JP2020068129A - Vacuum valve - Google Patents

Abstract

A vacuum valve capable of preventing dielectric breakdown and suppressing an increase in size is provided. A vacuum container in which both ends of an insulating cylinder (21) are sealed with sealing fittings (22); and an insulating member 8 provided so as to cover the outer circumference of the joint portion with a gap therebetween. [Selection drawing] Fig. 2

Description

  Embodiments of the present invention relate to vacuum valves.

  Generally, a solid insulated switchgear has a breaker for breaking the electric path. A vacuum valve is known as this blocking unit. In the vacuum valve, a fixed side electrode fixed to the fixed side energizing rod and a movable side electrode fixed to the movable side energizing rod are arranged to face each other in a vacuum container having an insulating tube and a sealing metal fitting. A cylindrical arc shield is provided so as to surround the pair of fixed-side electrodes and movable-side electrodes.

  Such a vacuum valve can obtain high insulation performance and arc extinguishing performance of the vacuum by creating a vacuum inside the vacuum container accommodating the fixed-side electrode and the movable-side electrode. It is possible to reduce the size as compared with the above.

  As the insulating cylinder of the vacuum valve, a ceramic porcelain insulator excellent in insulating performance, mechanical performance and gas barrier is used. The end portion of the insulating cylinder is subjected to a metallizing process for forming a metal film on the surface so as to be joined to the metal fitting. Then, the metallized portion and the metal fitting are brazed with a metal brazing material to realize an airtight state inside the vacuum container.

  However, a triple point at which the metal brazing material, the ceramic insulator, and the surrounding air are in contact with each other is formed in the portion where the metal fitting is sealed with the insulating cylinder. The three types of materials forming the triple point have a large difference in relative dielectric constant. Therefore, distortion and concentration of equipotential lines are likely to occur at points where they are in contact with each other, and the electric field strength becomes extremely high.

  Then, when arranging the vacuum valve in air or insulating gas, since the insulating performance of air and insulating gas is lower than that of vacuum, the vacuum between the sealing part on the fixed side and the sealing part on the movable side is reduced. There is a high possibility of dielectric breakdown through the creeping surface, which is the surface that constitutes the outside of the valve. Further, depending on the usage environment, the contaminants that have come in contact with the surface of the vacuum valve adhere to the surface of the vacuum valve. Since such contaminants often have conductivity, the insulation performance on the creeping surface of the vacuum valve deteriorates. In order to deal with this, an insulating material such as rubber is attached to the outer circumference of the insulating cylinder of the vacuum valve to extend the insulation distance along the creeping surface of the vacuum valve to improve the insulation performance.

JP, 2014-186879, A

  However, when an insulating material is attached to the outer periphery of the insulating cylinder of the vacuum valve, a void may be formed at the boundary between the insulating cylinder and the insulating material due to poor adhesion or the like. If this gap is present near the sealing metal fittings or is present continuously, there will be a portion where the outer peripheral surface is not substantially covered by the insulator, reducing the effect of extending the creepage insulation distance. To do. On the other hand, it is difficult to uniformly adhere the insulating material so that no voids are generated. Moreover, if an insulator is attached to the outer circumference, the entire vacuum valve becomes large.

  An object of the present embodiment is to provide a vacuum valve capable of preventing dielectric breakdown and suppressing an increase in size.

  In order to solve the above problems, the vacuum valve of the present embodiment is a vacuum container in which both ends of an insulating cylinder are sealed by sealing metal fittings, and in the vacuum container, a pair of electrodes that are arranged to face each other so that they can be contacted and separated. An insulating member provided so as to cover an outer periphery of a joint portion between the insulating cylinder and the sealing metal fitting with a gap therebetween.

It is a sectional view showing the whole vacuum valve composition concerning a 1st embodiment. It is an expanded sectional view of the place enclosed with the solid line circle of FIG. It is an expanded sectional view of the example which covered the insulating member and adhered it to the insulating cylinder. It is an expanded sectional view of the example which fixed the insulating member to the insulating cylinder with the screw. It is an expanded sectional view of the example which made the outer diameter of the insulating member larger than the insulating cylinder. It is an expanded sectional view of an example in which an insulating cylinder has a chamfered shape. It is an expanded sectional view of the example which separated the outer edge of the sealing part from the outer edge of the insulating cylinder. It is an expanded sectional view of the example which fitted the sealing metal fitting in the insulating cylinder.

Hereinafter, the vacuum valve according to the embodiment will be described in detail with reference to the drawings.
(Constitution)
First, the overall configuration of the vacuum valve of the embodiment will be described. FIG. 1 is a cross-sectional view showing the overall configuration of the vacuum valve 1 in the open circuit state. FIG. 2 is an enlarged view of the circled portion of FIG. The vacuum valve 1 is a device for connecting and disconnecting an electric path in a vacuum. As shown in FIG. 1, this vacuum valve 1 has a vacuum container 2, a conducting rod 3, an electrode 4, a bellows 5, an arc shield 6, an inner shield 7, and an insulating member 8.

  In this vacuum valve 1, a pair of electrodes 4 are arranged facing each other in a vacuum container 2 having a substantially cylindrical shape. The facing electrodes 4 are the fixed side electrode 4A and the movable side electrode 4B, and the movable side electrode 4B is brought into contact with and separated from the fixed side electrode 4A by moving the movable side electrode 4B along the axis X. In this embodiment, the axis X is common to the vacuum container 2, the fixed electrode 4A, and the movable electrode 4B. When the movable side electrode 4B is in contact with the fixed side electrode 4A, it becomes conductive and the electric circuit is closed. On the other hand, when the movable electrode 4B is separated from the fixed electrode 4A, the current is cut off and the electric circuit is opened. In the following description, the side on which the fixed-side electrode 4A is arranged is the fixed side, and the side on which the movable-side electrode 4B is arranged is the movable side.

The vacuum container 2 is a container whose sealed space is vacuum. The vacuum is not limited to this, but is preferably 10 ⁻² Pa or less, for example. The vacuum container 2 has an insulating cylinder 21 and a sealing metal fitting 22. The insulating cylinder 21 has a cylindrical shape with both ends open. In the present embodiment, the insulating cylinder 21 has two insulating porcelain tubes 211 and 212. The insulating porcelain tube 211 and the insulating porcelain tube 212 are coaxially stacked, and their ends are joined by stainless steel or the like. The insulating tubes 211 and 212 are made of an insulating material such as ceramics or glass.

  As shown in FIG. 2, the outer peripheral edge of the end portion of the insulating cylinder 21 is reduced by being cut out over the entire circumference so that the cross section in the direction along the axis X is L-shaped. Thus, the first peripheral surface 21a and the base surface 21b are formed at the end of the insulating cylinder 21. The first peripheral surface 21 a is a peripheral surface of a cylinder having a smaller diameter than the outer peripheral surface of the insulating cylinder 21. The base surface 21b is a ring-shaped flat surface that is orthogonal to the first peripheral surface 21a. The first peripheral surface 21a and the base surface 21b form an L-shaped cross section.

  The end of the insulating cylinder 21 is subjected to a metallizing process. The metallizing process is a process for forming a metal film on the surface of a non-metal such as ceramics. However, this metallizing treatment is formed only on the reduced-diameter end portion of the insulating cylinder 21. That is, the first peripheral surface 21a and the base surface 21b are not metallized. The shape and metallizing process of the end portion of the insulating cylinder 21 are common to the fixed side and the movable side.

  The sealing metal fitting 22 is a member that closes the openings on both the fixed side and the movable side of the insulating cylinder 21. The sealing metal fitting 22 has a shape in which a disk-shaped outer circumference is curved and raised over the entire circumference. The outer edge of the sealing metal fitting 22 closes the openings at both ends of the insulating cylinder 21, and is brazed to the metallized end surface with a metal brazing material. As a result, the metal fittings 22 are hermetically sealed at both ends of the insulating cylinder 21, and the inside of the vacuum container 2 is sealed. This brazing material reaches the edge of the metallized end of the insulating cylinder 21 to form the sealing portion 9. The outer edge of the sealing portion 9 does not reach the table surface 21b. In the following description, the fixed side is referred to as the fixed side sealing metal fitting 22A and the fixed side sealing portion 9A, and the movable side is referred to as the movable side sealing metal fitting 22B and the movable side sealing portion 9B.

  The current-carrying rod 3 is a pair of conductors made of a conductive material such as copper, and has, for example, a cylindrical shape. The pair of energizing rods 3 are a fixed side energizing rod 3A and a movable side energizing rod 3B. The center of the sealing metal member 22 is open, the current-carrying rod 3 penetrates this opening from the outside of the vacuum container 2, and one end thereof extends into the vacuum container 2. The pair of fixed-side conducting rods 3A and movable-side conducting rods 3B have a common axis with the axis X. Further, the fixed side energization rod 3A and the movable side energization rod 3B are arranged to face each other.

  The outer diameter of the fixed-side conducting rod 3A is approximately the same as the inner diameter of the opening of the sealing metal fitting 22A. The fixed-side energizing rod 3A is airtightly fixed and supported by the fixed-side sealing metal fitting 22A by brazing the opening of the fixed-side sealing metal fitting 22A with a brazing metal. On the other hand, the outer diameter of the movable-side energizing rod 3B is slightly smaller than the inner diameter of the opening of the movable-side sealing fitting 22B. The term “slightly small” means that the movable-side conducting rod 3B is small enough to move along the axis X in the opening of the movable-side sealing fitting 22B. That is, the movable-side conducting rod 3B is loosely inserted into the opening of the movable-side sealing metal fitting 22B.

  The bellows 5 is an expandable and contractible bellows-shaped expansion tube and is made of a material such as metal. The bellows 5 is provided in the vacuum container 2. The movable-side conducting rod 3B penetrates the inside of the bellows 5. One end of the bellows 5 is fixed to the movable side sealing metal fitting 22B by brazing with a metal brazing material so as to cover the opening of the movable side sealing metal fitting 22B. That is, the outer diameter of the bellows 5 is larger than the inner diameter of the opening of the movable side sealing fitting 22B. On the other hand, the other end of the bellows 5 is airtightly fixed to the movable-side conducting rod 3B by brazing with a metal brazing material. That is, the bellows 5 is fixed to the sealing metal fitting 22B and the movable-side energization rod 3B, so that the atmosphere flowing from the opening of the movable side metal-sealing metal fitting 22B is retained inside the bellows 5. Thereby, the atmosphere can be prevented from flowing into the vacuum container 2, and the vacuum in the vacuum container 2 can be maintained.

  A bellows cover 10 is provided on the end portion side of the bellows 5 that is joined to the movable-side energizing rod 3B. The bellows cover 10 prevents metal particles from adhering to the bellows 5. Specifically, due to the arc generated when the current is cut off, the surfaces of the fixed-side electrode 4A and the movable-side electrode 4B are evaporated, and metal particles are generated. When the metal particles adhere to the bellows 5, a crack may be formed in that portion, and the vacuum in the vacuum container 2 may not be maintained. By attaching the metal particles to the bellows cover 10, the metal particles are prevented from attaching to the bellows 5.

  The fixed electrode 4A and the movable electrode 4B are, for example, spiral electrodes made of a conductive material such as copper. The spiral electrode is a disc-shaped electrode having a plurality of slits extending from the outer peripheral portion thereof, and thus having a plurality of arm portions partially defined by the slits and having a spiral shape. The fixed-side electrode 4A and the movable-side electrode 4B are not limited to spiral electrodes, and various types such as vertical magnetic field electrodes and flat plate electrodes can be used.

  The fixed-side electrode 4A is in contact with the end surface of the fixed-side current-carrying rod 3A extending into the vacuum container 2 and fixed by brazing with a metal brazing material. On the other hand, the movable side electrode 4B is in contact with the end surface of the movable side conducting rod 3B, and is fixed by brazing with a metal brazing material. That is, the fixed electrode 4A and the movable electrode 4B are arranged to face each other. The fixed side electrode 4A and the movable side electrode 4B are brought into contact with and separated from each other to conduct or cut off the current.

  The arc shield 6 is made of a material such as stainless steel, copper, or a copper-chromium alloy, and has a cylindrical shape with both ends open. The arc shield 6 is provided in the vacuum container 2 in the axis X direction so as to surround the fixed electrode 4A and the movable electrode 4B. The length of the arc shield 6 in the axis X direction is at least the sum of the thickness of the fixed side electrode 4A and the movable side electrode 4B in the axis X direction and the distance between the fixed side electrode 4A and the movable side electrode 4B in the open state. Have a length.

  The arc shield 6 prevents the metal particles from adhering to the insulating cylinder 21 and deteriorating the insulating performance. Specifically, if the metal particles generated by the arc generated when the current is cut off adhere to the insulating cylinder 21, the insulating performance of the vacuum container 2 will deteriorate. Since the arc shield 6 is provided so as to surround the fixed electrode 4A and the movable electrode 4B, the metal particles are attached to the arc shield 6 and prevented from attaching to the insulating cylinder 21.

  The inner shield 7 is a cylindrical body provided inside the sealing metal fitting 22. The outer periphery of the inner shield 7 is arranged with a gap from the sealing portion 9 at the end of the insulating cylinder 21. The end portion of the inner shield 7 is folded so as to bend toward the axis X. The inner shield 7 relieves the electric field at the joint between the sealing metal member 22 and the insulating cylinder 21 inside the vacuum container 2. The fixed side of the inner shield 7 is a fixed side inner shield 7A, and the movable side is a movable side inner shield 7B.

  The insulating member 8 is provided so as to cover the outer periphery of the joint between the insulating cylinder 21 and the sealing metal fitting 22 with a gap. The insulating member 8 is a cylindrical member made of an insulating material.

  The outer diameter of the insulating member 8 is the same as the outer diameter of the insulating cylinder 21. One end of the insulating member 8 is a protruding edge 81 that annularly protrudes toward the axis X so that the cross section has an L shape. The other end of the insulating member 8 is mounted on the base surface 21b of the insulating cylinder 21 and fixed by adhesion with an adhesive or the like. The outer peripheral surface of the insulating cylinder 21 and the outer peripheral surface of the insulating member 8 are flush with each other. The insulating member 8 is separated from the sealing fitting 22, the sealing portion 9, and the first peripheral surface 21a. The structure of the insulating member 8 is common to the fixed side end and the movable side end of the insulating cylinder 21. Hereinafter, the fixed side is referred to as a fixed side insulating member 8A, and the movable side is referred to as a movable side insulating member 8B.

(Action)
The joint portion between the sealing metal fitting 22 and the insulating cylinder 21 is a triple point T (a portion surrounded by a broken line circle in FIG. 2) where the three sealing mediums of metal, the insulating cylinder 21 of ceramics, and air are overlapped. It is also called a triple junction). At the triple point T, as described above, the electric field becomes very strong, so that electrons are emitted from there. Then, dielectric breakdown easily occurs between the fixed side and the triple point T on the movable side.

Here, in order to improve the creepage insulation performance of the vacuum valve 1, the following method is considered.
(a) The electric field strength at the triple point T is reduced.
(b) The creepage distance between the fixed triple point T and the movable triple point T is extended.
(c) Suppress secondary electron emission along the surface of the insulator.
(d) Do not contaminate the surface of the vacuum valve.

  In the present embodiment, the sealing portion 9 where the triple point T is present and the end portion of the insulating cylinder 21 are covered with the insulating member 8 with a gap. That is, by blocking the electrons generated from the triple point T by the insulating member 8, it becomes difficult for the electrons to be emitted outside the outer diameter of the insulating cylinder 21. The creepage distance between the fixed-side triple point T and the movable-side triple point T can be extended by the inner surface and the outer surface of the insulating member 8 in addition to the first peripheral surface 21a and the base surface 21b. The extension of the creepage distance is common to the fixed side and the movable side. Therefore, as compared with the case where the insulating member 8 is not provided, the effect of extending the creepage distance by the extension on the fixed side and the extension on the movable side can be obtained.

  The creepage distance can also be extended by extending the insulating member 8 in the direction of the axis X. However, in this case, the outer shape of the vacuum valve 1 is enlarged. Therefore, as in the present embodiment, it is preferable to provide the protruding edge 81 to extend the creepage distance while suppressing the expansion of the outer shape of the vacuum valve 1.

  In addition, since the insulating member 8 is interposed between the outside of the vacuum valve 1 and the sealing portion 9, the insulating member 8 shields substances that come in from the outside and adhere. Therefore, the fouling of the sealing portion 9 is reduced. Furthermore, the insulating member 8 is not in contact with the sealing portion 9. If the sealing portion 9 made of metal and the insulating member 8 come into contact with each other, a triple point is newly generated by the sealing portion 9, the insulating member 8 and air, and electrons are emitted from here. In this embodiment, since the insulating member 8 and the sealing portion 9 are not in contact with each other, the emission of electrons is suppressed.

(effect)
As described above, in the vacuum valve 1 of the present embodiment, the vacuum container 2 in which the both ends of the insulating cylinder 21 are sealed by the sealing metal fittings 22 and the pair of the vacuum container 2 which are arranged in the vacuum container 2 so as to face each other so as to be separable from each other. The fixed-side electrode 4A, the movable-side electrode 4B, and the insulating member 8 provided so as to cover the outer periphery of the joint between the insulating cylinder 21 and the sealing metal member 22 with a gap.

  This makes it possible to extend the creepage distance between the triple point T on the fixed side and the movable side. Therefore, between the fixed side and the movable side, the dielectric breakdown that occurs on the outer surface of the insulating cylinder 21 can be suppressed. Further, since the insulating member 8 reduces the contamination of the sealing portion 9 from the outside, it is possible to suppress the dielectric breakdown of the outer surface of the insulating cylinder 21 due to the contamination.

  Here, in order to prevent such dielectric breakdown, it is possible to cast the outside of the vacuum valve 1 with epoxy resin or the like. However, in this case, since the entire vacuum valve 1 becomes large, it is not suitable for a model that requires a smaller size, for example, a model having a low rated voltage. In the present embodiment, the risk of dielectric breakdown can be suppressed without such casting, so that the size can be reduced. Rather than covering the entire vacuum valve 1 with an insulator or covering most of the outer circumference of the insulating cylinder 21 with an insulator, the creeping insulation performance can be improved and the miniaturization can be realized only by local protection.

(Modification)
Next, a vacuum valve 1 according to a modified example of the embodiment will be described with reference to the drawings.
(1) The material of the insulating member 8 may be the same as or different from that of the insulating cylinder 21. When the material of the insulating member 8 is different from that of the insulating cylinder 21, the potential distribution around the sealing portion 9 changes due to the difference in relative permittivity, which affects the electric field of the sealing portion 9. That is, by using the insulating member 8 having a relative dielectric constant different from that of the insulating cylinder 21, the electric field strength of the sealing portion 9 can be adjusted.

  For example, when the relative permittivity of the insulating member 8 is higher than the relative permittivity of the insulating cylinder 21, the difference in relative permittivity between air and the insulating member 8 becomes large, and the electric field strength of the sealing portion 9 increases. On the other hand, by using an insulating material having a relative permittivity lower than that of the insulating cylinder 21 as the insulating member 8, it is possible to reduce the difference in relative permittivity between air and the insulating member 8, and to seal. The sealing portion 9 can be protected while the electric field strength of the portion 9 is kept substantially the same as the electric field strength when the insulating member 8 is not attached. The insulating material used for the insulating member 8 may be, for example, a resin material such as epoxy resin or PTFE, but is not limited thereto.

(2) The insulating member 8 may be bonded to the insulating cylinder 21 with an insulating adhesive. For example, as shown in FIG. 3, a fixing portion 11 is provided on the insulating member 8. The fixed portion 11 has a second peripheral surface 21c. The second peripheral surface 21c is formed between the outer periphery of the insulating cylinder 21 and the first peripheral surface 21a so as to have a diameter smaller than that of the outer periphery of the insulating cylinder 21 and larger than that of the first peripheral surface 21a. It is a peripheral surface. The outside of the second peripheral surface 21c is designated as a base surface 21b.

  The outer diameter of the second peripheral surface 21c is the same as the inner diameter of the insulating member 8. Here, the same diameter means that it is the same as long as the insulating member 8 can be covered with the second peripheral surface 21c. Therefore, even if the inner diameter of the insulating member 8 is slightly larger than the outer diameter of the second peripheral surface 21c and the inner diameter of the insulating member 8 fits smoothly over the second peripheral surface 21c, the same is true. Good. The same can be said even if the inner diameter of the insulating member 8 is slightly smaller than the outer diameter of the second peripheral surface 21c and the inner diameter of the insulating member 8 slightly expands when the second peripheral surface 21c is covered. The adhesive R is interposed when the insulating member 8 is covered on the second peripheral surface 21c. As a result, it is possible to prevent the insulating member 8 from falling off during operation of the vacuum valve 1. As the adhesive R, it is preferable to use an insulating adhesive, for example, an adhesive mainly composed of an epoxy resin or a ceramic material, which has little deterioration over time.

(3) The insulating member 8 and the insulating cylinder 21 may be connected to each other by fitting thread grooves formed on each other. For example, as shown in FIG. 4, screw grooves are formed on the inner peripheral surface of the insulating member 8 and the second peripheral surface 21c. Then, the screw groove of the insulating member 8 and the screw groove of the second peripheral surface 21c are fitted and screwed together, so that the insulating member 8 is fixed to the insulating cylinder 21. Since the thread groove is formed by thread cutting, it is preferable to use a material having excellent machinability, for example, machinable ceramic, as the insulating cylinder 21. As a result, when cutting, a chip or the like is less likely to occur, and fine processing is facilitated.

  In this way, by fixing the insulating member 8 with screws, it is not necessary to interpose a material such as an adhesive different from the material between the insulating cylinder 21 and the insulating member 8, which affects the distribution of the dielectric constant. The insulating member 8 can be fixed without applying. Even in the case of fixing with screws, it may be fixed more firmly by further interposing an adhesive.

(4) By forming the outer diameter of the insulating member 8 to be larger than the outer diameter of the insulating cylinder 21, the creeping distance between the fixed-side and movable-side triple points T may be further extended. For example, as shown in FIG. 5, the outer diameter of the insulating member 8 is formed to be larger than the outer diameter of the insulating cylinder 21 so as to project outward. When the outer diameter difference between the insulating member 8 and the insulating cylinder 21 is ΔR, the creepage distance can be extended by ΔR × 2 on the fixed side and ΔR × 2 on the movable side. Therefore, the insulation separation distance can be extended to further suppress the dielectric breakdown.

  It should be noted that, with this configuration, the maximum outer diameter of the entire vacuum valve 1 increases. For this reason, when the space to be arranged is limited, the outer diameter of the insulating member 8 should be determined after grasping the dimensions that can be mounted in advance and obtaining a sufficient insulation separation distance based on the working voltage. Is preferred.

(5) The end of the insulating cylinder 21 provided with the insulating member 8 may have a chamfered shape. As shown in FIG. 6, the chamfered shape has a surface that is inclined with respect to the end surface and the outer peripheral surface of the insulating cylinder 21, so that a shape in which an angle orthogonal to the end surface and the outer peripheral surface of the insulating cylinder 21 is eliminated. Say. This chamfered inclined surface is referred to as a chamfered portion 21d. The chamfered portion 21d may have an outwardly convex rounded shape. When the chamfered shape is provided, the fixing portion 11 is provided near the end of the outer peripheral surface of the insulating cylinder 21. The fixing portion 11 is a portion fixed by fitting the insulating member 8 together. In the fixing portion 11, similarly to the above, by fitting the outer peripheral surface of the insulating cylinder 21 and the thread groove formed on the inner peripheral surface of the insulating member 8 or by interposing the adhesive R, both members are joined together. Just fix it.

  In this way, by providing the insulating cylinder 21 with the chamfered shape, if the insulating member 8 is fitted along the chamfered shape, contact between the end of the sealing portion 9 and the insulating member 8 is avoided. You can As the insulating cylinder 21, a porcelain insulator having a chamfered shape in advance may be used, so that it is not necessary to additionally process the notch or the like by grinding or the like. Further, if chamfered, it becomes easier to center the insulating cylinder 8 when the insulating member 8 is combined with the insulating cylinder 21, and it is difficult for positional displacement to occur.

(6) The outer edge of the sealing portion 9 may be separated from the outer edge of the insulating cylinder 21. For example, as shown in FIG. 7, since the outer diameters of the insulating cylinder 21 and the airtight sealing portion 9 of the sealing metal fitting 22 are smaller than the outer diameter of the insulating cylinder 21, the sealing portion 9 is insulated. It is not in contact with the cylinder 21. Further, since it suffices to fit the insulating member 8 into the end portion of the insulating cylinder 21, it is not necessary to provide a notch and a chamfered shape. In forming such a region of the sealing portion 9, it is preferable that the region to be metallized by masking or the like does not reach the outer edge of the insulating cylinder 21, and the brazing material spreads only to the metallized region. Alternatively, a brazing material that is difficult to spread may be used, or the amount of the brazing material may be adjusted so that the brazing material does not reach the outer edge of the insulating cylinder 21. Further, a mold that blocks the brazing material may be placed so that it does not reach the outer edge of the insulating cylinder 21.

  In the fixing portion 11, similarly to the above, by fitting the screw groove formed on the outer peripheral surface of the insulating cylinder 21 and the inner peripheral surface of the insulating member 8 or by interposing the adhesive R, The member may be fixed.

(7) A material having a secondary electron emission coefficient smaller than that may be provided on the surface of the insulating member 8. The electrons emitted from the triple point T are used as primary electrons, and the primary electrons collide with the insulating member 8 to emit secondary electrons. At this time, the electric field having the opposite polarity to the applied voltage is charged on the insulating member 8 to increase the electric field at the end of the sealing portion 9. In order to deal with this, for example, a material such as silicon carbide, titanium nitride, or chromium oxide having a small secondary electron emission coefficient is applied to the surface of the insulating member 8 in the above-described mode. As a result, secondary electron emission at the time of primary electron collision is suppressed, so that it is possible to suppress charging of the insulating member 8 and prevent an increase in electric field.

  The application site may be the entire surface of the insulating member 8 or a part thereof. In the case where it is partly formed, it is preferable to set it at a position facing at least the triple point T. Further, since the material having a small secondary electron emission coefficient has a property of metal or a property close to that of a metal, the application position may be a position not reaching the insulating cylinder 21 so that a new triple point is not formed. preferable.

(8) The sealing metal fitting 22 may be brazed by being fitted inside the insulating cylinder 21, as shown in FIG. In this case, it becomes easy to prevent the contact between the insulating member 8 and the end of the sealing portion 9 when the insulating member 8 is attached.

(9) In the above aspect, the insulating member 8 is provided on both the fixed side and the movable side to prevent dielectric breakdown, but the insulating member 8 is provided on only one of the fixed side and the movable side. It may be. Another insulating structure may be applied to the other.

(Other embodiments)
Although an embodiment according to the present invention has been described herein, this embodiment is presented as an example and is not intended to limit the scope of the invention. The above-described embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. The embodiments and the modifications thereof are included in the invention described in the claims and equivalents thereof as well as included in the scope and the gist of the invention.

1 vacuum valve 2 vacuum container 3 energizing rod 3A fixed side energizing rod 3B movable side energizing rod 4 electrode 4A fixed side electrode 4B movable side electrode 5 bellows 6 arc shield 7 inner shield 7A fixed side inner shield 7B movable side inner shield 8 insulating member 8A Fixed-side insulating member 8B Movable-side insulating member 9 Sealing portion 9A Fixed-side sealing portion 9B Movable-side sealing portion 10 Bellows cover 11 Fixed portion 21 Insulating cylinder 21a First peripheral surface 21b Platform surface 21c Second peripheral surface 21d Chamfering part 22 Sealing metal fitting 22A Fixed side sealing metal fitting 22B Movable side sealing metal fitting 81 Protruding edge 211 Insulator porcelain tube 212 Insulator porcelain tube R Adhesive T Three point X axis

Claims (9)

A vacuum container in which both ends of the insulating cylinder are sealed with sealing metal fittings,
In the vacuum container, a pair of electrodes arranged so as to be contactable and separable,
An insulating member provided so as to cover the outer periphery of the joint between the insulating cylinder and the sealing metal fitting with a gap therebetween,
A vacuum valve characterized by having.   The vacuum valve according to claim 1, wherein the insulating cylinder and the insulating member are made of different materials.   The vacuum valve according to claim 1 or 2, wherein the material of the insulating member has a lower relative dielectric constant than the material of the insulating cylinder.   4. The vacuum valve according to claim 1, wherein the insulating member is bonded to the insulating cylinder with an insulating adhesive.   The vacuum valve according to any one of claims 1 to 4, wherein the insulating member and the insulating cylinder are connected to each other by fitting threaded grooves formed on each other.   The vacuum valve according to claim 1, wherein an outer diameter of the insulating member is larger than an outer diameter of the insulating cylinder.   The vacuum valve according to any one of claims 1 to 6, wherein an end portion of the insulating cylinder provided with the insulating member has a chamfered shape.   The vacuum valve according to any one of claims 1 to 7, wherein an outer edge of a sealing portion in which the insulating cylinder and the metal fitting are sealed is separated from an outer edge of the insulating cylinder.   9. The vacuum valve according to claim 1, wherein a material having a secondary electron emission coefficient smaller than that of the insulating member is provided on a surface of the insulating member.

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