| 摘要 |
<p>Provided is an improved pressure-type flow rate control apparatus that can control the flow rate of a fluid with great precision using an empirical formula. The empirical formula can provide values that closely fit with the actual flow rates of a compressible fluid under non-critical conditions. <??>The improved pressure-type flow rate control apparatus can control the flow rate of fluid passing through an orifice 4 to a target flow rate with accuracy and at a high speed. The empirical formula for the compressible fluid under non-critical conditions (sub-sonic) is expressed as Qc = KP2<m>(P1 - P2)<n> and the flow rate of fluid passing through orifice 4 is calculated by: <DF>Qc = KP2<m>(P1 - P2)<n> </DF> (K is a proportional constant; and m and n are constants) so that the flow rate of fluid passing through the orifice 4 can be controlled to the target flow rate with high precision at a high speed. <??>Also provided is an improved pressure-type flow rate control apparatus in which a pressure ratio P2/P1 = r, obtained from an upstream pressure P1 and a downstream pressure P2 is constantly compared with a critical value rc, and under critical conditions (r≤rc), the flow rate is calculated by : <DF>Qc = KP1. </DF> Under non-critical conditions (r > rc), the flow rate is calculated by Qc = KP2<m>(P1 - P2)<n>, so that the flow rate is controlled to the target flow rate with accuracy at a high speed depending upon the conditions of fluid. <IMAGE></p> |
