Patent ID: 6990801

Claim:
A combustion control apparatus for an internal combustion engine, comprising: an exhaust purifier in an exhaust passage of the engine; a combustion controlling actuator for causing combustion in a combustion chamber of the engine; a controller for controlling the combustion controlling actuator; and the controller configured to perform the following: switching a combustion mode between a normal combustion mode and a split retard combustion mode, in accordance with an condition of the exhaust purifier; determining a first EGR rate for the normal combustion mode and a second EGR rate lower than the first EGR rate for the split retard combustion mode, in accordance with an operating point of the engine; performing the following in the normal combustion mode: producing normal combustion to generate an output torque of the engine; and recirculating exhaust gas to the combustion chamber at the first EGR rate; and performing the following in the split retard combustion mode: producing preliminary combustion at or near top dead center, to release a predetermined quantity of heat in the combustion chamber; starting main combustion at a timing later than a start timing of the normal combustion in the normal combustion mode, after an end of the preliminary combustion, to generate the output torque of the engine; and recirculating exhaust gas to the combustion chamber at the second EGR rate.