BALL VALVE

摘要

A ball valve (10) comprises a main opening (14) and an auxiliary opening (14A) which serve as an opening on an inflow side of a passing hole (13) of a ball (12), and a sector opening (15) which serves as an opening on an outflow side of the passing hole. The passing hole (13) comprises a tapered flow passage surface (13A) extending from the main opening (14) to the sector opening (15). When a valve is fully closed, a tip end portion (15A) of the sector opening (15) is set in a first sealing region (17A) defined by an outflow side sealing member (17) immediately near an outlet flow passage (11B), and when the valve is fully opened, the tip end portion (15A) of the sector opening (15) is set to enter across the outlet flow passage (11B) into a second sealing region (17A) defined by the outflow side sealing member (17). The auxiliary opening (14A) makes an inlet flow passage (11A) communicate with the passing hole (13) when the tip end portion (15A) of the sector opening (15) passes the first sealing region (17A) to start opening the valve, and the main opening (14) makes the inlet flow passage (11A) communicate with the passing hole (13) after the valve begins to open, whereby a fluid is rapidly started to flow after a valve opening action performed by an operating unit, a zone, in which the fluid is controlled by the opening unit, is made large and an accuracy of fluid control is improved.