JP3219483B2 - 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 incorporated in a vacuum circuit breaker or the like, and more particularly, to a vacuum valve having a vertical magnetic field electrode for applying a magnetic field parallel to an arc generated when current is interrupted.

[0002]

2. Description of the Related Art As is well known, among conventional vacuum valves, there is a vacuum valve provided with a vertical magnetic field electrode for interrupting an arc by applying a magnetic field parallel to an arc generated between the electrodes. FIG. 5 is a vertical sectional view showing an example of a conventional vacuum valve provided with the vertical magnetic field electrode.

In FIG. 5, a fixed-side energizing shaft 26 is brazed through the center of an end plate 22A brazed to the upper end of a cylindrical insulating cylinder 21. A guide bearing 30 is inserted into the center of 22B. This guide bearing 30
In the upper part of the movable-side energizing shaft 27, a cylinder formed of stainless steel and having an inverted U-shaped cross section is formed. The bellows 10 is coaxially inserted and brazed to the movable-side conducting shaft 27 and the end plate 22B.

The lower end of the fixed-side energizing shaft 26 is brazed to the upper surface of the fixed-side electrode 24, which will be described in detail with reference to FIG. Is brazed on its lower surface. Around the fixed side electrode 24 and the movable side electrode 25, a cylindrical shield 29 is fixed to the insulating cylinder 21. The lower end (not shown) of the movable-side conducting shaft 27 is connected to a link mechanism of an operation mechanism (not shown) via an insulating rod (not shown).

In the vacuum valve configured as described above, the fixed side electrode 24 and the movable side electrode 25
Is in a contact state by being pressed by an operation mechanism (not shown). When the movable energizing shaft 27 is driven by the operation mechanism (not shown) in the direction shown by the arrow P from this state, the movable electrode
25 is separated from the fixed side electrode 24, and an arc is generated between the fixed side electrode 24 and the movable side electrode 25. This arc is
The arc is sustained by the metal vapor generated from the fixed side electrode 24 and the movable side electrode 25 which is the starting point of the arc. When the current becomes zero and the generation of the metal vapor stops, the arc cannot be maintained and the interruption is completed.

When the breaking current is large, the arc is extremely unstable due to the interaction between the magnetic field generated by the arc and the magnetic field generated by an external circuit. For this reason, the arc moves on the electrode surface, and the electrode is locally heated by being biased toward the edge or the peripheral portion of the electrode, thereby melting the local portion of the electrode and generating a large amount of metal vapor, thereby deteriorating the breaking performance. To prevent this phenomenon, the fixed side electrode 24 and the movable side electrode 25
A vertical magnetic field electrode as shown in FIG. 6 is employed.

In FIG. 6, the tip of the fixed-side energized shaft 26 and the tip of the movable-side energized shaft 27 are respectively connected to the fixed-side energized shaft.
Energized shafts 31A, 31 smaller in diameter than 26 and movable-side energized shaft 27
B. The fixed-side electrode 24 has an annular portion 32A fitted to the conducting shaft 31A, and a 90-degree radially outward portion from the annular portion 32A.
The arm 33A radially extends at an interval of 33 °, and a circumferential portion 34A bent in an arc shape in the circumferential direction from the outer end of the arm 33A. The distal end of the free end 35A of the circumferential portion 34A It is composed of the joined disk-shaped electrode 6A.

Similarly to the fixed-side electrode 24, the movable-side electrode 25 has an annular portion 32B fitted to the energizing shaft 31B, and arms extending radially outward from the annular portion 32B at 90 ° intervals. 33B
And a disc-shaped electrode 6B having a circumferential portion 34B bent in an arc shape in the circumferential direction from the outer end of the arm 33B, and joined to the end of the free end 35B of the circumferential portion 34B. It is configured.
Among these, the disk-shaped electrodes 6A and 6B are provided with slits 6a and 6b radially from the vicinity of the center to the outer peripheral end at 90 ° intervals.

In the vacuum valve constructed as described above, the breaking current in the event of an accident and the normal energizing current are transmitted from the fixed energizing shaft 26 through the central energizing shaft 31A to the annular portion 32A and the arm portion.
33A, and flows from the circumferential portion 34A to the disk-shaped electrode 6A. The arc current flowing from the disk-shaped electrode 6A to the movable-side disk-shaped electrode 6B is applied to the free end portion 35B, the circumferential portion 34B, and the arm portion 33.
B, flows from the annular portion 32B to the movable-side energized shaft 27 via the energized shaft 31B.

Therefore, at this time, a current flowing through the arms 33A, 33B and the circumferential portions 34A, 34B generates a magnetic field parallel to the arc 40, and the arc 40 is dispersed over the entire electrode surface, and the arc voltage is reduced. When reduced, the arc current is interrupted. On the other hand, the eddy currents flowing through the disc-shaped electrodes 6A, 6B are suppressed by the slits 6a, 6b formed in the disc-shaped electrodes 6A, 6B, the distribution of the magnetic field is made substantially uniform, and the cutoff performance is improved.

[0011]

However, in the vacuum valve configured as described above, as shown in FIG. 7A, the magnetic flux density in the space between the disk-shaped electrodes 6A and 6B is not uniform. The magnetic flux density at the center is high, and the magnetic flux density sharply decreases when the distance from the center of the electrode exceeds about 50% of the electrode diameter.

On the other hand, as shown in a graph showing the relationship between the arc voltage and the magnetic flux density shown in FIG. 7B, the magnetic flux density of the vertical magnetic field electrode has an optimum value at which the arc voltage becomes the lowest.
Therefore, if the magnetic flux density at the center of the electrode is
If it becomes higher than the optimum value shown in (b), on the contrary, the arc voltage becomes high and the electrode surface generates heat, partial melting is promoted, and the breaking performance is lowered.

Therefore, when a large current is cut off, the diameter of the electrode is increased in order to suppress the magnetic flux density at the central portion to an optimum value shown in the graph of FIG. Then, since the outer diameter of the vacuum valve increases, the outer shape of the vacuum circuit breaker in which the vacuum valve is incorporated and the switchgear in which the vacuum circuit breaker is housed also increase. Therefore, an object of the present invention is to provide a vacuum valve capable of improving the shutoff performance without increasing the outer shape.

[0014]

SUMMARY OF THE INVENTION The present invention relates to a vacuum valve having a vertical magnetic field electrode at the end of an energized shaft, wherein the end of the energized shaft has a tubular shape, and the inside of the end of the energized shaft has conductivity and mechanical strength. Penetrates a support rod larger than the current-carrying shaft, and a leveling coil that generates a magnetic flux in the opposite direction to the magnetic flux generated by this vertical-magnetic-field electrode is interposed between the tip of the current-carrying shaft and the vertical magnetic-field electrode. And

[0015]

The arc generated between the electrodes is prevented from sticking to a specific portion of the electrode by the magnetic flux which is parallel to the arc and is uniformly generated. The evaporation of metal is suppressed.

[0016]

1 is a partial longitudinal sectional view of a vacuum valve according to the present invention, and FIG. 2 is a perspective view of a movable electrode incorporated in the vacuum valve of the present invention. Since the fixed-side electrode is completely the same, only the movable-side electrode shown in FIGS. 1 and 2 will be described.

In FIGS. 1 and 2, a cylindrical portion 2 having an outer diameter of about one half of the outer diameter of the movable electrode 5 is formed in the penetrating portion of the end plate 22B of the movable current-carrying shaft 7. The lower part of the support rod 8 made of stainless steel is press-fitted from the middle to the cylindrical part 2 and fixed.

A cylindrical spiral conductor 3 is inserted into the upper part of the support rod 8 and is brazed to the upper end of the movable current-carrying shaft 7. Spiral grooves 3a are formed in advance in the spiral conductor 3 at intervals of 60 °.

Above the spiral conductor 3, a cylindrical conductive tube 1 is press-fitted into a small diameter portion 8a formed at the upper end of the support rod 8, and brazed to the upper surface of the spiral conductor 3. A plurality of grooves (not shown) are formed in the outer circumference of the conductive tube 1 in the axial direction.

The inner end of the arm 33B of the electrode having the same shape as the arm 33B of the conventional movable electrode 5 shown in FIG. 6 is brazed to the upper end of the conductive tube 1, and the outer peripheral end of the arm 33B. The disk-shaped electrode 6B is brazed on the upper surface of the free end portion 35B at the tip of the circumferential portion 34B located in the same manner as in the prior art.

In the vacuum valve thus configured, most of the current flowing between the movable-side electrode 5 and the fixed-side electrode (not shown) flows through the spiral conductor 3 and, as shown by the arrow FA in FIG. An axial magnetic field is generated in a direction opposite to that of the electrode portion. Moreover, since the diameter of the current-carrying part of the spiral conductor 3 is about one half of the diameter of the electrode part, the magnetic field at the center of the magnetic field generated by the movable electrode 5 is different from the magnetic field generated by the spiral conductor 3. Decrease by vector sum.

FIG. 3 is a graph showing the relative values of the magnetic flux densities of the magnetic field generated at the electrode portion and the magnetic field generated at the spiral conductor 3 in the radial direction from the center of the electrode, and the resultant magnetic field obtained by summing these values. is there.

As shown in FIG. 3, the distribution curve of the relative value of the magnetic flux density generated at the electrode portion is, as shown also in FIG. Droop drastically. On the other hand, the distribution curve of the relative value of the magnetic flux density generated in the spiral conductor 3 is opposite to the direction of the magnetic flux generated in the electrode portion up to a half of the radius of the electrode portion, and becomes the same direction after passing through it. .

Therefore, as shown in the graph of FIG. 3, the combined magnetic field (F + FA) decreases at the center as compared with the curve F indicating the magnetic field generated only by the movable side electrode 5, but it is reduced by half in the radial direction. On the contrary, it becomes higher. As a result,
The spiral conductor 3 is an auxiliary coil for leveling a magnetic field generated by the movable electrode 5 serving as a main coil. Moreover, since a plurality of grooves are formed in the outer periphery of the conductive tube 1 in the axial direction, the eddy current due to the magnetic field FA generated in the spiral conductor 3 is suppressed, and the disturbance of the magnetic field FA due to the eddy current is prevented. Can also.

Therefore, in the vacuum valve according to the present invention, the magnetic flux density generated on the electrode surface is substantially uniform, thereby preventing an increase in arc voltage due to partial density change as in a conventional vacuum valve, and improving the breaking performance. Therefore, it is possible to obtain a vacuum valve that is small in size, has excellent cutoff performance, and can extend the contact life. Next, FIG. 4 is a perspective view showing another embodiment of the vacuum valve of the present invention, and is a view corresponding to FIG.

FIG. 4 differs from FIG. 1 and FIG. 2 in that the outer periphery of the support rod 8 is replaced by the spiral conductor 3 and the movable-side energizing shaft 7 shown in FIG. 1 and FIG. 2 and the outer diameter is about half that of the movable electrode 5 shown in FIG.
In addition, the auxiliary electrode 15 in which the magnetic flux generated by the flowing current is opposite to the direction of the magnetic flux generated in the movable electrode 5 is the cylindrical portion 12 formed upside down.

That is, the auxiliary electrode 15 is provided with a plurality of fixed ends 15B corresponding to the free ends 35B of FIG. 1, and the upper end of the fixed end 15B is formed at one end of the arc-shaped circumferential portion 14B. A short free end 13B corresponding to the arm 33B shown in FIGS. 1 and 2 is formed at the other end of the circumferential portion 14B.
The conductive tube 1 shown in FIGS. 1 and 2 is inserted into the upper end of the support rod 8 inside the auxiliary electrode 15, and the lower end of the support rod 8 is a cylindrical portion at the base end of the auxiliary electrode 15. Twelve upper surfaces are brazed.

Also in this case, similarly to the spiral conductor 3 shown in FIG. 1 and FIG.
As shown by the combined magnetic field F + FA curve shown in FIG. Leveling can be prevented, increase in arc voltage can be prevented, breaking performance can be increased, and contact life can be extended.

In the above-described embodiment, the case where the cylindrical portion 2 and the spiral conductor 8 are individually manufactured in FIG. 1 has been described. However, a spiral groove 3a is formed at the upper end of the cylindrical portion 2, The conductive tube 1 may be integrated.

[0030]

As described above, according to the present invention, in a vacuum valve provided with a vertical magnetic field electrode at the end of an energized shaft, the end of the energized shaft has a tubular shape, and the conductivity and mechanical strength are provided inside the end of the energized shaft. Penetrates a support rod that is larger than the current-carrying axis, and a leveling coil that generates a magnetic flux in the opposite direction to the magnetic flux generated by this vertical-field electrode is interposed between the tip of the current-carrying shaft and the vertical magnetic-field electrode. Since the arc generated between the arc and the standardized magnetic flux was prevented from sticking to a specific part of the electrode, the melting of the electrode material at the specific part and the evaporation of the molten metal were suppressed. It is possible to obtain a vacuum valve capable of improving the shut-off performance without increasing the outer shape.

[Brief description of the drawings]

FIG. 1 is a partial longitudinal sectional view showing one embodiment of a vacuum valve of the present invention.

FIG. 2 is a partial perspective view showing a main part of the vacuum valve of the present invention.

FIG. 3 is a graph showing the operation of one embodiment of the vacuum valve of the present invention.

FIG. 4 is a partial perspective view showing another embodiment of the vacuum valve of the present invention.

FIG. 5 is a longitudinal sectional view showing an example of a conventional vacuum valve.

FIG. 6 is a partial perspective view showing a main part of a conventional vacuum valve.

FIG. 7A is a graph showing the operation of a conventional vacuum valve. (B) is a graph showing the operation of this kind of vacuum valve.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Conductive tube, 2 ... cylindrical part, 3 ... spiral conductor, 5 ... movable-side electrode, 6B ... disk-shaped electrode, 7 ... movable-side conducting shaft, 8 ...
Support rod, 15 ... Auxiliary electrode.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-201837 (JP, A) JP-A-58-169834 (JP, A) JP-A-57-189420 (JP, A) JP-A-56-169420 84829 (JP, A) JP-A-56-28422 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01H 33/66

Claims (2)

(57) [Claims] 1. A vacuum valve provided with a vertical magnetic field electrode at the end of an energized shaft, wherein the end of the energized shaft has a tubular shape, and the conductivity and the mechanical strength are larger than the energized shaft inside the end of the energized shaft. Wherein a leveling coil for generating a magnetic flux in a direction opposite to a magnetic flux generated by the vertical magnetic field electrode is interposed between a tip of the current-carrying shaft and the vertical magnetic field electrode. valve. 2. The vacuum valve according to claim 1, wherein the leveling coil is a spiral conductor.