JPH0113619B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a vacuum shield breaker, and its purpose is to make the entire vacuum shield breaker made of non-magnetic material so that it can be applied as a vacuum shield breaker for high-frequency current switching. It is to do so.

The vacuum container constituting the vacuum chamber disconnector is composed of a cylinder and end plates that seal the upper and lower ends of the cylinder. Ceramic or hard glass, which is an insulator, is generally used as the material for the cylinder in order to maintain dielectric strength, and the upper and lower ends are heated to join the upper and lower end plates described below to the cylinder. In order to absorb the difference in thermal expansion caused by the cylindrical material, we use a bonding metal such as Fe-Ni alloy or Fe-Ni-Co alloy that has a coefficient of thermal expansion similar to that of the cylinder material. On the other hand, stainless steel is used for the upper and lower end plates, and the end plates are fixed to both ends of the cylinder via the above-mentioned joining metal.

In addition, among the components housed in the vacuum container, the conductor is made of Cu or Al, the electrode is made of Cu as the main ingredient, the bellows is made of stainless steel or phosphor bronze, and the shield is made of iron or Cu. Generally, it is selected as follows.

Among the above-mentioned constituent members, Fe-Ni is a metal that is attached to both ends of the cylinder and is the joining metal between the cylinder made of insulating material and the upper and lower end plates made of stainless steel.
Alloys, Fe-Ni-Co alloys, etc., are inherently limited because the material of the cylinder is ceramic or hard glass, and it has been difficult to apply materials other than the above-mentioned bonding metals. . The reason is,
It was considered to use soft Cu as the bonding metal, but the difference between the coefficient of thermal expansion of Cu and that of ceramic or hard glass is large, so slow cooling after brazing is required to bond the bonding metal and the cylinder. This is because it was thought that brazing defects would occur during the process.
However, since this joining metal is a magnetic material, it is easily melted and damaged by resistance heating caused by eddy current when high frequency current is applied.
It has a current capacity of up to several 100 A, making it impossible to apply it to circuit breakers for high-frequency current switching of several KHz and several 100 A, which have been particularly required in recent years.

The present invention was proposed to solve the above-mentioned drawbacks, and its feature is that the cylinder is made of non-magnetic stainless steel, while the upper and lower end plates that seal the ends of the cylinder are made of ceramic disks. A vacuum vessel is constructed by joining this stainless steel and the upper and lower end plates together via a ring-shaped joining member made of Cu material as a member that absorbs the difference in thermal expansion due to the difference in the materials of both members. Or with an Al conductor,
An electrode part mainly composed of Cu and a bellows etc. made of stainless steel or phosphor bronze are arranged in the vacuum container, and all the constituent members are non-magnetic, so the vacuum shield is suitable for switching high-frequency current. is composed of

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a longitudinal cross-sectional view of a vacuum sheath disconnector according to the present invention, in which insulating end plates 2, 2 made of an inorganic insulator are attached to both ends of a metal cylinder 1 to form a ring-shaped joint member. 3, 3 are interposed and airtightly joined to form a vacuum vessel 4, and a pair of conductors are introduced from each insulating end plate 2 into the vacuum vessel 4 so as to be able to approach and separate from each other,
In other words, a pair of fixed and movable electrodes 7 and 8 are provided via fixed and movable electrode 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, which is a non-magnetic material and has high mechanical strength, and is formed into a cylindrical shape. As shown in FIGS. 1 and 2, stepped fitting portions 9 having a diameter larger than the inner diameter are provided on the inner periphery of both ends of the metal cylinder 1. As shown in FIGS.
In each stepped fitting part 9 of the metal cylinder 1, cylindrical auxiliary shields 10, 10, which are arranged opposite to each other near both internal ends of the metal cylinder 1, are connected to each other via a flange part 10a integrally formed on the outer end of each of the stepped fitting parts 9. While being fitted, the outer peripheral surfaces of each flange portion 10a are joined and fixed by brazing. Each auxiliary shield 10
is made of austenitic stainless steel, which is a non-magnetic material, and in combination with an arc shield, which will be described later, the metal vapor generated when the fixed and movable electrodes 7 and 8 come into contact with each other is transferred to the inner end surface of each insulating disk 2, or the metal vapor generated when the fixed and movable electrodes 7 and 8 come into contact with each other. This is to prevent it from sticking to the bellows.

Each stepped fitting part 9 of the metal cylinder 1 has a ring-shaped cylindrical part 3a in the axial direction (vertical direction in FIG. 1) and a radial direction (first
The joining member 3, which is formed into an L-shaped cross section and includes a flange portion 3b (in the left-right direction in the figure), is fitted through the cylindrical portion 3a and is hermetically joined by brazing. Each joining member 3 is
This is to increase the reliability of the airtight joint between the metal cylinder 1 and the insulating end plate 2, which have different coefficients of thermal expansion. Each flange portion 3 is made of copper that can be plastically deformed during the slow cooling process after brazing due to the thermal stress generated by brazing.
b is located inside the metal cylinder 1.

Here, the reason why Cu was used instead of Fe-Ni material or Fe-Ni-Co material for the ring-shaped joining member that has been generally used is as follows. Must be non-magnetic material. Cu is softened by high-temperature brazing in a vacuum and easily deforms plastically, allowing the Cu member to absorb residual thermal stress caused by the difference in expansion coefficients between ceramic and Cu.
It has a high specific gravity and is smooth, so it can absorb vibrations well due to a lower elastic modulus (short damping time constant). This is because ceramic is a brittle material and has a relatively large elastic modulus but a low tensile strength at break. Those skilled in the art believe that it is undesirable to use Cu as a bonding metal, so it was not used, but when we actually used it, we found that it had a large difference in coefficient of thermal expansion compared to ceramics, etc. It was found that there were no problems in use because it was easily plastically deformed and for the reasons mentioned above.

The adoption of Cu for the bonding member in the present invention is attributable to the above points.
This is because in the case of Ni-Co materials, it takes time to dampen vibrations, reducing the level of repeated fatigue failure.

Next, the insulating end plates 2 are fitted into each of the joining members 3 and are hermetically joined. This insulating end plate 2 is made of an inorganic insulator such as alumina ceramic or crystallized glass, and is formed into a disk shape with a hole 11 in the center. Near the outer periphery, metallized layers 12 and 13 made of Mn--Ti alloy, Mo--Mn--Ti alloy, or the like having the same coefficient of thermal expansion as the insulating end plate 2 are formed, respectively. Note that the metallized layer 1 of each insulating end plate 2
When forming the holes 2 and 13, a grinding process is performed near the outer circumferential edge of the inner circumferential surface and one end surface of the hole 11, and a grinding process is performed near the outer circumferential edge of the one end surface to facilitate the grinding process. An annular protrusion 14 protruding by about 0.1 to 0.5 mm is formed on the periphery. Each insulating end plate 2 is fitted into the cylindrical portion 3a of the respective joining member 3, and the metallized layer 13 on one end surface thereof is hermetically joined to the flange portion 3b of the joining member 3 by brazing. .

In the hole 11 of the one insulating end plate 2, there is provided an auxiliary member 15 which is ring-shaped and has an L-shaped cross section with an axial cylindrical portion 15a and a radial locking portion 15b perpendicular to the axial cylindrical portion 15a. are fitted through the cylindrical portion 15a and hermetically joined to the metallized layer 12 by brazing.

This auxiliary member 15 consists of a metal cylinder 1 and an insulating end plate 2.
Similarly to the joining member 3 interposed between the insulating end plate 2 and the fixed electrode rod 5 that is hermetically joined thereto, thermal stress caused by the difference in thermal expansion coefficient between the two This is to prevent deterioration of the reliability of the airtight joint at the joint of the insulating end plate 2 made of alumina ceramic etc. due to thermal stress caused by the brazing with the insulating end plate 2, which causes plastic deformation during the slow cooling process after brazing. Made of flexible copper (Cu).
A fixed electrode rod 5, which is made of copper or a copper alloy and is a non-magnetic material, is inserted into the vacuum container 4 through an auxiliary member 15. Fixed electrode rod 5
has an outer diameter that is almost the same as the inner diameter of the auxiliary member 15, and a circumferential groove 5a near the longitudinal center of the auxiliary member 15.
By abutting the retaining ring 16, such as a snap spring, fitted onto the locking portion 15b of the reinforcing member 15, the movement in the direction of the other insulating end plate 2 is restricted, and the cylinder of the auxiliary member 15 is secured by brazing. Part 15
It is airtightly joined to a.

At the inner end of the fixed electrode rod 5, an arc shield 17 formed in a cup shape with a larger diameter than the auxiliary shield 10 has an open end connected to one insulating end plate 2.
and is fitted through a hole 18 provided at the center of the bottom. The movement of the arc shield 17 in the direction of the other insulating end plate 2 is regulated by a retaining ring 19 fitted in the circumferential groove 5b near the inner end of the fixed electrode rod 5, and the fixed electrode rod 5 is It is fixed near the inner end of the The arc shield 17 cooperates with the auxiliary shield 10 on the side of the one insulating end plate 2 described above to prevent metal vapor from adhering to the one insulating end plate 2, and is made of austenitic stainless steel.
The vicinity of the open end and the vicinity of the open end of the auxiliary shield 10 on one side of the insulating end plate 2 are concentrically overlapped with the fixed electrode rod 5 as the center. Furthermore, the inner end of the fixed electrode rod 5 is formed into a substantially disk shape.
The fixed electrode 7, whose main component is Cu, is fitted through a recess 7a formed in the center of the contact back surface (upper surface in FIG. 1) and is fixed by brazing.

In the hole 11 of the other insulating end plate 2, a bellows 20 made of austenitic stainless steel or phosphor bronze, which is a non-magnetic material, is housed concentrically in the vacuum container 4, and the bellows 20 is arranged axially on the inner diameter side of one end thereof. It is stretched, formed, fitted, and hermetically joined to the metallized layer 12 by brazing. As shown in FIG. 3, the other end of the bellows 20 is integrally molded with a mounting portion 20b having a substantially V-shaped cross section, extending in the axial direction on the inner diameter side and bent inward. In the vacuum container 4, there is a bellows 2.
The movable electrode rod 6 inserted through the center of the bellows 20 is introduced with its inner end appropriately protruding from the mounting portion 20b of the bellows 20. The movable electrode rod 6 is
It is made of Cu or Al and is a non-magnetic material.
A retaining ring 21 such as a snap spring fitted in the circumferential groove 6a near the inner end of the bellows 20 is attached to the mounting portion 2 of the bellows 20.
0b, the other insulating end plate 2
The movement in the direction is restricted, and the inner end portion of the bellows 20 and the mounting portion 20 are fixed by brazing.
It is hermetically joined to b.

At the inner end of the movable electrode rod 6, similarly to the arc shield 17 of the fixed electrode rod 5, there is an arc shield 22 formed in a cup shape having a larger diameter than the auxiliary shield 10 on the other insulating end plate 2 side. , its open end faces the other insulating end plate 2, and is fitted through a hole 23 provided at the center of its bottom. Then, the arc shield 22 is connected to the retaining ring 21.
movement in the direction of the other insulating end plate 2 is regulated by the movable electrode rod 6, and is fixed near the inner end of the movable electrode rod 6 by brazing. In addition, in the closed state shown in FIG. They are arranged so that they are superimposed on each other. The movable electrode 8, which is formed in a substantially disk shape, is fitted into the inner end of the movable electrode rod 6 via a recess 8a formed in the center of the opposing back surface (lower surface in FIG. 1). It is fixed by brazing. A circular groove 8b centered at the center of the facing surface of the movable electrode 8 is bored, and a ring-shaped contact 24 is appropriately protruded from the facing surface and fitted into this groove 8b. It is fixed by brazing.

In order to manufacture the vacuum shield and disconnector having the above structure, the vacuum shield and disconnector are temporarily assembled by interposing a brazing material between each component, and then brazed in a vacuum furnace. First, to temporarily assemble the vacuum shield and disconnector,
The other insulating end plate 2 is supported horizontally with the metallized layer 13 facing upward, and the cylindrical portion 20 of the bellows 20 is
A is fitted into the hole 11, and the brazing material 25 is placed around the hole 11 as shown in FIG. Next, the auxiliary member 3 is fitted to the outer periphery of the other insulating end plate 2 with the brazing material 25 interposed between the flange portion 3b and the metallized layer 13. Furthermore, the metal cylinder 1, in which the auxiliary shield 10 is fitted into the stepped fitting part 9 at one end with the brazing material 25 interposed, is fitted into the auxiliary member 3. Then, the movable electrode rod 6 is inserted into the bellows 20, and as shown in FIG.
0b, and a brazing material 25 is placed between the mounting portion 20b and the movable electrode rod 6.

It should be noted that an arc shield 22 is fitted in advance to the upper end of the movable electrode rod 6 by being locked to a retaining ring 21 with a brazing material 25 interposed therebetween.
The movable electrode rod 8, in which the contact 24 is fitted into the groove 8b with a brazing material interposed therebetween, is previously fitted into the bottom of the recess 8b with a brazing material interposed therebetween. Further, the movable electrode rod 6 is placed on the mounting portion 20b of the bellows 20 after the auxiliary shield 10 is placed on the joining member 3, and then the metal cylinder 1
The lower end of the connecting member 3 may be fitted into the joining member 3.

As mentioned above, the movable electrode 8 is placed on the other insulating end plate 2.
After temporarily assembling the movable side such as the metal cylinder 1 and the movable side such as the fixed electrode 7, etc., the fixed side such as the fixed electrode 7 is temporarily assembled on the upper end of the metal cylinder 1. That is, the fixed electrode rod 5, which has the fixed electrode 7 fitted at its lower end with a brazing material interposed therebetween, is placed on the contact 24 of the movable electrode 8 so as to be located at the center of the metal cylinder 1. The arc shield 17 is fitted onto the fixed electrode rod 5, and the arc shield 17 is secured to the retaining ring 18 near the lower end thereof with a brazing material 25 interposed therebetween. Next, the stepped fitting part 9 at the upper end of the metal cylinder 1
Then, the flange portion 10a of the auxiliary shield 10 is fitted with the brazing material 25 (see FIG. 2) interposed, and the cylindrical portion 3a of the joining member 3 is fitted with the brazing material 25.
5 and fit together. Then, the fixed electrode rod 5 is inserted into the hole 11 of one insulating end plate 2, and a brazing material is interposed between the metallized layer 13 and the flange portion 3b of the joining member 3, and the cylindrical portion 3a of the joining member 3 is Fits in. Further, the auxiliary member 15 is fitted into the fixed electrode rod 5, the cylindrical portion 15a of the auxiliary member 15 is inserted between the fixed electrode rod 5 and the metallized layer 12 of the hole 11, and the auxiliary member 15 is locked. A brazing material is interposed between the portion 15b and one insulating end plate 2 and between the locking portion 15b of the auxiliary member 15 and the fixed electrode rod 5, respectively. Then, the peripheral groove 5a near the center of the fixed electrode rod 5 is inserted into the auxiliary member 15.
When the retaining ring 16 is positioned above the locking portion 15b and the retaining ring 16 is fitted into the circumferential groove 5a, the temporary assembly of the vacuum shield and disconnector is completed.

The vacuum shield and disconnector temporarily assembled as described above,
It is heated by placing it in a vacuum furnace that can be freely evacuated to a pressure of 10 ^-5 Torr or less. Note that heating also involves exhausting, degassing, and removing the oxide film on the brazed part, so if the temperature does not melt the brazing material, the higher the heating temperature, the better, and the degree of vacuum is preferably 10 ^-5 Torr or less. Next, the temperature in the vacuum furnace is raised to 900°C or more and less than 1050°C to activate the surface of the austenitic stainless steel, and while the pressure is evacuated to 10 ^-5 Torr or less, a brazing filler metal 25 is used to connect each component. are joined airtightly.
Then, the inside of the vacuum furnace is lowered to a predetermined temperature by slow cooling (furnace cooling), held at this temperature for a predetermined time, and then lowered to room temperature again by slow cooling, or after the inside of the vacuum furnace is cooled to room temperature by slow cooling. After it has cooled, remove the vacuum chamber and disconnector to obtain the desired result.

In addition, in the above-mentioned manufacturing method, the upper limit of the heating temperature can be set to 900°C or less by applying nickel plating treatment to the brazed parts of the metal cylinder 1 or bellows 20 made of austenitic stainless steel in advance. .

Here, although the thermal expansion coefficients of the insulating end plate 2 made of an inorganic insulator such as alumina ceramic and the metal cylinder 1 made of austenitic stainless steel are significantly different, by interposing the joining member 3 made of copper, The reason why the airtightness and mechanical strength of the joint in the vacuum container can be made high is considered to be due to the following reasons.

In other words, the tensile strength and elongation of copper and the tensile strength and elongation of iron with respect to temperature are shown by curve A ₁ in Figure 4, where the horizontal axis is temperature (°C) and the vertical axis is tensile strength (Kg/mm ² ) and elongation (%). , A ₂ and curves B ₁ and B ₂ , it is known that the tensile strength increases as the temperature decreases, and the elongation almost decreases as the temperature decreases.
Therefore, when the joining member 3 or the metal cylinder 1 made of copper is brazed to the insulating end plate 2 made of an inorganic insulator such as alumina ceramic or the joining member 3 made of copper at a high temperature of 900°C or more and less than 1050°C, ,
During the slow cooling process in a vacuum furnace, copper has a very low tensile strength compared to the mechanical strength of inorganic insulators such as alumina ceramics, so it is plastically deformed by the thermal stress caused by brazing and cooled to room temperature. It is considered that the airtightness of the joint of the vacuum container is not impaired when the vacuum container is cooled, and the residual thermal stress of the joint becomes extremely small.

Further, the reason why the insulating end plate 2 made of an inorganic insulating material such as alumina ceramic and the bellows 20 made of austenitic stainless steel can be made to have high airtightness and mechanical strength is because the bellows 20 is Since the bellows 20 is formed extremely thin, usually around 0.1 to 0.2 mm, and the thermal stress generated by brazing the two is extremely small compared to the mechanical strength of the insulating end plate 2, it is assumed that the bellows 20 itself will undergo plastic deformation. Conceivable.

As explained above, according to the vacuum cutter according to the present invention, the metal cylinder 1 is made of austenitic stainless steel, the insulating end plate is made of a ceramic material, and the metal cylinder and the insulating end plate are connected via a Cu bonding member. A vacuum vessel is formed by using Cu or Al, and Cu is interposed at the joint between the conductor, that is, the electrode rod made of Cu or Al, and the ceramic end plate, and at the joint between the bellows made of nonmagnetic stainless steel and the ceramic insulating disk. As a result, all the constituent members of the vacuum shield and disconnector are made of non-magnetic materials, and therefore, unlike conventional methods, using magnetic materials in some parts makes them less susceptible to high-frequency currents. It does not melt due to resistance heating caused by electric current, and is extremely effective as a high-frequency current switch, vacuum breaker, or disconnector. Furthermore, by joining the metal cylinder and the insulating end plate via a Cu joining member, the metal cylinder can be made of austenitic material, which has high mechanical strength and is made of non-magnetic material, regardless of the coefficient of thermal expansion of the insulating end plate. Can be made of stainless steel and even
It is possible to make a vacuum shield and disconnector with low temperature rise, no noise due to magnetostrictive vibration, and able to withstand shocks during input and disconnection.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of an embodiment of a vacuum shear disconnector according to the present invention, FIGS.
FIG. 4 is an explanatory diagram showing the relationship between tensile strength and elongation of copper and iron with respect to temperature. 1... Metal cylinder, 2... Insulating end plate, 3... Joining member,
4... Vacuum container, 5... Fixed electrode bar, 6... Movable electrode bar, 7... Fixed electrode, 8... Movable electrode, 11... Hole, 2
0...bellows, 25...brazing material.

Claims (1)

[Claims] 1 Insulating end plates made of an inorganic insulator are placed at both ends of a metal cylinder made of non-magnetic stainless steel, which can be plastically deformed by thermal stress and is made of a non-magnetic material.
By interposing a ring-shaped joining member made of Cu,
A metallized layer made of a non-magnetic metal is formed at the joint between the joining member and the insulating end plate, and these are hermetically brazed together in a vacuum furnace to form a vacuum container, and a pair of Cu is placed in the vacuum container. The main component electrode is provided so as to be able to come into contact with and separate from it through a pair of electrode rods made of Cu or Al that are introduced from each insulating end plate so as to be able to approach and separate from each other, and one of the insulated end plates and the movable electrode. A vacuum shield breaker for high-frequency current switching in which all components are made of non-magnetic materials, with the bellows for airtight sealing being made of non-magnetic stainless steel or phosphor bronze.