Filter cartridge

#The invention relates to a filter cartridge, in particular for the air filter of an internal combustion engine, in which the air filter has a housing for holding the filter cartridge with an inlet for untreated air and an outlet for clean air, in which the filter cartridge comprises a filter medium that preferably is folded in a zigzag shape (i.e., pleated) and is provided with sealing elements on end plates disposed at the axial end faces of the cartridge.

#A filter cartridge of this type is known, for example, from published international patent application no. WO 95/19382. The filter cartridge is arranged in a housing that has an inlet for untreated air and an outlet for clean air. The filter cleans the intake air in an internal combustion engine. Since the filter cartridge is replaced at regular intervals, it must be manufactured as economically as possible. The filter cartridge must also be easy to remove and install, as well as assure a reliable seal between the region of untreated air and the region of clean air.

#This known filter cartridge is clamped between two concentric surfaces of the filter housing. The clamping action also simultaneously creates a seal, which must be maintained during shock or vibration.

#The invention will be described in further detail hereinafter with reference to illustrative preferred embodiments shown in the accompanying drawings in which:

#FIG. 1 is a sectional view of one embodiment of filter cartridge constructed in accordance with the present invention, and

#FIG. 2 is a partially cut away sectional view of a second filter cartridge embodiment constructed in accordance with the present invention.

#The air filter according to the sectional view of FIG. 1 comprises a filter housing 10 that is sealed by a lid or cover 11. An inlet for untreated air 12 is situated on the filter housing 10, and an outlet for clean or filtered air 13 is situated on the end face opposite from the lid 11. An axial cyclone 14 is provided on the inner circumference of the filter housing 10, and a concentric connection piece 15 located in the vicinity of the clean air outlet 13 extends inwardly into the interior of the housing.

#Situated in the filter housing 10 is a filter cartridge 16 comprising a filter medium such as filter paper, for example, that is folded in a zigzag shape and arranged on a support body 17. The end faces of the filter cartridge 16 are provided with elastic or resilient end plates 18, 19. A safety filter element 21 is also situated in the housing, and likewise comprises a filter cartridge 20 or non-woven fabric and a support body that is arranged in the filtered air outlet 13 by means of attachment fittings 22.

#The support body 17 of the filter cartridge 16 is provided with support surfaces 23 on the end facing toward the filtered air outlet. The support surfaces rest against the connection piece 15 at the filtered air outlet and thereby radially fix the filter cartridge 16. The support body 17 is situated axially in contact with an annular support surface 24, thereby defining the axial position of the filter cartridge. A foam interlayer may be provided, if needed. The support body 17 merges directly into the end plate 18 on the axial end of the filter cartridge facing toward the cover.