Valves and valve actuation – Electrically actuated valve – Remote or follow-up control system for electrical actuator
Reexamination Certificate
2008-05-27
2008-05-27
Bastianelli, John (Department: 3753)
Valves and valve actuation
Electrically actuated valve
Remote or follow-up control system for electrical actuator
C251S129050, C318S599000, C361S160000
Reexamination Certificate
active
11083585
ABSTRACT:
A servomechanism includes a controller which dynamically estimates the resistance of the solenoid coil in an electrohydraulic valve as part of determining a level of electric voltage to apply to open the valve. The servomechanism receives a current setpoint designating a desired electric current level and senses the actual level of current flowing through the coil. A proportional term is derived from the current setpoint and the actual level of current. Creation of a derivative term is based on the difference between the current setpoint and the actual level of current. A feedforward term is produced by estimating the resistance of the electrohydraulic valve and limiting the feedforward term to a predefined range of acceptable values. The proportional term, derivative term, and the feedforward term are summed to define a desired voltage level, and a PWM signal for driving the electrohydraulic valve is generated based on the desired voltage level.
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Pfaff Joseph L.
Tabor Keith A.
Bastianelli John
Haas George E.
HUSCO International Inc.
Quarles & Brady
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