| 摘要 |
There are provided a control system and method and an engine control unit for an internal combustion engine, which are capable of properly determining an amount of fuel to be injected during a two-stage fuel injection combustion mode and a duration period of this mode such that stable combustion and smooth transition between combustion modes are ensured, thereby attaining excellent drivability and fuel economy. The combustion mode of the engine is switched between a homogeneous combustion mode in which fuel injection into each cylinder is performed during an intake stroke, a stratified combustion mode in which the fuel injection into the cylinder is performed during a compression stroke, and the two-stage fuel injection combustion mode in which the fuel injection into the cylinder is performed once during the intake stroke and once during the compression stroke during transition between the homogeneous combustion mode and the stratified combustion mode. The control system includes an ECU and a crank angle sensor. The ECU calculates a demanded torque PME demanded of the engine, and determines which of the homogeneous combustion mode, the stratified combustion mode, and the two-stage fuel injection combustion mode should be selected as the combustion mode of the engine, based on the demanded torque PME. The ECU determines an injection time period ToutD during the compression stroke in the two-stage fuel injection combustion mode based on the engine rotational speed.
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