JPS6338808B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vacuum chamber disconnector, and more particularly, the present invention relates to a vacuum chamber disconnector, and more specifically, a vacuum chamber is formed by closing both ends of a metal cylinder with an insulating disk made of an inorganic insulator, and a vacuum chamber is formed in the vacuum chamber. The present invention relates to a vacuum shield and disconnector having a pair of electrodes that can be brought into contact with each other and separated from each other.

Conventionally, a vacuum vessel in a vacuum chamber or disconnector has a cylindrical body constituting the vacuum vessel, an insulating member made of hard glass or ceramic as a member constituting the upper and lower end plates that are joined to close it, and a thermal expansion material. Kovar (Fe−Ni−
Metal members such as Co) were used, and a vacuum container was formed by joining both members.

Generally, the inside of the vacuum container of this type of vacuum shield and disconnector is
Since it is necessary to maintain a high vacuum with a pressure of 10 ^-4 Torr or less, great care is taken to ensure an airtight bond between metal and ceramics.In particular, the coefficient of thermal expansion of the metal plates to be joined is As mentioned earlier, the most desirable equivalent is Fe−
Ni-Co alloy or Fe-Ni alloy was used.

However, if the cylindrical body of the vacuum vessel is formed of the above-mentioned insulating material such as ceramic, the price of the insulating tube will rise rapidly as the diameter increases, and the vacuum vessel and disconnector themselves will become expensive. cause In addition, metal members such as Kovar used for the upper and lower end plates of vacuum vessels have the drawback of being very expensive, and their thermal expansion coefficient α [α-T characteristic] at each temperature T does not necessarily match that of ceramics. The metal end plates, etc., must be provided with a stress relaxation structure to relieve the thermal stress caused by joining them by brazing, and since they are made of ferromagnetic material, they are susceptible to temperature rise due to eddy currents and alternating magnetic fields. There are problems such as noise caused by the magnetostrictive phenomenon.

For this reason, it has been desired that the upper and lower end plates of the vacuum vessel be constructed of an insulating material such as ceramic, and that the cylindrical body be constructed of an easily available and inexpensive metal material, rather than an expensive metal such as Kovar.

The present invention has been made in view of the above-mentioned problems, and makes it possible to easily and inexpensively increase the diameter of the vacuum vessel of a vacuum shield or disconnector, and to make it possible to join a metal cylinder and an insulating disk. The purpose of the present invention is to provide a vacuum shield and disconnector which can have high airtightness and mechanical strength, and can have a metal cylinder with excellent arc resistance and mechanical strength.

The present invention makes it possible to use common metals (for example, non-magnetic stainless steel) for the cylindrical body of the vacuum container without using special alloys such as Kovar, and to ensure airtight connection with insulating members. In addition, in order to prevent damage due to thermal stress, the joint is bonded via an auxiliary shield at the joint portion. For this reason, as a concrete means to use, a cylindrical vacuum container is made of a metal material such as ceramic which can be plastically deformed during the slow cooling process after brazing due to the thermal stress generated by cooling after brazing. It is constructed by airtightly joining insulating disks made of an inorganic insulator with the flange portion of the auxiliary shield interposed therebetween. Hereinafter, one embodiment of the present invention will be described in detail using the drawings.

The figure is a half-cut sectional view of a vacuum shear breaker according to the present invention, which has insulating disks 2, 2 made of an inorganic insulator at both ends of a metal cylinder 1, which can be plastically deformed by thermal stress. Auxiliary shield 3 made of metal material
A vacuum container 4 is constructed by airtightly joining the flange portions 3a of the insulating disks 2, and a pair of fixed and movable electrodes are introduced into the vacuum container 4 from the center of each insulating disk 2 so as to be able to approach and separate from each other. A pair of fixed and movable electrodes 7 and 8 are provided via rods 5 and 6 so as to be able to come into contact with and separate from each other.

That is, the metal cylinder 1 constituting a part of the vacuum vessel 4 is made of austenitic stainless steel (hereinafter simply referred to as "stainless steel") which is non-magnetic, has relatively high mechanical strength, and has excellent arc resistance. ), and is formed into a cylindrical shape, and stepped fitting portions 9 having an appropriately larger diameter than the inner diameter are provided on the inner peripheral portions of both ends thereof.

Note that the metal cylinder 1 is not limited to one made of stainless steel; for example, it can be made of relatively thick copper, or relatively inexpensive if the current carrying capacity of the vacuum shield or disconnector is small. A material made of iron may also be used. The stepped fitting portions 9 at both ends of the metal cylinder 1 have flange portions 3a integrally molded on the outer ends thereof, respectively. It is fitted through the step and is airtightly joined to the step by brazing. Each auxiliary shield 3 is used to prevent metal vapor from adhering to the inner end surface (vacuum side) of the insulating disk 2 and the bellows, etc. together with the arc shield described later. It is made of copper, which is a non-magnetic material, and can be plastically deformed during the slow cooling process after brazing due to thermal stress caused by cooling after brazing. In addition, each auxiliary shield 3
Not limited to those made of copper, for example, if the current carrying capacity of the vacuum shield is small, the thermal stress generated by cooling after brazing with the insulating disk 2 may cause the slow cooling process after brazing. In addition to being plastically deformable, it is also possible to use a magnetic material made of iron, which is cheaper than copper.

The insulating disks 2 are fitted into the stepped fitting parts 9 at both ends of the metal cylinder 1, and are hermetically joined to the flange part 3a of the auxiliary shield 3. That is, each insulating disk 2 is made of an inorganic insulator such as alumina ceramic or crystallized glass, and is formed into a disk shape with a hole 10 in the center. One end surface in the periphery is made of Mn-Ti alloy or Mo with a thermal expansion coefficient similar to that of alumina ceramic.
-Metallized layer 11, 1 made of Mn-Ti alloy etc.
2 is formed. In addition, each metallized layer 1
1 and 12, the insulating disk 2 is subjected to a grinding process, and in order to facilitate this grinding process, between each metallized layer 11, 12,
A groove 13 having a depth of about 0.1 to 0.5 mm is formed in a circular shape. Each insulating disc 2 is fitted into stepped fitting parts 9 at both ends of the metal cylinder 1, and is airtightly connected to the flange part 3a of the auxiliary shield 3 through the metallized layer 11 near the outer peripheral edge. is joined to.

A ring-shaped auxiliary member 14 having a substantially J-shaped cross section is attached to the metallized layer 12 around the hole 10 in the one (upper side in the figure) insulating disk 2 through the end of its outer peripheral portion 14a. Airtightly joined by brazing.

The auxiliary member 14 has a joint portion between one insulating disc 2 and the fixed electrode rod 5 that is hermetically joined to the insulating disc 2.
This is to prevent deterioration in airtightness and mechanical bonding strength due to thermal stress caused by the difference in coefficient of thermal expansion between the two, which is caused by cooling after brazing with the insulating disk 2. Made of copper or iron that can be plastically deformed during the slow cooling process after brazing due to thermal stress. Then, at the end of the inner peripheral part 14b of the auxiliary member 14, copper or copper alloy is introduced into the vacuum vessel 4 by passing through the hole 10 of one insulating disk 2 and the inner peripheral part 14b of the auxiliary member 14. The fixed electrode rod 5 is hermetically joined to the outer end of the fixed electrode rod 5 by brazing via a stepped portion of a larger diameter portion 5a formed integrally with the fixed electrode rod 5. Near the inner end of the fixed electrode rod 5, an arc shield 15 formed in a cup shape with a larger diameter than the auxiliary shield 3 is provided at the center of the bottom with its open end facing one of the insulating discs 2. While being fitted through the hole 16, movement in the direction of one insulating disk 2 is regulated by a retaining ring 17 such as a snap spring fitted into the circumferential groove 5b near the inner end of the fixed electrode rod 5. It is fixed by attaching it. The arc shield 15 is made of stainless steel, copper, or iron, and the vicinity of its open end is concentrically overlapped with the vicinity of the inner end of one of the auxiliary shields 3 and the fixed electrode rod 5 .

Further, the fixed electrode 7 formed in a substantially disk shape is fitted into the inner end of the fixed electrode rod 5 via a recess 7a bored in the center of the contact back surface (upper surface in the figure). They are also fixed together by brazing.

In the metallized layer 12 around the hole 10 in the other insulating disk 2 (lower in the figure), a bellows 18 made of stainless steel and housed concentrically in the vacuum container 4 is attached with the inner diameter side of one end extending in the axial direction. Cylindrical portion 18 formed by extending in the vertical direction (in the figure)
They are hermetically joined by brazing through the ends of a. At the other end of the bellows 18, a mounting portion 1 is provided with the inner diameter side extending inward in the radial direction (horizontal direction in the figure).
8b is formed in a ring shape, and this mounting portion 1
8b, the movable electrode rod 6 made of copper or steel alloy is introduced into the vacuum vessel 4 by passing through the hole 10 of the other insulating disk 2 and the center of the bellows 18.
However, there is a flange part 6 integrally formed near the inner end of the flange part 6.
They are airtightly joined by brazing through a.
Near the inner end of the movable electrode rod 6, an arc shield 19 made of the same metal material as the arc shield 15 fixed to the fixed electrode rod 5 and formed in a similar cup shape has an open end connected to the other insulating circle. It is fitted through a hole 20 formed in the center of the bottom facing the plate 2, and is fixed by brazing while being restricted from moving in the direction of the other insulating disk 2 by the flange 6a of the movable electrode rod 6. There is. It should be noted that the vicinity of the opening end of this arc shield 19 and the vicinity of the inner end of the other auxiliary shield 3 are concentrically overlapped with the movable electrode rod 6 in the closed state as shown in the figure. be. Moreover, the movable electrode 8 formed in a substantially disk shape is provided at the inner end of the movable electrode rod 6.
are fitted through a recess 8a formed in the center of the contact back surface (lower surface in the figure) and are fixed by brazing. A groove 8b is formed in the contact surface of the movable electrode 8 in a circular shape around the center thereof, and a ring-shaped contact 21 is fitted into the groove 8b so as to protrude appropriately from the contact surface. It is fixed by brazing.

In addition, in the embodiment described above, the metal cylinder 1
Although a case has been described in which stepped fitting parts 9 are provided on the inner periphery of both ends of the metal cylinder 1 in order to position the auxiliary shield 3 and the insulating disk 2 against the metal cylinder 1, the method is not limited to this method. Instead of providing a stepped fitting part on the auxiliary shield 3, a cylindrical part with approximately the same diameter as the inner diameter of the metal cylinder 1 and a stepped cylindrical part with an L-shaped cross section connected to the flange part 3a of the auxiliary shield 3 are provided. The auxiliary shield 3 of the insulating disk 2 is positioned and joined to the metal cylinder by the step part and the stepped part of the stepped cylinder part.
Alternatively, the positioning and joining may be performed.

To manufacture the vacuum shield and disconnector having the above configuration, first, the other insulating disc 2 is supported horizontally with its metallized layers 11 and 12 facing upward, and each The structural members are temporarily assembled as shown in the figure by interposing a brazing material between the joints. Next, the temporarily assembled vacuum shield and disconnector is placed in a vacuum furnace and heated. This heating also serves to exhaust, degas, and remove the oxide film on the brazed parts, so it is desirable that the temperature be as high as possible, below the temperature at which the brazing material does not melt, and the pressure inside the vacuum furnace should be below 10 ^-4 Torr. It is desirable to do so. Then, in a vacuum furnace, the stainless steel is heated to 1050°C or above 900°C to activate the surface of the stainless steel.
While evacuation is carried out so that the temperature rises to less than ℃ and the pressure becomes less than 10 ^-5 Torr, each component is hermetically joined using a brazing filler metal. Finally, the inside of the vacuum furnace is lowered from the brazing temperature to a predetermined temperature by slow cooling (furnace cooling), held at this temperature for a predetermined time, and then lowered to room temperature by slow cooling again, or the inside of the vacuum furnace is slowly cooled. If the vacuum shield and disconnector are removed after the brazing temperature has been lowered to room temperature, the desired result can be obtained.

In the above manufacturing method, the upper limit of the heating temperature can be increased to 900°C by applying nickel plating treatment to the brazed portion of the metal cylinder 1 or bellows 18 made of stainless steel in advance.
It can be as follows.

Here, the insulating disk 2 made of an inorganic insulator such as alumina ceramic and the metal cylinder 1 made of stainless steel, copper, or iron are bonded to each other using copper or iron, even though their thermal expansion coefficients are significantly different. The reason why good airtightness and mechanical bonding force can be achieved by interposing the flange portion 3a of the auxiliary shield 3 is considered to be due to the following reason.

As described above for the manufacturing process of the vacuum shield and disconnector, the member brazed to the insulating disc 2 is the auxiliary shield 3, and the metal cylinder 1 is brazed to the auxiliary shield 3. This brazing is performed simultaneously on the three members of the metal cylinder 1, the insulating disk 2, and the auxiliary shield 3 under the same heating conditions, resulting in thermal stress in the metal cylinder 1 caused by cooling after brazing. It is thought that this is because the mechanical strength of the insulating disc 2 is lowered because it is absorbed as plastic deformation of the auxiliary shield 3 made of copper or iron.

That is, it is known that the tensile strength of copper or iron with respect to temperature increases as the temperature decreases, and that the elongation of copper or iron with respect to temperature decreases as the temperature decreases. Therefore, copper,
The auxiliary shield 3 made of iron is heated to a temperature of 900°C or higher to 1050°C.
When the auxiliary shield 3 made of copper or iron is brazed to the insulating disk 2 made of an inorganic insulating material such as alumina ceramic at a high temperature below 200 yen, the tensile strength of the auxiliary shield 3 made of copper or iron will exceed that of the insulating disk 2 made of an inorganic insulating material such as alumina ceramic.
Since the mechanical strength is extremely small compared to the mechanical strength of the material, it is plastically deformed during the slow cooling process after brazing due to thermal stress generated by cooling after brazing. for,
It is considered that the airtightness of the joint between the two is not impaired when the two are cooled to room temperature, and the residual thermal stress is extremely small.

Although iron has a higher tensile strength at various temperatures than copper, and its creep elongation with respect to loading time under constant temperature conditions is smaller than that of copper, it is similar to copper when it is used with inorganic insulators such as alumina ceramics. It is thought that the reason why it can be bonded well is because its coefficient of thermal expansion is smaller than that of copper.

Furthermore, the bellows 18 can achieve high airtightness and mechanical strength by joining the insulating disk 2 made of an inorganic insulator such as alumina ceramic and the bellows 18 made of stainless steel.
The bellows 18 is extremely thin, approximately 0.1 to 0.2 mm, and the thermal stress caused by cooling after brazing the two is extremely small compared to the mechanical strength of the insulating disk 2 made of an inorganic insulator. This is thought to be because the material itself undergoes plastic deformation during the slow cooling process after brazing.

As described above, in the present invention, auxiliary shields made of a metal material that can be plastically deformed by thermal stress are disposed facing each other near both ends in a metal cylinder, and each auxiliary shield is attached to the outer end of the cylinder via a flange integrally molded. A vacuum vessel is constructed by airtightly bonding an insulating disk made of an inorganic insulator to the flange portion of each of the auxiliary shields near the outer periphery of the auxiliary shield. Since a pair of electrodes are provided so that they can come into contact with and separate from each other through a pair of electrode rods that are introduced from the center of an insulating disk so that they can approach and separate from each other, it is easy to increase the diameter of the vacuum vessel. Moreover, it can be performed at low cost, and the metal cylinder having different coefficients of thermal expansion and the insulating disk can be joined with high airtightness and mechanical bonding strength. Furthermore, the metal cylinder can be made of a metal material with excellent arc resistance and mechanical strength. Further, the number of constituent members of the vacuum container can be reduced and temporary assembly can be easily performed.

[Brief explanation of the drawing]

The figure is a half-cut sectional view of a vacuum shield disconnector according to the present invention. DESCRIPTION OF SYMBOLS 1... Metal cylinder, 2... Insulating disk, 3... Auxiliary shield, 3a... Flange part, 4... Vacuum container, 5, 6... Electrode rod, 7, 8... Electrode.

Claims (1)

[Claims] 1. Auxiliary shields made of a metal material that can be plastically deformed by thermal stress are placed opposite each other near both ends of the metal cylinder, and each auxiliary shield is attached to the end of the metal cylinder via a flange integrally molded to the outer end of each auxiliary shield. and an insulating disc made of an inorganic insulator is hermetically joined to the flange portion of each of the auxiliary shields near the outer periphery thereof to form a vacuum vessel;
A vacuum breaker comprising a pair of electrodes that are movable into contact with each other through a pair of electrode rods that are introduced into the vacuum container from the center of each insulating disk so as to be able to move toward and away from each other.