Internal combustion engine having variable compression ratio selection as a function of projected engine speed

摘要

A method for operating an internal combustion engine. The method includes: providing a functional relationship between time rate of change in engine speed, and compression ratio switching engine speed limit; determining time rate of change in engine speed; determining from the determined rate of change of engine speed and the function whether the engine speed exceeds the compression ratio switching engine speed; and commanding the engine to operate at a relatively low compression ratio if the determined time of change in engine speed exceeds the compression ratio switching engine speed limit and commanding the engine to operate at a relatively high compression ratio if the determined time of change in engine speed is less than the compression ratio switching engine speed limit.