Patent ID: 6915790

Claim:
Process for operating a piston engine in which at least one intake valve and at least one exhaust valve are assigned to each cylinder of said piston engine and in which a valve actuator permits variable opening and closing times for the valves, comprising determining a current actual value of an exhaust gas mass proportion which forms the contents of each cylinder together with a fresh gas mass proportion after fresh gas has been supplied to each cylinder and before combustion, and actuating the valve actuator to set a desired value for the exhaust gas mass proportion, wherein the associated actual value of the exhaust gas mass proportion is individually determined for each cylinder and the valve actuator is actuated individually for each cylinder to set the desired value for the exhaust gas mass proportion, and exhaust gas recirculation is provided to operate with the piston engine at least in certain operating states, and the engine control system is configured to actuate the valve actuator so that an exhaust gas recirculation is achieved solely by an internal exhaust gas recirculation.