Title:
Motorized street sweeper
Kind Code:
A1


Abstract:
A street sweeper system is used in a motorized vehicle. The sweeper utilizes a cylindrical brush rotating about a horizontal axis that is typically 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 conveyor flap is mounted on a lower edge of the conveyor to improve sweeping performance. The conveyor lip covers a space between the lower edge of the conveyor and the ground. A cutoff flap is located on a forward portion of the brush to deflect debris that is passing over the brush. A recirculation flap is located at a rear portion of the brush to recirculate debris that has passed over the top of the brush.



Inventors:
Mathews, Thomas P. (Plymouth, MN, US)
Lenzmeier, Michael H. (North Branch, MN, US)
Weidner, Archie A. (Minnetonka, MN, US)
Wilmo, Michael S. (Crystal, MN, US)
Engel, Gregory J. (Plymouth, MN, US)
Application Number:
10/237212
Publication Date:
03/11/2004
Filing Date:
09/06/2002
Assignee:
Tennant (Minneapolis, MN, US)
Primary Class:
Other Classes:
15/84, 15/82
International Classes:
E01H1/04; E01H1/08; (IPC1-7): E01H1/04
View Patent Images:



Primary Examiner:
GUIDOTTI, LAURA COLE
Attorney, Agent or Firm:
Hamre, Schumann, Mueller & Larson, P.C. (Minneapolis, MN, US)
Claims:

What is claimed is:



1. A sweeper for a ground surface having a front end, a back end and a forward direction of motion, the sweeper comprising: a debris mover comprising: an outer surface; a ground contact area defined where the outer surface of the debris mover contacts the ground surface; an axis of rotation, the debris mover rotating 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; a cutoff area on the outer surface of the debris mover, the outer surface of the debris mover moving at least in part upwards at the cutoff area as the debris mover rotates about the axis of rotation; and a recirculation contact area, the outer surface of the debris mover moving at least in part downwards at the recirculation contact area as the debris mover rotates about the horizontal axis; a cutoff flap mounted forward of the debris mover, the cutoff flap having a distal end adjacent the outer surface of the debris mover along the cutoff area so that a first portion of the debris traveling to the cutoff area is deflected at least in part downward; and a recirculation flap mounted behind the debris mover, the recirculation flap proximate the recirculation contact area so that a second portion of the debris traveling to the recirculation contact area is deflected back into the debris mover.

2. The sweeper of claim 1, further comprising: a debris collector mounted forward of the debris mover; and a conveyor flap mounted adjacent a lower edge of the debris collector, the conveyor flap having a distal edge proximate the ground surface, the conveyor flap substantially covering a space defined between a lower edge of the debris collector and the ground surface.

3. The sweeper of claim 2, further comprising a ground gap defined between the distal edge of the conveyor flap and the ground surface.

4. The sweeper of claim 2, wherein the conveyor flap comprises a plurality of slots at the distal edge.

5. The sweeper of claim 2, wherein at least the distal edge of the conveyor flap is oriented an angle between 40 and 50 degrees relative to vertical.

6. The sweeper of claim 1, wherein the cutoff area is located between 45 degrees and 140 degrees from the ground contact area.

7. The sweeper of claim 1, wherein at least a portion of the cutoff flap proximate the distal tip is oriented between 10 degrees and 30 degrees relative to horizontal.

8. The sweeper of claim 1, further comprising a gap between the distal end of the cutoff flap and the outer surface of the debris mover.

9. The sweeper of claim 1, wherein the recirculation flap comprises: a flexible mounting flap fixably attached to the sweeper; an elongated blade connected to the mounting flap, an edge of the elongated blade engaging the debris mover.

10. The sweeper of claim 1, wherein the recirculation contact area is located between 40 degrees and 80 degrees from the ground contact area.

11. The sweeper of claim 1, wherein the debris mover comprises a brush having bristles.

12. The sweeper of claim 11, wherein a distal end of the recirculation flap extends substantially within the bristles of the brush.

13. A method of street sweeping of a debris from a ground surface, comprising: moving a conveyance in a forward direction on the ground surface; rotating a debris mover of the conveyance to move the debris at least in part forward of the debris mover; catching the debris on a debris collector facing the debris mover to collect the debris; deflecting back a first portion of the debris thrown into a space defined between a lower edge of the debris collector and the ground surface to recirculate the first portion of the debris back into the debris mover; deflecting downwards a second portion of the debris that passes upwards along a forward portion of the debris mover to recirculate the second portion of the debris back into the debris mover; and deflecting forwards a third portion of debris that passes downwards along a rear portion of the debris mover to recirculate the third portion of debris back into the debris mover.

14. The method of claim 13, further comprising drawing a vacuum to move an airborne dust from a space surrounding the debris mover to collect the airborne dust.

15. The method of claim 14, further comprising blocking the airborne dust at the forward portion of the debris mover to prevent escape of the airborne dust therethrough.

16. The method of claim 14, further comprising blocking the airborne dust at the rear portion of the debris mover to prevent escape of the airborne dust therethrough.

17. The method of claim 14, further comprising blocking the airborne dust at the space defined between a lower edge of the collector and the ground surface to prevent escape of the airborne dust therethrough.

18. A mobile sweeping system for removing a debris from a ground surface, the sweeping system having a forward direction of motion and a sweeping width, the sweeping system further comprising: a debris moving means moving a debris at least in part forwards across the sweeping width; a debris collecting means catching the debris moved by the debris moving means; a deflecting means covering at least part of a collector clearance space defined between a lower edge of the debris collecting means and the ground surface, the deflecting means deflecting a first portion of the debris moved by the debris moving means into the collector clearance space back to the debris moving means; a cutoff means 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 deflecting downwards a second portion of the debris passing upwards along the outer surface of the debris moving means; and a recirculation means proximate a back portion of the debris moving means where the outer surface of the debris moving means is moving at least in part downwards and forwards, the recirculation means deflecting a third portion of the debris passing over and behind the debris moving means back to the debris moving means.

19. The sweeping system of claim 18, wherein the deflecting means comprises a distal edge adjacent the ground surface and a substantially flexible portion along the distal edge.

20. The sweeping system of claim 19, wherein the substantially flexible portion comprises a plurality of slots along the distal edge.

21. The sweeping system of claim 18, further comprising a gap between the cutoff means and the outer surface of the debris moving means.

22. The sweeping system of claim 18, further comprising a flexible mounting means resiliently coupling the recirculation means to the sweeping system.

23. The sweeping system of claim 18, wherein a distal portion of the recirculation means substantially penetrates beneath the outer surface of the debris moving means.

24. The sweeping system of claim 18, wherein the deflecting means causes a restriction of a flow through the collector clearance space, the restriction of flow preventing release of a portion of an airborne dust therethrough.

25. The sweeping system of claim 18, further comprising housing means encompassing a rear portion of the debris moving means and wherein the recirculation means causes an air restriction between the debris moving means and the housing means, the air restriction preventing release of a portion of an airborne dust of the debris therethrough.

26. The sweeping system of claim 18, wherein the cutoff means forms an air restriction between the debris moving means and the debris collecting means, the restriction preventing release of a portion of an airborne dust of the debris therethrough.

Description:

FIELD OF THE INVENTION

[0001] The present invention relates to motorized street sweeping vehicles.

BACKGROUND OF THE INVENTION

[0002] 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.

[0003] 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 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.

[0004] 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 bounces around between the brush and conveyor, and can be ejected out from underneath the vehicle. At other times, the debris bounces over the top of the brush and is passed over.

[0005] During operation, such sweepers can also generate a dust cloud when sweeping. In some cases, 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 during sweeping. Besides being a nuisance, the dust is a source of particulate air pollution. In some localities particulate air pollution is a major problem, and municipalities are under government mandates to reduce particulate air pollution.

[0006] What is needed is a sweeper that can pick up a higher percentage of road debris, especially large items. 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

[0007] 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. The sweeper has 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, a cutoff area, and a recirculation contact area. 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 outer surface of the debris mover moves at least in part downwards at the recirculation contact area as the debris mover rotates about the horizontal axis.

[0008] The sweeper also includes a cutoff flap and a recirculation flap. The 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 so that a first portion of the debris traveling to the cutoff area is deflected at least in part downward. The recirculation flap is mounted behind the debris mover. The recirculation flap engages the recirculation contact area so that a second portion of the debris traveling to the recirculation contact area is deflected back into the brush.

[0009] The sweeper may include debris collector mounted forward of the debris mover and a conveyor flap mounted adjacent a lower edge of the debris collector. The conveyor flap has a distal edge proximate the ground surface. The conveyor flap substantially coves a space defined between a lower edge of the debris collector and the ground surface. A ground gap may be included between the distal edge of the conveyor flap and the ground surface. The conveyor flap may include a plurality of slots at the distal edge. In one arrangement, the distal edge of the conveyor flap is oriented an angle between 40 and 50 degrees relative to vertical.

[0010] The sweeper may be configured so that 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. A gap between the distal end of the cutoff flap and the outer surface of the debris mover may be included.

[0011] In one configuration, the recirculation flap includes a flexible mounting flap fixably attached to the sweeper. An elongated blade is connected to the mounting flap. An edge of the elongated blade engages the debris mover. In one arrangement, the recirculation contact area is located between 40 degrees and 80 degrees from the ground contact area. The debris mover may include a brush having bristles. A distal end of the recirculation flap may extend substantially within the bristles of the brush.

[0012] In another embodiment of the present invention, a method of street sweeping of a debris from a ground surface involves moving a conveyance in a forward direction on the ground surface. A debris mover of the conveyance is rotated to move the debris at least in part forward of the debris mover. The debris is caught on a debris collector facing the debris mover to collect the debris. A first portion of the debris thrown into a space defined between a lower edge of the debris collector and the ground surface is deflected back to recirculate the first portion of the debris back into the debris mover. A second portion of the debris that passes upwards along a forward portion of the debris mover is deflected downwards to recirculate the second portion of the debris back into the debris mover. A third portion of debris that passes downwards along a rear portion of the debris mover is deflected forwards to recirculate the third portion of debris back into the debris mover.

[0013] The method may involve drawing a vacuum to move airborne dust from a space surrounding the brush to collect the airborne dust. The method may also involve blocking the airborne dust at the forward portion of the debris mover to prevent escape of the airborne dust therethrough. The airborne dust can also be blocked at the rear portion of the debris mover to prevent escape of the airborne dust therethrough. The airborne dust can further be blocked at the space defined between a lower edge of the collector and the ground surface to prevent escape of the airborne dust therethrough.

[0014] In another embodiment of the present invention, a mobile sweeping system is usable for removing a debris from a ground surface. The sweeping system has a forward direction of motion and a sweeping width. The sweeping system further includes a debris moving means moving a debris at least in part forwards across the sweeping width. A debris collecting means catches the debris moved by the debris moving means. A deflecting means covers at least part of a collector clearance space defined between a lower edge of the debris collecting means and the ground surface. The deflecting means deflects a first portion of the debris moved by the debris moving means into the collector clearance space back to 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 downwards a second portion of the debris passing upwards along the outer surface of the debris moving means. A recirculation means engages a back portion of the debris moving means where the outer surface of the debris moving means is moving at least in part downwards and forwards. The recirculation means deflects a third portion of the debris passing over and behind the debris moving means back to the debris moving means.

[0015] The deflecting means may include a distal edge adjacent the ground surface and a substantially flexible portion along the distal edge. The substantially flexible portion can include a plurality of slots along the distal edge. A gap may be included between the cutoff means and the outer surface of the debris moving means. A flexible mounting means can be used to resiliently couple the recirculation means to the sweeping system.

[0016] In one configuration, a distal portion of the recirculation means substantially penetrates beneath the outer surface of the debris moving means. The deflecting means can cause a restriction of a flow through the collector clearance space. The restriction of flow prevents release of a portion of airborne dust therethrough.

[0017] The sweeper may further include housing means encompassing a rear portion of the debris moving means. The recirculation means causes an air restriction between the debris moving means and the housing means. The air restriction thereby prevents release of a portion of airborne dust of the debris therethrough.

[0018] The cutoff means may form an air restriction between the debris moving means and the debris collecting means. The restriction prevents release of a portion of airborne dust of the debris therethrough.

[0019] The above summary of the present invention is not intended to describe each embodiment or every implementation of the present invention. Advantages and attainments, together with a more complete understanding of the invention, will become apparent and appreciated by referring to the following detailed description and claims taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG. 1 is a cutaway perspective view of a street sweeper vehicle according to an embodiment of the present invention;

[0021] FIG. 2 is a side view of the brush, conveyor and flaps according to an embodiment of the present invention;

[0022] FIG. 3 is a side view of the brush and recirculation flap showing geometric details according the an embodiment of the present invention;

[0023] FIG. 4 is a perspective view of a conveyor flap according to an embodiment of the present invention;

[0024] FIG. 5 is a perspective view of a cutoff flap according to an embodiment of the present invention; and

[0025] FIG. 6 is a perspective view of a recirculation flap according to an embodiment of the present invention.

[0026] While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail herein. For example, while the title describes a street sweeper, this refers only to a preferred embodiment since the present invention is applicable to all forms of debris gathering equipment. It is to be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the invention is intended to cover all modifications, equivalents, and alternatives falling within the scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE VARIOUS EMBODIMENTS

[0027] In the following description of the illustrated embodiments, references are made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration, various embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural and functional changes may be made without departing from the scope of the present invention.

[0028] Referring now to FIG. 1, a street sweeping vehicle, generally indicated by reference numeral 100, has a front end 102 and back end 104. The front end 102 of the vehicle includes a cab section 103 where an operator sits A debris mover, typically a cylindrical pickup brush and generally indicated by reference numeral 106, is mounted near the back end 104 of the vehicle 100. The brush 106 includes bristles 108 and a hub 110. The horizontal axis of the brush 106 is oriented substantially perpendicular to the direction of forward motion of the vehicle 100, indicated by the bold, straight arrow above the vehicle 100. It is appreciated, however, that the brush 106 can be oriented skewed (i.e. non-perpendicular to forward motion) to push debris both forwards and sideways.

[0029] The brush 106 is powered and rotates about its axis in the direction indicated by the bold, curved arrow. It is appreciated that the brush 106 can be rotated opposite the direction indicated in Fig.1, although such a rotation is likely to be less effective. The brush 106 can rotate at varying speeds, typically in the range of 75 to 150 rpm. The brush 106 in this example has an outer diameter ranging from 36 to 18 inches (91 to 45 cm), the outer diameter decreasing with wear of the bristles 108. The outer surface of the brush 106 (i.e. at the tip of the bristles 108) contacts the ground surface 112 at a contact surface 114. The brush 106 throws debris from the ground surface 112 to a debris collector (in this example a conveyor), generally indicated by reference numeral 120.

[0030] The conveyor 120 includes a belt 122 with paddles or cleats 124 mounted along an outer surface at regularly spaced intervals. Debris is thrown by the brush 106 onto a collecting surface 123 of the belt 122. The belt 122 rotates in a direction counter to rotation of the broom 106 such the collecting surface 123 of the belt 122 is moves at least in part upwards (and typically forwards as well) away from the brush 106, as indicated by the angled arrow located over the belt 122. The debris leaves an exit area 126 at the top of the conveyor 120 and drops into a hopper 127.

[0031] It is well known that debris can escape the brush 106 and conveyor 120 in various ways. In particular, the debris can be ejected out underneath the conveyor 120 or bounce over the top of the brush 106. In the sweeping vehicle 100 according to the present invention, a set of flaps or plates are included to prevent debris from escaping. These flaps include a conveyor flap 130, a cutoff flap 140, and a recirculation flap 150.

[0032] The conveyor flap 130 is mounted adjacent a bottom edge of the conveyor 130. The conveyor flap 130 covers at least in part a collector clearance space 138 defined between the bottom edge and the ground surface 112 along the width of the conveyor 120. The conveyor flap 130 improves the sweeping performance of the sweeper 100 and helps contain dust at least within the enclosed space between the brush 106 and conveyor 120.

[0033] Conceptually, the conveyor flap 130 is a structural element that prevents debris thrown by the brush from colliding with a counter rotating cleat 124 and being batted over the brush 106. The conveyor flap 130 also serves as a device to improve the trajectory of debris so the debris can land on the belt 122 rather than be thrown under the conveyor 120.

[0034] The cutoff flap 140 is mounted above the conveyor flap 130 and forward of the brush 106. In this example, the cutoff flap 140 is attached to the conveyor shroud 142. It is possible to attach the cutoff flap 140 to any structure allowing the flap 140 to be adjacent the brush 106. The cutoff flap 140 includes a distal edge that is adjacent the outer surface of the brush 106 at a cutoff area 144 of the brush 106. The cutoff area 144 is located on a portion of the brush's outer surface that is moving substantially upwards as the brush 106 rotates.

[0035] The recirculation flap 150 is mounted behind the brush 106. The recirculation flap 150 engages the outer surface of the brush 106 at a recirculation contact area 152 of the brush 106. The recirculation contact area 152 is located on a portion of the brush's outer surface that is moving substantially downwards and forwards as the brush 106 rotates.

[0036] Conceptually, the flaps 140 and 150 are structural elements that counteract the trajectory of debris being expelled by the brush 106 or other debris moving device to recirculate/recollect the debris. By forcing the debris back into the brush 106, the debris will not be expelled until it reaches the appropriate collection portion of the brush's rotation (e.g. at the debris collector 120). In broad terms, the flaps 140 and 150 are constructed to provide at least a barrier (deflector) to ejected debris and, in the case of the recirculation flap 150, a bias element to re-introduce the debris into the brush 106.

[0037] Turning now to FIG. 2, a side view of the sweeping system shows the orientation of the flaps 130, 140, 150 relative to the other parts of the vehicle 100. The brush 106 contacts the ground at the contact surface 114 as it is being rotated in the direction indicated by the curved arrow. If there is a large amount of debris, the rotation of the brush 106 at the contact surface 114 may build up a “wedge” 200 of debris as the vehicle 100 moves forward. Most of the debris is thrown upwards in a debris path 202 tangential to the brush 106 where the brush 106 contacts a top portion of the wedge 200. This portion of the debris lands on the belt 122 and is carried into the hopper 127.

[0038] If there is not enough debris to form a wedge 200 of sufficient size, debris can be thrown in a path 204 that is more parallel to the ground surface 112. The debris may shoot forward under the conveyor's lower edge 205. The debris may collide also with a counter-rotating cleat 124 and be batted up and over the brush 106 where it can be left on the ground surface 112 behind the machine 100. Also, since heavier debris (e.g. rocks from 2 cm to 5 cm in diameter) is more prone to travel along the lower path 204, the heavier debris tends to reciprocate in a space between the brush 106 and conveyor 120. The more that debris reciprocates between the brush 106 and conveyor 120, the more likely it is to batted over the brush 106 by a counter-rotating cleat 124 or be launched in a direction (e.g. sideways, backwards) where it is missed by the brush 106 and left on the ground surface 112.

[0039] The conveyor flap 130 has been found to help reduce collisions with counter-rotating cleats and reciprocation of debris between the brush 106 and conveyor 120, as well as preventing debris from being ejected underneath the conveyor 120. The conveyor flap 130 typically includes at least a rigid mounting bracket 230 and a flexible blade or skirt 232. The mounting bracket 230 attaches adjacent to the lower edge 205 of the conveyor 120. The mounting bracket 230 can either be attached to the conveyor 120 or to any part of the surrounding structure. The mounting bracket 230 extends along the width of the conveyor 120 and forms a rigid blocking member in front of and/or below the conveyor 120. The conveyor flap 130 thereby covers the collector clearance space 138 between the ground surface 112 and the conveyor's lower edge 205.

[0040] The conveyor flap 130 may be configured so that a ground clearance gap 234 exists between the flexible blade 232 and the ground surface 112. The ground clearance gap 234 prevents dust and small debris from accumulating on the flexible blade 232 and lessens wear on the flexible blade 232. The flexible blade 232 is compliant enough that material that is larger than the clearance gap 234 will deflect the flexible blade 232 upwards so that debris does not get swept forward by the flexible blade 232, thereby allowing the debris to reach the brush 106.

[0041] It is also known that debris can be carried over the top of the brush 106 such as in a path 240 as indicated in FIG. 2. In prior art sweepers, this debris is usually ejected from behind the brush 106 and therefore missed by the sweeper. By including the cutoff flap 140, the debris is defected substantially downwards so that the debris can be returned to the collection space 242, and eventually be recovered at the conveyor 120.

[0042] The cutoff flap 140 in the illustrated embodiment is formed as an elongated blade fixably attached to an angle bracket 243 and a mounting plate 244. A retainer bracket 246 clamps the cutoff flap 140 to the mounting plate 244. The retainer bracket 246 may have an angular cross section to further stiffen the cutoff flap 140 and angle bracket 243.

[0043] The angle bracket 243 orients the distal end of the cutoff flap 140 to the desired angle relative to the brush 106. The angle bracket 243 also positions the cutoff flap 140 so that there is a gap 248 between a distal edge 247 of the cutoff flap 140 and the outer surface of the brush 106 (i.e. at the tip of the bristles 108). In most applications, the gap 248 is desired to reduce vibrations and wear on the brush 106 and cutoff flap 140. In some applications, however, it may be beneficial to allow the distal edge 247 to touch the brush 106 (i.e. gap 248 measures zero), or arrange the cutoff flap 140 so that the distal edge 247 protrudes through the brush's outer surface to extend into the bristles 108.

[0044] The cutoff flap 140 is preferably made adjustable (e.g. by using elongated mounting slots) thereby allowing the user to adjust the gap 248 to keep it a desired value given various stages of brush wear. The cutoff flap 140 is made from a flexible material, such as rubber or plastic. A cutoff flap 140 using a rigid blade may also be constructed, although the associated gap 248 would typically need to be larger to prevent flap damage due to deflecting large objects or inadvertent contact with the brush 106.

[0045] Debris can also be carried over the top of the brush 106 by being embedded within the bristles of the brush 106 and therefore missed by the cutoff flap 140. This debris can fall off the back end of the brush 106 as it rotates. By including the recirculation flap 150, the debris is deflected back into the bristles 108 at the back end of the brush so that the debris can be carried forward (recirculated) to the wedge 200 and eventually be recovered at the conveyor 120.

[0046] The recirculation flap 150 in the illustrated embodiment includes a flexible mounting flap 250 fixably attached to a chassis bracket 251. The mounting flap 250 allows the recirculation flap 150 to conform to ground surface irregularities so as to prevent breakage of the flap 150. Alternate structural elements may be used in place of a flexible mounting flap 250 to allow conformance of the flap 150, including spring loaded and/or slidable mounts. However, such alternates may be more prone to damage due to chassis movement. The flexible mounting flap 250 allows a flexible and resilient mount that is not easily damaged even when contacting the ground.

[0047] A rigid angle bracket 252 is coupled to the mounting flap 250 and an elongated blade 254. The angle bracket 252 can be incorporated as part of the mounting flap 250 and/or elongated blade 254, or be fabricated as a separate piece as shown. The angle bracket 252 orients the elongated blade 254 so that a portion of the blade 254 is at least touching an outer surface of the brush 106 (i.e. at the tip of the bristles 108) along the brush's width. As shown in FIG. 2, the elongated blade 254 may protrude beneath the outer surface so that a tip 255 of the elongated blade 254 extends into the bristles 108. An additional skirt 222 extends from the mounting flap 210 to close proximity with the ground. The skirt 222 could also be formed by further extending the mounting flap 210 downward.

[0048] A housing 258 typically surrounds the brush 106 and conveyor 120. It is appreciated that the spaces between the rotating brush 106 and the housing 258 are potential escape routes for airborne dust stirred up by the brush's rotation. The conveyor clearance space 138 is another escape route for dust. The flaps 130,140,150 substantially block portions of these spaces and thereby help prevent the airborne dust from escaping. The conveyor flap 130 prevents dust from passing through the collector clearance space 138, the cutoff flap 140 traps dust in the collection space 242, and the recirculation flap 150 prevents dust from passing between the inner surface of the housing 258 and a rear portion of the brush 106. The vehicle 100 may also include a vacuum system 150 (best seen in FIG. 1) to pull dust from inside the housing 258. The flaps 130,140,150 create a restriction of outside air flowing into the housing 258, and thereby help retain the dust in the housing 258 so that it can be more thoroughly removed by the vacuum system 150. Skirt 222 further contains dust and improves the effectiveness of the vacuum system.

[0049] Turning now to FIG. 3, geometric details of the flaps are illustrated. The conveyor flap 130 is mounted adjacent the lower edge of the conveyor 120, typically at an angle 330 ranging between 20 degrees and 70 degrees. If a ground clearance gap 234 (seen in FIG. 2) is included, it measures preferably between 0.75 and 1.25 inches (0.9 and 3.2 cm).

[0050] The cutoff flap 140 is mounted forward of the brush 106 so that the distal edge 247 is adjacent the cutoff area 144. The cutoff area 144 is preferably located at an angle 340 measuring between 45 degrees to 140 degrees (preferably 94 degrees) from the ground contact area 114. For a brush 106 with a nominal outer diameter of 35.5 inches (90.2 cm), this corresponds to locating the distal edge 247 of the cutoff flap 140 about 20.0±1.0 inches (51.0±2.0 cm) above ground. The cutoff flap 140 is typically oriented at a mounting angle 342 measuring between 10 degrees and 30 degrees from horizontal, preferably about 23±1 degrees. In this application, the gap 248 ranges from 0.0 inches to 1.0 inch (2.50 cm) or more, preferably 0.75±0.10 inches (1.91±0.25 cm).

[0051] At the back end of the brush, the recirculation flap 150 contacts the brush 106 at the recirculation contact area 152. The recirculation contact area 152 can be located anywhere the brush's outer surface is moving at least in part downwards. Typically, the recirculation contact area 152 located at a contact angle 350 measuring between 20 degrees to 90 degrees clockwise from the ground contact area 114, preferably 63±2 degrees. For a brush 106 with a nominal outer diameter of 35.5 inches (90 cm), this corresponds to locating the tip 350 of the recirculation flap 150 between 4.1 and 14.7 inches (10 and 37 cm) above the ground, preferably 6.75±0.50 inches (17.1±1.2 cm). The elongated blade 254 is oriented at a mounting angle 352 which is from 0 degrees to 90 degrees from vertical, preferably 50±2 degrees. It is appreciated that the nominal brush diameter of 35.5 inches (90 cm) used in this example is that of an unworn brush 106.

[0052] The construction and attachment of the flaps 130,140, 150 can be accomplished using materials and methods well known in the arts. Typically, the portions of the flaps 130,140,150 adjacent to moving surfaces (e.g. the brush 106, the ground surface 112) are formed a flexible material. In particular, two- or three-ply sheet rubber product such as thick Goodyear Plylon® is suitable for this application. The flaps 130, 140, 150 are typically adjustably fastened to rigid brackets that are bolted or welded to the structures.

[0053] FIG. 4 shows a useful configuration of the conveyor flap 130. The mounting bracket 230 can be formed from sheet metal, in this example {fraction (3/16)} inch (4.8 mm) thick carbon steel. The mounting bracket 230 is formed into a tubular structure which gives it strength to resist damage yet keeps the bracket's weight acceptably low. An equivalent strength aluminum sheet may be used where even lower weight or corrosion resistance is desired. A support blade 402 made of relatively thick rubber (e.g. {fraction (3/16)} inch (4.8 mm) 3-ply rubber) may be sandwiched between the mounting bracket 230 and flexible blade 232, extending out past the mounting bracket 230. The support blade 402 is relatively flexible, yet will not droop down when mounted.

[0054] In this configuration, the flexible blade 232 is mounted on top of the support blade 402 and extends past an edge of the support blade 301. The flexible blade 232 is formed from a relatively compliant belted rubber, such as ⅛ inch thick (3 mm) bias 2-ply belted sheet rubber. The flexible blade 232 may include edge slots 404 evenly spaced along the distal edge 406 of the conveyor flap 140. The slots 404 allow large debris that is passing under the flap 130 to deflect only a small, local portion of the flexible blade 232 so that the remainder of the flexible blade 232 remains substantially undeformed, and therefore the blade 232 can continue to deflect debris back onto the brush 106. The edge slots 404 shown are substantially perpendicular to a distal edge of the conveyor lip 408, although it is appreciated that the slots 404 can be formed at a non-perpendicular angle relative to the distal edge 406.

[0055] The flexible blade 232 and support blade 432 are attached to the mounting bracket 230 by fasteners 408 (e.g. bolts) and a clamping bracket 410. The mounting bracket 230 can be mounted to the vehicle 100 by using fasteners or by other means such as welding. It is appreciated that the flexible blade 232 and/or support blade 402 are removably mounted with bolts 408 at least for maintenance purposes. It may also be desired to remove the blades 232, 402 for certain tasks such as sweeping up leaves or other lightweight debris. More elaborate quick release methods of blade mounting may be used, although inexpensive and reliable fasteners such as bolts 408 are usually sufficient for assembling and attaching the blades 232, 402. It is also appreciated the conveyor flap 130 provides some benefit even with one or both blades 232, 402 removed.

[0056] Referring now to FIG. 5, an embodiment of a cutoff flap 140 is shown. The cutoff flap 140 is 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 cutoff flap 140 from relatively flexible rubber helps prevent damage caused by deflecting heavy objects and inadvertent contact with the brush 106. In another embodiment, the cutoff flap 140 can 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 vehicle 100.

[0057] The cutoff flap 140 can be attached standard fasteners that pass through the retainer bracket 246 (seen in FIG. 2) mounting slots 500 in the flap 140. The retainer bracket 246 can be formed of angled sheet metal to further stiffen the mounting plate 244 and cutoff flap 160.

[0058] Turning now to FIG. 6, an embodiment of a recirculation flap 150 is shown. The mounting flap 250 and elongated blade 254 are typically made of two- or three-ply sheet rubber product such as ⅜ inch (0.95 cm) thick Goodyear Plylon®). Fabricating the mounting flap 250 from relatively flexible rubber helps prevent damage to the blade and/or vehicle caused by heavy objects and ground surface irregularities. Further, use of sheet rubber in fabricating the mounting flap 250 and elongated blade 254 help provide damping of the assembly and reduce noise.

[0059] The mounting flap 250 can be attached to the chassis bracket 251 (best seen in FIG. 2) using standard fasteners through mounting slots 600. The angle bracket 252 can be formed from sheet metal, typically 0.08 inch to 0.12 inch thick (2.0 to 4.5 mm) carbon steel. An equivalent strength aluminum or magnesium material may be used where low weight or corrosion resistance is desired. The angle bracket 252 is fastened to the mounting flap 250 and elongated blade 254 by using fasteners 602. Any type of fastener 602 can be used, such as bolts and/or rivets.

[0060] Although the sweeping system of the present invention has been described in conjunction with a self propelled vehicle 100, it is appreciated that a brush 106, conveyor 120, and flaps 130, 140, 150 can be used alone or in combination on any conveyance, such as trailers or push sweepers. The flaps 130, 140, 150 can also be used on smaller sweeping systems that have alternate conveyor (debris collector) 120 embodiments, such as an auger conveyor or a suction plenum. The flaps 130, 140, 150 can also be used in systems that do not have a conveyor, such as systems that throw the debris directly into a hopper.

[0061] 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.