JP2020004577A - Surge protection element - Google Patents

Abstract

To provide a surge protection element, which can be manufactured at a low cost, capable of suppressing short circuit due to adhesion of metal components scattered by arc discharge.SOLUTION: The surge protection element includes: an insulating tube 2; a pair of sealing electrodes 3 for closing both end openings of the insulating tube and sealing a discharge control gas therein; and an interval adjusting member 4 for defining an interval between the pair of sealing electrodes, by being sandwiched between opposing surfaces of the pair of sealing electrodes in a state where a part is left open as a discharge space S between the pair of sealing electrodes. The interval adjusting member is composed of a plurality of thin plate members 4a and 4b, overlapped in an axial direction of the insulating tube, at least one of which is formed of an insulating material. In at least one of the plurality of thin plate members, a peripheral edge portion in contact with the discharge space has a different shape from other overlapping thin plate members. A step portion D is formed at a peripheral edge portion of the interval adjusting member that is in contact with the discharge space.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a surge protection element used to protect various devices from a surge generated by a lightning strike or the like and prevent an accident from occurring.

  Telecommunications equipment such as telephones, facsimiles, modems, etc., connected to communication lines, power lines, antennas or image display drive circuits such as CRTs, liquid crystal televisions and plasma televisions, abnormal voltages such as lightning surges and static electricity A surge protection element is connected to a part which is easily affected by electric shock due to (surge voltage) in order to prevent an electronic device or a printed circuit board on which the device is mounted from being damaged by heat or fire due to abnormal voltage.

  2. Description of the Related Art Conventionally, for example, Patent Literature 1 describes a microgap type surge protection element in which a member covered with conductive coating is sandwiched between metal members facing each other in a glass tube. This micro-gap type surge protection element has a structure in which a slit (gap) of several μm to several tens μm is provided at the center of a conductively coated member, and no current flows between opposing metal members below a specified voltage. . When the voltage exceeds the set voltage, an arc discharge occurs between the slits, and a current flows between the opposed metal members.

This surge protection element is a device that utilizes the shape changeability of a glass tube due to softening of glass and the characteristics of joining with a metal, and has excellent mass productivity, and is therefore used in a wide range of fields.
In addition, Patent Document 2 discloses a surge protection device including a cylindrical body formed of ceramics or glass, and a pair of electrodes facing each other with a predetermined space therebetween by interposing an electrically insulating ring-shaped spacer. An element is described. A surge protection element in which the opposing electrode is sealed with a ceramic cylindrical body such as alumina as in such a surge protection element is called an arrester.

JP-B-63-57918 JP-A-63-318085

The following problems remain in the above-described conventional technology.
In other words, the glass-coated microgap surge protection element has good bonding properties between glass and metal members, and has excellent reliability such as gas sealing properties and air and moisture blocking properties. However, since the slit width constituting the microgap is small and the thickness of the conductive coating forming the periphery of the microgap is as thin as several tens of μm, the surge withstand capability is limited to about 1500A. In addition, a film forming step of a conductive coating and a laser processing step for forming a micro gap are required, so that the steps become complicated, the production takes time, and the cost is increased.
On the other hand, the arrester-type surge protection element has a withstand capacity of 2000A for a product with a diameter of 5 mm and a resistance of 5000 A for a product with a diameter of 8 mm, and has a surge withstand characteristic higher than that of a glass-coated micro gap type surge protector. I have. Such an arrester-type surge protection element is used for infrastructure equipment such as large home appliances, solar power generation, and water and sewage that require high reliability. The arrester-type surge protection element requires an expensive bonding agent (silver-based brazing material) and an alumina cylindrical member that is more expensive than a glass cylindrical member in joining metal and ceramics. In addition, very high technology is required for joining ceramics and metal parts, and an auxiliary electrode material (such as graphite) is provided inside the electrode, and a dielectric material is applied to the surface of the counter electrode for the purpose of protecting the electrode and promoting discharge. And the production process is complicated. Therefore, the manufacturing cost tends to be significantly higher than that of the glass-coated micro gap type surge protection element. In particular, in the case of using for countermeasures against static electricity, it is necessary to separate electrodes facing each other at a very small interval such as the above-mentioned micro gap, and it has been difficult to set the gap with high accuracy.
Further, there is a problem in that the metal constituting the electrode portion is melted and scattered by the arc discharge, and the metal component adheres to the inner surface of the insulating tube, thereby deteriorating the insulating property between the pair of sealing electrodes. In particular, if a large amount of metal component adheres to the inner surface of the insulating tube, a current-carrying circuit may be formed on the inner peripheral surface of the insulating tube, causing a short circuit.In such a case, the life of the surge protection element is determined. There was an inconvenience. In the surge protection element described in Patent Document 2, the metal component does not adhere to the inner peripheral surface of the insulating tube because the ring spacer is interposed, but the metal component adheres to the inner peripheral surface of the ring spacer. As a result, there was a risk that a short circuit would occur.

  The present invention has been made in view of the above-described problems, and has an object to provide a surge protection element that can be manufactured at low cost and that can suppress a short circuit due to adhesion of a metal component scattered by arc discharge. .

  The present invention has the following features to attain the object mentioned above. That is, a surge protection element according to a first aspect of the present invention includes an insulating tube, a pair of sealing electrodes for closing both ends of the insulating tube to seal a discharge control gas therein, and a pair of the sealing electrodes. A gap adjusting member that is sandwiched between opposing surfaces of the pair of sealing electrodes and defines a gap between the pair of sealing electrodes in a state where a part of the sealing electrodes is left as a discharge space, and the gap adjusting member Is composed of a plurality of thin plate members that are stacked in the axial direction of the insulating tube and at least one of which is formed of an insulating material, and in at least one of the plurality of thin plate members, a peripheral edge portion that contacts the discharge space is provided. The gap adjusting member has a shape different from that of the other thin plate member, and a step portion is formed on a peripheral edge portion of the gap adjusting member that is in contact with the discharge space.

In this surge protection element, the gap adjusting member is composed of a plurality of thin plate members that are overlapped in the axial direction of the insulating tube and at least one of the thin plate members is formed of an insulating material. The peripheral portion in contact with the space has a shape different from that of the other thin sheet member that overlaps, and a step portion is formed in the peripheral portion of the gap adjusting member that is in contact with the discharge space. Even if it adheres to the peripheral portion of, it is difficult to form an energizing circuit by the adhered metal due to the presence of the stepped portion, and it is possible to suppress a short circuit.
In addition, the step portion increases the creeping distance between the sealing electrodes via the peripheral portion of the gap adjusting member, and in this respect, it is difficult to form an energizing circuit using the adhered metal. Although it is difficult to form a step portion having a large step by processing the peripheral portion of the conventional integral spacer, the surge protection element of the present invention has a step difference by stacking a plurality of thin plate members. It is easy to obtain a large step portion.
Furthermore, the gap between the pair of sealing electrodes can be easily adjusted by the number of the thin plate members, which is easy to manufacture and low in cost, and is small in size by employing an arrester-type counter electrode. However, high durability and high reliability can be obtained.

A surge protection element according to a second invention is the surge protection device according to the first invention, wherein the insulating tube has a cylindrical shape, and a plurality of the thin plate members have an outer peripheral edge in contact with an inner peripheral surface of the insulating tube. The stepped portion is formed in an annular shape, wherein at least one of the plurality of thin plate members has an inner diameter different from the other thin plate members, and the step portion is formed on an inner peripheral surface of the gap adjusting member.
That is, in this surge protection element, since the inner diameter of at least one of the plurality of annular thin plate members is different from the other thin plate members, a stepped portion is formed on the inner peripheral surface of the interval adjusting member. Positioning can be performed by the member being in the form of an annular shape that comes into contact with the inner peripheral surface of the insulating tube, and a discharge space surrounded by a step can be secured inside the gap adjusting member.

In the surge protection element according to a third aspect, in the first aspect, the insulating tube has a cylindrical shape, the interval adjusting member is disposed at a central portion of the facing surface, and a plurality of the thin plate members are provided. An outer diameter of at least one of the plurality of thin plate members is different from other thin plate members, and the step portion is formed on an outer peripheral surface of the interval adjusting member. It is characterized by having.
That is, in this surge protection element, the plurality of thin plate members in the central portion of the opposing surface are formed in a disk shape having a common axis, and the outer diameter of at least one of the plurality of thin plate members is different from the other thin plate members. Since the step portion is formed on the outer peripheral surface of the gap adjusting member, a discharge space can be secured around the step portion of the gap adjusting member. In addition, the gap adjusting member disposed at the center portion of the facing surface serves as a barrier, so that it is possible to suppress the metal component generated by the arc discharge from scattering to the discharge space on the opposite side in the radial direction of the insulating tube.

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 gap adjusting member is formed of an insulating thin plate as the thin plate member formed of an insulating material, and metal. And a functional thin plate as the thin plate member.
That is, in this surge protection element, the interval adjusting member includes an insulating thin plate that is a thin plate member formed of an insulating material, and a functional thin plate that is a thin plate member formed of a conductive material. Insulation between the sealing electrodes is ensured by the insulating thin plate, and discharge characteristics can be adjusted by the functional thin plate having conductivity.

A surge protection element according to a fifth invention is characterized in that, in the fourth invention, the functional thin plate is formed of a metal.
That is, in this surge protection element, since the functional thin plate is formed of a metal, the scattered metal component easily adheres to the functional thin metal plate, and it is possible to suppress the metal component from adhering to the insulating thin plate.

A surge protection element according to a sixth aspect is characterized in that, in the fourth aspect, the functional thin plate is formed of an ion source material.
That is, in this surge protection element, since the functional thin plate is formed of the ion source material, it can be a functional thin plate having a discharge auxiliary function as a trigger of arc discharge.

A surge protection element according to a seventh aspect is characterized in that, in any one of the first to sixth aspects, the insulating tube is a glass tube.
That is, in this surge protection element, since the insulating tube is a glass tube, it can be manufactured at a lower cost than ceramics such as alumina, and at the same time, has excellent reliability due to high gas sealing property and moisture blocking property. Can be

According to the present invention, the following effects can be obtained.
That is, according to the surge protection element of the present invention, the interval adjusting member is constituted by a plurality of thin plate members which are overlapped in the axial direction of the insulating tube and at least one of which is formed of an insulating material. In at least one of them, the peripheral portion in contact with the discharge space has a shape different from that of the other thin sheet member overlapping, and a step portion is formed in the peripheral portion of the gap adjusting member in contact with the discharge space. While being possible, it is possible to suppress a short circuit due to the adhesion of the metal component scattered by the arc discharge.
Therefore, the surge protection device according to the present invention is suitable for a power supply circuit unit and a communication circuit unit of an electric device that requires a small, inexpensive, and highly reliable product. In particular, the surge protection element of the present invention is suitable for a wide range of applications including measures against static electricity for mounting on a substrate.

It is an axial sectional view showing a 1st embodiment of a surge protection element concerning the present invention. FIG. 2 is an exploded perspective view showing the surge protection element in the first embodiment. It is an axial sectional view showing a 2nd embodiment of a surge protection element concerning the present invention. It is an exploded perspective view showing a surge protection element in a 2nd embodiment. It is an axial sectional view showing a 3rd embodiment of a surge protection element concerning the present invention. It is an axial sectional view showing a 4th embodiment of a surge protection element concerning the present invention.

  Hereinafter, a first embodiment of a surge protection device according to the present invention will be described with reference to FIGS. In each drawing used in the following description, the scale is appropriately changed in order to make each member a recognizable or easily recognizable size.

As shown in FIGS. 1 and 2, the surge protection element 1 of the present embodiment includes an insulating tube 2 and a pair of sealing members for closing the openings at both ends of the insulating tube 2 to seal the discharge control gas therein. An interval defining the interval between the pair of sealing electrodes 3 sandwiched between the opposing surfaces of the pair of sealing electrodes 3 in a state where a part thereof is provided as a discharge space S between the stop electrode 3 and the pair of sealing electrodes 3. And an adjusting member 4.
The interval adjusting member 4 is composed of a plurality of thin plate members 4a and 4b which are stacked in the axial direction of the insulating tube 2 and at least one of which is formed of an insulating material, and at least one of the plurality of thin plate members 4a and 4b. The peripheral portion in contact with the discharge space S has a shape different from that of the other thin plate members 4a and 4b that overlap, and a step portion D is formed in the peripheral portion of the gap adjusting member 4 in contact with the discharge space.

The insulating tube 2 has a cylindrical shape and is formed of a glass tube of lead glass or the like. Note that the insulating tube 2 is preferably formed of a glass tube which is inexpensive and has excellent sealing properties, but may be formed of a crystalline ceramic material such as alumina.
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 , atmosphere, etc., and a mixed gas thereof are employed.

The sealing electrode 3 is formed of, for example, a dumet wire, a 42 alloy (Fe: 58 wt%, Ni: 42 wt%), Cu, or the like in a columnar shape.
In the present embodiment, the pair of sealing electrodes 3 enter the inside of the insulating tube 2 to close the openings at both ends.
The base end of the lead wire 5 projecting outward is embedded in each sealing electrode 3.

The interval adjusting member 4 is composed of a plurality of thin plate members 4a and 4b formed of a thin plate or a film of an insulating material such as glass, ceramics, paper, and resin.
The plurality of thin plate members 4a and 4b are formed in an annular shape in which the outer peripheral edge is in contact with the inner peripheral surface of the insulating tube 2.
The inner diameter of the thin plate member 4a among the plurality of thin plate members 4a and 4b is different from the other thin plate members 4b, and a step portion D is formed on the inner peripheral surface of the interval adjusting member 4.

That is, the interval adjusting member 4 of the present embodiment is composed of four thin plate members 4a and 4b in which thin plate members 4a having a small inner diameter and thin plate members 4b having a larger inner diameter than the thin plate member 4a are alternately stacked in the axial direction. It is configured.
Since the annular thin plate members 4a and 4b having different inner diameters are alternately stacked in this manner, the inner peripheral edge of the thin plate member 4a having a smaller inner diameter is inward of the thin plate member 4b having a larger inner diameter. In this state, the plurality of steps D are formed on the inner peripheral surface of the gap adjusting member 4. A substantially disk-shaped discharge space S is formed inside the gap adjusting member 4.

The thickness and the number of the plurality of thin plate members 4a and 4b to be stacked are set such that the thickness of the gap adjusting member 4 is, for example, 200 to 800 μm. That is, the thickness of the gap adjusting member 4 becomes the distance between the sealing electrodes.
Further, it is preferable that the installation area of the space adjusting member 4 with respect to the facing surface of the sealing electrode 3 be set to 50% or less. That is, the reason why the installation area of the gap adjusting member 4 is set within 50% is that if it exceeds 50%, a sufficient discharge space S cannot be secured.

  As described above, in the surge protection element 1 according to the present embodiment, the gap adjusting member 4 is constituted by the plurality of thin plate members 4a and 4b, which are stacked in the axial direction of the insulating tube 2 and at least one of which is formed of an insulating material. In at least one of the plurality of thin plate members 4a and 4b, a peripheral portion in contact with the discharge space S has a shape different from that of another overlapping thin plate member, and a step portion is formed in the peripheral portion of the gap adjusting member 4 in contact with the discharge space S. Since D is formed, even if the metal component scattered by the arc discharge adheres to the peripheral portion of the gap adjusting member 4, the stepped portion D makes it difficult to form an energizing circuit by the adhered metal, resulting in a short circuit. Can be suppressed.

In addition, the step portion D increases the creeping distance between the sealing electrodes 3 via the peripheral portion of the gap adjusting member 4, and in this respect, it is difficult to form a current-carrying circuit using the adhered metal.
It is difficult to form a step portion having a large step by processing the peripheral portion of the conventional integral spacer. However, in the surge protection element 1 of the present embodiment, a plurality of thin plate members 4a having different inner diameters are formed. , 4b, it is easy to obtain a step portion D having a large step.

  Further, since the inner diameter of at least one of the plurality of annular thin plate members 4a, 4b is different from the other thin plate members 4a, 4b, the step portion D is formed on the inner peripheral surface of the interval adjusting member 4. Since the thin plate members 4a and 4b are in an annular shape in contact with the inner peripheral surface of the insulating tube 2, positioning can be performed, and a discharge space S surrounded by a step D is secured inside the gap adjusting member 4. can do.

In addition, the gap between the pair of sealing electrodes 3 can be easily adjusted by the number of the thin plate members 4a and 4b, so that the manufacturing is easy and the cost is low, and the arrester-type counter electrode is adopted. In addition, high durability and high reliability can be obtained while being small.
In particular, since the insulating tube 2 is a glass tube, it can be manufactured at a lower cost than ceramics such as alumina, and high reliability can be obtained due to a high gas sealing property and a barrier property against moisture and the like.

  Next, second to fourth embodiments of the surge protection element according to the present invention will be described below with reference to FIGS. In the following description of each embodiment, the same components described in the above embodiment will be denoted by the same reference numerals, and description thereof will be omitted.

The difference between the second embodiment and the first embodiment is that, in the first embodiment, the interval adjusting member 4 is configured by stacking a plurality of annular thin plate members 4a and 4b. As shown in FIGS. 3 and 4, the surge protection element 21 according to the embodiment is configured such that a plurality of disc-shaped thin plate members 24 a and 24 b are overlapped to form the interval adjustment member 24.
That is, in the second embodiment, the interval adjusting member 34 is disposed at the center of the opposing surface of the sealing electrode 3, and the plurality of thin plate members 24a and 24b are formed in a disk shape having a common axis. .

The outer diameter of at least one of the plurality of thin plate members 24a, 24b is different from the other thin plate members 24a, 24b, and a step portion D is formed on the outer peripheral surface of the interval adjusting member 24.
In the second embodiment, the interval adjusting member 24 is composed of four thin plate members 24a, in which thin plate members 24a having a small outer diameter and thin plate members 24b having a larger outer diameter than the thin plate member 24a are alternately stacked in the axial direction. 24b.
Since the disk-shaped thin plate members 24a and 24b having different outer diameters are alternately stacked in this way, the outer peripheral edge of the thin plate member 24b having a larger outer diameter is arranged outward with respect to the thin plate member 24a having a smaller outer diameter. Are projected outward, and a plurality of steps D are formed on the outer peripheral surface of the gap adjusting member 24. A substantially annular discharge space S is formed outside the gap adjusting member 24.

  As described above, in the surge protection element 21 according to the second embodiment, the plurality of thin plate members 24a and 24b at the central portion of the facing surface of the sealing electrode 3 are formed in a disk shape having a common axis, and the plurality of thin plate members 24a are formed. , 24b is different from the other thin plate members 24a, 24b in that the step D is formed on the outer peripheral surface of the gap adjusting member 24. , A discharge space S can be secured. In addition, the gap adjusting member 24 disposed in the central portion of the facing surface serves as a barrier, so that it is possible to suppress the metal component generated by the arc discharge from scattering to the discharge space S on the opposite side in the radial direction of the insulating tube 2.

  Next, the difference between the third embodiment and the first embodiment is that in the first embodiment, the thin plate members 4a and 4b are all formed of an insulating material, whereas the surge protection of the third embodiment is different. In the element 31, as shown in FIG. 5, the interval adjusting member 34 includes insulating thin plates 34a and 34b, which are thin members formed of an insulating material, and functional thin plates 34c, which are thin members formed of metal. This is the point that has.

In particular, in the third embodiment, the functional thin plate 34c is formed of metal.
The functional thin plate 34c is made of, for example, the same 42 alloy or Cu as the sealing electrode 3 and made of metal.
The functional thin plate 34c is preferably set to protrude inward, and has an inner diameter smaller than that of the upper and lower insulating thin plates 34b.

As described above, in the surge protection element 31 of the third embodiment, the gap adjusting members 34 are the insulating thin plates 34a and 34b, which are the thin plate members formed of the insulating material, and the thin plate members formed of the conductive material. Since the functional thin plate 34c is provided, insulation between the sealing electrodes 3 can be ensured by the insulating thin plates 34a and 34b, and the discharge characteristics can be adjusted by the conductive functional thin plate 34c. .
In particular, in the third embodiment, since the functional thin plate 34c is formed of metal, the scattered metal component is more likely to adhere to the metallic functional thin plate 34c and to adhere to the insulating thin plates 34a and 34b. It can be suppressed.

Next, the difference between the fourth embodiment and the third embodiment is that, in the third embodiment, the metal functional thin plate 34c is employed, whereas in the surge protection element 41 of the fourth embodiment, As shown in FIG. 6, the functional thin plate 44c of the gap adjusting member 44 is formed of an ion source material.
That is, the functional thin plate 44c of the fourth embodiment is an annular plate-shaped discharge auxiliary portion made of, for example, a carbon material that is an ion source material and has a higher electron emission ability than the sealing electrode 3. is there.

In the surge protection element 41, when an overvoltage or an overcurrent enters, first, an initial discharge is performed between the functional thin plate 44c serving as a discharge auxiliary portion and the sealing electrode 3, and further discharge is triggered by the initial discharge. As it progresses, an arc discharge is performed from one sealing electrode 3 to the other sealing electrode 3.
Thus, in the surge protection element 41 of the fourth embodiment, since the functional thin plate 44c is formed of the ion source material, it can be a functional thin plate having a discharge auxiliary function as a trigger of arc discharge. .

  Note that the technical scope of the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention.

  1, 21, 31, 41: surge protection element, 2: insulating tube, 3: sealing electrode, 4, 24, 34, 44: gap adjusting member, 4a, 4b: thin plate member, 34a, 34b: insulating thin plate , 34c, 44c: functional thin plate, D: stepped portion, S: discharge space

Claims (7)

An insulating tube;
A pair of sealing electrodes for closing the opening at both ends of the insulating tube and sealing the discharge control gas inside,
A gap adjusting member that is sandwiched between opposing surfaces of the pair of sealing electrodes in a state where a part thereof is left as a discharge space between the pair of sealing electrodes, and defines an interval between the pair of sealing electrodes,
The interval adjusting member is constituted by a plurality of thin plate members that are stacked in the axial direction of the insulating tube and at least one of which is formed of an insulating material,
In at least one of the plurality of thin plate members, a peripheral portion in contact with the discharge space has a shape different from that of the other thin plate members that overlap,
A surge protection element, wherein a step portion is formed on a peripheral edge portion of the gap adjusting member that contacts the discharge space. The surge protection device according to claim 1,
The insulating tube is cylindrical,
A plurality of the thin plate members are formed in an annular shape in which an outer peripheral edge is in contact with an inner peripheral surface of the insulating tube,
At least one inner diameter of the plurality of thin plate members is different from other thin plate members,
The surge protection element, wherein the step portion is formed on an inner peripheral surface of the gap adjusting member. The surge protection device according to claim 1,
The insulating tube is cylindrical,
The interval adjusting member is disposed at a central portion of the facing surface,
A plurality of the thin plate members are formed in a disk shape having a common axis.
At least one outer diameter of the plurality of thin plate members is different from other thin plate members,
The surge protection element, wherein the step portion is formed on an outer peripheral surface of the gap adjusting member. The surge protection device according to any one of claims 1 to 3,
The gap adjusting member, an insulating thin plate that is the insulating thin plate member,
And a functional thin plate which is the thin plate member formed of a conductive material. The surge protection device according to claim 4,
The said functional thin plate is formed of metal, The surge protective element characterized by the above-mentioned. The surge protection device according to claim 4,
The surge protective element, wherein the functional thin plate is formed of an ion source material. The surge protection device according to any one of claims 1 to 6,
2. The surge protection device according to claim 1, wherein the insulating tube is a glass tube.

Images