Patent ID: 6269634
Filing Date: 2001-08-07
Classification: F01N,F02D,F02M,Y02T

Abstract:
An engine control device for controlling an engine provided with a fuel injection valve for supplying the engine with fuel, an EGR regulator for recirculating part of exhaust gas to an intake air line, an NOx-absorbing material arranged in an exhaust passage for discharging the exhaust gas from a combustion chamber for absorbing NOx in an oxygen-rich atmosphere, and releasing NOx and absorbing sulfur content when the oxygen concentration drops, and an air-fuel ratio controller for controlling an air-fuel ratio, the engine control device comprising;a NOx-absorbing state judging unit for judging whether the amount of NOx absorbed in the NOx-absorbing material has reached a predetermined quantity;a NOx releasing controller for switching the air-fuel ratio from lean to rich over a first period of time to release the absorbed NOx from the NOx-absorbing material;an absorbed sulfur state judging unit for judging whether the amount of sulfur absorbed by the NOx-absorbing material has reached a predetermined quantity; anda desulfuirization controller for causing the EGR regulator to decrease the EGR ratio over a second period of time that is longer than the first period of time to release the absorbed sulfur from the NOx-absorbing material when the amount of sulfur absorbed in the NOx-absorbing material is judged by the absorbed sulfur state judging unit to have reached a predetermined quantity.