Using EGR And Electronically Control Technique To Derease NOx Emission From Diesel Enigne

With the increasing of automobile numbers, automobiles gradually become the main source of air pollutions. In particular, the increasing percentage of diesel vehicles in the whole power vehicles will worsen the air quality, as the diesel engines emit a great deal of PM and NOx. It is difficult to decrease PM and NOx simultaneously by engine modification. Besides, their corresponding technologies are not mature and largely applied, therefore research for the control of diesel engine emissions has great social and practical significance.The main aim of the thesis is to develop a kind of model system that uses variable EGR ration for control in order to decrease NOx eficiently. Subordinately, the technology for reducing both NOx and PM is also studied.Based on the advanced technological measures for control of NOx emission, (in particular exhaust gas recirculation (EGR) system) and the earlier studies of particulate trap system-bag filter system and electronically controlled EGR system, a new kind of electronically controlled model system is developed for SD1110 diesel engine. This m odel has three characteristics: First, a new method using fuel pump rack position signal to replace exhaust temperature signal is adopted to fix on the working point, which solved the problem of slow response, long adjustive control period in the earlier electronically controlled EGR system. Second, the EGR value designed by author, which has simple configuration and can be drive neatly, is applied in the controlled EGR system. Third, the new control strategy and arithmetic are adopted. In the thesis, the arrangement of EGR system and control strategy are studied, the performance of electronically controlled EGR system is introduced in detail. At the same time, the combination of the new model system and bag filter system are investigated.