Research On Emission And Evaluation Method Of Heavy Duty Hybrid Electric Vehicle Based On PEMS

Due to the large differences between the actual vehicle operation and the emissions during laboratory type certification,actual road emission testing has become a hot spot in the field of emission testing.Various countries and regions have included motor vehicle road emission tests into the test regulations.There are relatively few studies on the road emissions of heavy-duty hybrid electric vehicles,and the corresponding on-board emission test methods and data evaluation methods are not yet complete.This article uses the vehicle-mounted emission test system to perform actual road emission tests on heavy-duty hybrid vehicles under different fuel types,different emission stages,and different control strategies.The relationship between speed,acceleration,and specific power of vehicles and emissions is analyzed.Emission evaluation methods calculate the test results and analyze the adaptability of different methods.Experimental results and analysis show:1.ChinaⅤphase of diesel-electric hybrid each pollutant emissions and fuel consumption than conventional diesel-powered cars,especially in the low speed driving conditions such as downtown,role in reducing pollutant emissions and fuel consumption is very significant.When driving in suburban conditions,hybrid electric vehicles have no advantages over conventional diesel vehicles in terms of NOx emissions and fuel consumption.ChinaⅥphase of gas-electric hybrid bus fuel consumption have obvious advantages over the conventional gas car,can save more than 20%of the fuel,but its emissions,especially NO_X emissions and no advantage.When gas-electric hybrid buses run at medium speed and medium load,their emissions and fuel consumption are higher than that of conventional gas buses,but the emissions and fuel consumption under low or high load are significantly lower than that of conventional gas buses.2.Idle mode diesel-electric hybrid relative to the star-stop mode at the expense of the fuel consumption reduced emissions,the difference is mainly caused by the change of the engine combustion chamber temperature and discharge temperature.Therefore,emissions can be reduced through measures such as the use of exhaust heating systems,the addition of post-treatment insulation materials,and changes to engine control strategies.3.The existing vehicle emission evaluation methods are not comprehensive in evaluating hybrid vehicle emissions.In the actual driving of hybrid electric vehicles,the engine operating point deviates from the NTE region,and due to the influence of start-stop control,it is difficult to generate NTE events,so the NTE method is not applicable to hybrid electric vehicles.In the calculation of modified CO₂ window method,the process of pure electric driving of hybrid vehicles is ignored,which weakens the advantage of low absolute pollutant emission of hybrid vehicles,and is also not applicable to hybrid vehicles.In the calculation of the mean power limit of the window by the power base window method,some Windows with low emission are excluded,and the pollutant calculation of hybrid vehicles will make the test results higher,so it is more reasonable to modify or remove the mean power limit of the window.