| 摘要 |
PROBLEM TO BE SOLVED: To prevent leakage of a fluid from a seat ring portion to the outside, in a butterfly valve. SOLUTION: Step portions 21, 22 are formed along a peripheral portion of a valve element 19. The step portions 21, 22 comprises: a seat ring 23 made of elastic material and made press-contact with/separated from an inner circumferential face of a valve casing, and a seat pressing ring 24 pressing the seat ring 23 in a thickness direction of the valve element 19 to hold it in the step portions 21, 22. An inner circumference 24a of a seat pressing ring 24 and an outer circumference 22a opposed to the inner circumference 24a are formed in a screw shape to be engaged with each other. Thereby, a valve casing 16 is brought into contact with a pipeline 11 neighboring the valve casing 16 at a flat contact face to prevent leakage of a fluid outside. Making the seat pressing ring 24 moves forward and backward can generate bearing pressure in which the leakage of a fuel between the seat ring 23 and the valve body 19 is prevented.
|
