文档介绍：华中科技大学
硕士学位论文
汽油机油膜动态效应及瞬态空燃比控制的研究
姓名:舒咏强
申请学位级别:硕士
专业:动力机械及工程
指导教师:李顶根
20090525
华中科技大学硕士学位论文
摘要
对于进气道多点喷射汽油机而言,进气道油膜动态效应是导致瞬态空燃比控制出
现偏差的主要原因。研究瞬态油膜动态效应,并在此基础之上展开瞬态空燃比精确控
制研究,是改善汽油机瞬态燃烧,提高燃油经济性、动力性以及排放性的关键所在。
为分析附壁油膜动态效应,对某进气道多点喷射汽油机的燃油喷射碰壁及蒸发过
程进行模拟。模拟过程中,分别就不同喷射参数、进气道壁面条件以及进气条件展开
对比研究。模拟结果表明,喷射锥角、喷射高度、进气道壁温以及进气流速对附壁油
膜形状及质量分布、燃油液态颗粒空间分布影响较大。此外通过模拟发现,悬浮燃油
颗粒的逐渐沉积是附壁油膜的另外一个重要来源,且即使是一次喷射所形成的附壁油
膜完全累积过程和蒸发过程将持续很长时间,是燃油传输迟滞的根本原因。
对油膜现象建模并对模型参数辨识展开研究,结合最小二乘法及夏氏偏差修正法
对模型参数进行辨识,辨识对比结果表明夏氏法辨识所得结果离散程度优于最小二乘
辨识。在模型参数辨识的基础上,展开油膜模型补偿研究,在 Matlab/Simulink 环境下
对油膜模型仿真标定进行了仿真研究。设计了一种基于 BP 神经网络的喷油脉宽预测
模型,与标定实验所得喷油数据对比结果表明预测误差较小。结合进气系统模型、油
膜模型、BP 神经网络模型对瞬态空燃比进行了仿真研究,仿真结果表明所建立的空
燃比预测系统预测值的最大偏离值小于原始模型,对瞬态空燃比的控制可以发挥有效
作用。

关键词:汽油机,空燃比控制,油膜动态效应,喷雾碰壁,参数辨识,神经网络
I
华中科技大学硕士学位论文
Abstract
For intake manifold multi-point fuel injection (MPI) of gasoline engine, the dynamic
effect of fuel film is the main reason to excursion of transient A/F ratio control. In order to
improve the bustion and fuel economy, increase the specific output power, and
reduce the exhaust emission, the transient A/F ratio should be accurately controlled based
on the dynamic effect study of the transient fuel film.
Gasoline engine with intake manifold MPI system was studied in this thesis, and in
order to analyze the dynamic effect of the fuel film, spray impingement and evaporation
characteristics of fuel injection were simulated. The simulation was studied under different
injection parameters with varying intake manifold wall setup and intake air conditions.
Among all the parameters, the formation and concentration of fuel film and spatial
distribution of liquid fuel particles were more influenced by injection angle, intake air
speed and the wall temperature of intake can be demonstrated by the
simulation result, the gradual deposit of suspended fuel particles was another important fuel
film source besides the direct spray impingement