Control apparatus of internal combustion engine

A control apparatus for an internal combustion engine, comprising:

• ignition means for igniting a gas mixture within a combustion chamber of the engine at an ignition timing corresponding to an operation state of the engine;
• full-combustion-correspondence-period estimation means for estimating a full combustion correspondence period, which is a period from the ignition timing to a combustion completion time at which combustion of the gas mixture within the combustion chamber ends;
• and
• burnt-gas-quantity control means for controlling a quantity of a burnt gas contained in the gas mixture such that the estimated full combustion correspondence period coincides with a target full combustion correspondence period, wherein
• the control apparatus further comprises cylinder pressure detection means for detecting a cylinder pressure, which is a pressure within the combustion chamber;
• and
• the full-combustion-correspondence-period estimation means is configured to estimate, on the basis of the detected cylinder pressure, an indicated heat quantity ratio corresponding to a ratio Qsum/Qtotal, which is a ratio of, a cumulative quantity Qsum of heat which is a portion of heat generated by fuel bunt within the combustion chamber until a predetermined timing and which was converted to work for a piston, to the total quantity Qtotal of heat which is a portion of heat generated by all fuel bunt within the combustion chamber and which was converted to work for the piston;
• obtain the maximum value of a change amount of the indicated heat quantity ratio Qsum/Qtotal in a predetermined crank angle extent;
• and estimate the combustion completion time on the basis of the maximum value.