Air cleaners

An air cleaner comprising a shallow housing having a first outer end wall and a second inner end wall, said inner and outer end walls connected by a peripheral wall, a plurality of tubular dust separator elements arrayed in the housing for generally straight through flow of air across the thickness of said housing, wherein

• each separator element comprises
• a tubular portion having inner and outer generally cylindrical surfaces,
• an annular inlet generally defined by said first outer end wall of said housing, said inlet further defined by an annular inlet wall and a central dome,
• the inner surface of said tubular portion being of greater diameter than the inlet wall,
• inclined vanes connecting said annular inlet wall and said central dome adapted to impart spin to dust-laden air entering said inlet,
• an air outlet generally defined by said second, inner end wall of said housing, said wall having an annular portion extending from the surface thereof toward said air inlet,
• said air outlet of smaller diameter than said inlet and coaxial with said inlet and the inner surface of said tubular portion,
• an annular space remote to said inlet defined by at least the inner surface of said tubular portion and by the annular inwardly extending portion of the inner housing wall,
• a circumferential dust exit defined in said tubular portion adjacent to said annular space, said exit extending over a limited arc within the range 45.degree. to 90.degree.,
• the housing defines about the separator elements a closed dust collection chamber, said chamber containing means for guiding flow of air in said chamber, the guide means including the generally cylindrical outer surface of said tubular portion, and
• the vanes of the plurality of separator elements being inclined so as to impart left- or right-handed spin to air passing therethrough, with elements having vanes adapted to impart left-handed spin positioned adjacent to elements having vanes adapted to impart right-handed spin in said array of elements,
• whereby dust-laden air entering a first separator element through said air inlet is imparted with left- or right-handed spin and enters said annular space, the circulating air mass in the annular space inducing at the exit a corresponding circulation of an air mass in the dust collection chamber surrounding said first separator element, the opposite direction of flow being imparted to air flow in adjacent separator elements and thereby in the air masses surrounding said adjacent elements reinforcing the circulating flow in the closed dust collection chamber, dust in the spinning air flow mass in the annular space of said first element is directed toward the inner surface of the tubular portion by the imparted spin and held in suspension by the air mass circulating in the annular space, air substantially free of dust leaves said separator element via said air outlet, and dust in the air flow mass passing the exit is separated from the air flow mass in said annular space remote to said inlet by centrifugal force with a radial velocity component and enters the air flow mass in the surrounding dust collection chamber, the dust collection chamber being closed so substantially no air flows through the exit between the separator element and the dust collection chamber.