| From point of views of development of automotive electronics and electronic engineering, in order to reduce exaughst emission and meet rigid regulations of automobile exhausts, such as ULEV, control strategies of automotive engine are under strict requirements. For now, the strategy of control of SI engine is to employ 3-way catalytic converter with λ controller and electric-controlled fuel injection to meet these requirements. However, in order to minimize engine exhausts, the catalytic converter has to perform within its most efficient ranges for every single operating point of SI engine. In some paper, it says that in order to achieve the most efficient conversion, average air/fuel ratio should be controlled within the range of 14.7±0.147.In order to achieve highly precise control of AFR, highly precise measurement of both intake air and injected fuel have to be first achieved. To achieve those two goals, the following 3 technical problems have to be solved using available measurement and control parameters: 1.Respond delay of air measurement instrument. 2.Measurement error of intake air in intake manifold due to manifold filling and emptying process during transient operations. 3.Control error of fuel injection due to the different locations of fuel injection and air measurement.With respect to above problems, a Mean Value Engine Model(MVEM) is developed in this paper. This model, along with control strategy using information fusing, realizes precise control of flow mass of intake air. Applying this model on a LPG engine shows that the control system can reliably control operation of LPG engine and LPG engine's power, economy and exhaust performances are obviously improved. All indicate that this control model and the information fusing method work well.During development and application of this control system, the main tasks include:1 In accordance with gas injection instrument from OMVL, Italy, a manifold, sequence, multiply-point gas injection system using single LPG fuel is reconstrusted on JETTA gasoline fuel injection engine.2 A data acquisition system is designed in order to acquire data during transient operations. It consists of a high-performance PCL-818HG data acquisition card and its PCLD-8115 writing terminal board from Advantech Co., Ltd. Using hardware timer (in the PCL-818HG card) to interrupt, multiple thread and double buffer technologies are used in the work of programming. high-speed real-time data acquisition is realized. Thus intake air flow mass, intake manifold pressure and other high-speed data can be acquired and stored reliably. Meanwhile, in order to realize transient operations through adjusting throttle position on an ordinary dynamometer, a control system controlling step motor is designed, which can duplicate performed transient operations.3 A dynamic MVEM is developed for LPG engine concerning with AFR control. The engine is modeled as a simple pump and the manifold like a tank with input and output. The equations for balances of air masses of this system can be defined with the filling and emptying method. The air mass flow at the throttle can be described with the equation for compressible gases at an ideal nozzle. In order to precisely calibrate the control model, a time-delay model of AFR sensor is developed. The model is the basse of control arithmetic simulating and control strategies designing.4 With the data acquisition system developed, the signals of MAP,TPS and MAF are analyzed under stable and non-stable operations. The relation between MAP, TPS, MAF and crank angle is found out. By way of wavelet analysis, signals from MAP sensor are processed and analyzed. The MAP signals are measured in10oCA. All this paves the way for measurement of intake air masses on the base of state observor.5 In order to obtain better control precision, the control system is non-linear and discrete, that is the state equation is non-linear continuous and the observation equation is discrete. Instead of a Luenbergerr observer or a conventional Kalman Fi...
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