Search Results

Electronic throttle control has been receiving increased attention lately as a technique for attaining highly accurate idling air control and improving emissions. To accomplish these goals, it is necessary to achieve greater robustness in control performance, and to compensate for the production variability of individual units and degradation of parts over time. Up to now, it has been difficult for PID control systems to recognize uncertain disturbances, and this has been an impediment to achieving balance between robustness and responsiveness. To attain robustness, an adaptive control system has been constructed which utilizes sliding mode control and includes an identifier to perform sequential calculations. This technology has realized previously unattainable levels of robustness, accuracy, and responsiveness in an electronic throttle control system.

The reduction of fuel consumption is of great importance to automobile manufacturers. As a prospective means to achieve fuel economy, lean burn is being investigated at various research organizations and automobile manufacturers and a number of studies on lean-burn technology have been reported to this date. This paper describes the development of a four-valve lean-burn engine; especially the improvement of the combustion, the development of an engine management system, and the achievement of vehicle test results. Major themes discussed in this paper are (1) the improvement of brake-specific fuel consumption under partial load conditions and the achievement of high output power by adopting an optimized swirl ratio and a variable-swirl system with a specially designed variable valve timing and lift mechanism, (2) the development of an air-fuel ratio control system, (3) the improvement of fuel economy as a vehicle and (4) an approach to satisfy the NOx emission standard.

In this research project, modeling of the dynamic air excess ratio (λ) behavior in the exhaust gas at the confluence point in the exhaust manifold was performed. By applying an observer which is one method described by modern control system theory, estimation of the λ for each cylinder was carried out using one λ sensor. The estimated value was used to perform λ feedback control for each cylinder, allowing compensation of deviation in air-fuel ratio between cylinders and individual control of fuel injection volume for each cylinder, dramatically enhancing λ controllability.

In a conventional fuel metering control system (speed density method) for an internal combustion engine, the fuel injection amount during transient operation is usually determined by using mapped data and various settings in a feedforward system predetermined through experimentation. However, this still does not necessarily represent the ideal level of compensation under a diverse range of environmental conditions. In order to satisfy various demanding requirements, such as reducing emissions, it is vital that the controllability of the air excess ratio(λ) be enhanced. The main technological obstacle that needs to be overcome is how best to determine accurately the required fuel amount from the engine in the feedforward system. To enable accurate prediction of the cylinder intake air volume, physical formulas of fluid dynamics were used to facilitate formulation of a model for the dynamic behavior of the intake air.