Study On The Diesel Engine’s Exhaust Temperature Improvement Technologies In WHTC Cycle

In recent years, persistent fog and haze serious impact on people’s lives, for the source of haze, the community has done a lot of research and analysis, Among them, the high proportion of vehicle emissions, more than 30%, some cities have more than 50%.Reducing vehicle emissions has become the focus. for municipal vehicles with SCR technology route, especially buses, sanitation(such as: garbage trucks and sprinkler vehicles) and other municipal vehicles, the actual operating conditions tend to the low-speed、 low-load conditions, exhaust temperature of this area is low, the efficiency of after-treatment systems is low,NOx emissions during operation excesses the regulation standard seriously. Accordingly, Beijing and the country has issued a DB11 / 964-2013 and HJ689-2014 standards for municipal vehicles engine, request for additional WHTC test cycle. As for the implementation of regulations, since April 1, 2016, in the eastern 11 provinces(Beijing, Tianjin, Shanghai, Hebei, Liaoning, Jiangsu, Zhejiang, Fujian, Shandong, Guangdong and Hainan) all imported、sale、registered light diesel bus and heavy diesel vehicles are required to meet the State V emission standards.Because of WHTC cycle low exhaust temperature, most conditions can not meet the urea injection conditions,even if injection, Nox conversion efficiency is relatively low, making it difficult to control emissions and ammonia leak.at the same time, SCR prone to crystallization problem. Therefore, it is the most fundamental measure to ensure the State V WHTC city bus driving cycle meet emissions that improving exhaust gas temperature entering the SCR tank.Weichai diesel engine with turbocharged and common rail is selected as the research object of the issue, optimizating Piston chamber contour and cam shaft profile by performance simulation, CAE simulation to improve the temperature of the exhaust gas。...