Methods and apparatus to automatically determine friction of a control valve
AssigneeFisher Controls International LLC
InventorsMichael Fontaine, David Smid
Life of this patent
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Abstract
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.
Claims20
A method comprising:
- 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.
A method comprising:
- determining an average control hysteresis value for a valve over a first range of travel of the valve;
- comparing 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
- selecting one of multiple control step sizes for the valve based on the comparison.
An apparatus comprising:
- 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.
Dependencies are inferred from the claim text.