JPH03230486A - Surge absorbing element - Google Patents

Abstract

PURPOSE:To hardly lower the discharge start voltage and extend the life by providing collar sections in tip sections of electrode sections of two metal terminals of a surge absorbing element faced to each other. CONSTITUTION:A carbon thin film A is stuck on the whole surface of an insulator 2 made of a round bar-shaped alumina porcelain, two symmetrical portions B, B on the right and left are cut into a ring shape to expose the insulator 2, the thin film A is divided into three positions, portions on both sides are used as terminal fixing thin films 6, 6, and the center portion is used as a discharge thin film 3. U-shaped metal terminals 4, 4 made of SUS are fixed on both ends of the insulator 2, the root side has the inner diameter nearly equal to the outer diameter of the insulator 2 as a fixed section 41, the tip side has the inner diameter larger than the outer diameter of the insulator 2 by a preset size as an electrode section 42, a collar section 43 folded with the whole periphery to the outside is formed at its tip, and the gas discharge between the metal terminals 4 is mainly performed between the collars 43. The terminals 4 are inserted into both ends of the insulator 2, lead wires 5 are connected on the outside faces of the terminals 4, then a case 7 filled with gas is sealed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a surge absorbing element that absorbs surge voltage that occurs instantaneously in excess of a steady voltage.

[Problems to be solved by conventional techniques and inventions] Conventionally,
Among the surge absorbing elements, there is a so-called two-stage discharge type surge absorbing element (for example, the surge absorbing element disclosed in Japanese Patent Laid-Open No. 52-6956).

This kind of two-stage discharge type surge absorption element has a conductive thin film attached to the surface of a rod-shaped insulator, and cap-shaped metal electrodes are fixed to both ends of the insulator so as to be connected to the conductive thin film. Furthermore, the conductive thin film was divided into two or more parts via a filament, and these parts were sealed in a gas-filled case.

In a surge absorbing element having such a structure, when a surge voltage is applied between both electrodes, the electric field is first concentrated on the linear portion of the conductive thin film, and a first stage discharge occurs there. Next, the electrons released by this first-stage discharge collide with the gas sealed within the case, ionizing the gas.

The new electrons that fly out from the gas as a result of this ionization further ionize the gas, and the same phenomenon is repeated, so the ionization of this gas rapidly progresses, and eventually the insulating properties of the gas are destroyed and the gas becomes ionized. A gas discharge occurs directly between both electrodes as a two-stage discharge.

By the way, in the above-mentioned surge absorbing element, when a gas discharge occurs between both electrodes, the ionized gas collides with the negative electrode, and atoms and molecules are sputtered from the negative electrode and the gas is I get kicked out inside. Then, a part of it adheres to the filament, narrowing the width of the filament, and not only reducing the discharge voltage of this surge absorbing element, but also causing the risk that the two may eventually connect and cause a short circuit. .

Therefore, the applicant filed the patent application earlier (Japanese Patent Application No.
No. 276341) proposed a surge absorbing element 80 as shown in FIG.

As shown in the figure, this surge absorbing element 8o has a thin film 82 for discharge and a thin film 84 for terminal fixing on the surface of a rod-shaped insulator 81.
．． 84 and a thin film 84.8 for fixing the terminal.
Metal terminals 83.83 are attached to the metal terminals 83.83, lead wires 85.85 are fixed to these metal terminals 83.83, and these are housed in a case 87.

Here, the metal terminal 83 is composed of a fixing part 831 and an electrode part 832, and the part of the fixing part 831 is attached to a thin film 84 for fixing the terminal.
At this time, the tip of the electrode portion 832 is located at a predetermined distance from the discharge thin film 82.

With this configuration, the first stage of discharge is caused by the discharge thin film 82.
and the electrode portion 8320, and the second stage gas discharge is performed between the two types of pole portions 832, 832.

At this time, what is mainly sputtered by the second stage gas discharge is the electrode portion 8 of the negative metal terminal 83.
It is near the tip of 32. Therefore, the sputtered material generated by the sputtering is difficult to enter the deep inside of the electrode section 832. Therefore, the insulator 8 at the back
The sputtered material is difficult to adhere to the surface where 1 is exposed.

By configuring the surge absorbing element as described above, the discharge starting voltage is less likely to drop than in the past, and its lifespan is significantly extended.
3 and the discharge thin film 82 became less likely to be short-circuited.

Although the durability of this surge absorbing element 80 is sufficient for practical use, the present invention further improves this surge absorbing element to create a surge absorbing element whose service life is further extended because the discharge starting voltage is further reduced. is intended to provide.

[Means to solve the problem]

The present invention comprises a rod-shaped insulator 2, a discharge thin film 3 made of a conductive material attached to a predetermined portion of the surface of the insulator 2, a fixing part 41 fixed to an end of the insulator 2, and a The electrode portion 42 has an inner diameter enlarged so as to be separated from the discharge thin film 3 by a predetermined distance, and has two metal terminals 4.4 attached to both ends of the insulator 2, respectively. The tip portions of the electrode portions 42 and 42 of No. 4 are provided with collar portions 43 and 43 formed by bending the tip portions at approximately right angles, respectively.
The surge absorbing element 1 was constructed by providing the following.

[Effect]

Since the flanges 43 and 43 are provided as described above, both terminals 4 and 4
Gas discharge between the two is mainly performed between the flanges 43, 43, and sputtering is also mainly concentrated on the flanges 43, 43. Therefore, it is considered that the inner and outer circumferential surfaces of the electrode portions 42, 42 are less likely to be sputtered.

Therefore, even if the terminals 4 and 4 of this surge absorbing element 1 are discharged many times, the discharge starting voltage becomes difficult to drop.
Kira's lifespan is extended.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail based on the drawings.

FIG. 1 is a side sectional view showing a surge absorbing element 1 according to the present invention (however, the insulator 2, the discharge thin film 3, and the terminal fixing thin film 6 are not shown in the cross section).

As shown in the figure, a surge absorbing element 1 according to this embodiment
, a round bar-shaped insulator 2, a discharge thin film 3 and a terminal fixing thin film 6.6 completely attached to the surface of the insulator 2, and a metal terminal 4 attached on the terminal fixing thin film 6.6. ,4
and a lead wire 5.5 connected to the metal terminal 4°4,
It is completely constructed by case 7.

Each component of this surge absorbing element 1 and its manufacturing method will be explained in detail below.

Here, FIG. 2 is a diagram showing a method of manufacturing this surge absorbing element 1.

First, as shown in FIG. 3(a), an insulator 2 made of a round bar of alumina porcelain is prepared.

Note that the material of this insulator 2 is not limited to this, and other porcelains (for example, mullite porcelain, orsterite porcelain, steatite porcelain, etc.) may be used, and they also have the effects of the present invention. Any insulating material other than porcelain may be used for that.

Next, as shown in FIG. 2B, a thin carbon film A is deposited on the entire surface of this insulator 2.

Note that the material of this thin film A is not limited to this, and may be a metal, for example, tin oxide (Sno), niobium oxide (Nb*C) +), molybdenum oxide (MoO
s), tungsten oxide (WO.

), titanium nitride (TiN), tantalum nitride (TaN),
You may use metal compounds such as.

Next, as shown in FIG. 4C, two symmetrical positions B and B portion of this thin film A are cut into a ring shape to expose the insulator 2, and the thin film A is divided into three parts.

Here, of the divided thin film A, the parts on both sides are used as the terminal fixing thin film 6.6, and the central part is used as the discharge thin film 3.

Next, as shown in FIG. 2D, metal terminals 4, 4 made of metal (for example, SUS, N1Fe) are fixed to both ends of this insulator 2.

Here, the metal terminals 4, 4 have a cap shape with a substantially U-shaped cross section, and the inner diameter of the base side thereof is formed to be substantially concave with the outer diameter of the insulator 2, and a fixing portion 41 is formed. The inner diameter of the distal end thereof is larger than the outer diameter of the insulator 2 by a predetermined dimension to form an electrode portion 42 .

Furthermore, a flange portion 43 whose entire circumference is bent outward is formed at the tip of the electrode portions 42, 42 of these metal terminals 4, 4.

Then, the metal terminals 4.4 are inserted into both ends of the insulator 2, and the fixing parts 41.41 of the metal terminals 4,4 are attached to cover the terminal fixing thin films 6,6.

By caulking the outer periphery of the fixing portions 41.41, the metal terminals 4, 4 are fixed onto the terminal fixing thin films 6, 6.

At this time, as shown in the figure, the flange portions 4 of both metal terminals 4, 4
3 and 43 face each other with a predetermined distance apart.

Note that the reason why the terminal fixing thin films 6, 6 are left attached to the insulator 2 is to make the surface of the attached part smooth and to ensure the fixation of the fixing part 41 to the insulator 2. This is to do so. However, the terminal fixing thin films 6, 6 may not be necessary depending on the case.

Next, as shown in FIG. 4(d), lead wires 5, 5 are connected to the outer surface of this metal terminal 4.4.

Finally, as shown in FIG. 1, this insulator 2 is sealed in a case 7 filled with gas.

Here, the case 7 is made of an insulating material. Also, inside this case 7, argon (Ar), helium (H
e) An inert gas such as neon (Ne) or nitrogen gas is sealed. Further, depending on the case, the inside of this case 7 may be set to a vacuum.

This completes the surge absorbing element 1.

Next, the operation of this surge absorbing element 1 will be explained.

As shown in FIG. 1, when a surge voltage is applied between both metal terminals 4, 4, first of all, the area near the end of the discharge thin film 3 and the flange 43 (or near the tip of the electrode part 42) is An electric field concentrates between them, and the first stage of discharge occurs here. That is, the discharge thin film 3 and the metal terminal 4 are not connected, and the discharge thin film 3 and the flange portion 43 (or near the tip of the electrode portion 42) are spaced apart by a predetermined distance so that discharge occurs between them. Since the discharge thin film 3 and the flange part 43 (or electrode part 4
The first stage of discharge occurs between the two ends (near the tips of the two).

Electrons released by this first stage discharge then collide with the surrounding gas, ionizing the gas.

New electrons ejected from the gas as a result of this ionization further ionize the gas, and the same phenomenon is repeated thereafter, so that the ionization of the gas rapidly progresses. Finally, the insulation of the gas is broken, and a second stage of gas discharge occurs directly between the two flanges 43, 43.

FIG. 3 shows the rate of change ((VS −VSO) /VSO) of the discharge starting voltage vS with respect to the initial discharge starting voltage VSO when the surge voltage shown in FIG. ).

The peak value of the surge current shown in Fig. 4 is 130A, and the waveform (regular wavefront length x standard wavetail length μ) is as follows.
(8X20ss).

As shown in FIG. 3, in this surge absorbing element 1,
Even if the surge voltage is applied 500 times and the surge current is passed, the rate of change is within 20%, and the discharge starting voltage v
S is less likely to fall, and its life is significantly extended.

The inventor speculates as follows about why such an effect occurs.

That is, in the present invention, since the flanges 43, 43 are provided at the tips of the electrode portions 42, 42, most of the second stage gas discharge occurs between the flanges 43, 43. Therefore, the gas ionized by the second-stage gas discharge mainly collides with the minus-side flange 43, and it is also the flange 43 (ie, the front surface of the electrode part 42) that is sputtered. Therefore, the inner and outer circumferential surfaces of the minus-side electrode section 42 are less likely to be sputtered, and the sputtered material is also less likely to adhere to the inner periphery of the electrode section 42, which is thought to produce the above-mentioned effects.

Although the embodiments of the surge absorbing element according to the present invention have been described in detail above, the present invention is not limited thereto. Various modifications are possible.

〔Effect of the invention〕

As explained in detail above, according to the surge absorbing element of the present invention, since the flanges are provided at the opposing tips of the electrode portions of the two metal terminals, gas discharge between the two is mainly caused by the flanges. This has the excellent effect of making it difficult for the discharge starting voltage to drop and extending its life.

[Brief explanation of drawings]

FIG. 1 is a side cross-sectional view showing a surge absorbing element 1 according to the present invention, FIG. 2 is a diagram showing a method for manufacturing the surge absorbing element 1, and FIG. Figure 4 is a diagram showing the rate of change of the discharge starting voltage ■S. Figure 4 is a waveform diagram of the surge current applied to the surge absorbing element 1.
The figure is a side sectional view showing a surge absorbing element previously proposed by the inventor of the present application. In the figure, 1... surge absorption element, 2... insulator, 3...
... Thin film for discharge, 4.4... Terminal, 41... Fixing part, 42... Electrode part, 43... Flange part, 5.5... Lead wire, 6°6... A thin film for fixing terminals.

Claims (2)

[Claims] (1) A rod-shaped insulator, a discharge thin film made of a conductive material attached to a predetermined portion of the surface of the insulator, a fixed part fixed to the end of the insulator, and a predetermined distance from the discharge thin film. and two metal terminals each having an electrode portion whose inner diameter is enlarged so as to be separated from each other, and which are attached to both ends of the insulator, respectively, and the tip portions of the electrode portions of the two metal terminals are provided with the tip portions. A surge absorbing element characterized by having a flange formed by bending at a substantially right angle. (2) Claim (1) characterized in that a terminal fixing thin film made of a conductive material is attached to a position covered by the fixing part of the metal terminal near both ends of the surface of the insulator.
The surge absorbing element described.