Valves and valve actuation – Fluid actuated or retarded – Pilot or servo type motor
Patent
1976-08-19
1977-12-27
Geoghegan, Edgar W.
Valves and valve actuation
Fluid actuated or retarded
Pilot or servo type motor
60404, 60405, 60416, F16K 3112, F15B 1800, F15B 2000
Patent
active
040650944
ABSTRACT:
A hydraulic actuator for a gate or like valve such as the main steam isolation valve in an electric power plant characterized in that the actuator is a compact self-contained unit secured to the valve housing and comprises a hydraulic cylinder having its piston rod connected to the movable valve member to open or close the valve, an air-driven hydraulic pump for pressurizing dual hydraulic circuits (active and standby) each of which includes an accumulator, an air-piloted accumulator control valve, an air-piloted directional control valve for the hydraulic cylinder, and solenoid-operated pilot valves for said control valves in a pneumatic circuit including an air pressure reservoir. The hydraulic actuator is further characterized in that fast closing or opening of the valve is achieved by combined accumulator and pump discharge through the directional control valve and slow opening of the valve is achieved by pump discharge alone. A further characterizing feature of the hydraulic actuator herein is that in the event of electrical power failure, the actuator automatically rapidly closes the valve by the conjoint discharge of the active and standby circuit accumulators and pump discharge. If there is a loss of air pressure to the hydraulic pump and to the active and standby pilot circuits, the respective air reservoirs in the pilot circuits enable closing or opening of the valve by the active or standby accumulator discharge (when electrical power is available for operating the solenoid pilot valves) and automatic rapid closing of the valve by both accumulator discharges (when both air pressure and electric power are lost).
REFERENCES:
patent: 2396984 (1946-03-01), Broadston et al.
patent: 2942581 (1960-06-01), Gaffney
patent: 2974677 (1961-03-01), Natho
Geoghegan Edgar W.
Parker-Hannifin Corporation
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