| 摘要 |
<p>PURPOSE:To obtain the captioned mechanism wherein the seal thereof will never be spoiled even upon being used in an extreme low temperature, further, a blow- out pressure as well as a blow-stop pressure thereof can be adjusted easily and correctly, and furthermore the opening condition thereof can be held forcibly when it is necessary. CONSTITUTION:The space between a helium vessel 2 and the wall part 1 of an outer tank is evacuated. A valve rod 3 is formed by connecting cylindrical first to third shaft bodies 4-6 and a pipe 7 while a valve sheet 11 is attached to the lower end of the pipe 7. The valve rod 3 is energized toward the downward direction thereof by a spring 24 so as to push the valve sheet 11 against a valve seat 12. The valve can be held under the opening condition forcibly by introducing high-pressure air into a pressure chamber 21. A spring 19 is provided at normal temperature part, therefore, change of elasticity thereof under an extreme low temperature may be prevented and the pushing force thereof may be set correctly.</p> |
