JPH0474812B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to a vacuum valve, and particularly to the structure of an electrode that applies a magnetic field parallel to an arc generated when the vacuum valve is shut off. [Technical background of the invention and its problems] Generally, a vacuum valve has an insulating cylinder formed of an insulating material, with openings at both ends closed by end plates.
It consists of a pair of electrodes that can be moved into and out of contact with each other in a vacuum container with an internal pressure of 10 ^-4 Torr or less. Incidentally, in recent years, in order to improve the interrupting performance and reduce the size of the electrode, electrodes that apply a magnetic field parallel to the arc (hereinafter referred to as longitudinal magnetic field electrodes) have been increasingly used. FIG. 7 shows the structure of this vertical magnetic field electrode. In the figure, the vertical magnetic field electrodes 1 and 2 are constructed by providing a coil electrode 4 on the back of a main electrode 3, and are designed to prevent shocks when switching on and off the current. A reinforcing member 5 is provided between the main electrode 3 and the coil electrode 4 to prevent the main electrode 3 from cracking or the coil electrode 4 from deforming due to an increase in internal stress. This reinforcing member 5 is usually made of a high-resistance member such as a stainless steel material so that most of the cut-off current flows through the coil electrode 4 in order to maintain a desired magnetic field strength during current cut-off. The coil electrode 4 is composed of a plurality of arm portions 4a extending radially from the center and a plurality of outer peripheral portions 4b extending circumferentially, and is separated from the main electrode 3 by interposing a connector 6 at the terminal end. They are joined using silver brazing. Therefore, when the current is cut off, the vertical magnetic field electrodes 1 and 2 constitute an electric path from the main electrode 3 to the connector 6 to the coil electrode 4, and a magnetic field parallel to the arc generated between the vertical magnetic field electrodes 1 and 2 is generated. The structure is such that it is possible to add However, although the vacuum valve equipped with the vertical magnetic field electrodes 1 and 2 has the advantage of improved shutoff performance over vacuum valves of other types (for example, spiral electrodes), it has the disadvantage of a complicated structure and an increase in the number of joints. There is. In particular, the reliability of silver soldered parts may be impaired. That is, the eighth
In the figure, the connection between the main electrode 3 and the coil electrode 4 is as follows.
A connector 6 is interposed between the connector 6 and the main electrode 3 at a junction 7, and between the connector 6 and the coil electrode 4 at a junction 8.
They are joined by silver brazing, but due to the fact that the plate thickness of the silver solder is as thin as 0.1 to 0.3 mm, joining by silver brazing has the following problems. (1) When manufacturing the coil electrode 4, it is necessary to strictly measure and manage its flatness. This means that there are multiple coil electrodes 4 for the main electrode 3.
Since these are joined via the connector 6, uniform silver soldering becomes impossible if a difference in level occurs between these plurality of joined parts. This is because, as described above, the plate thickness of the silver solder is extremely thin at 0.1 to 0.3 mm, so if a step larger than this occurs, there will be a problem that at least one spot will not be able to be bonded. (2) When manufacturing the connector 6, it is necessary to strictly measure and control the length dimension. This is because the same problem as described in item (1) above occurs. (3) It has a complex structure with many joints, which may lead to errors during assembly. (4) Visual control of the silver brazing condition of joints is essential, but this control is not possible for the internal condition, which is important only for the external condition of the silver brazing. For this reason, it is difficult to increase the mechanical strength and improve reliability, and if the opening and closing are repeated many times, the joints 7 and 8 will break due to the transmission of the impact force applied between the electrodes. Failure to do so may result in malfunctions. On the other hand, the contact area between the connector 6 and the main electrode 3 influences the current carrying capacity. However, since this connector 6 is cylindrical for economical reasons, its diameter is limited by the width W of the circumferential portion 4b of the coil electrode 4, and the diameter of the connector 6 is limited by the width W of the circumferential portion 4b of the coil electrode 4. It is not possible to secure a sufficient contact area for the current carrying capacity. Still, in order to increase the silver brazing strength of the joint, it is necessary to increase the silver brazing area of the connector 6, that is, the bonding area. However, increasing the joint area is preferable in terms of increasing silver brazing strength, but it also shortens the effective distance of the current carrying path, which is related to the magnetic field distribution and magnetic field strength for controlling the arc. , which is disadvantageous in terms of interrupting performance. On the other hand, if the effective distance of the coil electrode 4 is increased, a sufficient joint area for silver soldering cannot be ensured, and the coil electrode 4 is likely to fall off from the main electrode 3. [Object of the Invention] The present invention was made in view of the above-mentioned circumstances, and aims to provide a high-quality vacuum valve with increased mechanical strength of the electrode and improved reliability. . [Summary of the Invention] The present invention provides an arm portion extending radially from the center and an outer periphery extending circumferentially at the back of a main electrode, inside a vacuum container in which both openings of an insulating cylinder are closed with end plates. In a vacuum valve in which a pair of electrodes each having a coil electrode consisting of two parts are arranged so as to be able to come and go, the coil electrode is protruded in a stepped manner toward the main electrode side at the terminal end of the outer peripheral part, and the upper surface thereof is used as the main electrode. Protrusions that are joined by silver brazing are provided to improve the precision of the flatness of the coil electrodes, increase the mechanical strength of the joint, and improve reliability. [Embodiment of the Invention] Hereinafter, an embodiment of the vacuum valve of the present invention will be described with reference to the drawings. Note that the same parts as in FIGS. 7 and 8 are denoted by the same reference numerals, and redundant explanation will be omitted. In FIGS. 1 to 5, a vacuum valve 10 has end plates 12a and ^12b airtightly provided at the openings at both ends of an insulating cylinder 11 formed of an insulating material such as ceramic.
It consists of a vacuum container 13 evacuated as described below, and a pair of vertical magnetic field electrodes 14 and 15 disposed inside the vacuum container 13 so as to be able to freely come and go. The shaft (fixed current-carrying shaft) 16 hermetically passes through the end plate 12a to form one electrical path, and the current-carrying shaft (movable current-carrying shaft) 17, which has one end fixed to the vertical magnetic field electrode 15, connects the end via the bellows 18. attached to the plate 12b, forming the other electric path and being driven by an operating mechanism (not shown);
It can move freely in the axial direction while maintaining a vacuum. Further, inside the vacuum container 13, a vertical magnetic field electrode 14 is provided.
An arc shield 19 is attached to surround the electrodes 14 and 15, and prevents the inner wall of the insulating cylinder 11 from being contaminated by metal vapor generated from the vertical magnetic field electrodes 14 and 15 when current is cut off. The vertical magnetic field electrode 14 is composed of a main electrode 3 and a coil electrode 20 provided on the back of the main electrode 3, and has a structure in which a magnetic field parallel to the arc generated when the current is interrupted is applied. There is. In addition,
The vertical magnetic field electrode 15 also has a similar configuration. The coil electrode 20 described above has an arm portion 20a extending radially from the center, an outer peripheral portion 20b extending in an arc shape in the circumferential direction, and a terminal end of the outer peripheral portion 20b protruding stepwise toward the main electrode 3 side. Protrusion 2
0c, and is connected to the main electrode 3 by silver brazing on the upper surface of this protrusion 20c (symbol 2
1 indicates the joint). Note that the coil electrode 20 having such a configuration can be easily manufactured by plastic deformation using a press. Here, in the above-mentioned protruding portion 20c, the dimension Y of the stepped portion is 10 to 70% of the thickness T of the outer peripheral portion 20b. This is due to the relationship between the thickness of the silver solder and the strength of plastic deformation. In addition, the area of the upper surface joined to the main electrode 3, that is, the joint area, is set to 1.0 to 1.0 of the cross-sectional area (WXT) of the outer peripheral part 20b, that is, the cross-sectional area of the current-carrying path.
Make it 1.6 times. This is based on the following experiment. That is, the outer diameter is 42 mm and the thickness T of the outer peripheral part 4b is
A coil electrode 4 with a diameter of 5.6 mm and a width W of 7 mm was manufactured from pure copper material, and the coil electrode 4 had a diameter of 7 mm and a length of 7 mm.
A 1.5 mm cylindrical connector 6 is interposed and connected to a main electrode 3 made of a 0.5% Bi-Cu alloy material with an outer diameter of 42 mm and a thickness of 4 mm using silver solder made of 72% Ag-Cu. Magnetic field electrodes 1 and 2 were manufactured, and these were placed in a vacuum container (same configuration as vacuum container 13) to manufacture a vacuum valve. This vacuum valve is referred to as Comparative Example 3. On the other hand, as shown in FIG. 6, the area of the upper surface 20d of the protrusion 20c that is joined to the main electrode 3, that is, the joint area, is varied by 0.75 to 2.25 times the cross-sectional area of the outer peripheral part 20b, that is, the current-carrying path area. The coil electrode 20 was manufactured from pure copper material, and the vertical magnetic field electrodes 14 and 15 were manufactured by joining this coil electrode 20 to the main electrode 3 similar to that in Comparative Example 3 using the same silver solder. A vacuum valve was manufactured by installing the These vacuum valves will be referred to as Comparative Examples 1 and 2 and Examples 1 to 3. Therefore, impact tests and interruption tests were conducted on these comparative examples and examples, and the results shown in the following table were obtained. Here, the impact test is performed on the energized shaft of the vacuum valve.
500Kg impact load (impact load time 1000μsec) 10 ²
The number of joints that fell off was evaluated for 10 vacuum valves. In addition, the cut-off test is 6KV-
This was used to cut off 12.5 KA of power, and was compared with other vacuum valves with the cut-off characteristics of the vacuum valve using connector 6 as 100%.

〔Effect of the invention〕

Since the present invention is configured as described above,
It is possible to provide a vacuum valve in which the mechanical strength of the electrode is increased without impairing electrical performance, the reliability is improved, and the vacuum valve is economically advantageous.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an embodiment of the vacuum valve of the present invention, Fig. 2 is a plan view showing essential parts of an embodiment of the invention, and Fig. 3 is a view taken in the direction of arrow A in Fig. 1. 4 is a sectional view taken along the line B-O-B in FIG. 1 and viewed in the direction of the arrow, and FIG. 5 is a sectional view taken along the line C--
Sectional view taken along line C and viewed in the direction of the arrow, No. 6
The figure is a perspective view showing main parts different from FIG. 2 of the present invention,
Figure 7 is a plan view showing the electrodes of a conventional vacuum valve;
FIG. 8 is a sectional view taken along line A--O--A in FIG. 7 and viewed in the direction of the arrow. 3... Main electrode, 13... Vacuum container, 14, 15
...Electrode, 20...Coil electrode, 20a...Arm part, 20b...Outer peripheral part, 20c...Protrusion part.

Claims (1)

[Claims] 1 Inside a vacuum vessel in which the openings at both ends of an insulating cylinder are closed with end plates, the main electrode is made up of arms that extend radially from the center and an outer periphery that extends circumferentially from the center, and diffuses the arc. A vacuum valve in which a pair of electrodes including a coil electrode that generates an axial magnetic field for generating an axial magnetic field is disposed such that the coil electrode can be freely moved toward and away from the vacuum valve, and the coil electrode is protruded in a stepped manner toward the main electrode at a terminal end of the outer peripheral portion. The vacuum valve is characterized in that the upper surface thereof is provided with a protruding portion having an area 1.0 to 1.6 times as large as the cross-sectional area of the outer peripheral portion and connected to the main electrode by silver brazing.