EXHAUST EMISSION CONTROL DEVICE FOR INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To raise the temperature of exhaust emission by post injection in an optimal condition when raising an exhaust temperature to regenerate a filter in an exhaust emission control device provided with a DPF. SOLUTION: This exhaust emission control device uses a common rail system to inject fuel for the post injection into a cylinder in an expansion stroke after main injection. A control unit ECU of the exhaust emission control device practically controls the fuel injection, and sets a target injection quantity Qp and a target fuel injection timingθp of the post injection on the basis of an engine speed and acceleration valve opening (step S3). The ECU performs the real fuel injection with a fuel injection quantity smaller than the target value Qp in the injection timing advanced than the target valueθp during the predetermined time from a starting point of the post injection (steps S5 and S6), and gradually brings the real injection quantity and the real injection timing near the target values Qp andθp with the lapse of time.