| 摘要 |
PROBLEM TO BE SOLVED: To prevent a reducing agent from being adhered to a cylinder inner wall surface in an exhaust emission control device provided with NOx catalyst for purifying NOx in exhaust gas by supply of the reducing agent by supplying the reducing agent into the cylinder when the cylinder internal temperature is higher than a predetermined temperature. SOLUTION: The internal temperature of each cylinder #1-#4 is estimated from the output of a water temperature sensor 28, and when an exhaust circulating valve 16 is opened, and the internal temperature of the cylinder #3 is higher than a set temperature, exhaust gas purifying HC is supplied only into the cylinder #3 in the expanding stroke or exhausting stroke of the cylinder #3 separately from fuel HC supplied into the cylinder #3 in the compressing stroke of the cylinder #3. The set temperature is a temperature sufficient for the purifying HC to form a gas before it is adhered to the cylinder inner wall surface or to be evaporated immediately after adhered to the cylinder inner wall surface. Thus, the purifying HC is never adhered to the cylinder inner surface, or it can be immediately evaporated, even if adhered, and discharged together with exhaust gas. |
