| Compared to gasoline engine,diesel engine has good performances of power, economy,reliability, higher thermal efficiency and lower emissions of CO and HC. The diesel engines of non-road mobile machinery have been widely used,but the higher emissions of NOx and PM are the problems that restrict its development. How to reduce the diesel’s emission effectively and meet the more strict emission legislation’s demand is the problem to be solved urgently.The research engine is a diesel engine of non-road mobile machinery in this thesis. It is optimized and improved to meet the more strict emission legislation’s demand. Firstly, diesel emission legislation and emission control technique of domestic and overseas are analyzed. The real situation of the diesel engines of non-road mobile machinery and the emission control route of domestic and overseas are considered. The selected emission control route is EGR.The related information and data of diesel engines of non-road mobile machinery is collected, and the complicated engine is divided into several subsystems that are easy to be handled. The AVL BOOST model of diesel engines of non-road mobile machinery is used and the relevant parameters and boundary conditions are determined, the influences of fuel injection timing and fuel injection pressure on the performance of engine are analyzed based on the validity of the model. Optimized measures are put forward with the combination of the simulation results and real situation of the diesel engine of non-road mobile machinery. The measures include: the model selection of injector, the optimization of fuel pump, the optimization of fuel injection timing, the optimization of EGR.Then, the test bench is established and the experiments have been carried out about the optimized measures. The influences of injector, fuel pump, EGR cooler to the engine main performances are measured and analyzed. The measures are confirmed by the analysis of experimental results and simulation results. Finally, 1mm beetle height of nozzle, 26 MPa injector opening pressure and suitable fuel pump, also the best fuel injection timing and EGR of best emission performance are confirmed.Finally, the 8-working test is carried out on the optimized diesel engine of non-road mobile machinery, and its result is showed as follows: NOx: 3.577 g/(kW·h), PM: 0.175 g/(kW·h), CO: 1.625 g/(kW·h), HC: 0.175 g/(kW·h). |
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