EXHAUST PURIFICATION DEVICE FOR INTERNAL COMBUSTION ENGINE

摘要

In the disclosed internal combustion engine, a hydrocarbon supply valve (15) and an exhaust purification catalyst (13) are disposed within an engine exhaust passage. Platinum (Pt) (51) is supported on the exhaust purification catalyst (13), and an alkaline layer (53) is formed on the exhaust purification catalyst (53). The concentration of hydrocarbons flowing to the exhaust purification catalyst (13) is caused to oscillate at an amplitude that is within a predetermined range and at a period that is within a predetermined range, and as a result, NOx contained within exhaust gas is reduced at the exhaust purification catalyst (13). A degree-of-clogging detection means is provided that detects the degree of clogging of the nozzle opening of the hydrocarbon supply valve (15), and the rate of NOx scrubbing is estimated from the detected degree of clogging of the nozzle opening of the hydrocarbon supply valve (15).