重型柴油车区域达标法和窗口平均值法对中国 典型路况的适应性

选择2台重型柴油车发动机,在测功机台架上复现其在中国典型道路工况下的运行过程,并测取发动机的外特性曲线、特征转速和ETC(European Transient Cycle,欧洲瞬态循环)做功量;在此基础上,基于美国和欧洲2种典型的重型在用车符合性检测方法,即NTE(Not-To-Exceed,区域达标)法和AWM(Averaging Window Method,窗口平均值法),对比研究了这2种方法对中国重型柴油车典型道路工况的适应性.结果发现:NTE法对在重庆国道高速公路下运行的重型柴油车工况具有较好的覆盖性,但对北京通州的公交车运行工况的覆盖性较差;改变NTE事件的采样时间准则和控制区域定义,对NOx比排放的数值影响不大.AWM能够利用全部的道路工况数据,但是由于怠速工况的存在,使得用该方法计算出的平均NOx比排放值比NTE法得出的数值偏高;而基于ETC循环做功量的窗口平均NOx比排放值具有较为合理的离散度.

Adaptability of NTE and AWM Heavy Duty Diesel Vehicles In Use Compliance Test Methods to Typical Road Conditions in China

The operating conditions of two heavy-duty diesel engines simulating real road running conditions in China were investigated using an electric dynamometer in a laboratory.The full-load speed characteristic curve,the featured engine speeds and work performed over the European Transient Cycle(ETC) were also measured.The adaptability of the Not-To-Exceed(NTE) and Averaging Window Method(AWM) heavy-duty diesel vehicle in-use compliance test methods used in the USA and Europe to typical road conditions in China was studied.The test results show that valid NTE events can cover most highway operating conditions in Chongqing city for a long-haul truck,but they can only cover a small area of the operating conditions for a city bus.Changing the NTE measuring time and control area boundaries has little effect on brake specific NOx emission.AWM has higher data sampling efficiency than NTE does,but the average NOx emission value by AWM is higher than that by NTE,due to the included NOx from idling conditions.The window averaged brake specific NOx emissions based on the work over the ETC have a reasonable scattering range.