JPH0719518B2 - Vacuum interrupter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a vacuum interrupter.

B. Outline of the Invention In the vacuum interrupter of the present invention, a pair of electrodes are provided in a metal tank of a vacuum container in which an insulating cylinder is closed by a metal end plate and a metal tank, and a fixed electrode rod is inserted from the end plate to a fixed electrode rod. By introducing shorter movable electrode rods from the metal tanks respectively, forming a large diameter portion on the outer end side of the fixed electrode rod, and using the bellows as an internal vacuum type, insulation is stable and the disconnection performance is improved. Without any decrease, the strength of the fixed electrode itself and the strength of the joint between it and the member to be fixed are increased to prevent uneven contact of the electrode, reduce the weight load on the operating mechanism, and prevent damage to the bellows. Is.

C. Conventional Technology Conventionally, vacuum interrupters such as those disclosed in Japanese Patent Laid-Open No. 59-79921 are known.

In this vacuum interrupter, as shown in FIG. 2, one end of the insulating cylinder 1 is closed by an end plate 3 made of metal via a sealing metal 2 and the other end of the insulating cylinder 1 is interposed by a sealing metal fitting 4. A metal container 5 having a bottom cylindrical shape is closed, and a high vacuum is formed inside to form a vacuum container 6. Then, in the metal tank 5 of the vacuum container 6, a pair of fixed and movable electrodes 7,
8 are arranged.

The fixed electrode rod 9 having the fixed electrode 7 fixed to the inner end thereof is introduced into the metal tank 5 through the bottom portion 5a of the metal tank 5 in an airtight manner. A movable electrode rod 10 having a movable electrode 8 fixed to its inner end penetrates the end plate 3 in an airtight manner via a bellows 11, passes through the insulating cylinder 1, and is introduced into the metal tank 5. That is, the movable electrode rod 10 is longer than the fixed electrode rod 9. Further, the bellows 11 is provided so as to project from the end plate 3 into the insulating cylinder 1 so that the inside thereof is on the atmosphere side. The bellows 11 is provided at a position farthest from both electrodes 7 and 8 so that the metal vapor does not easily adhere to the bellows 11.

On the other hand, an outer lead conductor 12 extending in a direction orthogonal to the fixed electrode rod 9 is connected to the outer end portion of the fixed electrode rod 9 via a coil 13. The coil 13 is formed into a substantially cylindrical shape, one end of which is connected to the outer end of the fixed electrode rod 9 and the other end of which is connected to the end of the external lead conductor 12, and both electrodes 7, outside the metal tank 5. Surrounding eight. The coil 13 generates a magnetic field in the axial direction parallel to the arc. Further, an outer lead conductor 14 extending parallel to the outer lead conductor 12 is connected to the outer end portion of the movable electrode rod 10 via a sliding contact 15.

In FIG. 2, 16 is a main shield having one end fixed to the inner peripheral surface of the metal tank 5 and covering a part of the insulating cylinder 1 from the inside. Further, 17 is a bellows shield and 18 is an auxiliary shield.

D. Problems to be Solved by the Invention In the conventional vacuum interrupter described above, the external lead conductor is used.
12-Coil 13-Fixed electrode rod 9-Fixed and movable electrodes 7,8-Movable electrode rod 10-Sliding contact 15-Current flows through the external lead conductor 14. As a result, the fixed and movable electrode rods 9 and 10 apply a radial electromagnetic force in the opposite direction (leftward direction in FIG. 2) to the extraction method of the external extraction conductors 12 and 14 according to Fleming's left-hand rule. receive. Both electrodes 7 and 8 are provided in the metal tank 5 at one end side of the vacuum container 6 (one end side of the insulating cylinder 1), and the bellows 11 are provided in consideration of prevention of metal vapor adhesion. It is provided at a position farthest from the electrodes 7 and 8 (on the other end side of the insulating cylinder 1). For this reason, the movable electrode rod 10 penetrates the end plate 3, passes through the inside of the insulating cylinder 1 and extends into the inside of the metal tank 5, and its length is extremely long.

Therefore, the movable electrode rod 10 is greatly affected by the electromagnetic force and causes radial runout during the opening / closing operation. Due to this deflection, the gap between the movable electrode rod 10 which is a different potential member and the main shield 16 is narrowed, and the withstand voltage characteristic is deteriorated. Further, when the movable electrode rod 10 is tilted, both electrodes 7 and 8 are in a single contact (point contact) state on the outer peripheral side thereof, and the impact stress at the time of injection is concentrated only at the contact point, resulting in Electrodes 7 and 8 cracked over the years,
There was a problem that the chipping performance was deteriorated due to chipping or damage. Furthermore, since the length of the movable electrode rod 10 is extremely long, the weight of the movable portion becomes heavy and the weight load of the operating mechanism becomes large.

On the other hand, the metal vapor generated when the electrodes 7 and 8 are opened mainly moves to the insulating cylinder 1 side where the vacuum space is large, because the back vacuum space of the fixed electrode 7 is small. For this reason, despite the provision of the bellows shield 17, a part of the scattered metal vapor adhered to the surface of the bellows 11 due to a large number of times of opening and closing. Moreover, the bellows 11 is configured to contract when the contact is opened. Therefore, the ridges of the bellows 11 were welded to each other by the adhered metal vapor, causing a leak.

E. Means for Solving Problems In order to solve the above-mentioned conventional problems, the present invention provides
The insulating cylinder is closed by a metal end plate and a metal tank to form a vacuum container, and the electrodes are arranged in the metal tank. And
The fixed electrode rod is introduced from the metal end plate, and the movable electrode rod is introduced from the bottom of the metal tank via the bellows. The fixed electrode rod extends from the metal end plate through the insulating cylinder into the metal tank, and is longer than the movable electrode rod. Further, the fixed electrode rod has a large diameter from the inner portion to the outer end portion of the insulating cylinder. Further, the bellows is provided so as to project from the bottom of the metal tank to the outside of the vacuum container so that a vacuum is formed inside.

F. Action In the vacuum interrupter having such a configuration, the fixed electrode rod in the vacuum container is long, while the movable electrode rod is short. Therefore, the influence of the electromagnetic force in the radial direction received by the movable electrode rod by the circuit including the external lead conductor is small, and the movable electrode rod hardly causes radial deflection. As a result, the withstand voltage characteristic is not deteriorated, and the electrode does not come into partial contact. Further, since the weight of the movable part is reduced, the weight load on the operating mechanism is reduced.

On the other hand, the fixed electrode rod and the main shield facing each other at different potentials are
Since they are stationary and fixed, the withstand voltage characteristic between them does not change during the opening / closing operation. Further, since the fixed electrode rod has a large diameter from the inner portion of the insulating cylinder to the outer end portion thereof, the strength and heat dissipation rate of the fixed electrode rod itself are improved, and at the same time, the fixed electrode rod, the metal end plate and the outer lead conductor are provided. The joint strength with

Further, the metal vapor mainly moves to the back side of the large fixed electrode as the vacuum space, and hardly scatters to the back side of the small movable electrode as the vacuum space. Therefore, the metal vapor does not adhere to the bellows protruding from the bottom of the metal tank to the outside of the vacuum container.

G. Example Hereinafter, the present invention will be described in detail based on an example shown in FIG.

The vacuum interrupter of the present invention is, for example, as shown in FIG. 1, a cylindrical insulating cylinder made of glass or ceramics.
Metallized layers 22 are formed on both ends of 21. Then, one end of the insulating cylinder 21 is connected to, for example, copper or Kovar (Fe-Ni-
A bottomed cylinder made of non-magnetic stainless steel with a disc-shaped metal end plate 24 closing a cylindrical sealing metal 23 made of a Co alloy) and the other end of the insulating cylinder 21 via a sealing metal fitting 25. A metal container 26 is closed and the inside is evacuated to a high vacuum (pressure of 6.67 mPa or less) to form a vacuum container 27.

A fixed electrode rod 28 located on the axis of the vacuum container 27 is introduced airtight from the metal end plate 24, and the fixed electrode rod 27 passes through the insulating cylinder 21 and extends into the metal tank 26. .
In addition, a movable electrode rod 29, which can move toward and away from the fixed electrode rod 28, is airtightly introduced into the vacuum container 27 from a bottom portion 26a of a metal tank 26 via a bellows 30 made of metal. The bellows 30 is provided so as to project from the bottom portion 26a of the metal tank 26 to the outside of the vacuum container 27 so that a vacuum is formed inside.

Further, the fixed electrode rod 28 has a large diameter portion 31 formed from the inner portion of the insulating cylinder 21 to the outer end portion thereof. And, a corner portion 31a in the vacuum container 27 in the large diameter portion 31 of the fixed electrode rod 28,
A line segment connecting the fixed electrode rod 28 and the outermost diameter portion of the metallized layer 22 (the lower end side of the insulating cylinder 21 in FIG. 1) at the same potential,
The angle θ with the radial plane is 60 ° or more.

An external lead conductor 32 extending in a direction orthogonal to the fixed electrode rod 28 is connected to an outer end portion of the fixed electrode rod 28. Also,
At the outer end of the movable electrode rod 29, one end of a substantially cylindrical coil 33 that generates a magnetic field parallel to the arc is slidably contacted.
Connected through. The other end of the coil 33 is connected to an end portion of an outer lead conductor 35 extending in parallel with the outer lead conductor 32 connected to the fixed electrode rod 28.

On the other hand, a disk-shaped fixed electrode 36 is fixedly attached to the inner end portion of the fixed electrode rod 28 located in the metal tank 26, and the inner end portion of the movable electrode rod 29 can be attached to and detached from the fixed electrode 36. Disk-shaped movable electrode
37 is fixed. That is, fixed and movable electrodes 36, 37
Is located inside the metal tank 26 and
Surrounded by 33.

In FIG. 1, reference numeral 38 denotes a main shield made of non-magnetic stainless steel which is fixed to the inner peripheral surface of the metal tank 26 and has a tubular shape that partially covers the insulating cylinder 21 from the inside.

In the vacuum interrupter having such a structure, the external lead conductor 35-coil 33-sliding contact 34-movable electrode rod 29-movable and fixed electrodes 37, 36-fixed electrode rod 28-external lead conductor 32 causes Electromagnetic force is generated in the direction opposite to the direction of drawing out the external lead conductors 32, 35 (leftward in FIG. 1). By the way, since the fixed electrode rod 28 has a long axial length (the length from the metal end plate 24 to the fixed electrode 36), it receives a large bending force due to an electromagnetic force, but is fixed stationary. The fixed relationship with other members in the vacuum container 27 does not change. That is, the relationship between the fixed electrode rod 28, which is a different potential member, and the main shield 38 is stable, and the withstand voltage characteristics do not change.

On the other hand, the movable electrode rod 29 has an axial length (sliding contact 34
Since the length from the movable electrode 37 to the movable electrode 37) is short, the bending force is extremely small compared to the fixed side even when an electromagnetic force is applied. Therefore, the movable electrode rod 29 hardly causes the deflection, and as a result, the partial contact of the electrodes 36 and 37 is prevented. Further, even if the movable electrode rod 29 causes a slight radial deflection due to the electromagnetic force, members such as the metal tank 26 located near the movable electrode rod 29 have the same potential as the movable electrode rod 29. Therefore, the withstand voltage characteristic does not deteriorate. further,
Since the movable electrode rod 29 has a short length and the weight of the movable portion is light, the weight load on the operating mechanism is significantly reduced.

Further, since the large diameter portion 31 is formed in the fixed electrode rod 28, the strength and heat dissipation rate of the fixed electrode rod 28 itself are improved, and the fixed electrode rod 28 and the metal end plate 24 and the external lead conductor 32 are Bonding strength is improved. And in this embodiment,
The angle θ formed by the line segment connecting the corner portion 31a of the large diameter portion 31 of the fixed electrode rod 28 and the outermost diameter portion of the metallized layer 22 with the radial plane is
It is more than 60 °. Therefore, the equipotential lines do not cross the metallized layer 22 and the electric field is not concentrated in the metallized layer 22.

On the other hand, the metal vapor generated at the time of opening the electrodes 36, 37 mainly moves to the back side of the fixed electrode 36 and hardly scatters to the back side of the movable electrode 37. Moreover, the bellows 30 is configured so as to operate in the extending direction when the contact is opened. Therefore, the metal vapor does not adhere to the bellows 30, and even if the metal vapor adheres, the peaks of the bellows 30 do not weld to each other to cause a leak.

In the above embodiment, the sealing metal fitting 23 and the insulating cylinder 21 are joined by a knife edge seal, but the present invention is not limited to this embodiment, and the insulating metal fitting 21 is attached to the insulating metal fitting 21.
One end of 23 may be buried and joined. In this case, the angle formed by the line segment connecting the corner 31a of the large-diameter portion 31 of the fixed electrode rod 28 and the end of the end of the sealing metal fitting 23 on the embedded side with the radial plane is
When the angle is 60 ° or more, the electric field is not concentrated at the tip of the sealing metal member 23.

H. Effects of the Invention As described above, according to the vacuum interrupter of the present invention, a pair of electrodes is provided in the metal tank of the vacuum container in which the insulating cylinder is closed by the metal end plate and the bottomed cylindrical metal tank, Introduce the fixed electrode rod from the end plate and the movable electrode rod from the bottom of the metal tank so that each inner end is located inside the metal tank. Since the movable electrode rod is shorter than the fixed electrode rod and the bellows is an internal vacuum type, the relationship between the fixed electrode rod and the main shield facing each other at different potentials is fixed, and the electromagnetic force is applied during opening / closing operation. The relationship between the two is fixed even under the influence of, and the withstand voltage characteristics do not deteriorate.

Since the movable electrode rod, which is easily moved by the influence of the electromagnetic force of the circuit, has a length sufficiently shorter than that of the fixed electrode rod, the movable electrode rod is hardly affected by the electromagnetic force and rarely causes radial runout. Further, even if the movable electrode rod slightly oscillates in the radial direction, the member located in the vicinity of the movable electrode rod has the same potential as the movable electrode rod, so that the withstand voltage characteristic does not deteriorate.

Since the movable electrode bar is less prone to shake, point contact due to one-sided contact of the electrode can be prevented, the electrode is not damaged, and there is no deterioration in the breaking performance.

Since the length of the movable electrode rod is short, the weight of the movable portion is light, and the weight load on the operating mechanism is significantly reduced.

The strength and heat dissipation rate of the fixed electrode rod itself are improved, and the joint strength between the fixed electrode rod and the metal end plate and the outer lead conductor is improved.

Since the back vacuum space of the movable electrode is small and the metal vapor when opening and closing is mainly scattered to the back vacuum space of the fixed electrode, the metal vapor does not adhere to the bellows. Since the bellows is an internal vacuum type and protrudes to the outside of the vacuum container and operates in the extending direction at the time of opening the electrode, even if metal vapor adheres, the bellows peaks are not welded to each other to cause a leak.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view showing an embodiment of a vacuum interrupter of the present invention, and FIG. 2 is a vertical sectional front view of a conventional vacuum interrupter. 21 ... Insulation cylinder, 24 ... Metal end plate, 26 ... Metal tank, 26
a ... bottom, 27 ... vacuum container, 28 ... fixed electrode rod, 29 ...
… Movable electrode rod, 30 …… bellows, 31 …… large diameter part, 36 ……
Fixed electrode, 37 ... movable electrode.

Claims (1)

[Claims] 1. A vacuum container is formed by closing one end of an insulating cylinder with a metal end plate and closing the other end with a bottomed cylindrical metal tank.
A pair of electrodes is arranged in the metal tank of this vacuum container, and a fixed electrode rod having one of the electrodes fixedly fixed to the inner end is provided through the metal end plate in an airtight manner and by inserting the insulating cylinder,
A large diameter portion is formed from the inner portion of the fixed electrode rod to the outer end portion, the other electrode is fixed to the inner end portion, and a movable electrode rod shorter than the fixed electrode rod is provided at the bottom of the metal tank via a bellows. The vacuum interrupter is characterized in that the bellows is provided so as to penetrate airtightly, and the bellows is provided so as to project from the bottom of the metal tank to the outside of the vacuum container so that a vacuum is formed inside.