Patent ID: 6416033
Filing Date: 2002-07-09
Classification: F15B

Abstract:
A valve actuation system comprising:a valve stem position indicator arranged to sense a valve stem position in a working fluid valve; a coupling configured to relay information sensed in said valve stem position indicator; a high pressure circuit for circulating hydraulic fluid, said high pressure circuit comprising: a reservoir configured to contain hydraulic fluid; a pump possessive of a duty cycle, said pump comprising: an intake in fluid communication with said reservoir; and a discharge; an accumulator configured to be in pressurized fluid communication with said discharge; a hydraulic actuator configured to engage with said working fluid valve, said hydraulic actuator in fluid communication with said discharge and said accumulator such that it is mechanically responsive to changes in pressure caused by circulation of said hydraulic fluid; a servo valve configured to control movement of said hydraulic fluid between said pump, said accumulator and said hydraulic actuator, said servo valve comprising: a pneumatic fluid path; and a hydraulic fluid path in fluid communication with said pump, said accumulator and said hydraulic actuator; a trip manifold configured to facilitate retraction of said hydraulic actuator upon attainment of a preset condition; a low pressure circuit for circulating pneumatic fluid, said low pressure circuit comprising: a pneumatic fluid supply; a pneumatic positioner operably responsive to said valve stem position indicator through said coupling, said pneumatic positioner in fluid communication with said pneumatic fluid supply; and a solenoid operated valve in fluid communication with said pneumatic fluid supply and said trip manifold, said solenoid operated valve configured to selectively permit said pneumatic fluid from said pneumatic fluid supply to flow to said trip manifold; and a saturated fluid feedback circuit comprising: a shutdown manifold in fluid communication with said pneumatic positioner and said servo valve; and a binary valve in fluid communication with said trip manifold, said servo valve and said shutdown manifold, said binary valve configured to intermittently cut off flow of said hydraulic fluid to said servo valve.