JP2668230B2 - Choke coil and manufacturing method thereof - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a choke coil and a method for manufacturing the choke coil. Prior art and its problems The choke coil is a current with a relatively high frequency, and it constantly or periodically leaks from, for example, electrical equipment or enters from the power supply side, or in a circuit. , For example, to remove ripple current, on-off surge current, etc., and to pass only DC or a relatively low frequency desired current. Such a choke coil is used in various devices such as switching regulators, inverters such as thyristor inverters, or ordinary DC power supplies for the purpose of removing ripples, removing ON-OFF surges, and the like. And, as such a magnetic core material for a choke coil, a silicon steel plate or ferrite has been conventionally used. Furthermore, due to its excellent soft magnetic characteristics, a ribbon of an amorphous magnetic alloy is used as a magnetic core material for a choke coil. (Japanese Patent Laid-Open No. 57-193006, etc.) have been proposed and put to practical use. The choke coil is generally constructed so that an alternating current flows through it superimposed on a direct current component, and the magnetic characteristics of the magnetic core material for the choke coil are such that Br is small in the BH characteristic diagram and BH It is required that the unsaturated region of the characteristic be wide. Conventionally, a method of providing a gap in a magnetic path of a magnetic core to widen an unsaturated region has been generally used. In this case, the gap may be a void or may be filled with a non-magnetic material. However, in such a method, a thin ribbon of an amorphous magnetic alloy is wound and then fixed and cut, so that the process is complicated, time-consuming, and disadvantageous in cost. In the case of a small choke coil, the gap length must be set to an extremely small value (usually about 100 μm to submicron), and there is a problem that the gap cannot be set to an appropriate value. In addition, energy is concentrated in the gap, causing magnetic leakage, adversely affecting peripheral devices, and generating beats. Therefore, it is desired to improve the magnetic characteristics so as to satisfy the required characteristics of the choke coil by a method different from the above method. In the case of a small choke coil, a magneto-mechanical resonance based on magnetostrictive vibration is observed, and a singular point occurs in the frequency characteristic of the magnetic permeability, so that it is necessary to take some means. II Object of the Invention It is an object of the present invention to improve the magnetic characteristics required for a choke coil, such as to expand the unsaturated region in the BH characteristics without providing a gap, and to improve the ultra-compact size of the choke coil. It is possible to eliminate the adverse effect on peripheral devices without magnetic leakage, avoid beats, and be advantageous in terms of cost.In addition to these, it is possible to prevent magneto-mechanical resonance and improve the frequency characteristics of permeability. An object is to provide a good choke coil and a manufacturing method thereof. III Disclosure of the Invention Such an object is achieved by the present invention described below. That is, a first invention of the present invention is a choke coil having a magnetic core in which an alkali-silicate glass film is interposed between thin ribbons of an Fe-based amorphous magnetic alloy. In a second aspect of the present invention, a water glass is applied to the surface of a ribbon of an Fe-based amorphous magnetic alloy, and then the ribbon is wound to form a wound body, which is then subjected to a heat treatment to form a magnetic core. The method of manufacturing a choke coil is characterized in that a winding is applied to the choke coil. A third invention is to wind a thin ribbon of an Fe-based amorphous magnetic alloy and impregnate it with water glass to form a wound body.
This is a method for manufacturing a choke coil, wherein heat treatment is performed to form a magnetic core, and a winding is applied to the magnetic core. JP-A-59-177377 discloses a method in which a solution in which an acid is added to an alcohol solution of ethyl silicate is applied to the surface of an amorphous alloy and dried to form a film. In the invention disclosed in the above publication, only insulation and rust resistance are taken into consideration, and in the magnetic properties of the present invention, iron loss is slightly increased in the present invention, whereas iron loss is increased. Is reduced, which is completely different from the present invention. More specifically, in the coating film of the hydrolytic condensate of ethyl silicate as described above, the effect of expanding the unsaturated region of the BH characteristic of the present invention is not realized, as will be apparent from the examples described later. IV Specific Configuration of the Invention Hereinafter, the specific configuration of the present invention will be described in detail. The choke coil of the present invention has a wound core in which an alkali-silicate glass film is interposed between thin ribbons of an Fe-based amorphous magnetic alloy. In this case, the thin ribbon of the Fe-based amorphous magnetic alloy may have a thickness of about 10 to 100 μm obtained by a known high-speed quenching method. In addition, the composition may be various ones containing Fe as a main component, but may contain an iron group transition metal element in addition to Fe as an iron group element, and the Fe composition ratio in the iron group element is 40 at. % Or more, more preferably 60 at% to 100 at%, and Si, B,
It is preferable that at least one of P, C and the like is contained as a vitrifying element. In order to interpose the alkali-silicate glass film in the present invention, it is preferable to adopt a method of impregnating water glass with a ribbon-shaped wound body of an Fe-based amorphous magnetic alloy from the viewpoint of easy handling. . Alternatively, a wound body may be formed after applying water glass to the ribbon. In this case, the water glass is a concentrated aqueous solution of alkali-silicate glass. The alkali-silicate glass contains an alkali component, and the alkali is generally Na ₂ O, but a part or all of Na ₂ O may be replaced by K ₂ O in some cases. Generally, the molar composition of the glass is preferably represented by R ₂ O · nSiO ₂ (R = Na and / or K, n = 1 to 10, more preferably 2 to 4). In addition to these, the alkali-silicate glass further contains lithium, alkaline earth metal,
An oxide such as lead, aluminum or boron may be contained in an amount of 10 mol% or less. The components of the water glass used are SiO ₂ 15 to 50 wt%,
More preferably 23~37wt%, Na ₂ O and / or K ₂ O 1
-30 wt%, more preferably 6-18 wt%, and further Fe
₂ O _{3 0.03~0.05wt%,} it is preferable to contain the extent insoluble matter of 0.2% or less. In this case, the thickness of the coating film formed from the water glass may be such that the interlayer thickness is 0.01 to 10 μm, preferably 0.1 to 1 μm. When the thickness is less than 0.01 μm, BH
There is no effective expansion effect of the unsaturated region in the characteristics,
exceeds m, when the magnetic core of the wound body, the magnetic flux density B _m of the magnetic core reduces the space factor of Fe-based amorphous magnetic alloy of it is because deteriorated. In the present invention, by controlling the thickness of the coating film, it is possible to obtain magnetic characteristics suitable for a target choke coil. The choke coil of the present invention is obtained as follows. First, a thin strip of an Fe-based amorphous magnetic alloy is wound to form a wound body. The wound body is formed by winding a ribbon using a winding frame, a winding core, or the like as necessary, and fixing the ends thereof. In this case, the structure, shape, etc. of the winding frame, winding core, etc. can be various. The material is porcelain, glass, resin, etc.
The end portion may be fixed by an adhesive, welding, tape, or the like, or may be caulked by a caulking claw provided on a winding frame or the like. The size of the wound body may be appropriately determined according to the application. Thereafter, the wound body is impregnated into the above-mentioned water glass by a method such as vacuum impregnation to form a coating film of water glass. The water glass may be diluted with water to, for example, about 30% or less before use. Thereafter, preliminary drying is performed at room temperature to 100 ° C. for about 10 minutes to 2 hours. Obtaining a wound body by such a method is preferable from the viewpoint of productivity. Further, in order to obtain a thin roll of a Fe-based amorphous magnetic alloy with a water glass coating interposed therebetween, the water glass coating having a desired thickness is formed on the surface of the thin ribbon. It may be wound after being formed in the shape. In this case, the water glass may be applied by a known method such as dipping, brushing or spraying. When applying the water glass, the water glass may be diluted with water, for example, to about 30% or less, as described above. Thereafter, preliminary drying is performed under the same conditions as described above. Water glass may be applied to both sides or one side of the ribbon. Further, in the present invention, not only a wound body but also a laminated body may be used, and the same effect can be obtained. The wound body thus manufactured is preferably subjected to a heat treatment to remove the strain in the ribbon. The heat treatment is usually performed at a temperature from the Curie point to the crystallization temperature, specifically, about 350 to 500 ° C. for about 30 minutes to 5 hours. The atmosphere may be any of air, vacuum, inert gas, non-oxidizing gas and the like. Further, such processing may be performed in a magnetic field or in a magnetic field. When the magnetic field is applied, it is usually a static magnetic field, and the applied magnetic field at this time is, for example, about 100 e. In addition, the heat treatment can be performed while applying tension, or in some cases, in a rotating magnetic field. In the present invention, during the heat treatment, stress-strain is applied to the ribbon due to the fact that the coefficient of thermal expansion of the alkali-silicate glass as the coating film is larger than that of the amorphous magnetic alloy. The unsaturated region in the H characteristic increases, which is different from the conventional method. The magnitude of stress strain can be changed by controlling the thickness of the coating film. In this case, according to the present invention, the unsaturated region 3 of the BH characteristic is
It increases to about 20 times. After the heat treatment, the wound body is cooled to room temperature. Such cooling is performed by, for example, air cooling. The cooling rate is usually about 1 to 400 ° C / min. After cooling, a resin film is preferably provided on the surface of the wound body in the present invention. Such a resin film is 10 μm
It is preferable to make the above. Such a resin film is preferably formed by arranging a magnetic core in a casing and molding the magnetic core. Further, resin impregnation or resin coating may be performed by dipping or the like according to a known method. As the resin material, for example, any of an epoxy resin, a phenol resin, a silicone resin, a urethane resin and the like may be used, but a thermosetting material is preferable. Further, a filler may be contained in such a resin. By having such a resin film, when a magnetic core is used, the frequency characteristics of magnetic permeability are smoothed. Thereafter, a predetermined winding is applied to the magnetic core thus obtained, and other predetermined processing is performed to form a choke coil. Such a choke coil is used for various electric devices such as a switching regulator, a thyristor inverter and other inverters, or a normal DC power supply. It is useful as a coil for removing ripples, on / off surges, etc. V. Specific Action and Effect of the Invention According to the present invention, without providing a gap in the magnetic core,
Permeability required when using as a choke coil,
It is possible to expand the unsaturated region in the BH characteristics while maintaining magnetic characteristics such as iron loss. Such an expansion of the unsaturated region can be adjusted only by controlling the thickness of the coating film of the alkali-silicate glass, and the production is easy. As a result, it can be applied to an ultra-small choke coil. Further, since there is no step of providing a gap or filling a gap with a non-magnetic material, the production becomes easy and the cost is also advantageous. Further, magnetic leakage due to the gap can be prevented, adverse effects on peripheral devices can be eliminated, and beats can be prevented. In addition, it is possible to prevent the magnetic properties from deteriorating with time. By having the resin film, it becomes possible to prevent magneto-mechanical resonance and to smooth the frequency characteristics of magnetic permeability. VI Specific Examples of the Invention Hereinafter, the present invention will be described in more detail by showing specific examples of the present invention. Example 1 A long strip of an amorphous magnetic alloy having a composition of Fe ₇₈ Si ₉ B ₁₃ having a thickness of 25 μm and a width of 1 mm was washed with water glass (Na ₂ O 30 wt%, SiO ₂ 10 wt
%), And pre-dried at 100 ° C. for 30 minutes to form a 1 μm thick alkaline solution on both surfaces of the ribbon.
A coating of silicate glass was formed. The thin ribbon on which the coating film was formed was formed into a toroidal magnetic core having an inner diameter of 3 mm, an outer diameter of 8 mm, and a height of 1 mm according to a conventional method. This wound magnetic core was heat-treated at 450 ° C. for 1 hour. afterwards,
It was cooled to room temperature (cooling rate 200 ° C / min), and this was used as a magnetic core for winding. The winding was 15 turns. The choke coil manufactured in this manner is referred to as Sample 1. A choke coil was prepared in the same manner as in Sample 1, except that no alkali-silicate glass coating film was formed. This is designated as Sample 2. In addition, samples 3 and 4 were formed by using a varnish (U varnish; manufactured by Ube Industries, Ltd.) and a phosphate (FT-7; manufactured by Nippon Parkerizing Co., Ltd.) in place of water glass. And Further, Sample 5 was obtained by forming a coating film using ethyl silicate according to the method described in JP-A-59-177377. The magnetic characteristics of each of these samples 1 to 5 were examined. Table 1 shows the results. In Table 1, as a summary, the suitability for use as a choke coil is indicated by O and X. In the above, a ribbon of an amorphous magnetic alloy was wound into a wound body, and then impregnated with a 30% by weight solution of water glass. When the magnetic properties of this sample were examined, results equivalent to those of the above-mentioned sample 1 were obtained. Example 2 Sample 1 produced in Example 1 was molded with an epoxy resin in a casing. This is designated as Sample 1a. These samples 1, 1a, bias 50e, H _m = 10m
The DC superposition characteristics were measured by Oe, and the frequency characteristics of the magnetic permeability μ were examined. The result is shown in FIG. In sample 1a, smoothing of the frequency characteristic is observed as compared with sample 1. From the above, the effect of the present invention is clear.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing frequency characteristics of magnetic permeability of a choke coil according to the present invention.

Claims (1)

(57) [Claims] A choke coil having a magnetic core in which an alkali-silicate glass film is interposed between thin ribbons of an Fe-based amorphous magnetic alloy. 2. The choke coil according to claim 1, wherein the magnetic core is a wound body of a ribbon. 3. The choke coil according to claim 1, wherein the wound body has a resin film on a surface thereof. 4. After water glass is applied to the surface of the Fe-based amorphous magnetic alloy ribbon, the ribbon is wound to form a wound body, which is heat-treated to form a magnetic core, which is then wound. A method for manufacturing a choke coil. 5. A choke characterized by winding a thin ribbon of an Fe-based amorphous magnetic alloy, impregnating this with water glass to form a wound body, then heat-treating it to form a magnetic core, and winding the core. Manufacturing method of coil.