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Proceedings Paper

Self diagnosis for hot film airflow mass microsensors
Author(s): Lifu Li; Fan Fan
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Paper Abstract

A self-diagnosis method for hot film airflow mass microsensor has been developed for the vehicle air intake. Based on the theory of heat transfer and airflow mass rate measurement for internal combustion engines, a hot film airflow mass microsensor with self-diagnosis capability is designed. It is composed of a heat sensing unit, a temperature sensing unit using a Heraeus silicon, a signal processor, a converters, a heater, a heating controller and a computer. The temperature sensing unit is split into a heater upstream temperature sensing resistor and a heater downstream temperature sensing resistor according to the air intake flow direction. From both theory and experiments, the relation between the heat transfer rate of the heater and the airflow mass rate at the air intake are deduced under the working conditions of a certain engine, and the temperature distribution rules in the heater surface, heater upstream and heater downstream are obtained. These relations are regarded as a reference model for the self-diagnosis in the microsensor. Finally, the failure of the microsensor can be detected by comparing the real-time measurement model with the reference model. Thus, this method can not only measure mass airflow rates in real time, but also inspect diagnosis faults of the heat sensing unit and the temperature sensing unit automatically.

Paper Details

Date Published: 31 December 2008
PDF: 7 pages
Proc. SPIE 7130, Fourth International Symposium on Precision Mechanical Measurements, 71301B (31 December 2008); doi: 10.1117/12.819585
Show Author Affiliations
Lifu Li, South China Univ. of Technology (China)
Fan Fan, South China Univ. of Technology (China)

Published in SPIE Proceedings Vol. 7130:
Fourth International Symposium on Precision Mechanical Measurements
Yetai Fei; Kuang-Chao Fan; Rongsheng Lu, Editor(s)

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