Patent ID: 8458855

Claim:
A mobile surface maintenance machine comprising: a debris hopper movable between an operational position and a debris dump position; an exhaust conduit in air communication with the debris hopper when the debris hopper is in said operational position; and an exhaust fan in air communication with the exhaust conduit and drawing an airstream [air]through the debris hopper when the debris hopper is in said operational position, with said debris hopper having a debris inlet into which dust and debris is thrown by a sweeping brush or drawn in to the debris hopper by action of said exhaust fan, said debris hopper having an upper opening supporting a filter module, said filter module providing two filter stages for separating dust and debris from the airstream, with a first filter stage including a plurality of cone-shaped vortex separators having open lower ends through which dust and debris are removed from the airstream, and the second filter stage receiving the airstream from the first filter stage and including a rigid cylindrical filter having a pair of open ends and a cylindrical interior and an exterior upon which dust and debris are removed from the airstream, with the filter module having a debris collection surface and a movable flap for retaining dust and debris removed from airstream at the first filter stage and second filter stage upon the collection surface, said movable flap being held closed by way of vacuum action from the exhaust fan and being released to swing open when the hopper is in the debris dump position, with the collection surface of the two filter stages being separated by a wall allowing a pressure differential to exist thereacross, and said filter module including a filter shaking mechanism having an electric motor positioned substantially within the cylindrical interior of the cylindrical filter and with at least one eccentric weight being attached to a motor shaft positioned within the interior of the cylindrical filter, with said electric motor being secured to a plate sealing one of said open ends of the cylindrical filter, and with said airstream passing out of the other of said of open ends of the cylindrical filter, and a housing adapted to seal against said upper opening of the debris hopper, and wherein said exhaust conduit is removed from air communication with the debris hopper when the debris hopper is in said debris dump position.