利用振动加速度识别HCCI发动机燃烧始点

Combustion Timing Identification by Using Vibration Acceleration in HCCI Engine

燃烧始点是均质压燃(Homogenous charge compression ignition,HCCI)燃烧控制的基本反馈参数,基于振动加速度信号对HCCI发动机燃烧始点的识别进行研究。建立295HCCI发动机有限元分析模型,基于模型模拟分析了缸盖表面振动加速度信号与缸内压力二次导数之间的关系,指出缸内峰值压力出现之前,缸盖表面振动加速度信号和缸内压力二次导数有相近的变化规律,可利用燃烧阶段振动加速度信号最大峰值前的第一个过零点判断发动机的燃烧始点。在295 HCCI发动机上的实测结果表明,据缸盖表面振动加速度信号得到的燃烧始点滞后于压力二次导数表征的燃烧始点,滞后角度在2.5°～4.5°之间,以3.5°作为系统滞后,相对于压力二次导数表征的燃烧始点,振动加速度信号获得的燃烧始点波动在±1.0°CA之间。

Estimating combustion timing in homogenous charge compression ignition（HCCI） engines based on cylinder head＇s vibration acceleration is presented.The relationship between the vibration acceleration and the second derivative of cylinder pressure is analyzed on a 295 engine model.Results indicate that the vibration acceleration and the second derivative of cylinder pressure has similar trend before the appearance of the peak pressure.Combustion timing can be estimated by the first zero-crossing point before the location of the peak vibration acceleration of cylinder head.Experiments are conducted on a 295 HCCI engine.Results show that the combustion timing obtained on the basis of the cylinder surface vibration acceleration signal lags behind that characterized by the second derivative of cylinder pressure.The lag angle is in the range of 2.5°～4.5°.The average value 3.5° is regarded as system lag.The fluctuation of combustion timing obtained from the vibration acceleration signal is ±1.0° relative to the combustion timing characterized by the second derivative of cylinder pressure.