| 摘要 |
PROBLEM TO BE SOLVED: To inhibit injection of a different type of a reducing agent from a reducing agent to be injected, when a reducing agent is injected from one injection valve that can supply a plurality of types of reducing agents.SOLUTION: An exhaust emission control device for an internal combustion engine includes: a tank for storing a reducing agent; an injection valve; a reducing agent passage for connecting the tank with the injection valve; a hydrolysis catalyst that is provided in the reducing agent passage to hydrolyze the reducing agent; a heating device for heating the hydrolysis catalyst to a hydrolysis temperature at which the reducing agent is hydrolyzed or higher; a pump for discharging the reducing agent; and a control device for controlling the pump so that the reducing agent present closer to the injection valve side than the hydrolysis catalyst is made to flow toward the hydrolysis catalyst side, before injection of the reducing agent in the state where the temperature of the hydrolysis catalyst is the hydrolysis temperature or higher is started after completion of the injection of the reducing agent in the state the temperature of the hydrolysis catalyst is lower than the hydrolysis temperature, in the case where the reducing agent is injected in the state where the temperature of the hydrolysis catalyst is lower than the hydrolysis temperature and then, the reducing agent is injected in the state where the temperature of the hydrolysis catalyst is the hydrolysis temperature or higher.SELECTED DRAWING: Figure 5 |
