JPH0612946A - Vacuum valve - Google Patents

Abstract

PURPOSE:To provide a vacuum valve excellent in mechanical strength and large current breaking ability by applying an oxide insulating ceramics film and a metal film to one of opposed surfaces excepting a connection part, in the case of connecting a pair of electrodes, coming into contact with and separating from each other in a vacuum vessel, and a coil electrode connected through a connecting part to a pair of these electrodes. CONSTITUTION:In a vacuum valve wherein a main electrode 8, coil electrode and an electrification shaft 5 are arranged in a vacuum vessel, the coil electrode is constituted of a center part 9a fixed to the electrification shaft 5, arm part 9b extended toward the periphery from the center part 9a, circular arc part 9c extended in a circular arc shape from a point end of this arm part to form a current route and an electric connection part 9d electrically connected to the main electrode 8. An oxide insulating ceramic film 10 is vacuum-evaporated to a coil electrode surface except this electric connection part 9d, and further a metal film 11 is brazed onto this film 10.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to vacuum valves.

[0002]

2. Description of the Related Art A vertical magnetic field electrode for generating a magnetic field parallel to an arc (hereinafter referred to as a vertical magnetic field) at the time of interruption has already been put into practical use. A typical structure thereof is shown in FIG. In FIG. 5, the electrode 1 is composed of a main electrode 2, a coil electrode 3 provided on the back surface thereof, and a reinforcing member 4 provided between the main electrode 2 and the coil electrode 3.

Here, the coil electrode 3 has a central portion 3a fixed to the current-carrying shaft 5, an arm portion 3b extending from the central portion 3a toward the outer circumference, and a circular arc shape concentric with the current-carrying shaft 5 from its tip. The arc portion 3c extending to form a current path, and the main electrode 2
Is provided with a connecting protrusion 3d for electrically connecting to
A longitudinal magnetic field is generated between the electrodes facing each other by the current in the circumferential direction flowing through each arc portion 3c, and the vacuum arc generated between the electrodes is stabilized by the action of this longitudinal magnetic field, so that a large current can be interrupted.

[0004]

However, in such a structure of the electrode 1 of the vacuum valve, the current path is from the current-carrying shaft 5 to the center portion 3a of the coil electrode-the arm portion 3b-the arc portion 3c-the connecting projection portion 3d. Through to the main electrode 2. Here, a gap d for electrical insulation is provided between the central portion 3a of the coil electrode-the arm portion 3b-the circular arc portion 3c and the main electrode 2 so that the current flows through the circular arc portion 3c.
Moreover, the reinforcing member 4 is arranged so that the electrode is not deformed by the force in the compression direction or the tensile direction. Gap d
Must have a sufficient size so that the coil electrode 3 and the main electrode 2 do not come into contact with each other even if they are deformed by the force acting on the electrode.

For example, if the electrode diameter is about 100 mm, the gap d needs to be 2 to 5 mm. In this case, the distance from the central axis of the arc portion 3c of the coil electrode to the intermediate point between the opposing electrodes is about 15 mm. Since the magnitude of the magnetic field generated by the current is inversely proportional to the square of the distance from the current, the gap d
The strength of the magnetic field generated between the electrodes due to (for example, 2 mm) is

[0006]

[Equation 1] {(15/13) ² -1} x 100 = 33%, a reduction of about 30%. For this reason, there is a drawback that the stability of the vacuum arc generated between the electrodes is lowered and the breaking performance is lowered. Further, in order to provide the gap d, the coil electrode 3 needs to be provided with the connecting projection 3d, which results in a complicated processing shape and a high cost.

On the other hand, since the coil electrode 3 is made of a material having low rigidity such as oxygen-free copper, it is necessary to dispose and join the reinforcing member 4 to prevent the electrode from being deformed. Even if it is reinforced with this reinforcing member 4, there is a drawback that the coil electrode 3 and the main electrode 2 are deformed by the impact when the electrode is turned on and when the electrode is opened. Further, by disposing and joining the reinforcing member 4, a part of the electric current that should originally flow through the arc portion 3c of the coil electrode 3 is shunted through the reinforcing member 4 and the strength of the magnetic field generated between the electrodes is weakened. There is also a drawback that the large current interruption performance is deteriorated.

Further, when a contact material having poor brazing property is used, the necessary bonding strength cannot be obtained only by the bonding area of the connecting protrusion 3d, so that the main electrode is not connected to the contact 6 as shown in FIG. 6, for example. It was necessary to increase the connection strength separately for the main electrode 7 made of oxygen copper. An object of the present invention is to provide a vacuum valve that has a simple structure, is mechanically strong, and improves the large current interruption performance.

[0009]

In order to achieve the above object, the present invention provides a vacuum container, a pair of electrodes disposed in the vacuum container so as to be freely contactable and separable, and a connecting portion at the back of the pair of electrodes. In a vacuum valve having a coil electrode that is connected via an electrode and generates an axial magnetic field between the electrodes, a metal film is formed after applying oxide-based insulating ceramics to at least one of the opposing surfaces of the electrode and the coil electrode excluding the connecting portion. Is applied to join the electrode and the coil electrode.

[0010]

In such a structure, at least one of the opposing surfaces excluding the connecting portion between the electrode and the coil electrode is coated with an oxide-based insulating ceramic and then with a metal coating so as to be bonded. It is very strong and can improve the blocking performance.

[0011]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 shows a coil electrode 9 of a vacuum valve of the present invention.
FIG. 2 is a partially enlarged vertical sectional view of the coil electrode 9 of the vacuum valve of the present invention.

In FIG. 1, 8 is a main electrode, 9 is a coil electrode, and 5 is a current-carrying shaft. Here, the coil electrode 9 includes a central portion 9a fixed to the current-carrying shaft 5, an arm portion 9b extending from the central portion 9a toward the outer periphery, and an arc portion 9c extending in an arc shape from its tip to form a current path. , And an electrical connection portion 9d electrically connected to the main electrode 8.

Further, in FIG. 2, except for the electrical connection portion 9d of the coil electrode 9, for example, about 30 is previously prepared in a vacuum deposition apparatus.
The oxide-based insulating ceramic coating 10 is coated to a thickness of about several angstroms to several μm in a vacuum of about 10 ⁻⁴ to 10 ⁻⁵ Torr by heating to a temperature of about 0 to 500 ° C.

Since this coating film 10 is coated in a high vacuum, there is no mixing of gas or oxidation of the surface of the coil electrode 9, so that the coating material has excellent adhesion. On the other hand, in coating by thermal spraying or the like, a large amount of gas is mixed, and when assembled after brazing the coil electrode 9 and the main electrode 8 with the gas mixed, the degree of vacuum in the vacuum valve may decrease with the passage of time. There is. Further, in the case of thermal spraying, the surface roughness is rough and it is difficult to obtain a uniform film thickness. When brazing is performed with unevenness, defects partially occur and the joint strength is reduced. However, in the case of vacuum vapor deposition, a brazing property is also good because a film is densely and uniformly formed. In addition, a metal coating 1 such as Ti or Ni is formed on the surface of the coil electrode 9 on the main electrode 8 side.
1. By applying to the outermost surface of the oxide-based insulating ceramic coating 10, a buffering effect of preventing peeling or cracking of the insulating ceramic coating 10 due to a difference in thermal expansion during brazing is obtained, and brazing property is improved. . Further, since Ti is an active metal, high adhesion strength can be easily obtained even on the surface of the oxide-based insulating coating 10 or the like, and sound brazing can be expected.

FIG. 3 shows the amount of release of the internal gas by vacuum vapor deposition, thermal spraying and the like. As shown in FIG. 3, the insulating ceramics film formed by vacuum vapor deposition is suitable for vacuum equipment such as a vacuum valve because it releases less gas than other coatings. FIG. 4 shows the bonding strength of the insulating ceramic coating 10. As shown in FIG. 4, the vacuum-deposited ceramic coating 10 has higher bonding strength and less variation than other coatings.

On the other hand, since the coil electrode 9 is connected to the main electrode 8 via the insulating ceramic coating 10 except for the electrical connection portion 9d, the resistance between the coil electrode 9 and the main electrode 8 is extremely large. Therefore, it is not necessary to provide the gap d as shown in FIG. 5 of the related art, and it is considered that the insulating film is electrically insulated even if it is thin.

The current flowing through the coil electrode 9 is not shunted to the main electrode 8 on the way, and all the current flows through the arc portion 9c.
Flowing through. That is, the current that generates the vertical magnetic field is the main electrode 8
Since it flows through the coil electrode 9 without being divided into two, a longitudinal magnetic field of effective strength can be generated between the electrodes, and the breaking performance is improved.

The present invention is not limited to the above embodiment,
Either one or both of the coil electrode 9 and the main electrode 8 is provided with an insulating ceramic coating 10 for bonding, and various shapes of electrodes can be devised. Further, the shape of the coil electrode 9 does not necessarily have to be a flat plate shape, and may be any shape that engages with the main electrode 8.

[0019]

As described above, according to the present invention, with respect to the joining of the pair of electrodes that come into contact with and separate from each other in the vacuum container and the coil electrode connected to the pair of electrodes through the connecting portion, the electrode excluding the connecting portion is provided. Since at least one of the opposing surfaces of the coil electrode and the coil electrode is coated with an oxide-based insulating ceramic and then a metal coating is applied to join the main electrode and the coil electrode, a simple structure and mechanical strength The blocking performance can be improved.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a coil electrode of a vacuum valve of the present invention.

FIG. 2 is a partially enlarged vertical sectional view of a coil electrode of a vacuum valve of the present invention.

FIG. 3 is a diagram showing the amount of gas released according to the type of coating.

FIG. 4 is a diagram showing the bonding strength depending on the type of coating.

FIG. 5 is an exploded perspective view of a coil electrode of a conventional vacuum valve.

FIG. 6 is a view showing another electrode structure of a conventional vacuum valve.

[Explanation of symbols]

8 ... Main electrode, 9 ... Coil electrode, 9d ... Electrical connection part, 10 ...
Oxide insulating ceramic coating, 11 ... Metal coating.

Claims (1)

[Claims] 1. A vacuum container, a pair of electrodes disposed in the vacuum container so as to be able to come into contact with and separate from each other, and a back part of the pair of electrodes via a connecting portion, and an axial magnetic field is applied between the electrodes. In a vacuum valve having a coil electrode to be generated, at least one of the opposing surfaces of the electrode and the coil electrode excluding the connecting portion is coated with an oxide-based insulating ceramic and then a metal coating is applied to bond the electrode and the coil electrode. A vacuum valve that is characterized.