Abstract:
A sweep auger having an auger that is rotated about its longitudinal axis by a power means and a drive assembly having at least three reduction gears that operatively connect the auger to a drive wheel such that the drive wheel rotates at a speed that is substantially less than the rotational speed of the auger.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    This invention relates to an auger apparatus, and more particularly to sweep augers suitable for moving granular material across the floor of a circular storage bin toward the center of the bin.  
           [0002]    Sweep augers have long been used to unload grain or other granular material from circular storage bins. In such apparatus, a radially disposed auger rotates about its own axis to drag the granular material to an unloading sump at the center of the bin. Simultaneously, the auger revolves around the central vertical axis of the bin to advance across the bin floor in a sweeping action. The auger shaft typically is rotated by power means connected to the radially inner end of the shaft. A drive wheel often is attached to the radially outer end of the auger shaft for rotation therewith to support the outer portion of the auger, as well as to assist in driving the auger in its sweeping motion. While such arrangements provide for ease of manufacturing, certain operating and other disadvantages are inherent in the equipment. Auger shafts typically rotate at several hundred revolutions per minute to achieve the desired unloading capacity. However, this results in a peripheral velocity of the support wheel which is far greater than the rate of advancement of the outer end of the auger and hence of the wheel. This results in excessive slippage of the wheel on the support floor. Hence, the drive wheel wears out quickly if its periphery is made of rubber or other relatively soft traction material, as is desirable to provide sufficient frictional engagement with the steel bin floor to accomplish the sweeping motion. On the other hand, if the drive wheel periphery were made of steel or other hard material, the wheel often would not provide adequate traction for satisfactorily advancing the auger into the granular material, and would wear the bin floor.  
           [0003]    In the past, the aforesaid disadvantages have been overcome or minimized only with more complex apparatus and at considerably greater expense. In one such instance (see U.S. Pat. No. 3,127,032) a separate drive shaft extends coaxially through the auger shaft and drives a sprocket at a rotational speed independent of the speed of the rotating auger, the sprocket engaging a circular perforated track to provide a positive drive during the sweeping action. In other instances, auxiliary motors have been provided to drive sprockets or gears which similarly engage circular tracks to effect a positive drive for sweeping (see e.g., U.S. Pat. Nos. 3,356,235; 3,391,809; and 3,489,643). In yet another instance (see U.S. Pat. No. 4,063,654), a sweep auger shaft rotatably carries a floor engaging wheel which rides on a smooth portion of a circular track and, in addition, speed reduction gearing is driven from the auger shaft to operate an eccentrically mounted drive ratchet which engages a toothed portion of the track to effect a positive drive during the sweeping action. All of these constructions are unnecessarily cumbersome and expensive.  
           [0004]    More recently (see U.S. Pat. No. 4,701,093) a speed reduction drive system having a sprocket mounted on a shaft to engage a sprocket chain secured to a drive wheel is coupled to the auger and drives the wheel at a reduced speed relative to the rotation of the auger. The speed reduction ratio is determined by the dimensions of the sprocket and sprocket chain which based on size limitations due to the construction of sweep augers, makes certain higher speed reduction ratios impracticable.  
           [0005]    A higher speed reduction ratio between the rotational speed of the auger and that of the drive wheel is desired as slower rotational speed of the drive wheel extends the life of both the drive wheel and the floor since the surface areas of both the wheel and the floor will not wear down as fast. In addition, higher speed reduction ratio places less stress and bending on the end of the backboard and allows more time for grain to be transported away along the middle of the sweep auger. The need for a higher speed reduction ratio increases as storage bins get larger, for both of these reasons.  
           [0006]    It is an object of this invention to provide improved drive arrangement for sweep augers.  
           [0007]    A further object of this invention is to provide an economical sweep auger apparatus which avoids the problems of the aforementioned apparatus.  
           [0008]    Another object of the invention is to provide an improved sweep auger apparatus which enables the auger shaft to be rotated about its longitudinal axis at a speed sufficient to achieve the desired bin unloading capacity and at the same time to drive a drive wheel on the apparatus at such sufficiently lesser speed than conventional devices that the wheel engages the bin floor with greatly reduced slippage as the auger revolves around the central vertical axis of the bin in unloading material from the bin.  
           [0009]    A further object of the invention is to provide a sweep auger apparatus which may be effectively employed to unload granular material from a circular storage bin without requiring a special circular track or the like around the periphery of the bin floor to effect a positive drive for the sweeping action.  
           [0010]    A still further object of this invention is to provide an economical sweep auger apparatus in which a single power source is employed both to rotate the auger about its longitudinal axis and to rotate the drive wheel which supports the radially outer end of the auger at a substantially lesser speed.  
           [0011]    These and other objectives will become apparent to those skilled in the art based on the following disclosure.  
         BRIEF SUMMARY OF THE INVENTION  
         [0012]    The sweep auger apparatus of this invention has an auger with a longitudinal axis that extends radially from the center of a circular storage bin. A power means, operatively connected to a first end of the auger, rotates the auger about its longitudinal axis. A drive assembly operatively connects the auger to a drive wheel and by utilizing a combination of at least three reduction gears, the drive assembly rotates the drive wheel at a speed substantially less than the rotational speed of the auger. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    [0013]FIG. 1 is a longitudinal side view, partially broken away, illustrating one embodiment of a sweep auger apparatus radially disposed above the floor of a circular storage bin and employing the invention.  
         [0014]    [0014]FIG. 2 is an enlarged side view, partially in section, of the radially outer end of the apparatus of the invention shown in FIG. 1.  
         [0015]    [0015]FIG. 3 is an exploded perspective view of the apparatus.  
         [0016]    [0016]FIG. 4 is a perspective view of the radial end of the apparatus.  
         [0017]    [0017]FIG. 5 is a partial sectional view of the drive wheel assembly of the apparatus of the invention, taken in the direction of the arrows  5 - 5  of FIG. 2.  
         [0018]    [0018]FIG. 6 is a partial sectional view of a portion of the drive wheel assembly taken in the direction of the arrows  6 - 6  of FIG. 2.  
         [0019]    [0019]FIG. 7 is a partial sectional view of a portion of the drive wheel assembly taken in the direction of arrows  7 - 7  of FIG. 2. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0020]    Referring to the figures, the sweep auger apparatus  10  is assembled in relation to a circular grain storage bin  2  having a vertical and generally cylindrical sidewall  4  and a circular false bottom or floor  6 , e.g., a bin as shown in Sukup U.S. Pat. No. 3,532,232, which is incorporated herein by reference.  
         [0021]    The apparatus  10  includes a radially extending sweep auger  12  and drive wheel  14  that is rotatably mounted within the bin  2  above the false floor  6 . A drive train for operating the apparatus  10  includes a drive unit housing  16  at the center of the bin with a drive element engaging the end of the auger to operatively connect the inner end of the auger  12  to the drive train. The auger  12  includes an axial drive shaft  20  and helical flighting  22  secured to the shaft  20 . Rotatably connected to the distal end of the auger  12  is a drive wheel  14  that supports the outer end of the auger  12  about the central vertical axis y-y of the bin  2 .  
         [0022]    The housing  16  encloses a power means that may include suitable gears and/or a motor (not shown) for rotating the auger  12  about its longitudinal axis. Alternatively, the housing  16  may enclose only suitable gearing engaging a vertical shaft  24  that extends below the false floor  6  and is driven by a motor (not shown) located below the floor  6  or outside the storage bin.  
         [0023]    In operation, the auger  12  rotates about its longitudinal axis as the apparatus  10  revolves around the central vertical axis y-y causing granular material (not shown) stored in the bin to move across the floor  6  toward and into a central sump opening  26 . The stored material typically is a free-flowing material such as, e.g., shelled corn. After the granular material falls through the central opening  26 , it may be transported outside the bin by an unloading conveyor (not shown) beneath the floor. The grain in the bin  2  is first unloaded via gravity through the central sump  26  and then through intermediate sump openings  27  which are aligned with the unloading conveyor along the false floor  6 . The apparatus  10  then removes the remaining grain in the bin  2 .  
         [0024]    As best seen in FIGS. 2-5, the drive assembly  28  comprises a rotatably mounted drive wheel  14  at the outer or distal end of the auger assembly  10 , and a speed reduction gear assembly for coupling with the auger shaft  20  and driving the wheel  14  which is rotatably mounted on shaft  34 . The gear assembly can include a variety of combinations of gears with varying construction. As an example, a reduction gear may consist of a sprocket mounted on a shaft that rotates within a bearing.  
         [0025]    The gear assembly includes a first reduction gear having a first shaft  36  and a sprocket  38  secured to the shaft  36  for rotation therewith. The sprocket  38  engages a sprocket chain  40  that is also engaged by a second reduction gear having a second sprocket  42  supported on a second shaft  44 . It is preferred that the first shaft  36  is positioned forwardly and downwardly of the second shaft  44  to achieve the optimum height of the flighting  22  above the floor  6 . On the opposite end of the second shaft  44  is a third reduction gear having a third sprocket  46  that engages an annular mating sprocket chain  48  secured to the drive wheel  14  as described further below.  
         [0026]    The drive wheel  14  rolls on the floor  6  of the bin and thus supports the radially outer end of the sweep auger apparatus  10 . The circularly disposed sprocket chain  48  is fixedly secured to the inner periphery  50  of the drive wheel  14  and effectively but very economically forms a large annular internal gear which is engaged by the sprocket  46 . The sprocket chain  48  can be secured to the drive wheel in any conventional manner such as by bolts shown in FIG. 3. By reason of this construction, when the drive wheel assembly  28  is operatively connected as a part of the sweep auger apparatus  10 , rotation of shaft  20  causes rotation of the drive wheel  14  in the same direction, but at a greatly reduced speed of rotation. The combination of the sprockets  38 ,  42  and  46  and sprocket chains  40  and  48  are selected to obtain a desired velocity of wheel  14  relative to the velocity of the auger  12 . In one embodiment an approximately 17 to 1 speed reduction is used, e.g., when the drive shaft  20  and hence shaft  36  are caused to rotate at approximately 400 r.p.m. the drive wheel  14  rotates at approximately 23.5 r.p.m. The wheel  14  will provide a steady advancing force to continuously press the auger  12  into the pile of remaining material, with slippage of the wheel accommodating the slow advance while assuring continued force of the auger into the material. However, the slippage is controlled and greatly reduced as compared, for example, to prior devices. In addition, the slower speed of the drive wheel places less stress on the backboard since there is more time for the auger to take away the grain.  
         [0027]    The gear assembly is partially covered by a gear reduction housing  72  that is comprised of a first side plate  74 , a second side plate  76 , and a casing cover  78 .  
         [0028]    The attachment of the drive wheel assembly  28  to the auger is best described as follows. The inner end of shaft  36  is snuggly and coaxially received in the outer end of the auger shaft  20  and is fixed thereto by means of holes  52  and mating pins  54 . First shaft  36  extends through apertures in plates  74  and  76  and is secured to the plates by bearings  81  for rotation of the shaft. Second shaft  44  extends through plate  76  and is secured to plates  74  and  76  by bearings  81  for rotation of the shaft  44 . Shaft  34  extends through a central aperture of plates  74  and  76  and is secured to plate  74 . The drive wheel  14  has a bushing that rotates about shaft  34 .  
         [0029]    A plurality of bolts  77  extend through a plurality of apertures in plate  76 , a plurality of spacer sleeves  79  positioned between the plates, and a plurality of apertures in plate  74  to further secure and separate the two plates. The casing cover  78  extends around and between the outer periphery of plates  74  and  76  and is secured in any conventional manner.  
         [0030]    A vertical backboard  64  extends the full length of the auger  12  and is disposed proximate to its trailing edge. The backboard  64  is fixedly secured at its inner end to the housing  16  and the drive assembly  28  at its outer end. The backboard has a flange  66  that extends transversely to the longitudinal axis of the backboard  64  at the backboard&#39;s outer end. The drive assembly  28  includes a brace member  80  that is secured to side plate  74  and then attached to flange  66  of backboard  64  to assist in maintaining the gear reduction housing  72  in a vertical position.