Patent ID: 7481185

Claim:
A method of operating an internal combustion engine including an engine cylinder having a piston, comprising: providing a four-stroke engine cycle, Homogeneous Charge Compression Ignition engine operation for a first characteristic engine operating region having an upper boundary defined by a first power output threshold and a first engine speed threshold; providing a two-stroke engine cycle, Homogeneous Charge Compression Ignition engine operation for a second characteristic engine operating region having an upper boundary defined by a second power output threshold and a second engine speed threshold, wherein the second power output threshold is greater than the first power output threshold, and wherein the second engine speed threshold is greater than the first engine speed threshold; and providing a four-stroke engine cycle, boosted Spark Ignition engine operation for a third characteristic engine operating region having an upper boundary defined by a third power output threshold and a third engine speed threshold, wherein the third power output threshold is greater than the second power output threshold, and wherein the third engine speed threshold is greater than the second engine speed threshold; wherein the first, second and third characteristic engine operating regions are sequentially contiguous.