Patent ID: 7438045

Claim:
A method of operating an internal combustion engine ( 1 ) comprising cylinders ( 2 ), each having a combustion chamber ( 4 ) and including a longitudinally movable piston ( 3 ), a cylinder head ( 5 ) delimiting the combustion chamber ( 4 ) and including a spark plug ( 8 )), the cylinder head ( 5 ) having a fresh gas inlet passage ( 13 ) with an inlet valve ( 6 ) and an exhaust gas outlet passage ( 14 ) provided with an outlet valve ( 7 ) operated by a valve drive ( 26 ) for controlling the admission of fresh gas to, and the discharge of exhaust gas from, the combustion chamber ( 4 ), said method comprising the steps of: operating the internal combustion engine in high load ranges in a spark ignition mode wherein a stoichiometric air fuel mixture is provided in the combustion chamber ( 4 ) and ignited therein by the spark plug ( 8 ), operating the internal combustion engine ( 1 ) during lower load operation in a compression ignition mode, wherein a lean air/fuel mixture is provided in the combustion chamber ( 4 ), controlling the temperature in the combustion chamber by changing the inlet and outlet valve opening times such that a controllable amount of exhaust gases is retained in the combustion chamber so as to participate in the formation of the air/fuel mixture for increasing the temperature thereof by providing during a compression mode of operation an increased valve overlap in comparison with the spark ignition mode of operation and, for a change between a spark ignition mode of operation and a compression mode of operation, changing the injection parameters, the throttling of the fresh gas flow and the valve control in a coordinated manner, wherein the valve control is switched over by changing the amplitude and the phase position of the valve lift of at least one of the gas exchange valves ( 6 , 7 ) and, depending on the desired operating load of the engine ( 1 ), with a change-over to the compression ignition mode of operation, the injection duration of a main fuel injection is reduced and, in a first operating cycle of the cylinder with compression ignition, the injection timing is retarded.