Method for operating a direct injection internal combustion engine

Abstract

The invention relates to a method of operating a direct injection internal combustion engine operated on both spark-ignitable and autoignitable fuel, more specifically on gasoline, wherein the operational range of the engine is allocated autoignition ranges and spark-ignition ranges, an at least nearly homogeneous fuel-air mixture being produced in the combustion chamber in autoignition ranges, a high compression ratio suitable for spontaneous ignition of the fuel being provided and the combustion in the autoignition range being mostly initiated by spontaneous ignition, and wherein, in the ranges of spark ignition, combustion is initiated by spark ignition of said air-fuel mixture and a spark ignition range is assigned to the full load range and an autoignition range assigned to at least part of the part load range and wherein the effective compression ratio is lowered in spark ignition ranges and combustion controlled by regulating the residual gas content in the ranges of spontaneous ignition. In order to improve the exhaust emission quality while keeping efficiency high, the operational range of the engine is allocated two-stroke and four-stroke operational ranges and the internal combustion engine is operated on a two-stroke cycle in the ranges operating in the two-stroke mode and on a four-stroke cycle in the ranges operating in the four-stroke mode.

Dependencies are inferred from the claim text.