| 摘要 |
PROBLEM TO BE SOLVED: To solve a problem on a conventional on-off valve which uses a rubber member for energizing a valve element cover to the side of a valve element and is mounted in a state of being compressed to some extent to avoid the movement of the valve element cover until pressure in a secondary chamber reaches predetermined pressure, that the rubber member has characteristics of abruptly increasing its elastic modulus when compressed and deformed and requires great power for further deformation when elastically deformed to some extent, and therefore other components including a retainer retaining the rubber member are plastically deformed while the rubber member is not elastically deformed when a degree of freezing water in the secondary chamber becomes higher to increase the displacement of the valve element cover. SOLUTION: This on-off valve has a slit groove 12 as a pressure releasing means for releasing pressure from the secondary chamber 5 while opening the secondary chamber 5 to the outside when the valve element cover 6 is moved by a predetermined distance d. COPYRIGHT: (C)2009,JPO&INPIT
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