The Research Of Digital Intelligent Vehicle Air Flow Sensor

As a part of the engine system, air flow sensor is of great significance for the EFI system.The flow sensor signal for a vehicle is a basic control signal of injection quantity and hasimportant influence on the power performance, economical efficiency, emission, especially onthe emission performance. As a kind of commonly used air flow sensors, thermal air flowsensor, which can directly measure the amount of air mass inflow without pressure andtemperature correction, has fast response and high accuracy of measurement, and it has beenwidely used into the vehicle.Combined with the existing conditions, according to the working principle of thermal airflow sensor, based on the principles of electrical engineering and electronic control theory, adigital intelligent air flow sensor is designed. Design includes selecting traffic detectionstrategies, determining the value range of sensor signal, designing circuit, designing controlsystem, packaging design. After the design is completed, select the appropriate electroniccomponents, and make the sensor samples. Meanwhile, modeling air flow sensor samples,according to the basic principle of heat transfer, a quantitative analysis is made on the sensingunit which contains convection, thermal conductivity, heat radiation and so are during thework. Finally, building the calibration test bench and test-bed, the prepared air flow sensorsample was calibrated and made a test of the flow detectionThe heat analysis result shows that during the sample sensor operation, forcedconvection is the main way of heat transfer on the sensing units and heat exchange increaseswith increasing flow, the proportion is also growing. Conduction and radiation heat transfersize is fixed, do not change with the flow, but occupy a certain proportion of the total heat onsensing unit, but the proportion decreases with increasing flow. Traffic flow detection resultsshowed good performance of digital intelligence air flow sensor samples which meets therequirements of the car, achieves the purpose of the design.