JPH0778729A - Vacuum capacitor - Google Patents

Abstract

PURPOSE:To obtain a vacuum capacitor, which can prevent its temperature rise at the time of current condition and at the same time, can prolong its life. CONSTITUTION:Fixed electrodes 5 are provided on the inside of a fixed conductor 3 provided at one end of a vacuum container 13 and with movable electrodes 6, which cross these electrodes 5, mounted on a movable conductor 8, an electrostatic capacity adjusting screw 9, which is rotatably supported by a cover body 4, is made to screw into this conductor 8 and a stainless steel bellows 14 and a copper bellows 15, which is used as a current conduction path, are provided between the conductor 8 and the cover body 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum capacitor.

[0002]

2. Description of the Related Art FIG. 5 is a cross-sectional structural view of a general variable type vacuum capacitor of this type. For example, a tubular portion is formed by a tubular ceramic 2 having copper flanges 1a and 1b on both ends. The cylindrical portion is closed by the fixed conductor 3 and the metal lid body 4 to form a vacuum container 13 for filling the high-proof vacuum dielectric. Inside the fixed conductor 3, a plurality of substantially cylindrical electrode plates having different inner diameters are concentrically provided at regular intervals to form a fixed electrode 5.
The movable electrode 6 is formed by a plurality of cylindrical electrode plates having different inner diameters which are inserted / removed in the respective electrode intervals in a non-contact state.
The movable electrode 6 is provided on the movable conductor 8.

The movable conductor 8 has a hollow lead portion 8a on the back side of the movable electrode 6, and the side surface of the hollow lead portion 8a is slidably supported by a bearing 7. A female screw portion 8b is formed on the inner wall of the end of the hollow lead portion 8a.
Reference numeral 9 denotes a capacitance adjusting screw, which includes a head portion 9a and a female screw portion 8
It is composed of a male screw portion 9b screwed with b. The capacitance adjusting screw 9 is supported by a support body formed in a substantially central portion of the lid body 4, that is, a screw receiving portion 10 and a thrust bearing 11 for reducing a rotation torque, and its head portion 9a is manually operated. Alternatively, the movable conductor 8 is moved up and down by rotating it using a motor or the like. As a result, the crossing area between the fixed electrode 5 and the movable electrode 6 changes, so that when the voltages of different polarities are applied to both electrodes 5 and 6, the value of the electrostatic capacitance generated between the electrodes 5 and 6 is continuous. Can be changed.

Reference numeral 12 is a bellows made of a soft metal, and one end of the bellows is joined to the inner wall of the lid 4 and the bearing 7 so that the movable conductor 8 and the movable electrode 6 can move up and down while keeping the vacuum container 13 airtight. In addition, the other end is joined to the movable conductor 8. There is also a structure in which the other end edge is joined to the surface of the hollow lead portion 8a. Since the hollow lead portion 8a and the bearing 7 that guides the hollow lead portion 8a are insulated by the lubricating oil,
Inside the vacuum vessel 13, the bellows 12 is energized. That is, the bellows 12 also serves as an energization path between the external power supply terminal (not shown) provided on the lid 4 and the movable electrode 6.

[0005]

By the way, the characteristics required for the vacuum capacitor include that the loss is low, the heat generation is small when energized, and the life is long. In the above-mentioned conventional vacuum capacitor, the material of the bellows 12 has a great influence on the above characteristics, and the material thereof is a copper-based material such as phosphor bronze or beryllium copper and SUS30.
There is a stainless steel type material such as 4L, but both have advantages and disadvantages, and it was not possible to satisfy the above required characteristics at the same time. For example, a stainless steel bellows has a longer life than a copper bellows, but its current-carrying ability is inferior, and heat generation during powering cannot be avoided. For this reason, in the past, although the problem of service life remains, phosphor bronze bellows, which has excellent current carrying capacity, has been mainly used.

The present invention has been made to solve the above problems, and an object thereof is to obtain a vacuum capacitor which can reduce heat generation during energization and has a long life.

[0007]

The vacuum capacitor according to the first aspect of the present invention is provided for forming a current-carrying path between the movable conductor and the other metal material and for keeping the inside of the vacuum container airtight. The bellows is composed of a stainless bellows and a copper bellows.

Further, in the vacuum capacitor according to the second aspect, the bellows which is provided between the movable conductor and the other metal material as a current-carrying path and which keeps the inside of the vacuum container airtight is composed of a stainless bellows. In addition, a copper strip or a silver strip is provided in parallel with the bellows.

[0009]

According to the first aspect of the present invention, the electric conduction between the movable conductor and the other metal material is performed by the copper bellows, and the electric conductivity of copper is higher than that of phosphor bronze. It Also, the life is the same as that of the stainless bellows alone, and the life is long.

In the second aspect, the electric current between the movable conductor and the other metal material is substantially performed by the copper strip or the silver strip, and the conductivity of these is larger than that of phosphor bronze. Heat generation is reduced. In addition, the life is the same as when using the stainless bellows alone, and the life is long.

[0011]

【Example】

Embodiment 1 Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Figure 1
1 is a vertical sectional view of the vacuum capacitor according to the first embodiment.
Reference numeral 4 denotes a cylindrical bellows made of stainless steel (for example, SUS304L) provided between the movable conductor 8, the bearing 7 and the lid body 4, and 15 denotes an outside of the stainless bellows 14 and the movable conductor 8, the bearing 7 and the lid body. 4 is a cylindrical bellows made of copper provided between the bellows. Other configurations are the same as the conventional one.

In the above structure, the bellows 14 and 15 keep the inside of the vacuum container 13 airtight and serve as a current-carrying path between the movable conductor 8 and the lid 4, but the power supply frequency is 13.56 MH.
_In the case of a vacuum capacitor having a capacitance of 500 PF and a capacitance of 500 PF, the relationship between the energizing current and the surface temperature is as shown in FIG. This is because the energization is mainly performed by the copper bellows 15 and the conductivity of phosphor bronze is about 10% of the conductivity of copper, so that heat generation is reduced. The life characteristics are as shown in FIG. 3, which is about 8 when the phosphor bronze bellows is used as 1. This is stainless steel (SUS3
(04L) This is similar to the case where the bellows is used alone, and the vacuum holding is mainly performed by the stainless bellows 14.

The operation as a vacuum capacitor is the same as the conventional one, the fixed electrode 5 is energized through the fixed conductor 3, and the movable electrode 6 is energized by the lid 4 and the copper bellows 1.
5 through the movable conductor 8 and the capacitance adjusting screw 9
The movable conductor 8 is moved up and down by the rotation of, and the electrostatic capacitance can be continuously changed by changing the crossing area of both electrodes 5, 6.

As described above, in the first embodiment, the copper bellows 15 is used.
The temperature rise can be reduced by energizing the vacuum capacitor, and the maximum allowable current of the vacuum capacitor can be increased accordingly, and when the vacuum capacitor is incorporated in the device, its cooling can be reduced or unnecessary. it can.
In addition, the vacuum of the vacuum container 13 is maintained by the stainless bellows 14.
By doing so, the life can be extended.

Embodiment 2 FIG. 4 is a vertical sectional view of a vacuum capacitor according to Embodiment 2, 16 is a movable conductor 8 outside the stainless bellows 14.
Is a strip-shaped copper strip connected between the lid 4 and the lid 4, and the other configurations are the same as those described above.

In the above structure, the relationship between the current flowing through the vacuum capacitor and the surface temperature is as shown in FIG.
The temperature rise will be lower than before. This is because energization is mainly performed by the copper strip 16, and the conductivity of phosphor bronze is less than that of copper.
Since it is about 0%, heat generation is reduced.
The life characteristics are also as shown in FIG. 3, which is equivalent to the case where the stainless bellows is used alone. this is,
This is because vacuum holding is mainly performed by the stainless bellows 14.

In the second embodiment, the temperature rise can be reduced by energizing the copper strip 16, and the same effect as in the first embodiment can be obtained. In addition, the same effect as that of the first embodiment can be obtained in extending the life. In addition, copper strip 1
The same effect can be obtained by using a silver strip instead of 6.

[0018]

As described above, according to the present invention, the stainless bellows is provided between the movable conductor and the other metal material, and the copper bellows or the copper strip or the silver strip is provided in parallel with the stainless bellows. By energizing with a copper bellows or copper strip or silver strip with high conductivity, it is possible to prevent temperature rise during energization, and accordingly increase the maximum allowable current and reduce cooling. Or it may be unnecessary. Also, by holding the vacuum with stainless bellows,
The life can be extended.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a vacuum capacitor according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a current-surface temperature characteristic of a vacuum capacitor according to Examples 1 and 2 of the present invention.

FIG. 3 is a life characteristic diagram of vacuum capacitors according to Examples 1 and 2 of the present invention.

FIG. 4 is a vertical sectional view of a vacuum capacitor according to a second embodiment of the present invention.

FIG. 5 is a vertical sectional view of a conventional vacuum capacitor.

[Explanation of symbols]

 1a, 1b ... Flange 2 ... Ceramic 3 ... Fixed conductor 4 ... Lid 5 ... Fixed electrode 6 ... Movable electrode 8 ... Movable conductor 9 ... Capacitance adjusting screw 13 ... Vacuum container 14 ... Stainless steel bellows 15 ... Copper bellows 16 ... Copper Article

Claims (2)

[Claims] 1. A vacuum container is formed by closing both ends of a tubular part, at least a part of which is an insulating tube, with a metal material, and a plurality of tubular electrode plates are concentrically provided inside one metal material. A fixed electrode is formed, and a movable electrode composed of a plurality of tubular electrode plates that are inserted and inserted in a non-contact manner between the tubular electrode plates is attached to a movable conductor, and the movable conductor is rotatably supported by the other metal member. In the vacuum capacitor, which is screwed with the capacitance adjusting screw, and in which a cylindrical bellows is provided between the movable conductor and the other metal material to keep the inside of the vacuum container airtight and to serve as a conductive path, Vacuum capacitor characterized by being composed of stainless bellows and copper bellows. 2. A vacuum container is formed by closing both ends of a tubular part, at least a part of which is an insulating tube, with a metal material, and a plurality of tubular electrode plates are concentrically provided inside one metal material. A fixed electrode is formed, and a movable electrode composed of a plurality of tubular electrode plates that are inserted and inserted in a non-contact manner between the tubular electrode plates is attached to a movable conductor, and the movable conductor is rotatably supported by the other metal member. In a vacuum capacitor screwed with a capacitance adjusting screw, and in which a cylindrical bellows is provided between the movable conductor and the other metal material to keep the inside of the vacuum container airtight and to serve as a current path, A vacuum capacitor comprising a stainless bellows and a movable conductor and the other metal material connected by a copper strip or a silver strip.