Study On The Matching Between High Speed Diesel Engine And SUV’s Powertrain System

Nowdays，energy shortage and environmental degradation is one of the most intractableproblems in the world，all walks of life are trying to explore and seek ways to alleviate it.Forthe vast suomotive industry，this mainly reflected in the continuous advancement of energyand emissions regulations by every governments.These regulations become an invisiblebaton,urging automotive industry to place the target of energy-saving and emission reductionin the most prominent position. At present,quite a few technologies are researching aroundenergy-saving and emission reduction involving all aspects of automotive,and vehicle’spowertrain system matching is the one.Automotive powertrain system including power system and transmission system，powertrain system matching means to optimize the engine performance and its matching withtransmission system based on characteristics of vehicle model,and finally achieve the purposeof improving vehicle’s performance.The main content of this paper is the matching of dieselengine and SUV’s transmission system.Guided by the basic theories of vehicle，taking intoaccount the characteristics of SUV’s vehicle model and combined with the group’s project of2.0TCI high pressure common rail diesel engine combustion system development andcalibration，this paper determined the goals and methods of matching，and has carried on therelated experimental or simulative research， and ultimately improved entire vehicleperformance.Firstly，the article improved the selected engine’s performance through relevant enginebench test，including the external characteristic and the universal characteristic of theengine.Diesel engine performance depends on the combustion process in cylinder，while in certain operating conditions，the main factor that influence diesel engine combustion processis the matching of inner flow characteristics and the spray characteristics.Therefore，the papercoordinated the parameters of the combustion system by comparative tests，such as differentshapes of combustion chamber、different fuel injectors、different thicknesses of injector shim、different turbochargers and so on，this made the spray characteristics match well with theinner flow characteristics，and improved engine performance synthetically.To further improvethe external characteristics of the engine，the original ordinary turbocharger was replaced byVNT，thus taking into account the engine’s high and low speed torque characteristics，thevehicle’s acceleration ability had improved.To further improve the universal characteristics ofthe engine，effective EGR was implemented，thus achieving coordinated control of EGR andVNT，thereby significantly reducing NOXemissions.On this basis，building the vehicle simulation model with the aid of GT-DRIVE software，the paper selected a SUV’s chassis as reference to test the vehicle’s performance whilematching with improved engine.The simulation results showed that the vehicle’s powerperformance and emission performance have improved while the economy performance hasdeteriorated as a result of improving the engine performance.So，this paper then studied howchassis transmission ratio parameters affect each vehicle performance，and optimized theseparameters using the DOE optimization module in the GT-DRIVE，selected the existingchassis transmission ratio on the market that is closest to the DOE result as the optimizedchassis，thus the fuel economy performance has improved as soon as possible under thepremise of guaranteed power ability and taking into certain emissions performance account atthe same time，and ultimately achieved the purpose of improving entire vehicle performance.