Patent ID: 7284531

Claim:
A method for operating a four-stroke internal combustion engine, wherein, to provide a cylinder charge: fuel is injected directly into at least one combustion chamber of the internal combustion engine, the volume of which changes cyclically, fresh gas is supplied to the combustion chamber through at least one intake valve and exhaust gas is discharged through at least one exhaust valve, during part-load operation, a lean base mix of air, fuel and retained exhaust gas is formed, and during full load operation a stoichiometric mix is formed, compression ignition takes place during part-load engine operation and spark ignition takes place during full load engine operation, and the fuel quantity is supplied to the combustion chamber in a pre-injection step in the form of a pre-injection fuel quantity and during a main injection step in the form of a main injection fuel quantity, said method comprising the steps of injecting fuel during part-load operation, in which compression ignition takes place in the pre-injection step, before the top dead center of the gas exchange depending on the location of a center of combustion of the cylinder charge, and injecting the main fuel quantity synchronously with the induction of the fresh gas into the cylinder.