JPH054230Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is connected between an electronic device and a power source, and is used to prevent surges from entering the device through a discharge gap sealed in an airtight container. This invention relates to a discharge-type surge absorption element that absorbs electricity through a discharge phenomenon, and in particular to a discharge-type surge absorption element with a safety mechanism that improves safety in the event of a failure by devising the container structure to create an open failure mode. .

[Prior Art] Conventionally, a seed discharge type surge absorbing element 10 widely known as an arrester has a pair of rod-shaped discharge electrodes 2, 2 made of Ni or the like, as shown in FIG.
A discharge gap 4 is formed between the discharge electrodes 2, 2 by arranging them substantially parallel to each other, and this is sealed together with a discharge gas such as a rare gas in an airtight container 5 made of a glass bulb. It has a structure in which lead wires 3, 3 are connected to 2 and guided out of the airtight container 5.

The discharge type surge absorbing element 10 is used by being connected between a circuit of an electronic device and a power source,
If a surge such as dielectric lightning is applied to this,
A discharge occurs in the discharge gap, absorbing the surge, and protecting the electronic equipment from the surge.

[Problems to be solved by the invention] The above-mentioned discharge-type surge absorption element absorbs surges by arc discharge in the discharge gap, so it can absorb quite large surges, but the rated If a significantly larger surge is applied, the energy may melt the discharge electrode and cause a short circuit. Furthermore, even if the surge is within the rating, if it is applied repeatedly over a long period of time, spatter material from the discharge electrode may adhere to and accumulate on the inner wall of the airtight container, causing a short circuit.

As mentioned above, when the discharge type surge absorbing element fails in the short circuit mode, an excessive short circuit current flows through the surge absorbing element and melting it, eventually causing the circuit board on which the discharge type surge absorbing element is mounted to fail. The heat generated by the element may lead to combustion, which may cause burnout to the surrounding area.

This invention was devised in view of the above points,
Safety equipment equipped with a mechanism that can cut off the overcurrent and prevent burnout accidents when an overcurrent flows due to a surge that significantly exceeds the rating, or when a short circuit current due to spatter material becomes excessive. The aim is to realize a discharge type surge absorption element with a mechanism.

[Means for Solving the Problem] In order to achieve the above object, the discharge type surge absorbing element with a safety mechanism according to the present invention has a pair of discharge electrodes arranged facing each other at a predetermined interval, and a discharge between the discharge electrodes. A discharge type surge absorbing element formed by forming a gap and enclosing the gap in an airtight container, which is generated when the discharge type surge absorbing element generates heat due to the application of an overcurrent. The airtight container is characterized in that a mechanically weak portion is formed in the airtight container so that the airtight container is destroyed by thermal distortion.

[Function] Therefore, if a surge that greatly exceeds the rating is applied to the above-mentioned discharge-type surge absorption element, and an overcurrent flows through the element due to the application of the surge, a large amount of electricity will be generated by the arc discharge generated in the discharge gap. heat is generated,
The airtight container is heated by this heat, thermal distortion occurs, and the container is destroyed at its mechanically weak portion. As a result, the discharge in the discharge gap is stopped and the overcurrent is cut off. In addition, if a short circuit occurs due to spatter material, the amount of heat generated by the short circuit will increase if the short circuit current becomes excessive, and as mentioned above, the airtight container will be destroyed, the conductive path will be severed, and the overcurrent will be cut off. .

[Example] Hereinafter, an example of the present invention will be described based on the drawings.

FIG. 1 is a perspective view of a discharge type surge absorbing element with a safety mechanism according to an embodiment of the present invention. In the figure, the discharge type surge absorbing element 1 with safety mechanism uses BaCO ₃ , BaO, etc. on the surface of a metal with good discharge characteristics such as Ni.
A pair of rod-shaped discharge electrodes 2, 2 formed by covering with an emitter material such as AI ₂ O ₃ is connected to one end of each of the lead wires 3, 3 made of a composite wire, and the lead wires 3, 3 are made to face each other substantially in parallel to perform the above-mentioned discharge. A discharge gap 4 is formed between the electrodes 2, 2, and this is further sealed in an airtight container 5 together with a discharge gas mainly composed of a rare gas such as Ne, He, Ar, etc. or an inert gas such as nitrogen gas. have.

The airtight container 5 is formed by heating and crushing one end of a glass tube to fix the lead wires 3, 3, and sealing off the other end. , a mechanically weak portion 6 that can be destroyed by thermal strain caused by overcurrent.

The thin wall portion as the mechanically weak portion 6 in the airtight container 5 can be formed by the above-mentioned scratches or by heating and softening the airtight container 5 and pressing the wall surface with a jig or the like. Alternatively, it can also be formed by holding both ends of the airtight container 5 that has been partially softened by heating and pulling it to stretch the softened portion. In the former case, the cross-sectional shape of the thin portion is as shown in FIG. 2A, and in the latter case, the cross-sectional shape is as shown in FIG. 2B. In addition, the mechanically weak portion 6 is not limited to the thin portion described above, but can also be formed by, for example, applying strain to the wall portion of the airtight container in advance. It is sufficient that the mechanical strength is reduced to such an extent that the airtight container can be destroyed by thermal distortion caused by heat generation. The aspects of this mechanically weak portion 6 (formation location, number of formation, shape, area, depth, etc.) are as follows:
It is determined individually and specifically by taking into account the material, shape, and hardness of the airtight container 5, the amount of heat generated by the element when an overcurrent is applied, and the like.

[Effects of the invention] As detailed above, in the discharge type surge absorbing element with a safety mechanism of the present invention, when the element becomes overheated due to overcurrent, the airtight container is destroyed in the mechanically weak part. Since the overcurrent is cut off, burnout accidents can be prevented. Moreover, the above-mentioned safety mechanism can be easily formed by simply processing the airtight container of the conventional discharge type surge absorbing element, and has high practical value.

[Brief explanation of the drawing]

1 and 2 show an embodiment of the present invention, FIG. 1 is a perspective view, and FIG. 2 is a sectional view of a main part showing an example of the shape of a thin part as a part with weak mechanical strength. , FIG. 3 is a perspective view of a conventional example. 1...discharge type surge absorption element with safety mechanism, 2,
2...Discharge electrode, 4...Discharge gap, 5...Airtight container, 6...Mechanically weak part.

Claims (1)

[Claims for Utility Model Registration] (1) A discharge-type surge absorber in which a pair of discharge electrodes are arranged facing each other at a predetermined interval to form a discharge gap between the discharge electrodes, and this is sealed in an airtight container. The airtight container is configured such that when the discharge type surge absorbing element generates heat due to the application of an overcurrent, the airtight container is destroyed by thermal distortion caused by the heat generation. A discharge type surge absorption element with a safety mechanism, characterized by forming a mechanically weak part. (2) The discharge-type surge absorbing element with a safety mechanism according to claim 1, wherein the mechanically weak portion is a thin wall portion formed on the wall of the airtight container. (3) The discharge type surge absorbing element with a safety mechanism according to claim 1, wherein the mechanically weak portion is a distortion formed in the wall of the airtight container.