JPH023276B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing a surge absorption element, and in particular, to provide an internal space around a (micro) gap member without requiring any special material. The present invention relates to a method for manufacturing a surge absorbing element that can create a space by using a pressure difference when encapsulating the element.

[Prior Art] The present inventors have already filed patent applications for the manufacturing method of microgap type surge absorbing elements (Japanese Patent Application No. 112119/1982, Japanese Patent Application No. 112120/1983,
No. 61-112121), all of them require special materials in order to secure and install the space around the micro gap. These materials include (1) cap electrodes, (2) specially shaped slug leads (dimensions), and (3) specially shaped ceramic elements.

Examples of such conventionally manufactured devices are shown in FIGS. 4A, B, and C.

FIG. 4A uses a cap electrode, and the thickness of the cap electrode ensures a space around the microcap.
FIG. 4B uses a specially shaped slug lead, and by providing a recess in the center of the slag lead, the ceramic element is placed in the center of the external insulator. FIG. 4C uses a specially shaped ceramic element, in which the outer diameter of the central part of the ceramic element is reduced as shown. All of these use special materials, which poses a problem in terms of cost.

[Problems to be Solved by the Invention] Therefore, an object of the present invention is to provide a method for manufacturing a surge absorption element that can easily secure the space around the micro gap without using such special materials. be. Furthermore, another object of the present invention is to provide a method of manufacturing a surge absorbing element in a cost-effective manner. A further object of the present invention is to provide a method for manufacturing a microgap type surge absorbing element without requiring a special shape for the microgap forming element. A further object of the present invention is to provide a method for manufacturing a microgap type surge absorbing element having a simple structure and sufficient functionality at low cost.

[Structure of the Invention] [Means for Solving the Problems] Here, the gist of the present invention is to provide a method for manufacturing a micro-gap type surge absorption element in order to fill the surge absorption element with gas. When heating the surge absorbing element, the external insulator of the surge absorbing element is expanded by creating a pressure difference between the inside and the outside of the surge absorbing element, thereby securing a space around the microgap of the absorbing element. This is a method for manufacturing a surge absorbing element.

[Function] According to the manufacturing method of the present invention, it is necessary to provide an internal space around the microgap forming body of a surge absorbing element such as a microgap type discharge tube, but the treatment process for this is performed by filling the discharge tube with an inert gas. During heat treatment for sealing the external insulation,
By creating a pressure difference between the inside and outside of the outer glass tube, an internal space can be easily created around the microgap.

In a surge absorption element such as a microgap type surge absorption element, a gas such as an inert gas is usually sealed around the microgap.
This containment generally involves maintaining airtightness from the outside by sealing an insulator such as glass with a metal such as a cement. In order to seal the glass and metal, it is necessary to maintain the temperature at or above the softening point for an appropriate period of time. Further, in order to confine gas inside the microgap type surge absorbing element, all of these heat treatments are normally performed in a gas atmosphere, and the gas pressure can be controlled.

By using this gas pressure control to expand the glass tube during heat treatment, it is possible to easily secure space around the microgap without using special materials.

Surge absorbing elements include gap type discharge tubes and improved micro gap type discharge tubes.
In such a surge absorbing element, when a surge voltage is applied between the electrodes, a discharge occurs, and a surge current flows through the absorbing element so as to protect the equipment circuit. A microgap is provided to perform the function of such a surge absorbing element, but an internal space for insulation and discharge is required around the microgap. The gist of the manufacturing method of the present invention is to easily form this internal space.

To explain the present invention in more detail, at the end of the heat treatment, the glass and metal are sealed and the inside and outside of the glass tube are kept airtight. If the pressure outside the glass tube is reduced in this state, the pressure inside the glass tube will be relatively applied toward the outside, and the glass tube will inevitably expand.

FIG. 1 is a schematic cross-sectional view showing the heat treatment of the absorption element used in the manufacturing method of the present invention.
3', the microgap forming element 51 and the outer insulator (usually a cylindrical glass body) 52 are inserted into the arrangement shown in the cross-sectional view of FIG. When this is heated above the softening point of the glass body, the composite leads 53, 53' and the glass body 52 are sealed.

FIG. 2 is a cross-sectional view schematically showing the method for manufacturing the surge absorbing element according to the present invention. FIG. 2A shows the surge absorbing element member inserted as described above, before being heat-sealed. FIG. 2B shows the state of the heat-sealed surge absorbing element member. That is, the upper and lower composite leads are sealed to a cylindrical glass body, and the microgap forming element is located in the inner space thereof. An inert gas to be sealed within the glass body exists in the gap in the internal space. The glass body is in a softened state due to heating. At this time, when the external pressure of this cylindrical glass body is reduced, the inert gas in the internal space expands and pushes the softened glass body outward, so that the glass body expands uniformly.

FIG. 3 shows an apparatus used in the method for manufacturing the surge absorbing element of the present invention.

This is a schematic diagram of a glass encapsulation apparatus commonly used in the manufacture of glass diodes. A device (43) incorporating slag lead, glass, ceramic elements, etc. is placed in the carbon heater 42 and set in the enclosure tank 41, and then the vacuum pump 4
After opening the valve 45 connected to 4 and evacuating the enclosure tank 41, the valve 45 is closed. Subsequently, the valve 47 connected to the inert gas cylinder 46 is opened to introduce inert gas into the sealed tank 41 up to a predetermined gas pressure. Next, the carbon heater 42 is energized from the power source 48, the temperature of the carbon heater 42 is raised to a predetermined temperature, and the temperature is maintained for a certain period of time, whereby the microgap type surge absorption element structure 43 assembled in the carbon heater 42 is heated. The glass tube 52 and the slag lead 53,5
3' (Fig. 1). next,
After the glass body and the slag lead are sealed, the valve 45 is opened, the valve 45 and the leak valve 49 are opened simultaneously, or the leak valve 49 is opened, according to the method of the present invention. As a result, by lowering the pressure outside the glass tube 52 (FIG. 1), that is, within the enclosure tank 41, the relative pressure inside the glass tube 52 is increased, and the heated and softened glass tube is expanded. This ensures a space around the microgap forming body 51 (FIG. 1).

In other words, a space can be secured around the microgap simply by controlling the gas pressure at the end of the heat sealing process. Furthermore, since the glass tube is maintained above its softening point during this heat sealing process, by operating the cooling (slow cooling) process in the same way as usual after the gas pressure control is completed,
This allows product management to be performed without causing distortion to the glass tube.

As described above, according to the manufacturing method of the present invention, it is possible to easily secure a space around the microgap forming body without using special materials or tools, and this has an extremely large cost advantage in the manufacturing process. It is.

Additionally, gas pressure control does not specify the pressure difference between the inside and outside of the glass tube;
It is necessary to make an appropriate selection depending on the shape, dimensions, etc. of the glass tube.

Note that there are no particular limitations on the heat treatment method, shape, and arrangement of the surge absorbing element;
It is preferable to have a shape that allows the surge absorbing element to be reliably encapsulated in glass, and preferably arranged so that pressure is evenly applied from the inside to the outside.

Next, the method for manufacturing the surge absorbing element of the present invention will be explained with reference to the following specific examples.
The following description is not intended to be limiting.

[Example] Fig. 1 shows a cross section of a portion of a carbon heater. The ceramic element 51 in which the microgap has been made is placed in a glass tube 52 with a slug lead 5.
3,53'. At this time, there is almost no gap between the glass tube 52 and the ceramic element 51.

Raise the temperature for something with such a complicated configuration. The steps of changing the configuration of the surge absorbing element during the heat treatment are sequentially shown in FIGS. 2A, B, and C. FIG. 2A schematically shows the cross section of the microgap type surge absorption element before heating, FIG. 2B after heating, and FIG. 2C after gas pressure control. In FIG. 2A, the glass tube and the slag lead have not yet been sealed, and airtightness with the outside of the glass tube is not maintained. FIG. 2B shows the state after being maintained at a predetermined temperature for a predetermined time, and the glass tube and the slag lead are sealed to maintain airtightness from the outside of the glass tube. When the pressure outside the glass tube is reduced in this state, the pressure of the inert gas inside the glass tube is applied to the glass, pushing the glass from the inside to the outside, and the glass tube, which is in a softened state, naturally expands. go. The state in which the glass tube is expanded in this way is shown in FIG. 2C. By gradually cooling the surge absorbing element installed in this expanded state, the surge absorbing element with a space formed around the micro gap forming body can be easily created without using any special materials or tools. It can be manufactured.

[Effects of the Invention] The method for manufacturing a surge absorbing element according to the present invention expands the glass tube by creating a pressure difference between the inside and outside of the glass tube of the surge absorbing element when gas is filled in the micro gap type surge absorbing element. The purpose of this invention is to provide a method for manufacturing a surge absorbing element in a cost-effective manner without using special materials to form the internal space of the absorbing element. Second, it is possible to provide a method for manufacturing a microgap type surge absorption element without requiring a special shape for the microgap forming element. Thirdly, it is possible to provide a microgap type surge absorption element with a simple structure. Technical effects such as the ability to manufacture devices with sufficient functionality at low cost were obtained.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the assembly structure of a surge absorbing element and the structure of a heating tool in the manufacturing method of the present invention. FIGS. 2A, B, and C are cross-sectional views sequentially showing the manufacturing process of the surge absorbing element according to the manufacturing method of the present invention. Third
The figure is a diagram showing the configuration of a manufacturing apparatus used in the method for manufacturing the surge absorbing element of the present invention. Figure 4 A, B, C
1 is a cross-sectional view showing the structure of a conventional surge absorbing element. [Explanation of symbols of main parts], 41... Enclosure tank,
42... Carbon heater, 44... Vacuum pump, 46... Inert gas cylinder, 45, 47, 4
9... Bulb, 51... Ceramic element with microgap fabricated, 52... Glass tube, 5
3,53'...Slug lead.

Claims (1)

[Claims] 1. In the manufacture of a surge absorbing element, when the surge absorbing element is heat-treated to fill the surge absorbing element with gas, the outside of the surge absorbing element is heated by creating a pressure difference between the inside and outside of the surge absorbing element. A method for manufacturing a surge absorbing element, which comprises expanding an insulator to secure a space around a microgap of the absorbing element.