【作者】 李新；

【导师】 颜伏伍； 资新运；

【作者基本信息】 武汉理工大学 ， 车辆工程， 2009， 博士

【摘要】 随着机动车排放法规的日益严格,颗粒物后处理技术已经成为柴油车排放控制的重要途径。后处理技术中最为有效的措施之一就是采用颗粒物捕集器(Diesel Particulate Filter, DPF),但对于捕集之后颗粒物的去除(即DPF的再生)问题,至今仍然缺乏简单可靠的解决方案。针对以往再生系统结构复杂,能耗过高等问题,结合我国柴油机技术现状,本文对基于喷油助燃再生的颗粒物后处理技术展开了理论与试验研究。首先,设计了集燃烧器再生与催化再生于一体的柴油车颗粒物捕集器喷油助燃再生后处理技术方案,提出了以燃烧器升温为主,柴油机氧化催化器(Diesel Oxidation Catalyst, DOC)前喷油升温为辅的两级排气升温策略。该技术方案有利于提高后处理系统能量利用率,并且燃烧器工作所需助燃空气从发动机涡轮增压器出口处获取,摒弃了空气压缩机等复杂供气系统。其次,根据柴油车排气特点,设计了喷射式与蒸发式两种全流式燃烧器,分别对其工作特性进行了研究,其中蒸发式燃烧器能够在发动机整个MAP范围内正常工作,在没有助燃空气条件下可依靠排气维持燃烧。为提高再生可靠性,对改善DPF入口温度场均匀性方法进行了试验研究；建立了DPF再生零维模型,对影响再生过程中峰值温度的DPF材质、颗粒物特性、气流特征等因素进行了数值模拟与试验研究；并对再生过程中后处理系统的二次污染问题进行了研究。再次,针对车辆运行过程中发动机转矩难以测量问题,提出了基于转速、排气温度、排气背压的三维MAP再生时机查表判断方法。为了简化控制策略,提出了对燃油喷射量与助然空气实行分段供给的控制策略,结合本文所确定的两级升温策略,按照再生功率MAP划分了燃烧器与DOC工作模式,并对不同模式下后处理系统工作特性进行了试验研究。试验结果表明,各种模式下后处理系统都能将排气温度提升至600℃以上,达到再生要求。最后,对后处理系统进行了集成与优化,对影响DPF阻力特性的主要参数、影响排气系统热损失与热迟滞的主要因素进行了研究；并在Aumark轻型柴油车(国Ⅲ车型)上实现了喷油助燃再生后处理系统的装车改造,进行了车载道路试验,改造后的整车的排放性能达到了国Ⅳ排放标准。更多还原

【Abstract】 Since the emission regulations are becoming more and more rigorous throughout the world, after-treatment technology has been paid more attentions from the viewpoint of controlling diesel vehicle emission. And diesel particulate filter (DPF) has been recognized one of the most effective ways in particulate matter (PM) emission control. But the problem of removing PM deposited in DPF, which is called regeneration process, is still not solved very well nowadays. Aiming at reducing the complexity and energy consumption of the regeneration system, this Thesis presents the research results achieved by the author on the issue of fuel injection assisted-regeneration of particulate trap for diesel vehicles.Firstly, a diesel particulate filter (DPF) system based on fuel injection assisted-regeneration is designed. In the system, the exhaust gas temperature will be enhanced by two ways:if the temperature is not heated up to regeneration temperature by a burner designed in this thesis, additional diesel fuel is sprayed before a diesel oxidation catalyst (DOC) to enhance exhaust temperature further by HC’s oxygen process. The scheme of the after-treatment system is helpful for energy efficiency. And auxiliary air used by the burner and the after-treatment system is supplied from the boosted engine intake.Secondly, two kinds of burners have been designed aiming at heating the exhaust gas. And the performance of each burner is evaluated by experiment. One of the burners, which called vaporizing-type burner, can work at the entire engine MAP. In the condition of no auxiliary air will be supplied from the turbocharger, combustion can be completed relying on the exhaust gas. In order to safely regenerate the DPF, the uniformity of temperature before DPF is improved; the factors which influence the peak temperature in DPF is investigated by simulation and experiments methods, such as:DPF material, particulate matter characteristic, exhaust gas characteristic. HC and CO emission is also controlled in the regeneration process.Thirdly, a three-dimensional MAP of engine speed, exhaust temperature, exhaust backpressure is designed aiming at estimating the mass of particulate matter retained in the DPF. The engine map is divided into several areas based on the characteristic of the after-treatment system for the sake of predigesting the control strategy. At each area, the fuel and air supply of the after-treatment system is fixed. The results of the regeneration tests show that the exhaust gas temperature can be raised to 600 deg. C in different areas of the engine map.At last, the characteristic of the DPF resistance and energy management of the burner type after-treatment system are studied. The entire system is integrated on a light duty diesel vehicle, which can meet Chinese III before. And it can meet ChineseⅣemission regulation after equipped with the DPF system.更多还原