Abstract: A filter system, including a folded filter (1) and a cover (2) of a filter housing (3), the folded filter (1) and the cover (2) forming a preassemblable unit (4) and being essentially sealingly joined to each other so as to be detachable without destruction.

Abstract: A filter cartridge is made of an accordion fold pack folded in a zigzag-shape. At the end faces (4) of the accordion fold pack, running parallel to the folds, provision is made for the closing elements (5) which include stiffening strips (6), partially covering the accordion fold pack (2), at least on its discharge side, and sealing elements (7) integrally connected to the stiffening strips (6).

Abstract: A filter assembly includes an accordion fold pack made of filter material, which is sealingly joined to a retention frame. The retention frame has at its end face, at least on one side, a bracing whose length corresponds essentially to length of an end-face fold of the accordion fold pack extends the bracing essentially parallel to the direction of the end-face fold edge of the accordion fold pack and is arranged in the end-face fold. Disposed at the end face of the retention frame is a double sealing lip which extends in the direction of the end-face fold edge, as well as essentially parallel to the bracing. The double sealing lip is able to swivel about a film-hinge-type joint, and can be sealingly positioned with first sealing lip against end-face fold wall, and with second sealing lip against a boundary wall of a filter housing that faces the fold wall.