EXHAUST EMISSION CONTROL DEVICE FOR INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To provide an exhaust emission control device for an internal combustion engine capable of regenerating a filter by controlling an air-fuel ratio of the internal combustion engine while suppressing a NOx emission amount.SOLUTION: An exhaust emission control device for an internal combustion engine includes: a three-way catalyst disposed in an exhaust passage of the internal combustion engine; a filter arranged in the exhaust passage in the downstream side of the three-way catalyst; a NOx sensor disposed in the exhaust passage in the downstream side of the filter; and a control section for controlling an air-fuel ratio of the internal combustion engine to be in the vicinity of a theoretical air-fuel ratio, which executes regeneration control processing for continuously controlling the air-fuel ratio of the internal combustion engine to be an air-fuel ratio with oxygen more excessive than the theoretical air-fuel ratio during regeneration of the filter, and terminates the regeneration control processing when a detection value of concentration by the NOx sensor is equal to or more than a prescribed value.