Fisher Controls International LLC

Michael R Fontaine

David Lee Smid

Davin Scott Nicholas

Gregory Robert Bulleit

Christopher C Arnold

Kenneth William Junk

Kurtis K Jensen

Christopher Steven Metschke

Methods and apparatus for quantifying pneumatic volume usage via valve controllers are disclosed. An example apparatus includes a valve controller operatively couplable to a pneumatic actuator, the pneumatic actuator being operatively coupled to a control valve. In response to an input signal indicating that a flow control member of the control valve is to be moved in a specified direction, the valve controller commands a current-to-pressure (I/P) converter of the valve controller to pulse a relay valve of the valve controller between a closed position and an open position. The pulsing of the relay valve causes the pneumatic actuator to move the flow control member in the specified direction. The valve controller calculates a pneumatic volume usage associated with the moving of the flow control member in the specified direction. The pneumatic volume usage is based on the pulsing of the relay valve.

Methods and apparatus for quantifying pneumatic volume usage via valve controllers

Methods, apparatus, systems and articles of manufacture are disclosed for automatically determining friction of a control valve. An example method includes measuring first and second pressures corresponding to respective first and second positions of a valve while stroking the valve in a first direction, measuring third and fourth pressures corresponding, respectively, to the second and first positions while stroking the valve in a second direction opposite the first direction, determining a first pressure difference between the second and third pressures, determining a second pressure difference between the first and fourth pressures, determining an average pressure based on the first and second pressure differences, comparing the average pressure to a third pressure difference corresponding to a range of travel of an actuator including the first and second positions, and determining a control step size for the valve based on the comparison.

Methods and apparatus to automatically determine friction of a control valve

Methods and apparatus to detect and/or recover from failures in valve control devices. An apparatus includes an input signal generator to provide a digital input signal to a first converter. The first converter corresponds to one of a supply converter or an exhaust converter. The supply converter controls actuation of a supply relay to deliver pressurized fluid to an actuator operatively coupled to a valve in a process control system. The exhaust converter to control actuation of an exhaust relay to exhaust the pressurized fluid from the actuator. The digital input signal triggers application of a current to the first converter to open the first converter. The apparatus further including a failure detector to: determine a difference in at least one of a pressure in the actuator or a position of a flow control member in the valve; and detect a failure when the difference satisfies a failure threshold.

Methods and apparatus to detect and/or recover from failures in valve control devices

Methods, apparatus, systems and articles of manufacture are disclosed for automatically determining friction of a control valve. An example apparatus includes a hysteresis measurement controller to determine an average control hysteresis value for a valve over a first range of travel of the valve, a comparator to compare the average control hysteresis value to a second value corresponding to a second range of travel of the valve encompassing the first range of travel of the valve, and a step size selector to select one of multiple control step sizes for the valve based on the comparison.

Techniques for diagnosing failures in a digital solenoid I/P converter are provided herein. A controller of the I/P converter may apply a fixed voltage to an I/P coil of the I/P converter, causing an armature to move from an off-position to an on-position in a properly-functioning I/P converter. The controller may receive an indication of whether a digital logic line trip has occurred, indicating that a current for the I/P coil has reached a desired maximum current level. The controller may remove the fixed voltage applied to the I/P coil when the maximum current level is reached or when a threshold period of time has elapsed from the application of the fixed voltage to the I/P coil. The controller may diagnose, based on whether the digital logic line trip occurred prior to removing the fixed voltage, a failure in the I/P converter.

Open circuit diagnostic for pulsed solenoid I/P

Techniques for diagnosing failures in a digital solenoid I/P converter are provided herein. A controller of the I/P converter may apply a fixed voltage to the I/P converter, causing an armature to move from an off-position to an on-position in a properly-functioning I/P converter. The controller may receive an indication of whether a digital logic line trip has occurred, indicating that a current for the I/P coil has reached a desired maximum current level, and an elapsed time from the application of the fixed voltage. The controller may compare the amount of time elapsed from the application of the fixed voltage to an expected amount of elapsed time from the application of the fixed voltage to the I/P coil after which a digital logic line trip will occur for a properly functioning I/P coil and diagnose, based on the comparison, a failure in the I/P converter.

Diagnostic for pulsed solenoid I/P functionality

Example electro-pneumatic converters and related methods are disclosed herein. An example electro-pneumatic converter includes an axial passageway defined in a body between a first opening and a second opening. A supply port is formed by the first opening. The supply port is to receive pressurized fluid from a pressure supply source. The electro-pneumatic converter further includes an output port fluidly coupled to the axial passageway and a solenoid including a coil and an armature. The armature is disposed in and movable in the axial passageway. The armature is movable between a first position blocking the pressurized fluid from flowing through the axial passageway between the supply port and the output port and a second position allowing the pressurized fluid to flow through the axial passageway between the supply port and the output port.

Electro-pneumatic converters and related methods

A control loop for a double-acting pneumatic actuator is configured to generate two control signals, one for each of the two pneumatic chambers for the purpose of controlling the actuator position in view of operating constraints on the chamber pressures or the stiffness of the actuator. A numerical indicator of the stiffness may be computed in a variety of ways, for example, as the average of the two chamber pressures. In one embodiment a numerical indicator of stiffness is treated as an output of the system along with the position of the actuator. A multi-input multi-output control loop with position and pressure feedback may be used to simultaneously control the position and the stiffness of the actuator.

Method and apparatus for controlling a double-acting pneumatic actuator

Systems and methods may be provided to digitally control both position and crossover pressure in a double-acting pneumatic actuator, in view of constraints (e.g., a deadband range comprising a set point) set on the crossover pressure. Control may be achieved, via a control algorithm (e.g., a Multiple Input Multiple Output (MIMO) control algorithm) acting upon inputs of actuator position feedback and crossover pressure feedback (e.g., as indicated by pressure feedback of each respective pneumatic chamber). Further, the embodiments described herein may reduce the necessary frequency of control actions for adjusting crossover pressure, thus reducing wear on process components, and allowing for finer control of actuator position.

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Marshalltown, IA, United States of America

Michael R Fontaine