JPS639969Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a vacuum valve in which an insulating cylinder for reinforcing creeping insulation is attached to the outside of a vacuum vessel.

As is well known, a vacuum valve is made by fixing Kovar metal rings to the top and bottom ends of a cylindrical vacuum container made of ceramic, hard glass, etc. by vapor deposition or embedding, respectively, and welding metal flanges to these rings. The lead portion of a fixed electrode is welded to the flange, and the lead portion of a movable electrode that comes into contact with and separated from the flange is welded to the other metal flange via a bellows for sealing, and the interior is treated to a high degree of vacuum.

In this way, vacuum valves open and close their electrodes in a high vacuum, so a slight opening between the electrodes allows the high voltage circuit to be broken or disconnected, and the vacuum container housing the electrodes can also be made more compact. can.

However, since the vacuum container is small, the creepage insulation distance on the outside is short, and when used in a high voltage circuit, when atmospheric contaminants (humidity, dust, etc.) adhere to the container surface, the withstand voltage decreases and external flashover occurs. There is a risk of causing

On the other hand, as a means of solving the above-mentioned drawbacks, it is known that an insulating jacket is integrally formed on the outside of the vacuum vessel by casting an epoxy resin or the like to provide a substantially sufficient creeping insulation length in consideration of contamination conditions. There is.
However, in such a structure, the coefficient of thermal expansion of the insulating jacket differs from that of the ceramic material of the vacuum container, so cracks may occur due to the generation of thermal stress, and the interface may peel off due to impact during opening and closing operations. It lacks reliability as a product.

In addition, as a basis for a structure that eliminates the above-mentioned problems such as cracks, an insulating tube with an epoxy resin that substantially increases the external creeping insulation length is manufactured in advance by casting, and this is placed outside the vacuum container. There are also products in which rubber or the like is poured as an elastic material into the gap between the container and the vacuum container and then hardened. However, even with this structure, if the gap is large and the elastic material is thick, the shrinkage stress during hardening will easily cause cracks in the insulating tube, and if the gap is made small, the layer of elastic material will become thinner and its ability to cushion shocks will be reduced. Otherwise, it may cause peeling.

The present invention was developed in view of the above circumstances, and aims to provide a highly reliable vacuum valve that can reliably guarantee the withstand voltage between external electrodes without the risk of cracking or peeling of the insulation for reinforcing external creeping insulation. purpose.

An embodiment of the present invention will be described below with reference to the drawings. In the figure, 11 is a vacuum valve configured by providing a fixed electrode 13 and a movable electrode 14 in a vacuum container 12 so as to be able to come into contact with and separate from it in the axial direction, and 15 is a vacuum container 1.
A rubber layer is integrally formed on the outer circumferential surface of 2 by casting, and the outer circumferential surface has a taper corresponding to the draft angle of the mold during casting. Reference numeral 17 is an insulating cylinder made of epoxy resin or the like, which has appropriate pleats 18 on the outer periphery and is molded in advance by casting. As shown in the figure, it is fitted onto the outside of the rubber layer 16 and brought into close contact. The mating surfaces of the rubber layer 16 and the insulating cylinder 17 are coated with grease compound 1 in advance.
9 (Toshiba Silicone Co., Ltd. trade name: TSK551, etc.) to prevent contaminants from entering.

According to the present invention configured as described above, since the insulating tube can be tightly fitted to the outside of the rubber layer and assembled, there is no risk of cracking or peeling due to thermal stress during casting unlike in the conventional method. The elasticity of the rubber layer prevents damage from impact during opening and closing, making it highly reliable. In addition, since the insulating tube is integrally provided with a rubber layer interposed therebetween, the external creeping insulation is strengthened, and the withstand voltage between the external electrodes can be reliably guaranteed even in the event of contamination.

[Brief explanation of drawings]

The figure is a sectional view showing an embodiment of the vacuum valve according to the present invention. 12... Vacuum container, 15... Rubber layer, 17...
Insulating tube.

Claims (1)

[Scope of utility model registration request] It is characterized by comprising a rubber layer integrally formed on the outer peripheral surface of the vacuum container and an insulating tube fitted on the outside of this rubber layer, and a fitting surface of the rubber layer and the insulating tube is tapered. vacuum valve.