Vacuum valve

Abstract

To prevent partial discharge in vacuum and dielectric breakdown of a vacuum valve.SOLUTION: According to an embodiment, a vacuum valve is provided, which comprises: an insulating container that has an opening end having a chamfered corner surface; a vacuum container that has sealing metal fittings joined to the opening end with a metalized layer therebetween; and a pair of electrodes that are arranged opposite to each other separably in the vacuum container. The width dx of chamfering of the corner surface and the depth dy of chamfering of the corner surface have the relationship represented by dx>dy.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] FIELD OF THE INVENTION An embodiment of the present invention relates to a vacuum valve. [Background technology]

[0002] A vacuum valve maintains a vacuum inside by sealing the insulating vessel and the sealing metal fittings with silver solder or other soldering materials. The ends of the insulating vessel are metallized to increase the strength of the brazing process, but the point where the insulating vessel (insulator), metallization (metal), and vacuum overlap (the triple junction) is known to have an extremely high electric field. A high electric field makes it easy for electrons to escape, which makes partial discharges and dielectric breakdown more likely in the vacuum, adversely affecting the performance of the vacuum valve. Therefore, there is a need to mitigate the electric field at the triple junction. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-147026 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-119091 Summary of the Invention [Problem to be solved by the invention]

[0004] An embodiment of the present invention aims to suppress partial discharge and dielectric breakdown in a vacuum of a vacuum interrupter. [Means for solving the problem]

[0005] According to an embodiment, a vacuum vessel includes an insulating vessel having an open end with a chamfered corner, and a sealing metal fitting joined to the open end via a metallized layer; a pair of electrodes detachably disposed opposite each other within the vacuum vessel; There is provided a vacuum interrupter in which the width dx of the chamfer of the corner surface and the depth dy of the chamfer of the corner surface have a relationship expressed by the following formula (1). dx>dy…(1) [Brief explanation of the drawings]

[0006] [Figure 1] 1 is a schematic cross-sectional view illustrating an example of a vacuum interrupter according to an embodiment. [Figure 2] FIG. 2 is a partially enlarged view of FIG. [Figure 3] FIG. 2 is a model diagram for explaining the cross-sectional structure of a metallized layer. [Figure 4] FIG. 10 is a graph showing the relationship between the chamfer width dx and the electric field strength at the triple junction portion. [Figure 5] FIG. 10 is a graph showing the relationship between the chamfer depth dy and the electric field strength of the triple junction portion. [Figure 6] FIG. 10 is a graph showing the relationship between the chamfer angle θ and the electric field strength of the triple junction portion. [Figure 7] FIG. 10 is a partially enlarged view of a vacuum valve according to another embodiment. [Figure 8] FIG. 10 is a graph showing the relationship between the radius of curvature R and the electric field intensity at the triple junction portion. [Figure 9] FIG. 10 is a graph showing the relationship between angle θr and electric field intensity. DETAILED DESCRIPTION OF THE INVENTION

[0007] The vacuum interrupter according to the embodiment comprises an insulating container having an opening end with a chamfered corner or curved surface, a vacuum container having a sealing metal fitting joined to the opening end via a metallized layer, and a pair of electrodes arranged opposite each other and detachably within the vacuum container. The width dx of the chamfer of the corner surface and the depth dy of the chamfer of the corner surface have a relationship expressed by the following formula (1). dx>dy…(1) The radius of curvature R of the chamfered curved surface is 0.1 mm or more and 1.0 mm or less.

[0008] If the chamfer width dx and the chamfer depth dy of the corner face are dx≦dy, it becomes difficult to alleviate the electric field at the triple junction. Also, if the curvature radius R is less than 0.1 mm, processing becomes difficult and it becomes difficult to prevent chipping of the metallization layer. If it exceeds 1.0 mm, the electric field strength at the triple junction becomes greater than the electric field strength when the chamfer angle θ is 45°. According to the embodiment, by providing an opening end with a chamfered corner or curved surface on the insulating container, it is possible to reduce the electric field at the triple junction, suppress electron emission, and suppress partial discharge and dielectric breakdown in the vacuum of the vacuum valve.

[0009] Hereinafter, embodiments will be described with reference to the drawings. The disclosure is merely an example, and appropriate modifications that are easily conceivable by those skilled in the art while maintaining the gist of the invention are naturally included within the scope of the present invention. Furthermore, in order to clarify the explanation, the drawings may show the width, thickness, shape, etc. of each part schematically compared to the actual embodiment, but these are merely examples and do not limit the interpretation of the present invention. Furthermore, in this specification and each drawing, elements similar to those described above with reference to the previous drawings may be designated by the same reference numerals, and detailed descriptions may be omitted as appropriate.

[0010] FIG. 1 is a schematic cross-sectional view showing an example of a vacuum interrupter according to an embodiment. As shown in the figure, the vacuum interrupter 100 includes a cylindrical ceramic container 10 made of, for example, alumina porcelain and having openings at both ends. It also includes a fixed sealing metal fitting 11 sealed to one opening and a movable sealing metal fitting 12 sealed to the other opening. A vacuum is maintained within the vacuum interrupter 100. The fixed sealing metal fitting 11 and the movable sealing metal fitting 12 are both conductive and may be made of a metal material such as stainless steel. The fixed sealing metal fitting 11 has a central opening through which a fixed current-carrying shaft 13 is fixedly inserted. A fixed contact 14 is fixed as an electrode to the end of the fixed current-carrying shaft 13 within the ceramic container 10. A movable contact 15, which faces the fixed contact 14 and serves as a pair of disconnectable electrodes, is fixed to the end of a movable current-carrying shaft 16, which movably passes through a central opening in the movable sealing metal fitting 12. The portion of this movable current-carrying shaft 16 closer to the movable sealing metal fitting 12 than the central portion extends outside the ceramic container 10, and a freely expandable cylindrical bellows 17 is disposed in this portion for hermetic sealing. A free end 17-2 of the bellows 17 is sealed to the central portion of the movable current-carrying shaft 16, and a fixed end 17-1 is sealed to the central opening of the movable sealing metal fitting 12. A cylindrical arc shield 18 is provided around the fixed contact 14 and the movable current-carrying shaft 16.

[0011] Arc shield 18 includes a cylindrical arc shield body 18-1 and a ring-shaped support portion 18-2 that supports the outer surface of arc shield body 18-1. The arc shield is a conductor and can be made of a metal material such as stainless steel. The ceramic container 10, which serves as an insulating container, is a two-chamber type and is divided into a first ceramic container 10-1 on the fixed side, which has a first open end 10-1a and a second open end 10-1b, and a second ceramic container 10-2 on the movable side, which has a third open end 10-2a and a fourth open end 10-2b at both ends. A support 18-2 for fixing an arc shield 18 is provided between the first ceramic container 10-1 and the second ceramic container 10-2, and the second open end 10-1b and the third open end 10-2a are each joined and fixed to the support 18-2.

[0012] The fixed sealing metal fitting 11 has a disk-shaped fixed sealing plate 11-1 and a sealing portion 11-2 provided on the outer periphery of the inner surface of the fixed sealing plate 11-1, with the sealing portion 11-2 joined and sealed to the first opening edge 10-1a. The movable sealing metal fitting 12 has a disk-shaped fixed sealing plate 12-1 and a sealing portion 12-2 provided on the outer periphery of the inner surface of the sealing plate 12-1, with the sealing portion 12-2 joined and sealed to the fourth opening edge 10-2b, thereby forming a vacuum valve 100 as a vacuum container. In this case, a first metallized layer 51 is formed between the sealing portion 11-2 of the fixed side sealing metal fitting 11 and the first opening end 10-1a, a second metallized layer 52 is formed between the second opening end 10-1b and the support portion 18-2, a third metallized layer 53 is formed between the third opening end 10-2a and the support portion 18-2, and a fourth metallized layer 54 is formed between the sealing portion 12-2 of the movable side sealing metal fitting 12 and the fourth opening end 10-2b.

[0013] FIG. 2 shows an enlarged view of a region 101 near the first metallization layer in FIG. FIG. 3 shows a model diagram for explaining the cross-sectional structure of the first metallized layer 51. As shown in FIG. As shown in the figure, in the vacuum interrupter 100 according to the embodiment, a first ceramic container 10-1 has a first open end 10-1a, a first corner of which is chamfered to form a corner 10-1e on the inner periphery, and a corner of which is chamfered to form a corner 10-1f on the outer periphery. A first metallized layer 51 is provided on the first open end 10-1a, extending from a portion of the corner 10-1e to a portion of the corner 10-1f. For example, the width dx of the chamfer of the corner 10-1e is expressed by the length W of the insulating container 10-1 in the radial direction, and the depth dy of the chamfer of the corner 10-1e is expressed by the length D of the insulating container 10-1 in the axial direction, and the relationship is expressed by the following formula (1). dx>dy…(1) In this case, the chamfer angle θ of the corner surfaces 10-1e and 10-1f is expressed as the angle between the surface along the width dx and the corner surfaces 10-1e and 10-1f, and is greater than 0° and less than 45°.

[0014] A brazing material layer 45 is formed on the top of the first opening end 10-1a, and the sealing portion 11-2 of the fixed sealing metal fitting 11 can be joined by brazing. The first metallized layer 51 includes the brazing material layer 45. 3, the first metallization layer 51 may include a metallization layer 57 provided on the top of the first opening end 10-1a and a brazing material layer 45 provided on the metallization layer 57. The metallization layer 57 may also include a molybdenum-manganese layer 55 provided on the top of the first opening end 10-1a and a nickel layer 56 plated on the molybdenum-manganese layer 55, and the brazing material layer 45 may be provided on the nickel layer 56.

[0015] The braze used in the braze layer may include silver and at least one of the metals copper, zinc, or cadmium. As shown in FIG. 2, in the first metallized layer 51, a triple junction portion 41-1 is present on the corner surface 10-1e of the first opening end 10-1a, where the insulating container 10-1, the brazing material layer 45, and the vacuum inside the vacuum container overlap.

[0016] According to the embodiment, the corners on the inner and outer periphery of the first opening end 10-1a of the insulating container 10-1 are chamfered at a chamfering angle greater than 0° and less than 45°, respectively, to form corner surfaces 10-1e and 10-1f whose chamfer width and depth satisfy the above formula (1). This reduces the electric field strength of the triple junction portion 41-1 and suppresses electron emission, thereby making it possible to suppress partial discharge and dielectric breakdown in the vacuum of the vacuum valve.

[0017] Similarly to the first metallization layer 51, the second metallization layer 52 includes a triple junction 41-2 where the metal of the support 18-2, the insulator of the first ceramic container 10-1, and the vacuum within the vacuum container overlap. The third metallization layer 53 includes a triple junction 41-3 where the metal of the support 18-2, the insulator of the second ceramic container 10-2, and the vacuum within the vacuum container overlap. Furthermore, the fourth metallization layer 54 includes a triple junction 41-4 where the insulator of the second ceramic container 10-2, the metal of the movable sealing metal fitting 12, and the vacuum within the vacuum container overlap. Similarly to the first opening end 10-1a, the second opening end 10-1b, the third opening end 10-2a, and the fourth opening end 10-2b can each have a chamfered corner at an angle greater than 0° and less than 45° at the inner and outer circumferential corners. This reduces the electric field strength in the triple junction portion 41-2, 41-3, or 41-4 as well as the triple junction portion 41-1, thereby suppressing electron emission and making it possible to suppress partial discharge and dielectric breakdown in the vacuum of the vacuum valve.

[0018] The vacuum interrupter 100 according to the embodiment is configured in this manner. An insulating layer 21 can be provided around the vacuum valve 100. For example, epoxy resin can be used as the insulating material. A ground layer (not shown) may be further provided on the outer periphery of the insulating layer 21. An interface connecting portion (not shown) may be provided on the end of the insulating layer 21 facing the fixed-side current-carrying shaft 13 and the end of the insulating layer 21 facing the movable-side current-carrying shaft 16, respectively, so that they can be connected to similar interface connecting portions. This completes the molded vacuum valve 205.

[0019] Examples will be given below to more specifically illustrate the embodiments. Example Example 1 The width dx of the chamfer of the corner surface 10-1e and the depth dy of the chamfer of the corner surface 10-1e were changed, and the electric field strength of the triple junction portion 41-1 was measured. The measurement was performed by electric field analysis using the finite element method. FIG. 4 is a graph showing the relationship between the chamfer width dx and the electric field strength at the triple junction.

[0020] Here, the chamfer depth dy was fixed at 0.5 mm, 1.0 mm, and 1.5 mm, and the chamfer width dx was changed to measure the electric field strength of the triple junction portion 41-1 in the same manner. The electric field strength was normalized with the electric field strength when dx = 0.5 mm and dy = 0.5 mm as 1. Curves 101, 102, and 103 show the cases when dy is 0.5 mm, 1.0 mm, and 1.5 mm, respectively. From Figure 4, it can be seen that the electric field is reduced as dx increases.

[0021] FIG. 5 is a graph showing the relationship between the chamfer depth dy and the electric field strength at the triple junction. Here, the electric field strength was measured while changing the chamfer depth dy when the chamfer width dx was fixed at 0.5 mm, 1.0 mm, and 1.5 mm. The electric field strength was normalized with the electric field strength when dx = 0.5 mm and dy = 0.5 mm set to 1. Curves 106, 105, and 104 show the cases when dx is 0.5 mm, 1.0 mm, and 1.5 mm, respectively. Figure 5 shows that the electric field is reduced as dy becomes smaller. As dx increases or dy decreases, the triple junction position tends to move inward in the radial direction (dx direction), reducing the electric field strength. This also makes it more difficult for electrons to escape from the triple junction, suppressing the occurrence of partial discharge in a vacuum.

[0022] Example 2 FIG. 6 is a graph showing the relationship between the chamfer angle θ and the electric field strength at the triple junction. Here, the chamfer angle θ was changed and the electric field strength of the triple junction portion 41-1 was measured in the same manner as in Example 1. The electric field strength was normalized by setting the electric field strength when the chamfer angle θ was 45° to 1. From Figure 6, it can be seen that an electric field reduction effect can be expected when the chamfer angle θ is smaller than 45°. This makes it difficult for electrons to escape from the triple junction, and the occurrence of partial discharge in a vacuum can be suppressed. It should be noted that the chamfer angle θ can be less than 45° by making dx larger than dy so that the width and depth of the chamfer satisfy the above formula (1).

[0023] Example 3 FIG. 7 shows an enlarged view of the vicinity of the first metallized layer 51 of a vacuum interrupter 100-1 according to another embodiment. As shown in the figure, the first ceramic container 10-3 of the vacuum interrupter 100-1 has the inner corners of the first opening end 10-3a chamfered to form a curved surface 10-3r with a radius of curvature R, and the outer corners chamfered to form a curved surface 10-3s with a radius of curvature R. The first metallization layer 51 has a configuration similar to that shown in FIG. 3 and includes a brazing filler layer 45. It is disposed on the first opening end 10-3a and extends from a portion of the curved surface 10-3r to a portion of the curved surface 10-3s. In the first metallization layer 51 of FIG. 7, a triple junction 41-1 is present at the curved surface 10-3r of the first opening end 10-3a, where the insulating container 10-3, the brazing filler layer 45 on the surface of the first metallization layer 51, and the vacuum inside the vacuum container overlap. The vacuum valve 100-1 has the same configuration as that shown in FIGS. 1 and 2, except that a first ceramics container 10-3 is used instead of the first ceramics container 10-1.

[0024] In the vacuum interrupter 100-1, the radius of curvature R of the curved surfaces 10-3r and 10-3s was changed, and the electric field intensity of the triple junction portion 41-1 was measured in the same manner as in Example 1. FIG. 8 is a graph showing the relationship between the radius of curvature R and the electric field strength at the triple junction. The electric field strength was normalized to 1 when the chamfer angle θ was 45°, and is shown as curve 108. From Fig. 8, it was found that the electric field is reduced as the radius of curvature R becomes smaller, and that the electric field strength can be sufficiently reduced particularly when R is 1.0 mm or less. The area where the first metallized layer 51 was formed was also changed to measure the electric field strength.

[0025] 9 is a graph showing the relationship between the angle θr when the area between the upper end of curved surface 10-3r and triple junction 41-1 is considered to be an arc and the electric field strength. The electric field strength is normalized to 1 when θr is 45°. As shown in the figure, it is clear that the electric field strength can be reduced when θr is 45° or less and the area where the first metallized layer 51 is formed is not too wide. By reducing the electric field strength, electrons are less likely to escape from the triple junction, and the occurrence of partial discharge in a vacuum can be suppressed.

[0026] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0027] 10...insulating container, 10-1c, 10-1d...cornered surface, 10-1a, 10-1b, 10-1c, 10-1d...opening end, 10-3r, 10-3s...curved surface, 11...sealing metal fitting, 14, 15...electrode, 45...brazing material layer, 51...metallized layer, 57...metallized treatment layer, 100...vacuum container

Claims

1. an insulating container having an open end with a chamfered corner, and a vacuum container having a sealing metal fitting joined to the open end via a metallized layer; a pair of electrodes detachably disposed opposite each other within the vacuum vessel; A vacuum valve in which the width dx of the chamfer of the corner surface and the depth dy of the chamfer of the corner surface have a relationship expressed by the following formula (1). dx>dy...(1)

2. an insulating container having an open end with a chamfered curved surface, and a vacuum container having a sealing metal fitting joined to the open end via a metallized layer; a pair of electrodes detachably disposed opposite each other within the vacuum vessel; A vacuum valve in which the radius of curvature R of the chamfer of the curved surface is 0.1 mm or more and 1.0 mm or less.

3. the metallization layer includes a molybdenum-manganese layer on the open end of the insulating container and a nickel layer on the molybdenum-manganese layer; 3. The vacuum valve according to claim 1, further comprising a brazing material layer on the metallized layer.

4. 4. The vacuum valve according to claim 3, wherein the brazing material used in the brazing material layer contains silver and at least one metal selected from the group consisting of copper, zinc, and cadmium.

5. 2. The vacuum valve according to claim 1, wherein the chamfer angle θ of the corner surface is greater than 0° and less than 45°.

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