汽油HCCI发动机燃烧相位及瞬态过程的控制

Controlling of Gasoline HCCI Combustion Phase and Transient Operation

由于HCCI燃烧受化学动力学控制,燃烧相位控制一直是HCCI面临的挑战之一.通过缸内直喷方式,可以灵活控制HCCI燃烧相位.研究表明,在HCCI失火界限,在负气门重叠期喷入燃油,能够实现燃油重整,通过调整不同的负气门重叠喷油量,可以控制燃烧相位;在HCCI爆震界限,负气门重叠期的喷油会导致燃烧粗暴,NOx排放大量上升,而在压缩行程喷入燃油形成分层混合气,能够有效地控制燃烧相位,且不引起排放的恶化.通过负气门重叠喷油形成的组分控制和压缩行程喷油形成的浓度控制相结合,能够在整个HCCI运行范围内有效地控制燃烧相位.通过考察燃烧相位调整的瞬态过程,发现通过缸内直喷技术,能够在一个发动机循环内实现燃烧相位的调整,控制灵活,响应迅速.

As homogeneous charge compression ignition（HCCI） combustion is controned by chemical kinetics, combustion phase control remains a challenging topic. Combustion can be controned flexibly due to gasoline direct injection. On missfiring boundary load, injection in negative valve overlap （NVO） can reform fuel. The combustion phase can be adjusted with different NVO injection mass. On knocking boundary, NVO injection leads to increased NO2 emission, while injection in the compression process resuits in stratified mixture. The combustion phase can be adjusted by the injection in the compression process without deteriorating N02 emission. Through NVO injection as wen as injection in the compression process, the combustion over the whole HCCI region can be controlled effectively. The control principle combines the component control and the concentration control. The transient process of combustion phase control is also studied in this article, through direct injection, combustion can be adjusted within a single engine cycle with quick response and flexible and reliable control.