Abstract: Based on results of a knock control for adjusting ignition timing in accordance with the occurrence of knocking, an electronic control unit computes deposit required ignition timing akgrg, which is ignition timing determined by taking adhesion of deposits in an internal combustion engine into consideration. Based on the deposit required ignition timing akgrg, the electronic control unit reduces a vvt allowable variable range of a target VVT advancement amount, which is a control target value of a variable valve timing mechanism. The electronic control unit corrects a required ignition timing based on the actual VVT advancement amount vt, which is chanted according to the reduction of the allowable variable range of the target VVT advancement amount. As a result, problems resulting from the adhesion of deposits are effectively avoided.

Abstract: An upper limit guard is set for a valve overlap amount according to a KCS learning value used to retard-correct an ignition timing in order to suppress knock, and an engine load. As a result, it is possible to make the upper limit guard value a value able to restrict the valve overlap amount to a value equal to, or less than, a value at which an internal EGR amount does not become excessive during a retard-correction of the ignition timing. By applying the upper limit guard to the valve overlap amount using the upper limit guard value, it is possible to suppress the valve overlap amount from increasing from the optimum value following a retard-correction of the ignition timing, as well as suppress the value of overlap amount from being reduced when it is not deviating from the optimum value and is below the upper limit guard value.

Abstract: An upper limit guard is set for a valve overlap amount according to a KCS learning value used to retard-correct an ignition timing in order to suppress knock, and an engine load. As a result, it is possible to make the upper limit guard value a value able to restrict the valve overlap amount to a value equal to, or less than, a value at which an internal EGR amount does not become exvessive during a retard-correction of the ignition timing. By applying the upper limit guard to the valve overlap amount using the upper limit guard value, it is possible to suppress the valve overlap amount from increasing from the optimum value following a retard-correction of the ignition timing, as well as suppress the value of overlap amount from being reduced when it is not deviating from the optimum value and is below the upper limit guard value.

Abstract: A combustion control apparatus for an internal combustion engine that switches combustion modes at the proper timing. At the time of switching from a stratified-charge combustion mode to a homogeneous-charge combustion mode, the angle of an EGR valve is changed to the angle needed for the homogeneous-charge combustion mode first. When a predetermined delay time elapses after a request for switching the combustion mode has been made, substantial mode switching is carried out. The delay time is set based on engine speed and engine load.

Abstract: A fuel vapor treating mechanism includes a canister for adsorbing fuel vapor produced in a fuel feed system. The treating mechanism purges the fuel vapor adsorbed by the canister, along with air, to an intake system of the engine. An ECU computes a value representing the flow rate of the purged gas as a value that represents the capability of the treating apparatus. The ECU sets a decision value in accordance with the amount of the fuel vapor produced in the fuel feed system. The decision value represents a required capability of the treating mechanism. When the value representing the capability is less than the decision value, the ECU prohibits stratified charge combustion and causes the engine to perform homogeneous charge combustion. Therefore, as many opportunities as possible are provided to perform stratified charge combustion, which improves fuel efficiency.

Abstract: A combustion control apparatus for an internal combustion engine that switches combustion modes at the proper timing. At the time of switching from a stratified-charge combustion mode to a homogeneous-charge combustion mode, the angle of an EGR valve is changed to the angle needed for the homogeneous-charge combustion mode first. When a predetermined delay time elapses after a request for switching the combustion mode has been made, substantial mode switching is carried out. The delay time is set based on engine speed and engine load.