Integral Vacuum Fan Housing

Abstract

A filter box for a surface maintenance machine incorporating aspects of a fan housing. In one example, a filter box for a sweeping machine is provided with an impeller fan housing beneath a cylindrical filter. Operation of the impeller fan draws air from a debris hopper, through the cylindrical filter, and through an expansion chamber defined by a scroll conduit prior to outlet to atmosphere.

1 . A filter system for a mobile surface maintenance machine comprising:
 a hopper adapted to receive debris from a sweeping brush; and   a filter box carrying at least one filter and a vacuum fan impeller and being externally provided relative to the hopper, said filter box being in air communication with the hopper so as to support a vacuum-based airflow through the hopper and said at least one filter.   
     
     
         2 . The system of  claim 1  wherein the vacuum fan impeller is a closed impeller. 
     
     
         3 . The system of  claim 1  wherein the filter box defines a portion of an expansion chamber which receives air from the closed impeller during machine operation. 
     
     
         4 . The system of  claim 3  wherein the expansion chamber is defined by an axially expanding scroll. 
     
     
         5 . The system of  claim 4  wherein the expansion chamber is center by an open conduit between the filter interior and the fan impeller center. 
     
     
         6 . The system of  claim 2  further comprising a filter shaking mechanism to dislodge dust and debris from a surface of the filter, said dust and debris accumulating on a bottom of the filter box. 
     
     
         7 . The system of  claim 3  wherein the dust and debris of the filter box are selectively passed through a conduit into the hopper. 
     
     
         8 . The system of  claim 4  wherein a movable flap, biased by operation of the vacuum fan, controls the flow of dust and debris through the conduit and into the hopper. 
     
     
         9 . A filter housing comprising:
 a molded plastic housing having an interior volume into which a filter is disposed and defining at least a portion of a vacuum expansion chamber.   
     
     
         10 . A filter comprising:
 an integrated filter box containing a filter, said filter box being external to a hopper of a sweeping machine;   a filter shaking mechanism attached to the filter box; and   an impeller attached to the filter box.   
     
     
         11 . The filter of  claim 10  wherein the filter box defines a portion of an expansion chamber surrounding at least a portion of the impeller. 
     
     
         12 . The filter of  claim 11  wherein the expansion chamber maintains a generally constant radial distance from a center. 
     
     
         13 . The filter of  claim 11  wherein the expansion chamber expands axially around the impeller blade. 
     
     
         14 . The filter of  claim 10  wherein the filter box includes a conduit between the interior of the filter and the impeller. 
     
     
         15 . The filter of  claim 10  further comprising a selectively operable duct for passing dislodged debris from the filter box into the hopper. 
     
     
         16 . A filter comprising:
 a housing having an air inlet and a filtered air outlet;   a filter within the housing;   a vacuum fan connected to the housing and drawing air from the inlet toward the outlet;   an expansion chamber at least partially molded into the housing, said expansion chamber surrounding at least a part of the vacuum fan.   
     
     
         17 . A surface maintenance machine comprising:
 a mobile chassis having a sweeping brush;   a hopper receiving debris thrown by the sweeping brush;   a filter box external to the hopper and being in selective air communication therewith, said filter box carrying a filter, a shaking mechanism and a vacuum impeller.   
     
     
         18 . The machine of  claim 17  wherein the impeller is driven by a hydraulic motor. 
     
     
         19 . A surface maintenance machine comprising:
 an integrated molded filter box external to a main debris hopper and carrying a filter and defining at least a portion of a curved expansion chamber proximate to a driven air impeller.   
     
     
         20 . The machine of  claim 19  wherein the expansion chamber is generally circular.