Air filter

Claim 1

A SELF-CLEANING DUST FILTERING APPARATUS COMPRISING A PLURALITY OF OPEN-ENDED DUST FILTERING SLEEVES, A FRAME ON WHICH SAID SLEEVES ARE MOUNTED, SAID FRAME INCLUDING UPPER AND LOWER PLATES HAVING VERTICALLY ALIGNED OPENINGS THEREIN BETWEEN WHICH SAID SLEEVES ARE REMOVABLY DISPOSED, A HOOD OF SUBSTANTIALLY THE SAME AREA AS SAID UPPER PLATE POSITIONED OVER THE UPPER PLATE AND HAVING A CONICAL WALL TAPERING UPWARDLY TO AN AIR INLET NEAR ITS UPPER END, SAID HOOD DEFINING AN INLET CHAMBER COMMUNICATING DIRECTLY WITH ALL OF SAID FILTERING SLEEVES, A PLURALITY OF DOORS ONE FOR EACH SAID SLEEVE PIVOTALLY MOUNTED BELOW SAID LOWER PLATE, RESILIENT MEANS POSITIONED BELOW THE LOWER PLATE URGING SAID DOORS TO CLOSE ALL THE OPENINGS IN SAID LOWER PLATE AND LEAVING SAID SLEEVES FREE FOR UNIMPEDED AIR FLOW THERETHROUGH WHEN SAID DOORS ARE OPENED, A DUST COLLECTING CHAMBER BELOW SAID DOORS HAVING A SIDE WALL AND A BOTTOM WALL, A DUST OUTLET IN THE BOTTOM WALL OF SAID CHAMBER, AT LEAST ONE SCREENED OPENING IN THE SIDE WALL OF SAID CHAMBER, AND MEANS FOR OPENING SAID DOORS PERIODICALLY IN SEQUENCE SO THAT THE DUST LADEN AIR PASSES FROM END TO END THROUGH EACH SLEEVE HAVING ITS DOOR OPEN AND THE DUST WITHIN THE SLEEVE IS DISCHARGED INTO THE DUST COLLECTING CHAMBER WHEREBY CLEANING OF THE FILTER SLEEVES TAKE PLACE DURING OPERATION OF THE FILTERING APPARATUS AND THE DUST LADEN AIR EXITS THROUGH SAID SCREENED OPENING IN THE DUST COLLECTING CHAMBER.