Filter device, especially air filter for an internal combustion engine

A filter device comprising a filter housing, a main filter element received in the filter housing, a cyclone preseparator embodied as a prefilter and a secondary filter element arranged downstream of the main filter element,

• the main filter element comprising:
• axially opposing intake side and outflow side;
• an intake end face arranged at said intake side at a first axial end of said filter element, said intake end face having an intake opening through which fluid to be filtered enters said filter element;
• an outlet end face arranged at an opposing second axial end of said filter element, said outlet end face having an outlet opening through which filtered fluid exits said filter element;
• wherein said filter element is embodied as a multi-bellows filter with at least two radially nested filter bellows;
• wherein said intake opening and said outlet opening are at opposing axial ends of said filter element;
• a first filter bellows construction with filter media folds extending axially between said intake end face and said outlet end face;
• wherein said first filter bellows construction radially surrounds and delimits an axially extending first flow space within said first filter bellows construction;
• wherein said first flow space is in flow communication with only one of said intake opening or said outlet opening;
• a second filter bellows construction with filter media folds extending axially between said intake end face and said outlet end face, said second filter bellows construction arranged radially outwards of and radially surrounding said first filter bellows construction;
• wherein a second flow space is defined in a gap between an radially outer surface of said first filter bellows construction and a radially inner surface of said second filter bellows construction;
• wherein said second flow space is in flow communication with a different one of said intake opening or outlet opening than said first flow space;
• wherein said flow opening at said opposing flow face is an annular flow opening through said opposing flow face in flow communication with said second flow space;
• wherein said filter element is a one-piece component inserted into and removed from a filter housing as a single component;
• wherein said second filter bellows construction is a star-shaped filter with filter folds arranged in a star shape and on at least one end face of the filter element a seal is arranged between said second filter bellows construction and the filter housing,
• wherein a third flow space is provided at a radially outer surface of said second filter bellows construction,
• wherein said third flow space is in flow connection with said first flow space, such that said first flow space and said third flow space are on same filtered or unfiltered side of said filter element.