Research Of Automotive Air Quality Flow Sensor

Intake air flow in internal combustion engine is a very important measuring parameters, because the air-fuel ratio regulation of engine is adjusting the injection quantity matching with the subsystem, So can electronic gasoline injection system accurately measure the subsystem, then control the air-fuel ratio, determines the engine power, economy and emission performance indicators.The key to Electronic Fuel Injection System of automobile engine is the accurate measurement of air mass flux in manifold in order to maintain an optimal air-fuel ratio. For many air flow meters, the thermal film based air flow meter develops very rapidly and begins to be applied to automobile widely, due to its many advantages such as no mechanical transmission, no pressure compensation, quick response and high sensitivity. The main research contents of this thesis are as follows:Through the performance analysis and contrast among the hot film type mass air flow sensor, the hot film type mass air flow sensor is one of the best performance vehicle air flow sensor Detailed analysis the basis of the theoretical basis and heat transfer of the hot film type mass air flow sensor, and the working principle of sensor, and the fundamental structural studied. After the analysis and comparison, the advantage of the hot film type mass air flow sensor used in the automobile are discussed.After we master the theory knowledge of the hot film type mass air flow sensor, this paper adopts MEMS technology making the hot film type mass air flow sensor. Fist design a kind of integrated type sensor head of the sensor to make the structure more simple, then design a diagram controlled by microcomputer, which direct control heating electric current. Emphatically expounds the choice of sensing unit chip materials and processing procedures. Finally, using the finite element analysis software to do the temperature field of thermal analysis on design sensor, and optimize the structure of the sensor chip designThrough the research of the hot film type mass air flow sensor, The purpose is master manufacture process and MEMS technology of the sensor, Based on the structure and control circuit sensor of improvement, improve the performance of this product, popularizing this product in domestic applications.