段伟1,3，牛贝妮2，解方喜3，洪伟3
1.菲亚特克莱斯勒动力科技研发（上海）有限公司，上海 201807；
2.上海宏景智驾信息科技有限公司，上海 201804；
3.吉林大学 汽车仿真与控制国家重点实验室，吉林 长春 130025
摘要：通过优化缸内直喷（gasoline direct injection, GDI）汽油机的喷油正时和喷射压力，研究喷射策略对降低汽油机油耗和排放的粒子数量（particle number, PN）的影响。研究结果表明：对于单次喷射策略，适当提高喷射压力和增大喷油起始相位，可以降低PN排放和改善油耗，喷油起始相位过小或过大均不利于PN排放，转速小于3000 r/min时，优化的喷油起始相位为压缩上止点前曲轴转角280°~300°，转速为3000~5000 r/min时，优化的喷油起始相位为压缩上止点前曲轴转角300°~320°；对于二次喷射策略，合理调整第二次喷油结束相位和喷射比例，可以改善经济性和排放性，随着发动机转速和负荷的增加，减小第二次喷油结束相位和提高喷射比例，可以获得较好的经济性和排放性。
关键词：GDI；喷油正时；喷射压力；污染物排放；PN
Abstract：Based on a small turbocharged gasoline direct injection(GDI) engine, the effects of injection strategy on the reduction of fuel consumption and particle number (PN) emission are studied by optimizing injection timing and injection pressure. The results show that, for the single injection strategy, the increase of injection pressure and advancing the initial injection phase could effectively reduce PN emission and improve fuel consumption, but an excess earlier or later injection phase could lead to a deterioration of PN emission. For the engine speed lower than 3000 r/min, the optimal initial injection phase is 280°-300° before top dead center of combustion stroke, and at the engine speed 3000-5000 r/min, that is about 300°-320° before top dead center of combustion stroke. For the double injection strategy, the appropriate second injection end phase and split injection ratio could improve the fuel economy and PN emission. With the increase of engine speed and load, better economy and emission could be obtained by postponing the second injection end phase and increasing split injection ratio.
Keywords:GDI engine; injection timing; injection pressure; pollutant emissions；PN
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