Core piece, reactor, converter, power conversion device, and method for manufacturing core piece

Abstract

A core piece for constituting a magnetic core arranged inside and outside a coil comprises: a first part composed of a powder compact of soft magnetic powder; and a plurality of second parts composed of a molded body of a composite material in which soft magnetic powder is dispersed in a resin. The first part includes a first block section having a portion provided so as to face an end face of the coil, and a lower step section in which each edge portion of two mutually facing surfaces among a plurality of surfaces constituting the first block section is locally lowered. Each of the second parts includes a second block section that is arranged so as to face the side surface of the adjacent second part and has a side surface facing either the inner surface or the outer surface of the coil, and a protrusion provided at an edge of an end surface of the second block section so as to overlap the lower step section.

Description

Core piece, reactor, converter, power conversion device, and method for manufacturing core piece

[0001] The present disclosure relates to a core piece, a reactor, a converter, a power conversion device, and a method for manufacturing the core piece. This application claims priority based on Japanese Patent Application No. 2023-096752 filed on June 13, 2023, and incorporates by reference all of the contents of the Japanese application.

[0002] Patent Document 1 discloses a core piece formed by combining a first core piece and a second core piece. The first core piece is formed of a composite material molded body in which soft magnetic powder is dispersed in a resin. The second core piece is formed of a powder compact of soft magnetic powder. The core piece is manufactured by placing the second core piece in a mold and molding the first core piece around the second core piece. Hereinafter, the portion of the core piece formed of the powder compact will be referred to as the first portion, and the portion of the core piece formed of the composite material molded body will be referred to as the second portion.

[0003] JP 2022-45166 A

[0004] The core pieces disclosed herein are core pieces for constituting a magnetic core to be placed inside and outside a coil, and include a first portion composed of a powder compact of soft magnetic powder and a plurality of second portions composed of a compact of a composite material in which soft magnetic powder is dispersed in a resin. The first portion includes a first block portion having a portion facing an end face of the coil, and a lower step portion formed by locally lowering each edge of two opposing faces of the first block portion. Each of the plurality of second portions includes a second block portion having a side surface facing either the inner or outer surface of the coil and arranged to face the side surface of the adjacent second portion, and a protrusion provided on the edge of the end face of the second block portion so as to overlap the lower step portion.

[0005] FIG. 1 is a schematic perspective view showing a core lamination of embodiment 1. FIG. 2 is a schematic perspective view showing an exploded version of the core lamination of embodiment 1. FIG. 3 is a schematic perspective view showing a first portion of the core lamination of embodiment 1. FIG. 4 is a schematic configuration diagram explaining a method for manufacturing the core lamination of embodiment 1. FIG. 5 is a schematic perspective view showing a reactor of embodiment 1. FIG. 6 is a schematic view showing the flow of magnetic flux in a magnetic core of the reactor of embodiment 1. FIG. 7 is a schematic perspective view showing a core lamination of embodiment 2. FIG. 8 is a schematic perspective view showing an exploded version of the core lamination of embodiment 2. FIG. 9 is a schematic perspective view showing a reactor of embodiment 2. FIG. 10 is a configuration diagram schematically showing a power supply system of a hybrid vehicle. FIG. 11 is a circuit diagram showing an example of a power conversion device including a converter.

[0006] [Problem to be Solved by the Present Disclosure] In a core piece configured by combining a first portion and a second portion made of different materials, it is desirable that the first portion and the second portion are well bonded to each other. For example, even when a plurality of second portions configured independently of each other are bonded to the first portion, it is desirable that the first portion and each second portion are well bonded to each other.

[0007] One object of the present disclosure is to provide a core piece in which a first portion and a second portion made of different materials are well joined. Another object of the present disclosure is to provide a reactor including the core piece. Another object of the present disclosure is to provide a converter including the reactor. Another object of the present disclosure is to provide a power conversion device including the converter. Another object of the present disclosure is to provide a method for manufacturing a core piece in which a first portion and a second portion made of different materials are well joined.

[0008] [Advantages of the Present Disclosure] The core piece of the present disclosure is formed by favorably joining a first portion and a second portion made of different materials.

[0009] [Description of Embodiments of the Present Disclosure] First, embodiments of the present disclosure will be listed and described.

[0010] (1) A core piece according to an embodiment of the present disclosure is a core piece for constituting a magnetic core disposed inside and outside a coil, and includes a first portion formed of a compact of a soft magnetic powder and a plurality of second portions formed of a compact of a composite material in which soft magnetic powder is dispersed in a resin. The first portion includes a first block portion having a portion facing an end surface of the coil, and a lower step portion formed by locally lowering each edge of two of the plurality of surfaces forming the first block portion. Each of the plurality of second portions includes a second block portion having a side surface facing either the inner surface or the outer surface of the coil and arranged to face the side surface of the adjacent second portion, and a protrusion provided on the edge of the end surface of the second block portion so as to overlap the lower step portion.

[0011] A powder compact can have a higher content of soft magnetic powder in the compact than a composite material compact. A powder compact with a high content of soft magnetic powder has high magnetic permeability, but is prone to magnetic saturation. In particular, under high current operating conditions, powder compacts are prone to magnetic saturation and increased iron loss. A composite material compact has lower magnetic permeability than a powder compact, but is less prone to magnetic saturation under high current operating conditions and has low iron loss. Therefore, a core piece that combines a first portion made of a powder compact and a second portion made of a composite material compact has excellent magnetic properties even under high current.

[0012] The first portion made of a powder compact and the second portion made of a composite material compact are joined mainly at their opposing end faces. In addition to the joint between the end faces, the first portion and the second portion are also joined at the lower step provided in the first portion and the protrusion provided in the second portion. The lower step portions are provided on two surfaces of the first block portion of the first portion, and the protrusions are provided so as to overlap each of the lower step portions. In this configuration, the protrusions sandwich the first portion at the lower step portions. As described below, the core piece is manufactured by filling a mold in which partial core pieces are placed with composite material. The partial core piece becomes the first portion. The composite material filled in the mold solidifies while shrinking. The composite material that solidifies to overlap the lower step portion of the first portion becomes the protrusion. By providing the protrusion to overlap the lower step portion, the first portion and the second portion of the core piece are well joined together, even though they are made of different materials.

[0013] (2) In the core piece described in (1) above, the plurality of second portions may be configured independently of each other, and the first portion may have a low step portion corresponding to the protrusion of each of the plurality of second portions.

[0014] Even if the plurality of second parts are constructed independently of each other, the first part has a low step portion corresponding to the protrusion of each second part, so that the first part and the second part are joined well.

[0015] (3) In the core piece described in (1) or (2) above, the outer surface of the first portion at the joint between the lower step portion and the protrusion may be flush with the outer surfaces of each of the plurality of second portions.

[0016] If the outer surface of the first portion at the joint is flush with the outer surface of each second portion, the joint is less likely to interfere with a member facing the core piece, such as a coil.

[0017] (4) In the core piece according to any one of (1) to (3) above, the second portions may include molded bodies formed of composite materials different from one another.

[0018] The plurality of second portions include, for example, a portion arranged to face the inner surface of the coil and a portion arranged to face the outer surface of the coil. The portion arranged to face the inner surface of the coil is a portion arranged inside the coil. The portion arranged to face the outer surface of the coil is a portion arranged outside the coil. If the portion arranged inside the coil and the portion arranged outside the coil are made of moldings of different composite materials, it is easy to adjust the magnetic properties of the entire core piece.

[0019] (5) In the core piece described in (1) above, the protrusion includes a connecting protrusion connected to all of the plurality of second portions, and the connecting protrusion may be arranged on one of two mutually facing surfaces of the plurality of surfaces constituting the first block portion so as to continuously overlap both the low-stage portion and a portion other than the low-stage portion.

[0020] If the connecting protrusion is provided on one of the two surfaces so as to overlap not only the low step portion but also a portion other than the low step portion, the contact area between the first portion and the second portion can be increased, and the first portion and the second portion can be more easily joined. If the connecting protrusion is provided so as to overlap a portion other than the low step portion, a portion of the second portion is positioned so as to face the end face of the coil. By positioning a portion of the second portion so as to face the end face of the coil, the magnetic properties are superior even with a large current.

[0021] (6) A reactor according to an embodiment of the present disclosure comprises a magnetic core formed by combining first core pieces and second core pieces, and a coil arranged in a part of the magnetic core, and at least one of the first core pieces and the second core pieces is a core piece described in any one of (1) to (5) above.

[0022] A reactor equipped with a magnetic core including the core pieces has excellent magnetic properties.

[0023] (7) A converter according to an embodiment of the present disclosure includes the reactor described in (6) above.

[0024] A converter including the reactor has excellent magnetic properties.

[0025] (8) A power conversion device according to an embodiment of the present disclosure includes the converter described in (7) above.

[0026] A power conversion device including the converter has excellent magnetic properties.

[0027] (9) A method for manufacturing a core piece according to an embodiment of the present disclosure includes the steps of: preparing a mold having a first space and a plurality of second spaces that communicate with each other; arranging partial core pieces formed from a powder compact of soft magnetic powder in a space including the first space; and filling each of the plurality of second spaces with a composite material in which soft magnetic powder is dispersed in resin. Each of the plurality of second spaces extends in a direction intersecting the first space and is arranged side by side. The partial core piece includes a first block portion and a lower step portion in which each edge portion of two of the plurality of surfaces that face each other is locally lowered. In the filling step, the composite material is filled into each of the plurality of second spaces so as to overlap the lower step portion.

[0028] In the above-mentioned core piece manufacturing method, partial core pieces are placed in a space including the first space of a mold, and a composite material is filled into the second space, whereby the composite material covers the end faces of the partial core pieces and also covers the lower step portions. The composite material filled into the mold solidifies while shrinking. The partial core pieces become the first portion, and the composite material filled into the second space solidifies to become the second portion. The solidified composite material overlapping the lower step portions becomes protrusions. The lower step portions are provided on two surfaces of the first block portion of the partial core piece, and the protrusions are formed to overlap each of the lower step portions. In this configuration, the protrusions sandwich the partial core pieces at the lower step portions. In the above-mentioned core piece manufacturing method, the composite material solidifies so as to sandwich the two surfaces of the partial core pieces in addition to the end faces, making it possible to manufacture a core piece in which two portions made of different materials are well bonded to each other.

[0029] (10) In the method for manufacturing a core piece according to (9) above, in the filling step, at least two of the second spaces may be filled with different composite materials.

[0030] The composite material filled in each of the multiple second spaces, for example, constitutes a portion arranged to face the inner surface of the coil and a portion arranged to face the outer surface of the coil. The portion arranged to face the inner surface of the coil is the portion arranged inside the coil. The portion arranged to face the outer surface of the coil is the portion arranged outside the coil. If the portion arranged inside the coil and the portion arranged outside the coil are made of molded bodies of different composite materials, it is easy to adjust the magnetic properties of the entire core piece.

[0031] [Details of the Embodiments of the Present Disclosure] Specific examples of the embodiments of the present disclosure will be described below with reference to the drawings. The same reference numerals in the drawings indicate the same objects. In each drawing, for the convenience of explanation, some components may be exaggerated or simplified. The dimensional ratios of each part in the drawings may also differ from the actual ratios. Note that the present invention is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0032] <First Embodiment> <Core Laminate> A core laminate 1 of the first embodiment will be described with reference to FIGS. 1 to 3 . The core laminate 1 is a component of a reactor 7, which will be described later. As shown in FIG. 1 , the core laminate 1 is an integrated body formed integrally with a first portion 11 and a plurality of second portions 12. One of the features of the core laminate 1 of the first embodiment is that the first portion 11 and the plurality of second portions 12, which are made of different materials, are well joined. In the core laminate 1 of the first embodiment, the plurality of second portions 12 are formed independently of one another, and each second portion 12 is joined to the first portion 11. Below, the overall shape of the core laminate 1 will be described first, and then the configuration of the first portion 11 and each second portion 12 will be described.

[0033] [Overall Shape of Core Piece] The core piece 1 includes one middle core portion 21, two side core portions 3 and 4, and one end core portion 5. The core piece 1 has an E-shape configured by the middle core portion 21, the two side core portions 3 and 4, and the end core portion 5. In Figure 1, the boundary between the middle core portion 21 and the end core portion 5 is indicated by a two-dot chain line.

[0034] In the following description, the first direction D1, the second direction D2, and the third direction D3 may be used. The first direction D1 is a direction along the axis of the middle core portion 21 that moves away from the joint surface with the end core portion 5. The second direction D2 is a direction from the side core portion 3 toward the side core portion 4 along the alignment of the middle core portion 2 and the two side core portions 3, 4. The third direction D3 is a direction from the lower surface toward the upper surface of the core piece 1. The lower surface of the core piece 1 includes a second surface 112 of a first block portion 110 provided in a first region 11, which will be described later with reference to Figures 2 and 3. The upper surface of the core piece 1 includes a first surface 111 of the first block portion 110. The first direction D1, the second direction D2, and the third direction D3 are perpendicular to each other. In each drawing, the first direction D1, the second direction D2, and the third direction D3 are each indicated by a single arrow. Hereinafter, the opposite directions of the first direction D1, the second direction D2, and the third direction D3 may also be referred to as the first direction D1, the second direction D2, and the third direction D3, respectively.

[0035] The middle core portion 21 has a portion that is disposed inside the winding portion 90 (FIGS. 5 and 6) of the coil 9, which will be described later. The middle core portion 21 is a portion that extends in a direction intersecting with the end core portions 5, and may have a portion that is disposed outside the winding portion 90. In other words, the middle core portion 21 may have a portion that is disposed inside the winding portion 90 and a portion that is disposed outside the winding portion 90. The shape of the middle core portion 21 roughly corresponds to the inner peripheral shape of the winding portion 90. In this example, the middle core portion 21 is a rectangular block. The corners of the middle core portion 21 are rounded to fit the corners of the winding portion 90.

[0036] The two side core portions 3, 4 are arranged side by side with the middle core portion 21 outside the winding portion 90 ( FIGS. 5 and 6 ) of the coil 9, which will be described later. The two side core portions 3, 4 are arranged to sandwich the middle core portion 21 with a gap between them. The shape of each side core portion 3, 4 may be any shape that allows it to be arranged side by side with the middle core portion 21. In this example, each side core portion 3, 4 is a rectangular block body. In this example, the two side core portions 3, 4 have the same shape and dimensions. In this example, the length of each side core portion 3, 4 along the first direction D1 is longer than the length of the middle core portion 21 along the first direction D1. The length of each side core portion 3, 4 along the first direction D1 may be equal to or shorter than the length of the middle core portion 21 along the first direction D1. In this example, the length of each side core portion 3, 4 along the second direction D2 is shorter than the length of the middle core portion 21 along the second direction D2. In this example, the total length of each side core portion 3, 4 along the second direction D2 is shorter than the length of the middle core portion 21 along the second direction D2. The total length of each side core portion 3, 4 along the second direction D2 may be equal to or greater than the length of the middle core portion 21 along the second direction D2. In this example, the length of each side core portion 3, 4 along the third direction D3 is the same as the length of the middle core portion 21 along the third direction D3. The length of each side core portion 3, 4 along the third direction D3 may be shorter or longer than the length of the middle core portion 21 along the third direction D3. The shapes and dimensions of the two side core portions 3, 4 may be different.

[0037] The end core portion 5 is disposed outside the winding portion 90 ( FIGS. 5 and 6 ) of the coil 9, which will be described later, so as to connect the middle core portion 21 and the two side core portions 3, 4. The shape of the end core portion 5 may be any shape that connects the middle core portion 21 and the two side core portions 3, 4. In this example, the end core portion 5 is a rectangular block body. The length of the end core portion 5 along the third direction D3 is the same as the length of the middle core portion 21 along the third direction D3. The length of the end core portion 5 along the third direction D3 may be shorter or longer than the length of the middle core portion 21 along the third direction D3.

[0038] [First Section] The first section 11 is made of a powder compact of soft magnetic powder. As shown in Figures 2 and 3, the first section 11 includes a first block portion 110 and lower stage portions 115 and 116.

[0039] <Materials> The powder compact constituting the first portion 11 is obtained by pressing raw material powder containing soft magnetic powder. The powder compact can have a higher content of soft magnetic powder in the compact compared to a compact of a composite material described later. A powder compact with a higher content of soft magnetic powder has high magnetic permeability. The content of soft magnetic powder in the powder compact is, for example, more than 80% by volume, or even 85% by volume or more, when the powder compact is taken as 100% by volume. The raw material powder may contain a lubricant.

[0040] The soft magnetic powder is formed of, for example, soft magnetic metal particles, coated particles, or soft magnetic non-metal particles. The coated particles include soft magnetic metal particles and an insulating coating provided on the outer periphery of the soft magnetic metal particles. The soft magnetic metal is, for example, pure iron or an iron-based alloy. The iron-based alloy is, for example, an Fe—Si alloy or an Fe—Ni alloy. The insulating coating is, for example, a phosphate. The soft magnetic non-metal is, for example, ferrite.

[0041] <First Block Portion> The first block portion 110 is a block body having a portion provided to face an end surface 91 ( FIG. 6 ) of the winding portion 90 of the coil 9, which will be described later. The first block portion 110 of this example includes a portion of the middle core portion 21 and the end core portion 5. The first block portion 110 of this example has a T-shape constituted by the portion of the middle core portion 21 and the end core portion 5.

[0042] 2 and 3, the multiple surfaces that make up the first block portion 110 include a first surface 111, a second surface 112, and an end surface 113. The first surface 111 and the second surface 112 are surfaces that face each other in the third direction D3. The end surface 113 faces the end surfaces 123A, 123B, and 123C of each second portion 12 shown in FIG. 2. The end surface 113 is a surface that is joined to the end surfaces 123A, 123B, and 123C.

[0043] <Low step portion> The first surface 111 has a low step portion 115. The low step portion 115 is provided on the edge portion of the first surface 111. The low step portion 115 is a portion where the edge portion of the first surface 111 is locally lowered. In other words, the low step portion 115 is a portion that is lower and steps down than areas other than the edge portion of the first surface 111. In the first portion 11 having the low step portion 115, the density near the edge portion of the first surface 111 is equivalent to the density of other portions. In the first portion 11 having the low step portion 115, there are fewer cracks in the edge portion of the first surface 111.

[0044] The low step portion 115 may be provided continuously around the entire circumference of the first surface 111. In this example, the low step portion 115 is provided on the edge portion of the first surface 111 extending from the end core portion 5 to the middle core portion 21. When the low step portion 115 is provided continuously around the entire circumference of the first surface 111, the low step portion 115 and the protrusions 125 are well joined together regardless of the number of second portions 12, i.e., the number of protrusions 125. When the low step portion 115 is provided continuously around the entire circumference of the first surface 111, a portion of the low step portion 115 is covered by the protrusions 125. When the low step portion 115 is provided continuously around the entire circumference of the first surface 111 and the reactor 7 described later includes a molded resin portion 10, at least a portion of the remaining portion of the low step portion 115 may be covered by the molded resin portion 10.

[0045] The first surface 111 is flat except for its edges. The surface extending from this flat surface to the lower step 115 is an inclined surface. The bottom surface of the lower step 115 is flat. In this example, the lower step 115 has a frame-shaped flat surface that surrounds the outside of the inclined surface. The width of the flat surface that forms the bottom surface of the lower step 115 is very narrow. In this example, the end core portion 5 and the middle core portion 21 are flush with each other on the first surface 111.

[0046] The step in the low step portion 115 relative to a portion other than the edge of the first surface 111 is, for example, 1 mm or more and 10 mm or less. The step is the depth of the low step portion 115. If the step in the low step portion 115 is 1 mm or more, the protrusion 125 of the second portion 12, which will be described later, and the low step portion 115 are likely to be joined well. If the step in the low step portion 115 is 10 mm or less, the end surface 113 remains relatively. The step in the low step portion 115 may be 1 mm or more and 7 mm or less, 1 mm or more and 4 mm or less, or 1 mm or more and 3 mm or less.

[0047] As shown in FIG. 3 , the second surface 112 has a low step 116. The low step 116 is provided on the edge of the second surface 112. The low step 116 is a portion where the edge of the second surface 112 is locally lowered. In other words, the low step 116 is a portion that is lower than the rest of the second surface 112. In the first portion 11 having the low step 116, the density near the edge of the second surface 112 is equivalent to the density of other portions. In the first portion 11 having the low step 116, there are fewer cracks on the edge of the second surface 112.

[0048] The low step portion 116 may be provided continuously around the entire circumference of the second surface 112. In this example, the low step portion 116 is provided on the edge portion of the second surface 112 extending from the end core portion 5 to the middle core portion 21 shown in FIG. 1 . When the low step portion 116 is provided continuously around the entire circumference of the second surface 112, the low step portion 116 and the protrusions 126 are well joined together regardless of the number of second portions 12 shown in FIG. 2 , i.e., the number of protrusions 126. When the low step portion 116 is provided continuously around the entire circumference of the second surface 112, a portion of the low step portion 116 is covered by the protrusions 126. When the low step portion 116 is provided continuously around the entire circumference of the second surface 112 and the reactor 7 described later includes a molded resin portion 10, at least a portion of the remaining portion of the low step portion 116 may be covered by the molded resin portion 10 shown in FIG. 5 .

[0049] The second surface 112 is flat except for its edge. The surface extending from this flat surface to the lower step 116 is an inclined surface. The bottom surface of the lower step 116 is flat. In this example, the lower step 116 has a frame-shaped flat surface that surrounds the outside of the inclined surface. The width of the flat surface that forms the bottom surface of the lower step 116 is very narrow. In this example, the end core portion 5 and the middle core portion 21 are flush with each other on the second surface 112.

[0050] The step in the low step portion 116 relative to a portion other than the edge of the second surface 112 is, for example, 1 mm or more and 10 mm or less. The step is the depth of the low step portion 116. If the step in the low step portion 116 is 1 mm or more, the protrusion 126 of the second part 12, which will be described later, and the low step portion 116 are likely to be joined well. If the step in the low step portion 116 is 10 mm or less, the end surface 113 remains relatively. The step in the low step portion 116 may be 1 mm or more and 7 mm or less, 1 mm or more and 4 mm or less, or 1 mm or more and 3 mm or less.

[0051] [Second Region] Each of the multiple second regions 12 is formed from a molded body of a composite material in which soft magnetic powder is dispersed in resin. As shown in FIG. 2 , the core piece 1 of this example includes three second regions 12A, 12B, and 12C. The second region 12A includes a second block portion 120A and protrusions 125 and 126. The second region 12B includes a second block portion 120B and protrusions 125 and 126. The second region 12C includes a second block portion 120C and protrusions 125 and 126. The second regions 12A, 12B, and 12C are made of the same material. Hereinafter, second regions 12A, 12B, and 12C having the same configuration will be referred to as second regions 12 without distinction.

[0052] <Materials> The composite material compact that constitutes the second portion 12 is manufactured by filling a mold with raw material in which soft magnetic powder is mixed and dispersed in unsolidified resin, and then solidifying the resin. The magnetic properties of the composite material, such as the magnetic permeability or saturation magnetic flux density, can be easily reduced by adjusting the content of soft magnetic powder in the resin. In particular, the magnetic permeability of the composite material can be easily reduced by adjusting the content of soft magnetic powder to a low level. Although the composite material compact has lower magnetic permeability than the powder compact, it is less likely to become magnetically saturated under high-current operating conditions and has low iron loss. The composite material compact can be easily molded into complex shapes compared to the powder compact.

[0053] The soft magnetic powder forming the composite material compact is the same as the soft magnetic powder forming the powder compact described above. The content of the soft magnetic powder in the composite material compact is, for example, 20% by volume or more and 80% by volume or less, assuming the composite material to be 100% by volume.

[0054] The resin forming the composite material molded body is, for example, a thermosetting resin or a thermoplastic resin. Examples of thermosetting resins include epoxy resin, phenolic resin, silicone resin, and urethane resin. Examples of thermoplastic resins include polyphenylene sulfide (PPS) resin, polybutylene terephthalate (PBT), polyamide (PA) resin, liquid crystal polymer (LCP), polyimide (PI) resin, and fluororesin. Examples of polyamide resins include nylon 6, nylon 66, and nylon 9T. The resin content in the composite material molded body is, for example, 20% by volume or more and 80% by volume or less, assuming the composite material to be 100% by volume.

[0055] The composite material may contain a filler in addition to the resin. The filler contributes to improving heat dissipation. For example, a powder of a non-magnetic material such as ceramics or carbon nanotubes can be used as the filler. The ceramic is, for example, a metal or non-metal oxide, nitride, or carbide. An example of an oxide is alumina, silica, or magnesium oxide. An example of a nitride is silicon nitride, aluminum nitride, or boron nitride. An example of a carbide is silicon carbide.

[0056] <Second Block Portion> Each of the second block portions 120A, 120B, and 120C has a side surface facing either the inner surface 92 or the outer surface 93 ( FIG. 6 ) of the winding portion 90. As shown in FIG. 2 , each of the second block portions 120A, 120B, and 120C is arranged to face the side surface of the adjacent second block portion 120A, 120B, and 120C. Each of the second block portions 120A, 120B, and 120C has multiple side surfaces. It is sufficient that any one of the multiple side surfaces of each of the second block portions 120A, 120B, and 120C faces the side surface of the adjacent second block portion 120A, 120B, and 120C. The second block portion 120A arranged inside the winding portion 90 has a side surface facing the inner surface 92 of the winding portion 90. The second block portions 120B and 120C disposed outside the winding portion 90 have side surfaces facing the outer surface 93 of the winding portion 90 .

[0057] Each of the second block portions 120A, 120B, and 120C extends in a direction intersecting the end core portion 5 (FIG. 1) of the first block portion 110. In this example, each of the second block portions 120A, 120B, and 120C extends in the first direction D1.

[0058] The second block portion 120A is a block body arranged to face the inner surface 92 (FIG. 6) of the winding portion 90 of the coil 9, which will be described later. The second block portion 120A of this example includes a part of the middle core portion 21. The second block portion 120A of this example has an I-shape formed by a part of the middle core portion 21. The middle core portion 21 is formed by a part of the first block portion 110 and the entire second block portion 120A described above.

[0059] 2, the multiple surfaces constituting the second block portion 120A have an end surface 123A facing the first block portion 110. The end surface 123A is a surface joined to the end surface 113 of the first block portion 110.

[0060] The second block portion 120B is a block body arranged to face the outer surface 93 ( FIG. 6 ) of the winding portion 90. The second block portion 120B includes side core portions 3. The second block portion 120B has an I-shape formed by the side core portions 3. Similar to the second block portion 120A, the multiple surfaces forming the second block portion 120B also have end surfaces 123B facing the first block portion 110.

[0061] The second block portion 120C is a block body arranged to face the outer surface 93 ( FIG. 6 ) of the winding portion 90. The second block portion 120C includes side core portions 4. The second block portion 120C has an I-shape formed by the side core portions 4. Similar to the second block portion 120A, the multiple surfaces constituting the second block portion 120C also have end surfaces 123C facing the first block portion 110.

[0062] <Protrusions> The end faces 123A, 123B, and 123C are provided with protrusions 125 and 126. The protrusions 125 and 126 are provided on the edges of the end faces 123A, 123B, and 123C. The protrusions 125 and 126 are provided on the edges of the end faces 123A, 123B, and 123C at positions facing each other in the third direction D3. The protrusions 125 and 126 protrude from the end faces 123A, 123B, and 123C toward the end face 113 of the first portion 11. The protrusions 125 and 126 protrude in the first direction D1.

[0063] The protrusion 125 is arranged so as to overlap the low step portion 115 provided in the first portion 11. The protrusion 125 is arranged to correspond to the low step portion 115. In this example, the protrusion 125 is arranged continuously along the entire length of one side forming the end faces 123A, 123B, 123C. In this example, the protrusion 125 is a strip-shaped piece extending along the one side. In this example, the protrusion 125 is a strip-shaped piece extending along the second direction D2. The protruding length of the protrusion 125 corresponds to the width of the low step portion 115. The width of the low step portion 115 is the length of the low step portion 115 along the first direction D1. In this example, the protrusion 125 is arranged so as to fill the low step portion 115. When the protrusion 125 is provided so as to fill the lower step 115, the outer surface of the first section 11 and the outer surface of the second section 12 at the joint between the lower step 115 and the protrusion 125 are flush with each other.

[0064] The protrusion 125 provided on the end face 123A further includes extensions 127 that partially protrude from both ends of the protrusion 125 toward the end face 113 of the first section 11. The extensions 127 are protruding pieces that extend along the first direction D1. The extensions 127 are also provided so as to fill the lower step 115.

[0065] The protrusion 125 on the end surface 123B further includes extensions 127 that partially protrude in different directions from each end of the protrusion 125. The extension 127 on the first end of the protrusion 125 protrudes toward the end surface 113 of the first section 11. The extension 127 on the first end of the protrusion 125 is a protruding piece extending along the first direction D1. The extension 127 on the second end of the protrusion 125 protrudes further along the length of the protrusion 125. The extension 127 on the second end of the protrusion 125 is a protruding piece extending along the second direction D2. The first end of the protrusion 125 is located distal to the middle core portion 21 relative to the second end. The second end of the protrusion 125 is located proximal to the middle core portion 21 relative to the first end. Each extension 127 is arranged to fill the lower step portion 115.

[0066] Like the protrusion 125 provided on the end face 123B, the protrusion 125 provided on the end face 123C also further includes extension portions 127 that partially protrude in different directions from each end of the protrusion 125. The protrusion 125 provided on the end face 123C is provided symmetrically in the second direction D2 with the protrusion 125 provided on the end face 123B.

[0067] The protrusion 126 is arranged so as to overlap the low step portion 116 provided in the first portion 11. The protrusion 126 is arranged to correspond to the low step portion 116. In this example, the protrusion 126 is arranged continuously along the entire length of one side forming the end faces 123A, 123B, 123C. In this example, the protrusion 126 is a strip-shaped piece extending along the one side. In this example, the protrusion 126 is a strip-shaped piece extending along the second direction D2. The protruding length of the protrusion 126 corresponds to the width of the low step portion 116. The width of the low step portion 116 is the length of the low step portion 116 along the first direction D1. In this example, the protrusion 126 is arranged so as to fill the low step portion 116. When the protrusion 126 is provided so as to fill the lower step 116, the outer surface of the first section 11 and the outer surface of the second section 12 are flush with each other at the joint between the lower step 116 and the protrusion 126. Like the protrusion 125, the protrusion 126 also has an extension 127 formed of a protruding piece extending along the first direction D1 or the second direction D2.

[0068] The first portion 11 and the second portion 12A are joined at their opposing end faces 113, 123A and between the low step portions 115, 116 and the protrusions 125, 126. The first portion 11 and the second portion 12B are joined at their opposing end faces 113, 123B and between the low step portions 115, 116 and the protrusions 125, 126. The first portion 11 and the second portion 12C are joined at their opposing end faces 113, 123C and between the low step portions 115, 116 and the protrusions 125, 126. The low step portion 115 is provided on the first surface 111, the low step portion 116 is provided on the second surface 112, and the protrusions 125, 126 are provided to overlap the low step portions 115, 116. Therefore, the protrusions 125 and 126 sandwich the first portion 11 at the lower step portions 115 and 116 .

[0069] The multiple second regions 12 may include molded bodies made of different composite materials. For example, the second regions 12A and 12B may be molded bodies made of different composite materials. In this case, the second regions 12B and 12C may be molded bodies made of the same composite material. If the second regions 12B and 12C are molded bodies made of the same composite material, the region disposed within the winding portion 90 (FIG. 5) of the coil 9 (described later) and the region disposed outside the winding portion 90 will be molded bodies made of different composite materials. The second regions 12A, 12B, and 12C may be molded bodies made of different composite materials. Different composite materials refer to at least some of the types and contents of the constituent materials of the composite materials being different. Different types of constituent materials of the composite materials include different types of soft magnetic powder and different types of resin. Different types of soft magnetic powder refer to, for example, different compositions of the soft magnetic powder. Different contents of the constituent materials of the composite materials refer to different contents of the soft magnetic powder in the resin.

[0070] <<Method of Manufacturing Core Piece>> A method of manufacturing the core piece 1 of embodiment 1 will be described with reference to Fig. 4. The method of manufacturing the core piece 1 includes a first step of preparing a mold, a second step of arranging a partial core piece in the mold, and a third step of filling the mold with a composite material. The first step, second step, and third step are performed in this order.

[0071] [First Step] In the first step, a mold 300 is prepared, which has a first space 310 and a plurality of second spaces 321, 322, 323 that communicate with each other. The first space 310 is a space in which a partial core piece 370, which will be described later, is disposed. In FIG. 4, the partial core piece 370 is disposed in the first space 310. The first space 310 is a space that is disposed along the second direction D2. In this example, a portion of the partial core piece 370 that corresponds to the end core portion 5 ( FIG. 1 ) is disposed in the first space 310. The first space 310 has a size that allows the end core portion 5 of the partial core piece 370 to fit snugly.

[0072] The second spaces 321, 322, and 323 extend in a direction intersecting the first space 310 and are arranged side by side. The second spaces 321, 322, and 323 are arranged along the first direction D1. In this example, the length of the second space 321 located in the middle of the three second spaces 321, 322, and 323 along the first direction D1 is shorter than the second spaces 322 and 323 on either side. In this example, the lengths of the second spaces 322 and 323 on either side along the first direction D1 are the same. In this example, a portion of the second space 321 corresponds to the middle core portion 21 ( FIG. 1 ) of the partial core piece 370. The remaining portion of the second space 321 has a size corresponding to the second block portion 120A described above. The second block portion 120A corresponds to the middle core portion 21 described above. The second space 322 has a size corresponding to the second block portion 120B described above. The second block portion 120B corresponds to the above-described side core portion 3. The second space 323 has a size corresponding to the above-described second block portion 120C. The second block portion 120C corresponds to the above-described side core portion 4.

[0073] [Second Step] In the second step, the partial core piece 370 is disposed in the first space 310. The partial core piece 370 is the above-mentioned first portion 11, and is formed of a powder compact of soft magnetic powder.

[0074] The partial core piece 370 includes a first block portion and a lower step portion 375. The first block portion is the first block portion 110 of the first section 11 described above, and corresponds to a part of the middle core portion 2 and the end core portion 5. The lower step portion 375 is provided on each edge portion of two of the multiple surfaces that form the first block portion, which face each other. The lower step portion 375 is a portion where the edge portion of each of the two surfaces is locally lowered. The partial core piece 370 is manufactured by pressure-molding raw material powder containing soft magnetic powder. The raw material powder is pressed in the direction in which the two surfaces of the resulting partial core piece 370 face each other. During this pressure-molding, the lower step portion 375 is formed on the edge portion of each of the two surfaces. The two surfaces correspond to the first surface 111 and the second surface 112 of the first section 11 described above.

[0075] [Third Step] In the third step, a composite material in which soft magnetic powder is dispersed in resin is filled into each of the plurality of second spaces 321, 322, 323. The composite material is filled into each of the second spaces 321, 322, 323 through the sprue 330, the runner 340, and the gate 350. In this example, three runners 340 and gates 350 are provided corresponding to the three second spaces 321, 322, 323.

[0076] In the third step, the composite material is filled into each of the second spaces 321, 322, and 323 so as to overlap the low step portion 375 of the partial core piece 370. The composite material filled into each of the second spaces 321, 322, and 323 covers the end faces of the partial core piece 370 and also covers the low step portion 375. The composite material filled into each of the second spaces 321, 322, and 323 solidifies while shrinking. The partial core piece 370 becomes the first portion 11, and the composite material filled into each of the second spaces 321, 322, and 323 solidifies to become the second portion 12. The composite material solidified so as to overlap the low step portion 375 becomes the protrusions 125 and 126 ( FIG. 2 ). In this example, the extension portion 127 ( FIG. 2 ) is also formed from the composite material solidified so as to overlap the low step portion 375. Since the low step portion 375 is provided on two sides of the first block portion of the partial core piece 370, the protrusions 125, 126 that are solidified and formed so as to overlap the low step portion 375 sandwich the partial core piece 370 in the low step portion 375.

[0077] In the third step, different composite materials can be filled into at least two of the multiple second spaces 321, 322, and 323. For example, the second space 322 and the second space 323 may be filled with the same composite material, and the second space 321 may be filled with a composite material different from that of the second spaces 322 and 323. The second spaces 321, 322, and 323 may be filled with different composite materials. In this example, the gates 350 are provided for each of the second spaces 321, 322, and 323, so that the second spaces 321, 322, and 323 can be filled with different composite materials.

[0078] In the core piece 1 obtained by the above-described core piece manufacturing method, gate marks are formed in each of the second portions 12A, 12B, and 12C. That is, the core piece 1 has three gate marks.

[0079] <Reactor> A reactor 7 of the first embodiment will be described with reference to Fig. 5 and Fig. 6 . The reactor 7 includes a magnetic core 8 and a coil 9. The magnetic core 8 is configured by combining first core laminations 81 and second core laminations 82. The coil 9 is disposed in a portion of the magnetic core 8. One of the features of the reactor 7 of the first embodiment is that at least one of the first core laminations 81 and the second core laminations 82 is the core lamination 1 described above. In this example, the first core laminations 81 are the core laminations 1 described above.

[0080] [Magnetic Core] The magnetic core 8 is a magnetic member for forming a circular magnetic path when the coil 9 is excited. The magnetic core 8 of this example is configured in an overall θ shape by combining first core pieces 81 and second core pieces 82. Below, the overall shape of the magnetic core 8 will first be described, and then the combination of the first core pieces 81 and the second core pieces 82 will be described.

[0081] <Overall Shape of Magnetic Core> The magnetic core 8 includes a middle core portion 2, two side core portions 3 and 4, and two end core portions 5 and 6. In Fig. 6, dashed two-dot lines indicate the boundaries between the middle core portion 2 and each of the end core portions 5 and 6. In Fig. 6, cross-hatching is applied to the portions of the magnetic core 8 that are made of a compacted powder formed from soft magnetic powder.

[0082] The middle core portion 2 has a portion that is disposed inside the winding portion 90 (FIGS. 5 and 6) of the coil 9, which will be described later. In this example, the middle core portion 2 is composed of the middle core portion 21 of the first core lamination 81, the middle core portion 22 of the second core lamination 82, and a gap. The middle core portion 22 of the second core lamination 82 has the same cross-sectional area as the middle core portion 21 of the first core lamination 81. The lengths of the middle core portion 21 and the middle core portion 22 along the second direction D2 are the same. The lengths of the middle core portion 21 and the middle core portion 22 along the third direction D3 are the same. A gap is provided between the middle core portion 21 of the first core lamination 81 and the middle core portion 22 of the second core lamination 82. Providing a gap makes it easy to adjust the inductance of the reactor 7. For example, a gap material (not shown) is disposed in the gap. Known gap materials can be used for the gap material. The gap material is formed of, for example, non-magnetic ceramics or resin. The gap may be an air gap without a gap material. When the reactor 7 includes a molded resin portion 10 described later, the gap may be filled with a resin that forms the molded resin portion 10. In this case, the resin that forms the molded resin portion 10 serves as a gap material.

[0083] The length of the middle core portion 2 in the first direction D1 is equal to or greater than the length of a winding portion 90 ( FIGS. 5 and 6 ) of the coil 9, which will be described later, in the first direction D1. In this example, the length of the middle core portion 2 in the first direction D1 is slightly longer than the length of the winding portion 90 in the first direction D1. In other words, the middle core portion 2 has a portion that is disposed inside the winding portion 90 and a portion that is disposed outside the winding portion 90. Both end portions of the middle core portion 2 are located outside the winding portion 90.

[0084] The two side core portions 3 and 4 are the first core pieces 81 , that is, the side core portions 3 and 4 of the core piece 1 described above.

[0085] Of the two end core portions 5, 6, one end core portion 5 is the end core portion 5 of the first core piece 81, i.e., the above-mentioned core piece 1. Of the two end core portions 5, 6, one end core portion 6 is the end core portion 6 of the second core piece 82. The end core portion 6 of the second core piece 82 has the same shape and size as the end core portion 5 of the core piece 1.

[0086] In the magnetic core 8, the middle core portion 2, the two side core portions 3 and 4, and the two end core portions 5 and 6 are connected, so that when the coil 9 described below is excited, magnetic flux flows and a closed magnetic circuit is formed. As shown by the dashed arrows in Figure 7, the magnetic flux flows from the middle core portion 2 to the end core portion 5, from the end core portion 5 to each of the two side core portions 3 and 4, from each of the side core portions 3 and 4 to the end core portion 6, and from the end core portion 6 to the middle core portion 2.

[0087] <Combination> The first core pieces 81 and the second core pieces 82 are split pieces that separate the magnetic core 8 in the first direction D1. In this example, the first core pieces 81 have an E-shape, and the second core pieces 82 have a T-shape. By combining the E-shaped first core pieces 81 and the T-shaped second core pieces 82, the magnetic core 8 has a θ-shape.

[0088] The first core lamination 81 of this example is the above-mentioned core lamination 1 and includes a first portion 11 and a second portion 12 .

[0089] The second core laminations 82 of this example are formed of a powder compact. That is, the second core laminations 82 of this example include only the first region 11. The second core laminations 82 may be formed of the first region 11, or may be formed of a composite of the first region 11 and the second region 12. When the second core laminations 82 are formed of a composite of the first region 11 and the second region 12, the first region 11 includes the end core portion 5, and the second region 12 includes the middle core portion 22. As with the core laminations 1 described above, the first region 11 and the second region 12 may be joined at the end faces 113, 123A, 123B, and 123C, and may also be joined at the lower step portions 115, 116 and the protrusions 125, 126.

[0090] The shape of the second core laminations 82 is not particularly limited. The shape of the second core laminations 82 may be, for example, E-shaped. The E-shaped second core laminations 82 include a middle core portion, two side core portions, and end core portions. In this case, it is sufficient to appropriately adjust the lengths of the middle core portion and two side core portions of the first core laminations 81 along the first direction D1, and the lengths of the middle core portion and two side core portions of the second core laminations 82 along the first direction D1.

[0091] [Coil] The coil 9 has at least one winding portion 90. In this example, the coil 9 has one winding portion 90. The winding portion 90 is formed by spirally winding a single wire. Both ends of the wire are drawn out from the respective ends of the winding portion 90. Terminal fittings (not shown) are attached to both ends of the wire drawn out from the winding portion 90. An external device (not shown) is connected to the terminal fittings. In Figures 5 and 6, only the winding portion 90 is shown, and the ends of the wire are omitted.

[0092] The winding may be a known winding. The winding in this example is a coated rectangular wire made of a conductor wire with an insulating coating. The conductor wire is formed of, for example, a copper rectangular wire. The insulating coating is made of, for example, enamel. The winding portion 90 in this example is an edgewise coil made by edgewise winding the coated rectangular wire.

[0093] The winding portion 90 has a rectangular cylindrical shape. That is, the end face 91 of the winding portion 90 in this example has a rectangular frame shape. The winding portion 90 has an inner surface 92 and an outer surface 93. The inner surface 92 faces the middle core portion 2. There is a gap between the inner surface 92 and the outer peripheral surface of the middle core portion 2. If the reactor 7 includes a molded resin portion 10 (described later), this gap is filled with resin that forms the molded resin portion 10. The outer surface 93 faces the side core portions 3 and 4. The end face 91 faces the end core portions 5 and 6. The corners of the winding portion 90 in this example are rounded. When the winding portion 90 has a rectangular cylindrical shape, the contact area between the winding portion 90 and the installation object tends to be larger compared to when the winding portion is cylindrical with the same cross-sectional area. A larger contact area between the winding portion 90 and the installation object improves the heat dissipation performance of the reactor 7. If the contact area between the winding part 90 and the installation object is large, the installation state of the winding part 90 relative to the installation object is likely to be stable.

[0094] [Molded Resin Portion] As shown in FIG. 5 , the reactor 7 may include a molded resin portion 10. In FIG. 5 , the appearance of the molded resin portion 10 is indicated by a two-dot chain line for ease of understanding. The molded resin portion 10 covers at least a portion of the magnetic core 8. The molded resin portion 10 has a function of protecting the magnetic core 8 from the external environment. The molded resin portion 10 may also cover the coil 9. In other words, the molded resin portion 10 is provided so as to cover at least a portion of the assembly of the magnetic core 8 and the coil 9. The molded resin portion 10 integrates the magnetic core 8 and the coil 9. A portion of the outer circumferential surface of the magnetic core 8 or at least a portion of the outer circumferential surface of the coil 9 may be exposed from the molded resin portion 10.

[0095] If the molded resin portion 10 is provided between the magnetic core 8 and the coil 9, the insulation between the magnetic core 8 and the coil 9 is likely to be improved. If the molded resin portion 10 is provided between the middle core portion 21 of the first core piece 81 and the middle core portion 22 of the second core piece 82, the molded resin portion 10 provided therebetween functions as a gap material for the magnetic core 8.

[0096] The resin forming the molded resin portion 10 is, for example, the same resin as the resin of the composite material described above. The material forming the molded resin portion 10 may contain the filler described above, similar to the composite material.

[0097] [Others] The reactor 7 may include a retaining member, although not shown. The retaining member is disposed between the magnetic core 8 and the coil 9 and serves to electrically insulate the magnetic core 8 from the coil 9. The retaining member defines the relative positions of the magnetic core 8 and the coil 9 and maintains their positioning. The retaining member is disposed, for example, between the end surface 91 of the winding portion 90 and the end core portions 5, 6. The retaining member disposed between the end surface 91 of the winding portion 90 and the end core portions 5, 6 is, for example, a frame-shaped member. The retaining member is disposed, for example, between the inner circumferential surface of the winding portion 90 and the outer circumferential surface of the middle core portion 2. The retaining member disposed between the inner circumferential surface of the winding portion 90 and the outer circumferential surface of the middle core portion 2 is, for example, a cylindrical member. The retaining member disposed between the inner circumferential surface of the winding portion 90 and the outer circumferential surface of the middle core portion 2 is, for example, structured to allow unsolidified resin forming the molded resin portion 10 to flow between the winding portion 90 and the middle core portion 2.

[0098] <Embodiment 2> <Core Piece> A core piece 1 of embodiment 2 will be described with reference to Figures 7 and 8. Like the core piece 1 of embodiment 1, the core piece 1 of embodiment 2 is also an integrated body in which a first portion 11 and a plurality of second portions 12 are integrally molded, and the first portion 11 and the plurality of second portions 12 made of different materials are well joined. One of the features of the core piece 1 of embodiment 2 is that the protrusions 125 provided on each second portion 12 include connecting protrusions 128. The overall shape of the core piece 1 of embodiment 2 is similar to that of the core piece 1 of embodiment 1. The following description will focus on the differences from the core piece 1 of embodiment 1.

[0099] [First Section] The first block section 110 of the first section 11 is a block body having a portion arranged to face the end surface 91 ( FIG. 6 ) of the winding section 90 of the coil 9. The first block section 110 of this example includes a portion of the end core section 5. The first block section 110 has an I-shape formed by a portion of the end core section 5. The length of the first block section 110 of this example along the third direction D3 is shorter than the length of the end core section 5 along the third direction D3. In other words, the first section 11 of this example is arranged biased toward the third direction D3 of the end core section 5.

[0100] The first surface 111 of the first block portion 110 has a lower step portion 115. The lower step portion 115 is provided on the edge portion of the first surface 111. The lower step portion 115 is a portion where the edge portion of the first surface 111 is locally lowered. In this example, the lower step portion 115 is provided continuously around the entire circumference of the first surface 111.

[0101] Although not shown, the second surface of the first block portion 110 has a low step portion. The second surface of the first block portion 110 is the surface facing the first surface 111 shown in FIG. 8. The low step portion is provided on the edge of the second surface. The low step portion is a portion where the edge of the second surface is locally lowered. The low step portion in this example is provided continuously around the entire periphery of the second surface, similar to the low step portion 115 shown in FIG. 8.

[0102] [Second Regions] The core piece 1 of the second embodiment includes three second regions 12A, 12B, and 12C, similar to the core piece 1 of the first embodiment.

[0103] The second block portion 120A of the second section 12A includes a middle core portion 21. The second block portion 120A has an I-shape formed by the middle core portion 21. The multiple surfaces forming the second block portion 120A include an end surface 123A facing the first section 11.

[0104] The second block portion 120B of the second section 12B includes the side core portions 3. The second block portion 120B has an I-shape formed by the side core portions 3. Similar to the second block portion 120A, the multiple surfaces forming the second block portion 120B also have end surfaces 123B facing the first section 11.

[0105] The second block portion 120C of the second section 12C includes a side core portion 4. The second block portion 120C has an I-shape formed by the side core portions 4. Similar to the second block portion 120A, the multiple surfaces forming the second block portion 120C also have end surfaces 123C facing the first section 11.

[0106] The second block portions 120A, 120B, 120C are block bodies arranged to face an inner surface 92 (FIG. 6) of a winding portion 90 of the coil 9, which will be described later.

[0107] The end faces 123A, 123B, and 123C include protrusions 125 and 126. The protrusions 125 and 126 are provided on the edges of the end faces 123A, 123B, and 123C. The protrusions 125 and 126 are provided on the edges of the end faces 123A, 123B, and 123C at positions facing each other in the third direction D3. The protrusions 125 and 126 protrude from the end faces 123A, 123B, and 123C toward the end face 113 of the first portion 11. The protrusions 125 and 126 protrude in the first direction D1.

[0108] The protrusion 125 in this example is a connecting protrusion 128 connected to all of the second portions 12A, 12B, and 12C. The connecting protrusion 128 is provided on the first surface 111 of the first block portion 110 so as to continuously overlap both the low step portion 115 and a portion other than the low step portion 115. The connecting protrusion 128 constitutes a part of the end core portion 5. The end core portion 5 is constituted by a part of the first block portion 110 and the connecting protrusion 128. In other words, the end core portion 5 is constituted by a part of the first portion 11 and a part of the second portion 12. In FIG. 7 , the boundary between the middle core portion 21 and the end core portion 5 and the boundary between the side core portions 3 and 4 and the end core portion 5 are indicated by two-dot chain lines. Extension portions 127 constituted by protruding pieces extending along the first direction D1 are provided at both ends of the connecting protrusion 128 in the second direction D2.

[0109] The protrusions 126 are provided on each of the second portions 12A, 12B, and 12C. The protrusions 126 are provided so as to fill the lower step portions 116. The protrusions 126 have the same configuration as the protrusions 126 described in the first embodiment.

[0110] As shown in Fig. 9 , the reactor 7 of the second embodiment includes first core laminations 81 configured with the core laminations 1 of the second embodiment described above. The configuration of the second core laminations 82 and the configuration of the coil 9 are the same as those of the first embodiment. In this example, a part of the second portion 12 is arranged to face an end surface 91 of the coil 9. By arranging a part of the second portion 12 to face the end surface 91 of the coil 9, the magnetic properties are superior even with a large current.

[0111] <Modifications> Although not shown, the coil may have two winding portions. In this case, the magnetic core has two inner core portions and two outer core portions. The two inner core portions are arranged to face the inner surfaces of the winding portions. The two outer core portions are arranged to connect the end faces of the two inner core portions. The two outer core portions have portions arranged to face the end faces of each winding portion. The core pieces that make up the magnetic core are, for example, formed of a U-shaped block body. The U-shaped core piece is formed by joining a first portion and a second portion. For example, the first portion is formed of one outer core portion and a portion of each of the two inner core portions. The second portion is formed of the remaining portions of the two inner core portions. The first portion has a lower step portion, and the second portion has a protrusion portion.

[0112] <Embodiment 3> <Converter / Power Conversion Apparatus> The reactor 7 of the above-described embodiment 1 or embodiment 2 can be used in applications that satisfy the following energization conditions. The energization conditions include, for example, a maximum DC current of approximately 100 A to 1000 A, an average voltage of approximately 100 V to 1000 V, and an operating frequency of approximately 5 kHz to 100 kHz. The reactor 7 of embodiment 1 or embodiment 2 is typically used as a component of a converter mounted on a vehicle such as an electric vehicle or a hybrid vehicle, or as a component of a power conversion apparatus including this converter.

[0113] As shown in Fig. 10 , a vehicle 1200 such as a hybrid vehicle or an electric vehicle includes a main battery 1210, a power conversion device 1100 connected to the main battery 1210, and a motor 1220 that is driven by power supplied from the main battery 1210 and used for traveling. The motor 1220 is typically a three-phase AC motor that drives wheels 1250 during traveling and functions as a generator during regeneration. In the case of a hybrid vehicle, the vehicle 1200 includes an engine 1300 in addition to the motor 1220. In Fig. 10 , the charging point of the vehicle 1200 is an inlet, but a plug may also be provided.

[0114] The power conversion device 1100 includes a converter 1110 connected to a main battery 1210, and an inverter 1120 connected to the converter 1110 and performing mutual conversion between direct current and alternating current. The converter 1110 shown in this example boosts the input voltage of the main battery 1210, which is approximately 200 V or more and 300 V or less, to approximately 400 V or more and 700 V or less, when the vehicle 1200 is running, and supplies power to the inverter 1120. During regeneration, the converter 1110 reduces the input voltage output from the motor 1220 via the inverter 1120 to a direct current voltage suitable for the main battery 1210, and charges the main battery 1210. The input voltage is a direct current voltage. When the vehicle 1200 is running, the inverter 1120 converts the DC boosted by the converter 1110 into a predetermined AC and supplies it to the motor 1220, and when regenerating, it converts the AC output from the motor 1220 into DC and outputs it to the converter 1110.

[0115] As shown in FIG. 11 , 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 1115, and converts the input voltage by repeatedly turning the elements on and off. The conversion of the input voltage here refers to boosting and bucking the voltage. The switching elements 1111 are power devices such as field-effect transistors and insulated gate bipolar transistors. The reactor 1115 utilizes the properties of a coil that hinders changes in current flowing through the circuit, and has the function of smoothing changes when the current increases or decreases due to switching operations. The reactor 1115 includes the reactor 7 of embodiment 1 or embodiment 2.

[0116] In addition to converter 1110, vehicle 1200 also includes a power supply converter 1150 connected to main battery 1210, and an auxiliary power supply converter 1160 connected to main battery 1210 and sub-battery 1230, which serves as a power source for auxiliary equipment 1240, and converts the high voltage of main battery 1210 to low voltage. Converter 1110 typically performs DC-DC conversion, while power supply converter 1150 and auxiliary power supply converter 1160 perform AC-DC conversion. Some power supply converters 1150 perform DC-DC conversion. A reactor having a configuration similar to reactor 7 of embodiment 1 or embodiment 2, but with a modified size, shape, etc., can be used as the reactor for power supply converter 1150 and auxiliary power supply converter 1160. Furthermore, reactor 7 of embodiment 1 or embodiment 2 can also be used for a converter that converts input power and that only boosts or only bucks the voltage.

[0117] DESCRIPTION OF SYMBOLS 1 Core piece 11 First portion 110 First block portion 111 First surface 112 Second surface 113 End surface 115, 116 Lower step portion 12, 12A, 12B, 12C Second portion 120A, 120B, 120C Second block portion 123A, 123B, 123C End surface 125, 126 Protrusion 127 Extension portion 128 Connecting protrusion 2, 21, 22 Middle core portion 3, 4 Side core portion 5, 6 End core portion 7 Reactor 8 Magnetic core 81 First core piece 82 Second core piece 9 Coil 90 Winding portion 91 End surface 92 Inner surface 93 Outer surface 10 Molded resin portion 300 Mold 310 First space 321, 322, 323 Second space 330 Sprue 340 Runner 350 Gate 370 Partial core piece 375 Lower stage portion D1 First direction, D2 Second direction, D3 Third direction 1100 Power conversion device, 1110 Converter, 1111 Switching element 1112 Drive circuit, 1115 Reactor, 1120 Inverter 1150 Converter for power supply device, 1160 Converter for auxiliary power supply 1200 Vehicle, 1210 Main battery, 1220 Motor 1230 Sub-battery, 1240 Auxiliary equipment, 1250 Wheels, 1300 Engine

Claims

1. A core piece for constituting a magnetic core arranged inside and outside a coil, comprising: a first portion composed of a pressed powder molding of soft magnetic powder; and a plurality of second portions composed of a molding of a composite material in which soft magnetic powder is dispersed in resin, wherein the first portion comprises: a first block portion having a portion arranged to face an end face of the coil; and a low step portion in which each edge of two of the plurality of faces constituting the first block portion that face each other is locally lowered, and each of the plurality of second portions comprises: a second block portion having a side facing either the inner or outer surface of the coil and arranged to face the side face of an adjacent second portion; and a protrusion provided on the edge of the end face of the second block portion so as to overlap the low step portion.

2. A core piece according to claim 1, wherein the plurality of second portions are constructed independently of one another, and the first portion has a lower step portion corresponding to the protrusion of each of the plurality of second portions.

3. A core piece according to claim 1 or 2, wherein an outer surface of the first portion at the joint between the lower step and the protrusion is flush with an outer surface of each of the plurality of second portions.

4. A core piece according to any one of claims 1 to 3, wherein the plurality of second regions include molded bodies formed of mutually different composite materials.

5. A core piece as described in claim 1, wherein the protrusion includes a connecting protrusion connected to all of the plurality of second portions, and the connecting protrusion is arranged on one of two mutually facing faces among the plurality of faces constituting the first block portion so as to overlap continuously with both the low step portion and a portion other than the low step portion.

6. A reactor comprising: a magnetic core formed by combining first core pieces and second core pieces; and a coil arranged in a part of the magnetic core, wherein at least one of the first core pieces and the second core pieces is a core piece as defined in any one of claims 1 to 5.

7. A converter comprising the reactor according to claim 6.

8. A power conversion device comprising the converter according to claim 7.

9. A method for manufacturing a core piece, comprising: a step of preparing a die having a first space and a plurality of second spaces which are connected to each other; a step of arranging a partial core piece constituted by a compressed powder molding of soft magnetic powder in a space including the first space; and a step of filling each of the plurality of second spaces with a composite material in which soft magnetic powder is dispersed in resin, wherein each of the plurality of second spaces extends in a direction intersecting with the first space and is arranged side by side with each other, and the partial core piece comprises a first block portion and a lower step portion in which each edge portion of two opposing faces among a plurality of faces constituting the first block portion is locally lowered, and in the filling step, the composite material is filled into each of the plurality of second spaces so as to overlap the lower step portion.

10. The method for manufacturing a core piece according to claim 9, wherein in the filling step, at least two of the plurality of second spaces are filled with different composite materials.

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