NVO策略下HCCI汽油机缸内残余废气率估计

Estimation of Residual Gas Fraction in HCCI Gasoline Engine with NVO Strategy

为满足HCCI汽油机对缸内废气率的迅速感知、精确控制燃烧相位的要求,提出了一种残余废气率建模思路:建立气体在排气道和排气管中流动的散热模型,把排气流经气门作为绝热膨胀过程,用排气温度估计排气门关闭时刻缸内温度,计算出缸内废气率;同时为了满足瞬态工况控制要求,用一阶惯性环节来修正热电偶测温的延迟问题,并根据不同工况修正排气道壁温,有效提高了模型的计算精度.经验证,该模型的计算结果与GT仿真结果的相对误差在4%,以内.

To acquire the residual gas fraction （FRO quickly and control the combustion phase precisely in homoge- neous charge compression ignition （HCCI） gasoline engine, this paper proposed an FR6 estimation model. The flow thermal model of exhaust gas in exhaust duct and exhaust pipe was established, the exhaust flowing through the valve was considered as an adiabatic expansion process, the cylinder temperature in exhaust valve closing was estimated with exhaust gas temperature, and FgG in cylinder was calculated. At the same time, in order to meet the control requirements in transient condition, a first-order inertia link was used to modify the delay of thermocouple temperature measurement, and exhaust duct wall temperature was fixed according to different conditions, thus the calculation precision of the model was effectively improved. It is validated that the relative error between the calculated resuits using the proposed model and GT simulation results is within 4%.