基于燃烧闭环控制的灵活燃料发动机燃烧控制研究

发布时间：2018-01-21 21:36

本文关键词： 汽柴油灵活燃料发动机多模式组合燃烧燃烧闭环控制　出处：《清华大学》2015年博士论文　论文类型：学位论文

【摘要】：同时提升内燃机的经济性和排放性,实现内燃机清洁高效燃烧,是汽车行业面临的艰巨挑战。利用多种燃料的不同特性(灵活燃料)来弥补现有汽、柴油单一燃料在实现清洁燃烧上的不足,被认为是有潜力的切实可行方案。但如何实现其燃烧过程的精确控制,拓展工况范围,实现灵活燃料自适应,是需要解决的问题。本文以燃烧闭环控制技术为手段,从混合燃烧和混合燃料两个角度,对灵活燃料发动机的燃烧优化控制问题进行了深入研究。第一,燃烧闭环控制技术是实现灵活燃料发动机的核心控制技术。针对目前每一个气缸都装缸压传感器的方案成本高的缺点,以及传统基于曲轴瞬时转速分析算法复杂、精度低的缺点,本文创新地将两种传感器信号相结合,通过试验研究,提出了一种一个缸压传感器和曲轴瞬时转速传感器相结合的、基于信号融合进行燃烧状态估计的方法。这种方法可以大幅降低系统成本和算法复杂度,具有重要的理论价值和实际应用价值。第二,针对新概念燃烧清洁高效燃烧模式工况范围受限的问题(小负荷燃烧稳定性问题和大负荷排放受限问题),采用不同掺混比例的汽柴油掺混燃料,通过对部分预混燃烧、晚喷低温燃烧和传统压燃模式的试验对比研究,本文提出了一种在全工况范围内进行多模式组合燃烧的控制策略:在小负荷工况,通过预热塞辅助和超低压喷射策略来改善燃烧稳定性;在中小负荷采用部分预混燃烧模式实现高效清洁燃烧;在中高负荷通过晚喷低温燃烧模式实现清洁燃烧;而在高速大负荷则采用传统压燃的方式组织燃烧。随着燃料掺混比例变化,不同模式的工况范围会相应变化,但是多模式组合燃烧是在全工况范围内组织燃烧的最佳控制策略。第三,从开环控制和闭环控制两个角度,通过两种方法开展了灵活燃料自适应优化控制的研究。第一种方法是基于燃料识别的开环控制方法。通过对汽油和柴油燃料理化特性、燃烧特性的分析,分别提出了一种基于能量的、基于滞燃期的、和多参数融合算法的燃料识别方法,并进行了验证。然而开环方法具有标定工作量大和对精度要求非常高的缺点。进而研究提出了一种基于闭环控制的灵活燃料自适应控制方法,分别设计了前馈与反馈相结合的灵活燃料发动机转矩控制和经济性自适应优化控制算法,初步建立了灵活燃料发动机燃料自适应控制体系。
[Abstract]:At the same time, improving the economy and emission of internal combustion engine, realizing clean and efficient combustion of internal combustion engine, is a formidable challenge facing the automobile industry. The different characteristics of multiple fuels (flexible fuel) are used to compensate for the existing steam. The shortage of diesel single fuel in realizing clean combustion is considered to be a feasible scheme with potential. However, how to realize the accurate control of its combustion process, expand the range of operating conditions, and realize flexible fuel adaptation. In this paper, the combustion optimization control of flexible fuel engine is studied from two aspects of mixed combustion and mixed fuel by means of combustion closed-loop control technology. The combustion closed-loop control technology is the core control technology to realize the flexible fuel engine. As well as the traditional crankshaft instantaneous speed analysis algorithm based on complex and low accuracy, this paper innovatively combines the two sensor signals, through experimental research. A combustion state estimation method based on signal fusion is proposed, which combines cylinder pressure sensor and crankshaft instantaneous speed sensor. This method can greatly reduce the system cost and algorithm complexity. It has important theoretical value and practical application value. Secondly, the new concept combustion clean and efficient combustion mode operating range is limited (small load combustion stability problem and large load emission limitation problem). By using different blending ratio of gasoline and diesel fuel, the experimental study on partial premixed combustion, late injection low temperature combustion and traditional compression combustion mode was carried out. In this paper, a control strategy for multi-mode combined combustion in the whole operating condition is proposed. In the small load condition, the combustion stability is improved by pre-heating plug auxiliary and ultra-low pressure injection strategy. Using partial premixed combustion mode to realize high efficiency clean combustion in medium and small load; Clean combustion is realized by late injection low temperature combustion mode at medium and high load. At high speed and high load, the combustion is organized by traditional combustion-burning method. With the change of fuel mixing ratio, the operating range of different modes will change accordingly. But the multi-mode combined combustion is the best control strategy in the whole operating conditions. Third, from the open-loop control and closed-loop control. The flexible fuel adaptive optimal control is studied by two methods. The first method is an open-loop control method based on fuel identification. The physical and chemical characteristics and combustion characteristics of gasoline and diesel fuel are analyzed. A fuel-recognition method based on energy-based, time-delay and multi-parameter fusion algorithms is proposed. However, the open-loop method has the disadvantages of high calibration workload and high precision. Then, a flexible fuel adaptive control method based on closed-loop control is proposed. The flexible fuel engine torque control algorithm and the economy adaptive optimization control algorithm are designed, and the fuel adaptive control system of the flexible fuel engine is preliminarily established.
【学位授予单位】：清华大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TK401

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