| 摘要 |
PROBLEM TO BE SOLVED: To prevent ports from simultaneous communication during switching of a three-port valve and besides to reduce the number of fluid reservoirs and seal spots. SOLUTION: Passages 21 and 41 on the output side of two two-port valves 2 and 4 communicating with a common port P are caused to communicate with respective individual ports to form a three-port valve. The two-port valves 2 and 4 are constituted such that valve elements 24 and 44 are driven by pilot fluids Pa and Pb in pressure chambers 31 and 51 exerted on pistons 27 and 47, and the two-port valve consists of a pilot drive valve to felease respective valve seats 23 and 43. Besides, the pressure chamber 33 of the two-port valve 2 is caused to communicate with the pressure chamber 51 for the pilot fluid Pb of the trwo-port valve 4 and during a feed of the pilot fluid Pb, the two-port valve 2 is closed by a fluid pressure fed to the pressure chamber 33.
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