| 摘要 |
<p>An electronic control unit (50) estimates the amount of the exhaust purification reaction on a NOx storage reduction catalyst supported on a PM filter (42), by comparing the states of exhaust gas before and after passage through the PM filter (42) based on the upstream-side exhaust gas temperature detected by an upstream-side exhaust temperature sensor (55) and the downstream-side exhaust gas temperature detected by a downstream-side exhaust temperature sensor (56). The unit (50) determines the degradation of the NOx storage reduction catalyst based on a relation between the catalyst bed temperature and the estimated amount of the exhaust purification reaction on the NOx storage reduction catalyst when the catalyst bed temperature is in a temperature range in which the amount of the reaction increases as the catalyst bed temperature rises and which is below an activation temperature at which the activation of the NOx storage reduction catalyst is completed.</p> |
