JP2016063158A - Inductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inductor which allows for formation of an efficient magnetic circuit for magnetic flux generated in the inner part of winding, without causing magnetic saturation of a magnetic core even under a large current, while suppressing generation of noise due to magnetic flux leakage to the outside.SOLUTION: A magnetic core is not arranged on the winding inside of a coil 2, at least one of a resin body 4 and a magnetic material 3 is arranged on the winding outside of the coil 2, and the winding outside of the coil is especially covered with at least one of the resin body and magnetic material.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an inductor, and more particularly to an inductor for removing noise used as a magnetic core of a transformer, an antenna (bar antenna), a choke coil, a filter, a sensor or the like under a large current and a high magnetizing force.

In recent years, with the improvement of functions of power semiconductors such as switching elements and diodes, the current flowing in the circuit has been increased in current and frequency. Along with this, the inductors used as reactors, choke coils, transformers and the like used in the circuit are also required to cope with high current and high frequency.
In addition, applications that handle large currents such as converters for solar power generation and wind power generation, data centers, etc. have been expanded, and countermeasures against instantaneous large current noise such as lightning, which is called surge current, have become important for these devices. Yes.
In the conventional inductor, a magnetic core is inserted inside the winding to increase the amount of generated magnetic flux and reduce the amount of leakage magnetic flux, thereby realizing downsizing and high efficiency of the inductor. For example, a fixed inductor is disclosed that includes a coil in which an insulating coated wire is wound around a rod-shaped core having either a concave portion or a convex portion on both end faces, and a rectangular sleeve core that houses the coil (Patent Document 1). ).

  On the other hand, a coil composed only of a spirally wound wire, or an air-core coil in which the entire coil is covered and hardened by a resin mold is known. As an improvement to these conventional air-core coils, an air-core coil wound with a conductive wire, enclosing the upper and side surfaces of the air-core coil, providing a vent hole in the lower part of the side part, and forming an opening in the upper part There is disclosed an air core coil device including a frame body, in which a coil terminal of an air core coil is taken out from a notch provided on a side surface of the frame body and the coil terminal is fixed to a mounting substrate (Patent Document 2).

JP 2005-338772 A JP 2002-280232 A

  However, in the case of an inductor in which a magnetic core is arranged inside a winding coil, when a very large current such as a surge current flows through the inductor, the magnetic core becomes magnetically saturated and functions as an inductor. It may disappear. Even when the magnetic saturation is not reached, when the magnetizing force increases with the increase in current, the magnetic flux density increases and the magnetic permeability decreases. Therefore, there is a problem that it is difficult to ensure a high inductance under a high magnetizing force.

  In the case of the air-core coil described in Patent Document 2, there is a problem that noise generation due to magnetic flux leakage to the outside cannot be suppressed. Moreover, since the whole coil is not covered with the insulation case, there exists a problem that the electric leakage to the outside cannot be suppressed.

  The present invention has been made to cope with such a problem, and the magnetic flux generated at the inner side of the winding without magnetic saturation of the magnetic core even under a large current of several thousand A such as a surge current. On the other hand, an object of the present invention is to provide an inductor capable of forming an efficient magnetic circuit and suppressing noise generation due to magnetic flux leakage to the outside.

The inductor of the present invention is characterized in that at least one of a resin body and a magnetic body is disposed outside the coil winding of the coil without disposing a magnetic core inside the coil winding of the coil. In particular, the coil winding outer side of the coil is covered with at least one of a resin body and a magnetic body.
In addition, a coil having no magnetic core is embedded in the resin body.
In the inductor of the present invention, the two lead wires of the coil are drawn in directions that do not overlap each other as viewed from the axial direction around which the coil is wound, or the distance space between the lead ports of the two lead wires of the coil An insulator is disposed on the substrate.

  In the inductor according to the present invention, a resin body and / or a magnetic body is arranged outside the coil winding without arranging a magnetic core inside the coil winding where the magnetic flux density is highest. As a result, an efficient magnetic circuit can be formed with respect to the magnetic flux generated inside the coil winding without magnetic saturation of the magnetic core even under a large current of several thousand A such as a surge current. Further, when a magnetic body is disposed outside the coil winding, a magnetic path is formed through the magnetic body, so that it is possible to increase inductance while suppressing noise generation due to magnetic flux leakage to the outside.

It is a figure which shows an example of the inductor which concerns on this invention. It is a figure which shows the conventional pot type inductor. It is a figure which shows an example of the other inductor which concerns on this invention. It is a figure which shows the example of the inductor with which two coils were connected. It is sectional drawing of the conventional UU type | mold inductor. It is a figure which shows the form 1 of two leader lines. It is a figure which shows the form 2 of two leader lines. It is a figure which shows the form 3 of two leader lines. It is a figure which shows an example of a surge countermeasure circuit. It is a measured value of inductance measured by changing the magnetizing force.

An example of the inductor according to the present invention is shown in FIG. FIG. 1 is a cross-sectional view of a pot-type inductor as viewed obliquely from above. The lead lines are not shown.
In the inductor 1, the outer side of the wound coil 2 is covered with a magnetic body 3. The magnetic core is not arranged inside the coil winding. The entire coil 2 is embedded in an electrically insulating resin body 4. The resin body 4 can secure the coil 2 and ensure insulation. Reference numeral 5 denotes an abutting surface when the magnetic body 3 is manufactured.

  In the inductor according to the present invention, the coil 2 is not sealed with the resin body 4 as long as the coil 2 can be secured and insulated with respect to the magnetic body 3 arranged on the outer side of the coil winding. May be arranged inside the magnetic body 3 as an air-core coil.

  FIG. 2 is an example of a conventional pot-type inductor 1 ′ corresponding to FIG. 1, and is a comparative example in which the magnetic body 3 is arranged on the outer side and the inner side of the wound coil 2. In this case, when a large current flows through the coil 2, the magnetic permeability decreases and it is difficult to secure a high inductance.

Another example of the inductor according to the present invention is shown in FIG. FIG. 3A is a top view of the pot type inductor, and FIG. 3B is a cross-sectional view taken along line AA.
The inductor 1a is a coil in which the coil 2 is arranged inside the resin case 4a and the magnetic core is not arranged inside the coil winding. The coil 2 is a coil obtained by edgewise winding a rectangular insulated winding. In FIG. 3, the included angle θ between the two lead lines 6a and 6b is set to 180 °. By setting the included angle to 180 ° and arranging the coil 2 in the resin case 4a, withstand voltage, insulation resistance and impulse insulation could be secured.

An example of an inductor in which two coils according to the present invention are connected is shown in FIG. 4A is a top view of the UU-type inductor, and FIG. 4B is a cross-sectional view taken along the line BB.
The inductor 1b is a coil composed of two coils 2 connected at a portion 2a, and magnetic bodies 3a and 3b are arranged above and below the coil in the axial direction. Since there is no magnetic core inside the coil winding, high inductance can be maintained.

  FIG. 5 shows a BB cross-sectional view of a conventional UU type inductor corresponding to FIG. In the inductor 1 ″, a coil 2 is wound around a magnetic core made of a magnetic body 3. In this case, since the magnetic body 3 is disposed, when a large current flows through the coil 2, the magnetic permeability is reduced and it is difficult to secure a high inductance.

  Magnetic materials that can be used in the present invention include pure iron, iron-silicon alloys, iron-nitrogen alloys, iron-nickel alloys, iron-carbon alloys, iron-boron alloys, iron-cobalt alloys, iron- It can be produced by subjecting the powder surface of a phosphorus alloy, iron-nickel-cobalt alloy, iron-aluminum-silicon alloy (Sendust alloy), amorphous material, fine crystal material or the like to insulation treatment and compression molding. Among these magnetic powders, pure iron is preferable, and reduced iron powder or atomized iron powder used in powder metallurgy is particularly preferable. More preferably, the reduced iron powder is excellent in mechanical properties of the magnetic core obtained.

  The surface of the magnetic powder particles is preferably coated with an inorganic insulator. There is no limitation in particular in the kind of inorganic insulating material, The thing conventionally used in the dust core can be used. Examples of preferable insulating materials include metal phosphates such as iron phosphate, manganese phosphate, zinc phosphate, calcium phosphate, and aluminum phosphate, metal oxides such as silicon oxide, magnesium oxide, aluminum oxide, titanium oxide, and zirconium oxide. Things. As a commercial product of iron-based soft magnetic powder coated with an inorganic insulator, there is a trade name manufactured by Höganäs; Somaloy.

The magnetic substance disposed outside the coil winding is formed by pressure-molding the raw material powder alone with an inorganic insulating coating formed on the particle surface or a powder in which a thermosetting resin such as an epoxy resin is blended with the raw material powder. It is possible to produce a green compact by firing the green compact.
The epoxy resin that can be used in the present invention is a resin that can be used as an epoxy resin for bonding, and is preferably a resin having a softening temperature of 100 to 120 ° C. For example, an epoxy resin that is solid at room temperature, becomes a paste at 50 to 60 ° C., becomes fluid at 130 to 140 ° C., and starts a curing reaction when further heated can be used. This curing reaction starts at around 120 ° C., but the temperature at which the curing reaction is completed within a practical curing time, for example, 2 hours, is preferably 170 to 190 ° C. In this temperature range, the curing time is 45 to 80 minutes.

  Examples of the resin component of the epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, hydrogenated bisphenol A type epoxy resin, hydrogenated bisphenol F type epoxy resin, stilbene type epoxy resin, and triazine skeleton. -Containing epoxy resin, fluorene skeleton-containing epoxy resin, alicyclic epoxy resin, novolac-type epoxy resin, acrylic epoxy resin, glycidylamine-type epoxy resin, triphenolphenolmethane-type epoxy resin, alkyl-modified triphenolmethane-type epoxy resin, biphenyl-type Examples thereof include an epoxy resin, a dicyclopentadiene skeleton-containing epoxy resin, a naphthalene skeleton-containing epoxy resin, and an arylalkylene type epoxy resin.

The curing agent component of the epoxy resin is preferably a latent epoxy curing agent. By using a latent epoxy curing agent, the softening temperature can be set to 100 to 120 ° C, and the curing temperature can be set to 170 to 190 ° C. Formation of an insulating coating film on iron powder powder, and subsequent compression Molding and thermosetting can be performed.
Examples of the latent epoxy curing agent include dicyandiamide, boron trifluoride-amine complex, and organic acid hydrazide. Of these, dicyandiamide that meets the above-mentioned curing conditions is preferred.
Moreover, hardening accelerators, such as tertiary amine, an imidazole, and an aromatic amine, can be included with a latent epoxy hardening | curing agent.
The epoxy resin containing the latent curing agent is latent so that the curing conditions are 160 ° C. for 2 hours, 170 ° C. for 80 minutes, 180 ° C. for 55 minutes, 190 ° C. for 45 minutes, and 200 ° C. for 30 minutes. Add a functional curing agent.

  The blending ratio of the iron-based soft magnetic powder whose surface is treated with the inorganic insulating coating and the epoxy resin is 95 to 99% by mass of the iron-based soft magnetic powder and the latent hardener based on the total amount of these. The resin is 1 to 5% by mass. This is because if the epoxy resin is less than 1% by mass, it is difficult to form an insulating coating, and if it exceeds 5% by mass, the magnetic properties are degraded and a resin-rich coarse aggregate is generated.

  The magnetic material disposed on the outer side of the coil winding is obtained by dry-mixing the iron-based soft magnetic material powder whose surface is treated with an inorganic insulating coating and the epoxy resin at a temperature of 100 to 120 ° C. An uncured resin film is formed on the inorganic insulating film formed on the surface of the magnetic powder. An iron-based soft magnetic powder with an insulating coating formed on its surface is formed into a compact by compression molding using a mold, and then heat-cured at a temperature equal to or higher than the thermal curing start temperature of the epoxy resin. The body is obtained.

The magnetic body 3 can also be manufactured by blending a binder resin with iron-based soft magnetic powder and injection molding the mixture. As the binder resin, a thermoplastic resin capable of injection molding can be used. Examples of thermoplastic resins include polyolefins such as polyethylene and polypropylene, polyvinyl alcohol, polyethylene oxide, polyphenylene sulfide (PPS), liquid crystal polymers, polyether ether ketone (PEEK), polyimide, polyether imide, polyacetal, polyether sulfone, and polysulfone. , Polycarbonate, polyethylene terephthalate, polybutylene terephthalate, polyphenylene oxide, polyphthalamide, polyamide, and mixtures thereof. Among these, polyphenylene sulfide has excellent fluidity during injection molding when mixed with iron-based soft magnetic powder, and the surface of the molded article after injection molding can be covered with a resin layer, and also has excellent heat resistance, etc. (PPS) is more preferable.
The ratio of the raw material powder is preferably 80 to 95% by mass, where the total amount of the raw material powder and the thermoplastic resin is 100% by mass. If it is less than 80% by mass, magnetic properties cannot be obtained, and if it exceeds 95% by mass, the injection moldability is poor.
For the injection molding, for example, a method of injecting and molding the raw material powder into a mold in which a movable mold and a fixed mold are abutted can be used.

  The above-mentioned binder resin can be used for the resin insulator disposed outside the coil winding and covering the coil. Moreover, thermosetting resins, such as an epoxy resin or a phenol resin, can be used.

As the winding used for the coil 2 that can be used in the present invention, a copper enameled wire can be used, and the types thereof are urethane wire (UEW), formal wire (PVF), polyester wire (PEW), polyesterimide. A wire (EIW), a polyamideimide wire (AIW), a polyimide wire (PIW), a double coated wire combining these, a self-bonding wire, a litz wire, or the like can be used. A round wire or a square wire can be used as the cross-sectional shape of the copper enamel wire.
As the winding method of the coil, edgewise winding, helical winding, and toroidal winding of a flat enameled wire can be adopted. In the present invention, edgewise winding of a rectangular enameled wire is preferable.

  As the resin body 4 in which the coil 2 is embedded, any resin that can fix the coil 2 and impart insulation can be used. Preferably, a thermoplastic resin capable of injection molding can be used. Examples of the thermoplastic resin include the thermoplastic resins described as the binder resin. Among these, polyphenylene sulfide (PPS), which has excellent fluidity during injection molding, can cover the surface of the molded article after injection molding with a resin layer, and is excellent in heat resistance and the like, is preferable.

  For the injection molding, for example, a method of injecting and molding the resin body 4 into a mold in which a movable mold and a fixed mold are abutted and the coil 2 is placed inside can be used. Although the injection molding conditions vary depending on the type of thermoplastic resin, for example, in the case of polyphenylene sulfide (PPS), the resin temperature is preferably 290 to 350 ° C. and the mold temperature is preferably 100 to 150 ° C.

  As the resin body 4 in which the coil 2 is embedded, in addition to the thermoplastic resin, a thermosetting resin such as the epoxy resin used as a binder of the magnetic body 3 or a phenol resin can be used.

  The inductor of the present invention shown in FIG. 1 is obtained by press-fitting a resin body 4 in which a coil 2 is embedded into a magnetic body 3 that is divided into two vertically in the sectional view shown in FIG. The two divided magnetic bodies 3 are bonded to each other at the abutting surface 5 using a solventless epoxy adhesive or the like.

  The inductor according to the present invention can suppress a decrease in inductance even when a large current flows into the coil 2, and by adopting a specific form for the lead wire, two inductors can be connected even if a large current flows. Insulation between the lead wires can be ensured. Two lead wire forms are shown in FIGS. 6 and 7 are diagrams in the case where the two lead wires of the coil are separated from each other in a direction not overlapping each other when viewed from the axial direction in which the coil is wound, and FIG. 8 is a diagram between the two lead wires of the coil. It is a figure in the case of arranging an insulator on.

  FIGS. 6A and 6B are diagrams showing a first form of the lead line, in which FIG. 6A shows an inductor top view, FIG. 6B shows the same front view, and FIG. 6C shows the same side view example. The inductor 1 is composed of a coil (not shown in the figure) in which the magnetic body 3 is embedded around the resin body 4 without arranging a magnetic core inside the coil winding, Two lead wires 6a and 6b are drawn out from the coil terminal. The lead wires 6a and 6b are drawn and fixed in directions that do not overlap each other, such as an angle of 180 ° when viewed from the axial direction around which the coil is wound, so that insulation can be ensured by the distance space. .

FIGS. 7A and 7B are diagrams showing a second form of the lead line, in which FIG. 7A shows an inductor top view, FIG. 7B shows the same front view, and FIG. 7C shows the same side view example. The inductor 1 is composed of a coil (not shown in the figure) in which the magnetic body 3 is embedded around the resin body 4 without arranging a magnetic core inside the coil winding, Two lead wires 6c and 6d are led out from the coil terminal. The lead wires 6c and 6d are drawn in the same direction as seen from the axial direction of the coil in the top view, but are separated into an upper stage and a lower stage of the coil axis and do not overlap with each other as seen from the axial direction of the coil. Insulating properties can be ensured by the distance space.
Since the inductor shown in FIG. 7 can be provided at a greater distance from the coil wire outlet than the inductor shown in FIG. 6, it is easy to ensure insulation.

  FIGS. 8A and 8B are diagrams showing a third form of the lead line, in which FIG. 8A shows the top view of the inductor, FIG. 8B shows the same front view, and FIG. 8C shows the same side view example. The inductor 1 is composed of a coil (not shown in the figure) in which the magnetic body 3 is embedded around the resin body 4 without arranging a magnetic core inside the coil winding, Two lead wires 6e and 6f are drawn out from the coil terminal. The insulators 7 are disposed in the distance space between the two lead wires 6e and 6f of the two lead wires. By this insulator 7, the insulation between lines is further enhanced. The insulator 7 is not particularly limited, and an inorganic insulator such as ceramic or an organic insulator such as synthetic resin can be used.

  The inductor of the present invention is not easily magnetically saturated with a coil having no magnetic core inside the coil winding, and can maintain a high inductance even when a large magnetic field is generated. ), Can be used as an inductor for removing noise in a choke coil, filter, sensor, or the like. In particular, it can be suitably used as an inductor used in a surge countermeasure circuit.

An example of a surge countermeasure circuit is shown in FIG. FIG. 9 is an example in which an inductor is arranged in series between two voltage clamping devices.
By arranging the inductor 1 in series with the clamping devices 8a and 8b so as to clamp the voltage from the input side to a protected circuit device serving as an electrical load, a voltage surge due to lightning can be prevented. In particular, the inductor of the present invention is effective for voltage surges because the inductance change rate is small in the range of high magnetizing force.

Example 97.3 g of iron powder particles whose surface is covered with an inorganic insulating coating (Homanes, Somaloy: insulating coating-treated iron powder) and 2.7 g of epoxy resin powder containing dicyandiamide as a curing agent are used in a blender. And mixed for 10 minutes at room temperature. The iron powder particles used were particles that passed through a sieve having a sieve opening of 106 μm and did not pass through a 25 μm sieve. The mixture was put into a kneader and heated and kneaded at 110 ° C. for 15 minutes. The cake agglomerated from the kneader was taken out and cooled, and then pulverized with a pulverizer. Next, compression molding was performed using a mold at a molding pressure of 200 MPa. The compression molded product was taken out from the mold and cured in a nitrogen atmosphere at a temperature of 180 ° C. for 1 hour. Further, cutting was performed to produce a pod type magnetic body 3 having no protrusion at the center as shown in FIG. The magnetic body 3 has a pod shape having an inner diameter of 96 mm, an outer diameter of 120 mm, an inner dimension of 26 mm, and an outer dimension of 36 mm, and two of them were produced.

  A rectangular insulated winding having a width and thickness of 19 × 1.2 mm was prepared, and this was wound edgewise to produce a coil having an inner diameter of 52 mm, an outer diameter of 83 mm, and a height of 56 mm. A resin body capable of fixing the coil to a size that fits in the core was prepared, and the coil was placed on a case and sealed with resin. The lead wire was fixed with a resin sealing material. The obtained resin body was inserted into the pod type magnetic body 3 to produce the inductor shown in FIG.

Comparative Example In the example, an inductor shown in FIG. 2 was manufactured using the same material as in the example except that a pod type magnetic body having a protrusion at the center was used.

  The inductance of the example and the comparative example was measured with an LCR meter by changing the magnetizing force. The results are shown in FIG. As shown in FIG. 10, in the comparative example, the inductance is remarkably reduced as the magnetizing force increases. Usually, since the inductance change rate is used within 30%, the comparative example cannot be used at about 10 kA / m or more. In the choke coil of the present invention, there was almost no decrease in inductance even when the choke coil was increased to 150 kA / m, and a choke coil having a stable inductance in a wide range was obtained.

  The inductor of the present invention has a small inductance change rate in the range of high magnetizing force, and can be used as an inductor for electrical equipment that requires high current and high frequency.

DESCRIPTION OF SYMBOLS 1 Inductor 2 Coil 3 Magnetic body 4 Resin body 5 Abutting surface 6 Lead wire 7 Insulator 8 Clamping device

Claims (7)

  An inductor characterized in that at least one of a resin body and a magnetic body is disposed outside the coil winding of the coil without disposing a magnetic core inside the coil winding of the coil.   2. The inductor according to claim 1, wherein a coil winding outer side of the coil is covered with at least one of a resin body and a magnetic body.   The inductor according to claim 1, wherein the coil is embedded in a resin body.   4. The inductor according to claim 1, wherein the two lead wires of the coil are drawn in a direction not overlapping each other when viewed from an axial direction around which the coil is wound.   The inductor according to claim 1, wherein the two lead wires of the coil are provided with an insulator in a distance space between the lead ports.   An inductor used in a surge countermeasure circuit, wherein the inductor is the inductor according to any one of claims 1 to 5.   The inductor according to claim 6, wherein the inductor is arranged in series between two voltage clamping devices.