JP5845022B2 - Magnetic circuit parts - Google Patents

Description

  The present invention relates to a magnetic circuit component such as a reactor used as a component of an in-vehicle DC-DC converter mounted on a vehicle such as a hybrid vehicle. In particular, the present invention relates to a magnetic circuit component having excellent productivity.

  2. Description of the Related Art Magnetic circuit components including a coil and a magnetic core in which the coil is arranged and forming a magnetic flux path (magnetic path) created by the coil are used in various fields. For example, a reactor is one of magnetic circuit components that perform voltage step-up and voltage step-down operations. As a reactor used for a circuit component of a converter mounted on a vehicle such as a hybrid vehicle, a cylindrical coil, an inner core portion disposed in the coil, and an exposed core portion exposed from the coil Examples thereof include a magnetic core that forms a closed magnetic circuit. Typically, there are a form having two cylindrical coils and a form having one cylindrical coil.

  Patent Document 1 discloses a form including a coil including a pair of cylindrical coil elements arranged side by side so that their axes are parallel to each other, and an annular magnetic core on which the coils are arranged. Patent Document 1 discloses a form in which a plurality of core pieces made of a compacted body obtained by compression-molding soft magnetic powder are combined as the annular magnetic core (particularly, FIG. 3 of Patent Document 1). The magnetic core includes a pair of columnar inner core portions respectively disposed in each coil element, and a pair of exposed core portions exposed from the coil without the coil element being disposed. Each inner core portion includes a plurality of core pieces, and each exposed core portion includes a single columnar core piece.

  On the other hand, in the form having a single cylindrical coil, as the magnetic core, the columnar inner core portion disposed in the coil and the coil are exposed so as to cover at least a part of the outer periphery and end face of the coil. And an exposed core portion to be disposed. Typically, the magnetic core uses a form called an E-I form, an E-E form, a pot form, or the like configured by combining an ER type core, an E type core, and an I type core. In this form, for example, the inner core part is constituted by at least one columnar core piece, and the exposed core part is constituted by a cylindrical core piece or a plate-like core piece. The form which comprises the core piece by which the part was shape | molded integrally is mentioned.

JP 2009-246222

  Improvement of productivity of magnetic circuit parts such as reactors is desired.

  When using powdered core pieces, increasing the molding speed (the number of core pieces that can be molded per unit time) can shorten the manufacturing time of the magnetic core, which in turn improves the productivity of magnetic circuit components such as reactors. Can contribute. In particular, in the form including the above-described pair of coil elements, the core piece constituting the exposed core part (hereinafter referred to as the exposed core piece) passes magnetic flux from one inner core part to the other inner core part. Usually, the volume is larger than each core piece constituting the inner core portion (hereinafter referred to as an inner core piece). Since the exposed core piece provided in the above-described E-I form is also arranged outside the coil, the outer shape tends to be larger and the volume tends to be larger than the inner core portion arranged inside the coil. Therefore, the time for forming one exposed core piece tends to take longer than the time for forming one inner core piece, and it is desired to improve the forming speed of the exposed core piece.

  Further, since the exposed core piece has a larger volume than the inner core piece, the spring back at the time of molding is large, and this spring back increases the friction with the molding die, and the molding die is easily worn. This also leads to a decrease in productivity of magnetic circuit components such as a reactor.

  Therefore, an object of the present invention is to provide a magnetic circuit component having excellent productivity.

  Although the core pieces used in one magnetic core are different in size as described above, usually the green compact that is the material has the same specifications (composition, density, particle size, magnetic properties, etc.) ) To produce. Specifically, in the production of each core piece, raw material powder made of the same material and having the same particle size is used and produced under the same production conditions (molding pressure, atmosphere, temperature, etc.). One reason for this is that if the specifications of the core pieces used in one magnetic core are the same, preparation of raw material powder and control of manufacturing conditions can be easily performed. A conventional reactor including a core piece made of a compacted body manufactured using the same raw material powder under the same manufacturing conditions is usually a core piece constituting the inner core portion: a particle size of particles constituting the inner core piece and Core piece constituting the exposed core portion: The particle diameter of the particles constituting the exposed core piece is the same.

  Here, in the case of using coarse powder as the raw powder of the green compact, compared with the case of using fine powder, (1) it is easier to fill the raw powder into the molding space of the molding die (powder feeding). The time is short), (2) the raw material powder is easily crushed and the molding speed can be improved, and (3) the raw material powder is easily crushed and the molding pressure is easily reduced. Therefore, when coarse powder is used as the raw material powder, the productivity of core pieces made of compacted compacts can be improved by reducing the pressing time and reducing the molding die wear by reducing the molding pressure. The productivity of the magnetic circuit component can be improved.

  However, the size of the particles constituting the green compact is affected by the size of the raw material powder. For example, when a raw material powder having a large particle size is used, each particle constituting the green compact is also large. The coarsening of the particles constituting the green compact tends to increase eddy current loss. Therefore, conventionally, the particle size of the raw material powder is set mainly for the purpose of reducing the loss, and the raw material powder having the same particle size (preferably fine particles) is used for both the inner core piece and the exposed core piece. And by manufacturing on the same conditions as mentioned above, all the several core pieces which comprise the magnetic core with which the conventional reactor is provided were comprised by the particle | grains of the substantially same particle diameter. Thus, conventionally, it has been considered that all core pieces preferably have a uniform particle size.

  As a result of investigations by the present inventors, a fine raw material powder is used for the inner core piece that is placed in the coil and easily causes eddy current loss, and a coarse raw material powder is used for the exposed core piece exposed from the coil. Also, when the inner core piece and the exposed core piece are prepared using the fine raw material powder (when the average particle diameter of the inner core piece and the average particle diameter of the exposed core piece are the same), the performance is comparable. And obtained knowledge that it can be used sufficiently. In the core piece obtained using the raw material powder, the particle size of the particles constituting the core piece differs depending on the particle size of the raw material powder. The present invention is based on the above findings.

The magnetic circuit component of the present invention includes a cylindrical coil and a magnetic core on which the coil is disposed. The magnetic core forms a closed magnetic path by an inner core portion disposed in the coil and an exposed core portion exposed from the coil. The magnetic core includes a plurality of core pieces formed of a compacted body obtained by compression-molding soft magnetic powder. The magnetic circuit component of the present invention is configured such that when the core piece constituting the exposed core portion is an exposed core piece and the core piece constituting the inner core portion is an inner core piece, at least one of the exposed core portions is constituted. The average particle diameter d _S of the exposed core piece is larger than the average particle diameter d _{M of} at least one inner core piece constituting the inner core portion. A method for measuring the average particle diameters d _M and d _S will be described later.

In the magnetic circuit component of the present invention, the average particle diameter of each core piece made of a compacted body, which is a main component of the magnetic core, is not uniform, and the average particle diameter is different in a part of the magnetic core. Specifically, as described above, the average particle diameter d _S of at least one exposed core piece is larger than the average particle diameter d _{M of} at least one inner core piece. With this configuration, the magnetic circuit component of the present invention can use a coarse particle powder having a large particle size as the raw material powder in the production of the exposed core piece. Therefore, the magnetic circuit component of the present invention can reduce the time for supplying powder to the molding die and the pressurizing time when manufacturing the exposed core piece, thereby improving the molding speed. In addition, since the magnetic circuit component of the present invention can reduce the molding pressure by using coarse powder in the production of the exposed core piece, the pressurization time can also be shortened. Furthermore, since the molding pressure can be reduced, the springback can be reduced, and consequently the wear of the molding die can be reduced. For these reasons, the magnetic circuit component of the present invention is excellent in productivity.

As one aspect of the present invention, when the ratio of the average particle diameter d _S of the exposed core piece to the average particle diameter d _M of the inner core piece is d _S / d _M , d _S / d _M is more than 1 and 10 or less. The form which is is mentioned.

In the above-mentioned form, since d _S / d _M is more than 1, in the production of the exposed core piece, one having a sufficiently larger particle diameter than the raw material powder used for the production of the inner core piece can be used. Therefore, the above-mentioned form can shorten the powder supply time, pressurization time, etc., or reduce the molding pressure, so that it is possible to improve the molding speed of the exposed core piece and reduce the wear of the molding die. . Further, in the above embodiment, since d _S / d _M is 10 or less, the particles constituting the exposed core piece do not become too large and the loss is low.

As one mode of the present invention, the average particle diameter d _M of the inner core piece is at 20μm or 100μm or less, an average particle diameter d _S of the exposed core pieces include forms is 100μm or more 200μm or less.

The said form can utilize what has a particle size sufficiently larger than the raw material powder used for manufacture of an inner core piece in manufacture of an exposed core piece. Therefore, the above-mentioned form can shorten the powder supply time, pressurization time, etc., or reduce the molding pressure, so that it is possible to improve the molding speed of the exposed core piece and reduce the wear of the molding die. . Further, in the above embodiment, the average particle diameter d _S of particles constituting the exposed core piece (hereinafter referred to as outer particles) is 200 μm or less, and the average particle diameter of the particles constituting the inner core piece (hereinafter referred to as inner particles). by d _M is 100μm or less, the outer particles does not become too large, and because the inner particles also sufficiently small, low loss. Furthermore, since the average particle diameter d _M of the inner particles is 20μm or more, as the raw material powder used in the production of the inner core piece, not too fine, available ones easy to handle size. From this point, the said form is excellent in productivity.

  As one form of this invention, the said coil has a pair of cylindrical coil element, the said magnetic core is a pair of inner core part arrange | positioned in each coil element, and the said coil element is not arrange | positioned, but the said coil The form which comprises a pair of exposed core part exposed from the element is mentioned. The magnetic core is formed in an annular shape by combining the inner core portion and the exposed core portion. Each inner core portion is composed of one or more inner core pieces. Each exposed core portion is composed of one or more exposed core pieces.

In the form including the pair of coil elements and the annular magnetic core, the volume of the exposed core pieces constituting each exposed core portion tends to be larger than that of one inner core piece as described above. A exposed core pieces of such large, in producing a mean particle diameter d _S is greater exposed core pieces, by coarse powder is available, the above embodiment, improvement in the productivity of the exposed core pieces It is expected that the contribution to Therefore, the said form is excellent in productivity of a magnetic circuit component.

As one form of the invention, the soft magnetic powder is made of the same composition, the density D _S of the at least one exposed core pieces constituting the exposed core portion, at least one inner core piece constituting the inner core portion The form is smaller than the density D _{M of} .

  The inventors of the present invention have a reactor in which the density of the exposed core piece is smaller than that of the inner core piece, compared with the conventional reactor in which the density of the inner core piece and the density of the exposed core piece are the same. We have the knowledge that it has performance and can be used sufficiently. Further, as a technique for reducing the density of the exposed core piece, it is conceivable to reduce the molding pressure during the production of the green compact. When the molding pressure is reduced, the spring back is reduced as described above, and the friction with the molding die can be reduced, so that the wear of the molding die can be reduced. Further, when the molding pressure is reduced, the pressurization time can be shortened as described above, so that the molding speed can be increased. Therefore, in addition to making the average particle size different between the inner core piece and the exposed core piece as described above, it is proposed to make the density of the exposed core piece smaller than the density of the inner core piece.

In the above-described embodiment, the density of each core piece made of a compacted body, which is a main component of the magnetic core, is not uniform, and the density is different in a part of the magnetic core. Specifically, as described above, the density D _S of at least one exposed core piece is smaller than the density D _{M of} at least one inner core piece. With this configuration, the above-described configuration can reduce the molding pressure in the production of the exposed core piece. Therefore, the molding speed can be improved by shortening the pressurizing time, and the wear of the molding die can be reduced by reducing the spring back. Can be planned. In this way, in addition to the difference in the average particle size of both core pieces between the inner core piece and the exposed core piece, the molding pressure can also be reduced by changing the density of both core pieces to improve the molding speed of the exposed core piece. Thus, the wear of the molding die can be reduced, and the above configuration can contribute to the improvement of the productivity of the magnetic circuit component.

  In recent years, in-vehicle components such as hybrid vehicles are desired to be reduced in weight to improve fuel efficiency, and magnetic circuit components such as reactors are also desired to be reduced in weight. As described above, the exposed core piece tends to be larger in volume than the inner core piece and may be three times the weight of one inner core piece or more, depending on the size of the magnetic circuit component. Therefore, the weight reduction of the exposed core piece is expected to contribute greatly to the weight reduction of the magnetic circuit components such as the reactor. In the above-described form, among the core pieces that are the main constituent members of the magnetic core, the density of the exposed core pieces (particularly those having a volume larger than that of the inner core pieces) is smaller than the density of the inner core pieces. be able to.

As one mode of the present invention, the difference the difference between the density D _S of the density D _M and the exposed core piece of the inner core piece D _M -D _S, for the density D _M of the inner core piece (D _M -D _When the ratio of _S ) is (D _M −D _S ) / D _M , (D _M −D _S ) / D _M is 1/80 or more. Alternatively, as one embodiment of the present invention, when the difference between the density D _M of the inner core piece and the density D _S of the exposed core piece is D _M −D _S , D _M −D _S is 0.1 g / cm ^3. The form which is the above is mentioned.

  In any of the above forms, since the density of the exposed core pieces is sufficiently small, the molding speed can be improved, the wear of the molding die can be reduced, and the weight can be reduced more effectively.

  A typical example of the magnetic circuit component of the present invention is a reactor. This reactor is excellent in productivity by including the exposed core piece composed of relatively coarse particles as described above.

  The magnetic circuit component of the present invention is excellent in productivity.

1 is a perspective view illustrating a schematic configuration of a reactor according to a first embodiment. FIG. 2A is an exploded perspective view of a magnetic core included in the reactor according to the first embodiment, and FIG. 2B is a front view schematically showing the reactor according to the first embodiment.

  Hereinafter, a reactor will be described in detail as an example of a magnetic circuit component according to an embodiment of the present invention with reference to the drawings. In the drawings, the same reference numerals indicate the same items.

(Embodiment 1)
A reactor 1 shown in FIG. 1 is a magnetic circuit component that is installed and used in an installation target such as a metal (typically aluminum) cooling base (not shown) having a refrigerant circulation path therein. The reactor 1 includes a coil 2 having a pair of cylindrical coil elements 2a and 2b, a pair of inner core portions 31 disposed in the coil elements 2a and 2b, respectively, and a pair of coil elements 2a and 2b not disposed. A magnetic core 3 that forms a closed magnetic path with the exposed core portion 32 is provided. The magnetic core 3 is mainly composed of a plurality of core pieces (an inner core piece 31m and an exposed core piece 32m) made of a powder compact. The basic shape / constituent member of the reactor 1 is the same as that of a conventional reactor including a pair of coil elements and a plurality of core pieces made of a compacted body. It is a feature of the reactor 1 is that the average particle diameter d _S of the exposed core pieces 32m is larger than the average grain size d _M of the inner core pieces 31m. Hereinafter, first, the basic shape of each component will be described, and then the method for manufacturing the core piece will be described in detail.

[coil]
The coil 2 includes a pair of coil elements 2a and 2b formed by spirally winding a single continuous winding 2w without a joint, and a portion of the winding 2w bent in a U shape. And a connecting portion 2r for connecting the coil elements 2a and 2b. Each coil element 2a, 2b is a hollow cylindrical body having the same number of turns, and is formed in parallel (side by side) so that the respective axial directions are parallel.

  The winding 2w is preferably a covered wire having an insulating layer made of an insulating material (typically an enamel layer made of polyamideimide) on the outer periphery of a conductor made of a conductive material such as copper, aluminum, or an alloy thereof. Available. As the conductor of the winding 2w, a rectangular wire having a rectangular cross section as well as a round wire having a circular cross section can be suitably used. The coil elements 2a and 2b are edgewise coils formed by edgewise winding a covered rectangular wire having an insulating layer.

  It is also possible to use a coil in which each coil element is produced by separate windings and the ends of the windings forming each coil element are joined and integrated by welding or cold welding.

  Both end portions of the winding 2w are appropriately extended from the turn forming portion, and a terminal member (not shown) made of a conductive material is connected to the conductor portion exposed by peeling off the insulating layer. An external device (not shown) such as a power source for supplying power is connected to the coil 2 through this terminal member. For connection between the conductor portion of the winding 2w and the terminal member, welding such as TIG welding, cold welding, soldering, or the like can be used.

[core]
"overall structure"
The magnetic core 3 will be described with reference to FIG. The magnetic core 3 has a pair of rectangular parallelepiped inner core portions 31 covered by the coil elements 2a and 2b (FIG. 1), respectively, arranged in parallel so that their axes are parallel to each other, and the coil elements 2a and 2b A pair of columnar exposed core portions 32 that are not covered and are exposed from the coil elements 2a and 2b are annular bodies arranged so as to sandwich the inner core portion 31 therebetween.

《Inner core part》
Each inner core portion 31 is an assembly of a plurality of rectangular parallelepiped inner core pieces 31m and a plurality of plate-shaped gap members 31g, and the inner core pieces 31m and the gap members 31g are alternately stacked. . This assembly is easy to handle as a laminate when bonded with an adhesive or an adhesive tape. The number of inner core pieces 31m and the thickness / arrangement location / number of gap members 31g can be appropriately selected according to the inductance of the reactor 1.

  The shape of the inner core portion 31 can be selected as appropriate. When the coil elements 2a and 2b (FIG. 1) have a shape along the inner peripheral shape, the gap between the coil elements 2a and 2b and the inner core portion 31 can be reduced, and the reactor 1 can be downsized. The shape of the inner core piece 31m may be selected so that the inner core portion 31 has a desired shape. Here, the inner core piece 31 is formed in a rectangular parallelepiped shape, but may be a cylindrical shape, a rounded rectangular parallelepiped shape in which corners are rounded to a desired angle, or the like. Here, each inner core piece 31m is made of a soft magnetic material (described later) having the same composition, and is formed by using raw material powder having the same average particle diameter and molded under the same manufacturing conditions (such as molding pressure). It is composed of a molded body, and the shape and size are the same.

  Each gap material 31g is a plate-like material disposed in a gap provided between the core pieces for adjusting the inductance of the reactor 1. The constituent material of the gap material 31g is a material having a relative permeability smaller than that of the core piece, typically a non-magnetic material such as alumina. Other constituent materials include a mixture of magnetic powder such as iron powder and non-magnetic resin such as phenol resin (relative magnetic permeability is about 1.1 to 10). When at least the gap material 31g interposed between the inner core piece 31m and the exposed core piece 32m of the gap material 31g is made of the above mixture, the leakage magnetic flux can be effectively reduced. At least one of the gap members 31g can be an air gap.

<Exposed core>
Each exposed core portion 32 is composed of one exposed core piece 32m. Here, each exposed core piece 32m is a prismatic body which is a rounded trapezoidal shape with a pair of opposing surfaces rounded at the corners. In each exposed core piece 32m, an inner end surface 32e that connects the pair of rounded trapezoidal surfaces 32u and 32d and sandwiches the pair of inner core portions 31 is formed by a flat surface. In each exposed core piece 32m, the other surface (hereinafter referred to as the outer peripheral surface) connecting the pair of rounded trapezoidal surfaces 32u and 32d is composed of a curved surface and a flat surface.

  Here, each exposed core piece 32m is a plane (the above-mentioned rounded trapezoidal shape surface) that tapers toward the side away from the inner core portion 31 when the annularly assembled magnetic core 3 is viewed in plan from its axial direction. The solid body has an inclined surface (a surface constituting a part of the outer peripheral surface) connected to the plane. In addition, the exposed core piece 32m can be a rectangular or trapezoidal prism body in which the pair of opposed surfaces described above are rectangular or trapezoidal and the outer peripheral surface is configured only by a flat surface. Each exposed core portion 32 can also be composed of a plurality of exposed core pieces.

Further, here, as shown in FIG. 2 (B), each exposed core piece 32m has a height h ₃₂ (a distance between a pair of rounded trapezoidal surfaces 32u and 32d = the axial direction of the coil 2 and the coil element). 2a, 2b is greater than the height h ₃₁ direction distance) of the inner core pieces 31m that is orthogonal to both the side-by-side direction (FIG. 1) (high).

As shown in FIG. 2 (B), the magnetic core 3 has a rounded trapezoidal surface 32d on the installation side in a state in which the reactor 1 is attached to the installation target, and protrudes from the surface on the installation side in the inner core portion 31. It can be. Alternatively, the magnetic core 3 has a configuration in which the rounded round trapezoidal surface 32d facing the rounded round trapezoidal surface 32d on the installation side protrudes beyond the surface facing the installation side in the inner core portion 31. Can do. Since the exposed core piece 32m is a powder compact, the above-described protruding portion can also be used for the magnetic path. Further, by providing this protruding portion, the projected area of the exposed core piece 32m (the area of the rounded trapezoidal surfaces 32u and 32d) can be reduced, and the installation area can be reduced. Here, the difference between the height h ₃₁ of the inner core pieces 31m and the height h ₃₂ of the exposed core pieces 32m: to h ₃₂ -h ₃₁ is about the width of the winding 2w (Figure 1) constituting the coil 2 Both heights h ₃₁ and h ₃₂ are adjusted. For this reason, the rounded trapezoidal surface 32d on the installation side of the exposed core piece 32m and the installation side surface of the coil 2 are substantially flush with each other. The difference in height: h ₃₂ −h ₃₁ (projection amount of the exposed core piece 32m) can be selected as appropriate.

  Thus, each of the exposed core pieces 32m connected to the two inner core portions 31 has a volume larger than that of the arbitrary inner core piece 31m. Here, each exposed core piece 32m is made of the same composition (the same soft magnetic material as the raw material powder used for the inner core piece 31m (described later)), and the same average particle diameter raw material powder is used. The production conditions (molding pressure, etc.) are the same, and the shape and size are the same. However, the average particle diameter of the raw material powder used for the exposed core piece 32m is larger than the average particle diameter of the raw material powder used for the inner core piece 31m. It should be noted that by adjusting the composition of the raw material powder, the exposed core pieces 32m may have different compositions, or the inner core pieces 31m and the exposed core pieces 32m may have different compositions.

Then, the reactor 1, either the exposed core pieces 32m has an average particle diameter d _S, larger than the average grain size d _M of either of the inner core pieces 31m. That is, in the reactor 1, the ratio of the average particle diameter d _S of the exposed core piece 32m to the average particle diameter d _M of the inner core piece 31m: d _S / d _M is more than 1. Here, the average particle diameter d _S of each exposed core piece 32m is the same, and the average particle diameter d _M of all the inner core pieces 31m is also the same.

Average particle size ratio: Typically, the larger the d _S / d _M , the larger the absolute value of the average particle size d _S of the exposed core piece 32m, and the larger the average particle size of the raw powder of the exposed core piece 32m. Coarse powder can be used. By using coarse powder as raw material powder, productivity of the exposed core piece 32m can be increased. When the ratio of the average particle diameters: d _S / d _M is 1.5 or more, further 2 or more, particularly 3 or more, the productivity of the exposed core piece 32m can be further increased. However, if the ratio of the average particle diameter: d _S / d _M is too large, the absolute value of the average particle diameter d _S of the exposed core piece 32m becomes too large, causing problems such as an increase in eddy current loss. Therefore, the upper limit of the ratio of average particle diameter: d _S / d _M is preferably about 5.

More specifically, the average particle diameter d _M of the inner core piece 31m is 20 μm to 100 μm, and the average particle diameter d _S of the exposed core piece 32 m is 100 μm to 200 μm (provided that d _M ≠ d _S ). Coil elements 2a to generate a magnetic flux, that the average particle size d _M of the inner core pieces 31m disposed within 2b (FIG. 1) satisfies the above range, the eddy current loss is small, and low loss reactor it can. It is possible to reduce the eddy current loss as the average particle diameter is small, the average particle diameter d _M of the inner core piece 31m is, 70 [mu] m or less, more 50μm or less.

When the average particle diameter d _S of the exposed core piece 32m is 100 μm or more, a raw material powder having a sufficiently large average particle diameter can be used, and the productivity of the exposed core piece 32m can be improved. The larger the average particle diameter d _S of the exposed core piece 32m, the larger the raw material powder can be used, and the productivity of the exposed core piece 32m can be further improved. Therefore, it is preferably 120 μm or more, more preferably 130 μm or more. . However, the average particle diameter d _S of the exposed core piece 32m is preferably 200 μm or less, and more preferably 170 μm or less because an excessive increase in eddy current loss will result.

[Other components]
In addition, in order to improve the insulation between the coil 2 and the magnetic core 3, an insulator made of an insulating resin can be provided. Or it can replace with an insulator and can be set as the coil molded object which coat | covered the inner periphery and outer periphery of each coil element with insulating resin. To protect the assembly of coil 2 and magnetic core 3 and to improve heat dissipation, etc., use a case where the outer periphery of the assembly is covered with an insulating resin, or a case made of a metal material. It can be housed or the assembly housed in the case can be covered with a sealing resin.

[Reactor manufacturing method]
The reactor 1 having the above configuration can be manufactured, for example, as follows. First, the coil 2, the inner core piece 31m, the exposed core piece 32m, the gap material 31g, and other insulators are prepared. Two inner core portions 31 are formed by alternately laminating inner core pieces 31m and gap members 31g. Next, an assembly in which the inner core portion 31 is inserted into each of the coil elements 2a and 2b is formed, and the end surface of each inner core portion 31 and the inner end surface 32e of the exposed core piece 32m (exposed core portion 32) (see FIG. By joining 2), a reactor 1 having a combination of a coil 2 and a magnetic core 3 is obtained. Furthermore, this combination may be housed in a case as described above or covered with a resin.

[Magnetic core piece]
Next, the raw material powder used for the inner core piece 31m and the exposed core piece 32m and the manufacturing method will be described. Both core pieces 31m and 32m can be basically manufactured by using a conventional method for manufacturing a green compact. Typically, after filling a raw material powder made of a magnetic material into a molding space formed by a cylindrical die provided with a through hole and a lower punch inserted into one opening of the through hole, When the raw material powder is pressed and compressed by the upper punch inserted into the other opening of the through hole and the lower punch and subjected to a predetermined pressure, the compression molded product is extracted from the die. The obtained compression-molded product can be used as it is, but is generally subjected to a heat treatment described later. Furthermore, the post-processing mentioned later may be given to the compression molded product and the heat-treated material which heat-processed. Accordingly, the green compact is typically in the form of any one of a compression molded product, a heat-treated product, and a post-treated product after being subjected to post-treatment.

≪Raw material powder≫
The raw material powder is particularly preferably a coated soft magnetic powder comprising soft magnetic particles made of a soft magnetic material and an insulating coating provided on the surface of the particles. When the coated soft magnetic powder is used, the inner core piece 31m and the exposed core piece 32m are composed of coated particles in which the soft magnetic particles are covered with the insulating coating (or an insulating material modified by heat treatment described later). It becomes a green compact. This green compact has high electrical resistance, can reduce eddy current loss, and has low loss due to the interposition of the insulating coating (insulator).

  Examples of soft magnetic materials include metal materials such as iron-based materials and rare earth metals, and non-metallic materials such as ferrite. In particular, when a form having an insulating coating is provided, an iron-based material containing 50% by mass or more of iron is preferable. For example, pure iron (Fe), other Fe-Si alloys, Fe-Al alloys, Fe-N alloys, Fe-Ni alloys, Fe-C alloys, Fe-B alloys, Fe-Co alloys There is one kind of iron alloy selected from alloys, Fe-P alloys, Fe-Ni-Co alloys, and Fe-Al-Si alloys. In particular, a compacted body made of pure iron in which 99% by mass or more is Fe can obtain a magnetic core having a high magnetic permeability and magnetic flux density, and a compacted body made of an iron alloy can easily reduce eddy current loss, A lower loss magnetic core can be obtained. The material is selected so that the inner core piece 31m and the exposed core piece 32m have a desired composition.

  The particle diameters of the soft magnetic particles are selected so that the average particle diameter of the inner core piece 31m and the average particle diameter of the exposed core piece 32m each have desired values. For example, the average particle size of the raw material powder of the inner core piece 31m is 20 μm to 100 μm, and the average particle size of the raw material powder of the exposed core piece 32m is 100 μm to 200 μm. The average particle size of the raw material powder of the inner core piece 31m is 20 μm or more, so that it has excellent fluidity and can suppress an increase in hysteresis loss, and the average particle size of the raw material powder of the exposed core piece 32m is 200 μm or less. Thus, when the obtained green compact is used for a magnetic core, eddy current loss can be effectively reduced even when used at a high frequency of 1 kHz or higher. When the average particle size of the raw material powder of the inner core piece 31m is 50 μm or more, it is easy to obtain the effect of reducing hysteresis loss and the powder is easy to handle. The average particle diameter refers to a particle diameter of particles in which the sum of masses from particles having a small particle diameter reaches 50% of the total mass in the particle diameter histogram, that is, 50% particle diameter (mass).

  As the insulating film, an appropriate insulating material having excellent insulating properties can be used. For example, the insulating material includes oxidation of one or more metal elements selected from Fe, Al, Ca, Mn, Zn, Mg, V, Cr, Y, Ba, Sr, and rare earth elements (excluding Y). Metal oxides such as oxides, nitrides and carbides, metal nitrides and metal carbides. Alternatively, examples of the insulating material include compounds other than the metal oxide, metal nitride, and metal carbide, for example, one or more compounds selected from phosphorus compounds, silicon compounds, zirconium compounds, and aluminum compounds. Other insulating materials include metal salt compounds, such as metal phosphate compounds (typically iron phosphate, manganese phosphate, zinc phosphate, calcium phosphate, etc.), borate metal salt compounds, silicate metal salt compounds, Examples include titanic acid metal salt compounds. In particular, since the metal phosphate compound is excellent in deformability, the insulation coating made of the metal phosphate compound can easily be deformed following the deformation of the soft magnetic particles during compression molding and is not easily damaged. If the powder which comprises is used, it will be easy to obtain the compacting body in which an insulating film exists in a healthy state. In addition, the insulating coating made of a metal phosphate compound has high adhesion to soft magnetic particles made of an iron-based material and is difficult to drop off from the surface of the particles.

  Examples of insulating materials other than the above include resins such as thermoplastic resins and non-thermoplastic resins and higher fatty acid salts. In particular, a silicon-based organic compound such as a silicone resin is excellent in heat resistance, so that it is difficult to be decomposed when the obtained compression-molded product is subjected to a heat treatment described later.

  For the formation of the insulating film, for example, a chemical conversion treatment such as a phosphate chemical conversion treatment can be used. In addition, for the formation of the insulating film, spraying of a solvent or sol-gel treatment using a precursor can be used. In the case where the insulating coating is formed from a silicone organic compound, wet coating using an organic solvent, direct coating using a mixer, or the like can be used.

  The thickness of the insulating coating provided in the soft magnetic particles is 10 nm or more and 1 μm or less. When it is 10 nm or more, insulation between soft magnetic particles can be secured, and when it is 1 μm or less, a decrease in the ratio of the magnetic component in the green compact can be suppressed due to the presence of the insulating coating. That is, when a magnetic core is produced with this compacting body, the remarkable fall of magnetic flux density can be suppressed. The thickness of the insulating coating is determined by composition analysis (analyzer using transmission electron microscope and energy dispersive X-ray spectroscopy: TEM-EDX) and inductively coupled plasma mass spectrometer (ICP-MS). In view of the amount of element obtained by the above, the equivalent thickness is derived, and further, the insulation film is directly observed by the TEM photograph to confirm that the order of the equivalent thickness derived earlier is an appropriate value. The average thickness determined by

  A lubricant can be added to the raw material powder. Examples of the lubricant include organic lubricants and inorganic substances such as boron nitride and graphite. Alternatively, a lubricant can be applied to a molding die (in particular, the inner peripheral surface of the die). By using these lubricants, it is possible to reduce the friction between the raw material powder or the compression molded product and the molding die, and to reduce the damage to the insulating coating due to the friction. Lubricant is a metal soap such as lithium stearate, a fatty acid amide such as stearic acid amide, a solid lubricant such as higher fatty acid amide such as ethylenebisstearic acid amide, a solid lubricant dispersed in a liquid medium such as water. Examples thereof include liquids and liquid lubricants. In addition, if the mold is molded in a heated state (warm molding), the moldability can be further improved. Of course, cold forming may be used.

≪Forming pressure≫
The molding pressure is 5 ton / cm ² (≈490 MPa) or more and 15 ton / cm ² (≈1470 MPa) or less. By using 5 ton / cm ² or more, the raw material powder can be sufficiently compressed, and the relative density of the green compact can be increased. By making the product to 15 ton / cm ² or less, the insulation film is damaged. Can be suppressed.

In particular, when using coarse powder (for example, an average particle size of 150 μm or more) as the raw material powder for the exposed core piece 32m, molding pressure for molding the inner core piece 31m and molding for molding the exposed core piece 32m The pressure can be made different. Specifically, the molding pressure of the exposed core piece 32m can be made smaller than the molding pressure of the inner core piece 31m. The smaller the molding pressure, the shorter the pressurization time and the higher the molding speed, so the smaller the molding pressure of the exposed core piece 32m is preferable. Specifically, the molding pressure P _S of the exposed core pieces 32m is include ^{5ton / cm 2 ~7ton / cm 2} , the molding pressure P _M of the inner core piece 31m ^{is, 7ton / cm 2 ~9ton / cm} 2 is (Where P _M ≠ P _S ).

≪Process after molding≫
The compression-molded product extracted from the die can be subjected to a heat treatment for the purpose of removing distortion caused by compression. By removing distortion, loss such as hysteresis loss can be reduced. The heat treatment conditions include heating temperature: about 300 ° C. to 800 ° C., holding time: 30 minutes to 60 minutes. The higher the heating temperature, the easier the distortion can be removed and the hysteresis loss can be reduced. However, if an insulating film is provided, the insulating film may thermally decompose and eddy current loss may increase, so the temperature should be lower than the thermal decomposition temperature. Is preferred. Typically, when the insulating coating is made of an amorphous phosphate such as iron phosphate or zinc phosphate, the heating temperature is preferably up to about 500 ° C., and is excellent in heat resistance such as a metal oxide or silicone resin. In the case of an insulating material, the heating temperature is raised to 550 ° C. or higher, further 600 ° C. or higher, particularly 650 ° C. or higher. The heating temperature and holding time may be appropriately selected according to the constituent material of the insulating coating. The atmosphere during the heat treatment is not particularly limited, but the oxidation of the soft magnetic particles can be prevented if a non-oxidizing atmosphere such as a nitrogen atmosphere or a low oxygen atmosphere with a low oxygen concentration is used.

  When using raw material powder that has an insulation coating, the insulation coating is damaged, such as when a compression molded product is extracted from the die after a predetermined pressure, and the deformed soft magnetic particles are electrically connected to each other. Where it became possible: A bridge may be formed. Therefore, post-treatment such as acid etching can be performed on the obtained compression-molded product or the heat-treated product subjected to the above-described heat treatment for the purpose of removing the bridge portion. In the post-treatment, for example, the treatment time and the concentration of the treatment liquid may be adjusted so that the loss becomes a predetermined magnitude or less.

<Effect>
Reactor 1 is an inner core constituting inner core portion 31 in which average particle diameter d _S of exposed core piece 32m constituting exposed core portion 32 exposed from coil 2 is covered by coil 2 (coil elements 2a, 2b). greater than the average particle diameter d _M pieces 31m. In this example, both the average particle diameter d _S of the exposed core pieces 32m is the same, since the average particle diameter d _M of each the core pieces 31m is the same both, the average particle diameter of each exposed core pieces 32m All of d _S is larger than the average particle diameter d _M of an arbitrary inner core piece 31m. Therefore, it is possible to use coarse powder that is easy to mold as the raw material powder of the exposed core piece 32m, and in the manufacturing process of the exposed core piece 32m, the powder feeding time and pressurizing time can be shortened to increase the molding speed. . Moreover, when using coarse-grained powder, a shaping | molding pressure can be made small. This also shortens the time for pressurization to a predetermined molding pressure, thereby increasing the molding speed of the exposed core piece 32m. In addition, since the molding pressure is low, the spring back of the compression molded product is reduced, and wear of the molding die due to the spring back can be reduced. For these reasons, the magnetic core 3 is excellent in productivity, and the reactor 1 including the magnetic core 3 as a constituent member is also excellent in productivity.

In particular, in the reactor 1 of the first embodiment, the height h ₃₂ of the exposed core piece 32m is larger than the height h ₃₁ of the inner core piece 31m, and the volume of the exposed core piece 32m is sufficiently larger than the inner core piece 31m. When manufacturing such an exposed core piece 32m, if the molding pressure is made the same as the molding pressure of the inner core piece 31m, the pressurization time tends to be long and the spring back tends to be large. Therefore, as in the reactor 1 of the first embodiment, when the exposed core piece 32m has a much larger volume than the inner core piece 31m, the average particle diameter d _S of the exposed core piece 32m is the average particle diameter of the inner core piece 31m. Making it larger than d _M is expected to contribute greatly to the productivity improvement of the magnetic core 3 and the reactor 1.

  In addition, in the reactor 1, since the surface on the installation side of the exposed core piece 32m and the surface on the installation side of the coil 2 are substantially flush, it is easy to stabilize when installing the reactor 1, and the coil 2 And since the magnetic core 3 is directly supported by the cooling base and the case, the heat dissipation is excellent.

(Modification 1)
In addition to the configuration described in the first embodiment, the average particle diameter d _S of the exposed core piece 32m is larger than the average particle diameter d _M of the inner core piece 31m, and the density D _S of the exposed core piece 32m is 31 m of the inner core piece 31m. The form is smaller than the density D _{M of} . More specifically, both the exposed core pieces 32m has a density D _S, less than the density D _M of either of the inner core pieces 31m. Here, the density D _S of the exposed core pieces 32m are the same. Moreover, the same also both the density D _M of all of the inner core pieces 31m.

Relative density D _M of the inner core pieces 31m, the difference between the density D _M of the inner core pieces 31m and density D _S of the exposed core pieces 32m: as D _M -D _S is large, typically, the exposed core pieces the absolute value of the density D _S of 32m is reduced, it increased the productivity of the exposed core pieces 32m. Therefore, the density ratio: (D _M −D _S ) / D _M is preferably 1/80 or more (0.0125 or more), 1/70 or more (0.0143 or more), 1/50 or more (0.02 or more), particularly 1/70 or more. If it is 20 (0.05 or more), the productivity of the exposed core piece 32m can be increased more effectively. However, if the ratio of density: (D _M −D _S ) / D _M is too large, the absolute value of the density D _S of the exposed core piece 32m becomes too small, and the leakage flux increases due to a decrease in the magnetic component. Invite the problem. Therefore, the upper limit of the density ratio: (D _M −D _S ) / D _M is preferably about 0.1.

Further, as the above-described density difference: D _M −D _S itself is larger, typically, the absolute value of the density D _S of the exposed core piece 32m becomes smaller, and the productivity of the exposed core piece 32m can be increased. Therefore, the density difference: D _M −D _S is preferably 0.1 g / cm ³ or more, 0.15 g / cm ³ or more, more preferably 0.2 g / cm ³ or more, and particularly 0.4 g / cm ³ or more. The productivity of can be increased more effectively. However, if the difference in density: D _M −D _S is too large, the absolute value of the density D _S of the exposed core piece 32m becomes too small, causing the above-described problems. Therefore, the difference in density: D _M − the upper limit of the D _S is about 0.8 g / cm ³ are preferred.

Reactor first modification, among the density D _S of the exposed core pieces 32m constituting the exposed core portions 32 are exposed from the coil 2 constitute the inner core portion 31 covered with the coil 2 (coil elements 2a, 2b) small it is than the density D _M of the core pieces 31m, in the production of exposed core pieces 32m, it is possible to reduce the molding pressure. Therefore, in the reactor of the first modification, it is possible to improve the molding speed of the exposed core piece 32m and reduce the wear of the molding die. For these reasons, the magnetic core 3 is excellent in productivity, and the reactor of the first modification using the magnetic core 3 as a constituent member is also excellent in productivity.

In addition, the reactor of the first modification can effectively reduce the weight because the density D _S of the exposed core piece 32m having a larger volume than the inner core piece 31m is smaller than the density D _M of the inner core piece 31m. Can do.

(Modification 2)
In the first embodiment, the form in which the outer surface of the exposed core portion 32 protrudes from the outer surface of the inner core portion 31 has been described. The outer surface of the inner core part and the outer surface of the exposed core part may be flush with each other (not shown). Even in this embodiment, when each exposed core part is composed of one exposed core piece, each exposed core piece is connected to a pair of inner core parts, so each exposed core piece is one inner core piece. The volume becomes larger. Therefore, this form is also formed by using coarse powder as the raw powder of the exposed core piece because the average particle diameter d _S of the exposed core piece having a large volume is larger than the average particle diameter d _M of the inner core piece. The speed can be improved and the wear of the molding die can be reduced. Therefore, the reactor of Modification 2 is also excellent in productivity.

(Modification 3)
In the first embodiment, the mode in which the joint surface (inner end surface 32e) with the inner core portion 31 in the exposed core piece 32m constituting the exposed core portion 32 is a flat surface has been described. The exposed core piece may be a solid whose perspective plane shape is U-shaped. Even in this embodiment, when each exposed core part is composed of one exposed core piece, each exposed core piece is connected to a pair of inner core parts, so each exposed core piece is one inner core piece. The volume becomes larger. Therefore, this form is also formed by using coarse powder as the raw powder of the exposed core piece because the average particle diameter d _S of the exposed core piece having a large volume is larger than the average particle diameter d _M of the inner core piece. The speed can be improved and the wear of the molding die can be reduced. Therefore, the reactor of Modification 3 is also excellent in productivity. One exposed core piece may have the shape of the first embodiment, and the other exposed core piece may have the U-shaped body described above.

(Modification 4)
In the first embodiment, the configuration including the pair of coil elements 2a and 2b and the magnetic core 3 formed in an annular shape by the inner core portion 31 and the exposed core portion 32 has been described. As another form, the form provided with one cylindrical coil and the magnetic core by which this coil is arrange | positioned is mentioned. Examples of the magnetic core of this form include a form including a columnar inner core portion disposed in the one cylindrical coil and an exposed core portion exposed from the coil. The exposed core portion includes an outer peripheral core portion disposed so as to cover at least a part of the outer peripheral surface of the coil, and an end core portion disposed so as to cover at least a part of the end surface of the coil. It is done. As such a magnetic core, a magnetic core of a form called an EI form, an EE form, a pot form, etc. configured by combining an ER type core, an E type core, and an I type core can be used. More specifically, for example, one core piece (for example, a cylindrical core piece) constituting the outer peripheral core portion and a pair of core pieces (for example, a plate-shaped core piece) constituting the end core portion. A form having a plurality of core pieces, a form having a core piece integrally forming at least two core parts selected from an inner core part, an outer core part, and an end core part, etc. Can be mentioned. Since the exposed core piece constituting the exposed core portion is disposed so as to cover the outer peripheral surface and end face of the coil, the outer shape thereof is likely to be larger than the inner core piece. Therefore, the reactor of Modification 4 also uses coarse powder as the raw material powder for the exposed core piece because the average particle diameter d _S of at least one exposed core piece is larger than the average particle diameter d _M of the inner core piece. Thus, the molding speed can be improved and the wear of the molding die can be reduced. Therefore, the reactor of the modification 4 is also excellent in productivity.

(Test example)
A compacted body was produced under various conditions, a reactor was fabricated using the obtained compacted body, and the performance (iron loss and inductance) of the reactor was compared. Further, the molding speed of the green compact and the amount of wear of the molding die were examined.

  In this test, three reactors were produced. The material, shape, and size of the reactor of each sample were all the same. Specifically, a reactor including the coil having the pair of coil elements and the magnetic core having the pair of rectangular parallelepiped inner core portions and the pair of exposed core portions described in the first embodiment was manufactured. Sample No. 1 is a sample corresponding to Embodiment 1, and Sample No. 2 is a sample corresponding to Modification 1. Sample No. 100 is a comparative sample.

  A plurality of cuboid compacts (40 mm × 25 mm × 15 mm) were prepared for each of the pair of inner cores provided in each reactor, and each compact was used as an inner core piece. The number, shape, and size of the inner core pieces were the same for all samples. Each inner core portion is provided with a gap material, and the material, shape, and size of the gap material are the same for all samples.

  One compacted body was produced for each of the pair of exposed core portions provided in each reactor, and each compacted body was used as an exposed core piece. In this test, the exposed core piece was a rectangular parallelepiped shape of 70 mm × 50 mm × 25 mm. The volume of one exposed core piece is larger than the volume of one inner core piece.

  In any sample, the raw material powder is made of coated soft magnetic particles in which an insulating coating (thickness: about 20 nm or less) made of a metal phosphate compound is formed by chemical conversion treatment on pure iron powder produced by a water atomization method. A coating powder was prepared. In each test, a mixed powder obtained by mixing the powdered zinc stearate with the above-described coating powder (mixed amount of zinc stearate: 0.6% by mass with respect to the whole mixed powder) was used.

  In each of Sample Nos. 1 and 2, pure iron powder having an average particle size of 50 μm was used as the raw material powder for the inner core piece, and pure iron powder having an average particle size of 100 μm was used as the raw material powder for the exposed core piece. In sample No. 100, the inner core piece and the exposed core piece were formed using pure iron powder having an average particle diameter of 50 μm as the raw material powder. The average particle diameter is the 50% particle diameter (mass) described above.

The molding pressure of the inner core piece of sample No. 1 and ² was 7 ton / cm ² , and the molding pressure of the exposed core piece was sample No. 1: 6.5 ton / cm ² and sample No. 2: 6 ton / cm ² . On the other hand, in sample No. 100, the inner core piece and the exposed core piece had the same molding pressure of 7 ton / cm ² .

  The compression molded product of Sample Nos. 1, 2, 100 extracted from the die was subjected to heat treatment (400 ° C. × 30 minutes, nitrogen atmosphere) under the same conditions to obtain a heat treated product.

  The heat-treated product of Sample No. 1,2,100 obtained was post-treated under the same conditions to obtain a post-treated product. This post-treatment was performed by etching the surface of each heat-treated product with hydrochloric acid (concentration: 35% by mass).

  The obtained samples No. 1, 2,100 were treated as inner core pieces and exposed core pieces, and the densities of the inner core pieces and the exposed core pieces of sample Nos. 1, 2, 100 were measured. The results are shown in Table 1. The density was measured using the Archimedes method.

  The average particle size of the inner core piece and the exposed core piece of sample No. 1,2,100 was measured. The results are shown in Table 1. The average particle size was measured as follows. Each core piece includes the center of the pressure molding surface (surface formed by the upper punch or lower punch), and the area within 50% of the area of the pressure molding surface is the observation area, and the observation field is selected from the observation area. And observe with a microscope (about 100 to 1000 times). The obtained observation image is image-processed, the outline of the particle existing in the observation image is extracted, and the area of the outline is calculated. The calculation can be easily performed using a commercially available image processing apparatus. Circle having an area equal to the area within the outline of each particle: An equivalent area circle is obtained, the diameter of each equivalent area circle is taken as the diameter of each particle, and the average of the diameters of all particles present in the observation image is obtained. The average particle size at. The average particle diameter may be measured using an arbitrary cross section parallel to the pressing direction at the time of compression molding, or an arbitrary cross section orthogonal to the pressing direction, instead of the pressure forming surface. In this case, an area including the center of the cross section and within 50% of the area of the cross section is taken as an observation area. Since the insulating film is very thin, such as 20 nm or less, its thickness has little effect on the particle size of the particles constituting each core piece, so it is necessary to extract the contour including the insulating film. Allow.

  An annular magnetic core was formed using the inner core piece and the exposed core piece of sample Nos. 1, 2, 100, and a reactor in which a pair of coil elements were arranged on a part of this magnetic core (inner core part) was produced. Specifically, the inner core portion was inserted and arranged in each coil element, and the exposed core piece and the inner core portion were connected.

  Using the AC-BH curve tracer, the iron loss (W) at an excitation magnetic flux density Bm: 1 kG (= 0.1 T) and a measurement frequency: 5 kHz was measured for the reactor of the produced sample Nos. 1, 2,100. The results are shown in Table 1. In addition, the inductances of the reactors of the manufactured samples No. 1, 2,100 were examined. The results are shown in Table 1. The measurement condition of the inductance was set to a current carrying current (DC): 350A.

  Furthermore, for the exposed core piece, powder feeding → pressurization / compression / deaeration → extraction of the compression molded product is a series of processes, and the time required for this series of processes is measured to determine the molding speed (pieces / minute). It was. The results are shown in Table 1.

  In addition, the amount of wear of the molding die after continuously molding the compression molding used as the material of the exposed core piece was examined. The results are shown in Table 1. Here, the amount of wear is measured at the following locations on the inner peripheral surface of the die, and the contour shape (profile) of the measurement region is measured with a three-dimensional shape measuring machine. The measurement region is a portion in contact with the central portion in the thickness direction on the outer peripheral surface of the molded compression molded product in a state where the raw material powder is completely compressed (a state where a predetermined molding pressure is applied). Then, the difference between the contour shape of the measurement region before molding and the contour shape of the measurement region after molding 10,000 compression molded products is examined, and the maximum value of this difference is defined as wear amount: die wear amount.

As shown in Table 1, each of the sample Nos. 1 and 2 in which the average particle diameter d _S of the exposed core piece is larger than the average particle diameter d _M of the inner core piece is the average particle diameter d _S , d of both core pieces. Compared to Sample No. 100 having the same _M, it can be seen that the loss is about the same or less and the inductance is about the same. That is, it can be seen that both sample Nos. 1 and 2 have performance comparable to the reactor of sample No. 100 and low loss. In addition, it can be seen that Sample Nos. 1 and 2 both have the same performance as Sample No. 100, but have a high molding speed of the exposed core piece and a small amount of die wear. The reason for this is that both sample Nos. 1 and 2 are raw material powders so that the average particle diameter d _S of the exposed core piece having a larger volume than the inner core piece is larger than the average particle diameter d _M of the inner core piece. This is probably because the use of coarse powder and the reduction of the molding pressure shortened the powder feeding time and pressurizing time and reduced the friction caused by springback. Further, in addition to the average particle diameter d _S of the exposed core piece being larger than the average particle diameter d _M of the inner core piece, the sample No. in which the density D _S of the exposed core piece is smaller than the density D _{M of the} inner core piece. 2 shows that the molding speed can be further improved and the die wear amount can be further reduced. This is probably because the molding pressure was reduced so that the density D _S of the exposed core pieces was reduced.

Sample No. 2 has an inner core piece density D _{M of} 7.2 g / cm ³ and an exposed core piece density D _S of 7.0 g / cm ³ , so the density ratio: D _S / It can be seen that the weight can be reduced with respect to the sample No. 100 in which D _M ≈0.972 and the density ratio: D _S / D _M = 1. In this test, two exposed core pieces of 70 mm × 50 mm × 25 mm are provided, so that sample No. 2 is (7.2−7.0) g / cm ³ × (7.0 cm × 5.0) with respect to sample No. 100. (cm x 2.5cm) x 2 pieces = 35g can be reduced in weight. Therefore, it can be said that the reactor of sample No. 2 can be suitably used for in-vehicle components that are required to be reduced in weight on the order of grams.

Further, from this test, the ratio of the average particle diameter d _S of the exposed core piece to the average particle diameter d _M of the inner core piece: d _S / d _M is more than 1 and 10 or less (in this test, 2 or more), If the average particle diameter d _M of the inner core piece is 20 μm or more and 100 μm or less, and the average particle diameter d _S of the exposed core piece is 100 μm or more and 200 μm or less (in this test, the inner core piece: 50 μm, the exposed core piece: 100 μm), It can be seen that the molding speed can be increased and the friction amount can be sufficiently reduced. Therefore, by adjusting the average particle size of the exposed core piece and the inner core piece to the above range, it is possible to improve productivity within a range where the desired performance (iron loss and inductance) does not substantially change. I can say that.

From the above, as a magnetic circuit component comprising a pair of coil elements and a magnetic core formed in an annular shape by combining a plurality of core pieces made of a powder compact, an exposed core part exposed from the coil elements is formed. By making the average particle diameter d _S of the core piece larger than the average particle diameter d _M of the inner core piece constituting the inner core portion arranged in the coil element, a magnetic circuit component such as a reactor having excellent productivity can be obtained. It can be said that it is obtained.

  The present invention is not limited to the above-described embodiment, and can be modified as appropriate without departing from the gist of the present invention. For example, the material / average particle diameter / shape of each core piece, the number of inner core pieces / exposed core pieces, and the like can be appropriately changed.

  The magnetic circuit component of the present invention can be suitably used for various reactors (on-vehicle components, components for power generation / transforming equipment, etc.). In particular, the magnetic circuit component of the present invention can be suitably used for a reactor provided in an in-vehicle power conversion device such as an in-vehicle converter mounted on a vehicle such as a hybrid vehicle, an electric vehicle, or a fuel cell vehicle.

1 Reactor 2 Coil 2a, 2b Coil element 2w Winding 2r Connection
3 Magnetic core 31 Inner core part 31m Inner core piece 31g Gap material
32 Exposed core part 32m Exposed core piece 32u, 32d Rounded trapezoidal surface 32e Inner end face

Claims (5)

A cylindrical coil;
A magnetic circuit component comprising an inner core portion disposed in the coil and a magnetic core that forms a closed magnetic path with an exposed core portion exposed from the coil,
The core may comprise a plurality of core pieces composed of green compact made of a soft magnetic powder,
When the core piece constituting the exposed core portion is an exposed core piece and the core piece constituting the inner core portion is an inner core piece, the average particle diameter d _{S of} at least one exposed core piece constituting the exposed core portion but at least one average particle diameter d magnitude I磁 magnetic circuit components than _M of the inner core piece constituting the inner core portion. When the ratio of the average particle diameter d _S of the exposed core pieces to the average particle diameter d _M of the inner core piece and d _S / d _M, 請 Motomeko 1 d _S / d _M is Ru der than 1 to 10 The magnetic circuit component described in 1. The average particle size d _M of the inner core piece is at 20μm or 100μm or less,
The magnetic circuit component according to 請 Motomeko 1 or claim 2 average particle diameter d _S is Ru der least 200μm below 100μm of the exposed core pieces. The coil has a pair of cylindrical coil elements,
The magnetic core includes a pair of inner core portions disposed in each coil element, and a pair of exposed core portions exposed from the coil element, where the coil elements are not disposed, and the inner core portion and the exposed core. It is formed into a ring by combining the parts,
Each Each inner core portion is composed of one or more of the inner core piece, each of the exposed core portion, 請 Motomeko 1 any one of claims 3 that consists of one or more of the exposed core pieces The magnetic circuit component described in 1. The magnetic circuit component, the magnetic circuit component according to any one of the reactor der Ru請 Motomeko 1 to claim 4.

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