基于氧传感器信号的用于研究空气/燃料比率变化的统计方法

A Statistical Approach in Studying the Air/Fuel Ratio Variation Based on Oxygen Sensors′ Signals

给出了火花点火式发动机排气氧传感器(EGO)输出信号的实验结果。实验中采用V6、3.8 L、BUICK发动机且每个气缸中安装有一个氧传感器,以研究影响发动机消耗燃料的因素。应用LabView数据采集装置记录单个气缸废气以及主流尾气氧传感器的输出电压信号。对来自6个气缸变量的平均值采用统计的方法进行处理后,并与主流的EGO电压进行比较,确定了产生系统误差的因素。对左右两侧气缸信号平均值的差别进行比较发现,采用此种排气管结构的气缸中空气—燃料混合气平均值存在一些明显差别。根据数据和图表解释了统计的结果。研究表明,V字形排列的发动机两侧的气缸的空气和燃料混合气是不同的;在低速、高负荷和高辛烷燃料的情况下,右侧气缸具有比较稀的混合气;而在某些情况下两侧气缸具有相同的混合气。基于统计估计的方法,提出了一个可以用于估计V字形排列发动机左右两侧气缸中空气—燃料混合气的简单模型。此方法还可以应用于分析进气管和排气管的缺陷。

This study examines the test results from a spark ignition engine exhaust gas oxygen （EGO） sensors＇ output signals obtained from a V6, 3.8 liter, BUICK engine fitted with individual oxygen sensor per cylinder exhaust runner. The goal is to find which factors and what combination of factors may influence the feeding of an engine with fuel. A LabView data acquisition equipment is used to record the individual cylinder＇s exhaust gas oxygen sensor＇s output voltage signal and the main flow （stock） exhaust gas oxygen sensor voltage signal. A statistical treatment of the variability of the mean values of the six cylinders＇ voltage signal is compared with the stock EGO sensor＇s voltage signal. The factors that provide stable systematic error are established. The variations between the mean signal values on the left and right banks of cylinders are compared. Some significant differences between the mean values in air-fuel mixture of the cylinders with this configuration of the exhaust manifold have been found. Tables and graphs illustrate the statistic results. The major conclusions are ： the two banks of this V-engine are not equally supplied by airfuel mixture; there are cases where the right bank has a leaner mixture than the left, namely at moderate speed, high load, and high-octane gasoline, and there are cases when both banks have the same air-fuel mixture. A brief model for an overall estimation of air-fuel mixture to the two banks is proposed based on the statistical estimation used in this work. This approach can also be used to highlight the deficiency in the intake and exhaust manifolds designs.