The Establishment And Experimental Investigation Of Mean Value Engine Model Of Gasoline Engine

As 'Energy Saving & Emission Reducing' become the hotspot universally,the current development of Hybrid Electric Vehicle(HEV) introduced initially.Basing on 'the research and development of mass-production of super-capacitor based HEV ' which is national 863 key project,various methods of engine model building are analyzed and compared.The well developed model building method and concept of Mean Value Engine Model(MVEM) is adopted to build the model of 1.5L gasoline engine used in HEV.This model has significantly practical value and directive significance for the engine performance prediction and development of multi-energy management system used in HEV.To be the basis of the whole engine model,the traditional MVEM is built firstly and it contains three major parts:intake manifold model,fuel vaporization model and power output model.The important phenomena and parameters,such as,Filling & Emptying Effect within intake pipe,Wall-Wetting Effect caused by fuel film deposited on the inner wall of intake manifold and indicated heat efficiency are discussed and analyzed in detail.The traditional MVEM is constructed as a basic frame.Based on MVEM and 1^st law of thermodynamics as well as law of energy conservation,the thermal model of engine is built.This model can indicates the temperature of engine components,especially the engine coolant temperature.Based on the thermal model and analyzing the distribution and transfer of fuel in cylinder, the hydrocarbon(HC) emission model is proposed.The three-way catalyst model which includes temperature submodel,oxygen storage submodel and conversion efficiency submodel is also put forward.This model is able to predict the HC emission during cold-start process precisely.The above mentioned engine model is verify by dynamometer test and cold-start experiment,the results show that this model gives a good precision of various engine parameters.Under some typical conditions,the simulation error of intake air flow, intake air pressure,engine coolant temperature and torque output is less than 5%. Beside,the HC emission values and tendency during cold-start can also be simulated accurately.Finally,the mechanism of HC reduction by retarding spark advance is illustrated, the experiment results show that this method can effectively shorten 'Light-Off' time of three-way catalyst and reduce HC emission during cold-start.In addition,the transient fuel compensation strategy is presented.The influencing factors including engine coolant temperature,throttle position and its changing rate on Wall-Wetting Effect are all studied.The transient fuel film compensation experiment confirms that this fuel film compensation strategy has outstanding effectiveness and precision.