Backflushed air filters

A porous media barrier type air filter unit, said filter unit including:

• a housing forming a filter chamber including means for conducting dust laden air into said chamber;
• a porous media barrier filter element in said filter chamber, said filter element including a first planar filter panel, said filter panel defining at least in part a clean air chamber for receiving air which has flowed through said filter element, said clean area chamber having an opening for discharging clean air from said clean air chamber;
• means for supporting said filter element in said filter chamber;
• means forming a flow tube opening into said clean air chamber for conducting clean air from said clean air chamber and away from said filter element;
• reverse flow air jet nozzle means disposed downstream of said filter element with respect to the direction of flow of clean air through said filter element, said nozzle means being in communication with a source of pressure air and including a plurality of orifices arranged in a predetermined pattern for discharging a shaped jet of pressure air for contact with the walls of said flow tube, said nozzle means being arranged in such a way as to generate a jet having a cross-sectional shape conforming to the cross-sectional shape of said flow tube and for inducing a relatively large volume of substantially ambient pressure air into said flow tube in a direction opposite to the direction of flow of clean air out of said flow tube to backflush said filter element with a quantity of combined induced and jetted pressure air, wherein said first filter panel is canted inwardlly with respect to said flow tube opening, whereby said jet of pressure air impinges directly upon said first filter panel.

A porous media barrier type air filter unit, said filter unit including:

• a housing forming a filter chamber including means for conducting dust laden air into said chamber;
• a porous media barrier filter element in said filter chamber, said filter element including a first planar filter panel, said filter panel defining at least in part a clean air chamber for receiving air which has flowed through said filter element, said clean air chamber having an opening for discharging clean air from said clean air chamber;
• means for supporting said filter element in said filter chamber;
• means forming a flow tube opening into said clean air chamber for conducting clean air from said clean air chamber and away from said filter element, wherein said clean air chamber is tapered inwardly with increasing distance from said flow tube opening, whereby the clean air chamber discharge velocity is constant throughout the clean air chamber length as measured inwardly from said flow tube opening;
• reverse flow air jet nozzle means disposed downstream of said filter element with respect to the direction of flow of clean air through said filter element, said nozzle means being in communication with a source of pressure air and including a plurality of orifices arranged in a predetermined pattern for discharging a shaped jet of pressure air for contact with the walls of said flow tube, said nozzle means being arranged in such a way as to generate a jet having a cross-sectional shape conforming to the cross-sectional shape of said flow tube and for inducting a relatively large volume of substantially ambient pressure air into said flow tube in a direction opposite to the direction of flow of clean air out of said flow tube to backflush said filter element with a quantity of combined induced and jetted pressure air.