METHOD FOR OPERATING A COMBUSTION ENGINE, IN PARTICULAR A DIESEL ENGINE

The invention relates to a method for operating an internal combustion engine, in particular a diesel engine, wherein an external exhaust gas recirculation device (39) is provided, by means of which the exhaust gas (25) emitted by the internal combustion engine (7) can be supplied back to the internal combustion engine (7), wherein the exhaust gas recirculation device (39) has a recirculation actuator (43), by means of which the quantity of recirculated exhaust gas (25) is adjustable, wherein a closing timing actuator (47) is provided, by means of which the closing timing of the at least one intake valve of the internal combustion engine (7) is adjustable, wherein by means of the closing timing actuator (47) a base cycle of the internal combustion engine (7) is adjustable, in which the at least one intake valve of the internal combustion engine (7) closes in a crank angle range of 1° to 40° crank angle, in particular of 10° to 40° crank angle, after BDC (bottom dead center). According to the invention, in order to reduce the nitrogen oxides emitted by the internal combustion engine (7), a nitrogen oxide reduction cycle can be set by means of the closing timing actuator (47), in which the at least one intake valve of the internal combustion engine (7) closes earlier or later compared to the base cycle, wherein a control device (57) is provided, by means of which the closing timing actuator (47) and the recirculation actuator (43) are regulated and/or controlled as a function of the torque of the internal combustion engine (7), wherein, if the torque (M) of the internal combustion engine (7) falls below at least one defined torque limit value (MGrenz), the internal combustion engine (7) is operated in the base cycle and the recirculation of the exhaust gas by means of the recirculation actuator (43) is enabled, and wherein, if the torque (M) of the internal combustion engine (7) exceeds the defined torque limit value (MGrenz), the internal combustion engine (7) is operated in the nitrogen oxide reduction cycle and the recirculation of the exhaust gas by means of the recirculation actuator (43) is blocked.