JPH09245589A - Vacuum valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increas breakdown voltage against impulse voltage and perform miniaturization, by forming a metal coating of high electric breakdown voltage in the periphery of an electrode, in a vacuum valve provided with an arc shield between the electrode and an insulating cylinder. SOLUTION: A coating film 11A of tungten is formed in the pariphery of an upper/lower coil electrode 10, a thin reformed layer 13 is formed in an internal surface of an insulating cylinder 1. The electrode 10 coated with tungsten displays a breakdown impulse voltage characteristic about 1.9 times as compared with a copper base electrode, a creeping breakdown voltage characteristic of the layer 13 displays a characteristic of about 1.4 times as compared with in the past. Here, impurity gas in the vicinity of a solid surface of ceramic is fused to be removed by an ion beam, also crystal organization of ceramic is fined. Consequently, even when an electron emitted from a shield 12 collides against the internal surface of the cylinder 1, impurity gas is prevented from being emitted, so to make tracking difficult to extend in the internal surface of the cylinder 1, creeping insulation performance is improved.

Description

Detailed Description of the Invention

[0001]

[0001] The present invention relates to a vacuum valve.

[0002]

2. Description of the Related Art FIG. 4 is a vertical sectional view showing an example of a conventional vacuum valve. In FIG. 4, a fixed end plate 2 drawn from a stainless steel plate into a shallow U-shape is brazed to the upper end of an insulating cylinder 1 formed of an alumina ceramics material in a cylindrical shape.

Similarly, a movable side end plate 3 having the same shape as the fixed side end plate 2 is brazed to the lower end of the insulating cylinder 1 symmetrically with the fixed side end plate 2. Of these, the fixed side energization shaft 5 made of oxygen-free copper is provided at the center of the upper fixed side end plate 2.
And the lower surface of the head portion 5a formed at the upper end of the fixed side energization shaft 5 is brazed to the upper surface of the fixed side end plate 2.

On the other hand, a bush 6 is inserted in the center of the movable side end plate 3, and a movable side current-carrying shaft 7 is vertically movably provided in the bush 6. The lower end of the movable side current-carrying shaft 7 is connected to an operating mechanism of a circuit breaker incorporating the vacuum valve via an insulating rod (not shown).

On the inner surface of the movable side end plate 3, a lower end of a bellows 9 formed of a stainless steel plate in a substantially U shape is brazed in an airtight manner. The upper part of the bellows 9 is brazed to the outer circumference of the movable side current-carrying shaft 7 in an airtight manner.

On the outer circumferences of the tips of the fixed-side energizing shaft 5 and the movable-side energizing shaft 7, the inner circumference of the coil electrode 10, which is not shown in detail, is brazed. At the tips of these coil electrodes 10, a disk-shaped fixed side electrode 4A and a movable side electrode 4 made of a copper plate are provided.
B are symmetrically stacked and brazed via a connector (not shown).

These fixed side electrode 4A and movable side electrode 4
A disk-shaped contact 8 made of copper / chromium alloy or the like is superposed on the facing surface of the tip of B, and is brazed to the fixed side electrode 4A and the movable side electrode 4B.

These fixed side electrode 4A and movable side electrode 4B
The outer periphery of the contact 8 and the contact 8 are chamfered in an arc shape in order to prevent sticking of the arc and in consideration of withstand voltage characteristics between the shield 12 and the shield 12, which will be described later.

A support ring made of a stainless steel plate is provided on the inner periphery of an annular support portion 1a protruding from the center of the inner periphery of the insulating cylinder 1.
12a is fixed, and the center portion of the outer circumference of the shield 12 also made of stainless steel plate is brazed to the inner circumference of the support ring 12a.

In the vacuum valve thus constructed, the fixed side end plate 2 and the movable side end plate 3 are brazed in a vacuum vacuum heating furnace at the final stage of assembly, and a vacuum of 0.1 Pa or less is provided inside. Has been maintained.

When the movable side energizing shaft 7 is driven upward in FIG. 4 by the operation mechanism of the circuit breaker described above, the bellows 9 expands and the contact 8 on the front surface of the movable side electrode 4B moves to the fixed side. The contact 8 is brought into contact therewith and is pressurized so that it is energized.

When the movable side energizing shaft is driven downward in FIG. 4 when the load current or the fault current is cut off and the movable side contact 8 is opened, an arc generated between the movable side contact 8 and the fixed side contact 8 is generated. Due to the arc extinguishing performance between the contacts and the axial magnetic flux generated by the coil electrode described above, the arc is extinguished in a short time and the circuit is cut off.

The metal vapor or molten powder scattered from the surface of the contact 8 by the arc generated between the contacts at the time of this interruption adheres to the inner surface of the insulating cylinder 1, and the fixed side and the movable side of the inner surface of the insulating cylinder 1 are separated. The arc shield 12 described above is incorporated in order to prevent a phenomenon in which the insulation creepage characteristics are degraded during the period.

On the other hand, by improving the contact material and the shape of the electrode, the outer diameter of the electrode and the breaking performance have been greatly improved compared to the initial vacuum valve, the outer diameter has been reduced, and the breaking capacity has increased. However, there is a tendency for users to demand further miniaturization and capacity increase.

[0015]

However, in the vacuum valve thus constructed, the gap of the contact 8 in the open state is restricted by the breaking performance and the insulation gap, and the outer diameter of the electrode is It is difficult to reduce the size and size because there are restrictions from the capacity and the dispersed area of the arc (that is, arc extinguishing performance). .

Further, the gap between the electrode and the arc shield 12 cannot be reduced in order to prevent the possibility that the arc generated between the contacts will short-circuit from the end of the electrode through the arc shield 12, and therefore the arc shield. The outer diameter of 12 cannot be reduced.

Further, in order to prevent the inner diameter of the insulating cylinder 1 from being flashed over the upper and lower end plates through the upper and lower ends of the arc shield 12, and the length of the insulating cylinder 1 is also set.
In order to maintain the insulation creepage withstand voltage value of the inner surface of the above for a long period of time, it cannot be shortened.

The reason is that secondary electrons emitted from the arc shield 12 collide with the inner surface of the insulating cylinder 1 during long-term use of the vacuum valve, and the insulating characteristics of the inner surface of the insulating cylinder 1 and the vacuum valve. This is because there is a risk that the insulation characteristics of the vacuum inside the are deteriorated.

Therefore, in order to guarantee the insulating characteristics of the vacuum valve for a long period of time, the insulating cylinder 1 cannot be downsized. Then, the objective of this invention is to obtain the vacuum valve which can aim at further size reduction of an external shape.

[0020]

According to a first aspect of the present invention, an electrically conductive shaft is penetrated through an end plate which seals both ends of an insulating cylinder, and an electrode is provided at an opposite end of the electrically conductive shaft. In a vacuum valve in which an arc shield is provided between the insulating cylinder and the insulating cylinder, a coating of a metal material having a high dielectric breakdown voltage is formed on the outer circumference of the electrode.

The invention according to claim 2 is characterized in that the coating film is formed by ion plating, vacuum deposition or plasma spraying.

The invention according to claim 3 is characterized in that a coating is formed on the outer circumference of the coil electrode of the electrode and the electrode plate.

The invention according to claim 4 is characterized in that the metal material is tungsten, stainless steel, or chromium.

The invention according to claim 5 is characterized in that the thickness of the coating is in the range of 0.1 μm to 100 μm.

The invention according to claim 6 is characterized in that a modified layer is formed on the inner surface of the insulating cylinder by irradiation of an ion beam.

The invention according to claim 7 is characterized in that the ion beam is carbon or proton.

The invention described in claim 8 is characterized in that the ion beam is applied at a voltage of 0.5 MeV to 2 MeV.

Furthermore, the invention according to claim 9, characterized in that the range of the density of the ion beam ^{5J / cm 2 ~50J / cm 2} .

According to the present invention, by such means, the withstand voltage value against the impact voltage between the outer circumference of the electrode and the arc shield is increased, and the decrease of the creeping withstand voltage value of the inner surface of the insulating cylinder is prevented for a long period of time.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the vacuum valve of the present invention will be described below with reference to the drawings. FIG. 1A is a diagram showing a first embodiment of a vacuum valve of the present invention, a diagram corresponding to FIG. 4 shown in the prior art, and FIG. 1B is a diagram shown in FIG.
It is a partially expanded detailed view of the electrode shown to (a).

1 (a) and 1 (b) are different from FIG. 4 shown in the prior art in that a metal for improving the withstand voltage characteristic between the arc shield 12 and the outer circumference of the electrode is used. Forming the coating as described below, and insulating cylinder 1
By forming a modified layer on the inner surface of
Is the same as Therefore, the same elements as those in FIG.

That is, on the outer periphery of the upper and lower coil electrodes 10, a tungsten film 11 having an average film thickness of about 50 μm is formed.
A is formed by an ion plating device. Further, a thin modified layer 13 is formed on the inner surface of the insulating cylinder 1 by irradiating the ion beam of Garbon.
This modified layer 13 has an output of 1 MeV ion beam equipment, and the density of the ion beam for irradiation is 5 J / cm ² to 50 J / cm 2.
Control was performed within the range of ² .

The inventor has also used, as the metal coating, a coating of stainless steel (SUS304) instead of tungsten.
Performed on other vacuum valves. Further, instead of the carbon ion beam, the modified layer 13 was formed for another vacuum valve by irradiation with a proton ion beam.

In the vacuum valve in which the coatings 11A and 11B and the modified layer 13 are formed in this manner, the withstand voltage characteristic between each electrode and the arc shield 12 and the creeping insulation characteristic of the inner surface of the insulating cylinder 1 are shown. It can be greatly improved.

FIG. 2 shows the test results showing the comparison of the characteristics of the impact breakdown voltage against the copper material, the stainless steel (SUS304) steel material and the tungsten, and the electrode whose surface is not coated with the conventional copper material. Compared with, the electrode with the stainless steel film formed showed about 1.7 times the characteristics. The test conditions were a flat plate electrode with a diameter of 34 mm, and the electrode gap was
1.5 mm.

Similarly, the electrode coated with tungsten exhibited a shock withstand voltage characteristic that was about 1.9 times that of a copper-based electrode. On the other hand, the creepage withstand voltage characteristic of the modified layer 13 was about 1.4 times that of the conventional insulating cylinder.

The reason for this is considered to be that the impurity gas near the solid surface of the ceramic was melted and removed by the ion beam, and the crystal structure of the ceramic was made fine. Therefore, even if the electrons emitted from the shield 12 collide with the inner surface of the insulating cylinder 1, the impurity gas is not emitted, so that the tracking on the inner surface of the insulating cylinder 1 does not easily progress, and the insulation performance on the creeping surface is improved. To do.

Therefore, in a vacuum valve incorporating an electrode having such a coating formed thereon, not only can the gap between the electrode and the arc shield 12 be shortened, but also the length of the insulating cylinder 1 can be shortened. Therefore, the outer diameter and length of the vacuum valve can be reduced.

Therefore, it is possible to reduce the outer shape of the switch and the circuit breaker incorporating this vacuum valve, so that the installation area of the switchgear and the power receiving and distributing equipment whose main constituents are the switchgear and the circuit breaker can be reduced. In addition, it is possible to reduce the size of the switchgear, reduce design restrictions of these switchgear and power receiving and distributing equipment, and increase the degree of freedom.

In the above embodiment, the coatings 11A, 11
The thickness of B was explained in the case of about 50 μm, but it is thinner than
The thickness may be 0.1 μm, or conversely may be increased to about 100 μm.

It is preferable that the thickness is as thick as possible. However, as a result of the breaking test conducted by the inventor by actually incorporating it, as a result, when it exceeds 100 μm, not only the adhesion strength with the copper of the base material is lowered, but also the energization / stopping is stopped. Repeatedly, cracks may be generated in the coating.

Further, when the film thickness is 0.1 μm or less, it may be peeled from the film in the current switching test (condition process) in the final stage of the manufacturing process of the vacuum valve.

In the above embodiment, the film was formed by the ion plating device, but
It may be performed by vacuum deposition. Further, in the above-mentioned embodiment, the ion beam irradiation is explained in the case where the output is 1 MeV, but it may be performed with an output in the range of 0.5 MeV to 2 MeV.

Further, in the above embodiment, the coating may be formed by plasma spraying instead of the ion beam. Further, in the above embodiment, the coating may be formed on the inner surface and the outer surface of the arc shield 12, and the material may be chrome.

Next, FIG. 3 shows a second embodiment of the vacuum valve of the present invention.
FIG. 2 is a vertical cross-sectional view showing the embodiment of FIG. 1, corresponding to FIG. 3A and 3B is different from FIGS. 1A and 1B in that the upper and lower coil electrodes 10 have a U-shaped cross section with the outer circumference and the rear surface fitted inward and have a thickness of 0.2 mm (SUS30.
4) The shield 14 made of steel plate was joined by brazing. The shield 14 has a chamfered outer periphery on the opening side.

Even in the vacuum valve provided with such a shield 14, the withstand voltage characteristic between the coil electrode 10 and the arc shield 12 can be improved. In the above embodiment, the shield 14 has a plate thickness of 0.2 mm.
It may be increased to about 1 mm depending on the outer diameter of the electrode.

[0047]

As described above, according to the first aspect of the present invention,
In a vacuum valve in which an energizing shaft is penetrated through an end plate that seals both ends of an insulating cylinder, an electrode is provided at the opposite end of this energizing shaft, and an arc shield is provided between this electrode and the insulating cylinder, dielectric breakdown By forming a coating of a metal material with a high voltage on the outer circumference of the electrode, the withstand voltage value against the shock voltage between the outer circumference of the electrode and the arc shield was increased, so that the outer diameter of the vacuum valve can be further miniaturized. Can be obtained.

According to the second aspect of the present invention, by forming the coating by ion plating, vacuum deposition or plasma spraying, the withstand voltage value against the impact voltage between the outer circumference of the electrode and the arc shield is increased. So
It is possible to obtain a vacuum valve whose outer shape can be further miniaturized.

According to the third aspect of the present invention, by forming the coating on the coil electrode of the electrode and the outer circumference of the electrode plate, the withstand voltage value against the shock voltage between the outer circumference of the electrode and the arc shield is increased. Therefore, it is possible to obtain a vacuum valve whose outer shape can be further miniaturized.

According to the fourth aspect of the invention, since the metal material is tungsten, stainless steel, or chromium, the withstand voltage value against the impact voltage between the outer periphery of the electrode and the arc shield is increased. It is possible to obtain a vacuum valve whose outer shape can be further miniaturized.

According to the invention of claim 5, the thickness of the coating film is set in the range of 0.1 μm to 100 μm, so that the withstand voltage value against the impact voltage between the outer periphery of the electrode and the arc shield is increased. Thus, it is possible to obtain a vacuum valve whose outer shape can be further miniaturized.

According to the sixth aspect of the invention, the impact voltage between the outer circumference of the electrode and the arc shield is formed by forming the modified layer by the irradiation of the ion beam on the inner surface of the insulating cylinder. Withstand voltage is increased,
Since the reduction of the creeping withstand voltage value on the inner surface of the insulating cylinder is also prevented for a long period of time, it is possible to obtain a vacuum valve capable of further miniaturizing the outer shape.

According to the invention described in claim 7, by using carbon or protons as the ion beam, the withstand voltage value against the impact voltage between the outer circumference of the electrode and the arc shield is increased, and the inner surface of the insulating cylinder is increased. Since the decrease in creepage withstand voltage value of (1) was also prevented for a long period of time, it is possible to obtain a vacuum valve capable of further miniaturizing the outer shape.

Further, according to the invention described in claim 8, by irradiating the ion beam with a voltage of 0.5 MeV to 2 MeV, the withstand voltage value against the impact voltage between the outer circumference of the electrode and the arc shield is increased, and Since the reduction of the creeping withstand voltage value on the inner surface of the insulating cylinder is also prevented for a long period of time, it is possible to obtain a vacuum valve capable of further miniaturizing the outer shape.

Further, according to the invention of claim 9,
With the range density of 5J / cm ² ~50J / cm ² of the ion beam, with increasing breakdown voltage against impact voltage between the outer periphery and the arc shield electrode, the creepage withstand voltage value of the inner surface of the insulating cylinder Since the decrease is also prevented for a long period of time, it is possible to obtain a vacuum valve whose outer shape can be further miniaturized.

[Brief description of drawings]

FIG. 1A is a vertical sectional view showing a first embodiment of a vacuum valve of the present invention. (B) is a partial enlarged detailed view of (a).

FIG. 2 is a graph showing the operation of the first embodiment of the vacuum valve of the present invention.

FIG. 3 is a vertical sectional view showing a second embodiment of the vacuum valve of the present invention.

FIG. 4 is a vertical sectional view showing an example of a conventional vacuum valve.

[Explanation of symbols]

1 ... Insulating cylinder, 2 ... Fixed end plate, 3 ... Movable end plate, 4A
... fixed side electrode, 4B ... movable side electrode, 5 ... fixed side energizing shaft,
6 ... Bushing, 7 ... Movable side energizing shaft, 8 ... Contact point, 9 ... Bellows, 10 ... Coil electrode, 11A, 11B ... Coating, 12 ... Arc shield, 13 ... Modification layer, 14 ... Shield.

Claims (9)

[Claims] 1. An electrically conductive shaft is penetrated through an end plate that seals both ends of an insulating cylinder, an electrode is provided at an opposite end of the electrically conductive shaft, and an arc shield is provided between the electrode and the insulating cylinder. The vacuum valve is characterized in that a coating of a metal material having a high dielectric breakdown voltage is formed on the outer periphery of the electrode. 2. The vacuum valve according to claim 1, wherein the coating film is formed by ion plating, vacuum deposition, or plasma spraying. 3. The vacuum valve according to claim 1, wherein the coating film is formed on an outer circumference of a coil electrode of the electrode and an electrode plate. 4. The vacuum valve according to claim 1, wherein the metal material is tungsten, stainless steel, or chrome. 5. The vacuum valve according to claim 1, wherein the coating film has a thickness in a range of 0.1 μm to 100 μm. 6. The vacuum valve according to claim 1, wherein a modified layer is formed on the inner surface of the insulating cylinder by irradiation of an ion beam. 7. The vacuum valve according to any one of claims 1 to 6, wherein the ion beam is carbon or proton. 8. The method according to claim 1, wherein the ion beam is irradiated with a voltage of 0.5 MeV to 2 MeV.
The vacuum valve according to any one of 1. 9. The density of the ion beam is 5 J / cm ² to 50.
The vacuum valve according to any one of claims 1 to 8, wherein the vacuum valve has a range of J / cm ² .