Coil device

Abstract

To provide a coil device that offers good heat dissipation and is also miniaturized and lightweight. [Solution] A magnetic core according to one embodiment of the present invention comprises a first core. The first core has a first middle leg, an annular portion surrounding the first middle leg, and a first yoke connecting the first middle leg and the annular portion at one end. The end face of the first middle leg and the end face of the annular portion are formed on the same plane. An annular recess capable of accommodating a coil is formed between the first middle leg and the annular portion.

Description

Technical Field

[0001] The present invention relates to a magnetic core and a coil device.

Background Art

[0002] Since a large-capacity coil device generates a relatively large amount of heat during use, in order to obtain stable characteristics, means for efficiently discharging heat to the outside are required. Patent Document 1 describes an example of a coil device provided with such means.

[0003] Patent Document 1 describes a transformer in which a winding (hereinafter referred to as a "coil") and a magnetic core (hereinafter referred to as a "core") are housed in a case made of a material having a high thermal conductivity such as aluminum, and the inside of the case is filled with a filler such as silicone resin. A cooling device such as cooling fins is provided outside the case, and the heat generated in the element part (coil and core) of the transformer is efficiently discharged to the outside through the filler and the case.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, since the transformer described in Patent Document 1 has a structure in which the entire element part including the core is housed in a case, it is difficult to miniaturize and lighten the weight.

[0006] The present invention has been made in view of the above circumstances, and an object thereof is to provide a coil device having good heat dissipation performance and capable of being miniaturized and lightened.

Means for Solving the Problems

[0007] A magnetic core according to one embodiment of the present invention comprises a first core, the first core having a first middle leg, an annular portion surrounding the first middle leg, and a first yoke connecting the first middle leg and the annular portion at one end, the end face of the first middle leg and the end face of the annular portion being formed on the same plane, and an annular recess capable of accommodating a coil being formed between the first middle leg and the annular portion.

[0008] In the magnetic core described above, the recess may be formed such that it is surrounded by a first middle leg, an annular portion, and a first yoke, and is capable of storing a liquid filler.

[0009] By using a magnetic core with this configuration in a coil device and filling the recess with a filler material, the heat generated in the coil can be quickly released through the first core. Therefore, it becomes unnecessary to house the entire element part of the coil device, including the magnetic core, in a heat dissipation case, making it possible to miniaturize and lighten the coil device while ensuring good heat dissipation.

[0010] In the magnetic core described above, the first core may have a pair of first side legs and a pair of third yokes connecting the pair of first side legs and the first yoke, and the pair of first side legs and the pair of third yokes may be connected to form an annular portion.

[0011] In the magnetic core described above, the third yoke may be configured to have a hole or groove extending parallel to the first middle leg through which a fixing bolt is passed.

[0012] This configuration allows for the mounting of the magnetic core without the use of mounting brackets, enabling miniaturization and weight reduction of the coil device.

[0013] In the magnetic core described above, the first core may be assembled from a main part and a pair of sub-parts, the main part having a first central leg, a pair of first side legs, and a first yoke, and the sub-parts having a third yoke.

[0014] This configuration allows the size of the magnetic core components to be reduced to approximately the same size as an E-type core of the same capacity, making it possible to form them using the same press equipment as an E-type core. Furthermore, it becomes possible to reduce the size of the mold used for forming the magnetic core.

[0015] In the magnetic core described above, a second core may be provided, wherein the second core has a second middle leg, and a region wider than the second middle leg is formed in at least one direction around the second middle leg that is not surrounded by a part of the second core.

[0016] With this configuration, the inductance value can be adjusted by adjusting the length of the second middle leg through machining or other processes.

[0017] In the magnetic core described above, the second core may be configured to have a pair of second side legs facing each other with a second middle leg in between, and a second yoke connecting the second middle leg and the pair of second side legs at one end.

[0018] Furthermore, according to one embodiment of the present invention, a coil device is provided comprising any of the above-mentioned magnetic cores, a coil housed in a recess and through which a first central leg passes, a filler material filled in the recess of the first core, and mounting means for attaching the coil device to a mounting surface, wherein a flat heat dissipation surface is formed on one surface of the first core, excluding the surface in which the recess is formed, and the mounting means is configured to allow the coil device to be attached such that the heat dissipation surface is pressed against the mounting surface. [Effects of the Invention]

[0019] According to one embodiment of the present invention, a coil device is provided that has good heat dissipation and can be made smaller and lighter. [Brief explanation of the drawing]

[0020] [Figure 1] This is an external view of a switching transformer according to the first embodiment of the present invention. [Figure 2]Exploded view of the switching transformer according to the first embodiment of the present invention. [Figure 3] Plan view of the core. [Figure 4] Side view of the second core (lid-shaped core). [Figure 5] Perspective view of the first core (box-shaped core) according to the second embodiment of the present invention. [Figure 6] Exploded view of the core according to the third embodiment of the present invention.

Mode for Carrying Out the Invention

[0021] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same or corresponding matters are denoted by the same or corresponding reference numerals, and redundant descriptions are omitted.

[0022] <First Embodiment> FIG. 1 and FIG. 2 are an external view and an exploded view of a switching transformer 1 according to the first embodiment of the present invention, respectively. The switching transformer 1 is a large-capacity coil device used, for example, in a rapid charging device for an electric vehicle.

[0023] In the following description, the direction from the lower right to the upper left in FIG. 1 is defined as the X direction, the direction from the upper right to the lower left is defined as the Y direction, and the direction from the bottom to the top is defined as the Z direction. The X direction, the Y direction, and the Z direction are directions orthogonal to each other. The switching transformer 1 may be used in a state where any of the X direction, the Y direction, the Z direction, and the intermediate directions thereof is directed vertically. In the following description, for convenience of explanation, the X direction may be referred to as the length direction or the front-rear direction, the Y direction may be referred to as the width direction or the left-right direction, and the Z direction may be referred to as the height direction or the up-down direction.

[0024] The switching transformer 1 includes a main body 1a and a mounting bracket 7 (mounting means) for mounting the main body 1a on, for example, the cooling surface of a heat sink or a cooling device. The main body 1a includes a core 2 and a coil portion 4.

[0025] As shown in Figure 2, the coil section 4 comprises a primary coil 40, a secondary coil 50, and a bobbin 60 around which coils 40 and 50 are wound. Coils 40 and 50 are made by spirally winding conductors coated with an insulating coating such as enamel. A pair of leads 42 and 52 are drawn out from both ends of the winding sections 41 and 51 of coils 40 and 50, respectively, and crimp terminals 43 and 53 are attached to the ends of each lead 42 and 52. The allowable current for coils 40 and 50 and leads 42 and 52 is 5A or more.

[0026] Coils 40 and 50 are wound around a bobbin 60 and housed together with the bobbin 60 in the hollow section of the core 2 (the housing section 20a of the core 20, which will be described later).

[0027] The bobbin 60 is formed from an electrically insulating material such as phenolic resin, epoxy resin, unsaturated polyester resin, urethane resin, BMC (Bulk Molding Compound), PPS (Polyphenylene Sulfide), or PBT (Polybutylene Terephthalate) to ensure sufficient electrical insulation between the coils 40 and 50 and the core 2, and between the coils 40 and 50 themselves.

[0028] The bobbin 60 has a cylindrical body 61 extending in the Z direction, a flange 62 including three annular plate-shaped flanges 62A, 62B, and 62C that protrude perpendicularly from the outer circumferential surface of the body 61, and a pair of lead pull-out portions 63 provided at both ends in the Y direction of the flange 62 (more specifically, flanges 62A and 62B).

[0029] A flange portion 62A protrudes from one end (the upper end in Figure 2) in the Z direction of the body portion 61, a flange portion 62B protrudes from the central portion, and a flange portion 62C protrudes from the other end (the lower end in Figure 2). A coil 50 is housed between flange portions 62A and 62B, and a coil 40 is housed between flange portions 62B and 62C.

[0030] The lead extraction section 63 includes a lead extraction section 63A provided on the flange section 62A and a lead extraction section 63B provided on the flange section 62B. One or more grooves 64 are formed in each lead extraction section 63A, 63B, extending from the outside to the inside in the Y direction. Each lead 42, 52 is passed through the groove 64 and extracted to the outside of the bobbin 60.

[0031] The core 2 of this embodiment is a ferrite core and includes a box-shaped core 20 (first core) having a housing portion 20a which is a recess in which the coil portion 4 is housed, and a PQ-shaped core 30 (second core).

[0032] The core 20 has a cylindrical central leg 21 (first central leg) extending in the Z direction, a pair of side legs 22 (first side legs) facing each other in the X direction with the central leg 21 in between, a first yoke 23 connecting the central leg 21 and the pair of side legs 22 at one end in the Z direction (the lower end in Figure 2), and a pair of third yokes 24 connecting the pair of side legs 22 and the first yoke 23 at one end or the other end in the Y direction. The pair of side legs 22 and the pair of third yokes 24 form an annular portion surrounding the central leg 21. Furthermore, the roughly E-shaped portion of the core 20 consisting of the central leg 21, the pair of side legs 22 and the first yoke 23 has the same shape as a PQ-type magnetic core (or ETD-type magnetic core). That is, the core 20 has the shape of a PQ-type magnetic core (or ETD-type magnetic core) with the openings at both ends in the Y direction closed by the pair of third yokes 24. Around the central leg 21, a housing portion 20a is formed, which is an annular hollow portion (in other words, an annular recess formed on the upper surface of the core 20) surrounded on three sides by a pair of side legs 22, a first yoke 23, and a pair of third yokes 24. Furthermore, by providing the third yoke 24 and forming an annular portion surrounding the coil portion 4, the electromagnetic noise generated by the coils 40 and 50 is shielded by the annular portion, and the emission of electromagnetic noise to the outside is reduced.

[0033] The core 30 has a central leg 31 (second central leg), a pair of side legs 32 facing each other in the X direction with the central leg 31 in between, and a yoke 33 (second yoke) that connects the central leg 31 and the pair of side legs 32 at one end in the Z direction (upper end in Figure 2). The central leg 31 has the same cross-sectional shape as the central leg 21 of the core 20, and the side legs 32 have the same cross-sectional shape as the side legs 22 of the core 20. Approximately V-shaped notches 33a are formed at both ends of the yoke 33 in the Y direction.

[0034] Core 2 is formed when the end faces of the middle legs 21 and 31, and the end faces of the pair of side legs 22 and 32 are abutted against each other.

[0035] Figure 3 is a plan view of core 2. In this embodiment, the length of core 30 (size in the X direction) is the same as the length of core 20. Also, the width of core 30 (size in the Y direction) is the same as the width of the side legs 22 of core 20 (i.e., narrower than the width of the housing portion 20a). Therefore, in core 2, which is a combination of core 20 and core 30, the housing portion 20a is not completely blocked by core 30, and a part of the housing portion 20a (exposed portion 20b shown in Figure 3) is exposed.

[0036] The coil section 4 is housed in the housing section 20a. When the core 2 is assembled with the coil section 4 housed in the housing section 20a, the lead lead-out section 63A is positioned adjacent to both sides of the core 30 in the Y direction so as to cover the exposed section 20b. The leads 42 and 52 are then led out of the core 2 through this exposed section 20b (more specifically, through the groove 64 of the lead lead-out section 63).

[0037] The housing portion 20a of the core 30 is filled with a thermally conductive filler after the coil portion 4 is housed therein. In this embodiment, for example, a silicone resin having a thermal conductivity of 1 W / m·K or higher (more preferably 2 W / m·K or higher) is used as the filler. As a result, the heat generated in the coils 40 and 50 is quickly transferred to the core 30 and released to the heat sink or cooling device via the mounting bracket 7.

[0038] The core 30 in this embodiment is container-shaped with a housing section 20a, and therefore also functions as a case for storing the packing material. As a result, there is no need to separately provide a large case to house the entire body 1a (core 2 and coil section 4) of the switching transformer 1. Consequently, the number of parts and assembly man-hours can be reduced, and miniaturization and weight reduction are possible.

[0039] The mounting bracket 7 is a sheet metal part formed by pressing or other methods from a metal plate with high thermal conductivity, such as a copper alloy (e.g., brass), and consists of two parts: a main bracket 70 and a retaining bracket 80.

[0040] The main body fitting 70 has a base plate portion 71, a pair of first side plate portions 72 extending vertically upward from both ends of the base plate portion 71 in the X direction, a pair of second side plate portions 74 extending vertically upward from both edges of the base plate portion 71 in the Y direction, and two pairs of claws 73 protruding inward in the X direction from the tips of the first side plate portions 72. In addition, legs 75 extending in the Y direction are formed at the four corners of the base plate portion 71, and through holes 76 are formed in the legs 75.

[0041] The pair of first side plates 72 are formed parallel to each other, spaced approximately the same as the length of the core 2 (size in the X direction). The pair of second side plates 74 are formed parallel to each other, spaced approximately the same as the width of the core 20 (size in the Y direction). In addition, the height of the first side plates 72 (i.e., the distance between the bottom plate 71 and the claws 73) is formed to be approximately the same as the height of the core 2.

[0042] The retaining bracket 80 has a top plate portion 81 and two pairs of side plate portions 82 that extend vertically downward from the four corners of the top plate portion 81. Each pair of side plate portions 82 facing each other in the Y-axis direction is formed with a spacing that is approximately the same as the width (size in the Y-direction) of the core 30. The top plate portion 81 has approximately V-shaped notches 81a formed in the center of both sides in the Y-direction, and is formed to be approximately the same shape as the upper surface of the core 30.

[0043] The main body 1a of the switching transformer 1 is inserted between the pair of first side plates 72 and the pair of second side plates 74 of the main body fitting 70 and placed on the bottom plate 71. The retaining bracket 80 is then placed on top of the main body 1a of the switching transformer 1 (at this time, the core 30 is sandwiched between the two pairs of side plates 82), and the mounting bracket 7 is attached to the main body 1a of the switching transformer 1 by bending the two pairs of claws 73 inward.

[0044] The switching transformer 1 is attached to a heat sink or cooling device by bolts passed through holes 76 in the main body fitting 70. At this time, the bottom plate portion 71 of the main body fitting 70 comes into contact with the cooling surface of the heat sink or cooling device, and the heat generated in the main body 1a of the switching transformer 1 is transferred to the cooling surface via the bottom plate portion 71.

[0045] Next, we will explain the procedure for assembling switching transformer 1. First, the coil section 4 is assembled. First, coils 40 and 50 are wound around the bobbin 60, and leads 42 and 52 are passed through grooves 64 of the lead outlet section 63 and pulled out upwards (opposite side of the body section 61). In order to ensure insulation between leads 42 and 52, it is preferable to limit the number of leads 42 and 52 passed through each groove 64 to only one. In order to ensure insulation between leads 42 and 52, it is preferable to pass one of the pair of leads 42 and 52 of each coil 40 and 50 through one groove 64 of the pair of lead outlet sections 63, and pass the other lead 42 and 52 through the groove 64 of the other lead outlet section 63.

[0046] Next, the coil section 4 is placed in the housing section 20a of the core 20, and a filler material is poured into the gap in the housing section 20a, and the filler material is hardened (or made non-flowing).

[0047] Next, the core 30 is combined with the core 20 to complete the main body 1a. At this time, the pair of lead lead outlets 63A of the bobbin 60 are fitted into the pair of notches 33a of the core 30. In other words, the core 30 is fitted between the pair of lead lead outlets 63A. Also at this time, the end faces 22a of the pair of side legs 22 of the core 20 and the end faces 32a of the pair of side legs 32 of the core 30 are brought into contact. The end faces 22a of the side legs 22 and the end faces 32a of the side legs 32 may be glued together.

[0048] Finally, the mounting bracket 7 is attached to the main body 1a. In this step, first, the main body 1a (specifically, the core 20) is inserted between the pair of first side plates 72 and the pair of second side plates 74 of the main body bracket 70, and the main body 1a is placed on the bottom plate 71 of the main body bracket 70. Next, with the bottom surface of the core 20 in close contact with the bottom plate 71, the claws 73 are bent inward, and the core 2 is tightened between the bottom plate 71 and the four claws 73, thereby fixing the mounting bracket 7 to the main body 1a, and the switching transformer 1 is completed.

[0049] A magnetic gap is formed between the end face 21a of the middle leg 21 of core 20 and the end face 31a of the middle leg 31 of core 30. In order to give core 2 a predetermined inductance value, it is necessary to precisely adjust the gap length of the magnetic gap by grinding the end face 21a of the middle leg 21 or the end face 31a of the middle leg 31.

[0050] As described above, the housing portion 20a of the core 20 is filled with a filler material. In order to improve the heat dissipation of the main body 1a, it is desirable to fill the housing portion 20a with filler material up to near its upper limit, thereby minimizing the area of ​​the core 20 exposed to the air. Furthermore, if filler material adheres to the end faces of the core 20 (end faces 21a, 22a, and the end face 24a of the third yoke 24), it becomes difficult to adjust the magnetic gap, and the magnetic gap may fluctuate due to the thermal expansion of the filler material, potentially causing the inductance value to become unstable. For this reason, in the core 20 of this embodiment, the end faces 21a, 22a, and 24a of the core 20 are formed on the same plane perpendicular to the Z direction. Consequently, it is undesirable to change the length of the middle leg 21 of the core 20.

[0051] Furthermore, since the central leg 21 is surrounded by a pair of annularly connected side legs 22 and the first yoke 23, it is difficult to perform cutting or grinding only on the end face 21a of the central leg 21.

[0052] Figure 4 is a side view of the core 30 as seen from the Y direction. In Figure 4, only the middle leg 31 and the yoke 33 exist in the region R sandwiched between the pair of side legs 32. The width W of region R is large enough to allow a tool used for machining the end face 31a, such as an end mill, to pass through. Also, since the tip of the middle leg 31 protrudes from the yoke 33, the yoke 33 does not interfere with the machining of the end face 31a of the middle leg 31. In other words, since there is no structure within region R that would hinder the machining of the end face 31a, it is possible to perform cutting or grinding on the end face 31a by introducing a tool into region R from the Y direction. That is, in this embodiment, by using a PQ-type magnetic core in the core 30, the inductance value can be adjusted by performing cutting or grinding on the end face 31a of the middle leg 31 of the core 30.

[0053] Furthermore, the shape of the core 30 is preferably such as PQ type, or E type, ETD type, ER type, EL type, EFD type, EP type, RM type, pot type, etc., in which at least one gap is formed between the side legs that is wide enough for a tool to pass through (at least wider than the middle leg 31). In other words, it is preferable that a region wider than the middle leg 31 (i.e., a region wide enough for a tool to pass through) is formed in at least one direction around the middle leg 31 that is not surrounded by a part of the core 30. Using a core 30 of such a shape makes it easy to adjust the inductance value by adjusting the length of the middle leg 31 by cutting or grinding. The core 30 may also be a simple flat plate or block shape, for example, without a middle leg 31 or side legs 32.

[0054] <Second Embodiment> Figure 5 is a perspective view of the core 20A of the switching transformer 1A according to a second embodiment of the present invention. Note that the switching transformer 1A of the second embodiment differs from the switching transformer 1 of the first embodiment only in the shape of the core 20A (core 2A).

[0055] At the four corners of the core 20A, grooves 25 (mounting means) with a U-shaped cross-section are formed, penetrating in the Z direction (i.e., extending parallel to the central leg 21). Note that the core 20A differs from the core 20 of the first embodiment only in that grooves 25 are formed therein. Bolts are passed through the grooves 25. These bolts allow the core 20A (switching transformer 1A) to be attached, for example, to the cooling surface of a heat sink or cooling device. Therefore, the switching transformer 1A of this embodiment can be attached to a heat sink or the like without using the mounting bracket 7 of the first embodiment, making it possible to make it smaller and lighter. Note that the core 30 is not placed on the third yoke 24 on which the grooves 25 are formed (see Figure 3), so the bolts passed through the grooves 25 do not interfere with the core 30. Also, since the height of the head of a typical bolt is smaller than the thickness of the core 30, passing the bolts through the grooves 25 does not increase the height of the switching transformer 1A.

[0056] Alternatively, a through-hole for a bolt may be provided in the core 20A instead of the groove 25. Alternatively, a reinforcing collar (cylindrical metal member) may be inserted around the inner circumference of the groove 25 or through-hole, and a bolt may be passed through the hollow portion of the collar. Note that if the core 20A is a ferrite magnetic core, a collar is unnecessary due to its high compressive strength; however, if it is a compacted magnetic core, reinforcement with a collar is required.

[0057] <Third Embodiment> Figure 6 is an exploded view of the core 2B of the switching transformer 1B according to the third embodiment of the present invention. The switching transformer 1A of the third embodiment differs from the switching transformer 1 of the first embodiment only in the shape of the core 2B (more specifically, the core 20B).

[0058] The core 20B of this embodiment is obtained by cutting the core 20 of the first embodiment in a plane perpendicular to the Y direction and dividing it into three members (a main part 20B1 and a pair of sub-parts 20B2). The main part 20B1 is an ETD-type magnetic core and has a central leg 21, a pair of side legs 22 facing each other in the X direction with the central leg 21 in between, and a first yoke 23 that connects the central leg 21 and the pair of side legs 22 at their lower ends. The sub-parts 20B2 consist of a third yoke 24. In other words, the core 20B of this embodiment can also be described as the core 20 of the first embodiment with two third yokes 24 separated.

[0059] The main part 20B1 and the two sub-parts 20B2 are combined and joined together, for example, with an epoxy adhesive, to form the core 20B. The adhesive layer formed between the main part 20B1 and the two sub-parts 20B2 relieves the stress applied to the core 20B due to the thermal expansion of the filler material, making it less likely for cracks to occur in the core 20B. Note that a different type of adhesive may be used for joining. Alternatively, the individual components constituting the core 20B may be joined by other methods such as various welding, brazing, or bolting.

[0060] Ferrite cores are manufactured by molding (press molding) powdered raw materials and then sintering them. The box-shaped core 20 of the first embodiment has a larger cross-sectional area than typical E-type or ETD-type cores, requiring a larger press load for molding and thus a larger press molding machine. In addition, the size of the mold required for molding is also larger and more expensive.

[0061] The core 20B of this embodiment is formed by combining a main part 20B1, which is a general ETD-type magnetic core, with two sub-parts 20B2 of similar or smaller size. Therefore, each component constituting the core 20B can be molded using a press molding machine used for molding general ETD-type magnetic cores. Furthermore, since it can be molded with a smaller mold than the core 20 of the first embodiment, it is possible to reduce mold manufacturing costs and shorten the manufacturing period.

[0062] In this embodiment, the main part 20B1 and the two sub-parts 20B2 are made of the same material, but they may be made of different materials. The sub-parts 20B2 may also be made of a non-magnetic material such as resin. However, if the main part 20B1 and the two sub-parts 20B2 are made of different materials (especially if a non-magnetic material is used for the sub-parts 20B2), magnetic flux leakage will increase. It is desirable that the main part 20B1 and the two sub-parts 20B2 be made of the same material, or materials with as similar magnetic permeability as possible.

[0063] The sub-part 20B2 may also be provided with the groove 25 of the second embodiment.

[0064] The PQ, E, ETD, ER, EL, EFD, EP, RM, and pot-shaped cores mentioned above are the core shapes described in the Japanese Industrial Standard JIS C 2560-1:2014.

[0065] The above describes embodiments of the present invention, but the present invention is not limited to the configurations of the embodiments described above, and various modifications are possible within the scope of its technical idea. For example, embodiments of the present invention also include combinations of at least a part of the technical configuration of one or more embodiments described in the specification with well-known technical configurations.

[0066] In each of the embodiments described above, cores 2, 2A, and 2B are ferrite cores, but cores of other materials may also be used (for example, laminated cores, powdered cores, amorphous metal cores, metal composite cores formed from resin containing magnetic particles, etc.).

[0067] In each of the embodiments described above, a flat heat dissipation surface is formed on the bottom surface of the first core (core 20, 20A, 20B) in which a filler material is filled into the recess (housing portion 20a), and the coil device (switching transformer 1, 1A, 1B) is attached to the mounting surface (for example, the cooling surface of a heat sink or cooling device) by mounting means so as to press the heat dissipation surface directly or indirectly against the mounting surface. This allows the heat generated in the main body 1a to be efficiently dissipated. Note that the heat dissipation surface is not limited to the bottom surface of the first core, but may also be provided on another surface of the first core (excluding the surface in which the recess is formed).

[0068] In the embodiments described above, silicone resin is used as the filler, but other types of fillers such as epoxy resin or urethane resin may also be used.

[0069] In the first embodiment described above, the mounting bracket 7 is made of brass, but it may be made of another material (for example, copper, aluminum, aluminum alloy, carbon steel, stainless steel, etc.).

[0070] In the first embodiment described above, the mounting bracket 7 is a sheet metal part, but it may be manufactured by other processing methods such as casting or machining.

[0071] In each of the embodiments described above, the middle leg is cylindrical, but it may be prismatic, elliptical, or have other shapes.

[0072] In each of the embodiments described above, the magnetic gap formed between the middle leg 21 of the core 20 and the middle leg 31 of the core 30 is an air gap, but a gap member made of a non-magnetic material may be inserted into the gap between the middle leg 21 and the middle leg 31.

[0073] Although the above embodiment applies the present invention to a transformer, the present invention is not limited to this configuration, and can be applied to various inductors such as reactors and choke coils, for example. [Explanation of Symbols]

[0074] 1, 1A, 1B Switching Transformers 2, 2A, 2B cores 20 cores 21 Middle leg 22 Side legs 30 cores 31 Middle leg 32 Side legs 4. Coil section 40 coils 50 coils 60 bobbins 7 Mounting brackets 70 Main body fittings 80 Retaining clip

Claims

1. Equipped with a first core, The first core is The first middle leg, The annular portion surrounding the first midfoot, It has a first middle leg and a first yoke connecting the annular portion at one end, The end face of the first middle leg and the end face of the annular portion are formed on the same plane. An annular recess capable of accommodating a coil is formed between the first middle leg and the annular portion. core.

2. The recess is surrounded by the first middle leg, the annular portion, and the first yoke, and is formed to be able to store liquid filler. The magnetic core according to claim 1.

3. The first core is A pair of first lateral legs, It has a pair of third yokes connecting the pair of first side legs and the first yoke, The pair of first side legs and the pair of third yokes are connected to form the annular portion. The magnetic core according to claim 1.

4. The third yoke has a hole or groove formed in it that extends parallel to the first middle leg, through which a fixing bolt is passed. The magnetic core according to claim 3.

5. The first core is assembled from a main part and a pair of sub-parts. The main part is, The aforementioned first middle leg, The pair of first side legs, The first yoke, The aforementioned sub-part is, Having the third yoke, The magnetic core according to claim 3.

6. Equipped with a second core, The second core described above is It has a second middle leg, In at least one direction around the second midfoot, a region wider than the second midfoot is formed that is not surrounded by a portion of the second core. The magnetic core according to claim 1.

7. The second core described above is A pair of second lateral legs facing each other with the aforementioned second middle leg in between, It has a second yoke that connects the second central leg and the pair of second side legs at one end, The magnetic core according to claim 6.

8. A coil device, A magnetic core according to any one of claims 1 to 7, The coil housed in the recess and through which the first middle leg passes, The filler material filled in the recess of the first core, Mounting means for attaching the coil device to the mounting surface, Equipped with, A flat heat dissipation surface is formed on one surface of the first core, excluding the surface on which the recess is formed. The mounting means is configured to allow the coil device to be mounted such that the heat dissipation surface is pressed against the mounting surface. Coil device.

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