PRESSURE-OPERATED CONTROL VALVE

摘要

[Problem] In a pressure-operated control valve having a configuration in which a valve body is pushed against a valve seat by a spring force of a diaphragm, and when the diaphragm starts being deformed by a setup pressure of fluid, the valve is open, a liquid leak upon an initial deformation of the diaphragm is prevented. [Means for solving problem] A ball valve 2 and a valve shaft 3 are arranged in a valve chamber 13. The ball valve 2 opens and closes a valve port 14. A coil spring 5 is arranged in a spring chamber 16. The coil spring 5 pushes the valve shaft 3 against a diaphragm 7 via a spring bracket 31 of the valve shaft 3. A corn portion 71 and a flat portion 72 (or a concave portion) arranged at an inside of the corn portion 71 are formed on the diaphragm 7. A diameter of a diaphragm-side end face 3A of the valve shaft 3 is larger than a diameter of the flat portion 72 of the diaphragm 7. When the diaphragm 7 is initially deformed, a boundary portion 74 interposed between the corn portion 71 and the flat portion 72 abuts on the diaphragm-side end face 3A.