Dual media air filter

Claim 1

An air filter assembly having a flat silhouette and adapted for use on automotive internal combustion engines comprising a housing having a vertiCal axis and a height along said axis that is relatively small compared with the width of the housing transverse to said axis, said housing having a tubular wall means providing central outlet passage substantially coaxial with said axis and first housing wall means providing an annular air inlet chamber disposed around and substantially concentric with said outlet passage, said air inlet chamber having an inlet for air to be filtered, said housing having second housing wall means providing an air outlet chamber communicating with said outlet passage, said housing including inner and outer annular seats and an annular pancake shaped filter body supported on said seats and separating the inlet chamber and the outlet chamber, said filter body being substantially coaxial with said vertical axis and having a height in the direction of said axis that is relatively small compared with the width of the filter body transverse to the axis, the transverse distance between said inner and outer seats being relatively large compared with the vertical height of said filter body and the transverse width of the body between said inner and outer seats being unsupported, the inlet side of said body extending transversely between said inner and outer seats being exposed to the pressure of incoming air, said filter body comprising an inlet upstream section and a downstream outlet section each extending across the full width of the filter body and engaging each other on a surface defined by the outlet side of the inlet section of the body, the inlet side of said body comprising inlet side of said inlet section and said inlet side being substantially parallel to said outlet side, said inlet section comprising a semi-rigid pad-like homogeneous porous body formed of synthetic, controlled and predetermined diameter fibers bonded to each other and having a predetermined substantially uniform thickness, density, and porosity throughout and in the absence of a support means being subject to flexing in the direction of said vertical axis as a result of air pressure on it, said body having a high dirt-holding capacity and serving as a depth type filter, said outlet section comprising a body of substantially uniform thickness air filter paper having a high dirt removal efficiency and a relatively low dirt-holding capacity compared with the inlet section and having a relatively thin thickness compared with the inlet section, said outlet section paper being pleated with the pleats extending transversely to said vertical axis and across substantially the full width of the filter body and the apices of a multitude of said pleats engaging the outlet side of said inlet section so that said outlet section acts as an anti-flexing support means for said inlet section, said inlet and outlet section bodies having compressed inner and outer peripheral flanges connected together to form inner and outer resilient annular rims, said inner and outer rims engaging said inner and outer annular seats, and first and second clamping means in said housing respectively clamping said inner and outer rims to said inner and outer seats to form air tight squeeze seals between said filter body and housing to prevent by-passing of air from the inlet to the outlet chamber.

Claim 9

The method of making a dual media filter which comprises forming a fibrous filter pad of substantially uniform thickness in the direction of fluid flow, forming a flange from said pad around its outer periphery by compressing the outer edge portion of the pad relative to the inward portions, forming a pleated sheet of filter paper, forming a rim around the outer periphery of the paper by crushing the ends of the pleats and folding and nesting them together, placing the rimmed sheet of pleated paper on the pad inside the flange on said pad and bending and compressing the flange over the rim and uniting the pad and paper.

Claim 10

The method of making a dual media filter which comprises forming a fibrous filter pad of substantially uniform thickness in the direction of fluid flow, forming a flange from said pad around its outer periphery by compressing the outer edge portion of the pad relative to the inward portions, forming a pleated sheet of filter paper, forming a rim around the outer periphery of the paper by crushing the ends of the pleats and folding and nesting them together, placing the rimmed sheet of pleated paper on the pad inside the flange on said pad and bending and compressing the flange over the rim and uniting the pad and paper.