A filter assembly including a filter media sized for positioning within an air induction system, the filter media possessing a first side and a second side substantially opposite the first side. The filter assembly includes a layer of sound absorbing foam positioned adjacent one of the first side of the filter media and the second side of the filter media, the sound absorbing foam including a plurality of perforations therein, the plurality of perforations permitting air to flow through the filter media and the layer of sound absorbing foam.

An intake system component of an internal combustion engine includes a porous material product and a resin molded portion. The porous material product is formed from a porous material and includes an outer edge and a general portion. The resin molded portion encompasses the outer edge and is formed integrally with the porous material product. The general portion is located outside the resin molded portion. The outer edge has a lower filling density than the general portion.

It is provided that a pre-air-filter, for an internal combustion engine, which allows stiffness to be assured even when the weight is reduced, which also has excellent dust holding properties, and which has an excellent resistance to entry of water. A pre-air-filter for an internal combustion engine (1) contains a nonwoven fabric comprising a first fiber having a melting point of not lower than 80 C. and not higher than 200 C., a second fiber having a melting point of higher than the melting point of the first fiber by not less than 30 C., being crimped, and having a hollow structure, entanglement of the first fiber and the second fiber by needle punching, and fusion of partly or entirely melted first fiber and the second fiber. This pre-air-filter (1) is installed at an air-inlet-side of a main-air-filter (2).

Air filter cartridges are disclosed. Also described are air cleaners including the filter cartridges. Methods of assembly and use are also provided. Also, systems of use are described.

Provided is a non-woven filtration material including a multilayer structure having a density gradient. The multilayer structure includes a coarse layer disposed at an upstream side of the non-woven filtration material and a dense layer disposed at a downstream side of the non-woven filtration material. The coarse layer and the dense layer are dry layers. The coarse layer contains 30% to 60% by weight of crimped conjugated fibers and contains 30% to 70% by weight of finer fibers. The crimped conjugated fibers have an average fiber diameter in a range from 15 m to 45 m. The finer fibers have an average fiber diameter that is in a range from 5 m to 20 m and smaller than the average fiber diameter of the conjugated fibers.