JP6705339B2 - Film capacitor - Google Patents

Description

The present invention relates to a film capacitor in which a film capacitor element is housed in a case.

For example, a film capacitor having high withstand voltage and excellent temperature characteristics and frequency characteristics is applied to an inverter circuit for vehicles. Conventional film capacitors are generally of a winding type formed by winding a metallized film or a laminated type formed by laminating metallized films.

For example, for a film capacitor element formed by winding a metallized film, metallikon electrodes (metal sprayed parts) are formed on the two electrode extraction surfaces at both ends of the film capacitor element, and the metallikon electrodes are connected via a solder layer or the like. A bus bar (external lead-out terminal) is attached, and the whole structure is roughly configured. Here, the metallized film is formed by depositing a metal vapor deposition film on one side of the dielectric film, and two metallized films are laminated to form a set (two metallized film pairs). A film capacitor element is formed by winding a pair of metallized films.

A film capacitor element with a metallikon electrode and a bus bar formed on both ends is housed in a case, and a film resin element is embedded in the case to form a film capacitor element. It is possible to prevent the moisture (humidity) from entering the inside of the film capacitor element via the metallikon electrode.

This will be described with reference to FIG. In FIG. 4, the film capacitor FC has a film capacitor element F having a metallikon electrode M and a bus bar B at both ends housed in a case C, and a sealing resin body P is formed in the case C to form the film capacitor element F. The entire structure is formed by embedding and projecting a part of the bus bar B to the outside of the sealing resin body P.

In the figure, moisture in the air penetrates inside along the interface between the inner wall surface of the case C and the sealing resin body P, and enters inside the film capacitor element F through the metallikon electrode M. Follow the moisture permeability path in the X direction. Since the outer film exists on the peripheral surface of the film capacitor element F, the route from the outside air to the film capacitor element F through the inside of the sealing resin body P is generally not a moisture permeable path.

Therefore, in order to ensure a high moisture-proof capability, the distance t from the upper end of the sealing resin body P to the upper end of the film capacitor element F is made longer, in other words, the depth of the case C is made as deep as possible, By increasing the volume of the sealing resin body P, particularly the volume of the sealing resin body P above the film capacitor element F, it is necessary to increase the path length of the moisture permeable path X shown in FIG.

However, by increasing the depth of the case C and increasing the volume of the sealing resin body P, the size and weight of the film capacitor FC are increased, and the distance from the upper surface of the film capacitor element F to the outside air is increased. A new problem may occur such that the heat dissipation performance decreases.

Here, in Patent Document 1, a capacitor element in which a metallized film is wound or laminated is housed in a case, and a gel-like silicone material is injected as a filler into a space between the capacitor element and the case to form a gel-like material. A film capacitor in a case is disclosed in which the upper surface of a silicone material is sealed with urethane resin.

JP, 10-326721, A

According to the film capacitor with the case disclosed in Patent Document 1, even if the capacitor element is largely destroyed when an excessive surge voltage is applied, the conductor is not scattered and the safety thereof can be improved. I'm going to do it.

However, even when the case-included film capacitor disclosed in Patent Document 1 is applied, it is not possible to obtain a film capacitor having a high moisture-proof capability without increasing the above-mentioned problem, that is, increasing the size and weight of the film capacitor.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a film capacitor having excellent moisture resistance and heat dissipation without increasing the size and weight.

In order to achieve the above object, a film capacitor according to the present invention is an element set including a film capacitor element, a metallikon electrode formed on two electrode extraction surfaces of the film capacitor element, and a bus bar attached to the metallikon electrode. A solid body, a case accommodating the element assembly, and a sealing resin body formed in the case for embedding the element assembly, and a part of the bus bar of the sealing resin body. In the film capacitor extending to the outside, an endless projecting portion is provided on the inner wall of the case above the element assembly at a position above the element assembly.

In the film capacitor of the present invention, the inner wall of the case in which the element assembly is housed and the encapsulating resin body is formed has an endless convex portion projecting inside the case at a position above the element assembly. By being provided, since the moisture permeable path length can be lengthened by this convex portion, it is possible to obtain a high moisture proof capacity without increasing the depth of the case and increasing the volume of the sealing resin body. It is possible. Therefore, the moisture-proof ability of the film capacitor can be enhanced without increasing the size and weight of the film capacitor.

Here, the endless convex portion is, for example, when the case is a rectangular parallelepiped having an opening upward, is a convex portion of a rectangular shape in plan view which is continuous along each inner wall of the four side surfaces of the rectangular parallelepiped, In the case of a cylinder or an elliptic cylinder having an opening at the top, it means a circular or elliptical convex portion in plan view which is continuous along the inner wall of the cylindrical side surface or the elliptic cylinder side surface.

Here, the number of endless protrusions provided on the inner wall of the case may be one or may be two or more at intervals. By providing two or more convex portions, the moisture permeable path length along the inner wall of the case can be further lengthened, and a film capacitor having a higher moisture proof capacity can be obtained.

The inner wall of the case is provided with an endless convex portion at a position higher than the element assembly, so that the moisture-proof ability of the film capacitor is enhanced, and the heat from the film capacitor element is generated in the convex portion. It becomes easier to convey the heat, and the heat dissipation of the film capacitor can be improved. This is because the distance between the convex portion and the film capacitor element is shortened because the convex portion projects inside the case, and heat easily flows from the film capacitor element to the convex portion.

With regard to this heat dissipation, the endless convex portion lengthens the moisture-permeable path to enhance the moisture-proof ability, so that the thickness of the sealing resin body above the element assembly can be reduced ( Since it is not necessary to secure the moisture permeable path length by the thickness of the resin stopping body), the distance between the upper surface of the element assembly and the outside air may be short, which also improves the heat dissipation.

By the way, it is preferable that the longer the protruding length of the convex portion to the inside of the case is, the longer the moisture permeation path length becomes.However, if the protruding length of the convex portion is too long, when the element assembly is arranged in the case. In addition, the element assembly may interfere with the convex portion and may not be arranged.

However, in such a case, a configuration in which the convex portion is attached to the inside of the case is adopted, the element assembly is housed in the case, and in some cases, the sealing resin body is attached to the convex portion mounting position on the inner wall of the case. After the formation, the endless convex portion is attached to the inner wall of the case afterwards, whereby a film capacitor having a convex portion having a long protruding length toward the inside of the case can be obtained.

As can be understood from the above description, according to the film capacitor of the present invention, in the inner wall of the case in which the element assembly is housed and the sealing resin body is formed, the endless shape is provided at a position higher than the element assembly. Since the convex part that protrudes inside the case is provided, the convex part can increase the moisture-permeable path length, and the case can be deepened to increase the volume of the sealing resin body. Without, and thus without increasing the size and weight of the film capacitor, it can have a high moisture barrier capacity. Further, the sealing resin body above the film capacitor element is thin, and the distance between the film capacitor element and the case (convex portion) is short, so that excellent heat dissipation can be achieved.

1 is a vertical sectional view of a first embodiment of a film capacitor of the present invention. It is a II-II arrow line view of FIG. It is a longitudinal cross-sectional view of Embodiment 2 of the film capacitor of the present invention. It is a longitudinal cross-sectional view of an embodiment of a conventional metallized film capacitor.

Embodiments of the film capacitor of the present invention will be described below with reference to the drawings. The planar shape of the illustrated film capacitor and the case which is the constituent member thereof is a rectangle, but the planar shape may be a film capacitor having various planar shapes such as a square shape, a circular shape, an elliptical shape, and the like. As the endless convex portion provided, a linear one corresponding to the planar shape of the case is applied.

(Embodiment 1 of film capacitor)
1 is a vertical cross-sectional view of Embodiment 1 of the film capacitor of the present invention, and FIG. 2 is a view taken along the line II-II of FIG.

The film capacitor 100 shown in FIG. 1 includes an element assembly 10, a case 20 in which the element assembly 10 is housed, and a sealing resin body 30 which is formed in the case 20 and in which the element assembly 10 is embedded. It is configured.

The element assembly 10 includes a film capacitor element 1, a metallikon electrode 2 formed on two electrode extraction surfaces of the film capacitor element 1, and a bus bar 3 attached to the metallikon electrode 2, A part of the bus bar 3 extends outside the sealing resin body 30.

The film capacitor element 1 is composed of two kinds of metallized films (not shown), and each of the metallized films is composed of a dielectric film and a metal evaporated film having a non-evaporated slit and an insulating margin. By laminating these two types of metallized films so that both insulation margins do not match in the laminating direction to form a pair of metallized films, by laminating or winding the pair of metallized films, The film capacitor element 1 is formed.

Here, the dielectric film is formed of polypropylene (PP), polyphenylene sulfide (PPS), polyvinylidene fluoride (PVDF), or the like. The metal vapor deposition film is formed by vapor deposition of aluminum, zinc, or the like on the surface of the dielectric film.

The metallikon electrode 2 is formed by spraying aluminum, zinc, or the like, and an external lead terminal made of a plate-shaped bus bar 3 is connected to the metallikon electrode 2 via a solder layer (not shown).

The sealing resin body 30 is obtained by molding a resin such as an epoxy resin, a silicone resin, or a urethane resin in the case 20, and silica, alumina, boron nitride, or nitride as an insulating filler having a heat dissipation property to these resins. One of silicon, silicon carbide, magnesium oxide, talc, and clay, or a mixture of two or more of these is molded in the case 20.

The case 20 is made of aluminum, for example, and the case 20 in the illustrated example has a rectangular shape in a plan view and has a rectangular parallelepiped shape with an opening upward, and is composed of four side surfaces and a bottom surface.

At the position above the element assembly 10 on the inner wall of the case 20, there is provided an endless projection 20a projecting inside the case 20 as shown in FIG.

In the film capacitor 100, the inner wall of the case 20 is provided with the endless projecting portion 20a projecting inside the case 20 at a position higher than the element assembly 10. The path length of X1 can be increased. Therefore, unlike the conventional film capacitor FC shown in FIG. 4, a high moisture resistance is achieved without increasing the depth of the case to increase the volume of the sealing resin body, and thus without increasing the physique and weight of the film capacitor. You can gain the ability.

Furthermore, since the endless convex portion 20a is provided at a position above the element assembly 10 on the inner wall of the case 20, the distance between the film capacitor element 10 and the case 20 (the convex portion 20a thereof) is short. As a result, the heat from the film capacitor element 10 is easily transferred to the convex portion 20a (X2 direction), and the heat dissipation of the film capacitor 100 is also improved.

Regarding this heat dissipation property, the endless convex portion 20a lengthens the path length of the moisture permeable path X1 to enhance the moisture proof ability, so that the thickness t1 of the sealing resin body 30 above the element assembly 10 is reduced. Since the distance between the upper surface of the element assembly 10 and the outside air is shortened, heat dissipation from the upper surface of the element assembly 10 to the outside air (X3 direction) is promoted, and heat dissipation is also improved. ..

Therefore, the film capacitor 100 having excellent moisture-proof and heat-radiating properties can be obtained by providing the end wall-shaped convex portion 20a projecting inside the case 20 at a position above the element assembly 10 on the inner wall of the case 20. Become. Further, in the film capacitor 100, since the amount of the sealing resin body 30 used can be small, the manufacturing cost can be reduced, the physique can be made as small as possible, and the weight can be reduced.

By the way, it is preferable that the longer the protruding length of the convex portion to the inside of the case is, the longer the moisture permeation path length becomes. However, if the protruding length of the convex portion is too long and the convex portion extends right above the element assembly, for example. When attempting to arrange the element assembly in the case, the element assembly may interfere with the convex portion and cannot be arranged. However, in such a case, a configuration in which the convex portion is attached to the inside of the case is adopted, the element assembly is housed in the case, and in some cases, the sealing resin body is attached to the convex portion mounting position on the inner wall of the case. After the formation, the endless convex portion is attached to the inner wall of the case afterwards, whereby a film capacitor having a convex portion having a long protruding length toward the inside of the case can be obtained.

(Embodiment 2 of film capacitor)
FIG. 3 is a vertical sectional view of Embodiment 2 of the film capacitor of the present invention. The illustrated film capacitor 100A is one in which two endless convex portions 20a are provided at intervals on the inner wall surface of the case 20, and the other configuration is the same as that of the film capacitor 100.

By providing the two endless convex portions 20a, the path length of the moisture permeable path X1' can be made longer than the path length of the moisture permeable path X1, and the film capacitor further excellent in moisture resistance can be obtained.

(Analysis and results of verification of the amount of resin used to form the sealing resin body of the film capacitor and heat dissipation)
The present inventors modeled the film capacitor of the conventional structure shown in FIG. 4 (comparative example) and the film capacitor of the present invention shown in FIG. 1 (example) in a computer, and calculated the amount of resin for forming a sealing resin body. In addition, the maximum temperature of the film capacitor element was verified.

In this analysis, in both the comparative example and the example, the physical constitution of the film capacitor element was (3×3×1.5) cm ³ , the thickness of the case was 2 mm, the distance between the inner wall of the case and the film capacitor element was 2 mm, and the metallikon electrode The thickness was 1 mm and the generated loss was 2 W, and the thickness of the sealing resin body above the film capacitor elements in the comparative example and the example was set to 10 mm and 6 mm, respectively, from the viewpoint of having the same moisture resistance. The analysis was performed by thermofluid analysis (analysis software: SCRYU/TETRA). The analysis results are shown in Table 1 below.

From Table 1, it was found that the amount of resin for the encapsulating resin body of the example was about half that of the comparative example, and the maximum temperature of the film capacitor element was reduced by about 10%.

Although illustration is omitted, according to the thermo-fluid analysis result (temperature contour diagram) on the computer screen, in the comparative example, the heat dissipation from above the film capacitor element is caused by the large thickness of the sealing resin body above the film capacitor element. It was confirmed that the temperature was bad and the heat was easily trapped. On the other hand, in the example, it was confirmed that the heat dissipation from above the film capacitor element was good because the thickness of the sealing resin body above the film capacitor element was thin, and these results are reflected in the results of Table 1. It is believed that

Although the embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and there are design changes and the like within a range not departing from the gist of the present invention. However, they are included in the present invention.

DESCRIPTION OF SYMBOLS 1... Film capacitor element, 2... Metallicon electrode, 3... Bus bar, 10... Element assembly, 20... Case, 20a... Convex part, 30... Sealing resin body, 100, 100A... Film capacitor

Claims (1)

An element assembly comprising a film capacitor element, a metallikon electrode formed on two electrode extraction surfaces of the film capacitor element, and a bus bar attached to the metallikon electrode,
A case accommodating the element assembly,
A film capacitor, comprising: a sealing resin body formed in the case and burying the element assembly, wherein a part of the bus bar extends outside the sealing resin body,
On the inner wall of the case, two or more convex portions endlessly projecting inward of the case are provided at intervals above and below the upper end of the metallikon electrode of the element assembly. ,
The bus bar is a film capacitor formed in a flat plate shape and provided so as to extend upward along the metallikon electrode.

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