Power plants – Pressure fluid source and motor – Ram driven by fluid pumped from reservoir
Reexamination Certificate
1999-04-29
2001-08-21
Nguyen, Hoang (Department: 3748)
Power plants
Pressure fluid source and motor
Ram driven by fluid pumped from reservoir
C091S006000, C091S461000
Reexamination Certificate
active
06276135
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to hydraulic emergency shut-down systems (ESD) for actuating closure of valves.
BACKGROUND OF THE INVENTION
Several emergency shut down systems are known in the art such as the ESD sold by Erichsen, the ESD sold by Bettis of Houston, USA, the RA-Presco™-Dyne ESD sold by Barber Industries, of Edmonton, Canada, and U.S. Pat. No. 5,341,837 of Johnson. U.S. Pat. No. 4,961,560 Ellett-Two Way Latching Trip Valve. U.S. Pat. No. 5,070, 00 Johnson-Safety Valve Actuator. U.S. Pat. No. 5,213,133 Ellett-Pilot Control Valve. U.S. Pat. No. 5,291,918 Johnson-Safety Valve Actuator. U.S. Pat. No. 5,464,040 Johnson-Safety Valve Actuator. These devices typically include a pilot valve that senes pressure in a flow line. When the pressure moves out of a pre-defined range, the pilot valve signals an actuator to close a valve and shut down flow in the flow line. These devices typically have a high pressure line and a low pressure line. The high pressure line is used to actuate the actuator, while the low pressure line is controlled by the pilot valve.
SUMMARY OF THE INVENTION
The use of dual high and low pressure controls unnecessarily complicates the design of the ESD. This invention provides a novel ESD that includes a single pressure line for control functions at the pilot valve and actuator.
There is therefore provided in accordance with an aspect of the invention, a hydraulic control circuit for a hydraulic actuator, including a high-low pilot valve having a sensing port for connection to a flow line. A single pressure line connects the high-low pilot to a hydraulic actuator. A second line connects the high-low pilot to a reservoir. A normally closed relief valve is connected to the single pressure line for relief of excessive pressure. A normally closed override valve is connected to the single pressure line for manual override of circuit controls. And a pump is connected to the single pressure line for pressuring the single pressure line.
In a further aspect of the invention, the hydraulic control circuit has a normally open time out valve on the single pressure line, the time out valve being set to close a pre-set time interval after being manually activated. In a further aspect of the invention, the override valve is connected to the single pressure line between the time out valve and the hydraulic actuator. The relief valve is preferably connected to the single pressure line between the time out valve and the hydraulic actuator. The override valve, relief valve and the pump are preferably connected between the first line and the reservoir.
In addition, this invention provides a novel configuration of pilot valve and time out valve.
These and other aspects of the invention are described in the detailed description of the invention and claimed in the claims that follow.
REFERENCES:
patent: 3800537 (1974-04-01), Denis
patent: 4676140 (1987-06-01), Haussler
patent: 4961560 (1990-10-01), Ellett
patent: 5070900 (1991-12-01), Johnson
patent: 5213133 (1993-05-01), Ellett
patent: 5291918 (1994-03-01), Johnson
patent: 5341837 (1994-08-01), Johnson
patent: 5464040 (1995-11-01), Johnson
patent: 5522212 (1996-06-01), Kubik
Abstract of U.S. Patent No. 4,921,207, issued May 1, 1990, Baker, 1 page.
Sigma Enterprises, Inc. product brochure entitled “Combination Hi/Low Bleeder Pilot”, 1997 Technical Product Bulletin, 3 pages.
Erichsen product brochure entitled “Self Contained Hydraulic Shutdown System”, at least as early as Oct. 1989, 3 pages. Inventor has seen earlier versions but does not have copies.
Bettis Actuators & Controls, product brochure entitled “PressureGuard™ Self-Contained Hydraulic Emergency Shutdown Systems”, printed Sep. 1995, 6 pages.
Barber™ Industries Ltd. product brochure entitled “RA-PRESCO-DYNE Self Contained Emergency Shut Down System For Reverse Acting Gate Valves”, Bulletin 680, printed Aug. 1991, and Operating Manual for Hydraulic Operated-Spring Opposed Valve Actuation Systems, printed Feb. 1993, 15 pages. Advertising for RA-PRESCO-DYNE system appeared in Oilweek magazine, Canada, in Sep. 1977.
Barber™ Industries Ltd. C-HL-Presco Pilot 1991+10+28, and Type C-HL-Presco Pilot, Model 5398, 14+Nov.+1991, 2 pages.
Barber™ Industries Ltd. product brochure entitled “Presco-Pilot”, 10/91, 4 pages.
“New pressure control pilot solves a pollution problem,” Jim Ellett, Oilweek, Canada, Sep. 20, 1971.
Argus Machine Co. Ltd.
Lambert Anthony R.
Nguyen Hoang
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