利用压力和温度测量计算直喷汽油机的再循环废气率

Prediction of Direction-injection Engine Exhaust Gas Recirculation Rate Based on Pressure and Temperature Measurements

传统的再循环废气率测量方法主要通过测量气量或气体组分含量对再循环废气率进行计算,但此方法传感器不能完全适用于整车复杂的排气系统。基于测量废气再循环阀前后压力和温度的测量结果,对一台直喷汽油机再循环废气率的计算和分析,开发了利用压力法公式拟合来测量再循环废气率的方法,通过实际发动机的实验数据和计算流体力学的模型验证来拟合针对此款发动机的计算公式,对公式拟合方法的误差敏感度进行探索,并分析此方法对于传感器精度的需求,最后利用更广工况范围的其他数据点对此方法进行验证。

Traditional EGR rate measurement schemes usually involve gas flow rate measurements or exhaust species concentration measurements,and infer EGR rate via theoretical calculations.However,for such a method,it is challenging for the sensors to function under the harsh environment of practical vehicle exhaust systems.This work measured the pressure and temperature before and after the EGR valve,and derived the EGR rate for a practical gasoline direct injection(GDI)engine.Using pressure-related equations,this work explored methods to measure the EGR rate.Empirical equations were obtained based on experimental engine data and computational fluid dynamics(CFD)results,and the sensitivity of the fitting model was investigated as well.Finally,the sensitivity requirements for the sensors to implement this technique were illustrated,and further experimental data was employed to justify the application of this model for more general applications.