| 摘要 |
<p>Provided is an exhaust gas purification system for an internal combustion engine, which can reduce emission deterioration due to blow-by of NOx in an internal combustion engine provided with an NSR catalyst. An exhaust gas purification system for an internal combustion engine (10) capable of a lean-burn operation is provided with an NSR catalyst (16) which is disposed in an exhaust gas passage (12) for the internal combustion engine (10), an SCR (18) which is disposed downstream from the NSR catalyst (16), an NOx sensor (26) which is disposed downstream from the SCR (18) and gives an output corresponding to the concentration of NH3, and a rich spike means which executes a rich spike. The rich spike means starts the rich spike at a predetermined timing during the lean-burn operation, and ends the rich spike at a timing when the NOx sensor (26) gives a predetermined output characteristic showing an increase in the concentration of NH3.</p> |
