单缸柴油机气门间隙对换气过程影响的模拟计算

换气过程对柴油机动力性 ,经济性及排放指标等有较大的影响 文中用建立的换气过程缸内压力计算模型及实测缸内换气过程时的低压示功图 ,对一台单缸、水冷、四冲程、直喷式柴油机进、排气门间隙变化引起配气相位变化时的换气过程进行了模拟计算研究 ,结果表明 ,进、排气门间隙减小时 ,进、排气门提前开启迟后关闭 ,换气损失减小 ,充气效率增加 当进、排气门间隙过大时 ,换气过程性能变差 转速不变 ,负荷变化时 ,充气效率变化不大 转速为 1 650r/min时充气效率较大 ,当转速高于或低于此值时 ,充气效率均降低

A Simulating Calculation on the Influence of Valve Clearance on the Gas Exchange Process in a Single Cylinder Diesel Engine

Gas exchange process has a great influence on the power,the economy and the emission performance of a diesel engine. The valve open and close phases will be changed when the valve clearance changes. The influence of valve clearance on the gas exchange process is investigated by measuring the cylinder pressure and by making a through simulation .The engine is a single cylinder, water cooled, four stroke, direct injection diesel engine. It is found that gas exchange loss will decrease and volumetric efficiency will increase when exhaust or intake valve clearance decreases. It is also found that the gas exchange performance will be poor when valve clearances are too big. The volumetric efficiency changes little when engine load changes but the speed does not change .The volumetric efficiency is at the biggest when the engine speed is at 1650r/min. The volumetric efficiency decreases when the engine speed increases or decreases from 1650r/min.