Study On Fuel Control Strategy About Electronic Fuel Injection (EFI) Gasoline Engines For Euro Ⅲ

With the rapid development of economy in the world, more and more attentionsfrom the government and society are paid on vehicle emissions. After application ofElectronic Fuel Injection (EFI) and Three-Way-Catalyst (TWC) in gasoline engine,more than 90% of CO, NOX, THC emitted from the engine is reduced. The fuelcontrol is very important for Euro â…¢ emission. The fuel control matching is one ofthe most important parts in engine management system. It can influence not onlyemission but also drivablility.But during fuel control process the Air-Fuel-Ratio (AFR) shows an excursion,resulting in a low conversion efficiency of TWC because of the inexact control whichmaybe on account of the engine consistency and aging. Therefore, study on emissioncharacteristic of EFI engine is very important. This paper analyzed the emissioncharacteristics of EFI engine. The fuel control theory of EFI system was explainedthrough the description of the start,transient and steady state control logic of DelphiMT20 EFI system.It is concluded that during start process, AFR should be used as lean as possiblebut to assure start stability. There is no misfire in transient acceleration. But intransient deceleration, some misfire cycles can be found. In this case, emissions due tothe misfire in transient deceleration should be concerned. In addition, AFR fluctuationis beneficial to transient emissions because of the oxygen storage effect of TWC.After optimization of different combinations of modification terms, one set ofparameters is picked up for good emission result.One novel fuel control strategy with linear oxygen sensor is developed throughanalyzing different phases' emission results. This strategy's aim is to control the AFRat stoichmetric and make TWC's conversion efficiency higher. We can see that it isvery useful to reduce emission from the experimental data.