JP2017107678A - Surge protective element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surge protective element capable of suppressing sublimation and elimination of a discharge auxiliary part, and improving durability.SOLUTION: A surge protective element comprises an insulation tube 2, a pair of sealing electrodes for sealing a discharge control gas inside the insulation tube by blocking openings at both ends of the insulation tube, and a discharge auxiliary part 4 formed of a material containing an ion source material on an inner peripheral surface of the insulation tube. The pair of sealing electrodes includes a pair of protruding electrode parts protruding inward and facing to each other. The discharge auxiliary part includes a plurality of composite bodies 8 composed of a nuclear particle 8a formed of an ion source material and a coating film 8b formed of an insulation material and coating the nucleus particle.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. Usually, in such a surge protection element, a discharge auxiliary portion made of a carbon material is formed on the inner surface of an insulating tube facing an intermediate region between a pair of protruding electrode portions. Such a discharge auxiliary portion is generally formed of a conductive ion source material such as graphite and serves as an ion source for promoting initial discharge.

Utility Model Registration No. 3151069

The following problems remain in the conventional technology.
In the conventional structure, a part of the auxiliary discharge part sublimates and disappears due to the heat and expansion energy at the time of arc discharge generated between the pair of protruding electrode parts, and the discharge voltage at the time of repeated discharge is unstable (the discharge voltage increases). ).
In particular, in the discharge of a large current, the sublimation disappearance of the discharge auxiliary part tends to become remarkable. Also, if the discharge current greatly exceeds the guaranteed range, it is required to change the design of the electrode, and for stable operation, measures such as increasing the size or connecting in parallel are required. There was an inconvenience that was necessary.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a surge protection element that can suppress instability of operation due to sublimation disappearance of a discharge auxiliary portion.

  The present invention employs the following configuration in order to solve the above problems. That is, the surge protection element according to the first invention includes an insulating tube, a pair of sealing electrodes that closes both ends of the insulating tube and seals a discharge control gas therein, and the insulating tube. A discharge auxiliary portion formed of a material containing an ion source material on the inner peripheral surface of the electrode, and the pair of sealing electrodes has a pair of protruding electrode portions protruding inward and facing each other, and the discharge auxiliary portion The portion has a plurality of composites composed of core particles formed of the ion source material and a coating film formed of an insulating material and covering the core particles.

  In the surge protection element of the present invention, the discharge assisting portion has a plurality of composites composed of core particles formed of an ion source material and a coating film formed of an insulating material and covering the core particles. Therefore, since the core particles of the ion source material are protected by the coating film, the disappearance of sublimation of the ion source material due to discharge can be suppressed, and the discharge assist function can be maintained.

The surge protection element according to a second aspect of the present invention is characterized in that, in the first aspect, the discharge assisting part has a plurality of the core particles not covered with the coating film.
That is, in this surge protection element, since the discharge auxiliary part has a plurality of core particles not covered with the coating film, the core particles with the ion source material exposed on the surface are also mixed. Ions can be generated more than in the discharge assisting unit composed only of the composite, and the discharge assisting function can be improved.

A surge protection element according to a third invention is characterized in that, in the first or second invention, the coating film is formed of the same insulating material as that of the insulating tube.
That is, in this surge protection element, since the coating film is formed of the same insulating material as the insulating tube, the adhesion of the composite to the insulating tube is improved.

According to a fourth aspect of the present invention, there is provided the surge protection device according to any one of the first to third aspects, wherein the discharge assisting portion has at least two types of the composite films having the coating films set to different thicknesses. It is characterized by having.
That is, in this surge protection element, the discharge auxiliary part has at least two types of composites having coating films set to different thicknesses, so that a coating having a specific thickness is formed by the discharge arc energy. Even if the composite having the film disappears, the composite having the coating film having another thickness remains, so that the discharge assisting function can be maintained.

The present invention has the following effects.
That is, according to the surge protection element according to the present invention, the discharge assisting portion includes a plurality of core particles formed of an ion source material and a coating film formed of an insulating material and covering the core particles. Since the composite is included, the disappearance of sublimation of the ion source material due to discharge can be suppressed by the coating film, and the discharge assisting function can be maintained.
Therefore, even if the surge current and the number of discharges increase, it is possible to maintain the surge protection element performance satisfactorily. 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.

In 1st Embodiment of the surge protection element which concerns on this invention, it is a perspective view of the principal part which fractures | ruptures and shows a part of insulating tube. In 1st Embodiment, it is sectional drawing of the axial direction which shows a surge protection element. In 1st Embodiment, it is schematic sectional drawing which shows a composite_body | complex. In 2nd Embodiment of the surge protection element which concerns on this invention, it is sectional drawing which shows three types of composites.

  Hereinafter, a first embodiment of a surge protection element according to the present invention will be described with reference to FIGS. 1 to 3. 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 and an auxiliary discharge portion 4 formed of a material containing an ion source material on the inner peripheral surface of the insulating tube 2 are provided.
The pair of sealing electrodes 3 has a pair of protruding electrode portions 5 that protrude inward and face each other.
As shown in FIG. 3, the discharge assisting unit 4 includes a plurality of composites composed of core particles 8a formed of an ion source material and a coating film 8b formed of an insulating material and covering the core particles 8a. It has a body 8.

Moreover, the discharge auxiliary | assistant part 4 also has the some nuclear particle 8a which is not coat | covered with the coating film 8b. That is, the discharge auxiliary part 4 is composed of a mixture of a plurality of composites 8 and a plurality of core particles 8a.
The core particle 8a is formed of a carbon material such as graphite which is, for example, a rod-like, spherical or polygonal particle.
The ion source material of the core particle 8a is a conductive material, and for example, one of carbon materials, metals and alloys, or a composite thereof can be used.

The covering film 8b is formed of the same insulating material as that of the insulating tube 2. For example, when the insulating tube 2 is formed of an insulating material of alumina (Al ₂ O ₃ ), the coating film 8b is also formed of alumina.
Incidentally, the insulating tube 2, when formed of a glass tube of lead glass or the like containing SiO _2, even coating film 8b, is preferably formed of a SiO _2.
The insulating tube 2 is formed in a cylindrical shape.

If the coating film 8b is too thick, the generation of ions from the internal core particles 8a is excessively suppressed and it is difficult to be exposed to the discharge space. Therefore, it is preferable that the film thickness Rc of the coating film 8b is set within a range set by the following relational expression, where R is the radius of the core particle 8a.
R × 0.05 <Rc <R × 0.5

When the composite 8 is produced, the coating film 8b is coated on the surface of the core particle 8a using, for example, a sol-gel method.
For example, when the core particles 8a of carbon particles are coated with a silica (SiO 2) coating film 8b, the core particles 8a are surface-treated by heating or oxidation treatment such as nitric acid, and thereafter, the silica particles such as silicic acid solution are used as a silica raw material. Make contact. That is, an aqueous dispersion of the surface-treated core particles 8a and a silicic acid solution are mixed. As a result, silica is adsorbed on the surface of the core particle 8a by so-called heteroaggregation, and the core particle 8a is covered with the silica coating film 8b to form a composite 8 particle. The powder-like composite 8 is produced by drying and heat-curing the particles thus formed.

In order to manufacture the insulating tube 2, first, the raw material powder of the insulating material and a binder are mixed at a predetermined ratio, and after passing through a pulverization process, a drying process, etc., the resultant is formed into a cylindrical shape and subjected to a firing process. Insulating tube 2 is obtained by sintering.
In addition, when forming the produced composite 8 on the inner peripheral surface of the insulating tube 2, first, the powder of the composite 8 is adhered to the inner peripheral surface of the insulating tube 2 after the molding before the firing step. Further, the composite 8 is sintered on the inner peripheral surface of the insulating tube 2 together with the sintering of the insulating tube 2 in the firing step.

For example, when graphite is used as the ion source material of the core particle 8a and alumina is used as the insulating material of the insulating tube 2 and the coating film 8b, the sintering temperature in the inert gas in the firing step is 1200 ° C. And That is, since the reaction temperature between Al ₂ O ₃ (alumina) and graphite is 1280 ° C., the upper limit of firing is 1200 ° C. Even when SiO ₂ is employed as the insulating material, the reaction temperature between SiO ₂ and graphite is 1250 ° C., and therefore firing is performed at 1200 ° C. as an upper limit.

In addition, when an insulating material such as Al ₂ O ₃ or SiO ₂ is employed, a metal or alloy having a melting point of 1200 ° C. or less cannot be employed as the ion source material. Therefore, Au, Ag, Zn or the like cannot be used as the ion source material, and Ni, Ti, Mo, W, or the like can be used.
In addition, as the insulating material, magnesia, zirconia, aluminum nitride, silicon nitride, silicon carbide, and the like can be used.

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 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 , air, etc. and mixed gas thereof are used.

  In this surge protection element 1, when an overvoltage or overcurrent enters, initial discharge is first performed between the exposed core particle 8 a or the core particle 8 a in the composite 8 and the protruding electrode portion 5. As a result, the discharge further progresses and discharge is performed between the pair of flange portions 7 or between the protruding electrode portions 5.

  As described above, in the surge protection device 1 of the present embodiment, the discharge assisting portion 4 includes the core particles 8a formed of the ion source material and the coating film 8b formed of an insulating material and covering the core particles 8a. Since the core particles 8a of the ion source material are protected by the coating film 8b, the disappearance of the ion source material from sublimation due to the discharge can be suppressed. Auxiliary functions can be maintained.

Further, since the discharge assisting part 4 has a plurality of core particles 8a not covered with the coating film 8b, the core particles 8a with the ion source material exposed on the surface are also mixed, so that the composite body Ions can be generated more than in the discharge assisting section of only 8, and the discharge assisting function can be improved.
Furthermore, since the coating film 8b is formed of the same insulating material as that of the insulating tube 2, the adhesion of the composite 8 to the insulating tube 2 is improved.

  Next, a second embodiment of the surge protection element according to the present invention will be described below with reference to FIG. Note that, in the following description of the embodiment, the same components described in the above embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  The difference between the second embodiment and the first embodiment is that the thickness of the coating film 8b is set to be the same in the first embodiment, whereas in the surge protection element of the second embodiment, As shown in FIG. 4, the discharge assisting unit has at least two types of composites 28A, 28B, and 28C having coating films 28b, 28c, and 28d set to different thicknesses.

  That is, in the second embodiment, for example, as shown in FIG. 4 (a), the composite 28A coated with a thin coating film 28b and the coating film 28b as shown in FIG. 4 (b). The composite 28B coated with the thicker coating film 28c and the composite 28C coated with the coating film 28d thicker than the coating film 28c as shown in FIG. It is configured.

  As described above, in the surge protection element of the second embodiment, the discharge assisting portion has at least two types of composites 28A, 28B, and 28C having the coating films 28b, 28c, and 28d set to different thicknesses. Therefore, even if the composite (for example, the composite 28A) having the coating film having a specific thickness (for example, the coating film 28b) disappears due to the discharge arc energy, other thickness of the coating film (for example, the coated film) Since the composite (for example, 28B and 28C) having the covering films 28c and 28d remains, the discharge assisting function can be maintained.

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

  DESCRIPTION OF SYMBOLS 1 ... Surge protection element, 2 ... Insulating tube, 3 ... Sealing electrode, 4 ... Discharge auxiliary | assistant part, 5 ... Protruding electrode part, 8, 28A, 28B, 28C ... Composite, 8a ... Nuclear particle, 8b, 28b, 28c, 28d ... coating film

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;
An auxiliary discharge portion formed of a material containing an ion source material on the inner peripheral surface of the insulating tube;
The pair of sealing electrodes has a pair of protruding electrode portions protruding inward and facing each other,
The discharge assisting unit has a plurality of composites composed of core particles formed of the ion source material and a coating film formed of an insulating material and covering the core particles. Surge protective element. The surge protection element according to claim 1,
The surge protection element, wherein the discharge assisting part has a plurality of the core particles not covered with the coating film. The surge protection element according to claim 1 or 2,
The surge protection element, wherein the covering film is made of the same insulating material as the insulating tube. In the surge protection element according to any one of claims 1 to 3,
The surge protection element, wherein the discharge assisting part has at least two kinds of the composites having the coating films set to different thicknesses.

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