EXHAUST GAS PURIFICATION DEVICE FOR INTERNAL COMBUSTION ENGINE

摘要

An exhaust gas purification device for an engine has a filter which is provided in an exhaust passage of the engine, collects particles in exhaust gas, and is subjected to Active Regeneration for burning and removing the collected particles by heating, and a diesel oxidation catalyst which is provided on the upstream side of the filter and increases the temperature of the filter. The exhaust gas purification device further has a control unit which effects combustion using the diesel oxidation catalyst to perform the Active Regeneration of the filter by injecting fuel at a timing when no contribution is made to combustion in a combustion chamber of the engine when the quantity of the particles collected in the filter reaches a predetermined quantity or more, or when the quantity of the particles collected in the filter is less than the predetermined quantity and an elapsed time from the last reconditioning of the filter reaches a predetermined time. The control unit includes a fuel mixing quantity calculation unit which calculates a mixing quantity of the fuel mixed into an engine oil at the time of the Active Regeneration of the filter, and a fuel evaporation quantity calculation unit which calculates an evaporation quantity of the fuel from the engine oil. Amixing ratio of the fuel in the engine oil is calculated from the mixing quantity of the fuel and the evaporation quantity of the fuel from the engine oil, and the predetermined time or an operation mode of the engine is adjusted such that the mixing ratio is not more than a prescribed control value.