【作者】 韩志强；

【导师】 黄海波； 曾东建；

【作者基本信息】 西华大学 ， 动力机械及工程， 2007， 硕士

【摘要】 DME是甲醇系列衍生物之一，也是一碳化工的重要中间体，应用广泛。国内外实验研究表明，其燃烧尾气不需催化转化处理就可以达到欧洲Ⅲ级排放标准。所以，国内外专家一致认为，二甲醚的开发，不仅具有经济性、环保性，更具有战略性。但是二甲醚的弹性模量小，易压缩；常温常压下为气态等决定了它在柴油机上应用，需要选择一种适合该燃料应用的喷射系统，并对选用的喷射系统进行改造。电控单体泵结构简化，喷油量和喷油正时控制灵活，喷射压力高，定时波动较小，这些特点有利于二甲醚的应用。结合二甲醚燃烧特性及喷射系统开发项目，本文对二甲醚在电控单体泵上的应用提出了改进建议，并通过计算机仿真技术和油泵试验，讨论了其喷射特性，制定了电控单体泵燃用二甲醚的控制策略。本文首先介绍了二甲醚的物化特性和国内外将二甲醚作为代用燃料的研究现状，分析了国内外柴油机燃油喷射系统发展现状，通过对二甲醚性质特点的深入研究，将二甲醚燃油喷射系统进行模拟仿真，制定一套适合二甲醚燃油喷射系统的控制策略，并将控制策略运用到发动机中，实现对二甲醚发动机各工况的精确控制。为二甲醚代替柴油后，改善燃烧和排放的实现提供可行性，并为进一步的研究提供硬件基础。本文通过AMEsim4.30软件建立电控单体泵模型，然后根据制定的控制策略，得到不同工况下的仿真结果。仿真结果表明，在电控单体泵上应用二甲醚时，虽然降低针阀起喷压力，但二甲醚弹性模量小，易压缩，导致喷油器盛油腔内压力波动较大。泵端和嘴端最大压力随柱塞直径的增大而增大。对于主预喷射方式的控制策略，主喷射脉宽变化引起的压力波变化不大，但预喷射脉宽和主预喷射间隙所导致的两个压力波的叠加问题，是影响针阀运动变化的主要因素之一，需慎重考虑两波的相位关系。因此，要调整二甲醚电控单体泵供油系统的喷射性能可以从以上方面着手。此外，本文结合国内外对二甲醚的研究，搭建了机械泵的试验台架，根据试验数据进行了MAP图的初始化标定，结合该试验和仿真结论设计了电控单体泵油泵试验的内容和方法。最后，本文得出结论，根据仿真结果和试验结果的对比分析，适当的改变电控单体泵的关键结构参数和制定合理的燃用二甲醚的控制策略，可以满足二甲醚在电控单体泵上的现实使用。更多还原

【Abstract】 DME is the one of the ramifications of methanol, it is also an important intermediate of carbon chemistry industry, and applying very widely. Experiments in domestic and abroad showed that its emission could easy to reach Europe III emission criterion without catalyzing disposal. Therefore, the experts in domestic and abroad believed that using DME not only was economization and protecting the natural environment, it also had strategic significance. However, the bulk modulus of elasticity is too small for DME, and it is gaseity in normal temperature and pressure Although there were some problems to be solved if we wanted to apply the DME on diesel engine. All the problems summed up were how to choose injection system, considering the merits of the DME as well as how to modulate construct parameters of the system to adapt to the fuel.At the same time, structure of EUP was simplified, and it was flexible to control the fuel injected and injection timing while fluctuation of timing was improved consequently. All these merits were helpful for the application of DME on diesel engine. Associating combustion characteristic and the project of devise injection system, this study combined simulation technical and pump test bench .Reforming advices and controlling strategies in general were also put forward on researching results.At first, the physical and chemical merits of DME were introduced and research actuality in domestic and abroad of DME as a substitute fuel. Then analyzing the development of diesel injection system in domestic and abroad. According to deeply research the characteristic of DME, and putting up simulation of DME injection system, we established a useful control strategy to ECU, and applying to the DME engine. It could make precise control of DME engine come true. It also supplied the possibility of improve combustion and emission after DME substitute diesel. Do the further researches, we could make hardware according to the simulation. Using the software of AMEsim4.30 to built electronic unit pump model, and established a useful control strategy in ECU, it was easy to get kinds of result of different working condition. The simulation results showed that applied DME to electronic unit pump injection system, and decreased needle open pressure were caused higher pressure wave in injection chamber, because the bulk modulus of elasticity is too small for DME and it was compressible. With the increased of plunger diameter, the maximum pump pressure and injection pressure were also increased. Changing main injection PWM wasn’t caused pressure fluctuation. However, changing pre-injection PWM and interval PWM were make two pressure waves superpose, and it also caused needle move. We need considerate the phase problem of two pressure wave when they were superposed. Therefore, improving the injection capability need change the key parameters of DME injection system of electronic unit pump.Furthermore, according to the research of DME in domestic and abroad, we built an experiment rig and wrote down the experiment data of pump and injection chamber pressure wave. Then compared the experiment data with simulation result, we devised the way of pump experiment of EUP and carried out the initialize demarcation.At last, we drew a conclusion that improved some key parameters of electronic unit pump and established a useful control strategy in ECU, it made the possibility of DME applied to EUP come true.更多还原