JP2012212535A - Surge absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite-type surge absorber which can be integrated compactly and can be assembled easily at a low cost.SOLUTION: The surge absorber comprises a pair of end electrodes 2 disposed to face each other, and an insulating tube 3 in which a hermetically sealed discharge space S is formed with the pair of end electrodes 2 being arranged at the both ends. A varistor 4 is provided on at least one internal surface of the pair of end electrodes 2. Since the varistor 4 facing the discharge space S functions as a part of the discharge electrode of a surge absorption element, the composite function of varistor function and surge absorption function can be built in compactly.

Description

  The present invention relates to a surge absorber used for protecting various devices from a surge caused by a lightning strike or the like and preventing an accident in advance.

  Portions where electronic devices for communication devices such as telephones, facsimiles, modems, etc. are connected to communication lines, power lines, antennas, CRT drive circuits, etc., portions that are susceptible to electrical shock due to abnormal voltage (surge voltage) such as lightning surge or static electricity A surge absorber is connected 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 an abnormal voltage.

  Conventionally, in the case of use in a circuit to which a power supply voltage is applied, a discharge type surge absorber has a low arc sustaining voltage and discharge does not stop and there is a risk of subsequent flow. Furthermore, a composite type surge absorber in which a discharge type surge absorber and a varistor are connected in series with each other has been proposed.

JP-A-5-283140 JP 2000-188169 A Japanese Patent Laid-Open No. 3-198301

The following problems remain in the conventional technology.
In the case of a composite type surge absorber combining a conventional discharge type surge absorber and varistor, when the discharge type surge absorber and varistor are manufactured independently, the manufacturing process becomes complicated due to the combination of these, resulting in high costs. As a result, there was an inconvenience of increasing the size. In addition, when an internal lamination type varistor in which a plurality of internal electrodes and varistor layers are laminated is employed, there is a disadvantage that the manufacturing process is complicated and the cost is increased.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a composite surge absorber that can be compactly integrated, is low-cost, and is easy to assemble.

  The present invention employs the following configuration in order to solve the above problems. That is, a surge absorber according to a first aspect of the present invention includes a pair of end electrodes opposed to each other and an insulating tube in which the pair of end electrodes are arranged at both ends and the inside is sealed to form a discharge space. And at least one of the pair of end electrodes includes a varistor portion formed of a varistor material at least on the inner surface side.

  That is, in this surge absorber, since at least one of the pair of end electrodes is provided with a varistor part formed of a varistor material at least on the inner surface side, the varistor part is electrically connected in series with the surge absorber function part between the electrodes. It is connected and built in, and functions as a part of the discharge electrode of the surge absorbing element facing the discharge space. Therefore, this surge absorber can incorporate a composite function of a varistor function and a surge absorption function in a compact manner. Further, it is possible to easily assemble the varistor part as at least a part of the end electrode in the insulating tube, and it can be manufactured at a low cost and in a small size.

The surge absorber according to the second invention is characterized in that, in the first invention, a metal electrode film is formed on the inner surface of the varistor portion.
That is, in this surge absorber, since the metal electrode film is formed on the inner surface of the varistor portion, the discharge characteristics can be adjusted by the metal electrode film having higher conductivity than the varistor material.

The surge absorber according to a third aspect of the present invention includes the pair of varistor portions disposed on the inner surfaces of the pair of end electrode bodies and disposed in the insulating tube in the first or second aspect of the invention. A cylindrical spacer inscribed in the inner peripheral surface of the insulating tube is interposed between the varistor portions.
That is, in this surge absorber, a cylindrical spacer that is inscribed in the inner peripheral surface of the insulating tube is interposed between a pair of opposed varistor portions, so that the interval between the pair of varistor portions can be adjusted by the spacer. Can be easily positioned and assembled.

According to a fourth aspect of the present invention, in the surge absorber according to any one of the first to third aspects, the outer peripheral surface of the varistor portion is bonded to the inner peripheral surface of the insulating tube in an adhesive state by an adhesive. It is characterized by sealing the space.
That is, in this surge absorber, since the outer peripheral surface of the varistor part is bonded to the inner peripheral surface of the insulating tube in an intimate contact state with an adhesive to seal the discharge space, the gap between the varistor part and the insulating tube is interposed. Can be prevented from discharging.

The present invention has the following effects.
That is, according to the surge absorber according to the present invention, since at least one of the pair of end electrodes includes a varistor portion formed of a varistor material at least on the inner surface side, a composite of a varistor function and a surge absorbing function is provided. The function can be built in in a compact manner, and can be easily assembled and manufactured at low cost.

It is sectional drawing which shows 1st Embodiment of the surge absorber which concerns on this invention. In 1st Embodiment, it is an equivalent circuit schematic which shows a surge absorber. It is sectional drawing which shows 2nd Embodiment of the surge absorber which concerns on this invention. It is sectional drawing which shows 3rd Embodiment of the surge absorber which concerns on this invention.

  Hereinafter, a first embodiment of a surge absorber according to the present invention will be described with reference to FIGS. 1 and 2. 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 FIG. 1, the surge absorber 1 according to the first embodiment is a chip-type surge absorber having a rectangular parallelepiped shape as a whole, and includes a pair of end electrodes 2 and a pair of end electrodes 2 arranged to face each other. The insulating tube 3 is disposed at both ends and sealed inside to form the discharge space S, and the pair of end electrodes 2 includes a pair of varistor portions 4 formed of a varistor material on the inner surface side. .

  The insulating tube 3 is formed of a ceramic material such as alumina in the shape of a rectangular cylinder having a hollow outer shape and a hollow cylindrical shape. For example, Mo-W metallization is performed on both end faces of the insulating tube 3, and then a metallization layer is formed by Ni plating. A trigger portion such as a carbon trigger formed of a conductive material such as a carbon material may be provided on the inner peripheral surface of the insulating tube 3 and in the middle portion between the pair of end electrodes 2. The insulating tube 3 is preferably a ceramic material, but a glass tube such as lead glass may be adopted.

The pair of end electrodes 2 are installed on the inner surfaces of the pair of end electrode main bodies 2a that are bonded to both end surfaces of the insulating tube 3 to close the open ends, and the inner surfaces of the pair of end electrode main bodies 2a. And a pair of the varistor portions 4 arranged on the surface.
The end electrode body 2a is formed of an alloy of Fe and Ni, Kovar, or the like, and is sealed to both ends of the insulating tube 3 with a brazing material made of Ag-Cu.
The discharge control gas is sealed in the discharge space S. This discharge control gas is an inert gas such as He, Ar, Ne, Xe, SF ₆ , CO ₂ , C ₃ F ₈ , C ₂ F ₆ , CF ₄ , H _2, or a mixed gas thereof.

The varistor portion 4 is a varistor element formed in a plate shape or a chip shape that can be fitted into the insulating tube 3 with, for example, a ZnO-based material, and the outer electrode 5 is made of Ag or the like on the end electrode body 2a side surface. Is formed. The outer electrode 5 and the end electrode body 2a are bonded with a brazing material.
Further, the outer peripheral surface of the varistor portion 4 is brought into close contact with the inner peripheral surface of the insulating tube 3 with an adhesive such as a ceramic adhesive (for example, a water glass adhesive such as Aron Ceramic (registered trademark) manufactured by Toa Gosei). It joins and discharge space S is sealed. That is, the gap between the outer peripheral surface of the varistor part 4 and the inner peripheral surface of the insulating tube 3 is filled and sealed with an adhesive.

As shown in FIG. 2, the surge absorber 1 is an equivalent circuit in which a pair of varistor portions 4 are electrically connected in series as discharge electrodes on both sides of a surge absorber function portion 6 that functions as a surge absorbing element. .
That is, in this surge absorber 1, when an overvoltage or overcurrent enters, the discharge first develops after trigger discharge and discharge is performed between the pair of varistor portions 4 that are discharge electrodes, thereby absorbing the surge. Then, after the discharge of the surge is finished, a continuity phenomenon in which a current continues to flow due to the power supply voltage of the circuit is prevented by the varistor characteristics of the pair of varistor portions 4 connected in series to the surge absorber function portion 6. The

  As described above, in the surge absorber 1 according to the present embodiment, at least one of the pair of end electrodes 2 includes the varistor portion 4 formed of the varistor material on at least the inner surface side. The absorber function unit 6 is electrically connected in series and built in, and faces the discharge space S and functions as a part of the discharge electrode of the surge absorbing element. Therefore, the surge absorber 1 can incorporate a composite function of the varistor function and the surge absorption function in a compact manner. Further, it is possible to easily assemble the varistor part 4 as at least a part of the end electrode 2 in the insulating tube 3, and it can be manufactured inexpensively and in a small size.

Furthermore, since the outer peripheral surface of the varistor part 4 is joined to the inner peripheral surface of the insulating tube 3 in an adhesive state by an adhesive to seal the discharge space S, the gap between the varistor unit 4 and the insulating tube 3 is interposed. It is possible to prevent discharge.
In addition, since the discharge control gas is sealed in the discharge space, the discharge characteristics can be adjusted by selecting the discharge control gas.

  Next, a second embodiment and a third embodiment of the surge absorber according to the present invention will be described below with reference to FIGS. In the following description of each embodiment, the same constituent elements 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 inner surfaces (opposing surfaces) of the pair of varistor portions 4 are varistor material surfaces, whereas the surge absorber 21 of the second embodiment. Then, as shown in FIG. 3, a metal electrode film 25 is formed on the inner surface of the varistor portion 4. The metal electrode film 25 is formed of, for example, a Ni film or an Au film.
Therefore, in the surge absorber 21 of the second embodiment, the metal electrode film 25 is formed on the inner surface of the varistor part 4, and therefore the discharge characteristics can be adjusted by the metal electrode film 25 having higher conductivity than the varistor material. .

  Next, the difference between the third embodiment and the second embodiment is that, in the second embodiment, the pair of varistor portions 4 are incorporated in the insulating tube 3 while being bonded to the end electrodes 2. In the surge absorber 31 of the second embodiment, as shown in FIG. 3, a cylindrical spacer 33 inscribed in the inner peripheral surface of the insulating tube 3 is interposed between the pair of varistor portions 4, and in this state The varistor part 4 is bonded to the end electrode 2.

That is, in the third embodiment, first, the spacer 33 is inserted into the insulating tube 3, and a pair of varistor portions 4 are inserted from both ends. At this time, a ceramic adhesive is applied to the outer peripheral surface of the varistor portion 4. Next, both ends of the insulating tube 3 are closed with a pair of end electrodes 2 coated with brazing material on the inner surface, and the outer peripheral surface of the varistor portion 4 and the insulating tube 3 are bonded by heating in this state. At the same time, the surge absorber 31 is produced by bonding the outer electrode 5 and the end electrode body 2a.
The spacer 33 is an insulator and is made of the same material as that of the insulating tube 3.

  As described above, in the surge absorber 31 according to the third embodiment, the cylindrical spacer 33 inscribed in the inner peripheral surface of the insulating tube 3 is interposed between the pair of opposed varistor portions 4. Can be adjusted by the spacer 33, and positioning and incorporation of the varistor portion 4 are facilitated.

  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 embodiments, in order to obtain high sealing performance, both end surfaces of the insulating tube are sealed with a pair of end electrode bodies, and the varistor portion is installed on the inner surface of the end electrode body. The entire end electrode may be formed of a varistor material without using the partial electrode body. In this case, since the entire end electrode is a varistor part, an outer electrode is formed on the outer surface of the varistor part with Ag or the like for electrical connection with the outside, and at the varistor part to ensure sealing performance. It is necessary to adhere both ends of the insulating tube in close contact with a ceramic adhesive or the like.
Moreover, in each said embodiment, although the varistor part is provided in the inner surface of both of a pair of end part electrode, you may provide a varistor part only in one side of a pair of end part electrode.

  DESCRIPTION OF SYMBOLS 1, 21, 31 ... Surge absorber, 2 ... End electrode, 2a ... End electrode main body, 3 ... Insulating tube, 4 ... Varistor part, 25 ... Metal electrode film, 33 ... Spacer, S ... Discharge space

Claims (4)

A pair of end electrodes disposed opposite each other;
An insulating tube in which the pair of end electrodes are arranged at both ends and the inside is sealed to form a discharge space;
A surge absorber, wherein at least one of the pair of end electrodes includes a varistor portion formed of a varistor material at least on the inner surface side. The surge absorber according to claim 1,
A surge absorber, wherein a metal electrode film is formed on an inner surface of the varistor portion. The surge absorber according to claim 1 or 2,
A pair of end electrode bodies that are bonded to both end faces of the insulating tube to close the open ends; and
A pair of the varistor portions installed on the inner surfaces of the pair of end electrode bodies and disposed in the insulating tube;
A surge absorber characterized in that a cylindrical spacer inscribed in the inner peripheral surface of the insulating tube is interposed between the varistor portions. In the surge absorber according to any one of claims 1 to 3,
A surge absorber, wherein an outer peripheral surface of the varistor portion is bonded to an inner peripheral surface of the insulating tube in an intimate contact state with an adhesive to seal the discharge space.

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