| 摘要 |
PROBLEM TO BE SOLVED: To provide a butterfly valve preventing seal leakage by pressing a seal ring in a "thickness direction" and a "diameter enlargement direction", and also preventing inclination of the seal ring caused by rotation of a valve element.SOLUTION: In this butterfly valve, the seal ring 5 is pressed and mounted to the valve element 4 by a ring pressing arm 8 provided to a plate spring 7, and the seal leakage is prevented by applying pressing force in the "thickness direction" and "diameter enlargement direction" from the plate spring 7 to the seal ring 5. A relation between "pressing force F1 in the thickness direction" and "diameter enlarging force F2" which are applied to the seal ring 5 from the plate spring 7 is set to be F1>F2. Thereby, the "pressing force F1 in the thickness direction, which acts to prevent the inclination of the seal ring 5" surpasses, and such malfunction that the seal ring 5 is inclined is avoided. Also, since such a sandwich structure that the valve element 4 composed of a press-molded article, seal ring 5 and plate spring 7 are layered is employed, it is possible to suppress a pressure loss during a fully opening period. |
