Valve operator circuit with provision for presetting
AssigneeSun Oil Company of Pennsylvania
InventorRobert Mayer
Life of this patent
Estimating the term…
Abstract
A valve operator circuit normally operates to compare the pulse rates of two trains of pulses and to step an associated valve open or closed depending on which of the two pulse rates is the higher. The circuit includes a manually-operated presetting arrangement which, when operated, causes the normal pulses to be inhibited from moving the valve, and causes the valve to move to a desired position.
Claims7
A control system for maintaining a process control element at a predetermined position, comprising:
- a. reversible motor means for moving the process control element between positions;
- b. a first control channel for energization of the motor in one sense in response to application of signals to said channel;
- c. a second control channel for energization of the motor in another sense in response to the application of signals to said second channel;
- d. means for developing a voltage whose amplitude is representative of the position of the process control element;
- e. means for producing a continuous presetting signal;
- f. means, responsive to a developed voltage from said voltage developing means which is less than a predetermined voltage, for connecting the presetting signal producing means to one of the control channels so that the motor is energized in one sense;
- g. means, responsive to a developed voltage from said voltage developing means which is greater than the predetermined voltage, for connecting the presetting signal producing means to the other control channel so that the motor is energized in the other sense.
In a system for controlling the position of a process control element in response to at least two control signals, a first signal being a command signal and the second being a feedback signal indicating the actual condition of the process being controlled, said system having:
- a. reversible motor means for moving the process control element;
- b. a first control channel for receiving command signals;
- c. a second control channel for receiving feedback signals;
- and
- d. means for comparing the command and feedback signals from the first and second control channels for actuating the reversible motor so that the process control element position is adjusted in accordance with the difference between the command and feedback signals to achieve like command and feedback signals;
- an improvement for prepositioning the process control element to a predetermined position before normal operation of the process control element and the comparing means is commenced, said improvement comprising:
- e. means for inhibiting any command and feedback signals on the first and second control channels, respectively;
- f. means for developing a voltage whose amplitude is representative of the position of the process control element;
- g. means, responsive to a developed voltage which is less than a predetermined amplitude, for applying signals to one of the control channels so that the motor is energized in one sense;
- and
- h. means, responsive to a developed voltage which is greater than the predetermined amplitude, for applying signals to the other control channel so that the motor is energized in the other sense.
Dependencies are inferred from the claim text.