- Patent Title: MEMS thermal flow sensor with compensation for fluid composition
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Application No.: US15047839Application Date: 2016-02-19
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Publication No.: US09874467B2Publication Date: 2018-01-23
- Inventor: Thomas O. Maginnis , Nan Jou Pern , Zhengxin Zhao , Yongyao Cai , Yang Zhao
- Applicant: MEMSIC, INC.
- Applicant Address: US MA Andover
- Assignee: ACEINNA, INC.
- Current Assignee: ACEINNA, INC.
- Current Assignee Address: US MA Andover
- Agency: Preti Flaherty Beliveau & Pachios LLP
- Main IPC: G01F1/696
- IPC: G01F1/696 ; G01F1/684 ; G01F25/00 ; G01F1/688 ; G01F15/04 ; G01F1/36 ; 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.
Public/Granted literature
- US20160245681A1 MEMS THERMAL FLOW SENSOR WITH COMPENSATION FOR FLUID COMPOSITION Public/Granted day:2016-08-25
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