically at a spacing of 0.02 mm, the impedance improved significantly, reaching approximately 99% at 1 MHz and 10 MHz and approximately 93% at 100 MHz. When the spacing between the magnetic laminated pieces was further increased, there was little change at 1 MHz and 10 MHz, but at 100 MHz, the impedance improved to 95% at spacings of 0.10 mm or more.

[0060] Example 2: Magnetic Laminate Height Data Except for using an Fe-based amorphous alloy ribbon having a width (length in the short direction) selected from 0.3 to 30.0 mm, a circular Fe-based amorphous alloy having an outer diameter of 37.0 mm, an inner diameter of 25.0 mm, and a height of 0.3 to 30.0 mm was obtained in the same manner as in Example 1. Next, a magnetic laminated piece having a circular structure and a height (h) selected from 0.3 to 30.0 mm was produced in the same manner as in Example 1.

[0061] The interlayer distance of the soft magnetic metal ribbon (Fe-based nanocrystalline alloy ribbon) of the prepared magnetic laminated piece was measured according to the same procedure as in Example 1. All of the magnetic laminated pieces used in the invention examples had a ratio R4 = S4 / S of 10.0% or less.

[0062] The magnetic laminate pieces produced were selected and used so that the total height dimension (h x number) was 30 mm, as shown in Table 1, and the magnetic laminate pieces were arranged side by side in the height direction, with a 0.02 mm gap (p) between them by sandwiching a 0.02 mm thick polyethylene film. In this way, the magnetic cores of each example were produced (the dimensions of the magnetic core, such as the outer diameter and inner diameter, were the same as those of the magnetic laminate pieces).

[0063] For the magnetic cores of each example produced, the impedance Z was measured at frequencies of 1 MHz, 10 MHz, and 100 MHz in the same manner as in Example 1, and the impedance Z was converted into impedance relative permeability (μrz). The results are shown in Table 1.

[0064] The conversion from impedance Z to impedance relative permeability (μrz) is μrz=Z×L m / (2πμ0f×Ae), where μ0 is the magnetic permeability of a vacuum, L m is the average magnetic path length, f is the measurement frequency, and Ae is the effective cross-sectional area. m Regarding the effective cross-sectional area Ae, when the outer diameter of the magnetic core is OD, the inner diameter is ID, and the height is h, L m =π(OD+ID) / 2, Ae=(OD-ID)×h / 2×dr. dr is the packing rate of the magnetic material (soft magnetic metal ribbon), and is the density d (g / cm) calculated from the volume and weight of the magnetic laminated piece. 3 ) with a theoretical density of 7.3 (g / cm 3 ) and in this case it was 0.75 (75 vol%).

[0065] [Table 1]

[0066] Table 1 shows that the magnetic cores of Examples 2-1 to 2-8, in which multiple magnetic laminate pieces are arranged side by side with gaps in the height direction, all have high relative permeability to impedance (μrz) at frequencies of 1 MHz, 10 MHz, and 100 MHz. On the other hand, the magnetic core of Comparative Example 2-1, which has a height of 30.0 mm and is made of a single magnetic laminate piece, had a low relative permeability to impedance. This is thought to be due to an increase in eddy currents and distortion of the ribbon during resin impregnation.

[0067] Furthermore, from Examples 2-1 to 2-7 in Table 1, it can be seen that within the range of 0.5 to 20 mm in height of the magnetic laminated pieces used, the smaller the height dimension, the higher the impedance relative permeability (μrz) in the high frequency range of 1 MHz or higher. This is because the smaller the height dimension, the smaller the eddy current. On the other hand, Example 2-8, which used magnetic laminated pieces with a height dimension of 0.3 mm, exhibited characteristics similar to those of Example 2-2 with a height dimension of 15.0 mm, and the effect of reducing the height dimension was reduced. This is thought to be due to deterioration of the material during manufacturing or deformation of the magnetic laminated pieces.

[0068] (Example 3: Data on various dimensions of toroidal magnetic laminated pieces) Magnetic laminated pieces having a circular ring structure (toroidal shape) were produced in the same manner as in Example 2, with various conditions such as dimensions being changed as appropriate.

[0069] The interlayer distance of the soft magnetic metal ribbon (Fe-based nanocrystalline alloy ribbon) of the prepared magnetic laminated piece was measured according to the same procedure as in Example 1. All of the magnetic laminated pieces used in the invention examples had a ratio R4 = S4 / S of 10.0% or less.

[0070] The magnetic laminate pieces produced were selected and used so that the total height dimension (h x number) was 30 mm, as shown in Table 2, and the magnetic laminate pieces were arranged side by side in the height direction, with a 0.02 mm gap (p) between them by sandwiching a 0.02 mm thick polyethylene film. In this way, the magnetic cores of each example were produced (the dimensions of the magnetic core, such as the outer diameter and inner diameter, were the same as those of the magnetic laminate pieces).

[0071] For the magnetic cores of each example produced, the impedance Z was measured at frequencies of 1 MHz, 10 MHz, and 100 MHz in the same manner as in Example 2, and the impedance Z was converted into impedance relative permeability (μrz). The results are shown in Table 2.

[0072] [Table 2]

[0073] From Table 2, it can be seen that the smaller the height dimension of the magnetic laminated pieces used in Example 2 (Table 1), the higher the impedance relative permeability (μrz) in the high frequency range of 1 MHz or higher, was a tendency that was also observed in Example 3. In other words, it can be seen that this tendency also applies to magnetic cores with various dimensions.

[0074] Example 4: Data on various dimensions of racetrack-shaped magnetic laminated pieces A toroidal Fe-based amorphous alloy strip was obtained in the same manner as in Example 1, except that a thin Fe-based amorphous alloy ribbon having a predetermined dimension was used. Next, the toroidal Fe-based amorphous alloy strip was fixed with a jig to the predetermined dimension and placed in a heat treatment furnace maintained at 600°C under an argon atmosphere. Heat treatment was performed for 30 minutes to produce a racetrack-shaped magnetic laminate piece (before impregnation). The obtained magnetic laminate piece (before impregnation) was immersed for 20 minutes under normal pressure in a solution containing a specified ratio of epoxy resin base and curing agent, which was kept at 50°C, to impregnate the magnetic laminate piece (before impregnation) with the resin. The resin was then cured by heat treatment at 180°C in the atmosphere for 8 hours, producing a racetrack-shaped magnetic laminate piece.

[0075] The interlayer distance of the soft magnetic metal ribbon (Fe-based nanocrystalline alloy ribbon) of the prepared magnetic laminated piece was measured according to the same procedure as in Example 1. All of the magnetic laminated pieces used in the invention examples had a ratio R4 = S4 / S of 10.0% or less.

[0076] The magnetic laminate pieces produced were selected and used so that the total height dimension (h x number) was 30 mm, as shown in Table 3, and the magnetic laminate pieces were arranged side by side in the height direction, with a 0.02 mm gap (p) between them by sandwiching a 0.02 mm thick polyethylene film. In this way, the magnetic cores of each example were produced (the dimensions of the magnetic core, such as the outer diameter and inner diameter, were the same as those of the magnetic laminate pieces).

[0077] For the magnetic cores of each example produced, the impedance Z was measured at frequencies of 1 MHz, 10 MHz, and 100 MHz in the same manner as in Example 2, and the impedance Z was converted into impedance relative permeability (μrz). The results are shown in Table 3.

[0078] [Table 3]

[0079] From Table 3, even when the magnetic laminated piece has an elliptical ring structure, as in Example 2 (Table 1) and Example 3 (Table 2), it was observed that the smaller the height dimension of the magnetic laminated piece used, the higher the impedance relative permeability (μrz) in the high frequency range above 1 MHz.

[0080] The impedance Z of the magnetic core of Example 4-18 and the magnetic core of Comparative Example 4-3 was measured at 10 kHz and 100 kHz, and the frequency characteristics of the impedance Z are shown in Figure 6. Although the magnetic core of Example 4-18 and the magnetic core of Comparative Example 4-3 have the same volume, Figure 6 shows a difference between Example 4-18 and Comparative Example 4-3 from 100 kHz onwards, and the difference becomes larger as the frequency increases. It can be seen that in the high frequency range above 1 MHz, the impedance Z of Example 4-18 is significantly higher than that of Comparative Example 4-3. In other words, a magnetic core obtained by using multiple magnetic laminate pieces with small height dimensions and arranging them at intervals in the height direction has a higher impedance Z than a magnetic core of the same volume, and it is thought that this difference becomes particularly large in the high frequency range above 1 MHz.

[0081] As described above, according to the present invention, the performance of magnetic cores used at high frequencies is improved, and it is possible to reduce the volume and weight, which is expected to lead to the miniaturization and weight reduction of components. Note that the dimensions and shapes of the magnetic laminated pieces and magnetic cores shown in the above examples are merely examples, and are not limited to these, as they can be adapted to various dimensions and shapes. [Industrial Applicability]

[0082] The magnetic core of the present invention can be attached to the power cables or bus bars of electronic devices such as automobiles, power generation / power supply equipment, communication equipment, and office / factory equipment, and can be used as a noise filter to suppress noise generated within these electronic devices or noise generated externally and propagating through the cables. [Explanation of symbols]

[0083] 1 Magnetic laminate piece 2 Soft magnetic metal ribbon 3 Resin (impregnated resin) 10 Magnetic Core

Claims

1. A magnetic core comprising a plurality of magnetic laminations, the magnetic laminated piece is formed by laminating soft magnetic metal ribbons, and has a height corresponding to the length of the soft magnetic metal ribbons in the short side direction, A magnetic core, characterized in that the magnetic laminated pieces are arranged side by side at intervals in the height direction.

2. 2. The magnetic core according to claim 1, wherein the interval between adjacent magnetic lamination pieces is 0.02 mm or more.

3. The magnetic core according to claim 1 or 2, wherein the height of each of the plurality of magnetic laminated pieces is 0.5 mm or more and 20 mm or less.

4. Each of the plurality of magnetic laminated pieces has an annular structure and an average magnetic path length of L ｍ (mm), the height is h (mm), and the thickness in the radial direction is t (mm), L ｍ The coefficient Cs calculated by / (h t) is 90.0 mm －１ 3. The magnetic core according to claim 1, wherein:

5. The magnetic core according to claim 1 or 2, wherein the soft magnetic metal ribbon contains an Fe-based nanocrystalline alloy.

6. The magnetic core according to claim 1 or 2, which is used in a frequency band of 1 MHz or more.

7. A noise filter comprising the magnetic core according to claim 1 or 2.

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