Transient Air Fuel Ratio Control Strategy Considering Transport Time Delay For Gasoline Engine

In order to alleviate the automobile emission pollution to the environment, reduce fuel consumption, the issues of the accurate control of the air-fuel ratio for the spark ignition engine turns out to be a hot spot that the scholars researching. As the complex physical structure, the operating characteristics and the existence of the time delay of the pot injection engine, the precise control of the air-fuel ratio under transient conditions is difficult to achieve. The object of this paper is to regulate the air fuel ratio for the gasoline port injection spark ignition engine at the stoichiometric value in the transient operation.The main content is shown as follows:First, by analyzing the working principle of the port injection spark ignition engine and the dynamic of the air path, fuel path and the air fuel ratio measurement, the adaptive fuel injection controller is designed with considering the effect of the time varying delay in the system caused by the location of the measuring sensors, and the parameter uncertainties due to the sensor aging, the change of the intake air mass into the cylinder,and the wall wetting compensation to the precise control of the air fuel ratio.Second, through the further analysis of the dynamic characteristics of the air-fuel ratio for the gasoline engine, a modified active disturbance rejection fueling controller is designed to improve the accuracy of the air fuel ratio, which not only takes the time varying delay and the parameter uncertainties caused by the change of the intake air mass and the sensor aging into consideration, but also pays attention to the influence on the air fuel ratio as the change of the engine speed and the intake manifold pressure, the disturbance of the load torque and the varied parameters in the evaporation of the fuel film.An extended state observer is constructed and the air fuel ratio in the transient operation of the engine can be improved by the compensation of the total disturbance combining with the information of the former variations.Finally, the proposed two air fuel ratio controllers are both validated on the engine simulation model which is developed by the Society of Instrument and Control Engineers of Japan and the Toyota research department. The simulation results of the the proposed algorithms and the tradition control method under different engine operations arepresented and by comparison the performance of the controller are analyzed.