| 摘要 |
A novel butterfly valve is provided herein. The butterfly valve is of the type having a spherical protuberance formed on a valve stem connected to a valve body, the spherical protuberance being supported in a support member mounted in a casing, the valve body being engageable with, and disengageable from, a valve seat through pivotal movement and rotational movement of the valve stem about the spherical protuberance so that the valve body is rotatable when it is away from the valve seat. The butterfly valve comprises a drive shaft disposed at a location adjacent to the outer end of the valve stem and extending outward therefrom, the drive shaft being rotatable in forward and reverse directions and reciprocatable in longitudinal directions of the valve stem. One end of the drive shaft is connected to the outer end of the valve stem to enable the valve stem to rotate in cooperation with the reciprocating movement of the drive shaft in the longitudinal directions thereof. A packing member is provided for shaft sealing with respect to the drive shaft, the packing member being disposed between the drive shaft and an outwardly-extending portion of the valve casing, for covering the outer peripheries of the valve stem and of the drive shaft. This structure assures more complete shaft sealing without causing any inconvenience to the controllability of the valve body and valve stem and can thus advantageously prevent fluid from leaking outwardly of a valve casing. |
