Control system for compression-ignition engine

A system for controlling an internal combustion engine whose operation is switchable between a compression-ignition operation in which an air-fuel mixture supplied to a combustion chamber auto-ignites to burn owing to compression and a spark-ignition operation in which the air-fuel mixture is ignited to burn by a spark of a spark plug installed in the combustion chamber, comprising:

• a permissible condition determiner that determines whether a predetermined permissible condition to permit switching from the spark-ignition operation to the compression-ignition operation is satisfied at least in part via calculating upper and lower limits of required torque of the engine depending on whether or not combustion-ignition is possible;
• and
• a switching permitter that permits switching from the spark-ignition operation to the compression-ignition operation when the predetermined permissible condition is satisfied, and
• wherein the permissible condition determiner determines whether a catalytic converter installed in an exhaust system of the engine is in activated condition, and determines that the predetermined permissible condition is satisfied when the catalytic converter is in the activated condition, and
• wherein the permissible condition determiner discriminates whether a catalyst warm-up operation has been completed, obtains a temperature of the catalytic converter and determines that the catalytic converter is in the activated condition when the catalyst warm-up operation has been completed and when the temperature of the catalytic converter is equal to or greater than a predetermined value for a predetermined period of time.