EP0718860A2

EP0718860A2 - Vacuum valve and vacuum circuit breaker utilizing said vacuum valve

Info

Publication number: EP0718860A2
Application number: EP95119341A
Authority: EP
Inventors: Toru Tanimizu; Yoshimi Hakamata; Yoshitomo Goto; Masato Kobayashi; Katsuhiro Komuro
Original assignee: Hitachi Ltd
Current assignee: Hitachi Ltd
Priority date: 1994-12-22
Filing date: 1995-12-07
Publication date: 1996-06-26
Also published as: KR960025890A; TW373207B; CN1133416A; EP0718860A3; KR100242330B1; CN1047463C

Abstract

To provide a low cost and a high reliable vacuum valve which can improve the production efficiency and the vacuum tightness of the vacuum valve, and a vacuum circuit breaker using the vacuum valve. Inside a insulating housing 1, a pair of separable conductors in the central axial direction of the sealed vacuum vessel composed of a stationary conductor 3 and amovable conductor 5 are disposed. A stationary conductor 3 having an external surface being broader than a contact area of the separable conductors 3, 5 is jointed to the lower end portion 1B of the insulating housing 1 and the lower end portion 1B of the insulating housing 1 is sealed thereby.

Description

Background of the Invention

The present invention relates to a vacuum valve, and more particularly to a vacuum valve and a vacuum circuit breaker utilizing the vacuum valve which are suitable for improving its vacuum tightness and production efficiency.
A vacuum valve which is one of important elements in a vacuum circuit breaker used as a circuit breaking portion, and is composed of a vacuum vessel constructed by sealing both ends of a follow cylindrical insulation body with metal end plate and a pair of separable electrodes constructed with a stationary conductor and a movable conductor in the vacuum vessel. The stationary conductor extends in vacuum tightness through the metal end plate in the stationary side, and is disposed in the vacuum vessel. The other electrode is secured to one end of the movable conductor and the movable conductor is connected in vacuum tightness to the other metal end plate via a bellows. Further, for the stationary and the movable conductors, copper was used, and for the metal end plate, in particular, the insulating housing having phosphorus deoxidized copper subjected to thermal stress, an Fe-Hi alloy and an Fe-Ni-Co alloy was used for the metal end plate as disclosed in Japanese Patent Application Laid-Open No.5-41143 (1993).
The above mentioned parts composing the vacuum valve are jointed by brazing which makes use of a metallic solder as a jointing member. The brazing is performed in such a manner that a brazing material is placed between or near the members to be jointed, and is heated at a temperature higher than the melting point of the brazing material in a furnace of non-oxidizing atmosphere such a vacuum furnace or a hydrogen furnace to melt the brazing material to joint the members. Further, TIG welding or plasma welding may be used for jointing the parts composing the vacuum valve.
During production of a vacuum valve, evacuation and brazing are performed at the same time in a vacuum furnace and the inside of the vacuum valve is evacuated and is vacuum sealed. For, example, such a method is disclosed in Japanese Patent Application Laid-Open No.59-175521 (1984) in which after partially assembling the parts the assembly is sealed in vacuum tight in a vacuum furnace. More specifically, a stationary electrode, a stationary conductor and a stationary side metal end plate, and a movable electrode, amovable conductor, a metallic bellows and a movable side end plate are firstly jointed by brazing, subsequently, the stationary side metal end plate and the movable side metal end plate are secondly jointed by brazing in a vacuum furnace to the hollow cylindrical body in such a manner that the stationary side metal end plate and the movable side metal side plate sandwich the insulating housing. After completing the brazing operation silver plating is applied onto the respective external connection terminal portions of the stationary and the movable conductors.
Further, many investigations have been performed for improving vacuum sealing of the vacuum valve until now. Japanese Patent Publication No.5-31245 (1993) discloses one of such investigation results in which an improvement of the brazing material for the jointing member is proposed, and Japanese Patent Application Laid-Open No.2-195618 (1990) discloses another investigation result in which in order to properly guide to be sealed a ring shaped brazing member having a plurality of non-continuous projections along both inner and outer circumferences thereof is used.
For the purpose of vacuum sealing the inside of the vacuum valve, if the parts are jointed through a single brazing operation, no sufficient heat is transmitted through the single brazing operation for jointing both the stationary conductor and the stationary electrode, and the movable conductor and the movable electrode, thereby reliable brazing cannot be obtained. For this reason, the jointing method as explained above was used in which both the stationary electrode, the stationary conductor and the stationary side metal end plate, and the movable electrode, the movable conductor, the metallic bellows and the movable side metal end plate are firstly jointed by brazing, subsequently, the stationary side metal end plate and the movable side metal end plate are secondly jointed by brazing in a vacuum furnace to the insulating housing. With such a method it is found that the brazing operation time is prolonged, which decreases production efficiency (work efficiency) and increases the production cost of such vacuum valves.
Further, in a case where silver plating is applied to the connecting portions with the external conductors of the stationary and the movable conductors after the brazing operation between the parts, a solvent such as acid and a plating electrolyte are coated on the surface of the connecting portions. However, these materials show corrosive property such that when these corrosive materials remain at the vacuum valve, a significant problem such as the vacuum leakage or the like is caused. Therefore, the corrosive materials have to be completely removed, which requires substantial time and further reduces production efficiency (work efficiency) and further increases production cost of the vacuum valve.
Further, when the parts composing the vacuum valve in the vacuum furnace, heat is supplied through radiation to the vacuum valve so as to melt the brazing material of joint member, however copper which is a major component material is likely to reflect the radiation heat and absorbs a limited heat so that it takes a long time for heating the vacuum valve as well as prevent a uniform radiation heat transmission and causes a non-uniform melting of the brazing material of jointing member which induces one of cause of vacuum leakage.
Further, in the vacuum valve as described above, material such as Fe-Ni alloy or Fe-Ni-Co alloy different from the conductor material Cu is used for the metal end plates, and further many constituent parts require to be jointed at portions which require vacuum tight seal, which induces one of causes of vacuum leakage.
Further, although with the conventional method, such as one using an improved brazing material of joint member or guiding members by a plurality of projections formed on the joint member, vacuum tight sealing property of the vacuum valve is improved. However, no vacuum valve having a reliable vacuum tight sealing structure is obtained until now. Accordingly, the vacuum tight sealing property of the conventional vacuum valve is still insufficient.

Summary of the Invention

An object of the present invention is to provide a low cost and high reliable vacuum valve which is improved the production efficiency and the vacuum sealing property of the vacuum valve.
Another object of the present invention is to provide a vacuum circuit breaker having a decreased weight by using the above mentioned vacuum valve.
In order to obtain a vacuum valve which attains the above object, the vacuum valve according to the present invention comprising an insulating housing, a pair of separable conductors having an electrode in the end portion of the conductor disposed within the insulating housing, and a flexible member which connects one of the conductors with one end of the insulating housing in such a manner as to allow the one of the conductor to separate from the other of the conductor while maintaining vacuum tightness inside the hollow cylindrical insulator body, wherein the other end of the insulating housing is sealed in vacuum tight by the other conductor.
In order to obtain a vacuum valve which attains the above object, the vacuum valve according to the present invention comprising a pair of separable conductors having an electrode in the end portion of the conductor disposed within an insulating housing, and one end side of the insulating housing is sealed in vacuum tight by one of the conductors, an end plate and a bellows, wherein the other end side of the insulating housing is sealed in vacuum tight by the other of the conductors.
In order to obtain a vacuum valve which attains the above object, the vacuum valve according to the present invention comprising a pair of separable conductors composed of a stationary conductor and a movable conductor having an electrode in the end portion of the conductor disposed within an insulating housing, and one end side of the insulating housing is sealed in vacuum tight by one of the conductors, an end plate and a bellows, wherein the other end side of the insulating housing is sealed in vacuum tight by the stationary conductor.
It is preferable that the material near the joint portion between the other end side of the insulating housing and the stationary conductor is an alloy having Cu as the major component containing Cr of 1 to 10 wt%.
Further, it is preferable that the cross-sectional area near the joint portion between the other end side of the insulating housing and the stationary conductor is varied depending on variation of magnitude of bending moment to the distance near the joint portion.
Further, it is preferable that the stationary conductor has a groove at the end thereof which forms a joint portion with the other end side of the insulating housing, and a projecting surface having a level higher than the level of the joint portion at the opposite side of the joint portion.
In order to obtain a vacuum valve which attains the above object, the vacuum valve according to the present invention comprising a pair of separable conductors composed of a stationary conductor and a movable conductor having an electrode in the end portion of the conductor disposed within an insulating housing, and one end side of the insulating housing is sealed in vacuum tight by one of the conductors, an end plate and a bellows, wherein the other end side of the insulating housing is sealed in vacuum tight by the stationary conductor, and at least one of the section between the one end side of the insulating housing and the movable conductor and the section between the other end side of the insulating housing and the stationary conductor is multiply sealed in vacuum tight.
It is preferable that at least two joint portions are provided between the other end side of the insulating housing and the stationary conductor, and the space between the joint portions is evacuated.
Further it is preferable that the bellows is composed of a plurality of bellows, and one ends of the plurality of bellows are jointed to the movable conductor, and at least one of the other ends of the plurality of bellows is jointed to the one end side of the insulating housing, and the space between the plurality of bellows is evacuated.
In order to obtain a vacuum valve which attains the above object, the vacuum valve according to the present invention comprising a pair of separable conductors composed of a stationary conductor and a movable conductor having electrodes in the end portions of the conductors facing each other disposed within an insulating housing, and one end side of the insulating housing is sealed in vacuum tight by one of the conductors, an end plate and a bellows, wherein the other end side of the insulating housing is sealed in vacuum tight by the stationary conductor, and the other end side of the insulating housing and the stationary conductor are jointed with a joint member formed a ring shape for guiding the stationary conductor with the inner circumference having a bent portion for guiding the insulating housing with the outer circumference and projections arranged in the circumferential direction with a given spacing.
It is preferable that the bellows is composed of a plurality of bellows, and one ends of the plurality of bellows are jointed to the movable conductor, and at least one of the other ends of the plurality of bellows is jointed to the one end side of the insulating housing, and the one end side of the insulating housing and the other end of at least one of the plurality of bellows are jointed with a joint member formed a ring shape for guiding the stationary conductor with the inner circumference having a bent portion for guiding the insulating housing with the outer circumference and projections arranged in the circumferential direction with a given spacing.
Further, it is preferable that the bellows is composed of a plurality of bellows, and one ends of the plurality of bellows are jointed to the movable conductor, and at least one of the other ends of the plurality of bellows is jointed to the one end side of the insulating housing, and the metal end plate and the other end of at least one of the plurality of bellows are jointed with a joint member having a bent portion formed a ring shape for guiding the metal end plate with the inner circumference and the insulating housing with the outer circumference, a step portion for guiding the other end of at least one of the plurality of bellows, and projections arranged in the circumferential direction with a given spacing.
In order to obtain a manufacturing method of vacuum valve which attains the above object, on an end portion of a stationary conductor a joint member is placed, on which the lower end portion of an insulating housing is placed, then a movable conductor is inserted into the insulating housing, and joint members are respectively placed on a bellows jointing portion of the movable conductor and the upper end portion of the insulating housing, then one end of the bellows is placed on the bellow jointing portion via the joint member and one end of a metal end plate is placed on the upper end portion of the insulating housing via the jointing member, then a jointing member is placed on the other end of the metal end plate and the other end of the bellows is placed on the jointing member, thereafter the assembly is heated in a vacuum furnace at a temperature higher than the melting temperature of the joint member while a pressure is being applied to the jointing portion of the bellows from the outside, thereby the vacuum valve is produced.
It is preferable that the vacuum valve is manufactured by plating the stationary conductor with nickel, and contacting a heater onto the nickel plated portion to be heated by thermal conduction.
In order to obtain a vacuum circuit breaker which attains the above object, the vacuum circuit breaker according to the present invention comprises at least one of vacuum valves constructed by tightly sealing a one end of an insulating housing with conductor, external conductors extending from the both ends of the vacuum valve, contacting terminals connected to the external conductors for electrically connecting the external and the vacuum valve, and an operating mechanism for operating the vacuum valve.
The one end of the insulating housing is sealed in vacuum tight by the stationary conductor, the conventional metal end plate is eliminated which is connected in vacuum tight to the stationary conductor as well as seals in vacuum tight of the lower end of the insulating housing. Thereby, number of jointing portions between parts which form the vacuum valve is decreased and the portions which require vacuum tight seals are accordingly reduced.
Further, the cross sectional area of the stationary conductor near the jointing portion with the insulating housing is varied depending on the variation of bending moment thereof with respect to distance to the jointing portion as well as the material of the stationary conductor near the jointing portion is composed of Cu alloy containing Cr of 1 to 10 wt%. Thereby, the mechanical strength of that portion is increased by about 40%.
Further, the stationary conductor is provided with the projecting surface having a level higher than that of the jointing portion with the lower end portion of the insulating housing. thereby, electrical field concentration at top end portion of the brazed material caused during voltage application is moderated.
Further, at least one of the section between the one end side of the insulating housing and the movable conductor and the section between the other end side of the insulating housing and the stationary conductor is multiply sealed in vacuum tight, that is, at least two jointing portions between the stationary conductor and the insulating housing are sealed in vacuum tight or one ends of a plurality of bellows are sealed in vacuum tight to the movable conductor and at least on of the other ends of the plurality of bellows is sealed in vacuum tight to the insulating housing. Thereby, vacuum tightness of the possible vacuum leakage portions is enhanced.
Further, the jointing portion between the lower end portion of the insulating housing and the stationary conductor are jointed with a joint member formed a ring shape for guiding the stationary conductor with the inner circumference having a bent portion for guiding the insulating housing with the outer circumference and projections arranged in the circumferential direction with a given spacing. thereby, evacuation and maintenance of vacuum at the double sealed structure portions are enabled. Further, with the provision of the bent portions the jointing portions between parts are strengthened and vacuum tightness of the possible vacuum leakage portions is enhanced.
Still further, with this structure, the brazing material is uniformly spread over the jointing portions between the parts and reliable portions are obtained.
Further, the bellows is composed of a plurality of bellows, and at least one of the other ends of the plurality of bellows is jointed to the one end side of the insulating housing, and the one end side of the insulating housing and the other end of at least one of the plurality of bellows are jointed with a joint member formed a ring shape for guiding the stationary conductor with the inner circumference having a bent portion for guiding the insulating housing with the outer circumference and projections arranged in the circumferential direction with a given spacing, and at least one of the other ends of the plurality of bellows is jointed to the one end side of the insulating housing, and the metal end plate and the other end of at least one of the plurality of bellows are jointed with a joint member having a bent portion formed a ring shape for guiding the metal end plate with the inner circumference and the insulating housing with the outer circumference, a step portion for guiding the other end of at least one of the plurality of bellows, and projections arranged in the circumferential direction with a given spacing. Thereby, evacuation and maintenance of vacuum in the space between the plurality of bellows are enabled. Still further, with this structure the brazing material is uniformly spread over the jointing portions between parts and reliable jointing positions are obtained.
In the manufacturing of a vacuum valve, on an end portion of a stationary conductor a joint member is placed, on which the lower end portion of an insulating housing is placed, then a movable conductor is inserted into the insulating housing, and joint members are respectively placed on a bellows jointing portion of the movable conductor and the upper end portion of the insulating housing, then one end of the bellows is placed on the bellow jointing portion via the joint member and one end of a metal end plate is placed on the upper end portion of the insulating housing via the jointing member, then a jointing member is placed on the other end of the metal end plate and the other end of the bellows is placed on the jointing member, thereafter the assembly is heated in a vacuum furnace at a temperature higher than the melting temperature of the joint member while a pressure is being applied to the jointing portion of the bellows from the outside, thereby the vacuum valve is produced. Thereby, the entire parts of the vacuum valve are assembled in order beginning from the stationary conductor located at the bottom portion while sandwiching the respective jointing members therebetween. As a result, the vacuum valve is produced by a single jointing operation.
Further, the vacuum valve is manufactured by plating the stationary conductor with nickel, and contacting a heater onto the nickel plated portion to be heated by thermal conduction. Thereby, the vacuum valve assembly effectively absorbs the heat from the heater to thereby shorten the heating time thereof.
Further, the silver plating time required for the conventional manufacturing of vacuum valve is also eliminated. As a result, the production time for the vacuum valve is shortened.

Brief Description of the Drawings

FIG.1 is a vertical cross-sectional view showing the characteristic structure of one embodiment of a vacuum valve in accordance with the present invention.
FIG.2 is a graph showing the relationship between size, bending moment and cross-sectional area of the jointing portion of the stationary conductor in the vacuum valve as shown in FIG.1.
FIG.3 is a vertical cross-sectional view for explaining a manufacturing method of the vacuum valve as shown in FIG.1.
FIG.4 is a vertical cross-sectional view showing the characteristic structure of anther embodiment of a vacuum valve in accordance with the present invention.
FIG.5 is an enlarged view showing the lower end joint portion of the insulating housing in the vacuum valve as shown in FIG.4.
FIG.6 is an enlarged view showing the upper end joint portion of the insulating housing in the vacuum valve as shown in FIG.4.
FIG.7 is a perspective view showing the structure of one joint member used in one of the jointing position of FIG.6.
FIG.8 is a perspective view showing the structure of one joint member used in one of the jointing position of FIG.6.
FIG.9 is a perspective view showing the structure of one joint member used in one of the jointing position of FIG.5.
FIG.10 is a cross-sectional view showing a vacuum circuit breaker using a vacuum valve of FIG.1 to FIG.4.

Detailed Description of the Preferred Embodiments

Embodiments of the present invention will be described in detail below, referring to the accompanying drawings.
FIG.1 is a vertical cross-sectional view showing a first embodiment of a vacuum valve in accordance with the present invention. FIG.2 is a graph showing the relationship between size, bending moment and cross-sectional area of the jointing portion of the stationary conductor in the vacuum valve as shown in FIG.1.
Inside an insulating housing 1, a pair of separable conductors in the central axial direction of the sealed vacuum vessel composed of a stationary conductor 3 and amovable conductor 5 are disposed.
One end of a metal end plate 7 in the movable conductor side is jointed to an upper end portion 1A of the insulating housing 1, one end (the movable conductor side 6B of the metal end plate) of the flexible member, that is, bellows 6 is jointed to the other side of the metal end plate 7 (the movable conductor side 6A) is jointed to the movable conductor 5 so as to seal the upper end portion 1A of the insulating housing 1. The bellows 6 keeps the inside of vacuum valve 100 in vacuum even when the movable conductor 5 is operated.
A stationary conductor 3 is jointed to the lower end portion 1B of the insulating housing 1 and the lower end portion 1B of the insulating housing 1 is sealed thereby.
To one end of the stationary conductor 3, a stationary electrode 2 is jointed and the other end thereof is provided with a connecting screw portion 3F for connecting an external conductor (not shown), thereby there is formed a rod-shaped conductor which extends from the stationary electrode 2 through the stationary electrode 2 to a stationary side electrical contacting surface 3E which allows current to flow therethrough.
The stationary side electrical contacting surface 3E of the stationary conductor 3 is formed in an umbrella-shape extending radially, and at the end of the radially extended portion a groove 3C is formed, and through the formation of the groove 3C, a jointing base portion 3B and a jointing end portion 3A, which is jointed to the lower end 1B of the insulating housing at the top thereof, are formed.
The thermal expansion coefficient difference of the materials at the jointing portion is controlled by reducing the thickness of the jointing end portion 3A near the jointing portion. However, such thickness reduction causes decrease of mechanical strength of those portions. Therefore, in the present embodiment, a reinforced copper of Cu alloy containing Cr of 1 to 10 wt% is used for the portion near the jointing end portion 3A in order to obtain a required strength. Further, the cross-sectional area (S) from the joint base portion 3B to the joint end portion 3A is gradually decreased from the joint base portion 3B depending on the variation of bending moment (M) acting thereon with regard to the distance (1) from the joint base portion 3B to the joint end portion 3A as shown in FIG.2. More specifically, the thickness reduces gradually from the thickness t1 at the joint base position 3B to the thickness t2 at the top of the joint end portion 3A.
Further, at the central axis side of the stationary conductor 3 (opposite side of the jointing base 3B and the jointing end portion 3A interposing the groove 3C), a projecting surface 3D, which projects toward the stationary electrode 2 higher than the jointing end portion 3A, is formed, and further an inclining portion 3G having expanded diameters, which extends into the central portion of the stationary conductor 3 from the projecting surface 3D, is formed. Still further, onto the surface of the stationary conductor 3 nickel plating is applied.
At one end (the side of the stationary conductor 3) of the movable conductor 5, a movable electrode 4 is jointed and at the other end thereof a connecting screw portion 5F is provided which is for connecting with an external conductor (not shown). Thereby, there is formed a rod-shaped conductor which extends from the movable electrode 4 through the movable conductor 5 to a movable side electrical contacting surface 5E which allows current to flow therethrough. At the intermediate portion of the movable conductor, a bellows protecting shield 5A projecting outward is formed so as to have a larger outer diameter than that of the bellows 6, and at the root portion of the protecting shield a bellows joint portion 5B is provided, and the bellows joint portion can joint the movable conductor side 6A of the bellows 6.
Further, the movable conductor 5 is made of a reinforced copper of Cu alloy containing Cr of 1 to 10 wt% like that near the jointing end portion 3A of the stationary conductor 3 as described above and is also plated with nickel like the stationary conductor 3 as described above.
The bellows 6 is provided with the movable conductor side end 6A at one end of thereof which is adapted to be jointed to the bellows jointing portion 5B and a metal end plate side end 6B at the other end which is adapted to be jointed to the movable conductor side metal end plate 7.
The movable conductor side metal end plate 7 is adapted to joint to the metal end plate side end 6B of the bellows 6 at the inner circumference thereof and to the upper end 1A of the insulating housing 1 at the outer circumference thereof.
Further, a shield 8 surrounding the stationary electrode 2 and the movable electrode 4 is supported by the inner wall of the insulating housing 1.
Now, a manufacturing method of the above mentioned vacuum valve will be described below, referring to FIG.3. In FIG.3, the vacuum valve is manufactured according to the following steps.

I. Fitting the stationary conductor 3 into a lower supporting stand 31 incorporating a heater 32 inside while contacting the stationary side electrical contacting surface 3E thereto, and placing a brazing member 10 and the stationary electrode 3 above the stationary conductor 3.
II. Placing a ring-shaped brazing member 11 and the lower end portion 1B of the insulating housing 1 on the joint end portion 3A successively, and fitting the insulating housing 1 into the lower supporting stand 31.
III.Fitting a brazing member 12 and movable electrode 4 into the lower portion of the movable conductor 5, and inserting the movable electrode until the movable electrode 4 contacts the stationary electrode 2 to support it.
VI. Placing a brazing member 15 on the upper portion 1A of the insulating housing 1, and further placing the movable conductor side metal end plate 7.
V. Placing a brazing member 13 on the bellows joint portion 5B of the movable conductor 5, and placing movable conductor side end 6A of the bellow 6, then placing a brazing member 14 on the upper portion of the inner circumference of the movable conductor side metal end plate 7, and then placing the metal end plate side end 6B of the bellows 6.
VI. Inserting an upper center pressing metal piece 33 which presses the movable conductor side end 6A of the bellows 6 and the brazing member 13 while heating the same, then placing another upper pressing metal piece 34 on the movable side metal end plate 7, the brazing member 14 and metal end plate side end 6B of the bellows 6 while pressing and heating the same.
VII.Once heating the thus assembled assembly in a vacuum furnace at a temperature higher than the melting temperature of the brazing members to complete a vacuum valve.

According to the present embodiment, since the lower end portion 1B side of the insulating housing 1 is sealed with the stationary conductor 3 , and a wide area from the stationary side electrical contacting surface 3E of the stationary conductor 3 to the jointing end portion 3A is plated with nickel to be directly heated through conduction by the heater 32, the stationary conductor 3 absorbs the heat efficiently and apart of the heat melt the brazing member 11 at the jointing end portion 3A. Most of the heat absorbed from the stationary conductor 3 is used to melt the brazing member 10 of the stationary electrode 2 through the inclining portion 3G having a larger cross-sectional area and also to melt the brazing member 12 at the movable electrode 3 contacting to the stationary electrode 2.
Further, since the heat absorption of the movable conductor 5 is also improved by nickel plating the wide area of the movable conductor 5 covering from the movable conductor side electrical contacting surface 5E to the bellows joint portion 5B and the upper center pressing metal piece 33 pressing directly by its weight the movable conductor side end 6A of the bellows 6, the heat absorbed by the upper center pressing metal piece 33 of radiation heat in vacuum is absorbed into the movable conductor 5 through the nickel plated surface of the movable conductor 5, and the contacting portion between the movable conductor side end 6A of the bellows and the upper center pressing metal piece 33, and the brazing member 13 is melted as well as the brazing member 12 at the movable electrode 4 is heated and melted.
By heating both from the upper and the lower sides as described above, the brazing members 10, 12 and 13 at the inside of the insulating housing 1 are certainly melted to certainly joint the parts with a single jointing operation. Further, because of a shortened heating time as well as a shortened work time, the production efficiency is improved. In addition, because of a uniform heat application to the respective jointed portions a complete jointing can be achieved.
Further according to the present invention, with sealing the lower end portion of the insulating housing 1 using the stationary conductor 3, the metal end plate in the lower end portion of the insulating housing 1 can be eliminated. Thereby, number of positions to be tightly jointed is reduced, and accordingly possible vacuum leakage portions are reduced. Therefore, vacuum tightness of the vacuum valve is improved and the reliability is improved.
With sealing the lower end portion of the insulating housing 1, the thickness of the lower end portion of the insulating housing 1 becomes thicker than the thickness of the upper end portion (the side of the movable conductor 5) of the insulating housing 1, and the strength of the lower end portion side of the insulating housing is enhanced. Therefore, the reliability of the vacuum valve is improved.
Further, in the stationary conductor 3 the cross-sectiona 1 area (S) from the joint base portion 3B to the joint end portion 3A is gradually decreased from the joint base portion 3B depending on the variation of bending moment (M) acting thereon with regard to the distance (1) from the joint base portion 3B to the joint end portion 3A as shown in FIG.2. More specifically, the thickness reduces from the thickness t1 at the joint base portion 3B to the thickness t2 at the top of the joint end portion 3A. Further, since a rein forced copper of Cu alloy containing Cr of 1 to 10 wt% is used for the stationary conductor 3 near the jointing portion with the insulating housing 1, the mechanical strength of those portions of the stationary conductor 3 is reinforced by about 40 % in compared with pure copper conductors. Thereby, the thickness t2 of the joint end portion 3A of the stationary conductor 3 is thinned by about 40 %. accordingly, even when a pressing force is acted onto the movable conductor side metal end plate 7 while fixing the stationary side electrical contacting surface 3E as stationary plane and bending moment are respectively applied to the joint base portion 3B having thickness t1 and to the joint end portion 3A having thickness t2 of the stationary conductor 3, because of the above provision the influence due to thermal expansion coefficient difference between the insulating housing 1 and the joint end portion 3A is reduced, thereby a possibility of break-down of the joint portion is reduced. Further, the thickness of the joint end portion of the stationary conductor 3 can be easily adjusted by modifying the configuration of the groove 3C. Therefore, the reliability of the vacuum valve is improved.
Further, according to the present embodiment, since the projecting surface 3D is designed so as to have a higher level than the level of the joint portion between the lower end portion 1B of the insulating housing 1 and the jointing end portion of the stationary conductor 3, the electrical field at the top end portions of the brazing material during voltage application is moderated. Thereby, corona discharge initiation voltage can be increased and dielectric break-down of the vacuum valve can be prevented. Therefore, the reliability of the vacuum valve is improved.
Further, according to the present embodiment, like the stationary conductor 3 the reinforced copper of Cu alloy containing Cr of 1 to 10 wt% is also used for the movable conductor 5,. Therefore, the mechanical strength of the movable conductor 5 is also reinforced, and the possible deformation due to a large mechanical force during circuit making and breaking operation can be reduced. Therefore, the reliability of the vacuum valve is improved.
Further, according to the present embodiment, since the nickel plating is applied to the stationary conductor 3 and the movable conductor 5 before assembling stage thereof, there is no need to perform silver plating after sealing work. Thereby, manufacturing time for the vacuum valve can be shortened. Therefore, the reliability of the vacuum valve is improved.
The nickel plating never scatters at the brazing temperature of the brazing members, the nickel plating maintains its electrical contacting function even after the sealing operation in the vacuum furnace.
Further, since the nickel plating shows a good wettability with the brazing materials, in particular, with a commonly used silver series brazing material, highly reliable joints both at the portions requiring vacuum tightness and at the portions requiring current conduction.
Still further, nickel shows twice as high withstanding voltage as that of copper in vacuum, the dielectric distance between the shield 8 and the stationary conductor 3 or the movable conductor 5 is shortened. Thereby, the diameter of the vacuum valve can be reduced and the size of the vacuum valve is also reduced.
In the present embodiment, though the use of the above described structure and vacuum tightness of the vacuum valve are improved. However, the vacuum tightness of vacuum valves can be also improved through the use of the following structure which will be described with referring to FIG.4 to FIG.9.
FIG.4 is a vertical cross-sectional view showing the vacuum valve. FIG.5 is an enlarged view showing a jointing portion 16 between the lower end portion 1B of an insulating housing 1 and a stationary conductor 3. FIG.6 is an enlarged view showing a jointing portion 17 between an upper end joint portion 1A of the insulating housing 1 and movable conductor metal end plate 7. FIG.7 to FIG.9 are perspective views showing respective brazing members used as jointing member for the present embodiment. In the present embodiment, the same and equivalent elements as in the previous embodiment are identified by the same reference character, and the explanation thereof is omitted here.
Initially, the upper end portion side 1A of the hollow cylindrical insulator body will be described. In the vacuum valve 100, a bellows , one of the constitutional pars, is constructed in a double structure composed of a movable conductor side bellows 6 and an insulating housing side bellows 6'. In the movable conductor side bellows 6 among these two bellows, the metal end plate side end 6B is jointed at one end of the movable conductor side metal end plate 7 (the opposite end from that jointed to the upper end portion 1A of the insulating housing 1) along the inner circumference thereof and the movable conductor side end 6A is jointed to the bellows jointing portion 5B of the movable conductor 5.
In the insulating housing side bellows 6' the metal end plate side end 6'B is jointed to the upper end portion 1A of the insulating housing 1 and the movable conductor side end 6'A is also jointed to the bellows jointing portion 5B of the movable conductor 5.
On the bellows jointing portion 5B of the movable conductor 5, a step is formed which corresponds to the thickness required when the movable conductor side bellows 6, 6' are brazed, and the movable conductor side bellows 6, 6' are respectively brazed to the bellows joint portion 5B of the movable conductor 3 with pressing pressure P.
For jointing the metal end plate side end 6B of the insulating housing side bellows 6' with the upper end portion 1A of the insulating housing 1 a ring-shaped movable conductor side inner brazing member 26 is used. The outer circumferential portion of the movable conductor side metal end plate 7 is jointed on the metal end plate side end 6'B of the insulating housing side bellows 6, via a ring-shaped movable conductor side outer brazing member 25.
The movable conductor side inner brazing member 26 is formed by a inner circumferential bent portion 20 for firmly guiding the entire inner circumference of the upper end portion 1A of the hollow cylindrical insulator body 1 and a plurality of projections 23 forming a gap for evacuating the space between the plurality of bellows. The projections 23 are formed in a recess and projection shape in a given spacing along the circumferential direction of the insulating housing 1.
The movable conductor side outer brazing member 25 is provided with an outer circumferential bent portion 21 which is designed to firmly guide the entire circumference of the upper end portion 1A of the insulating housing 1, an inner circumferential bent portion 20 which is designed to guide the inner circumference of the movable conductor side metal end plate 7, a step portion 24 which is designed to guide the outer circumference of the movable conductor side inner brazing member 26 and the metal end plate side end 6'B of the insulating housing side bellows 6' and a plurality of projections 23 which are designed to form gap for evacuating the space between the plurality of bellows. The projections 23 are formed in a recess and projection shape along the circumference of the insulating housing 1 at a given spacing.
Therefore, the jointing portion 17 between the movable conductor side metal end plate 7 and the upper end portion 1A of the insulating housing 1 is selected so as to extend from the outer circumference of the upper end portion 1A of the insulating housing 1 to the inside of the metal end plate 7 and to cover the surface of the metal end plate side end 6'B of the insulating housing side bellows 6'.
In the present embodiment, the surfaces of the upper end portion 1A and the metal end plate side end 6'B are continuously coated with the brazing material after the brazing operation.
The lower end portion 1B side of the insulating housing 1 will be described below. The stationary conductor side electrical surface 3E of the stationary conductor 3 is formed by extending in an umbrella-shape and at the end thereof the groove 3C is provided. With this groove 3C projections 3H at the end thereof are formed which are to be jointed in ring-shapes with the lower end portion 1B of the insulating housing 1, and the projections 3H and the lower end portion 1B of the insulating housing 1 are jointed via a ring-shaped stationary conductor side brazing member 22.
The ring-shaped stationary conductor side brazing member 22 is provided with an outer circumferential bent portion 21 which is designed to firmly guide the entire circumference of the lower end portion 1B of the insulating housing 1, an inner circumferential bent portion 20 which is designed to firmly guide the entire circumference of the projection 3H and a plurality of projections 23 which are designed to form gap for evacuating the space between the projection 3H. The projections 23 are formed in a recess and projection shape along the circumference of the insulating housing 1 at a given spacing.
Further, the vacuum valve according to the present embodiment is manufactured by making use of substantially the same manufacturing method as described in connection with the previous embodiment.
According to the present embodiment, the bellows, one of the constitutional members of the vacuum valve is formed in a double structure, that is, formed by the movable conductor side bellows 6 and the insulating housing side bellows 6', and at the end portion of the stationary conductor 3 the groove 3C is formed to form projection 3H, and thereby the vacuum tight sealing portion is doubled. therefore, possible vacuum leakage portions are strengthened. Accordingly, the vacuum tightness of the vacuum valve according to the present embodiment is further enhanced.
According to the present embodiment, since the lower end portion of the insulating housing 1 is sealed, the thickness of the lower end portion of the insulating housing 1 becomes thicker than the thickness of the upper end portion (the side of the movable conductor 5) of the insulating housing 1, the strength of the lower end portion side of the insulating housing 1 is enhanced. Thereby, the reliability of the vacuum valve is improved.
Further, according to the present embodiment, with the provision of the projections 23 formed in a recess and projection shape along the circumference of the insulating housing 1, the joint portion of the lower end portion 1B of the insulating housing 1 and the stationary conductor 3 and the space between the plurality of bellows are evacuated as well as the inside of the insulating housing 1 during heating and evacuating operation.
Further, since the movable conductor side inner brazing member 26 is provided with the inner circumferential bent portion 20 which is designed to firmly guide the entire circumference of the upper end portion 1A of the insulating housing 1 as well as the movable conductor side outer brazing member 25 is provided with the outer circumferential bent portion 21 which is designed to firmly guide the entire circumference of the upper end portion 1A of the insulating housing 1, the inner circumferential bent portion 20 which is designed to guide the inner circumference of the movable conductor side metal end plate 7 and the step portion 24 which is designed to guide the circumferences of the movable conductor side inner brazing member 26 and the metal end plate side end 6'B of the insulating housing side bellows 6', the jointing portion 17 of the metal end plate side end 6'B of the insulating housing side bellows 6', the upper end portion 1A of the insulating housing 1 and the movable conductor side metal end plate 7 is kept under a given condition, that is, a vacuum sealed condition even when the movable conductor 5 is moved. accordingly, vacuum inside the insulating housing 1 is maintained, which improves the tightness of sealing at the positions to be tightly jointed. Thereby, the reliability of the vacuum valve can be improved.
The double sealed vacuum valve is very useful for a vacuum circuit breaker which is used under a condition requiring frequent switching operation.
Further, since substantially the same manufacturing method as described in connection with the previous embodiment is used for the present embodiment, the jointing operation can be completed reliably by a single jointing work. Further, because of a shortened heating time as well as a shortened work time, the production efficiency is improved. In addition because of a uniform heat application to the respective jointing portions a complete joint can be achieved. Further, the reliability of the vacuum valve can be improved.
Fig. 10 shows a sectional view of a vacuum circuit breaker constructed by using any one of the vacuum valves stated above.
The vacuum circuit breaker 101 is constructed with a operating mechanism 104 disposed in a front panel side, three pair of insulation tubes 107 (only one pair of the insulation tube is shown in the Figure 10) on a back side of the operating mechanism 104 and a movable carriage 103 having wheels 102 mounting the operating mechanism 104 and the insulation tubes 107.
The vacuum valves 100 are respectively disposed in the three pair of insulation tubes 107, and the separable conductors constituting the stationary conductor 3 and the movable conductor 5 are respectively connected to external conductors 105, 106 disposed on a central axis of the vacuum valve 100.
The external conductor 105 connected to the stationary conductor 3 and the external conductor 106 connected to the movable conductor 5 are respectively connected to contacting terminals 108, 109, and are respectively fed out of the insulation tubes 107 from upper and lower portions thereof. The contacting terminals 108, 109 are respectively contacted to or separated from disconnecting portions of a switch board which is not shown in the figure by moving the carriage 103.
As the external conductors 105, 106 connected to the contacting terminals 108, 109 are fed out horizontally from the insulation tubes 107 from the upper and lower portions thereof on the back of the front panel of the vacuum circuit breaker 101, the upper and lower portions of the insulation tubes 107 are opened. Therefore, the air which comes in through the lower opening of the insulation tubes 107 is heated by the vacuum valve 100 and the heated air comes out through the upper opening of the insulation tubes 107 because the insulation tube 107 effects as a chimney.
The end of the external conductor 106 connected to the movable conductor 5 is connected to a operating rod 110, and the operating rod 110 is connected to a main lever (which is not shown in the figure), one end of which is connected to the operating mechanism 104, thereby the movable conductor 5 of the vacuum valve 100 is actuated by the operating mechanism 104 through the main lever, the operating rod 110 and the external conductor 106.
Therefore, when the operating rod 110 moves downward, an electrode mounted at a top end of the movable conductor 5 is separated from an electrode mounted at a top end of the stationary conductor 3, and when the operating rod 110 moves upward, the electrode mounted at the top end of the movable conductor 5 is contacted to the electrode mounted at the top end of the stationary conductor 3.
In such the vacuum valve 100, an external surface of the stationary conductor 3 is very broad and has a function as a radiator. At least, the area of the external surface of the stationary conductor 3 is broader than a contact area of the separable conductors 3, 5. The separable conductors 3, 5 constituting of the stationary conductor 3 and the movable conductor 5 are contacted through the electrodes 2, 4 respectively mounted at the tops of the stationary conductor 3 and the movable conductor 5, and the heat is generated between the stationary electrodes 2 and the movable electrode 4 when the stationary electrodes 2 and the movable electrode 4 are contacted so as to flow a large current therethrough.
In such a situation, as the area of the external surface of the stationary conductor 3 is broader than a contact area of the separable conductors 3, 5 through the stationary electrodes 2 and the movable electrode 4, that is, a contact area of the stationary electrodes 2 and the movable electrode 4, the heat generated at the contact area is easily radiated from the broad external surface of the stationary conductor 3, thereby the size of the vacuum valve may be very compact and the weight thereof becomes smaller than that in the convectional vacuum valve as 7 to 10 % down.
Further, the vacuum circuit breaker using such vacuum valve may be more compact than ever too.

Claims

A vacuum valve in which a pair of separable conductors (3, 5) constituting a stationary conductor (3) and a movable conductor (5) are disposed in a hollow cylindrical insulation body (1), and one end side of said hollow cylindrical insulation body (1) is sealed in vacuum-tight fashion with an end plate (7) and a flexible member (6, 6'),
characterised in that the other end side of said hollow cylindrical insulation body (1) is sealed in vacuum tight with said stationary conductor (3) having an external surface connected to an external conductor (105), said external surface being broader than the contact area of the separable conductors (3, 5) or that of contacting electrodes respectively mounted on the separate conductors (3, 5).
The vacuum valve of claim 1 and disposed in an insulation container of a vacuum circuit breaker having openings upper and lower portions thereof.
The vacuum valve of claim 2, wherein said insulation container is a tube disposed vertically.
The vacuum valve of any of claims 1 to 3, wherein said stationary conductor (3) is disposed over said movable conductor (5).
The vacuum valve of any of claims 1 to 4, wherein the central axis of said stationary conductor (3) is disposed substantially vertically.
A vacuum circuit breaker comprising the vacuum valve of any preceding claim, wherein an external conductor (105) is connected to the external surface of the stationary conductor (3), another conductor (106) is connected to said movable conductor (5) and an operating rod (110) is provided for actuating said movable conductor (5).
The circuit breaker of claim 6, wherein said separable conductors (3, 5) are disposed vertically, whereby said movable conductor (5) is moved up and down by said operating rod (110).