JPH11354373A - Capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize a capacitor, by preventing reduction of the pressure inside a sealed metal package of the capacitor due to the change of the temperature around the capacitor. SOLUTION: A capacitor has a sealed metal package 14 in which a capacitor element 8 is housed and an electrical insulation oil 12 in which the capacitor element 8 is immersed within the capacitor sealed metal package 14, and a foaming elastic body 11 is provided between the capacitor element 8 and the capacitor sealing metal package 14. This can protect the change of the pressure inside the capacitor sealing metal package 14 which occurs due to the expansion and shrinkage of the electrical insulation oil 12 caused by the change of the temperature around the capacitor, and a lot of bubbles within the foamed elastic body 11 stand a vacuum due to the immersion process of the electrical insulation oil 12 without bursting. Also prevention of reduction of the pressure inside the capacitor sealing metal package 14 enables prevention of reduction of a corona start voltage to prevent occurrence of dielectric breakdown even at high temperatures.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a condenser for a microwave oven mainly used in a voltage doubler rectifier circuit.

[0002]

2. Description of the Related Art As a prior art, FIG. 7 is a sectional view showing a structure of a general capacitor. 7, 1 is a terminal fitting, 2 is a terminal cup, 3 is a terminal rod, 4 is a metal cover, 5 is a packing rubber, 6 is an insulating plate, 7 is a discharge resistor, 8 is a capacitor element, and 9 is metal. Case, 10
Denotes an insulating package, 12 denotes an electric insulating oil, and 13 denotes a lead piece. In this conventional capacitor, a capacitor element 8 is arranged in a capacitor-sealed metal container sealed by a metal lid 4 and a metal case 9, and the inside of the capacitor-sealed metal container is impregnated with an electric insulating oil 12.

As another prior art, FIG. 8 is a sectional view showing the structure of a capacitor disclosed in Japanese Patent Application No. 60-35770. 8, 1 is a terminal fitting, 2 is a terminal cup, 3 is a terminal rod, 4 is a metal cover, 5 is packing rubber, 6 is an insulating plate, 7 is a discharge resistor, 8 is a capacitor element, and 9 is metal. Case 10, insulating packaging, 21 is a hollow sealed molded product, 12 is an electrical insulating oil, 13
Is a lead piece. This conventional capacitor has, in addition to the configuration of FIG. 6, one hollow sealed molded product 21 in a capacitor sealed metal container sealed with a metal lid 4 and a metal case 9.

[0004]

There have been various problems when a capacitor having the above configuration is used. First, in the above-described conventional technique, when the ambient temperature of the capacitor becomes higher than room temperature, the electric insulating oil 12 expands. Then, the pressurized pressure expands the capacitor-sealed metal container. Thereafter, when the capacitor is cooled to room temperature or lower, the electric insulating oil 12 contracts. However, the metal container sealed with the capacitor is not completely restored to the original state and is deformed. As a result, a phenomenon has occurred in which the internal pressure of the metal container closed with the capacitor is reduced. When the pressure inside the capacitor-sealed metal container is reduced, there is a problem that the corona discharge starting voltage, which greatly affects the life of the capacitor, is remarkably reduced, resulting in dielectric breakdown of the capacitor.

[0005] Further, by utilizing the technique known in Japanese Patent Application No. 60-35770, the expansion of the electric insulating oil 12 caused by the above-mentioned problem that the ambient temperature of the capacitor becomes higher than room temperature is reduced. The expansion of the capacitor-sealed metal container can be suppressed by the contraction of the hollow hermetically sealed product 21 provided in the capacitor-sealed metal container.
However, the expansion of the metal container closed with the condenser occurs to a considerable extent. Thereafter, when the condenser is cooled to a room temperature or lower, the electric insulating oil 12 contracts. At this time, the pressure inside the capacitor-sealed metal container tends to decrease by an amount corresponding to the expansion of the capacitor-sealed metal container, but the hollow sealed molded product 21 provided in the capacitor-sealed metal container expands. As a result, it was possible to manufacture a capacitor that alleviated the pressure drop inside the metal container.

On the other hand, as a method of manufacturing the capacitor, it is general to provide a step of bringing the inside of the capacitor-sealed metal container into a high vacuum state in order to impregnate the capacitor element 8 with the electric insulating oil 12. However, in the configuration of the above-mentioned conventional technology, since the hollow sealed molded product 21 formed of one hollow portion is provided, the gas inside the molded product 21 expands greatly in the impregnation step, and the molded product 21 Sometimes burst and destroyed. The destruction of the molded article 21 causes the molded article 21
The gas leaked from the inside is diffused into the inside of the capacitor-sealed metal container, and penetrates into the inside of the capacitor element 8 or adheres to the end face of the capacitor element 8. Also, the molded product 21
There is also a problem that a fatal defect is caused in the capacitor element 8 due to the impact of the destruction. In order to solve the problem, it is conceivable to increase the thickness of the molded article 21,
In this case, there is a problem that the reversibility due to the temperature change is impaired and the pressure drop cannot be absorbed.

One hollow sealed molded product 21 is formed in a flat plate shape and disposed on the bottom surface of the capacitor-sealed metal container. As can be seen from FIG. Since the hollow sealed molded product 21 is formed to have almost the same area as the area, the hollow sealed molded product 21 inevitably expands and contracts to absorb a change in the internal pressure of the capacitor sealed metal container with respect to the height direction of the capacitor sealed metal container. Only done. Therefore, it is necessary to provide a space for this in the height direction, and there is a problem that the size is increased.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems, and to provide a compact and lightweight capacitor which prevents a pressure drop inside a capacitor-sealed metal container due to a change in the temperature around the capacitor.

[0009]

In order to achieve the above object, a capacitor according to a first aspect of the present invention includes a capacitor-sealed metal container containing a capacitor element, and an electric insulating oil impregnated in the capacitor-sealed metal container. Wherein a foamed elastic body is provided between the capacitor element and the capacitor-sealed metal container.

As described above, since the foamed elastic body is provided between the capacitor element and the capacitor-sealed metal container, a pressure change inside the capacitor-sealed metal container caused by expansion and contraction of the electric insulating oil due to a change in the ambient temperature of the capacitor. On the other hand, when the foamed elastic body expands and contracts reversibly, it is possible to prevent a pressure drop inside the metal container closed with the capacitor. In addition, since many bubbles inside the foamed elastic body can withstand without being ruptured even in a high vacuum state due to the electric insulating oil impregnating step in the capacitor manufacturing process, the gas inside the foamed elastic body is diffused. There is no. For this reason,
In a high vacuum state, gas does not permeate into the inside of the capacitor element or adhere to the end face of the capacitor element, so that the insulation performance of the capacitor element can be maintained. Also, by preventing the pressure inside the sealed metal container from dropping, it is possible to prevent the drop in the corona discharge starting voltage, which greatly affects the life of the capacitor. Can be provided.

According to a second aspect of the present invention, there is provided a capacitor according to the first aspect, wherein the foamed elastic body is formed in a flat plate shape and is disposed on the bottom surface of the capacitor-sealed metal container so as to secure a space where the foamed elastic body can expand and contract. The bottom area of the flat elastic foam was made smaller than the bottom area of the capacitor-sealed metal container. As described above, the foamed elastic body is formed in a flat plate shape and is disposed on the bottom surface of the metal container, and the bottom area of the foamed elastic body is set so as to secure a space where the foamed elastic body can expand and contract. Since it was made smaller with respect to the bottom area of the closed metal container, in addition to the effect of claim 1,
The expansion and contraction directions of the foamed elastic body can be ensured not only in the height direction but also in the lateral direction. For this reason, the range in which the internal pressure of the condenser-sealed metal container can be changed is widened, and high-temperature use is possible, and the size can be reduced.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. FIG. 1A is a structural sectional view of a capacitor according to a first embodiment of the present invention.
(A) is a front view, (b) is the side view. As shown in FIG. 1, this capacitor has a capacitor sealed metal container 14 containing a capacitor element 8 and an electric insulating oil 12 impregnated in the capacitor sealed metal container 14.
The foamed elastic body 11 is provided between the capacitor element 8 and the capacitor-sealed metal container 14. As in the conventional case, the capacitor element 8 is formed by using paper or a plastic film as a dielectric and using a metal foil or a vapor-deposited metal as an electrode. The capacitor-sealed metal container 14 is sealed with a metal lid 4 and a metal case 9. The terminal fitting 1 is housed in a terminal cup 2 and is connected to an electrode of the capacitor element 8 by a terminal rod 3 and a lead piece 13. 7 is a discharge resistor. In addition, the capacitor element 8 is insulated packaging 1
The packing rubber 5 is interposed between the insulating plate 6 and the metal cover 4 provided on the top of the packing rubber 5.

The foamed elastic body 11 is formed in the shape of a flat plate and disposed on the bottom surface of the capacitor-sealed metal container 14, and expands and contracts reversibly in response to a pressure change inside the capacitor. Has the effect of mitigating changes. In this case, the foamed elastic body 11 is an independent foamed rubber formed of silicon, and has a number of closed cells inside. Further, the individual closed cells are very small and do not burst even in a high vacuum state in the impregnation step for impregnating the capacitor element 8 with the electric insulating oil 12.

Next, the operation of the capacitor configured as described above will be described. 2 and 3 show the first embodiment of the present invention.
FIGS. 3A and 3B are explanatory views of the operation of the capacitor according to the embodiment, wherein FIG. 3A is a front view and FIG. As shown in FIG. 2, when the ambient temperature of the capacitor becomes higher than room temperature, the electric insulating oil 1
2 expands. Along with this, the foamed elastic body 11 contracts due to the pressing force. Thus, the expansion of the metal container 14 can be suppressed. However, expansion of the condenser-sealed metal container 14 occurs at least.
Therefore, when the capacitor is cooled to room temperature or lower, as shown in FIG. 3, the electric insulating oil 12 contracts and the internal pressure of the capacitor-sealed metal container 14 tends to decrease by the amount of expansion of the capacitor-sealed metal container 14. However, the foamed elastic body 11 expands due to the decrease in the internal pressure. As a result, the pressure inside the metal container 14 closed with the condenser does not change compared to the initial pressure, so that a pressure drop can be prevented.

As described above, according to this embodiment, since the foamed elastic body 11 is provided between the capacitor element 8 and the capacitor-sealed metal container 14, the expansion of the electric insulating oil 12 due to a change in the ambient temperature of the capacitor. Since the foamed elastic body 11 reversibly expands and contracts in response to a pressure change inside the capacitor-sealed metal container 14 caused by contraction, it is possible to prevent a pressure drop inside the capacitor-sealed metal container 14. Further, since a large number of bubbles inside the foamed elastic body 11 can withstand without being ruptured even in a high vacuum state caused by the step of impregnating the electric insulating oil 12 in the manufacturing process of the capacitor, the gas inside the foamed elastic body 11 It does not spread. Therefore, in a high vacuum state, gas does not permeate into the inside of the capacitor element 8 or adhere to the end face of the capacitor element 8, and the insulation performance of the capacitor element 8 can be maintained. Also, by preventing the pressure inside the metal container 14 from lowering, it is possible to prevent a decrease in the corona discharge starting voltage, which greatly affects the life of the capacitor. Capacitors can be provided.

A second embodiment of the present invention will be described with reference to FIGS. FIG. 4 is a structural sectional view of a capacitor according to a second embodiment of the present invention, in which (a) is a front view,
(B) is a side view. As shown in FIG. 4, in this capacitor, as in the first embodiment, the foamed elastic body 11 is formed in a flat plate shape and arranged on the bottom surface of the capacitor-sealed metal container 14. The bottom area of the flat foamed elastic body 11 is made smaller than the bottom area of the capacitor-sealed metal container 14 so as to secure a space for expansion and contraction. In this case, the bottom area of the foamed elastic body 11 is formed to be 80% of the bottom area of the capacitor-sealed metal container 14.

Next, the operational effects of the first and second embodiments of the present invention and the prior art will be compared. FIG. 5 is a graph showing a decrease in internal pressure with respect to an ambient temperature in the first and second embodiments of the present invention, and FIG. 6 is a corona discharge starting voltage with respect to the ambient temperature in the first and second embodiments of the present invention. FIG. In the figure, a prototype is a conventional technique without a hollow hermetically sealed product, a prototype is a hollow hermetically molded product according to a conventional technique, a prototype is a first embodiment, and a prototype is a second embodiment. As shown in FIG. 4, it can be seen that in the second embodiment, as in the first embodiment, the internal pressure hardly decreases even when the ambient temperature increases. Further, as shown in FIG. 5, it can be seen that the corona discharge starting voltage does not decrease in the second embodiment even when the ambient temperature increases, as in the first embodiment. Table 1 shows the volume ratio of the capacitor container, and the prototype is set to 100%. According to this, the volume ratio of the second embodiment is smaller than that of the first embodiment, and the size can be reduced.

[0018]

[Table 1]

As described above, according to this embodiment, the bottom area of the foamed elastic body 11 is made smaller than the bottom area of the capacitor-sealed metal container so as to secure a space where the foamed elastic body 11 can expand and contract. Therefore, the expansion and contraction directions of the foamed elastic body 11 can be secured not only in the height direction but also in the lateral direction. For this reason, the range which can respond to the change in the internal pressure of the capacitor-sealed metal container 14 is widened, so that it can be used at a high temperature and the size can be reduced. Other configuration effects are the same as those of the first embodiment.

Although the result of using the independent foamed rubber of silicon has been described for the foamed elastic body 11, the same effect can be obtained as long as the material is excellent in oil resistance such as fluorine.

[0021]

According to the capacitor of the present invention, since the foamed elastic body is provided between the capacitor element and the metal container enclosing the capacitor, the capacitor sealing caused by expansion and contraction of the electric insulating oil due to a change in the ambient temperature of the capacitor. Since the foamed elastic body expands and contracts reversibly in response to a pressure change inside the metal container, it is possible to prevent a pressure drop inside the capacitor-closed metal container. In addition, since many bubbles inside the foamed elastic body can withstand without being ruptured even in a high vacuum state due to the electric insulating oil impregnating step in the capacitor manufacturing process, the gas inside the foamed elastic body is diffused. There is no. For this reason, in a high vacuum state, gas does not permeate into the inside of the capacitor element or adhere to the end face of the capacitor element, and the insulation performance of the capacitor element can be maintained. Also, by preventing the pressure inside the sealed metal container from dropping, it is possible to prevent the drop in the corona discharge starting voltage, which greatly affects the life of the capacitor. Can be provided.

According to a second aspect of the present invention, the foamed elastic body is formed in a flat plate shape and disposed on the bottom surface of the metal container closed with a capacitor, so as to secure a space where the foamed elastic body can expand and contract.
Since the bottom area of the flat foamed elastic body is made smaller than the bottom area of the capacitor-sealed metal container, the expansion and contraction direction of the foamed elastic body can be changed not only in the height direction but also in the horizontal direction. The direction can also be secured. For this reason,
The range capable of responding to changes in the internal pressure of the capacitor-sealed metal container is widened, enabling high-temperature use and miniaturization.

[Brief description of the drawings]

FIG. 1 is a structural sectional view of a capacitor according to a first embodiment of the present invention, in which (a) is a front view and (b) is a side view.

FIGS. 2A and 2B are operation explanatory diagrams when the ambient temperature of the capacitor according to the first embodiment of the present invention is high; FIG.
(B) is a side view.

FIGS. 3A and 3B are explanatory diagrams of an operation when the ambient temperature of the capacitor according to the first embodiment of the present invention is low; FIG.
(B) is a side view.

FIG. 4 is a structural sectional view of a capacitor according to a second embodiment of the present invention, in which (a) is a front view and (b) is a side view.

FIG. 5 is a graph showing an internal pressure according to the embodiment of the present invention.

FIG. 6 is a graph showing a corona discharge starting voltage according to the embodiment of the present invention.

7A and 7B are cross-sectional views of the structure of a conventional capacitor, wherein FIG. 7A is a front view and FIG. 7B is a side view.

FIG. 8 is a structural sectional view of another conventional capacitor, and FIG.
Is a front view, and (b) is a side view.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Terminal fitting 2 Terminal cup 3 Terminal rod 4 Metal lid 5 Packing rubber 6 Insulating plate 7 Discharge resistance 8 Capacitor element 9 Metal case 10 Insulating packaging 11 Foam elastic body 12 Electrical insulating oil 13 Lead piece 14 Capacitor sealed metal container

Claims (2)

[Claims] 1. A capacitor-sealed metal container accommodating a capacitor element, and an electrical insulating oil impregnated in the capacitor-sealed metal container, wherein a foamed elastic body is interposed between the capacitor element and the capacitor-sealed metal container. A capacitor provided. 2. The foamed elastic body is formed in a flat plate shape and is disposed on the bottom of the metal container with a capacitor. 2. The capacitor according to claim 1, wherein the size of the capacitor is smaller than a bottom area of the metal container.