公开(公告)号：US09874467B2

公开(公告)日：2018-01-23

申请号：US15047839

申请日：2016-02-19

Applicant: MEMSIC, INC.

Inventor： Thomas O. Maginnis ,  Nan Jou Pern ,  Zhengxin Zhao ,  Yongyao Cai ,  Yang Zhao

IPC: G01F1/696 ,  G01F1/684 ,  G01F25/00 ,  G01F1/688 ,  G01F15/04 ,  G01F1/36 ,  G01N11/08

CPC classification number: G01F1/6845 ,  G01F1/36 ,  G01F1/688 ,  G01F15/046 ,  G01F25/0053 ,  G01N11/08

Abstract: The present invention provides a MEMS thermal flow sensor or meter for measuring the flow rate of a fluid without need for calibration of the flow sensor for that particular fluid. A response curve is determined by plotting the sensor output voltage against the volume flow rate divided by fluid thermal diffusivity for a calibration fluid of known thermal diffusivity, and storing response curve data in memory. A conversion factor is employed to provide a measure of correct flow rate of an unknown fluid. This conversion factor is derived from the ratio of the thermal time constant of the calibration fluid to the thermal time constant of the measured fluid, the time constants being measured at zero flow. These time constants are stored in memory. This conversion factor in conjunction with the response curve data is utilized by the processor to produce the correct flow rate. The invention also encompasses a method for measuring fluid flow rate of fluids of differing properties without necessity of a separate flow calibration for each fluid.

公开(公告)号：US20160245681A1

公开(公告)日：2016-08-25

申请号：US15047839

申请日：2016-02-19

Applicant: MEMSIC, INC.

Inventor： Thomas O. Maginnis ,  Nan Jou Pern ,  Zhengxin Zhao ,  Yongyao Cai ,  Yang Zhao

IPC: G01F1/684

CPC classification number: G01F1/6845 ,  G01F1/36 ,  G01F1/688 ,  G01F15/046 ,  G01F25/0053 ,  G01N11/08

Abstract: The present invention provides a MEMS thermal flow sensor or meter for measuring the flow rate of a fluid without need for calibration of the flow sensor for that particular fluid. A response curve is determined by plotting the sensor output voltage against the volume flow rate divided by fluid thermal diffusivity for a calibration fluid of known thermal diffusivity, and storing response curve data in memory. A conversion factor is employed to provide a measure of correct flow rate of an unknown fluid. This conversion factor is derived from the ratio of the thermal time constant of the calibration fluid to the thermal time constant of the measured fluid, the time constants being measured at zero flow. These time constants are stored in memory. This conversion factor in conjunction with the response curve data is utilized by the processor to produce the correct flow rate. The invention also encompasses a method for measuring fluid flow rate of fluids of differing properties without necessity of a separate flow calibration for each fluid.

Abstract translation: 本发明提供一种用于测量流体流速的MEMS热流量传感器或仪表，而不需要校准该特定流体的流量传感器。 通过将传感器输出电压与已知热扩散系数的校准流体的体积流量除以流体热扩散率相加，并将响应曲线数据存储在存储器中来确定响应曲线。 使用转换因子来提供未知流体的正确流量的量度。 该转换因子来自校准流体的热时间常数与测量流体的热时间常数的比率，时间常数是在零流量下测量的。 这些时间常数存储在内存中。 该转换系数与响应曲线数据一起被处理器利用以产生正确的流速。 本发明还包括用于测量不同性质的流体的流体流速的方法，而不需要对每种流体进行单独的流量校准。