多次点火对喷雾引导分层稀薄燃烧性能的影响

Effect of Multi-Ignition on the Performance of Spray-Guided Stratified Combustion

在一台喷油器中置的单缸直喷汽油机上,基于2,000,r/min、平均指示压力(IMEP)为0.3,MPa的工况,研究了多次点火技术对喷雾引导分层燃烧性能的影响.基于NI Com Pact RIO开发了一套单缸机控制系统,成功实现多次点火并应用于试验.结果表明:多次点火技术增加了点火次数和点火能量,改善了分层燃烧的稳定性.在相同的喷油开始时刻(SOI)为50°,CA BTDC时,多次点火的稳定点火窗口比单次点火增加了15°,CA.此外,多次点火能拓展分层燃烧的EGR率容忍度.随着EGR率的提高,分层燃烧相位推迟,燃油消耗率及排放可以得到优化.相比单次点火,在SOI为50°,CA BTDC、点火时刻(IGN)为40°,CA BTDC时,其EGR率上限可以从15%,拓展到22%,,指示燃油消耗率(ISFC)降低约3%,,NO_x排放降低约20%,;在EGR率同为15%,时,其THC排放降低约10%,,CO排放降低约8.3%,.

Effects of multi-ignition on spray-guided stratified combustion performance at part load(2,000,r/min,IMEP=0.3,MPa)were investigated on a single-cylinder GDI engine with centralized mounted injector.Based on NI Com Pact RIO,an engine control system was developed to achieve the multi-ignition.Results show that multi-ignition improves the stability of stratified combustion because of the increased ignition time and energy.For the same start of injection(SOI)timing(SOI=50°,CA BTDC),the stable ignition window extends by 15°,CA compared with that of the single-ignition.Furthermore,multi-ignition enhances the torelance on the exhaust gas recirculation(EGR)of stratified combustion.With the increase of EGR ratio,the phase of stratified combustion is postponed,and fuel economy and emissions are optimized.At same injection and ignition(IGN)timings(SOI=50°,CA BTDC,IGN=40°,CA BTDC),the upper limit of EGR ratio is extended from 15%, to 22%,,resulting in a significant reduction in the indicated specific fuel consumption(about 3%,)and NO_x emission(about 20%,).Meanwhile,at same EGR ratio(15%,),multi-ignition also has lower THC(about 10%,)and CO(about 8.3%,)emissions.