柴油机低温预混合燃烧稳定性控制方法

Stability Control Methods of Low-temperature PCCI for Diesel Engine

为了解决低温预混合燃烧不稳定的问题,在基于缸压信息的燃烧闭环控制基础上,建立了以θCA50(累计放热50%的曲轴转角)波动率为指标的燃烧状态稳定性评价体系;在分析燃油系统和空气系统控制参数对燃烧状态稳定性影响的基础上,提出了燃烧状态不稳定判据,过滤掉发动机瞬态工况的中低频波动;设计了自适应的燃烧稳定性控制方法,分阶段通过θCA50目标值、新鲜空气流量和燃烧模式的调整来降低燃烧的不稳定性。台架试验结果表明,该控制方法能够在燃烧状态稳定性指标超过限值时,通过调整控制参数自动把指标重新控制在限值以内。

For the instability problem of low-temperature PCCI ,the evaluation system ofθCA50 fluctuation ratio for the combus-tion state stability was established based on the closed-loop control of in-cylinder pressure .The influences of fuel and air control parameters on the combustion stability were analyzed and the criterion of unstable combustion was put forward .According to the criterion ,the low frequency fluctuations of engine transient operation were filtered .The self-adaptive control method was designed ,which reduced the instability of combustion by regulating theθCA50 target value ,the fresh air mass flow and combus-tion mode in stages .The test results show that the control method can automatically regulated the control parameters to make the higher stability index drop within the limit .