【作者】 张海峰；

【导师】 于秀敏；

【作者基本信息】 吉林大学 ， 车辆工程， 2013， 硕士

【摘要】 随着汽车技术的迅速发展，每家一车不再是梦想。近年来，汽车的产销量在我国迅速增长，2009年，我国乘用车产量为1038.38万辆，同比增长了54.11%，销量为1033.13万辆，同比增长了52.93%。随着汽车保有量的激增，国家越来越关注起汽车排放造成的环境问题。自2007年7月1日起，轻型汽车国III排放标准在全国实施，从2008年3月1日，国IV排放标准在北京市率先得到实施，与此同时，由于排放标准变得越来越严格，各种控制发动机排放的方案如雨后春笋般应运而生，发动机先进技术发展迅速。目前国内的车型，如：天津一汽的威志和N5、东风悦达起亚赛拉图、奇瑞瑞麟、一汽丰田锐志和皇冠、一汽大众迈腾、克莱斯勒300C、东风日产颐达和骐达、广汽丰田凯美瑞、北京本田CRV、北京奔驰E230、奥迪A6L等车型已经达到国IV标准。但是，国内的汽车产品与发达国家相比，在动力性能和排放水平上差距还是很大，排放的标准也一直是追随欧洲的脚步，目前欧洲已经实行了欧V排放标准，很多企业甚至已经研制出对应欧VI的产品，而国内还是国III和国IV的水平，因此国内的汽车产品要想走向世界，任重而道远。为实施贯彻《中华人民共和国环境保护法》和《中华人民共和国大气污染防治法》，切实实行环境保护，保证人们的身体健康，也为使国内车辆尾气污染物的管理和控制强度与世界接轨，国家环境保护部决定制定《轻型汽车污染物排放限值及测量方法（中国第五阶段）》这一新的环保标准。目前，编制单位已完成标准的征求意见稿，向国内汽车行业征求意见。在2013年北京首先实施国V标准，而到2016年全国都要达到国V标准。为满足国家逐渐严格的排放法规要求，本课题决定采用微型汽车上比较典型的4GFA型发动机作为研究对象，探讨并试验出汽油机达国V的方案策略。4GFA发动机是由中国第一汽车集团公司技术中心研发的直列四缸、四冲程、水冷、双顶置凸轮轴、16气门、进气VCT、电控多点喷射式汽油机，目前搭载在天津一汽的主力车型N5和威志上。这款发动机应用了链传动、VCT等先进技术，目前排放已经达到国IV水平，要达到国V有相当大的潜力，在对催化器配方、标定策略进行优化后，对发动机进行性能试验、整车标定试验和整车OBD耐久试验，在试验中进一步改进方案，寻求一种最经济条件下达到法规要求的最优化方法。本文开展的试验研究工作主要包括：1.研究4GFA汽油机的基本性能参数及国IV排放的试验数据，对比国V法规，找出差距。2.研究催化器的组成成分及工作原理，通过改良催化器成分降低排放水平。3.研究电控系统的控制策略，通过标定的办法进一步降低排放，使排放达到国V的水平。4.进行发动机性能、标定、整车OBD耐久等试验，使此发动机的排放水平达到国V乃至国V+的标准。上述试验研究结果表明：1.通过以前的试验数据得知，目前状态的4GFA发动机的HC、NOX和CO的排放值已经进入了国V的限制范围，这证明此款发动机有达国V的潜力，但是考虑到国V对耐久性和一致性的要求，目前的数值还远远不够，必须通过有效的手段进一步降低排放。2.4GFA发动机达国IV的时候采用的是国IV催化剂，具有975摄氏度稀燃尖峰80小时台架老化的特点。对应国V，又新研制了A和B配方，新配方的测试需要经过空燃比扫描试验，动态起燃温度试验、发动机台架试验和整车试验来验证，采用的发动机分别为1.4T气道喷射发动机、1.2L8V发动机、1.6L欧IV发动机；这三种发动机每种都要搭载三种配方进行对比，得出的结论为B配方无论在动态起燃温度性能、HC空燃比扫描特性还是整车排放方面都比其他两种方案更加优秀，因此4GFA发动机决定采取B方案进行国V的标定，达到了国V排放标准。3.标定策略研究中，通过改变触媒暖机迟角、起动相关补正、空燃比反馈补正和断油恢复补正达到改善排放的目的；在OBD标定中，通过改善触媒劣化、O2劣化和FTP失火等参数，来满足国V+和OBD的相关要求。a)通过某标定软件和发动机ECU建立通讯，采集车辆在NEDC循环中各工况的情况。通过对起动、过度工况（加速、减速）进行适当调整，使排放结果达到预期值（标定流程图）；b)加浓增量标定，排温模型确认：为了达到排放标准，在NEDC循环中当车辆大负荷时不进行加浓喷射（延迟加浓喷射），同时确认排气温度是否在合理范围内。c)OBD标定：需要临界催化器（失效的临界状态），失火、触媒劣化、前氧传感器失效标定。d)OBD标定完成后再进行老化、新鲜催化器验证，符合标准进行数据冻结。4.要达到国V标准，就必须进行以下10项型式核准试验，数据合格才可以通过。它们是：I型气态污染物试验（常温下冷启动后排气污染物排放试验）、I型颗粒物质量试验、III型试验（曲轴箱污染物排放试验）、IV型试验（蒸发污染物排放试验）、V型试验（污染控制装置耐久性试验）、VI型试验（低温下冷启动后排气中的CO和HC的排放试验）、双怠速试验（指测定双怠速的CO、HC的值和高怠速下的λ值）、OBD系统试验、生产一致性试验、在用车符合性试验。经过国家机构的认定，本文的试验用车均通过以上试验验证，结果理想（文中附检测结果），满足国V要求，可以量产。更多还原

【Abstract】 With the rapid development of gasoline engine technology, it is not a dream that every family has its own car. In recent years, vehicle production and sales increase fast in our country. In the year2009, passenger car production is10.38million and54.11%year-on-year growth, sales is10.33million and52.93%year-on-year growth. With the increasing of car ownership, the government is focus on the environment issue caused by the vehicle emission. From1st July2007, China Ⅲ emission standard for light-vehicle has been implemented nationwide. From1st March2008, China Ⅳ emission standard for light-vehicle has been implemented in Bei Jing first. At the same time, the emission standard have been tightened, this will cause many kinds of engine emission control technology have been applied like bamboo shoots after a spring rain, the advanced engine technology gets a rapid development. Now the Chinese brands, Veta and N5, Cerato, Rui Lin, Reiz and Crown, Magotan, Chrysler300C, Tiida, Camry, CRV, Benz E230, Audi A6L have met the EU Ⅳ emission guidelines. But comparing with the foreign brands, the performance and emission level gap is still very large. And we still follow the Europe way of the emission standard, now EU Ⅴ emission standard has been implemented in Europe, many companies have even research new products to meet EU Ⅵ standard, but the emission level in China is still EU Ⅲ or EU Ⅳ, if we want to make our products sale all over the world, it is a long way.In order to implement the "environmental protection law of the people’s Republic of China" and "the prevention Law of air pollution of the people’s Republic of China " protect the environment and people’s health, also for the domestic vehicle exhaust pollution control and management can follow the rest of the world, The Ministry of Environmental Protection decided to create "value and measurement methods for emissions of pollutants from light-duty vehicle limit (China fifth stage)" this new environmental standard. Now, consultation draft has been completed, to seek the views of domestic automobile industry. Bei Jing will implement China V emission standard first in2013, other cities will follow it in the year2016.In order to fulfill the requirement of the strict emission regulations, this paper decides to use a typical gasoline engine which named4GFA as the object of study, to find the strategy of meeting the China V emission standard. Researched by FAW technology center,4GFA is an inline four cylinder, four strokes, water cooled, DOHC,16valves, VCT-i, electronically controlled multi-point injection gasoline engine. Now it is assembled on Vita and N5which is producted in TJFAW. This engine uses chain drive, VCT and other advanced technology. Now the emission level has reached China IV, to meet China V it has considerable potential. After optimizing catalyst formulation and the calibration strategy, we do performance test, car calibration test and OBD realiability test, update the programme during the tests, find a most effective and economic way to meet China V emission standards.The research and test work of this paper include:1. Research basic performance parameters and China IV emission test data of4GFA gasoline engine, compare with China V regulation, and find the gap.2. Research composition and working principle of the catalyst, change the the catalyst composition to reduce emissions.3. Research the control strategy of the electrical control system, reduce emissions by calibration method, make the engine meet China V regulation.4. Do performance test, car calibration test and OBD realiability test, make the car meet China V or V+emission standard.The above experimental results show that,1. According to the latest test result, the emissions including HC, NOx and CO have already entered China V limits. It improves that this engine has considerable potential to meet China V, but these datas are not enough because China V also has the requirement of realiability and consistency. We must use effective methods to reduce emission further.2. The current three-way catalyst of4GFAis China IV catalyst, its performance is975℃lean-burn peak80hours stand aging. To follow China V regulation, we have researched formula A and B. The new formula requires the air-fuel ratio scanning test, dynamic light-off temperature test, bench test and vehicle test to verify. The test engine which we use is1.4T port injection engine,1.2L8V engine,1.6L Euro IV engine. Each of the three engines assembles all three kinds of formula; the conclusion is B formula in terms of dynamic ignition temperature performance, the air-fuel ratio characteristics of HC scanning and vehicle emissions is more excellent than the other two schemes. So we decide to use formula B on4GFA engine to calibration, meet the China V regulation. 3. During the calibration strategy research, we reduce the exhaust emission by changing the catalyst warm-up angle, start related correction, air-fuel ratio feedback correction and oil recovery correction. During OBD calibration, we meet the requirements of China V+and OBD regulation by improving the catalyst degradation,02degradation and FTP fire and other parameters.a) Communicate ECU and engine by a calibration software, collect informations of vehicle in different working conditions in the NEDC loop. Based on the starting conditions, excessive (acceleration, deceleration) appropriate adjustments, make the emissions results to achieve the desired value (calibration flow chart).b) Calibration of the concentrated increment, confirm the exhaust temperature model:In order to achieve the emission standard, the engine doesn’t use concentrated injection (delay concentrated injection)in the NEDC loop when the vehicle working with high load, at the same time recognize whether the exhaust temperature is in reasonable range.c) OBD calibration:we need the critical catalyst (critical state failure), fire, catalyst deterioration, oxygen sensor failure calibration.d) Verify the old and fresh catalyst after OBD calibration, if the result meet the standard then do data-frozen.4. In order to pass China V regulation,10type approval tests must be passed. They are test I gaseous pollutants (exhaust emission at room temperature after a cold start), I type particle quality test, test III (crankcase pollutants emission test), test IV (evaporative emissions test), test V (pollution control device durability test), test VI (emission test at low temperature under the cold start exhaust CO and HC), double idle speed test (refers to the determination of double idle CO, HC value and high idle speed lambda), OBD system test, production consistency test, conformance testing of the car. After the accreditation of national institutions, the sample cars can pass the above tests with the ideal result (report of test results are in this paper), meet the China V requirements, can be mass production.更多还原