Research On Correction The RDE Test Results Of Light-Duty Vehicles With Smooth Driving Behavior Based On Windows Dynamic Characteristics

At present,the china-6 emission regulations mainly refer to the Euro-6c emission regulations and standards,and take the real driving pollutant emission test（RDE）as a supplement to the laboratory test procedure.According to the RDE regulations,CO₂moving average window method is used as the test data processing method,but the moving average window method is used to calculate the RDE test results based on the European test data.However,the domestic traffic conditions and driving behaviors are quite different from those in Europe,so whether it can accurately reflect the real driving emission level in China remains to be studied.In addition,because there is no fixed cycle condition in RDE test,the test results are easily affected by many factors.Driving behavior is the main reason for the non repeatability of RDE test results.Therefore,in this paper,six light gasoline vehicles that meet the China-6 standards are tested by the Portable Emission Measure System（PEMS）for RDE with different driving behaviors.The correlation between the window travel dynamics parameters and the regulatory travel dynamics parameters with the pollutant emission factors is analyzed.Meanwhile,the window normality and RDE results of smooth driving behavior are modified according to the actual road driving characteristics in China.The main research contents and conclusions are as follows:（1）In order to explore the influence of different driving behaviors on the results of RDE,the driving behaviors of three light gasoline vehicles were compared.The results show that the emissions of CO,NO_x and PN increase with driving intensity.Compared with normal driving,intense driving results in a 59%-382%increase in PN emissions,a 10%-82%increase in NO_x emissions,and a 71%-504%increase in CO emissions.（2）In order to evaluate the influence of driving intensity on dynamic parameters,the relationship between dynamic parameters and driving intensity was analyzed.The results show that there is a significant correlation between the driving intensity and the dynamic parameters,that is,with the driving intensity increasing,the dynamic parameters gradually increase.Compared with smooth driving?(6_pos[95]and RPA,the average growth rate of normal driving is 51%and 57%,while that of intense driving is 120%and 100%.（3）This paper analyzes the correlation between the dynamic parameters and pollutant emission factors,and compares the correlation between the dynamic parameters of regulations and windows with pollutant emission factors under different road sections.The results show that,compared with the dynamic parameters of the regulation,the dynamic parameters of the window(?(6_pos[95]and RPA)have more obvious correlation with CO and PN emission factors,and the NO_x emission factors only have strong correlation with the dynamic parameters of the window RPA,besides the fluctuation amplitude of the correlation coefficient of the three vehicles decreases by25%～64%respectively.（4）In order to improve the normal passing rate of RDE test window for smooth driving and better evaluate the real road driving emission level,the P₁,P₂ and P₃reference point coefficients of CO₂ characteristic curve in moving average window method are modified in combination with the real road characteristics in China.The results show that the normal passing rate of urban,suburban and motorway windows is more than 95%after the correction,which improves the success rate of RDE test,and the effect of the correction on the RDE test results of smooth driving is small,which proves the effectiveness of the correction method.（5）In order to improve the repeatability of RDE test results and reduce the influence of smooth driving on RDE test results,the RDE test results are modified in combination with the driving characteristics of slow acceleration and slow deceleration of the actual road.The results show that:after the RDE results of smooth driving are corrected,the emissions increase 43%～82.9%compared with the emissions before the correction,and the difference between the emissions of smooth driving and normal driving decreases to 7.3%～56.9%;It is proved that the correction method based on the window dynamics correction factor can correct the RDE test results of smooth driving,and make the corrected RDE test results more repeatable.