| 摘要 |
<P>PROBLEM TO BE SOLVED: To accurately estimate the temperature of an NOx catalyst. <P>SOLUTION: A sulfur concentration sensor 26 detecting the sulfur concentration in exhaust gas is arranged on the downstream side of the NOx catalyst 23. In engine operation, the temperature of the NOx catalyst 23 is estimated by taking into consideration giving-receiving of heat between the exhaust gas and the NOx catalyst 23, reaction heat in the NOx catalyst 23 and catalyst heat capacity. The sulfur concentration in the exhaust gas flowing out of the NOx catalyst 23 or a sulfur elimination speed (an elimination quantity of a sulfur compound per unit time) from the NOx catalyst 23, is estimated based on an engine operation state or an integral travel distance or an integral consumption fuel quantity after performing sulfur poisoning recovery control of the last time. The estimated catalyst temperature of the NOx catalyst 23 is corrected in response to its comparing result by comparing the detected sulfur concentration of the sulfur concentration sensor 26 or the detected sulfur elimination speed calculated from this detected sulfur concentration with the estimated sulfur concentration or the estimated sulfur elimination speed. <P>COPYRIGHT: (C)2009,JPO&INPIT |
