JPH0732054B2 - Surge absorption element - Google Patents

Description

The present invention relates to a surge absorbing element for protecting electrical equipment and the like from surges such as lightning damage, static electricity and noise, and more specifically, a conductive thin film is formed on the surface of an insulator via a gap. The present invention relates to improvement of a surge absorbing element formed.

The applicant has a small discharge delay, a small capacitance,
We have developed and disclosed surge absorbing elements with excellent discharge performance (Japanese Patent Publication No. 55-43595, Japanese Patent Publication No. 56-44547, Japanese Patent Publication No. 53-84).
8, JP-A-55-128238, JP-A-56-168379, actual development Sho 56-1
30291).

In these surge absorbing elements, a conductive thin film is formed on the surface of an insulator, the conductive thin film is divided into a plurality of gaps, and the divided conductive thin film is made of a metal or an alloy having high electric conductivity. Each of the electrodes is in close contact with the conductive thin film. In such a surge absorption element, when a surge voltage is applied between the electrodes and it reaches a certain specified value,
First, electrons are generated in the gap of the conductive thin film to cause discharge, and then arc discharge is generated between the metal pieces or alloy pieces forming the electrodes, thereby absorbing the surge.

The present invention, as a result of research for further significantly improving the life characteristics of the surge absorbing element having such excellent characteristics,
It was developed.

An object of the present invention is to provide a surge element capable of significantly extending its life without impairing the characteristics of the surge absorbing element.

Another object of the present invention is to provide a surge absorbing element capable of preventing a decrease in reliability due to contamination from the environment when the environment in which the surge absorbing element is installed is not appropriate.

According to the present invention, the surge absorber is a cylindrical insulator,
A conductive thin film that covers the surface of the insulator and is symmetrically formed with respect to the longitudinal center of the cylinder, and is divided into a plurality of gaps in a ring shape, and adheres to the thin films at both ends of the divided conductive thin film. It consists of a pair of electrodes, and opposite electrodes facing each other are placed opposite to each other by surrounding a conductive thin film at a position separated from the conductive thin film, and arc discharge occurs at the opposite ends, so the conductive thin film deteriorates. Is prevented.

Therefore, the life of the surge absorbing element is greatly extended, which contributes to the industrial world in combination with its excellent discharge characteristics.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded.

FIG. 1 is a vertical sectional view of a surge absorber 10 according to an embodiment of the present invention.

The insulator 11 is a molded body of an insulating material such as mullite porcelain, forsterite porcelain, and alumina porcelain having a small dielectric constant.
The shape is not particularly limited. A conductive thin film 12 is attached to the surface of the insulator 11. Examples of the dielectric thin film 12 include metal oxides such as tin oxide (SnO ₂ ) and niobium oxide (Nb ₂ O ₅ ), titanium nitride (TiN), metal nitrides such as tantalum nitride (TaN), and aluminum (Al). The substance is not particularly limited as long as it is a single metal such as nickel, nickel (Ni), or so-called conductive thin film such as carbon (C). As a method for depositing the conductive thin film 12 on the insulator 11, a chemical vapor deposition method,
There are vacuum vapor deposition method, sputtering method, ion plating method (Japanese Patent Application No. 57-81504), spraying method and the like, but the method is not limited.

The conductive thin film 12 is divided into a plurality of parts with a narrow gap 13 therebetween. The gap 13 has a width of, for example, about 10 to 50 μm. The method of forming the gap 13 can be achieved by, for example, depositing a conductive thin film on the insulator 11 and then making a cut in the conductive thin film 12 using a laser beam or a diamond blade. These conductive thin films
It is generally preferable that the gap 13 dividing 12 is narrow. If a narrow gap 13 is required, a laser beam may be used, and a stable gap 13 up to a width of 10 μm can be obtained.

A pair of electrodes 14, 14 are attached to both ends of the conductive thin film 13 in close contact with each other.

The electrodes 14 and 14 are made of a pair of metals or alloys having high corrosion resistance and high electric conductivity. The electrodes 14 and 14 have counter electrodes 15 and 15 that face each other at positions separated from the conductive thin film 12.

The counter electrodes 15 and 15 are for preventing arcing at a position apart from the thin film 12 when the surge absorbing element 10 of the present invention discharges and causing deterioration of the thin film 12.

The material of the electrode 14 is a metal such as copper (Cu), zinc (Zn), nickel (Ni), aluminum (Al), iron (Fe),
Alternatively, alloys such as brass, phosphor bronze, nickel silver and stainless steel can be used. The opposite electrode 15 and the electrode 14 may be made of the same material, or may be of a combination of different materials.

The shape of each metal piece or alloy piece forming the electrodes 14, 14 and the shape of the counter electrodes 15, 15 are not limited.

The operation of the surge absorbing element of the present invention is as follows.

When a surge is applied between the electrodes 14 on both ends, the surge voltage is applied to both sides of the gap 13 through the conductive thin films 12 and 12, and the electric field is concentrated near the gap 13. Therefore, when the surge voltage reaches a certain value, electrons are generated in a portion of the gap 13 between the conductive thin films 12, 12 which are separated from each other by a short distance, and a discharge is first generated between both sides of the gap 13. . At this time, the energy of the surge causes various discharge states. First,
If the energy of the surge is small, discharge will occur only between the two sides of the gap 13, but if the energy of the surge is high, the gap will be discharged.
The discharge between both sides of 13 shifts to an arc discharge between electrodes 14 and 14. The surge is absorbed by this arc discharge.

The present invention, as the structure of the electrode, by providing the counter electrodes 15 and 15 that generate arc discharge in a position distant from the conductive thin film 12, the conductive thin film 12 when a high energy surge is applied. The high heat generated by the arc discharge causes the conductive thin film 12
Suppresses the influence on, to prevent the deterioration of the conductive thin film 12,
As a result, the life characteristics of the surge absorbing element 10 are dramatically improved.

An example in which the life of the surge absorbing element is improved by the present invention is shown in FIG. Fig. 2 is a life characteristic diagram showing the change of insulation resistance value with respect to the number of times of surge application.
A standard lightning surge of (1.2 × 50) μsec, 5KV was applied and the insulation resistance of the surge absorber was observed.

A curve (a) in FIG. 2 is an example of a surge absorbing element having a conventional structure, that is, a surge absorbing element having no opposing electrodes 15 and 15 separated from the conductive thin film 12, and the electrode portion which causes arc discharge and the conductivity. There is no space between the thin film 12 and the thin film 12.
The curve (b) in FIG. 2 is an example of the surge absorbing element according to the present invention, and there is a space between the counter electrodes 15 and 15 and the conductive thin film 12 which cause arc discharge of the electrodes.

As is apparent from FIG. 2, when a surge having high energy such as lightning surge is applied, the effect of arc discharge on the conductive thin film in the surge absorbing element of the present invention is higher than that in the conventional surge absorbing element. Therefore, the life characteristics are significantly improved.

FIG. 3 is a vertical sectional view of a surge absorbing element 30 according to another embodiment of the present invention.

This surge absorber 30 is a cylindrical forsterite porcelain
31, a two-divided tin oxide thin film 32 adhered to the entire surface via a gap 33, and cap-shaped nickel electrodes 34, 34 having a diameter larger than that of the forsterite porcelain 31. The cap-shaped nickel electrodes 34, 34 are arranged at both ends of the forsterite porcelain 31 and are in close contact with both ends of the tin oxide thin film 32 divided into two parts. Peripheral portions of the cap-shaped nickel electrodes 34, 34 are opposed to each other at positions separated from the tin oxide thin film 32 to form counter electrodes 35, 35.

The surge absorbing element 30 is manufactured as follows.

A cylindrical forsterite porcelain 31 is used as an insulator, a tin oxide (SnO ₂ ) thin film 32 is deposited on the entire surface of the forsterite porcelain 31 by a spraying method, and then the tin oxide thin film 32 is coated with a circle. A YAG laser is used along the circumference of the column-shaped forsterite porcelain to form one gap 33 of about 50 μm width, and the tin oxide thin film 32 is divided into two parts, which are then made of nickel. A pair of cap-shaped electrodes 34,3
4 is attached to the outermost ends of the tin oxide thin film 32 divided into two pieces.

In this embodiment, the cap-shaped electrodes 34, 34 have a peripheral portion having a diameter of about 1.5 times the outer diameter of the tin oxide thin film 32, and the peripheral portions form counter electrodes 35, 35 with each other. The arc discharge is generated between the counter electrodes 35, and is separated from the tin oxide thin film, so that the deterioration of tin oxide is prevented and the life is long.

FIG. 4 shows that the surge absorbing element 40 has an outer cover made of a highly insulating material as a measure for preventing the reliability of the surge absorbing element from being deteriorated due to contamination from the environment in which the surge absorbing element is installed. It is a characteristic embodiment.

In this embodiment, a cylindrical mullite porcelain 41 is used as an insulator.
The carbon (C) thin film 42 is deposited on the entire surface of the mullite porcelain 41 by a spraying method. The carbon thin film 42
Using a YAG laser, insert two gaps 43 of about 30 μm width,
The carbon thin film 42 is divided into three parts.

The carbon thin film obtained by dividing the cap-shaped electrode 44 made of stainless steel into three parts, in which the both ends of the mullite porcelain 41 are fitted in the central part so that the mullite porcelain 41 is located at the center, is divided into three parts. It sticks to both ends of 42. As a measure for preventing the reliability of the mullite porcelain 41 and the carbon thin film 42 from being deteriorated due to the contamination from the external environment, the insulating jacket 45 so as to wrap the mullite porcelain 41, the carbon thin film 42, and the stainless steel electrode 44. Is used to seal the stainless steel electrode 44 and the insulating jacket 45 at the sealing portion 46.

In this case, the material of the insulating jacket 45 is lead glass,
Glass materials such as hard glass, ceramic materials such as alumina, forsterite, steatite, epoxy, PBT
Any material having a high insulating property, such as a resin material such as, may be used, and the shape thereof is not limited.

This embodiment includes an insulating jacket 45, which is
Mullite porcelain 41, which is an insulator, and at least counter electrodes 47, 4
It has a long life without being affected by contamination from the environment in which the surge absorber is installed by enclosing 7 opposite ends.

In the embodiment 50 shown in FIG. 5, in the surge absorbing element, metals or alloys 55, 55 having good adhesion to the insulating outer covering are fixed to the outer surfaces of the pair of electrodes 54, 54, respectively. This is an embodiment characterized in that the metal or alloy 55, 55 and the insulating jacket 57 are sealed.

In this case, as the combination of the highly insulating insulating jacket 57 and the metal or alloy 55, 55, a combination of lead glass and Dumet, hard glass and Kovar, ceramics (steatite, forsterite, etc.) and Kovar, etc. It is suitable. However, the combination of these is not particularly limited.

This Example 50 is an embodiment in which the adhesiveness of the insulating jacket 57 is enhanced. Specifically, the Example of FIG. 5 will be described. A cylindrical alumina porcelain 51 is used as an insulator.
After depositing a titanium nitride (TiN) thin film 52 on the entire surface of 51 by the ion plating method, YA is formed on this titanium nitride thin film 52.
Using the G laser, the titanium nitride thin film 52 is divided into three parts by inserting two gaps 53 with a width of about 15 μm, and then the titanium nitride thin film in which the cap-shaped electrode 54 made of stainless steel is divided into three parts. After sealing at the extreme ends of 52, a disc-shaped Dumet board 55 having a structure in which lead wires 56 are attached is adhered from both ends of the stainless steel electrode 54, and then a Dumet board 55 as a jacket 57. The cylindrical lead glass having good sealing property is wrapped around the alumina porcelain 51, the titanium nitride thin film 52, and the stainless steel electrode 54, and the dumet disk 55 and the lead glass are sealed with the sealing portion 58 using the lead glass. It is a dress.

In this Example 50, the counter electrodes 59, 59 that generate an arc discharge are separated from the titanium nitride thin film 52, and the jacket 57 and the Dumet board 55 are tightly sealed by the sealing portion 58, and the installation is performed. Protected from the environment, it has a long service life, and it is easy and reliable to seal and easy to manufacture.

[Brief description of drawings]

FIG. 1, FIG. 3, FIG. 4, and FIG. 5 are longitudinal sectional views of the embodiment of the present invention, and FIG. 2 is a life characteristic diagram of the embodiment and the comparative example. 10,30,40,50 …… Examples of the present invention 11 …… Insulator 12 …… Conductive thin film 13,33,43,53 …… Gap 14 …… Electrode 15,35,47,59 …… Counter electrode 31 …… Forsterite porcelain 32 …… Tin oxide thin film 34 …… Nickel electrode 41 …… Mullite porcelain 42 …… Carbon thin film 44 …… Stainless steel electrode 45,57 …… Insulating jacket 46,58 …… Sealing part 51 …… Alumina porcelain 52 …… Titanium nitride thin film 54 …… Stainless steel electrode 55 …… Metal or alloy (Dumet board) 56 …… Lead wire

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Bibliographic references Sho 58-43790 (JP, U)

Claims (3)

[Claims] 1. A cylindrical insulator, and a conductive thin film that covers the surface of the insulator and is formed symmetrically with respect to the center of the cylinder in the longitudinal direction and is divided into a plurality of gaps into a ring shape. A pair of electrodes that are in close contact with the thin films at both ends of the divided conductive thin film, and counter electrodes that face each other are surrounded by the conductive thin film at a position separated from the conductive thin film. A surge absorbing element characterized by being installed. 2. The surge absorbing element according to claim 1, further comprising an insulating jacket enclosing the insulator and at least opposite ends of the counter electrode. 3. Fixed to each outer surface of said electrode,
The surge absorbing element according to claim 2, further comprising: a metal body having good adhesion to the insulating jacket and the insulating jacket that is in close contact with the metal body.