米勒循环结合两次喷射对缸内直喷发动机起动工况下混合气的影响  

Study on the Influence of Miller Cycle Combined with Two-Stage Injection on Mixture During Gasoline Direct Injection Engine Starting

作　　者：魏胜利[1] 张绍邦 丁统元 倪士栋 张志成 WEI Shengli;ZHANG Shaobang;DING Tongyuan;NI Shidong;ZHANG Zhicheng(School of Automotive and Traffic Engineering,Jiangsu University,Zhenjiang,Jiangsu 212013,China;GRC Automotive Technology(Suzhou)Co.,Ltd.,Suzhou,Jiangsu 215100,China)

机构地区：[1]江苏大学汽车与交通工程学院,江苏镇江212013 [2]吉孚汽车技术(苏州)有限公司,江苏苏州215100

出　　处：《西安交通大学学报》2023年第4期11-21,共11页Journal of Xi'an Jiaotong University

基　　金：国家重点研发计划资助项目(2017YFB0103402)。

摘　　要：为探究直喷发动机第二次喷油时刻、两次喷油比例对燃油蒸发与混合气形成质量的影响,在一台汽油缸内直喷(GDI)发动机进气门早关(EIVC)米勒循环单次喷射的基础上,采用控制变量的方法,在两次喷油量相同的情况下,设计了7组不同的第二次喷油时刻方案,并在最优喷油正时的基础上,设计了6组不同喷油比例的方案进行试验。结果表明:在压缩冲程中后期,缸内湍动能随着喷油重心的后移而增强;随着二次喷油正时的推迟,更多的燃油附着位置从活塞顶部转向缸套表面;当二次喷油正时为进气上止点后150°曲轴转角、喷油比例为2∶1时,附壁油膜蒸发效果最佳,点火时刻缸内残余油膜量最少,较原机下降95%,并且该条件下当量比分布良好,在火花塞附近形成了当量比为1.3的微浓混合气,有助于火核的形成。Based on an early inlet valve closing(EIVC)single injection of a gasoline direct injection(GDI)Miller cycle engine,the method of controlling variables was adopted to study the influence of the second injection time and the ratio of the two injections on the quality of fuel evaporation and mixture formation.The two injections were set to have the same quantity,and seven different sets of second injection timing programs were designed.Based on the optimal injection timing,six groups of different first and second injection ratios were designed.The results show that in the middle and later stages of the compression stroke,the turbulent kinetic energy in the cylinder increases with the backward shift of the fuel injection center of gravity,and with the delay of the timing of the secondary fuel injection,more fuel attachment positions shift from the top of the piston to the surface of the cylinder liner.When the secondary injection timing is 150°crankshaft angle after top dead center(TDC)and the fuel injection ratio is 2∶1,the wall film evaporation effect is the best,and the residual wall film mass in the cylinder is the lowest at ignition time,which is 95% lower than that of the original engine.Under this condition,the equivalent ratio distribution is good.A slightly concentrated mixture with an equivalent ratio of 1.3 is formed near the spark plug,which is helpful for the formation of a fire nucleus.

关 键 词：汽油缸内直喷发动机 米勒循环 喷油时刻 喷油比例 附壁油膜 

分 类 号：TK411[动力工程及工程热物理—动力机械及工程]