Coil component

Abstract

To provide a coil component having high heat dissipation.SOLUTION: A coil component 1 includes a coil 2 formed by winding a conductive wire 21, a bus bar 3 connected to the coil 2, and a heat dissipation path 9 for dissipating heat of the bus bar 3. The heat dissipation path 9 includes the thermally conductive layer 4, the coil 2, and the sealing resin 7. The thermally conductive layer 4 is in contact with the bus bar 3, and is in contact with the surface of the coil 2 on the surface opposite to the contact surface with the bus bar 3. The thermally conductive layer 4 absorbs heat from the busbar 3 and dissipates the heat of the busbar 3 to the coil 2. The coil 2 receives heat of the bus bar 3 from the thermally conductive layer 4.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a coil component. [Background technology]

[0002] When a current is passed through a coil, the coil generates a magnetic flux according to the number of turns, and therefore, the coil is used as an electromagnetic component that converts electric energy into magnetic energy or converts magnetic energy into electric energy, for example, as a transformer, a choke coil, or a reactor.

[0003] In recent years, transformers have also been installed in power converters for automobiles, such as electric vehicles (EVs) and plug-in hybrid electric vehicles (PHEVs), which use battery-powered motors. These power converters convert AC power into DC power using a converter circuit, and then convert this DC power into the desired AC power using an inverter circuit. They are equipped with electromagnetic components such as a transformer and a reactor.

[0004] Reactors are used in a wide variety of applications, including boost reactors, series reactors, parallel reactors, current limiting reactors, starting reactors, shunt reactors, neutral reactors, and arc suppression reactors.

[0005] Boost reactors are incorporated into onboard boost circuits such as those found in the drive systems of hybrid and electric vehicles. Series reactors are connected in series to motor circuits to limit current during short circuits. Parallel reactors stabilize current sharing between parallel circuits. Current-limiting reactors limit current during short circuits and are connected to them. Starting reactors are connected in series to motor circuits to protect the machine and limit starting current. Shunt reactors are connected in parallel to transmission lines to compensate for leading reactive power and suppress abnormal voltages. Neutral reactors are connected between the neutral point and the ground to limit the ground fault current that flows in the event of a ground fault in the power system. Arc-suppression reactors automatically extinguish the arc that occurs when a single-phase ground fault occurs in a three-phase power system.

[0006] A coil generates heat when current is applied. Therefore, a heat dissipation path is required to dissipate the heat generated in the coil. For example, a coil component includes a coil component main body having a core and a coil, a case, and a sealing resin. The case has a bottom at one end and an open at the other end, and the bottom surface is surrounded by side walls on all four sides. The coil component main body is housed in this case. The coil component main body is then embedded in sealing resin filled in a thermally conductive case. The sealing resin is a thermally conductive resin, and absorbs heat from the coil. The case is, for example, a highly thermally conductive case made of metal, and receives the heat of the coil that flows into the sealing resin. This sealing resin and case act as a heat dissipation path for the coil, suppressing a rise in the temperature of the coil (see, for example, Patent Document 1).

[0007] This coil component also includes a metal plate-like bus bar for electrical connection to an external component. The bus bar electrically connects the external component to the coil within the coil component. This bus bar also generates heat when current is passed through it. The heat generated by the bus bar is dissipated into the air by wiring the bus bar in the air (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 2023-102370 [Patent Document 2] Japanese Patent Application Publication No. 2022-183479 Summary of the Invention [Problem to be solved by the invention]

[0009] In the past, coil components typically carried currents of 100A to 200A. However, in recent years, the applications of coil components have become more diverse, and there has been an increasing demand for coil components to be used with large currents. However, when a large current of 500A or more is supplied to a coil component, the heat dissipation of the bus bar, which is wired in the air, cannot keep up and the component becomes very hot. For this reason, it has been difficult to use coil components in applications where a current of 500A or more flows.

[0010] The present invention has been proposed to solve the above-mentioned problems, and has an object to provide a coil component with high heat dissipation properties. [Means for solving the problem]

[0011] In order to achieve the above object, a coil component according to an embodiment of the present invention includes a coil formed by winding a conductive wire, a bus bar connected to the coil, and a heat dissipation path that dissipates heat from the bus bar, wherein the heat dissipation path includes a thermally conductive layer that contacts the bus bar and also contacts a surface of the coil on the side opposite to the contact surface with the bus bar, absorbing heat from the bus bar and dissipating the heat of the bus bar to the coil, and the coil that receives the heat of the bus bar from the thermally conductive layer.

[0012] Two or more of the coils may be provided, and the bus bar may be a common wiring for the plurality of coils.

[0013] The cross-sectional area of ​​the bus bar may be smaller than the cross-sectional area of ​​the conductive wire forming the coil.

[0014] The heat dissipation path may further include a sealing resin that covers a part or all of the coil and receives heat that has flowed from the bus bar via the thermally conductive layer and the coil.

[0015] The device may further include a thermally conductive case that houses the coil and a sealing resin that covers part or all of the coil, wherein the heat dissipation path further includes the thermally conductive case and the sealing resin, and the sealing resin receives heat that flows from the bus bar via the thermally conductive layer and the coil, and the thermally conductive case absorbs heat from the bus bar that has been conducted through the thermally conductive layer, the coil, and the sealing resin.

[0016] The coil may be attached to a core that includes a magnetic material. [Effects of the Invention]

[0017] According to the present invention, heat dissipation from the bus bar can be promoted while suppressing an increase in size, resulting in a coil component with high heat dissipation properties. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 2 is a schematic diagram of a coil component. [Figure 2] FIG. 2 is a cross-sectional view of the coil component. [Figure 3] FIG. 10 is a schematic diagram showing a state in which a thermally conductive layer is laid on a coil. [Figure 4] FIG. 10 is a schematic diagram showing a state in which a bus bar is arranged on the upper surface of a thermally conductive layer. [Figure 5] FIG. 2 is a schematic diagram showing a terminal block mold resin. [Figure 6] FIG. 2 is a circuit diagram of the coil component. [Figure 7] FIG. 3 is a cross-sectional view showing a heat dissipation path in the coil component. [Figure 8] FIG. 10 is a plan view showing another configuration of the coil component. [Figure 9] FIG. 2 is a perspective view showing a cross section of a conductive wire and a bus bar drawn out from a coil. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, coil components according to embodiments of the present invention will be described with reference to the drawings. In each drawing, thickness, dimensions, positional relationships, ratios, shapes, and the like may be emphasized for ease of understanding, but the present invention is not limited to such emphasis.

[0020] 1 is a schematic diagram of a coil component. The coil component 1 includes a coil component body 11, a thermally conductive case 6, and a sealing resin 7. The coil component body 11 is housed in the thermally conductive case 6. The sealing resin 7 is poured into the thermally conductive case 6 and solidifies, sealing the coil component body 11 within the thermally conductive case 6. The coil component body 11 includes a core 5 and a plurality of coils 2. The core 5 is an annular body, and the coils 2 are fitted into the core 5.

[0021] This core 5 contains a magnetic material such as a powder magnetic core, a ferrite magnetic core, a metal composite core, or a laminated steel plate. A powder magnetic core is an annealed compact made by compressing magnetic powder. The magnetic powder is primarily composed of iron, and examples thereof include pure iron powder, iron-based permalloy (Fe-Ni alloy), Si-containing iron alloy (Fe-Si alloy), sendust alloy (Fe-Si-Al alloy), amorphous alloy, nanocrystalline alloy powder, and a mixture of two or more of these powders. A metal composite core is a core made by kneading and molding magnetic powder and resin.

[0022] The coil 2 is a wound body of conductive wire 21 with an insulating coating such as enamel coating. The coil 2 is formed into a cylindrical shape by spirally winding the conductive wire 21 around a winding axis 2a while shifting the winding position for each turn. The cylindrical shape includes a cylindrical shape and a rectangular cylindrical shape, and the coil 2 has an outer peripheral surface 2b that extends along the winding axis 2a and an end surface 2d that is perpendicular to the winding axis 2a. The conductive wire 21 of the coil 2 is, for example, a rectangular wire, and the coil 2 is, for example, an edgewise coil. The wide surface of the conductive wire 21 of the coil 2 extends in a direction perpendicular to the winding axis 2a of the coil 2. There is no limitation on the type of conductive wire 21, and other types of wire such as round wire may also be used. A flatwise coil may also be used as the coil 2.

[0023] The coil 2 has a conductive wire 21 drawn out from an end surface 2d as a lead wire 2e, and generates magnetic flux according to the number of turns when current is passed through the lead wire 2e from a circuit in which the coil component 1 is incorporated. Meanwhile, the core 5 forms a closed magnetic circuit through which the magnetic flux generated by the coil 2 passes with a magnetic permeability higher than that of a vacuum. Therefore, the coil component body 11 is an electromagnetic component that converts electrical energy into magnetic energy and stores and releases it.

[0024] The heat conduction case 6, which houses the coil component body 11, is box-shaped with one end closed and the other end open, and has a rectangular parallelepiped space inside that can house the coil component body 11. The heat conduction case 6 is made of metal and has heat dissipation and magnetic shielding properties. Specifically, the heat conduction case 6 is made of aluminum, an aluminum alloy, or the like.

[0025] The sealing resin 7 reduces vibration of the coil component body 11 by filling the gap between the coil component body 11 and the thermally conductive case 6. The sealing resin 7 also transfers heat from the coil 2 to the thermally conductive case 6. The sealing resin 7 also electrically, chemically, and mechanically protects the coil component body 11 from the external environment, and suppresses short circuits, corrosion, and damage to the coil component body 11. The sealing resin 7 is, for example, a thermosetting resin or a thermoplastic resin. Examples of thermosetting resins include epoxy resin, urethane resin, silicone resin, and unsaturated polyester resin. Examples of thermoplastic resins include PPS resin.

[0026] FIG. 2 is a cross-sectional view of the coil device 1. As shown in FIG. 2, the core 5 is partially or entirely covered with a core mold resin 51. The core mold resin 51 is a resin component made by molding an insulating material. This core mold resin 51 is interposed between the coil 2 and the core 5, and insulates the coil 2 from the core 5. Therefore, the core mold resin 51 only needs to cover at least the portions where the coil 2 and the core 5 face each other, for example, the portions facing the inner circumferential surface 2c and the end surface 2d of the coil 2.

[0027] The material of core mold resin 51 is, for example, epoxy resin, unsaturated polyester resin, urethane resin, BMC (Bulk Molding Compound), PPS (Polyphenylene Sulfide), PBT (Polybutylene Terephthalate), or a composite of these. A thermally conductive filler may be mixed into core mold resin 51.

[0028] The coil 2 is fitted into the core 5 covered with this core mold resin 51. The top surface 2f of the coil 2 is exposed from the sealing resin 7. The top surface 2f is located directly opposite the winding axis 2a from the surface 2g of the outer circumferential surface 2b of the coil 2 that faces the bottom surface 6a of the thermally conductive case 6. FIG. 3 is a schematic diagram showing a state in which a thermally conductive layer 4 is provided on the top surface 2f of the coil 2. As shown in FIGS. 2 and 3, a sheet-like or film-like thermally conductive layer 4 is provided on the top surface 2f of the coil 2 so as to be in direct contact with the top surface 2f. The bottom surface 4a of the thermally conductive layer 4 is made of an elastic material and is in contact with the top surface 2f of the coil 2, and has high thermal conductivity, heat resistance, and insulating properties.

[0029] The thermally conductive layer 4 is made of a base material such as silicone resin, urethane resin, natural rubber, or synthetic rubber, and contains a thermally conductive filler such as silicon nitride, alumina, aluminum nitride, boron nitride, and silicon carbon.

[0030] FIG. 4 is a schematic diagram showing a state in which a bus bar 3 is disposed on the upper surface 4b of the thermally conductive layer 4. As shown in FIGS. 2 and 4, the bus bar 3 is disposed so as to be in direct contact with the upper surface 4b of the thermally conductive layer 4, and the thermally conductive layer 4 and the bus bar 3 are in contact with each other. In other words, the thermally conductive layer 4 is interposed between the bus bar 3 and the coil 2, and the thermally conductive layer 4 is in contact with both the bus bar 3 and the coil 2. The bus bar 3 is a conductive plate, and is welded to the lead wire 2e of the coil 2 for electrical continuity. The bus bar 3 supplies current from the outside to the coil 2, or passes current output from the coil 2 to the outside.

[0031] 5 is a schematic diagram showing a terminal block molded resin 82. As shown in FIG. 5, the bus bar 3 is arranged by being molded in the terminal block molded resin 82. As shown in FIGS. 2 and 5, the bus bar 3 is molded in the terminal block molded resin 82. The terminal block molded resin 82 bridges the opening of the thermally conductive case 6 and is fixed to the edge of the thermally conductive case 6 with bolts 83. The bottom surface 3a of the bus bar 3 is exposed from the terminal block molded resin 82 and is in contact with the thermally conductive layer 4.

[0032] This terminal block mold resin 82 extends beyond the heat conduction case 6 and is provided with a terminal block 8 located outside the heat conduction case 6 (see FIG. 2). The terminal block 8 is provided for electrically connecting external terminals, and the ends of the bus bars 3 that protrude from the heat conduction case 6 are introduced into the terminal block 8. Fastening holes 3b are drilled in the bus bars 3 within the terminal block 8, and after the external terminals are aligned, they are fastened with nuts 81 to electrically connect the bus bars 3 and the external terminals.

[0033] 6 is a circuit diagram of this coil component 1. As shown in FIGS. 2 and 6, such a coil component 1 includes a plurality of coils 2, for example, two coils 2. At least some of the plurality of coils 2 are connected in parallel, and each lead wire 2e is welded to a common bus bar 3. In other words, one bus bar 3 is a common wiring for the plurality of coils 2, and current is distributed from the single bus bar 3 to the plurality of coils 2, or current is led from the plurality of coils 2 to the single bus bar 3. In other words, the total amount of current flowing through the plurality of coils 2 flows through the single bus bar 3.

[0034] When a bus bar 3 connected to multiple coils 2 supplies a large current to each coil 2, the bus bar 3 conducts the sum of the currents of the connected coils 2, and therefore becomes hotter than each of the coils 2. However, the coil component 1 has a heat dissipation path 9 as shown in Figure 7. That is, the thermally conductive layer 4 forms part of the heat dissipation path 9, and the heat of the bus bar 3 is absorbed by the thermally conductive layer 4 in contact with the bus bar 3.

[0035] The thermally conductive layer 4 is sandwiched between the busbar 3 and the coil 2, and the busbar 3 has a higher temperature than the coil 2. The coil 2 is immersed in sealing resin 7, which is in contact with the thermally conductive case 6. As a result, the temperature gradient is highest in the busbar 3, followed by the thermally conductive layer 4, which absorbs the heat from the busbar 3, and the coil 2 has the lowest temperature among the busbar 3, the thermally conductive layer 4, and the coil 2. Therefore, the coil 2 serves as a heat dissipation path 9 that transfers the heat from the busbar 3. In other words, the coil 2 receives the heat from the busbar 3 that has been absorbed by the thermally conductive layer 4. The heat from the busbar 3 that the coil 2 receives is transferred to the sealing resin 7, then to the thermally conductive case 6, and is dissipated from the thermally conductive case 6.

[0036] As described above, the coil component 1 has a thermally conductive layer 4, which is in contact with the busbar 3. Furthermore, the thermally conductive layer 4 is in contact with the outer peripheral surface 2b of the coil 2 and other surfaces at its bottom surface 4a, which is the surface opposite to the top surface 4b that is in contact with the busbar 3. By making the busbar 3 hotter than the coil 2, a temperature gradient is formed in which the coil 2 is cooler than the busbar 3. Therefore, the thermally conductive layer 4 and the coil 2 can serve as a heat dissipation path 9 that dissipates heat from the busbar 3, and the busbar 3 is prevented from becoming too hot. By preventing the busbar 3 from becoming too hot, it is possible to supply a large current to the coil component 1.

[0037] Furthermore, this coil component 1 has a thermally conductive layer 4 interposed between the coil 2 and the bus bar 3, which is often wired aerial above the coil 2, and the coil 2, which is the basic component of the coil component 1, serves as the heat dissipation path 9, so no special structure is required to dissipate heat from the bus bar 3. This makes it possible to prevent the coil component 1 from becoming larger.

[0038] Although the heat dissipation path 9 downstream of the coil 2 includes the sealing resin 7 and the thermally conductive case 6, this is not limiting. For example, a cooling sheet separate from the thermally conductive layer 4 in contact with the bus bar 3 may be provided on the outer peripheral surface 2c of the coil 2, and the heat of the bus bar 3 transferred to the coil 2 may be absorbed by the cooling sheet. This cooling sheet may be replaced with a coolant. Alternatively, the sealing resin 7 may be a molded resin that covers the outer peripheral surface 2b of the coil 2, except for the upper surface 2f that is in contact with the thermally conductive layer 4, and the heat of the bus bar 3 may be transferred from the coil 2 to the molded resin, and the heat may be dissipated from the resin.

[0039] Fig. 8 is a cross-sectional view showing another configuration of the coil device 1. As shown in Fig. 8, this coil device 1 has one coil 2. Fig. 9 is a perspective view showing a cross section of the conductive wire 21 drawn out from the coil 2 and the bus bar 3. The cross-sectional area S3 of the bus bar 3 is smaller than the cross-sectional area S2 of the conductive wire 21 that forms the coil 2.

[0040] As shown in Figures 8 and 9, this bus bar 3 is wide to increase the heat dissipation area from the bus bar 3 to the thermal conduction layer 4, but is thin-walled, and its cross-sectional area S3 is smaller than the cross-sectional area S2 of the conductive wire 21 that forms the coil 2.

[0041] Even in the case where one coil 2 is provided, by making the cross-sectional area S3 of the busbar 3 smaller than the cross-sectional area S2 of the conductive wire 21 that forms the coil 2, the temperature gradient of the busbar 3 is higher than that of the coil 2, and the coil 2 serves as a heat dissipation path 9 that dissipates heat from the busbar 3. From the viewpoint of having the coil 2 function as the heat dissipation path 9, the cross-sectional area S3 of the busbar 3 may be made smaller than the cross-sectional area S2 of the coil 2 by narrowing the width of the busbar 3.

[0042] In other words, even when one busbar 3 is shared by multiple coils 2, the cross-sectional area S3 of the busbar 3 can be made smaller than the total cross-sectional area S2 of the multiple shared coils 2, allowing the coil 2 to function as a heat dissipation path 9 for dissipating heat from the busbar 3.

[0043] As described above, this coil component 1 includes a coil 2 formed by winding a conductive wire 21, a bus bar 3 connected to the coil 2, and a heat dissipation path 9 that dissipates heat from the bus bar 3. The heat dissipation path 9 includes a thermally conductive layer 4 and the coil 2. The thermally conductive layer 4 contacts the bus bar 3 and also contacts the surface of the coil 2 on the side opposite to the contact surface with the bus bar 3, absorbing heat from the bus bar 3 and dissipating the heat from the bus bar 3 to the coil 2. The coil 2 receives heat from the bus bar 3 from the thermally conductive layer 4. This allows for enhanced heat dissipation from the bus bar 3 while minimizing size, resulting in a coil component with high heat dissipation properties.

[0044] Furthermore, this coil component 1 includes two or more coils 2, and the bus bar 3 is a common wiring for the multiple coils 2. This results in a temperature gradient that increases in the order of the bus bar 3, the thermally conductive layer 4, and the coil 2, making it easy to include the coil 2 in the heat dissipation path 9 of the bus bar 3.

[0045] In addition, in this coil component 1, the cross-sectional area S3 of the busbar 3 is smaller than the cross-sectional area S2 of the conductive wire 21 that forms the coil 2. This results in a temperature gradient that increases in the order of the busbar 3, the thermally conductive layer 4, and the coil 2, making it easier to include the coil 2 in the heat dissipation path 9 of the busbar 3.

[0046] Furthermore, the heat dissipation path 9 further includes a sealing resin 7 that covers part or all of the coil 2 and receives heat that has flowed from the bus bar 3 via the thermally conductive layer 4 and the coil 2. This allows the heat from the bus bar 3 that has flowed to the coil 2 to be further flowed to the sealing resin 7, preventing the coil 2 from becoming too hot, and allowing the heat dissipation path 9 to function efficiently.

[0047] The coil component 1 further includes a thermally conductive case 6 that houses the coil 2, and a sealing resin 7 that covers part or all of the coil 2. The heat dissipation path 9 further includes the thermally conductive case 6 and the sealing resin 7. The sealing resin 7 receives heat that flows from the bus bar 3 via the thermally conductive layer 4 and the coil 2, and the thermally conductive case 6 absorbs the heat of the bus bar 3 that is conducted between the thermally conductive layer 4, the coil 2, and the sealing resin 7. This allows the heat of the bus bar 3 that flows to the coil 2 to flow further to the sealing resin 7 and the thermally conductive case 6, preventing the coil 2 from becoming too hot, and allows the heat dissipation path 9 to function efficiently.

[0048] The above-described embodiments of the present invention are presented as examples, and the present invention is not limited to the above-described embodiments. The above-described embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the scope of the invention. The embodiments and their modifications are included in the scope of the present invention. [Explanation of symbols]

[0049] 1 Coil parts 11 Coil component body 2 coils 21 Conductive wire 2a reel 2b Outer surface 2c Inner surface 2d end face 2e leader line 2f top surface 2g Opposite side 3 Busbar 3a Bottom 3b Fastening hole 4. Thermal Conduction Layer 4a Bottom 4b Top surface 5 cores 51 Core mold resin 6 Thermal Conduction Case 6a Bottom 7 Sealing resin 8 Terminal block 81 Nut 82 Terminal block mold resin 83 volts 9 Heat dissipation path

Claims

1. a coil formed by winding a conductive wire; a bus bar connected to the coil; a heat dissipation path for dissipating heat from the bus bar; Equipped with The heat dissipation path is a thermally conductive layer that contacts the bus bar and also contacts a surface of the coil on the opposite side to the contact surface with the bus bar, absorbs heat from the bus bar, and dissipates heat from the bus bar to the coil; the coil receiving heat from the bus bar from the thermally conductive layer; containing, A coil component characterized by:

2. Two or more of the coils are provided, the bus bar is a common wiring for the plurality of coils; The coil component according to claim 1 ,

3. a cross-sectional area of ​​the bus bar is smaller than a cross-sectional area of ​​the conductive wire forming the coil; The coil component according to claim 1 ,

4. the heat dissipation path further includes a sealing resin that covers a part or all of the coil and receives heat that has flowed from the bus bar via the thermally conductive layer and the coil; 4. The coil component according to claim 1, wherein:

5. a thermally conductive case that accommodates the coil; a sealing resin that covers a part or all of the coil; Further provided with the heat dissipation path further includes the thermal conduction case and the sealing resin; the sealing resin receives heat flowing from the bus bar via the thermally conductive layer and the coil; the thermally conductive case absorbs heat from the bus bar that has been conducted through the thermally conductive layer, the coil, and the sealing resin; 4. The coil component according to claim 1, wherein:

6. a core including a magnetic material and on which the coil is mounted; 4. The coil component according to claim 1, wherein:

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