缸内直喷CNG发动机点火提前特性分析

摘要

将4气门4缸车用汽油机改装为缸内直喷CNG发动机,在发动机台架试验及燃烧过程试验基础上,对发动机的充气效率、点火提前角进行了基础标定,并分析了发动机的点火提前特性.研究表明:发动机采用缸内直喷,输出扭矩对点火提前角变化敏感;随着点火提前角增大,发动机最高燃烧压力升高,出现最大燃烧压力所对应的曲轴转角逐渐靠近上止点,发动机爆燃倾向加大,最高燃烧温度升高,经济性好转.%A 4-valve, 4-cylinder gasoline engine was converted into a direct injection CNG engine. Based on the bench experiment and combustion analysis, the volumetric efficiency and the ignition advance angle were optimized and the ignition advance characteristics were analyzed. The results show that the output torque is sensitive to the ignition advance angle in the direct injection CNG engine. With the increase of ignition advance angle, the maximum cylinder pressure increases and its corresponding crank angle is gradually close to the TDC. In addition, the engine knock tendency becomes severe, the maximum combustion temperature rises and the engine economy improves.