Abstract: An air filter unit, including a filter medium held on reels, a drive mechanism for automatic filter reeling, having a filter medium in the form of an exchangeable filter element inserted in a recess in the air filter unit; the filter element comprising a housing featuring two parallel shafts located at opposite sides of the frame; the shafts being located at a distance from each other that allows for the taut positioning of the effective filter area between them; whereby at least one of the shafts is detachably connected to at least one force transfer element attached to an electric drive installed in the air filter unit and driven by an electric drive; including an exchangeable air freshener cartridge placed inside or to the side of the air filter unit, releasing air freshener to the filter medium through at least one valve.