Patent ID: 6902592

Claim:
An air filter assembly, comprising: a housing including an air inlet and an air outlet, said housing including a wall separating the housing into a filtering chamber and a clean air chamber, said wall including at least one air flow aperture therethrough; an elongated substantially tubular filter element positioned in air flow communication with the air flow aperture at an end of the filter element, said filter element including filter media having an inner dimension defining an inner chamber and said filter element being oriented with the inner chamber in air flow communication with the aperture; a reverse flow cleaning system, comprising: a venturi element having an inlet portion with an inlet opening, an outlet portion with an outlet opening, and a narrowed throat portion therebetween, said inlet opening substantially corresponding in size with the inner dimension of the filter element and positioned on the housing wall to project into the clean air chamber of the housing; a blowpipe for selectively delivering a reverse direction pulse of air having an outlet nozzle and being substantially axially aligned with the outlet opening of the venturi, said nozzle being flared in a substantially conical shape and having an included angle that exceeds an angle at which high pressure air would ordinarily diverge from an unmodified blowpipe opening, said nozzle being axially spaced from the venturi at a selected distance such that a high velocity pulse of air delivered by the blowpipe through the nozzle is delivered to the outlet portion of the venturi substantially between the outlet opening and the throat to effectively completely choke all forward movement of air flow through the venturi and to deliver a pulse wave of high pressure, high velocity air along substantially the full length of the filter element.