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 the 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, 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, an annular metallic backfire screen engaging the outlet side of the paper forming said outlet section, said inlet and outlet section bodies and said screen having inner and outer peripheries, substantially C-shaped seal elements binding the inner peripheries together and the outer periph-eries together and forming inner and outer resilient annular sealing rims, said inner and outer rims engaging said inner and outer annular seats, said 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 bypassing of air from the inlet to the outlet chamber.

Claim 7

The method of making an air filter member which comprises axially aligning an annular pad of fibrous material, an annular sheet of air filter paper, and an annular backfire screen so that their inner and outer peripheries are in contact to form inner and outer annular joints, surrounding said joints with moldable plastic material, and solidifying the plastic material to form resilient seals serving to bind the peripheries together and integrate the joints and unite the pad and paper.

Claim 8

The method of making an air filter member which comprises axially aligning an annular pad of fibrous material, an annular sheet of air filter paper, and an annular backfire screen so that their inner and outer peripheries are in contact to form inner and outer annular joints, surrounding said joints with moldable plastic material, and solidifying the plastic material to form resilient seals serving to bind the peripheries together and integrate the joints and unite the pad and paper.