EGR率对柴油机排放特性影响的试验

研究了增压直喷柴油机在不同工况下不同EGR率对性能和排放的影响规律,确定了各个工况下EGR率的优化原则,并获取了柴油机最佳EGR率的M AP图,设计出一套EGR电子控制系统,可以对EGR系统中的进气节流阀和EGR阀进行控制,确保不同工况的最佳EGR率。发动机台架试验证实,设计的EGR电控系统按所获取的最佳EGR率运行,可以使NOx排放量降低19.9%,CO和HC排放量略有增加,动力性和经济性与原机相当,对EGR回路冷却可以抑制柴油机因使用EGR技术而导致的PM排放的增加。

EGR Rates Optimization Rule and Experimental Study about Influence of EGR Rates on Diesel Engine

The technology of exhaust gas recirculation(EGR) was studied and applied in a turbocharged direct-injected diesel engine in order to reduce nitrogen oxides(NO_x) emission.When diesel engine operated under different operational conditions,the influence of different EGR rates on diesel engine performance and emissions was investigated,the optimization rule of EGR rates was constructed,the optimum EGR rates were concluded and labeled for different operational conditions,the optimization EGR MAP was formed.An electronic EGR system was designed and it controlled intake throttle valve and EGR valve precisely to ensure the optimum EGR rates.The diesel engine experimental tests show that when electronic EGR system operates on the basis of optimum EGR rates,diesel engine NO_x reductions are 19.9% compared with the original,CO and HC emissions are a little more than the original,power and fuel economy characteristics are similar to the original,cooling of EGR can restrain PM increase when EGR technology is used in diesel engine.