Abstract:
A granule spreader controls granule distribution by using a granule pump. The pump uses a rotating impeller that extracts measured amounts of granular material from a reservoir or hopper. Only the measured amounts are delivered to a rotary spreader for dispersal.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     Granule spreaders, such as grass seed spreaders and fertilizer spreaders are well known. These devices typically have a holding tank or hopper for granular material to be dispersed. They also have some form of dispersing mechanism that receives granules from the hopper and either drops them horizontally onto the ground or distributes them radially.  
         [0002]     A problem with prior art granule spreaders is their inability to accurately control the granule material delivery rate. Because granular material is difficult to handle, prior art granule spreaders control flow rate by increasing or decreasing an opening through which granular material flows vertically from the hopper to the dispersing mechanism. As such, granular material will continue to flow when the spreader is not moving across land to be treated. A spreader for granular material that provides flow control by relating the ground speed of a spreader to an amount that is pumped and dispersed to give a more consistent granule application would be an improvement over the prior art.  
       SUMMARY OF THE INVENTION  
       [0003]     Granule material is controllably delivered by gravity-feeding granules into partially-covered rotating vanes of an impeller. The impeller vanes carry the granules to an opening in the spreader hopper through which the granules fall onto a rotating plate that radially disperses the material. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0004]      FIG. 1  is an example of a granule spreader.  
         [0005]      FIG. 2  is an exploded isometric view of a spreader hopper with a granule pump.  
         [0006]      FIG. 3  is a top view of a granule measuring impeller used in the spreader for granular material depicted in  FIG. 1  and  FIG. 2 .  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0007]     A granule is defined by the Merriam-Webster&#39;s Dictionary, Tenth Edition as a “small particle.” Individual grass seeds and solid fertilizer pellets are “granules.” Salt crystals and sugar crystals are also “granules. Grains of sand are small particles and are therefore “granules.” Ordinary flour is an aggregation of small particles; flour can therefore be considered to be granules.  
         [0008]     The aforementioned dictionary definition of “granule” does not limit what is and what is not a “granule.” For purposes of this disclosure therefore, the term “granule” can therefore include very small particles but it can also include relatively large particles.  
         [0009]      FIG. 1  shows a granule spreader  2  for use in dispersing fertilizer, grass seed or other granular materials. The spreader  2  is constructed from tubular steel or other rigid material that forms a frame  3 , which supports a bin or hopper  12  in which granular material to be dispersed is stored.  
         [0010]     The frame  3  and the hopper  12  can be easily moved about on first and second wheels  6 A and  6 B, which are rotatably connected to the frame  3 . As shown in  FIG. 1 , the wheels  6 A and  6 B are coupled to each other by an axle  4 , to which a ring gear  5  is attached in order to drive a small pinion gear (not shown) that is connected to a drive shaft  7 . The ring gear  5  and pinion form a simple transmission that rotates the drive shaft  7  by rotation of the spreader&#39;s wheels  6 A and  6 B, i.e., by movement of the spreader  2  on a surface. Any other mechanism which translates rotational movement from one axis to another may also be used. Rotation of the drive shaft  7  turns a granule pump that is located inside the hopper  12  and a spreader plate  40 .  
         [0011]     Granules to be dispersed onto the ground from the bin or hopper  12 , fall into the granule material pump inside the hopper  12 , which measures granules to be dispersed and directs them onto the rotating plate  40 . Vanes  41  in the rotating plate  40  act to throw granules radially, i.e. disperse them.  
         [0012]      FIG. 2  shows an isometric view of the spreader&#39;s hopper  12 , including an exploded view of the granule material pump  20 .  
         [0013]     The hopper  12  defines an open top  13  through which granular material to be distributed can be poured into the interior  14  of the hopper  12 . As shown, the hopper  12  has a generally inverted frusto-pyramidal shape so that it&#39;s widest dimension is up, whereby granules are added through the wide end of the frusto-pyramid. The inverted orientation of the frusto-pyramid shape also helps move granules in the hopper  12  toward the center and bottom  16 .  
         [0014]     Granular material in the hopper  12  cannot flow directly to the opening  18  because of a granule measuring pump  20 , attached to the hopper bottom  16  and over the bottom-located opening  18 . By virtue of the hopper&#39;s inverted frusto-pyramid shape, gravity will cause granules in the hopper to fall toward the bottom  16  and into the granule measuring pump  20  input. Once granular material enters the granule measuring pump, it is carried by the pump to an opening in the bottom of the pump  20  that is directly above and aligned with the opening  18  in the hopper bottom  16 . There is no direct, unobstructed pathway from the hopper interior  13  to its exterior; granules in the hopper  12  must pass through the pump.  
         [0015]     Granules from the hopper  12  that are directed onto the rotating plate  40  are dispersed by the spreader vanes  41 , the rotation of which radially accelerates granules outwardly where they fall to the ground or other surface onto which the granules are to be distributed.  
         [0016]     One embodiment of the granule measuring pump  20  is a four-piece assembly. It will be recognized by those of skill in the art that the number of pieces which make up the granule measuring pump  20  may be varied. The pump  20  uses a multi-vane impeller  30 , which is also shown in greater detail in  FIG. 3 . The impeller  30  is constructed to have several vanes  34  with the space between each vane defined as an internal space or portion  35 . Granules in the hopper  12  will fall into the internal space  35  as the impeller  30  rotates in the housing  22  of the pump  20 . Because the amount of granular material that can occupy each internal space  35  is limited, each internal space  35  conveys a fixed or measured amount of granular material from the hopper  12  to the opening  18  in the hopper bottom  16 . Adjacent ones of the impeller vanes  34 , which extend radially from the central part  32  of the impeller  30 , define additional internal portions  35  into which granules fall from the hopper  12 . Granules in the other internal portions  35  are carried by the impeller  30  rotation to the opening  18  in the hopper bottom  16 .  
         [0017]     The granule measuring pump  20  is made up of a substantially planar pump housing  22 , which has a planar top  24  and a planar bottom  26  and a centrally located opening  28 , sized and shaped to enclose the aforementioned granule impeller  30 . When the pump  20  is assembled, it&#39;s attached to the hopper bottom  16 .  
         [0018]     The top surface  24  of the housing  22  is partially covered by the top cover plate  40 . Because the top cover plate  40  covers only a portion of the impeller  30 , granular material above the impeller, i.e., above the pump  20 , can fall into at least some of the spaces  35  between each of the impeller vanes  34  that are exposed to the interior  14  of the hopper  12 . The portion of the impeller  30  that is not covered by the top cover plate is considered to be the pump opening or inlet, into which granules above the pump inlet can pass. As shown in  FIG. 3 , vanes  34  that are open or exposed to granular material above the pump can be considered to cover a certain area, which can be represented as subtending an angle 0, measured with respect to the impeller&#39;s axis of rotation  21 .  
         [0019]     A pump housing bottom cover plate  36  has a first centrally located opening  38  through which a drive shaft can pass to be coupled to the impeller  30 . A second opening  39  in the bottom plate  36  is aligned to the opening  18  in the bottom of the hopper  12  such that when the pump  20  and its components are assembled, granular material in the hopper  12  can exit the hopper opening  18  only by passing through the impeller  30 . The second opening  39  in the bottom plate  36  is considered to be the pump&#39;s output. The second opening  39  in the bottom cover  36  covers only a portion of the area beneath the impeller  30 . Importantly, the opening  39  subtends an angle less than 180 degrees, measured about the axis of rotation  21 , so that granules do not have a direct pathway through the pump  20  but instead must be conveyed from the inlet to the offset pump outlet via the impeller  30 .  
         [0020]     As shown in  FIG. 3 , a central part  32  of the impeller  30  includes an opening through which a drive shaft extends and fixed to the impeller and whereat the impeller&#39;s axis of rotation  21  is located. Several granule-scooping vanes  34  extend away from that evenly spaced around the axis of rotation  21  and located away from the axis or rotation in the central part  32  of the impeller. These scooping vanes,  34  which are just outside the central part, define a volume  35  that carries granules. When the pump  20  is assembled into a granule spreader, the drive shaft that extends through the opening in the central part  32  of the impeller, rotates the impeller  30 , causing it to rotate in the pump housing  22 .  
         [0021]     As shown in  FIG. 2 , the pump housing cover plate  40  partially covers the impeller vanes  34 . Because the cover plate  40  lies above the second opening  39  in the pump housing bottom cover  36 , which is aligned with the opening  18  in the hopper bottom  16 . The pump housing cover  40  therefore prevents granule material in the hopper  12  from free flowing out of the opening  18 . Granules can only leave the hopper through the impeller  30  vanes  34  as they are rotated about the impeller&#39;s axis of rotation  21 . This overcomes the disadvantage of the prior art where granules would continue to flow when the spreader was not traversing the surface being treated.  
         [0022]     As set forth above, the cover plate  40  restricts granule material from free-flowing out of the hopper  12 . Granule delivery rate can therefore be controlled by the size, i.e., diameter of the impeller, the geometry of the vanes  34  and its rotational speed. Material delivery rate is also controlled by the depth or thickness of the impeller  30 , which will determine the volume of material that can be moved by each impeller space  30 . In addition to granule delivery rate, the configuration of the pump and its associated assembly elements function to limit the granule size that is dispersed. This is particularly advantageous when spreading a non-homogenous material such as rock salt, fertilizer or any other non-homogeneous material.  
         [0023]     In the preferred embodiment, the bottom plate  36  of the granule pump  20  lies against the bottom  16  of the hopper  12 . The bottom plate  36  provides a wear plate for the impeller  30  but it also provides an opening  39  through which granules pass to the spreader plate  40 . It will be recognized by those of skill in the art that the granule pump may also be disposed external of the hopper and perform the intended function. For example, the granule pump may be connected to the exterior bottom of the hopper in communication with an opening in the bottom of the hopper and perform the intended function described herein.  
         [0024]     The bottom plate  36  actually has two openings, the first  38  of which accepts a drive shaft for the pump impeller  30 . The second opening  39  is aligned with the hopper opening  18  and coupled to the hopper bottom  16 . As shown on  FIG. 2 , the dimensions of the second opening  39  are such that it will subtend an angle that extends only partially around the first opening  38 . The second opening  39  should be sized and shaped so that there is no direct pathway from the hopper interior  13  to its exterior. In one preferred embodiment the second opening  39  in the bottom plate  36  is substantially the same size as the bottom opening  18 .  
         [0025]     It is important to note that the second opening  39  of the bottom plate  36  should be sized and shaped so that all of the granule material carried in the interior  35  of the impeller will fall away from the portion of the impeller that is over the second opening  39 . If the second opening  39  is too small, granules that don&#39;t fall away from the impeller will remain in the impeller until the opening is enlarged.  
         [0026]     Because the impeller  30  in the pump rotates on a drive shaft that also drives the spreader, the pump needs to be fixed in the hopper  12  or it will tend to rotate with the drive shaft to which the impeller is attached. Indeed, as granules are collected in the pump housing  20 , some of them will tend to become wedged between the rotating impeller  30  and the top cover plate  22  and the bottom cover plate  36 . Fixing the pump  20  so that it can&#39;t rotate will help insure granule delivery.  
         [0027]     The granule pump  20  in one embodiment shown in  FIG. 2  is attached to the hopper bottom  16  by fasteners that extend through the bottom plate  36  into the hopper bottom  16 . Alternatively, the pump  20  can be attached to the exterior of the hopper bottom  16  by fasteners that extend through the bottom plate  36 , the top surface  24  of the housing  22  and into the hopper bottom  16 . The pump  20  may be attached by mechanical fasteners, an adhesive or any other means as a design choice.  
         [0028]     The drive shaft  7  (shown in  FIG. 1 ) drives both the rotating spreader  40  and the impeller  30  and is driven by a conventional transmission between the spreader&#39;s wheels (not shown). Inasmuch as the impeller  30  and the spreader plate  40  are preferably driven by the same drive shaft, the central axes of the impeller  30  and the axis of the spreader  40  are preferably co-linear.  
         [0029]     While the impeller  30  provides a controlled delivery of granule material from the hopper  12  to the spreader  40 , it&#39;s also desirable to stop granule material from flowing from the spreader. The spreader  10  is therefore provided with a granule gate  42  comprised of a gate bracket  44  and a sliding gate  46 . The granule gate  42 , which is located between the spreader plate  40  and the opening  18  in the bottom  16 , has a “first” or open position that will allow granules to drop from the opening  18  to the spreader plate  40 . In the open position, the gate plate  46  is slid away from the sliding gate bracket  44 . In a “second” or closed position, the gate  46  is slide into the gate bracket  44  such that granules cannot pass through the opening  18 . In the closed position, the gate  46  is inserted into the gate bracket  44  and obstructs the passage of granule material thereby closing it into the hopper and preventing any dispersal of the granule material. The spreader may continue to be moved over the ground to be treated without causing damage to the spreader because the impeller will continue to rotate and the granules that fall into the volume  35  will be returned to the hopper  12 .  
         [0030]     From the foregoing, it should be apparent that an improved spreader for granular material is provided by a granule-measuring pump that positively collects granule material from the hopper and delivers it to the opening from the hopper for distribution by the rotating spreader  40 .