【作者】 李云强；

【导师】 姚春德；

【作者基本信息】 天津大学 ， 动力机械及工程， 2009， 博士

【摘要】 随着柴油机排放法规限值日趋严格及柴油机技术的不断进步,开发满足中国III、国IV号排放标准的柴油机已成为目前我国柴油机工作者的迫切任务。根据我国柴油机产业技术现状和市场需求,在现有两气门柴油机的基础上研究满足国III排放标准的燃烧技术以及满足国IV标准的柴油机燃烧和后处理技术显得尤为重要。本课题采用德国博世第二代电控高压共轨系统EDC7,在潍柴动力股份有限公司WD615(单缸两气门)增压中冷柴油机基础上,研究开发了满足中国III阶段排放标准的两气门电控柴油机。在此基础上,采用博世DeNOx2 SCR控制系统,匹配国际先进的SCR后处理器,研究开发了满足中国IV阶段排放标准的柴油机。1.对比分析了不同电控系统的优缺点,确定在两气门WP10国III柴油机上选用博世公司的电控高压共轨系统。并在EFS高压共轨试验台上对影响燃烧的主要部件-电控喷油器的喷油规律进行测试和研究。2.对影响发动机燃烧和排放的原WD615国II柴油机的主要零部件进行了配置优化,优化活塞环以降低机油消耗,进而降低颗粒排放。优化燃烧室,改善燃烧室内气流运动分布规律的同时,改善扩散燃烧减少颗粒排放。对不同喷油器和增压器进行优化,选出了最佳配置。3.在确定发动机最佳配置的基础上,通过燃烧分析手段,对不同喷射压力、提前角以及多次喷射的发动机热力学性能进行分析研究,为改善发动机性能,降低发动机排放提供燃烧方面的理论支持。4.研究了电控高压共轨系统控制策略,通过优化喷油压力、定时、预喷、后喷等参数,对发动机的性能进行全面的燃烧开发和标定,使柴油机达到国III排放标准,测试结果为:NOx=4 .80g/kW.h,PM=0.08g /kW.h ,CO=0.45g/kW.h,HC=0.30g/kW.h,ELR烟度:0.46 m-l。5.通过研究分析确定采用SCR技术路线达到中国IV、V阶段最佳方案,根据两气门WP10柴油机实际情况,优化设计了SCR系统,研究了SCR对NOx的催化转化的历程,并通过对柴油机的SCR稳态温度、尿素喷射量、稳态及瞬态的开发标定,使两气门WP10柴油机达到国IV排放标准,测试结果ESC循环:NOx =2.91g/kW.h,PM=0.014g /kW.h,CO=0.38g/kW.h,HC=0.054g/kW.h,ELR烟度:0.042 m-l,ETC循环:NOx=2.83g/kW.h,PM=0.017g /kW.h,CO=0.094g/kW.h,HC=0.129g/kW.h。更多还原

【Abstract】 With the increasingly stringent exhaust emission standards of the diesel engine as well as the development of the diesel engine technology, it is very imperative for China to design a diesel engine that can meet Chinese Phase III and IV standard. This study aims to develop this type diesel engine using advanced combustion and exhaust gas after-treatment technologies on the basis of existing diesel engine with 2-valve per cylinder. More and more extraordinary development efforts have been required by improved combustion processes and tailpipe emissions by new exhaust gas after-treatment systems.This investigation was conducted on a current production turbocharged, inter-cooled, Model WD615 diesel engine manufactured by Weichai Power Co. Ltd., which fulfill Phase II emissions standard. This study is concentrated on two basic problems. The first part deals with the diesel engine to meet Phase III, which equipped with the second generation of the Bosch common rail system (Model EDC-7) with some optimized engine parameters. The second part deals with the optimized engine using a selective catalytic reduction (SCR) system to meet Phase IV. On the new development engine basis, the further developed diesel engine retrofitted by SCR system controlled by the Bosch DeNOx2 can meet Phase IV emission requirements in China.The basic approach to the research, according to the mentioned objectives (two parts), can be noted as follows:1. The advantages and disadvantages of different electronic control systems have been discussed and the Bosch common rail system was retrofitted onto the Model WP10 diesel engine. The characteristics investigation related with combustion process of the electronically controlled injector have been performed on the high pressure common rail test bench.2. The essential parameters of the combustion system, including piston rings, combustion chamber shape, injection system and turbocharger have been optimized for the base engine WD615. The aim was to achieve low lubricant oil consumption and low particulate matter (PM) emissions through improving intake flow characteristics. Finally, the optimized design parameters are determined. 3. On the basis of the optimized parameters, the effects of different injection pressure, ignition timing and multiple injections have been investigated to evaluate thermodynamic performance by heat release analysis. The test results provide a theoretical basis to support the lower exhaust emissions and improved engine performance.4. The control strategies for high pressure common rail have been carefully considered to optimize fuel injection pressure, injection timing, pilot injection and post injection. To fulfill Phase III emission standard, the test engine was completely developed and calibrated. The results obtained for regulated emissions are illustrated below with Phase III emissions limits in brackets. NOx=4.80(5.0)g/kW.h, PM=0.08(0.10)g/kW.h, CO=0.45(2.1)g/kW.h, HC=0.30(0.66)g/kW.h and smoke opacity with ELR(European Load Response Test)=0.46(0.8)m-1, which are below the Phase III limits.5. The effects of the SCR system on NOx reduction was carried out on Model WP10 diesel engine. To optimize the SCR system, steady conditions of temperature, injection amount of Urea and calibration for steady and transient operating conditions have been investigated. The detailed result data from the test engine operating with (European Steady State Cycle) ESC and ETC (European Transient Cycle) test cycle are shown as follows, respectively. For ESC cycle: NOx=2.91(3.5)g/kW.h, PM=0.014(0.02)g/kW.h, CO=0.38(1.5)g/kW.h, HC=0.054(0.46)g/kW.h and smoke opacity with ELR=0.042(0.5)m-1. For ETC cycle: NOx=2.83(3.5)g/kW.h, PM=0.017(0.03)g/kW.h, CO=0.094(4.0)g/kW.h, HC=0.129(0.55)g/kW.h. The test results measured in regulated emission meet Phase IV emission standard.更多还原