Abstract:
A flexible endless belt mountable on rotating elements has an outer and inner surface between first and second lateral edges and a plurality of longitudinally spaced-apart laterally oriented upraised flights on the outer surface. Each flight has a single medial portion offset in a rearward longitudinal direction from portions of the flight immediately lateral to the medial portion. Protrusions on the inner surface engage the rotating elements for endlessly rotating the endless belt in a forward longitudinal direction. Such an endless belt is particularly useful on a control apparatus for a stone slinger.

Description:
FIELD OF THE INVENTION 
   The present invention is related to endless belts, preferably endless belts for assisting in transporting particulate material. 
   BACKGROUND OF THE INVENTION 
   Conveyors for moving particulate material, such as stone, gravel, sand, and the like, are known in the art. Such conveyors, commonly called “stone slingers”, generally comprise a thrower belt mounted on a truck, the truck having a storage hopper for holding the particulate material. Particulate material is dispensed from the hopper on to the thrower belt and then transported along the thrower belt to be deposited in a desired locating remote from the truck. 
   Particulate material on the thrower belt has a tendency to bounce around and be thrown off in a premature and/or erratic manner. To control the flow of particulate material on the thrower belt, an endless belt positioned above the thrower belt may be used. Such an arrangement is disclosed in U.S. Pat. No. 6,241,076 issued Jun. 5, 2001, U.S. Pat. No. 6,615,976 issued Sep. 9, 2003 and U.S. Pat. No. 6,695,125 issued Feb. 24, 2004. While use of such an endless belt has improved control over particulate material on the thrower belt, there remains a need for an improved belt, particularly for such a use. 
   Various types of endless belts for various purposes are known in the art. For example, United States Publication 2002/0175055 published Nov. 28, 2002 discloses a conveyor belt having V-shaped grooves for transporting particulate material. This belt is designed to actually carry particulate material, hence the troughing of the belt, and would be poorly effective in a control apparatus for a stone slinger. U.S. Pat. No. 6,371,280 issued Apr. 16, 2002 discloses a conveyor belt having “wavy” flights for use on a crop baler. This belt is designed to grip a bale of crop. If used in a control apparatus on a stone slinger, the “waviness” of the belt would detrimentally affect object control as it would permit objects to escape off the sides of the thrower belt and objects would collect in several regions rather than just one. U.S. Pat. No. 6,644,463 issued Nov. 11, 2003 disclose a conveyor belt with two flights that are laterally spaced apart thereby having a gap in the middle. Such a belt is designed to carry objects, not control objects from above. If used on a control apparatus for a stone slinger, this belt would allow objects to slip back through the gap thus losing throwing effectiveness and control. Thus, the aforementioned belts are not well suited for use on a control apparatus positioned above particulate material for controlling particulate material on a thrower belt of a stone slinger. Furthermore, these belts, and other conveyor belts like them are flat on the underside and do not have means on the underside to permit engagement with rotational elements. 
   SUMMARY OF THE INVENTION 
   There is provided a flexible endless belt mountable on rotating elements comprising: an outer and inner surface between first and second lateral edges; a plurality of longitudinally spaced-apart laterally oriented upraised flights on the outer surface, each flight having a medial portion offset in a rearward longitudinal direction from portions of the flight immediately lateral to the medial portion; and, engagement means on the inner surface for engagement with the rotating elements for endlessly rotating the endless belt in a forward longitudinal direction. 
   Since the medial portion of the flight is rearwardly offset from the portions immediately lateral to it, the flight forms a natural “cup” that helps brings objects towards and holds objects in a central region of the belt. When the endless belt is disposed above a conveyor belt, for example a conveyor belt of a stone slinger, such an arrangement of flights on the endless belt provides much better control of objects being transported on the conveyor belt. Premature and erratic discharge of objects is greatly reduced as the objects are guided toward and held in the center of the conveyor belt by the endless belt. 
   Preferably, each flight extends laterally across the outer surface from the first lateral edge to the second lateral edge, thereby spanning the entire width of the endless belt. This helps ensure that objects at the very edges of the endless belt are guided towards the central region. Each flight has only one “cup” so that all of the objects collect in a single region, i.e. the central region, to ensure tighter control over objects being transported on the conveyor belt. Further, the flight at both the first and second lateral edges is forwardly offset from the medial portion so that objects on the conveyor belt are not thrown off one or both sides of the conveyor belt. The flights may be, for example, arcuate or chevron-shaped. Preferably, the flights are chevron-shaped with the vertex of the chevron pointing rearwardly against the direction of travel of the endless belt, and thus against the direction of flow of the objects on the conveyor belt. Preferably, each chevron-shaped flight extends from one lateral edge to the other with a single vertex pointing rearwardly. 
   Each flight has a leading edge and trailing edge extending laterally on the outer surface of the belt. The leading edge is longitudinally forward of the trailing edge, that is, the leading edge is in the direction of travel of the belt. In a preferred embodiment, the leading edge forms a first angle with the outer surface that is steeper than a second angle formed between the trailing edge and the outer surface. Thus, the flight is less sloped on the leading edge than the trailing edge and the flight is more capable of cupping objects without bending or breaking due to back-jamming of objects. To further mitigate against bending or breaking, the flight preferably has a middle portion that is thicker than the end portions, the end portions being laterally offset from the middle portion. Since the middle portion is the place where back-jamming is most likely to occur, a thicker middle portion considerably reduces the possibility of damage to the flight. 
   Each flight is also preferably higher at the middle portion than at the end portions. Such an arrangement is particularly advantageous since conveyor belts transporting objects are often channeled or sloped toward the center. Having flights on the endless belt that are higher at the middle portion means that the flight can extend farther into the sloped channel of the conveyor belt over which the endless belt is positioned. The flight of the endless belt more closely follows the contour of the conveyor belt thereby maintaining better control over objects on the conveyor belt. 
   Preferably, each flight has a top that is flat along at least part of the middle portion and that is parallel to the outer surface of the endless belt. The top of each flight tapers downwardly from the middle portion towards the lateral edges. Thus the height of the flight is greater at the center of the endless belt than at the edges. Flat middle portions provide greater stability to the endless belt when resting on a flat surface since the belt is not resting on a peak. 
   The outer surface of the endless belt preferably has a central region between two lateral regions, the central region being depressed in respect of the lateral regions. The depression is preferably slight, for example from 0.0625 inch to 0.25 inch deep, preferably about 0.125 inch. The depression assists in guiding objects from the lateral regions into the central regions where the objects are more tightly controlled. 
   The outer surface of the endless belt may have a plurality of laterally extending grooves between the flights. Such grooves permit the belt to flex more easily as it rides on the objects on the conveyor belt. The ability to flex is particularly important when the endless belt encounters an unusually large object. Easier flexing reduces the likelihood of delamination and tearing of the belt. 
   The flights of the endless belt bound spaces between them that are not partitioned into compartments, that is, there is no blockage from the first lateral edge to the second lateral edge in the space between two flights. Therefore, objects in the lateral region at the very edge of the endless belt can be guided without obstruction into the central region where control can be more easily maintained over the object. 
   The inner surface of the endless belt comprises engagement means for engaging the rotating elements to endlessly rotate the endless belt in a forward longitudinal direction. The forward longitudinal direction is the direction of motion of the surface of the endless belt that is in contact with the objects, which is also the direction of motion of the objects on the conveyor belt. Any suitable engagement means may be used. Selection of the type of engagement means depends on the type of rotating elements. In one embodiment, the rotating elements are preferably wheels having sprockets elements attached thereon. The inner surface of the endless belt rides on the wheels and the engagement means engages the sprocket elements. Where sprocket elements are used, the engagement means may be, for example, protrusions on the inner surface of the endless belt. The size and shape of the protrusions are designed to efficiently engage the sprocket elements. Protrusions may be aligned in longitudinal rows. Preferably, there are two or more spaced-apart longitudinal rows. Preferably the two or more spaced-apart longitudinal rows are laterally-aligned so that the protrusions are aligned both longitudinally and laterally. More preferably, there are four spaced-apart longitudinal rows of protrusions. 
   Alignment of the endless belt on the rotating elements may be maintained by alignment means. Alignment means may be part of the rotating elements, part of a frame on which the rotating elements are mounted, and/or part of the endless belt itself. Preferably, the inner surface of the endless belt comprises the alignment means. In one embodiment, the alignment means may be protrusions on the inner surface that prevent the belt from slipping sideways off the rotating elements. Where the rotating elements are wheels or wheels together with attached sprocket elements, the protrusions are preferably laterally inward from the wheels. Laterally inward means closer to the center of the endless belt. Preferably, there are no protrusions laterally outward of the wheels so that the lateral edges of the endless belt can bend inward to accommodate larger objects without interfering with the motion of the wheels. This reduces chatter and reduces belt wear. Protrusions may be aligned in longitudinal rows. Preferably, there are two or more spaced-apart longitudinal rows. Preferably the two or more spaced-apart longitudinal rows are laterally-aligned so that the protrusions are aligned both longitudinally and laterally. More preferably, there are four spaced-apart longitudinal rows of protrusions. 
   In a preferred embodiment, the rotating elements are wheels having sprocket elements attached laterally inwardly thereon and the same protrusions on the inner surface of the endless belt function as both the engagement means and the alignment means. Each sprocket element engages one longitudinal row of protrusions. Since the longitudinal row of protrusions engaged by the sprocket elements is immediately laterally inwardly proximal the wheel to which the sprocket elements are attached, the longitudinal row of protrusions also acts to prevent the endless belt from slipping inwardly. Two such arrangements, one proximal the first lateral edge of the endless belt and the other proximal the second lateral edge, keep the endless belt aligned on the wheels. 
   The wheels may be driven by a driving means, for example a motor, preferably a hydraulic motor, thus driving the sprocket elements attached to the wheel and the endless belt engaged with the sprocket elements. In an embodiment having four laterally-aligned spaced-apart longitudinal rows of protrusions, two of the longitudinal rows may be closely spaced near the center of the endless belt so that a third wheel in the center may be used as either an idler wheel or a driving wheel for better tracking and/or extra drive. 
   The endless belt may comprise any suitably flexible material that is strong enough to withstand the forces involved in moving the objects on the conveyor belt. Preferably, the endless belt comprises a natural or synthetic rubber or elastomer. More preferably, the endless belt comprises a cloth casing laminated between layers of rubber. The flights on the outer surface and the engagement means and alignment means on the inner surface may be separate pieces attached to the endless belt, for example by screws, rivets and the like, or they may be a unitized part of the endless belt. Preferably, the endless belt is molded with the flights, engagement means and alignment means being integrally molded with the outer and inner surfaces. Preferably, the lateral edges of the endless belt are also molded to seal the cloth casing between the layers of rubber. 
   Objects that may be transported on a conveyor belt and controlled on the conveyor belt by an endless belt of the present invention are any relatively solid object, for example, vegetables (e.g. beans, potatoes, etc.) and particulate matter (e.g. stones, sand, rocks, gravel, etc.). Endless belts of the present invention are preferably used on control apparatuses for conveyors of particulate material (e.g. stone slingers). Such control apparatuses are described in U.S. Pat. No. 6,241,076 issued Jun. 5, 2001, U.S. Pat. No. 6,615,976 issued Sep. 9, 2003 and U.S. Pat. No. 6,695,125 issued Feb. 24, 2004, the disclosures of which are herein incorporated by reference in their entirety. The endless belt of the present invention advantageously provides unexpected improvement in the control of larger volumes of objects, in the control of a greater selection of object shapes, in the control of objects in a wider variety of weather conditions, or in any combination of the above. In the case of stone slingers, increased control over objects on the conveyor belt leads to an advantageous improvement in throw distance and accuracy. 
   Further features of the invention will be described or will become apparent in the course of the following detailed description. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In order that the invention may be more clearly understood, embodiments thereof will now be described in detail by way of example, with reference to the accompanying drawings, in which: 
       FIG. 1  is a top perspective view of a section of an endless belt of the present invention; 
       FIG. 2  is a bottom perspective view of the section of the endless belt depicted in  FIG. 1 ; 
       FIG. 3  is a top plan view of the section depicted in  FIG. 1 ; 
       FIG. 4  is a schematic end cross-sectional view taken through one flight of the section of the endless belt depicted in  FIG. 1 ; 
       FIG. 5  is a schematic side view of the section of the endless belt depicted in  FIG. 1 ; and, 
       FIG. 6  is a schematic side view of an endless belt mounted on wheels. 
   

   DESCRIPTION OF PREFERRED EMBODIMENTS 
   Referring to  FIG. 1 , a section of endless rubber belt  10  comprises outer surface  11  and inner surface  12 . Molded integrally with outer surface  11  are a plurality of longitudinally spaced-apart laterally oriented upraised chevron-shaped flights  20  (four shown and one labeled) extending across the width of the belt from first lateral edge  13   a  to second lateral edge  13   b . Forward longitudinal direction (i.e. direction of travel) of the endless belt is shown by arrows  14  molded into outer surface  11 . A plurality of laterally-extending grooves  15  (only one labeled) between flights  20  permit the belt to flex more readily without breaking or delaminating. First and second lateral regions  16   a , 16   b  of the endless belt are 0.125 inch higher than central region  17 , the central region being depressed relative to the lateral regions as better illustrated in  FIG. 4 . Lateral edges  13   a , 13   b  are integrally molded with the rubber outer and inner surfaces to seal the cloth casing of the belt between the outer and inner rubber surfaces. The space between flights  20  do not contain any obstructing walls or partitions so that there is an open channel from first lateral edge  13   a  to second lateral edge  13   b  between two flights. 
   Referring to  FIG. 2 , a bottom perspective view of the section of endless belt  10  depicted in  FIG. 1  illustrates four laterally-aligned spaced-apart longitudinal rows of protrusions  18   a , 18   b , 18   c , 18   d  integrally molded with inner surface  12 . Row of protrusions  18   a  functions as engagement means and alignment means in respect of wheels near one lateral edge and row of protrusions  18   d  functions as engagement means and alignment means in respect of wheels near the other lateral edge. Rows of protrusions  18   a , 18   d  would be laterally inward of their respective wheels. Rows of protrusions  18   b ,  18   c  would bracket and/or engage a single wheel proximal the center of the belt, if desired. 
   Referring to  FIG. 3 , a top view of the section depicted in  FIG. 1  more clearly shows the chevron shape of flights  20  on outer surface  11  of endless belt  10 . Vertices  21  (only one labeled) on trailing edges  22  (only one labeled) of flights  20  point against the direction of travel of endless belt  10  as represented by arrows  14  (only one labeled) molded into outer surface  11 . Objects being controlled by endless belt  10  are guided into central region  17  by the chevron-shape of flights  20  and the difference in height between lateral regions  16   a , 16   b  and central region  17  where they are cupped in the “V&#39;s” of leading edges  22  (only one labeled) of the flights. Ridges  19  illustrate the boundary between lateral regions  16   a , 16   b  and central region  17 . 
   Still referring to  FIG. 3 , each flight  20  is longitudinally thinner in lateral regions  16   a , 16   b  near lateral edges  13   a , 13   b  than in central region  17  near the center of the belt. Making flights  20  thicker in the central region provides reinforcement to the flights to reduce the possibility of the flights bending or breaking when objects are jammed against the flights. Laterally-extending grooves  15  (only one labeled) between flights  20  permit the belt to flex more readily without breaking or delaminating in response to larger objects. 
   Referring to  FIG. 4 , a schematic end cross-sectional view of the section of endless belt  10  illustrates the profile of a flight  20  from the rear. Top  24  in a medial portion  25  of flight  20  is flat and parallel to outer surface  11 . Top  24  tapers downwardly in end portions  26   a ,  26   b  towards lateral edges  13   a ,  13   b . Thus, the medial portion of each flight is higher than the laterally offset end portions. Central region  17  on outer surface  11  is depressed by 0.125 inch in relation to lateral regions  16   a ,  16   b . Inner surface  12  comprises four integrally molded laterally-aligned spaced-apart longitudinal rows of protrusions  18   a ,  18   b ,  18   c ,  18   d . Cloth casing  30  is laminated between rubber outer surface  11  and rubber inner surface  12  and sealed within endless belt  10  by integrally molded rubber lateral edges  13   a ,  13   b.    
   Referring to  FIG. 5 , a schematic side view of endless belt  10  illustrates the side profile of flights  20  (only one labeled) and protrusions  18   a , 18   b , 18   c , 18   d  (only  18   a  shown and only one labeled). Endless belt  10  is depicted in operating position above a conveyor belt (not shown), therefore the flights are depicted below the protrusions.  FIG. 6  shows the endless belt mounted on wheels in the operating position. Forward longitudinal direction and direction of flow of objects is depicted by arrow A. 
   Still referring to  FIG. 5 , trailing edge  22  and leading edge  23  of flight  20 , form angles P and Q, respectively, with normal X perpendicular to outer surface  11  and direction of flow A. Angle Q is set to provide effective trapping of objects against leading edge  23  and is preferably within a range of from about 5° to about 15°, more preferably about 10°. Angle P is set to provide effective reinforcement of flight  20  at trailing edge  22  and is preferably within a range of from about 20° to about 60°, more preferably about 30°. Thus, leading edge  23  forms a steeper angle than trailing edge  22  with respect to outer surface  11 , which makes flight  20  more effective at trapping objects at the leading edge while providing better reinforcement at the trailing edge. 
   Still referring to  FIG. 5 , protrusion  18   a  has angled edges and a flat top. The edges form angles S and R with normal Y perpendicular to inner surface  12  and direction of flow A. Angles S and R may be the same or different and are set to efficiently engage sprockets on rotating elements driving the belt. Angles S and R are preferably in a range of from about 20° to about 30°, more preferably about 25°. Angles S and R are preferably the same. 
   Referring to  FIG. 6 , endless belt  10  having a plurality of flights  20  on outer surface  11  and longitudinal rows of laterally-aligned spaced-apart protrusions  18   a  (only one row shown) on inner surface  12  is mounted on sets of wheels  41 , 42 , 43 . The sets of wheels are mounted on laterally extending axles  44  (only one labeled) mounted on a pair of longitudinal frame elements  45  (only one shown) of a frame. Sets of wheels  41  and  43  comprise two or more laterally space-apart wheels, one wheel located near one lateral edge of the belt and another wheel located near the other lateral edge of the belt. Set of wheels  42  may comprise one wheel or two or more laterally spaced-apart wheels. Endless belt  10  is driven in direction A by engagement of the longitudinal rows of protrusions with sprockets attached to the wheels of one or more of the sets of wheels. At least one set of wheels has drive wheels while the others may have drive or idler wheels. The drive wheels are driven by a motor or motors (not shown), preferably a hydraulic motor. 
   Other advantages which are inherent to the structure are obvious to one skilled in the art. The embodiments are described herein illustratively and are not meant to limit the scope of the invention as claimed. Variations of the foregoing embodiments will be evident to a person of ordinary skill and are intended by the inventor to be encompassed by the following claims.