| With the advantages of high thermal efficiency, good power and durability performance, diesel engines are widely used in many fields. But the disadvantages such as big noise and high NOx as well as PM emissions greatly restrict diesel engine's futher development and application. Therefore, how to control the harmful emissions of diesel engine efficiently to meet the increasingly strict emission regulations and insure the good fuel economy is the kernel issue in diesel engine research field. Since the high pressure common-rail electronic-controlled fuel injection system for diesel engine has the capability to meet the emission regulation of national IV emission and later stage regulations, it is important to develop such kind of fuel injection system for vehicle diesel engine. The development of the high pressure common-rail electronic-controlled fuel injection system for vehicle diesel engine can not only improve the competence capability of domestic automobile industrial on world market, but also make great contribution on the harmful emission control in china. Based on the investigation on the relating theories, a simplified phase-divided spray mixing model and the quasi-dimensional model for diesel engine working process based on the phase-divided spray mixing model were developed which has high real-time operating performance in this paper. Moreover, the power, fuel economy and emissions performance of diesel engine were optimized by combining the quasi-dimensional model for diesel engine working process, the simulation model of high pressure common-rail electronic-controlled fuel injection system of diesel engine and the practicality of common-rail fuel injection system in this research which was based on the Hardware-In-the-Loop technology and orthogonal experimental design method. The following work has been carried out:(1) In order to investigate the simulation object's working characteristic, the zero-dimensional model for diesel engine working process was proposed based on the filling and emptying method. The software MATLAB/Simulink was utilized to develop the zero-dimensional model on the basis of analysis on the diesel engine working process of naturally aspired single cylinder diesel engine in detail. The parameters and limited condition of the simulation model were selected. The relative error between experimental data and simulation results less than 3.3% which indicates that the model has capability to predict the power and fuel economy performance of the diesel engine with good precision. At the same time, the influence of back flow at intake valve on the mass state in intake pipe can be neglected for the sake of simplification of the simulation model and improvement of the real-time operating performance of the simulation system. The modeling and simulation of the zero-dimensional model for diesel engine working process lays a foundation to the simulation study on the quasi-dimensional simulation model for diesel engine working process.(2) The phase-divided spray mixing model was proposed on the basis of analysis on the diesel engine combustion process and comparing with the representative existed spray mixing model and relating experiments for the sake of developing a simulation model for diesel engine working process being fit for the Hardware-In-the-Loop simulation system. Then, the simplified quasi-dimensional model for diesel engine working process was developed which was based on the new phase-divided spray mixing model. The simulation results show that the calculated process of mixing process between fuel spray and fresh air can be simplified by the use of phase-divided spray mixing model. The relative error between experimental data and simulation results less than 12.3% which proves that the power, fuel economy and emissions performance of diesel engine can be precisely predicted by the use of the quasi-dimensional model based on the phase-divided spray mixing model for diesel engine working process. In addition, the prediction precision is enhanced (the relative error between experimental data and simulation results less than 5.9%) and the real-time operating performance of the simulation system can be improved by the utilization of the calculating method which supposes that there is no fresh air entraining into combustion zone after the fuel in this zone is burnt out. Furthermore, the important parameters such as the value of nozzle flow coefficient in the simulation model must be precisely selected to ensure the prediction precision of the model. The comparisons of the prediction of in-cylinder pressure, heat release rate and performance parameters of diesel engine between the quasi-dimensional and zero-dimensional model indicate that the former one has better prediction precision and even can predict the NOx, PM emissions.(3) In oreder to study the fuel injection property of high pressure common-rail electronic-controlled fuel injection system for diesel engine, the mathematic model of high pressure common-rail electronic-controlled fuel injection system for diesel engine was proposed according to some simplification of the fuel injection system on the basis of some reasonable hypothesis and analysis on its composition and working process in detail. The simulation model of high pressure common-rail electronic-controlled fuel injection system for diesel engine was composed of high pressure pump submodel, common-rail pipe submodel and injector submodel which were developed according to their working processes individually. The simulation results show that the fuel injection characteristic of the high pressure common-rail electronic-controlled fuel injection system can be accurately simulated, and the movement process of the electromagnetic valve's drive-voltage, electromagnetic valve's drive-current, electromagnetic force and electromagnetic lift can be understood with the aid of the simulation model. At the same time, with the increase of the common-rail pressure, the fuel injection quantity is enlarged. Moreover, the simulation research of the fuel injection rate with pilot injection indicates that the delay of the electromagnetic valve's electromagnetic effects and the mechanism parts'movement must be considered during the control process of injector electromagnetic valve in order to avoid the injector needle-valve is lifted when it is still in the process of dropping to the valve seat.(4) For the sake of studing the influence of common-rail fuel injection system parameters to the performance of diesel engine and finding out the combined scheme of the common-rail fuel injection system parameters to optimize the the performance of diesel engine, the common-rail fuel injection system for diesel engine in Hardware-In-the-Loop simulation system was developed by the combination of the quasi-dimensional model for diesel engine working process, the simulation model of high pressure common-rail electronic-controlled fuel injection system of diesel engine and the practicality of common-rail fuel injection system. The influence of common-rail fuel injection system parameters on the power, fuel economy and emissions performance of diesel engine was simulated. At the same time, the principle of orthogonal experimental design was applied to the optimization simulation of the diesel engine performance by the utilization of the orthogonal table in order to optimize the power, fuel economy and emissions performance of diesel engine. The simulation results shows that the order of the influence degree of fuel injection parameters on the integrated diesel engine performance for the high pressure common-rail electronic-controlled fuel injection system with single injection rate is the fuel injection pressure, the nozzle number and diameter and the fuel injection pre-angle, and the order of the influence degree of fuel injection parameters on the integrated diesel engine performance for the high pressure common-rail electronic-controlled fuel injection system with pilot injection rate is the fuel injection quantity of pilot injection, the start angle of main injection, and interval angle between pilot injection and main injection on the condition that the the fuel injection pressure and the nozzle number and diameter are optimized selected. Besides, with the application of the orthogonal experimental design table and a few representative simulation schemes, it is possible to find out the inherent law between the parameters of the common-rail fuel injection system, and then optimize the integrated performance of diesel engine.
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