Development Of China Light-duty Vehicle Driving Cycle

In China, one of the main air pollution sources is the emissions of motor vehicles, and the emissions of light duty passenger cars take a significant proportion in the total vehicle emissions. The CO, HC, NO_x and CO₂ emissions of light duty passenger cars has brought great harm to the environment and people’ health. So, it is of great significance to control and decrease the emissions of light duty passenger cars.Stringent emission standards can promote the automobile manufacturers to develop energy saving and emission reduction technologies. The vehicle driving cycle in emissio n standard is very important for certification of the vehicle emissions and fuel consumpt io n. Based on the project of Ministry of Environmenta l Protection cal ed ‘China 6th Stage Driving Cycle Development for Light-duty Vehicle’, an investigation about real-world driving conditions of light-duty vehicles was conducted in 20 typical cities. About 4.7 million real driving velocity data was collected.T4253H method was applied to preprocess the real driving velocity data. Based on the corresponding statistical methods, CLDC（China Light-duty Vehicle Driving Cycle） was developed.The main characteristic parameters of CLDC are as follows: time of duration is 1800 s, average velocity is 47.1km/h, and the maximum velocity is 128.5km/h, proportion of acceleration is 31.0%, proportion of deceleration is 27.4%, proportion of idle is 14.1%, proportion of cruise is 27.5%, and the maximum acceleration is 1.310m/s2, RPA（Relative Positive Acceleration） is 0.142 m/s2.The characteristics of CLDC were compared with those of NEDC, WLTC and FTP75. The results showed that CLDC was similar to WLTC in form.An AT light-duty gasoline passenger car with the engine displacement of 2.0L was selected as the test vehicle. In the laboratory, the CO, HC, NO_x and CO 2 emissions of the test vehicle were measured under normal cold start and hot start conditions according to NEDC, WLTC and CLDC, respectively. The main conclusions are as follows:（a） Under normal cold start condition, more than 65% CO emissions were from extra-high speed phase, but more than 80% HC emissions and more than 63% NO_x emissions were from low speed phase for CLDC and WLTC. Under hot start condition, more than 80% CO emissions were from extra-high speed phase, but more than 60% HC emissions and NO_x emissions were from low speed phase for CLDC and WLTC.（b） For NEDC, 86.91% CO emissions, 97.58% HC emissio ns and 91.83% NO_x emissions were from ECE phase under normal cold start condition. Under hot start condition, 67.00% CO emissions were from EUDC phase, but 76.23% HC emissio ns and 88.71% NO_x emissions were from ECE phase for NEDC.（c） Compared with the emissions of CLDC under normal cold start condition, the CO was increased by 4.89%, HC was decreased by 59.95%, NO_x was increased by 0.0098g/km, and CO 2 was decreased by 6.03% for the emissions of CLDC under hot start condition.The real-world driving emissions of the test vehicle were also measured, and CO₂ moving average window method was applied to calculate the CO, HC, NO_x and CO₂ emissions. Compared with the emissions of CLDC under normal cold start condition, the CO was decreased by 31.89%, HC was decreased by 63.38%, NO_x was decreased by 4.55%, and CO₂ was increased by 5.03% for the RDE（Real-world Driving Emissions）.