| 摘要 |
A ball valve comprising a valve box having inlet and outlet openings (1b, 1c), and a spherical valve body (2) rotatably arranged in the valve box and having a flow passage (7) communicated with the inlet and outlet openings so as to open and close the inlet and outlet openings of the valve box with rotation of the spherical valve body, the improvement comprising; a sub-valve plate (9) disposed respectively on the side of a close surface of the spherical valve body for closing the inlet and outlet openings to be in contact with and apart from the inlet and outlet openings, and pressing means (12, 14, 15) for pressing the backs of the sub-valve plates to close the inlet and outlet openings by the sub-valve plates. |
