利用缸盖振动速度识别HCCI发动机着火时刻

HCCI Engines’ Combustion Timing Identification Based on Vibration Velocity

着火时刻是HCCI燃烧控制的基本反馈参数,为此,基于振动速度信号对HCCI发动机着火时刻进行了识别.建立了295 HCCI发动机机体、缸盖有限元模型,模拟分析了缸盖表面振动速度与压力升高率之间的关系,指出缸内峰值压力出现之前,缸盖振动速度信号和压力升高率有相近的变化规律,可利用缸盖振动速度信号估计发动机的着火时刻.295 HCCI发动机上的实测结果也表明了利用缸盖振动速度信号识别着火时刻的可行性.根据缸盖表面振动速度得到的着火时刻滞后于压力升高率表征的着火时刻,滞后角度在2.4°～3.7°CA之间,以3.05°CA作为系统滞后,相对于根据压力升高率表征的着火时刻,缸盖振动速度获得的着火时刻波动在±0.65°CA之间.

Identification of combustion timings in homogenous charge compression ignition（HCCI）engines based on cylinder head’s vibration velocity was presented in this paper.The relationship between cylinder head’s vibration velocity and pressure rise rate was analyzed on a 295 engine model.The results show that vibration velocity and pressure rise rate have similar traces before the occurrence of peak pressure,so combustion timing can be identified by the velocity of cylinder head.Experiments were conducted on a 295 HCCI engine,and the results show that there is a lag angle between the combustion timings determined by vibration velocity and by pressure rise rate.When the lag angle is within the range of 2.4°—3.7°,CA the average value 3.05°,CA can be regarded as system deviation.Regardless of system deviation,compared with the combustion timings determined by pressure rise rate,those determined by vibration velocity fluctuate within the range of ±0.65°,CA.