| 摘要 |
PURPOSE:To restrain a temperature rise of an O-ring and to realize a long life of gas seal by providing a bendable heat-resistant ring to a vacuum side of the O-ring which is used for gas sealing. CONSTITUTION:An O-ring 11 seals between gas in the inside 3 and a vacuum heat insulating layer 10. A ring 12 has a slit 19 or recesses 20, 21, and is provided to the side of the vacuum heat insulating layer 10 against the O-ring 11. The ring 12 is heated more rapidly than the O-ring 11. Even if rubber of fluorine compound which is known as a heat-resistant material is used as a construction material, a surface of the ring 12 begins to melt to gel and to adhere to surfaces of a peripheral outer tune 8 and a supporting tube 7 when a temperature exceeds 250 deg.C. The ring 12 without sealing function is selectively deteriorated; deterioration of the O-ring 11 is thereby delayed and function of gas sealing can be maintained for a long time. |
