JP6646873B2 - Surge protection element - Google Patents

Description

  The present invention relates to a surge protection element used to protect various devices from a surge generated by a lightning strike or the like and prevent an accident from occurring.

  Telecommunications equipment such as telephones, facsimile machines, modems, etc., connected to communication lines, power lines, antennas or CRTs, image display drive circuits such as liquid crystal televisions and plasma televisions, etc., abnormal voltages such as lightning surges and static electricity A surge protection element is connected to a part which is easily affected by electric shock due to (surge voltage) in order to prevent an electronic device or a printed circuit board on which the device is damaged due to thermal damage or fire due to abnormal voltage.

  Conventionally, as shown in Patent Document 1, for example, an arrester-type surge protection element including a pair of protruding electrode portions protruding from a pair of sealing electrodes in a facing state and having a discharge auxiliary portion formed on an inner surface of an insulating tube is known. Has been described. In this surge protection element, a large number of substantially rectangular parallelepiped holes are formed substantially in a matrix on opposing surfaces of a pair of protruding electrode portions. A coating containing a base glass is formed.

Japanese Utility Model Registration No. 3151069

The following problems remain in the above conventional technology.
That is, in the conventional structure, the location where the arc discharge reaches the protruding electrode portion is not constant, and may reach the outer peripheral portion of the protruding electrode portion. Further, the arc discharge may reach the same place repeatedly. Due to the arrival of the arc discharge at the outer peripheral portion of the protruding electrode portion or the concentration at the same location, there is a disadvantage that the outer peripheral portion of the protruding electrode portion is significantly damaged. In particular, when the surge applied current exceeds 10 kA, the damage becomes remarkable. Such damage to the outer peripheral portion of the protruding electrode portion is caused by melting and scattering of the metal constituting the protruding electrode portion, the metal component adheres to the inner surface of the insulating tube, and the insulation between the pair of sealing electrodes is reduced. There was a problem that made it worse. In addition, the discharge starting voltage may be reduced to exceed the set allowable range of the discharge starting voltage, and the function as the surge protection element may be lost.

  The present invention has been made in view of the above problems, and has as its object to provide a surge protection element that can reduce damage to the outer peripheral portion of a protruding electrode portion due to arc discharge.

  The present invention has the following features to attain the object mentioned above. That is, the surge protection element according to the first invention includes an insulating tube, and a pair of sealing electrodes for closing the opening at both ends of the insulating tube and sealing the discharge control gas therein. The sealing electrode has a pair of protruding electrode portions protruding inward and facing each other, and opposing surfaces of the pair of protruding electrode portions are formed in a concave curved surface, and oppose a central region of the opposing surface. A protrusion protruding toward the protruding electrode is formed.

  That is, in this surge protection element, the opposing surfaces of the pair of protruding electrode portions are formed in a concave curved shape, and the protrusion protruding toward the opposing protruding electrode portion is formed in the central region of the opposing surface. In addition, the location where the arc discharge arrives is concentrated on the protruding portion in the central region of the opposing surface of the concave curved surface, so that damage to the outer peripheral portion of the protruding electrode portion can be reduced and the firing voltage can be stabilized. That is, as compared to the case where the opposing surface of the protruding electrode portion is only a flat surface or a surface on which a groove is formed, the distance between the opposing surface of the concave curved surface and the opposing protruding portion is easily uniform over the entire surface, Electrons emitted from the entire opposing surface are more likely to concentrate on the protrusion. In addition, the stable power reception of the arc discharge at the protrusion reduces the fluctuation width of the discharge starting voltage.

A surge protection element according to a second aspect of the present invention is the surge protection element according to the first aspect, wherein a discharge active layer is formed on at least a part of the opposing surface except for the protrusion by using a material having higher electron emission characteristics than a material of the sealing electrode. It is characterized by being formed.
In other words, in this surge protection element, the discharge active layer is formed on at least a part of the opposing surface except for the protrusions with a material having higher electron emission characteristics than the material of the sealing electrode. By covering at least a part of the facing surface with the active layer, the arc discharge is more likely to be concentrated on the protruding portion, and the discharge active layer provides stability of operating voltage against repeated discharges and excellent withstand voltage characteristics. Can be

A surge protection element according to a third aspect of the present invention is the surge protection element according to the second aspect, wherein the discharge active layer is formed on an outer peripheral portion of the facing surface.
That is, in this surge protection element, since the discharge active layer is formed on the outer peripheral edge of the opposing surface, the outer peripheral edge of the opposing surface is covered with the discharge active layer to which discharge is difficult to reach. Arc discharge hardly reaches the portion, and damage on the outer peripheral surface of the protruding electrode portion and its vicinity is further suppressed.

A surge protection element according to a fourth invention is characterized in that, in any one of the first to third inventions, the protrusion projects beyond an outer peripheral edge of the facing surface.
That is, in this surge protection element, since the protrusion protrudes from the outer peripheral edge of the opposing surface, the arc discharge from the opposing surface of the opposing protruding electrode portion is located at a position entirely lower than the tip of the protrusion. Since it is more difficult to reach the opposite surface, it is easier to concentrate on the protrusion.

According to the present invention, the following effects can be obtained.
That is, according to the surge protection element of the present invention, the opposing surfaces of the pair of protruding electrode portions are formed in a concave curved surface, and the protrusion protruding toward the opposing protruding electrode portion is formed in the central region of the opposing surface. Since it is formed, the location where the arc discharge reaches is concentrated on the protrusion of the concave portion in the facing surface, so that damage to the outer peripheral portion of the protruding electrode portion can be reduced and the discharge starting voltage can be stabilized.
Therefore, the fluctuation range of the firing voltage can be reduced by stable power reception of the arc discharge, and the life of the element can be extended by reducing the electrode damage, and the number of operable surges can be increased. Become. Further, since the withstand capacity is improved, the size can be reduced. In particular, the surge protection element according to the present invention is suitable for power supply and communication equipment for infrastructure (railway-related, renewable energy-related (solar cell, wind power generation, etc.)) requiring high current surge resistance.

It is an axial sectional view showing one embodiment of a surge protection element concerning the present invention. FIG. 2 is a sectional view taken along line AA of FIG. 1.

  Hereinafter, an embodiment of a surge protection device according to the present invention will be described with reference to FIGS. In each drawing used in the following description, the scale is appropriately changed in order to make each member recognizable or easily recognizable.

As shown in FIGS. 1 and 2, the surge protection element 1 of the present embodiment includes an insulating tube 2 and a pair of sealing members for closing the openings at both ends of the insulating tube 2 to seal the discharge control gas therein. And a stop electrode 3.
Further, the surge protection element 1 of the present embodiment includes a discharge auxiliary part 4 formed of an ion source material on the inner peripheral surface of the insulating tube 2.

The pair of sealing electrodes 3 have a pair of projecting electrode portions 5 projecting inward and facing each other.
The opposing surfaces 5b of the pair of protruding electrode portions 5 are formed in a concave curved shape, and a protruding portion 5c protruding toward the opposing protruding electrode portion 5 is formed in a central region of the opposing surface 5b. The protruding portion 5c protrudes toward the protruding electrode portion 5 which is opposed to the outer peripheral edge of the opposed surface 5b.

  The discharge active layer 8 is formed on at least a part of the opposing surface 5b except for the protrusion 5c with a material having higher electron emission characteristics than the material of the sealing electrode 3. In particular, in the present embodiment, the discharge active layer 8 is formed on the outer peripheral edge of the facing surface 5b. That is, the discharge active layer 8 is formed in an annular shape on the outer peripheral edge of the facing surface 5b.

  The discharge active layer 8 includes, for example, Si and O as main components and at least one of Na, Cs, and C. The discharge active layer 8 is prepared, for example, by adding a cesium carbonate powder to a sodium silicate solution to form a precursor, and applying the precursor to the outer peripheral edge of the facing surface 5b. It is produced by performing a heat treatment at a temperature equal to or higher than the softening temperature and equal to or higher than the temperature at which cesium carbonate melts and decomposes.

The discharge auxiliary portion 4 is a conductive material, and is a discharge auxiliary portion formed of, for example, a carbon material.
Note that, in the present embodiment, the discharge auxiliary portion 4 is formed linearly along the axis C on the inner peripheral surface of the insulating tube 2.
Further, FIG. 1 shows only one discharge assisting portion 4 along the axis C, but a plurality of discharge assisting portions 4 may be formed at intervals in the circumferential direction.

The sealing electrode 3 is made of, for example, 42 alloy (Fe: 58 wt%, Ni: 42 wt%), Cu, or the like.
The sealing electrode 3 has a disc-shaped flange portion 7 which is fixed to the open state at both ends of the insulating tube 2 by heat treatment using a conductive fusion material (not shown). Inside the flange portion 7, a columnar protruding electrode portion 5 protruding inward and having an outer diameter smaller than the inner diameter of the insulating tube 2 is provided integrally.

The insulating tube 2 is made of a crystalline ceramic material such as alumina. Note that the insulating tube 2 may be formed of a glass tube of lead glass or the like.
The conductive fusion material is formed of, for example, an Ag-Cu brazing material as a brazing material containing Ag.
The discharge control gas sealed in the insulating tube 2 is an inert gas or the like, for example, He, Ar, Ne, Xe, Kr, SF ₆ , CO ₂ , C ₃ F ₈ , C ₂ F ₆ , CF ₄ , H ₂ , atmosphere, etc., and a mixed gas thereof are employed.

The facing surface 5b has a concave curved surface shape that is formed in an arc-shaped cross section around the axis C.
The protrusion 5 c has a rectangular cross section in the axial direction, is formed in a column shape longer than the depth of the facing surface 5 b, and is provided on the axis C of the protruding electrode 5.

  In this surge protection element 1, when an overvoltage or an overcurrent enters, an initial discharge is first performed between the discharge assisting part 4 and the protruding electrode part 5, and the initial discharge further triggers the discharge to progress further, Electrons are emitted from the entire opposing surface 5b of the protruding electrode portion 5 on the minus electrode side, and as shown by the two-dot chain line arrow in FIG. Arc discharge is performed on the projection 5c of the electrode unit 5.

  As described above, in the surge protection element 1 of the present embodiment, the opposing surfaces 5b of the pair of protruding electrode portions 5 are formed in a concave curved shape, and protrude toward the opposing protruding electrode portion 5 in the central region of the opposing surface 5b. Since the projecting portion 5c is formed, the location where the arc discharge reaches is concentrated on the projecting portion 5c in the central region of the concave curved opposing surface 5b, and damage to the outer peripheral portion of the projecting electrode portion 5 can be reduced. The discharge starting voltage can be stabilized.

That is, as compared with the case where the opposing surface of the protruding electrode portion 5 is a flat surface or a surface where only a groove is formed, the distance between the opposing protruding portion 5c of the concave curved opposing surface 5b is more uniform over the entire surface. The electrons emitted from the entire opposing surface 5b are easily concentrated on the protrusions 5c. Also, the stable receiving of the arc discharge at the protrusion 5c reduces the fluctuation width of the discharge starting voltage.
Further, since the protrusion 5c protrudes from the outer peripheral edge of the opposing surface 5b, the arc discharge from the opposing surface 5b of the opposing protruding electrode 5 causes the opposing electrode 5 to be entirely lower than the tip of the protrusion. Since it is more difficult to reach the surface 5b, it is easier to concentrate on the protrusion 5c.

  In addition, since the discharge active layer 8 is formed on at least a part of the opposing surface 5b except for the protrusion 5c with a material having higher electron emission characteristics than the material of the sealing electrode, the discharge active layer 8 that is hard to reach the discharge is formed. By covering at least a part of the opposing surface 5b, the arc discharge is more likely to be concentrated on the protruding portion 5c, and the discharge active layer 8 improves the stability of the operating voltage against repeated discharges and excellent withstand voltage characteristics. can get.

  In particular, since the discharge active layer 8 is formed on the outer peripheral edge of the opposing surface 5b, the outer peripheral edge of the opposing surface 5b is covered with the discharge active layer 8 that is difficult for discharge to reach. Arc discharge becomes difficult to reach, and damage on the outer peripheral surface of the protruding electrode portion 5 and its vicinity is further suppressed.

  The technical scope of the present invention is not limited to the above embodiment, and various changes can be made without departing from the spirit of the present invention.

For example, in the first embodiment, one protrusion is provided upright in the center region of the facing surface, but a plurality of protrusions may be provided in the center region. Even in this case, since the arc discharge is concentrated on the plurality of protrusions in the central region of the facing surface, damage to the outer peripheral surface of the protruding electrode portion can be reduced.
Further, the protrusion may be formed in a cylindrical shape such as a cylindrical shape. In that case, a discharge active layer may be formed inside the protrusion.

  DESCRIPTION OF SYMBOLS 1 ... Surge protection element, 2 ... Insulating tube, 3 ... Sealing electrode, 4 ... Discharge auxiliary part, 5 ... Projecting electrode part, 5b ... Opposing surface of projecting electrode part, 5c ... Projection part, 8 ... Discharge active layer

Claims (4)

An insulating tube;
A pair of sealing electrodes for closing the opening at both ends of the insulating tube and sealing a discharge control gas therein.
The pair of sealing electrodes has a pair of projecting electrode portions projecting inward and facing each other,
Opposing surfaces of the pair of protruding electrode portions are formed in a concave curved surface shape,
A surge protection element, wherein a projection protruding toward the opposed protruding electrode portion is formed in a central region of the opposed surface. The surge protection device according to claim 1,
A surge protection element, wherein a discharge active layer is formed on at least a part of the opposing surface except for the protrusion, with a material having higher electron emission characteristics than a material of the sealing electrode. The surge protection device according to claim 2,
The surge protection element, wherein the discharge active layer is formed on an outer peripheral edge of the facing surface. The surge protection device according to any one of claims 1 to 3,
The surge protection element according to claim 1, wherein the protruding portion protrudes from an outer peripheral edge of the facing surface.

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