Development Of Automobile Air Flow Meter Calibration System Based On The Theory Of Wind Tunnel

At present,the quality and measurement precision of domestic automobile air flow meter are comparatively low, and the flow-output voltage characteristic is instability.The accuracy of various calibration systems is pool.Considering the present situation, this paper puts forward a new calibration system based on the wind tunnel principle.This paper firstly introduces the development status of automobile air flow meter calibration system, the method of flow measurement and calculation, and the calibration principle. Then, emphatically expounds the integral design of the system, selection and design of hardware, and the design of software function.Finally, lists the conclusion and innovation points of this calibration system.This calibration system including three components, flow measurement and controlling, calibration temperature measurement and controlling, and automobile air flow meter calibration.The continuous adjustable stable airflow is produced by the fan ,which is controlled by the frequency converter.Various kinds of transmitters are installed in different positions of calibration system to measure flow-related parameters,such as temperature,differential pressure and absolute pressure. After fixed by the algorithm in the software, all of the parameters are used to calculate the air mass flow. The temperature measured by the temperature transmitter is directly displayed on the meter, and the intelligent auto-tuning PID control instrument controls the heating device to reach the stable calibration temperature. Begin with static, whenever flow stabilized in a calibration point, interpolation calculation model will be analysis and calculated through software, and then written in the nonvolatile storage space by the communication controller.All the measurement, communication, calibration are controlled by computer completely, which eliminates various deviations caused by human factors, and the accuracy and stability of the system are guaranteed.In order to adapt to the actual need of mass production, this system sets two calibration pipelines to achieve calibration incessantly.Each of the calibration pipelines has 8 calibration sockets and can simultaneously calibrate 8 automobile air flow meters. In ensuring the accuracy of the calibration, this system can greatly improve the calibration efficiency and realize the rational utilization of resource.