EXHAUST PURIFICATION DEVICE FOR INTERNAL COMBUSTION ENGINE

摘要

An exhaust purification device for an internal combustion engine, in which at least NOx, out of unpurified components contained in exhaust gas, is appropriately purged with consideration of characteristics of separation of NOx from an adsorption material. The exhaust purification device has a bypass path (18) bypassing a main exhaust path (12) of an internal combustion engine (10). The bypass path (18) is provided with a HC/NOx adsorption material (22) having a function of adsorbing HC and NOx. A second underfloor catalyst (30) is provided on the downstream side of the adsorption material (22). The exhaust purification device further has a purge path (26) branched from the bypass path (18) and connected to an air intake path, and also has an exhaust switchover valve (20) and a purge control valve (28) that function as flow path switchover means capable of switching the flow destination of exhaust gas between the main exhaust path (12) and the bypass path (18). To perform purge operation, intake purge operation is made first. Then, the intake purge operation is switched to exhaust purge operation at a time point after NOx purge is completed and when the temperature of the adsorption material is stabilized.