JP2017195141A - Surge protection element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surge protection element capable of reducing damage on an outer peripheral portion of a protruding electrode portion due to arc discharge.SOLUTION: The surge protection element includes: an insulating tube 2; and a pair of sealing electrodes 3 for sealing a discharge control gas inside thereof by closing opening ends of the insulating tube at both ends. The pair of sealing electrodes has a pair of projecting electrode portions 5 projecting inward and facing each other. A pair of opposing surfaces 5b of the projecting electrode portions is formed concave. A protruding portion 5c protruding from the bottom surface in the central recessed portion toward the opposing protruding electrode portion than the opposing surface around the central recessed portion is formed.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a surge protection element used for protecting various devices from a surge caused by a lightning strike and preventing accidents.

  Abnormal voltage such as lightning surge and static electricity, etc., such as parts where electronic devices for communication equipment such as telephones, facsimiles and modems are connected to communication lines, power lines, antennas or image display drive circuits such as CRTs, liquid crystal televisions and plasma televisions A surge protection element is connected to a portion that is easily subjected to electric shock due to (surge voltage) in order to prevent damage due to thermal damage or ignition of an electronic device or a printed circuit board on which the device is mounted due to abnormal voltage.

  Conventionally, as shown in Patent Document 1, for example, an arrester-type surge protection element having a pair of protruding electrode portions protruding in a facing state from a pair of sealing electrodes and having a discharge auxiliary portion formed on the inner surface of an insulating tube is provided. Have been described. In this surge protection element, a large number of substantially rectangular parallelepiped holes are arranged and formed on the opposing surfaces of a pair of protruding electrode portions, and vanadium pentoxide-zinc oxide-barium oxide-tellurium dioxide is formed on the inner surface of each hole portion. A film containing the system glass is formed.

Utility Model Registration No. 3151069

The following problems remain in the conventional technology.
That is, in the conventional structure, the arrival location of the arc discharge in 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. There is a disadvantage that the outer peripheral portion of the protruding electrode portion is greatly damaged due to the arrival of arc discharge to the outer peripheral portion of the protruding electrode portion or the concentration at the same place. In particular, when the surge applied current exceeds 10 kA, the damage becomes significant. Such damage to the outer peripheral portion of the protruding electrode part is that the metal constituting the protruding electrode part melts and scatters, 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 start voltage is reduced, the allowable range of the discharge start voltage is exceeded, and the function as a surge protection element may be lost.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide a surge protection element capable of reducing damage to the outer peripheral portion of the protruding electrode portion due to arc discharge.

  The present invention employs the following configuration in order to solve the above problems. That is, the surge protection element according to the first aspect of the present invention includes an insulating tube and a pair of sealing electrodes that closes both end openings of the insulating tube and seals the discharge control gas inside. The sealing electrode has a pair of projecting electrode portions that project inward and face each other, and the opposed surfaces of the pair of projecting electrode portions are formed in a concave curved surface and face a central region of the opposed surface. A protruding portion protruding toward the protruding electrode portion 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 surface shape, and the protruding portion that protrudes toward the protruding electrode portion facing is formed in the central region of the opposing surface. The arrival point of the arc discharge is concentrated on the protruding portion in the central area 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 discharge start voltage can be stabilized. That is, compared with the case where the opposing surface of the protruding electrode portion is a flat surface or a surface where only grooves are formed, the opposing surface of the concave curved surface is easy to make the distance between the opposing protrusions uniform over the entire surface, Electrons emitted from the entire facing surface are easily concentrated on the protrusion. In addition, due to the stable power reception of the arc discharge at the protrusion, the fluctuation range of the discharge start voltage is also reduced.

A surge protection element according to a second invention is the surge protection element according to the first invention, wherein the discharge active layer is made of a material having electron emission characteristics higher than that of the material of the sealing electrode on at least a part of the facing surface excluding the protrusion. It is formed.
In other words, in this surge protection element, a discharge active layer is formed of a material having higher electron emission characteristics than the material of the sealing electrode on at least a part of the opposing surface excluding the protrusion, so that the discharge is difficult to reach. By covering at least a part of the opposing surface with the active layer, it becomes easier for arc discharge to concentrate on the protrusions, and the discharge active layer provides stability of the operating voltage against repeated discharge and excellent withstand voltage characteristics. It is done.

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

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

The present invention has the following effects.
That is, according to the surge protection element according to the present invention, the opposing surfaces of the pair of protruding electrode portions are formed in a concave curved surface, and the protruding portion protruding toward the opposing protruding electrode portion is formed in the central region of the opposing surface. Since it is formed, the arrival point of the arc discharge is concentrated on the protruding portion of the concave portion in the opposing surface, so that damage to the outer peripheral portion of the protruding electrode portion can be reduced and the discharge start voltage can be stabilized.
Therefore, it is possible to reduce the fluctuation range of the discharge start voltage by stably receiving arc discharge, and to contribute to extending the life of the element by reducing electrode damage, and to increase the number of operable surges. Become. Furthermore, since the tolerance is improved, the size can be reduced. In particular, the surge protection element according to the present invention is suitable for power supplies and communication facilities for infrastructure (railway-related, renewable energy-related (solar cell, wind power generation, etc.)) that require high current surge resistance.

It is sectional drawing of the axial direction which shows one Embodiment of the surge protection element which concerns on this invention. It is AA arrow sectional drawing of FIG.

  Hereinafter, an embodiment of a surge protection element according to the present invention will be described with reference to FIGS. 1 and 2. In each drawing used for 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 this embodiment includes a pair of seals that close the insulating tube 2 and both ends of the insulating tube 2 and seal the discharge control gas inside. A stop electrode 3 is provided.
In addition, the surge protection element 1 of the present embodiment includes a discharge auxiliary portion 4 formed of an ion source material on the inner peripheral surface of the insulating tube 2.

The pair of sealing electrodes 3 has a pair of protruding electrode portions 5 that protrude inward and face each other.
The opposing surfaces 5b of the pair of protruding electrode portions 5 are formed in a concave curved surface, and a protruding portion 5c protruding toward the opposing protruding electrode portion 5 is formed in the central region of the opposing surface 5b. The protruding portion 5c protrudes toward the protruding electrode portion 5 facing the outer peripheral edge portion of the facing surface 5b.

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

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

The discharge auxiliary part 4 is a conductive material and is a discharge auxiliary part made of, for example, a carbon material.
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, in FIG. 1, only one discharge assisting portion 4 along the axis C is shown, 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 disk-like flange portion 7 that is fixed in close contact by a heat treatment with a conductive adhesive (not shown) at both ends of the insulating tube 2. A cylindrical protruding electrode portion 5 that protrudes inward and has an outer diameter smaller than the inner diameter of the insulating tube 2 is integrally provided inside the flange portion 7.

The insulating tube 2 is a crystalline ceramic material such as alumina. The insulating tube 2 may be formed of a glass tube such as lead glass.
The conductive fusing 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 , the atmosphere, etc. and a mixed gas thereof are employed.

The facing surface 5b has a concave curved surface formed in a circular arc shape with the axis C as the center.
The protrusion 5c is formed in a columnar shape having a rectangular cross section in the axial direction and longer than the depth of the facing surface 5b, and is provided on the axis C of the protruding electrode portion 5.

  In this surge protection element 1, when an overvoltage or overcurrent enters, an initial discharge is first performed between the discharge auxiliary portion 4 and the protruding electrode portion 5, and the discharge further develops triggered by this initial discharge. Electrons are emitted from the entire facing surface 5b of the projecting electrode portion 5 on the negative electrode side, and the other projecting from the respective portions of the facing surface 5b of one projecting electrode portion 5 as indicated by the two-dot chain line arrow shown in FIG. Arc discharge is performed to the protrusion 5c of the electrode part 5.

  Thus, 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 surface shape, and protrude toward the opposing protruding electrode portion 5 in the central region of the opposing surface 5b. Since the protruding portion 5c is formed, the place where the arc discharge reaches is concentrated on the protruding portion 5c in the central region of the concave surface 5b, and damage to the outer peripheral portion of the protruding electrode portion 5 can be reduced. The discharge start voltage can be stabilized.

That is, 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 opposing surface 5b having a concave curved surface has a uniform distance from the opposing protruding portion 5c. The electrons emitted from the entire facing surface 5b are easily concentrated on the protrusion 5c. Moreover, the fluctuation | variation range of a discharge start voltage also becomes small by the stable electric power reception of the arc discharge in the protrusion part 5c.
Further, since the protruding portion 5c protrudes from the outer peripheral edge portion of the facing surface 5b, the arc discharge from the facing surface 5b of the facing protruding electrode portion 5 is opposed to the position where the whole is lower than the tip of the protruding portion. Since it becomes difficult to reach the surface 5b, it becomes easier to concentrate on the protrusion 5c.

  In addition, since the discharge active layer 8 is formed of a material having higher electron emission characteristics than the material of the sealing electrode on at least a part of the facing surface 5b excluding the protrusions 5c, the discharge active layer 8 is difficult to reach discharge. Since at least a part of the facing surface 5b is covered, the arc discharge is more likely to be concentrated on the protrusion 5c, and the discharge active layer 8 provides stability of the operating voltage against repeated discharge, excellent withstand voltage characteristics, and the like. can get.

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

  The technical scope of the present invention is not limited to the above embodiment, and various modifications 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 central area of the opposing surface, but a plurality of protrusions may be provided in the central area. Even in this case, since the arc discharge concentrates on the plurality of protrusions in the central area of the opposing surface, it is possible to reduce damage to the outer peripheral surface of the protruding electrode portion.
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 protective element, 2 ... Insulating tube, 3 ... Sealing electrode, 4 ... Discharge auxiliary | assistant part, 5 ... Protruding electrode part, 5b ... Opposite surface of protruding electrode part, 5c ... Protruding 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 the discharge control gas inside;
The pair of sealing electrodes has a pair of protruding electrode portions protruding inward and facing each other,
The opposing surfaces of the pair of protruding electrode portions are formed in a concave curved surface shape,
A surge protection element, wherein a protruding portion that protrudes toward the protruding electrode portion is formed in a central region of the facing surface. The surge protection element according to claim 1,
A surge protection element, wherein a discharge active layer is formed of a material having an electron emission characteristic higher than that of the material of the sealing electrode on at least a part of the facing surface excluding the protrusion. The surge protection element according to claim 2,
A surge protection element, wherein the discharge active layer is formed on an outer peripheral edge of the facing surface. In the surge protection element according to any one of claims 1 to 3,
The surge protection element according to claim 1, wherein the protrusion protrudes from an outer peripheral edge of the facing surface.

Images