Predicting Combustion Pressure of Automobile Engine based on Chaos Theory

Abstract

Recently, automobile manufacturers continue large effort for developing the low emission and fuelefficient vehicle, and various researches have been made. One of the most important researches is to develop the engine that can practically work in the ideal combustion condition with fuel as little as possible. However, the tolerance is narrow for normally driven with a small air fuel ratio. The combustion condition becomes unstable, when the air fuel ratio is below the tolerance. The unstable combustion condition makes a fluctuation of torque and an increase of NOx in exhaust gas. Conventional method for solving the problem stated above is to control the air fuel raito by sensing an unstable combustion condition. But the control method predicting the combustion condition is not proposed yet. Generally the predictive control has many advantages, but is required high prediction accuracy. It is considered that to predict the combustion condition of an automobile engine is quite difficult. By the way, the chaos is noticed as the theory that can treat the nonlinear dynamical system, and the research has energetically been advanced. For predicting the combustion condition of an automobile engine, we applied the chaos theory. That is : the peak pressure of succeeding combustion is forecasted, using only combustion pressure time series of cylinders inside at a constant load. In this paper, the purpose, method and result of our research are reported.