Electrical apparatus

Abstract

To provide a structure for improving heat dissipation by potting for a capacitor mounted on a printed circuit board.SOLUTION: In an electrical device 1 including a first printed circuit board 2, a case 6 that houses the first printed circuit board 2, and a capacitor 5 mounted on the first printed circuit board 2, the case 6 is provided with a main container 7 that houses the capacitor 5 and is filled with a potting material 9, an adjusting container 8 that is filled with the potting material 9, and a wall portion 11 that separates the main container 7 and the adjusting container 8. The wall part 11 is provided with a slit 12, and the main container 7 and the adjusting container 8 are communicated with each other through the slit 12. Thus, the potting material 9 can flow between the main container 7 and the adjustment container 8 through the slit 12.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an electrical device having a heat dissipation structure using potting, and more particularly to heat dissipation from a capacitor mounted on a printed circuit board. [Background technology]

[0002] Potting is a technology known as potting, which protects electronic components from vibration and improves heat dissipation by filling parts of electrical equipment with resin, etc. For example, Patent Document 1 discloses a method for improving the heat dissipation of smoothing capacitors installed in power conversion equipment by potting using a resin with high thermal conductivity.

[0003] A capacitor element that becomes a smoothing capacitor mainly consists of a capacitance element, an element case that houses it, and potting resin that fills the gap between the two. When this capacitor element is installed in the housing of a power conversion device, the potting resin is pushed out and overflows from the element case. Therefore, in Patent Document 1, a reservoir is provided inside the housing to receive the overflowing potting resin, thereby ensuring the amount of potting resin to be filled. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 7426315 Public Relations Summary of the Invention [Problem to be solved by the invention]

[0005] 2 shows a configuration for improving the heat dissipation of an electrolytic capacitor 25 directly mounted on a first printed circuit board 22 of an electric device 21, with reference to the potting method disclosed in Patent Document 1. The electric device 21 is, for example, a power conversion device.

[0006] In general, power conversion devices often have a drive board mounted with a DC smoothing electrolytic capacitor and a circuit for generating control signals for a power module (such as a field effect transistor), and a metal board mounted with a heat-generating power module and closely attached to a case to dissipate the heat. In electrical device 21 of Fig. 2, a first printed circuit board 22 corresponding to the drive board and a second printed circuit board 23 corresponding to the metal board are provided separately and connected by connectors 24a and 24b.

[0007] When assembling this electrical device 21, first, potting material 29 is filled into container 27 provided in case 26, which serves as the housing, and then connector 24a of first printed circuit board 22 is fitted into connector 24b of second printed circuit board 23 while inserting electrolytic capacitor 25 into container 27 so that it is immersed in potting material 29. At this time, potting material 29 that is pushed out by electrolytic capacitor 25 and overflows from container 27 flows into reservoir 32.

[0008] During such assembly work, there are cases where the connectors 24a, 24b do not fit together properly, and the first printed circuit board 22 must be pulled up and the fitting must be redone. However, the potting material 29 that has flowed into the reservoir 32 does not return to the container 27. Therefore, depending on the amount of potting material 29 that overflows from the container 27, the amount of potting material 29 filled in the container 27 may be insufficient, which may result in a deterioration in heat dissipation.

[0009] This problem does not occur if wall 31 and reservoir 32 are not provided. However, since variations in size and mounting height (such as mounting slightly above the board) cannot be ignored for electronic components mounted on a printed circuit board, it becomes necessary to increase the size of container 27 to accommodate these variations. Increasing the size of container 27 increases the gap between electrolytic capacitor 25 and case 26, and the potting material 29, which has a lower thermal conductivity than case 26, increases on the heat dissipation path, thereby worsening heat dissipation.

[0010] As described above, the challenge in electrical equipment is to improve the heat dissipation of components that vary widely, while also maintaining a consistent amount of potting material filled even after reassembly. [Means for solving the problem]

[0011] The present invention was devised in consideration of the above-mentioned problems of the conventional art, and one aspect thereof is an electrical device comprising a first printed circuit board, a case that houses the first printed circuit board, and a capacitor mounted on the first printed circuit board, wherein the case comprises a main container that houses the capacitor and is filled with potting material, an adjustment container that is filled with potting material, and a wall that separates the main container and the adjustment container, wherein a slit is formed in the wall, and the main container and the adjustment container are in communication with each other via the slit.

[0012] According to a preferred aspect of the present invention, the slit extends in the depth direction of the main container, and the end of the slit on the bottom side of the main container is below the liquid level of the potting material filled in the main container and the adjustment container before the capacitor is accommodated.

[0013] According to another preferred embodiment, the device further comprises a second printed circuit board housed in the case, and the connector of the first printed circuit board and the connector of the second printed circuit board are fitted together.

[0014] According to another preferred embodiment, the second printed circuit board includes a power module, and the first printed circuit board generates a control signal for the power module. [Effects of the Invention]

[0015] According to the above-described aspects of the present invention, in an electrical device, it is possible to improve the heat dissipation performance of components that vary widely, and to maintain a constant amount of potting material filled even after reassembly. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a schematic configuration diagram for explaining an electric device 1 according to a first embodiment of the present invention. [Figure 2] FIG. 1 is a schematic configuration diagram for explaining an electric device 21 according to the prior art. DETAILED DESCRIPTION OF THE INVENTION

[0017] A first embodiment of an electrical device having a heat dissipation structure using potting according to the present invention will be described in detail below with reference to the drawings.

[0018] [Example 1] FIG. 1 is a schematic diagram illustrating an electrical device 1 according to a first embodiment of the present invention. The electrical device 1 is a power conversion device, and includes a case 6 serving as a housing, and a first printed circuit board 2 and a second printed circuit board 3 housed in the case 6. The first printed circuit board 2 is a drive board, and directly mounts an electrolytic capacitor 5. The second printed circuit board 3 is a metal board, and mounts a heat-generating power module (not shown), such as a field-effect transistor. The second printed circuit board 3 is fixed to the case 6, and the power module is in close contact with the case 6 for heat dissipation. A connector 4a provided on the first printed circuit board 2 is mated and fixed to a connector 4b provided on the second printed circuit board 3.

[0019] The case 6 includes a main container 7 and a regulation container 8 that are provided adjacent to each other, and a wall 11 that separates the main container 7 from the regulation container 8. The main container 7 and the regulation container 8 are filled with a potting material 9 made of resin to improve heat dissipation, and the electrolytic capacitor 5 is housed in the main container 7 so that the lower end side is immersed in the potting material 9 inside the main container 7.

[0020] The wall 11 has a thin slit 12 penetrating the wall 11 in the thickness direction. The slit 12 extends in the vertical direction (depth direction of the main container 7) from the upper edge of the wall 11 (the end on the side of the first printed circuit board 2) toward the bottom of the main container 7. The lower end of the slit 12 (the end toward the bottom of the main container 7) is located at a predetermined position below the liquid level 10 of the potting material 9 before the electrolytic capacitor 5 is housed. In other words, the main container 7 and the adjusting container 8 are in communication with each other via the slit 12, and the potting material 9 can flow between the main container 7 and the adjusting container 8 via the slit 12. Therefore, the height of the liquid level 10 of the potting material 9 is always the same in the main container 7 and the adjusting container 8.

[0021] The main container 7 is filled with potting material 9, and the electrolytic capacitor 5 is inserted into the main container 7 so that it is immersed in the potting material 9, while the connector 4a of the first printed circuit board 2 is mated with the connector 4b of the second printed circuit board 3. At this time, the potting material 9 extruded into the electrolytic capacitor 5 flows from the main container 7 through the slit 12 in the wall 11 into the adjustment container 8.

[0022] If the connectors 4a, 4b do not mate well and the mating work needs to be redone, the potting material 9 flows from the adjustment container 8 through the slit 12 in the wall 11 into the main container 7 when the first printed circuit board 2 is pulled up.

[0023] The total amount of potting material 9 filled in the main container 7 and the adjustment container 8 is greater than the amount that can be filled in the main container 7 alone, and a sufficient amount of potting material 9 is filled to absorb variations in the height of the liquid surface 10 of the potting material 9 (variations in the amount of potting material 9 adhering to the electrolytic capacitor 5) caused by variations in the size of the electrolytic capacitor 5 and variations in the height position when mounted on the first printed circuit board 2 (the degree of floating from the first printed circuit board 2).

[0024] Furthermore, because the main container 7 and the conditioning container 8 are in communication with each other via the slit 12, the height of the liquid surface 10 of the potting material 9 is the same inside both the main container and the conditioning container. Furthermore, even if the fitting work of the connector 4a of the first printed circuit board 2 and the connector 4b of the second printed circuit board 3 needs to be redone during assembly of the electrical device 1, this does not affect the height of the liquid surface 10 of the potting material 9 after final assembly. This is because even if the potting material 9 is pushed out of the main container 7, it only flows into the conditioning container 8 via the slit 12 and does not flow out to the outside of the case 6, and can also flow from the conditioning container 8 back to the main container 7 again via the slit 12.

[0025] This makes it possible to stabilize the performance and quality of the electrical device. Furthermore, by designing the shape and size of the main container 7 to match the shape and size of the electrolytic capacitor 5, the gap between the electrolytic capacitor 5 and the case 6 can be reduced, and the amount of potting material 9 contained in the heat dissipation path can be reduced, thereby improving heat dissipation.

[0026] The wall 11 provided between the main container 7 and the adjustment container 8 also contributes to ensuring the mechanical strength of the case 6.

[0027] Although only the specific examples of the present invention have been described above in detail, it will be apparent to those skilled in the art that various modifications and alterations are possible within the scope of the technical idea of ​​the present invention, and it is natural that such modifications and alterations fall within the scope of the claims.

[0028] For example, in the first embodiment, the electric device 1 is a power converter, but the present invention is not limited to this and can be applied to any electric device that includes a substrate on which a capacitor is mounted. [Explanation of symbols]

[0029] 1. Electrical equipment 2...First printed circuit board 3...Second printed circuit board 4a, 4b...Connector 5...Electrolytic capacitor 6. Case 7...Main container 8…Adjustment container 9...Potting material 10…Liquid level 11...Wall part 12...Slit 21...Electrical equipment 22...First printed circuit board 23...Second printed circuit board 24a, 24b...connectors 25...Electrolytic capacitor 26…Case 27…Container 29...Potting material 31...Wall part 32...Reservoir

Claims

1. An electrical device comprising: a first printed circuit board; a case that houses the first printed circuit board; and a capacitor mounted on the first printed circuit board, the case includes a main container that houses the capacitor and is filled with a potting material, an adjustment container that is filled with a potting material, and a wall that separates the main container from the adjustment container; An electrical device characterized in that a slit is formed in the wall portion, and the main container and the adjustment container communicate with each other through the slit.

2. The slit extends in the depth direction of the main container, The electrical device according to claim 1, characterized in that the end of the slit on the bottom side of the main container is below the liquid level of the potting material filled in the main container and the adjustment container before the capacitor is accommodated.

3. a second printed circuit board housed in the case; 2. The electrical device according to claim 1, wherein the connector of the first printed circuit board and the connector of the second printed circuit board are fitted together.

4. the second printed circuit board includes a power module; 4. The electrical device according to claim 3, wherein the first printed circuit board generates a control signal for the power module.

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