Patent ID: 8776762

Claim:
A method of controlling an engine comprising: determining a first engine speed; determining a first engine temperature; determining a first plurality of combustion mode (CM) threshold curves based on the first engine temperature, wherein each of the first plurality of CM threshold curves is a respective load line having a respective engine load versus engine speed relationship; determining a first engine load; based on the first engine speed, comparing the first engine load to each of the first plurality of CM thresholds; based on the comparisons of the first engine load to each of the first plurality of CM threshold curves, changing a combustion mode of the engine from a first homogeneous charge compression (HCCI) mode to a second HCCI mode; determining a second engine temperature; determining a second plurality of CM threshold curves based on the second engine temperature, wherein each of the second plurality of CM threshold curves is a respective load line having a respective engine load versus engine speed relationship; based on the first engine speed, comparing the first engine load to each of the second plurality of CM threshold curves; and based on the comparisons of the first engine load to each of the second plurality of CM threshold curves, changing the combustion mode of the engine from the second HCCI mode to the first HCCI mode or to a third HCCI mode.