Seed metering device

Abstract

A seed metering device includes a roller nip for mounting beneath a seed reservoir. The nip is formed by first and second opposed facing nip forming surfaces mounted beneath, and aligned with, the reservoir wherein the first nip forming surface is a radially-outer surface of a soft resilient roller. The roller is rotatable by a roller drive in a first rotational direction so as to draw down through the nip, by frictional engagement of the seeds in the nip with the surface of the resilient roller, seeds falling into the nip. The nip is an elongate, curved, thin wedge-shaped nip providing an increased dwell time for seeds being compressed in the nip.

What is claimed is:  
     
         1 . A seed metering device comprising: 
 a seed reservoir for holding seeds, said reservoir having an aperture in a floor of said reservoir,    first and second opposed facing nip forming surfaces mounted beneath said aperture so as to form a primary nip below said aperture so that seeds fall through said aperture into said primary nip, wherein said first nip forming surface is a radially-outer surface of a resilient cylindrical roller and said second nip forming surface is a rigid curved control surface on a lower wall adjacent said roller, said roller rotatable about an axis of rotation by a roller drive in a first rotational direction so as to draw down through said primary nip, by frictional engagement of said seeds in said nip with said surface of said resilient roller,    said control surface having a center of curvature offset from said axis of rotation of said roller so that said control surface and said roller are eccentric and said primary nip is elongate, curved and wedge-shaped along an arc of generally 60 degrees about generally said center of curvature of said control surface, a vertex of said wedge-shape of said primary nip being at a lower end of said control surface,    said seeds following a pathway from said reservoir, through said first aperture, into a wide upper opening of said primary nip and into compressed engagement between said roller and said control surface so as to resiliently deform said roller as said roller resiliently urges said seeds into a single thickness layer as said primary nip converges to said vertex and said seeds are drawn through said primary nip so as to emerge downstream of said vertex and drop into an outfeed chute,    wherein said second nip forming surface includes a rigid flow restrictor.    
     
     
         2 . The device of  claim 1  wherein said flow restrictor is a rigid nozzle surface of a nozzle mounted beneath said aperture.  
     
     
         3 . The device of  claim 2  wherein said rigid nozzle surface is a lower surface of a converging nozzle conduit extending through said nozzle.  
     
     
         4 . The device of  claim 3  wherein said nozzle has a curved lower surface flush with said surface of said roller, said nozzle conduit terminating in an aperture in said curved lower surface so as to form a secondary nip between said nozzle surface and said surface of said roller.  
     
     
         5 . A seed metering device comprising: 
 a seed reservoir for holding seeds, said reservoir having an aperture in a floor of said reservoir,    first and second opposed facing nip forming surfaces mounted beneath said aperture so as to form a primary nip below said aperture so that seeds fall through said aperture into said primary nip, wherein said first nip forming surface is a radially-outer surface of a resilient cylindrical roller and said second nip forming surface is a rigid curved control surface on a lower wall adjacent said roller, said roller rotatable about an axis of rotation by a roller drive in a first rotational direction so as to draw down through said primary nip, by frictional engagement of said seeds in said nip with said surface of said resilient roller,    said control surface having a center of curvature offset from said axis of rotation of said roller so that said control surface and said roller are eccentric and said primary nip is elongate, curved and wedge-shaped along an arc of generally 60 degrees about generally said center of curvature of said control surface, a vertex of said wedge-shape of said primary nip being at a lower end of said control surface,    said seeds following a pathway from said reservoir, through said first aperture, into a wide upper opening of said primary nip and into compressed engagement between said roller and said control surface so as to resiliently deform said roller as said roller resiliently urges said seeds into a single thickness layer as said primary nip converges to said vertex and said seeds are drawn through said primary nip so as to emerge downstream of said vertex and drop into an outfeed chute,    wherein said roller is mounted on a drive shaft of said roller drive, a pair of rigid discs mounted one on each opposite side of said roller so as to sandwich said roller between said pair of rigid discs leaving substantially only said radially-outer surface of said roller exposed for rotation through said primary nip.    
     
     
         6 . The device of  claim 5  wherein said pair of rigid discs are rigidly mounted on said drive shaft and snugly sandwich said roller mounted in adhesive engagement therebetween so that rotation of said pair of rigid discs on said drive shaft simultaneously rotates said roller.  
     
     
         7 . The device of  claim 7  wherein a pair of rigid walls are mounted below said floor, generally orthogonal thereto, said pair of walls having apertures therein, said drive shaft journalled through said apertures in said pair of walls, said pair of walls sandwiching therebetween said pair of rigid discs and said roller.  
     
     
         8 . The device of  claim 7  wherein each wall of said pair of walls has arcuate disc supports formed therein for sliding rotational mating of said pair of rigid discs into said disc supports.  
     
     
         9 . The device of claims  1  wherein said roller is a parallel array of rollers, said array extending the length of said first aperture.  
     
     
         10 . The device of claims  1  wherein said surface of said roller is notched.  
     
     
         11 . The device of claims  1  wherein said center of curvature of said roller is offset downwardly from said center of curvature of said control surface.  
     
     
         12 . The device of claims  1  wherein said center of curvature of said roller is offset outwardly from said center of curvature of said control surface and away from said control surface.  
     
     
         13 . The device of claims  1  wherein said roller has a resilient core.  
     
     
         14 . The device of  claim 13  wherein said roller is made of polyurethane foam.  
     
     
         15 . The device of  claim 14  wherein said polyurethane foam is 40 pound polyurethane foam.  
     
     
         16 . The device of claims  5  wherein said roller is a parallel array of rollers, said array extending the length of said first aperture.  
     
     
         17 . The device of claims  5  wherein said surface of said roller is notched.  
     
     
         18 . The device of claims  5  wherein said center of curvature of said roller is offset downwardly from said center of curvature of said control surface.  
     
     
         19 . The device of claims  5  wherein said center of curvature of said roller is offset outwardly from said center of curvature of said control surface and away from said control surface.  
     
     
         20 . The device of claims  5  wherein said roller has a resilient core.