Patent ID: 6619032
Filing Date: 2003-09-16
Classification: F01N,F02D,Y02T

Abstract:
An engine exhaust purification device comprising:a catalyst provided in an engine exhaust passage, a first sensor which detects an exhaust characteristic flowing into the catalyst, a second sensor which detects an air-fuel ratio of an exhaust flowing out of the catalyst, and a microprocessor programmed to: compute an oxygen storage amount of the catalyst using the detected exhaust characteristic, compute a target air-fuel ratio of the engine based on the computed oxygen storage amount such that the oxygen storage amount of the catalyst is a predetermined target value, determine a deterioration of the catalyst based on an integrated value of the oxygen storage amount for a predetermined time, perform reset processing which initializes the oxygen storage amount to a maximum value when the air-fuel ratio of the exhaust from the catalyst detected via the second sensor exceeds a lean determining value, and initializes the oxygen storage amount to a minimum value when the air-fuel ratio of the exhaust from the catalyst detected via the second sensor exceeds a rich determining value, and determine that the catalyst has deteriorated based on the integrated value of the oxygen storage amount on each occasion reset processing is performed.