| 摘要 |
PROBLEM TO BE SOLVED: To provide a compact and inexpensive vacuum valve having a longer life. SOLUTION: The vacuum valve 1 comprises a cylinder part 12, a first port 32 provided in a valve body 31, a second port 33, a valve seat part 34, and a valve element 24 having a seal member 35 connected to a movable shaft 23 for abutting on or separating from the valve seat part 34. The cylinder part 12 has a first piston 45 and a second piston. With pressure fluid supplied to a first operation port 25, the first piston 45 and the second piston 46 receive pressure to be moved. When the second piston 46 abuts on a cylinder tube inner abutting face 21d, a space is formed between the first piston 45 and an end abutting face 45d and so the first port 32 and the second port 33 are further moved to the side of shutting off the first port 32 and the second port 33. The thrust of the first piston 45 only serves as pressure on the seal member 35 which abuts on the valve seat part 34. COPYRIGHT: (C)2007,JPO&INPIT
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