JP3601320B2 - surge absorber - Google Patents

Description

【００３４】
表１より、本発明のサージアブソーバは、小型でしかも寿命特性に優れ、テーピング特性、封着特性にも優れることが明らかである。
【００３５】
【発明の効果】
以上詳述した通り、本発明のサージアブソーバは、サージ耐量が大きく、寿命特性に優れ、しかも、ガラス管の内径や肉厚を大きくする必要がないため、小型で、自動実装に必要な５ｍｍピッチのテーピングが可能であると共に、市販品で入手が容易な通常の封止材で封着することができる。また、ガラスビーズが不要で、ガラス管自体のコストアップの問題がないため、安価に作製することができる。
【図面の簡単な説明】
【図１】本発明のサージアブソーバの実施の形態を示す断面図である。
【図２】図２（ａ）は緩衝部材の実施例を示す平面図、図２（ｂ）は同側面図である。
【図３】図４（ａ）は緩衝部材の他の実施例を示す平面図、図４（ｂ）は同側面図である。
【図４】従来のサージアブソーバを示す断面図である。
【図５】図５（ａ）は緩衝部材の別の実施例を示す正面図、図５（ｂ）は側面図である。
【符号の説明】
１ セラミック素体
２ 導電性皮膜
２Ａ マイクロギャップ
３ サージ吸収素子
４Ａ，４Ｂ キャップ電極
５，５Ａ，５Ｂ ガラス管
６Ａ，６Ｂ スラグリード
１０，１０Ｂ，１０Ｃ 緩衝部材[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electronic device such as a telephone or a modem connected to a communication line or a CRT drive circuit or the like which is susceptible to electric shock due to an abnormal voltage such as lightning surge or static electricity. TECHNICAL FIELD The present invention relates to a discharge forming type surge absorber used to prevent the breakage of a battery.
[0002]
[Prior art]
FIG. 4A is a cross-sectional view showing a conventional microgap surge absorber. The surge absorber, a cylindrical (may be polygonal column.) Micro-gap surge absorber 3 formed conductive film 2 of SnO ₂ or the like provided with a micro gap 2A on the surface of the ceramic body 1 of Metal cap electrodes 4A and 4B attached to both ends are inserted together with an inert gas into a glass tube 5 made of lead glass, and terminal electrodes (slag leads: sealing electrodes with lead wires) 6A and 6B It is manufactured by sandwiching, fixing, and sealing.
[0003]
Characteristics required for such a surge absorber include a discharge starting voltage, insulation resistance, life characteristics, and surge withstand capability. Of these, surge resistance, when the arc discharge in the surge absorber is generated by the abnormal voltage, resistance to phenomena that surge absorber reaches the breakdown by the difference in heat capacity and thermal conductivity of the ceramic body 1 and the glass tube 5 Which is a characteristic determined by the shape of the surge absorber. In order to increase this surge resistance,
(1) As shown in FIG. 4B, a glass tube 5A having a large inner diameter is used as the glass tube;
(2) As shown in FIG. 4C, a thick glass tube 5B is used as the glass tube;
That is being done.
[0004]
That is, the arc discharge in the surge absorber by abnormal voltage when the generated heat of the arc discharge is conducted to a surge absorption element 3 and the glass tube 5 made of ceramic body 1, respectively is heated pressurized. At this time, the ceramic body 1 has a small heat capacity and a large heat conductivity, but the glass tube 5 has a large heat capacity and a small heat conductivity, so that the ceramic body 1 expands more thermally than the glass tube 5. . For this reason, when a large current flows, tensile stress is generated in the glass tube 5, and cracks are generated at the contact points between the terminal electrodes (slag leads 6A and 6B) where the stress is concentrated and the glass tube 5, and the glass tube 5 is broken. Leads to.
[0005]
In the above (1) , the occurrence of the crack is prevented by using the glass tube 5A having a large inner diameter to reduce the influence of the thermal expansion of the ceramic body 1. In the above (2) , the occurrence of cracks is prevented by using the glass tube 5B which is thick and has excellent crack resistance.
[0006]
In addition, the arc discharge may evaporate the gap electrode, deteriorating the characteristics of the micro gap, and deteriorating the characteristics of the surge absorbing element. To prevent this,
(3) using a surge absorbing element without the metal cap electrodes 4A, 4B;
Things have also been done.
[0007]
[Problems to be solved by the invention]
The above methods (1) and (2) for increasing the surge withstand capability have the following problems.
[0008]
As shown in FIG. 4B, when a glass tube 5A having a large inner diameter is used, the manufactured surge absorber itself naturally becomes large, and axial taping at a pitch of 5 mm necessary for automatic mounting becomes impossible. Also, as the inner diameter of the glass tube 5A increases, the diameter of the sealing material (slag lead 6A ', 6B') used for sealing increases, making it extremely difficult to obtain a commercially available product. As shown in FIG. 4D, the slag leads 6A and 6B and the glass tube 5A can be sealed with a normal sealing material without using a sealing material having a large diameter. It is conceivable that glass beads 7A and 7B are interposed between the two. However, in this case, glass beads 7A and 7B are separately required, which leads to an increase in cost.
[0009]
As shown in FIG. 4C, even when the thick glass tube 5B is used, the size of the surge absorber increases and the amount of glass used for sealing increases. In addition, the cost of the glass tube itself is increased.
[0010]
When the surge absorbing element without a cap electrode described in the above (3) is put in a glass tube, cracks are likely to occur in the sealed glass tube.
[0011]
SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned conventional problems and to provide a small, low-cost surge absorber having a large surge withstand capability, a long life, and a small size.
[0012]
[Means for Solving the Problems]
A surge absorber according to the present invention (claim 1) is a discharge-forming surge absorber having a glass tube, a surge absorbing element inserted into the glass tube, and sealing electrodes provided at both ends of the glass tube. A buffer member made of a high melting point metal is interposed between the end of the surge absorbing element and the sealing electrode, and a surge absorber using the buffer member as a main discharge electrode , wherein the buffer member is The glass tube can be elastically deformed in the axial direction .
[0013]
The surge absorber according to the present invention (claim 2) is characterized in that the high melting point metal is a metal or an alloy composed of at least one of Cr, Mo and W.
[0014]
In the surge absorber of the present invention, the instantaneous thermal expansion of the ceramic body when receiving an abnormal voltage is absorbed by the deformation of the buffer member, thereby preventing a tensile stress from being generated in the glass tube, thereby improving the surge withstand capability. Can be increased.
[0015]
In the present invention, the surge absorbing element does not have the metal cap electrode, and therefore, there is no evaporation due to the discharge from the metal cap electrode, and there is no deterioration of the element due to this.
[0016]
In the present invention, the buffer member is used as the main discharge electrode, and since the discharge electrode is farther from the microgap of the surge absorbing element than in the related art, the influence of evaporation of the main discharge electrode is small. Since the main discharge electrode is made of a high melting point metal, evaporation is extremely small.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0018]
FIG. 1 is a sectional view showing an embodiment of a surge absorber according to the present invention. The surge absorber shown in FIG. 1 is characterized in that the surge absorbing element 3 does not have the cap electrodes 4A and 4B and that the buffer member 10B is interposed between the surge absorbing element 3 and the slag leads 6A and 6B. Unlike the conventional surge absorber shown in FIG. 4A, the other configuration is the same. In FIG. 1, members having the same functions as those in FIG. 4A are denoted by the same reference numerals.
[0019]
As shown in FIG. 3, the cushioning member 10B shown in FIG. 1 has a shape in which a circular metal plate is curved like a watch glass. Since the cushioning member 10B is elastically deformed in the direction of the arrow X, the thermal expansion of the ceramic body 1 is absorbed.
[0020]
The diameter of the buffer member 10B is slightly smaller than the inner diameter of the glass tube 5, and the thickness thereof is suitably about 0.1 to 1 mm. If the thickness is less than 0.1 mm, the elastic modulus (spring strength) is too small, and if it exceeds 1 mm, the elastic modulus may be too large.
[0021]
As a material of the metal plate, Cr, Mo, or W alone or an alloy of two or more thereof having a melting point of 2000 ° C. or more can be used.
[0022]
As shown in FIGS. 2 (a) (plan view) and (b) (side view), the cushioning member made of such a metal plate is preferably formed by cutting a metal plate into a circular shape at the center, preferably θ = about 90 to 90%. The buffer member 10 may be bent at about 178 °, particularly preferably about 150 to 175 °. As shown in FIGS. 5 (a) and 5 (b), a cushioning member 10C formed by bending the four corners of a metal plate cut into a square at about 30 to 90 ° and bending the center of the plate into a watch glass shape. It may be.
[0023]
The surge absorber of the present invention can be easily manufactured by sealing the buffer member together with the surge absorbing element in the glass tube.
[0024]
【Example】
Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.
[0025]
Example 1
The surge absorber of the present invention shown in FIG. 1 was produced using a buffer member 10B having a diameter of 1.6 mm and a shape shown in FIG. 3, which was made of a tungsten plate having a thickness of 0.1 mm.
[0026]
As the surge absorbing element 3, a SnO ₂ conductive film 2 having a thickness of 2 μm is formed on a cylindrical ceramic body (diameter 1 mm, length 3 mm, made of corundum mullite) 1, and a peripheral portion is formed at the center of the conductive film 2. The micro-gap 2A (width 50 μm) formed in the direction was used.
[0027]
This was inserted glass tube (outer diameter 3 mm, an inner diameter of 1.8 mm, length 7.3 mm) to 5, then inserting the cushioning member 10 B. After the end of the glass tube 5 is closed with a slag lead (diameter 1.7 mm, length 1.8 mm of the sealing portion), the inside of the glass tube 5 is sealed with a sealing gas (Ar gas, (1300 Torr) atmosphere, and then sealed by heating.
[0028]
The life characteristics of this surge absorber were measured as follows. That is, the rate of change of the discharge starting voltage when an impulse current having a waveform of 8/20 μsec-100 A was applied 300 times was measured. And the possibility of axial taping and sealing at a pitch of 5 mm was examined. The results are shown in Table 1.
[0029]
Comparative Example 1
A cap electrode (made of SUS, wall thickness: 0.1 mm) was press-fitted into the surge absorbing element 3 to reduce the number of micro gaps to five. Further, the buffer member 10B was not used. Except for these, a surge absorber as shown in FIG. 4A (however, the number of micro gaps is 5) is manufactured in the same manner as in the first embodiment, and the surge resistance, taping availability and sealing availability are similarly determined. The examination and the results are shown in Table 1.
[0030]
Examples 2 and 3
Instead of the cushioning member 10B, the cushioning member 10 shown in FIG. 2 was used in the second embodiment, and the cushioning member 10C shown in FIG. 5 was used in the third embodiment. The buffer member 10 has a diameter of 1.6 mm and an angle θ = 30 °. The cushioning member 10C is formed by processing a square plate having a side of 1.25 mm, and the bending angles of the four corners are 30 ° with respect to the original plate surface. Except for these, a surge absorber was produced in the same manner as in Example 1, and the surge resistance, taping availability and sealing availability were similarly examined. The results are shown in Table 1.
[0031]
Comparative Example 2
In manufacturing the surge absorber shown in FIG. 4D, a glass tube having an outer diameter of 5.3 mm, an inner diameter of 3.3 mm, and a length of 7.3 mm was used, and an outer diameter of 3.1 mm, an inner diameter of 1.8 mm, Slag leads 6A and 6B were attached via glass beads 7A and 7B having a length of 1.8 mm. Further, as the surge absorbing element, one provided with only one micro gap was used. Except for these, the surge absorber shown in FIG. 4D was manufactured in the same manner as in Comparative Example 1, and the surge resistance, taping availability and sealing availability were similarly examined. The results are shown in Table 1.
[0032]
Comparative Example 3
A surge absorber as shown in FIG. 1 was produced in the same manner as in Example 1 except that the buffer member 10B was not used, and the surge resistance, taping and sealing were examined in the same manner. The results are shown in Table 1. .
[0033]
[Table 1]

[0034]
From Table 1, it is clear that the surge absorber of the present invention is compact and has excellent life characteristics, and also has excellent taping characteristics and sealing characteristics.
[0035]
【The invention's effect】
As described in detail above, the surge absorber of the present invention has a large surge withstand capability, excellent life characteristics, and does not require an increase in the inner diameter or wall thickness of the glass tube. Can be used, and can be sealed with an ordinary sealing material that is easily available as a commercial product. Further, since glass beads are unnecessary and there is no problem of increasing the cost of the glass tube itself, it can be manufactured at a low cost.
[Brief description of the drawings]
FIG. 1 is a sectional view showing an embodiment of a surge absorber of the present invention.
FIG. 2 (a) is a plan view showing an embodiment of a cushioning member, and FIG. 2 (b) is a side view thereof.
FIG. 4A is a plan view showing another embodiment of the cushioning member, and FIG. 4B is a side view of the same.
FIG. 4 is a cross-sectional view showing a conventional surge absorber.
5 (a) is a front view showing another embodiment of the cushioning member, and FIG. 5 (b) is a side view.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Ceramic body 2 Conductive film 2A Micro gap 3 Surge absorption element 4A, 4B Cap electrode 5, 5A, 5B Glass tube 6A, 6B Slag lead 10, 10B, 10C Buffer member

Claims (2)

A glass tube, a surge absorbing element inserted into the glass tube, and a discharge forming surge absorber having sealing electrodes provided at both ends of the glass tube,
A surge absorber made of a metal having a high melting point of 2000 ° C. or more is interposed between the end of the surge absorbing element and the sealing electrode, and the surge absorber is a surge absorber using the buffer member as a main discharge electrode ,
The surge absorber is characterized in that the buffer member can be elastically deformed in the axial direction of the glass tube . 2. The surge absorber according to claim 1, wherein the refractory metal is a metal or an alloy composed of at least one of Cr, Mo and W.

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