| To overcome the defaults of offset wearing, cylinder temperature varying and shock at varying cylinder of engine, the author raises a new idea about variable power displacement (VPD) engine and has done much studying work on the control technology and application of VPD. The varying cylinder models have been designed which pause cylinder power circulated, alternately, and regularly. With the theory of fuzzy identification and fuzzy control, the author has studied the judging method of car running state, the technologies of fuzzy identifying driver's intention and the fuzzy control strategies. Taking the Infineon XC164CM microprocessor as key component, samples of VPD controller have been designed and made. One of a sample was installed on Jetta car, and many tests have been done on road to detect its function.Main contents of this paper are as follows:(1)Theoretical problems of engine VPD model have been studied. The design rules and design methods of VPD model are given. The wear homogenization, operating flexibility and rotating stability are used to assess the VPD model. According to the arrangement of cylinders, VPD models of L4, L6, V6 and V8 engine have been designed respectively.(2)The method of thermodynamic simulation about engine output properties has been studied. Using the zero-dimension simulation model of thermodynamics and Adams/Engine module, the power output under stable rotating condition of engine has been simulated and calculated. Taking an example of Jetta car, the output torque MAP and power MAP are calculated with the simulation method. The MAPs change with engine rotating speed and throttle opening degree.(3)Using fuzzy reasoning and control theory, the fuzzy judging method for running states of motorcar have been studied. According to the dynamic characteristics, classified the complicated running states of motorcar into 7 kinds of independent conditions. After fuzzification of parameters from car sensors, fuzzy model and rules are created to identify running states of motorcar. The judging method for identifying the running state of motorcar is given.(4)Apply the fuzzy identification and control theory into identifying driver's intention. Classify the driver's intention into 5 numerical accelerating intentions. Fuzzificationing the relative throttle percentage and the change rate of throttle opening, fuzzy inference model and rules are created. Using Matlab/Fuzzy Logic workbox, simulation of identifying driver's intention is done to detecting correctness of the method. The simulating result indicates that the fuzzy model and inference rules can reflect driver's intention accurately.(5) The fuzzy control strategies have been designed for choosing VDP model. The car speed, gearshift, running state and driver's intention have been taken as basis for choosing VDP model. Fuzzy control rules and control strategies under different running condition, speed, gearshift and driver's intention have been designed.(6) The VPD controller samples has been designed and made using the VPD theory and the technologies of judging car running states, the recognizing driver's intention and control strategies. Which is centered-XC164CM microprocessor. The programming software is completed on the developing platform which was provided by the OEM of XC164CM.(7)The theory and technique are applied into the Jetta car. The indoor tests of engine and road tests of car with VPD controller sample were done. The engine test result validates the feasibility and validity of VPD. The road tests compare the fuel consumption of different power displacement. The test results show that a car applied VPD technology not only consumes less fuel obviously, but also reduces cylinder offset wear and cylinder temperature changing.The VPD theory and techniques of using fuzzy theory to judge car running state and to identify driver's intention are very useful. All of the techniques have theoretical significance and practical value in engineering.
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