Metering unit for a cleaning device, wherein the metering unit comprises a receiving unit for inserting a cartridge, which contains a cleaning agent for a cleaning process of the cleaning device, into the receiving unit and for removing the cartridge from the receiving unit; characterized in that the metering unit further comprises a detection device both for detecting whether the cartridge is inserted into the receiving unit or is removed from the receiving unit, and also for detecting a level of a cleaning liquid, which contains the cleaning agent, in the receiving unit; wherein the detection device comprises a first detection unit and a second detection unit; wherein the first detection unit is arranged to be movable back and forth, relative to the receiving unit, between a first position and a second position; wherein the first detection unit and the second detection unit are coupled to one another such that a relative movement between the first detection unit and the second detection unit is possible at least in a certain position of the first detection unit relative to the receiving unit; wherein the second detection unit can assume an operating position, an empty position, and an overflow position relative to the receiving unit; and wherein the metering unit is configured such that: - when the cartridge is removed from the receiving unit, the second detection unit is arranged in the empty position, - when the cartridge is inserted into the receiving unit and the level is below a first threshold value, the second detection unit is arranged in the operating position, and - when the cartridge is inserted into the receiving unit and the level is above a second threshold value, which is greater than or equal to the first threshold value, the second detection unit is arranged in the overflow position. the metering unit further comprises a detection device both for detecting whether the cartridge is inserted into the receiving unit or is removed from the receiving unit, and also for detecting a level of a cleaning liquid, which contains the cleaning agent, in the receiving unit; wherein the detection device comprises a first detection unit and a second detection unit; wherein the first detection unit is arranged to be movable back and forth, relative to the receiving unit, between a first position and a second position; wherein the first detection unit and the second detection unit are coupled to one another such that a relative movement between the first detection unit and the second detection unit is possible at least in a certain position of the first detection unit relative to the receiving unit; wherein the second detection unit can assume an operating position, an empty position, and an overflow position relative to the receiving unit; and wherein the metering unit is configured such that: - when the cartridge is removed from the receiving unit, the second detection unit is arranged in the empty position, - when the cartridge is inserted into the receiving unit and the level is below a first threshold value, the second detection unit is arranged in the operating position, and - when the cartridge is inserted into the receiving unit and the level is above a second threshold value, which is greater than or equal to the first threshold value, the second detection unit is arranged in the overflow position. - when the cartridge is removed from the receiving unit, the second detection unit is arranged in the empty position, - when the cartridge is inserted into the receiving unit and the level is below a first threshold value, the second detection unit is arranged in the operating position, and - when the cartridge is inserted into the receiving unit and the level is above a second threshold value, which is greater than or equal to the first threshold value, the second detection unit is arranged in the overflow position.