Abstract:
A device for controlling the conveyance of particulate material on a conveyor belt comprises a frame with an endless belt attached thereto. The apparatus is positioned above the conveyor belt and in frictional contact therewith whereby the motion of the conveyor results in motion of the endless belt on the apparatus. The particulate material thereby is passes between the endless belt and the conveyor belt and any bouncing movement of such material is prevented. Use of the present invention on conventional conveyor belts controls the dispersion of the particulate material carried thereon and allows for the speed of the conveyor to be increased. The present invention is suitable for use with a conveyor apparatus used with a truck and commonly known as a “stone slinger”.

Description:
This application is a continuation application of U.S. patent application Ser. No. 09/870,695 filed Jun. 1, 2001, now issued under U.S. Pat. No. 6,625,976, which is a continuation-in-part application of U.S. patent application Ser. No. 09/210,745 filed Dec. 15, 1998, now U.S. Pat. No. 6,241,076, the entire contents of both of which are incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a device which attaches to a conveyor belt and which controls the conveyance of particulate matter along such belt. 
     BACKGROUND OF THE INVENTION 
     Conveyors for moving particulate material such as stone, sand or gravel can be found in various applications. A truck with a conveyor apparatus as known in the art is disclosed in U.S. Pat. No. 5,190,432. This patent discloses an optional attachment for a standard dump truck that includes a swing arm, pivotally connected to the truck&#39;s chassis, an elongated frame pivotally connected to the swing arm and mounting an endless conveyor belt. 
     Another application where conveyors are used to move particulate material is a stone slinger. A stone slinger includes a first conveyor that receives material from a hopper, which is located behind the cab of a truck. The first conveyor moves the material onto a second conveyor. The second conveyor then sprays the material from the back end of the truck. 
     Stone slingers are used so that the particulate material can be projected from the rear of a dump truck or similar device to a desired location. The slinger has a limited dispensing range that is determined by the speed of the conveyor. 
     Material is usually dumped onto the conveyor from a hopper or another conveyor. The method in which the material is loaded onto the conveyor from the truck causes it to bounce along the conveyor rather than rest on it. This can cause some material to be projected from the conveyor prematurely in all directions. This creates a hazard to anyone standing in the vicinity of the slinger. An increase in the conveyor speed causes further erratic discharge of material. Therefore, the speed of the conveyor is limited thereby limiting the discharge range of the slinger. 
     Some attempts have been made to control the premature and erratic discharge of material from the conveyor. In one such method, the material is sandwiched between the conveyor belt and a cover that is made of relatively light material such as sheet metal. The cover lies flat on the belt, while maintaining its horizontal position, and is temporarily displaced as the material passes underneath it. This method does not effectively control the erratic and premature discharge of material. 
     Thus, a need exists for a device for controlling the erratic dispersion of particulate material being conveyed on a conveyor belt. Such a device would reduce any impediment in increasing the speed of the conveyor belt and, thereby, allow material to be ejected farther. 
     SUMMARY OF THE INVENTION 
     In general terms, the present invention provides, in one embodiment, an apparatus for controlling the conveyance of particulate material on a first conveyor belt, the first conveyor being driven by a driving means, the apparatus comprising: 
     a) a frame having at least one longitudinal member; 
     b) at least two rotating elements spaced apart along the frame; and, 
     c) an endless belt extending around the rotating elements; 
     the apparatus being positioned above and proximal to the first conveyor, wherein the endless belt extends along a portion of the first conveyor and wherein the particulate material flows between the endless belt and the first conveyor and whereby the endless belt is frictionally driven by the first conveyor belt. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other features of the preferred embodiments of the invention will become more apparent in the following detailed description in which reference is made to the appended drawings wherein: 
     FIG. 1 shows a stone slinger truck in accordance with the prior art with a safety apparatus 
     FIG. 2 is a side view of a safety apparatus in accordance with an embodiment of the invention 
     FIG. 3 is a front view of the apparatus of FIG. 2 
     FIG. 4 is a detailed view of the apparatus of FIG. 2 
     FIG. 5 is a view on A—A of FIG. 4 
     FIG. 6 is a side view of the safety apparatus in accordance with another embodiment of the invention 
     FIG. 7 is a front view of the apparatus of FIG. 6 
     FIG. 8 is a view of the opposite side of the apparatus of FIG. 6 
     FIG. 9 is a view on B—B of FIG.  8 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIG. 1, a prior art stone slinger truck is generally shown at  10 . The truck includes an endless thrower belt  12 , that is attached to the vehicle and is supported by a frame  50 . The truck includes a drive means (not shown) to power the belt so as to move particulate material (not shown) deposited onto the belt from the truck bed  14  or from a hopper. Material may be deposited onto the belt directly from the truck bed  14  or an additional conveyor  54  may operate between the truck bed  14  and the belt  12  to transfer the material. The thrower belt  12  may be either smooth or ribbed. 
     Referring to FIG. 2, the apparatus of the invention is generally shown at  11 . The apparatus includes an endless belt  16  located above the thrower belt  12  and adjacent to the outlet of the truck bed or hopper  14 . In a preferred embodiment the endless belt  16  is approximately the same width as the thrower belt  12 . In one embodiment, the endless belt  16  has ribs  30  located on the outer surface thereof and that run transverse to the direction of travel  32 . The ribs  30  assist in frictionally engaging the endless belt  16  and the thrower belt  12 . When the thrower belt  12  is in motion it drives the endless belt  16  as a result of the frictional engagement between the belts  12  and  16 . In another embodiment, the endless belt  16  may be smooth while still maintaining the frictional engagement with the thrower belt  12 . The frictional engagement may result from direct contact between the belts  12  and  16  or indirect contact, where the particulate material that is passing between the belts  12  and  16  transfers the motion from the thrower belt  12  to the endless belt  16 . 
     The endless belt  16  extends around at least two pairs of wheels  22  rotatably attached to axles  24  mounted on opposite ends of a frame  54  which preferably comprises two longitudinal frame rails  20  extending along the length of endless belt  16 . In a preferred embodiment, the apparatus of the invention includes a plurality of pairs of wheels  22  positioned along the length of the belt  16  so as to provide adequate support therefor. The number of additional wheels  22  and axles  24  between the ends of the endless belt  16  will vary depending on the size of the endless belt  16 . In another embodiment, the wheels may be replaced with rollers. In yet another embodiment, the frame rails  20  may be replaced by a single longitudinal frame rail  20 . 
     In a preferred embodiment, the endless belt  16  includes two rows of inner knobs  26  provided on the inner surface of the belt and along the length thereof. The knobs  26  are arranged so as to form two channels running longitudinally along the belt thereby providing a groove for the wheels  22 . The channels formed by the knobs  26  thereby serve to maintain the belt in alignment with the wheels. It will be appreciated that various other arrangements are possible for maintaining the belt  16  in the desired alignment. 
     In a further preferred embodiment, the apparatus of the invention,  11 , is kept from moving in the direction of travel  32  by a pivoting linkage  28 . The linkage can be attached to any stationary part of the slinger such as the frame  50 . The other end of the linkage  28  is attached to the side rails  20 . It will be apparent that any other attachment means may be used. 
     In a further preferred embodiment, a support  19  may be detachably fixed to the frame  50 . The support is U-shaped and extends across the top of the apparatus  11  and attaches to the frame  50  on both sides. In a preferred embodiment, depth stops, or ledges,  52  are located on either side of the support  19  adjacent to the frame rails  20 . The depth stops  52  are provided for supporting the apparatus  11  of the invention so that the full weight of the apparatus is prevented from resting on the thrower belt  12 . In addition, the support  19  restricts the vertical movement of the apparatus  11  so that it can only deflect a predetermined distance. In another embodiment, the depth stops may be omitted thereby allowing the thrower belt  12  to support the full weight of the apparatus  11 ; however, such an arrangement may lead to excessive wear or contortion of the belt  16  of the conveyor apparatus  11 . This problem may be averted by reinforcing the belt  16  to prevent bending thereof. 
     In a further preferred embodiment, a shield  18  is located on top of the belt  16 . The rear end of the shield  18  is adjacent to the hopper  14  and the forward end of the shield  18  may overhang the belt  16  by several inches to control any kickback of material. The shield  18  is attached to the frame rails  20 . The shield  18  may have side guards  17  as shown in FIG. 3, and which have been omitted from FIG. 2 for clarity. 
     Referring to FIGS. 4 and 5, the pivoting linkage  28  is comprised of one link  38 , which is attached to the conveyor assembly  11  at ball joints  44  and  46 . Ball joint  44  is attached to the frame rail  24  and ball joint  46  is attached to the arch frame  19 . The joints are in the same horizontal plane, although this is not necessary. The link  38  can rotate freely about both joints  44  and  46 . 
     Now that the apparatus has been described, the mode of operation of the device will now be described. 
     The thrower belt  12  is set in motion by the driving means of the truck. Particulate material is released onto the thrower belt  12 . The material is carried along the thrower belt  12  and underneath the endless belt  16 . 
     The thrower belt  12  frictionally engages the outer ribs  30  of the endless belt  16  so that material passes between the two belts. In the preferred embodiment, the frame rails  20  keep the axles  24  aligned and the inner knobs  26  on the belt  16  keep it located with respect to the wheels  22 . This configuration acts to keep the belt  16  in line with the thrower belt  12  as material passes under it. 
     As the material is passed between the two belts it is forced to settle on the thrower belt  12  instead of bouncing around, as it would normally do. The shield  18  that is located on top of the belt  16  may overhang the conveyor slightly. Although this is not essential, it is useful in order to deflect any material that may be stuck in the belt  16  and carried partway around before flying off. The shield  18  also ensures that any stones that are carried the entire way around stay on the belt  16 . 
     The conveyor assembly  11  is equipped with a pivoting linkage  28  that allows temporary raising of the assembly  11  when large material passes between the belts  12  and  16 . The pivoting linkage  28  is attached to a stationary part of the slinger such as the frame  50 , in one embodiment, and the frame rails  20 . The maximum vertical deflection of the conveyor assembly  11  is controlled by the support  19 , which the conveyor assembly  11  cannot deflect beyond. The ability of the belt  16  to deflect vertically is useful when large particulate material is encountered. 
     It will be apparent to those skilled in the art that the apparatus of the invention can be utilized with any conveyor and with a variety of material. For example, particulate material may include sand, gravel, salt, rock etc. The conveyor may be associated with trucks (as described above) or with mining, equipment, farming equipment etc. 
     In a further preferred embodiment, shown in FIG. 6, a hydraulic motor  59  is bolted to frame rails  20  and connected to a drive axle  62  and two drive wheels  58 , which replace the front pair of wheels  22 . A series of hydraulic lines (not shown) connect hydraulic motor  59  with the same drive means (not shown) that powers belt  12 . The hydraulic motor  59 , thus drives the belt  16  on the wheels  22  to assist the conjoint movement of belts  12  and  16 . This embodiment is useful when conveying particulate materials to a higher elevation. In the previous embodiment, the endless belt  16  is driven by frictional engagement between belt  16  and thrower belt  12 , and slippage between these two belts may occur when frame  50  is elevated above a certain angle to convey particulate material to a higher elevation. In order to inhibit this slippage, the hydraulic motor  59  connected to the drive axle  62  and the two drive wheels  58 , will power the operation of belt  16  independent of any frictional engagement between belts  16  and  12 . Further, since hydraulic motor  59  is connected to the drive means that powers belt  12  by hydraulic lines, the drives may be arranged so that the two belts  16  and  12  will run at the same speed. 
     As a further alternative, either in combination with the motor  59  or in the arrangement of FIGS. 1-9, the frictional engagement between belts  12  and  16  may be increased by a tensioning member  60 , one end of which is connected to frame  20 , and the opposite end of which is connected to arch frame  19  as shown in FIGS. 6 and 8. Adjustment of the tensioning member will increase or decrease the normal forces acting between the belts  12 ,  16 , thereby varying the frictional engagement. 
     In a further embodiment, nylon wear plates  17 , shown in FIGS. 7 and 9, may be used to reduce the wear on the sides of the shield  18  and also help reduce the noise generated by apparatus  11  when it is in operation. 
     Outer deflectors  57  may also be mounted at either or both ends of shield  18  to minimize wet or sticky particulate material from being projected erratically due to the material adhering to belt  16  upon discharge of the material at the front of apparatus  11  or the kickback of any material at the rear of the apparatus  11 . The shield  18  may also have at least one angle rubber  55 , held by bracket  56 , at the rear end of apparatus  11  to help the particulate material from bouncing away before being carried along the thrower belt  12  and underneath the endless belt  16 . 
     Although the invention has been described with reference to certain specific embodiments, various modifications thereof will be apparent to those skilled in the art without departing from the spirit and scope of the invention as outlined in the claims appended hereto.