均质GDI汽油机混合气形成的影响因素研究

文中以一款增压直喷汽油机燃烧系统开发为例,从低速及高速两种工况,研究了气道及燃烧室形状、油束布置方案等因素对缸内混合气形成过程的影响。分析结果显示改变进气道及燃烧室屋脊形状、增加缸盖排气侧挤气面积以及调整油束喷射角度,可以提高缸内滚流运动强度、加强油气混合过程,从而有效改善了点火前缸内混合气的分布情况。研究了高转速下喷油时刻对混合气形成及燃油湿壁情况的影响,结果显示喷油起始角为390°CA时综合效果较好。采用较优方案组合进行的初步性能试验表明,外特性及部分负荷工况下的燃烧效率较高,动力性及经济性基本达到既定目标。

The Study of Influence Factor on Mixture Formation of a Homogeneous GDI Engine

In the development of a T-GDI engine combustion system, the influence of intakeport and combustion chamber and fuel spray scheme to mixture formation in cylinder was studied under two operating conditions （ the low rotation speed an the high rotation speed ）. The results show that modifying the shape of intakeport and combustion chamber, increasing the squish area of cylinderhead near the exhaust valve and adjusting the angle of fuel spray can improve the tumble intensity and the mixing process, leading to a good result of fuel distribution at the ignition time. Under the high rotation speed condition, the influence of injection time to mixing process and wall wetting was studied. The results indicate that the best overall effects can be obtained at 410°CA SOI at the high speed. The test results of the engine which adopt those better scheme show that combustion efficiency is high at the full load and the part load, power performance and economy have reached the target.