JPH0726833Y2 - Mold capacitor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a molded capacitor whose inside is filled with an insulating gas.

[Prior Art and Problems Thereof] A wound-type capacitor element in which a plastic film is used as a dielectric layer and a metallized film having an electrode layer formed by vapor-depositing a metal on the plastic film is stacked and rolled up is non-polar. Although it has advantages such as low dielectric loss, it has a drawback that weak points of the insulator are easily generated on both end faces of the winding and corona discharge is likely to occur. In order to eliminate this drawback, the winding type capacitor element is housed in a container, the container is filled with an insulating gas, the circumference of the container is molded with a synthetic resin, and the container is sealed. In particular, there is an idea that the insulating gas atmosphere is applied to both end faces of the winding to improve the dielectric strength.

In order to realize this idea, it is necessary to first deaerate the air around the capacitor element in the container by evacuation and then replace it with insulating gas.Therefore, form a vent hole for air or insulating gas in the container. Need to be kept. The larger the ventilation hole, the better when circulating air or insulating gas. The smaller the ventilation hole, the better when the container is molded and sealed with synthetic resin to prevent the synthetic resin liquid from entering the container. Therefore, there is a problem that the concentration of the insulating gas cannot be sufficiently increased and that the mold resin flows into the container to reduce the dielectric strength.

During resin molding, when the synthetic resin liquid is filled around the container, a part of the synthetic resin liquid comes out as air bubbles from the vent due to the buoyancy of the insulating gas in the container, and the next synthetic resin Even when the liquid is heated and hardened, the buoyancy increases due to the thermal expansion of the insulating gas in the container, and the synthetic resin liquid is further bubbled out of the vent holes, causing the insulating gas in the container to be diluted. There is a problem.

Therefore, this invention intends to provide a molded capacitor capable of improving the corona discharge characteristics by sealing the insulating gas in a positive pressure state around the wound capacitor element.

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a strip-shaped dielectric layer on a tubular bobbin in a container in which a tube communicating with an outer space is provided in an inner bottom portion of the container. And the electrode layer are alternately stacked and wound, and the wound type capacitor element is housed by inserting the tube into the hole of the cylindrical bobbin, filling the inside of the container and the tube with an insulating gas, and surrounding the container. When molding with a synthetic resin, the synthetic resin is made to flow into the tube to be in a pressurized state so that the insulating gas in the container is hermetically sealed in a positive pressure state.

[Operation] When the container is molded and sealed with a synthetic resin, the synthetic resin liquid is injected around the container, and insulation is provided inside the container and the tubular bobbin when the lower end opening of the tube comes into contact with the synthetic resin liquid. The gas can be sealed at the gas pressure at the time of filling the insulating gas.

Further, when the synthetic resin liquid was further injected, the free surface of the synthetic resin liquid generated in the lower part of the tube was pushed upward according to the height of the injected synthetic resin liquid surface, and then flowed in and flowed in. It is also possible to increase the gas pressure by compressing the insulating gas in the container by the amount of the synthetic resin liquid.

Also, if it is desired to increase the gas pressure of the insulating gas in the container, applying an external force to the synthetic resin liquid injected around the container pushes the free surface of the synthetic resin liquid in the tube further upward. As a result, the gas pressure of the insulating gas in the container can be further increased.

The insulating gas filled in the container and the tube is compressed by pushing the free surface of the synthetic resin liquid upward into the tube from the time when the lower opening of the tube is covered with the synthetic resin liquid and sealed. Can be prevented from leaking.

When the gas pressure of the insulating gas in the container reaches a desired value, the injected synthetic resin liquid is cured by reaction while maintaining the pressurized state, whereby the insulating gas can be sealed in the container at a desired positive pressure. .

In this case, the amount of the synthetic resin liquid to be injected is sufficient as long as the insulating gas can be sealed in the container, and the entire surface around the container does not necessarily have to be covered.

Since the insulating gas can be sealed at a desired high pressure in the container, the corona discharge starting voltage at the weak point of the dielectric strength of the wound capacitor element can be increased according to the Paschen rule, and the corona discharge starting voltage of the molded capacitor of the present invention can be increased. Can be improved.

Embodiments 1 to 4 Hereinafter, the invention of the present application will be described with reference to FIGS. 1 to 3 of the drawings. FIG. 1 is a sectional view of a molded capacitor for explaining an embodiment, FIG. 2 is a characteristic diagram, and FIG. 3 is a cutaway sectional view of a casting mold apparatus used for manufacturing the molded capacitor.

A container 3 for accommodating the wound-type capacitor element 2 is prepared. The container 3 is composed of a container body 3a located on the upper side and a lid body 3b located on the lower side, has an inner diameter slightly larger than the outer diameter of the wound capacitor element 2, and faces both end faces of the winding. The inner dimension of the height that forms a gap in each is set, and the container body 3a and the lid 3b are provided with eyelet terminals 4a, 2a, 2b for pulling out the lead wires 2a, 2b of the winding type capacitor element 2 to the outside. 4b is provided, and a tube 3c communicating with the outer space is provided at the inner bottom portion of the lid 3b, which is the inner bottom portion of the container 3.

Next, in this container 3, a winding type capacitor element 2 formed by alternately winding a band-shaped dielectric layer and an electrode layer on a cylindrical bobbin 1 is wound, and a tube 3c is inserted into a hole portion of the cylindrical bobbin 1. To accommodate. At this time, the lead wire of the winding type capacitor element 2
2a and 2b are soldered to the eyelet terminals 4a and 4b, respectively, and if necessary, further sealed with a sealing material and pulled out to the outside.

In this way, the wound-type capacitor element 2 is housed in the container 3 and set in a mold 8 having an inner diameter larger than the outer diameter of the container 3, as shown in FIG. Valve 8,
The valves 10 and 11 are closed, the valve 9 is opened, the vacuum pump 12 is operated, and the inside of the mold 7 is vacuum deaerated. The air in the container 3 is degassed through the hole of the tube 3c inserted into the cylindrical bobbin 1, and the inside of the container 1 and the tube 3c are pulled to a vacuum degree of about 10 ^-2 mmHg.

Then, the valve 9 is closed and the valve 10 is opened to allow an insulating gas, for example, SF ₆ gas 5 to flow into the vacuum mold 7 to fill the container 3 and the tube 3c with the SF ₆ gas 5. That S
When the filling pressure of the F ₆ gas 5 is P _O [atm], for example, P _O is 1.0
Atm (Example 1), 1.2 atm (Example 2), 1.5 atm (Example 3), and 1.8 atm (Example 4) are filled. The filling pressure P _O of the SF ₆ gas 5 can be set to a desired value when setting the gas pressure of the insulating gas 5 in the container 3.

After that, valves 9 and 10 are closed and valve 11 is opened, and the mold 7
The epoxy resin liquid 6 ′ is injected between the container 3 and the container 3. The epoxy resin liquid 6'uses, for example, an epoxy resin mixed with an inorganic filler and having a density ρ of 1.3 grams / cc.
When this epoxy resin liquid 6'is poured between the mold 7 and the container 3, first, the lower opening of the tube 3c is sealed when it comes into contact with the epoxy resin liquid 7 ', and the inside of the container 3 and the tube 3 are closed. SF ₆ gas 6 can be enclosed in the 3c hole. FIG. 3 illustrates almost this state. When the epoxy resin liquid 6'was further injected, the synthetic resin liquid 6'injected onto the free surface of the synthetic resin liquid 6'generated in the lower portion of the hole of the cylindrical bobbin 1 was in a pressurized state to which gravity was applied. Become. Assuming that the height of the injected epoxy resin liquid 6 ′ surface is hcm, the gravity P _h applied to the free surface in the tube 3c is P _h = ρgh / 10 ⁶ [atm]. The P _h is the increased pressure of the pressurized insulating gas in the container 3 and the tube 3c.

Assuming that the height h of the epoxy resin liquid 6'side is the height of the molded capacitor, that is, h = 12 cm, SF ₆ gas 5 in the container 3
The gas pressure P _{X of} is P _X = P _O + P _H = P _O + 1.3 × 980 × 12 ÷ 10 ⁶ ≈P _O +0.015 [atm].

Incidentally, FIG. 3 shows a state in which the epoxy resin liquid 6'has risen to about 60% of the height of the molded capacitor.

When the gas pressure P _X of the SF ₆ gas 5 in the container 3 is raised to a desired value, the injected epoxy resin liquid 6 ′ is cured while maintaining the pressurized state, and the epoxy resin around the container 3 is cured. 6 mold layers are formed. This can be taken out of the mold 7 and subjected to post-processing if necessary to obtain the molded capacitor of the present invention.

When P _O is set to 1.0 atm, the gas pressure P _X of SF ₆ gas 5 in the container 3 is 1.0.
Molded capacitor of 15 atm (Example 1), P 2 _O of 1.2 atm
To the gas pressure P _X of SF ₆ gas 5 in the container 3 is molded capacitor 1.215Atm (Example 2), the gas pressure P _X of SF ₆ gas 5 in the container 3 to the P _O to 1.5atm is 1.515atm Molded capacitor (Example 3), P 6 _O 8 atm and SF _{6 in} container 3
A molded capacitor (Example 4) having a gas pressure P _{X of} gas 5 of 1.815 atm was prepared.

[Comparative Example] As a comparative example, the conditions are the same as those of the example except that the lid of the container has a closed structure and pores for degassing air and filling SF ₆ gas 5 are provided in the upper part of the container main body. Molded capacitor molded under _O at 1.0 atm (Comparative Example 1), P _O at 1.2 atm
Molded capacitor molded below (Comparative Example 2), P _O
There mold capacitor (Comparative Example 3) were molded under 1.5 atm, P _O creates the molded mold capacitors (Comparative Example 4) under 1.8 atm.

The corona discharge inception voltage of the mold capacitors of Examples 1 to 4 and Comparative Examples 1 to 4 was measured, and the relative values are shown in FIG. 2 based on the corona discharge inception voltage of the mold capacitor of Comparative Example 1.

[Effect of the Invention] The molded capacitor of the present invention is a wound-type capacitor element in which a synthetic resin liquid for molding is introduced under pressure from a lower opening of a tube communicating with an outer space provided in an inner bottom portion of a container. Since the insulating gas is sealed in a positive pressure state in the container that accommodates the insulating gas, it is possible to interpose the insulating gas at high density in the weak points of the dielectric strength of both ends of the winding type capacitor element, and start corona discharge. The voltage can be improved.

[Brief description of drawings]

1 shows a cutaway sectional view of a molded capacitor in an embodiment, FIG. 2 shows a characteristic view of the embodiment and a comparative example, and FIG. 3 shows a cutaway sectional view of a casting mold apparatus. 1 ... Cylindrical bobbin, 2 ... Winding type capacitor element, 2a, 2b ...
Lead lines, 3 ... Container, 3a ... Container body, 3b ... Lid, 3c ... Tube, 4a, 4b ... Eyelets, 5 ... SF ₆ gas, 6 ... Epoxy resin, 6 '... Epoxy resin liquid, 7 ... Gold Mold, 8, 9, 10, 11 ... Valve, 12 ... Vacuum pump device, 13 ... Synthetic resin liquid tank, 14 ... SF ₆ gas cylinder.

Claims (1)

[Scope of utility model registration request] 1. A wound-type capacitor element comprising a cylindrical bobbin and a strip-shaped dielectric layer and an electrode layer which are alternately laminated and wound in a container having a tube communicating with the outer space at the inner bottom of the container. A tube is inserted into the hole of the cylindrical bobbin to be housed, the container and the tube are filled with insulating gas, and when the container is molded with a synthetic resin, the synthetic resin flows into the tube to be in a pressurized state. As a result, the molded capacitor is characterized in that the insulating gas in the container is sealed in a positive pressure state.