电控168F 汽油机燃烧与排放特性分析

摘要

The electronic control fuel injection system of universal small gasoline engine was self‐developed and the combus‐tion ,emission and other comprehensive performance were optimized through controlling the mixture concentration flexibly .The system was applied to 168F gasoline engine and its control strategy was determined according to the influences of excess air co‐efficient(φa ) on engine working process and emission characteristics .In order to meet the current emission standard of United States Environmental Protection Agency(EPA) ,the richer mixture was used to reduce NOx emission in rated conditions ,the lean mixture was used to reduce CO and HC emissions ,and the cyclic fluctuation of engine should be controlled .The optimalφa andθwere determined by introducing the optimized ignition advance angle and were written into the MAP .Accordingly ,the power of the gasoline engine kept unchanged and the emission and economy improved ,which met the user application require‐ments and EPAⅢ emission standard .%自主开发了通用小型汽油机电控燃油喷射系统，通过柔性控制混合气浓度优化燃烧性能和发动机排放及其他综合性能。将其应用于168 F汽油机，通过研究过量空气系数（φa ）对整机工作过程和排放特性的影响来制订控制策略。为满足美国EPA现行排放法规，标定工况需使用比功率混合气偏浓的混合气减少NOx 排放，部分负荷采用偏稀的混合气控制CO和 HC排放，同时需要控制发动机的循环波动。结合优化点火提前角（θ）研究形成了整机匹配的最佳φa 和θ并写入MAP ，汽油机整机动力性不变，排放和经济性能提高，能全面满足用户使用和美国EPAⅢ排放法规要求。