在WLTC工况下不同驾驶模式对轻型车高原排放特性的影响

Influence of different driving modes on emission characteristics of light-duty vehicles in plateau under WLTC conditions

为研究在高原和平原地区的不同驾驶模式对全球轻型车统一测试循环(WLTC)工况下污染物排放特性的影响,针对搭载汽油缸内直喷(GDI)发动机的动力总成,在高原和平原实验室内采用底盘测功机进行WLTC工况行驶测试。结果表明:在不同驾驶模式下,高原与平原地区的CO排放量相差不大,均为国六b排放法规限值的40%左右;在高原地区经济模式下CO相对排放量较平原略有升高,在运动模式和正常模式下CO相对排放量略有下降;相对于平原地区,不同驾驶模式下高原地区的总碳氢化合物(THC)、非甲烷碳氢化合物(NMHC)排放情况整体表现较好,均为国六b排放法规限值的65%左右,其中运动和经济模式下THC、NMHC相对排放量均略有降低,正常模式下THC与NMHC的相对排放量增幅超过8%;相对于平原地区,在高原地区运动模式下,氮氧化物(NOx)相对排放量的增幅达到23.7%,正常模式次之,达到11.4%;与平原地区相比,3种驾驶模式下高原地区颗粒物(PM)和颗粒数(PN)排放均有所降低,正常模式下PM相对排放量降幅最大(30.6%),经济模式下PN相对排放量降幅最大(13.3%);低速时段是不同驾驶模式下污染物排放量占比最大的阶段,也是进行排放物改进优化的关键阶段。

In order to study the impact of different driving modes on emission characteristics of world light-vehicle test cycle(WLTC)in plateau and plain areas,a chassis dynamometer was used to conduct WLTC driving tests on a powertrain equipped with a gasoline direct injection(GDI)engine in the plateau and plain laboratories.The results show that in different driving modes,the CO emissions between plateau and plain areas are not significantly different,with the average of around 40%of the emission limit of China-Ⅵemission regulations.In the economic mode of plateau areas,CO relative emission slightly increases compared to the plain,while in the sport and normal modes,CO relative emissions slightly decrease.Compared to plain areas,the overall emissions of total hydrocarbons(THC)and non methane hydrocarbons(NMHC)in plateau areas are better under different driving modes,both of which are about 65%of the emission limit of China-Ⅵemission regulations.The relative emissions of THC and NMHC are slightly reduced in both sport and economy modes,while the relative emissions of THC and NMHC increase by more than 8%in normal mode.Compared to plain areas,the increase in nitrogen oxide(NOx)relative emission in plateau areas under sport mode reaches 23.7%,followed by normal mode at 11.4%.In three driving modes,compared with plain areas,the particulate matter(PM)emission and particle number(PN)emission in plateau areas have decreased.The PM relative emission has decreased the most in normal mode(30.6%),and the PN relative emission has decreased the most in economic mode(13.3%).The low-speed period is the stage with the highest proportion of pollutant emissions under different driving modes,and it is also a key stage for emission optimization.