| 摘要 |
A valve position controller (10) for controlling the position of an industrial-valve element (29, 29') includes a check valve (72, 74) in each of closing and opening pressurized-fluid input lines (68, 70) for respectively leading pressurized fluids from a pressurized source (30) to closing and opening solenoid actuating valves (106, 104) via a common input fork (62). The valve position controller can be changed between a fail-in-place" mode, and a "fail-closed" mode by interchanging input and exhaust lines (68, 88) to an opening actuating valve (64) and reversing electrical operation of a solenoid (104) of the opening actuating valve. A needle valve (94) in a common exhaust line allows speed of the system to be optimized for a set resolution. Locking actuating valves (108, 110) are respectively between the closing and opening actuating valves and a motivator (34, 36) to lock the industrial valve element (29', 29) in position when close and open manual switches (48, 50) are not activated and an auto/manual switch (46) is in a "manual" position.
|
