JPS5845766B2 - Vacuum cutter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vacuum breaker, and more particularly, to a vacuum breaker in which a metal bellows has a longer service life.

In general, a vacuum breaker has fixed and movable leads equipped with movable electrodes placed in a vacuum container evacuated to a high vacuum and facing each other so as to be able to approach and separate from each other. A metal bellows is used to prevent the vacuum state of the vacuum container from being impaired by the movable reed that is moved back and forth during the reciprocation.

In recent years, as the voltage of vacuum breakers has become higher, the electrode separation length, that is, the moving distance of the movable lead, has increased, and the metal bellows have also become correspondingly longer.

began to be used, and as the travel distance increased, the cutting and input speeds also increased.

However, as the length of the metal bellows increases and the cutting and closing speeds also increase, the metal bellows becomes
Due to the action of atmospheric pressure and vacuum pressure or its own elastic force, it does not shrink normally and instead meanderes as if a force perpendicular to the axial direction is applied, causing so-called buckling.

Therefore, the metal bellows may be damaged early due to sliding contact between the inner diameter portion of the metal bellows and the movable lead, or the inner diameter portions of the metal bellows or the outer diameter portions of the metal bellows may come into contact with each other and spark discharge may occur, causing a hole in the metal bellows. There are problems such as leakage and loss of airtightness.

In order to deal with this problem, there is a known method in which a pipe made of synthetic resin is inserted between the movable reed and the metal bellows, and the base of the pipe is fixed to the vacuum container to prevent the metal bellows from buckling. However, since the length of the pipe is regulated by the electrode open length, the pipe is not interposed near the joint to the movable lead in the metal bellows, especially in high-voltage vacuum breakers. However, if the button has a long electrode separation length, there is a problem that buckling occurs in that part, causing early damage to the metal bellows.

The present invention has been made in view of the above-mentioned problems, and the object thereof is to form a material between a metal bellows and a movable lead, which is formed into almost the same shape as the metal bellows, and has a similar length. The purpose of the present invention is to provide a vacuum breaker in which the metallic bellows is prevented from buckling and sliding against the movable lead by interposing a bellows made of resin, thereby extending the life of the metallic bellows.

Hereinafter, one embodiment of the present invention will be described in detail using the drawings.

The figure is a longitudinal cross-sectional view of a vacuum breaker 1 according to the present invention, in which a vacuum container 2 whose interior is maintained at a high vacuum has metal ends attached to both ends of an insulating cylinder 3 formed into a cylindrical shape and made of glass or ceramic. It is constructed by airtightly joining plates 4 and 5 via ring-shaped connecting fittings 6 and 6, and a disk-shaped fixed electrode 7 is fixed to the inner end in the center of one end plate 4. A fixed lead 8 is inserted therethrough and hermetically fixed by brazing or the like.

In addition, a movable lead 11 having a disk-shaped movable electrode 10 fixed to the inner end thereof that makes contact with and separates from the fixed electrode 7 is inserted into the hole 9 bored in the center of the other end plate 5. It is fitted and inserted so that it can freely reciprocate in the axial direction via a fitted bearing 12.

The button 13 in the figure is a bearing holder for fixing the bearing 12, and the movable lead 11 is appropriately connected to an operating mechanism (not shown) provided outside the vacuum container 2.

On the inner surface of the other end plate 5, a ring-shaped bellows fitting 14 is airtightly fixed facing the outer periphery of the hole 9, and on the surface of the movable electrode 10 facing the other end plate 5. In the similar bellows attachment, a metal fitting 15 is hermetically fixed, and in each bellows attachment, the end of a metal bellows 16 of a mold is airtightly attached to the metal fitting 14, 15 by brazing or the like.

A bellows 17 made of synthetic resin is interposed between the metal bellows 16 and the movable lead 11, and the base thereof is appropriately attached to the bearing 12.

The bellows 11 is intended to reduce battering of the metal bellows 16 and to prevent the inner diameter portion of the metal bellows 16 from coming into direct sliding contact with the circumferential surface of the movable reed 11.

It is molded into approximately the same shape as the metal bellows 16 and has the same length, and is made of a synthetic resin with a thermal expansion ratio such as fluororesin that expands when heated and maintains that state after cooling.

Note that in order to interpose the synthetic resin bellows 11 described above between the metal bellows 16 and the movable lead 11, a pipe made of thermally expandable fluororesin is inserted between the metal bellows 16 and the movable lead 11, Metal bellows 1
Experiments have shown that if the wall thickness is less than 0.17n11L, the elasticity will be low and if it exceeds 2mm, the rigidity will increase and it will not function as a bellows. found.

The housing and bellows 11 are not limited to thermally expandable synthetic resin.
For example, a bellows formed by heating a pipe made of a synthetic resin such as ordinary fluororesin to have the inner diameter and outer diameter of the metal bellows 16 may be used.

As described above, the present invention provides a vacuum breaker in which fixed and movable leads equipped with movable electrodes are disposed facing each other in a vacuum container, and the movable leads are airtightly mounted with a metal bellows. Since a bellows made of synthetic resin that is molded into almost the same shape as the metal bellows and has the same length is interposed between the lead and the metal bellows, the knocking force of the metal bellows is reduced, and the metal bellows is also different from the metal bellows. Since the metal bellows is not in direct sliding contact with the movable lead, the life of the metal bellows is extended, and the voltage of the vacuum breaker can be increased.

According to a durability test of a metal bellows with a conventional configuration and a metal bellows with a configuration according to the present invention, an outer diameter of 55 mm was determined.
, 10 conventional metal bellows with an inner diameter of 357n11 and a free length of 250e with a pipe made of synthetic resin inside, an internal pressure of 1 kg/cmG, and a repeated expansion and contraction of 40 mm. The average durability is 5 x 10' to 1 x 105 times, whereas a bellows made of thermally expandable fluororesin with a wall thickness of Q and 9 mm is installed inside the same metal bellows, and the same stroke and the same Those with internal pressure applied are 2X105 to 5X
10" durability, and a bellows made of normal fluororesin with a wall thickness of Q, 9 mm is installed inside the same metal bellows, and the same stroke and internal pressure are applied.
The durability was 1 x 105 to 3 x 105 times.

Therefore, it can be seen that the life of the synthetic resin pipe is much longer than that of a metal bellows.

Further, in the above-mentioned embodiments, the metal bellows of the molding die is described in detail, but the same effect can be achieved in the case of a welded metal bellows, and the bellows made of synthetic resin is double-layered. Alternatively, it may be tripled or divided into multiple parts.

The present invention also includes embodiments in which various changes have been made without departing from the technical scope of the vehicle invention.

BRIEF DESCRIPTION OF THE DRAWINGS The drawing is a longitudinal cross-sectional view of the vacuum breaker according to the present invention. 2... Vacuum container, 7... Fixed electrode, 8... Fixed lead, 10... Movable electrode, 11... Movable lead, 1
6...Metal bellows 7...Bellows.

Claims (1)

[Claims] 1 Fixed and movable leads 8 and 11 equipped with electrodes 7 and 10 that can be moved toward and away from each other are arranged facing each other in a vacuum container 2 so as to be able to move toward and away from each other, and the movable lead 11 is connected to the metal bellows 1.
In the vacuum breaker, a bellows made of synthetic resin is formed between the metal bellows 16 and the movable lead 11 and is molded into approximately the same shape as the metal bellows 16 and has a similar length. 17. A vacuum breaker characterized by having 17 interposed therebetween.