Surge protection element

Abstract

This invention provides a surge protection element capable of mitigating damage caused by surges and suppressing fluctuations in discharge initiation voltage. The surge protection element of this invention comprises: an insulating tube (2); a pair of sealing electrodes (3) sealing the openings at both ends of the insulating tube and sealing the discharge control gas inside; a pair of discharge electrodes (4) having their bases in contact with the inner surfaces of the sealing electrodes and their ends protruding into the insulating tube and facing each other; and an insulating member (5) being held and housed within the insulating tube by the end faces of the pair of discharge electrodes, the insulating member being cylindrical with an axis orthogonal to the axis of the insulating tube, and having a groove (5a) extending along its own axis formed on the exposed outer peripheral surface between the pair of discharge electrodes.

Description

Technical Field

[0001] This invention relates to a surge protection element for protecting various devices from surges caused by lightning strikes, etc., and preventing accidents before they occur. Background Technology

[0002] Surge protection components are connected to parts of electronic devices such as telephones, fax machines, and modems that are connected to communication lines, power lines, antennas, or CRT drive circuits, which are susceptible to electric shocks caused by abnormal voltages (surge voltages) such as lightning surges or static electricity. These components are designed to prevent damage to the electronic devices or the printed circuit boards on which the devices are mounted due to abnormal voltages.

[0003] Previously, as a surge protection element, a surge absorber was known, which used a pair of sealing electrodes to seal a discharge element inside a glass tube. The discharge element consisted of a ceramic insulator with one or more discharge gaps (micro-gap) separated from the center by a conductive film formed on its surface, and a pair of cap-shaped electrodes (discharge electrodes) disposed at both ends of the insulator (for example, see Patent Document 1).

[0004] In this surge protection element, a conductive film is formed as an electrode film. The thin conductive film locally increases the surrounding electric field, thereby advantageously acting on the surge response voltage.

[0005] Patent Document 1: Japanese Patent Application Publication No. 8-153565

[0006] The following issues remain in the aforementioned prior technologies.

[0007] In the aforementioned conventional surge protection components, a conductive film of several to tens of μm is formed using film-forming techniques such as thick film printing or sputtering to serve as the electrode film. However, due to its thin thickness, the conductive film may melt and scatter under high-intensity surges or repeated surges, thus failing to maintain its function.

[0008] Furthermore, the following problem exists: conductive debris such as metal that scatters from the discharge electrode and adheres to the outer peripheral surface of the insulator will significantly disrupt the electric field distribution, causing the discharge initiation voltage Vs to fluctuate and making it impossible to maintain a stable discharge initiation voltage Vs.

[0009] The present invention was made in view of the aforementioned problems, and its object is to provide a surge protection element that can mitigate damage caused by surges and suppress fluctuations in discharge initiation voltage. Summary of the Invention

[0010] To address the aforementioned problem, the present invention employs the following structure. Specifically, the surge protection element of the first invention is characterized by comprising: an insulating tube; a pair of sealing electrodes that seal the openings at both ends of the insulating tube and seal the interior with a discharge control gas; a pair of discharge electrodes, the base of which contacts the inner surface of the sealing electrodes and the ends of which protrude into the insulating tube and are opposite each other; and an insulating member that is held and housed within the insulating tube by the end faces of the pair of discharge electrodes, the insulating member being cylindrical with an axis orthogonal to the axis of the insulating tube, and having a groove extending along its own axis formed on the exposed outer peripheral surface between the pair of discharge electrodes.

[0011] In this surge protection element, the insulating component is cylindrical with an axis orthogonal to the axis of the insulating tube. A groove extending along its own axis is formed on the exposed outer peripheral surface between a pair of discharge electrodes. Therefore, even if conductive debris from the discharge electrodes, generated by surge discharge, adheres to the outer peripheral surface of the insulating component, it is less likely to adhere to the groove, thus being interrupted and separated by the groove. Consequently, the debris-laden areas are segmented and reduced in size, resulting in less disturbance in the electric field distribution and suppressing fluctuations in the discharge initiation voltage Vs after a surge life test. Furthermore, by using discharge electrodes as conductive components, compared to a thin conductive film, the heat capacity is increased and the thermal resistance is reduced, improving surge resistance and suppressing fluctuations in the discharge initiation voltage.

[0012] The surge protection element of the second invention is characterized in that, in the first invention, the insulating component has a plurality of said grooves.

[0013] In this surge protection element, the insulating component has multiple slots. Therefore, even if conductive debris adheres to the outer peripheral surface of the insulating component, the debris area will be further divided and separated into multiple slots, and each debris area will become smaller.

[0014] The surge protection element of the third invention is characterized in that, in the second invention, the insulating component is formed as a cross-sectional gear having a plurality of said slots at equal intervals in the circumferential direction.

[0015] In this surge protection element, the insulating component is formed as a cross-section gear with multiple slots at equal intervals in the circumferential direction. Therefore, when the insulating component is inserted between a pair of discharge electrodes inside the insulating tube, multiple slots are easily exposed between the pair of discharge electrodes, thus eliminating the need for positioning during assembly.

[0016] The surge protection element of the fourth invention is characterized in that, in the third invention, the insulating component is formed as a cross-sectional gear having eight slots at equal intervals in the circumferential direction.

[0017] In this surge protection element, the insulating component is formed as a gear-shaped cross-section with eight equally spaced slots in the circumferential direction, thus having eight teeth on its outer circumferential surface. Two adjacent teeth of the eight teeth abut against the opposing discharge electrodes, thereby being stably disposed between a pair of discharge electrodes. Furthermore, by exposing three slots on each of the outer circumferential surface portions exposed on both sides between the pair of discharge electrodes, the scattering area can be segmented and separated into three parts.

[0018] The surge protection element of the fifth invention, in the first or second invention, is characterized in that the outer diameter of the insulating component is smaller than the outer diameter of the discharge electrode, and regions are formed on both sides of the insulating component where the end faces of the pair of discharge electrodes directly face each other.

[0019] In this surge protection element, the outer diameter of the insulating component is smaller than the outer diameter of the discharge electrode, and a pair of discharge electrodes are formed on both sides of the insulating component with their end faces directly facing each other. Therefore, a discharge path is formed on both sides of the insulating component, making it easy for the arc discharge to be conducted between the pair of discharge electrodes.

[0020] According to the present invention, the following effects are achieved.

[0021] That is, according to the surge protection element of the present invention, the insulating component is columnar with an axis orthogonal to the axis of the insulating tube, and a groove extending along its own axis is formed on the exposed outer peripheral surface between a pair of discharge electrodes. Therefore, the electric field distribution is less disordered, which can suppress the variation of the discharge initiation voltage Vs after the surge life test and improve the surge resistance.

[0022] Therefore, the surge protection element of the present invention can improve surge damage resistance and surge characteristic resistance. Attached Figure Description

[0023] Figure 1 This is a front view showing a partial cross-section of a surge protection element in one embodiment of the surge protection element involved in this invention.

[0024] Figure 2 This is an explanatory diagram showing the scattering area of ​​conductive flyers in the insulating component disposed between a pair of discharge electrodes in this embodiment.

[0025] Figure 3 This is a side view showing a partially cut-out surge protection element in this embodiment.

[0026] Figure 4 This is a perspective view showing the insulating component disposed between a pair of discharge electrodes in this embodiment.

[0027] Figure 5This is a graph showing the change of discharge initiation voltage Vs relative to the number of lifetime tests in embodiments of the surge protection element involved in this invention.

[0028] Figure 6 This is a graph showing the change of discharge initiation voltage Vs relative to the number of lifetime tests in a comparative example of the surge protection element involved in this invention.

[0029] Figure 7 These are images showing the outer peripheral surface of the insulating component after a life test in embodiments (a) and comparative examples (b) of the surge protection element involved in this invention. Detailed Implementation

[0030] The following is for reference. Figures 1 to 4 This paper describes one embodiment of the surge protection element according to the present invention. Furthermore, the scales in the accompanying drawings used in the following description have been appropriately altered to make the components appear as easily identifiable or recognizable sizes.

[0031] like Figures 1 to 4 As shown, the surge protection element 1 of this embodiment includes: an insulating tube 2; a pair of sealing electrodes 3 that close the openings at both ends of the insulating tube 2 and seal the discharge control gas inside; a pair of discharge electrodes 4 whose base ends contact the inner surface of the sealing electrodes 3 and whose ends protrude into the insulating tube 2 and are opposite each other; and an insulating component 5 that is held by the end faces 4a of the pair of discharge electrodes 4 and housed in the insulating tube 2.

[0032] like Figure 3 As shown, the insulating component 5 is columnar with an axis AX2 orthogonal to the axis AX1 of the insulating tube 2, and a groove 5a extending along its own axis AX2 is formed on the exposed outer peripheral surface between a pair of discharge electrodes 4.

[0033] Furthermore, the insulating component 5 has multiple grooves 5a.

[0034] Moreover, such as Figure 1 and Figure 2 As shown, the insulating component 5 is formed as a cross-section gear with a plurality of grooves 5a at equal intervals in the circumferential direction.

[0035] That is, the insulating component 5 is formed as a gear-shaped cross-section having eight slots 5a and eight teeth 5b at equal intervals in the circumferential direction.

[0036] The groove depth of the aforementioned groove 5a is preferably set within the range of 10% to 20% of the radius of the insulating component 5. In this embodiment, for the insulating component 5 with a radius of 1 mm, a groove 5a with a groove depth of 150 μm is used.

[0037] In addition, the outer diameter of the insulating component 5 is smaller than the outer diameter of the discharge electrode 4, and a region A1 is formed on both sides of the insulating component 5 where the end faces 4a of the discharge electrodes 4 directly face each other.

[0038] At the end of a pair of discharge electrodes 4, an annular protrusion 4b protruding in the axial direction is formed along the outer periphery.

[0039] Furthermore, the discharge electrode 4 is formed as a cylindrical part with a circular hole 4c centered on the axis AX1 at the end.

[0040] That is, at the end of the discharge electrode 4, an annular protrusion 4b is formed on the outer periphery of the hole 4c.

[0041] In this embodiment, the discharge electrode 4 is formed of copper, for example.

[0042] In addition, in this embodiment, one end of the lead wire 7 is connected to the outside of the sealing electrode 3 by welding, brazing, embedding, etc.

[0043] The aforementioned sealing electrode 3 is formed, for example, of a metal with a copper oxide coating on the surface of an Fe (iron)-Ni (nickel) alloy, and is in the shape of a disc or a cylinder.

[0044] For example, the sealing electrode 3 is made of Dummey wire.

[0045] The aforementioned insulating tube 2 is, for example, a glass tube made of lead glass or the like and formed into a generally cylindrical shape.

[0046] Furthermore, a pair of sealing electrodes 3 are embedded into the openings at both ends of the insulating tube 2, which is a glass tube, and are fused together by heat treatment, so that the insulating tube 2 is fixed in a tight-fitting state.

[0047] The discharge control gas sealed inside the insulating tube 2 is an inert gas, such as He, Ar, Ne, Xe, Kr, SF6, CO2, C3F8, C2F6, CF4, H2, atmosphere, and their mixtures.

[0048] The aforementioned insulating component 5 is formed of ceramic materials such as alumina, mullite, and corundum mullite. Furthermore, in this embodiment, the insulating component 5 is formed of alumina.

[0049] Thus, in the surge protection element 1 of this embodiment, the insulating component 5 is cylindrical with an axis AX2 orthogonal to the axis AX1 of the insulating tube 2, and a groove 5a extending along its own axis AX2 is formed on the exposed outer peripheral surface between the pair of discharge electrodes 4. Therefore, as Figure 2As shown in the right side, even if conductive debris from the discharge electrode 4, generated by surge discharge TB, scatters and adheres to the outer peripheral surface of the insulating component 5 as shown by arrow M1, it is not easy to adhere to the groove 5a, and thus it is separated and isolated by the groove 5a.

[0050] Therefore, the scattering region M with attached conductive debris is broken down and separated, resulting in smaller individual areas. This reduces the disorder in the electric field distribution and suppresses fluctuations in the discharge initiation voltage Vs after the surge life test. Furthermore, by employing the discharge electrode 4 as a conductive component, compared to a thin conductive film, the heat capacity is increased and the thermal resistance is reduced, thereby improving surge resistance and suppressing fluctuations in the discharge initiation voltage Vs.

[0051] Additionally, for example, in the case of using a surge protection element that is a cylindrical insulating component 15 (hereinafter also referred to as a circular insulator) without a slot 5a, such as Figure 2 As shown in the left part, conductive debris from the discharge electrode 4 scatters like arrow M2 and widely adheres to the outer peripheral surface of the insulating component 15, so the scattering area M is not broken and becomes larger, thus causing the electric field distribution to be easily disordered.

[0052] Furthermore, the insulating component 5 has multiple grooves 5a, so even if conductive debris adheres to the outer peripheral surface of the insulating component 5, the debris area M will be further divided and separated into multiple segments by the multiple grooves 5a, and each debris area M will become smaller.

[0053] Furthermore, the insulating component 5 is formed as a gear-shaped cross-section with a plurality of slots 5a at equal intervals in the circumferential direction. Therefore, when the insulating component 5 is inserted into the space between a pair of discharge electrodes 4 inside the insulating tube 2, the plurality of slots 5a are easily exposed between the pair of discharge electrodes 4, thus eliminating the need for positioning during assembly.

[0054] In particular, the insulating component 5 is formed in the shape of a gear with eight equally spaced grooves 5a in the circumferential direction, thus having eight teeth 5b on its outer circumferential surface. Two adjacent teeth 5b abut against the opposing discharge electrodes 4, thereby being stably disposed between a pair of discharge electrodes 4. Furthermore, by exposing three grooves 5a on each of the outer circumferential surface portions exposed on both sides between the pair of discharge electrodes 4, the scattering region M can be divided and separated into three parts.

[0055] Furthermore, the outer diameter of the insulating component 5 is smaller than the outer diameter of the discharge electrode 4, and a region A1 is formed on both sides of the insulating component 5 where the end faces 4a of a pair of discharge electrodes 4 directly face each other. Therefore, a discharge path is formed on both sides of the insulating component 5, making it easy for the arc discharge TB to be conducted between the pair of discharge electrodes 4.

[0056] Example

[0057] Regarding the surge protection element using the slotted insulating component (gear insulator) described in the above embodiment, as an embodiment of the present invention, a life test with repeated surges was conducted and the change in the discharge initiation voltage Vs during this test was investigated, and the results are presented below. Figure 5 (The image shows a gear insulator.)

[0058] In addition, as a comparative example, a life test was also conducted on a surge protection element using an insulating component without slots (circular insulator), and the change in the discharge initiation voltage Vs thereafter was investigated. The results are presented below. Figure 6 (The diagram shows a circular insulator).

[0059] These results show that in the comparative example using a circular insulator without slots, the discharge initiation voltage Vs decreased significantly after 100 lifetime tests. In contrast, in the embodiment of the present invention using a gear insulator with slots, the decrease in discharge initiation voltage Vs was suppressed even after 300 lifetime tests.

[0060] Furthermore, regarding the insulating component of the embodiment of the present invention, which was removed after 300 cycles of the aforementioned life test, an image of its outer peripheral surface is shown. Figure 7 (a). Furthermore, in the comparative example, an image of the outer peripheral surface of the removed insulating component is similarly shown. Figure 7 (b)

[0061] It can be seen that in the circular insulator of the above comparative example, the scattering area with conductive debris attached is extensive and distributed throughout the outer peripheral surface. In contrast, in the gear insulator of the embodiment of the present invention, the scattering area with conductive debris attached is divided into smaller areas by the slots on the outer peripheral surface.

[0062] Furthermore, the technical scope of the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

[0063] Explanation of reference numerals in the attached figures

[0064] 1-Surge protection components

[0065] 2-Insulating tube

[0066] 3-Sealed electrode

[0067] 4-Discharge electrode

[0068] 4a - End face of discharge electrode

[0069] 5-Insulating components

[0070] 5a-groove section

[0071] AX1 - Axis of the insulating tube

[0072] AX2 - Axis of insulating components

[0073] The area directly opposite the end face of the A1-discharge electrode

Claims

1. A surge protection element, characterized in that, have: Insulating tube; A pair of sealed electrodes, which seal the openings at both ends of the insulating tube and seal the discharge control gas inside; A pair of discharge electrodes, with their bases in contact with the inner surface of the sealing electrode and their ends protruding into the insulating tube and facing each other; and An insulating component is held and housed within the insulating tube by the end faces of the pair of discharge electrodes. The insulating component is cylindrical with an axis orthogonal to the axis of the insulating tube, and has a groove extending along its own axis formed on the exposed outer peripheral surface between the pair of discharge electrodes.

2. The surge protection element according to claim 1, characterized in that, The insulating component has a plurality of the grooves.

3. The surge protection element according to claim 2, characterized in that, The insulating component is formed as a cross-section gear with a plurality of slots spaced at equal intervals in the circumferential direction.

4. The surge protection element according to claim 3, characterized in that, The insulating component is formed as a cross-section gear with eight slots spaced equally in the circumferential direction.

5. The surge protection element according to claim 1, characterized in that, The outer diameter of the insulating component is smaller than the outer diameter of the discharge electrode, and regions are formed on both sides of the insulating component where the end faces of the pair of discharge electrodes directly face each other.

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