| 摘要 |
PROBLEM TO BE SOLVED: To control flow rate in the state of making the change amount of manipulated variable of a manipulated variable commanding means almost proportional to the flow rate change rate without providing any special valve device for flow rate control for which the relative forms of valve element or valve seat are worked corresponding to conditions such as the character or flow rate range of a desired fluid to be controlled. SOLUTION: A valve device 1 for flow rate control is constituted so that a change amountΔE of moving amount E of valve element 1b, and a flow rate change rateΔQ/Q to be specified by the ratio between a flow rate change amountΔQ generated by that change amountΔE and a flow rate Q before the move of that valve element 1b are provided with characteristic relation not in proportional relation. Then, a flow rate control means 3 is constituted so as to operate a valve element driving means 1a by finding a target driving amount of valve element 1b corresponding to a manipulated variable S for setting the flow rate Q based on the characteristic relation of valve device 1 for flow rate control so that a change amountΔS of that manipulated variable and the flow rate change rateΔQ/Q can be in the almost proportional relation over the almost entire change range of manipulated variable S.
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