Cover lens cleaning system comprising - a cover lens for closing an opening of a housing and - a cleaning device, wherein the cover lens is transparent, wherein the cleaning device comprises - an air connection, via which air can be supplied to the cleaning device, and - an air outlet and wherein an air guide channel is formed in the cleaning device, which opens into the air outlet, wherein the air supplied to the cleaning device flows to the air outlet via the air guide channel and emerges from the latter in the form of an air flow which, for cleaning the cover lens, acts on the outer surface of the cover lens, the air outlet being arranged in a lower region of the cover lens in the installed position of the cover lens such that the air flow is directed from below onto the outer surface of the cover lens, characterized in that one or more drainage openings leading into an outer space are provided on an underside, via which moisture or liquid, such as water, present in the cleaning device, for example in the air duct, can escape, wherein - in the installed position - at least one membrane element is arranged above the one or more drainage openings, which is reversibly deformable and which is designed in such a way that in a first, the so-called ON-state, in which the cleaning device is pressurized with air, the at least one membrane element is deformed in such a way that the one or more drainage openings are closed, and that in a second, the so-called OFF state, in which the cleaning device is not acted upon by air, the at least one membrane element is deformed in such a way that the one or more drainage openings are at least partially not closed. - a cover lens for closing an opening of a housing and - a cleaning device, wherein the cover lens is transparent, wherein the cleaning device comprises wherein the cover lens is transparent, wherein the cleaning device comprises - an air connection, via which air can be supplied to the cleaning device, and - an air outlet and wherein an air guide channel is formed in the cleaning device, which opens into the air outlet, wherein the air supplied to the cleaning device flows to the air outlet via the air guide channel and emerges from the latter in the form of an air flow which, for cleaning the cover lens, acts on the outer surface of the cover lens, the air outlet being arranged in a lower region of the cover lens in the installed position of the cover lens such that the air flow is directed from below onto the outer surface of the cover lens, characterized in that one or more drainage openings leading into an outer space are provided on an underside, via which moisture or liquid, such as water, present in the cleaning device, for example in the air duct, can escape, wherein - in the installed position - at least one membrane element is arranged above the one or more drainage openings, which is reversibly deformable and which is designed in such a way that in a first, the so-called ON-state, in which the cleaning device is pressurized with air, the at least one membrane element is deformed in such a way that the one or more drainage openings are closed, and that in a second, the so-called OFF state, in which the cleaning device is not acted upon by air, the at least one membrane element is deformed in such a way that the one or more drainage openings are at least partially not closed. and wherein an air guide channel is formed in the cleaning device, which opens into the air outlet, wherein the air supplied to the cleaning device flows to the air outlet via the air guide channel and emerges from the latter in the form of an air flow which, for cleaning the cover lens, acts on the outer surface of the cover lens, the air outlet being arranged in a lower region of the cover lens in the installed position of the cover lens such that the air flow is directed from below onto the outer surface of the cover lens, characterized in that one or more drainage openings leading into an outer space are provided on an underside, via which moisture or liquid, such as water, present in the cleaning device, for example in the air duct, can escape, wherein - in the installed position - at least one membrane element is arranged above the one or more drainage openings, which is reversibly deformable and which is designed in such a way that in a first, the so-called ON-state, in which the cleaning device is pressurized with air, the at least one membrane element is deformed in such a way that the one or more drainage openings are closed, and that in a second, the so-called OFF state, in which the cleaning device is not acted upon by air, the at least one membrane element is deformed in such a way that the one or more drainage openings are at least partially not closed.