Dry air filter for internal combustion engines of utility vehicles

In a dry air filter for internal combustion engines of utility vehicles having an outlet for the dust separated in a preliminary separator stage, compressed air is delivered to the outlet, at least intermittently, and in order to produce an ejector action to keep the outlet and optionally the dust discharge valve closing off the outlet free of dust, is blown in the direction of the dust discharge valve. Preferably, surplus compressed air already to hand from an on-board compressed air generating system is used for this purpose. In order to improve the cleaning action, the compressed air is delivered into the outlet via a nozzle.