公开(公告)号：US6012474A

公开(公告)日：2000-01-11

申请号：US850895

申请日：1997-07-24

申请人： Masaki Takamoto ,  Shinichi Nakao ,  Masahiro Ishibashi ,  Yoshitaka Ina ,  Yoshikazu Yokoi ,  Masao Hayakawa

发明人： Masaki Takamoto ,  Shinichi Nakao ,  Masahiro Ishibashi ,  Yoshitaka Ina ,  Yoshikazu Yokoi ,  Masao Hayakawa

IPC分类号： G05D7/06 ,  F16K24/04 ,  F17D1/16

CPC分类号： G05D7/0635 ,  Y10T137/0396 ,  Y10T137/7759 ,  Y10T137/7761

摘要： A control circuit (20) of a mass flow control device (1) retains the relation (Cd=f(ReTH)) between the Reynolds number and the actual discharge coefficient of a sonic nozzle (13) in the area where the Reynolds number is small. In such an area, the sonic nozzle can be used as a variable mass flow element for controlling mass flow rate. If a pressure Pu and a temperature Tu of an upstream fluid of the sonic nozzle 13 are detected, the theoretical mass flow rate QmTH and the theoretical Reynolds number ReTH can be calculated; since the actual discharge coefficient Cd can be calculated by the above relationship Cd=f(ReTH) based on the calculated Reynolds number, the actual mass flow rate Qm can be calculated based on the relation of Qm=Cd.multidot.QmTH. In the control circuit 20, in order to obtain the predetermined mass flow rate Qm, the upstream fluid pressure Pu and temperature Tu of the sonic nozzle are obtained based on the above relationship, and a variable valve (12) is driven so that the mass flow rate may have this value. Since the properties of the sonic nozzle can be made full use of, it is possible to control trace amounts of mass flow rate with extremely high accuracy.

摘要翻译： 质量流量控制装置（1）的控制电路（20）保持雷诺数与声波喷嘴（13）的实际排放系数之间的关系（Cd = f（ReTH））在雷诺数为 小。 在这样的区域中，声波喷嘴可以用作用于控制质量流量的可变质量流量元件。 如果检测到声波喷嘴13的上游流体的压力Pu和温度Tu，则可以计算理论质量流量QmTH和理论雷诺数ReTH; 由于可以根据计算的雷诺数根据上述关系Cd = f（ReTH）来计算实际的放电系数Cd，所以可以基于Qm = CdxQmTH的关系来计算实际的质量流量Qm。 在控制电路20中，为了获得预定质量流量Qm，基于上述关系得到声波喷嘴的上游流体压力Pu和温度Tu，并且驱动可变阀（12），使得质量 流量可能有这个值。 由于可以充分利用声波喷嘴的特性，所以可以极高精度地控制痕量的质量流量。