EXHAUST EMISSION CONTROL DEVICE FOR ENGINE

摘要

PROBLEM TO BE SOLVED: To enhance durability of a catalyst, by preventing generation of a heat shock to a catalytic carrier. SOLUTION: This exhaust emission control device has an engine provided with: a means 11 estimating a sticking amount of an emission control capacity decreasing substance to a catalyst 7 provided in an exhaust passage of the engine; a temperature increasing means 11 for increasing a catalytic temperature to a target temperature when the timing is generated the emission control capacity decreasing substance adhering to the catalyst must be released to be based on this estimated sticking amount; and an air/fuel ratio control means 11 maintaining exhaust air/fuel ratio of the catalyst in an air/fuel ratio condition slightly richer than theoretical air/fuel ratio similarly when the emission control capacity decreasing substance adhering to the catalyst must be released. The device also consists of the temperature increasing means 11 of a first step delaying the ignition timing by an ignition device 6, and the temperature increasing means 11 of a second step continuing to fuel supply in a compression stroke to execute fuel supply in an expansion stroke by a fuel supplier 5 in a condition delaying the ignition timing thereafter.