Patent Publication Number: US-2018040407-A1

Title: Reactor

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is the U.S. national stage of PCT/JP2016/052755 filed Jan. 29, 2016, which claims priority of Japanese Patent Application No. JP 2015-030109 filed Feb. 18, 2015. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a reactor that is used as a constituent component of an on-board DC-DC converter and a power conversion device that are mounted on a vehicle such as a hybrid vehicle. 
     BACKGROUND 
     Magnetic components such as reactors and motors are used in various fields. For example, JP 2012-253384A discloses, as an example of such a magnetic component, a reactor that is used as a circuit component of an on-board converter. JP 2012-253384A discloses a reactor that is housed in a casing, the reactor including: a coil that is formed by winding a winding wire; a ring-shaped magnetic core on which the coil is disposed; a casing that houses a combined body that includes the coil and the magnetic core; an insulator that is interposed between the coil and the magnetic coil; and a sealing resin that fills the casing. JP 2012-253384A discloses that an adhesive agent or an adhesive tape, for example, is used to integrate a plurality of core pieces that constitute the magnetic core into one piece, and integrate the core pieces and a gap member into one piece. 
     In recent years, as demand for hybrid vehicles and electric vehicles has increased, it is desired to improve productivity when manufacturing reactors. In terms of such a demand, the process of manufacturing a reactor that is housed in a casing has room for improvement. 
     In the process of manufacturing a reactor, when forming a reactor by attaching a plurality of core pieces to a coil, high accuracy is required when positioning the core pieces relative to each other and when positioning the magnetic core and the coil relative to each other. Therefore, according to JP 2012-253384A, the core pieces and the gap members are fixed to each other in advance, using an adhesive tape or the like, so that the magnetic core and the coil are accurately positioned relative to each other. It is expected that productivity can be improved when manufacturing a reactor by simplifying such a task of fixing the core pieces and the gap members to each other. 
     The present invention has been made in view of the above-described situation, and one objective of the present invention is to provide a reactor that makes it easier to hold constituent components thereof at predetermined positions relative to each other during the manufacturing process thereof, and that achieves excellent productivity. 
     SUMMARY 
     A reactor according to one aspect of the present invention includes: a coil that includes winding portions; magnetic cores that are formed by combining a plurality of core pieces and gap members that are interposed between the core pieces, and include portions that are located inside the winding portions; interposed members that are interposed between inner surfaces of the winding portions and the magnetic cores, and include a core holding portion that secures gaps between the plurality of core pieces and position the core pieces; a casing that houses a combined body that includes the coil, the magnetic cores, and the interposed members; and a sealing resin portion that fills the casing and seals the combined body. The gap members are formed using a constituent resin of the sealing resin portion. 
     Advantageous Effects 
     The above-described reactor makes it easier to hold constituent components thereof at predetermined positions relative to each other during the manufacturing process thereof, and achieves excellent productivity. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic perspective view of a reactor according to a first embodiment. 
         FIG. 2  is a cross-sectional view along (II)-(II) of the reactor shown in  FIG. 1 . 
         FIG. 3  is a cross-sectional view along (III)-(III) of the reactor shown in  FIG. 1 . 
         FIG. 4  is a schematic exploded perspective view of the reactor according to the first embodiment. 
         FIG. 5  is a schematic exploded perspective view of a combined body that is provided in the reactor according to the first embodiment. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     First, embodiments of the present invention will be listed and described. 
     (1) A reactor according to an embodiment of the present invention includes: a coil that includes winding portions; magnetic cores that are formed by combining a plurality of core pieces and gap members that are interposed between the core pieces, and include portions that are located inside the winding portions; interposed members that are interposed between inner surfaces of the winding portions and the magnetic cores, and include a core holding portion that secures gaps between the plurality of core pieces and position the core pieces; a casing that houses a combined body that includes the coil, the magnetic cores, and the interposed members; and a sealing resin portion that fills the casing and seals the combined body. The gap members are formed using a constituent resin of the sealing resin portion. 
     In the above-described reactor, gaps are secured between adjacent core pieces by the interposed members, and the core pieces can be accurately positioned relative to each other. The core pieces to which the interposed members are attached can be treated as an integrated element with gaps being provided between the core pieces, and therefore workability is excellent. By inserting, into the winding portions, the core pieces to which the interposed members are attached, it is possible to keep the core pieces in the state of having gaps therebetween inside the winding portions. Therefore, after the combined body is put in the casing, upon the casing being filled with an unsolidified constituent resin of the sealing resin portion, the unsolidified constituent resin flows into the gaps between the above-described core pieces, and gap members that match the gaps between the core pieces are formed. When the sealing resin portion is molded the combined body that includes the coil, the magnetic cores, and the interposed members can be sealed, and also the gap members can be formed between the core pieces. Therefore, during the process of manufacturing the reactor, it is possible to simplify the task of fixing the core pieces and the gap members to each other in advance using an adhesive or the like, and it is possible to achieve excellent productivity when manufacturing the reactor. 
     (2) In one example of the above-described reactor, the interposed members include a supporting portion that supports the core holding portion, and a flow path that is formed in the supporting portion and allows an unsolidified constituent resin of the sealing resin portion to flow into gaps between the plurality of core pieces when the sealing resin portion is molded. 
     With the above-described configuration, a flow path is formed in the supporting portion that is connected to the core holding portion that secures gaps between the plurality of core pieces, and therefore it is possible to reliably allow the above-described unsolidified constituent resin to flow along the flow path, into the gaps between the core pieces. Therefore, it is easier to form the gap members between the core pieces, using the constituent resin of the sealing resin portion. 
     (3) In one example of the above-described reactor, the sealing resin portion is molded using a soft resin. 
     In a reactor, when a current at a predetermined frequency is applied to the coil and the coil is excited, the magnetic cores repeat expansion and contraction and vibrate due to magnetostriction, and make noise. For example, the vibrations of the magnetic cores are transmitted to the casing and makes transmission noise. Since the sealing resin portion is formed using a soft resin, the vibrations from the magnetic cores are buffered by the sealing resin portion. Therefore, the vibrations of the magnetic cores are prevented from being transmitted to the casing, and it is possible to suppress the noise due to vibrations that are transmitted from the magnetic cores to the casing. In particular, in the above-described reactor, the gap members that are interposed between the core pieces are formed using the constituent resin of the sealing resin portion, and therefore, the vibrations from the magnetic cores (the core pieces) are more likely to be buffered, and it is possible to more effectively prevent the vibrations from the magnetic cores from being transmitted to the casing. 
     (4) In one example of the above-described reactor in which the sealing resin portion is formed using a soft resin, a gap is provided between: outer core pieces out of the magnetic core; and a mounting surface of the casing on which the outer core pieces are mounted, the outer core pieces being located outside the winding portions, and the sealing resin portion fills the gap. 
     Since the sealing resin portion that is formed using a soft resin is interposed between the outer core pieces and the mounting surface of the casing, the magnetic cores and the casing are prevented from being brought into direct contact with each other, and the vibrations from the magnetic cores can be buffered by the sealing resin portion. Therefore, the vibrations from the magnetic cores can be further prevented from being transmitted to the casing. 
     (5) In one example of the above-described reactor, the sealing resin portion is formed using a hard resin. 
     Since the sealing resin portion is formed using a hard resin, the magnetic cores are more firmly fixed to the sealing resin portion. Therefore, it is possible to suppress the vibrating of the magnetic cores per se. In particular, in the above-described reactor, the gap members that are interposed between the core pieces are formed using the constituent resin of the sealing resin portion, and therefore it is possible to more effectively suppress the vibrating of the magnetic cores (the core pieces) per se. 
     The following describes the details of embodiments of the present invention. Note that the present invention is not limited to these examples, and is specified by the scope of claims. All changes that come within the meaning and range of equivalency of the claims are intended to be embraced therein. Elements having the same name are denoted by the same reference signs throughout the drawings. 
     First Embodiment 
     A reactor  1  according to a first embodiment will be described with reference to  FIGS. 1 to 5 . 
     Reactor 
     Overall Configuration 
     As shown in  FIGS. 1 to 5 , the reactor  1  according to the first embodiment includes: a coil  2  that has winding portions  2   a  and  2   b  that are formed by spirally winding a winding wire  2   w ; a magnetic core  3  that includes portions that are located inside the winding portions  2   a  and  2   b ; interposed members  5  that are interposed between the inner surfaces of the winding portions  2   a  and  2   b  and the magnetic cores  3 ; a casing  4  that houses a combined body  10  that includes the coil  2 , the magnetic cores  3 , and the interposed members  5 ; and a sealing resin portion  6  that fills the casing  4  to seal the combined body  10 . The magnetic core  3  is formed by combining: a plurality of inner core pieces  31   m  that are entirely located inside the winding portions  2   a  and  2   b ; outer core pieces  32   m  that include portions that are located outside the winding portions  2   a  and  2   b ; and gap members  31   g  that are interposed between the inner core pieces  31   m  and between the inner core pieces  31   m  and the outer core pieces  32   m . One feature of the reactor  1  according to the first embodiment is that the interposed members  5  include core holding portions  51  that secure gaps between the plurality of core pieces and that position the core pieces (see  FIG. 3 ), and that the gap members  31   g  are formed using the constituent resin of the sealing resin portion  6  (see  FIGS. 2 and 3 ). The following describes each component in detail. In the following description, it is assumed that the lower side is the installation side when the combined body  10  is installed in the casing  4  (the side on which a bottom plate portion  40  of the casing  4  is located), and that the upper side is the opposing side (the side on which the opening of the casing  4  is located). 
     Coil 
     As shown in  FIG. 5 , the coil  2  includes: a pair of tubular winding portions  2   a  and  2   b  that are formed by spirally winding one continuous winding wire  2   w ; and a coupling portion  2   r  that couples the winding portions  2   a  and  2   b  to each other. The winding portions  2   a  and  2   b  have a hollow tube shape as a result of winding the winding wire  2   w  the same number of times in the same winding direction, and are arranged side by side (in the horizontal direction) such that their axial directions are parallel with each other. The coupling portion  2   r  is a portion that is bent in a U-like shape to connect the winding portions  2   a  and  2   b . The coil  2  may be formed by spirally winding one winding wire that does not have a joint portion, or by manufacturing the winding portions  2   a  and  2   b  using separate winding wires and joining the end portions of the winding wires of the winding portions  2   a  and  2   b  to each other through welding or crimping. Both end portions of the coil  2  are drawn out of the winding portions  2   a  and  2   b  in appropriate directions, and are connected to a terminal member, which is not shown. An external device such as a power supply for supplying power to the coil  2  is connected via the terminal member. 
     The winding portions  2   a  and  2   b  in the present embodiment have a rectangular tube shape. The winding portions  2   a  and  2   b  that have a rectangular tube shape are winding portions whose end surfaces have a rectangular shape (including a square shape) and whose corners are rounded. Of course, the winding portions  2   a  and  2   b  may have a circular tube shape. The winding portions that have a circular tube shape are winding portions whose end surfaces have a closed surface shape (such as an oval shape, a perfect circle shape, or a race track shape). 
     The coil  2  that includes the winding portions  2   a  and  2   b  can be formed on the outer circumferential surface of a conductor such as a flat wire or a round wire that is made of a conductive material such as copper, aluminum, magnesium, or an alloy thereof, using a coated wire that includes an insulative coating that is made of an insulative material. In the present embodiment, the winding portions  2   a  and  2   b  are formed through edgewise-winding of a coated flat wire that includes a conductor that is made of a copper flat wire and an insulative coating that is made of enamel (typically polyamide imide). 
     Magnetic Core 
     As shown in  FIG. 5 , the magnetic core  3  includes: a plurality of columnar inner core pieces  31   m ; a pair of outer core pieces  32   m  that have a U-like shape; and a plurality of gap members  31   g  that are interposed between the core pieces (see  FIG. 2 ). The inner core pieces  31   m  are magnetic pieces that are entirely located inside the winding portions  2   a  and  2   b , and the outer core pieces  32   m  are magnetic pieces that include portions that are located outside the winding portions  2   a  and  2   b . The outer core pieces  32   m  may include portions that are located inside the winding portions  2   a  and  2   b . In this example, the outer core pieces  32   m  include both portions that are located outside the winding portions  2   a  and  2   b  and portions that are located inside the winding portions  2   a  and  2   b . The outer core pieces  32   m  are arranged such that their respective openings that have a U-like shape face each other, and the inner core pieces  31   m  are arranged between the outer core pieces  32   m  in the horizontal direction (side by side). In  FIG. 5 , gaps are provided between the inner core pieces  31   m , and the gap members  31   g  (see  FIG. 2 ) are formed between the inner core pieces  31   m  by filling the gaps with the constituent resin of the sealing resin portion  6 , which will be described below. In this example, the gap members  31   g  are also provided in gaps between the inner core pieces  31   m  and the outer core pieces  32   m  that face the inner core pieces  31   m , by filling the gaps with the constituent resin of the sealing resin portion  6 . With this arrangement, the magnetic core  3  is attached so as to have a ring-like shape, and forms a closed magnetic circuit when the coil  2  is excited. 
     Inner Core Pieces 
     It is preferable that the inner core pieces  31   m  have a shape that matches the shape of the winding portions  2   a  and  2   b . In this example, as shown in  FIG. 5 , the inner core pieces  31   m  have a rectangular parallelepiped shape, and the corners of the inner core pieces  31   m  are rounded along the corners of the inner circumferential surfaces of the winding portions  2   a  and  2   b . The number of inner core pieces  31   m  can be appropriately selected. 
     Outer Core Pieces 
     The pair of outer core pieces  32   m  have the same shape, namely a substantially U-like shape when seen from above in  FIG. 5 . Each outer core piece  32   m  includes an outer core base portion  321  that has a rectangular parallelepiped shape and is located outside the winding portions  2   a  and  2   b  so as to span the winding portions  2   a  and  2   b ; and a pair of protruding portions  322  that protrude from the outer core base portion  321  and are located inside the winding portions  2   a  and  2   b . The outer core base portion  321  and the pair of protruding portions  322  are molded integrally with each other. Also, in this example, a portion that protrudes in a direction that is opposite the direction in which the pair of protruding portions  322  protrude is molded integrally with the outer core base portion  321 . The cross-sectional area of this protruding portion is substantially equal to the cross-sectional areas of the inner core pieces  31   m  and the protruding portions  322 . The end surfaces of the pair of protruding portions  322  above have a shape and a size that are substantially the same as those of the end surfaces of the inner core pieces  31   m , and the size and the length of protrusions of the pair of protruding portions  322  can be appropriately selected such that the end surfaces of the pair of protruding portions  322  have a predetermined magnetic circuit cross-sectional area that matches the coil  2 . It is preferable that the pair of protruding portions  322  have a shape that matches the shape of the winding portions  2   a  and  2   b . In this example, the corners of the pair of protruding portions  322  are substantially rounded along the corners of the inner circumferential surfaces of the winding portions  2   a  and  2   b.    
     The lower surfaces of the outer core base portions  321  of the outer core pieces  32   m  that have a U-like shape protrude to positions that are downward of the lower surfaces of the inner core pieces  31   m . Also, when the coil  2  and the magnetic core  3  are attached to each other, the lower surface of the coil  2  protrudes to a position that is downward of the lower surfaces of the outer core base portions  321 , and a gap is formed between the lower surfaces of the outer core base portions  321  and the mounting surface of the bottom plate portion  40  of the casing  4 , which will be described below (see  FIG. 2 ). The height of the outer core base portions  321  is adjusted such that the above-described gap can be formed. The length of the gap between the lower surfaces of the outer core base portions  321  and the bottom plate portion  40  of the casing  4  is, for example, within the range from 0.3 mm to 3.0 mm inclusive. Here, a configuration in which the lower surface of the coil  2  protrudes to a position that is downward of the lower surfaces of the outer core base portions  321  is employed in order to form a gap between the lower surfaces of the outer core base portions  321  and the bottom plate portion  40  of the casing  4 . However, the lower surface of the coil  2  and the lower surfaces of the outer core base portions  321  may be flush with each other. By interposing a joining layer  7 , which will be described below, between the lower surface of the coil  2  and the bottom plate portion  40 , a gap that corresponds to the thickness of the joining layer  7  is formed between the lower surfaces of the outer core base portions  321  and the bottom plate portion  40 . 
     In this example, both the inner core pieces  31   m  and the outer core pieces  32   m  are powder compacts. A powder compact is typically obtained by molding a raw material powder that contains soft magnetic powder of a metal such as iron or an iron alloy (a Fe—Si alloy, a Fe—Ni alloy, etc.), and a binder (resin, etc.) and a lubricant if necessary, and then performing a heat treatment for the purpose of eliminating distortion that occurs during the molding process, for example. By using coated powder obtained by applying an insulating treatment to metal powder, or mixed powder obtained by mixing metal powder and an insulative material, as raw material powder, it is possible to obtain a powder compact that substantially includes metal particles and insulative materials that are interposed between the metal particles, after performing molding. This powder compact includes an insulative material, and therefore it can reduce eddy currents, resulting in lower energy loss. 
     Gap Members 
     The gap members  31   g  are formed by filling the gaps between the core pieces with the constituent resin of the sealing resin portion  6 , which will be described below. The gap members  31   g  will be described in detail later, in the description of the method for manufacturing a reactor. 
     Interposed Members 
     The interposed members  5  are members that are interposed between: the inner surfaces of the winding portions  2   a  and  2   b ; and core portions of the magnetic core  3  that are located inside the winding portions  2   a  and  2   b , and insulate the coil  2  and the magnetic core  3  from each other. This example is provided with a pair of interposed members  5 , which are respectively provided for the winding portions  2   a  and  2   b . The pair of interposed members  5  have the same shape, and therefore the following describes one of the interposed members  5  that is arranged for one of the winding portions  2   a  and  2   b . In this example, the interposed member  5  includes a pair of divisional interposed members  5 A and  5 B that have division surfaces that extend in the axial direction of the winding portions. The following describes the components of the interposed member  5  in detail, mainly with reference to  FIGS. 2, 3, and 5 . 
     The pair of divisional interposed members  5 A and  5 B are members that each have a squared C shape, are not in contact with each other, and are arranged on portions of the inner core pieces  31   m  in the circumferential direction (see FIGS.  3  and  5 ). The divisional interposed members  5 A and  5 B have a length that spans the entire length of the plurality of inner core pieces  31   m  and the protruding portions  322  of the outer core pieces  32   m  in the axial direction when the core pieces  31   m  and  32   m  are attached so as to have a ring-like shape (see  FIGS. 2 and 5 ). In this example, the pair of divisional interposed members  5 A and  5 B are arranged sandwiching the inner core pieces  31   m  from their upper and lower surfaces. That is, the divisional interposed member  5 A ( 5 B) includes: a top plate portion  520  that is arranged on the entire surface of the upper surface (the lower surface) of the inner core pieces  31   m  and the protruding portions  322  of the outer core pieces  32   m ; and a pair of leg portions  521  that are provided on the top plate portion  520  and are arranged to span the corners of the inner core pieces  31   m  and the protruding portions  322  of the outer core pieces  32   m  and portions of the side surfaces. The pair of divisional interposed members  5 A and  5 B include: core holding portions  51  that secure gaps between adjacent inner core pieces  31   m  when sandwiching the inner core pieces  31   m , and position the inner core pieces  31   m  relative to each other; and flow paths  53  that allow an unsolidified constituent resin of the sealing resin portion  6 , which will be described later, to flow into the gaps between the above-described inner core pieces  31   m.    
     Core Holding Portions 
     The plurality of core holding portions  51  that protrude inward are molded integrally with the inner surfaces of the top plate portion  520  and the leg portions  521 . That is, the top plate portion  520  and the leg portions  521  serve as a supporting portion  52  that supports the core holding portions  51 . Each core holding portion  51  is a protrusion that has an I-like shape and extends from a corner that is formed by the top plate portion  520  and a leg portion  521  along the leg portion  521 . As shown in  FIG. 3 , the core holding portions  51  are inserted into the gaps between the inner core pieces  31   m , at positions corresponding to the four corners of each inner core piece  31   m . The areas surrounded by the dotted lines in  FIG. 3  are the cross-sectional areas of the inner core pieces  31   m.    
     The core holding portions  51  allow the inner core pieces  31   m  to be located at desired positions. The thickness of the core holding portions  51  (the thickness in the axial direction of the winding portions) corresponds to the thickness of the gap members  31   g  (see  FIG. 2 ). Therefore, by arranging the pair of divisional interposed members  5 A and  5 B such that the core holding portions  51  are interposed between the inner core pieces  31   m , it is possible to position the inner core pieces  31   m , and it is possible to form gaps that match the thickness of the gap members  31   g  between the inner core pieces  31   m . That is, by sandwiching the inner core pieces  31   m  between the pair of divisional interposed members  5 A and  5 B, it is possible to accurately position the portions of the magnetic core  3  that are located inside the winding portions. 
     The core holding portions  51  may be formed such that the cross-sectional area of the gap members  31   g  that are formed using the constituent resin of the sealing resin portion  6  is greater than or equal to 50% of the cross-sectional area of the inner core pieces  31   m  (see  FIG. 3 , the area surrounded by the dotted lines in  FIG. 3  is the cross-sectional area of the inner core pieces  31   m ). It becomes easier to reliably secure the gaps between the inner core pieces  31   m  if the contact area between: the inner core pieces  31   m  or the protruding portions  322 ; and the core holding portions  51  is increased. However, if the area of the protrusions of the core holding portions  51  is increased in order to increase the contact area between: the inner core pieces  31   m  or the protruding portions  322 ; and the core holding portions  51 , the cross-sectional area of the gaps between the core pieces decreases. As a result, the amount of the unsolidified constituent resin of the sealing resin portion  6  that fills the gaps between the core pieces decreases, and the cross-sectional area of the gap members  31   g  that are formed using the constituent resin of the sealing resin portion  6  decreases. If the amount of the unsolidified constituent resin of the sealing resin portion  6  that fills the gaps between the core pieces decreases, the area where the core pieces are fixed to each other by the sealing resin portion  6  decreases. Therefore, the core pieces cannot be firmly fixed to each other, which leads to the risk of the core pieces vibrating during the operation of the reactor  1 . Therefore, it is preferable that the length of the projections of the core holding portions  51  is adjusted such that the gaps between the core pieces can be secured and the cross-sectional area of the gap members  31   g  that are formed by the constituent resin of the sealing resin portion  6  is greater than or equal to 50% of the cross-sectional area of the inner core pieces  31   m . The cross-sectional area of the gap members  31   g  that are formed by the constituent resin of the sealing resin portion  6  may be greater than or equal to 60%, or greater than or equal to 70%, or even greater than or equal to 80% of the cross-sectional area of the inner core pieces  31   m.    
     Flow Paths 
     The flow paths  53  are formed in the top plate portion  520 . When the sealing resin portion  6 , which will be described later, fills the casing  4 , the flow paths  53  allow the unsolidified constituent resin of the sealing resin portion  6  to flow into the gaps between the inner core pieces  31   m . In this example, a plurality of through holes  53   h  are formed in the top plate portion  520  as the flow paths  53  such that the gaps between the inner core pieces  31   m  are exposed to the outside. The unsolidified constituent resin usually fills the casing  4  from the lower side of the casing  4  in order to prevent the unsolidified constituent resin from including bubbles. Therefore, it is particularly preferable that the through holes  53   h  are formed in the divisional interposed member  5 B that is located on the side of the lower surfaces of the inner core pieces  31   m . Due to the through holes  53   h  being provided, it is possible to remove air via the through holes  53   h  when filling the above-described unsolidified constituent resin. 
     In addition, groove portions (not shown) may be formed in the inner circumferential surfaces and the outer circumferential surfaces of the top plate portion  520  and the leg portions  521  as the flow paths  53 . For example, lateral groove portions that extend inward from end portions of the divisional interposed members  5 A and  5 B in the axial direction of the winding portions and join the through holes  53   h  may be formed. When a plurality of through holes  53   h  are provided, lateral groove portions that connect the through holes  53   h  to each other may be formed. This configuration allows the unsolidified constituent resin of the sealing resin portion  6  to easily flow into the gaps between the inner core pieces  31   m.    
     As the constituent material of the interposed members  5 , a polyphenylene sulfide (PPS) resin, a polytetrafluoroethylene (PTFE) resin, a liquid crystal polymer (LCP), a polyamide (PA) resin such as nylon 6 or nylon 66, and a thermoplastic resin such as a polybutylene terephthalate (PBT) resin or an acrylonitrile butadiene styrene (ABS) resin may be used, for example. In addition, it is also possible to use a thermosetting resin such as an unsaturated polyester resin, an epoxy resin, a urethane resin, or a silicone resin. The interposed members  5  can be easily manufactured using a known molding method such as injection molding using the above-described resins. 
     In this example, the interposed members  5  are arranged such that the pair of divisional interposed members  5 A and  5 B are independent of each other. However, a fixing member that fixes the positions of the pair of divisional interposed members  5 A and  5 B may be provided. For example, the divisional interposed members  5 A and  5 B may be fixed to the core pieces using an adhesive tape. By using an adhesive tape to fix the divisional interposed members  5 A and  5 B, it is possible to prevent the interposed members  5  from having a complex shape, and prevent the amount of the constituent material from increasing. Also, workability is excellent because the interposed members  5  can be fixed by performing the task of attaching the adhesive tape, which is easy. Alternatively, it is possible to provide the pair of divisional interposed members  5 A and  5 B with fitting portions that fit to each other, or band the divisional interposed members  5 A and  5 B together using a rubber band or a clamping band. 
     Also, although the interposed members  5  are arranged on portions of the inner core pieces  31   m  in the circumferential direction in this example, the interposed members  5  may be arranged along the entire circumferences of the inner core pieces  31   m . The interposed members  5  only need to secure the gaps between the inner core pieces  31   m . It is possible to reduce the amount of the constituent material of the interposed members  5  by employing a configuration in which the interposed members  5  are arranged on portions of the inner core pieces  31   m  in the circumferential direction. 
     Furthermore, although the pair of divisional interposed members  5 A and  5 B included in the interposed members  5  in this example have the same shape, they may have different shapes. For example, it is possible to allow the unsolidified constituent resin of the sealing resin portion  6  that fills the casing  4  to more efficiently flow into the gaps between the inner core pieces  31   m  by increasing the number of through holes  53   h  that are formed in the divisional interposed member  5 B that is located on the lower surface side of the inner core pieces  31   m.    
     Casing 
     As shown in  FIG. 4 , the casing  4  includes: the bottom plate portion  40  that is flat and on which the combined body  10  is mounted; and a side wall portion  41  that has a substantially rectangular frame shape and stands on the bottom plate portion  40  and surrounds the combined body  10 . The casing  4  has a substantially rectangular box shape with an opening that is on the opposite side (upper side) to the bottom plate portion  40 . In the reactor  1 , the combined body  10  is housed in the casing  4 . Thus, it is possible to protect the combined body  10  from the external environment (dust, corrosion, etc.), and to provide mechanical protection. In this example, the lower surface of the bottom plate portion  40  of the casing  4  is fixed so as to be in contact with the upper surface of an installation target such as a cooling base (not shown), and the reactor  1  is installed on the installation target. Although  FIG. 1  shows an installation state in which the bottom plate portion  40  is on the lower side, it is possible that the bottom plate portion  40  is on the upper side or a lateral side. 
     The casing  4  shown in this example is a metal casing into which the bottom plate portion  40  and the side wall portion  41  are integrated. In general, metal has a relatively high thermal conductivity. Therefore, if a metal casing is used, the casing can be entirely used as a heat dissipation path, and heat that is generated by the combined body  10  can be efficiently dissipated to an external installation target (e.g. a cooling base). Thus, the heat dissipation properties of the reactor  1  can be improved. Examples of the constituent material of the casing  4  include, aluminum and an alloy thereof, a magnesium and an alloy thereof, a copper and an alloy thereof, silver and an alloy thereof, iron, and austenitic stainless steel. The casing  4  can be lightweight if it is formed using aluminum, magnesium, or an alloy of aluminum and magnesium. 
     The casing  4  shown in this example is provided with a stay attachment portion  45  at the four corners of the casing  4 . Stays  450  are arranged over the upper surface of the outer core base portions  321  of the outer core pieces  32   m , and the stays  450  are fixed to the stay attachment portion  45  using screws  451 . Thus, the combined body  10  can be fixed to the casing  4 , with the combined body  10  being pressed to the bottom plate portion  40 . 
     Joining Layer 
     As shown in  FIGS. 2 to 4 , the reactor  1  shown in this example is provided with the joining layer  7  on the installation surface of the combined body  10 . The joining layer  7  is interposed between the lower surface of the coil  2  of the combined body  10  and the bottom plate portion  40 . Due to the joining layer  7  being provided, the combined body  10  can be firmly fixed to the bottom plate portion  40 . Thus, it is possible to restrict the coil  2  from moving, improve the heat dissipation properties, and stably fix the reactor  1  to the installation target. Preferably, the constituent material of the joining layer  7  is a material that includes an insulative resin, in particular, a ceramic filler or the like, and has excellent heat dissipation properties (e.g. a thermal conductivity of 0.1 W/m·K or more, even more preferably 1 W/m·K or more, and particularly preferably 2 W/m·K or more). Specific examples of the resin include thermosetting resins such as an epoxy resin, a silicone resin, and unsaturated polyester, and thermoplastic resins such as a PPS resin and LCP. The joining layer  7  may have a sheet-like shape, or be formed through coating or spraying. 
     Sealing Resin Portion 
     As shown in  FIG. 1 , the sealing resin portion  6  is a member that fills the casing  4 , and seals the combined body  10  that is housed in the casing  4 . The sealing resin portion  6  fills the casing  4  such that the upper surface of the combined body  10 , excluding both end portions of the coil  2 , is embedded in the sealing resin portion  6  (see  FIG. 2 ). In the reactor  1 , the combined body  10  is sealed using the sealing resin portion  6 , and the combined body  10  is thereby fixed to the casing  4 . Thus, it is possible to electrically and mechanically protect the combined body  10 , protect the combined body  10  from the external environment, prevent the magnetic core  3  from vibrating when electricity is applied to the coil  2 , and reduce noise that is caused by the vibrations. 
     As shown in  FIG. 2 , the constituent resin of the sealing resin portion  6  fills the gaps between the core pieces  31   m  formed by the above-described core holding portions  51 . The gap members  31   g  that are interposed between the core pieces are formed by the constituent resin of the sealing resin portion  6 . 
     As the constituent resin of the sealing resin portion  6 , an epoxy resin, a urethane resin, a silicone resin, an unsaturated polyester resin, or a PPS resin may be used, for example. In particular, an epoxy resin and a urethane resin are preferable because they are soft and inexpensive. From the view point of improving the heat dissipation properties, ceramic filler with a high thermal conductivity, such as alumina or silica, may be mixed into the sealing resin portion  6 . 
     A soft resin may be used as the constituent resin of the sealing resin portion  6 . If a soft resin is used, it is preferable that the Young&#39;s modulus (20° C. to 100° C.), which is a kind of modulus of elasticity, is smaller than or equal to 100 MPa. If the sealing resin portion  6  is formed using a soft resin, the vibrations from the magnetic core  3  are buffered by the sealing resin portion  6 . Therefore, it is possible to suppress the noise caused by vibrations that are transmitted from the magnetic core  3  to the casing  4 , and therefore it is possible to more easily reduce noise that is caused by the vibrations from the magnetic core  3 . In particular, by forming the gap members  31   g  between the core pieces  31   m  using the constituent resin of the sealing resin portion  6 , it is possible to more easily buffer the vibrations from the core pieces  31   m , and to further suppress the noise caused by vibrations that are transmitted from the magnetic core  3  (the core pieces  31   m ) to the casing  4 . The Young&#39;s modulus (20° C. to 100° C.) of this soft resin is even more preferably smaller than or equal to 20 MPa, and particularly preferably smaller than or equal to 5 MPa. If the Young&#39;s modulus of the soft resin is too small, the magnetic core  3  is likely to vibrate. Therefore, the Young&#39;s modulus is preferably greater than or equal to 1 kPa, and particularly preferably greater than or equal to 100 kPa. Here, note that the Young&#39;s modulus of the constituent resin of the sealing resin portion  6  is a value that is obtained based on JIS K7161-2, for example. 
     Alternatively, a hard resin may be used as the constituent resin of the sealing resin portion  6 . If a hard resin is used, it is preferable that the Young&#39;s modulus (20° C. to 100° C.), which is a kind of modulus of elasticity, is greater than or equal to 1 GPa. If the sealing resin portion  6  is formed using a hard resin, the magnetic core  3  is more firmly fixed to the sealing resin portion  6 . Therefore, it is possible to suppress the vibrating of the magnetic core  3  per se. In particular, by forming the gap members  31   g  between the core pieces  31   m  using the constituent resin of the sealing resin portion  6 , it is possible to suppress the vibration of the core pieces  31   m  per se. The Young&#39;s modulus (20° C. to 100° C.) of this hard resin is even more preferably greater than or equal to 5 GPa, and particularly preferably greater than or equal to 10 GPa. 
     Method for Manufacturing Reactor 
     The reactor  1  that has the above-described configuration can be manufactured by, for example: assembling the coil  2 , the plurality of core pieces  31   m  and  32   m , and the interposed members  5  to form the combined body  10 ; putting the combined body  10  into the casing  4 ; and filling the casing  4  with the unsolidified constituent resin of the sealing resin portion  6  and solidifying the constituent resin. 
     Manufacturing of Combined Body 
     First, as shown in  FIG. 5 , the plurality of inner core pieces  31   m  are sandwiched between the pair of divisional interposed members  5 A and  5 B. At this time, the core holding portions  51  that are formed on the divisional interposed members  5 A and  5 B are interposed between the inner core pieces  31   m . As a result, the inner core pieces  31   m  are positioned, and gaps that match the thickness of the gap members  31   g  are formed between the inner core pieces  31   m . Assemblies that each include the inner core pieces  31   m  sandwiched between the pair of divisional interposed members  5 A and  5 B are respectively inserted into the winding portions  2   a  and  2   b  of the coil  2 . Then, the pair of outer core pieces  32   m  are attached to the ends of this assembly, and thus the combined body  10  is formed. The protruding portions  322  of the outer core pieces  32   m  are inserted into spaces that are formed at the end portions of the pairs of divisional interposed members  5 A and  5 B. As a result, the end surfaces of the protruding portions  322  abut against and are stopped by the core holding portions  51  at the end portions of the divisional interposed members  5 A and  5 B. Thus, the protruding portions  322  are positioned and arranged inside the winding portions  2   a  and  2   b . The combined body  10  can be treated as an integrated element in which the core pieces  31   m  and  32   m  are positioned by the interposed members  5 . 
     In this example, the inner core pieces  31   m  that are sandwiched between the pairs of divisional interposed members  5 A and  5 B are treated as an assembly, and this assembly is sandwiched between the pair of outer core pieces  32   m . Alternatively, it is possible to form a U-shaped assembly in which the inner core pieces  31   m  and the protruding portions  322  of one of the outer core pieces  32   m  are sandwiched by the pairs of divisional interposed members  5 A and  5 B, insert the U-shaped assembly into the winding portions  2   a  and  2   b  of the coil  2  from the openings side of the U-shape, and attach the other outer core piece  32   m.    
     Putting Combined Body into Casing 
     Next, the combined body  10  is put into the casing  4  (see  FIG. 4 ). In this example, first, the joining layer  7  is positioned on the lower surface of the combined body  10 , and then the combined body  10  is put into the casing  4 . Also, the stays  450  are positioned on the upper surfaces of the outer core base portions  321  of the outer core pieces  32   m , the stays  450  are fixed to the stay attachment portion  45  of the casing  4  using the screws  451 , and thus the combined body  10  is fixed inside the casing  4 . 
     Filling and Solidifying Constituent Resin of Sealing Resin Portion 
     The casing  4  that houses the combined body  10  is filled with an unsolidified constituent resin of the sealing resin portion  6 . The above-described unsolidified constituent resin that fills the casing  4  covers the outer circumferential surface of the coil  2  and the outer circumferential surface of the magnetic core  3 , and also spreads through the gap between the coil  2  and the magnetic core  3 . Then, the above-described unsolidified constituent resin flows along the flow paths  53  that are provided in the interposed members  5 , and flows into and fills the gaps between the above-described core pieces  31   m  and  32   m . By solidifying the above-described constituent resin in this state, the combined body  10  is sealed and the gap members  31   g  are formed between the core pieces  31   m  and  32   m.    
     Primary Effects 
     In the above-described reactor  1 , when the sealing resin portion  6  is molded, the combined body  10  that includes the coil  2 , the magnetic core  3 , and the interposed members  5  can be sealed, and also the gap members  31   g  can be formed between the core pieces  31   m . Therefore, it is possible to simplify the conventional task of fixing the core pieces and the gap members to each other in advance using an adhesive or the like, and it is possible to achieve excellent productivity when manufacturing the reactor  1 . 
     Other Configurations 
     The above-described reactor  1  may be provided with sensors (not shown) that measure physical amounts regarding the reactor  1 , such as a temperature sensor, a current sensor, a voltage sensor, and a magnetic flux sensor. Sensors may be located in a space that is formed between the winding portions  2   a  and  2   b , for example. 
     INDUSTRIAL APPLICABILITY 
     The reactor according to the present invention can be used in a preferable manner in various converters such as an on-board converter (typically a DC-DC converter) that is mounted on a vehicle such as a hybrid vehicle, a plug-in hybrid vehicle, an electric vehicle, or a fuel cell vehicle, and a converter for an air conditioner, and in constituent components of a power conversion device.