Research And Design On Strategy Of Controlling Air-fuel Ratio Of Engine

Automotive electronic system is the soul of the car, the engine electronic control systems is the most important part of automotive electronic system. Modern gasoline engine completely abandoned the carburetor mechanical structure, and all use of electronic control technology, which to make a qualitative leap in engine performance, engine power, economy and emissions have been improved significantly, and now the level of the engine electronic control technology directly determines the quality of the whole engine.Engine electronic control system has two of the most important parts: fuel injection control system and the ignition control system. The main task of fuel injection control system is to determine the flow rate of the injector fuel injection engine according to operating conditions in which the current, so that the air entering the engine cylinder, the fuel to achieve the best air-fuel ratio, waiting for lighting the engine. The main task of an ignition control system is decided based on the current engine operating conditions on the cylinder fuel ignition timing control to ensure that the power output of the engine and to prevent the occurrence of knocking phenomenon. Both control systems, fuel injection control system air-fuel ratio control is particularly important because that the air-fuel ratio directly determines the power, fuel economy, emissions of pollutants of the engine, so the engine air-fuel ratio control strategy research has a very important significance.Based on the analysis of insufficient of the current gasoline engine fuel injection system of hollow fuel ratio control method, has deeply studied the air-fuel ratio control method based on intelligent control theory. Firstly, the principle and significance of the theoretical air-fuel ratio has been analyzed in this thesis, and then on the factors affecting the accuracy of the engine control has been studied, and control strategies for understanding existing engine air-fuel ratio, as well as its shortcomings have been analyzed. In-depth understanding of the engine structure and control theory, this article based on the average value of the engine model, the establishment of a gasoline engine simulation model based on a mathematical model and MATLAB / Simulink, and by comparison with the actual data, the simulation model has better practicability and reliability. In order to improve the accuracy of the engine air-fuel ratio control, on the basis of a simulation model based on the design of the control of the air-fuel ratio control theory of intelligent strategy, has designed intelligent controller, intelligent building air-fuel ratio control system model, simulation results demonstrate the intelligent control strategies for air-fuel ratio advantage of precise control.The ultimate goal of graduation project is to design a highly versatile engine electronic control unit(ECU), and the air-fuel ratio to achieve intelligent control strategy is applied to the actual electronic control unit. In this thesis, TI's high-performance controller TMS320F28335 control core, has designed for the entire engine electronic control unit hardware circuit and a preliminary design of software development.