Study On The Emission Performance Of Gasoline Engine Based On Variable Valve Timing Technology

Domestic and foreign regulations become more and more strict and propose newrequest to the automobile exhaust pollutant purification. Many investigations havedemonstrated that variable valve timing technology (VVT) can not only improve thepower and fuel economy performance of gasoline engine, but also reduce emissions toa certain extent. VVT has become a new technology to control exhaust pollutant ofengine.This paper describes a research activity, concerning applying a kind of VVTsystem on a l.5L gasoline engine which invented by a domestic engine-productiveCompany. The main research work is focused on the emission performance of enginewhich influenced by the continuous variable valve timing (CVVT) system. On base ofconsulting lots of technological articles and papers, analyzing the advanced VVTmechanism both inland and overseas, researching the principle which impacts theexhaust performance in theory and summarizing the practical control strategy of VVTtechnology. Meanwhile, this paper mainly researches on the CVVT mechanism whichapplies to the experiment, including the structure, the principle of working as well asthe factors which impacts the corresponding rate.A calibration experiment was carried through in order to demonstrate the theorythat VVT technology can greatly influence the emission performance of engine. Theresult which comes from the experiment data has indicated that, intake CVVTmechanism can improve the exhaust performance under most operating modes ofgasoline engine, especially in partial loads of common condition, NOx emission canbe reduced by 10%-15% , HC can be reduced by 10%, In general, the effect onemissions of CO is little, but under high load, CO emission can be reduced obviously.Through theoretical analysis and advanced experiment method, this paperinvestigated the VVT technology, which is a relatively new measure to control enginepollutants. The conclusion is that VVT technology can not only improve dynamic andeconomic performance efficiently, but also control the harmful emission of engine, sothat providing an accurate rationale and reality basis for further developed of the VVTtechnology.