JP2018060729A - Surge protection element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surge protection element that suppresses occurrence of hold-over without increasing the area of opposing surfaces of protruded electrode parts.SOLUTION: A surge protection element comprises: a square cylinder shaped insulation tube 2 having four inner surfaces; a pair of sealing electrodes 3 which close and seal both-end openings of insulation tube; a discharge auxiliary portion 4 formed of an ion source material in a part of the four inner surfaces of insulation tube, in which the pair of sealing electrodes have a pair of flange parts 5, a pair of protruded electrode parts 6, and a pair of electrode auxiliary parts 7 which are adjacently formed to the pair of protruded electrode parts and protruded inward from the pair of flange parts and face to each other. The electrode auxiliary parts has an inclined plane 7a which extends from the protruded electrode parts toward an inner surface on which the discharge auxiliary portion of the insulation tube is not formed and inclined from tip parts of the protruded electrode parts toward the flange parts, and is not formed on an inner surface side on which the discharge auxiliary portion of the insulation tube 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 or static electricity in parts where electronic devices for communication equipment such as telephones, facsimiles, modems, etc. 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 Documents 1 and 2, for example, an arrester type comprising 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 peripheral surface of the insulating tube A surge protection element is described. Usually, in such a surge protection element, a discharge auxiliary portion made of a carbon material is formed on the inner peripheral surface of the insulating tube. 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. Further, in such a surge protection element, in order to position the insulating tube and the protruding electrode portion, a diameter-enlarged portion having a diameter larger than that of the distal end portion is provided on the proximal end side of the protruding electrode portion. .

JP 11-354244 A JP 2001-102148 A

The following problems remain in the conventional technology.
For example, in a discharge tube that is a surge protection element used for communication lines, it is necessary to cope with high-frequency signals, and it is necessary to minimize the area of the facing surface of the opposed protruding electrode part and the capacitance as small as possible. is there. However, if the current value to be transferred from the glow discharge to the arc discharge is low, when used in a circuit in which a voltage of DC 48V or the like is superimposed, if the area of the opposing surface of the protruding electrode portion is small, the holdover (discharge by DC voltage) There is a disadvantage that the possibility of the occurrence of the (continuing state) is increased. That is, in the process from the glow discharge to the arc discharge, the glow discharge first occurs, a part of the protruding electrode portion is covered with the glow discharge, and when the current increases, the current density becomes constant due to the characteristic of making the current density constant. Expands the glow discharge area. When the current further increases, the entire electrode surface is covered with glow discharge and becomes in an abnormal glow state. When the current further increases, the current concentrates on a part of the protruding electrode portion and is transferred to arc discharge. At this time, in order to increase the current value at the time of transition from glow discharge to arc discharge, it is important to increase the area of the opposing surface of the protruding electrode part. Then, there existed a problem that the electrostatic capacitance of the whole discharge tube (surge protection element) increased.
Moreover, in the said prior art, since the base side of the protrusion electrode part was expanded in diameter by the whole outer periphery of a protrusion electrode part, there existed a problem that the discharge space inside an insulating tube became small. In particular, since the protruding electrode part is expanded to the vicinity of the discharge auxiliary part formed on the inner surface of the insulating tube, the electrostatic capacity of the protruding discharge part is affected and the discharge in the vicinity of the discharge auxiliary part is performed. There was an inconvenience that the space became narrow.

  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 suppresses the occurrence of holdover without increasing the area of the opposing surface of the protruding electrode 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 is a pair of a rectangular tube-shaped insulating tube having four inner surfaces and a discharge control gas sealed inside by closing both end openings of the insulating tube. And a discharge auxiliary part formed of an ion source material on a part of four inner surfaces of the insulating tube, and the pair of sealing electrodes are in close contact with both end openings of the insulating tube A pair of flange portions fixed in a state, a pair of projecting electrode portions projecting inward from the center of the pair of flange portions and facing each other, and a pair of flanges formed adjacent to the pair of projecting electrode portions A pair of electrode auxiliary portions that protrude inward from the section and face each other, and the electrode auxiliary portions extend from the protruding electrode portions toward an inner surface of the insulating tube where the discharge auxiliary portions are not formed. And from the tip of the protruding electrode portion Has an inclined surface inclined toward the flange portion, characterized in that said on the inner surface of the discharge auxiliary section of the insulating tube is formed not formed.

  In this surge protection element, the electrode auxiliary portion extends from the protruding electrode portion toward the inner surface where the discharge auxiliary portion of the insulating tube is not formed and is inclined from the tip portion of the protruding electrode portion toward the flange portion. The inclined surface of the electrode auxiliary portion forms a glow discharge other than the opposing surface of the protruding electrode portion because the inclined auxiliary surface is not formed on the inner surface side where the discharge auxiliary portion of the insulating tube is formed. It functions as a surface and can increase the area as a discharge electrode. That is, since the inclined surface that forms glow discharge is formed in addition to the opposing surface (discharge surface) of the protruding electrode part, the arc transition point moves to the large current side, and the current value that generates holdover moves to the large current side. By doing so, it becomes difficult to generate a holdover. In addition, the inclined surface of the electrode auxiliary portion hardly affects the capacitance of the protruding electrode portion, and is not formed on the inner surface side where the discharge auxiliary portion is formed, and is not close to the discharge auxiliary portion. It is possible to ensure a sufficient discharge space in the vicinity of the auxiliary portion. Furthermore, it becomes possible to adjust the generation and area of glow discharge according to the inclination angle of the inclined surface of the electrode auxiliary portion.

The surge protection element according to a second invention is the surge protection element according to the first invention, wherein the inclined surface of the electrode auxiliary portion extends toward the entire width of the inner surface of the insulating tube where the discharge auxiliary portion is not formed. It is characterized by being.
That is, in this surge protection element, since the inclined surface of the electrode auxiliary portion extends toward the entire width of the inner surface of the insulating tube where the discharge auxiliary portion is not formed, a wide inclined surface can be secured, and the discharge auxiliary portion The area for glow discharge can be increased as much as possible on the inner surface side where no is formed.

According to a third aspect of the present invention, in the first aspect, the inclined surface of the electrode auxiliary portion is directed to approximately half of the width of the inner surface of the insulating tube where the discharge auxiliary portion is not formed. It is characterized by spreading.
That is, in this surge protection element, the inclined surface of the electrode auxiliary portion extends toward approximately half of the width of the inner surface of the insulating tube where the discharge auxiliary portion is not formed. In addition to securing an increased inclined surface, the discharge space can be enlarged on the inner surface side where the discharge auxiliary portion of the insulating tube is not formed.

A surge protection element according to a fourth invention is the surge protection element according to any one of the first to third inventions, wherein the electrode auxiliary portion is arranged in the vicinity of at least two opposing corners on the inner peripheral surface of the insulating tube. It has the positioning projection part made.
That is, in this surge protection element, since the electrode auxiliary portion has the positioning projections arranged up to the vicinity of at least two opposing corners on the inner peripheral surface of the insulating tube, the positioning projections Thus, the insulating tube and the sealing electrode can be positioned.

The present invention has the following effects.
That is, according to the surge protection element of the present invention, the electrode auxiliary portion extends from the protruding electrode portion toward the inner surface where the discharge auxiliary portion of the insulating tube is not formed, and the tip portion of the protruding electrode portion. Since the inclined surface is inclined toward the flange portion and is not formed on the inner surface side where the discharge auxiliary portion of the insulating tube is formed, the inclined surface can increase the area for glow discharge. And the occurrence of holdover can be suppressed. Further, since the electrode auxiliary portion is not formed on the inner surface side where the discharge auxiliary portion is not formed, it is possible to secure a sufficient discharge space in the vicinity of the discharge auxiliary portion.

In 1st Embodiment of the surge protection element which concerns on this invention, it is sectional drawing at the time of cut | disconnecting between a pair of protruding electrode parts. It is the sectional view on the AA line of FIG. It is the BB sectional view taken on the line of FIG. In 1st Embodiment, it is a front view which shows a sealing electrode. In 1st Embodiment, it is a side view which shows a sealing electrode. In 2nd Embodiment of the surge protection element which concerns on this invention, it is sectional drawing at the time of cut | disconnecting between a pair of protrusion electrode part. In 2nd Embodiment, it is a front view which shows the sealing electrode. In 2nd Embodiment, it is a side view which shows a sealing electrode.

  Hereinafter, a first embodiment of a surge protection element according to the present invention will be described with reference to FIGS. 1 to 5. 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 the present embodiment closes the rectangular tube-shaped insulating tube 2 having four inner surfaces, and the opening portions at both ends of the insulating tube 2. A pair of sealing electrodes 3 for sealing the discharge control gas, and a discharge auxiliary portion 4 formed of an ion source material on a part of the four inner surfaces of the insulating tube 2 are provided.

  As shown in FIGS. 3 to 5, the pair of sealing electrodes 3 includes a pair of flange portions 5 fixed in close contact with the opening portions at both ends of the insulating tube 2 and a center of the pair of flange portions 5. A pair of projecting electrode portions 6 projecting inward and facing each other, and a pair of electrode auxiliary portions 7 formed adjacent to the pair of projecting electrode portions 6 and projecting inward from the pair of flange portions 5 and facing each other are provided. doing.

The electrode auxiliary portion 7 extends from the protruding electrode portion 6 toward the inner surface where the discharge auxiliary portion 4 of the insulating tube 2 is not formed and from the tip portion of the protruding electrode portion 6 toward the flange portion 5. It has the inclined surface 7a which inclined, and is not formed in the inner surface side in which the discharge auxiliary | assistant part 4 of the insulating tube 2 is formed.
The inclined surface 7a of the electrode auxiliary portion 7 extends toward the entire width of the inner surface of the insulating tube 2 where the discharge auxiliary portion 4 is not formed.

Further, the electrode auxiliary portion 7 has a positioning projection 7b disposed up to at least the vicinity of two opposing corners 2a on the inner peripheral surface of the insulating tube 2.
In the present embodiment, positioning protrusions 7 b are provided in the vicinity of the four corners 2 a on the inner peripheral surface of the insulating tube 2. That is, the positioning projections 7b are provided at the four corners on the inner peripheral surface of the insulating tube 2, and each positioning projection 7b is in contact with the inner peripheral surface of the insulating tube 2 near the corner 2a. ing.

The discharge auxiliary portion 4 is formed linearly along the axis at the center of a pair of inner surfaces facing each other of the insulating tube 2. Further, the electrode auxiliary portion 7 is not formed on the inner surface side where the discharge auxiliary portion 4 is formed.
The discharge auxiliary portion 4 is a conductive material, and is formed of, for example, a carbon material.
The insulating tube 2 is a square cylindrical member formed of a crystalline ceramic material such as alumina. The insulating tube 2 may be an amorphous tube such as lead glass.

The sealing electrode 3 is made of, for example, 42 alloy (Fe: 58 wt%, Ni: 42 wt%), Cu, or the like.
In the sealing electrode 3, a square plate-like flange portion 5 is fixed in close contact with the opening portions at both ends of the insulating tube 2 by a conductive fusion material (not shown).
The pair of protruding electrode portions 6 are formed in a substantially cylindrical shape having the same axis as the insulating tube 2 and have a circular opposing surface 6a at the tip.

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.

A discharge active layer (not shown) is formed on the opposing surface 6 a of the protruding electrode portion 6 with a material having higher electron emission characteristics than the material of the sealing electrode 3.
The discharge active layer includes, for example, Si and O as main components and includes at least one of Na, Cs, and C. For this discharge active layer, for example, a cesium carbonate powder is added to a sodium silicate solution to prepare a precursor, and after this precursor is applied to the surface of the sealing electrode 3, the sodium silicate is softened to the precursor. It is produced by performing a heat treatment at a temperature higher than the temperature and higher than the temperature at which cesium carbonate melts and decomposes.

The positioning protrusion 7b has an outer peripheral portion formed in a half-cylindrical column shape.
The sealing electrode 3 is manufactured by cold forging using a mold, and the protruding electrode portion 6, the flange portion 5, and the electrode auxiliary portion 7 are integrally formed at the same time.

  In this surge protection element 1, when an overvoltage or overcurrent enters, first, initial discharge is preferentially performed between the discharge auxiliary portion 4 and the protruding electrode portion 6, and triggered by this initial discharge, When glow discharge occurs on the opposing surface 6a and the inclined surface 7a of each electrode auxiliary portion 7 and the current increases, the discharge further develops and discharge is performed between the pair of flange portions 5 or between the protruding electrode portions 6.

  Thus, in the surge protection element 1 of the present embodiment, the electrode auxiliary portion 7 extends from the protruding electrode portion 6 toward the inner surface where the discharge auxiliary portion 4 of the insulating tube 2 is not formed, and the protruding electrode. Since it has the inclined surface 7a inclined from the front-end | tip part of the part 6 toward the flange part 5, and is not formed in the inner surface side in which the discharge auxiliary | assistant part 4 of the insulating tube 2 is formed, The inclined surface 7a functions as a surface for forming glow discharge other than the opposing surface 6a of the protruding electrode portion 6, and the area of the discharge electrode can be increased.

  That is, since the inclined surface 7a for forming glow discharge is formed in addition to the opposed surface 6a (discharge surface) of the protruding electrode portion 6, the arc transition point moves to the large current side, and the current value for generating a holdover is a large current. Moving to the side makes it difficult for holdover to occur. Further, the inclined surface 7a of the electrode auxiliary portion 7 does not easily affect the electrostatic capacity of the protruding electrode portion 6, and is not formed on the inner surface side where the discharge auxiliary portion 4 is formed, and is close to the discharge auxiliary portion 4. Therefore, it is possible to secure a sufficient discharge space in the vicinity of the discharge auxiliary portion 4.

Moreover, since the inclined surface 7a of the electrode auxiliary portion 7 extends toward the entire width of the inner surface of the insulating tube 2 where the discharge auxiliary portion 4 is not formed, a wide inclined surface 7a can be secured, and the discharge auxiliary portion 4 is secured. The area for glow discharge can be increased as much as possible on the inner surface side where no is formed.
Furthermore, it is possible to adjust the generation and area of glow discharge according to the inclination angle of the inclined surface 7a of the electrode auxiliary portion 7.
Further, since the electrode auxiliary portion 7 has the positioning projection 7b disposed up to the vicinity of at least two opposing corner portions 2a on the inner peripheral surface of the insulating tube 2, the positioning projection 7b The insulating tube 2 and the sealing electrode 3 can be positioned.

  Next, a second embodiment of the surge protection element according to the present invention will be described below with reference to FIGS. 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, in the first embodiment, the inclined surface 7a of the electrode auxiliary portion 7 covers the entire width of the inner surface where the discharge auxiliary portion 4 of the insulating tube 2 is not formed. On the other hand, in the surge protection element 21 of the second embodiment, as shown in FIGS. 6 to 8, the inclined surface 27a of the electrode auxiliary portion 27 is replaced with the discharge auxiliary portion 4 of the insulating tube 2. It is the point which has spread toward about half of the width of the inner surface that is not formed.

That is, in the first embodiment, the electrode auxiliary portion 7 is not formed only on the inner surface side where the discharge auxiliary portion 4 of the insulating tube 2 is not formed, but in the second embodiment, the discharge auxiliary portion of the insulating tube 2 is formed. On the inner surface side where 4 is formed, the electrode auxiliary portion 27 is not formed in about half of the width, and a wide discharge space is secured between the protruding electrode portion 6 and the inner surface. Therefore, the area of the inclined surface 27a of the second embodiment is substantially half of the inclined surface 7a of the first embodiment.
Further, in the second embodiment, the positioning projections 7 b are provided in the vicinity of the pair of corners 2 a on the diagonal line facing each other on the inner peripheral surface of the insulating tube 2.

  As described above, in the surge protection element 21 according to the second embodiment, the inclined surface 27a of the electrode auxiliary portion 27 extends toward approximately half of the width of the inner surface where the discharge auxiliary portion 4 of the insulating tube 2 is not formed. Therefore, the inclined surface 27a that increases the area contributing to glow discharge can be secured, and the discharge space can be further expanded on the inner surface side of the insulating tube 2 where the discharge auxiliary portion 4 is not formed.

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.
For example, in each of the above-described embodiments, the inclined surface of the electrode auxiliary portion is a flat surface having a constant inclination angle, but may be a curved surface, and the staircase having a plurality of steps as the inclined surface of the electrode auxiliary portion. However, the surface may be inclined as a whole.

  DESCRIPTION OF SYMBOLS 1,21 ... Surge protection element, 2 ... Insulating tube, 2a ... Corner | angular part, 3,23 ... Sealing electrode, 4 ... Discharge auxiliary | assistant part, 5 ... Flange part, 6 ... Protruding electrode part, 7, 27 ... Electrode auxiliary | assistant Part, 7a, 27a ... inclined surface of electrode auxiliary part, 7b ... projection for positioning

Claims (4)

A rectangular tubular insulating tube having four inner surfaces;
A pair of sealing electrodes for closing the opening at both ends of the insulating tube and sealing the discharge control gas inside;
A discharge auxiliary part formed of an ion source material on a part of the four inner surfaces of the insulating tube;
A pair of sealing electrodes, a pair of flange portions fixed in close contact with both end openings of the insulating tube;
A pair of protruding electrode portions protruding inward from the center of the pair of flange portions and facing each other;
A pair of electrode auxiliary portions that are formed adjacent to the pair of protruding electrode portions and protrude inward from the pair of flange portions to face each other;
The electrode auxiliary portion extends from the protruding electrode portion toward an inner surface of the insulating tube where the discharge auxiliary portion is not formed, and is inclined from the distal end portion of the protruding electrode portion toward the flange portion. A surge protection element having an inclined surface that is not formed on an inner surface side of the insulating tube where the discharge assisting portion is formed. The surge protection element according to claim 1,
The surge protective element according to claim 1, wherein the inclined surface of the electrode auxiliary portion extends toward the entire width of the inner surface of the insulating tube where the discharge auxiliary portion is not formed. The surge protection element according to claim 1,
The surge protection element according to claim 1, wherein the inclined surface of the electrode auxiliary portion extends toward substantially half of the width of the inner surface of the insulating tube where the discharge auxiliary portion is not formed. In the surge protection element according to any one of claims 1 to 3,
The surge protection element according to claim 1, wherein the electrode auxiliary portion has a positioning protrusion disposed at least in the vicinity of two opposing corners on the inner peripheral surface of the insulating tube.

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