Control device of internal combustion engine, and internal combustion engine

A control apparatus for an internal combustion engine including a crank mechanism for converting a reciprocating motion of a piston into a rotational motion of a crank shaft, a cylinder for housing the piston, and an intake valve capable of opening and closing a port for intake of gas into the cylinder, the control apparatus comprising:

• a volumetric-efficiency calculation section that calculates, based on a cylinder-volume when the intake valve closes, a volumetric-efficiency indicating intake-efficiency in intake of gas into the cylinder;
• an intake-gas-amount calculation section that calculates with a previously determined formula, based on the calculated volumetric-efficiency, an intake gas amount to be taken into the cylinder;
• and
• a control section that controls the internal combustion engine based on the calculated intake gas amount, wherein the intake valve is configured to close at a timing that is selected from a plurality of timings that is previously determined and that is a switchable timing of the plurality of timings, and wherein the control apparatus further comprises a memory section that previously stores a cylinder-volume when the intake valve closes at each of the plurality of timings, wherein
• in a case where the timing is switched, the volumetric-efficiency calculation section calculates the volumetric-efficiency based on the previously stored cylinder-volume when the intake valve closes at the timing that has been switched.