Analysis And Research Of Hybrid Bus Emission Characteristics

With the increasing oil supply shortage and growing environmental pollution, energy-saving vehicles have become the focus of attention gradually. Compared to pure electric vehicles and fuel cell vehicles, hybrid electric vehicles will be more hopeful to take the lead in achieving industrialization and commercialization, although it can not achieve zero fossil fuel consumption and zero emissions. Compared with traditional vehicles' cost, it is far less than the increase in fuel cell vehicles. Current hybrid vehicles' technology become more and more mature, industrialization has been approaching. With respect to the traditional internal combustion engine vehicle, hybrid electric vehicle's exhaust emission level is still a very vague question.The existing heavy vehicle emissions evaluation method is to assess the exhaust emissions by the engine test bed. However, it is very inappropriate to evaluate the emissions level of hybrid vehicles only based on the engine. Heavy-duty hybrid vehicles have a set of auxiliary electric power device which is designed to achieve the purpose of energy-saving and reduce emissions in accordance with the actual vehicle driving cycle, so the engine's actual operating conditions vary greatly and it has great limitations to evaluation emissions and energy consumption of the hybrid vehicles only by the engine.This study used the PEMS (portable emission measurement system) based on the actual working conditions of whole vehicle to measure the emission of the heavy-duty hybrid electric vehicle (HDHEV), to evaluate energy-saving and emission-reduction effect of HDHEV and to analyze the emission characteristics difference.This study compared the emission difference of series and parallel hybrid vehicles under four typical driving conditions. It also contrasted the transient emission difference between parallel hybrid vehicles and conventional vehicles and analyzed the emission reduction effect in depth.This study also analyzed the transient degree of hybridization (DOH) distribution of parallel hybrid vehicles and the effect of DOH and SOC on emission. It analyzed the engine load distribution of the hybrid electric vehicles and further researched the emission characteristic under different load distribution.