Reactor

A reactor includes a coil, a magnetic core having an inner core portion arranged inside a winding portion, and an inner interposed member insulating the winding portion from the inner core portion. The inner interposed member includes a thin portion with a small thickness, and a thick portion with a thickness larger than that of the thin portion. The inner core portion includes, on an outer peripheral face facing the inner interposed member, a core-side projecting portion with a shape conforming to a shape of the inner peripheral face of the thin portion. The thickness of the thin portion is 0.2 mm or more and 1.0 mm or less, and the thickness of the thick portion is 1.1 mm or more and 2.5 mm or less. There is a clearance in at least part of a portion between the inner interposed member and the winding portion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the U.S. national stage of PCT/JP2018/004415 filed on Feb. 8, 2018, which claims priority of Japanese Patent Application No. JP 2017-035999 filed on Feb. 28, 2017, the contents of which are incorporated herein.

TECHNICAL FIELD

The present disclosure relates to a reactor.

BACKGROUND

For example, JP 2012-253289A and JP 2013-4531A disclose reactors that are magnetic components used in converters of electric motor vehicles such as hybrid cars. The reactors of JP 2012-253289A and JP 2013-4531A include a coil having a pair of winding portions, a magnetic core that is partially arranged inside the winding portions, and a bobbin (insulating interposed member) that ensures insulation between the coil and the magnetic core.

With recent development of electric motor vehicles, it is required to improve performances of reactors. For example, it is required to suppress a change in magnetic characteristics of reactors caused by heat accumulating in the reactors, by improving the heat dissipation properties of the reactors. Furthermore, it is required for such reactors to be small and excellent in terms of magnetic characteristics. In order to satisfy these requests, researches have been repeatedly conducted on the configuration of reactors.

In view of these circumstances, it is an object of the present disclosure to provide a reactor that is excellent in terms of heat dissipation properties. Furthermore, it is another object of the present disclosure to provide a reactor that is small and excellent in terms of magnetic characteristics.

SUMMARY

The present disclosure is directed to a reactor, including: a coil having a winding portion; a magnetic core having an inner core portion arranged inside the winding portion; and an inner interposed member for ensuring insulation between the winding portion and the inner core portion, wherein the inner interposed member includes a thin portion with a small thickness due to an inner peripheral face thereof being recessed, and a thick portion with a thickness larger than that of the thin portion, the inner core portion includes, on an outer peripheral face thereof facing the inner interposed member, a core-side projecting portion with a shape that conforms to a shape of the inner peripheral face of the thin portion, the thickness of the thin portion is 0.2 mm or more and 1.0 mm or less, and the thickness of the thick portion is 1.1 mm or more and 2.5 mm or less, the inner core portion and the inner interposed member are in substantially close contact with each other, and there is a clearance in at least part of a portion between the inner interposed member and the winding portion.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In many cases, inner interposed members are formed through injection molding. When the thickness of inner interposed members is small, the dimensions of the injection molded products are likely to vary. Accordingly, conventionally, the thickness of inner interposed members is set to a predetermined value or more (e.g., 2.5 mm or more), or, as described in JP 2012-253289A and JP 2013-4531A, inner interposed members are provided with ribs, for example, so that the level of precision of the dimensions of the inner interposed members has been increased. However, with this configuration, the distance between a winding portion and an inner core portion increases. Accordingly, the heat dissipation properties from the inner core portion to the winding portion are limited, and, with a constant cross-sectional area of the winding portion, the cross-sectional area of a magnetic path of an inner core portion arranged inside the winding portion cannot be larger than a certain level. In view of these aspects, the inventors of the present disclosure completed a reactor according to embodiments described below.

An embodiment is directed to a reactor including: a coil having a winding portion; a magnetic core having an inner core portion arranged inside the winding portion; and an inner interposed member for ensuring insulation between the winding portion and the inner core portion, wherein the inner interposed member includes a thin portion with a small thickness due to an inner peripheral face thereof being recessed, and a thick portion with a thickness larger than that of the thin portion, the inner core portion includes, on an outer peripheral face thereof facing the inner interposed member, a core-side projecting portion with a shape that conforms to a shape of the inner peripheral face of the thin portion, the thickness of the thin portion is 0.2 mm or more and 1.0 mm or less, and the thickness of the thick portion is 1.1 mm or more and 2.5 mm or less, the inner core portion and the inner interposed member are in substantially close contact with each other, and there is a clearance in at least part of a portion between the inner interposed member and the winding portion.

When producing an inner interposed member through injection molding in which resin is injected into a mold, resin that is injected into portions with a large gap in the mold forms thick portions, and resin that is injected into portions with a small gap in the mold forms thin portions. The portions with a large gap in a mold have a function of quickly supplying resin to the entire gap in the mold. Accordingly, even when the inner interposed member includes the thin portion with a thickness smaller than that of conventional examples, if it includes the thick portion with a thickness that is greater than or equal to a predetermined thickness, it can be easily produced as designed. In order to bring the inner interposed member into substantially close contact with the outer periphery of the inner core portion, resin is molded on the inner core portion, or the inner core portion is press-fitted to the inner interposed member. In either case, the inner interposed member can be produced as designed, and thus the inner interposed member can be brought into substantially close contact with the outer periphery of the inner core portion. Here, in both cases in which resin is molded on the inner core portion and in which the inner core portion is press-fitted to the inner interposed member, there may be a gap at part of the boundary between the inner core portion and the inner interposed member. Even when there is a gap at part of the boundary, it is assumed that the inner core portion and the inner interposed member are in substantially close contact with each other, as long as the total area of the gap with respect to the entire boundary is small (e.g., as long as it is 40% or less, or 20% or less).

If variations in dimensions of the inner interposed member are small, even when the inner interposed member is designed such that the clearance between the inner interposed member and the winding portion is small, the occurrence of a problem that the inner interposed member cannot be inserted into the winding portion, for example, can be suppressed.

Since the clearance described above can be made smaller, the distance from the inner core portion to the winding portion can be made smaller, and the heat dissipation properties from the inner core portion to the winding portion can be improved. Furthermore, since the inner core portion and the inner interposed member are in substantially close contact with each other, the thermal conductivity between them is good, and thus the heat dissipation properties from the inner core portion to the winding portion can be improved. In particular, in the reactor according to the embodiment, since the core-side projecting portion of the inner core portion is arranged in the recess of the thin portion (hereinafter, it may be referred to as an “interposed-side recess portion”), the heat dissipation distance from the core-side projecting portion to the winding portion is short, and thus the heat dissipation properties of the reactor can be improved.

Furthermore, since the clearance described above can be made smaller, the cross-sectional area of a magnetic path in the inner core portion inside the winding portion can be increased, without increasing the size of the winding portion. In particular, in the reactor according to the embodiment, since the core-side projecting portion of the inner core portion is arranged in the interposed-side recess portion of the inner interposed member, the cross-sectional area of a magnetic path in the inner core portion can be increased. Accordingly, the cross-sectional area of a magnetic path in the inner core portion can be made larger than that in a conventional reactor using an inner interposed member having no interposed-side recess portion, without changing the size of the winding portion.

Furthermore, the configuration of this embodiment is advantageous in that vibrations of the inner core portion due to magnetostriction are likely to be suppressed by the inner interposed member that is in close contact with the outer periphery of the inner core portion.

The reactor according to an embodiment may be such that the inner interposed member is constituted by resin molded on an outer side of the inner core portion.

When forming the inner interposed member by arranging the inner core portion inside a mold and molding resin on the outer side of the inner core portion, resin that is injected into portions with a large gap between the outer peripheral face of the inner core portion and the inner peripheral face of the mold forms thick portions, and resin that is injected into portions with a small gap in the mold forms thin portions. If the inner interposed member is formed by molding resin on the inner core portion, the inner core portion and the inner interposed member can be reliably brought into close contact with each other. Furthermore, the inner core portion and the inner interposed member can be handled in one piece, and thus the productivity of the reactor can be improved.

The reactor according to an embodiment may be such that a difference between the thickness of the thin portion and the thickness of the thick portion is 0.2 mm or more.

If a difference between the thin portion and the thick portion is 0.2 mm or more, it is possible to suppress variations in dimensions of the inner interposed member, while sufficiently ensuring the resin injectability to a narrow portion in the mold corresponding to the thin portion.

The reactor according to an embodiment may be such that the thickness of the thin portion is 0.2 mm or more and 0.7 mm or less, and the thickness of the thick portion is 1.1 mm or more and 2.0 mm or less.

If the thickness of the thin portion is set to the above-described range, the distance between the winding portion and the core-side projecting portion of the inner core portion can be made sufficiently small, and thus the heat dissipation properties of the reactor can be further improved. Furthermore, if the thickness of the thick portion is set to the above-described range, variations in dimensions of the inner interposed member can be further suppressed.

The reactor according to an embodiment may be such that a plurality of the thick portions and a plurality of the thin portions are present in a dispersed manner in a circumferential direction of the inner interposed member.

In the mold for producing the inner interposed member with the above-described configuration, it is easy to supply resin into the entire gap in the mold when injecting the resin, and thus an inner interposed member with small variations in dimensions can be easily produced. That is to say, the inner interposed member with the above-described configuration is an inner interposed member with small variations in dimensions, and thus the heat dissipation properties and the magnetic characteristics of the reactor can be improved. In particular, if a portion with a small gap and a portion with a large gap are alternately arranged in the circumferential direction of the gap in the mold into which resin is injected, it is easier to supply resin to the entire gap in the mold. With this mold, an inner interposed member in which a thick portion and a thin portion are alternately arranged in the circumferential direction of the inner interposed member can be produced at a high level of precision of dimensions.

The reactor according to an embodiment may be such that at least part of the thick portion reaches an end face of the inner interposed member in an axial direction of the winding portion.

When producing an inner interposed member through injection molding, in many cases, resin is injected from a position in a mold at which an end face of an inner interposed member is to be formed. In this case, resin enters the mold from an end face of an inner interposed member, and thus, if a large gap corresponding to the thick portion is present at the entrance of resin, the moldability of the inner interposed member is improved. When producing an inner interposed member including a thick portion that reaches an end face of the inner interposed member, a portion with a large gap corresponding to the thick portion is formed at the entrance of resin. Accordingly, the inner interposed member with the above-described configuration is excellent in terms of moldability, and can be precisely produced even when the thickness of the thin portion is small.

The reactor according to an embodiment may be such that an outer peripheral face of the inner interposed member has a shape that conforms to an inner peripheral face of the winding portion.

If the outer peripheral face of the inner interposed member has a shape that conforms to the shape of the inner peripheral face of the winding portion, there is almost no gap between the inner interposed member and the winding portion, and the clearance between the outer peripheral face of the inner interposed member and the inner peripheral face of the winding portion can be easily made smaller. As a result, the heat dissipation properties and the magnetic characteristics of the reactor can be easily improved.

The reactor according to an embodiment may be such that a thickness of the inner interposed member gradually increases from the thin portion toward the thick portion.

If a thickness of the inner interposed member gradually increases from the thin portion toward the thick portion, the moldability of the inner interposed member can be improved. Examples of the configuration in which the thickness gradually increases from the thin portion toward the thick portion include a configuration in which a portion from the thin portion toward the thick portion is formed as a curved face or an inclined face. The moldability of the inner interposed member is improved due to the above-described configuration, because, when producing an inner interposed member through injection molding, resin that is injected into a portion, in the mold, at which the thick portion is to be formed smoothly flows into the portion at which the thick portion is to be formed.

The reactor according to an embodiment may be such that the clearance formed between the inner interposed member and the winding portion is more than 0 mm and 0.3 mm or less.

If the clearance described above is more than 0 mm and 0.3 mm or less, the heat dissipation properties and the magnetic characteristics of the reactor can be further improved.

Hereinafter, embodiments of the reactor according to the present disclosure will be described with reference to the drawings. Constituent elements with the same names are denoted by the same reference numerals in the drawings. Note that the present disclosure is defined by the claims without being limited to these configurations shown in the embodiments, and all modifications within the meaning and scope that are equivalent to the claims are intended to be included herein.

Overall Configuration

A reactor1shown inFIG. 1includes an assembly10obtained by combining a coil2, a magnetic core3, and an insulating interposed member4. One of the characteristics of the reactor1is that part of the insulating interposed member4(later-described inner interposed members41inFIGS. 2 and 3) has a shape different from that of conventional examples. First, constituent elements of the reactor1will be briefly described with reference toFIGS. 1 and 2, and then the shape of the inner interposed members41, and a relationship between the inner interposed members41, and the magnetic core3and winding portions2A and2B arranged inside and outside the inner interposed members41will be described in detail with reference toFIGS. 3 to 5.

The coil2in this embodiment includes a pair of winding portions2A and2B arranged side by side, and a connection portion2R for connecting the winding portions2A and2B. Two ends2aand2bof the coil2respectively extend from the winding portions2A and2B, and are connected to an unshown terminal member. An external apparatus such as a power source for supplying electric power to the coil2is connected via this terminal member. The winding portions2A and2B included in the coil2of this example are substantially in the shape of angular tubes in the same winding direction with the same number of turns, and are arranged side by side such that their axial directions are in parallel with each other. The numbers of turns or the wire cross-sectional areas of the winding portions2A and2B may be different from each other. Furthermore, the connection portion2R of this example is formed by joining the ends of wires of the winding portions2A and2B with each other through welding or crimping, for example. It is also possible that the coil2is formed by helically winding one winding wire with no joint portion.

The coil2including the winding portions2A and2B can be constituted by a coated wire including an insulating coating made of an insulating material on the outer periphery of a conductor such as a flat wire or a round wire made of a conductive material such as copper, aluminum, magnesium, or alloys thereof. In this embodiment, the winding portions2A and2B are formed by edgewise winding a coated flat wire in which a conductor is constituted by a copper flat wire and an insulating coating is made of an enamel (typically, polyamide imide).

Magnetic Core

As shown inFIG. 2, the magnetic core3of this example can be divided into inner core portions31and outer core portions32. The inner core portions31are portions arranged inside the winding portions2A and2B of the coil2, and, in this example, are arranged inside the inner interposed members41, and thus they are located at positions not seen inFIG. 2. The inner core portions31of this example are each formed by combining two divided pieces. Here, the inner core portions31refer to portions along the axial direction of the winding portions2A and2B of the coil2, in the magnetic core3. For example, portions projecting from the inside of the winding portions2A and2B to the outside of the end faces are also part of the inner core portions31. The inner core portions31on the whole have a shape that substantially conforms to the inner shape of the winding portion2A (2B), and, in the case of this example, the shape is substantially a cuboid.

The outer peripheral faces of the inner core portions31of this example have a concavo-convex shape. The concavo-convex shape of the outer peripheral faces of the inner core portions31conforms to the shape of the inner peripheral faces of the later-described inner interposed members41. The configuration of this concavo-convex shape will be described later in detail with reference toFIGS. 3 to 6.

The outer core portions32are portions arranged outside the winding portions2A and2B, and each have a shape connecting ends of a pair of inner core portions31. The outer core portions32of this example are each in the shape of a cuboid. The lower faces of the outer core portions32are substantially flush with the lower faces of the winding portions2A and2B of the coil2(seeFIG. 1). It will be appreciated that the lower faces do not necessarily have to be flush with each other.

The core portions31and32may be constituted by molded articles made of a composite material containing soft magnetic powder and resin. The soft magnetic powder is an aggregate of magnetic particles made of iron-group metals such as iron or an alloy thereof (an Fe—Si alloy, an Fe—Si—Al alloy, an Fe—Ni alloy, etc.). The surface of magnetic particles may also be provided with an insulating coating made of phosphate or the like. Examples of the resin include thermosetting resins such as epoxy resins, phenolic resins, silicone resins, and urethane resins, and thermoplastic resins such as polyphenylene sulfide (PPS) resins, polyamide (PA) resins (e.g., nylon6or nylon66), polyimide resins, and fluororesins.

The amount of soft magnetic powder contained in the composite material may be 50 vol % or more and 80 vol % or less, where the amount of composite material is assumed to be 100 vol %. When the amount of magnetic powder contained in the composite material is 50 vol % or more, the proportion of the magnetic component is sufficiently high, and it is easy to increase the saturation magnetic flux density. On the other hand, when the amount of magnetic powder contained in the composite material is 80 vol % or less, the mixture of magnetic powder and resin has high fluidity, and the composite material can exert excellent moldability. The lower limit of the amount of magnetic powder contained in the composite material may be 60 vol % or more. Furthermore, the upper limit of the amount of magnetic powder contained in the composite material may be 75 vol % or less, and further may be 70 vol % or less.

Contrary to this example, the core portions31and32also may be constituted by powder compacts that are obtained by compression molding a raw material powder containing soft magnetic powder. The soft magnetic powder may be the same as the soft magnetic powder that can be used for the molded articles made of the composite material. It is also possible that one of the inner core portions31and the outer core portions32is a molded article made of a composite material, and the other is a powder compact.

Insulating Interposed Member

The insulating interposed member4is a member for ensuring insulation between the coil2and the magnetic core3, and is formed by combining the inner interposed members41interposed between the inner peripheral faces of the winding portions2A and2B and the outer peripheral faces of the inner core portions31, and the end face interposed member42interposed between the end faces of the winding portions2A and2B and the outer core portions32. In this example, the insulating interposed member4is used as a pair of molded core members5A and5B formed in one piece with the inner core portions31. The molded core members5A and5B of this example may have the same shape, or the molded core member5A located on the side on which the ends2aand2bof the winding portions2A and2B are arranged and the molded core member5B located on the side on which the connection portion2R is arranged may have different shapes.

The molded core members5A and5B are members that are each substantially in the shape of the letter “n” formed by combining a pair of inner core portions31, a pair of inner interposed members41that respectively covers the outer peripheries of the inner core portions31, and a frame-like end face interposed member42into one piece. In production of the molded core members5A and5B in which the inner interposed members41and the end face interposed member42are formed by arranging the inner core portions31inside a mold and injecting resin into the mold, a positioning member for locating the inner core portions31away from the inner peripheral face of the mold and positioning the inner core portions31inside the mold is used. Accordingly, in the molded core members5A and5B, the positioning member is embedded in the inner interposed members41, that is, the positioning member constitutes part of the inner interposed members41. In view of this aspect, it is preferable that the positioning member is made of an insulating resin. It is more preferable that, in order to align the coefficients of thermal expansion of portions of the inner interposed members41, the entire inner interposed members41including the positioning member is the same type of insulating resin.

Two turn accommodating portions42s(in particular, see the molded core member5B) that accommodate axial direction ends of the winding portions2A and2B are formed on the face, on the coil2side, of each end face interposed member42. The turn accommodating portions42sare recesses with a shape that conforms to the shape of the axial direction end faces of the winding portions2A and2B, and are formed so as to allow the entire end faces to be in contact with the end face interposed member42. Furthermore, a partitioning portion42dthat is arranged between the winding portions2A and2B and is used to partition the winding portions2A and2B from each other is formed on the face, on the coil2side, of each end face interposed member42.

Here, each of the molded core members5A and5B of this example is molded such that the inner interposed members41and the end face interposed member42are formed in one piece, and the portions, indicated by the dashed double dotted lines, of the molded core member5A are the inner interposed members41.

The insulating interposed member4with the above-described configuration may be made of, for example, a thermoplastic resin such as a PPS resin, a polytetrafluoroethylene (PTFE) resin, a liquid crystal polymer (LCP), a PA resin (e.g., nylon6or nylon66), a polybutylene terephthalate (PBT) resin, or an acrylonitrile butadiene styrene (ABS) resin. Alternatively, the insulating interposed member4may be made of a thermosetting resin such as an unsaturated polyester resin, an epoxy resin, a urethane resin, or a silicone resin. It is also possible to improve the heat dissipation properties of the insulating interposed member4by mixing a ceramic filler into the aforementioned resins. Examples of the ceramic filler include non-magnetic powder of alumina or silica.

Other Configurations

The reactor1of this example has a configuration without a casing, but also may have a configuration in which the assembly10is arranged inside a casing.

Relationship Between Inner Interposed Member, and Inner Core Portion and Winding Portion

FIG. 3is a cross-sectional view taken along the line III-III that is orthogonal to the axial direction of the winding portions2A and2B inFIG. 1. InFIG. 3, the connection portion2R is not shown. Furthermore, inFIG. 3, shapes of constituent elements and an clearance therebetween are exaggerated.

As shown in an enlarged view enclosed in a circle inFIG. 3, a plurality of interposed-side recess portions411are formed on an inner peripheral face410of the inner interposed member41. The inner interposed member41includes thin portions41awith a small thickness due to the inner peripheral face410being recessed to form the interposed-side recess portions411, and thick portions41bwith a thickness larger than that of the thin portions41a.

There is no particular limitation on the shape of the inner peripheral faces of the interposed-side recess portions411in a cross-section that is orthogonal to the direction in which the interposed-side recess portions411extend (the depth direction of the section of the diagram ofFIG. 3, which is the same as the axial direction of the winding portions2A and2B). For example, the inner peripheral faces of the interposed-side recess portions411may be in the shape of semicircular arcs as shown inFIG. 3, or may be substantially in the shape of rectangles as shown inFIG. 4. Alternatively, the inner peripheral faces of the interposed-side recess portions411may be in the shape of V-shaped grooves or dovetail grooves.

A thickness t1of the thin portions41ais 0.2 mm or more and 1.0 mm or less, and a thickness t2of the thick portions41bis 1.1 mm or more and 2.5 mm or less. The thickness t1of the thin portions41ais the thickness of a portion corresponding to the deepest position in the interposed-side recess portions411as shown inFIGS. 3 and 4, that is, the smallest thickness of the thin portions41a. The thickness t1of the thin portions41ais apparently smaller than the thickness of conventional inner interposed members with a uniform thickness (e.g., 2.5 mm). Furthermore, the thickness t2of the thick portions41bis the largest thickness at portions at which the interposed-side recess portions411are not present.

When producing the inner interposed members41with the above-described configuration on the outer peripheries of the inner core portions31through injection molding, resin that is injected into portions with a large gap between a mold for injection molding and the inner core portions31(hereinafter, referred to as a “gap in a mold”) forms the thick portions41b, and resin that is injected into portions with a small gap in the mold forms the thin portions41a. The portions with a large gap in a mold have a function of quickly supplying resin to the entire gap in the mold. Accordingly, even when the inner interposed members41include the thin portions41awith a thickness smaller than that of conventional examples, if they include the thick portions41bwith a thickness that is greater than or equal to a predetermined thickness, they can be easily produced as designed, and the inner interposed members41can be brought into substantially close contact with the entire outer peripheries of the inner core portions31. If variations in dimensions of the inner interposed members41are small, the inner interposed members41can be designed such that an inner clearance c1between the inner core portions31and the inner interposed members41and an outer clearance c2between the inner interposed members41and the winding portions2A and2B are small. Even when the outer clearance c2is small, the occurrence of a problem that the inner interposed members41cannot be inserted into the winding portions2A and2B, for example, can be suppressed because the level of precision of the dimensions of the inner interposed members41is high.

In consideration of the moldability of the inner interposed members41, it is preferable that the plurality of interposed-side recess portions411are present in a dispersed manner in the circumferential direction of the inner peripheral faces410of the inner interposed members41. In other words, this configuration is a configuration in which a plurality of thick portions41band a plurality of thin portions41aare present in a dispersed manner in the circumferential direction of the inner interposed members41. In the mold for producing the inner interposed members41, a portion with a small gap and a portion with a large gap are alternately arranged in the circumferential direction of the gap in the mold into which resin is injected. In this mold, it is easy to supply resin into the entire gap in the mold when injecting the resin, and thus the inner interposed members41with small variations in dimensions can be easily produced. In particular, if the thin portions41aand the thick portions41bare along the axial direction of the inner interposed members41as in this example, it is easier to inject resin into the mold during molding.

Furthermore, in consideration of the moldability of the inner interposed members41, it is preferable that at least some of the thick portions41breach the end faces of the inner interposed members41in the axial direction of the winding portions2A and2B. It is preferable that all the thick portions41breach the end faces of the inner interposed members41shown inFIG. 2. When producing the inner interposed members41through injection molding, in many cases, resin is injected from a position in a mold at which an end face of an inner interposed member41is to be formed. In this case, if the gap through which resin enters the mold is large, the moldability of the inner interposed members41is improved. That is to say, the inner interposed members41including the thick portions41bthat reach the end faces of the inner interposed members41are excellent in terms of moldability, and they can be precisely produced even when the thickness of the thin portions41ais small.

Meanwhile, the inner core portion31arranged inside each inner interposed member41described above includes core-side projecting portions311that are formed on an outer peripheral face (the core outer peripheral face319) of the inner core portion31(seeFIG. 5as well). In this example, the inner interposed members41are molded on the inner core portions31, and thus the interposed-side recess portions411that are formed on the inner peripheral face410of each inner interposed member41are formed in a shape that conforms to the core-side projecting portions311. As described above, the thickness of the thin portions41aof the inner interposed members41at which the interposed-side recess portions411are formed is smaller than the thickness of conventional inner interposed members with a uniform thickness. Accordingly, the cross-sectional area of a magnetic path in the inner core portions31including the core-side projecting portions311that are arranged at the interposed-side recess portions411is reliably larger, by the cross-sectional area of the core-side projecting portions311, than that of conventional inner core portions.

It is preferable that outer peripheral faces419of the inner interposed members41have a shape that conforms to the shape of the inner peripheral faces of the winding portions2A and2B. Accordingly, the outer clearance c2between the outer peripheral faces419of the inner interposed members41and coil inner peripheral faces210of the winding portions2A and2B can be easily made smaller. Specifically, the outer clearance c2can be easily made to more than 0 mm and 0.3 mm or less. Since the outer clearance c2can be made smaller, the distance from the inner core portions31to the winding portions2A and2B can be made smaller, the heat dissipation properties from the inner core portions31to the winding portions2A and2B can be improved, and the cross-sectional area of a magnetic path in the inner core portions31can be increased. The outer clearance c2is preferably 0.2 mm or less, and more preferably 0.1 mm or less, in order to smoothly insert the inner interposed members41into the winding portions2A and2B, to improve the heat dissipation properties from the inner core portions31to the winding portions2A and2B, and to increase the cross-sectional area of a magnetic path in the inner core portions31.

More Preferable Configurations

In consideration of the fact that portions that have a large gap in a mold and that correspond to the thick portions41bprovide good moldability of the inner interposed members41, it is preferable that the difference between the thickness t1of the thin portions41aand the thickness t2of the thick portions41b(the thickness t2—the thickness t1) is 0.2 mm or more. When the thin portions41aand the thick portions41bare prescribed as specific numerical values, it is preferable that the thickness t1of the thin portions41ais 0.2 mm or more and 0.7 mm or less, and the thickness t2of the thick portions41bis 1.1 mm or more and 2.0 mm or less, and it is more preferable that the thickness t1of the thin portions41ais 0.2 mm or more and 0.5 mm or less, and the thickness t2of the thick portions41bis 1.1 mm or more and 2.0 mm or less.

If the thickness of the inner interposed members41gradually increases from the thin portions41atoward the thick portions41b, the moldability of the inner interposed members41can be improved. The reason for this is that, when producing the inner interposed members41through injection molding, resin that is injected into portions, in the mold, at which the thick portions41bare to be formed smoothly flows into the portions at which the thin portions41aare to be formed. Specific examples of this configuration include a configuration as shown inFIGS. 3 and 4in which a width direction edge of each thin portion41a(an edge in the direction in which a thick portion41bis present) has a rounded shape that is recessed to the outside of the inner interposed member41. It is also preferable that a width direction edge of each thick portion41b(an edge in the direction in which a thin portion41ais present) has a rounded shape that is projected to the outside of the inner interposed member41. The above-described width direction edges may be in the shape of an arc, and, in this case, the radius of curvature of the arc may be 0.05 mm or more and 20 mm or less, and further may be 0.1 mm or more and 10 mm or less. If the radius of curvature of the arc is large, as shown inFIG. 3, the width direction edges of the thin portions41aand the width direction edges of the thick portions41bare connected, and the inner peripheral faces410of the inner interposed members41are in the shape of waves. On the other hand, if the radius of curvature of the arc is small, as shown inFIG. 4, the inner peripheral faces410of the inner interposed members41have a shape in which the interposed-side recess portions411in the shape of rectangular grooves with rounded corners are arranged in a line. Alternatively, the inner peripheral faces410of the inner interposed members41may have a shape in which the interposed-side recess portions411in the shape of V-shaped grooves with rounded corners are arranged in a line.

In the configuration in which the inner interposed members41are molded on the outer peripheries of the inner core portions31, it is preferable that the inner core portions31each include a plurality of core-side projecting portions311that are formed on the core outer peripheral face319, as shown inFIG. 5. The core-side projecting portions311inFIG. 5are formed in the shape of ridges along the axial direction of the inner core portions31, and the core-side projecting portions311are arranged at predetermined intervals in the circumferential direction of the core outer peripheral face319. With such inner core portions31, it is easy to supply resin into the entire core outer peripheral faces319when molding resin from the end face side of the inner core portions31. The reason for this is that grooves formed between the core-side projecting portions311allow resin to move smoothly in the axial direction of the inner core portions31, and thus the resin is supplied from the positions of the grooves also to the outer peripheries of the core-side projecting portions311. If the inner core portions31are used, the interposed-side recess portions411of the inner interposed members41extend from end faces on one side to end faces on the other side in the axial direction of the inner interposed members41(which is the same as the axial direction of the winding portions2A and2B).

Also, an inner interposed member that includes an inner peripheral face that conforms to the inner core portion31as shown inFIG. 6may also be obtained. The inner core portion31inFIG. 6has a configuration in which the core-side projecting portions311on one side in the axial direction of the inner core portion31and the core-side projecting portions311on the other side are displaced from each other in the circumferential direction of the inner core portion31. When injecting resin from two end faces of the inner core portions31, it is easy to supply resin into the entire core outer peripheral faces319of the inner core portions31due to the same reason as that of the configuration inFIG. 5. In addition, it is also possible that the core-side projecting portions311are further extended in the axial direction of the inner core portions31, and grooves between the core-side projecting portions311adjacent to each other in the circumferential direction on one side and grooves between the core-side projecting portions311adjacent to each other in the circumferential direction on the other side are meshed with each other.

Method for Producing Reactor

The reactor1of Embodiment 1 can be produced by separately producing the coil2, the molded core members5A and5B, and the outer core portions32, and combining them. Specifically, the inner interposed members41of the molded core members5A and5B are inserted into the winding portions2A and2B of the coil2, and the outer core portions32are arranged on the outer side of the end face interposed members42of the molded core members5A and5B. The outer core portions32may be joined to the end face interposed members42using an adhesive or the like.

Modified Example 1-1

The divided state of the magnetic core3and the insulating interposed member4is not limited to that illustrated in Embodiment 1. For example, it is also possible to use a pair of molded core members each substantially in the shape of the letter “n” obtained by molding a pair of inner core portions31with about half the length and one outer core portion32using a material of the insulating interposed member4. Alternatively, it is also possible to use a pair of molded core members each substantially in the shape of the letter “L” obtained by molding one inner core portion31extending along the entire length of the winding portion2A (2B) and one outer core portion32using a material of the insulating interposed member4. Alternatively, it is also possible that two members obtained by molding the inner core portions31extending along the entire length of the winding portion2A (2B) using the inner interposed members41are prepared, and two outer core portions32are combined therewith to form the magnetic core3and the insulating interposed member4.

Modified Example 1-2

Contrary to the molded core members of Embodiment 1, it is also possible to use press-fitted core members obtained by forming the inner interposed members41through injection molding, and then press-fitting the inner core portions31to the inner interposed members41. With the configuration in which the inner core portions31are press-fitted to the inner interposed members41, the clearance between the inner core portions31and the inner interposed members41can be substantially 0 mm, that is, the inner core portions31and the inner interposed members41can be in substantially close contact with each other. The inner core portions31can be press-fitted to the inner interposed members41that have been already formed in this manner, because the inner interposed members41are constituted by the thin portions41aand the thick portions41band thus can be produced at a high level of precision of dimensions.

In Embodiment 1, an aspect was described in which the coil2includes a pair of winding portions2A and2B. Meanwhile, a configuration similar to that of Embodiment 1 can be applied to a reactor including a coil having one winding portion.

When using a coil having one winding portion, a magnetic core may be formed by combining two molded core members each substantially in the shape of the letter “E” when viewed from above. In this case, a projecting portion located at the middle of the letter “E” of the molded core member is inserted into a winding portion to form an inner core portion. Furthermore, portions other than the projecting portion located at the middle of the letter “E” of the molded core member form an outer core portion. It is apparent that the divided state of the magnetic core and the insulating interposed member is not limited to the shape of the letter “E”.

Applications

The reactor of the present disclosure can be utilized in a power conversion device such as a bidirectional DC-DC converter or the like that is installed in an electrically driven vehicle such as a hybrid car, an electric car, or a fuel cell car.