An internal combustion engine comprises an intake tract in which a
throttle valve is disposed. The engine also comprises a camshaft which
acts on gas inlet valves associated with respective cylinders. A
phase-adjustment device is used to adjust a phase between the camshaft
and a crankshaft. A desired air mass flow in a combustion chamber of the
cylinder is determined depending on a charge requirement requested by the
driver. The desired air mass flow is adjusted by varying the phase
between the camshaft and the crankshaft if the desired air mass flow can
be adjusted by varying the phase while substantially maintaining an
actual pressure difference upstream and downstream of the throttle valve.
Otherwise, the desired air mass flow is adjusted by varying the opening
angle of the throttle valve.