Study On The Urban Road Driving Cycle Of Light Vehicle In Changchun

The proportion of light vehicle in China's vehicle ownership is the highest,although the engine displacement of ones is small,but a certain amount of cumulative fuel consumption and pollutant emissions are considerable.The fuel consumption and pollutant discharge of light vehicles should not be ignored.Driving cycle is an important criterion to evaluate vehicle fuel consumption and pollutant emission.Therefore,it is necessary to study the driving cycle of light vehicle for promoting the development of light vehicle energy saving and emission reduction technology.Changchun is an important central city in Northeast China.Its geographical,climatic and humanistic characteristics have jointly played a role in the urban road driving conditions of light vehicle in Changchun.Based on the project of Ministry of industry and information called‘Research and Development of China New Energy Automotive Products Test Cycles',a study about the construction and verification of light vehicle urban road driving cycle of in Changchun.About 48 million speed data were collected during the 13-month real road test of 69 test vehicles.One dimensional discrete wavelet stratified threshold denoising and one dimensional discrete wavelet decomposition domain quantization compression are selected as the preprocessing method for the vehicle speed data.According to the principle of short segment segmentation and screening,282767 effective short segments are extracted,and the corresponding motion segments and idling segments database are set up.The constructed driving cycle is obtained by using the driving cycle construction method of‘motion segment+principal component analysis+clustering analysis+sum of squares of deviations+speed threshold'.The duration of the constructed driving cycle is 1700s,the running distance is 15744.8m,the maximum velocity is 108km/h,average velocity is 33.35km/h,the maximum acceleration is 2.639 m/s²,and the maximum deceleration is-4.722 m/s²,average acceleration is 0.524 m/s²,average deceleration is-0.603 m/s²?The probability density distribution of v-a of the constructed driving cycle is obvious.The low speed and medium speed part takes a larger proportion in the cycle,and the proportion of high speed and super high speed part is relatively small,while there is a certain proportion of larger acceleration and deceleration.The coefficient of variation of the main characteristic parameters of the constructed driving cycle and motion segments is calculated.The results show that the constructed driving cycle can accurately reflect the light vehicle real driving characteristics in Changchun.Comparison of three driving cycles,it is found that the constructed driving cycle are different from NEDC and WLTC.The constructed driving cycle,NEDC and WLTC is simulated and analyzed by AVL Cruise MT FWD vehicle model.The simulation results of the constructed driving cycle's fuel consumption and NO_X,CO,HC,CO₂ emissions are all larger than NEDC and WLTC.It can be understood that the constructed driving cycle is more stringent than NEDC and WLTC in the control of fuel consumption and gaseous pollutants.Comparison of the constructed driving cycle with NEDC and WLTC on the characteristics of engine 14 working conditions,the distribution and distribution proportion of work points on speed and torque,and the distribution proportion of fuel consumption on speed and average effective pressure.It is known that the constructed driving cycle is similar to WLTC,but the working point of the engine is more widely distributed.