Patent ID: 7100365

Claim:
A combustion control system of an internal combustion engine employing an exhaust purifying device in an exhaust passage, comprising: sensors that detect operating conditions of the engine; a control unit being configured to be electronically connected to the sensors, for combustion control and exhaust emission control purposes; wherein the control unit comprises a processor programmed to perform the following, (a) estimating an operating condition of the exhaust purifying device; (b) determining, based on the operating condition of the exhaust purifying device, whether a predetermined condition, including at least one of a request for a rise in an exhaust temperature and a request for an engine operating mode at an excess air factor corresponding to a rich air-fuel mixture ratio, is satisfied; (c) executing, by way of fuel injection control when the predetermined condition is satisfied, a split retard combustion mode in which a main combustion needed to produce a main engine torque and at least one preliminary combustion occurring prior to the main combustion are both achieved, wherein the preliminary combustion takes place near top dead center on a compression stroke, and wherein the main combustion initiates after the preliminary combustion has been completed; (d) determining whether the exhaust purifying device is in a catalyst deactivated state or in a catalyst activated state; and (e) simultaneously executing an exhaust-emission reduction control that reduces hydrocarbons (HC) and carbon monoxide (CO) emissions exhausted from a combustion chamber of the engine, while keeping the excess air factor at a desired value, during the split retard combustion mode in the catalyst deactivated state.