| 摘要 |
PURPOSE:To prevent generation of hydraulic self-oscillation without flawing seal surfaces and producing delay in control by constituting a valve such that the receprocating motion of a seal ring at the upstream side becomes larger than that at the dwonstream. CONSTITUTION:Considering displacement delta of a valve body sealing portion due to hydraulic pressure in a valve body 2, stroke S2 of a seal ring 9 at the downstream side is enlarged larger than stroke S1 of a seal ring 8 at the upstream side by the displacement delta of the valve body sealing portion or more. Since a seal gap G5 at the downstream side can be ensured to be at least a predetermined gap G01 even if the valve body 2 is displaced to the downstream side, the seal surface at the seal ring side or valve body side can be prevented from flaws caused by abutment of the seal ring 9 against the valve body 2 even if the valve body 2 is pivoted in the opening direction under such condition. |
