JPH0465506B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a method for manufacturing a surge absorption element using a spark discharge phenomenon.

[Background technology]

Conventionally, the surge absorbing element 50 includes a pair of carbon electrodes 51, 51, and these electrodes 5
1 and 51 are facing each other with a predetermined distance apart, as shown in FIG. An electrically insulating spacer 52 is interposed between the electrodes 51, 51 to provide a predetermined space. These electrodes 5
1, 51 and the spacer 52 are the insulating cylindrical body 5.
It is housed within 3. Metal plates 54, 54 are attached to the cylindrical body 53 so as to close the openings at both ends of the cylindrical body 53.
attached to the end. These metal plates 54,5
4 constitutes a container together with the cylindrical body 53, but at the same time, it is in electrically conductive contact with both electrodes 51, 51, respectively, and serves as an extraction electrode.

This surge absorbing element 50, for example, is connected in parallel to the load L as shown by the dashed line in FIG. 6, and when an abnormal surge voltage is applied, the electrode 51,
51 to generate a spark discharge to absorb the surge and protect the load L.

By the way, this surge absorbing element 50 does not start discharging even when a predetermined discharge starting voltage is reached, or
There is a problem in that the current value in the discharge state is not so large that the protection function cannot be reliably achieved.

[Purpose of the invention]

In view of the above-mentioned circumstances, this invention has stable discharge starting voltage characteristics, sufficient discharge current flows, etc.
It is an object of the present invention to provide a method for manufacturing a surge absorbing element that can provide a surge absorbing element that reliably performs a protective function.

[Disclosure of the invention]

In order to achieve the above object, the inventors conducted studies from various angles and found that fluctuations in the electrical conduction state and predetermined distance were caused by poor dimensional accuracy in the height (axial direction) of the cylindrical body 53. I obtained the knowledge that For example, if the size of the cylindrical body 53 is longer than a predetermined size, a gap G will be created between the upper electrode 51 and the metal plate 54 in the assembled state, as shown in FIG. If there is such a gap G, the contact between the electrode 51 and the metal plate 54 is insufficient, which increases the contact resistance and limits the discharge current, or the electrode 51 moves in the axial direction and the predetermined distance between the electrodes 51 and 51 increases. As a result, the discharge starting voltage may change.

As a result of continuing studies based on this knowledge, the inventors found that after attaching the metal plates to the cylindrical body, a pressing force was applied to at least one of the metal plates in the direction toward the electrode to cause plastic deformation, thereby making the metal plates stick closely together. It has been found that by doing so, the contact between the electrode and the metal plate becomes reliable, and an increase in the contact resistance between the electrode and the metal plate and a fluctuation in the predetermined distance between the electrodes can be prevented.

Therefore, in the present invention, a pair of electrodes facing each other with an electrically insulating spacer interposed therebetween are housed in an electrically insulating cylindrical body, and openings at both ends of the cylindrical body are provided. A metal plate is attached to the end of the cylindrical body so as to close the cylindrical body, and these metal plates contact both the electrodes and serve as extraction electrodes, so that spark discharge generated between the two electrodes is prevented. In order to obtain a surge absorption element that absorbs surges, after the metal plates are attached to the cylinder, a pressing force is applied to at least one of the metal plates in the direction toward the electrode to cause plastic deformation so that the metal plates are brought into close contact with each other. The gist of this invention is a method for manufacturing a surge absorbing element characterized by the following.

Hereinafter, the method for manufacturing the surge absorbing element according to the present invention will be explained in detail with reference to the drawings.

FIGS. 1a and 1b schematically represent important steps in an example of the method for manufacturing a surge absorbing element according to the present invention. FIG. 2 shows the appearance of the main parts used in manufacturing this surge absorbing element.

In manufacturing the surge absorbing element 1, the second
Prepare the parts as shown in the diagram. A pair of disk-shaped electrodes 2 and 2' made of carbon are electrodes for spark discharge. The ring-shaped spacer 3 is interposed between the electrodes 2 and 2' to form a space of a predetermined distance. The spacer 3 is made of an electrically insulating material such as ceramic. The cylindrical body 4 has the electrodes 2,
2' and spacer 3, and is made of an electrically insulating material such as ceramic (eg, alumina) or glass.

The metal plates 5, 5' close the openings at both ends of the cylindrical body 4, and are also used as extraction electrodes by contacting and conducting with the electrodes 2, 2'. The metal plates 5, 5' are made of a metal material such as copper or nickel. A concave recess 5a is formed in the metal plate 5, and a convex portion 5b is further formed in the recess 5a.
is formed. A concave depression 5'a is formed in the metal plate 5'.

An example of specific dimensions of each of the above-mentioned parts will be given below.

The cylindrical body 4 has, for example, an outer diameter of 4 to 10 mm and an inner diameter of 2.5 mm.
~7mm is selected. The height of the cylindrical body 4 is selected to be, for example, about 2 to 6 mm. disk-shaped electrode 2,
The outer diameter of 2' is approximately equal to the inner diameter of the cylindrical body 4, and the thickness is selected to be, for example, about 0.02 to 1.0 mm. The outer diameter of the spacer 3 is also approximately equal to the inner diameter of the cylindrical body 4, and the thickness is selected to be, for example, about 0.01 to 0.2 mm. The outer diameter of the metal plates 5, 5' is approximately equal to the outer diameter of the cylindrical body 4, and the thickness is selected to be, for example, about 0.1 to 0.35 mm. The concave depressions 5a and 5'a in the metal plates 5 and 5' have a diameter of about 2.5 to 3.5 mm and a depth of 0.5 to 3.5 mm.
It is selected to be around 0.8mm. The convex portion 5b of the metal plate 5 is
The diameter is about 1.0 to 2.0 mm and the height is about 0.2 to 0.5 mm.

Next, the assembly of the surge absorbing element 1 will be explained.

The cylindrical body 4 accommodates the electrodes 2, 2' and the spacer 3. Then, as shown in FIG. 1a, the metal plates 5, 5' are brazed to the ends of the cylindrical body 4 and hermetically sealed. At this time, brazing is performed in an inert gas atmosphere (for example, He or Ar gas 20 to 760 Torr).
It is made at a temperature of about 800℃. When brazing is performed in an inert gas, the cylindrical body 4 is filled with inert gas. The thicknesses of the electrodes 2, 2', spacer 3, cylindrical body 4, etc. are selected so that the gap between the metal plate 5 and the electrode 2 is approximately 0 to 0.1 mm in the brazed state.

After brazing, as shown in FIG. 1b, a punch P is applied to the convex portion 5b and a pressing force is applied in the direction toward the electrode 2 to plastically deform the metal plate 5 and bring it into close contact with the electrode 2. The applied load is, for example, about 5 to 15 kg. If this metal plate 5 has a convex portion 5b that bulges so that it is easily crushed, even if there is a slight spring back after the pressing force is removed, the state of plastic deformation will not substantially change. Moreover, stress that presses the electrode 2 remains. Therefore, the state in which the metal plate 5 is in strong contact with the electrode 2 is maintained.

The state of plastic deformation of the metal plate 5 was determined by computer simulation using the finite element method. The specific dimensions before plastic deformation are as follows. Outer radius l1 of cylindrical body 4: 4.125 mm, inner radius l2: 2.425 mm,
Thickness l3 of metal plate 5: 0.1 mm, depth l4 of depression 5a:
The height l5 of the convex portion 5b is 0.3 mm, and the gap l6 between the electrode 2 and the metal plate 5 before plastic deformation is 0.05 mm.

As shown in FIG. 3a, after brazing the metal plate 5, press the punch P against the convex part 5b and press the third
It is plastically deformed from the state shown by the dashed line in Figure b to the state shown by the solid line. The pressing distance l7 of punch P is
In the case of 0.3 mm, the contact pressure determined after the punch was released was 1.28 Kgf/mm2.

Note that when brazing is performed under reduced pressure, the internal space of the cylindrical body 4 becomes negative pressure in the atmosphere, so the metal plates 5, 5' bend inward and come into pressure contact with the electrodes 2, 2', respectively, making the contact even stronger. From this point of view as well, the electrical continuity between the metal plates and the electrodes and the assembly of the electrodes 2, 2' and the spacer 3 are ensured.

For example, when the surge absorbing element 1 is connected in parallel to a load and an abnormal surge voltage is applied, a spark discharge is generated between the electrodes 2 and 2', and the surge current is grounded through the electrodes 2 and 2' without passing through the load. At the same time, the voltage applied to the load is suppressed to approximately the discharge starting voltage.

As described above, in the surge absorbing element 1 obtained by the manufacturing method of the present invention, since the contact between the metal plates 5, 5' and the electrodes 2, 2' is strong, there is no increase in the contact resistance between the electrodes and the metal plates. Variations in the predetermined distance between the electrodes are prevented.

As shown in FIG. 4, the metal plate 5 may have a concave portion 5c in the center and a ring-shaped convex portion 5b surrounding the concave portion 5c. In this case, a pressing force is applied to the convex portion 5d to plastically deform it as shown by the dashed line in the same figure, thereby bringing the convex portion 5d into close contact.

As shown in FIG. 5, the metal plate 5 has a concave portion 5e.
It may also have a shape that has only one. In this case, a pressing force is applied to the shoulder 5f of the concave portion 5e to plastically deform it as shown by the dashed line in the same figure, thereby bringing it into close contact.

This invention is not limited to the above embodiments. For example, both metal plates may have depressions and convex portions, and pressing force may be applied from both sides to plastically deform both metal plates. The inside of the cylinder may be at atmospheric pressure instead of negative pressure. The inert gas does not need to be sealed. The electrodes may be made of materials other than carbon.

〔Effect of the invention〕

As described above, in the present invention, a pair of electrodes facing each other with an electrically insulating spacer interposed therebetween are housed in an electrically insulating cylindrical body, and both ends of the cylindrical body are A metal plate is attached to the end of the cylinder so as to close the opening,
These metal plates are in contact with both the electrodes and serve as lead-out electrodes, and in order to obtain a surge absorption element that absorbs surges even from spark discharge generated between the two electrodes, the metal plates are attached to the cylindrical body. After arriving,
A pressing force is applied to at least one metal plate in the direction toward the electrode to plastically deform the metal plate, thereby bringing the metal plate into close contact with the metal plate. Therefore, in the obtained surge absorbing element, since the contact between the metal plate and the electrode is firm, an increase in the contact resistance between the electrode and the metal plate and a change in the predetermined distance between the electrodes are prevented, resulting in a stable Sufficient surge absorption function is guaranteed.

[Brief explanation of the drawing]

FIGS. 1a and 1b are cross-sectional views schematically showing the plastic deformation process of a metal plate in an example of the method for manufacturing a surge absorbing element according to the present invention, and FIG. 2 is a main part used in manufacturing this surge absorbing element. Figures 3a and 3b are partial cross-sectional views explaining the state of plastic deformation of a metal plate determined by computer simulation, and Figures 4 and 5 are respectively a perspective view of another metal plate. FIG. 6 is a sectional view showing the structure of a conventional surge absorbing element. 1... Surge absorption element, 2, 2'... Electrode, 3
...Spacer, 4...Cylindrical body (cylindrical body), 5, 5'...
...metal plate.

Claims (1)

[Claims] 1 A pair of electrodes facing each other with a predetermined distance between them by interposing an electrically insulating spacer are housed in an electrically insulating cylindrical body, and the cylindrical body is closed so as to close the openings at both ends of the cylindrical body. metal plates are attached to the ends of the surge absorption element, these metal plates contact the two electrodes and serve as lead-out electrodes, and absorb surges even from spark discharge generated between the two electrodes. In obtaining the surge absorption, after the metal plates are attached to the cylindrical body, a pressing force is applied to at least one of the metal plates in the direction toward the electrode to cause plastic deformation so as to bring them into close contact. Element manufacturing method.