JPH0546262Y2 - - Google Patents

Description

[Detailed explanation of the invention] (a) Purpose of the invention This invention relates to a molded capacitor whose inside is filled with insulating gas.

[Prior art] So-called wound capacitor elements, in which a plastic film is used as a dielectric and a metallized film on which a metal is deposited are stacked and wound, are used for electric power because they are non-polar and have low dielectric loss. used for. However, it is well known that when used under high voltage, corona discharge tends to occur at both ends of the winding.

By the way, there is a method for manufacturing a molded capacitor described in JP-A-60-72212, which aims to improve the corona discharge characteristics by retaining an insulating gas on both ends of the winding of a wound capacitor element.

This manufacturing method involves placing a capacitor element in a high-temperature vacuum tank, performing heat treatment and vacuum treatment, filling the treated capacitor element with an insulating gas, and embedding the capacitor element filled with the insulating gas in a molded resin. This method of manufacturing molded capacitors can be expected to cause a slight amount of insulating gas to remain in the uneven parts on both ends of the winding of the capacitor element, resulting in improved corona discharge characteristics compared to those in which the capacitor element is not filled with insulating gas. At the same time, it has the advantage of improving dielectric strength.

[Problems to be solved by the invention] However, in the method for manufacturing the molded capacitor described above, when embedding the capacitor element filled with insulating gas in the mold resin, there is a step in which the capacitor element is placed in the mold resin liquid. The insulating gas that had accumulated in the uneven parts on both ends of the winding of the capacitor element gains buoyancy from the molding resin liquid, and some of it flows out as bubbles in the molding resin liquid, and further hardens the molding resin liquid. When the reaction temperature is raised to proceed with the curing reaction, the remaining insulating gas is warmed and gains even greater buoyancy, forming bubbles in the molding resin liquid and further exiting, so that both ends of the winding of the capacitor element There is also the problem that it is difficult to expect that the insulating gas will remain in the uneven portions.

In addition, the phenomenon in which the SF ₆ gas filled during molding becomes bubbles in the mold resin liquid due to buoyancy and escapes to the outside is exacerbated as the curing temperature of the mold resin increases, and this phenomenon is important for improving corona discharge. There is a problem that it may have a negative impact.

Furthermore, the curing temperature of the mold resin (approximately 50℃~
There is a problem in that when the temperature is returned from 120°C to room temperature, the gas pressure of the insulating gas at the weak point in the dielectric strength decreases to below atmospheric pressure, which results in a decrease in the corona discharge starting voltage.

Furthermore, such a molded capacitor has the problem that when the ambient temperature becomes low, the gas pressure further decreases and the corona discharge starting voltage decreases, making it impossible to use it in cold regions.

Therefore, this invention aims to provide a molded capacitor that can improve the corona discharge characteristics by sealing insulating gas under positive pressure in the dielectric strength weak points around the edges of the metal thin film on both ends of the winding of a wound capacitor element. That is.

(b) Structure of the device [Means for solving the problem] In order to solve the above problem, this device has the following features:
In a wound type capacitor element in which band-shaped dielectric layers and electrode layers are alternately wound around a cylindrical bobbin, the outer circumferential surface of the cylindrical bobbin, excluding the lower end hole, is wound with a container, and each of the strip-shaped dielectric layers and electrode layers are wound separately facing both end surfaces. A gap is formed to surround the container, and the inside of the container and the hole of the cylindrical bobbin are filled with insulating gas, and when the container is molded with synthetic resin, the synthetic resin is flowed into the hole of the cylindrical bobbin and pressurized. By doing so, the insulating gas inside the container was sealed to a positive pressure state and molded into one piece.

[Function] When filling an insulating gas into the container surrounding the outer peripheral surface of the cylindrical bobbin except for the lower end hole of the wound capacitor element and the cylindrical bobbin, and molding the container with synthetic resin, When the synthetic resin liquid is injected around the container, the lower opening of the cylindrical bobbin is first sealed with the synthetic resin liquid, and the gas pressure at the time of filling the container and the cylindrical bobbin with the insulating gas increases. It can be enclosed in

Furthermore, as more synthetic resin liquid is injected around the container, the gravity of the injected synthetic resin liquid is applied to the free surface of the synthetic resin liquid formed at the bottom of the hole in the cylindrical bobbin, creating a pressurized state. , it is possible to further push the synthetic resin liquid upward and allow it to flow in, thereby increasing the gas pressure of the insulating gas in the container.

In addition, after filling the container with synthetic resin liquid, if the synthetic resin liquid is further injected while being pressurized by an external force, the pressurized injection force is applied to the free surface of the synthetic resin liquid, resulting in an even greater pressurized state. , the insulating gas is compressed, and the synthetic resin liquid enters the hole of the cylindrical bobbin while pushing the insulating gas upward into the hole of the cylindrical bobbin against the compression repulsion force. It is compressed by the amount of synthetic resin liquid that has entered, and the gas pressure of the insulating gas can be further increased.

When the gas pressure of the insulating gas in the container reaches a desired value, the insulating gas can be sealed in the container at a desired high pressure by reacting and curing the injected synthetic resin liquid while maintaining the pressurized state.

By sealing the insulating gas in the container at a desired high pressure, the corona discharge starting voltage at the weak point in the dielectric strength of the wound capacitor element can be increased according to Paschen's law. Starting voltage can be improved.

[Example] Hereinafter, the invention of the present application will be described as an example with reference to FIG.
This will be explained using FIG. Note that FIG. 1 is a sectional view of a molded capacitor, and FIG. 2 is a cutaway sectional view of a casting mold device used for manufacturing the molded capacitor.

The molded capacitor has a wound capacitor element 2 in which band-shaped dielectric layers and electrode layers are alternately wound around a cylindrical bobbin 1.The outer peripheral surface of the cylindrical bobbin 1, excluding the lower end hole, is wound with a container 2 at both ends. The container 3 and the holes of the cylindrical bobbin 1 are filled with an insulating gas, such as SF ₆ gas 6, and the container 3 is surrounded by a synthetic resin, such as a synthetic resin, for example. When molding with the epoxy resin 7, the epoxy resin 7 is flowed into the hole of the cylindrical bobbin 1 to create a pressurized state, thereby sealing the SF ₆ gas 6 in the container 3 to a positive pressure state and molding it integrally. This is what I did.

The SF ₆ gas 6 can be sealed in a positive pressure state in the container 3 by the following method.

First, the cylindrical bobbin 1 is used as the winding core of the wound capacitor element 2, and the outer peripheral surface of the wound capacitor element 2, excluding the lower end hole of the cylindrical bobbin 1, is placed in a container.
The winding type capacitor element 2 is surrounded by the winding capacitor element 2, and gaps are formed between each end face of the winding.

The container 3 is made up of a container body 3a and a lid 3b in order to accommodate the wound capacitor element 2, and has an inner diameter slightly larger than the outer diameter of the wound capacitor element 2, and has a flat surface on both ends of the wound. The inner dimension is set to a height that forms a gap between the two. The lid body 3b is fixed to the outer periphery of the lower end of the cylindrical bobbin 1 in a sealed state, and one lead wire 4a of the wound capacitor element 7 is inserted into the container body 3a to enable soldering and sealing. Eyelets 5a are attached. Furthermore, an eyelet 5b is attached to the cylindrical bobbin 1 to allow the other lead wire 4b of the wound capacitor element 2 to be inserted therethrough and sealed by soldering.

After attaching the lid 2b to the cylindrical bobbin 1 of the wound type capacitor element 2 and positioning and housing it in the container body 2a, the lid 1b is fixed in a sealed state, and the container body 2a and the cylindrical bobbin 1 are fixed. Eyelet 4a, 4
The lead wires 4a and 4b inserted through the part b are soldered to form a sealed state.

Next, this is housed in a mold 8 having an inner diameter larger than its outer diameter as shown in FIG. Then, the inside of the mold 10 is evacuated.

The air in the container 3 is degassed through the cylindrical bobbin, and the inside of the container 1 and the cylinder pipe 2 are drawn to a degree of vacuum of about 10 ^-2 mmHg.

Next, the valve 10 is closed and the valve 11 is opened to allow an insulating gas, for example, SF ₆ gas 6 to flow into the vacuum mold 8, thereby filling the hole of the cylindrical bobbin and the container 1 with SF ₆ gas 6. After that, mold 8 and container 1
An epoxy resin liquid 7' is injected between the two.

The epoxy resin liquid 7' is made by mixing an epoxy resin with an inorganic filler and having a density ρ of 1.3 grams/
Use the one from cc. When this epoxy resin liquid 7' is injected between the mold 8 and the container 1, first, the lower opening of the hole of the cylindrical bobbin 1 is filled with the epoxy resin liquid 7'.
The container 3 and the cylindrical bobbin 1 are sealed with SF ₆ gas 6 in their holes. Figure 2 depicts approximately this state. The sealed pressure of the SF ₆ gas 8 in this state is P _p [Torr], and this sealed pressure P _p can be determined as appropriate. When the epoxy resin liquid 7' is further injected and the space between the mold 8 and the container 3 is filled, the free surface of the synthetic resin liquid 7' formed at the bottom of the hole of the cylindrical bobbin is filled with the injected liquid. A pressurized state is created in which the gravity of the synthetic resin liquid 7' is applied. If the height of container 3 is 12 cm, the gravity applied to this free surface
P _h is approximately P _h = ρgh = 15288 [dyn/cm ² ], and this gravity P _h changes the gas pressure P _x of the SF ₆ gas 6 in the container 3 and the hole of the cylindrical bobbin from P _p to P The pressure is increased to _x = P _p + 0.015288 [Torr] and is balanced.
In this pressurized state where the space between the mold 8 and the container 3 is filled with the synthetic resin liquid 7', when the epoxy resin liquid 7' is further injected while being pressurized by an external force, the free surface is further filled with the epoxy resin liquid 7'. A pressurized state is created in which pressure from an external force is applied, and as a result, the SF ₆ gas 6 is compressed and pushed into the epoxy resin liquid 7'.
enters the hole in the cylindrical bobbin 1 in the upper direction, and the SF ₆ gas 6 inside is compressed by the amount of epoxy resin that has entered the hole in the cylindrical bobbin 1.
The gas pressure P _x of the SF ₆ gas 6 becomes a pressurized state that is further increased from P _p .

For example, the injection pressure of the epoxy resin liquid 7' is
The volume of ^the hole in ^the cylindrical bobbin ¹ is calculated by subtracting ^the volume of the wound capacitor element from the internal volume of the container. When set to half, the gas pressure P _x of SF ₆ gas in the container increases from (P _p +0.015288) Torr to approximately (1.2 + P _O +0.015288) Torr and (1.5 + P _O +0.015288) Torr, respectively. let

When the gas pressure of the SF ₆ gas 6 in the container 1 reaches a desired value, the injected epoxy resin liquid 7' is reacted and hardened while maintaining the pressurized state, and SF 6 gas ₆ is formed in the container 1.
Since the gas 6 can be sealed at a desired high pressure, the molded capacitor of this invention can be obtained by taking it out from the mold 8 and performing post-processing if necessary.

With P _p set to _0.3 Torr, molded capacitors with gas pressures _P Compared to the corona discharge onset voltage of the molded capacitor produced using the manufacturing method, corona discharge onset voltages that were 1.4 times, 1.9 times, and 2.4 times higher, respectively, were obtained.

(c) Effects of the invention The molded capacitor of this invention is made by flowing synthetic resin liquid for molding under pressure from the lower opening of the hole of the cylindrical bobbin into the container housing the wound type capacitor element. Since the insulating gas is sealed under positive pressure, the insulating gas can be densely interposed in the dielectric strength weak points on both ends of the winding of the wound capacitor element, improving the corona discharge starting voltage. It is something that can be done.

[Brief explanation of the drawing]

FIG. 1 is an end view of a molded capacitor in the embodiment, and FIG. 2 is a cutaway cross-sectional view of a casting mold device. 1: cylindrical bobbin, 2: wound capacitor element, 3: container, 3a: container body, 3b: lid, 4a, 4b: lead wires, 5a,
5b: Eyelets, 6: _SF6 gas, 7:
... epoxy resin, 7'... epoxy resin liquid, 8...
...mold, 9, 10, 11, 12...valves, 13...vacuum pump, 14...synthetic resin liquid tank, 15... _SF6 gas cylinder.

Claims (1)

[Scope of utility model registration request] In a wound type capacitor element in which band-shaped dielectric layers and electrode layers are alternately wound around a cylindrical bobbin, the outer circumferential surface of the cylindrical bobbin, excluding the lower hole, is wound with a container, and each layer is separately wound facing both end surfaces. Form a gap and surround it,
In addition, the inside of the container and the hole of the cylindrical bobbin are filled with insulating gas, and when the container is molded with synthetic resin, the synthetic resin is flowed into the hole of the cylindrical bobbin to create a pressurized state. A molded capacitor characterized by being integrally molded with insulating gas sealed under positive pressure.