Abstract:
An improved brush assembly for mounting on horizontally rotating brushes on street sweeping machines. A circular disk carries brush holders holding bristles in the desired configuration. The brush holders are clamped to the disk by a clamp having a clamp bar that engages the brush holder and is maintained parallel to the brush holder with an offset support. A bolt and nut combination between the brush holder and disk presses the clamp bar firmly against the brush holder to hold it in place. Alignment holes in the brush holder cooperate with pins on the clamp bar to maintain the brush holder in the proper position. Holes through the brush holder have transverse walls so that U-shaped bristles can be extended through the holes with legs of the U-shape on opposite sides of the transverse walls. The brush holder can be configured with a reinforced strip area for extra strength and a pair of reinforced tabs to provide further strength to resist cracking and fatigue failure during use.

Description:
This application is a continuation-in-part of U.S. application Ser. No. 09/076,076, filed May 11, 1998 U.S. Pat. No. 6,134,740. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to machines, such as street sweepers, that move across a surface while sweeping that surface with rotary brushes mounted on disks generally parallel to the ground. 
     BACKGROUND OF THE INVENTION 
     Sweeping machines for streets, factory floors and the like generally include wheel mounted vehicle that moves across a street, floor or other surface to be swept. Most include a brush assembly on each side of the machine, each assembly including a disk on which the brush is mounted with the disk approximately parallel to the surface to be swept and rotatable to sweep dirt and debris from the surface towards a container for disposal. 
     Conventionally, each brush assembly consists of a heavy metal disk mounted on the sweeping machine for rotation adjacent to the surface to be swept. Brush holders, each a segment of a circle, are bolted to the underside of the disk adjacent to the disk periphery forming a circle. Generally, the brushes are made up of U-shaped bristles formed from stiff metal wire, such as piano wire and are attached to the brush holder. 
     These bristles tend to wear rapidly, particularly where the surface is rough, such rough concrete surfaces. Therefore, the brush holders must be removed from the disk and the bristles be replaced at regular intervals. To replace the brush holders requires elevation of the support disks and unbolting the brush holders from the support disks. This is a time consuming task which is difficult and can be dangerous because of the great weight of the support disks. The bolts may become jammed, rusted and are supporting the weight of the brush holders and brushes. Reinstallation requires holding the brush holders so that holes in the holders align with corresponding holes in the support disks. This is difficult with the heavy brush holders adjacent to the ground with no means of maintaining alignment during installation. 
     The brush holders, which are generally formed from a plastic material also wear and suffer cracks and must be replaced quite often. In addition the angle of the bristles to the surface being swept is often other than the optimum sweeping angle. 
     Thus, there is a continuing need for improved brush assemblies that allow replacement of brush holders and bristles in an easy, rapid and safe manner, that maintain alignment between brush holders and support disks during disassembly and reassembly that provide an optimum sweeping angle between bristles and the surface to be swept and that are resistant to cracking of brush holders in use. 
     SUMMARY OF THE INVENTION 
     The above-noted problems, and others, are overcome in accordance with this invention by a brush assembly which comprises a circular disk for mounting on a sweeping machine adjacent to a surface to be swept, brush holders for mounting along the periphery of the lower side of the disk and alignment holes in the brush holders for properly aligning the brush holders and a clamping arrangement for clamping the brush holders against the disk. 
     The brush holders have a number of bristle mounting holes extending from the side in contact with the disk to the opposite side for receiving brush-bristles. The bristles have a narrow U-shape. A transverse retainer wall extends across each mounting hole to hold the bristles, which are installed in the holes with the two legs of the U-shape on opposite sides of the retainer wall. 
     The clamping arrangement comprises a clamp bar that extends along the surface of each brush holder opposite the side in contact with the circular disk and extends beyond the brush holder towards the center of the disk. The clamp bar is firmly pressed against the disk by at least one threaded member extending through the clamp bar and disk, typically a bolt and nut arrangement or by a stud secured to the plate and extending through the clamp bar to a nut. For best results an offset support is secured to the edge of the bar towards the disk center, with the threaded member between the offset support and the brush holder. The offset support preferably has a thickness approximately equal to the thickness of the brush holder to assure uniform clamping pressure on the brush holder. 
     In order to assure proper alignment of the brush holder with the circular disk, alignment pins are provided on the clamp par to project into corresponding alignment holes in the brush holder. 
     For best results, the bristle mounting holes should be angled outwardly of the disk center an angle to the disk of about 60° to 65°, to provide optimum sweeping of debris and dirt. Optimally, this angle has been found to be about 62°. While any suitable number of bristle mounting holes and hole dimensions may be used, three rows of holes along the disk periphery provides excellent results. Best results are obtained with bristle mounting hole cross sections having widths of from about 0.4 to 0.6 inch and depth of from 0.7 to 1 inch. The overall thickness of the brush holder is preferably from about 0.75 to 1.25 inch, so that length of the bristle mounting holes is correspondingly just greater that 0.75 to 1.25 inch. 
     In order to prevent cracking of the brush holders at corners of the bristle mounting holes or at any other intersections between flat surfaces, all such corners are preferably rounded. Ideally, the radius of all corners is from about 0.030 to 0.150 inch. We have found that this rounding apparently prevents stress peaks at those corners and will add considerably to the useful life of the brush holders. 
     While the brush holders may be formed from any suitable material such as aluminum or high strength plastics, for optimum durability together with convenience of manufacture by injection molding, nylon of the sort available from Dupont under the “Nylon 66” designation is preferred. For further strength, the nylon may be filled with fibers such as short glass fibers. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     Details of the invention, and of preferred embodiments thereof, will be further understood upon reference to the drawing, wherein: 
     FIG. 1 is a schematic side elevation view of a portion of a street sweeping machine showing the brush assembly of this invention in place for sweeping; 
     FIG. 2 is and exploded view of the brush assembly; 
     FIG. 3 is a plan view of the brush holder taken from the disk engaging side; 
     FIG. 4 is a section view taken on line  4 — 4  in FIG. 3; 
     FIG. 5 is a section view taken on line  5 — 5  in FIG. 3; and 
     FIG. 6 is a section view taken on line  6 — 6  in FIG.  3 . 
     FIG. 7 is an additional embodiment of the device which includes a cooperating nut affixed to the lower side of the brush holder and upper side of clamp bar. 
     FIG. 8 is a section view taken on line  8 — 8  in FIG.  7 . 
     FIG. 9 is an additional embodiment of the device having an extra reinforcement section for strength. 
     FIG. 10 is a section view taken on line  10 — 10  of FIG.  9 . 
     FIG. 11 depicts another embodiment of the device which includes a reinforcing section and a pair of reinforcing tabs for strength. 
     FIG. 12 depicts an embodiment of the device which includes reinforced sections as well as additional mounting apertures for a plurality of mounting options. 
     FIG. 13 is a section view taken on line  13 — 13  of FIG.  12 . 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring to FIG. 1 there is seen a simplified side elevation view, representative of a conventional street sweeper  10 . Sweeper  10  is mounted on a plurality of wheels  12  for powered movement along a street, factory floor or other similar surface. Two brush assemblies  14  are mounted adjacent to front wheel for powered rotation in a generally horizontal plane. Brush assemblies  14  extend beyond the side of the vehicle a selected distance to clan up against curbs or other adjacent objects. Brush assemblies  14  generally rotate so that the forward edges are moving toward the centerline of sweeper  10 , so that dirt and debris encountered by the vehicle is moved toward the vehicle centerline. As sweeper  10  moves, a large brush  16  toward the back of the sweeper rotates about a horizontal axis transverse to the sweeper centerline to sweep accumulated dirt and debris forwardly and upwardly into a large container  18 . 
     Bristles  20  on brush assemblies  14  are in contact with the surface being swept, which is likely to be hard and irregular, such as concrete, so that the bristles may rapidly wear down. Also, the periphery of the brush assembly may bump against curbs or other objects. In order to replace worn bristles, it is important that the brush assembly be easily disassembled for bristle replacement and then easily reassembled. Further, the brush assembly  14  must be sturdy and maintain the brush in proper alignment during use. 
     Brush assembly  14  is shown in exploded perspective in FIG. 2, which shows a portion of the generally circular disk  22  with one of a peripheral plurality of brush holders  24 . Bristle mounting holes  26  extend through the brush holders  24  in a predetermined pattern, as detailed in FIGS. 3-6, discussed below. 
     A clamp assembly  28  is provided to hold brush holders  24  firmly against disk  22  during operation of sweeper  10 . Assembly  28  comprises a clamp bar  30  for engaging the side of a brush holder opposite that engaging disk  22  while extending toward the center of disk  22 . An offset support  32 , typically a small plate welted to clamp bar  30 , has a thickness the same as the thickness of brush holder  24 . A threaded member extends through clamp bar  30  between brush holder  24  and offset support  32  to press the clamp bar against the brush holder. In one embodiment of mounting a threaded member such as a bolts  36  extend through holes  38  in disk  22  to cooperatively engages a conventional nut affixed to the hidden side of clamp bar  30  in line with the holes or apertures  31 . Alternatively, other threaded members could be used, such as a stud (not shown) welded to disk  22  could extend though a hole in clamp bar  30  to a loose nut on the upper surface of the clamp bar  30 . 
     Alignment holes  42 , preferably two although more could be used if desired, are provided in brush holder  24 , positioned to receive alignment pins  44  on the side of clamp bar  30  that engages brush holder  24 . The cooperating alignment pins  44  and alignment holes  42  will keep brush holder  24  precisely in the optimum position during use and will hold these parts in alignment during disassembly and reassembly of the brush assembly whenever bristles  20  need to be replaced. 
     Details of brush holders  24  are provided in FIGS. 3-6. In FIG. 3, brush holder  24  is seen in plan view from the side that engages disk  22 . 
     Brush holders  24  are preferably formed from a high strength material, such as fiber reenforced nylon, by injection molding. Preferably, three approximately parallel peripheral rows of bristle receiving holes  26  are provided. To accommodate curvature of each brush holder  24  has fewer holes  26  in the inner rows. 
     Each bristle receiving hole  26  has a central, transverse, wall  46 . Each bristle, typically formed from piano wire or the like, has a narrow “U-shaped” configuration, with the distance between the legs of the “U” being greater than the width of wall  46  and less than the width of hole  26 . Since disk  22  covers the upper surface (seen in FIG. 3) of brush holder  24 , bristles  20  are held in place with some ability to move and flex slightly in use. A few bristles  20  are shown in FIGS. 3 and 4 to illustrate bristle position without cluttering the drawing. 
     An radially extending, circular ridge  48  is provided as a “bumper” to protect brush holder  24  against damage or sever wear from contact of the brush holder with a curb or other object during sweeping. Often, the outer edge of disk  22  will contact the curb. Since disk  22  is generally made from steel or the like, wear will be slow. Since bumper ridge  48  is spaced from disk  22  the thickness of brush holder  24 , the ridge will protect the brush holder from excessive wear in cases where a curb or object is high enough to impact the ridge but not high enough to impact the edge of disk  22 . 
     As seen in FIG. 5, spaces between adjacent peripheral holes  26  caused by the necessity to have fewer holes in inner rows due to curvature, either that space can be solid or can have a recess  50 . For maximum strength, a wall  51  may be formed all the way around alignment hole  42 , as seen in FIG.  6 . 
     In order to prevent stress concentrations and subsequent cracking in use, the approximately rectangular cross section bristle holes  26  preferably have rounded corners  54 , optimally with a radius of from about 0.025 to 0.05 inch. Similarly, the ends of brush holder preferably have corners  56  with radii of from about 0.12 to 0.14 inch. 
     Additional embodiments to prevent stress concentration and cracking in use and to provide additional mounting configurations are depicted in FIG.  7  through FIG.  13 . FIG. 7 shows an embodiment of the device with a mounting nut  68  cooperatively engaged in the bottom surface  25  of the brush holder  24  which could be done by forming an aperture to match the shape of the nut  68  and allow for a compression fit of the nut  68  therein. 
     The mounting nut  68  is engaged with the surface of the clamp bar  30  and holds it into position against the bottom surface  25  of the brush holder  24  before, and during mounting. 
     FIG. 9 depicts the brush holder  24  has an additional reinforcing strip area  62  extending from and defined by the area of the brush holder  24  between the alignment holes  42  and rearward of the inward most row of peripheral holes  26  and the inner edge  64  of the brush holder  24  to provide added strength to the brush holder  24  during use. As shown in FIG. 9 the clamp bar  30  extends beyond the inner edge  64  and toward the center of the disk  22 . This additional reinforcing strip area  62  in the current best mode terminates at a substantially straight inner edge  64  that when adjacent to and contacting the side of the similarly shaped offset support  32  extending from the clamp bar  30  provides additional lateral and vertical stability to the mount when mounted to the operating spinning disk  22 . Of course the inner edge  64  and side of the offset support  32  might be curved or shaped differently and maintain the support but the current best mode features substantially straight edges on both. 
     FIG. 11 depicts the disclosed device as shown in FIG. 9 with the addition of a pair of reinforcing tabs  70  having corners  72  formed by intersection of substantially perpendicular extensions  74  of the inner edge  64  and substantially straight inwardly extending sides  76 . The result being a notch area  78  to accommodate parts of the clamp assembly  28  and a much stronger brush holder  24  with the addition of the reinforcing strip area  62  and the two reinforcing tabs  70  which as shown have a substantially triangular shape with an arched hypotenuse which has shown to yield a substantial increase in strength to the device when in use. The construction of the wall of the brush holder  24  in the reinforcing strip area  62  and the reinforcing tabs  70  could be solid or in a honeycombed fashion with ribs to provide strength but reduce weight, much like that shown in FIG. 4 with the intent being a construction to provide a strong wall surface to both strengthen the brush holder  24  from cracking during operation. 
     FIG. 12 depicts another favored embodiment of the disclosed device as shown in FIG. 11 which provides an additional pair of mounting apertures  66  communicating through the brush holder  24  at positions determined to be inline with another pair of bolts  36  which would mount through the disk  22  and through the mounting apertures  66  wherein the bolts  36  would cooperatively engage mounting nuts  68  which are affixed to the brush holder  24  on the bottom side of the brush holder opposite the side contacting the disk  22 . This would allow the brush holder  24  to be mounted to the disk  22  using bolts  36  which would be cooperatively engaged with the mounting nuts  68  in addition to the aforementioned mounting configuration using the clamping assembly  28 . The provision of this pair of mounting apertures  66  will allow the improved brush holder  24  to be mounted on disks  22  that may not have been configured yet to accept the clamp assembly  28  and still be used at a later date when accommodations and mounting for the clamping assembly  28  have been provided on the disk  22 . The user thus still has the benefit of the added reinforcing strip  62  area between the inner edge  64  and the inward most row of peripphial holes  26 , the reinforcing tabs  70 , and the other improvements of the disclosed device using a mount to the disk  22 . The user can also later take advantage of the preferred mount using the clamp assembly  28  when the holes  38  in the disk  22  are in place to accommodate the bolts  36  for the clamp assembly  28 . In this fashion, the user takes advantage of the additional utility with the strengthened by the wall surfaces provided by the reinforcing strip area  62  and reinforcing tabs  70  and the other enhancements of the device when mounted to a non conforming disk  22 , and also allows the user to upgrade the clamp assembly later to achieve the best mount at a later time. 
     Still further, if the nuts  68  are attached on their lower side, to the surface of the clamp bar  30  which abuts the lower surface  25  of the brush holder  24 , they provided a mount to hold the clamp bar  30  against the lower surface  25  of the brush holder  24  during mounting to a properly configured disk  22 . 
     While certain specific relationships, materials and other parameters have been detailed in the above description of preferred embodiments, those can be varied, where suitable, with similar results. Other applications, variation and ramifications of the present invention will occur to those skilled in the art upon reading the present disclosure. Those are intended to be included within the scope of this invention as defined in the appended claims.