小型增压直喷发动机PN排放特性研究

摘要

With the global energy situation and the environment deteriorate more and more serious,energysaving and emission reduction have become a major task of all the auto companies at the moment.To achieve this goal,OEMs and engine design manufacturers aim at the smaller,lighter Turbocharged direct injection engine (TGDI).By increasing the injection pressure and the effective supercharger controlling,the same or higher power output is obtained than the naturally aspirated with larger displacement or conventional supercharged engine,while the fuel economy of the engine increases.However,since the fuel of TGDI is injected directly in the cylinder,it can't provide sufficient time for the mixture to be mixed evenly,resulting in a partial overpressure of the mixture and a large amount of PM and PN emissions during combustion.In the condition of China 6 emission regulation,during most of the time the vehicle is in the acceleration or high speed states,thus it needs larger power demand.The long-term work in large load area of downsized TGDI to ensure reliable power output also causes more emissions of PM and PN.%随着全球能源形势越来越严峻,环境不断恶化,节能减排成为当前所有汽车企业面临的一个主要任务.为达到节能减排的目的,汽车及发动机设计制造商们均对准了体积更小、重量更轻的小型增压直喷发动机,通过提高喷射压力及有效的增压器控制以获得比更大排量的自然吸气或普通增压发动机同等或更高的动力输出,同时提高发动机的燃油经济性.然而,由于增压直喷发动机在缸内直接喷射,不能为混合气均匀混合提供足够的时间,从而导致混合气局部过浓,在燃烧时产生大量的PM和PN;国六排放工况中,车辆大部分时间处于加速或高速状态,对车辆动力需求较大,小排量增压直喷发动机为保证可靠的动力输出,长期工作在大负荷区域,也造成较多的PM和PN排放.