Modification Of RDE Test Results Of Heavy-Duty Vehicles With Rough Driving Behavior Based On Window Dynamics

The latest Limits and Measurement Methods for Emissions from Diesel Fuelled Heavy-duty vehicles（China 6）used the heavy vehicle Real Driving Emissions（RDE）test as a supplementary test procedure for the laboratory certification cycle,in order to better control the real word emissions of heavy-duty vehicles.Because the emission results of the heavy-duty vehicle RDE test was not repeatable and consistent;at the same time,among the many factors that affect the heavy-duty vehicle RDE,the impact of driving behavior on its emission results is particularly prominent.In order to explore the influence of driving behavior on the results of heavy vehicle RDE test and increase the repeatability and operability of heavy-duty vehicle RDE test.Under the road conditions in Chongqing,the 3 heavy-duty vehicles were tested in three different driving behaviors in strict accordance with the China 6,study on the effects of different driving behaviors on the RDE test results of heavy vehicles.On this basis,the RDE test results under intense driving behavior were revised,and to increase the repeatability of the RDE test and the pass rate of the RDE test.The specific research contents are as follows:In order to explore the impact of different driving behaviors on the RDE test results of heavy-duty vehicles,the 3 heavy-duty vehicles were tested in smooth driving,normal driving and rough driving,and analyze the effects of different driving behaviors on the final evaluation results of the pollutants in the RDE test.The results show that compared to smooth driving,normal driving and rough driving behavior the total section CO emissions increase by-74.05%～64.16%;the total stroke NO_x emissions increase by 33.73%～621.1%;the total stroke PN emissions increase by 21.26%～122.4%.The driving behavior has a strong influence on the RDE test results of heavy-duty vehicles,and the influencing factors of driving behavior cannot be ignored.In order to find a practical and correctable method to increase the repeatability of RDE test.Study the correlation between pollutant emissions and RPA and v·a_pos[95],find that the CO ratio emissions of both the branch section and the total section are not significantly related to RPA and v·a_pos[95];There is also no obvious correlation between CO₂ emission and RPA or v·a_pos[95];Comparing to not containing urban areas sections,the correlation for the emission results of containing urban areas has a significant increase between NO_x emission factors and RPA and v·a_pos[95];The correlation between the PN emission factor and RPA and v·a_pos[95]is better than other pollutants.The PN emission factor has a strong correlation with RPA and v·a_pos[95].The difference between the actual road conditions in Chongqing and the C-WTVC laboratory benchmark test cycle conditions in the regulations is compared.It is found that the C-WTVC cycle is far from the dynamic parameters of the RDE test for heavy-duty vehicles under Chongqing road conditions,especially on high-speed sections.At the same time,analyze the correlation between RPA and v·a_pos[95]and pollutant emissions by statistically,and it is found that the dynamic parameter v·a_pos[95]can more accurately reflect the vehicle’s intense driving behavior and pollutant emissions.Therefore,select the normal driving behavior characteristic curve and window dynamics parameter v·a_pos[95]as the basis for calculating the correction reference curve and the window correction factor,respectively.According to this,the pollutants emitted by the vehicle under the intense driving behavior are corrected.In order to distinguish the difference between the window dynamic parameters under normal driving and intense driving behavior,the pollutant emission results under intense driving behavior are better corrected.Analyze the distribution characteristics of the window dynamic parameters v·a_pos[95]and the baseline and its basic and extended tolerance lines under normal driving and intense driving behavior.It is found that the reference curve and its basic and extended tolerance band can distinguish the difference of window dynamic parameters under normal driving and intense driving behavior.Further analysis of the pollutant distribution characteristics before and after correction under normal driving and intense driving behavior,It is found that after the correction,the window correction factor can well correct the emission of window pollutants for intense driving behavior.Based on the correction factors calculated by the window dynamic parameters,the pollutants（CO,NO_x,PN）emissions are corrected,and evaluate the final emission results.The results show that:Compared with the relative fluctuation before normal driving behavior correction,the relative fluctuation of NO_x emissions after correction is reduced by 25.41%～110.9%.Compared with the relative fluctuation before normal driving behavior correction,the relative fluctuation of PN emissions after correction is reduced by 9.83%～17.62%.Compared with the relative fluctuation before normal driving behavior correction,the relative fluctuation of CO emissions after correction is reduced by-42.33%～55.64%.Except for CO,the relative fluctuations of the NO_x and PN emission factors after the correction both dropped significantly.It shows that the correction method for the correction of NO_x and PN meets the desired requirements,and can effectively increase the repeatability of the RDE test results and increase the efficiency of passing RDE tests for heavy-duty vehicles.