492WQB汽油机排放的缸间差异研究

An Investigation on Emission Difference Among Cylinders of a 492WQB Spark ignition Engine.

对４９２ＷＱＢ汽油机的每个试验工况从各缸排气道出口中心附近进行了连续１０ｓ共９０次的采样， 对采样气体中ＮＯｘ、ＨＣ及ＣＯ的浓度分别采用了化学发光法、氢火焰离子法及不分光红外法进行了分 析，并把连续采样气体的排放平均值作为每个测试工况的排放值。试验结果表明，各缸空燃比等的微小 差异，引起的各缸ＮＯｘ、ＨＣ及ＣＯ排放的最高值与最低值比可达１０倍、５倍及６倍；缸间排放差异随着 点火时间、转速、节气门开度、混合气浓度的变化而变化；引起缸间排放差异的原因除空燃比的差异外还 有进气量等的差异。

In this study,the exhaust emissions are continuously sampled 90 times during 10 seconds near the center of exhaust port exit of each cylinder. The NO.HC and CO emission of samples were respectively analyzed by using Chemiluminescent Detector.Flame Ionization Detector and Nondispersive Infrared Analyzer. The average of 90 times sampling is regarded as the exhaust emission value of each condition. It can be found that the maximum value of NOx. emission is nine times more than the minimum value of NOx. emission,and 5 and 6 times for HC and CO respectively. The main reason of the emission differences among cylinders is the difference of air/fuel ratio among cylinders under the same operating condition,and there are some other reasons such as the difference of inlet air flow besides the main reason.