JPH0664973B2 - Vacuum discharge device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention has a low melting point and a high vapor content at a contact portion of an electrode for obtaining a low breaking current of a vacuum breaker, a circuit breaker, a vacuum arrester, a vacuum type three-point gear, etc. The present invention relates to a vacuum discharge device that includes a pressure metal and does not have an exhaust chip tube.

[Conventional technology]

An example of the configuration of a conventional vacuum discharge device will be described with respect to a vacuum breaker and a breaker of the type disclosed in Japanese Examined Patent Publication No. 59-8930, which does not include a conventional exhaust chip tube. In FIG. 2, 1a and 1b are fixed electrodes and movable electrodes, 2 is a bellows, 3a and 3b are fixed flanges and movable flanges, 4 is a shield, 5 is an insulating cylinder, and these members except the shield 4 are mutually It is joined to an adjacent member to form a sealed vacuum container. Generally, bismuth Bi, tellurium Te,
Copper alloy containing low melting point metal such as antimony Sb or lead Pb, bellows (2) is austenitic stainless steel, and flanges 3a and 3b are Kovar (16Co-29Ni-remaining Fe) or
The shield 4 is made of 13Cr stainless steel, the shield 4 is made of a material such as Cu, Ni, Fe or stainless steel, and the insulating cylinder 5 is made of alumina porcelain.

Next, the manufacturing process of the vacuum and the breaker according to the prior art will be described. The vacuum breaker and breaker shown in FIG. 2 are first assembled with the fixed side electrode 1a and the flange 3a by furnace brazing in the furnace or vacuum brazing, and similarly the movable side electrode 1b, Pre-assemble the bellows 2 and the flange 3b. Then, the shield 4 is attached to the insulating cylinder 5 by an appropriate method. Thus, the brazing filler materials 40a and 40b are inserted between the fixed side assembly structure 10, the movable side assembly structure 20 and the shield insulating cylinder assembly structure 30 to reduce the pressure of low pressure in the vacuum furnace or the vacuum furnace. Atmosphere gas is introduced and the whole is heated to melt and solidify the brazing filler metals 40a, 40b, and the required sealed vacuum container is completed.

As discussed in Japanese Patent Publication No. 59-8930, the problem in vacuum brazing is the reliability of the brazed seal of the stainless steel member containing chromium Cr. Since the reducing action in a vacuum is weaker than in a hydrogen furnace, a brazing temperature of about 950 ° C or higher is required for the stainless steel member containing Cr, which has a high oxygen affinity, but on the other hand, if heated to 950 ° C or higher, the bellows 2 Causes a problem that the elastic function is deteriorated to cause vacuuming and the mechanical opening / closing life of the circuit breaker is shortened. Therefore, the pressure number in the vacuum furnace
Introducing a reducing gas such as hydrogen or a mixed gas of these such as an inert gas at a low pressure of 10 ^-3 Torr to Torr to suppress the brazing temperature of stainless steel while keeping the brazing temperature in a vacuum furnace below 950 ° C. A method of maintaining the sealing reliability of the attachment part has been proposed.

[Problems to be solved by the invention]

The conventional vacuuming or disconnecting type that does not have a chip pipe for exhausting is configured as described above, and since low-pressure inert gas or hydrogen gas is introduced into the vacuum furnace and brazed and sealed, In some cases, a vacuum degree may be deteriorated as a result of confining the inert gas or hydrogen gas in the vacuum container, and therefore the manufacturing yield is not necessarily good.

In addition, Bi, Te, Sb, contained in the contact material of the electrode,
Since the metal vapor of high vapor pressure of low melting point metal such as Pb acts on the seal joint even in the low pressure vacuum brazing method, the joint strength of the braze seal is extremely low.
It has been extremely difficult to manufacture reliable vacuum and circuit breakers.

The present invention has been made in order to solve the above problems, does not leave a residual gas in a vacuum container, and has high sealing reliability without contamination of metal vapor of a low melting point metal at a sealing joint. For the purpose of economically providing a high-yield vacuum breaker, circuit breaker, and vacuum discharge device, which has a low breaking current and excellent handling characteristics without the need for an exhaust chip tube. There is.

[Means for solving problems]

A vacuum discharge device according to the present invention is characterized in that a hydrogen storage alloy is provided inside a vacuum container, and a part of a metal member of the vacuum container is composed of a hydrogen permeable member. Due to the action of pure hydrogen gas, an extremely reliable brazing and sealing part is obtained. After the brazing and sealing, the residual hydrogen gas inside the vacuum container is passed through the hydrogen permeable member by heating at a high temperature which is lower than the temperature at the time of brazing and sealing in a vacuum or a non-hydrogen atmosphere. Is evacuated to the outside of the vacuum container.

[Action]

In the vacuum discharge device according to the present invention, high-purity hydrogen gas is released from the hydrogen-absorbing alloy by heating during vacuum brazing and sealing, and the inside of the vacuum container (as compared with the conventional low-pressure vacuum method).
As a result of being filled with high-pressure hydrogen gas, it suppresses the evaporation of low-melting-point metal in the contact and strongly reduces the brazed joint, so it is significantly superior to the conventional vacuum brazing method in low-pressure hydrogen. Brazing and sealing are possible. In addition, since the reducing action of the brazing sealing part is stronger than the conventional method, the brazing temperature can be set lower (than the conventional method),
The mechanical open / close life of the bellows can be extended.

When exhausting the hydrogen gas through the hydrogen permeable member after brazing and sealing, heating may be performed in an inert gas such as nitrogen gas having a hydrogen partial pressure of 1 × 10 ^-5 Torr or less. If there is a leak hole in the brazing sealing part or the vessel wall of the vacuum container while exhausting the hydrogen gas, it becomes possible to test the presence and the size of this leak at the same time.

Example of Invention

An embodiment of the present invention will be described below with reference to the drawings. First
In the figure, 1a and 1b are fixed electrodes and movable electrodes, 2 is a bellows, 3a and 3b are fixed flanges and movable flanges, 4 is a shield, and 5 is an insulating cylinder.

All the members other than the shield 4 are airtightly joined to the members adjacent to each other to form a vacuum container, and the constituent materials thereof are the same as those of the conventional example shown in FIG.

The first feature of the present invention resides in that the hydrogen storage member 6 is housed inside the vacuum container. The hydrogen storage material is titanium T
It is made of a single metal such as i, tantalum Ta, niobium Nb, or zirconium Zr, or an alloy containing these, and is attached to a portion having a relatively low electric field so as not to affect the withstand voltage characteristics of a vacuum or a breaker.

The second characteristic of the present invention is that a part or all of the metal member of the vacuum container is formed of a hydrogen permeable member.
In this embodiment, the bellows 2, the fixed flange 3a, and the movable flange 3b are formed as hydrogen permeable members. That is, the bellows 2 is made of austenitic stainless steel containing Ti or Ta, Nb, and has a fixed flange 3a and a movable flange 3b.
Is composed of a copper Cu alloy or nickel Ni alloy containing palladium Pd. These hydrogen permeable members are made from conventional conventional austenitic stainless steel and Kovar (Kova
r) It is characterized by a hydrogen permeability that is about 10 times greater than that of the alloy.

Fixed side assembly structure, similar to conventional vacuum and breakers
10, the movable side assembly structure 20, the shield / insulation cylinder assembly structure 30 and the sealing brazing materials 40a and 40b are introduced into a high vacuum or a vacuum furnace by introducing a low pressure atmosphere gas (hydrogen pressure of about 10 Torr). Vacuum and heat the entire disconnector. In this embodiment, eutectic silver solder (about 72 Ag-28 Cu) was used as the sealing brazing filler metals 40a and 40b.

With the start of heating, the hydrogen storage member 6 in the present invention starts to release its built-in hydrogen as the temperature rises, and almost all the built-in hydrogen is released at the melting point (about 780 ° C.) of the eutectic silver braze. The hydrogen pressure in the vacuum container changes depending on the temperature rise rate and the exhaust conductance determined by the gap between the sealing brazing materials 40a and 40b.
The maximum pressure above was recorded.

The generation of high-temperature, high-purity hydrogen gas at such a relatively high pressure significantly suppresses the evaporation of low-melting-point, high-vapor-pressure metal contained in the contact points of the electrodes, and vacuum brazing. Since the reducing action of the sealing portion is also strong, an extremely good brazing sealing portion could be obtained.

Due to the melting (melting) of the brazing filler metal in the sealing part, the inside and outside of the vacuum vessel are cut off or disconnected, but the hydrogen trapped inside the vacuum at this time is rapidly cooled after the brazing filler metal has melted down. Absorption was started in the hydrogen storage member 6 by the operation, and the total pressure in the vacuum container when gradually cooled to room temperature was 5 × 10 ⁻³ Torr.

After that, vacuum again at a temperature of 600 ° C. and heat the breaker. It was confirmed that hydrogen trapped inside the vacuum container was exhausted to the outside of the vacuum container through the hydrogen permeable member (2, 3a, 3b) which is the second feature of the present invention. In the examples, after heating at 600 ° C. for 2 hours and gradually cooling to room temperature, a vacuum was applied and the total pressure inside the breaker was 3 × 10 ⁻⁶ Torr.

It should be noted that, in the above-mentioned examples, the case where after cooling by vacuum brazing and once cooled to room temperature and then vacuum heating again was described, in reality, the melting point of eutectic silver solder ( By gradually cooling from about 780 ° C) to about 600 ° C hydrogen exhaust temperature, the above-mentioned exhaust time of 2 hours can be further shortened.

Furthermore, in the above-mentioned embodiment, the case where the final brazing and sealing was carried out in a high vacuum or low pressure hydrogen of about 10 Torr was described. However, this was carried out in a hydrogen furnace of about 760 Torr (1 atm), After that, it is also possible to exhaust the hydrogen gas inside the vacuum container in a non-hydrogen gas atmosphere such as nitrogen gas or argon gas having a hydrogen partial pressure of 1 × 10 ⁻⁵ Torr or less or in vacuum. As a result, the total pressure inside the vacuum vessel after cooling to room temperature was about 1 × 10 ⁻⁴ Torr, and the required withstand voltage was obtained as a vacuum discharge device.

In still another embodiment, the fixed flange 3a, the movable flange 3b
Even when austenitic stainless steel containing Ti, Ta, and Nb was used, good withstand voltage could be obtained.

〔The invention's effect〕

As described above, according to the present invention, since the hydrogen storage member is provided inside the vacuum container, and the metal member of the vacuum container is composed of the hydrogen permeable member, the metal of low melting point and high vapor pressure is contained in the vacuum container. It is possible to completely prevent the contamination of the brazing and sealing part of the discharge device with a high vapor pressure metal, has a high yield and high sealing reliability, and has no exhaust chip and a low breaking current. There is an advantage that a vacuum discharge device having characteristics can be stably and economically produced.

[Brief description of drawings]

FIG. 1 is a sectional view showing a vacuum discharge device according to an embodiment of the present invention, and FIG. 2 is a sectional view showing a conventional vacuum breaker and breaker. In the figure, 1a is a fixed electrode, 1b is a movable electrode, 2 is a bellows, 3a is a fixed flange, 3b is a movable flange, 4 is a shield, 5 is an insulating cylinder, and 6 is a hydrogen storage member. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A vacuum discharge device of a type having at least a pair of electrodes in a vacuum, including a low melting point metal in a contact portion of the electrodes, and not having an exhaust chip tube portion, and storing hydrogen in a vacuum container. A vacuum discharge device comprising a member, wherein a part or all of a metal member of a vacuum container constituted by a metal member and an insulating member is constituted by a hydrogen permeable member.