Street sweeper main broom cutoff flap

A street sweeper system is used typically in a motorized vehicle. The sweeper utilizes a cylindrical brush rotating about an axis generally perpendicular to the vehicle's direction of motion. A conveyor belt catches debris thrown forwards and upward by the brush and moves the debris to a hopper. A cutoff flap is mounted contacting a front portion of the brush. The cutoff flap deflects debris that moves upwards along a front portion of the brush back downwards to be recollected at the conveyor.

FIELD OF THE INVENTION

The present invention relates to motorized street sweeping vehicles.

BACKGROUND OF THE INVENTION

Automated street sweeping vehicles are essential equipment for commercial and government organizations. The vehicles are used for cleaning debris from roadways, walkways, parking lots, runways, and many other ground surfaces.

For streets and highways, large sweepers are primarily used. The large sweepers are motorized (typically diesel powered) and can be custom-made or built upon a standard commercial truck chassis. The large sweepers typically include large main brushes which direct debris onto a paddled conveyor that moves the debris into a large-capacity debris hopper. The large hoppers allow the sweepers to cover greater distances without the need for emptying the hopper. The large brushes allow the sweeper to pick up larger debris (e.g. rocks, tire treads, wood pieces), thus avoiding the need for multiple passes of the sweeper or manual retrieval of the debris.

Although effective, such street sweepers often miss a certain percentage of the debris, even when the sweeper passes directly over the debris. In some cases, the debris gets caught up in the brush and passes over the top of the brush. When this happens, the debris typically falls off the back end of the brush and is ejected out the back end of the sweeper.

Such sweepers can also generate a dust cloud while in operation. Typically, suction is used on side brushes and on the conveyor to control this dust. Regardless, a significant amount of dust is ejected into the atmosphere at least at the periphery of the brushes during sweeping. Besides being a nuisance, the dust is a source of particulate air pollution. In many localities air pollution is a major problem, and some municipalities are under government mandates to reduce particulate air pollution in particular.

What is needed is a sweeper that can pick up a high percentage of road debris by preventing debris from passing over the top of the main brush. Further, the sweeper should reduce the amount of dust ejected into the air. The present invention fulfills these and other needs, and addresses other deficiencies of prior art implementations.

SUMMARY OF THE INVENTION

To overcome the limitations in the prior art described above, and to overcome other limitations that will become apparent upon reading and understanding the present specification, the present invention discloses a sweeper for a ground surface having a front end, a back end and a forward direction of motion. The sweeper includes a debris mover with an outer surface, a ground contact area, an axis of rotation, and a cutoff area on the outer surface of the debris mover. The ground contact area is defined where the outer surface of the debris mover contacts the ground surface. The debris mover rotates about the axis of rotation so that the outer surface of the debris mover moves at least in part towards the front end of the vehicle at the ground contact area. The outer surface of the debris mover moves at least in part upwards at the cutoff area as the debris mover rotates about the axis of rotation.

The sweeper further includes a debris collector mounted forward of the debris mover. A collection space is defined between the debris mover and the debris collector. A cutoff flap is mounted forward of the debris mover. The cutoff flap has a distal end adjacent the outer surface of the debris mover along the cutoff area. The cutoff flap is mounted at an angle relative to the outer surface of the debris mover so that a portion of the debris traveling to the cutoff area is deflected back into the collection space.

The distal edge of the cutoff flap may include an elongated blade, and the elongated blade may be substantially flexible. In one configuration, the elongated blade is made from belted rubber sheet.

In one arrangement, the cutoff area is located between 45 degrees and 140 degrees from the ground contact area. Also, at least a portion of the cutoff flap proximate the distal tip may be oriented between 10 degrees and 30 degrees relative to horizontal.

The sweeper may include a shroud encompassing the debris collector. A passageway is formed between a rear portion of the shroud and a front portion of the debris mover. The cutoff flap substantially covers the passageway to prevent the passage of dust therethrough.

The sweeper may be configured with a gap between the distal end of the cutoff flap and the outer surface of the debris mover. In one arrangement, the gap measures between 0 and 1 inch.

The debris mover may include a cylindrical brush having a plurality of radial bristles each having distal ends, the distal ends of the radial bristles defining the outer surface of the debris mover. In one configuration, the distal end of the cutoff flap extends substantially within the bristles of the brush. Also, the debris collector may include a conveyor, the conveyor moving the debris substantially upwards and forwards.

In another embodiment of the present invention, a method of sweeping debris involves moving a conveyance in a forward direction. A debris mover is rotated on the conveyance to push the debris at least in part in the forward direction. A portion of the debris that is moving at least in part upwards at a forward portion of the debris mover is deflected substantially downwards for recollection by the debris mover.

The method may include collecting the debris at a debris collector located forward of the debris mover to remove the debris. The method may also involve blocking airborne dust from passing though at least a portion of a passageway between the debris mover and the debris collector to prevent escape of a dust portion of the debris.

In another embodiment of the present invention, a mobile sweeping system is usable for removing debris from a ground surface. The street sweeping system has a forward direction of motion and a sweeping width. The street sweeping system further includes a debris moving means moving a debris at least in part forwards and upwards across the sweeping width. A debris collection means is mounted generally forward of the debris moving means to collect debris from the debris moving means. A cutoff means is adjacent to a forward portion of the debris moving means where an outer surface of the debris moving means is moving at least in part upwards. The cutoff means deflects a portion of the debris passing upwards along the outer surface of the debris moving means substantially downwards.

The sweeping system may include shroud means encompassing at least part of the debris collection means. The cutoff means forms an air restriction between the debris moving means and the shroud means. The restriction prevents release of a portion of airborne dust of the debris therethrough. The sweeping system may also include an air moving means drawing air away from a passageway between the debris moving means and the shroud means. The air restriction between the debris moving means and the shroud means traps the airborne dust for collection by the air moving means.

In one configuration, the sweeping system further includes a gap between the cutoff means and the outer surface of the debris moving means. A distal portion of the cutoff means may substantially penetrate beneath the outer surface of the debris moving means. The collecting means may include conveyor means for moving the collected debris into a hopper.

DETAILED DESCRIPTION OF THE VARIOUS EMBODIMENTS

Referring now toFIG. 1, a street sweeping vehicle, generally indicated by reference numeral100, has a front end102and back end104. The front end102of the vehicle includes a cab section103where an operator sits. A cylindrical debris mover (typically a brush), generally indicated by reference numeral106is mounted near the back end104of the vehicle100. The brush106includes bristles108and a hub110. The centerline of the brush106is preferably substantially perpendicular to the direction of forward motion of the vehicle100, forward motion being indicated by the bold, straight arrow above the vehicle100. It is appreciated, however, that the brush106can be oriented skewed (i.e. non-perpendicular to forward motion) to push debris both forwards and sideways.

The brush106is powered and rotates in the direction indicated by the bold, curved arrow. It is appreciated that the brush106can be rotated opposite the direction indicated inFIG. 1, although such a rotation is likely to be less effective. The brush106can rotate at varying speeds, typically in the range of 75 to 150 rpm. The brush106in this example has an outer diameter ranging from 36 to 18 inches (91 to 45 cm), the outer diameter typically decreasing with wear of the bristles108. Alternative pickup elements other than a brush are possible so long as the pickup element has the capability to pickup debris and resist wear while contacting the debris and a ground surface112.

The outer surface of the brush106(i.e. at the tip of the bristles108) contacts the ground surface112at a contact area114. The brush106throws debris from the ground surface112into a collection space123, where the debris lands on a debris collector (e.g. conveyor), generally indicated by reference numeral120. The conveyor120includes a belt122with paddles124mounted along an outer surface at regularly spaced intervals. The belt122rotates such that the debris is carried upwards and forwards away from the brush106, as indicated by the angled arrow located over the belt122. The debris leaves the top of the conveyor120at an exit portion123aand drops into a hopper125. A shroud126covers a top portion of the conveyor120and helps contain dust and debris as the debris is moved upwards by the conveyor belt122.

In the sweeping vehicle100according to the present invention, a cutoff plate or flap130is mounted on the vehicle100forward of the brush106. In this example, the cutoff flap130is attached to the conveyor shroud126. It is possible to attach the cutoff flap130to any structure allowing the flap130to be adjacent the brush106. The cutoff flap130includes a distal end127that is adjacent the outer surface of the brush106at a cutoff area128. The cutoff area128is located on a portion of the brush's outer surface that is moving substantially upwards as the brush106rotates.

Conceptually, the cutoff flap130is a structural element that counteracts the tangential trajectory of debris being moved by the brush106or other debris moving device. By forcing the debris back into the collection space123, the debris will recirculated and thereby eventually be removed at the debris collector120. In broad terms, the flap130is constructed to provide a barrier to debris having a trajectory that would carry it upwards over the brush.

Turning now toFIG. 2, a side view of the sweeping system illustrates the benefits of the cutoff flap130. The brush106contacts the ground at the contact area114as the brush106is being rotated in the direction indicated by the curved arrow. The rotation of the brush106tends to build up a “wedge”200of debris at the contact area114as the vehicle100moves forward. Most of the debris in the wedge200is flung into the collection space123in a debris path202tangential to the brush106originating where the brush106contacts a top portion of the wedge200. Debris can become trapped in the bristles108or otherwise be carried over the top of the brush hub110, exemplified by debris path204.

Debris that is carried over the top of the brush106in prior art sweepers will usually be ejected from behind the brush106and therefore missed by the sweeper. By including the cutoff flap130, the debris is defected substantially downwards so that the debris can be returned to the collection space123, and eventually be recovered at the conveyor120.

The cutoff flap130in the illustrated embodiment is formed as an elongated blade fixably attached to an angle bracket212and a mounting plate214. A retainer bracket216clamps the cutoff flap130to the mounting plate214. The retainer bracket216may have an angular cross section to further stiffen the cutoff flap130and angle bracket212.

The angle bracket212orients the distal end127of the cutoff flap130to the desired angle relative to the brush106. The angle bracket212also positions the cutoff flap130so that there is a gap220between the distal tip127and the outer surface of the brush106(i.e. at the tip of the bristles108). In most applications, the gap220is desired to reduce vibrations and wear on the brush106and cutoff flap130. In some applications, however, it may be beneficial to allow the distal tip127to touch the brush106(i.e. gap220size is zero), or arrange the cutoff flap130so that the distal tip127protrudes through the brush's outer surface to extend into the bristles108.

The cutoff flap130is preferably made adjustable (e.g. by using elongated mounting slots) thereby allowing the user to adjust the gap220to keep it a desired value given various stages of brush wear. The cutoff flap130is preferably made from a flexible material, such as rubber or plastic. A cutoff flap130using a rigid blade may also be constructed, although the associated gap220would typically need to be larger to prevent flap damage due to deflecting large objects or inadvertent contact with the brush106.

It is appreciated that other embodiments of the cutoff flap130may constructed to deflect debris back into the brush106. In some applications, the distal edge127of the cutoff flap130may be non-linear (e.g. curved or jagged). The cutoff flap130may have components that are non-planar, such as a blade portion that is formed from an elongated member with curved cross sectional shape. A cutoff flap130with a curved cross section may, for example, be shaped so that a portion near the distal edge127is substantially tangent to the brush's outer surface.

It is appreciated that the cutoff flap130helps reduce the release of airborne dust particles from the sweeper100. A housing218encloses at least a portion of the brush106and the collection space123. The cutoff flap is130positioned at a passage230between the rear of the conveyor shroud126and a front portion of the brush106. The cutoff flap130closes at least part of the passage230along the width of the brush106, thereby preventing the release of dust therefrom. The dust that is contained by the cutoff flap130can then be removed by a vacuum system150(best seen in FIG.1). The vacuum system150pulls air up through the conveyor120.

A particular useful arrangement of a cutoff flap130and brush106are shown in FIG.3A. The distal tip127of the cutoff flap130is adjacent the brush at the cutoff area128. The cutoff area128is preferably located at an angle300measuring between 45 degrees (or less) to 140 degrees (preferably 94 degrees) from the ground contact area114. For a brush106with a nominal outer diameter of 35.5 inches (90.2 cm), this corresponds to locating the tip215of the cutoff flap130about 20.0±1.0 inches (51.0±2.0 cm) above ground. The cutoff flap130is typically oriented at a mounting angle302measuring between 10 degrees and 30 degrees from horizontal, preferably about 23±1 degrees. In this application, the gap220ranges from 0.0 inches to 1.0 inch (2.50 cm) or more, preferably 0.75±0.10 inches (1.91±0.25 cm).

It is appreciated that the nominal brush diameter of 35.5 inches (90.2 cm) used in this example is that of an unworn brush106. The diameter of a brush106may decrease to approximately 19 inches (48 cm) or less due to normal wear. The brush106is attached to a drive mechanism (not shown) at the hub110, typically a swing-down drive arm. The drive arm will adjust the brush position for wear in order to keep the brush106in contact with the ground. Given the changing brush diameter and adjustments of the drive arm, the orientation of the cutoff flap130to the brush106, as well as the size of the gap127, may change from the values described above. Regardless, the cutoff flap130has been found to be beneficial through the entire wear range of the brush106.

Of course, means can be provided to move the flap130so as to maintain a constant gap220, or maintain contact with the brush106. An example of one such adjusting means includes an adjustment mechanism, generally indicated by reference350, as shown inFIGS. 3B and 3C. InFIG. 3B, the brush106is shown in an unworn state. The brush106is supported by a drive arm352which rotates about an axis354to raise and lower the brush106. The drive arm352allows the brush106to be lifted off of the ground surface112as well as adjusting for brush wear.

The adjustment mechanism350includes a drive arm linear gear356. The drive arm linear gear356meshes with a drive gear358that in turn meshes with a reduction gear360. The reduction gear360meshes with a cutoff flap linear gear362that is attached to the cutoff flap130. The adjustment mechanism350also includes additional structure well known in the art (and therefore not shown) such as support brackets for the gears and linear bearings for the cutoff flap130and cutoff flap linear gear362.

InFIG. 3C, the brush106is shown in a worn state. The unworn brush diameter ofFIG. 3Bis shown in broken lines to show that the brush wear has caused the drive arm352to move downward. Downward motion of the drive arm352(e.g. counterclockwise rotation about the axis354as seen in this view) causes clockwise rotation of the drive gear358as shown in the curved arrow. In turn, the reduction gear360will turn counterclockwise, thereby moving the cutoff flap linear gear362towards the brush's outer surface as shown by the arrow over the cutoff flap130.

Although the adjustment mechanism350shown inFIGS. 3B and 3Cuses gears, it is appreciated other means of adjusting the cutoff flap130possible. Fully mechanical devices such as rods, levers, screws, etc can be used to automatically position the cutoff flap130. Alternatively, electromechanical of hydromechanical devices such as motors or actuators can be used to move the cutoff flap160. Such devices are controllable by mechanical or electrical control systems, and can use sensors to determine brush wear and/or gap size.

Turning now toFIG. 4, a particularly useful embodiment of a cutoff flap130is shown. The cutoff flap130is best made of two- or three-ply sheet rubber product such as ⅜ inch (0.95 cm) thick Goodyear Plylon® (220B {fraction (3/16)}×{fraction (1/16)}, Class I). Making the elongated blade214from relatively flexible rubber helps prevent damage caused by deflecting heavy objects and inadvertent contact with the brush106. In another embodiment, the cutoff flap130can be made of a rubber blade portion attached to a rigid portion made of metal or some other suitable material. The rigid portion is attachable to the mounting structures of the vehicle100.

The cutoff flap130can be attached to the mounting plate214using the retainer bracket216and standard fasteners215(best seen inFIG. 2) that pass through mounting slots400in the flap130. The retainer bracket216can be formed of angled sheet metal to further stiffen the mounting plate214and cutoff flap160.

The retainer bracket216, angle bracket212and mounting plate214can be formed from sheet metal, typically 0.10 inch (2.5 mm) thick carbon steel. An equivalent strength aluminum or magnesium material may be used where low weight or corrosion resistance is desired.

Although the sweeping system of the present invention has been described in conjunction with a self propelled vehicle100, it is appreciated that a brush106, conveyor120, and cutoff flap130can be used in any conveyance, such as trailers or push sweepers. The cutoff flap130can also be used on smaller sweeping systems that have alternate conveyor120embodiments or sweeping systems that do not include conveyors (e.g. debris is swept directly into a hopper).

It will, of course, be understood that various modifications and additions can be made to the preferred embodiments discussed hereinabove without departing from the scope of the present invention. Accordingly, the scope of the present invention should not be limited by the particular embodiments described above, but should be defined only by the claims set forth below and equivalents thereof.