JPH09134650A - Vacuum valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance breaking performance by preventing the concentration of an arc on an electrode central part by a longitudinal magnetic field. SOLUTION: An annular coil support ring 5 is brazed to the tips of a movable side current carrying shaft 6 and a fixed side current-carrying shaft through a coil electrode 14 and a reinforcing member 18. In a central part of this coil support ring 5, a central coil 7 is housed in the axial direction inside the support ring 5. Outer peripheral part coils 3 manufactured by a copper material are arranged at intervals of 60 deg. around this central coil 7. An electrode plate 2 is superposed on the further tips of these outer peripheral part coils 3. A contact 1 is superposed on the outside surface side of this electrode plate 2, and these contact 1 and electrode plate 2 and outer peripheral part coils 3 and coil support ring 5 are brazed to each other. A carried current of the central coil 7 is restrained to about 1/4 of an electric current flowing to the outer peripheral part coils 3, and a synthetic magnetic filed by the coil electrode 14 is gradually increased to an outer peripheral part from the axis, and is almost doubled in the outer peripheral part.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Conventionally, in order to improve the breaking performance of a vacuum valve, a method of applying a magnetic field in parallel with a vacuum arc generated between electrodes to extinguish the arc has been adopted. As such a vacuum valve, there is a vertical magnetic field type vacuum valve, and several types of electrode structures have been implemented and proposed, but here, the structure of the vertical magnetic field electrode shown in FIG. 7 is used. The explanation will be based on Although FIG. 7 shows the case of the movable side electrode as an example, the fixed side electrode has the same structure.

In FIG. 7, a circular counterbore 6a is formed at the tip of a movable side current-carrying shaft 6B made of a copper rod.
A shaft portion 18a protruding from the lower portion of a reinforcing member 18 made of stainless steel in a plan view (not shown) having a substantially T-shaped vertical section is fitted and brazed to the spot facing portion 6a. .

On the outer periphery of the shaft portion 18a, an annular shaft portion 14a which is made of a copper material and which projects from the center of the coil electrode 14 described below is inserted, and the shaft portion 18a and the movable side energizing shaft 6B are connected to each other. It is brazed.

The coil electrode 14 has four arm portions (not shown) radially projecting from the outer periphery of the shaft portion 14a at 90 ° intervals in a plan view, and in a direction orthogonal to the axial direction.
The base ends of the arc-shaped coil portions 14c in the plan view (not shown) are brazed to the tips of these arms. Through holes 14d are axially formed at the tips of these coil portions 14c as shown in FIG.

In these through holes 14d, a shaft portion of a connector 13 made of a copper material, which is substantially T-shaped in FIG. 7 and which is circular in a plan view (not shown), is inserted and brazed to the tip of the coil portion 14c. Has been done.

On the upper end surface of the reinforcing member 18, there is placed an electrode plate 2B which is formed of a copper plate in a disk shape and has grooves radially formed from the central portion toward the outer circumference. The electrode plate 2B is brazed to the surfaces of the reinforcing member 18 and the connector 13.

On the upper surface of the electrode plate 2B, there is provided a contact 1A which is formed in a disk shape from a copper / chromium alloy, and like the electrode plate 2B, has grooves radially formed from the central portion toward the outer circumference and the outer circumference is chamfered in an arc shape. It is joined by brazing.

In the electrode of the vacuum valve thus constructed, for example, most of the current flowing from the movable side current-carrying shaft 6B to the contact 1A passes from the shaft portion 14a of the coil electrode 14 to the plural arm portions 14b, Coil portion 14c at the tip of this arm portion 14b
Flows to Note that a part of the current flows into the electrode plate 2B via the reinforcing member 18.

Of these, the current flowing into the coil portion 14c flows into the electrode plate 2B from the connector 13 at the tip of each coil portion 14c through the back surface of the outer periphery of the electrode plate 2B, and the electrode plate 2B.
Flows from the surface of the contact to the contact 1A.

The current flowing out to the contact 1A flows from the contact 1A into the contact of the fixed side electrode which is in contact with the surface of the contact 1A, and thereafter passes through the electrode plate of the fixed side electrode, the connector and the coil electrode. , Flows out to the fixed side energizing shaft.

FIG. 8 is a graph showing the distribution of the magnetic flux density Bz of the longitudinal magnetic field, that is, the magnetic field in the axial direction generated by the current flowing through each coil electrode in the movable side electrode and the fixed side electrode thus configured. Is. The movable side electrode is separated from the fixed side electrode, an arc is generated between both electrodes, and the magnetic flux generated by this arc current has the same tendency.

As shown in FIG. 8, the magnetic flux density Bz of the longitudinal magnetic field
Is maximum at the axial center of the electrode, becomes lower toward the outer periphery of the electrode, and is a substantially sinusoidal curve.

The arc generated between the electrodes which generate such a longitudinal magnetic field is larger than that of an electrode which does not generate a longitudinal magnetic field.
Do not locally concentrate on the surface of both electrodes, spread uniformly over the whole area, prevent melting of the contact surface due to local concentration, prevent the rise of metal vapor pressure caused by this melting, and suppress the increase of arc It is possible to improve the blocking performance.

[0015]

However, even in the vacuum valve having such a structure, when the breaking current further increases, the arc concentrates on the central portion of the contact having a high magnetic flux density, and the breaking performance is further improved. It will be an obstacle in trying.

The reason why the arc is concentrated in the central portion of the contact is considered to be due to the effect of the pinch force by the self-current acting on the arc and the characteristic that the arc current is concentrated in the region of the strong magnetic field. Experiments have confirmed that the latter effect of concentrating on a strong magnetic field is greater than the former effect of pinch force.

Therefore, a method may be considered in which the magnetic flux density shown in FIG. 8 is further increased to prevent the local concentration of the arc to improve the breaking performance. The arc is concentrated in the central part due to the effect. Further, a method of reducing the strength of the longitudinal magnetic field generated in the electrode center by the eddy current flowing in the electrode plate 2B shown in FIG. 7 has been attempted, but this method also significantly concentrates the arc on the electrode center. Can't prevent it.

FIG. 9 shows a paper (IEEE
Tranns. On Power Delivery, Vol.PWRD-1, No.4, Oct.198
6 is a graph showing an example of the distribution of magnetic flux density between electrodes with respect to the radial position of the electrode, which is cited from 6). As shown in FIG. 9, the distribution of the magnetic flux density varies depending on the gap length between the electrodes, but in each case, the maximum value of the magnetic flux density exists in the outer peripheral direction of the electrodes.

However, the position where the magnetic flux density is maximum is a position of about 55% of the electrode radius (28.5 mm), which is different from the vacuum valve of the present invention which will be described later in which the maximum value is further formed in the outer peripheral direction.

The following method can be considered as a method of reducing the magnetic flux density near the center of the electrode. (1) A method of generating a magnetic field in the opposite direction by an eddy current flowing through the electrode plate or the contact without forming a slit in the electrode plate and the contact. (2) A method in which a second coil electrode for generating a reverse magnetic field is provided at the center of the electrode. (3) A method of making the distance between the movable side and fixed side magnetic field generating coils as close as possible. Among these, as an example of the method of (1), Japanese Patent Laid-Open No.
There is an electrode disclosed in Japanese Patent Laid-Open No. 57-212719. The magnetic flux density distribution of this electrode is shown in FIG. 10 (a), and the structure is shown in FIG. 10 (b).

A magnetic field control plate made of pure copper is provided on the surface 22 of the electrode 12.
24 is buried, and a magnetic field in the opposite direction is generated by the eddy current generated in the magnetic field control plate 24, and has a distribution characteristic shown by a curve F2. The dotted line in FIG. 10A is a magnetic flux density distribution curve when the magnetic field control plate 24 is not provided.

In FIG. 10 (b), a connecting portion 15 is shown at the right end of the coil electrode 11 joined to the tip of the movable side current-carrying shaft 6C, and a spacer 18 is joined at the center thereof. . The contact plate 23 is joined to the front surface of the magnetic field control plate 24.

Even in such an electrode, the magnetic field control plate 24
There is a maximum value of the magnetic flux density on the outer circumference of the electrode due to the reverse magnetic flux generated at
It is about 40%, which is also different from the vacuum valve of the present invention described later.

Japanese Patent Publication No. Hei 4-3611 discloses an example which discloses a similar magnetic flux density distribution, though not an electrode for the magnetic flux density distribution. Figure 11 shows an example of the distribution of the magnetic flux density. In this electrode, due to the eddy current generated by the contact 1B, the maximum value of the magnetic flux density exists in the outer peripheral portion of the electrode as shown by the curve G2. However, a curved line G1 shown by a one-dot chain line is a magnetic flux density distribution only by the magnetic field generating coil 31. The radial position having the maximum value is included in the maximum value range of the electrode of the present invention.

However, in the detailed description of the vacuum valve of the present invention described later, the strength of the magnetic flux density is insufficient as described in the magnetic flux density distribution in which the effect of the longitudinal magnetic field is not sufficiently exerted. Further, in the graph of FIG. 11, the magnetic flux density at the electrode outermost diameter position is almost zero, and in such a magnetic flux density distribution, it is possible to effectively use the outermost electrode region for dispersing the arc. I can't.

As an example of the method (2), there is JP-A-57-20206. Fig. 12 shows the magnetic flux density distribution between the electrodes by this method. The position where the magnetic flux density is maximum is considered to be within the scope of the present invention described later, but due to the magnetic field generating coil arranged in the center of the electrode 32,
The magnetic flux density at the center of the electrode is opposite.

Several other electrode structures for generating a reverse magnetic field at the center of the electrode have been proposed, but all of them have the magnetic field oriented in the opposite direction at the center of the electrode. .

Japanese Patent Publication No. 2-30132 discloses an example of the method (3). Fig. 13 shows the magnetic flux density distribution between the electrodes by this method. In this case, the magnetic field at the center of the electrode is not negative compared to the method (2). Also, the radial position where the magnetic flux density reaches its maximum is considered to be within the scope of the present invention, but the maximum value of the magnetic flux density exceeds 1.6 times the magnetic flux density at the 40% position of the electrode radius. ing.

As described above, in the conventional vacuum valve, the magnetic flux density at the center of the electrode is high or, on the contrary, too low,
The arc concentrates on the center of the anode electrode. Further, since the number of concentrated areas is one, the energy density flowing into the surface of the anode side electrode becomes high, and therefore, the temperature of the surface of the anode side electrode becomes high and the blocking performance deteriorates.

Therefore, first of all, in order to increase the critical current value at which the arc is concentrated, it is conceivable to make the current density uniform on the electrode surface. Further, even if the current exceeds the critical current value and the current is concentrated, it is possible to disperse and concentrate the current at some points on the outer peripheral portion of the electrode. With such a method, it becomes a problem to increase the critical current value at which the arc begins to concentrate for the same breaking current value and reduce the current density in the concentrated region as compared with the conventional vacuum valve. Therefore, an object of the present invention is to obtain a vacuum valve capable of preventing the concentration of the arc in the central portion of the electrode and improving the breaking performance.

[0031]

A vacuum valve according to a first aspect of the present invention is a vacuum valve in which a pair of electrodes are provided in a vacuum container so as to be contactable and separable via a pair of conductive shafts electrically connected to the outside. The valve is characterized in that the magnetic flux density in the axial direction of the pair of electrodes increases from the electrode center side to the outside and has a maximum value outside the position of 70% of the electrode radius.

Further, in the vacuum valve of the invention described in claim 2, the maximum value of the magnetic flux density in the axial direction is set to a magnetic flux density of 1.2 to 1.2 which gives a minimum arc voltage for a breaking current of a predetermined electrode diameter.
It is characterized by being 1.6 times.

Further, the vacuum valve of the invention described in claim 3 is characterized in that the magnetic flux density at the outer peripheral end of the electrode is 2 mT / kA or more.

Further, in the vacuum valve of the invention described in claim 4, the arc voltage obtained from the relationship between the magnetic flux density (Bct) at the center of the electrode and the arc voltage corresponding to the breaking current of the electrode diameter and the axial magnetic flux density is The minimum magnetic flux density (Bcr) is 0.
It is characterized in that it is 75 to 0.90 times.

Further, the vacuum valve of the invention described in claim 5 is characterized in that the maximum values of the magnetic flux density in the axial direction are distributed at least at two positions on the outer circumference of the electrode.

According to the sixth aspect of the vacuum valve of the present invention, when the minimum value of the axial magnetic flux density in the circumferential direction at the electrode radial position where the axial magnetic flux density has the maximum value (Bmax) is Bmin, The region where the axial magnetic flux density in the circumferential direction is (Bmax + Bmin) / 2 or more is 50% or more with respect to the entire circumference.

Further, in the vacuum valve of the invention described in claim 7, in the vacuum valve in which a pair of electrodes are provided in the vacuum container so as to be contactable and separable via a pair of conductive shafts electrically connected to the outside, The axial magnetic flux density at the center of the magnetic field is set to the lowest magnetic flux density of the magnetic flux densities in the range of 2 to 5 V higher than the lowest arc voltage for the breaking current of the predetermined electrode diameter.

Further, the vacuum valve of the invention according to claim 8 is characterized in that the radial position where the magnetic flux density at which the arc voltage becomes the minimum is applied is within the range of 20 to 40% from the center of the electrode radius. And

According to the ninth aspect of the vacuum valve of the present invention, in the vacuum valve, a pair of electrodes are provided in the vacuum container so that they can be contacted and separated via a pair of conductive shafts electrically connected to the outside. It is characterized in that a plurality of energizing coils are formed on the outer peripheral portion of.

Further, the vacuum valve of the invention according to claim 10 is a vacuum valve in which a pair of electrodes are provided in a vacuum container so as to be contactable and separable via a pair of conductive shafts electrically connected to the outside. The contact surfaces having the inclination characteristics that the cathode drop voltage of the contact material decreases from the central portion toward the outer periphery are provided on the opposing surfaces of the contact points.

By such means, the magnetic flux in the axial direction generated by the coil electrode and the magnetic flux in the axial direction generated by the energizing coil are superposed to gradually increase the magnetic flux density from the central portion to the outer peripheral portion of the contact. At the same time, the distribution of the magnetic flux density in the outer peripheral portion is pulsated.

Generally, the voltage drop Vcolm in the arc column
Has the following relationship with the axial magnetic flux density Bz and the current density Jz.

[0043]

(Equation 1)

Therefore, when the magnetic flux density is high at the center of the electrode, the value of Vcolm becomes small even if currents of the same current density flow. The value of Vcolm between the electrodes is constant over the entire electrode surface, so Vcolm in the electrode outer peripheral region
The current density Jz becomes high at the center of the electrode where the magnetic flux density is high.

In order to make the current density on the electrode surface uniform,
It is necessary to suppress the current density in the central part of the electrode and increase the current density in the outer peripheral part of the electrode. Therefore, in order to suppress the current density in the central part of the electrode, the axial magnetic flux density in the central part is reduced, the voltage drop in the arc column in the central part of the electrode is increased, and it becomes difficult for the current to flow.

Therefore, the magnetic flux density is increased in the outer peripheral portion of the electrode so that the voltage drop in the arc column is reduced so that the current easily flows. In the vacuum arc, most of the current is carried by the electron current, and in the region where the magnetic flux density is high, the Larmor radius of the electron is small, and it is strongly trapped by the magnetic field lines.

Therefore, a current flows stably in the electrode outer peripheral region where the magnetic field is strong. As a result, the current density between the electrodes can be made uniform as compared with the conventional vacuum valve.

[0048]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a graph showing the characteristics of one embodiment of the present invention, and is a diagram showing the distribution of the magnetic flux density in the axial direction between the electrodes with respect to the radial position of the electrodes when the electrodes are separated to the intermediate position. .

In the vacuum valve of the present invention, by adopting the electrode structure described later with reference to FIG. 5, with respect to the low axial magnetic flux density Bct in the central portion of the electrode, the axial direction is increased as the axial magnetic flux is moved. The magnetic flux density is increased, and a high magnetic flux density Bm described later is provided slightly inside the outer circumference of the electrode.

FIG. 2 is a graph showing the distribution of the magnetic flux density in the axial direction in the circumferential direction of the electrode outer periphery of the vacuum valve of the present invention. The magnetic flux density shown in FIG. Bcr exists, and its value changes depending on the breaking current, the electrode diameter, and the contact material.

In FIG. 1, a magnetic flux density in the range of 0.75 to 0.9 times the axial magnetic flux density Bcr shown in FIG. 3 where the arc voltage between the electrodes is the lowest for each breaking current is applied to the center of the electrode. It The axial magnetic flux density gradually increases from the center of the electrode toward the outer peripheral portion of the electrode. here,
The radial position where the axial magnetic flux density Bcr giving the lowest arc voltage is applied is in the range of 20 to 40% of the electrode radius.

The magnetic flux density in the axial direction gradually increases from this area to the outside, and reaches the maximum value Bm at a position of about 80% of the area of 70% or more of the electrode radius. It is desirable that the maximum value Bm be 1.4 to 2.4 times the magnetic flux density at the center of the electrode.

Further, as shown in FIG. 2, the axial magnetic flux density in the circumferential direction is distributed so that three or more peaks appear within at least 360 °. Bmax and Bm
The value of in is in the range of 1.4 to 2.4 times the magnetic flux density at the center of the electrode. The range of (Bmax + Bmin) / 2 or more is preferably 50% or more of the whole.

Next, the operation of the vacuum valve having such an axial magnetic flux density distribution will be described. Since a magnetic flux density lower than the magnetic flux density that gives the lowest arc voltage is applied to the electrode central portion, the voltage drop in the arc column ignited to the central portion is higher than that in the electrode outer peripheral region.

Therefore, the voltage drop in the arc column is made to be low, and it is attempted to become equal to the arc voltage drop in the region of the electrode outer peripheral portion. Therefore, from the relationship of equation (1), the current density flowing in the central part of the electrode can be kept low, and the arc characteristic that the current density in the central part of the electrode becomes higher than the outer peripheral part as in the conventional case is suppressed. . Since the magnetic flux density in the axial direction increases from the center of the electrode toward the outer peripheral portion, the arc easily ignites on the outer peripheral portion of the electrode.

For example, when CuCr is used as the contact material, the arc voltage does not rise so much even if the magnetic flux density in the axial direction becomes higher than Bcr, so that the arc spreads to the outermost circumference of the electrode.

However, if the breaking current further increases, the arc voltage may increase in a high magnetic flux density region as shown in the graph of FIG. 3 showing the relationship between the arc voltage and the magnetic flux density.

Therefore, an arc can be more easily ignited on the outer peripheral portion of the electrode by combining the inclined characteristic contactor having the characteristic that the cathode drop voltage decreases from the central portion of the electrode toward the outer peripheral portion of the electrode.

Therefore, the increase in the current density at the center of the electrode is suppressed and the current density at the outer periphery of the electrode is increased, so that the current density distribution can be made uniform. By the way, as the breaking current increases, the force of the arc column shrinking toward the center of the electrode on the anode side, that is, the interaction between the magnetic flux in the circumferential direction of the arc column and the arc current generated by the self current. The pinch force to work works.

However, since the magnetic flux density on the outer peripheral portion of the electrode is higher than the magnetic flux density of the conventional vacuum valve, the electrons are strongly trapped by the lines of magnetic force. Therefore, it is possible to effectively suppress the force of contracting to the central portion.

Further, since the magnetic flux density in the circumferential direction is distributed in a wave shape as shown in FIG. 2, when the cutoff current increases, the current in the low magnetic flux density area concentrates in the high magnetic flux density area. If the circumferential distribution of the magnetic flux density at the electrode outer peripheral portion is constant as in the conventional vacuum valve, when the arc begins to concentrate on a certain part of the electrode surface, the arc concentrates only on that part. Therefore, as shown in FIG. 2, it is important to make the axial magnetic flux density strong and weak.

Further, as the current increases, the arc begins to concentrate at several points on the outer periphery of the electrode where the magnetic flux density is high. But,
Since the point of concentration is not a single point as in the conventional case but is separated into several points, the current density in the concentrated region is low and the critical current value at which the concentration is high rises.

Further, even if the concentration is intense, since the concentrated position becomes the outer peripheral portion of the electrode, the concentrated area increases, so that melting due to an arc applied to the surface of the anode electrode can be suppressed.

The inventors of the present invention have used the conventional electrode shown in FIG.
For the model electrode shown in FIG. 4, a comparative test of breaking performance was performed. Of these, the electrodes shown in FIG. 4 were obtained by loosely fitting an exciting coil 9 for generating a longitudinal magnetic field around the current-carrying axis of a conventional plate electrode in which coil electrodes and the like were not incorporated. An example of a detailed view of the model electrode will be described later in the vertical cross-sectional view of FIG.

The test was conducted by loosely fitting the exciting coil 9 around the current-carrying shaft 6 of the model electrode shown in FIGS. 4 and 5.
This is because the magnetic field in the axial direction cannot be minutely controlled only by the model electrode. The inventors conducted an experiment by adjusting the exciting current applied to the exciting coil 9 and superimposing the magnetic flux generated in the exciting coil 9 on the magnetic flux generated from the model electrode itself shown in FIG.

The results of this interruption test are shown in the graph of FIG.
In FIG. 6, assuming that the limit D1 of the breaking current in the breaking test performed with the conventional longitudinal magnetic field type electrode A is 1, the limit D2 of the breaking current is 1.15 of the conventional longitudinal magnetic field type electrode in the model electrode shown in FIG. It was double.

The exciting coil 9 shown in FIGS. 4 and 5 is also used.
Therefore, in the interruption test conducted under the conditions of FIG. 1 and FIG.
The average value D3 of the breaking current limit was 1.4 times. In addition,
In the above embodiment, the arc voltage generated by the arc between the contacts is changed only by the magnetic flux density in the axial direction between the contacts, and the arc is moved and dispersed in the outer peripheral direction of the contacts. Change the material in the center and the outer periphery,
The invention according to claim 10 may be combined with contacts having different minimum arc voltages in the central portion and the outer peripheral portion.

In FIG. 5, what is largely different from the electrode shown in FIG. 7 is that the electric path connecting the contact point and the movable side energization shaft is formed of a copper wire formed in a coil shape. It is the same as the electrode shown by 7.

In FIG. 5, at the upper end of the reinforcing member 18 to which the shaft portion 18a is brazed at the upper end of the movable side current-carrying shaft 6, there is provided a coil support ring 5 annularly made of copper material. It is placed through a positioning hole 5a formed at the center of the and is brazed to the upper end of the reinforcing member 18.

An annular groove having a narrow width is formed on the upper surface of the coil support ring 5 with respect to the outside of the positioning hole 5a.
On the outer side of this groove, circular counterbore portions 5b are formed at a total of 6 positions at 60 ° intervals in a cross-sectional view not shown. Of these, the central coil 7 formed in a coil shape from an oxygen-free copper wire is placed on the upper end surface of the reinforcing member 18, and brazed to the upper end of the reinforcing member 18.

The outer peripheral coil 3 which is the same as the central coil 7 is also mounted on each of the counterbore portions 5b for positioning formed on the upper surface of the coil support ring 5, and each of the counterbore portions 5b is brazed. Has been done. Furthermore, the positioning hole 5 of the coil support ring 5
The lower end of a support pipe 8 made of a thin stainless steel pipe is inserted and brazed into a narrow annular groove formed on the outer side of a.

A disk-shaped electrode plate 2 is mounted on the upper end surfaces of the support tube 8 and the outer peripheral coil 3. A through hole 2a is formed in the center of the electrode plate 2, and a narrow annular groove for positioning into which the upper end of the support tube 8 is fitted is coaxially formed on the lower surface outside the through hole 2a. Has been done.
The support tube 8 whose upper end is inserted into this groove is also brazed to the electrode plate 2.

On the inner surface of the electrode plate 2, shallow counterbore portions 2b having the same outer diameter as the counterbore portion 5b formed on the upper surface of the coil support ring 5 are provided at six positions symmetrical to the counterbore portion 5b. In a plan view not shown, they are formed at 60 ° intervals. The upper end of the outer peripheral coil 3 whose lower end is brazed to the counterbore 5b of the coil support ring 5 is brazed to the counterbore 2b formed on the electrode plate 2.

On the other hand, in the through hole 2a formed in the center of the electrode plate 2, the upper end of a substantially convex and disk-shaped stainless steel seat 4 in a plan view (not shown) is inserted to attach to the electrode plate 2. It is brazed. The upper end of the center coil 7 contacts the lower surface of the seat 4 and is brazed to the seat 4.

The outer shape of the contact 1 is the contact 1A shown in FIG.
However, a shallow truncated conical recess 1a is formed in the center of the upper end surface. The outer periphery of the upper end of the recess 1a is chamfered in an arc shape.

Next, the operation of the vacuum valve thus constructed will be described. In FIG. 5, most of the arc current generated between the contact of the fixed side electrode (not shown) and the contact 1 of the movable side electrode shown in FIG. 1 is inserted from the contact 1 between the electrode plate 2 and the support ring 5. And flows through each outer peripheral coil 3.

The current flowing through the central coil 7 should be set to about a quarter of the value of the current flowing through each outer peripheral coil 3 due to the resistance value of the seat 4 interposed between the central coil 7 and the electrode plate 2. You can

These center coil 7 and each outer peripheral coil 3
The distribution of the magnetic flux density of the longitudinal magnetic field generated by the current flowing in the coil and the composite magnetic field of the coil electrode 14 connected to the movable side energizing shaft side of the central coil 3 and the outer peripheral coil 3 are as shown in FIG.
The distribution is shown by.

In the above embodiment, the central coil 7
The cylindrical magnetic tube 9 may be loosely fitted in the inside of the coil and the inside of the outer peripheral coil 8. In this case, since the number of turns of the central coil 7 and the outer peripheral coil 8 can be reduced, the wire diameter of the central coil 7 and the outer peripheral coil 8 can be increased, and the current-carrying capacity and mechanical strength of the electrodes can be increased. There is an advantage that can be.

[0080]

As described above, according to the first aspect of the present invention,
In a vacuum valve in which a pair of electrodes are provided in a vacuum container so that they can be connected to and separated from each other via a pair of conductive shafts that are electrically connected to the outside, the axial magnetic flux density of the pair of electrodes is directed from the electrode center side to the outside. By setting the maximum value outside the position of 70% of the increased electrode radius, the axial magnetic flux generated by the coil electrode and the axial magnetic flux generated by the energizing coil are superposed, and from the center of the contact point. Since the magnetic flux density is gradually increased in the outer peripheral portion, it is possible to obtain the vacuum valve capable of preventing the concentration of the arc in the central portion of the electrode and improving the breaking performance.

According to the second aspect of the present invention, the maximum value of the magnetic flux density in the axial direction is set to 1.2 to 1.6 times the magnetic flux density that gives the minimum arc voltage for the breaking current of the predetermined electrode diameter. Axial magnetic flux generated by the coil electrode,
The magnetic flux in the axial direction generated by the energizing coil is superimposed to suppress the magnetic flux density in the axial direction at the center of the contact to raise the arc voltage and gradually increase the magnetic flux density from the center to the outer periphery of the contact. It is possible to obtain a vacuum valve that can prevent the concentration of the arc in the central portion and improve the breaking performance.

According to the third aspect of the invention, the magnetic flux density at the outer peripheral end of the electrode is set to 2 mT / KA or more, whereby the axial magnetic flux generated by the coil electrode and the energizing coil are generated. By superimposing the generated magnetic flux in the axial direction to suppress the magnetic flux density at the center of the contact and gradually increasing the magnetic flux density from the center of the contact to the outer periphery, it is possible to prevent the arc from concentrating at the center of the electrode and shut it off. It is possible to obtain a vacuum valve whose performance can be improved.

According to the invention described in claim 4, the arc voltage and the axial magnetic flux density corresponding to the breaking current of the electrode diameter are set to 0.75 to 0.90 times the magnetic flux density at which the arc voltage becomes the minimum. , The axial magnetic flux generated by the coil electrode,
The axial magnetic flux generated by the energizing coil is superimposed to suppress the magnetic flux density in the center of the contact and gradually increase the magnetic flux density from the center to the outer periphery of the contact, so that the arc is concentrated in the center of the electrode. It is possible to obtain a vacuum valve that can prevent and improve the shutoff performance.

According to the invention described in claim 5, the maximum values of the magnetic flux density in the axial direction are distributed at least at three positions on the outer circumference of the electrode, so that the magnetic flux in the axial direction generated by the coil electrode and the energization are conducted. The axial magnetic flux generated by the coil is superimposed to gradually increase the magnetic flux density from the center of the contact to the outer periphery, and the distribution of the magnetic flux density in the outer periphery is pulsated, so the arc is concentrated at the center of the electrode. It is possible to obtain a vacuum valve capable of preventing the above and improving the shutoff performance.

According to the sixth aspect of the invention, the minimum value of the axial magnetic flux density in the circumferential direction at the electrode radial position where the axial magnetic flux density has the maximum value (Bmax) is B.
When min, the axial magnetic flux density in the circumferential direction is (Bm
Ax + Bmin) / 2 or more is set to 50% or more of the total circumference so that the axial magnetic flux generated by the coil electrode and the axial magnetic flux generated by the energizing coil are superimposed. , The magnetic flux density was gradually increased from the central part of the contact to the outer peripheral part, and the distribution of the magnetic flux density in the outer peripheral part was pulsated, so it was possible to prevent the concentration of the arc in the central part of the electrode and improve the breaking performance. Obtainable.

Further, according to the invention described in claim 7, in a vacuum valve in which a pair of electrodes are provided in a vacuum container so as to be contactable and separable via a pair of conductive shafts electrically connected to the outside,
The axial magnetic flux density at the center of the electrode is set to be the lowest magnetic flux density in the range of 2 to 5 V higher than the lowest arc voltage for the breaking current of a predetermined electrode diameter, so that it is generated at the coil electrode. The axial magnetic flux and the axial magnetic flux generated by the energizing coil are superposed to gradually increase the magnetic flux density from the center of the contact point to the outer peripheral portion, and pulsate the magnetic flux density distribution in the outer peripheral portion at three or more locations. Therefore, it is possible to obtain a vacuum valve that can prevent the arc from concentrating on the central portion of the electrode and improve the breaking performance.

According to the eighth aspect of the invention, the radial position to which the magnetic flux density that minimizes the arc voltage is applied is within the range of 20 to 40% from the center of the electrode radius. The magnetic flux in the axial direction generated by the electrodes and the magnetic flux in the axial direction generated by the energizing coil are superposed to gradually increase the magnetic flux density from the central part of the contact to the outer peripheral part, and the arc voltage of the outer peripheral part also from the contact material. Since it is lowered, it is possible to obtain a vacuum valve capable of preventing the arc from concentrating on the central portion of the electrode and improving the breaking performance.

Further, according to the invention described in claim 9, in the vacuum valve in which the pair of electrodes are provided in the vacuum container so as to be contactable and separable via the pair of conductive shafts electrically connected to the outside,
By forming multiple energizing coils on the outer periphery of the electrode, the axial magnetic flux generated by the coil electrode and the axial magnetic flux generated by the energizing coil are superposed to move from the center of the contact to the outer periphery. While gradually increasing the magnetic flux density and pulsating the distribution of the magnetic flux density in the outer peripheral part and lowering the arc voltage in the outer peripheral part from the contact material as well, it is possible to prevent the concentration of the arc in the central part of the electrode and improve the breaking performance. A vacuum valve that can be obtained can be obtained.

Further, according to the invention of claim 10,
In a vacuum valve in which a pair of electrodes are provided in a vacuum container so that they can be connected to and separated from each other via a pair of conductive shafts that are electrically connected to the outside, a contact material from the center toward the outer periphery with respect to the facing surfaces of the electrodes. By providing a contact having a gradient characteristic that the cathode drop voltage of the contact is reduced, the axial magnetic flux generated by the coil electrode and the axial magnetic flux generated by the energizing coil are superposed so that the outer circumference is from the center of the contact. While gradually increasing the magnetic flux density in the part, pulsating the distribution of the magnetic flux density in the outer peripheral part and lowering the arc voltage in the outer peripheral part from the contact material, the concentration of the arc in the central part of the electrode is prevented and the interruption performance is improved. It is possible to obtain a vacuum valve that can be used.

[Brief description of the drawings]

FIG. 1 is a graph showing an embodiment of a vacuum valve of the present invention.

FIG. 2 is a graph showing an embodiment of the vacuum valve of the present invention different from FIG.

FIG. 3 is a graph showing the relationship between the magnetic flux density in the axial direction and the arc voltage between electrodes for explaining the operation of the vacuum valve of the present invention.

FIG. 4 is a partially enlarged view showing an embodiment of the vacuum valve of the present invention.

FIG. 5 is a partially enlarged sectional view showing details of an embodiment of a vacuum valve of the present invention.

FIG. 6 is a graph showing the operation of the vacuum valve of the present invention.

FIG. 7 is a partially enlarged vertical sectional view showing an example of a conventional vacuum valve.

FIG. 8 is a graph showing an example of the distribution of the magnetic flux density of the vertical magnetic field of the conventional vacuum valve.

FIG. 9 is a graph showing an example of the distribution of the magnetic flux density of the vertical magnetic field of the conventional vacuum valve, which is different from FIG. 8.

FIG. 10A is a graph showing an example of the distribution of the magnetic flux density of the vertical magnetic field electrode of the conventional vacuum valve, which is different from FIGS. 8 and 9. FIG. 6B is a diagram showing an example of a vertical magnetic field electrode incorporated in a conventional vacuum valve.

FIG. 11 is a vertical cross-sectional view of a vertical magnetic field electrode incorporated in a conventional vacuum valve and a diagram showing an example of its magnetic flux distribution.

FIG. 12 is a graph showing an example of a magnetic flux density distribution curve of a vertical magnetic field electrode of a conventional vacuum valve, which is different from FIGS. 8, 9, 10 (a) and 11.

FIG. 13 is a graph showing an example of a magnetic flux density distribution curve different from those of FIGS. 8, 9, 10 (a), 11 and 12 of a vertical magnetic field electrode of a conventional vacuum valve.

[Explanation of symbols]

1 ... contact point, 2 ... electrode plate, 3 ... outer peripheral coil, 4 ... seat, 5
... Coil support ring, 6 ... Movable side energizing shaft, 7 ... Central coil,
8 ... Support tube, 9 ... Excitation coil.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Junichi Sato 1 Toshiba Town, Fuchu City, Tokyo Inside the Toshiba Fuchu Factory (72) Inventor Eiji Kaneko 1-1-1, Shibaura, Minato-ku, Tokyo Toshiba Headquarters Co., Ltd. In the office (72) Inventor Mitaka Honma 1 in Toshiba Fuchu factory, Fuchu, Tokyo (72) Inventor Hiromichi Somei 1 in Toshiba Fuchu, Tokyo, Fuchu factory (72) Inventor The 1st place in Toshiba Fuchu factory, Fuchu city, Tokyo (72) Inventor Takashi Kusano 1st Toshiba town, Fuchu city, Tokyo Inside Fuchu factory, Toshiba

Claims (10)

[Claims] 1. A vacuum valve in which a pair of electrodes are provided in a vacuum container so as to be capable of contacting and separating via a pair of conductive shafts electrically connected to the outside, wherein the magnetic flux density in the axial direction of the pair of electrodes is at the electrode center. A vacuum valve characterized by increasing from the side to the outside and having a maximum value outside the position of 70% of the electrode radius. 2. The vacuum valve according to claim 1, wherein the maximum value of the magnetic flux density in the axial direction is 1.2 to 1.6 times the magnetic flux density that gives the minimum arc voltage to the breaking current of a predetermined electrode diameter. . 3. The magnetic flux density at the outer peripheral edge of the electrode is 2 mT
/ KA or more, and the maximum value is 1.4 to 2.4 times the magnetic flux density of the electrode center on at least one line on the radiation from the electrode center in the direction outside the electrode. The vacuum valve according to item 2. 4. The magnetic flux density (Bcr) at which the arc voltage is the minimum obtained from the relationship between the magnetic flux density (Bct) at the electrode center and the arc voltage corresponding to the breaking current of the electrode diameter and the axial magnetic flux density. The vacuum valve according to any one of claims 1 to 3, wherein the vacuum valve is 0.75 to 0.90 times as large. 5. The vacuum valve according to claim 1, wherein the maximum values of the magnetic flux density in the axial direction are distributed at least at two positions on the outer circumference of the electrode. 6. The maximum value of the magnetic flux density in the axial direction (Bma)
x), where Bmin is the minimum value of the axial magnetic flux density in the circumferential direction at the radial position of the electrode, the region where the axial magnetic flux density in the circumferential direction is (Bmax + Bmin) / 2 or more is the entire circumference. The vacuum valve according to any one of claims 1 to 4, wherein the vacuum valve is 50% or more. 7. A vacuum valve in which a pair of electrodes are provided in a vacuum container so as to be able to come into contact with and separate from each other via a pair of conductive shafts electrically connected to the outside, and a magnetic flux density in the axial direction at a central portion of the electrodes is set to a predetermined value. The vacuum valve is characterized in that it has the lowest magnetic flux density of the magnetic flux densities in the range of 2 to 5 V higher than the lowest arc voltage with respect to the breaking current of the electrode diameter. 8. The radial position to which the magnetic flux density that minimizes the arc voltage is applied is 20 from the center of the electrode radius.
The vacuum valve according to any one of claims 4 to 6, wherein the vacuum valve has a range of -40%. 9. A vacuum valve in which a pair of electrodes are provided in a vacuum container so as to be able to come into contact with and separate from each other via a pair of conductive shafts electrically connected to the outside, and a plurality of energizing coils are formed on an outer peripheral portion of the electrodes. A vacuum valve characterized by that. 10. A vacuum valve in which a pair of electrodes are provided in a vacuum container so as to be able to come into contact with and separate from each other via a pair of conductive shafts electrically connected to the outside. 2. A contact having a slope characteristic that the cathode drop voltage of the contact material decreases toward the contact.
The vacuum valve according to claim 9.