【摘要】 为改善柴油机预混合燃烧(PCCI)模式下的燃烧稳定性和分缸均匀性,研发了基于缸压的闭环反馈控制技术.该系统采用由两个控制单元组成的分布式结构,燃烧状态解析单元(iCAT)实时采集发动机各缸缸压-曲轴转角数据,计算缸内燃烧状态指标如平均指示压力(IMEP)、50%放热点(CA50)等,并将结果通过CAN网络发送到发动机控制单元(ECU),ECU据此对喷油参数进行调整,以精确控制发动机的燃烧状态.试验在一台经过系统升级的4缸2.5,L高压共轨柴油机上进行,结果表明,iCAT实时计算精度与燃烧分析仪测量精度基本一致,与燃烧分析仪数据相比,IMEP最大偏差为0.53%,CA50最大偏差为0.33,°,CA,闭环控制后,无论是传统CI燃烧还是PCCI燃烧,燃烧稳定性和各缸不均匀性都得到明显改善.更多还原

【Abstract】 To improve the combustion stability and decrease the cylinder-by-cylinder variations of diesel engines in PCCI combustion mode,a close-loop control strategy based on in-cylinder pressure is proposed.The control system consists of a distributed structure,a comprising in-cylinder Combustion Analysis Tools(iCAT)and an ECU.iCAT collects the real time information of in-cylinder pressure versus crank angle,calculates the combustion parameters like IMEP and CA50,and feedbacks the information to ECU through CAN.ECU adjusts the control parameters according to these results to precisely control the combustion.Test was made in a modified 2.5 L 4-cylinder common-rail diesel engine.Results showed that,the real-time values calculated by iCAT were in accordance with those off-line results calculated by combustion analysis device.When close-loop control strategy was used in either CI or PCCI combustion model,the combustion stability was improved and cylinder-by-cylinder variations was minimized.更多还原