Self-cleaning air filter

A self-cleaning air filter comprising a filter housing having a tubular body, a cover removably secured to one end of said body, latch means releasably securing said cover to said one end of said body, a first end wall connected to said tubular housing body at the end thereof opposite said removable cover, said first end wall having a central opening therein, a first tubular extension joined to said first end wall about said central opening in said first end wall and projecting outwardly therefrom, a second end wall connected to the end of said first extension opposite said first end wall, said second end wall having a central opening therein, a second tubular extension joined to said second end wall about the central opening therein and projecting outwardly therefrom, said first and second tubular extensions being coaxial with said tubular body and said second extension being of smaller diameter than said first extension, said extensions providing the outlet conduit for filtered air from said filter, an air inlet passage into said housing,

• a cylindrical filter cartridge removably and rotatably mounted in said housing, said filter cartridge having a perforated central tube, an annular filter media surrounding said central tube, an outer foraminous member surrounding said annular filter media and a pair of end caps secured to opposite ends of the filter cartridge, one of said end caps having a central opening therein to provide an outlet passage from one end of said perforated central tube, the other end cap being closed and having a central recess fitted snuggly in the other end of said central tube,
• a first rotary support means within said housing adjacent said one end wall for rotatably supporting one end of said filter cartridge, said rotary support means comprising a turntable having a circular plate with a central opening therein and a tubular neck joined to said plate about said central opening, radial bearing means mounted in said first extension for rotatably supporting said tubular neck in said first extension coaxially therewith, said circular plate being supported by said neck inside said housing adjacent to and substantially parallel to said first end wall, annular thrust bearing means secured to said first end wall for spacing said circular plate from said first end wall, said circular plate having an annular peripheral flange means for snuggly encompassing one end of said filter cartridge,
• a second rotary support means for rotatably supporting the other end of said filter cartridge, said second rotary support means being removably secured to the other end of said cartridge and being associated with said removable cover, said second rotary support means including a central aperture in said cover, a short shaft secured in said central aperture of said cover and projecting axially inwardly of said housing body when the cover is secured to said one end of said housing, a hub assembly rotatably mounted on the inner end of said short shaft, hub assembly centering means projecting into the recess of said closed end cap for centering said hub coaxially with said end cap, means for releasably securing said hub assembly to said closed end cap, resilient means interposed between said cover and said hub assembly for biasing said hub assembly and said filter cartridge toward said turntable,
• annular seal means secured on the circular plate of said turntable to prevent air flow between said circular plate and the end of said filter cartridge supported thereon;
• drive means for rotating one of said first and second rotary support means and thereby imparting rotation to said filter cartridge,
• an elongated air nozzle adjustably supported inside of said filter central tube of said filter cartridge for directing pressurized air radially outwardly through said filter cartridge to back flush same, said nozzle means having a closed back and a slotted open front adjacent the inner surface of said central tube,
• a source of air pressure supplying air to said nozzle,
• elongated cantilever support means fixed at one end inside of said second extension and extending through the neck of said turntable into the interior of said central tube,
• a plurality of saddle brackets supported at longitudinally spaced intervals on said cantilever support means inside of said central tube of said filter cartridge, said saddle brackets extending transversely over the back of said nozzle,
• a spring supported by each of said saddle brackets, each spring bearing against the back of said nozzle and biasing the front of said nozzle radially outwardly of said central tube,
• an elongated nozzle seal means interposed between the open front of said nozzle and the inside of said perforated central tube, said nozzle seal means surrounding the slotted open front of said nozzle for limiting air flow from said nozzle to a direction substantially radially outwardly from said nozzle through said perforated central tube,
• dust collecting means mounted opposite said nozzle in the space between the tubular body of said housing and said filter cartridge for collecting dust dislodged from said filter cartridge by air from said nozzle passing outwardly through said filter cartridge while back flushing same,
• a dust discharge passage through said housing communicating with said dust collecting means for passing dust from said dust collecting means to the outside of said housing,
• means for energizing said drive means for rotating said filter cartridge when back flushing is required, and air control means for supplying air from said air pressure source to said nozzle when said means for rotating said filter cartridge is energized.