【作者】 李兴；

【导师】 刘书亮；

【作者基本信息】 天津大学 ， 动力机械及工程， 2005， 硕士

【摘要】 环境和能源两大问题迫使发动机面临既要在保证动力性的前提下降低燃油消耗,又要满足排放法规的严峻局面。稀薄燃烧技术是汽油机提高部分负荷经济性和降低排放的有效措施。利用二次燃油喷射技术可以在丰田8A发动机上实现准均质稀薄燃烧,但准均质稀薄燃烧的点火提前、喷油定时、空燃比等参数的控制和调整会给发动机控制带来更高的要求。基于此,本文创造性地提出了将虚拟仪器和发动机电控技术相结合的新思路。按照这个思路去开发一套稀薄燃烧测控系统,其中用LabVIEW编写上位机软件完成发动机各种参数的采集,而由单片机去完成发动机的点火、喷油控制。这样既利用了LabVIEW在数据采集上的优势,又发挥了单片机在实时控制上的长处,可以为发动机稀薄燃烧性能和排放试验提供一个既可靠又方便的平台。利用新系统我们进行了大量实验,实验中能多角度地监视发动机的运行状况,采集的数据也能随时存入数据库。此外,借助于PC和单片机之间的串口通信,可以通过上位机软件来完成对发动机的控制。另外我们对稀薄燃烧过程也进行了一些研究,得出了本稀燃发动机在各种空燃比下的油耗和排放特性,并从机理上对它们进行了分析。结合汽油机稀薄燃烧NOX排放问题,本文从机内、机外两方面探讨了一些解决途径。通过适当推迟点火提前角可以在稍微牺牲经济性的前提下使NOX排放大幅度降低。使用分子筛选择还原催化剂可以在高空燃比下让准均质稀薄燃烧满足较为严格的排放法规。更多还原

【Abstract】 The problems of environment and energy sources make the engine notonly meet emission control regulations, but also reduce fuel consumptionin the same power. Lean burn is an effective measure to reduce emissionand improve fuel economy of gasoline engine in partial load. With theTwice Electronic Fuel Injection Technology, quasi-homogeneous mixturelean burn can be realized in Toyota 8A engine. But, it demands moreaccurate control of ignition timing, injection timing and air /fuel ratio.Based on virtual instrument and electronic control technology, ameasure and control system for the quasi-homogeneous lean burn isdeveloped. It is a reliable and convenient tool for the experiments of leanburn gasoline engine. The software programmed by LabVIEW 7.0 canacquire all kinds of parameters of the engine, and the SCM control theignition and injection of the engine. So, we combine the advantages of theLabVIEW and of SCM, which is a new way for the measure and control ofthe engine.With the system, the manipulator can save the acquired data in adatabase freely and adjust the engine in the software by the serialcommunication between PC and SCM.Many experiments on lean burn have been finished with thedeveloped system. We compare the fuel consumption and emission of theengine in the different air/fuel ratio, and explain reasons of the differencebetween them.Because NO_x from the lean burn gasoline engine cann’t meet thedemand of the emission regulations facilely, this kind of engine hasn’tbeen used popularly. To reduce the NO_x from it, some measures arediscussed in this paper. And many experiments prove that delay ignitionand HC-SCR have good effects.更多还原