【作者】 黄颖；

【导师】 杨福源；

【作者基本信息】 清华大学 ， 动力工程及工程热物理， 2010， 硕士

【摘要】 能源问题和环境问题迫使汽车行业寻求更为高效和清洁的解决方案。柴油机已经具备高燃烧效率的优势,然而其排放问题始终是一个难题。HCCI燃烧技术为其提供了同时大幅降低PM与NOx排放的潜力,然而其燃烧状态不稳定和工况范围狭窄等问题限制了它向实用化发展。近年来,随着量产型缸压传感器的出现,燃烧闭环控制技术逐渐成为支撑HCCI燃烧的一项新型平台技术。本课题在第一代燃烧状态解析单元的基础上,开发了新一代的燃烧闭环控制系统平台,并以此为基础开展了两项应用研究:基于缸压信号的燃油喷射控制与基于燃烧闭环控制反馈的起动过程优化。本论文从硬件和软件两个方面对新一代燃烧状态解析单元(iCAT)进行了重新设计。iCAT通过4路缸压传感器获取缸内压力信息,实时计算燃烧状态指标,并通过CAN总线或者BDM通讯方式与ECU进行数据交换,ECU根据这些反馈信息完成对发动机的燃烧闭环控制。通过与专业燃烧分析仪离线计算结果的对比实验,验证了iCAT对主要燃烧状态指标的计算准确性。基于新一代燃烧闭环控制系统平台,提出了基于缸压信号的燃油喷射方法,包括基于缸压信号的气缸识别和曲轴相位估计两个方面。从原理上对利用缸压信号进行气缸识别和曲轴相位估计进行了分析,提出了假想最大倒拖缸压模型,以完成曲轴相位的估计。实验结果表明,利用缸压信号可以实现气缸识别,简单且可靠,进行曲轴相位估计时可以为燃油喷射提供1°CA的估计精度。本论文在发动机起动过程中实现了燃烧闭环控制。通过建立发动机起动过程模型,设计了起动过程的燃烧闭环控制算法。验证实验表明,燃烧闭环控制算法有助于发动机在各种环境条件下实现对期望加速曲线的跟踪,各缸的燃油喷射参数可以根据各缸的燃烧状况进行独立的调节。由此可以显著降低起动过程的标定工作量,保证起动的可靠性,避免过度的燃油喷射,进而限制起动过程的排放。更多还原

【Abstract】 Energy crisis and environmental concern would require a more efficient andcleaner solution for automotive industry. Diesel Engine already has its advantage in thehigh combustion efficiency. But it has unsatisfactory emission issue. HCCI combus-tion technology provides the potential to reduce PM and NOx emissions dramaticallysimultaneously. But the problems of unstable combustion and narrow operating rangeprevent it from pratical use. In recent years, with the use of mass production type in-cylinder pressure sensor, combustion closed-loop control is becoming a key platformtechnology to support HCCI combustion. In this thesis, based on the first generation ofin-cylinder Combustion Analysis Tool (iCAT), the new combustion closed-loop con-trol system is developped. Two applications on the new platform are investigated: cyl-pressure based fuel injection method and combustion closed-loop control under enginestart conditions.The new generation of iCAT is redesigned in hardware and software. iCAT ac-quires and processes the cylinder pressure information from 4 in-cylinder pressuresensors. Combustion indices are calculated and delivered to ECU through CAN busor BDM communication. Closed-loop control is accomplished in ECU based on thisfeedback information. From the comparison tests with professional Combustion Anal-ysis System (CAS), the calculation accuracy of important combustion indices fromiCAT is verified.Based on the new combustion closed-loop control platform, a cyl-pressure basedfuel injection method is investigated. Cylinder identification and crank angle estima-tion with cylinder pressure are analysed in theory. Max. motoring pressure model isused to estimate the crank angle. Experimental result shows, cylinder identificationcan be achieved using cylinder pressure in a simple and robust mannor; crank angleestimation can provide a precision of within 1°CA for fuel injection.Combustion closed-loop control is applied in engine start process. Through an engine start model, the engine start feedback control algorithm is designed. From ex-perimental validation, the algorithm is proved to be effective in tracking a predefineddesired speed-up curve at didderent conditions. Injection parameters in each cylinderwould be adjusted individually according to the corresponding combustion state. Cali-bration e?ort can be notably reduced. The robust ability of engine start-up is enhancedwhile unnecessary fuel consumption is avoided and pollutant emissions are suppressed.更多还原