RING FILTER ELEMENT WITH RADIALLY INNER ENGAGEMENT CONTOUR FOR ANGULAR POSITIONING

A ring filter element for air filtration has a filter medium body enclosing an interior. An open end disc and a closed end disc delimit seal-tightly the filter medium body axially. The filter medium body has a folded bellows and an inner wall surface provided with a fold expansion. The open end disc has a cutout aligned with the fold expansion. A filter device has a filter housing with fluid inlet and fluid outlet. A ring filter element arrangement arranged in the filter housing separates fluid inlet from fluid outlet. The ring filter element arrangement has a ring filter element. A positioning device has an engagement element which extends radially outwardly and engages a counter engagement element of the ring filter element which is at least partially formed by the fold expansion at the inner wall surface of the filter medium body of the ring filter element.