JPH11144575A - Vacuum interrupter and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vacuum interrupter with high welding resistance in addition to keeping high breaking performance and durability, and provide its manufacturing method. SOLUTION: In this vacuum interrupter having a pair of fixed electrode and moving electrode openably/closably, the fixed electrode is made of a material containing a welding resistant component, contains Te as the welding resistant component, the fixed electrode is made of a sintered metal of Cu-Cr-Te, and the content of Te is limited to 0.05-2.0 wt.%. The holding time and cooling time in brazing with a silver brazing material are shortened about 1/2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum interrupter, and more particularly, to a fixed electrode of a pair of electrodes formed of a material containing a welding-resistant component to maintain a breaking performance and a durability and to improve a welding resistance. The present invention relates to an improved vacuum interrupter and a manufacturing method that ensures brazing.

[0002]

2. Description of the Related Art There are various types of performance required for a vacuum interrupter. For example, current interrupting performance, withstand voltage characteristics,
It has low breaking current, welding resistance and durability. Conventionally, various electrode materials have been developed in order to satisfy these various performances.
Electrodes and Cu-Cr sintered metals are known.

[0003] Among them, Cu-Bi electrodes have good welding resistance, but are characterized by inferior breaking performance and the like.
Although the u-Cr electrode has good blocking performance, it is characterized in that the welding resistance is slightly inferior. Recently, the company has high performance
A proposal for a u-Cr electrode has also been made (Japanese Patent Publication No. 61-31172).
No.), the present inventors have also paid attention to the Cu—Cr electrode and searched for an electrode material that improves welding resistance without lowering the blocking performance.

[0004]

A brittle material was added to improve the welding resistance. B for Cu-Cr electrode
When i was added, the blocking performance was reduced. Also, P
When b was added, the blocking performance was also reduced in this case. Furthermore, when Sb was added, the electrical conductivity also decreased with the decrease in the breaking performance.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a vacuum interrupter having an electrode material having improved welding resistance without lowering the breaking performance, and a method of manufacturing the same.

[0006]

The present invention that achieves the above object has the following matters specifying the invention. (1) In a vacuum interrupter having a pair of fixed electrodes and a movable electrode which can be opened and closed freely, the fixed electrodes are formed of a material containing a welding resistant component.

(2) In the above (1), the welding resistant component is Te.

(3) In the above (1), the fixed electrode is made of a sintered metal of Cu-Cr-Te.

(4) In the above (2), the Te content of the fixed electrode is 0.05 to 2.0% by weight.

(5) In a vacuum interrupter having a fixed electrode containing a welding-resistant component and a movable electrode, when the fixed electrode and the movable electrode are temporarily assembled and brazed, a silver brazing material is used. The brazing temperature was set to be equal to or higher than the melting point of the silver brazing material, and the holding time at the brazing temperature and the subsequent cooling time were shortened to about に 対 し て that of a vacuum interrupter having a Cu-Cr electrode. I do.

(6) In the above item (5), the brazing is performed at a temperature of 800 ° C. or more for a holding time of 10 minutes.

(7) In the above (5), the cooling time after the brazing is 30 to 700 ° C. at which the silver brazing material solidifies.
Minutes.

As a result of the experimental investigation, attention was paid to Te. This T
e does not form a solid solution in Cu. In addition, it has been found that the characteristic that the blocking performance is not reduced. And Cu, Cr, T
As a result of conducting various experiments using the metal powder of e, the following was found.

One electrode was made of 82% by weight of Cu and 18% by weight of Cr, and the other electrode was made of the same Cu-Cr with Te added. Here, when Te was added, FIG.
As shown in Fig. 7, as the amount of addition increased, the barrier performance gradually decreased, and when the amount was more than a certain amount, the barrier performance sharply decreased. On the other hand, it was also found that when Te was added, as shown in FIG. 2, the welding force was reduced in accordance with the amount of addition. The following was found from the experimental results shown in FIGS. Te
If the amount of addition of 2.0% by weight or more, it is found that the blocking performance is unfavorably reduced, and that the mechanical strength is also reduced.
If the content is 0.05% by weight or less, the welding strength is high, and improvement in the welding resistance cannot be expected.

Next, an electrode was formed from a sintered metal obtained by adding Te to 82% by weight of Cu and 18% by weight of Cr, and a durability test was performed. As shown in FIG. 3, it was found that when used for a movable electrode, the durability was significantly reduced, while when used for a fixed electrode, the durability was hardly reduced. That is, when the Te-containing electrode is used for the fixed electrode, the opening and closing of 20,000 times can be maintained even if 2% by weight of Te is contained, and when the Te-containing electrode is used for the movable electrode, about 100 times cannot be used. This is because a reciprocating impact load acts on the movable side to cause breakage due to the inclusion of fragile material Te, and the fixed side receives only a compressive load and has a low probability of breakage. As a result, if the Te-containing electrode is used as a fixed electrode, an electrode that has improved welding resistance and does not decrease durability can be obtained.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Here, an embodiment of the present invention will be described with reference to FIG. FIG. 4 shows a cross section of the vacuum interrupter. In FIG. 4, fixed and movable end plates 2 a and 2 b are attached to both ends of an insulating cylinder 1 to form a vacuum vessel.
Is arranged. A movable lead bar 5b is hermetically pierced through the movable end plate 2b via a bellows 4, and a movable electrode 6b made of a Cu-Cr sintered body is provided at the tip of the movable lead bar 5b. On the other hand, a fixed lead bar 5a is provided through the fixed end plate 2a in an airtight manner, and a fixed electrode (C) containing a welding resistant component is provided at the tip of the fixed lead bar 5a.
u-Cr-Te) 6a. The fixed electrode 6a and the movable electrode 6b are provided with a plurality of arcuate radial slits. In such a configuration, the current is opened and closed by the movable electrode 6b being brought into contact with and separated from the fixed electrode 6a in a vacuum.

In this structure, a Cr powder having an average particle size of 8 μm and Cu and Te powders having an average particle size of 40 μm are used for forming the electrodes.

<Case of Forming Fixed Electrode 6a> First, a mixed powder of Cu—Te is obtained. Next, this is mixed with a Cr powder to obtain a mixed powder. The mixed powder is compression molded with a 60φ mold. The molded body is gradually heated in an inert gas (such as in a vacuum) and finally sintered at about 1040 ° C. Predetermined machining (radial arc grooves,
By performing contact surface grinding or the like, a desired spiral fixed electrode 6a is obtained. In this case, when sintering by compression molding into a spiral shape, only the contact surface is ground.

<When the movable electrode 6b is formed> A mixed powder of Cu-Cr is obtained. The mixed powder is compression molded with a 60φ mold. The molded body is gradually heated in an inert gas (in vacuum) or the like, and finally sintered at about 1040 ° C. The obtained sintered body is subjected to predetermined machining (radial arc groove, contact surface grinding, etc.) to obtain a desired spiral movable electrode 6b. In this case, when sintering by compression molding into a spiral shape, only the contact surface is ground.

Each of the electrodes 6a, 6 obtained as described above
b is mounted on the ends of the lead rods 5a and 5b together with a brazing material (silver brazing), and other components of the vacuum interrupter are temporarily assembled together with the brazing material (silver brazing) and brazed in a vacuum furnace. I have a vacuum interrupter.

By including the body-welding component in this manner, characteristics that do not degrade the blocking performance can be obtained, and durability can be ensured by including the welding-resistant component only in the fixed electrode. In addition, the load on the operating device can be reduced by improving the welding resistance, and the operating portion such as the shut-off spring can be simplified.

As described above, by using a Cu-Cr sintered metal containing Te for the fixed electrode, a great technical effect can be obtained, but another problem arises in manufacturing. That is, when the vacuum interrupter component was vacuum brazed using silver brazing material using a Cu—Cr—Te electrode, poor brazing between the insulating cylinder 1 and the fixed-side end plate 2a and the movable-side end plate 2b. Was generated and vacuum leakage sometimes occurred. In this case, the brazing temperature is about 800
C. (at a melting point of the silver brazing material of about 780.degree. C.) for 20 minutes, and after brazing, the silver brazing material was cooled to 700.degree.

As a result of analyzing and pursuing the cause of the vacuum leakage, it was found that Te in the electrode evaporated and scattered and entered the brazing material, lowering the melting point of the brazing material and lowering the liquid layer temperature. And, for this purpose, 700 ° C. for more than 800 ° C. for 20 minutes
It was found that the brazing, which had been lacking for one hour for cooling to ° C., caused the molten brazing material to flow and the required amount of brazing material for airtight brazing could not be secured at the above-mentioned joint.

For this reason, a method of manufacturing a vacuum interrupter which can be vacuum-brazed without causing a shortage of the brazing material even if it contains Te, which is a low melting point metal, has been further invented. That is, FIG.
In the vacuum interrupter shown in (1), a movable electrode 6b made of Cu-Cr having a plurality of arc-shaped radial slits is attached to the tip of the movable lead rod 5b, while a Cu-Cr-Te having a plurality of arc-shaped radial slits is attached. The fixed electrode 6a is attached to the tip of the fixed lead bar 5a. Also,
The shield 3 is arranged in the insulating cylinder 1. Further, a fixed end plate 2a and a movable end plate 2b are attached to both ends of the insulating cylinder 1 to form a container. A fixed lead rod 5a is passed through the fixed end plate 2a in an airtight manner, and the movable end plate is formed. The movable lead bar 5b also passes through the bellows 4 airtightly through the bellows 4b.

A silver plate brazing material is interposed between the fixed end plate 2a, the movable end plate 2b and the insulating cylinder (ceramic) 1,
A wire brazing material or a sheet brazing material is interposed in another joining portion. The vacuum interrupter having the above configuration is temporarily assembled and heated in a vacuum furnace, and brazing is performed at a temperature of 800 ° C. or more (Examples 840 to 8).
(60 ° C.) for 10 minutes, then cooled to 700 ° C. at which the silver brazing material solidifies in 30 minutes, and then cooled in a vacuum furnace to obtain a vacuum interrupter.

As a result of the above-mentioned manufacturing method, there was no brazing defect (occurrence of airtightness) due to insufficient brazing material, and the vacuum airtight brazing could be performed reliably.

[0027]

According to the present invention as described above, the following effects can be obtained. (1) Although a welding-resistant component was contained, a vacuum interrupter with improved welding resistance was obtained without lowering the blocking performance. (2) Since the non-welding component was contained only in the fixed electrode and not contained in the movable electrode, the durability was secured. (3) As a result, the burden on the operation device can be reduced, and simplification of the operation part such as the shut-off spring can be expected. (4) The breaking performance of the Cu—Cr electrode material was maintained, and the welding resistance was improved. (5) It is possible to obtain a vacuum interrupter that can reliably perform hermetic brazing without brazing failure (occurrence of airtightness) due to insufficient brazing material.

[Brief description of the drawings]

FIG. 1 is a graph showing a breaking performance characteristic.

FIG. 2 is a characteristic diagram of a welding force.

FIG. 3 is a characteristic diagram of switching life.

FIG. 4 is a cross-sectional view of an example of a vacuum interrupter.

[Explanation of symbols]

 6a fixed electrode 6b movable electrode

 ────────────────────────────────────────────────── ─── Continued on front page (72) Inventor Yo Nishijima 2-1-1-17 Osaki, Shinagawa-ku, Tokyo Inside Meidensha Co., Ltd.

Claims (7)

[Claims] 1. A vacuum interrupter having a pair of fixed electrodes and a movable electrode that can be freely opened and closed, wherein the fixed electrode is formed of a material containing a welding-resistant component. 2. The vacuum interrupter according to claim 1, wherein said welding resistant component is Te. 3. The vacuum interrupter according to claim 1, wherein the fixed electrode is made of a sintered metal of Cu—Cr—Te. 4. The fixed electrode having a Te content of 0.05
3. The vacuum interrupter according to claim 2, wherein the amount is about 2.0% by weight. 5. A vacuum interrupter comprising a fixed electrode containing a welding-resistant component and a movable electrode, wherein when the fixed electrode and the movable electrode are temporarily assembled and brazed, a silver brazing material is used. The brazing temperature should be equal to or higher than the melting point of the silver brazing material, and the holding time at the brazing temperature and the subsequent cooling time should be Cu
-About 1/2 for vacuum interrupters with Cr electrodes
A method of manufacturing a vacuum interrupter, characterized in that the method is shortened to: 6. The method for manufacturing a vacuum interrupter according to claim 5, wherein the brazing is performed at a temperature of 800 ° C. or more for a holding time of 10 minutes. 7. The method for manufacturing a vacuum interrupter according to claim 5, wherein a cooling time after the brazing is set to 700 ° C. for 30 minutes until the silver brazing material solidifies.