| In order to accurate and efficient completion of the vehicle air-conditioner defrosting and demisting tests,the virtual test system for the vehicle Air-conditiner Defrosting and Demisting performance Test(i.e.ADDT)was developed,in which the relative domestic and foreign defrost and demist performance test standards were taken into consideration.In this paper,the key components of this ADDT were designed and tested,and the the image acquisition and its boundary recognition of defrost and demist were conducted.In addition,the ADDT can synchronously collect and process multi-channel signals,such as temperature,voltage,current,wind speed,and so on.The whole test system was tested in the low temperature warehouse,and the results were in accordance with the actual test requirements.The main works of the paper are as follows:(1)Design and calibration of the fog generator and the frost generator.Based on the requirements on the fog & frost generator in China standard,the fog geneator was developed,which could produce the fog accuratly,and had the characteristics of small external heat ratidation and great operation convenience.The fog generator not only work independently with independent control and display part,but also communicate with the host computer using wire or wireless way.So the fog generator can send the state of work and other information to the host computer,and controlled by the host computer to monitoring and control.The frost generator was designed and modified based on the market’s mature devices,which can accurately display the sprayed water volume,and easy to accurately control the formation of the frost when testing.(2)Design of the data collector and its integrated development based on Lab VIEW.According to the needs of vehicle air-conditioner defrost and demist performance test,the data collector can simultaneously acquire 30 temperature signals,4 voltage signals,4current signals,4 wind speed signal,and so on.According to the characteristics of each sensor signal and the requirements of the test,the data recording frequency of each sensor can be set by the PC software.In addition,the data collector can also acquire the engine speed signal for the vehicle OBD,the state data of the fog generator,and the sprayed water volume of the frost generator,then displayed in real-time on the host computer.These important process data can obtained by the data collector,whch provide a reliable means to test and evaluate the air-conditioner performance for defrosting and demisting tests.(3)Design of image acquisition system and Develop of the identification method for the fog and frost area boundary.Firstly,the cameras were adjusted in the low temperature warehouse to obtain a clearer picture of the front and lateral glass surface.Then the image processing methods were developed to identify the dissipation boundary of the fog and frost on the glasses.The transparency of the frost on the glass is lower,so its boundary is more obvious and its image quality is better.Correspondingly,the result of its image processing is great.But the fog on the window surface is thin,and the image collected included more information from the interior parts of the vehicle,which brings great difficulty to the image processing.(4)Through the special tests and the actual vehicle tests to verify the developed test system.The validity of the fog and frost generator,the accuracy of the data collector and the image acquisition system are evaluated by the special tests,which were conducted in low temperature conditions.On this basis,this test system’s accuracy was evaluated.In addition,the actual defrost and demist performance tests were conducted for a vehicle using the test system deveiped in this paper.The results show that the ADDT system works reliably and can be operated convinecly,so it provides an effective means for the accurate and efficient completion of vehicle air conditioner defrosting and demisting performance tests and evaluation. |
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