Electrical equipment

Abstract

To remove noise occurring from electronic components preferably.SOLUTION: An electric device 10 has: a housing 11; electronic components 20 disposed within the housing 11; and a cooling solvent 30 filling the housing 11. The cooling solvent 30 contains soft magnetic particles 40.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an electrical device.

Background Art

[0002] Patent Document 1 describes an electrical device including a housing, a circuit board disposed inside the housing, and an insulating liquid refrigerant filled inside the housing. Electronic components are mounted on the circuit board. The electronic components are immersed in the insulating liquid refrigerant. By immersing the electronic components in the insulating liquid refrigerant, heat generated from the electronic components is transmitted to the insulating liquid refrigerant and dispersed. Thereby, a local temperature rise of the electrical device is suppressed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in recent years, in electrical devices having electronic components, it has been required to suitably remove noise generated from the electronic components.

Means for Solving the Problems

[0005] The electrical device that achieves the above object is an electrical device having a housing, electronic components disposed inside the housing, and a cooling solvent filled inside the housing, wherein the electronic components are immersed in the cooling solvent, and the cooling solvent contains soft magnetic particles.

[0006] In the electrical device that achieves the above object, the soft magnetic particles have an insulating coating. In the electrical device that achieves the above object, the soft magnetic particles are surface-modified. The electrical device that achieves the above object has the soft magnetic particles containing ferrite.

Advantages of the Invention

[0007] According to the electrical device of the present invention, noise generated from electronic components can be suitably removed.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0009] Hereinafter, an embodiment embodying the present invention will be described with reference to the drawings. As shown in FIG. 1, the electrical device 10 has a housing 11, electronic components 20 disposed inside the housing 11, and a cooling solvent 30 filled inside the housing 11. The electronic components 20 are immersed in the cooling solvent 30. The cooling solvent 30 contains soft magnetic particles 40.

[0010] Since the cooling solvent 30 contains the soft magnetic particles 40, noise generated from the electronic components 20 can be suitably removed. Specific examples of the electrical device 10 are not particularly limited, and examples thereof include a DC-DC converter, an inverter, a charger, and the like.

[0011] Hereinafter, each component of the electrical device 10 will be described. <Housing 11> As shown in FIG. 1, the housing 11 has a rectangular plate-shaped bottom wall 12. The bottom wall 12 is rectangular, having a pair of short sides 12a and a pair of long sides 12b. The housing 11 has rectangular plate-shaped side walls 13 extending upward from each side of the bottom wall 12. Specifically, it has a pair of first side walls 13a extending upward from the pair of short sides 12a of the bottom wall 12 and a pair of second side walls 13b extending upward from the pair of long sides 12b of the bottom wall 12. That is, the bottom wall 12 and the side walls 13 constitute a bottomed cylindrical case main body 15 having an opening in one direction. In FIG. 1, for the sake of convenience, the second side wall 13b on the front side is omitted.

[0012] The housing 11 has a rectangular plate-shaped top wall 14 at the upper ends of the first side walls 13a and the second side walls 13b. The housing 11 has a vertically long box-shaped outer shape, in other words, it is composed of a vertically long hollow rectangular parallelepiped. The top wall 14 has a function as a lid, and by attaching the top wall 14 to the case main body 15 so as to cover the opening of the case main body 15, the inside of the housing 11 is sealed.

[0013] The materials of the bottom wall 12, the side walls 13, and the top wall 14 of the housing 11 are not particularly limited, and for example, they can be made of metal. Specific examples of the metal include, for example, aluminum, aluminum alloy, stainless steel, etc.

[0014] <Electronic component 20> As shown in FIG. 1, the electronic component 20 is disposed inside the housing 11 in a state of being mounted on a circuit board 21.

[0015] The circuit board 21 is not particularly limited, and a known circuit board 21 can be used. Examples of the known circuit board 21 include a plate material in which a conductive path is formed by a printed wiring technique on a mounting surface of an insulating board made of an insulating material. The size of the circuit board 21 is configured to be smaller than the second side wall 13b of the housing 11.

[0016] The electronic component 20 is not particularly limited, and known electronic components 20 used in the electric device 10 can be used. Specific examples of the electronic component 20 include, for example, resistors, coils, capacitors, fuses, relays, diodes, ICs (Integrated Circuits), FETs (Field Effect Transistors), and the like. The electronic component 20 may be used as a switching element.

[0017] As shown in FIG. 2, the electronic component 20 is mounted on both the first mounting surface, which is the mounting surface on one side of the circuit board 21, and the second mounting surface, which is the mounting surface on the other side located on the side opposite to the first mounting surface. The circuit board 21 on which the electronic component 20 is mounted is inserted into the housing 11 from the upper part of the housing 11, that is, from the opening of the case main body 15, and is attached to the bottom wall 12. In the state of being attached to the bottom wall 12, the circuit board 21 and the electronic component 20 are in a state with a predetermined interval between the first side wall 13a, the second side wall 13b, and the top wall 14.

[0018] <Cooling solvent 30> As shown in FIGS. 1 and 2, the cooling solvent 30 is filled inside the housing 11. Specifically, the cooling solvent 30 is filled between the inner circumference of the housing 11 and the circuit board 21 on which the electronic component 20 is mounted. The entire electronic component 20 is immersed in the cooling solvent 30. By attaching the top wall 14 to the case main body 15, leakage of the cooling solvent 30 from the housing 11 is suppressed.

[0019] Since the electronic component 20 in the housing 11 is immersed in the cooling solvent 30, the heat generated from the electronic component 20 can be transmitted to the cooling solvent 30. The heat transmitted to the cooling solvent 30 is released through the housing 11. Thereby, a local temperature rise of the electric device 10 can be suppressed.

[0020] The cooling solvent 30 is not particularly limited, and known cooling solvents 30 used for cooling the electric device 10 can be used. The cooling solvent 30 is preferably a solvent having no conductivity.

[0021] Specific examples of the cooling medium 30 include, for example, perfluorocarbon, hydrofluoroether, hydrofluoroketone, fluorine-inert liquid, silicone oil, mineral oil, hydrocarbon refrigerant, and the like. The above cooling medium 30 may be used alone or in combination of two or more.

[0022] The cooling medium 30 is also called a refrigerant, a liquid refrigerant, a cooling medium, a refrigerant liquid, a coolant, etc. <Soft magnetic particles 40> As shown in FIG. 1, the cooling medium 30 contains soft magnetic particles 40. The soft magnetic particles 40 are dispersed in the cooling medium 30.

[0023] Here, the soft magnetic particles 40 mean particles that become magnets when a magnetic field is applied and do not become magnets when no magnetic field is applied. The average particle diameter of the soft magnetic particles 40 is not particularly limited, but is preferably 0.01 μm or more, more preferably 0.1 μm or more, and even more preferably 1 μm or more. Also, it is preferably 50 μm or less, more preferably 30 μm or less, and even more preferably 20 μm or less.

[0024] When the average particle diameter of the soft magnetic particles 40 is 50 μm or less, it becomes easy to disperse in the cooling medium 30. When the average particle diameter of the soft magnetic particles 40 is 0.01 μm or more, the handleability of the soft magnetic particles 40 is improved.

[0025] The method for measuring the average particle diameter of the soft magnetic particles 40 is not particularly limited, and for example, it can be measured on a volume basis using a known laser diffraction particle size distribution measuring device. The type of the soft magnetic particles 40 is not particularly limited, and known soft magnetic particles 40 can be adopted. Examples of the known soft magnetic particles 40 include ferrite which is iron oxide, pure iron, Fe-Si based alloy which is silicon steel, Fe-Ni based alloy which is permalloy, Fe-Co based alloy which is permendur, Fe-Si-Al based alloy such as sendust, Fe-Si-Cr based alloy, Fe-Cr-Al based alloy, amorphous metal such as Fe-based amorphous, and the like.

[0026] The soft magnetic particles 40 may be formed by using one kind of the above types alone, or may be formed by using a combination of two or more kinds. Among these, since ferrite is a material with relatively low conductivity, it is preferable that the soft magnetic particles 40 are formed using ferrite.

[0027] In the cooling solvent 30, one kind of soft magnetic particles 40 may be dispersed, or a plurality of kinds of soft magnetic particles 40 may be dispersed. The content of the soft magnetic particles 40 in the cooling solvent 30 is not particularly limited, but it is preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more with respect to the total mass of the cooling solvent 30 combined with the soft magnetic particles 40. Also, it is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less.

[0028] The soft magnetic particles 40 preferably have an insulating film. By having the insulating film on the soft magnetic particles 40, it is possible to suppress the occurrence of a short circuit between the electronic components 20 and the circuit board 21 in the housing 11.

[0029] The insulating film preferably covers 50% or more of the surface area of the soft magnetic particles 40. That is, the coverage rate is preferably 50% or more. The coverage rate is more preferably 70% or more, still more preferably 90% or more, and most preferably 100%. The coverage rate of the insulating film can be determined by observing the surfaces of a plurality of soft magnetic particles 40 with an electron microscope and calculating the average value of the coverage rate.

[0030] The thickness of the insulating film is not particularly limited, but is preferably 5 nm or more, more preferably 10 nm or more, and still more preferably 20 nm or more. Also, it is preferably 200 nm or less, more preferably 150 nm or less, and still more preferably 100 nm or less. The thickness of the insulating film can be determined, for example, by depth direction analysis using Auger electron spectroscopy combined with sputtering.

[0031] The type of the insulating film is not particularly limited, and a known insulating film used as an insulating film for magnetic particles can be adopted. Examples of the known insulating film include an oxide film, a nitride film, an aluminum oxynitride film, and the like.

[0032] Specific examples of the oxide film include, for example, aluminum oxide, magnesium oxide, titanium oxide, zirconium oxide, silicon oxide, iron oxide, potassium oxide, sodium oxide, calcium oxide, chromium oxide, and the like.

[0033] Specific examples of the nitride film include, for example, boron nitride, silicon nitride, and the like. The insulating film may be used alone of one of the above types, or may be used in combination of two or more types.

[0034] The method for forming the insulating film is not particularly limited, and a known method can be adopted. For example, a method of mixing the soft magnetic particles 40 and the raw material of the insulating film using a ball mill or the like, that is, a method of forming by so-called mechanical alloying can be used. It can also be formed by chemical vapor deposition or physical vapor deposition.

[0035] The soft magnetic particles 40 are preferably surface-modified. Here, the surface modification means introducing an organic functional group onto the surface of the soft magnetic particles 40 to modify the surface of the soft magnetic particles 40. By modifying the surface of the soft magnetic particles 40, for example, hydrophobicity or insulating properties can be imparted. By imparting hydrophobicity, the dispersibility of the soft magnetic particles 40 in the cooling solvent 30 can be improved. By imparting insulating properties, the occurrence of a short circuit between the electronic component 20 and the circuit board 21 can be suppressed.

[0036] The surface modification can be performed using a known surface modifier. Specific examples of the surface modifier include, for example, silane-based coupling agents, titanium-based coupling agents, phosphorus-based coupling agents, carboxylic acids, alkylamines, grafting of polymers, etc. Note that the grafting of a polymer means graft-polymerizing a polymer onto the surface of the soft magnetic particles 40 to form a polymer layer.

[0037] The above surface modifiers may be used alone or in combination of two or more. The method of surface modification is not particularly limited, and a known method can be adopted. For example, it can be performed by dissolving or dispersing the surface modifier in a solvent in advance and then mixing it with the soft magnetic particles 40 for a certain period of time. Also, the presence or absence of surface modification can be confirmed, for example, by measuring the infrared spectrum using a Fourier transform infrared spectrometer.

[0038] The surface modification may be performed on the insulating film of the soft magnetic particles 40. That is, the surface modification may be performed on the insulating film. <Other components> The cooling solvent 30 may contain components other than the soft magnetic particles 40. Examples of the components other than the soft magnetic particles 40 include surfactants, chelating agents, silicone resins, etc.

[0039] <Arrangement configuration of each component of the electrical device 10> As shown in FIGS. 1 and 2, a circuit board 21 on which electronic components 20 are mounted is disposed in the housing 11 while being attached to the bottom wall 12. The circuit board 21 and the electronic components 20 are spaced apart from the first side wall 13a, the second side wall 13b, and the top wall 14 of the housing 11 by a predetermined distance. Also, a plurality of electronic components 20 mounted on the circuit board 21 are spaced apart from each other by a predetermined distance.

[0040] Since the circuit board 21 and the electronic components 20 are disposed at a predetermined distance as described above, heat generated from the electronic components 20 can be efficiently transferred to the cooling solvent 30 existing around the electronic components 20. Also, since the cooling solvent 30 that has received heat is likely to move by convection, it is easy to suppress a local temperature rise.

[0041] <Function and Effect> The operation of this embodiment will be described. When electromagnetic waves penetrate into the soft magnetic particles 40, the soft magnetic particles 40 have an action of converting the electromagnetic waves into heat. That is, the electromagnetic waves can be attenuated by an action called so-called magnetic loss. Therefore, when the cooling solvent 30 contains the soft magnetic particles 40, noise as electromagnetic waves generated from the electronic components 20 can be absorbed. Thereby, the noise can be suitably removed. Note that suitably removing the noise does not only mean completely absorbing the noise, but also means absorbing the noise to such an extent that it does not interfere with the use of the electric device 10.

[0042] In order to suitably remove the noise, it is conceivable to attach an electromagnetic wave shielding material around the housing 11. However, attaching an electromagnetic wave shielding material around the housing 11 may lead to an increase in the size of the electric device 10. On the other hand, in the electric device 10 of this embodiment, since the soft magnetic particles 40 contained in the cooling solvent 30 can absorb the noise, there is no need to attach an electromagnetic wave shielding material.

[0043] The effect of this embodiment will be described. An electric device 10 having a housing 11, electronic components 20 disposed inside the housing 11, and a cooling solvent 30 filled inside the housing 11, wherein the electronic components 20 are immersed in the cooling solvent 30, and the cooling solvent 30 contains soft magnetic particles 40.

[0044] Since the electronic components 20 disposed inside the housing 11 are immersed in the cooling solvent 30, heat generated from the electronic components 20 can be transmitted to the cooling solvent 30. Thereby, a local temperature rise of the electric device 10 can be suppressed. Further, since the cooling solvent 30 contains the soft magnetic particles 40, noise as electromagnetic waves generated from the electronic components 20 can be suitably removed. Since there is no need to attach an electromagnetic wave shielding material, it is possible to contribute to miniaturization of the electric device 10.

[0045] (2) The soft magnetic particles 40 have an insulating film. Therefore, it is possible to suppress the occurrence of a short circuit between the soft magnetic particles 40 and the electronic components 20 or the circuit board 21. (3) The soft magnetic particles 40 are surface-modified. By surface-modifying to impart hydrophobicity, the dispersibility of the soft magnetic particles 40 can be improved. Further, by surface-modifying to impart insulating properties, it is possible to suppress the occurrence of a short circuit between the soft magnetic particles 40 and the electronic components 20 or the circuit board 21 inside the housing 11.

[0046] (4) The soft magnetic particles 40 contain ferrite. Since ferrite is a material having a relatively low conductivity, it is possible to suitably suppress the occurrence of a short circuit between the soft magnetic particles 40 and the electronic components 20 inside the housing 11.

[0047] <Modified Example> This embodiment can be implemented with the following modifications. This embodiment and the following modified examples can be implemented in combination with each other within a technically non-conflicting range.

[0048] In this embodiment, the entire electronic component 20 was immersed in the cooling solvent 30, but the present invention is not limited to this mode. At least a part of the electronic component 20 may be in a state of being immersed in the cooling solvent 30.

[0049] In this embodiment, the housing 11 was configured as a vertically long rectangular parallelepiped, but the present invention is not limited to this mode. The housing 11 may be a horizontally long rectangular parallelepiped, a cube, or a cylindrical shape.

[0050] In this embodiment, the circuit board 21 was attached to the bottom wall 12 of the housing 11, but the present invention is not limited to this mode. The circuit board 21 may be attached to the side wall 13 of the housing 11 or the top wall 14.

[0051] In this embodiment, the electronic component 20 was disposed inside the housing 11 in a state of being mounted on the circuit board 21, but the present invention is not limited to this mode. The electronic component 20 may be directly mounted on the side wall 13, the bottom wall 12, or the top wall 14 of the housing 11. That is, the inside of the side wall 13, the bottom wall 12, or the top wall 14 may also serve as the circuit board 21.

[0052] In this embodiment, the cooling solvent 30 was sealed inside the housing 11, but the present invention is not limited to this mode. The cooling solvent 30 may be configured to cool the electronic component 20 while circulating outside the housing 11. That is, the electric device 10 may be provided with a circulation type cooling device.

Explanation of Reference Numerals

[0053] 10... Electric device, 11... Housing, 12... Bottom wall, 12a... Short side, 12b... Long side, 13... Side wall, 13a... First side wall, 13b... Second side wall, 14... Top wall, 15... Case main body portion, 20... Electronic component, 21... Circuit board, 30... Cooling solvent, 40... Soft magnetic particles.

Claims

1. An electrical device comprising a housing, electronic components disposed inside the housing, and a cooling solvent filled inside the housing in a sealed state without circulating outside the housing, wherein the electronic components are immersed in the cooling solvent, and the cooling solvent contains soft magnetic particles.

2. The electrical device according to Claim 1, wherein the soft magnetic particles have an insulating film.

3. The electrical device according to Claim 2, wherein the insulating film is surface-modified with an organic functional group.

4. The electrical device according to any one of Claims 1 to 3, wherein the soft magnetic particles contain ferrite.

5. The electrical device according to Claim 3, wherein the insulating film is imparted with hydrophobicity by the surface modification.

6. The electrical device according to any one of Claims 1 to 3, wherein the content of the soft magnetic particles in the cooling solvent is 20% by mass or more and 80% by mass or less with respect to the total mass of the cooling solvent including the soft magnetic particles.

7. The housing includes a bottomed cylindrical case main body and a lid covering an opening of the case main body, and a sealed structure is formed by attaching the lid to the case main body, the electronic components are disposed on a circuit board attached to one side wall of the case main body, and a predetermined interval is provided between the circuit board and the other side wall of the case main body and the lid. The electrical device according to any one of Claims 1 to 3.

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