US Patent 9316323 Hydraulic mechanism for valves

A valve assembly includes a first piston member displaceably disposed within a first chamber. A second piston member is coupled to a valve closure element, such as a diaphragm, and the second piston member is disposed within a second chamber. A longitudinal displacement of the first piston member relative to the first chamber causes hydraulic fluid disposed within the first chamber to longitudinally displace the second piston member such that the valve closure element engages a valve seat to close the valve assembly. The area of the second piston member is greater than that of the first piston member to multiply the force provided by an actuator that displaces a valve stem coupled to the first piston member.