Patent ID: 6591822
Filing Date: 2003-07-15
Classification: F02D,G05B

Abstract:
An air-fuel ratio controller for an internal combustion engine having a fuel injection valve for injecting fuel, air-fuel ratio detecting means for detecting an air-fuel ratio of exhaust gas, and controlling the air-fuel ratio of the exhaust gas to be close to a target air-fuel ratio based on state feedback by using a control model which simulates a control object ranging from the fuel injection valve down to the air-fuel ratio detecting means, said air-fuel ratio controller comprising:a control parameter calculation means for calculating control parameters based on coefficients of a characteristic polynomial of said control model and model parameters; and an air-fuel ratio correction factor calculation means for calculating an air-fuel ratio correction factor based on the control parameters, said air fuel ratio correction factor being used for feedback-based correction of fuel injection amount, wherein said control parameter calculation means calculates the coefficients of the characteristic polynomial based on a pole arrangement scheme which makes roots, which are equal in number to a dead time of the control model or equal in number to nâˆ’1 or nâˆ’2 (where n is the degree of the characteristic polynomial), to be zero.