Abstract: To operate an internal combustion engine subvolumes of the fluid flowing into an intake duct in each instance during a predetermined time period are determined for each period. Tank purging values of a characteristic quantity are determined for each period. The characteristic quantity is representative of a tank purging fuel mass, which flowed through the tank purging valve in each instance during the predetermined time period. The successive subvolumes are added together, starting from the currently determined subvolume, to give a total subvolume, until the total subvolume is greater than or equal to an effective intake duct volume downstream of the tank purging valve.

Abstract: For the purposes of a determination of a fuel vapor loading level of a fuel vapor retention system of a combustion engine, an opening level of a valve of the fuel vapor retention system is increased in steps or continuously during a determination phase. Furthermore, the valve is activated at most a predefined first period prior to a start of the determination phase by a conditioning pulse at least whenever the valve was closed previously for a second period that is longer than a predefined threshold value. The conditioning pulse is generated in such a way that the valve definitely opens at most for a predefined opening period and then closes again.

Abstract: An internal combustion engine has an intake duct, which opens into at least one inlet of at least one cylinder. It also has a tank purging valve, which is configured to control the initiation of a tank purging flow into the intake duct at an inlet point upstream of the respective inlet of the respective cylinder. A main path is configured in the intake duct and a recirculation path is configured there with a recirculation control element, a recirculation inlet from the main path into the recirculation path and a recirculation outlet from the recirculation path into the main path. The recirculation outlet is disposed in the main path upstream in relation to the recirculation inlet. A cylinder tank purging fuel mass is determined as a function of an opening angle of the tank purging valve and an opening angle of the recirculation control element.