Design And Research On Drying Efficiency Detection System Of Automotive Air Dryer

Automotive air dryers are important components in the air brake systems large passenger car or truck.Their drying capacity and drying efficiency directly affect the performance and service life of the air brake system.At present,domestic manufacturers only perform simple pressure characteristic tests on automobile air dryers,and the test items do not include drying efficiency.Foreign drying efficiency testing equipment is expensive,and it is difficult to learn from them due to the implementation of technical barriers in China.In response to the above problems,based on the recently released industry standards,an automatic detection system for the drying performance of automotive air dryers was designed.The research mainly includes:(1)According to the industry standard QC/T996-2015 "Automobile air dryer performance requirements and bench test method",analyzed the demand of the detection system,and determined the performance test items including drying efficiency,and put forward the system technical design indicators such as system withstand voltage,sensor measurement range and accuracy,and temperature and humidity deviation.Based on the analysis,test tubes were designed for each test item,which realized automatic detection of air dryer drying efficiency,inlet and outlet pressure difference,inlet flow rate and high temperature durability.(2)According to the demand analysis of the detection system,an environmental simulation gas source system based on air heater,saturator,steam separator and mixer was designed.PID control feedback heater and electric control valve,which realized the precise control of the temperature and humidity of the gas source,and the electric proportional valve realized the constant flow by controlling the high pressure,which meet the gas source conditions that high temperature,high humidity and high pressure required for the drying performance test of the dryer.By adjusting the opening degree of the proportional flow valve,the adjustable load volume could be simulated to achieve automatic control of dew point drop and load rate,which achieved the drying capacity and drying efficiency test requirements of the dryer.(3)According to the overall scheme,the hardware part of the detection system was designed,including analysis and design selection of data acquisition and control system,gas circuit components,and hardware circuit.Based on LabVIEW programming environment,the software part of the detection system was designed,including the modules of parameter configuration,data acquisition,performance testing,data management and saving,and designed human-computer interaction interface,which realized coordinated control of each hardware module,and completed the automatic operation of each detection item.(4)Through repeatability tests based on iterative method,the test curve and test data were recorded,and the measurement uncertainty was evaluated for each test item.The test results show that the system can accurately control the gas source temperature(room temperature~80°C),humidity(0~100%RH),pressure(0~1.6MPa),and meet the gas source conditions required for the dryer drying efficiency test;Automatically adjustable load air volume(45.7L~339.7L)enables control of dew point drop and dryer load rate.The drying efficiency test uncertainty meets the system testing requirements.