Abstract:
A low-profile side squeegee assembly for surface maintenance vehicles, capable of cleaning under so-called “toe kicks”. In contrast with typical suspensions that are mounted directly above the center of the squeegee assembly, and are therefore too tall to fit under toe kicks, a low-profile suspension attaches at the ends of a squeegee assembly, and uses torsion springs to provide a downward force on the squeegee assembly. In order to counteract any potential twisting effects that might result from suspending the squeegee from the ends rather than the center, the squeegee assembly is mounted at an angle.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 60/550,884, filed Mar. 5, 2004. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is directed to surface cleaning equipment, and more particularly to a low profile side squeegee assembly for surface cleaning equipment. 
     2. Background 
     Surface maintenance vehicles and cleaning devices have a long history subject to gradual innovation and improvement toward improved and oftentimes automated performance in removing debris and contamination from floors. These vehicles and devices may be self-powered, towed, or pushed, and/or manually powered and may carry a human operator during cleaning operations. Such vehicles and devices include scrubbers, extractors, sweepers and vacuums, as well as combinations thereof, intended for cleaning, scrubbing, wiping and/or drying a portion of a substantially flat surface both indoors and outdoors. Many such vehicles and devices employ a combination of squeegee assemblies for wiping dry a floor which has been cleaned by application of a cleaning solution of water and a detergent in conjunction with scrubbing action of one or more moving brushes. The squeegee assemblies are generally placed in various locations on the vehicle, including the rear and the sides. 
     The vertical profile of the side squeegee assembly generally limits how close the vehicle can get to walls and other objects. Particularly troublesome are so-called “toe kicks”, which are typically present in where cabinetry or the like does not touch the floor, but has a recessed area to partially accommodate a persons foot (allowing one to stand close to the cabinet). They are also found in supermarkets to prevent damage from shopping carts to displays and freezer doors. A toe kick may have a vertical clearance beneath it of perhaps 100 mm, and the recess may extend from the wall by perhaps 100 mm. Generally, a surface maintenance vehicle is unable to clean under the toe kicks, requiring that floor underneath the toe kicks be swept and mopped manually by hand. In a large grocery store or warehouse, the additional cleaning step required by the toe kicks can be inconvenient, time-consuming and expensive. 
     The difficulty in accommodating toe kicks stems in part from the manner in which the side squeegee assembly is supported. Generally, the side squeegees are held in place by a four-bar suspension, which is usually mounted directly above the center of the squeegee blade. The suspension is typically spring-loaded using tension springs, and ensures that the squeegee blade maintains proper contact with the floor as the vehicle travels over any irregularities in the floor. In addition, the squeegee suspension ensures that the squeegee blade is also maintained in the proper angular orientation with respect to the floor, in order to optimize the effectiveness of the squeegee. Further, the squeegee suspension should be self-adjusting, to accommodate pad and brush wear. 
     Although an obvious modification might be to move the four-bar suspension from directly above the center of the squeegee blade, away from the sides and toward the center of the vehicle, leaving the squeegee blade protruding out the sides of the vehicle, it turns out to be ineffective, and a modified four-bar suspension performs poorly. 
     Accordingly, there exists a need for a side squeegee suspension with a limited height total, with a low profile extending out to a minimum distance, which conforms to different brush heights and pad thicknesses, which self-adjusts to accommodate pad and brush wear, which is protected from obstacles, which has a minimum gap between the squeegee blade assembly and the pad or brush, and which contains substantially all the cleaning solution within the range of straight forward travel to a 90-degree turn. 
     BRIEF SUMMARY OF THE INVENTION 
     The present embodiment is a device for maintaining a ground surface, comprising: a housing with a peripheral edge; a squeegee assembly; a plurality of torsion elements connected between said peripheral edge and said assembly, and configured to apply a downward biased force to maintain the squeegee assembly in contact with the ground. 
     A further embodiment is a device for maintaining a ground surface, comprising: a housing having a front, rear and side peripheral edges; at least one squeegee assembly having first and second longitudinal ends; and a plurality of connecting elements connecting said first and second ends to said housing, said connecting elements providing a bias force between said housing and said assembly to urge said assembly into contact with said surface. 
     A further embodiment is a device for maintaining a ground surface, comprising: a housing; and a squeegee assembly having a blade with an attachment edge and a ground contact edge, said ground contact edge being inclined inwardly toward said housing by virtue of either of bolts  48  being inclined relative to their mount, though the inclination is not visible in FIG  4 . 
     There are other features of the invention defined by the claims. This summary is for convenience of the reader in becoming familiar with the subject matter. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  is a perspective drawing of a nozzle housing of a surface maintenance vehicle, upon which two side squeegee assemblies are mounted. 
         FIG. 2  is a top view drawing of the nozzle housing of  FIG. 1   
         FIG. 3  is a bottom view drawing of the nozzle housing of  FIGS. 1 and 2 . 
         FIG. 4  is an exploded view drawing of a torsion spring assembly. 
         FIG. 5  is a perspective drawing of the torsion spring assembly of  FIG. 4 , assembled. 
         FIG. 6  is an end-on view drawing of a surface maintenance vehicle, showing the incline of the side squeegee assemblies. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows an exemplary nozzle housing  11  for a surface maintenance vehicle, equipped with an embodiment of a low profile side squeegee assembly. As drawn in  FIG. 1 , the front of the vehicle would be in the bottom right corner of the drawing, and the vehicle would travel from top-left to bottom-right. The floor is at the bottom of the page. The nozzle housing is generally pivotally attached to the frame of the vehicle, and is usually capable of being raised off the ground by an actuator, so that the squeegee blades do not damage the floor surface when the vehicle moves during a non-cleaning period. 
     In effect this embodiment show how the housing may be configured as two housings, an upper  111 , and lower  113 . The upper housing being joined at edge  114  to the lower and the lower having a peripheral edge  115  where the squeegee  24  is typically attached, thereby defining a space partially enclosed by the squeegee. 
     In order to clean under the toe kick of a cabinet, or the like, the lower housing must be able to clear the limited space defined between the ground the and the occluding object/cabinet. This is possible if the lower housing has an upper surface  117  whose distance from the ground is less than that of the defined space. Prior art devices could not accomplish this and, at the same time, provide a bias force of the squeegee on the ground because the mechanism for applying the bias force could not fit in the defined space within the lower housing, or in some other way it would create interference with that housing being able to clear the toe kick space and clean thereunder. 
       FIG. 2  shows the nozzle housing  11  in a top view, where the vehicle travels from left to right. A cleaning solution is delivered by tubing  21  to a pair of nozzles or brushes, which are driven by a pair of electric motors  22  but are not seen in  FIG. 2  because they lie directly beneath the nozzle housing  11 . The nozzles or brushes may be asymmetrically offset from each other, in order to optimize cleaning performance along the centerline of the vehicle. Optionally, more or fewer than two nozzles or brushes may be used. At the sides of the nozzle housing  11  are a pair of generally rigid squeegee holders  23 , each of which supports a generally flexible squeegee blade  24 . 
       FIG. 3  shows the nozzle housing  11  in a bottom view, where the vehicle travels from left to right. The nozzles or brushes  31  are clearly seen in this view. Each squeegee holder  23  and squeegee blade  24  is attached to the nozzle housing  11  by a pair of torsion spring assemblies  32 , preferably located at the front and rear edges of the squeegee holders  23 . 
     Note that the exemplary torsion spring assemblies  32  can be substituted with any other variants to provide a low-profile and downward force from the nozzle housing  11  to the squeegee holders  23 . For instance, a torsion bar can be biased to provide the biasing downward force For instance, a torsion bar or element (resilient element attached at its ends) can be substituted for the assembly  32  though it is not the preferred solution. 
     An exemplary torsion spring assembly  32  is shown in exploded view in  FIG. 4 . A torsion spring  41  surrounds and is anchored at one end by a notched mandrel  42 , although any suitable support and anchor for the torsion spring  41  may be used in place of a notched mandrel  42 , such as a spindle or supporting rod. The other end  43  of the torsion spring  41  is held in one of the slots in a slotted link  44 . The slotted link  44  may be preferably molded from a durable plastic material, such as polycarbonate, although other materials may be used, including metals. In addition to providing an anchor for the torsion spring  41 , the slots and other molded features shown in  FIG. 4  may also assist in maintaining a near-uniform wall thickness throughout the part, which helps ensure that the part cools without deforming after molding. Alternatively, the slots may be shaped as a series of attachment points, rather than shaped as slots. Between the notched mandrel  42  and the slotted link  44  may be a spacer washer  45 . A spacer tube  46  may be inserted into each hole  47  in the slotted link  44 , in order to reduce wear on the slotted link  44 , as well as relax the manufacturing tolerances of the slotted link  44 . An additional spacer washer  45  may contact the slotted link  44  from the side opposite the torsion spring  41 . A bolt  48  extends through the wall of the nozzle housing  11 , through the spacer washer  45 , through the spacer tube  46  located in a hole  47  in the slotted link  44 , through another spacer washer  45 , and screws into threads located inside the notched mandrel  42 . 
     Analogous to parts described in the previous paragraph, a bolt  48  extends through a spacer washer  45 , through a spacer tube  46  located in a hole  47  in the slotted link  44 , through another spacer washer  45 , and screws into threads located in the squeegee holder  23 . In  FIG. 4 , the leftmost line of parts attaches the slotted link  44  to the nozzle housing  11 , and the rightmost line of parts attaches the slotted link  44  to the squeegee holder  23 . 
     Once the parts in  FIG. 4  are assembled, the spring tension may be calibrated by adjusting the bolt  48  that attaches to the notched mandrel  42 . Furthermore, an additional spring tension adjustment may be made by inserting the other end  43  of the torsion spring  41  into a different slot in the slotted link  44 . 
       FIG. 5  shows an assembled torsion spring assembly, using the same part numbers as  FIG. 4 . It will be appreciated by one of ordinary skill in the art that the torsion spring assembly  32  shown in detail in  FIGS. 4 and 5  is merely exemplary, and may be suitably reconfigured to have different combinations of washers, nuts, bolts and anchoring methods. For instance, the torsion spring  41  may just as easily be located in the other hole  47  in the slotted link  44 , or on the opposite side of the slotted link  44 . 
     It should be noted that the embodiment of the torsion spring  41  in  FIGS. 4 and 5  generates a substantially tangential force with respect to its spiral core. It will be appreciated by one of ordinary skill in the art that various other embodiments of torsion springs may be used, each preferably with a low profile that allows the full spring assembly to be mounted near the periphery of the nozzle housing and relatively low to the ground. In addition, various other types of springs may be used, including extension, compression, and leaf springs. 
     In some known vehicles, the squeegee assembly is generally supported at the center, usually by a four-bar suspension. This center support distributes a downward force roughly uniformly over the squeegee blade, and as a result, the blade is well supported, and generally good performance is achieved. In order to provide a low-profile squeegee assembly that can fit under toe kicks, the linkages that provide a connection to the frame may be moved away from the center to the ends of the squeegee assembly. It is found that there potentially may be some undesirable twisting of the blade at the center, if it is supported only at the ends. It is also found that a slight inclination of the squeegee assemblies may counteract any potential twisting at the center, by changing the geometry at which the blade contacts the floor. 
     This inclination is difficult to see in  FIGS. 1-5 , so it is redrawn and greatly exaggerated in  FIG. 6 . A surface maintenance vehicle  61  is shown in an end-on view, with a frame  62 , wheels  63 , and two side squeegee assemblies  64 . The side squeegee assemblies  64  are mounted to the frame  62  at an angle, and are bent inward, as shown schematically in  FIG. 6 . In practice, the actual inclination  65  may be less than the +/−10 degrees drawn in the exaggerated  FIG. 6 . The inclination  65  may be built into the wall of the frame, the squeegee assembly, the slotted link that joins them, or any combination thereof. Although the inclination  65  is drawn in  FIG. 6  as a rotation strictly about the longitudinal axis of the vehicle, there may be an additional rotational component about an axis transverse to the longitudinal axis of the vehicle. 
     The description of the invention and its applications as set forth herein is illustrative and is not intended to limit the scope of the invention. Variations and modifications of the embodiments disclosed herein are possible, and practical alternatives to and equivalents of the various elements of the embodiments would be understood to those of ordinary skill in the art upon study of this patent document. These and other variations and modifications of the embodiments disclosed herein may be made without departing from the scope and spirit of the invention.