| 摘要 |
PURPOSE:To aim at improvements in sealing capacity in time of cutting off a flow of fluid, by notching a side face at the fluid opposite side of a cutoff part formed in the side face in a way of thinning its thickness in the fluid flow direction an and around a contact-seating part. CONSTITUTION:When a plug 20 is made to go down together with a valve shaft 18 and thereby the lower end of a cutoff part 20b contacts and takes a seat on the peripheral surface of a valve inner hole 3a, a flow passage is fully closed and cut off. At this time, clamping force being added to the valve shaft 18 acts on the plug 20 through a driving device. Therefore, the cutoff part 20b is forcibly pressed to the peripheral surface of the valve inner hole 3a but a thinned part 20e is formed in this cutoff part 20b whereby flexibility is given to it, so that the thinned part 20e is gradually deformed in proportion to the pressure contact and gets to fit a fluid passage by degrees, thus sealability is secured. |
