Abstract:
Embodiments include a surface maintenance machine, comprising a maintenance tool chamber comprising a first side, a second side, a third side and a fourth side. A rotary broom is housed in the maintenance tool chamber and substantially enclosed by the first, second, third and fourth sides thereof. The rotary broom sweeps particulate from the surface. A vacuum system generates vacuum for drawing particulate swept by the rotary broom. The vacuum system is positioned proximal to the first side. A skirt assembly extends substantially around the second, third and fourth sides of the maintenance tool chamber. The skirt assembly has a vacuum passage defined therein and in fluid communication with the vacuum system to direct air flow into the vacuum passage, thereby drawing particulate into the vacuum passage and preventing particulate accumulation at portions of the second, third and fourth sides that are distal to the vacuum system.

Description:
RELATED APPLICATION 
       [0001]    This application claims the benefit of U.S. Provisional Patent Application No. 62/290,011 filed Feb. 2, 2016, the entire contents of which is hereby incorporated by reference. 
       BACKGROUND 
       [0002]    Surface maintenance machines include vehicles and devices that can be self-powered, towed, or pushed, and/or manually powered. Surface maintenance machines commonly include a cleaning head having one or more maintenance tools (e.g., a rotating drum brush) operated by one or more motors. Each maintenance tool is configured to perform a desired treating operation on the surface. For example, in cases where the surface maintenance machine is a surface maintenance machine, one or more brushes sweep dirt and debris from a surface and throw loose debris into a hopper. The brush may be housed in a maintenance tool chamber in such cases. 
         [0003]    Typically during the operation of a sweeper, sweeping tools that move and direct debris and generate particulate may cause adverse air currents that can be hard to control. In such cases, a vacuum system directing airflow in a predetermined direction can be commonly used to control the particulate and adverse air currents that are generated during the sweeping process. The surface maintenance machine may also include skirt assemblies comprising a single row of skirts on the front, lateral sides and/or rear of the machine, under which vacuum may be generated by the vacuum system thereby drawing particulate toward the hopper. As a result of the presence of the front skirt, large debris may not get drawn inward toward the machine during the sweeping process, and may be thrown off (sometimes referred to as “plowing.”) 
       SUMMARY 
       [0004]    In one example, the present disclosure includes a surface maintenance machine, comprising a body, comprising a transverse centerline. The surface maintenance machine can include a pair of brooms comprising a front broom and a rear broom. The pair of brooms can be positioned generally to the front of the transverse centerline when the machine is moving in a generally forward direction. The pair of brooms can rotate in a direction opposite to each other, whereby the counter-rotation of the pair of brooms can sweep the surface, including sweeping particulate located on the floor. The surface maintenance machine can include a vacuum system adapted to generate vacuum for drawing the particulate swept by the pair of brooms. An inlet of the vacuum system can be positioned generally to the front of the transverse centerline. The surface maintenance machine can include a chute positioned above the pair of counter-rotating brooms that can be fluidly coupled to the vacuum system. The pair of brooms can be exposed on the front to a portion of the surface such that each of the pair of brooms rotates in opposite directions to direct particulate present on the portion of the surface in front of the pair of brooms toward the chute. 
         [0005]    In another example, the pair of brooms housed in a sweep chamber can draw particulate on the surface to the front of the pair of brooms inwardly toward the surface maintenance machine. In such examples, the surface maintenance machine can include a skirt assembly generally surrounding the pair of brooms forms a vacuum passage to fluidly isolate the sweep chamber from an exterior of the surface maintenance machine. The skirt assembly can include side skirts and a rear skirt. The rear skirt can be positioned to the rear of the pair of brooms when the machine is moving in a generally forward direction. The skirt assembly may not surround the pair of brooms on the front of the pair of brooms so that particulate on the surface to the front of the pair of brooms is drawn toward the surface maintenance machine due to air currents generated during the rotation of the pair of brooms. 
         [0006]    In another example, each of the pair of brooms can rotate in a direction opposite to each other, such the rotation of a first broom can draw particulate inwardly toward the surface maintenance machine, and the rotation of the a second broom can lift particulate toward a hopper housed thereabove. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0007]    The following drawings are illustrative of particular embodiments of the present invention and therefore do not limit the scope of the invention. The drawings are not necessarily to scale (unless so stated) and are intended for use in conjunction with the explanations in the following detailed description. Embodiments of the invention will hereinafter be described in conjunction with the appended drawings, wherein like numerals denote like elements. 
           [0008]      FIG. 1  is a perspective view of a surface maintenance machine according to an embodiment; 
           [0009]      FIG. 2  is a front perspective view of the surface maintenance machine shown in  FIG. 1 ; 
           [0010]      FIG. 3  is a side perspective view of the surface maintenance machine shown in  FIG. 1 ; 
           [0011]      FIG. 4  is a cross-sectional side view of the surface maintenance machine shown in  FIG. 1  with the brooms in the transport position; 
           [0012]      FIG. 5  is a cross-sectional side view of the surface maintenance machine shown in  FIG. 1  with the brooms in the operating position; 
           [0013]      FIG. 6A  is a left side view illustrating portions of a particulate collection system according to an embodiment; 
           [0014]      FIG. 6B  is a right side view illustrating portions of the particulate collection system shown in  FIG. 6A ; 
           [0015]      FIG. 7  is a close-up view of a portion of a skirt assembly according to an embodiment; and 
           [0016]      FIG. 8  is an exploded perspective view of the skirt assembly shown in  FIG. 7 . 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    The following detailed description is exemplary in nature and is not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the following description provides some practical illustrations for implementing exemplary embodiments of the present invention. Examples of constructions, materials, dimensions, and manufacturing processes are provided for selected elements, and all other elements employ that which is known to those of ordinary skill in the field of the invention. Those skilled in the art will recognize that many of the noted examples have a variety of suitable alternatives. 
         [0018]      FIG. 1  is a perspective view of an exemplary surface maintenance machine  100 . In the illustrated embodiment shown in  FIG. 1 , the surface maintenance machine  100  is a ride-on machine  100  used to treat hard surfaces. In other embodiments, the surface maintenance machine  100  can be a walk-behind machine  100  or a towed-behind machine  100 , such as the surface maintenance machine  100  described in U.S. Pat. No. 8,584,294 assigned to Tennant Company of Minneapolis, Minn., the disclosure of each of which is hereby incorporated by reference in its entirety. The surface maintenance machine  100  can perform maintenance tasks such as sweeping (e.g., removing dust, debris or other particulate from the surface  152 ). As referred to herein, particulate may refer to dust as well as large and loose debris). In some cases, the machine  100  is a mechanical sweeper configured for mechanically moving particulate from the surface  152 . Alternatively, the machine  100  can be a combination sweeper-scrubber, or a burnisher. Other operations such as scrubbing, polishing (burnishing) a surface  152  are also contemplated. The surface  152  can be a surface  152 , pavement, road surface  152  and the like. 
         [0019]    Embodiments of the surface maintenance machine  100  include components that are supported on a mobile body  102 . As best seen in  FIG. 1 , the mobile body  102  comprises a frame  104  supported on wheels  106  for travel over a surface  152 , on which a surface  152  maintenance operation is to be performed. The mobile body  102  may include operator controls (not shown) and a steering control such as a steering wheel  108 . The surface maintenance machine  100  can be powered by an on-board power source such as one or more batteries, a fuel-cell, or an internal combustion engine (not shown). The power source can be proximate the front of the surface maintenance machine  100 , or it may instead be located elsewhere, such as within the interior of the surface maintenance machine  100 , supported within the frame  104 , and/or proximate the rear of the surface maintenance machine  100 . Alternatively, the surface maintenance machine  100  can be powered by an external electrical source (e.g., a power generator) via an electrical outlet. The interior of the surface maintenance machine  100  can include electrical connections (not shown) for transmission and control of various components. 
         [0020]    The machine  100  can include a maintenance tool for performing one or more cleaning tasks. For instance, the maintenance tool can perform sweeping, scrubbing, polishing/burnishing, striping, dry and wet vacuuming, and the like. Many different types of maintenance tools are used to perform such cleaning operations on the surface  152 . These include sweeping, scrubbing brushes, polishing/burnishing and/or buffing pads. In the embodiments illustrated herein, the machine  100  is a surface maintenance machine  100  wherein the maintenance tool can be a pair of rotary brooms  110 ,  112 . Alternatively, the machine  100  can be a combination sweeper-scrubber in which case the machine  100  can include one or more scrub-brushes in addition to the brooms  110 ,  112 , or a burnisher in which case the machine  100  can include one or more burnishing/polishing pads. The brooms  110 ,  112  can extend from the underside of the machine  100  and can be supported by an elongated cleaning head (not shown). While not illustrated, the cleaning head can house other maintenance tools (e.g., side brooms, scrubbing brush, and burnishing/polishing pads). The cleaning head assembly can be attached to the body  102  of the machine  100  such that the cleaning head can be lowered to a operating position and raised to a transport position. The cleaning head assembly is connected to the machine  100  using any known mechanism, such as a suspension and lift mechanism such as those illustrated in U.S. Pat. No. 8,584,294 assigned to Tennant Company of Minneapolis, Minn., the disclosure of each of which is hereby incorporated by reference in its entirety. The rotary brooms  110 ,  112  can be releasably loaded to or unloaded from the surface maintenance machine  100 . 
         [0021]    While a pair of counter-rotating brooms  110 ,  112  is shown in  FIG. 2 , other maintenance tools can also be provided. In cases where the machine  100  is a combination sweeper-scrubber, or a burnisher, the maintenance tool chamber can hold other maintenance tools (e.g., a scrub brush, a burnishing pad and the like) raised and lowered by a cleaning head (not shown). Additionally, the machine  100  may also have side brushes  114  positioned laterally on the machine  100  to maintain a larger envelope of the surface  152 . 
         [0022]    Referring to  FIG. 2 , the rotary brooms  110 ,  112  extend from a bottom surface  152  of the body  102  of the machine  100  and are rotatable. The brooms  110 ,  112  can be driven by a driver (e.g., a motor, not shown). The rotation of the rotary brooms  110 ,  112  generates air currents within a sweep chamber  115 . As the brooms  110 ,  112  rotate, particulate are picked up (e.g., swept) from the floor and acted upon by a vacuum system  150  as will be described below. The brooms  110 ,  112  are counter-rotating, and rotate in opposite directions such that the air currents generated by one broom are countered by those generated by the other broom. Such embodiments can be beneficial for ideally directing all the particulate into a hopper  144 . In sweeping systems known in the art, air currents due to broom rotation can have an associated positive pressure therewith such that particulate may sometimes be thrown off towards the outside of the machine  100 . However, the counter-rotating brooms  110 ,  112  reduce such throwing off of particulate, whereby air currents due to one broom are countered by air currents due to the other broom to draw and pick up particulate. In addition to counteracting the air currents due to rotation of the rear broom  112 , the front broom  110  may perform other functions typically performed by a front skirt, thereby eliminating the need for a front skirt. For example, the front broom  110  may fluidly isolate the vacuum generated by the vacuum system  150  from the exterior of the machine, and thereby facilitate maintaining and containing the vacuum over a desired area (e.g., the sweep chamber  115 ) and to direct particulate toward the hopper  144 . 
         [0023]    With continued reference to  FIG. 2 , as mentioned previously, the maintenance tools include a pair of brooms  110 ,  112  positioned generally to the front of the transverse centerline  120  when the machine  100  is moving in a generally forward direct. The front broom  110  can be a leading broom and the rear broom  112  can be a trailing broom when the machine is moving in a generally forward direction  153 , and the rear broom  112  can be the leading broom and the front broom  110  can be the trailing broom when the machine is moving in a generally rearward direction (opposite to the forward direction  153 ). As referred to herein, the terms “front”, “sides”, “rear”, “upwards”, “downward”, “inward”, “outward” “rearward” and “forward” take their ordinary meaning as is apparent to one skilled in the art. The brooms  110 ,  112  are movable between a transport position (illustrated in  FIGS. 1-4 ) and an operating position (illustrated in  FIGS. 5-7 ). In the transport position, the brooms  110 ,  112  are lifted above the surface  152  (e.g., relative to the vertical position of the wheels  106  of the machine  100 ) such that they do not contact the surface  152  on which the machine  100  is being operated. Conversely, in the operating position, the brooms  110 ,  112  are lowered toward the surface  152  and are generally in contact with the surface  152 . In some cases, the machine  100  may travel on uneven surfaces. In such cases, the brooms  110 ,  112  may or may not be in contact with the surface  152 . Optionally, such embodiments may include a suspension mechanism (not shown) to maintain the brooms  110 ,  112  generally in contact with the surface  152  when passing over undulations thereon. 
         [0024]    Referring now to  FIGS. 2 and 3 , the brooms  110 ,  112  comprise a front broom  110  and a rear broom  112  that are rotatable in a direction opposite to each other. As will be described further below, the brooms  110 ,  112  are generally exposed on the front  120  to a portion of the surface  152  when the machine  100  is moving in a generally forward direction  153 . Advantageously, the front broom  110  performs functions such as containing vacuum within the sweep chamber  115 . In such cases, advantageously, the brooms rotate in opposite directions  122 ,  124  to direct particulate present on the portion of the surface  152  in front of the pair of brooms  110 ,  112  toward a particulate collection system  140  (best seen in  FIGS. 4-6B ). In such cases, each broom can be powered independently by a motive source (e.g., a motor) adapted to rotate each broom in preferred direction such that the brooms  110 ,  112  may rotate generally opposite to each other. Moreover, the speed of rotation of each broom can be independently controlled by the motive source of the respective brooms. 
         [0025]    Referring now to  FIG. 4 , the front broom  110  rotates in a direction  122  toward the transverse centerline  120 , and the rear broom  112  rotates in a direction  124  away from the transverse centerline  120 . For instance, in the embodiments contemplated herein, the front broom  110  rotates in generally the same direction as the rotation of the wheels  106 , such that the brooms sweep particulate generally in the same direction as the direction of travel of the machine. More generally, the rotation of the leading broom can be generally in the same direction as the rotation of the wheel  106  and the rotation of the trailing broom can be opposite to the rotation of the leading broom. For instance, referring to  FIG. 4 , if the machine moves along the forward direction  106 , the wheels move in a generally clockwise direction. The leading broom in such a case is the front broom  110 , and it can rotate in the same direction (clockwise) as the rotation of the wheels  106 . 
         [0026]    As is apparent to one skilled in the art, brooms  110 ,  112  generate air currents in a direction generally tangential to their rotation. Advantageously, in certain embodiments disclosed herein, such air currents facilitate collection of particulate from the surface  152  and direct them into a particulate collection system  140 . For instance, referring to  FIG. 5 , each of the pair of brooms  110 ,  112  generates air currents associated with their rotation generally tangentially to the direction of their rotation. For example, the air currents of the front broom  110  near a front portion of the front broom  110  can be directed downward and inward (e.g., as shown by arrow  126 ) toward the machine  100 . Similarly, the air currents generated due to the rotation of the rear broom  112  is in a direction that counters the effects of the air currents generated by the front broom  110  to facilitate lifting of the particulate toward the particulate collection system  140 . For instance, the air currents generated near a front portion of the rear broom  112  can be directed upward (e.g., as shown by arrow  128 ). Thus, the air currents generated by the pair of brooms  110 ,  112  cooperatively collect particulate from the front of the machine  100  and direct it toward the particulate collection system  140 . 
         [0027]    With continued reference to  FIG. 4 , the front and rear brooms  110 ,  112  can be spaced such that they facilitate optimal particulate collection. For instance, in the illustrated embodiment, the front and rear brooms  110 ,  112  have a gap  130  therebetween. The gap  130  can be configured to a suitable value to facilitate effective collection of particulate. For example, the gap  130  between the front and rear brooms  110 ,  112  can be between about 0.125 inches. Other distances are also contemplated, and the values provided herein should not be construed as limiting. Alternatively, the brooms  110 ,  112  can be arranged such that the tips of the bristles of the front and rear brooms  110 ,  112  contact each other. 
         [0028]    Referring now to  FIG. 5 , the machine  100  can include a particulate collection system  140 . The particulate collection system  140  can comprise a chute  142 , a hopper  144  (best shown in  FIG. 5 ) and a vacuum system  150  (best shown in  FIGS. 6A and 6B ). In the illustrated embodiment, the hopper  144  is positioned generally to the front of and above a rotational axis  151  (shown by a point) of the pair of brooms  110 ,  112  when the machine  100  is moving in a generally forward direction  153 . For instance, the hopper  144  is positioned to the front of the front broom  110 , with at least one wall  154  of the hopper  144  contacting the chute  142 . In the illustrated embodiment, as described previously, the rotation of the pair of brooms  110 ,  112  facilitates pick up of particulate from the surface  152  and direct it toward the hopper  144 . Alternatively, the hopper  144  can be positioned toward the back of the machine  100 , when the machine  100  is moving in a generally forward direction  153 . The hopper  144  shown in  FIG. 6A  comprises a plenum  160  and associated plenum panels  162 . The plenum  160  can be coupled to and/or support one or more components of the vacuum system  150  shown in  FIG. 6A . 
         [0029]    The particulate collection system  140  comprises a vacuum system  150  best illustrated in  FIGS. 6A and 6B . The vacuum system  150  can comprise a vacuum source  164 , such as a fan housed in a fan housing  166 . In some cases, the vacuum system  150  can include a filtration system (hidden, housed on the wall  168 ) including a filter and other components which provide for support and function thereof. One example of a filtration system is described in the commonly-assigned U.S. Pat. No. 8,099,828, the disclosure of which is hereby incorporated by reference. The vacuum system  150  generates vacuum for drawing particulate swept by the pair of brooms  110 ,  112 . In some such examples, an inlet  170  of the vacuum system  150  can be positioned generally to the front of the transverse centerline  120  (e.g., in front of and above the chute  142 ). Such cases facilitate an air flow as illustrated by arrows  174  in  FIG. 6A , whereby particulate is drawn toward and settled in the hopper  144  and the air flow passes through the filtration system and leaves through the exhaust port  190  shown in  FIG. 6B . 
         [0030]    Referring back to  FIG. 6A , the particulate collection system  140  comprises a chute  142  positioned above the pair of counter-rotating brooms  110 ,  112 . As described above, the chute  142  is fluidly coupled to the vacuum system  150 , such that air flow drawn by the vacuum fan passes from between the brooms  110 ,  112  and into the chute  142 , facilitating particulate pick-up. Particulate and air flow leaving the chute  142  enters the hopper  144 , wherein the particulate settles in the hopper  144 . As seen in  FIG. 6A , the chute  142  is defined by a front wrap  178  and a rear wrap  180 . The front wrap  178  abuts against a lip  182  of a rear plenum  160  panel of the hopper  144 . Each of the front wrap  178  and rear wrap  180  contacts a broom. For example, the front wrap  178  contacts the front broom  110  and the rear wrap  180  contacts the rear broom  112 . The point of contact in some cases can be referred to as a “pick-off point”  184 ,  188 . In the operating position illustrated in  FIG. 6A , the pick-off points can be arranged such that the front and rear wraps form a passage for particulate to be directed from between the pair of brooms  110 ,  112  and into the hopper  144 . Thus, the rear wrap  180  of the chute  142  is positioned further forward in the transport position relative to its position in the operating position (seen in  FIG. 4 ). For example, as seen in the close-up view of  FIG. 7 , the pick-off points can be approximately at the one o&#39;clock position on the brooms  110 ,  112 , thereby forming a passage to direct particulate into the hopper  144 . However, other locations of the pick-off points on the broom to facilitate optimal collection of particulate are also contemplated. Conversely in the transport position seen in  FIG. 4 , the point of contact of the rear wrap  180  on the rear broom  112  is approximately at the two o′clock position and is further forward of the pick-off point at the operating position illustrated in  FIGS. 5 and 7 . Such embodiments facilitate the front and rear wraps of the chute  142  to be configured to allow optimal collection of particulate. 
         [0031]    Referring now to  FIGS. 7 and 8 , the surface maintenance machine  100  comprises a skirt assembly  200 . The skirt assembly  200  can be a separate component, or be integral with the frame  104  of the machine  100 . The skirt assembly  200  comprises a rear skirt  216  and side skirts  218  that generally surround the pair of brooms  110 ,  112 . As best seen in  FIG. 8 , the brooms  110 ,  112  are enclosed in a sweep chamber  115 . The skirt assembly  200  generally surrounds the brooms  110 ,  112  on the rear  210  and the sides  212 ,  214  to form a vacuum passage to fluidly isolate the rear  210  and sides  212 ,  214  of the sweep chamber  115  from an exterior of the surface maintenance machine  100 . As seem in  FIGS. 7 and 8 , the rear skirt  216  is positioned to the rear of the pair of brooms  110 ,  112  when the machine  100  is moving in a generally forward direction  153 . The rear skirt  216  is positioned farther away from and opposite to the inlet  170  of the vacuum system  150 . The skirt assembly  200  according to some such embodiments does not surround the pair of brooms  110 ,  112  on the front so as to facilitate particulate on the surface  152  to the front of the pair of brooms  110 ,  112  being drawn toward the surface maintenance machine  100  due to air currents generated during the rotation of the pair of brooms  110 ,  112 . 
         [0032]    The skirt assembly  200  does not surround the front of the front broom  110 , such that the front broom  110  is substantially unobstructed in the forward direction  153  by any portion of the surface maintenance machine  100 . For instance, at least a bottom half of the front broom  110  is unobstructed in the forward direction  153  by any portion of the surface maintenance machine  100 . Referring to  FIG. 7 , for instance, it can be seen that the front broom  110  extends a broom height  230  above the surface  152  when operating on the surface  152 . In such cases, the skirt assembly  200  seals the sides  212 ,  214  and the rear  210  of the sweep chamber  115 , while having the front of the front broom  110  exposed such that at least one-half of the front broom  110  is unobstructed in the forward direction  153  by any portion of the surface maintenance machine  100 . As used herein, the term “unobstructed” refers to being unobstructed to drawing particulate. 
         [0033]    The skirts can be mounted from components of the frame  104  of the machine  100  from a bottom portion  240  of the machine  100 . For instance, as shown in  FIG. 8 , the skirts can be mounted on a retainer bracket by fasteners  242 . In some cases best seen in  FIGS. 7 and 8 , the skirts are positioned such that they seal the rear  210  and sides  212 ,  214  of the sweep chamber  115 . In such cases, an edge  246  of each skirt can be spaced no greater than a predetermined ground clearance  250  from the surface  152  on which the surface maintenance machine  100  is positioned. Such embodiments facilitate the skirts to seal the sides  212 ,  214  and the rear  210  of the sweep chamber  115  and prevent dusting from happening on those portions. In some cases, the maximum permissible ground clearance can be about 0.05 inches and about 0.25 inches, and preferably about 0.125 inches. 
         [0034]    Prior surface  152  maintenance machines typically have a vacuum passage on all sides of the sweep chamber  115  such as front, rear and sides. However, such sweeping system design may not be able to pick up large debris and may wind up “plowing” debris rather than draw them into the particulate collection system  140 . Moreover, such large debris may damage the skirt on the front of the sweep chamber  115 , thereby leading to dusting because of reduced vacuum being maintained. The skirting as described herein reduces such adverse problems by having the front of the sweep chamber  115  be exposed to particulate. Advantageously, the present disclosure provides a pair of counter-rotating brooms  110 ,  112  that eliminate the need for a front skirt, and instead, rely on cooperative air currents due to the opposed rotation of the brooms  110 ,  112  to draw and lift particulate into the hopper  144 . 
         [0035]    In operation, the surface maintenance machine  100  is operated on a surface  152  to sweep particulate therefrom. When the vacuum system  150  is engaged, dirt and debris are directed from the surface  152  into the chute  142  due to air currents generated by counter-rotation of the broom. The rotation of the front broom  110  may draw the particulate inward toward the machine  100 , and the rotation of the front and/or the rear broom  112  may lift the particulate into the chute  142  positioned thereabove. Vacuumized airflow generated by the vacuum system  150  may further draw the particulate into the hopper  144 . The skirt assembly  200  substantially isolates the sweep chamber  115  on the rear  210  and sides  212 ,  214 . 
         [0036]    Advantages of embodiments disclosed herein include elimination of front skirting. As a result, routing of airflow is improved. Improved routing of airflow also allows larger particulate than is conventional to be drawn and lifted, rather than plowed as was conventional with several known sweeping machines. 
         [0037]    Thus, embodiments of the surface maintenance machine  100  with a skirt assembly  200  to allow particulate pick up are disclosed. The disclosed embodiments are presented for purposes of illustration and not limitation and other embodiments of the invention are possible. One skilled in the art will appreciate that various changes, adaptations, and modifications may be made without departing from the spirit of the invention.