JP2015050298A - Reactor, converter, and power converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reactor having excellent quietness.SOLUTION: A reactor comprises: a coil; a magnetic core for forming a closed magnetic circuit with the coil arranged; and a resin part formed around a combinational body of the coil and magnetic core. The magnetic core includes a powder core piece formed by a powder compressed molded body of magnetic powder, and the powder core piece has a coating layer formed from inorganic material on at least part of a surface opposite to the resin part. Preferably, the powder core piece has the coating layer on the whole area of the surface opposite to the resin part.

Description

  The present invention relates to a reactor used as a component of a power conversion device such as an in-vehicle DC-DC converter mounted on a hybrid vehicle, a converter including the reactor, and a power conversion device including the converter. In particular, the present invention relates to a reactor excellent in silence.

  A reactor is one of the parts of a circuit that performs a voltage step-up operation or a voltage step-down operation. The reactor is used in a converter mounted on a vehicle such as a hybrid vehicle. Technologies relating to such a reactor are disclosed in, for example, Patent Documents 1 to 3.

  The reactor includes a coil formed by winding a winding, and a magnetic core in which the coil is disposed to form a closed magnetic path. Moreover, in order to protect the combination body which has arrange | positioned the coil to the magnetic core from an external environment, the thing of the structure where the resin part was formed in the circumference | surroundings of the combination body is known (refer patent document 1, 2). . Specifically, the assembly is stored in a case and the assembly is sealed with resin (potting type), or the assembly is stored in a mold and the combination is molded with resin ( Mold type).

  On the other hand, it is known that the resin is filled in a vacuum in order to prevent bubbles from being mixed into the resin when the resin is filled in the case containing the combination of the coil and the magnetic core ( (See Patent Document 3).

JP 2007-134374 A JP 2012-119454 A JP 2010-263076 A

  Development of a reactor with excellent quietness is desired.

  If air bubbles remain in the resin portion formed around the combination of the coil and the magnetic core, a crack may be generated starting from that portion, and this crack may be one of the causes of noise generation. Therefore, a small amount of bubbles remaining in the resin portion is one of the effective elements in terms of enhancing the quietness.

  In the prior art, since the atmosphere when filling the resin is evacuated, a manufacturing facility such as a vacuum chamber is required, and it takes time to evacuate the vacuum chamber. is there.

  The present invention has been made in view of the above circumstances, and one of its purposes is to provide a reactor having excellent silence.

  The reactor of the present application includes a coil, a magnetic core in which the coil is disposed to form a closed magnetic path, and a resin portion formed around a combination of the coil and the magnetic core. And the said magnetic core has a compacting core piece formed with the compacting body of magnetic powder. The powder core piece has a coating layer formed of an inorganic material on at least a part of the surface facing the resin portion.

  Said reactor is excellent in silence.

It is a schematic perspective view which shows the reactor of Embodiment 1. FIG. 2 is a schematic exploded perspective view of a combination of a coil and a magnetic core provided in the reactor of Embodiment 1. FIG. 1 is an exploded schematic perspective view of a reactor according to a first embodiment. It is a schematic perspective view explaining the coating layer formed in the compacting core piece in the reactor of Embodiment 3. 1 is a schematic configuration diagram schematically showing a power supply system of a hybrid vehicle. It is a schematic circuit diagram which shows an example of the power converter device of embodiment provided with the converter of embodiment.

  As a result of diligent research by the present inventors, it has been found that when a powder compact (compact core piece) obtained by press-molding magnetic powder on a magnetic core is used, bubbles are likely to remain in the resin portion. This is because the powder core piece obtained by pressure-molding the magnetic powder has gaps in manufacturing, and if the powder core piece is not sufficiently deaerated when filled with resin, It is considered that air existing in the gap leaks from the surface of the core piece and remains in the resin part as bubbles. These bubbles rise upward due to the effect of buoyancy when the resin is in a liquid state before being cured, and thus increase on the upper surface side. Based on the above knowledge, the present inventor has made various studies on the configuration capable of preventing the air in the gap from leaking out from the dust core piece, and as a result, the present invention has been completed.

[Description of Embodiment of the Present Invention]
First, embodiments of the present invention will be listed and described.

  (1) A reactor according to the embodiment includes a coil, a magnetic core in which the coil is disposed to form a closed magnetic path, and a resin portion formed around the combination of the coil and the magnetic core. And a magnetic core has the compacting core piece formed with the compacting body of magnetic powder. The powder core piece has a coating layer formed of an inorganic material on at least a part of the surface facing the resin portion.

  According to the reactor described above, the coating layer is formed on the surface facing the resin portion in the powder core piece, so that air existing in the gap leaks from the surface of the powder core piece on which the coating layer is formed. Can be prevented. For this reason, it is possible to reduce the bubbles generated from the compacted core piece when filling the resin to form the resin portion, and to reduce the bubbles remaining in the resin portion. Therefore, the reactor excellent in silence can be provided. Further, since no vacuum equipment such as a vacuum chamber is required, the manufacturing cost can be reduced. Furthermore, when the coating layer is formed of an inorganic material, in addition to the function of preventing air leakage from the surface of the powder core piece, a heat conduction function and an insulating function can be imparted to the coating layer as will be described later.

  (2) As one form of an above-described reactor, it is mentioned that a compacting core piece has a coating layer on the whole surface facing a resin part.

  By forming the coating layer on the entire surface of the powder core piece that faces the resin portion, it is possible to further reduce the bubbles generated from the powder core piece and to reduce the bubbles remaining in the resin portion. Therefore, the quietness of the reactor can be further improved.

  (3) As one form of an above-described reactor, it is mentioned that a compacting core piece has a coating layer in surfaces other than a lower surface among the surfaces facing a resin part.

  The above-mentioned “lower surface” means a surface facing downward when the direction in which gravity acts when the resin portion is filled with resin is formed. The air leaking from the lower surface of the surface facing the resin portion in the powder core piece is originally less due to buoyancy. Therefore, if the coating layer is formed on the surface other than the lower surface of the powder core piece, bubbles generated from the powder core piece can be effectively reduced, and bubbles remaining in the resin portion can be effectively reduced. Therefore, the silence of the reactor can be effectively enhanced. In addition, the amount of the inorganic material can be reduced while the thickness of the powder core piece is reduced by the amount not having the coating layer on the lower surface.

  (4) As one form of an above-described reactor, it is mentioned that the compacting core piece which has a coating layer is an inner core part by which a coil is arrange | positioned.

  Depending on the inorganic material forming the coating layer, in addition to the function of preventing air leakage from the surface of the powder core piece, a thermal conduction function and an insulating function can be imparted to the coating layer. For example, when a coating layer is formed of a thermally conductive inorganic material, the coating layer can be provided with a heat conduction function, and when a coating layer is formed of an electrically insulating inorganic material, the coating layer is provided with an insulating function. Can do. The inner core portion in which the coil is arranged receives the heat from the coil and easily rises in temperature, and since the coil is arranged, it is difficult for the heat to escape and heat radiation. Therefore, the heat dissipation of the inner core portion can be enhanced by providing the coating layer with a heat conduction function. On the other hand, if the coating layer has an insulating function, the coating layer can provide electrical insulation from the coil, so the bobbin disposed between the coil and the inner core portion can be omitted, or the bobbin thickness can be reduced. The bobbin can be simplified. This bobbin is usually made of an electrically insulating resin. In addition, said "inner core part" means the part substantially arrange | positioned inside the coil among magnetic cores, for example, the edge part vicinity of the core piece which comprises an inner core part is the outer side of a coil. Also exposed to the inner core part.

  (5) As one form of an above-described reactor, it is mentioned that an inorganic material is at least 1 type of material selected from a metal, a ceramic, and glass.

Generally, a metal has thermal conductivity, and when the coating layer is formed of a metal, a thermal conduction function can be imparted to the coating layer. Examples of the metal include aluminum (Al), magnesium (Mg), copper (Cu), nickel (Ni), tin (Sn), lead (Pb), zinc (Zn), gold (Au), silver (Ag) or These alloys are mentioned. Moreover, ceramic and glass have electrical insulation, and when the coating layer is formed of ceramic or glass, an insulating function can be imparted to the coating layer. Examples of the ceramic include aluminum nitride (AlN), silicon carbide (SiC), boron nitride (BN), silicon nitride (Si ₃ N ₄ ), boron carbide (B ₄ C), and alumina (Al ₂ O ₃ ). It is done. Examples of the glass include glass containing silica (SiO ₂ ) as a component (for example, quartz glass).

  If the coating layer is formed of an inorganic material having a thermal conductivity of 30 W / m · K or more, a thermal conduction function can be effectively imparted to the coating layer. More preferably, the thermal conductivity is 60 W / m · K or more. All of the metals exemplified above have a thermal conductivity of 30 W / m · K or more. Among them, Al, Mg, Cu, Ni, Sn, Zn, Au, and Ag have a thermal conductivity of 60 W / m · K or more. If the coating layer is formed of an inorganic material having a dielectric breakdown voltage of 10 kV / mm or more, an insulating function can be effectively imparted to the coating layer. Both the ceramic and glass exemplified above have a dielectric breakdown voltage of 10 kV / mm or more. In particular, AlN and SiC may have a thermal conductivity of 60 W / m · K or more, and since they have both thermal conductivity and electrical insulation properties, the coating layer is effectively provided with a thermal conductivity function and an insulation function. Can do.

  (6) As one form of an above-described reactor, it is mentioned that the thickness of a coating layer is 10 micrometers or less.

  The coating layer has a thickness that satisfies the function of preventing air leakage from the surface of the powder core piece. By setting the thickness of the coating layer to 10 μm or less, it is possible to avoid the size of the powder core piece from becoming too large. The thickness of a coating layer should just be the thickness from which the effect which prevents the leakage of the air from the surface of a compacting core piece is acquired, for example, shall be 2 micrometers or more.

  (7) The converter which concerns on embodiment is provided with the reactor which concerns on any one embodiment of said (1)-(6).

  Since the converter described above includes the reactor excellent in silence, the converter is excellent in silence.

  (8) The power converter device which concerns on embodiment is provided with the converter which concerns on said embodiment.

  Since the above-described power conversion device includes the converter that is excellent in silence, it is excellent in silence.

[Details of the embodiment of the present invention]
Specific examples of embodiments of the present invention will be described below with reference to the drawings. In addition, this invention is not limited to these illustrations, is shown by the claim, and is intended that all the changes within the meaning and range equivalent to the claim are included.

[Embodiment 1]
<Overall structure of the reactor>
With reference to FIGS. 1-3, the reactor 1A of Embodiment 1 is demonstrated. Reactor 1A includes a coil 2, a magnetic core 3 in which the coil 2 is disposed to form a closed magnetic path, and a resin portion 6 (see FIG. 1) formed around the combined body 10 of the coil 2 and the magnetic core 3. Is provided. In the first embodiment, the reactor 1A includes a case 4 that houses the combined body 10 (see FIGS. 1 and 3). One of the features of the reactor 1A is that the magnetic core 2 has at least a portion of a powder core formed of a powder compact of magnetic powder, and at least one of the powder core pieces faces the resin portion 6. And a coating layer formed of an inorganic material on at least a part of the surface to be processed. Hereinafter, the configuration of the reactor 1A according to the first embodiment will be described in detail. In the following description, the opening side of the case 4 is described as “upper” and the bottom side is described as “lower”.

(coil)
As shown in FIGS. 2 and 3, the coil 2 includes a pair of coil elements 2a and 2b formed by spirally winding a winding 2w, and a connecting portion 2r for connecting both the coil elements 2a and 2b. Both coil elements 2a and 2b are formed in a hollow cylindrical shape with the same number of turns and the same winding direction, and are arranged in parallel (side by side) so that the respective axial directions are parallel. In this example, the coil 2 is formed by one continuous winding 2w, and the end surfaces of the coil elements 2a and 2b in the coil axis direction are substantially rectangular. Specifically, after one coil element 2a is formed from one end side to the other end side, the winding 2w drawn from the other end side is bent into a U shape to form a connecting portion 2r. The other coil element 2b is formed by forming from the other end side toward the one end side. The winding 2w is a covered rectangular wire having an insulating coating on the surface of a conductor made of a rectangular wire. The coil 2 (coil elements 2a and 2b) is an edgewise coil obtained by edgewise winding a covered rectangular wire.

  In the coil 2, each coil element 2a, 2b is formed by separate windings, and the winding ends on the other end side of each coil element are directly joined by welding, soldering, crimping, etc., or separately prepared conductive It is also possible to manufacture by joining via a connecting member (for example, a plate material) made of a conductive material. In this example, the end surfaces in the axial direction of the coil elements 2a and 2b have a substantially rectangular shape, but can be appropriately changed such as a substantially circular shape.

  The winding 2w is a covered wire having an insulating coating made of an electrically insulating material such as polyamideimide resin on the surface of a conductor made of a conductive material such as copper, aluminum, or an alloy thereof. The conductor is typically a round wire or a rectangular wire. When an edgewise coil using a rectangular wire is used for the winding 2w as in this example, a coil with a higher space factor than that when a round wire is used can be obtained. Therefore, the coil 2 (combined body 10) There are advantages such as being able to reduce the size. In this example, the winding 2w is an enameled wire whose conductor is copper and whose insulation coating is polyamideimide.

  Both winding ends 2e of the coil 2 are drawn out from the turn forming portion in an appropriate direction. Here, both winding end portions 2e of the coil 2 are drawn upward from the turn forming surface (coil upper surface) so as to be orthogonal to the coil axis direction, and are drawn from the opening of the case 4 (see FIG. 1). The ends of the coil 2 at both winding ends 2e are stripped of the insulation coating to expose the conductor, and this conductor exposed portion is electrically connected to an external device (not shown) such as a power source. A terminal fitting (not shown) is attached.

(Magnetic core)
As shown in FIG. 2, the magnetic core 3 includes a pair of columnar inner core portions 31, 31 and a pair of block-shaped outer core portions 32. The inner core portions 31, 31 are portions disposed inside the coil elements 2 a, 2 b arranged side by side and disposed inside the coil 2, respectively. The outer core portions 32 and 32 are portions outside the coil elements 2a and 2b and are portions where the coil 2 is not substantially disposed (that is, exposed from the coil 2). The magnetic core 3 has outer core portions 32 and 32 arranged so that the inner core portions 31 and 31 arranged side by side are sandwiched from both ends, and both end surfaces of the inner core portions 31 and 31 are arranged inside the outer core portions 32 and 32. Each of the end faces 32e is connected to each other to form an annular shape, and a closed magnetic circuit is formed when the coil 2 is energized. In this example, the inner core portion 31 has a quadrangular prism shape, and the outer core portion 32 has a rectangular block shape. However, the shape of the inner core portion 31 (core piece 31m and gap material 31g) and the shape of the outer core portion 32 are appropriately selected. be able to.

  The inner core portion 31 is a laminated member in which a plurality of core pieces 31m made of a soft magnetic material and gap members 31g made of a material having a lower relative permeability than the core pieces 31m are alternately laminated. When the core piece 31m and the gap member 31g are bonded with an adhesive, it is expected that the core piece 31m and the gap member 31g can be easily handled and noise can be reduced by firmly bonding the core piece 31m and the gap member 31g. In addition, the core piece 31m and the gap material 31g may be bonded by an adhesive tape or the like. The outer core portion 32 is one core piece made of a soft magnetic material. On the other hand, a known material can be used as the gap material 31g. For the gap material 31g, a nonmagnetic material such as alumina or unsaturated polyester, a mixture containing a nonmagnetic material such as polyphenylene sulfide (PPS) resin and magnetic powder (for example, soft magnetic powder such as iron powder), or the like is used. Can do.

(Powder compact (powder core piece))
The core piece 31m and the outer core portion 32 (that is, all the core pieces constituting the magnetic core 3) constituting the inner core portion 31 are both compacted bodies (compact core pieces) obtained by pressure-molding soft magnetic powder. ).

  The powder core piece has voids, and the porosity is generally 5% by volume or more and 25% by volume or less, although it depends on the production conditions. The porosity can be measured by Archimedes method.

(Coating layer)
As shown in FIG. 2, a coating layer 35 made of an inorganic material is formed on the surfaces of the core piece 31m and the outer core part 32 (compact core piece) constituting the inner core part 31. Specifically, in the core piece 31m, the coating layer 35 is formed on the outer peripheral surface (upper surface, lower surface, and side surface), and the coating layer 35 is not formed on the end surface 31me in contact with the gap material 31g. On the other hand, in the outer core portion 32, a coating layer 35 is formed on a part of the outer peripheral surface, the outer end surface, and the inner end surface 32e, and the remaining surface of the inner end surface 32e with which the inner core portion 31 is in contact is covered. The layer 35 is not formed (that is, the coating layer 35 is formed on the inner end surface 32e other than the surface where the inner core portion 31 is in contact). The surface of the core piece 31m and the outer core portion 32 on which the coating layer 35 is formed is a surface facing the resin portion 6 (see FIG. 1) described later with the coating layer 35 interposed therebetween.

  As will be described later, the coating layer 35 is formed when the assembly 10 of the coil 2 and the magnetic core 3 is accommodated in the case 4 and then the resin is filled in the case 4 to form the resin portion 6. This prevents air existing in the gap from leaking from the surfaces of the core pieces (the core piece 31m and the outer core portion 32).

As a material for forming the covering layer 35, for example, an inorganic material such as metal, ceramic, glass, or the like can be used. Examples of the metal include Al, Mg, Cu, Ni, Sn, Pb, Zn, Au, Ag, and alloys thereof. Examples of the ceramic include AlN, SiC, BN, Si ₃ N ₄ , B ₄ C, and Al ₂ O ₃ . Examples of the glass include glass containing silica as a component (for example, quartz glass).

  When the coating layer 35 is formed of a metal having thermal conductivity, the coating layer 35 can be provided with a thermal conduction function. Any of the metals exemplified above has a thermal conductivity of 30 W / m · K or more, and has a high effect of imparting a thermal conductivity function. Among them, Al, Mg, Cu, Ni, Sn, Zn, Au, and Ag have a thermal conductivity of 60 W / m · K or more, and thus have a higher effect of imparting a heat conduction function. On the other hand, when the coating layer 35 is formed of an electrically insulating ceramic or glass, an insulating function can be imparted to the coating layer 35. The ceramic and glass exemplified above all have a dielectric breakdown voltage of 10 kV / mm or more, and have a high effect of imparting an insulating function. In particular, AlN and SiC may have a thermal conductivity of 60 W / m · K or more, and can effectively impart a heat conduction function and an insulation function.

  For example, the thickness of the coating layer 35 is 10 μm or less. The size of a compacting core piece can be made small because it is 10 micrometers or less. Moreover, it is preferable to set it as 2 micrometers or more from a viewpoint of preventing the leak of the air from the surface of a compacting core piece, for example.

  As a formation method of the coating layer 35, in the case of a metal, for example, a metal sheet is bonded to a powder core piece and attached or wound. As the metal sheet, in addition to a metal foil, a metal film formed on a plastic film can be used. Moreover, you may form into a film using a PVD (physical vapor deposition) method. In addition, for example, in the case of a low melting point metal having a melting point of 400 ° C. or less (eg, Sn, Pb or an alloy thereof), it is heat-bonded with a metal foil in contact with the powder core piece, The powder core piece is immersed in molten metal. In the case of ceramic, for example, a ceramic sheet may be adhered and pasted to a powder core piece, or a film may be formed using a PVD (physical vapor deposition) method or a CVD (chemical vapor deposition) method. As the ceramic sheet, a plastic film obtained by forming a ceramic film can also be used. In the case of glass, for example, a glass sheet may be adhered and pasted to a powder core piece, or a glass material may be applied, followed by heat treatment to form a glass film.

(Combination of coil and magnetic core)
After assembling the combined body 10 by assembling the coil 2 and the magnetic core 3, the combined body 10 is housed in the case 4 (see FIG. 3), and the resin is filled in the case 4 to form the resin portion 6. Thus, reactor 1A is completed (see FIG. 1). In this example, as shown in FIG. 2, the assembled body 10 is arranged by inserting inner core portions 31, 31 through coil insulators 2 a, 2 b through insulators 5, which will be described later, and then inner core portions 31, 31, It is produced by adhering both end faces of 31 and inner end faces 32e of the outer core portions 32, 32.

(Case)
As shown in FIG. 3, the case 4 includes a bottom plate portion 40 on which the combined body 10 is placed, and a side wall portion 41 that stands from the bottom plate portion 40 and surrounds the outer periphery of the combined body 10. Is formed in a box shape having an opening on the opposite side (that is, the upper surface). In this example, the case 4 has a bottom plate portion 40 and a side wall portion 41 formed integrally. In addition, the case 4 is generally formed of a metal material having a high thermal conductivity, and the entire case 4 can be used as a heat dissipation path, so that heat generated in the assembly 10 can be efficiently radiated to the outside. That is, the heat dissipation of the reactor can be improved. Examples of the metal material forming the case 4 include Al, Mg, Cu, Ag, or an alloy thereof, or iron, austenitic stainless steel, and the like. When the case 4 is formed of Al, Mg, or an alloy thereof, there is an advantage that the case 4 can be reduced in weight. The thickness of the case 4 (the bottom plate portion 40 and the side wall portion 41) is, for example, about 2 mm to 5 mm in consideration of strength, shielding properties, heat dissipation properties, soundproofing properties, and the like.

The case 4 can also be formed of an electrically insulating resin material. Examples of the resin material forming the case 4 include polybutylene terephthalate (PBT) resin, urethane resin, polyphenylene sulfide (PPS) resin, acrylonitrile-butadiene-styrene (ABS) resin, and the like. Further, the case 4 can be formed of different materials for the bottom plate portion 40 and the side wall portion 41. In that case, for example, the bottom plate portion 40 is formed of the above metal material, and the side wall portion 41 is formed of the above resin material. The resin material may contain a filler having high thermal conductivity (eg, AlN, SiC, BN, Si ₃ N ₄ , B ₄ C, Al ₂ O _3, etc.) from the viewpoint of improving heat dissipation. . In addition, a lid (not shown) may be attached to the opening of the case 4.

(Resin part)
The resin portion 6 shown in FIG. 1 is formed by filling the case 4 with a resin after housing the combination 10 in the case 4. Examples of the resin that forms the resin portion 6 include epoxy resin, urethane resin, acrylic resin, silicone resin, unsaturated polyester resin, PPS resin, and liquid crystal polymer (LCP). The resin portion 6 may contain the ceramic filler described above.

(Insulator)
The insulator 5 is a member for ensuring electrical insulation between the coil 2 and the magnetic core 3. In this example, as shown in FIG. 2, the insulator 5 is configured by combining a pair of divided pieces 50 and 50. The split piece 50 includes a plurality of plate pieces 51 respectively interposed between the inner peripheral surfaces of the coil elements 2a and 2b and the outer peripheral surface of the inner core portions 31 and 31, and end surfaces and outer core portions of the coil elements 2a and 2b. And a frame plate portion 52 interposed between the inner end surface 32e of the first and second inner end surfaces 32e. And the frame board part 52 is provided in the one end side of the board piece 51, and the insulator 5 is comprised by abutting the other end sides of the board piece 51. FIG. The shape of the insulator 5 shown in FIG. 2 is an exemplification, and can be changed as appropriate.

  The plate piece 51 is disposed between the coil element 2a (2b) and the inner core part 31, positions the coil element 2a (2b) with respect to the inner core part 31, and secures an electrical insulation distance therebetween. . In this example, the plate piece 51 covers only the vicinity of each corner portion of the outer peripheral surface of the inner core portion 31, and the plurality of plate pieces 51 so that the remaining surfaces of the inner core portion 31 are exposed from the plate piece 51. Is arranged. Therefore, when the resin is filled, the resin enters the space formed between the plate pieces 51, and the resin portion 6 is interposed between the inner peripheral surface of the coil element 2a (2b) and the outer peripheral surface of the inner core portion 31. Is done.

  The frame plate portion 52 is a substantially B-shaped flat plate portion having a pair of openings (through holes) into which the inner core portions 31 and 31 can be inserted. In this example, the frame plate part 52 has a flat partition part 52b arranged so as to be interposed between the coil elements 2a and 2b when the assembled body 10 is assembled. This partition part can be omitted. In the divided piece 50, the plate piece 51 and the frame plate portion 52 are integrally formed.

  As a material for forming the insulator 5 (divided piece 50), an electrically insulating resin such as PPS resin, polytetrafluoroethylene (PTFE) resin, PBT resin, or LCP can be used.

<Main effects of the reactor>
The reactor 1A described above has the following effects.
In the dust core pieces (core piece 31m and outer core portion 32) constituting the magnetic core 3, the dust layer 35 is formed on the surface facing the resin portion 6 so that the dust layer 35 is formed. It is possible to prevent air existing in the gap from leaking from the surface of the core piece. For this reason, when the resin portion 6 is formed by filling the resin, bubbles generated from the powder core piece can be reduced, and the bubbles remaining in the resin portion 6 can be reduced. Therefore, improvement in quietness can be expected.

  In the reactor 1A, since the coating layer 35 is formed on the entire surface of the dust core piece that faces the resin part 6, bubbles generated from the dust core piece can be further reduced, and bubbles remaining in the resin part 6 can be reduced. Can be reduced. Since all the powder core pieces constituting the magnetic core 3 have the coating layer 35, bubbles remaining in the resin portion 6 can be further reduced.

  Moreover, in the powdered core piece (core piece 31m) which comprises the inner core part 31, when the coating layer 35 is formed with the metal which has heat conductivity, the heat dissipation of the inner core part 31 is improved with the coating layer 35. be able to. On the other hand, when the coating layer 35 is formed of ceramic or glass having electrical insulation, the coating layer 35 can achieve electrical insulation from the coil 2 (coil elements 2a and 2b). Therefore, the insulator 5 arranged between the coil 2 and the inner core portion 31 can be omitted, or the insulator 5 can be simplified by reducing the thickness of the insulator 5. In particular, if the coating layer 35 is formed of AlN or SiC having both thermal conductivity and electrical insulation, it is possible to achieve electrical insulation from the coil 2 while improving the heat dissipation of the inner core portion 31.

  Furthermore, it can avoid that the size of the compacting core piece (the core piece 31m and the outer core part 32) becomes too large because the coating layer 35 is 10 μm or less.

  In addition, since there are few air bubbles remaining in the resin portion 6, heat conduction is less likely to be hindered by the air bubbles, and the heat generated in the assembly 10 through the resin portion 6 is efficiently transmitted to the outside (for example, the case 4). Can dissipate heat well. Moreover, since generation | occurrence | production of the crack which originates in the bubble which remains in the resin part 6 is suppressed, the function which protects the assembly 10 by the resin part 6 from an external environment other than the improvement of a quietness is maintained.

(Use of reactor)
Reactor 1A of the first embodiment described above is used for applications in which the energization conditions are, for example, maximum current (direct current): about 100 A to about 1000 A, average voltage: about 100 V to about 1000 V, and operating frequency: about 5 kHz to about 100 kHz, typically electric The present invention can be suitably used for in-vehicle converters and power converter components for automobiles and hybrid cars.

[Embodiment 2]
In the reactor 1A of the first embodiment, the form in which the coating layer 35 is formed on the entire surface of the dust core piece facing the resin portion 6 has been described. However, as the reactor of the second embodiment, It is mentioned that the coating layer 35 is formed on a surface other than the lower surface among the surfaces facing the resin portion 6. As a specific example, in the reactor 1A of the first embodiment, the coating layer 35 is formed on a surface (that is, an upper surface and a side surface) other than the lower surface of the outer peripheral surface of the dust core piece (the core piece 31m and the outer core portion 32). The coating layer 35 is not formed on the lower surface. In the reactor 1A, the surface of the case 4 that faces the bottom plate portion 40 corresponds to the lower surface (see FIG. 3).

  When the resin portion 6 is formed by filling the resin, the air leaking from the lower surface of the powder core piece is originally small because buoyancy acts. Therefore, even if the coating layer 35 is not formed on the lower surface of the powder core piece, as long as the coating layer is formed on a surface other than the lower surface of the powder core piece, bubbles generated from the powder core piece are generated. It can be effectively reduced. Therefore, even if it is a reactor of Embodiment 2, the bubble which remain | survives in the resin part 6 can be decreased effectively, and the improvement of noise reduction can be anticipated.

[Embodiment 3]
In the reactor 1A of the first embodiment, the form in which the coating layer 35 is formed on each of the powder core pieces has been described. However, as the reactor of the third embodiment, a series of the coating layers 35 are provided on a plurality of powder core pieces. Is formed. As a specific example, as shown in FIG. 4, in the inner core portion 31 in which the plurality of core pieces 31 m and the gap material 31 g described in the first embodiment are stacked, on the outer peripheral surface (surface facing the resin portion 6). One coating layer 35 is formed.

  In the reactor according to the third embodiment, the coating layer 35 is collectively formed on a plurality of dust core pieces, so that the trouble of forming the coating layer 35 on each dust core piece can be saved.

[Embodiment 4]
In the reactor 1A of the first embodiment, the form in which the coating layer 35 is not formed on the surface that does not face (not in contact with) the resin portion 6 in the powder core piece has been described. For example, a coating layer 35 may be formed on the surface of the core piece that does not face the resin portion 6. As a specific example, in the reactor 1A of the first embodiment, the coating layer 35 is also formed on the end surface 31me in contact with the gap material 31g of the core piece 31m and the surface in contact with the inner core portion 31 of the inner end surface 32e of the outer core portion 32. Has been.

  When a nonmagnetic inorganic material is employed as the material for forming the covering layer 35, the same function as the gap material 31g can be exhibited. That is, the coating layer 35 is formed on the entire end face of the core piece 31m and the inner end face 32e of the outer core part 32, so that the gap between the core pieces 31m and between the inner core part 31 and the outer core part 32 is increased. The intervening coating layer 35 functions as a magnetic gap. Therefore, in the reactor of the fourth embodiment, there is a possibility that the gap material 31g described in the first embodiment can be omitted. Examples of the nonmagnetic metal include metals other than Ni exemplified above. Moreover, the ceramics and glasses exemplified above are non-magnetic.

[Embodiment 5]
In the reactor 1A of the first embodiment, the case 4 that includes the case 4 that houses the combined body 10 and the resin portion 6 is formed by filling the resin in the case 4 has been described. However, as the reactor of the fifth embodiment, The case where the resin part 6 is formed by molding the combination 10 with resin using a mold (not shown) without providing the case 4 can be mentioned.

[Embodiment 6]
In the reactor 1A according to the first embodiment, the description has been given of the rectangular core shape in which the outer core portion 32 is disposed so as to sandwich the pair of inner core portions 31 in which the shapes of the magnetic cores 3 are arranged in parallel from both ends. However, the shape is not limited to this. Examples of the shape of the magnetic core include various shapes such as a toroidal type, an EE type, an EI type, and a pot type.

  Moreover, the magnetic core may be comprised by the several core piece as demonstrated in Embodiment 1, and may be comprised by one core piece. When the magnetic core is composed of a plurality of core pieces, the number of core pieces and the number of gap members formed by dividing the magnetic core may be set as appropriate so as to obtain desired magnetic characteristics.

[Embodiment 7]
In the reactor 1A of the first embodiment, the form in which all the core pieces constituting the magnetic core 3 are the dust core pieces has been described. However, as the reactor of the seventh embodiment, the magnetic core 3 includes the dust core pieces and the dust core. A form having a core piece made of a different material from the molded body can be mentioned. As the core piece different from the green compact, typically, a composite material formed by molding a mixture containing soft magnetic powder and resin, a soft magnetic thin plate having an insulating coating (for example, an electromagnetic wave represented by a silicon steel plate). And a laminate obtained by laminating steel plates). As a specific example, in the reactor 1A of the first embodiment, the core piece 31m constituting the inner core portion 31 is a compacted body, and the outer core portion 32 is a composite material. Conversely, the core piece 31m is a composite material. The outer core portion 32 may be a green compact. Alternatively, a part of the core piece 31m constituting the inner core part 31 may be a green compact and the remaining part may be a composite material.

  The green compact is typically made of an electrically insulating material (eg, an iron insulating material (eg, an iron-based material (pure iron or iron alloy), an alloy containing a rare earth metal)) on the surface of soft magnetic particles. Soft magnetic powder having an insulation coating made of silicone resin or phosphate) or mixed powder in which a binder (for example, a resin such as a thermoplastic resin or higher fatty acid) is appropriately mixed in addition to the soft magnetic powder. It can manufacture by performing heat processing suitably after pressure forming. Distortion introduced into the soft magnetic particles during molding can be removed by heat treatment, and a low-loss compact can be obtained. The higher the heat treatment temperature is, the higher the distortion can be removed, but the temperature at which the insulating coating is not damaged. The binder is lost by the heat treatment or changed into an insulator such as silica. By the above manufacturing method, an insulating coating (for example, a phosphoric acid compound, a silicon compound, a zirconium compound, an aluminum compound, a boron compound, etc.) is formed around the soft magnetic particles, and an insulating material is interposed between the particles. Is obtained. A compacted body of soft magnetic powder having an insulation coating is excellent in electrical insulation and can reduce eddy current loss. When the soft magnetic material is ferrite, even if it does not have an insulating coating, it has excellent electrical insulation.

  The composite material is obtained by dispersing soft magnetic powder (soft magnetic particles) in a resin serving as a binder. Typically, it can be manufactured by injection molding, transfer molding, MIM (Metal Injection Molding), cast molding, press molding using soft magnetic powder and powdered solid resin, or the like. Among the listed production methods, in methods other than press molding, a mixture of soft magnetic powder and resin is filled in a mold and molded, and then the resin is appropriately cured to easily form a desired three-dimensional composite material. can get. For example, an epoxy resin, a phenol resin, a silicone resin, or a urethane resin can be used as the binder resin. In addition, thermoplastic resins such as PPS resin, polyimide resin, fluorine resin, and polyamide resin, room temperature curable resin, or low temperature curable resin can be used.

  As a material for forming the soft magnetic powder (soft magnetic particles), for example, an iron-based material such as pure iron or an iron alloy, a metal such as an alloy containing a rare earth element, or a non-metal such as ferrite can be used. Examples of iron alloys include Fe-Si alloys, Fe-Al alloys, Fe-N alloys, Fe-Ni alloys, Fe-C alloys, Fe-B alloys, Fe-Co alloys, Fe-P. Alloy, Fe—Ni—Co alloy, Fe—Al—Si alloy and the like. In the green compact, if pure iron powder is used as the soft magnetic material, the moldability is excellent and the core piece is easy to manufacture.

  In any of the green compact and the composite material, only a single material soft magnetic powder may be used, or a plurality of types of soft magnetic powders having different materials may be used in combination. Moreover, the average particle diameter of soft-magnetic powder is 1 micrometer or more and 1000 micrometers or less, for example, 10 micrometers or more and 500 micrometers or less are mentioned especially. You may use the mixed powder containing multiple types of powder (coarse powder and fine powder) from which a particle size differs. When the particle size is within the above range, for example, a composite material is excellent in fluidity of the mixture, and a core piece can be easily manufactured using injection molding or the like.

  The content of the soft magnetic powder in the green compact is more than 75% by volume, particularly 80% by volume or more when the green compact is 100%. In addition, compacted compacts can be made to adjust magnetic properties (especially by adjusting the material of soft magnetic powder, the mixing ratio of soft magnetic powder and binder, the thickness of insulation coating, etc., and adjusting the molding pressure. , Saturation magnetic flux density) can be changed. Use a soft magnetic material with a high saturation magnetic flux density (iron-based material is preferred over ferrite), increase the soft magnetic powder content by reducing the amount of binder, etc., or increase the molding pressure. Thus, a green compact with a high saturation magnetic flux density can be obtained. Examples of the magnetic properties of the green compact include a saturation magnetic flux density of 1.0 T or more, further 1.6 T or more, 1.8 T or more, 2 T or more, and a relative magnetic permeability of 50 or more and 500 or less.

  The content of the soft magnetic powder in the composite material may be 20 volume% or more and 75 volume% or less when the composite material is 100%. When the magnetic powder is 20% by volume or more, it is easy to ensure magnetic characteristics such as saturation magnetic flux density. When the magnetic powder is 75% by volume or less, it is easy to mix with the resin and the composite material is excellent in manufacturability. The content of the soft magnetic powder is 30% by volume or more, and further 40% by volume or more. Further, the content of the soft magnetic powder is 70% by volume or less, further 65% by volume or less, and 60% by volume or less.

  In addition to the soft magnetic powder and the resin, the composite material may contain a powder (filler) made of a nonmagnetic material such as ceramic such as alumina or silica. By mixing a filler having excellent thermal conductivity such as ceramic, it is possible to improve heat dissipation and suppress uneven distribution (uniform dispersion) of the soft magnetic powder. When the filler is finer than the soft magnetic powder, it is easy to suppress a decrease in the proportion of the soft magnetic powder due to the inclusion of the filler. When the content of the filler is 0.2% by mass or more and 20% by mass or less when the composite material is 100% by mass, the above effect can be sufficiently obtained.

  The composite material can change the magnetic properties by adjusting the material and content of the soft magnetic powder, the presence or absence of a filler, and the like. Further, since the composite material contains a resin, even if the soft magnetic powder is the same as the green compact, the saturation magnetic flux density and the relative permeability tend to be low. Examples of the magnetic properties of the composite material include a saturation magnetic flux density of 0.6 T or more, further 1.0 T or more, and a relative permeability of 5 or more and 50 or less, and further 10 or more and 35 or less. In this case, since the relative permeability is relatively low, for example, in the reactor 1A of the first embodiment, the gap material 31g can be omitted to form the magnetic core 3 having a gapless structure. If the gapless structure is used, the leakage magnetic flux in the gap portion can be reduced.

  Since the magnetic core is formed of partially different materials, a magnetic core having partially different magnetic characteristics can be obtained. As described above, when a green compact is used for the inner core part and a composite material is used for the outer core part, the saturation magnetic flux density of the inner core part is higher than that of the outer core part, and the relative permeability of the outer core part is high. Can be designed to be lower than the inner core. For example, in the reactor 1A of the first embodiment, the inner core portion 31 has a saturation magnetic flux density of 1.0 T or more, 1.2 times or more of the outer core portion 32, a relative permeability of 50 to 500, and the outer core portion 32 is The saturation magnetic flux density is 0.6 T or more, further less than the saturation magnetic flux density of the inner core portion 31, the relative magnetic permeability is 5 or more and 50 or less, and the relative magnetic permeability of the entire magnetic core 3 (including the gap material when including the gap material) The overall relative permeability) is 10 or more and 50 or less. When obtaining a constant magnetic flux, the higher the absolute value of the saturation magnetic flux density of the inner core part and the higher the saturation magnetic flux density of the inner core part relative to the outer core part, the smaller the cross-sectional area of the inner core part. it can. Therefore, the higher the saturation magnetic flux density of the inner core portion, the smaller the inner core portion's cross-sectional area when obtaining the same magnetic flux as the magnetic core having a uniform overall saturation magnetic flux density. Can be. The saturation magnetic flux density of the inner core part is preferably 1.8 T or more, more preferably 2 T or more, and 1.5 times or more, more preferably 1.8 times or more of the saturation magnetic flux density of the outer core part 32. On the other hand, if the relative permeability of the outer core portion is lower than that of the inner core portion, the magnetic flux easily passes through the inner core portion. Conversely, if the relative permeability of the outer core portion is higher than that of the inner core portion, It is easy to reduce the leakage flux.

  The relative permeability and saturation magnetic flux density are measured as follows. Using the same material as the core piece, a ring-shaped test piece having an outer diameter of 34 mm, an inner diameter of 20 mm, and a thickness of 5 mm is produced. The test piece is subjected to winding of 300 turns on the primary side and 20 turns on the secondary side, and the BH initial magnetization curve of the test piece is measured in the range of H = 0 to 100 Oersted (Oe). For this measurement, for example, a BH curve tracer “BHS-40S10K” manufactured by Riken Denshi Co., Ltd. can be used. Then, the maximum value of the gradient (B / H) of the obtained BH initial magnetization curve is obtained, and this maximum value is set as the relative permeability. Normally, the gradient (B / H) of the BH initial magnetization curve becomes maximum at around H = 0 or H = 0. The magnetization curve here is a so-called DC magnetization curve, which is different from the AC relative permeability measured in an AC magnetic field. On the other hand, the saturation magnetic flux density is defined as a magnetic flux density when a magnetic field of 10,000 (Oe) is applied to the test piece with an electromagnet and sufficiently magnetically saturated.

[Embodiment 8]
The reactor of Embodiment 1-7 mentioned above can be utilized for the component of a converter mounted in a vehicle etc., and the component of a power converter device provided with this converter, for example.

  For example, a vehicle 1200 such as a hybrid vehicle or an electric vehicle is used for traveling by being driven by a main battery 1210, a power converter 1100 connected to the main battery 1210, and power supplied from the main battery 1210 as shown in FIG. The motor (load) 1220 is provided. The motor 1220 is typically a three-phase AC motor, which drives the wheel 1250 when traveling and functions as a generator during regeneration. In the case of a hybrid vehicle, vehicle 1200 includes an engine in addition to motor 1220. In addition, in FIG. 5, although an inlet is shown as a charge location of the vehicle 1200, it can be set as the form provided with a plug.

  Power conversion device 1100 includes converter 1110 connected to main battery 1210 and inverter 1120 connected to converter 1110 and performing mutual conversion between direct current and alternating current. Converter 1110 shown in this example boosts the DC voltage (input voltage) of main battery 1210 of about 200V to 300V to about 400V to 700V and supplies power to inverter 1120 when vehicle 1200 is traveling. Converter 1110 steps down DC voltage (input voltage) output from motor 1220 via inverter 1120 to DC voltage suitable for main battery 1210 during regeneration, and charges main battery 1210. The inverter 1120 converts the direct current boosted by the converter 1110 into a predetermined alternating current when the vehicle 1200 is running, and supplies the motor 1220 with electric power. During regeneration, the alternating current output from the motor 1220 is converted into direct current and output to the converter 1110. To do.

  As shown in FIG. 6, the converter 1110 includes a plurality of switching elements 1111, a drive circuit 1112 that controls the operation of the switching elements 1111, and a reactor L, and converts input voltage by ON / OFF repetition (switching operation). (In this case, step-up / down pressure) is performed. For the switching element 1111, a power device such as a field effect transistor (FET) or an insulated gate bipolar transistor (IGBT) is used. The reactor L has the function of smoothing the change when the current is going to increase or decrease by the switching operation by utilizing the property of the coil that prevents the change of the current to flow through the circuit. As this reactor L, the reactor of Embodiments 1-7, etc. are provided. By providing the reactor having excellent silence, the power conversion device 1100 and the converter 1110 have excellent silence.

  Vehicle 1200 is connected to converter 1110, power supply converter 1150 connected to main battery 1210, sub-battery 1230 serving as a power source for auxiliary machinery 1240, and main battery 1210. Auxiliary power supply converter 1160 for converting high voltage to low voltage is provided. The converter 1110 typically performs DC-DC conversion, while the power supply device converter 1150 and the auxiliary power supply converter 1160 perform AC-DC conversion. Some power supply device converters 1150 perform DC-DC conversion. The reactor of the power supply device converter 1150 or the auxiliary power supply converter 1160 has the same configuration as that of the reactor of the first to seventh embodiments, and a reactor whose size and shape are appropriately changed can be used. In addition, the reactors of the first to seventh embodiments can be used for a converter that performs conversion of input power and that only performs step-up or only performs step-down.

[Appendix]
The following additional notes are disclosed in relation to the embodiment of the present invention described above.

(Appendix 1)
A reactor comprising a coil, a magnetic core in which the coil is disposed to form a closed magnetic path, and a resin portion formed around an assembly of the coil and the magnetic core,
The magnetic core has a dust core piece formed of a powder compact of magnetic powder,
The powder core piece has a coating layer formed of a resin material on at least a part of the surface facing the resin part,
A reactor in which the coating layer has a thickness of 10 μm or less.

  According to the reactor of above-mentioned supplementary note 1, the air existing in the gap from the surface of the powder core piece on which the coating layer is formed by forming the coating layer on the surface facing the resin portion in the powder core piece. Can be prevented from leaking out. For this reason, it is possible to reduce the bubbles generated from the compacted core piece when filling the resin to form the resin portion, and to reduce the bubbles remaining in the resin portion. Therefore, the reactor excellent in silence can be provided. Further, since no vacuum equipment such as a vacuum chamber is required, the manufacturing cost can be reduced. The thickness of a coating layer should just be the thickness from which the effect which prevents the leakage of the air from the surface of a compacting core piece is acquired, for example, shall be 2 micrometers or more. Furthermore, it can avoid that the size of a compacting core piece becomes large too much because the thickness of a coating layer shall be 10 micrometers or less.

  When the coating layer is formed of a resin material, examples of the resin material include alkyd resin, acrylic resin, epoxy resin, silicone resin, polyurethane resin, and fluorine resin. Moreover, as a formation method, the coating material which contains the above-mentioned resin as a component is applied to a powder core piece, or a powder core piece is immersed in a coating material, for example. Other forming methods include adhering and attaching the above resin sheet to the powder core piece or winding it.

  The reactor of the present invention includes various on-vehicle converters (typically DC-DC converters) mounted on vehicles such as hybrid vehicles, plug-in hybrid vehicles, electric vehicles, and fuel cell vehicles, and converters for air conditioners. It can utilize suitably for the component of a converter and a power converter device.

DESCRIPTION OF SYMBOLS 1A Reactor 10 Combination 2 Coil 2w Winding 2a, 2b Coil element 2r Connection part 2e Winding end part 3 Magnetic core 31 Inner core part 31m Core piece 31g Gap material 31me End face 32 Outer core part 32e Inner end face 35 Covering layer 4 Case 40 Bottom plate portion 41 Side wall portion 5 Insulator 50 Split piece 51 Plate piece 52 Frame plate portion 52b Partition portion 6 Resin portion 1100 Power conversion device 1110 Converter 1111 Switching element 1112 Drive circuit L Reactor 1120 Inverter 1150 Power supply device converter 1160 Auxiliary power supply Converter 1200 Vehicle 1210 Main battery 1220 Motor 1230 Sub battery 1240 Auxiliaries 1250 Wheel

Claims (8)

A reactor comprising a coil, a magnetic core in which the coil is disposed to form a closed magnetic path, and a resin portion formed around an assembly of the coil and the magnetic core,
The magnetic core has a dust core piece formed of a powder compact of magnetic powder,
The said powder core piece is a reactor which has the coating layer formed with the inorganic material in the at least one part surface of the surface facing the said resin part.   The reactor according to claim 1, wherein the powder core piece has the coating layer on the entire surface facing the resin portion.   The reactor according to claim 1, wherein the dust core piece has the coating layer on a surface other than a lower surface among surfaces facing the resin portion.   The reactor according to any one of claims 1 to 3, wherein the dust core piece having the coating layer is an inner core portion in which the coil is disposed.   The reactor according to any one of claims 1 to 4, wherein the inorganic material is at least one material selected from metal, ceramic, and glass.   The reactor according to any one of claims 1 to 5, wherein the coating layer has a thickness of 10 µm or less.   A converter comprising the reactor according to claim 1.   A power converter device comprising the converter according to claim 7.

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