Comparative Study On The Actual Driving Cycl Of Light Vehicle In Nanjing And Testing Standard Cycls

Motor vehicle driving cycle has a crucial impact on the emission characteristics of motor vehicles.In order to compare the differences between the parameters and the emission characteristics of actual driving cycle in Nanjing urban road and the testing standard driving cycle,this paper is a study on the light-duty vehicle in Nanjing.The Portable Emission Measurement System(PEMS)and Chassis dynamometers tests were used to carry out the experiments for the emission of light-duty vehicle actual driving cycle in Nanjing urban road and the test standard driving cycle,and analyzed the difference of emission characteristics between actual driving cycle and test standard driving cycle.Firstly,the SEMTECH-DS is used to build a set of PEMS which can be applied to emission tests of light-duty vehicle in Nanjing.The data of 44186 sets of valid data were obtained by measuring the driving cycles of the light and peak hours on the different levels of roads in Nanjing.Based on this data,the actual driving cycle of Nanjing light-duty vehicles with a total length of 1172s is constructed by principal component analysis and rapid clustering analysis.The driving speed is in the range of 0?76.28km/h and the acceleration is in the range of-2.72?2.05m/s2.The total relative error of the combined driving conditions and the actual operating parameters of the road is 19.75%,which can basically represent the actual operation status of the light-duty vehicles in Nanjing.Secondly,based on the conditions of the process and the characteristics of the parameters,the actual driving cycle in Nanjing and the test standard driving cycle were compared:In the actual driving cycle and test driving cycle,the actual driving cycle of has the longest drving time and mileage,as well as the maximum speed and acceleration with little frequency,while the ASM and VMAS have uniform acceleration and uniform deceleration,which the overall conditions of the process is relatively simple,and the travel distance of VMAS is the shortest;In the actual driving cycle and standard driving cycle,the cycle time and mileage of the WLTC is the largest,which has the most widely and uniform speed distribution,while the time duration and mileage of the actual driving cycle and NEDC are similar.At the same time,the average speed of the actual driving cycle is the smallest but the acceleration is the largest,the acceleration and deceleration of WLTC and the actual driving cycle is irregular,but NEDC are linearly changed.Finally,the characteristics of light-duty vehicle emissions in actual driving cycle and the test standard driving cycle are analyzed on the basis of measured data.The emission characteristics of CO2,CO,NOx and HC pollutants under various driving cycle were analyzed in detail from the aspects of overall operating conditions,driving mode,speed and acceleration.It is found that the instantaneous emissions under three types of driving cycle change similarly with the variable speeds and accelerations.In the acceleration mode,the emission rate of CO2,CO and NOx is the largest while in the idling mode is the smallest,and the emission rate of the HC in the actual driving cycle and the NEDC is the largest in the idling mode.Under the actual driving cycle,the emission rate of CO2,CO and NOx is 1.1?2.2 times higher than that of the test driving cycle,the emission factors of CO2 and CO are 0.3?0.8 times of the test driving cycle.The average emission rate and emission factor of CO2,CO,and HC of NEDC are 1.8?2.75 times of the actual driving cycle,but the average emission rate and emission factor of NOx under actual driving cycle are 1.25?1.5 times of NEDC.