| 摘要 |
<p>PROBLEM TO BE SOLVED: To secure high control precision by improving the control precision of the flow rate controller and making the device smallsized, and switching the operation to manual operation or automatically stopping the flow rate controller from operating if conditions under which a flow rate can be measured are not met. SOLUTION: The controller comprises a control valve 2 and an orifice corresponding valve 9 which are provided on the upstream and downstream sides of an orifice 5, a primary pressure detector 3 and a secondary pressure detector 11 which are provided on the upstream and downstream sides of the orifice 5, a flow rate arithmetic unit 6 which calculates the flow rate from Qc=KP1 (Kno constant) based upon the detected pressure P1 of the primary pressure detector 3 and outputs the difference between a flow rate command signal Qs and the calculated flow rate Qc as a control signal Qy, and a pressure comparison arithmetic unit 10 which operates the detected pressure ratio P2 /P1 of primary pressure and secondary pressure, and controls the pressure P1 by opening or closing the control valve 2 to control the orifice downstream-side flow rate.</p> |
