| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To reduce the deterioration of fuel economy when NOx storage reduction catalyst is refreshed in case that the catalyst is arranged in an exhaust passage 15, in a diesel engine 1 carrying out low-temperature combustion which is mainly premixed combustion on a low load side. <P>SOLUTION: When the NOx storage of the catalyst becomes not less than set amount, a target value of an air excessive rateλin a specified area on a high load side in a premixed combustion area P, namely in a low/middle load area which is frequently used in an automobile and the like, is corrected to beλ=1. Since the target value of the air excessive rateλin the specified area is set to be low, even if the target value is corrected to beλ=1, changes of engine output or great deterioration of fuel economy does not occur, and the increase of soot can be prevented. Therefore, the refreshing of the catalyst is promoted during the operation of the engine 1, thereby stably ensuring purifying performance. <P>COPYRIGHT: (C)2009,JPO&INPIT</p> |
