CAJ | 학술논문

为了提高某增压汽油机的性能，将其压缩比提高到11．5，并加装一套EGR循环系统。通过台架试验，在低速小负荷和中速中负荷工况下，研究了理论空燃比下废气再循环率对改造后汽油机性能的影响。结果表明：当EGR率小于20％时，采用合适的EGR率配合优化的点火时刻，可以使该发动机燃烧稳定，在保证发动机动力性的同时，指示热效率随着EGR率的增加不断升高；与无EGR时相比，EGR率为20％时，有效燃油消耗率在低速小负荷工况下降低了约4．5％，中速中负荷工况下降低了9．7％；随着EGR率的增加，THC排放增加，而NOx 排放显著降低，CO排放在低速小负荷时出现上下波动的现象，而在中速中负荷工况时，随着EGR率的增加不断降低。
위료제고모증압기유궤적성능，장기압축비제고도11．5，병가장일투EGR순배계통。통과태가시험，재저속소부하화중속중부하공황하，연구료이론공연비하폐기재순배솔대개조후기유궤성능적영향。결과표명：당EGR솔소우20％시，채용합괄적EGR솔배합우화적점화시각，가이사해발동궤연소은정，재보증발동궤동력성적동시，지시열효솔수착EGR솔적증가불단승고；여무EGR시상비，EGR솔위20％시，유효연유소모솔재저속소부하공황하강저료약4．5％，중속중부하공황하강저료9．7％；수착EGR솔적증가，THC배방증가，이NOx 배방현저강저，CO배방재저속소부하시출현상하파동적현상，이재중속중부하공황시，수착EGR솔적증가불단강저。
In order to improve the performance of a supercharged gasoline engine ,the compression ratio was increased to 11 .5 and a set of EGR system was configured .Under the conditions of low load at low speed and medium load at medium speed ,the effects of EGR rate on the performance of retrofitted gasoline engine were studied based on the theoretical air‐fuel ratio through the experiments .The results show that the controllable EGR rate and optimized ignition timing can keep stable during combus‐tion process when the EGR rate is less than 20% .Meanwhile ,the indicated thermal efficiency increases with the increase of EGR rate .Compared with non‐EGR ,the brake specific fuel consumption decreases by 4 .5% at low speed and load area and by 9 .7% at medium speed and load area when EGR rate is 20% .With the increase of EGR rate ,THC emission increases ,NOx emission decreases significantly and CO emission fluctuates at low speed and load and reduces at medium speed and load .