| 摘要 |
PROBLEM TO BE SOLVED: To provide a switching valve which has superior durability and which will not cause the operation of the valve to affect those of other constitutions. SOLUTION: The switching valve comprises an O-ring 4, disposed at a distal end of a drive rod 34 so as to enclose a first port 36 by the ring 4, to pneumatically isolate a communication of the first port 36 with a second port 38. The valve further comprises an O-ring group 43, having a plurality of O-rings 42a and being disposed on a side face of the rod 34 so as to shut off an atmosphere, the port 36 and the port 38, while both the port 36 and the port 38 are enclosing by an outer periphery of the ring 40. The ring group 42 are all closely brought into contact in a state, in which the all are compressed as prescribed in a laminating direction, in a state in which the rod 34 is raised to shut off the port 36 and the port 38 from the atmosphere. Each ring 42a is further compressed, in a state in which the rod 34 is lowered, and hence the valve can be closed by the ring 40.
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