| 摘要 |
PROBLEM TO BE SOLVED: To linearly control a control valve independently of the inlet/outlet pressure changed of the valve. SOLUTION: A system for executing the PID control system of the control valve 2 so that a deviation between a flow rate command value Ws and a flow rate detection value Wd becomes zero is provided with pressure detectors 11, 12 for detecting the inlet pressure P1 and outlet pressure P2 of the valve 2 and a correction control part 13 for computing a correction variable 1/√(P1 -P2 ) from the pressure detection values P1 , P2 and controlling the valve 2 by correcting a valve aperture signalβoutputted from a PID control part 6. Since a numerical model for the valve 2 is expressed by W=(Cv /1.17)×√(P1 -P2 )×β, the valve 2 is controlled by correcting the valve aperture signalβby 1/√(P1 -P2 ), so that W=(Cv /1.17)βis formed independently of a change in the values P1 , P2 and a flow rate W is proportionated to the valve aperture signalβ. Thereby the flow rate W can be linearly controlled based upon the valve apertureβ. Provided that Cv indicates the capacity of the valve 2.
|
