Auto-ignition combustion management in internal combustion engine

摘要

An internal combustion engine is operated on auto-ignition combustion of fuel with low cetane number like gasoline. The engine has at least one cylinder and a reciprocating piston in the cylinder to define a combustion chamber. Combustion event in the cylinder is expressed in terms of two variables. They are main combustion timing (theta50) and a main combustion period (theta20-50). The main combustion timing (theta50) represents a crank position when mass burnt rate is 50 percent. The main combustion period (theta20-50) represents a period from a crank position when mass burnt is 20 percent to a crank position when mass burnt is 50 percent. Controlled parameters governing main combustion are varied to adjust the main combustion timing on an advance side of a retard limit (theta50 max) and to adjust the main combustion period within a range between an upper limit (theta20-50 max) and a lower limit (theta20-50 min).