Walk behind floor maintenance machine
TECHNICAL FIELD 
     The present invention relates to surface maintenance equipment and more particularly to walk behind surface maintenance equipment utilizing a fan for drawing a vacuum airstream through such equipment. The present invention further relates to such equipment including a filter for removing dust from such stream prior to passage through the fan. 
     BACKGROUND OF THE INVENTION 
     A wide variety of machines have been available in the past for use in maintenance of surfaces such as floors, parking lots, and the like. Such maintenance machines include self-propelled riding machines as well as self-propelled walk behind machines. Typically, both types of machines have utilized fans or pumps to draw a vacuum in the brush housing thereby minimizing dusting around the brush housing. Filters have generally been provided to minimize the amount of dust that passes through the fan. In the absence of such filters, the dust causes unnecessary wear and degradation of the fan and pollutes the atmosphere. A long-standing problem has been the accumulation of dust on the filter. This tends to block the filter and create a substantial pressure differential between the upstream side of the filter and the downstream side of the filter, thus reducing the efficiency of the equipment. A manual or mechanical system is generally incorporated to clean the filter at regular intervals to enable the machine to continue to function without frequent replacement of the filter. 
     Walk behind units desirably are of a small size and thus large powered hopper dumping elements have not been provided. Some walk behind units have included a hopper that may be manually lifted by the operator, carried to a suitable location and dumped. Such units in the past have, of necessity, spaced the filter from the hopper to permit removal of the hopper. Such spacing, of course, does not provide for a minimized size of unit. Further, such spacing does not provide for return of the dust from the filter to the hopper. Instead, such units have generally included a secondary hopper or drawer into which accumulated dust is dropped. 
     SUMMARY OF THE PRESENT INVENTION 
     The present invention provides a walk behind, power driven floor maintenance machine including a hopper, a cylindrical driven brush for moving soilage into the hopper, a vacuum fan for drawing an airstream through the hopper and a filter for removing dust particles from the airstream before exhausting to the atmosphere. The present machine has a filter disposed in a filter housing. The filter housing is box-like in shape and is disposed immediately above the hopper. The filter housing is sloped downwardly and forwardly to communicate at its forward end with the hopper. The filter housing is hingedly secured at its upper end to the body of the floor maintenance machine and is freely but sealingly engaged at its lower end with the hopper. The filter housing may be vibrated to shake collected dust from the filter and to convey such dust along the sloped lower wall of the housing into the hopper. Thus the lower wall serves as a vibratory conveyor. The filter housing may be pivoted upwardly out of the way when one desires to remove the hopper such as for dumping. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. I is a perspective view from the left front of the present invention; 
     FIG. II is a side elevational view of the embodiment of FIG. I; 
     FIG. III is a perspective view of the present invention with the filter housing pivoted to its uppermost position; 
     FIG. IV shows a lower front portion of the invention including a hopper support member; 
     FIGS. V and VI show the upper side supports of the hopper; 
     FIG. VII shows the present invention with the filter housing pivoted to its uppermost position and the hopper lifted out of its supported position; 
     FIG. VIII shows the present invention with the hopper pivoted to a dumping position; 
     FIG. IX shows a side view of the present invention with housing portions removed to expose underlying structure; 
     FIG. X is an exploded view of the filter assembly on the present floor maintenance machine. 
     FIG. XI is a cross sectional view of the filter assembly; and 
     FIG. XII is a schematic view of an alternate embodiment. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present invention, as illustrated in FIGS. I-XI relates to surface maintenance equipment and more specifically to equipment commonly referred to as sweepers. The sweeper 10 includes a body portion 11 supported on a plurality of wheels 12. The body 11 has controls such as the steering bar 13 and shifting lever 14. A side brush 16 may be disposed at the forward portion of sweeper 10. The sweeper 10 of course includes a housing which overlies the internal structural portions of the machine. The present machine 10 has a rotatably driven cylindrical brush 17 which may be encased within a suitable dust housing 18 which minimizes dusting around the machine. 
     The present invention is illustrated in FIG. III with various housing portions removed to disclose the underlying structure, including hopper 19 and filter housing 21. As shown in FIGS. III, IV and VII, the hopper includes a bottom wall 22, a pair of sidewalls 23 and 24, an upper wall 26 and a front wall 27. The bottom wall 22 may include a ramp 28, for example, of a resilient elastomeric material. If desired, the hopper 19 may be partially enclosed to the rear by wall 25 thus providing an opening 31 for receipt of swept material. The upper wall 26 has a rectangular opening 32 therein for purposes hereinafter described. A pair of upwardly extending arms 33 and 34 may be mounted on the upper wall 26. The arms 33 and 34 are mirror images of each other; however, otherwise they may be identical in structure. Arm 33, for example, may include an upwardly extending portion 33a and a rearwardly extending portion 33b. Portion 33b has an outwardly extending stub shaft 36 which assists in supporting the hopper with respect to the body 11. Arm 34 is similarly constructed. A pair of L-shaped bars 37 and 38 serve as suitable handles for lifting and carrying the hopper 19. Bar 37, for example, may be welded at one end to upper wall 26 and secured by a bolt 39 at the other end. The hopper 19 has a lever and grip 41 rotatably secured at one end to the bar 37. The lever and grip 41 may be of a length slightly less than the width of the hopper 19 to permit stowing. The lever 41 may be rotated from the position shown in FIG. VII to the position shown in FIG. VIII. A small angle member or lock 42 secures handle 41 when rotated to the position shown in FIG. VIII. 
     The hopper sidewalls 23 and 24 each have an outwardly extending stub shaft 43. The stub shafts 36 and 43 serve to support the hopper 19 with respect to the body 11. The stub shaft 36 is located rearwardly of the center of mass of hopper 19 whereas the stub shaft 43 is located slightly forwardly of the center mass. The body 11 has a forwardly extending arm 44 adjacent each side for supporting engagement with the stub shaft 43. The arm 44 as illustrated in FIG. X may have an upwardly facing recess in which the stub shaft 43 is held. The body 11 (FIGS. V and VI) has a pair of side members 46, one on either side, on which is located a channel-like support 45 for reception of the stub shaft 36. 
     The filter assembly 21 as illustrated in FIGS. III, VII and IX, includes a housing 47 having a lower portion 48 and cover 59. Housing 47 is supported with respect to the body 11 by hinges 49 (FIG. VII) and by stop 50. A panel filter 51 (FIG. X) is supported in the housing 47 and sealed with respect to such housing such that any air passing through the housing 47 must pass through the filter. The filter thus divides the housing into a dusty air zone beneath the filter and a clean air zone above the filter. The housing 47 (FIGS. VII, VIII and X) has an inlet 52 with a suitable resilient seal 53 therearound. The inlet 52 mates with hopper opening 32 to receive air from the hopper. The housing 47 (FIGS. III and X) further includes an outlet 54 which communicates with a vacuum fan 56. The outlet 54 may include a short tube 57 which slides into a rubber boot 58 when the filter housing is in the lowered operating position, and yet slips out of such boot when the housing is raised, as illustrated in FIG. III. The filter housing 47 has a cover portion 59 which may be removed by the removal of screws 61 (FIGS. VII and X) from the threaded openings 62 in the housing support brackets 63. Panel filter 51 may be then lifted out and removed. 
     Although a specific embodiment of the present invention has been disclosed, it is to be recognized that a wide variety of modifications may be made within the scope of the present invention. For example, the present invention is illustrated using a panel filter however other types of filters may be used such as bag filters, canister filters and the like. Further, the tube 57 and boot 58 may be replaced with an accordion-type tube which is secured at one end to a fan duct and secured at the other end to the filter housing 47. 
     In a preferred embodiment of the present invention (FIG. III), an electrically powered eccentric weight device 64 is provided to vibrate the entire housing 47 and panel filter 51. Since the device 64 is located outside the filter housing 47 it is protected from the abrasive, dusty environment of such housing and thus has an extended life. In the absence of such a vibrating device, the housing and filter may be vibrated by merely striking the housing with one&#39;s fist to dislodge dust from the filter. The lower wall 48a of housing 47 may slope downwardly and may act as a vibratory conveyor to move the dislodged dust to the hopper. 
     OPERATION OF THE INVENTION 
     Although operation of the present invention would be apparent from the above description, it will be further described hereinafter to provide a more complete understanding of the advantages of the present invention. 
     In general operation, the present invention has many aspects which are common to most walk behind sweepers and further has aspects and advantages which are totally new. As with many walk behind sweepers in the past, the present sweeper is powered by any suitable power source, such as an electric motor or a gasoline powered engine. The power source drives the wheels 12 and the brushes 16 and 17. The brush 16 serves to sweep dirt and debris from the side of the sweeper path into the center portion where the main brush 17 picks up the dirt and debris, sweeping it into the hopper 19. The dirt and debris enters the hopper opening 31 and generally is retained therein. A vacuum fan 56 serves to draw an airstream through the hopper 19 moving light debris forwardly. The filter assembly 21 serves to remove dust-laden air from the airstream, thus protecting the fan motor 56 from abrasion. This also protects the operator from breathing dust-laden air. The panel filter 51 serves to trap such dust. During normal operation, the filter assembly 21 engages at its lower end the hopper 19 with the opening 52 of assembly 2 communicating with the opening 32 of hopper 19. The weight of the filter assembly 21 is supported on stop 50. The resilient seal 53 prevents entrance of ambient air, thus requiring all airstream to pass through the hopper. One may activate the eccentric vibrator 64 periodically to shake the dust collected from panel filter 51. The lower wall of the filter housing 47 is also vibrated and the dust slides therealong to drop into the hopper 19. If one wishes to replace the panel filter 51, screws 61 are removed and the cover 59 is removed providing access to such filter. 
     When the operator desires to empty the hopper 19 of collected dirt and debris, the filter assembly 21 is pivoted upwardly as shown in FIG. III. To facilitate this operation, an air spring 60 may be provided to counterbalance the weight of such assembly. Alternatively, suitable releasable bracing may be provided. The operator may grasp the handles 37 and 38 and lift the hopper 19 from its position on sweeper 10. The hopper may be carried to a suitable dump area and emptied. Alternatively, if the operator merely wishes to dump the hopper 19 at the location of the sweeper 10, the handle 41 may be pivoted to the position shown in FIG. IV and the hopper elevated to the position shown in FIG. VIII with the hopper pivoting on the stub shaft 36. The pair of stub shaft supports 43 at each side of hopper 19 permit the hopper to rock over obstacles. For example, as an obstacle such as a can or brick moves beneath the rear portion of hopper 19 and resilient lip 28, the hopper 19 may pivot upwardly resting on shafts 43. 
     ALTERNATE EMBODIMENT 
     An alternate embodiment of the present invention, sweeper 110, is illustrated in FIG. XII. Sweeper 110 may be identical in structure except that sweeper 110 includes a power dump for the hopper 119. The power dump may be an electrically driven screw 141 which is mounted on sweeper body 111. The screw 141 acts to rotate hopper 119 in a clockwise direction as viewed in FIG. XII to an elevated dump position. The upper stub shafts 136 may be locked in channel 145 by a solenoid 146 but only during the dumping operation. The sweeper 110 of course has suitable controls for activating the solenoid 146 and the screw 141 for dumping. The sweeper 110 may include a lockout mechanism which prevents activation of screw 141 unless the operator has first raised the filter housing 121. The operator may, if desired, manually lift and carry the hopper 119 to a dump site.