JP3933505B2 - Insulation cover for low temperature connection - Google Patents
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- JP3933505B2 JP3933505B2 JP2002078277A JP2002078277A JP3933505B2 JP 3933505 B2 JP3933505 B2 JP 3933505B2 JP 2002078277 A JP2002078277 A JP 2002078277A JP 2002078277 A JP2002078277 A JP 2002078277A JP 3933505 B2 JP3933505 B2 JP 3933505B2
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Description
【0001】
【発明の属する技術分野】
本発明は、天然ガス、プロパンガス等を貯蔵する低温液体用タンクの電線引き出し部等に使用される低温用接続部の絶縁カバーに関する。
【0002】
【従来の技術】
天然ガス、プロパンガス等の低温液体の貯蔵タンクに接続した液の吐出用ポンプ10の電源引き出しには、図4に示すように、低温液体吐出用高圧ポンプ10にフランジ部10aを設けて、この部分にターミナルヘッダ(電源引き出し用ブッシング)11を取り付けている。
上記ブッシング11の温度は、組み立て時には常温であるが、使用時には−20°C程度以下に達する。例えば、LPGの場合、沸点−45°C、LNGの場合は、沸点−161°Cであり、上記ブッシング11も熱伝導等より冷却され、−20°C程度以下となる。
また、その外、−40°Cまで冷却される低温倉庫や、−196°Cで使用される超伝導機器等に適用されるブッシング等においても、上記と同様に冷却され低温となる。
上記低温用機器の電源引き出し用ブッシング等に使用される絶縁カバーとして、従来、シリコンゴム等で形成される熱収縮チューブや、常温収縮チューブが使用されていた。この場合、絶縁カバーは全長収縮し、導体接続部等の被装着部の周辺の全面に締めばめで、密着して取り付けられている。なお、低温液体吐出用高圧ポンプ場合、その使用電圧は600V〜6000V程度である。
【0003】
図5に従来の絶縁カバーを取り付けた電源引き出し用ブッシングの断面構造の一例を示す。
同図において、1はシリコンゴム絶縁電線、1aは第1の導体接続金具であり、一方端が上記絶縁電線1の導体に圧着等により取り付けられる。
2は例えば低温液体貯蔵用タンクのポンプ電源に接続される中心導体であり、中心導体2の端部には、第2の導体接続金具2aが取り付けられ、上記第1,第2の導体接続金具1a,2aは導体接続用のボルト/ナット3により羽子板接続されている。
上記中心導体2の周囲には、中空の円筒形状のセラミック等で形成されるセラミック絶縁体2bが設けられ、該絶縁体2bの一方の端部には、金具2cが取り付けられている。また、上記絶縁体2bの他方端は、低温液体貯蔵用タンクのポンプ電源引き出し部に設けられたフランジ部等に取り付けられる。
【0004】
上記金具2cにはベローズ4の一端が取り付けられ、ベローズ4の他端は、上記中心導体2に取り付けられた金具2dに取り付けられている。
上記のようにベローズ4が設けられているので、その伸縮により、上記セラミックの絶縁体2bは中心導体に対して、同図の左右方向に若干移動可能である。また、上記ベロース4により、低温液体用タンク側は、絶縁電線側に対して気密に保たれる。
上記第1,第2の導体接続金具1a,2a、セラミック絶縁体2b、シリコン絶縁電線1等の周囲には、例えば、全長収縮する常温収縮チューブからなるシリコンゴム等で形成された絶縁カバー6が取り付けられる。
【0005】
【発明が解決しようとする課題】
天然ガス、プロパンガス等の低温液体の貯蔵タンク内ポンプ電源引き出し部等には、前記図4に示したようなセラミック絶縁体を備えた貫通ブッシング(以下ではセラミック絶縁ブッシングという)を取り付けている。このセラミック絶縁ブッシングの電線接続部は、図5に示したように羽子板接続あるいはプラグイン接続される。
上記低温用のセラミック絶縁ブッシング等の接続部に使用される絶縁カバーは、従来、図5に示したように、セラミック絶縁体2bから、接続端子金具1a,2a、電線1の絶縁部まで、絶縁カバー6が、締めばめ等により密着して取り付けられていた。
上記接続部において、低温液体によってブッシング導体が低温になり、上記シリコンゴム等で形成された絶縁カバーが弾性を失いプラスチック的な剛性を示す温度領域まで冷却されると、上記絶縁カバー6が図5のA部において、リング状に破断することがあった。
【0006】
これは以下の理由によるものと考えられる。
低温液体によって、上記接続部が上記温度まで冷却されると、接続部を構成する材料の熱膨張係数の差により、長さ方向、半径方向に変位が加わる。
ここで、図5に示す接続部のように、低温液体をシールするためセラミックブッシングにベローズ4が設けられ、このベローズ部や、セラミックブッシング部や、セラミックと金属の接合部等に凹部があると、上記絶縁カバー6は収縮後も、この凹部に密着せず凹部部分に空隙ができる。
一方、これ以外の部分では、絶縁カバー6は接続部を構成する被装着部材に密着しており、特に上記のように被装着物に凹凸があると、絶縁カバー6は被装着物に対して相対的に変位できない。
このため、接続部が上記温度まで冷却され、熱膨張係数の差により長さ方向、半径方向に変位が加わると、絶縁カバー6は、上記凹部上の部分でこの変位を全て負担することとなり、この部分に応力が集中する。
【0007】
絶縁カバー6は、冷却され伸び弾性を失っているので、上記のように特定部分に応力が集中すると、上記凹部上でリング状に破断するものと考えられる。
絶縁カバーが破断すると、ブッシング表面結露などにより、地絡・短絡発生に至る。
このため、上記ブッシングが、低温に温度低下しても、破断が発生しないものが望まれていた。
本発明は上記事情に鑑みなされたものであって、本発明の目的は、上記のような絶縁カバーのリング状破断を防止することができ、取り付け作業性に優れた低温用接続部の絶縁カバーを提供することである。
【0008】
【課題を解決するための手段】
本発明においては、上記課題を次のようにして解決する。
(1)少なくとも長さ方向の一方端側が、ガラス転移温度以下で使用され、少なくとも一部に断面が円もしくは楕円状の滑らかな表面を有し、他の部分は凹凸が形成された棒状あるいはパイプ状部分を有する電線接続部もしくはパイプ接続部にチューブ状の絶縁カバーを取り付けるに際し、絶縁カバーの一部を上記棒状あるいはパイプ状部分に気密シール可能に密着させ、他の部分を被装着物に接触させずに中空状に浮いた状態で取り付ける。
(2)上記中空状に浮いた部分の長さを、絶縁カバーと被装着物が低温になったとき、絶縁カバーと被装着物の熱膨張の差により生ずる上記中空状に浮いた部分に加わる伸びが、低温時における絶縁カバーの材料の破断伸びの範囲内にあるようにする。
上記のように、本発明においては、絶縁カバーの中央部を自己収縮させず中空状に浮いた状態とし、被装着部に対して所定の空隙が保たれるようにしたので、局部応力集中が発生せず、絶縁カバーが破断することがない。また、絶縁カバーが密着している被装着物の表面は滑らかなので、この部分に応力が集中することもなく、この部分で破断することもない。
特に、上記中空状に浮いた部分の長さを、絶縁カバーと被装着物の熱膨張の差により生ずる上記中空状に浮いた部分に加わる伸びが、低温時における絶縁カバーの材料の破断伸びの範囲内にあるようにすれば、効果的に絶縁カバーの破断を防止することができる。
【0009】
【発明の実施の形態】
図1に本発明の実施例の絶縁カバーを取り付けた接続部の断面構造を示す。前記図5に示したものと同一のものには同一の符号が付されており、1はシリコンゴム絶縁電線、1aは第1の導体接続金具であり、一方端が上記絶縁電線1の導体に圧着等により取り付けられる。
2は例えば低温液体貯蔵用タンクのポンプ電源に接続される中心導体であり、中心導体2の端部には、第2の導体接続金具2aが取り付けられ、上記第1,第2の導体接続金具1a,2aは導体接続用のボルト/ナット3により羽子板接続されている。
【0010】
上記中心導体2の周囲には、中空の円筒形状のセラミック等で形成されるセラミック絶縁体2bが設けられ、該絶縁体2bの一方の端部には、金具2cが取り付けられている。また、上記絶縁体2bの他方端は、低温液体貯蔵用タンクのポンプ電源引き出し部に設けられたフランジ部等に取り付けられる。
上記金具2cにはベローズ4の一端が取り付けられ、ベローズ4の他端は、上記中心導体2に取り付けられた金具2dに取り付けられている。
6は、例えば低温用シリコンゴム等で形成される本実施例の絶縁カバーであり、絶縁カバー6の両端部には厚肉部6aが形成されている。絶縁カバー6の厚肉部6aが、図1に示すように表面が滑らかなセラミック絶縁体2bとシリコンゴム絶縁電線1のシリコンゴム上で端部収縮して密着し、それ以外の部分は中空状に被装着部から浮いている。
【0011】
このため、上記接続部が温度低下し、絶縁カバー6と、第1,第2の導体接続金具1a,2a等から構成される被装着物の熱膨張率の差により、絶縁カバー6と被装着物が長さ方向に相対的に変位しても、この変位を上記絶縁カバー6の中空部分の長さ全体で受けることになる。
上記絶縁カバー6を構成する低温用シリコンゴムは、プラスチック状の剛性を示すようになっても、通常数十%以上の伸びは可能であり、この伸びは、上記温度低下による発生伸びより大きい。
上記のように絶縁カバー6の両端部以外の部分を、中空状に浮いた状態とすることにより、従来例に示したように局部応力集中が発生せず、また、低温用シリコンゴムは数十%以上の伸びは可能であるので、絶縁カバーが破断することがない。なお、絶縁カバー6の端部嵌合部(図1の厚肉部6aの部分)は、被装着物の表面が滑らかであるため、この部分に応力が集中することがなく、この部分で破断することはない。
【0012】
図2に各種ゴムの低温時における100%伸び時の応力値を示し、図3に低温用シリコンゴムの低温時における伸び特性を示す。
100%伸び時の応力値が高い程、剛性を示し、図2から分かるように、低温用シリコンゴムは、一般のシリコンゴム、有機ゴムに比べ、低温時(例えば−40°C以下)における剛性が小さいことが分かる。
また、低温用シリコンゴムは、組成により低温時でも高い弾性を示し、図3に示すように、−120°Cにおいても、2〜20%程度の伸びを示している。
【0013】
図1に示すように、絶縁カバー6が摩擦なく中空状に浮いた状態に保持され、この中空状に保持された部分に加わる低温時の伸びが、当該温度における絶縁カバー材料の破断伸びの範囲内にあり、かつ、伸びの発生回数が、繰り返し疲労の範囲内にあれば、絶縁カバー6は破断することはない。
すなわち、絶縁カバー6が破断しないようにするためには、以下の(i)(ii) の条件が満たされればよい。
(i) 〔温度変化によって発生する伸び長さ〕/〔中空に保持されている部分の長さ〕<〔低温時における材料の破断伸び率〕
(ii) 伸びの発生回数が、繰り返し疲労の範囲内にある。
なお、絶縁カバー6が摩擦なく中空に保持されている部分に加わる伸びは、前記したように、この絶縁カバー6が被着されている物体同士および絶縁カバーとの間の熱膨張の差によって発生するものである。これには、長さ方向と半径方向では差がある。
したがって、絶縁カバーが中空状に浮いた状態で保持される長さは、必ずしも図1に示した長さとする必要はなく、温度変化によって発生する伸び長さや、上記絶縁カバーの材料の破断伸び率等に応じて、上記(i)(ii) の条件を満たすように適宜設定すればよい。
【0014】
図1では、絶縁カバー6の両端部に一体に厚肉部6aを形成した場合を示したが、筒状の絶縁カバーの両端部分に別体の内層チューブを設け、外層の絶縁カバーが、内層チューブに対して、自己収縮気密シール可能に組み合わされたものであってもよい。また、絶縁カバーの長さ方向の少なくとも一端部に厚肉部を形成し、絶縁カバーの該厚肉部を含む一部を上記棒状あるいはパイプ状部分に気密シール可能に密着させるようにしてもよく、要するに、絶縁カバーの一部が中空状に浮いた状態で保持され、少なくとも、両端が気密シール可能に密着していればよい。
上記絶縁カバーの装着方法としては、例えば絶縁カバー内面に潤滑材を塗布し、絶縁カバーに被装着物を押し込んで装着するようにしてもよいが、絶縁カバーの少なくとも一端部を薄肉パイプ状の拡径支持材により拡形保持し、絶縁カバーの一端部を拡径保持した状態で、該絶縁カバー内に被装着物を挿入し、上記拡形支持材を除去することにより、絶縁カバーを被装着物に装着するように構成してもよい。
上記のように絶縁カバーの端部を拡形して、被装着物に装着するようにすれば、被装着物を絶縁カバー内に挿入する際、絶縁カバー内面に傷を付けることがないので、より望ましい。
なお、絶縁カバーの材料としては、低温で柔軟性に優れた前記低温用シリコンゴムが適しているが、これに限定されるものではなく、前記(i) (ii)の条件を満たすことができれば、プラスチック材料を用いてもよい。
【0015】
【発明の効果】
以上説明したように、本発明においては、絶縁カバーの中央部を自己収縮させず中空状に浮いた状態とし、被装着部に対して所定の空隙が保たれるようにしたので、接続部の温度が絶縁カバーのガラス転移温度以下まで低下しても、絶縁カバーが破断するのを防止することができる。
また、絶縁カバーが全長収縮しないので、従来例に比べ取り付け作業性を向上させることができる。
【図面の簡単な説明】
【図1】本発明の実施例を示す図である。
【図2】各種ゴムの低温時における100%伸び時の応力値を示す図である。
【図3】低温用シリコンゴムの低温時における伸び特性を示す図である。
【図4】低温液体用ポンプへの電源供給ブッシングの取り付け配置例を示す図である。
【図5】従来の絶縁カバーを取り付けた接続部の断面構造の一例を示す図である。
【符号の説明】
1 シリコンゴム絶縁電線
1a 第1の導体接続金具
2 ポンプ電源に接続される中心導体
2a 第2の導体接続金具
2b セラミック絶縁体
2c 金具
2d 金具
3 ボルト/ナット
4 ベローズ
6 絶縁カバー
6a 厚肉部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an insulating cover for a low temperature connecting portion used for an electric wire drawing portion of a low temperature liquid tank for storing natural gas, propane gas and the like.
[0002]
[Prior art]
As shown in FIG. 4, a low-pressure liquid discharge high-
The temperature of the bushing 11 is room temperature at the time of assembly, but reaches about −20 ° C. or less during use. For example, in the case of LPG, the boiling point is −45 ° C., and in the case of LNG, the boiling point is −161 ° C., and the bushing 11 is also cooled by heat conduction or the like and becomes about −20 ° C. or less.
In addition, in a low-temperature warehouse that is cooled to −40 ° C., a bushing that is applied to a superconducting device that is used at −196 ° C., and the like, it is cooled to a low temperature in the same manner as described above.
Conventionally, heat-shrinkable tubes formed of silicon rubber or the like, or cold-shrinkable tubes have been used as insulating covers used for power supply drawing bushings of the low-temperature equipment. In this case, the insulating cover is contracted over its entire length, and is tightly attached to the entire surface around the mounted portion such as the conductor connecting portion with an interference fit. In the case of a high-pressure pump for discharging a low temperature liquid, the operating voltage is about 600V to 6000V.
[0003]
FIG. 5 shows an example of a cross-sectional structure of a conventional power drawer bushing to which an insulating cover is attached.
In the figure, reference numeral 1 denotes a silicon rubber insulated wire, 1a denotes a first conductor connection fitting, and one end is attached to the conductor of the insulated wire 1 by crimping or the like.
Reference numeral 2 denotes a central conductor connected to a pump power source of a cryogenic liquid storage tank, for example. A second conductor connection fitting 2a is attached to an end of the center conductor 2, and the first and second conductor connection fittings are provided. 1a and 2a are connected to a wing plate by a bolt / nut 3 for conductor connection.
A ceramic insulator 2b formed of a hollow cylindrical ceramic or the like is provided around the center conductor 2, and a metal fitting 2c is attached to one end of the insulator 2b. Further, the other end of the insulator 2b is attached to a flange portion or the like provided in the pump power supply drawing portion of the cryogenic liquid storage tank.
[0004]
One end of a bellows 4 is attached to the metal fitting 2c, and the other end of the bellows 4 is attached to a metal fitting 2d attached to the center conductor 2.
Since the bellows 4 is provided as described above, the ceramic insulator 2b is slightly movable in the left-right direction in FIG. The bellows 4 keeps the cryogenic liquid tank side airtight with respect to the insulated wire side.
Around the first and second conductor connection fittings 1a and 2a, the ceramic insulator 2b, the silicon insulated wire 1 and the like, an insulating cover 6 formed of, for example, a normal temperature shrinkable tube made of a normal temperature shrinkable tube is contracted. It is attached.
[0005]
[Problems to be solved by the invention]
A penetrating bushing (hereinafter referred to as a ceramic insulating bushing) having a ceramic insulator as shown in FIG. 4 is attached to a pump power supply drawing portion in a storage tank of a low-temperature liquid such as natural gas or propane gas. The wire connecting portion of the ceramic insulating bushing is connected to a battledore or plug-in as shown in FIG.
As shown in FIG. 5, conventionally, the insulating cover used for the connecting portion such as the low-temperature ceramic insulating bushing is insulated from the ceramic insulator 2b to the connecting terminal fittings 1a and 2a and the insulating portion of the electric wire 1. The cover 6 was attached in close contact with an interference fit or the like.
When the bushing conductor is cooled to a low temperature by the low-temperature liquid in the connecting portion, and the insulating cover formed of the silicon rubber or the like loses elasticity and is cooled to a temperature region exhibiting plastic rigidity, the insulating cover 6 is shown in FIG. In part A, the ring sometimes broke.
[0006]
This is thought to be due to the following reasons.
When the connection portion is cooled to the temperature by the low-temperature liquid, a displacement is applied in the length direction and the radial direction due to the difference in thermal expansion coefficient of the material constituting the connection portion.
Here, the bellows 4 is provided in the ceramic bushing to seal the low temperature liquid as in the connection portion shown in FIG. 5, and the bellows portion, the ceramic bushing portion, the joint portion between the ceramic and the metal, or the like has a recess. Even after the insulating cover 6 contracts, the insulating cover 6 does not adhere to the concave portion, and a void is formed in the concave portion.
On the other hand, in other parts, the insulating cover 6 is in close contact with the mounted member constituting the connecting portion. In particular, when the mounted object has irregularities as described above, the insulating cover 6 is in contact with the mounted object. It cannot be displaced relatively.
For this reason, when the connecting portion is cooled to the above temperature and a displacement is applied in the length direction and the radial direction due to the difference in thermal expansion coefficient, the insulating cover 6 bears all of this displacement at the portion on the concave portion, Stress concentrates on this part.
[0007]
Since the insulating cover 6 is cooled and loses elasticity, it is considered that when the stress concentrates on the specific portion as described above, the insulating cover 6 breaks into a ring shape on the concave portion.
If the insulating cover breaks, grounding and short-circuiting may occur due to condensation on the bushing surface.
Therefore, it has been desired that the bushing does not break even when the temperature is lowered to a low temperature.
The present invention has been made in view of the above circumstances, and an object of the present invention is to prevent the ring-shaped breakage of the insulating cover as described above, and to provide an insulating cover for a low-temperature connection portion that is excellent in mounting workability. Is to provide.
[0008]
[Means for Solving the Problems]
In the present invention, the above problem is solved as follows.
(1) A rod or pipe in which at least one end side in the length direction is used below the glass transition temperature, and at least a part has a smooth surface with a circular or elliptical cross section, and the other part is uneven. When attaching a tube-shaped insulation cover to a wire connection part or pipe connection part that has a ring-shaped part, make sure that a part of the insulation cover is in close contact with the rod-shaped or pipe-shaped part so that it can be hermetically sealed, and the other part is in contact with the attachment Install in a hollow state without letting it go.
(2) The length of the hollow floating portion is added to the hollow floating portion generated by the difference in thermal expansion between the insulating cover and the mounted object when the insulating cover and the mounted object are cooled. The elongation is within the range of the breaking elongation of the insulating cover material at low temperatures.
As described above, in the present invention, the central portion of the insulating cover is in a hollow state without self-shrinking, and a predetermined gap is maintained with respect to the mounted portion. It does not occur and the insulating cover does not break. Further, since the surface of the object to be attached to which the insulating cover is in close contact is smooth, the stress does not concentrate on this portion and the portion does not break.
In particular, the elongation applied to the hollow floating portion, which is caused by the difference in thermal expansion between the insulating cover and the attached object, is the elongation at break of the insulating cover material at low temperatures. If it is within the range, the insulating cover can be effectively prevented from being broken.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a cross-sectional structure of a connecting portion to which an insulating cover according to an embodiment of the present invention is attached. The same components as those shown in FIG. 5 are denoted by the same reference numerals, 1 is a silicon rubber insulated wire, 1a is a first conductor connection fitting, and one end is a conductor of the insulated wire 1. It is attached by crimping or the like.
Reference numeral 2 denotes a central conductor connected to a pump power source of a cryogenic liquid storage tank, for example. A second conductor connection fitting 2a is attached to an end of the center conductor 2, and the first and second conductor connection fittings are provided. 1a and 2a are connected to a wing plate by a bolt / nut 3 for conductor connection.
[0010]
A ceramic insulator 2b formed of a hollow cylindrical ceramic or the like is provided around the center conductor 2, and a metal fitting 2c is attached to one end of the insulator 2b. Further, the other end of the insulator 2b is attached to a flange portion or the like provided in the pump power supply drawing portion of the cryogenic liquid storage tank.
One end of a bellows 4 is attached to the metal fitting 2c, and the other end of the bellows 4 is attached to a metal fitting 2d attached to the center conductor 2.
Reference numeral 6 denotes an insulating cover of the present embodiment formed of, for example, low-temperature silicon rubber, and thick portions 6 a are formed at both ends of the insulating cover 6. As shown in FIG. 1, the thick wall portion 6a of the insulating cover 6 is in close contact with the ceramic insulator 2b having a smooth surface on the silicon rubber of the silicon rubber insulated wire 1, and the other portions are hollow. Floating from the mounted part.
[0011]
For this reason, the temperature of the connecting portion is lowered, and the insulation cover 6 and the attached member are attached due to the difference in the coefficient of thermal expansion between the attached member composed of the insulating cover 6 and the first and second conductor connecting fittings 1a and 2a. Even if the object is relatively displaced in the length direction, this displacement is received by the entire length of the hollow portion of the insulating cover 6.
Even if the low-temperature silicon rubber constituting the insulating cover 6 exhibits plastic-like rigidity, the elongation can usually be several tens of percent or more, and this elongation is larger than the generated elongation due to the temperature decrease.
As described above, the portions other than the both end portions of the insulating cover 6 are made to float in a hollow state, so that local stress concentration does not occur as shown in the conventional example, and the low temperature silicon rubber is several tens of thousands. % Or more elongation is possible, so that the insulating cover does not break. The end fitting portion of the insulating cover 6 (the portion of the thick portion 6a in FIG. 1) has a smooth surface to be mounted, so that stress does not concentrate on this portion and breaks at this portion. Never do.
[0012]
FIG. 2 shows the stress values at 100% elongation of various rubbers at low temperatures, and FIG. 3 shows the elongation characteristics of low temperature silicon rubber at low temperatures.
The higher the stress value at 100% elongation, the higher the rigidity. As can be seen from FIG. 2, the low temperature silicone rubber has a lower rigidity (for example, −40 ° C. or lower) than the general silicon rubber and organic rubber. Is small.
Further, the low temperature silicon rubber exhibits high elasticity even at low temperatures due to its composition, and as shown in FIG. 3, it exhibits an elongation of about 2 to 20% even at −120 ° C.
[0013]
As shown in FIG. 1, the insulating cover 6 is held in a hollow state without friction, and the elongation at low temperature applied to the hollow portion is the range of the elongation at break of the insulating cover material at that temperature. If the number of occurrences of elongation is within the range of repeated fatigue, the insulating cover 6 will not break.
That is, in order to prevent the insulating cover 6 from being broken, the following conditions (i) and (ii) may be satisfied.
(i) [Elongation length generated by temperature change] / [Length of hollow portion] <[Elongation at break of material at low temperature]
(ii) The number of elongations is within the range of repeated fatigue.
In addition, as described above, the elongation applied to the portion where the insulating cover 6 is held hollow without friction is caused by the difference in thermal expansion between the objects to which the insulating cover 6 is attached and the insulating cover. To do. There is a difference between the length direction and the radial direction.
Therefore, the length of the insulating cover that is held in a hollow state is not necessarily the length shown in FIG. 1, and is not necessarily the length shown in FIG. Depending on the above, it may be set as appropriate so as to satisfy the above conditions (i) and (ii).
[0014]
Although FIG. 1 shows the case where the thick portions 6a are integrally formed at both ends of the insulating cover 6, separate inner layer tubes are provided at both ends of the cylindrical insulating cover, and the outer insulating cover is formed as an inner layer. The tube may be combined so that a self-shrinking hermetic seal is possible. Further, a thick part may be formed at least at one end in the length direction of the insulating cover, and a part including the thick part of the insulating cover may be closely attached to the rod-like or pipe-like part so as to be hermetically sealed. In short, it is only necessary that a part of the insulating cover is held in a hollow state and at least both ends are in close contact with each other so as to be hermetically sealed.
As a method for attaching the insulating cover, for example, a lubricant may be applied to the inner surface of the insulating cover, and an object to be attached may be pushed into the insulating cover for attachment. However, at least one end of the insulating cover may be expanded like a thin pipe. With the diameter support material expanded and held, with one end of the insulating cover expanded in diameter, insert the object to be inserted into the insulation cover and remove the expansion support material to attach the insulation cover. You may comprise so that it may mount | wear with a thing.
If you expand the end of the insulating cover as described above and attach it to the attachment, it will not damage the inner surface of the insulation cover when inserting the attachment into the insulation cover. More desirable.
As the material for the insulating cover, the low-temperature silicon rubber having excellent flexibility at low temperature is suitable, but is not limited to this, as long as the condition (i) (ii) can be satisfied. A plastic material may be used.
[0015]
【The invention's effect】
As described above, in the present invention, the central portion of the insulating cover is made to be in a hollow state without self-shrinking, and a predetermined gap is maintained with respect to the mounted portion. Even if the temperature falls below the glass transition temperature of the insulating cover, the insulating cover can be prevented from breaking.
In addition, since the insulating cover does not shrink the entire length, the mounting workability can be improved as compared with the conventional example.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of the present invention.
FIG. 2 is a diagram showing stress values at 100% elongation of various rubbers at low temperatures.
FIG. 3 is a view showing elongation characteristics at low temperature of low temperature silicon rubber.
FIG. 4 is a diagram showing an example of a mounting arrangement of a power supply bushing to a cryogenic liquid pump.
FIG. 5 is a diagram showing an example of a cross-sectional structure of a connection portion to which a conventional insulating cover is attached.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Silicon rubber insulated wire 1a 1st conductor connection metal fitting 2 2 Center conductor 2a connected to pump power supply 2nd conductor connection metal fitting 2b Ceramic insulator 2c Metal fitting 2d Metal fitting 3 Bolt / nut 4 Bellows 6 Insulation cover 6a Thick part
Claims (1)
上記絶縁カバーが取り付けられる被装着物は、少なくとも一部に断面が円もしくは楕円状の滑らかな表面を有する棒状あるいはパイプ状部分を有し、上記被装着物の他の部分は凹凸が形成されており、
上記絶縁カバーの一部が上記棒状あるいはパイプ状部分に気密シール可能に密着し、他の部分が被装着物に接触せずに中空状に浮いた状態で被装着物に取り付けられ、
上記中空状に浮いた部分の長さは、絶縁カバーと被装着物が低温になったとき、絶縁カバーと被装着物の熱膨張の差により生ずる上記中空状に浮いた部分に加わる伸びが、低温時における絶縁カバーの材料の破断伸びの範囲内にあるようにした
ことを特徴とする低温用接続部の絶縁カバー。At least one end side in the length direction is an insulating cover of a low temperature connecting portion attached to an electric wire connecting portion or a pipe connecting portion used below the glass transition temperature of the insulating cover material,
The object to be attached to which the insulating cover is attached has a rod-like or pipe-like part having a smooth surface with a circular or elliptical cross section at least in part, and the other parts of the object to be attached are uneven. And
A part of the insulating cover is in close contact with the rod-like or pipe-like part so as to be airtightly sealed, and the other part is attached to the attachment in a state of floating in a hollow shape without contacting the attachment ,
The length of the hollow floating part is the elongation applied to the hollow floating part caused by the difference in thermal expansion between the insulating cover and the mounted object when the insulating cover and the mounted object are at a low temperature. an insulation cover of the low-temperature connecting portion, wherein the <br/> this was to be within the scope of the elongation at break of the material of the insulating cover at the low temperature.
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JP2002078277A JP3933505B2 (en) | 2002-03-20 | 2002-03-20 | Insulation cover for low temperature connection |
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JP2002078277A JP3933505B2 (en) | 2002-03-20 | 2002-03-20 | Insulation cover for low temperature connection |
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JP3933505B2 true JP3933505B2 (en) | 2007-06-20 |
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