JPS6226131B2 - - Google Patents
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- Publication number
- JPS6226131B2 JPS6226131B2 JP55023707A JP2370780A JPS6226131B2 JP S6226131 B2 JPS6226131 B2 JP S6226131B2 JP 55023707 A JP55023707 A JP 55023707A JP 2370780 A JP2370780 A JP 2370780A JP S6226131 B2 JPS6226131 B2 JP S6226131B2
- Authority
- JP
- Japan
- Prior art keywords
- shield
- vacuum valve
- insulating
- fixed
- boron nitride
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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- High-Tension Arc-Extinguishing Switches Without Spraying Means (AREA)
Description
本発明は真空バルブに係り、特に真空バルブ内
の耐電圧性能の向上に関する。
従来の真空バルブは、第１図に示すように絶縁
筒１ａを軸方向に２個並設してなる絶縁容器１の
両端に夫々端板２，３を設けて内部を真空にした
真空容器を形成している。そして固定電極４は端
板２を気密に貫通する通電軸４ａに接触子４ｂを
有する電極４ｃを設けている。また、可動電極５
は端板３にベローズ６を介して可動に密封された
通電軸５ａに接触子５ｂを有する電極５ｃを設け
ている。そして、固定電極側に固定シールド７
を、真空容器の中間に中間シールド８を、可動側
には固定シールド７を設けている。
このようなシールド７，８は電流しや断時に電
極４，５間で発生する金属蒸気が絶縁容器１の内
壁に付着するのを防止するために大きな役割を果
している。しかしながら、この固定シールド７と
中間シールド８との近くに絶縁筒１ａがあるため
破壊電圧が低下する。これは、第２図に示すよう
に可動側について考えると、中間シールド８に電
界が加わると可動側の固定シールド７が陰極とな
つて放出された電子ｅは、絶縁筒１ａに衝突して
２次電子を放出する。この時の衝突エネルギーと
２次電子放出効率δ(E)との関係は第３図に示す特
性曲線δ(E)となる。第３図において縦軸は２次電
子放出効率δ(E)、横軸は電子の衝突エネルギーＥ
〔eV〕を示している。この曲線δ(E)に従つて絶縁
筒１ａには正の電荷が蓄積される。この絶縁筒１
ａから放出された電子は２次電子なだれによつて
電子増殖し、ついには絶縁破壊にいたる。したが
つて、比較的低電圧で電子なだれによる前駆破壊
電流が流れこの結果、破壊電圧は低くなつてしま
う。一方、近年真空バルブを用いる回路の高電圧
化が著るしく進み、高電圧で安定に用い得る真空
バルブの出現が望まれている。
しかして、上述の欠点を除去するための方法と
して、アルミナ及びエポキシ樹脂などの絶縁部材
で中間シールド８、固定シールド７の表面を被覆
することが考えられている。これは、陰極となる
どちらかのシールドからの電界放射電子の放出を
押えることができるため、絶縁筒に入射する１次
電子を抑制することができる。したがつて、絶縁
筒表面の２次電子なだれの進展を制限する事がで
き、耐電圧性能を向上する事が期待できる。しか
しながら、このようなものでは次のような欠点が
ある。
すなわち、真空バルブでは電流しや断時に発生
するアークによる電流表面の急激な温度上昇及び
ヒートラン試験等による温度上昇のために真空容
器内の部品は、なるべく熱伝導率の高い部品を使
用しなければならない。しかしながら、アルミナ
あるいはエポキシ樹脂等の絶縁材料は熱伝導率が
低いため、放熱特性が著るしく低下する。
また、アルミナあるいはエポキシ樹脂は絶縁材
料自体の絶縁耐力が低いため、期待する程耐電圧
性能が向上しない。
さらに、この種の真空バルブは脱ガス処理を行
なうために数100℃に真空加熱を行う必要があ
る。そのため、真空バルブ内の部品の融点を加熱
温度より高くしなければならない。一方、エポキ
シ樹脂は融点が低いため、エポキシ樹脂を真空容
器内で使用するためには加熱温度を低くする必要
があり脱ガス処理を充分に行なうことができな
い。
したがつて、真空バルブのシールドをアルミナ
あるいはエポキシ樹脂等の絶縁材料でコーテイン
グすることは困難であり、耐電圧性能の良好な高
電圧化に適した真空バルブを実用化することは困
難であつた。
本発明は、上記の事情に鑑みてなされたもの
で、放熱特性が良好でかつ耐電圧性能の優れた真
空バルブを提供することを目的とするものであ
る。
以下、本発明の一実施例を第４図および第５図
を参照して詳細に説明する。
なお、第１図と同一部分は同一符号を付してそ
の説明を省略する。第４図に示すように絶縁筒１
ａを軸方向に２個並設した絶縁容器１の両端にそ
れぞれ端板２，３を封着して真空容器を形成し、
固定電極４は端板２を貫通して封着された通電軸
４ａの先端に接触子４ｂを備えた電極４ｃを設け
ている。また可動電極５は端板３にカバー６ａを
有するベローズ６を介して可動に封着された通電
軸５ａの先端に接触子５ｂを備えた電極５ｃが設
けられている。固定電極側端板２及び可動電極側
端板３にはそれぞれ固定シールド７，７を設け、
この両固定シールド７，７の中間の絶縁筒１の接
続部の内壁に支持金物８を設けて中間シールド９
を保持するようにしている。
この固定シールド７及び中間シールド９の各軸
方向の端部には円弧部７ａ，９ａが設けられてお
り、固定シールド２１の端部の円弧部７ａはその
断面の曲率半径r1を有し、中間シールド９の先端
の円弧部９ａは、その断面の曲率半径r2を有して
いる。そして、この固定シールド７及び中間シー
ルド９の全周に窒化ホウ素系のセラミツク１０を
コーテイングしている。
また、コーテイング面積を少なくする場合は、
第５図に示すように固定シールド７の円弧部７ａ
及び中間シールド９の円弧部９ａの対向している
部位のそれぞれの頂点７ｂ，９ｂから、それぞれ
の曲率半径r1、r2の２倍、すなわち2r1、2r2の位
置まで絶縁筒１ａの内壁に対向する面に窒化ホウ
素系のセラミツク１０をコーテイングしている。
ところで窒化ホウ素、アルミナ、エポキシ樹脂
の物理的な性質を次の第１表に示す。
TECHNICAL FIELD The present invention relates to a vacuum valve, and more particularly to improving the withstand voltage performance within the vacuum valve. As shown in FIG. 1, a conventional vacuum valve has a vacuum container in which end plates 2 and 3 are provided at both ends of an insulating container 1, which is made up of two insulating cylinders 1a arranged side by side in the axial direction, and the inside is evacuated. is forming. The fixed electrode 4 is provided with an electrode 4c having a contact 4b on a current-carrying shaft 4a that passes through the end plate 2 in an airtight manner. In addition, the movable electrode 5
An electrode 5c having a contactor 5b is provided on the end plate 3 via a bellows 6 and movably sealed to a current-carrying shaft 5a. Then, a fixed shield 7 is placed on the fixed electrode side.
An intermediate shield 8 is provided in the middle of the vacuum container, and a fixed shield 7 is provided on the movable side. These shields 7 and 8 play a major role in preventing metal vapor generated between the electrodes 4 and 5 from adhering to the inner wall of the insulating container 1 when the current is interrupted. However, since the insulating tube 1a is located near the fixed shield 7 and the intermediate shield 8, the breakdown voltage decreases. Considering the movable side as shown in FIG. 2, when an electric field is applied to the intermediate shield 8, the fixed shield 7 on the movable side acts as a cathode, and the emitted electrons collide with the insulating tube 1a and 2 Emit secondary electrons. The relationship between collision energy and secondary electron emission efficiency δ(E) at this time is a characteristic curve δ(E) shown in FIG. In Figure 3, the vertical axis is the secondary electron emission efficiency δ(E), and the horizontal axis is the electron collision energy E.
[eV] is shown. Positive charges are accumulated in the insulating cylinder 1a according to this curve δ(E). This insulation tube 1
The electrons emitted from a multiply by a secondary electron avalanche, eventually leading to dielectric breakdown. Therefore, a precursor breakdown current due to electron avalanche flows at a relatively low voltage, resulting in a low breakdown voltage. On the other hand, in recent years, the voltage of circuits using vacuum valves has been significantly increased, and there is a desire for a vacuum valve that can be used stably at high voltage. Therefore, as a method for eliminating the above-mentioned drawbacks, it has been considered to cover the surfaces of the intermediate shield 8 and the fixed shield 7 with an insulating material such as alumina or epoxy resin. This can suppress the emission of field emission electrons from either of the shields serving as the cathode, and therefore can suppress the primary electrons entering the insulating tube. Therefore, it is possible to restrict the development of secondary electron avalanche on the surface of the insulating cylinder, and it is expected that the withstand voltage performance will be improved. However, such a device has the following drawbacks. In other words, in a vacuum valve, the parts inside the vacuum vessel must have as high a thermal conductivity as possible because of the sudden temperature rise on the current surface due to the arc that occurs when the current is interrupted, and the temperature rise due to heat run tests. It won't happen. However, since insulating materials such as alumina or epoxy resin have low thermal conductivity, their heat dissipation properties are significantly reduced. Furthermore, since the dielectric strength of the insulating material itself of alumina or epoxy resin is low, the withstand voltage performance does not improve as much as expected. Furthermore, this type of vacuum valve requires vacuum heating to several hundred degrees Celsius for degassing. Therefore, the melting point of the components inside the vacuum valve must be higher than the heating temperature. On the other hand, since epoxy resin has a low melting point, in order to use the epoxy resin in a vacuum container, it is necessary to lower the heating temperature, making it impossible to perform sufficient degassing treatment. Therefore, it is difficult to coat the shield of a vacuum valve with an insulating material such as alumina or epoxy resin, and it has been difficult to put into practical use a vacuum valve that has good withstand voltage performance and is suitable for high voltage applications. . The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a vacuum valve that has good heat dissipation characteristics and excellent withstand voltage performance. Hereinafter, one embodiment of the present invention will be described in detail with reference to FIGS. 4 and 5. Note that the same parts as in FIG. 1 are designated by the same reference numerals, and the explanation thereof will be omitted. As shown in Figure 4, the insulation tube 1
A vacuum container is formed by sealing end plates 2 and 3 to both ends of an insulating container 1 in which two A are arranged side by side in the axial direction,
The fixed electrode 4 has an electrode 4c provided with a contact 4b at the tip of a current-carrying shaft 4a that passes through the end plate 2 and is sealed. The movable electrode 5 is provided with an electrode 5c having a contact 5b at the tip of an energizing shaft 5a which is movably sealed to the end plate 3 via a bellows 6 having a cover 6a. Fixed shields 7, 7 are provided on the fixed electrode side end plate 2 and the movable electrode side end plate 3, respectively,
A support metal fitting 8 is provided on the inner wall of the connection part of the insulating cylinder 1 between the two fixed shields 7, 7, and an intermediate shield 9 is provided.
I try to keep it. Arc parts 7a and 9a are provided at each axial end of the fixed shield 7 and the intermediate shield 9, and the arc part 7a at the end of the fixed shield 21 has a radius of curvature r 1 of its cross section, The circular arc portion 9a at the tip of the intermediate shield 9 has a radius of curvature r 2 in its cross section. The fixed shield 7 and the intermediate shield 9 are coated with boron nitride ceramic 10 all over their circumferences. Also, if you want to reduce the coating area,
As shown in FIG. 5, the arc portion 7a of the fixed shield 7
and the inner wall of the insulating cylinder 1a from the respective vertices 7b and 9b of the opposing portions of the circular arc portion 9a of the intermediate shield 9 to twice the respective curvature radii r 1 and r 2 , that is, to the positions 2r 1 and 2r 2 A boron nitride-based ceramic 10 is coated on the surface facing the surface. Incidentally, the physical properties of boron nitride, alumina, and epoxy resin are shown in Table 1 below.
【表】
この第１表から明らかなように窒化ホウ素は、
アルミナあるいはエポキシ樹脂などの絶縁材料に
比して熱伝導率が非常に高く、かつ絶縁抵抗や絶
縁耐力等も高い。
このような性質を有する窒化ホウ素を真空バル
ブの中間シールド９及び固定シールド７の円弧部
９ｂ，７ｂの絶縁筒１ａの内壁に対向する面にコ
ーテイングすることにより、このコーテイング部
分の電界強度を高くでき、かつ絶縁筒１ａに対向
している部分であるため、固定シールド７及び中
間シールド９から放射された前駆破壊電流を抑制
し、絶縁筒１ａの表面の２次電子なだれを抑制で
きる。
この前駆破壊電流と印加電圧との関係を第６図
に示す。同図において、縦軸は前駆破壊電流を示
し、横軸は印加電圧を示している。曲線Ｉaは、
絶縁部材を被覆しない場合であり、曲線Ｉbは窒
化ホウ素系のセラミツクを被覆した場合である。
この前駆破壊電流が所定の限界Ｉcに達したとき
絶縁破壊となる。この前駆破壊電流が抑制される
ため絶縁破壊電圧が向上する。
したがつて、中間シールド９と固定シールド７
間の破壊電圧が高くなるため、中間シールド９の
円弧部９ｂの先端と固定シールド７の円弧部７ｂ
の先端との間のギヤツプ長を短かくする事がで
き、また絶縁筒１ａの内面と中間シールド９及び
固定シールド７間の距離も短くすることができ、
バルブの容積を大幅に小さくできる。
また窒化ホウ素は融点が非常に高くその値は真
空バルブの脱ガス処理時の加熱処理温度よりも充
分に高いため、解離ガスの放出も少なくバルブ内
の圧力もあまり高くはならない。
さらに第１表から明らかなように窒化ホウ素
は、他のアルミナ、エポキシ樹脂等の絶縁材料に
比して熱伝導率が高く放熱特性が良好であるた
め、これを絶縁材料として用いることにより電流
しや断による急激な温度上昇やヒートラン試験の
場合にも真空バルブ内の温度を他の絶縁材料をコ
ーテイングしたものに比して低温度に維持でき
る。
したがつて、真空容器の容積を小さくできるた
め、大幅なコストダウンを図ることができる。
また、中間シールド９及び固定シールド７の円
弧部９ａ，７ａの対向する頂点９ｂ，７ｂ間のギ
ヤツプ長を短かくできるため、電流しや断時に電
極４，５間から発生する金属蒸気が絶縁筒の内面
に付着することを防止できそれによつて、大電流
しや断時に金属蒸気が絶縁容器１ａの内面に付着
することによる耐圧低下を防止することができ
る。
以上詳述したように本発明によれば固定シール
ド及び中間シールドのそれぞれに窒化ホウ素系の
セラミツクをコーテイングする事により、両シー
ルド間の沿面耐圧を向上し、全体の形状を小型化
して大幅なコストダウンを図ることができ、また
放熱特性が良好なため高電圧、大容量に適する真
空バルブを提供する事ができる。[Table] As is clear from this Table 1, boron nitride is
It has a much higher thermal conductivity than insulating materials such as alumina or epoxy resin, and also has high insulation resistance and dielectric strength. By coating boron nitride, which has such properties, on the surfaces of the intermediate shield 9 of the vacuum valve and the arcuate portions 9b, 7b of the fixed shield 7, which face the inner wall of the insulating tube 1a, the electric field strength of this coated portion can be increased. , and facing the insulating tube 1a, it is possible to suppress the precursor breakdown current radiated from the fixed shield 7 and the intermediate shield 9, and to suppress the avalanche of secondary electrons on the surface of the insulating tube 1a. The relationship between this precursor breakdown current and the applied voltage is shown in FIG. In the figure, the vertical axis shows the precursor breakdown current, and the horizontal axis shows the applied voltage. The curve I a is
This is the case where the insulating member is not coated, and the curve I b is the case where the boron nitride ceramic is coated.
Dielectric breakdown occurs when this precursor breakdown current reaches a predetermined limit Ic . Since this precursor breakdown current is suppressed, the dielectric breakdown voltage is improved. Therefore, the intermediate shield 9 and the fixed shield 7
Since the breakdown voltage between the tip of the arc portion 9b of the intermediate shield 9 and the arc portion 7b of the fixed shield 7 is
It is possible to shorten the gap length between the tip of the insulating cylinder 1a and the distance between the inner surface of the insulating cylinder 1a and the intermediate shield 9 and fixed shield 7.
The volume of the valve can be significantly reduced. Further, boron nitride has a very high melting point, which is sufficiently higher than the heat treatment temperature during the degassing treatment of the vacuum valve, so that the release of dissociated gas is small and the pressure inside the valve does not become too high. Furthermore, as is clear from Table 1, boron nitride has higher thermal conductivity and better heat dissipation properties than other insulating materials such as alumina and epoxy resin, so boron nitride can be used as an insulating material to reduce current. Even in the case of a sudden temperature rise due to a heat-run test or a sudden temperature rise due to a heat-run test, the temperature inside the vacuum bulb can be maintained at a lower temperature than those coated with other insulating materials. Therefore, since the volume of the vacuum container can be reduced, it is possible to significantly reduce costs. Furthermore, since the gap length between the opposing vertices 9b and 7b of the arcuate portions 9a and 7a of the intermediate shield 9 and the fixed shield 7 can be shortened, metal vapor generated between the electrodes 4 and 5 when the current is cut off can be removed from the insulating tube. It is thereby possible to prevent metal vapor from adhering to the inner surface of the insulating container 1a, thereby preventing a drop in breakdown voltage due to metal vapor adhering to the inner surface of the insulating container 1a when a large current is interrupted. As described in detail above, according to the present invention, by coating each of the fixed shield and the intermediate shield with boron nitride ceramic, the creepage withstand voltage between the two shields is improved, the overall size is reduced, and the cost is significantly reduced. It is possible to provide a vacuum valve that is suitable for high voltage and large capacity because it has good heat dissipation characteristics.
第１図は、従来の真空バルブを示す縦断面図、
第２図は従来の真空バルブの中間シールドと固定
シールドの要部を示す断面図、第３図は、２次電
子放出特性を示す特性線図、第４図は本発明の真
空バルブを示す縦断面図、第５図は、本発明の真
空バルブの要部を示す断面図、第６図は印加電圧
と前駆破壊電流との関係を示す特性線図である。
１ａ……絶縁筒、１……絶縁容器、２，３……
端板、４……固定電極、５……可動電極、６……
ベローズ、７……固定シールド、９……中間シー
ルド、７ａ，９ａ……円弧部、１０……絶縁部
材。
FIG. 1 is a longitudinal sectional view showing a conventional vacuum valve;
Fig. 2 is a cross-sectional view showing the main parts of the intermediate shield and fixed shield of a conventional vacuum valve, Fig. 3 is a characteristic diagram showing secondary electron emission characteristics, and Fig. 4 is a longitudinal cross-sectional view showing the vacuum valve of the present invention. 5 is a cross-sectional view showing essential parts of the vacuum valve of the present invention, and FIG. 6 is a characteristic diagram showing the relationship between applied voltage and precursor breakdown current. 1a... Insulating cylinder, 1... Insulating container, 2, 3...
End plate, 4... Fixed electrode, 5... Movable electrode, 6...
Bellows, 7... Fixed shield, 9... Intermediate shield, 7a, 9a... Arc portion, 10... Insulating member.
Claims (1)
らなる真空容器内に接離可能な一対の電極を配置
しこの一対の電極の少なくとも一方がベローズを
介して前記端板に可動に封着されるとともに上記
端板に支持される固定シールドを配置しさらに上
記電極を包囲する中間シールドを備えた真空バル
ブにおいて、上記固定シールドおよび上記中間シ
ールドの各表面を窒化ホウ素系のセラミツクでコ
ーテイングした事を特徴とする真空バルブ。 ２ 固定シールドの軸方向端部を断面の曲率半径
r1の円弧部に形成し中間シールドの軸方向端部を
断面の曲率半径r2の円弧部に形成し、上記各円弧
部の対向部位の頂点から各曲率半径r1、r2の２倍
の部分でかつ絶縁容器内壁に相対面する部位の表
面を窒化ホウ素系のセラミツクでコーテイングし
た事を特徴とする特許請求の範囲第１項記載の真
空バルブ。[Claims] 1. A pair of electrodes that can be moved into and out of contact with each other is arranged in a vacuum container consisting of an insulating container and an end plate that closes the insulating container, and at least one of the pair of electrodes is connected to the end plate through a bellows. In the vacuum valve, each surface of the fixed shield and the intermediate shield is coated with a boron nitride-based material. A vacuum valve characterized by being coated with ceramic. 2 The radius of curvature of the cross section of the axial end of the fixed shield
The axial end of the intermediate shield is formed into a circular arc portion with a radius of curvature r 2 of the cross section, and the radii of curvature r 1 and twice the radius of r 2 are formed from the apex of the opposing portion of each of the above circular arc portions. 2. The vacuum valve according to claim 1, wherein the surface of the portion facing the inner wall of the insulating container is coated with boron nitride ceramic.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2370780A JPS56120043A (en) | 1980-02-27 | 1980-02-27 | Vacuum valve |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2370780A JPS56120043A (en) | 1980-02-27 | 1980-02-27 | Vacuum valve |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS56120043A JPS56120043A (en) | 1981-09-21 |
| JPS6226131B2 true JPS6226131B2 (en) | 1987-06-06 |
Family
ID=12117824
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2370780A Granted JPS56120043A (en) | 1980-02-27 | 1980-02-27 | Vacuum valve |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS56120043A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4703360B2 (en) * | 2005-10-21 | 2011-06-15 | 株式会社東芝 | Vacuum valve |
| JP2021089828A (en) * | 2019-12-03 | 2021-06-10 | 株式会社東芝 | Vacuum valve |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5855606B2 (en) * | 1978-12-27 | 1983-12-10 | 株式会社明電舎 | vacuum interrupter |
-
1980
- 1980-02-27 JP JP2370780A patent/JPS56120043A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS56120043A (en) | 1981-09-21 |
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