| 摘要 |
<p>PURPOSE: To aim at the proper maintenance of nitrogen dioxide purification modulus by altering the reference temperature of a catalyzer for which a hydrocarbon supply means starts a supply of hydrocarbon, with a catalytic secular change signal given by a means detecting a secular change in the catalyzer. CONSTITUTION: With a hydrocarbon(HC) supply routine started, engine load and engine speed are read, and also an HC supply is read out of an HC map. At this time, a catalytic secular change detecting routine selecting this HC map is started, an inlet exhaust temperature and a catalyzer temperature of a catalytic unit 4, where an exhaust temperature sensor 8 and a catalytic tejmperature sensor 9 output, are read as well. In addition, a temperature difference between them is calculated, whereby a fact that whether this temperature difference is smaller than the reference temperature difference or not, namely, whether a catalyst is subjected to its secular change or not is judged. In an affirmative result, the HC map to be used is specified to a secular change map 1. Then, in an executive process of the catalytic secular change detecting routine again, if such a fact that the catalyzer is subjected to the secular change is rejudged, the HC map to be used is controlled to be altered to a secular change map 2.</p> |
