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Study on Surface Acoustic Wave Air Flow Sensor for Vehicle

Air-fuel ratio, a major parameter of petrol engineer, directly affects the power, economy and indicators of exhaust emission of engine. To make the air-fuel ratio in the best state, the air flow entering into cylinder must be measured accurately. Due to gaseous property of air itself, the flow detection is greatly interfered by temperature and pressure. In the article, we used surface acoustic wave(SAW) technique combined with temperature and pressure compensation and made a detection device for engine intake, which was less interfered by temperature and pressure with high accuracy and wide measuring range. The paper introduced the working principle of SAW air flow sensor and its mathematic model, and discussed the development, signal detection and error processing of sensor. The results showed that SAW sensor could better overcome the interference of temperature and pressure, and then accurately got the air flow value of engine with preferable repeatability and reliability.