| 摘要 |
PROBLEM TO BE SOLVED: To regulate pressure of a liquid, to impart a function as a safety valve, to prolong a sealing life, to allow a smooth operation, and to reduce vibration and a noise. SOLUTION: When a pump is operated to make a liquid flow in from a communicated port 14, a differential pressure piston 41 is pushed up against a load of a coil spring 29. The pressurized liquid flows into a lower part of a piston sliding chamber 47 through the communication port 24. A piston 49 is pushed up thereby. Since the piston sliding chamber 47, an oil groove 59 and a communication port 53 are filled with a hydraulic fluid, pressure applied to the piston 49 is transmitted to the hydraulic fluid as it is. Substantially equal pressure is applied thereby to lower and upper parts of an O-ring 45 to enhance thereby sealability of the O-ring 45.
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