Memsic Transducer Systems Co., Ltd.

Aceinna, Inc.

Nan Jou Pern

Yang Zhao

Yongyao Cai

Thomas O Maginnis

Zhengxin Zhao

Ohlan Silpachai

A flow sensing module with a bypass channel is provided. The flow sensing module may include a body portion and a flow sensor. The body portion may include a main fluid inlet, a main fluid outlet, a main fluid channel extending between the main fluid inlet and the main fluid outlet, a bypass fluid inlet and a bypass fluid outlet each configured to be in communication with the main fluid channel, and a bypass fluid channel extending between the bypass fluid inlet and the bypass fluid outlet. The flow sensor may be disposed in the bypass fluid channel to sense a flow rate of a fluid in the bypass channel. No pressure drop element is disposed in the main fluid channel, so the main fluid channel may have a pressure loss of a very small value. Moreover, linearity and sensitivity of the flow sensing module may also be improved.

Flow sensing module with bypass channel

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.

MEMS thermal flow sensor with compensation for fluid composition

Growing community of inventors

Andover, MA, United States of America

Nan Jou Pern