Predicting combustion pressure of automobile engine employing chaos theory

Automobile manufacturers continue to put a large effort into developing low emission and fuel-efficient vehicles. One of the most important researches is to develop an engine that can work in the ideal combustion condition using fuel as little as possible. The air fuel ratio is reduced in order to realize high mileage. However, the exhaust gas condition may deteriorate or the engine stops, since the combustion condition becomes unstable. Therefore, high-precision predictive control of ignition timing and air fuel ratio are important in order to retain the engine performance. The preparation of the combustion model of the engine is indispensable for predictive control. But, because the combustion is nonlinear and complex, a practical combustion model is not yet developed. Chaos has been noticed as a theory that can treat nonlinear dynamical systems, and the research has energetically been advanced. For predicting the combustion condition of the automobile engine, we applied chaos theory. That is: the peak pressure of succeeding combustion is forecast, using only the combustion pressure time series of cylinders inside. In the paper, the purpose and results of research are reported.