微粒陶瓷过滤器和EGR在柴油机中的应用

Application of a Particulate Trap and EGR to Diesel Engine

通过联合使用废气再循环(EGR)和高过滤效率的红外再生微粒陶瓷过滤器,同时降低了柴油机的微粒和NOx排放.重新优化了过滤器再生用废气量,使其与EGR共同使用时过滤器的过滤效率和再生性能无明显变化,只是挂烟速度有所加快.同时,开发了一种新型的基于宽范围氧传感器的闭环反馈控制EGR系统,在不同的柴油机工况下,测定了不同EGR率时柴油机的空燃比α及NOx、CO和HC的排放值.最后得到了NOx、CO和HC的排放值随过量空气系数的倒数σ和EGR率变化的脉谱图.利用脉谱图拟合得出了最佳EGR率和σ之间的关系,为新型ECR系统的实用化铺平了道路.

The exhaust gas recirculation (EGR), coupled with a high-collection efficiency particulate trap is adopted to simultaneously control smoke and NOx emissions from diesel engines. Opening of the regeneration control valve of the trap is once again optimized to compensate for the decrease of the oxygen concentration in the exhaust gas resulted from EGR. The result indicates that the cleaning efficiency and the regeneration performance of the trap are maintained at the same level except that the back pressure increases faster. A new EGR system, which is based on a universal exhaust gas oxygen (UE-GO) sensor, is developed. Experiments are carried out under steady-state conditions. Throughout each test the EGR rate is kept at nine different settings and data are taken with the gas analyzer and UEGO sensor. Then, the EGR rate and engine load maps, which show the tendencies of NOx, CO and HC emissions from diesel engine, are made using the measured data. With the maps, the EGR regulation, the relationship between the optimal amounts of EGR flow and the equivalence ratio, σ, is obtained.