Reactor and manufacturing method thereof

Abstract

The present invention provides a reactor capable of suppressing leakage magnetic flux from a junction between a leg portion and a yoke portion of a core, and a method for manufacturing the same. The reactor of the present invention comprises: a core (2) having a plurality of legs (21) and a pair of yoke portions (22) disposed at both ends of the plurality of legs (21); and a coil (3) wound around the legs (21). At least one of the legs (21) or the yoke portion (22) comprises a composite magnetic material containing magnetic powder and resin, and the legs (21) and the yoke portion (22) are joined by the resin of the composite magnetic material.

Description

Technical Field

[0001] The present invention relates to a reactor and a method for manufacturing the same. The reactor includes a core containing magnetic powder and resin. Background Art

[0002] Reactors are used in various applications, such as office automation (OA) equipment, solar power generation systems, hybrid vehicles, electric vehicles, or fuel cell vehicle drive systems. This type of reactor includes: an annular core containing a magnetic material; a resin member covering the outer periphery of the annular core; and a coil wound around a portion of the outer periphery of the annular core via the resin member. The annular core has, for example: a pair of legs extending in a straight line; and a pair of yokes arranged at both ends of the legs and connecting the pair of legs. The annular core is formed by joining the pair of legs to the pair of yokes. Furthermore, when power is supplied from an external power source, current flows through the coil to generate magnetic flux, forming a magnetic circuit within the annular core.

[0003] [Prior art literature]

[0004] [Patent Document]

[0005] [Patent Document 1] Japanese Patent No. 5408272 Summary of the Invention

[0006] [Problems to be solved by the invention]

[0007] A magnetic gap of a specified width is sometimes provided at the junction of the legs and yoke that form the annular core. This gap prevents a decrease in the inductance on the high-current side of the reactor. Examples of such gaps include the use of gap materials such as spacers or the provision of an air gap. However, the presence of a gap can cause magnetic flux leakage through the gap, which can adversely affect peripheral equipment of the reactor.

[0008] Therefore, there are methods that directly bond the legs and yoke using adhesives without providing gap materials or air gaps. However, even when bonding the legs and yoke directly using adhesives, it is impossible to achieve a completely gap-free bond. When observed at a microscopic level, gaps are formed, which in turn cause magnetic flux leakage.

[0009] Furthermore, when the legs and yoke of a toroidal core are formed from materials with different magnetic permeabilities, magnetic flux tends to concentrate at the junction between the legs and the yoke. This means that magnetic flux is easily saturated at the junction between the legs and the yoke, increasing the likelihood of leakage flux. Since the coil is wound around the legs, it exists near the junction. Furthermore, this leakage flux induces current in the coil, increasing the AC losses of the reactor.

[0010] Therefore, by separating the junction between the coil, leg, and yoke, the increase in AC loss can be reduced. Another method for increasing the distance between the junction and the coil is to make the leg, on which the coil is wound, longer than the coil, thereby increasing the distance between the coil and the junction. However, this method requires the leg to be longer than the coil, which results in an increased size of the reactor.

[0011] Furthermore, in conventional reactors, pot cores, PQ cores, and E cores are partially made of resin, which disadvantageously traps heat from the coil inside the core. Consequently, there has long been a demand for reactors with improved heat dissipation.

[0012] The present invention aims to achieve at least any one of the following first, second, and third objectives.

[0013] A first object of the present invention is to provide a reactor and a method for manufacturing the same, the reactor being capable of suppressing leakage magnetic flux from a junction between a leg portion of a core and a yoke portion.

[0014] A second object of the present invention is to provide a reactor capable of reducing AC loss while maintaining miniaturization.

[0015] A third object of the present invention is to provide a reactor having improved heat dissipation performance.

[0016] [Technical means to solve the problem]

[0017] In order to achieve the first purpose, the inductor of the present invention includes: a core having a plurality of legs and a pair of yokes arranged at both ends of the plurality of legs; and a coil wound around the legs, at least either the legs or the yokes containing a composite magnetic material containing magnetic powder and resin, and the legs and the yokes are joined by the resin of the composite magnetic material.

[0018] In the manufacturing method of the inductor of the present invention, the inductor includes a core, the core includes a plurality of legs and yokes arranged at both ends of the plurality of legs, either the legs or the yokes contains a composite magnetic material containing magnetic powder and resin, and the manufacturing method of the inductor includes: an installation step of installing the coil on a resin component; a filling step of filling the resin component with the clay-like composite magnetic material; a pressurizing step of pressurizing the composite magnetic material injected into the resin component; and a curing step of curing the resin.

[0019] In order to achieve the second purpose, the inductor of the present invention includes: a core having a plurality of legs and a pair of yokes arranged at both ends of the plurality of legs; and a coil wound around the legs, the legs comprising a composite magnetic material containing magnetic powder and resin, the yoke comprising: a first component comprising the composite magnetic material; and a second component comprising a material different from the composite magnetic material, the first component being arranged on the side where the legs are arranged and formed integrally with the legs, the first component being joined to the second component, and the magnetic permeability of the second component being greater than the magnetic permeability of the legs and the first component.

[0020] In order to achieve the third purpose, the inductor of the present invention includes: a core, a middle leg having a wound coil, an outer leg arranged on the outside of the middle leg, and a yoke arranged at both ends of the middle leg and the two ends of the outer leg, the middle leg and the outer leg contain a composite resin material containing magnetic powder and resin, and form an opening portion for exposing the coil from the core, when the opening rate is 0% when the entire circumference of the coil is accommodated inside the core, and when the opening rate is 100% when the entire circumference of the coil is exposed from the core, the opening rate of the opening portion is set to more than 60%.

[0021] [Effects of the Invention]

[0022] According to the present invention, a reactor can be provided that can suppress leakage magnetic flux from a junction between a leg portion of a core and a yoke portion.

[0023] According to the present invention, it is possible to provide a reactor capable of reducing AC loss while maintaining miniaturization.

[0024] According to the present invention, a reactor can be provided in which the heat of the coil can be suppressed from being trapped inside the core by setting the opening ratio of the opening for exposing the coil from the core to more than 60%, thereby improving heat dissipation. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a perspective view showing the overall structure of the reactor according to the first embodiment.

[0026] Figure 2 It is an exploded perspective view showing the overall structure of the reactor according to the first embodiment.

[0027] Figure 3 This is a flowchart for explaining the method for manufacturing the reactor according to the first embodiment.

[0028] Figure 4 It is a perspective view showing the overall structure of a reactor according to Modification 1.

[0029] Figure 5It is an exploded perspective view showing the overall structure of a reactor according to Modification 1.

[0030] Figure 6 It is an exploded perspective view showing the overall structure of a reactor according to the second embodiment.

[0031] Figure 7 This is an enlarged plan view of the core of the second embodiment.

[0032] Figure 8 It is an exploded perspective view showing the overall structure of a reactor according to Modification 2.

[0033] Figure 9 It is a perspective view of the third embodiment.

[0034] Figure 10 It is an exploded perspective view of the third embodiment.

[0035] Figure 11 This is a side sectional view in which the resin member is omitted in the third embodiment.

[0036] Figure 12 It is a side view for explaining the effects of the third embodiment.

[0037] Figure 13 It is a perspective view of the fourth embodiment.

[0038] Figure 14 It is an exploded perspective view of the fourth embodiment.

[0039] Figure 15 This is a side sectional view in which the resin member is omitted in the fourth embodiment.

[0040] Figure 16 It is a diagram for explaining the shape of the yoke portion according to the fourth embodiment.

[0041] Figure 17 It is a diagram for explaining the shape of the yoke portion according to the fourth embodiment.

[0042] Figure 18 It is a diagram for explaining the shape of the yoke portion according to the fourth embodiment.

[0043] Figure 19 It is a diagram for explaining the shape of the yoke portion according to the fourth embodiment.

[0044] Figure 20 It is a diagram for explaining the shape of the yoke portion according to the fourth embodiment.

[0045] Figure 21 It is a perspective view of the fifth embodiment.

[0046] Figure 22 It is an exploded perspective view of the fifth embodiment.

[0047] Figure 23 It is a perspective view of the main parts of a modified example of the fifth embodiment.

[0048] Figure 24 It is an exploded perspective view of main parts of a modification example of the fifth embodiment.

[0049] Figure 25 It is a perspective view of the main parts of a modified example of the fifth embodiment.

[0050] Figure 26 It is an exploded perspective view of main parts of a modification example of the fifth embodiment.

[0051] Figure 27 Graphs showing the inductance values of Example 4, Comparative Examples 5, and 6.

[0052] Figure 28 This is a graph showing the AC loss when the thickness of the first member relative to the entire yoke is changed.

[0053] Figure 29 This is a graph showing the inductance value when the thickness of the first member relative to the entire yoke is changed.

[0054] [Explanation of Symbols]

[0055] 1: Reactor

[0056] 2: Core

[0057] 21: Feet

[0058] 22a: First component

[0059] 22b: Second component

[0060] 22: Yoke

[0061] 23: Midfoot

[0062] 24: Outside Foot

[0063] 25: Yoke

[0064] 25a: Extension

[0065] 25b, 25c: Chamfered parts

[0066] 26, 28, 30: Opening

[0067] 27a, 27b, 27c: Yoke (X-shaped)

[0068] 29: Opening

[0069] 3: Coil

[0070] 4: Resin components

[0071] 41: Straight line

[0072] 42: Connection

[0073] 5: Invalid space DETAILED DESCRIPTION

[0074] (First embodiment)

[0075] (constitute)

[0076] Hereinafter, the reactor according to the present embodiment will be described with reference to the drawings. Figure 1 It is a perspective view showing the overall structure of the reactor according to the first embodiment. Figure 2 1 is an exploded perspective view showing the overall structure of the reactor according to Embodiment 1. The positional relationship of the components described here does not reflect the positional relationship when the reactor 1 is mounted on an actual device.

[0077] The reactor 1 is an electromagnetic component that converts electrical energy into magnetic energy, stores it, and releases it, and is used for voltage step-up and step-down, etc. The reactor 1 of this embodiment includes a core 2 , a coil 3 , and a resin member 4 .

[0078] The core 2 has a plurality of legs 21 and a pair of yokes 22 arranged at both ends of the plurality of legs 21. In the present embodiment, there are two legs 21, and their shape is cylindrical, but it is not limited to this. The outer peripheral surface of the leg 21 is covered by a resin member 4. The two legs 21 are arranged so that the cylindrical axes become parallel. At least one of the legs 21 and the yoke 22 is a metal composite core (MC core) containing a composite magnetic material containing magnetic powder and resin. In the present embodiment, the leg 21 contains a composite magnetic material.

[0079] The entire outer surface of the MC core is a non-sliding surface. An MC core is formed by placing a composite magnetic material containing magnetic powder and resin into a container of a specified shape and solidifying the resin. In other words, applying pressure, as is done for powder cores, is not a necessary condition for forming MC cores. Furthermore, even when pressurized, unlike powder cores, which are formed by pressing magnetic powder covered with an insulating film with several tons to tens of tons, a low pressure of several kilograms to several tens of kilograms is sufficient to increase the density of the MC core.

[0080] Since MC cores are not pressurized or are pressurized at low pressure, the mold and core move simultaneously due to friction, preventing the formation of sliding surfaces with the numerous linear marks on the core surface. Consequently, the entire outer circumference of the MC core becomes a non-sliding surface. Furthermore, while powder cores pressurize the magnetic powder at several to several dozen tons, this can cause deformation. However, MC cores, also pressurized at several to several dozen kilograms, do not deform the magnetic powder.

[0081] Soft magnetic powder can be used as magnetic powder, and in particular, Fe powder, Fe-Si alloy powder, Fe-Al alloy powder, Fe-Si-Al alloy powder (sendust), amorphous metal powder (amorphous powder), or a mixture of two or more of these powders can be used. As Fe-Si alloy powder, for example, Fe-6.5% Si alloy powder and Fe-3.5% Si alloy powder can be used. The average particle size (D50) of the soft magnetic powder is preferably 20μm to 150μm. In addition, the so-called "average particle size" in this specification refers to D50, that is, the median particle size, unless otherwise specified.

[0082] The resin is mixed with the magnetic powder and the magnetic powder is retained. The resin may be a thermosetting resin, a UV curable resin, or a thermoplastic resin. Examples of thermosetting resins include phenol resins, epoxy resins, unsaturated polyester resins, polyurethane, diallyl phthalate resins, and silicone resins. Examples of UV curable resins include urethane acrylate, epoxy acrylate, acrylate, and epoxy resins. The thermoplastic resin is preferably a resin with excellent heat resistance, such as polyimide or fluororesin. The viscosity of epoxy resins cured by adding a curing agent can be adjusted by adjusting the amount of curing agent added.

[0083] The resin content is preferably 3-5% by weight relative to the magnetic powder. If the resin content is less than 3% by weight, the bonding strength of the magnetic powder is insufficient, reducing the mechanical strength of the core. If the resin content exceeds 5% by weight, the magnetic powder cannot be tightly held, resulting in a decrease in core density and magnetic permeability.

[0084] The yoke 22 can use a pressed powder core, a ferrite core, and a laminated steel plate. In this embodiment, the yoke 22 uses a pressed powder core. The yoke 22 is a block-shaped core. The end face of the yoke 22 on the opposite side to the leg 21 is preferably flat. As described later, the pressed powder core constituting the yoke 22 becomes an extrusion member for extruding the composite magnetic material. Therefore, the reason is that by making the end face of the yoke 22 on the opposite side to the leg 21 flat, the composite magnetic material can be extruded with uniform force.

[0085] The yoke 22 preferably has a higher magnetic permeability than the leg 21. The higher magnetic permeability of the yoke 22 than the leg 21 allows more magnetic flux generated by the leg 21 around which the coil 3 is wound to be captured.

[0086] The yoke 22 is arranged at both ends of the leg 21. The yoke 22 is joined to the ends of the leg 21 by the resin of the composite magnetic material of the leg 21. In other words, the leg 21 and the yoke 22 are joined without using an adhesive or the like. The yoke 22 is seamlessly and continuously joined to the leg 21. The resin of the composite magnetic material constituting the leg 21 permeates the yoke 22. Specifically, the resin of the composite magnetic material permeates the interior of the pressed powder magnetic core. In addition, there are a plurality of fine bumps and depressions on the end face of the yoke 22 that is joined to the leg 21. The size of the bumps and depressions is, for example, on the order of several tens of microns.

[0087] The irregularities may be formed by powders such as magnetic powder during the compacting of compacts such as powdered magnetic cores and ferrites, or by roughening the surface of the compact after compacting using a file, sandblasting, or the like. Furthermore, in the case of laminated steel sheets, the irregularities may be formed by the step differences resulting from lamination, or may be formed on the surface of the compact after lamination. The resin of the composite magnetic material enters the concave portions of the irregularities.

[0088] like Figure 2 As shown, there are two coils 3. The coil 3 includes two conductive members that are insulated and coated with enamel or the like. Copper wire or aluminum wire can be used as the conductive member. In this embodiment, copper wire is used. The coil 3 has a cylindrical shape with both ends open and wound with copper wire. Lead wires are led out from both ends of the coil 3. The two coils 3 are arranged so that the winding axis directions of the coils 3 become parallel. The inner circumferential surface of the coil 3 is covered by the resin member 4. That is, the coil 3 is wound around the leg 21 via the resin member 4.

[0089] In this embodiment, the coil 3 is cylindrical, but the shape of the coil 3 is not limited thereto and may be rectangular. The number of coils 3 is not limited to two and may be one or three or more.

[0090] The resin member 4 covers the periphery of the core 2 and insulates the core 2 from the coil 3. Examples of the resin constituting the resin member 4 include epoxy resin, unsaturated polyester resin, urethane resin, bulk molding compound (BMC), polyphenylene sulfide (PPS), and polybutylene terephthalate (PBT).

[0091] like Figure 2 As shown, the resin member 4 is divided into two parts. The divided resin member 4 has a generally U-shaped shape. The resin member 4 has a pair of straight portions 41 for mounting the coil 3 and a connecting portion 42 connecting the pair of straight portions 41. The resin member 4 is integrally formed by joining the ends of the straight portions 41 with an adhesive or the like.

[0092] The straight portion 41 has a cylindrical shape. The leg 21 is arranged on the inner circumference of the straight portion 41. The leg 21 including the composite magnetic material and the straight portion 41 are integrally formed by the resin of the composite magnetic material. That is, there is no gap between the leg 21 and the straight portion 41. In addition, the coil 3 is wound on the outer circumference of the straight portion 41. The connecting portion 42 has two openings with a diameter roughly the same as the inner circumference of the straight portion 41 at the end face connecting the straight portion 41. In addition, the end face opening on the opposite side to the end face connecting the straight portion 41 is the connecting portion 42. The formed yoke 22 is inserted from the opening. That is, the size of the opening becomes roughly the same size as the yoke 22.

[0093] (Method for Manufacturing Reactor)

[0094] The manufacturing method of the reactor 1 according to this embodiment will be described with reference to the accompanying drawings. Figure 3 As shown, the method for manufacturing a reactor according to the present embodiment includes (1) a mounting step, (2) a filling step, (3) a pressurizing step, and (4) a curing step.

[0095] (1) Installation process (step S01)

[0096] The installation process involves attaching coil 3 to resin member 4. Straight portions 41 of resin member 4 are inserted through the openings at both ends of coil 3. Adhesive is applied to the ends of straight portions 41, and the straight portions 41 of resin member 4 inserted through the coil openings are joined together within coil 3. In other words, the two-part resin member 4 is integrated.

[0097] (2) Filling process (step S02)

[0098] The filling process is a process of filling the inside of the straight portion 41 with a composite magnetic material containing magnetic powder and resin. In this process, first, the magnetic powder is mixed with the resin to produce a clay-like composite magnetic material. The clay-like composite magnetic material obtains the desired viscosity by the viscosity of the added resin. When mixed with the magnetic powder, the viscosity of the added resin is preferably 50mPa·s to 5000mPa·s. If the viscosity is less than 50mPa·s, the resin will not be entangled with the magnetic powder during mixing, and the magnetic powder and the resin will easily separate in the container, resulting in uneven density or strength of the core. If the viscosity exceeds 5000mPa·s, the viscosity will increase excessively, for example, the resin formed between the first magnetic powders will enter, and the second magnetic powder will not be able to fill the gap, etc., the density of the core will decrease, and the magnetic permeability will decrease.

[0099] The magnetic powder and resin can be mixed automatically or manually using a specified mixer. The mixing time can be set appropriately, but is not particularly limited thereto; for example, it can be set to 2 minutes. By mixing the magnetic powder and resin in this manner, a clay-like composite magnetic material can be obtained. A specified amount of the clay-like composite magnetic material is filled from the opening of the connecting portion 42 into the interior of the straight portion 41.

[0100] (3) Pressurization process (step S03)

[0101] The pressurizing process is a process of squeezing the composite magnetic material using the pressed powder core constituting the yoke 22. The pressed powder core is formed into a block shape in advance. The pressed powder core is formed by providing concave and convex surfaces on the surfaces where the composite magnetic materials constituting the yoke 22 are joined. The pressed powder core is inserted into each connecting portion 42 so that the surface with the concave and convex surfaces contacts the composite magnetic material. Then, the composite magnetic material filled in the straight portion 41 is squeezed using the pressed powder core inserted into each connecting portion 42. That is, the pressed powder core constituting the yoke 22 acts as a squeezing member. The composite magnetic material is pressurized from both ends of the straight portion 41. The time for squeezing the composite magnetic material can be appropriately changed according to the content or viscosity of the resin, for example, 10 seconds. By squeezing using the pressed powder core, the composite magnetic material is expanded into the internal shape of the straight portion 41, and the voids contained in the composite magnetic material are reduced, thereby increasing the apparent density.

[0102] The pressure for extruding the composite magnetic material is preferably 6.3 kg / cm 2 If it is less than the above value, the extrusion pressure is small and the effect of increasing the apparent density is small. In addition, even if it is above the above value, it is preferably 15.7 kg / cm 2 The reason for this is that even if the extrusion exceeds the above value, the effect of increasing the apparent density is small. In addition, if the extrusion exceeds the above value, only the resin is squeezed, and the insulation between the magnetic powders is deteriorated.

[0103] (4) Curing process (step S04)

[0104] The curing process is a process for curing the resin contained in the composite magnetic material filled into the leg portion 21 in the filling process. When the resin filled into the leg portion 21 is cured by drying, the drying environment can be set to an atmospheric environment. The drying time can be appropriately changed according to the type, content, drying temperature, etc. of the resin. For example, it can be set to 1 hour to 4 hours, but it is not limited to this. The drying temperature can be appropriately changed according to the type, content, drying time, etc. of the resin. For example, it can be set to 85°C to 150°C, but it is not limited to this. In addition, the drying temperature is the temperature of the drying environment.

[0105] Furthermore, curing of the resin is not limited to drying, and the curing method varies depending on the type of resin. For example, if the resin is a thermosetting resin, it is cured by heating, while if the resin is an ultraviolet curable resin, it is cured by irradiating the molded body with ultraviolet rays.

[0106] The curing process can also be repeated many times with the operation of making the molded body solidify the prescribed time at a prescribed temperature. In addition, for example, when resin is solidified by drying, it is also possible to make drying temperature or drying time different at each of the repeated times.

[0107] While the leg portion 21 is formed of a composite magnetic material in this embodiment, the yoke portion 22 may also be formed of a composite magnetic material. In this case, the core forming the leg portion 21 is pre-molded. In the installation step, the straight portion 41 is inserted into the coil 3, and the molded leg 21 is inserted into the interior of the straight portion 41. In the filling step, clay-like composite magnetic material is filled into the opening of the connecting portion 42. Subsequently, in the pressurizing step, the composite magnetic material filled into the connecting portion 42 is pressurized using a pressing member, and in the curing step, the resin contained in the composite magnetic material is cured.

[0108] (Effect)

[0109] The reactor 1 of this embodiment includes a core 2 having a plurality of legs 21 and a pair of yokes 22 disposed at opposite ends of the legs 21; and a coil 3 wound around the core 2, wherein either the legs 21 or the yokes 22 are formed from a composite magnetic material containing magnetic powder and resin, and the legs 21 and yokes 22 are bonded together by the resin of the composite magnetic material. This allows the legs 21 and yokes 22 to be seamlessly and continuously bonded, eliminating gaps at the bonded portion and suppressing magnetic flux leakage from the bonded portion between the legs 21 and yokes 22.

[0110] Furthermore, the leg 21 and yoke 22 are joined together using a resin composite of magnetic materials. In other words, this resin replaces adhesives, eliminating the need for adhesives to join the leg 21 and yoke 22. This eliminates the need for adhesives to join the leg 21 and yoke 22, and reduces costs by eliminating the need for adhesives.

[0111] The magnetic permeability of the yoke 22 is greater than that of the leg 21. Thus, the yoke 22 captures more magnetic flux generated by the leg 21 around which the coil 3 is wound. Therefore, leakage magnetic flux from the yoke 22 can be suppressed.

[0112] In the leg portion 21 or yoke portion 22, which does not contain the composite magnetic material, the end surfaces where the leg portion 21 and yoke portion 22 meet have irregularities. As a result, the resin contained in the composite magnetic material enters these irregularities, allowing the leg portion 21 and yoke portion 22 to be more firmly joined due to the anchoring effect. This tighter joining reduces magnetic flux leakage.

[0113] The leg portion 21 and the straight portion 41 are integrally formed without a gap from the composite magnetic material that constitutes the leg portion 21. This eliminates the need to consider the dimensional tolerances between the leg portion 21 and the straight portion 41 and allow the inner circumference of the straight portion 41 to be larger than that of the leg portion 21, thereby enabling a reduction in the size of the reactor 1. Furthermore, the leg portion 21, and therefore the core 2, can be enlarged by an amount corresponding to the gap between the leg portion 21 and the straight portion 41, which is formed to allow for dimensional tolerances and allow the straight portion 41 to be larger than the leg portion 21. This improves the characteristics of the reactor 1.

[0114] The reactor manufacturing method of this embodiment includes: an installation step of installing coil 3 on resin member 4; a filling step of filling resin member 4 with coil 3 installed with composite magnetic material; a pressurizing step of pressurizing the composite magnetic material injected into resin member 4 via yoke 22; and a curing step of curing the resin. Specifically, core 2 constituting yoke 22 serves as a pressing member to pressurize the composite magnetic material constituting leg 21.

[0115] This eliminates the need for preparing separate extruded components, reducing the number of parts required to manufacture the reactor 1. Furthermore, the leg 21 and the yoke 22 are joined together using the resin contained in the composite magnetic material, eliminating the need for applying an adhesive to join the leg 21 and the yoke 22. This reduces the number of manufacturing steps required for the reactor 1.

[0116] (Variation 1)

[0117] A reactor according to Modification 1 will be described with reference to the drawings. Figure 4 It is a perspective view showing the overall structure of a reactor according to Modification 1. Figure 5: is an exploded perspective view showing the overall structure of the reactor of Modification Example 1. Figure 4 、 Figure 5 As shown, in the first embodiment, the coils are wound around all the legs, but in Modification 1, there is a leg 21 around which the coil 3 is not wound.

[0118] Specifically, it has three legs 21. These three legs 21 are arranged parallel to the winding axis of coil 3. Of these three parallel legs 21, the center leg 23, around which coil 3 is wound, is located. On either side of center leg 23 are outer legs 24, around which no coil 3 is wound. Center leg 23 and the two outer legs 24 are MC cores.

[0119] The yoke 22 connects the center leg 23 and the two outer legs 24. The yoke 22 is a pressed powder magnetic core. The yoke 22 is bonded to the ends of the center leg 23 and the outer legs 24 using a resin composite of the magnetic material of the center leg 23 and the outer legs 24. The yoke 22, center leg 23, and outer legs 24 are seamlessly and continuously bonded.

[0120] As described above, in Modification 1, the number of joints between the yoke 22 and the legs 21 is two greater than in the first embodiment. Specifically, in the first embodiment, there are four joints, at the ends of the two legs 21. In contrast, in Modification 1, there are six joints, at the ends of the center legs 23 and the ends of the two outer legs 24.

[0121] If these six joints were joined separately using adhesives or the like, gaps would form at each joint, thereby generating more leakage flux. However, in this modified example, the center leg 23, the outer leg 24, and the yoke 22 are joined by a resin made of a composite magnetic material. That is, the joints between the center leg 23, the outer leg 24, and the yoke 22 are seamless and continuous, and are joined without gaps. Therefore, the leakage flux generated from the joints between the center leg 23, the outer leg 24, and the yoke 22 can be suppressed. In this way, when there are many joints between the leg 21 and the yoke 22, the leakage flux can be more significantly suppressed.

[0122] (Second embodiment)

[0123] A reactor 1 according to a second embodiment will be described with reference to the drawings. Figure 6 This is an exploded perspective view showing the overall structure of the reactor of the second embodiment. In this embodiment, the yoke 22 is different from the first embodiment in that it includes two components. Figure 1 In addition, about the same structure and the same function as the first embodiment, the same code|symbol is attached|subjected, and detailed description is abbreviate|omitted.

[0124] The yoke 22 is disposed at both ends of the leg 21. The yoke 22 captures the magnetic flux generated by the leg and allows it to pass through. The yoke 22 includes two components. Specifically, it includes a first component 22a and a second component 22b. The end faces of the first component 22a and the second component 22b, which are perpendicular to the winding axis of the coil 3, have approximately the same shape. The end faces of the first component 22a and the second component 22b of the approximately identical shape are joined to form the yoke 22.

[0125] The first member 22a is provided on a side where the foot 21 is provided and is formed integrally with the foot 21. The first member 22a includes a composite magnetic material constituting the foot 21. That is, the foot 21 is formed integrally with a portion of the yoke 22. In this way, the first member 22a constituting the yoke 22 connects a pair of feet 21. The second member 22b includes a material different from the composite magnetic material. The second member 22b can use a pressed powder core, ferrite, or laminated steel plates. In this embodiment, the second member 22b uses a pressed powder core.

[0126] Figure 7 is an enlarged plan view of the core 2. Figure 7 As shown, the thickness L1 of the coil 3 of the first member in the winding direction is smaller than the thickness L2 of the second member 22b in the winding direction. Alternatively, the ratio of the thickness L1 of the coil of the first member 22a in the winding direction to the thickness L2 of the coil of the entire yoke 22 in the winding direction may be less than 0.5. In other words, the thickness of the coil of the first member 22a in the winding direction may be equal to or smaller than the thickness of the coil 3 of the second member 22b in the winding direction. If the ratio exceeds 0.5, the inductance at low current values becomes lower, and the current ripple during low current operation becomes larger. Therefore, if the ratio exceeds 0.5, there is a possibility that the iron loss of the reactor increases or the rotational action becomes unstable.

[0127] The first member 22a and the second member 22b are joined by the resin of the composite magnetic material of the first member 22a. Specifically, the clay-like resin of the composite magnetic material solidifies, thereby joining the first member 22a and the second member 22b. In other words, the first member 22a and the second member 22b are joined without the use of adhesives or other agents. The first member 22a and the second member 22b are seamlessly and continuously joined. The resin of the composite magnetic material constituting the first member 22a permeates the second member 22b.

[0128] The end surface of the second member 22b opposite to the first member is preferably flat. In this embodiment, the second member 22b is a block-shaped core. As described later, the second member 22b serves as an extrusion member for compressing the composite magnetic material. Therefore, by making the end surface of the second member 22b opposite to the first member 22a flat, the composite magnetic material can be extruded with uniform force.

[0129] In addition, there are a plurality of fine bumps on the end face of the second member 22b that is joined to the first member 22a. The size of the bumps is, for example, about tens of microns. The bumps may be bumps formed by powders such as magnetic powder when compacting a molded body such as a powdered magnetic core or ferrite, or may be bumps formed by roughening the surface of the molded body by using a file, sandblasting, etc. after molding. In addition, in the case of stacked steel plates, the bumps may be bumps formed by the step difference caused by stacking, or may be bumps formed on the surface of the molded body after stacking. The resin of the composite magnetic material enters the concave portion of the bumps.

[0130] The magnetic permeability of the second member 22b is preferably greater than that of the first member 22a and the leg 21. By making the magnetic permeability of the second member 22b greater than that of the first member 22a and the leg 21, more magnetic flux generated by the leg 21 around which the coil 3 is wound can be captured.

[0131] (Method for Manufacturing Reactor)

[0132] The manufacturing method of the reactor 1 of this embodiment will be described. In the manufacturing method of the reactor 1 of this embodiment, the (1) mounting process, (3) pressurizing process, and (4) curing process are basically the same as those of the first embodiment, so their descriptions are omitted. Only the different (2) filling process will be described.

[0133] (2) Filling process

[0134] The filling process is a process of filling the inside of the straight portion 41 with a composite magnetic material containing magnetic powder and resin. In this process, first, the magnetic powder and the resin are mixed to make a clay-like composite magnetic material. The clay-like composite magnetic material obtains the desired viscosity by the viscosity of the added resin. When mixed with the magnetic powder, the viscosity of the added resin is preferably 50mPa·s to 5000mPa·s. If the viscosity is less than 50mPa·s, the resin will not be entangled with the magnetic powder during mixing, and the magnetic powder and the resin will easily separate in the container, resulting in uneven density or strength of the core. If the viscosity exceeds 5000mPa·s, the viscosity will increase excessively, for example, the resin formed between the first magnetic powders will enter, and the second magnetic powder will not be able to fill the gap, etc., the density of the core will decrease, and the magnetic permeability will decrease.

[0135] The mixing can be performed automatically or manually using a prescribed mixer. The mixing time can be appropriately set and is not particularly limited thereto, for example, it can be set to 2 minutes. In this way, a clay-like composite magnetic material can be obtained by mixing the magnetic powder with the resin. A prescribed amount of the clay-like composite magnetic material is filled from the opening of the connecting portion 42 to the interior of the straight portion 41. At this time, the volume is filled to be larger than that of the straight portion 41 in order to also fill the connecting portion 42. The thickness of the coil 3 of the first component 22a in the winding axis direction is determined according to the amount of the composite magnetic material filled in the connecting portion 42. In this way, the foot 21 is formed integrally with the first component 22a.

[0136] (effect)

[0137] Next, the flow of magnetic flux will be described. When current flows through coil 3, magnetic flux is generated from coil 3. This generated magnetic flux flows through leg 21, which contains magnetic powder. The magnetic flux flowing through leg 21 passes through yoke 22 connected to leg 21, thereby forming a closed magnetic circuit within annular core 3.

[0138] For example, if the first member is absent, the magnetic flux will flow along the shortest distance, primarily toward the inner circumference of the annular core. Consequently, the core becomes magnetically saturated on the inner circumference of the annular core. When the core is magnetically saturated, the magnetic permeability becomes equal to that of air, becoming 1, causing some of the magnetic flux to leak toward the coil. This leaked magnetic flux passes through the coil, generating AC losses in the coil.

[0139] However, in this embodiment, the first member 22a is configured. Therefore, even if the second member 22b saturates and generates leakage magnetic flux, the first member 22a can serve as a path for the leakage magnetic flux, preventing the leakage magnetic flux from passing through the coil 3. In particular, the magnetic flux flows according to whichever has the greater magnetic permeability. In other words, by making the magnetic permeability of the second member 22b greater than that of the first member 22a, the second member 22b saturates first. Then, the leakage magnetic flux generated by the saturation of the second member 22b passes through the first member 22a, which is connected to the second member 22b. In this way, the first member serves to prevent the leakage magnetic flux generated by the second member 22b from passing through the coil 3 and causing AC loss in the coil 3.

[0140] In this embodiment, the first member 22a and the second member 22b are joined in the core 2. That is, the distance from the joint to the coil 3 is only a fraction of the thickness L1 of the first member 22a. Even if leakage flux is generated from the joint, the effect of the leakage flux on the coil 3 is suppressed due to the increased distance from the joint to the coil 3. Furthermore, the joint between the first member 22a and the second member 22b is seamlessly and continuously joined by a resin composite magnetic material. Therefore, the joint is seamlessly joined, thus suppressing the generation of leakage flux itself.

[0141] In addition, the magnetic permeability of the second member 22b is greater than that of the first member 22a. In other words, more magnetic flux flows through the second member 22b than through the first member 22a. In other words, less magnetic flux flows through the first member 22a, which is arranged near the coil 3. By reducing the magnetic flux flowing through the first member 22a, leakage magnetic flux from the first member 22a, which is arranged near the coil 3, can be suppressed. Furthermore, since the distance between the joint between the first member 22a and the second member 22b and the coil is increased, the impact on the coil 3 can be reduced.

[0142] (Effect)

[0143] As described above, the reactor 1 of this embodiment includes a core 2 having a plurality of legs 21 and a pair of yokes 22 disposed at both ends of the legs 21; and a coil 3 wound around the legs 21. The legs 21 are made of a composite magnetic material containing magnetic powder and resin. The yoke 22 includes a first member 22a made of the same composite magnetic material as the legs 21; and a second member 22b made of a material different from the composite magnetic material. The first member 22a is disposed on the side where the legs 21 are disposed and is integrally formed with the legs 21. The first member 22a is joined to the second member 22b. The magnetic permeability of the second member 22b is greater than that of the legs 21 and the first member 22a.

[0144] As a result, more magnetic flux flows through the second member 22b, causing it to reach magnetic saturation before the first member 22a. The leakage flux generated by the magnetic saturation of the second member 22b then passes through the first member 22a, preventing the leakage flux from passing through the coil. This suppresses the effects of leakage flux on the coil 3 and reduces the AC losses of the reactor 1. Furthermore, the coil 3 and the junction between the first and second members 22a, 22b can be separated without increasing the length of the coil 3 in the winding direction of the leg 21, thereby maintaining compactness.

[0145] The coil 3 is wound around the leg 21, and the ratio of the thickness L1 of the coil 3 in the winding direction of the first member 22a to the thickness L2 of the coil 3 in the winding direction of the entire yoke 22 is 0.5 or less. This reduces AC loss while maintaining the initial inductance value (L value).

[0146] The second member 22b has a higher magnetic permeability than the leg 21 and the first member 22a. Consequently, magnetic flux flows more easily through the second member 22b than through the first member 22a, leading to a greater flow of magnetic flux through the second member 22b. This reduces the amount of magnetic flux flowing through the first member 22a, which is located on the side where the coil 3 is located. This prevents magnetic flux from saturating in the first member 22a. Consequently, leakage flux from the first member 22a can be suppressed, reducing AC losses in the reactor 1.

[0147] Furthermore, the distance between the junction of the first member 22a and the second member 22b and the coil 3 is increased. Therefore, even if leakage magnetic flux occurs from the junction, the effect on the coil 3 can be reduced, thereby reducing the AC loss of the reactor 1.

[0148] In the yoke 22, the first member 22a and the second member 22b are joined by the resin of the composite magnetic material of the first member 22a. In other words, the first member 22a and the second member 22b are seamlessly and continuously joined. This allows the first member 22a and the second member 22b to be joined without a gap, thereby suppressing magnetic flux leakage from the joint and reducing AC losses in the reactor 1.

[0149] (Variation 2)

[0150] The reactor of Modification 2 will be described with reference to the accompanying drawings. Figure 4 same. Figure 8 : is an exploded perspective view showing the overall structure of the reactor of Modification Example 2. Figure 4 、 Figure 8 As shown, in the second embodiment, the coil 3 is wound around all the legs, but in the second modification, there is a leg 21 around which the coil 3 is not wound.

[0151] Specifically, it has three legs 21. These legs 21 are arranged parallel to the winding axis of coil 3. Of these three parallel legs 21, the center leg 23, around which coil 3 is wound, is located. On either side of center leg 23 are outer legs 24, around which no coil 3 is wound. Center leg 23 and the two outer legs 24 are MC cores made of composite magnetic material.

[0152] The first member 22a is integrally formed with the center leg 23 and the two outer legs 24. The second member 22b is joined to the first member 22a by the resin of the composite magnetic material of the first member 22a. That is, the first member 22a and the second member 22b are seamlessly and continuously joined.

[0153] As described above, in Modification 2, there are three legs 21, one more than in the second embodiment, including a center leg 23 and two outer legs 24. Increasing the number of legs 21 increases the number of joints between the legs 21 and the yoke 22, potentially generating more leakage flux.

[0154] However, in this modified example, the center leg 23, outer leg 24, and first member 22a are integrally formed from a composite magnetic material. The first member 22a and second member 22b are then joined together using the composite magnetic resin. In other words, the junction between the first and second members 22a, made of different materials, and the coil 3 are separated. This reduces the effect of leakage flux from the junction on the coil 3. In this way, as the number of legs 21 increases, and thus the number of junctions between the legs 21 and the yoke 22 increases, the AC losses of the reactor 1 can be further significantly reduced.

[0155] (Third embodiment)

[0156] A reactor 1 according to a third embodiment will be described with reference to the drawings. Figure 9 is a perspective view showing the overall structure of a reactor 1 according to a third embodiment. Figure 10 It is an exploded perspective view showing the overall structure of a reactor 1 according to the third embodiment.

[0157] (Overview of the structure)

[0158] The reactor 1 is an electromagnetic component that converts electrical energy into magnetic energy and stores and releases it, and is used for voltage step-up and step-down. Figure 9 、 Figure 10 As shown, the reactor 1 of this embodiment includes a core 2, a coil 3, and a resin member 4. The core 2 has two legs 21: a center leg 21A and an outer leg 21B, and a pair of yokes 22 disposed at either end of the legs 21. The core 2 is covered with the resin member 4, and the coil 3 is mounted so as to be sandwiched between the center leg 21A and the outer leg 21B of the core 2, while the core 2 and the coil 3 are insulated by the resin member 4.

[0159] like Figure 10 As shown, the foot portion 21 includes a middle foot 21A and an outer foot 21B disposed on the outside (lower side in the figure) of the middle foot 21A. The middle foot 21A and the outer foot 21B are arranged in a manner such that the central axes are parallel to each other. Figure 10 They are arranged facing each other in the up and down directions. Figure 11 As shown, the middle leg 21A is arranged on the upper side, and the outer leg 21B is arranged on the lower side. The leg 21 is covered with a resin member 4. The leg 21 is a metal composite core (MC core) made of a composite magnetic material containing magnetic powder and resin.

[0160] The middle leg 21A includes a cylindrical member having a circular or elliptical cross section, but is not limited thereto. When the cross section of the middle leg 21A is an ellipse, the diameter of the ellipse is set to be a diameter perpendicular to the arrangement direction of the middle leg 21A and the outer leg 21B arranged in parallel. Figure 10 As shown, when middle leg 21A and outer leg 21B are arranged facing each other in the vertical direction, the diameter of the ellipse of middle leg 21A is set to a diameter extending in the horizontal direction. Coil 3 is wound around middle leg 21A via resin member 4. In reactor 1, middle leg 21A, where coil 3 is wound, serves as the location where magnetic flux is generated. Outer leg 21B is composed of a member having a width greater than the diameter of middle leg 21A and less than the diameter of the outer periphery of coil 3.

[0161] The end surface of the outer leg 21B opposite to the middle leg 21A ( Figure 10 The upper surface side in the figure) becomes a curved surface that is concave toward the lower side of the figure, and the surface on the opposite side ( Figure 10 When the reactor 1 is placed horizontally, the flat surface side of the outer leg 21B becomes the installation surface of the reactor 1. In addition, when the reactor 1 is placed vertically, the end surface facing the outside of the yoke 22 becomes the installation surface of the reactor 1.

[0162] Figure 11 FIG. 4 is a side sectional view in which the resin member 4 is omitted in the third embodiment. Figure 11 As shown, coil 3 is mounted on center leg 21A of core 2. An opening 29 (shown by a dotted line) is formed to expose coil 3 from outer leg 21B of core 2. The aperture ratio of opening 29 is defined as 0% when the entire circumference of coil 3 is contained within core 2 and 100% when the entire circumference of coil 3 is exposed from core 2. In this embodiment, the aperture ratio of opening 29 is set to over 60%, and more preferably, to over 67%.

[0163] like Figure 9 、 Figure 10 As shown, yokes 22 are disposed at both ends of legs 21. Yokes 22 capture the magnetic flux generated by legs 21 and pass it through. Yokes 22 are disposed so that their vertical direction is perpendicular to the longitudinal direction of legs 21. The outward end surfaces of yokes 22 are exposed and not covered by resin member 4, while the outer peripheral surface of yokes 22 is covered by resin member 4.

[0164] like Figure 10 As shown, the yoke 22 includes two components. Specifically, it includes a first component 22a and a second component 22b. The end faces of the first component 22a and the second component 22b, which are perpendicular to the winding axis of the coil 3, have approximately the same shape. The end faces of the first component 22a and the second component 22b of these approximately identical shapes are joined to form the yoke 22.

[0165] The first member 22a is provided on a side where the leg 21 is provided, and is formed integrally with the leg 21. The first member 22a includes a composite magnetic material constituting the leg 21. That is, the core 2 of the present embodiment is a block-shaped core in which the leg 21 and a part of the yoke 22 are formed integrally. In this way, the first member 22a constituting the yoke 22 connects a pair of legs 21, namely the middle leg 21A and the outer leg 21B. The second member 22b includes a material different from the composite magnetic material. As the second member 22b, a pressed powder core, ferrite, or laminated steel plates can be used. In the present embodiment, the second member 22b uses a pressed powder core and ferrite.

[0166] The yoke 22 includes a roughly hexagonal component that combines the following parts: a semicircular portion that is connected to the diameter portion of the center leg 21A; a trapezoidal portion that uses the diameter portion of the center leg 21A as a short side; and a rectangular portion that is connected to the trapezoidal portion with a long side opposite to the short side. The diameter of the semicircular portion on the upper side of the yoke 22 is the same as the diameter of the center leg 21A. The yoke 22 is joined to the end face of the leg 21 that is orthogonal to the winding direction of the coil 3. As described above, in the core 2, the yoke 22 (the first component 22a) is connected to the center leg 21A and the outer leg 21B, but at this time, the semicircular portion of the yoke 22 is consistent with the circumference of the center leg 21A, and the rectangular portion of the yoke 22 is consistent with the cross-section of the outer leg 21B.

[0167] (Function and Effect)

[0168] The functions and effects of the third embodiment are as follows.

[0169] (1) A reactor 1 according to the third embodiment includes a core 2 having a center leg 21A around which a coil 3 is wound, an outer leg 21B disposed outside the center leg 21A, and yokes 22 disposed at both ends of the center leg 21A and the outer legs 21B. The core 2 is made of a composite resin material containing magnetic powder and resin, and has an opening 29 formed therein for exposing the coil 3 from the core 2. When the entire circumference of the coil 3 is contained within the core 2, the opening ratio is 0%, and when the entire circumference of the coil 3 is exposed from the core 2, the opening ratio is 100%. In this case, the opening ratio of the opening 29 is set to 67%. In the third embodiment, since the core 2 is made of a composite resin material containing magnetic powder and resin, the shape of the core 2 can be easily formed to increase the opening ratio of the opening 29.

[0170] According to the third embodiment described above, by setting the opening ratio of opening 29 of core 2 to 67%, the area of coil 3 exposed from core 2 when coil 3 is mounted on core 2 increases. Consequently, heat from coil 3 is less likely to accumulate within core 2 and is readily dissipated into the air. Consequently, reactor 1 can exhibit excellent heat dissipation. Here, the temperatures of coil 3 in Example 1, which applies this embodiment, and Comparative Examples 1 to 3 are compared.

[0171] As shown in Table 1, the materials of the cores of Comparative Examples 1 to 3 and Example 1 are as follows. The legs are all made of MC cores (Fe-Si alloy). The yokes of Comparative Examples 1 and 2 use magnetic powder cores (Fe-Si-Al alloy), while those of Comparative Example 3 and Example 1 use ferrite (Mn-Zn). In other words, the cores 2 of Comparative Example 3 and Example 1 are made of the same type and material. The opening ratios of the openings 29 of the cores 2 of Comparative Examples 1, 2, 3, and Example 1 are 50%, 60%, 60%, and 67%, respectively.

[0172] [Table 1]

[0173]

[0174] For example, the heat of coil 3 in Comparative Examples 1 to 3 and Example 1 was measured, with the current applied at 27A and the frequency at 20kHz, and the cooling condition set to natural cooling without forced cooling. In this case, the temperatures of coil 3 in Comparative Examples 1 to 3 were 85.9°C, 76.9°C, and 68.7°C, respectively. In contrast, the temperature of coil 3 in Example 1, which applied the third embodiment, was 58.9°C. Specifically, while Comparative Example 3 and Example 1 had the same core 2 type and material, differing only in the aperture ratio of opening 29 of core 2, Example 1, in which the aperture ratio of opening 29 was increased to 67%, reduced the temperature of coil 3 by 9.8°C compared to Comparative Example 3.

[0175] (2) In the third embodiment, the first member 22a of the yoke 22 is integrally formed with the leg 21, and the composite resin material of the first member 22a and the composite resin materials of the middle leg 21A and the outer leg 21B serve as the adhesive that connects the yoke 22 to the leg 21. In other words, the leg 21 and the yoke 22 are joined by a composite magnetic material. In other words, the composite magnetic material replaces an adhesive, etc., eliminating the need for an adhesive, etc., to join the leg 21 and the yoke 22. Therefore, the process of joining the leg 21 and the yoke 22 using an adhesive, etc. can be reduced, and the cost of not using an adhesive, etc. can be reduced.

[0176] (3) The yoke 22 of the third embodiment includes: a first member 22a comprising the composite magnetic material constituting the leg 21; and a second member 22b comprising a material having a higher magnetic permeability than the composite magnetic material, such as a powdered magnetic core. That is, in the yoke 22, the second member 22b has a higher magnetic permeability than the leg 21 and the first member 22a. Therefore, magnetic flux flows more easily through the second member 22b than through the first member 22a, and more magnetic flux flows through the second member 22b. Therefore, the magnetic flux flowing through the first member 22a, which is provided on the side where the coil 3 is arranged, can be reduced. Therefore, saturation of the magnetic flux in the first member 22a is suppressed. As a result, leakage magnetic flux generated from the first member 22a can be suppressed, thereby reducing the AC loss generated in the coil 3. Thus, heat generation in the coil 3 can be suppressed in accordance with the heat dissipation by the opening 29 having a high aperture ratio.

[0177] (4) When the core 2 is entirely composed of block cores, the inductance characteristics are good, but the gap becomes larger, which may lead to worsening losses. On the other hand, if the core 2 is entirely composed of MC cores, the gap becomes smaller, but the core magnetic permeability becomes lower, which may deteriorate the inductance characteristics.

[0178] In contrast, in the core 2 of the third embodiment, the leg portion 21 is an MC core made of a composite magnetic material, and the yoke 22 is a block-shaped core including the second member 22b, which is a powder core. Therefore, good inductance characteristics can be achieved while achieving a gapless structure.

[0179] (5) In the third embodiment, the core 2 includes a center leg 21A and an outer leg 21B. The center leg 21A has a circular or elliptical cross-sectional shape, and the outer leg 21B is larger than the diameter of the center leg 21A and has a width dimension that is less than or equal to the diameter of the outer periphery of the coil 3. In such a core 2, by making the width dimension of the outer leg 21B larger than the diameter of the center leg 21A, the thickness dimension (the dimension in the vertical direction orthogonal to the width dimension) of the outer leg 21B can be suppressed while ensuring the cross-sectional area of the yoke.

[0180] This contributes to the miniaturization of core 2 in terms of the thickness of outer leg 21B. Furthermore, in core 2, by setting the width of outer leg 21B to be less than the diameter of the outer periphery of coil 3, core 2 can be confined to the projected area of coil 3 (the area when coil 3 is viewed from directly above), thereby preventing the core 2 from becoming too large. Furthermore, outer leg 21B is larger than the diameter of center leg 21A and has a width dimension less than the diameter of the outer periphery of coil 3. This ensures that the installation area is sufficient when outer leg 21B is placed on a mounting surface.

[0181] (6) In the third embodiment, the substantially hexagonal yoke 22 is expanded outward from the diameter portion of the center leg 21A, and the outer leg 21B is aligned with the bottom portion of the yoke 22 (the portion including the lower long side of the horizontally long rectangle). Therefore, the cross-sectional area of the yoke 22 can be sufficiently ensured while maintaining the compactness of the core 2, thereby achieving excellent inductance characteristics.

[0182] That is, in this embodiment, if Figure 12 As shown, the core 2 can be formed by effectively utilizing the dead space 5 (parts surrounded by dotted lines) on both sides of the core 2 when the coil 3 protrudes horizontally from the core 2. This can achieve both miniaturization of the core 2 and improvement of the inductance value.

[0183] Furthermore, in the roughly hexagonal yoke 22, the areas near the diameter of the center leg 21A and near the trapezoidal corners are difficult for magnetic flux to pass through. Therefore, even if the yoke 22 is rectangular, cutting out the areas near the trapezoidal corners will have little effect on the inductance. Therefore, in this embodiment, even if the yoke 22 is roughly hexagonal to reduce its cross-sectional area, there is no need to worry about a decrease in inductance. As a result, the advantage of reducing the weight of the yoke 22 can be achieved while maintaining excellent inductance characteristics.

[0184] (Fourth embodiment)

[0185] Reference Figures 13 to 20 A reactor 1 according to a fourth embodiment will be described. Figure 13 is a perspective view showing the overall structure of a reactor 1 according to a fourth embodiment. Figure 14 1 is an exploded perspective view showing the overall structure of the reactor 1 according to the fourth embodiment. Figure 13 、 Figure 14 As shown, the core 2 of the fourth embodiment is also similar to the third embodiment. The leg portion 21 is an MC core made of a composite magnetic material, and the yoke portion 25 is a block-shaped core including a second member 22 b as a ferrite core.

[0186] The yoke 25 of the fourth embodiment is similar to the yoke 22 and is disposed at both ends of the leg 21, but its cross-sectional shape is unique. While the yoke 22 of the third embodiment was generally hexagonal, the yoke 25 of the fourth embodiment extends the generally hexagonal shape in a vertically elongated manner, with the straight line portions removed.

[0187] Before explaining the shape of the yoke 25, the leg 21 will be explained. Figure 14 As shown, similarly to the third embodiment, the middle leg 21A includes a cylindrical member having a circular cross section. The end surface ( Figure 14 The upper surface side in the figure) becomes a curved surface that is concave toward the lower side of the figure, and the surface on the opposite side ( Figure 14 When the reactor 1 is placed horizontally, the flat surface side of the outer leg 21B becomes the installation surface of the reactor 1.

[0188] like Figure 15 As shown, in the fourth embodiment, similar to the third embodiment, when the coil 3 is mounted on the core 2, an opening 29 (shown by a dotted line) is formed in the reactor 1 for exposing the coil 3 from the core 2. In the fourth embodiment, the opening ratio of the opening 29 is also set to 67%.

[0189] Then, use Figures 16 to 20 The shape of the yoke 25 will be described in detail. Figure 16 As shown, the yoke 25 is formed by placing the middle leg 21A side (at Figure 16 The corners (upper side in the center) are cut into a roughly triangular shape. In the yoke 25, when the width dimension of the yoke 25 is set to 46.0 mm and the height dimension is set to 41.7 mm, the width dimension A is set to 10 mm and the height dimension B is set to 30 mm, and the area of the triangle enclosed by A×B (the portion enclosed by the dotted line) is removed. The ratio of the width dimension A to the width dimension of the yoke 25 is 10 / 46 = 21.7%, and the ratio of the height dimension B to the height dimension of the yoke 25 is 30 / 41.7 = 71.9%.

[0190] In addition, if Figure 17 As shown, the yoke 25 includes an extension portion 25a extending outward from the outer diameter of the center leg 21A. When the outer radius of the center leg 21A is set to 28 mm, the length of the extension portion 25a extending outward is within a range of 3 mm to 5 mm. The ratio of the length of the extension portion 25a to the outer radius of the center leg 21A is within a range of 3 / 28 × 100 = 10.7% to 5 / 28 × 100 = 17.6%.

[0191] Furthermore, if Figure 18 As shown, in the yoke 25, the corner portion on the side of the outer leg 21B is set to an R shape. The R-shaped portion of the yoke 25 at the corner portion on the side of the outer leg 21B includes a chamfered portion 25b. In the chamfered portion 25b, R is set to be less than 7 (mm). The chamfered portion 25b is provided by chamfering the ferrite constituting the second member 22b. In addition, the bottom portion of the yoke 25 (the lower surface portion in the figure) is consistent with the shape of the outer leg 21B. Therefore, according to the R shape of the chamfered portion 25b of the yoke 25, the corner portion of the outer leg 21B is also set to an R shape (refer to Figure 14 and Figure 15 ).

[0192] In addition, if Figure 19 and Figure 20 As shown, the corners of the yoke 25 facing the end face of the coil 3 are also R-shaped. The R-shaped portion of the yoke 25 at the corners facing the end face of the coil 3 includes a chamfer 25c. The R value of the chamfer 25c is set to be less than 6 mm. Similar to the chamfer 25b, the chamfer 25c is also provided by chamfering the ferrite constituting the second member 22b.

[0193] (Function and Effect)

[0194] In the fourth embodiment, as in the third embodiment, the opening ratio of opening 29 of core 2 is set to 67%. This increases the area of coil 3 exposed from core 2 when coil 3 is mounted on core 2. Consequently, heat from coil 3 is less likely to accumulate within core 2, allowing it to dissipate easily into the air. Consequently, reactor 1 exhibits excellent heat dissipation. In addition to these functions and effects, the fourth embodiment also exhibits functions and effects derived from the shape of yoke 25.

[0195] (1) The applicants investigated the inductance reduction rate of the reactor by setting the width A and height B to the same value when removing the corner portion on the center leg 21A side of the yoke 25. First, the width A and height B were set to 5 mm. Subsequently, the inductance reduction rate (%) was investigated by varying the values in 1 mm increments within a range of 10 mm to 17 mm (see Table 2).

[0196] [Table 2]

[0197]

[0198] As a result, the inductance reduction rate (%) is 1% at 5mm, 11mm, and 12mm, and increases to over 2% at 13mm and above. In contrast, at 10mm, it is 0%, indicating no reduction in inductance. When the reduction in width A is increased, the cross-sectional area of center leg 21A must be reduced by a smaller amount than the reduction in height B. Therefore, height B, which has a relatively larger reduction, is reduced.

[0199] Therefore, the applicant fixed width A at 10 mm, which has no effect on inductance, and varied only height B to investigate the inductance reduction rate. The results are shown in Table 3. As Table 3 clearly shows, even when height B is reduced to 30 mm, the inductance reduction rate remains at 1%, demonstrating minimal impact on inductance characteristics. Furthermore, given the yoke 25 height of 41.7 mm, increasing height B to 30 mm or greater would presumably make it difficult to maintain the width of the outer leg 21B.

[0200] [Table 3]

[0201]

[0202] Based on the above, in the reactor 1 of the fourth embodiment, the inductance reduction rate can be reduced by reducing the width dimension A by 10 mm and the height dimension B by 30 mm from the roughly triangular dimensions removed from the yoke 25. This can suppress the impact on the inductance characteristics. Furthermore, by removing a portion of the yoke 25, the volume of the core 2 can be reduced, thereby achieving a lighter reactor 1.

[0203] (2) In the fourth embodiment, the yoke 25 is provided with an extension portion 25a extending from the outer diameter of the center leg 21A relative to the outer diameter of the core 2. However, the inductance reduction rate changes when the length of the extension portion 25a is changed as shown below (see Table 4). Specifically, when the outer diameter of the core 2 is set to 28 mm and the length of the extension portion 25a is set to 1 mm, 2 mm, and 2.5 mm, the inductance reduction rate is 11%, 8%, and 4%, respectively.

[0204] [Table 4]

[0205]

[0206] Furthermore, when the length of the extension 25a is set to 3 mm, 3.5 mm, 4 mm, and 5 mm, the inductance reduction rate is 1%, 1%, 2%, and 1%, respectively. In other words, when the length of the extension 25a is between 3 mm and 5 mm, the inductance reduction rate can be suppressed to below 2%. Therefore, in the fourth embodiment, even if the yoke 25 is removed, the effect of the extension 25a on the inductance characteristics can be suppressed by providing it.

[0207] (3) In the fourth embodiment, not only the corners on the outer leg 21B side of the yoke 25 are cut off, but also the corners on the outer leg 21B side are cut off, forming an R-shaped chamfered portion 25b. If the corners on the outer leg 21B side of the yoke 25 are cut off, the outer leg 21B itself must also be cut off accordingly, which significantly affects the inductance value. However, in the fourth embodiment, by setting the R of the chamfered portion 25b to 7 mm or less, the rate of reduction in inductance can be suppressed.

[0208] [Table 5]

[0209]

[0210] Table 5 shows the variation in the inductance reduction rate when the R of the chamfered portion 25b is varied. Specifically, when the R of the chamfered portion 25b is 2mm, 4mm, 6mm, and 7mm, the inductance reduction rate is 2.9%, 2.5%, 2.5%, and 1.9%, respectively. On the other hand, when the R exceeds 7mm and reaches 8mm or 10mm, the inductance reduction rate drops to 3.4%, and when the R reaches 15mm, the inductance reduction rate reaches 3.8%.

[0211] If the inductance reduction rate is within 3%, the inductance characteristics can be fully satisfied. Therefore, in the fourth embodiment, by setting the R of the corner portion on the outer leg 21B side of the yoke 25 to 7 mm or less, the inductance reduction rate can be suppressed to within 3%. As a result, in the fourth embodiment, while maintaining good inductance characteristics, the weight can be reduced by reducing the core 2.

[0212] (4) Furthermore, in the yoke 25 of the fourth embodiment, an R-shaped chamfered portion 25c is provided at the corner of the portion facing the end face of the coil 3. Therefore, the coil 3 is exposed from the core 2, and the aperture ratio of the opening 29 can be ensured. The variation in the inductance reduction rate depending on the size of the R of the chamfered portion 25c of the yoke 25 is shown in Table 6 below.

[0213] [Table 6]

[0214]

[0215] When the R of the chamfered portion 25c is 6mm, the inductance reduction rate is the lowest, at 1.3%. For R = 1mm, 2mm, 3mm, 4mm, and 5mm, the inductance reduction rates are 1.7%, 2.1%, 2.1%, 1.7%, and 2.1%, respectively. Meanwhile, when R = 7mm, the inductance reduction rate reaches 3.5%, and when R = 10mm, the inductance reduction rate reaches 5.0%.

[0216] As described above, if the inductance reduction rate is a change in the inductance value within 3%, the inductance characteristics can be fully satisfied. Therefore, in the fourth embodiment, by setting the R of the chamfered portion 25c to be less than 6mm, the inductance reduction rate can be suppressed to within 3%, while taking into account both the maintenance of the inductance characteristics and the reduction of the core 2.

[0217] (Fifth embodiment)

[0218] Reference Figure 21 、 Figure 22 A reactor 1 according to a fifth embodiment will be described. Figure 21 is a perspective view showing the overall structure of a reactor 1 according to a fifth embodiment. Figure 22 1 is an exploded perspective view showing the overall structure of the reactor 1 according to the fifth embodiment. Figure 21 、 Figure 22 As shown, similarly to the third embodiment, in the core 2 of the fifth embodiment, the leg portion 21 is also an MC core made of a composite magnetic material, and is a block-shaped core including a second member 22b that is a ferrite core in the yoke portion 27a.

[0219] like Figure 22As shown, the fifth embodiment includes an X-shaped core 2, centered around a cylindrical center leg 21A and surrounded by four outer legs 21C. The four outer legs 21C are all of the same shape and are evenly spaced. In the X-shaped core 2, magnetic flux concentrates and flows through the yoke 27a connecting the center leg 21A and the four outer legs 21C. Therefore, magnetic flux is less likely to flow through the reduced portion, and even if this is reduced, it will not significantly affect the characteristics. In other words, the core 2 forms an X-shape by reducing the portion where magnetic flux is less likely to flow.

[0220] The surface of the outer leg 21C facing the middle leg 21A is a concave curved surface, and the other surfaces are flat surfaces that are perpendicular to each other. When the reactor 1 is placed horizontally, the flat surface side of the outer leg 21C becomes the installation surface of the reactor 1. Figure 21 The middle figure shows a case where the reactor 1 is placed vertically. In this case, the end surface of the yoke 27 a facing outward serves as the installation surface of the reactor 1 .

[0221] The yoke 27a of the fifth embodiment is similar to the yokes 22 and 25, and is located at both ends of the leg 21. However, the yoke 27a includes an X-shaped core member. In the X-shaped yoke 27a, the intersecting sides are formed to be orthogonal to each other. Furthermore, outer legs 21C are located at the front ends of each side of the X-shaped yoke 27a. Therefore, the front ends of each side of the yoke 27a are formed at right angles, corresponding to the flat surfaces of the outer legs 21C.

[0222] like Figure 21 As shown, when the coil 3 is mounted on the core 2, an opening 26 is formed in the reactor 1 for exposing the coil 3 from the core 2. The opening 26 is arranged between the four outer legs 21C. That is, the opening 26 is provided at four locations, and the total opening ratio of the four locations is set to 67%. Figure 21 As viewed from above, the opening 26 has a right-angled corner near the center of the coil 3 and is formed to expand in a fan shape from the corner.

[0223] (Function and Effect)

[0224] (1) In the fifth embodiment, the opening ratio can be increased by forming the core 2 in an X-shape. In the fifth embodiment, the heat dissipation is improved by providing the opening 26 with a width of 67%. For example, as Example 2 applying the fifth embodiment, the core 2 was manufactured using the leg 21 of the MC core (Fe-Si alloy) and the yoke 27a of ferrite (Mn-Zn system), and the heat dissipation of the coil 3 of Example 2 was measured. The energizing conditions were set to a current of 27A and a frequency of 20kHz, and the cooling conditions were set to natural cooling (see Table 7).

[0225] [Table 7]

[0226]

[0227] As a result, the temperature of coil 3 reached 57.8°C, 1.1°C lower than the temperature of the coil in Example 1, which applied the third embodiment. This is believed to be because, in the fifth embodiment, the openings 26 are divided into four sections, allowing for uniform heat dissipation throughout the entire circumference of coil 3. The fifth embodiment, as described above, achieves a higher heat dissipation effect.

[0228] (2) In the fifth embodiment, the flat surfaces of the outer legs 21C are perpendicular to each other, and therefore, when the reactor 11 is placed horizontally, the stability is high.

[0229] (Variation 3)

[0230] A third modification of the core 2 of the fifth embodiment has the following configuration. Figure 23 、 Figure 24 In the X-shaped yoke 27b shown in FIG. 1 , the front end portion of the cross side portion is set to be sharp. Figure 21 In the opening 26 shown, a right angle is formed near the center of the coil 3, and Figure 23 、 Figure 24 The opening 28 shown forms an acute-angled corner near the center of the coil 3 .

[0231] In addition, Figure 25 、 Figure 26 The X-shaped yoke 27c shown has a circular portion in the center corresponding to the shape of the middle leg 21A, and side portions are provided extending in all directions from the circular portion. Figure 26 As shown in FIG. 1 , the front end of each side of the yoke 27c is in a substantially trapezoidal shape. Therefore, the cross-sections of the four outer legs 21D that are consistent with the outer shape of the yoke 27c are all in a substantially hexagonal shape. Figure 23 、 Figure 24 In the opening 28 shown, an acute angle is formed near the center of the coil 3. Figure 25 、 Figure 26 The opening 30 shown forms an obtuse-angled corner near the center of the coil 3 .

[0232] In the third modification of the fifth embodiment described above, the desired aperture ratio can be achieved by changing the corners of openings 28 and 30 near the center of coil 3. This ensures inductance characteristics as required by the user while achieving excellent heat dissipation.

[0233] [Example 3]

[0234] The examples of the present invention are described with reference to Table 8. In Example 3, three core samples of Example 3 and Comparative Example 4 were produced under the same conditions, and the shear strength of each sample was measured. The samples of Example 3 and Comparative Example 4 were produced as follows. The difference between Example 3 and Comparative Example 4 lies in that Example 3 uses a composite magnetic material resin to bond the powder magnetic core and the MC core containing the composite magnetic material, while Comparative Example 4 produces a molded MC core and bonds the powder magnetic core and MC core using an adhesive. Furthermore, the three samples of Example 3 and Comparative Example 4 are identical.

[0235] (Sample Preparation Method of Example 3)

[0236] In the method for preparing the sample of Example 3, first, a frame filled with a composite magnetic material is arranged on the formed powder magnetic core (NPS series of POCO). Then, a clay-like composite magnetic material is filled in the frame. The composite magnetic material is made by adding 4wt% of epoxy resin to Fe-6.5% Si as a magnetic powder. The filled composite magnetic material is pressed at 400N toward the powder magnetic core. Thereafter, the resin is cured by heating at a temperature of 150°C in the atmosphere for 8 hours to bond it to the powder magnetic core. In this way, in the sample of Example 3, the powder magnetic core and the MC core are bonded by the resin of the composite magnetic material.

[0237] (Preparation Method of Sample of Comparative Example 4)

[0238] In the method for preparing the sample of Comparative Example 4, first, a molded body of a powder core and an MC core is prepared. The molded body of the powder core is the same as that of Example 3. The molded body of the MC core is produced as described below. The magnetic powder of the composite magnetic material, the type of resin, and the amount of resin added are the same as those of Example 3. First, a clay-like composite magnetic material is filled in a predetermined container and heated in the atmosphere at 150°C for 8 hours to solidify the resin, thereby obtaining a molded body of the MC core. Then, the powder core and the MC core are bonded using an adhesive. Epoxy resin is used as the adhesive, and it is heated at 120°C for 1 hour to solidify.

[0239] The shear strength of the samples of Example 3 and Comparative Example 4 was measured at 5 mm / min using the following apparatus. The measurement results are shown in Table 8.

[0240] Company Name: Nippon Measurement Systems Co., Ltd.

[0241] Device Name: MAX-20

[0242] [Table 8]

[0243]

[0244] As shown in Table 8, the results show that all samples 1 to 3 of Example 3 had higher shear strength than sample 3 of Comparative Example 4, which had the highest shear strength. Furthermore, in samples 1 to 3 of Comparative Example 4, cohesive failure of the adhesive occurred. That is, the adhesive was sheared off at the junction between the leg and the yoke. On the other hand, in samples 1 to 3 of Example 3, the powder core of yoke 22 experienced base material failure. That is, the adhesive was not sheared off at the junction between yoke 22 and leg 21.

[0245] This is believed to be because, when bonding with an adhesive, as in Comparative Example 4, gaps form at the joint, causing the adhesive to undergo cohesive failure. On the other hand, Example 3 does not use an adhesive, but instead uses the resin of the composite magnetic material that constitutes the MC core for bonding, resulting in a gapless bond. In other words, the dust core and MC core are more tightly bonded than when bonded with an adhesive. Therefore, it is believed that in Example 3, gapless bonding improves the strength of the joint, leading to base material failure of the dust core rather than severing the joint.

[0246] As described above, in Example 3, the leg portion 21 and the yoke portion 22 are joined by the resin of the MC core, thereby making it possible to firmly join the leg portion 21 and the yoke portion 22 without generating a gap. Therefore, leakage magnetic flux generated by the gap can be suppressed.

[0247] (Example 4)

[0248] Refer to Table 9, Table 10 and Figure 27 Example 4 of the present invention will be described. In Example 4, reactors of Example 4, Comparative Examples 5, and 6 were fabricated, and their losses and inductance (L values) were measured. The reactors of Example 4, Comparative Examples 5, and 6 differed only in the core material and bonding method; the core cross-sectional area, number of coil turns, and reactor size were the same.

[0249] In the core 2 of Example 4, an MC core (magnetic permeability μ30) was used for the leg 21, and a powder core (magnetic permeability μ147) was used for the yoke 22. The leg 21 and yoke 22 were bonded together using the MC core's resin. In Comparative Example 5, a powder core (magnetic permeability μ60) was used for the leg, and a powder core (magnetic permeability μ147) was used for the yoke. The leg and yoke were bonded together using an adhesive. In Comparative Example 6, an MC core (magnetic permeability μ30) was used for the leg, and an MC core (magnetic permeability μ30) was used for the yoke. The leg and yoke were bonded together using an adhesive. In Comparative Examples 5 and 6, which were bonded using adhesive, four gaps with an adhesive film thickness of 50 μm were present.

[0250] The results of the loss and inductance values of the reactors of Example 4, Comparative Example 5, and Comparative Example 6 are shown in Tables 9 and 10. Figure 27 .

[0251] [Table 9]

[0252]

[0253] [Table 10]

[0254]

[0255] As shown in Table 9, the iron loss and copper loss of Example 4 are also values that do not change much compared with the values of Comparative Examples 5 and 6. That is, Example 4 has the same low loss characteristics as Comparative Examples 5 and 6. Figure 27 As shown, the inductance values of Example 4 do not differ significantly from those of Comparative Examples 5 and 6. In particular, for inductance values of 30A to 40A, there is almost no difference between Example 4 and Comparative Examples 5 and 6, indicating that the DC superposition characteristics of the reactor of Example 4 are good.

[0256] As shown in Examples 3 and 4 above, the present invention achieves gapless bonding between the leg 21 and yoke 22 by joining them with a composite magnetic resin, thereby suppressing the generation of magnetic leakage flux. Furthermore, even when the leg 21 and yoke 22 are joined with a composite magnetic resin, as in the present invention, excellent loss characteristics and DC superposition characteristics are maintained. In other words, the present invention can suppress the generation of magnetic leakage flux while maintaining excellent loss characteristics and DC superposition characteristics.

[0257] (Example 5)

[0258] Refer to Table 11. Figure 28 、 Figure 29 Example 5 will be described. In this example, the overall thickness L2 of the yoke 22 was set to 14.0 mm, and the thickness L1 of the first member 22a of the yoke 22 was changed to measure the inductance value (L value) and AC loss. In this example, the first member 22a was made of the same composite magnetic material (magnetic permeability μ30) as the leg 21, and the second member 22b was made of a Fe-Si-Al powder core (magnetic permeability μ147). The measurement results are shown in Tables 11 and 12. Figure 28 、 Figure 29 .

[0259] [Table 11]

[0260]

[0261] As shown in Table 11 and Figure 28As shown in the figure, it can be seen that the greater the thickness L1 of the first member 22a, the lower the AC loss. This is because the greater the thickness L1 of the first member 22a, the greater the distance between the junction of the first member 22a and the second member 22b and the coil 3. This reduces the effect of leakage magnetic flux on the coil, thereby reducing the AC loss.

[0262] On the other hand, see Table 11 and Figure 29 The thicker the first member 22a, the lower the initial inductance. If the inductance at low current values decreases, the current ripple during low-current operation increases. Therefore, if the ratio exceeds 0.5, there is a risk of increased iron loss in the reactor or unstable rotation. Setting the ratio of the thickness L1 of the first member 22a to the overall thickness L2 of the yoke 22 to 0.5 or less maintains the initial inductance while reducing AC losses.

[0263] (Other embodiments)

[0264] While embodiments of the present invention are described in this specification, these embodiments are provided as examples and are not intended to limit the scope of the invention. The embodiments described above can be implemented in various other ways, and various omissions, substitutions, and modifications may be made without departing from the scope of the invention. Such embodiments or modifications thereof are intended to be within the scope and spirit of the invention and are also intended to be within the scope of the invention set forth in the claims and their equivalents.

[0265] The magnetic powder of the composite magnetic material can contain two or more magnetic powders with different average particle sizes. In this case, the magnetic powder includes a first magnetic powder and a second magnetic powder with a smaller average particle size than the first magnetic powder. The weight ratio of the first magnetic powder to the second magnetic powder is preferably 80:20 to 60:40. This range improves density and magnetic permeability while reducing iron loss.

[0266] The average particle size of the first magnetic powder is preferably 100 to 200 μm, and the average particle size of the second magnetic powder is preferably 3 to 10 μm. This is because the second magnetic powder with a smaller average particle size can enter the gaps between the first magnetic powder particles, thereby increasing density and magnetic permeability and reducing iron loss.

[0267] The first and second magnetic powders are preferably spherical. The circularity of the first magnetic powder is preferably 0.90 or greater, and the circularity of the second magnetic powder is preferably 0.90 or greater. This is because the gaps between the first magnetic powder particles are reduced, allowing more second magnetic powder to enter these gaps, thereby improving density and magnetic permeability.

[0268] Furthermore, the first magnetic powder and the second magnetic powder may be of the same or different types. In the case of different types, they may be of three or more types. When three or more types of powder are used to form the magnetic powder, the average particle size of each type may be different.

[0269] SiO2, Al2O3, Fe2O3, BN, AlN, ZnO, TiO2, and other viscosity-adjusting materials can be used in the resin. The average particle size of the viscosity-adjusting material should be less than or equal to the average particle size of the second magnetic powder, and preferably less than one-third of the average particle size of the second magnetic powder. This is because a larger average particle size of the viscosity-adjusting material prevents the magnetic powder from being fully retained, resulting in a lower density of the resulting core. Furthermore, high thermal conductivity materials such as Al2O3, BN, and AlN can be added to the resin.

[0270] The ratio of the core's apparent density to the magnetic powder's true density is preferably greater than 76.47%, more preferably 77.5% or greater. A ratio exceeding 76.47% can improve magnetic permeability. Conversely, a ratio below 76.47% results in low magnetic permeability due to low density.

[0271] In the first embodiment, an MC core is used for the leg 21, and a powder magnetic core is used for the yoke 22. However, this is not limiting; MC cores may be used for both the leg 21 and the yoke 22. In this case, the MC core of either the leg 21 or the yoke 22 is first formed into a solidified compact. The compacts are then bonded to the clay-like composite magnetic material resin that serves as the other MC core.

[0272] In addition, in this embodiment, Figure 2 As shown, the yoke 22 is joined to the end face of the leg 21 perpendicular to the winding axis direction of the coil 3, but this is not limited to this. As long as the core 2 can be joined by the composite magnetic resin, it can be applied to various forms. For example, the long sides of the two block-shaped legs 21 can be arranged parallel, and a pair of yokes 22 made of composite magnetic material are provided between the legs 21. Specifically, the legs 21 can have portions at both ends where the coil 3 is not wound, and the yoke 22 can be provided between the legs 21 where the coil 3 is not wound, and the legs 21 and yokes 22 can be joined by the composite magnetic resin.

[0273] In addition, for example, the opening ratio of the opening portion for exposing the coil 3 from the core 2 can be appropriately selected as long as it exceeds 60%. The upper limit of the opening ratio can be determined by the cross-sectional area of the outer leg that meets the required inductance characteristics, etc. In addition, in the yoke 22 of the roughly hexagonal shape of the third embodiment, the corners are straight lines, but it can also be the same as the yoke 25 of the fourth embodiment, with an extension extending outward from the outer diameter of the center leg 21A, or the corners on the outer leg 21B side can be set to R shape. Furthermore, in the yoke 22 of the roughly hexagonal shape, the corners of the portion facing the end face of the coil 3 can be set to R shape. In addition, in the fifth embodiment, although four outer legs are provided, the number of outer legs can be appropriately changed.

Claims

1. A reactor, characterized in that: include: a core having a plurality of legs and a pair of yokes disposed at both ends of the plurality of legs; a coil wound around the foot; as well as a resin member covering the core, in, The leg comprises a composite magnetic material containing magnetic powder and resin, The leg portion and the yoke portion are joined by the resin of the composite magnetic material. The resin member has: a plurality of straight portions covering the foot; as well as A connecting portion connects the plurality of straight line portions. The connecting portion has an opening at an end surface opposite to an end surface connecting the linear portions.

2. The reactor according to claim 1, characterized in that: The foot is seamlessly and continuously joined to the yoke.

3. The reactor according to claim 1 or 2, characterized in that: The yoke part that does not contain the composite magnetic material has a concave-convex end surface where the leg part and the yoke part are joined. The composite magnetic material enters the concave portion of the concavo-convex portion.

4. The reactor according to claim 1 or 2, characterized in that: The leg portion or the yoke portion including the composite magnetic material is integrally molded with the resin member without a gap using the resin of the composite magnetic material.

5. The reactor according to claim 1 or 2, characterized in that: The entire outer peripheral surface of the leg portion or the yoke portion including the composite magnetic material is a non-sliding surface.

6. The reactor according to claim 1 or 2, characterized in that: The foot includes the composite magnetic material.

7. The reactor according to claim 1 or 2, characterized in that: The magnetic permeability of the yoke is greater than the magnetic permeability of the leg.

8. A method for manufacturing a reactor, wherein: The reactor includes a core and a resin member covering the core, the core including a plurality of legs and yokes disposed at both ends of the legs, the legs comprising a composite magnetic material containing magnetic powder and resin, and a method for manufacturing the reactor comprising: a mounting step of mounting the coil on the resin member, wherein the resin member has: a plurality of straight portions covering the leg portions; and a connecting portion connecting the plurality of straight portions, the connecting portion having an opening on an end surface opposite to an end surface connecting the straight portions; a filling step of filling the clay-like composite magnetic material into the resin member through the opening; a pressurizing step of pressurizing the composite magnetic material injected into the resin member; and a curing step to cure the resin, in, In the filling step, a clay-like composite magnetic material is filled into the resin member covering the leg portion. In the pressurizing step, the composite magnetic material is pressurized via the core constituting the yoke.

9. A method for manufacturing a reactor, wherein the reactor comprises a core and a resin member covering the core, the core comprising a plurality of legs and yokes disposed at both ends of the legs, the yokes comprising a composite magnetic material containing magnetic powder and resin, and the method comprising: a mounting step of mounting the coil on the resin member, wherein the resin member has: a plurality of straight portions covering the leg portions; and a connecting portion connecting the plurality of straight portions, the connecting portion having an opening on an end surface opposite to an end surface connecting the straight portions; a filling step of filling the clay-like composite magnetic material into the resin member through the opening; a pressurizing step of pressurizing the composite magnetic material injected into the resin member; and a curing step to cure the resin, In the installation step, the leg portion formed into a molded body in advance is inserted into the resin member. In the filling step, the clay-like composite magnetic material is filled into the resin member covering the yoke. In the pressurizing step, the composite magnetic material is pressurized by a pressing member.

10. The method for manufacturing a reactor according to claim 8 or 9, characterized in that: The magnetic permeability of the yoke is greater than the magnetic permeability of the leg.

11. The method for manufacturing a reactor according to claim 8 or 9, characterized in that: The leg portion or the yoke portion that is not formed of the clay-like composite magnetic material has irregularities on the end surface where the leg portion and the yoke portion are joined.

12. A reactor, characterized in that: include: a core having a plurality of legs and a pair of yokes disposed at both ends of the plurality of legs; as well as The coil, wound around the foot, The leg comprises a composite magnetic material containing magnetic powder and resin, The yoke has: a first member comprising the composite magnetic material; and a second member comprising a material different from the composite magnetic material, The first member is arranged on the side where the leg is arranged, is formed integrally with the leg, and connects the plurality of legs. The end faces of the first member and the second member, which are perpendicular to the winding axis direction of the coil, have substantially the same shape, and the end faces of the first member and the second member are joined to each other. The magnetic permeability of the second member is greater than the magnetic permeability of the leg and the first member, A ratio of a thickness of the first member in a winding axis direction of the coil to a thickness of the entire yoke in the winding axis direction is 0.5 or less.

13. The reactor according to claim 12, characterized in that: The outer peripheral surfaces of the leg portion and the first member including the composite magnetic material are all non-sliding surfaces.

14. The reactor according to claim 12 or 13, characterized in that: In the yoke, the first member and the second member are joined by the resin of the composite magnetic material of the first member.

15. The reactor according to claim 12 or 13, characterized in that: In the yoke, the first member and the second member are seamlessly and continuously joined.

16. A reactor, characterized in that: include: The core has a middle leg on which a coil is wound, an outer leg arranged outside the middle leg, and a yoke portion arranged at both ends of the middle leg and both ends of the outer leg. The middle leg and the outer leg comprise a composite magnetic material containing magnetic powder and resin, and An opening portion is formed for exposing the coil from the core, and when the opening ratio is 0% when the entire circumference of the coil is housed inside the core and 100% when the entire circumference of the coil is exposed from the core, the opening ratio of the opening portion is set to be greater than 60%. The yoke includes a first component and a second component, the first component includes the composite magnetic material, and the second component includes a material having a magnetic permeability greater than that of the composite magnetic material. The yoke and the middle leg, as well as the yoke and the outer leg, are joined by the composite magnetic material of the first member.

17. The reactor according to claim 16, characterized in that: The opening ratio of the opening portion is set to 67% or more.

18. The reactor according to claim 16 or 17, characterized in that: The magnetic permeability of the second member is greater than the magnetic permeability of the first member.

19. The reactor according to claim 18, characterized in that: The second member includes at least a powder magnetic core, ferrite, and laminated steel plates.

20. The reactor according to claim 16 or 17, characterized in that: The middle foot and the outer foot are respectively one, The cross-sectional shape of the midfoot is circular or elliptical, The outer leg has a diameter greater than that of the middle leg and has a width dimension less than the diameter of the outer periphery of the coil.

21. The reactor according to claim 20, characterized in that: The yoke is a roughly hexagonal shape that combines the following parts: a semicircular part that is connected to the diameter part of the middle leg; a trapezoidal part with the diameter part of the middle leg as the short side; and a rectangular part that is connected to the trapezoidal part with the long side opposite to the short side.

22. The reactor according to claim 20, characterized in that: The yoke portion is formed by cutting a corner portion on the mid-leg side into a substantially triangular shape.

23. The reactor according to claim 20, characterized in that: The yoke has a protruding portion that protrudes outward from the outer radial side of the mid-leg.

24. The reactor according to claim 20, characterized in that In the yoke, a corner portion on the outer leg side is formed into an R shape.

25. The reactor according to claim 20, characterized in that The yoke portion has an R-shaped corner portion at a portion facing an end surface of the coil.

26. The reactor according to claim 16 or 17, characterized in that: The outer leg has a chamfered portion.

27. The reactor according to claim 16 or 17, characterized in that: The core is configured such that a plurality of the outer legs surround the middle leg.

28. The reactor according to claim 27, characterized in that The yokes arranged at both ends of the plurality of outer legs are configured to spread evenly and radially.

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