JP3176489B2 - Vacuum valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum valve having a pair of electrodes which can be brought into contact with and separated from an insulating container, and a barrier surrounding the electrodes.

[0002]

2. Description of the Related Art A vacuum valve is a hermetically sealed container having a metal lid covering both ends of a cylindrical insulating container, and the inside thereof is kept in a vacuum state. Then, a movable electrode and a fixed electrode are provided facing each other from both metal lids in abutting manner, and the electric circuit is opened and closed by bringing the tips of both electrodes into and out of contact. In this vacuum valve, a technique is known in which a vertical magnetic field is applied between both electrodes to prevent local concentration of the generated arc, thereby improving the breaking capacity.
Japanese Patent No. 627 discloses an invention in which a permanent magnet is accommodated in a concave portion formed on the abutting surface of both electrodes and a magnetic body is disposed on the front surface to apply a vertical magnetic field between the two electrodes.

[0003]

SUMMARY OF THE INVENTION In this conventional invention,
Since the permanent magnets are opposed to each other with the magnetic material interposed therebetween, the longitudinal magnetic field acting between the two electrodes cannot be sufficiently strengthened. To reinforce this, a permanent magnet having a stronger magnetic force is sealed. There is a need. However, if a permanent magnet with a strong magnetic force is used, this magnetic field also extends outside the insulating container, and ferromagnetic substances such as iron powder floating in the air as dust adsorb to the outer surface of the insulating container, and However, there is a problem that insulation on the outer surface is reduced.

Accordingly, an object of the present invention is to provide a vacuum valve which enhances a vertical magnetic field between both electrodes to enhance a breaking performance and maintain external insulation.

[0005]

Therefore, according to the present invention, a metal spacer made of a ferromagnetic material is fixed to the bottom surface of a housing recessed at each end of both electrodes, and further, both electrodes are attached to the front surface of the metal spacer. A cylinder made of a ferromagnetic material that has a permanent magnet that provides a longitudinal magnetic field between the two electrodes, and that has a peripheral surface and a front portion of the permanent magnet in a non-contact state, and that has an inner surface of an insulating container that surrounds between the two electrodes. Barrier is provided.

[0006]

When the electrodes are separated to open the electric circuit, an arc is generated between the electrodes. At this time, a permanent magnet is sealed in a housing recessed at the tips of both electrodes, and a magnetic field is applied by the permanent magnets. The magnetic circuit of this magnetic field is composed of a ferromagnetic barrier enclosing the space between the two electrodes in a cylindrical shape, the other metal spacer, and the other, from a ferromagnetic metal spacer sealed behind one of the permanent magnets. A magnetic circuit is formed via the permanent magnet. Since the metal spacer and the barrier made of a ferromagnetic material are excellent in magnetic permeability, the metal spacer and the barrier form a magnetic circuit having a small magnetic resistance, and the strength of the vertical magnetic field applied between both electrodes is increased. As a result, the arc is generated in a large vertical magnetic field, so that the arc is uniformly dispersed without being locally concentrated, and the breaking performance is enhanced.

The barrier not only reduces the magnetic resistance of the magnetic circuit, but also prevents the magnetic field from leaking out of the insulating container. Therefore, the ferromagnetic substance floating in the atmosphere is not attracted by the magnetic field and does not adhere to the surface of the insulating container. Also, a metal spacer made of a ferromagnetic material is fixed to the bottom surface of the accommodation portion recessed at each end of both electrodes, and a permanent magnet that applies a vertical magnetic field between both electrodes is fixed to the front surface of the metal spacer, Since the peripheral surface and the front part of the permanent magnet are housed in a non-contact state, the temperature of the permanent magnet rises slowly with the occurrence of the arc, and the heat is rapidly radiated with the disappearance of the arc. It is prevented that the magnet is heated to such an extent that the magnetic force of the magnet decreases.

[0008]

According to the present invention, a metal spacer made of a ferromagnetic material is fixed to the bottom surface of the housing recessed at each end of both electrodes, and a vertical magnetic field is applied between the two electrodes on the front surface of the metal spacer. A permanent magnet is fixed, the peripheral surface and the front part of the permanent magnet are accommodated in a non-contact state, and a cylindrical barrier made of a ferromagnetic material surrounding the two electrodes is provided on the inner surface of the insulating container. In addition, a magnetic circuit with low magnetic resistance is constructed, and the magnetic action to the outside of the insulating container is shielded, so that the vertical magnetic field is increased and the external insulation of the insulating container is protected to ensure the reliability of vacuum valve insulation It has the effect of enhancing the character.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to FIGS.

As shown in FIG. 1, the vacuum valve of this embodiment is a sealed container in which metal lids 2 and 3 are fixed to both open ends of a cylindrical insulating container 1 made of insulating ceramics such as porcelain by brazing. It has been. A movable electrode 4 having a contact plate 6 fixed to the tip of a conductive shaft 5 is attached to the one metal cover 2.
However, the other metal lid 3 is provided with a fixed electrode 8 formed by fixing a contact plate 6 to the tip of a conductive shaft 9 so as to penetrate therethrough. They are arranged facing each other on a coaxial line. The movable electrode 4 is moved forward and backward by a driving device (not shown) to contact or separate the contact plates 6 and 6. The movable electrode 4 is provided with a bellows 7 and a bearing 12 fixed to the bellows 7 to maintain a vacuum state.

Each of the conductive shafts 5 and 9 has a thermal conductivity of about 3.5 J /
The conductive shafts 5 and 9 are provided with recesses 5a and 9a at the end surfaces thereof. Hereinafter, the movable electrode 4 shown in FIG. 2 will be described. Although the tips of the electrodes 4 and 8 have the same structure, a thick cylindrical metal spacer 11 is provided on the bottom of the housing 5a in the housing 5a. It is fixed. The metal spacer 11 is a ferromagnetic metal having a high magnetic permeability, such as pure iron, martensite or ferrite, and a so-called soft magnetic material having a small coercive force. Furthermore, in the accommodation part 5a,
The columnar permanent magnets 10 having the same diameter are laminated and fixed to the metal spacer 11. The opening of the housing 5a is covered with a contact plate 6. The contact plate 6 is a disk having a larger diameter than the tip surface of the conductive shaft 5, and is welded to the tip of the conductive shaft 5 by brazing 13.

As a result, the metal spacer 11 and the permanent magnet 10 fixed to the bottom surface in the housing 5a are brought into non-contact with the peripheral surface thereof and the opening of the housing 5a by the gap S. And only contacts the bottom surface of the housing portion 5a via the. Therefore, even if the contact plate 6 is rapidly heated when an arc is generated, the heat is transferred from the bottom surface of the housing portion 5a to the metal spacer 11 having a thermal conductivity of about 0.1 J / cm.SK.
Only by the heat conduction through the permanent magnet 1
0 is prevented from being rapidly heated. Permanent magnet 1
Reference numeral 0 denotes a case where a magnetic material such as a samarium-cobalt-based or iron-boron-based anisotropic magnet material is housed in the housing portions 5a and 9a, and the metal lids 2 and 3 are fixed by brazing to form a closed container. An external magnetic field is applied in the axial direction from the outside of the insulating container 1 to be magnetized to form a permanent magnet. this is,
Since the magnetic force may be reduced when exposed to high temperatures, the magnet is magnetized after forming the closed container, and as described above, even when an arc is generated, the permanent magnet is magnetized so as not to lose the magnetic force of the magnetized permanent magnet. The magnet 10 is prevented from being rapidly heated.

In FIG. 1, reference numeral 14 denotes a metal barrier, which is attached to a projection 1a provided on the inner surface of the insulating container 1 and is formed in a cylindrical shape surrounding both electrodes 4 and 8, and is used for shutting off when shut off. An arc shield is provided to prevent metal gas generated from the electrodes 4 and 8 due to the arc from being deposited on the inner peripheral surface of the insulating container 1. As shown in FIGS. 1 and 3, the barrier 14 of this embodiment is made of the same pure iron, martensite or ferrite ferromagnetic metal as the metal spacer 11,
A so-called soft magnetic material having a small coercive force is used. In this way, the two permanent magnets 10,
A magnetic circuit is formed around the reference numeral 10. The barrier 14 has a slightly longer length so that the magnetic field from the rear end face of the metal spacer 11 is absorbed by the end of the barrier 14 and is formed in a cylindrical shape surrounding the electrodes 4 and 8. .

As described above, in this embodiment, the barrier 1 is separated from the metal spacer 11 by the permanent magnet 10 on the movable electrode 4 side.
4. Metal spacer 11 and permanent magnet 10 on fixed electrode 8 side
A magnetic circuit R for generating a vertical magnetic field is formed between the two permanent magnets 10 and 10.

Next, the operation of this embodiment will be described with reference to FIG. 3. Now, when the movable electrode 4 is retracted from the closed state and a small gap is formed between the contact plates 6, 6, both contact plates will be described. 6,6
An arc occurs between them. At this time, a magnetic circuit R is formed by the permanent magnets 10 and 10 sealed in the electrodes 4 and 8, and the magnetic circuit R is formed by a metal spacer 11 and a barrier 14 which are ferromagnetic and has a high magnetic permeability. The path is formed to be long. For this reason, the metal spacers 11 and the barriers 14 having a lower magnetic resistance than the case where the conductive shafts 5 and 9 or the vacuum space, which is a nonmagnetic metal, are used as magnetic paths.
Circuit R having a low magnetic resistance because the
Is configured. In particular, a metal spacer 11 is provided so as to be laminated on the permanent magnet 10, and the barrier 14 is formed so that the magnetic field generated from the rear end face of the metal spacer 11 is absorbed by the end of the barrier 14 through the shortest magnetic path. Since it is formed in a slightly longer cylindrical shape, it is a magnetic circuit having a smaller magnetic resistance. As described above, a large vertical magnetic field is applied between the electrodes 4 and 8 by the magnetic circuit R having a small magnetic resistance, and the arc becomes an evenly dispersed arc without local concentration in the large vertical magnetic field, thereby improving the breaking performance.

The magnetic circuit R is composed of the permanent magnet 1
Since a magnetic effect on the outer region is prevented by being shielded by the ferromagnetic barrier 14 provided on the outer periphery of the insulating container 1, the magnetic field hardly acts on the outside of the insulating container 1. This prevents the ferromagnetic substance floating in the atmosphere from adsorbing to the outer surface of the insulating container 1, and does not cause a decrease in external insulation due to the ferromagnetic substance.

In this embodiment, the housings 5a, 9a
A permanent magnet 10 is mounted via a metal spacer 11, and the peripheral surface and the front portion of the permanent magnet 10 are not in contact with the electrodes 4 and 8 due to the gap S. The temperature of the permanent magnet 10 rises slowly due to the excessive heating.
Since the heat is rapidly radiated from 9, the permanent magnet 10 is prevented from being heated to such an extent that its magnetic force decreases.

Further, in this embodiment, an example is shown in which the arc shield is formed of a ferromagnetic material to provide a barrier having a simple structure. However, the present invention may be practiced as a configuration in which a barrier is provided separately from the arc shield. it can.

[Brief description of the drawings]

FIG. 1 is a partially cutaway front view.

FIG. 2 is an enlarged sectional view of a movable electrode.

FIG. 3 is a distribution diagram of a magnetic field.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Insulating container 4 ... Movable electrode 8 ... Fixed electrode 10 ... Permanent magnet 11 ... Metal spacer 14 ... Barrier

──────────────────────────────────────────────────続 き Continued on the front page (72) Kazuaki Kato 2-56, Suda-cho, Mizuho-ku, Nagoya-shi, Aichi Japan Inside Insulator Co., Ltd. (72) Takashi Irie 2-56, Suda-cho, Mizuho-ku, Nagoya-shi, Aichi No. Japan Insulator Co., Ltd. (72) Inventor Setsuo Kosaka 2-6, Suda-cho, Mizuho-ku, Nagoya-shi, Aichi Japan Insulator Co., Ltd. (56) References JP-A-61-66324 (JP, A) JP-A-59 JP-A-207523 (JP, A) JP-A-60-12628 (JP, A) JP-A-62-206726 (JP, A) JP-A-60-3823 (JP, A) JP-A-52-100166 (JP, U (58) Fields surveyed (Int. Cl. ⁷ , DB name) H01H 33/66

Claims (1)

(57) [Claims] 1. A vacuum valve having a pair of opposed rod-shaped electrodes provided in a cylindrical insulating container so as to be able to contact and separate in abutting manner, wherein a ferromagnetic material is provided on a bottom surface of a housing recessed at each end of the two electrodes. A metal spacer made of a body is fixed, and a permanent magnet that applies a vertical magnetic field between both electrodes is fixed to the front surface of the metal spacer, and the peripheral surface and the front part of the permanent magnet are housed in a non-contact state, A vacuum valve, wherein a cylindrical barrier made of a ferromagnetic material surrounding the two electrodes is provided on an inner surface of the insulating container.