| 摘要 |
A check valve (fluid on-off valve device) capable of attaining high sealability in either case where a differential pressure is high or low, comprises a valve body assembly (valve body) contacting and separating from a valve seat portion for communicating and blocking a fluid passage. The valve body assembly comprises a valve body, a low-pressure seal portion constituted out of soft material and a high-pressure seal portion constituted out of harder material than the low-pressure seal portion. In blocking a fluid passage, when a differential pressure between an upstream path and a downstream path in the fluid passage is relatively low, the low-pressure seal portion comes into close contact with a protrusion to block the fluid passage, while when the differential pressure is relatively high, the low-pressure seal portion is compressively deformed by the differential pressure and the high-pressure seal portion comes into close contact with the valve seat body, thus blocking the fluid passage. |
