JP2000503169A - Distributed gap electric choke - Google Patents

Abstract

(57) [Summary] An electric choke includes a magnetic core having a distribution gap. The magnetic core is composed of a rapidly solidified iron-based metal alloy. The structure of the distribution gap is generated by an annealing process that causes partial crystallization of the amorphous alloy. As a result of this annealing treatment, the magnetic core has a permeability in the range of 100 to 400, low core loss (ie, less than 70 W / kg at 100 kHz and 0.1 T), and excellent DC bias behavior (at least 40%). The initial permeability is maintained at 3,980 A / m or a DC bias field of 50 Oe).

Description

DETAILED DESCRIPTION OF THE INVENTION                           Distributed gap electric choke                                  Background of the Invention 1. Field of the invention   The present invention relates to an amorphous metal magnetic core for an electric choke having a distribution gap. More specifically, the amorphous core is annealed and separated into the amorphous core. A method for forming a fabric gap.2. Description of the prior art   An electric choke is an energy storage inductor. Toroidal inductor , The stored energy W is W = １ ／ [(B^TwoA_cl_m) / (2μ₀μ_r )], Where B is the magnetic flux density and A_cIs the effective magnetic area of the core, l_mIs flat Uniform flux path length, μ₀Is the permeability of free space, μ_rIs the relative permeability of the material .   When a small air gap is introduced into the toroid, the magnetic flux in such an air gap Remain the same as the magnetic flux of the ferromagnetic core material. However, the permeability of air (Μ〜1) is significantly smaller than the magnetic permeability (μ〜thousands) of typical ferromagnetic materials Therefore, the magnetic field strength (H) of the gap is much higher than the magnetic field strength of the rest of the core. (H = B / μ). The energy W per unit volume stored in the magnetic field is W = １ ／ (B / H), such energy is mainly due to the air gap To be concentrated on In other words, the energy storage capacity of the core is Can be increased by the introduction of a tip. The gap is discrete. ) Or distributed. Giant distributed Gap or distribution gap uses ferromagnetic powder bound with a non-magnetic binder Or by partially crystallizing the amorphous alloy. Can be introduced. By partially crystallizing the amorphous alloy When a gap is introduced, the ferromagnetic crystal phase separates Wrapped in The mechanism of this partial crystallization is related to the chalk of the present invention. Used.   Electric choke based on the principle of annealing and treating an amorphous core of Fe base is No. 2,117,979A and U.S. Pat. No. 4,812,181. It is described in. The above-mentioned U.S. Pat. Long-time (10 hours or more) annealing at a temperature higher than 410 ° C. A method for obtaining a flat magnetized loop by applying a process is disclosed. Have been. This method, disclosed in the above-mentioned U.S. patent, uses an amorphous ribbon display. Providing a step of crystallizing the surface and thereby stressing the amorphous of the ribbon. I have.   In the above-mentioned British Patent No. 2,117,979A, the electric choke comprises an Fe-based It is formed based on the heat treatment of the amorphous core of the material. The maximum permeability is Reduced to 1/50 to 1/30 of its initial value (with a maximum permeability of 40,000) Then, the above process produces a value in the range of about 800 to 1,300). Rufascore indicates a certain degree of crystallization not exceeding 10% of its volume.   When applied to power supplies for notebook computers and other small devices, With small permeability (100-300), very low core loss and saturation magnetizability In addition, extremely small electrical chokes that can withstand high DC bias magnetic fields Needed.                                  Summary of the Invention   The present invention provides a magnetic permeability in the range of 100 to 400 and low iron loss (100 kHz and Range from about 8 mm to 45 mm (OD) with less than 70 W / kg at 0.1 T) Provide an electric choke of dimensions. Its magnetic properties are maintained under DC bias. (At least 40% of the initial permeability is 3,980 A / m or 50 Oe DC (Maintained under a bias electric field).   In addition, heat treatment is performed in a state where the amorphous alloy of the Fe base material is controlled, A method to partially crystallize the ribbon body to create a small gap in the core A method is provided by the present invention. As a result of the distribution gap, the above characteristics are obtained. Can be   More specifically, according to the present invention, a unique trade-off between the degree of crystallization and the magnetic permeability. A relationship is brought. To obtain a permeability in the range of 100 to 400, Crystallization of the core is required, and about 10 to 25% of the core volume is crystallized. It is preferred that   In addition, the present invention provides for the use of certain temperatures and times to achieve the desired choke characteristics. Requires annealing process parameters and the degree of control of these parameters .                               BRIEF DESCRIPTION OF THE FIGURES   A complete understanding of the present invention will be obtained by reference to the following detailed description and the accompanying drawings. And other advantages will be apparent. In the attached drawings,   FIG. 1 is a graph showing the relationship between the magnetic permeability of the core and the annealing temperature. , Each curve represents a material having a different crystallization temperature.   FIG. 2 shows the permeability of the core, the annealing temperature, and the various annealing times. 6 is a graph showing the relationship between.   FIG. 3 shows an annealing process for obtaining temperature uniformity within several degrees. FIG. 3 is a view showing a loading state of a core.   FIG. 4 shows core iron loss W / kg as a function of DC bias field and frequency. It is a graph.   FIG. 5 is a graph showing the magnetic permeability of the core under various DC bias electric field conditions. It is.   FIG. 6 is a representative scanning electron microscope (SEM) cross section after annealing treatment. The picture is shown.   FIG. 7 is a graph showing magnetic permeability as a function of volume% crystallinity.                             Description of the preferred embodiment   FIG. 1 shows the magnetic permeability of an annealed Fe-based magnetic core to determine the annealing temperature. As a function of The permeability is 10 kHz frequency, 8 turns jig and 1 At an AC excitation voltage of 00 mV, measurements were taken at the induction bridge. Annealing time Was constant for 6 hours. All cores are annealed in an inert gas atmosphere. Received. The various curves show a slight change in the chemical composition and thus a slight change in the crystallization temperature This represents an Fe base alloy. The crystallization temperature is determined by differential scanning calorimetry (DSC). It was measured. Increasing the annealing temperature for a given annealing time, A decrease in permeability was observed. For a given annealing temperature, the crystallization temperature The scale of permeability according to, i.e., the permeability is determined by the alloy with the highest crystallization temperature. About the biggest.   FIG. 2 shows the annealing of the magnetic permeability of the core having the same chemical composition subjected to the annealing treatment. Shown as a function of processing temperature. The different curves represent different annealing times. are doing. The plot shows the annealing temperature for temperatures higher than 450 ° C. The degree effect is shown to be more dominant than the effect of the annealing time.   Appropriate conditions for the annealing temperature and annealing time are shown in FIGS. 1 and 2. Is selected for the amorphous alloy based on Fe-B-Si. this The choice depends on the crystallization temperature (T_xAnd / or if the chemical composition is known It can be carried out. For example, Fe₈₀B₁₁Si₉(T_x= 507 ° C) To achieve a magnetic permeability in the range of 420 to 425 ° C. It is appropriate to perform annealing for 6 hours at the annealing temperature.   Referring again to FIG. 1, given a temperature variation of less than 1-2 ° C., Reproducibility and uniformity are obtained for the values of the magnetic permeability. Temperature uniformity in the furnace and Special loaded bears have been developed to carry out the annealing process so that reproducibility is established. Was. For box-type inert gas furnaces, wire mesh Al plates (aluminum The plates 2 are stacked as shown in FIG. 3 and the structure is placed in the center of the furnace. A above The l-plate is the substrate that holds the core 1 during the annealing process.   Representative magnetic property data for chokes, such as iron loss and DC bias, This is shown in FIGS. Iron loss data as a function of DC bias field The various curves show different measured frequencies, plotted. The data shown The data relates to a core having an OD (outer diameter) of 25 mm. Chalk Important performance parameters remain when the core is driven with a DC bias field It is the percentage of the initial permeability. FIG. 5 has an OD of 35 mm 3 shows a representative DC bias curve for a core.   Cross-sectional scanning electron microscopy (SEM) and X-ray diffraction (XRD) The distribution and percent crystallization of the softened core were measured. Figure 6 is representative Typical cross-sectional scanning electron micrographs show the alloy body and surface. Are crystallized together. This means that only the surface is crystallized It is easily distinguished from the method described in the aforementioned U.S. Pat. No. 4,812,181. It is.   The volume percent of crystallization was determined from both SEM and XRD data and the The results are plotted in FIG. 7 as a function of magnetic permeability. Permeability ranging from 100 to 400 Regarding the rate, crystallization of the body in the range of 5-30% is required.   Although the present invention has been described in considerable detail, it is necessary to pay close attention to such details. And other variations and modifications will be obvious to those skilled in the art. It is understood that all modifications fall within the scope of the present invention as set forth in the appended claims. There is a need.

[Procedure amendment] Article 184-8, Paragraph 1 of the Patent Act [Submission date] December 24, 1997 (December 24, 1997) [Content of amendment] "Electricity based on the principle of annealing an amorphous core of Fe base material" Chalk is described in British Patent 2,117,979A and U.S. Patent 4,812,181. U.S. Pat. No. 4,812,181 discloses that a flat magnetized loop is formed by annealing a Fe-based amorphous core at a temperature higher than 410 ° C. for a long time (10 hours or more). ) Are disclosed. The method disclosed in the above-mentioned U.S. patents comprises crystallizing the surface of the amorphous ribbon, thereby stressing the amorphous bulk of the ribbon. In the above-mentioned GB 2,117,979, the electric choke is formed based on a heat treatment operation of an Fe-based amorphous core. The maximum permeability is reduced to 1/50 to 1/30 of its initial value (for a maximum permeability of 40,000, the above process yields a value in the range of about 800 to 1,300) and the amorphous core is Shows a certain degree of crystallization not exceeding 10% of its volume. IEEE Transactions on Magnetics (MAG-20 (1984) Sep., No. 5, Part 2, NY, USA) discusses the development of Fe-B based amorphous alloys for chokes and inductors on pages 1415-1416. are doing. This article notes a permeability of 200 at the expense of high frequency loss characteristics. European Patent Application No. 513385 (EP-A-513-385) discloses an iron-based soft magnetic alloy that requires aluminum to prevent the formation of Fe-B crystals. When applied to power supplies for notebook computers and other small devices, it has low permeability (100-300), very low core loss and saturation magnetism, and can withstand high DC bias magnetic fields. Very small electric chokes are required. SUMMARY OF THE INVENTION The present invention provides an electrical choke with dimensions in the range of about 8 mm to 45 mm (OD) having magnetic permeability in the range of 100 to 400 and low core loss (less than 70 W / kg at 100 kHz and 0.1 T). I do. The magnetic properties are effective because they are maintained under a DC bias (at least 40% of the initial permeability is maintained under a DC bias electric field of 3,980 A / m or 50 Oe). The present invention also provides a method for producing a minute gap in a core by subjecting an amorphous alloy of a Fe base to a controlled heat treatment to partially crystallize the amorphous ribbon body. As a result of the distribution gap, the above-described characteristics are obtained. More specifically, the present invention provides a unique relationship between the degree of crystallization and the magnetic permeability. In order to obtain a magnetic permeability in the range of 100 to 400, crystallization of the amorphous core body is required, and it is preferable to crystallize about 10 to 25% of the core volume. Claims 1. An electrical choke, comprising: (a) a magnetic core essentially consisting of an Fe-based amorphous metal alloy partially crystallized to about 10% or more and having a distribution gap; b) An electrical choke comprising having a permeability in the range of about 100 to 400 at 10 kHz. 2. It has an initial permeability of 40% maintained in a DC bias field of 3,980 A / m (50 Oe), an iron loss of less than 70 W / kg in a bias field of 100 kHz and 0.1 T, and a high saturation magnetic flux density. An electric choke according to claim 1. 3. A method for manufacturing an electrical choke comprising a core comprising an amorphous metal alloy partially crystallized to about 10% or more and having a permeability at 10 kHz ranging from about 100 to 400, comprising: (a) Annealing the choke in a protective atmosphere at a temperature and time parameter dependent on the crystallization temperature and chemical composition of the amorphous metal alloy; (b) then setting the time and temperature parameters to a specific iron-based alloy A method of making an electrical choke, comprising selecting according to the data of FIGS. 4. The amorphous metal alloy is Fe ₈₀ B ₁₁ Si _9, said annealing temperature of 425 ° C., an electric choke method of claim 3 in which said annealing time about 6-8 hours. 5. The amorphous metal alloy is Fe ₈₀ B ₁₂ Si _8, said annealing temperature of 455 ° C., an electric choke method of claim 3 in which said annealing time about 4 hours. 6. 4. The method for manufacturing an electric choke according to claim 3, wherein the annealing step is performed in the absence of a magnetic field. 7. 4. The electrical power of claim 3, wherein during the annealing step the temperature is controlled within the range of about 2-5 [deg.] C, such that the choke after the annealing exhibits a substantially constant magnetic permeability. Chalk manufacturing method. 8. The annealing step is performed in a box-type convection furnace, and the cores are arranged in the furnace as shown in FIG. 3, thereby controlling the temperature within a range of about 2 to 5 ° C. A method for manufacturing an electric choke according to claim 7. 9. 4. The chalk of claim 3, wherein the chalk is partially crystallized by undergoing annealing such that substantially all of the amorphous metal therein is about 10-25% crystalline. Electric chalk manufactured by the method. 10. The partial crystallization is intended to cause crystal formation of αFe and Fe ₂ B therein, produced by the method according to claim 3 electrical choke. 11. 7. The method of claim 6, wherein the core is coated with a thin high-temperature resin, the thin high-temperature resin electrically insulating the core and maintaining the integrity of the core. Electric chalk. 12. 4. The chalk produced by the method of claim 3, wherein the chalk is partially crystallized by annealing, whereby substantially all of the amorphous metal therein is about 10-30% crystalline. Electric chalk.

────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Abou-Elias, Joseph             United States of America New Jersey 07838,             Great Meadows, Shire Drive               2 (72) Inventors Martis, Ronald Jay             United States of America New Jersey 07936,             East Hanover, Fairway             Drive 34 (72) Hasegawa, Ryusuke             07960 United States New Jersey             Morristown, Hill Street 29

Claims (1)

[Claims] 1. An electric choke comprising a magnetic core having a distribution gap, wherein the magnetic core consists essentially of a partially crystallized Fe-based amorphous metal alloy. 2. The electrical choke of claim 1, having a permeability in the range of about 100 to 400 at 10 kHz, wherein 40% of the initial permeability is maintained at a DC bias field of 3,980 A / m (50 Oe); An electric choke having an iron loss of less than 70 W / kg at 100 kHz and 0.1 T bias magnetic field and having a high saturation magnetic flux density. 3. What is claimed is: 1. A method for producing an electric chalk having a core made of an amorphous metal alloy, comprising annealing the choke in a protective atmosphere at a temperature and time parameter dependent on the crystallization temperature and chemical composition of the amorphous metal alloy. A method for producing an electric choke, comprising an annealing step for treating, wherein said time and temperature parameters are selected according to the data of FIGS. 1 and 2 for a particular iron-based alloy. 4. In the electric choke method according to claim 3, characterized in that the amorphous metal alloy and Fe ₈₀ B ₁₁ Si _9, said annealing temperature of 425 ° C., and about 6-8 hours the annealing time Method of manufacturing electric chalk. 5. In the electric choke method according to claim 3, wherein the amorphous metal alloy and Fe ₈₀ B ₁₂ Si _8, said annealing temperature of 455 ° C., characterized by about four hours the annealing time Electric chalk manufacturing method. 6. 4. The method of manufacturing an electric chalk according to claim 3, wherein the annealing process is performed in the absence of a magnetic field. 7. 4. The method of claim 3, wherein the temperature is controlled within about 2-5 [deg.] C. during the annealing step, so that the choke after the annealing step is substantially constant. A method for producing an electric choke, characterized by exhibiting a magnetic permeability of: 8. The method for manufacturing an electric chalk according to claim 7, wherein the annealing process is performed in a box-type convection furnace, and the cores are arranged in the furnace as shown in FIG. A method for manufacturing an electric choke, wherein the temperature is controlled within about 2 to 5 ° C. 9. 4. An electric choke manufactured according to the method of claim 3, wherein the choke is partially crystallized by undergoing an annealing treatment, whereby substantially all of the amorphous metal therein is reduced. An electric choke configured to be about 10-25% crystalline. 10. 4. The method for manufacturing an electric choke according to claim 3, wherein the crystals of αFe and Fe ₂ B are formed by the partial crystallization. 11. 7. The electrical choke of claim 6, wherein the core is coated with a thin high temperature resin, the thin high temperature resin configured to electrically insulate the core and maintain core integrity. An electric choke characterized by: