Patent ID: 8100099

Claim:
A method of operating an internal combustion engine, wherein the internal combustion engine comprises at least one cylinder having an inlet and an outlet, an intake valve at the inlet of the cylinder, and an exhaust valve at the outlet of the cylinder, the method comprising: opening the exhaust valve during an outlet event time dimensioned to provide a positive scavenging of the cylinder, and wherein the outlet event time is 180° KW+/−10° KW for an R4 engine; opening the inlet valve, such that both the exhaust valve and the inlet valve are open during a crossover phase having a length between 5° and 30° KW relative to a 1 mm valve stroke; and closing the exhaust valve before an outlet pressure at the outlet of the cylinder exceeds an inlet pressure at the inlet of the cylinder, wherein the opening of the intake valve and the exhaust valve and the closing of the exhaust valve is effected by a camshaft comprising at least a first cam and a second cam, each having defined cam profiles cooperating with said valves, wherein the first cam and the second cam have stroke contours that are interlaced against one another, wherein the first cam and the second cam do not lie within one another, wherein the second cam has a smaller stroke contour than the first cam, and wherein, when the internal combustion engine is operated in a low rpm range of less than 2500 1/min, the method further comprises: shortening the outlet event time; and lengthening the crossover phase, wherein both the shortening of the outlet event time and the lengthening of the crossover phase are achieved by switching from the first cam to the second cam.