HK1161436B - Surge absorber - Google Patents

Description

Surge absorber

Technical Field

The present invention relates to a surge absorber which protects various devices from a surge generated by lightning or the like and is used to prevent an accident from occurring.

Background

In order to prevent the electronic equipment or the printed circuit board mounted on the electronic equipment from being damaged due to thermal damage or fire caused by abnormal overvoltage, the surge absorber is connected to a portion where the electronic equipment used for communication devices such as a telephone, a facsimile, a modem, etc. is in contact with a communication line, and a portion such as a power line, an antenna, a CRT driving circuit, etc. which is easily damaged by electric shock caused by abnormal overvoltage (surge voltage) such as lightning surge, static electricity, etc.

In general, as a surge absorber having good responsiveness, patent document 1 proposes a surge absorber using a surge absorbing element having a micro gap. The surge absorber is a surge absorber of a discharge type in which a so-called "micro gap" is formed on a peripheral surface of a ceramic member which is a cylindrical insulating member provided with a conductive coating, a surge absorbing element having a pair of electrode caps on both ends of the ceramic member is placed in a glass tube together with a discharge control gas, and a sealing electrode having leads on both ends of the cylindrical glass tube is sealed under high-temperature heating.

On the other hand, patent document 2 proposes a surge absorbing element of a discharge type having a carbon trigger wire in which a plurality of discharge electrodes composed of a rod-like discharge substrate are arranged opposite to each other across a discharge gap and then sealed in a sealed container together with a discharge gas. In a surge absorbing element of a discharge type in which a lead terminal connected to a lower end of an electrode base body is led out to the outside of a hermetic container, a trigger electrode made of a carbon wire is provided on a surface of a dielectric substrate base body in the hermetic container with a slight distance from each discharge electrode.

Patent document 1: japanese unexamined patent publication No. 2003-282216

Patent document 2: japanese patent No. 2745393

Disclosure of Invention

The following problems still remain in the above conventional techniques. In the micro gap type surge absorber disclosed in patent document 1, when a current surge having a long wave tail enters, the internal element is seriously damaged. Meanwhile, in the carbon trigger line type surge absorber disclosed in patent document 2, it is necessary to provide a projecting electrode for forming a main discharge, and at the same time, it is necessary to coat a discharge assistant to the tip of the projecting electrode to stabilize the dielectric breakdown voltage, resulting in an increase in manufacturing cost.

The present invention has been made in view of the foregoing circumstances, and it is an object of the present invention to provide a surge absorber capable of absorbing a surge having a long wave tail, thereby obtaining a stable insulation breakdown voltage without applying a discharge assistant to an electrode.

In order to solve the aforementioned problems, the present invention adopts the following structure. More specifically, the surge absorber of the present invention comprises a pair of terminal electrode members opposed to each other, and insulating tubes arranged on both ends of the terminal electrode members to contain a discharge control gas inside the surge absorber, wherein a projecting electrode member having a raised central portion is formed on the inner surfaces of the pair of terminal electrode members, and the projecting electrode member contains a metal capable of emitting more electrons than the terminal electrode members.

In the surge absorber, a projecting electrode member having a bulged central portion is formed on the inner surfaces of a pair of terminal electrode members. Therefore, the surge absorber can be manufactured with a simple structure. Further, since the electric field is concentrated on the bulging central portion of the projecting electrode member so as to be able to be easily discharged therefrom, the surge absorber can absorb a surge having a long wave tail. Further, since the projecting electrode member contains a metal capable of emitting more electrons than the terminal electrode member, a stable insulation breakdown voltage is obtained without applying a discharge assistant to the projecting electrode member.

Further, the surge absorber of the present invention is characterized in that the projecting electrode member is made of a solder that bonds the terminal electrode member and the insulating tube, and the projecting electrode member is formed on the inner surface of the terminal electrode member in a projecting state by surface tension when the solder is melted. More specifically, in the surge absorber, since the projecting electrode member is formed on the inner surface of the terminal electrode member in a projecting state by its surface tension when the solder for bonding is melted, the projecting electrode member having the bulged central portion can be easily formed while the terminal electrode member is bonded to the insulating tube.

Further, the surge absorber of the present invention is characterized in that the projecting electrode member is formed of Ag-containing solder. More specifically, in the surge absorber, since the projecting electrode member is formed of Ag-containing solder, since Ag contained in the solder has high electron emission energy, a stable insulation breakdown voltage is easily obtained.

The surge absorber of the present invention is characterized in that the trigger portion made of a conductive material is provided at an inner peripheral surface of the insulating tube at an intermediate portion between a pair of the terminal electrode members. More specifically, in the surge absorber, since the trigger portion made of a conductive material is provided at the inner peripheral surface of the insulating tube and at the intermediate portion between the pair of terminal electrode members, the responsiveness to the surge voltage is improved by the trigger discharge of the trigger portion.

In the surge absorber of the present invention, the insulating tube is formed of a square ceramic material. More specifically, in the surge absorber, since the insulating tube is formed of a square-shaped ceramic material, a highly stable insulating tube can be obtained as compared with a glass tube or the like, and surface mounting can be easily performed also because of a sheet-like or block-like shape.

According to the present invention, the following effects can be provided.

More specifically, according to the surge absorber of the present invention, a projecting electrode member having a raised central portion is formed on the inner surfaces of the pair of terminal electrode members, and the projecting electrode member contains a metal capable of emitting more electrons than the terminal electrode members. Therefore, the surge absorber can be manufactured in a simple structure while absorbing a surge having a long wave tail, whereby a stable insulation breakdown voltage can be obtained.

Drawings

Fig. 1 is a sectional view showing a surge absorber according to an embodiment of the present invention.

Fig. 2 is a perspective view showing a surge absorber according to the present embodiment.

Fig. 3 is an exploded perspective view showing a method of manufacturing the surge absorber according to the present embodiment.

Fig. 4 is a sectional view showing an example of a conventional surge absorber according to comparative example 1 of the present invention.

Fig. 5 is a sectional view of an example of a conventional surge absorber according to comparative example 2 of the present invention.

Detailed Description

A surge absorber according to an embodiment of the present invention will be described below with reference to fig. 1 to 3. In the drawings used in the following description, the proportions of the elements are appropriately changed so that the elements can be identified or easily identified.

As shown in fig. 1 to 3, the surge absorber (1) of the present embodiment includes a pair of terminal electrode members (2) opposed to each other; and an insulating tube (3), the pair of terminal electrode members (2) being arranged on both ends of the insulating tube (3) and having a discharge control gas sealed therein.

A projecting electrode member (4) having a raised central portion (4a) is formed on the inner surfaces of the pair of terminal electrode members (2).

The projecting electrode member (4) is made of solder (5) that bonds the terminal electrode member (2) and the insulating tube (3), and the projecting electrode member (4) is formed on the inner surface of the terminal electrode member (2) in a projecting state by its surface tension when the solder (5) is melted. Further, the projecting electrode member (4) contains a metal capable of emitting more electrons than the terminal electrode member (2). In the present embodiment, the projecting electrode member (4) is formed of an Ag — Cu solder as an Ag-containing solder.

The insulating tube (3) is formed of a hollow square ceramic material having a polygonal profile. Further, a trigger portion (6) made of a conductive material is provided at an inner peripheral surface of the insulating tube (3) at an intermediate portion between the pair of terminal electrode members (2). For the insulating tube (3), a ceramic material is preferably used, but a glass tube such as lead glass may also be used.

The trigger part (6) is a carbon trigger made of a carbon material, and may be formed in a linear shape other than the elliptic film shape shown in fig. 1.

The terminal electrode member (2) is a discharge electrode and is sealed at both ends of the insulating tube (3) by solder (5).

Examples of the foregoing discharge control gas include inert gases such as He, Ar, Ne, Xe, SF₆、CO₂、C₃F₈、C₂F₆、CF₄、H₂And mixed gases thereof.

In order to manufacture the surge absorber (1), an insulating tube (3) having an inner surface formed by a trigger part (6) is prepared, air in the insulating tube (3) is replaced with a predetermined discharge control gas (e.g., Ar), and then both ends of the insulating tube (3) are pressed to adhere to the terminal electrode member (2) and heated in a state where a solder (5) having a predetermined thickness is arranged on the joining surface and the inner surface of the terminal electrode member (2). In this manner, the solder (5) is melted and brought into close contact with the terminal electrode member (2) to perform sealing, thereby obtaining the surge absorber (1) in which the discharge control gas is sealed in the insulating tube (3).

When joining is performed, the melted solder 5 is pressed against the end of the insulating tube 3 so as to be pushed into the insulating tube 3, and then the projecting electrode member 4 is formed into a convex shape having a central portion 4a thereof raised by surface tension so as to be solidified. The thickness, material, heating conditions, etc. of the solder (5) can be determined according to the degree of expansion caused by the inner diameter or surface tension of the insulating tube (3). When the solder (5) expands due to surface tension, the projecting electrode member (4) is provided so as to form a convex shape, such as an arc-shaped cross-sectional shape having a bulged central portion (4a) instead of a trapezoidal cross-sectional shape.

The reason for this arrangement is as follows. If the electrode member has a trapezoidal cross section in which the solder (5) expands only by surface tension, but does not have a raised central portion, the electric field is not concentrated thereon because the central portion is flat, so that a desired discharge characteristic cannot be obtained.

As described above, although the solder (5) may be mounted separately from the terminal electrode member (2), the solder (5) may be bonded in advance to the joining surface of the terminal electrode member (2) to have a double-layer structure, and then melting and bonding are performed.

In the surge absorber (1), when an overvoltage or an overcurrent is input, trigger discharge is first performed between the projecting electrode element (4) and the trigger section (6), and then discharge further occurs between a pair of projecting electrode elements (4), thereby absorbing the surge.

In this way, in the surge absorber (1) of the present embodiment, the projecting electrode member (4) having the bulged central portion (4a) is formed on the inner surface of the pair of terminal electrode members (2). Thus, the surge absorber (1) can be easily manufactured with a simple structure. Further, the above surge absorber can absorb a surge having a long wave tail because an electric field is concentrated on the center portion (4a) of the swell of the projecting electrode member (4) so that discharge can be easily performed therethrough.

Further, since the projecting electrode member (4) contains a metal capable of emitting more electrons than the terminal electrode member (2), a stable insulation breakdown voltage is obtained without applying a discharge assistant to the projecting electrode member (4). Specifically, since the projecting electrode member (4) is formed with the Ag-containing solder (5), a stable insulation breakdown voltage can be easily obtained because Ag contained in the solder (5) has a high electron emission energy.

Moreover, since the projecting electrode member (4) is formed on the inner surface of the terminal electrode member (2) in a projecting state by its surface tension when the solder (5) for adhesion has melted, the projecting electrode member (4) having the bulged central portion (4a) can be easily formed while the terminal electrode member (2) is adhered to the insulating tube (3).

Since the trigger portion (6) made of a conductive material is provided at the inner peripheral surface of the insulating tube (3) and at the intermediate portion between the pair of terminal electrode members (2), the responsiveness to the impact voltage is improved by the trigger discharge of the trigger portion (6).

Since the insulating tube (3) is formed of a square ceramic material, a highly reliable insulating tube can be obtained as compared with a glass tube or the like, and also surface mounting can be easily performed because of the sheet-like or block-like shape.

Example 1

Next, based on the foregoing embodiments, the surge absorber of the present invention will be specifically described with reference to the evaluation results of the surge absorber actually produced by examples.

The surge absorber of the present invention according to example 1 was measured for the impact ratio ("impact insulation breakdown voltage"/"direct current insulation breakdown voltage"). Note that the closer the impact ratio is to 1, the better the responsiveness. The applied impulse was 5kV with a 1.2/50 voltage waveform. Further, the deterioration was measured when the applied surge was 5kV with 10/700 μ s. The results of these evaluations are shown in table 1 below.

As a comparative example, a conventional micro gap type surge absorber (11) (comparative example 1) was manufactured in which a cylindrical insulating member (17) on which a plurality of micro gaps (17a) were formed was arranged and sealed between a pair of terminal electrode members (2) as shown in fig. 4; and a conventional brake type surge absorber (21) (comparative example 2), as shown in fig. 5, the surge absorber (21) includes a pair of protrusion electrode members (27) protruding from a pair of terminal electrode members (22) in an opposed manner, and a trigger part (6) is formed on an inner surface of the insulating tube (3); and their evaluation results are also shown in table 1.

In comparative example 1, the insulating member (17) serving as an insulator had a diameter of 1mm, and seven micro gaps (17a) of 50/20 μm were formed thereon. In fig. 5, only four micro gaps (17a) are shown for simplicity.

TABLE 1

As a result of the evaluation, the impact ratio of example 1 was 1.2, the impact ratio of comparative example 1 was 2.0, and the impact ratio of comparative example 2 was 4. As described above, it was found that example 1 of the present invention has a smaller impact ratio (close to 1) than comparative examples 1 and 2, and thus has high-speed responsiveness.

After the surge was applied, no deterioration was found in example 1 and comparative example 2, whereas deterioration was found in comparative example 1.

As described above, it was found that example 1 of the present invention exhibited excellent responsiveness and had high surge resistance.

The technical scope of the present invention is not limited to the foregoing embodiments, but the present invention may be modified in various ways without departing from the scope or teaching of the present invention.

Reference numerals:

1,11, 21: surge absorber 2: terminal electrode element

3: an insulating tube 4: projecting electrode element

4 a: central portion 5 of the projecting electrode element: solder

6: trigger part

Claims (4)

1. A surge absorber, comprising:

a pair of terminal electrode members opposed to each other; and

an insulating tube, at both ends of which the pair of terminal electrode members are arranged, and which has a discharge control gas sealed therein,

wherein a projecting electrode member having a bulged central portion and an arc-shaped sectional shape is formed on inner surfaces of the pair of terminal electrode members, and the projecting electrode member contains a metal which emits more electrons than the terminal electrode members, and

wherein the projecting electrode member is made of a solder that bonds the terminal electrode member and the insulating tube, and the projecting electrode member is formed on an inner surface of the terminal electrode member in a projecting state by surface tension when the solder is melted.

2. The surge absorber of claim 1 wherein the projecting electrode element is formed from an Ag-containing solder.

3. The surge absorber according to claim 1, wherein a trigger portion made of a conductive material is provided at an inner peripheral surface of the insulating tube at an intermediate portion between the pair of terminal electrode members.

4. The surge absorber of claim 1 wherein the insulating tube is formed from a square ceramic material.