汽油机EGR率的计算机理及预测算法研究

Study on the Calculation Principle and Estimation Algorithm for EGR Rate of Gasoline Engine

应对最新高效汽油机的发展趋势,低压废气再循环(LP-EGR)技术成为国内可以尝试的降低油耗,抑制爆震,优化排放的新型技术之一。但是,不正确的废气量的计算引入反而会给稳定燃烧带来新的挑战,比如失火,早燃等异常现象。在没有成熟的EGR率传感器的条件下,如何较为准确地估算废气量占总气量的比例(质量EGR率)成为了电控系统开发人员的首要挑战。旨在剖析气体分析仪得到的摩尔EGR率与质量EGR率的异同,同时介绍了一种在不同位置预测瞬态EGR率的算法模型,为LP-EGR的精确控制以及该项技术的大规模产业化提供思路。

Face to up-to-date technical evolution tendency for modern gasoline Engine,LP-EGR(Low Pressure Exhaust Gas Recirculation)is demonstrated as a new technology to reduce fuel consumption,suppress knock and optimize the emission.However,some abnormal combustion phenomena such as missfire,pre-ignition will rise up if the calculation for exhaust gas fraction is not accurate.Nowadays there is no mature sensor to measure EGR rate at market,thus how to correctly predict the exhaust gas fraction(Mass EGR rate)becomes the top challenge for EMS workers.This paper aims to study the difference between typical Mole EGR rate from Air analyzer and Mass EGR rate,also to provide one estimation algorithm to predict the transient EGR rate at variant position.Hopefully this study can help LP-EGR to be controlled precisely,and facilitate the mass production for this technology.