Abstract: A filter system for filtering a fluid has a filter housing with housing top part and housing bottom part, wherein the housing top and bottom parts extend along a housing axis. A filter pack arranged in the filter housing separates fluid-tightly a clean fluid side and a raw fluid side from each other. The filter pack has a filter element with a hollow cylinder-type filter bellows arranged about a longitudinal axis of the filter element. The filter element has a first substantially closed end face and a first end disk arranged thereat, wherein the first end disk is positioned opposite a second end disk of the filter element. The second end disk has a fluid passage for filtered fluid. A resonator with an end closed by a bottom is arranged inside the filter pack such that the bottom is oriented toward the first end disk of the filter element.

Abstract: A filter element for a filter system has a hollow cylinder-type filter bellows with an end face and a substantially closed bottom provided thereat. At least one resonator structure provided at the bottom provides noise attenuation of a flowing fluid. The resonator structure has two or more grooves arranged at an outer side of the bottom and separated from each other by a partition. At least one of the grooves is connected in fluid communication through an opening to an interior of the filter element. The resonator structure, when installed in a filter housing of the filter system as intended, seals tightly relative to a complementary resonator structure of the filter housing. The grooves are connected in fluid communication through connection openings arranged in the resonator structure of the filter element and/or the complementary resonator structure of the filter housing. A filter system with such a filter element is provided.

Abstract: A secondary element for a filter system has first and second ends oppositely positioned to each other in longitudinal direction. The first end is closed by a closed end disk. The closed end disk has a first connection device for interacting with a complementary second connection device of a central tube of the filter system and for fixing the secondary element on the central tube. The first connection device has lock elements with radially inwardly oriented lock hooks distributed circumferentially on the closed end disk. A filter medium surrounds the lock elements. The lock elements include two directly neighboring lock elements having a distance relative to each other along the circumference of the closed end disk that is larger than a circumferential measurement of a radially outwardly oriented deflection element arranged at a collar of the central tube. A filter system with such a secondary element is provided.

Abstract: A filter element for filtering a fluid has a support pipe and a filter bellows arranged about a longitudinal axis on the support pipe. The filter bellows has folds with radially outer fold edges. The filter bellows has a first axial end and a second oppositely positioned axial end. The filter bellows has a notch at least at one of the first and second axial ends. An axial length of the notch in longitudinal direction is shorter than a longitudinal extension of the filter bellows. The support pipe has a support structure at the axial end with the notch and has at least two wings. The support structure is oriented radially away from the support pipe and is integrated into the end disk at both sides of the notch. A filter system with such a filter element arranged in a housing is provided.