Abstract:
The present invention is directed to a belt conveyor of the type in which a continuous belt runs along a support duct where the support duct is carried on an undercarriage for raising and lowering movements of a discharge end of the duct and where an input drive member for driving the belt is mounted at or on the undercarriage. At least one idler roller is provided to maintain a predetermined tensioning force to the belt. An accumulator is arranged to contain hydraulic fluid and to maintain the hydraulic fluid at a predetermined set pressure while allowing changes in volume of the hydraulic within the accumulator. The accumulator is connected to at least one cylinder. The cylinder is operatively connected to the idler roller for movement thereof.

Description:
This application is a continuation in part application of application Ser. No. 09/391,666 filed Sep. 7 th  1999 and now abandoned. 
    
    
     The present invention relates to a belt conveyor of the type in which a continuous belt runs along a support duct where the support duct is carried on an undercarriage for raising and lowering movements of a discharge end of the duct and where an input drive member for driving the belt is mounted at or on the undercarriage. 
     BACKGROUND OF THE INVENTION 
     Belt conveyors are well known in which the belt passes through a duct which is usually a cylindrical tube so that the belt is curved as it sits against the lower part of the tube while sliding along the tube. The return run of the belt passes on the outside of the tube and is sometimes, but not always, contained in a housing attached to the lower part of the tube and extending downwardly and outwardly therefrom. At a top end, the belt passes around an idler roller so as to discharge material at the roller where the belt turns to move along the return run. At the lower end there is provided a hopper into which material is fed so as to fall onto the belt in the hopper with the belt being guided around a lower idler roller. 
     Generally the belt is driven by a drive roller located at a point along its length at the return run so that the belt wraps around the drive roller as well as around one or more idler rollers to guide the belt in its movement around the drive roller. 
     The drive roller is located on the underside of the tube at the optional cover. The drive roller is driven generally by a belt which runs from a drive system to the drive roller. 
     The tube carrying the belt is supported on an undercarriage which includes a transverse axle by which the conveyor can be rolled from place to place. A first leg assembly extends from the axle upwardly and this is extendable or moveable so as to raise and lower the upper end of the tube to change the height of the discharge onto the belt. A second leg assembly extends from the axle to the tube at a position adjacent the lower end and the second leg assembly can pivot relative to the tube as the first leg assembly is operated to effect the raising and lowering movement. 
     The simplest undercarriage includes simply two such legs together with a single axle. However more complex undercarriages can be provided. 
     Generally the belt driving the drive roller passes from an input drive system on the undercarriage generally adjacent the axle. The input drive member can comprise simply a PTO input coupling for receiving drive from a tractor. However the system can include a motor so as to avoid the necessity for connection to a drive output of a tractor. The motor can be electric or an internal combustion engine or can be any other suitable source of power. 
     This arrangement has been utilised for many years but the drive belt to the drive roller from the power input is a source of problem in that it requires adjustment and replacement when worn. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to provide an improved belt conveyor and particularly in which the drive system to connect an input drive to the belt is improved. 
     According to one aspect of the invention there is provided a belt conveyor comprising: 
     a continuous belt having a material transportation run and a return run such that movement of the belt along its length causes the belt to move continuously through the transportation run and the return run; 
     a duct for supporting the transportation run of the belt, the duct having a feed end at which material to be transported is deposited onto the transportation run of the belt for movement along the belt and a discharge end at which the material transported by the belt is discharged from the belt; 
     the return run of the belt being guided along an underside of the duct; 
     an undercarriage for supporting the duct and arranged to cause raising and lowering movement of at least the discharge end of the duct; 
     a drive roller in contact with the belt for driving the belt along its length; 
     an input drive member for supplying a drive force for drivingly rotating the drive roller; 
     the input drive member and the drive roller being mounted on the undercarriage at respective positions thereon which remain substantially stationary as the duct is moved in said raising and lowering movement so that the input drive member remains in a fixed position as the duct is moved in said movement and so that the drive roller is fixed relative to the input drive member to receive drive therefrom without necessity for adjustment as the duct is moved; 
     the drive roller being spaced from the return run of the belt on the underside of the duct and the belt including a divergent portion having two runs extending from the return run to and from the drive roller to receive drive therefrom; 
     the undercarriage and the position of the drive roller thereon being arranged such that the length of the divergent portion remains constant as the duct is moved in said movement. 
     Preferably the undercarriage includes a first leg assembly which is of constant length and at a fixed position on the duct and a second leg assembly which is adjustable to cause said movement of the duct, the divergent portion of the belt extending along the first leg assembly from a guide system at an end thereof adjacent the duct to the drive roller adjacent an opposed end of the first leg assembly. 
     Preferably the drive roller is carried on a mounting assembly at the opposed end of the first leg assembly. 
     Preferably undercarriage includes an axle having ground wheels thereon the first and second leg assemblies converge to said axle. 
     Preferably there is provided at least one idler roller at the drive roller around which the belt passes so as to wrap the belt around the drive roller, the idler roller being adjustable in position relative to the drive roller to effect tensioning of the belt. 
     Preferably there are at least three idler rollers arranged to guide the belt from a first contact point on the drive roller partly around the drive roller and back to the same side of the drive roller as the first contact point. 
     Preferably the divergent portion is arranged on the return run at a position spaced from one end so as to define a first portion of the return run and a second portion of the return run, wherein the first leg assembly is pivotal relative to the duct about a horizontal axis at the duct transverse to the duct and wherein the divergent portion is guided at the duct by a first idler roller around which the first portion of the return run is wrapped and two second rollers which guide opposite sides of the second portion to maintain the two runs of the divergent portion spaced and substantially parallel. 
     Preferably the two runs of the divergent portion are contained within a cover assembly along the first leg assembly. 
     Preferably the input drive member comprises a PTO coupling for attachment to a PTO shaft of a drive tractor and wherein the PTO coupling is directly attached to the drive roller such that the PTO coupling is maintained at a fixed position relative to the ground as the duct is moved in said movement. 
     Preferably the input drive member a drive motor which has an output shaft directly connected to the drive roller without intervening drive belts. 
     Preferably the duct comprises a tube. 
     According to a second aspect of the invention there is provided a belt conveyor comprising: 
     a continuous belt having a material transportation run and a return run such that movement of the belt along its length causes the belt to move continuously through the transportation run and the return run; 
     a duct for supporting the transportation run of the belt, the duct having a feed end at which material to be transported is deposited onto the transportation run of the belt for movement along the belt and a discharge end at which the material transported by the belt is discharged from the belt; 
     the return run of the belt being guided along an underside of the duct; 
     an undercarriage for supporting the duct including: 
     a base assembly with ground wheels for movement of the undercarriage across the ground, 
     a first leg assembly having one end pivotally connected to the base assembly and extending therefrom to the duct at a position adjacent to the feed end, the first leg assembly being of constant length, arranged at a fixed position on the duct and pivotally connected to the duct for pivotal movement about a horizontal axis transverse to the duct, 
     and a second leg assembly extending from the base assembly to the duct adjacent to the discharge end and to arranged to cause raising and lowering movement of the discharge end of the duct; 
     a drive roller in contact with the belt for driving the belt along its length; 
     an input drive member for supplying a drive force for drivingly rotating the drive roller, the input drive member and the drive roller being mounted on the undercarriage at said one end of the first leg assembly; 
     the belt including a divergent portion having two runs extending from the return run to and from the drive roller to receive drive therefrom, the divergent portion being guided to run along the first leg assembly from the end thereof at the duct to the drive roller at said one end thereof. 
     According to a third aspect of the invention there is provided a belt conveyor comprising: 
     a continuous belt having a material transportation run and a return run such that movement of the belt along its length causes the belt to move continuously through the transportation run and the return run; 
     a duct for supporting the transportation run of the belt, the duct having a feed end at which material to be transported is deposited onto the transportation run of the belt for movement along the belt and a discharge end at which the material transported by the belt is discharged from the belt; 
     the return run of the belt being guided along an underside of the duct; 
     an undercarriage for supporting the duct and arranged to cause raising and lowering movement of at least the discharge end of the duct; 
     a drive roller in contact with the belt for driving the belt along its length; 
     an input drive member for supplying a drive force for drivingly rotating the drive roller; 
     at least one idler roller at the drive roller around which the belt passes so as to wrap the belt around the drive roller, the idler roller being adjustable in position relative to the drive roller to effect tensioning of the belt; 
     wherein the position of the idler roller is adjusted by a hydraulic cylinder and wherein the hydraulic cylinder is attached to an accumulator of hydraulic fluid arranged to receive a fluid at a predetermined pressure such that the idler roller is pulled in a direction to apply tension to the belt at a predetermined force thus maintaining a predetermined tension in the belt while accommodating changes in belt length. 
     Preferably there are at least three idler rollers arranged to guide the belt from a first contact point on the drive roller partly around the drive roller and back to the same side of the drive roller as the first contact point. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     One embodiment of the invention will now be described in conjunction with the accompanying drawings in which: 
     FIG. 1 is a side elevational view of a conveyor according to the present invention. 
     FIG. 2 is a vertical cross-sectional view of the conveyor of FIG. 1 showing on an enlarged scale the belt drive arrangement at the base of the leg assembly. 
     FIG. 3 is a vertical cross-sectional view of the conveyor of FIG. 1 showing on an enlarged scale the belt guide arrangement at the top of the leg assembly. 
     FIG. 4 is a cross-sectional view along the lines  4 — 4  of FIG.  3 . 
     FIG. 5 is a cross-sectional view along the lines  5 — 5  of FIG.  2 . 
    
    
     DETAILED DESCRIPTION 
     The conveyor arrangement shown in FIG. 1 comprises a duct in the form of a tube or other containment for a belt, the tube being indicated at  10  and the belt being shown at  11 . An undercarriage generally indicated at  12  includes and axle  13  carrying ground wheels  14  by which the structure can be moved from place to place. A first leg assembly  15  extends from the axle to a mounting bracket  16  adjacent an upper end of the tube. The leg  15  in the example shown is foldable at a pivot junction  17  operable by a cylinder  18  connected between brackets  19  and  20  on the leg. Actuation of the cylinder thus extends the leg from a fully folded position as shown in FIG. 1 to a raised position (not shown) in which the leg is fully extended and thus two portions of the leg  15 A and  15 B are in line. Positions intermediate the two extreme positions provided adjustment of the height of the upper end of the tube  10 . The support bracket  21  extends from the axle to a position on the upper portion  15 A of the leg to hold the structure stable when in the folded position shown on FIG. 1 for transportation. 
     The details of the leg  15  comprises one example only and alternative arrangements for raising and lowering the upper end of the tube are well known to one skilled in the art. 
     The leg assembly  15  is formed of two separate leg portions each at a respective end of the axle as indicated at  15 C and  15 D in FIG.  5 . The leg portions thus together define the leg assembly which converges from a wider width at the axle to a narrower width at the bracket  16  so as to support the tube centrally over the axle  13 . 
     A second leg assembly  22  is of a constant or fixed length extending from the axle  13  to a bracket  23  on the tube adjacent the lower end of the tube. Again the leg assembly  22  is formed of two leg portions  22 A and  22 B spaced apart at the axle and converging inwardly towards one another at the bracket  23 . The leg portions are pivotally mounted at the axle  13  and are also pivotally connected to the bracket  23  at the tube. As the leg  15  is thus actuated to raise and lower the tube, the second leg assembly  22  pivots relative to the tube and to the axle to accommodate the changes in angle of the tube. 
     At the upper end of the tube is provided an idler roller  26  around which the belt turns from its drive length or run  11 A within the tube to its return run  11 B underneath the tube. 
     At the bottom end is provided a hopper  27  which is attached to the lower end of the tube and confines material fed into the hopper as indicated at  28  so as to fall onto an exposed lower end portion of the belt which extends beyond the lower end  30  of the tube. The exposed portion of the belt passes around an idler roller  31  so that the drive portion  11 A of the belt lies upwardly within the hopper to receive the material and the return rub  11 B passes underneath the idler roller and back along the underside of the tube. 
     In many cases the return length of the belt is exposed on the outside of the tube. In the embodiment shown, however, the return length  11 B is contained within a cover  32  attached to the underside of the tube  10 . Thus as shown in FIG. 4, the drive run  11 A of the belt sits on the inside surface of the tube  10  at the bottom of the tube. The cover  32  comprises two side walls  33  and  34  which extend vertically downwardly together with sloped side walls  35  and  36  which are attached to the tube at the upper inner end and extend therefrom downwardly and outwardly to the top of the vertical side walls  33  and  34 . A bottom wall closes the cover and contains the belt. 
     As shown in FIG. 3, the belt includes a divergent portion which extends in a loop from the return run  11 B. The divergent loop  40  includes an upper run  40 A and a lower run  40 B. The divergent run or loop is guided at its upper end by three rollers  41 ,  42  and  43  at the bracket  23 . 
     The bracket  23  includes two depending side walls  23 A and  23 B on which the legs  22 A and  22 B of the second leg assembly are pivoted by respective mounting pins  23 C and  23 D. The depending side walls  23 A and  23 B also mount suitable support bearings for the rollers  41 ,  42  and  43 . The upper run of the divergent loop  40  wraps around the roller  41  so as to pass underneath that roller and then along between the leg portions  22 A and  22 B. The lower run  40 B of the divergent loop  40  passes underneath the roller  42  and on top of the roller  43 . Thus rollers  41  and  43  guide the return run  11 B of the belt along the underside of the tube. The roller  42  guides the divergent loop  40  from the return run to hold the upper run  40 A spaced away from the lower run  40 B. The roller  42  further guides the lower run  40 B while accommodating the changes in angle of the leg assembly  22  relative to the bracket  23  by pivotal movement about the pins  23 C and  23 D. 
     At the lower end of the legs  22 A and  22 B, as best shown in FIGS. 2 and 5, there is provided a belt drive system generally indicated at  50 . The belt drive system is mounted in a housing  51  mounted on the second leg assembly  22 . The housing  51  includes a pair of upstanding side plates  52  and  53  each on a respective side of the belt. The side plate  53  is attached to the outside vertical surface of the leg portion  22 B. The side wall  52  is spaced to one side of the side wall  53  by a distance sufficient to receive the belt therebetween. The side walls  52  and  53  extend to a front plate  54 . The side plates extends down to the axle  13 . A bottom plate  55  extends across underneath the bottom of the leg portions  22 A and  22 B and is attached thereto. A top  56  extends from the top surface of the leg portions  22 A an  22 B and thus bridges the top of the loop  40  which is located between the leg portions  22 A and  22 B. The top plate  56  may extend across the full width of the area between the legs or may bridge only the area containing the belt. It will be appreciated that as the legs increase in width from the top at the tube to the axle, the width of the belt completely fills the area between the legs at the top but is relatively narrow in comparison with the space in between the legs at the bottom. 
     At the bottom end of the legs within the housing  51 , the drive system  50  comprises a main drive roller  60  and a plurality of idler rollers  61 ,  62 ,  63  and  64 . It is most convenient to provide four such idler rollers as shown so as to provide effective driving for the belt while wrapping the belt around the majority of the peripheral surface of the main drive roller  60 . The idler rollers and the main drive roller are carried on suitable bearings attached to the side walls  52  and  53 . 
     The main drive roller  60  has a drive shaft  65  which projects through the side wall  52 . In one embodiment the shaft carries a conventional PTO coupling  66  which is thus fixed to the side wall  52  and substantially at a fixed position relative to the axle  13 . The PTO coupling is therefore substantially stationary even as the tube  10  is raised and lowered between the extreme positions. The stationary position is obtained since the distance between the shaft  65  and the axle  13  is relatively small, the leg assembly  22  is relatively long and the amount of movement of the bracket  23  is relatively small. 
     In an alternative arrangement shown in dashed line, the PTO coupling  66  is replaced by a drive motor  66 A of any conventional type. Thus the drive motor can include an electric motor suitably carried at the housing  51  or can comprise an internal combustion engine again mounted on the leg assembly at the lower end. 
     The four idler rollers  61 ,  62 ,  63  and  64  guide the belt from the lower run  40 B under the idler  64 , over the idler  63 , over the idler  62 ,under the idler  61  and onto the top of the roller  60 . From the bottom of the roller  60 , the upper run  40 A extends along the leg assembly back to the top. One of the idlers, in this arrangement the idler  63 , is adjustable by a adjustment device  70  so as to move the position of the idler relative to the other three idlers and the main drive roller to effect tensioning of the complete belt length. Thus the only adjustment for the tensioning of the belt is provided at the idler  63  which is located conveniently at the bottom of the leg assembly  22  within the housing  51 . 
     In one example (not shown) the adjustment device comprises a simple screw tensioner which can be adjusted to apply the required tensioning force. 
     In FIG. 2, the idler roller  63  is attached to the piston rod  71  of a hydraulic cylinder  70  arranged so that the piston applies a pulling force on the roller  63  in a direction to apply a tensioning force to the belt. Thus the position of the idler roller  63  is adjusted by the hydraulic cylinder  70 . The hydraulic cylinder is attached to an accumulator  72  of hydraulic fluid arranged through a port  73  to receive a fluid at a predetermined pressure indicated by a gauge  74 . The accumulator is of a type which is commercially available and well known to one skilled in the art and includes a bladder set at the predetermined pressure while allowing changes in fluid volume within the accumulator to be accommodated such that the idler roller is pulled in a direction to apply tension to the belt at a predetermined force thus maintaining a predetermined tension in the belt while accommodating changes in belt length at that predetermined tension by movement of the cylinder. Such changes in belt length can be caused by material collecting under the belt on the rollers, by changes in temperature and by changes in loading on the belt and all of these changes can be automatically accommodated by the cylinder without manual adjustment. 
     Thus the main belt of the conveyor is directly driven by the drive system at the bottom of the second leg assembly so that direct driving of the belt is convenient for direct connection to a motor or to a PTO shaft as previously described. There is no necessity for extra drive belts which can stretch and wear. 
     Since various modifications can be made in my invention as herein above described, and many apparently widely different embodiments of same made within the spirit and scope of the claims without department from such spirit and scope, it is intended that all matter contained in the accompanying specification shall be interpreted as illustrative only and not in a limiting sense.