| 摘要 |
PROBLEM TO BE SOLVED: To restrict the influence of the viscosity of hydraulic fluid on valve operation in an air vent valve for discharging the air contaminated in the hydraulic fluid for transmitting the driving force to a diaphragm of a diaphragm pump. SOLUTION: A sleeve 22 has a shaft hole 28 for communicating a fluid pressure chamber with an atmospheric air side. A valve element 38 has a spool 34 to be slid along the shaft hole 28 and valve heads 30 arranged in both end of the spool 34 so as to regulate the sliding range of the valve element 38. Any one of the valve heads can be seated in a valve seat 32 provided in each sleeve end so as to cut the communication between the fluid pressure chamber and the atmospheric air side. Flow passages 40, 42 are provided in the spool 34, and when the valve element 38 exists within the predetermined range, this flow passage communicates both the ends of the sleeve 22 with each other. When pressure of the fluid pressure chamber rises, the valve element is moved upward, and the contaminated air inside of the fluid pressure chamber is discharged through the flow passage on the way of the upward movement of the valve element 38.
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