JPH0229647Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a vacuum valve, and particularly to improving the strength of the current-carrying shaft.

[Technical background of the invention and its problems]

In general, as the pressure and capacity of vacuum valves increases, the distance between the electrodes increases, and the speed of opening and closing operations of the movable electrode section also tends to increase. In this way, as the speed of opening and closing operations increases, the impact load when the movable electrode collides with the fixed electrode also increases, and the current-carrying shaft to which the electrode is attached is susceptible to the compressive and tensile loads caused by the impact. This may result in deformation or fatigue failure due to repeated loading. Since this current-carrying shaft is generally made of copper material, elongation and constriction due to impact loads are unavoidable due to material characteristics.In vacuum valves, this elongation and contraction of the current-carrying shaft appears as the distance between the electrodes, and this If the distance is short, the current cannot flow or cut, and if the distance is long, the contact pressure between the electrodes decreases, arcing occurs between the electrodes, and the electrodes melt and weld, making it impossible to pass or cut the current. Ta.

[Purpose of invention]

The present invention was developed in view of the above-mentioned circumstances, and aims to provide a vacuum valve that prevents deformation of the current-carrying shaft due to impact loads during opening and closing operations, and further improves impact fatigue strength. .

[Summary of the idea]

The present invention is characterized in that the strength of the current-carrying shafts on the fixed and movable sides of the vacuum valve is improved by coating the entire length of the current-carrying shafts with a brazing material.

[Example of idea]

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, a pair of electrodes 4a and 4b are provided facing each other in a vacuum container 3 whose openings at both ends of an insulating container 1 are closed by end plates 2a and 2b.
They are attached to the ends of the current-carrying shafts 6 and 7 inserted into the vacuum container 3 by penetrating through the shafts a and 2b, respectively.
Current is turned on and off by moving one of the current-carrying shafts 7 in the axial direction by an operation mechanism (not shown). Here, a bellows 8 is provided between the end plate 2b and the current-carrying shaft 7 in order to keep the inside of the vacuum container 3 airtight and to allow the current-carrying shaft 7 to move in the axial direction. In addition, wire-shaped silver brazing material is wrapped around the outer peripheral surfaces of the current-carrying shafts 6 and 7, and maintained in a vacuum furnace under the same temperature conditions as for silver brazing, so that the silver brazing material 9 is uniformly coated on the outer peripheral surfaces. It's made to flow.
In this way, as shown in FIG.
A new alloy layer #9b is formed at the boundary between the copper material 7 and the silver brazing material 9a.

This alloy layer #9b is a Cu-rich α solid solution and generally has mechanical properties that are harder than copper materials. When coating the outer circumferential surfaces of the current-carrying shafts 6 and 7 with the silver brazing material 9, unlike general brazing, which is sealed, the silver solder after forming a copper-based solid solution flows down, so that the surface layer is The thickness of silver solder is measured in microns. This thin and hard part has the effect of reducing the ductility of the copper material, and the current-carrying shafts 6 and 7
It exhibits mechanical properties different from those of copper, making it difficult to deform. The above explanation is based on the case where silver solder is used for brazing, but it is also possible to use copper-phosphorus brazing material to create an intermetallic compound of Cu ₃ P in the boundary layer, or gold solder or other low melting point solder. The same applies when using materials.

Furthermore, the same temperature conditions as those for brazing can be applied after the current-carrying shafts 6 and 7 are plated with silver brazing material.

Figure 3 shows that the impact fatigue strength until the current-carrying shafts 6, 7 fatigue due to the impact load generated on the current-carrying shafts 6, 7 during repeated opening and closing operations of the vacuum valve is as follows:
According to experiments conducted by the inventors of the present invention, the fatigue life is improved when the current-carrying shafts 6 and 7 are coated with silver brazing material than when they are made of copper. This case is also due to the effect of the copper-based solid solution mentioned above.

[Effect of idea]

The present invention improves impact fatigue strength and reduces deformation by simply coating the current-carrying shaft with a brazing material, making it possible to provide a vacuum valve with a mechanically long life.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an embodiment of the vacuum valve of the present invention, FIG. 2 is a cross-sectional view of the current-carrying shaft of the present invention,
FIG. 3 is a characteristic diagram of fatigue strength of the present invention. 6, 7... Current-carrying shaft, 9... Brazing metal.

Claims (1)

[Scope of utility model registration request] What is claimed is: 1. A vacuum valve comprising a pair of removable electrodes provided in a vacuum container, characterized in that the outer surface of a current-carrying shaft to which the electrodes are attached is coated with a brazing material.