Abstract:
A seed singulator for use with a vacuum disk having a seed face and a shoulder. The seed singulator has a first member and a second member supported by biasing members. The first member has upper lobes disposed at a radius of curvature slightly less than the outside radius of a row of apertures on a seed plane of the vacuum disk. The seed member has lower lobes disposed at a radius of curvature slightly greater than the inside radius than the row of apradius. The biasing members permit the lobes to move with the seed plane and the shoulder as the vacuum disk rotates thereby maintaining their position with respect to the apertures.

Description:
This application Ser. No. 13/451,386 is a Reissue of Ser. No. 12/064,059, filed on Jun. 3, 2008 and now U. S. Pat. No. 7,699,009, which is a 371 of PCT/US06/32256, filed on Aug. 17, 2006, which claims benefit of 60/710,014, filed on Aug. 19, 2005.  
    
    
     BACKGROUND OF THE INVENTION 
     It is well recognized that proper and uniform spacing of seed in the furrow is essential to maximizing crop yield. The first step in achieving uniform spacing is to accurately dispense one seed and one seed only at the proper timing. This “singulation” accuracy is a performance benchmark that is well known for many types of seed meters, whether mechanical or pneumatic, and is often tested on a seed meter test stand prior to the beginning of the planting season. 
     There are many different manufacturers of pneumatic seed meters which fall into the more specific categories of air meters and vacuum meters. An example of one type of commercially successful air meter is disclosed in U.S. Pat. No. 3,888,387 to Deckler. An example of one type of commercially successful vacuum meter is disclosed in U.S. Pat. No. 5,170,909 to Lundie et al. Other commercially successful vacuum meters include those disclosed in U.S. Pat. No. 5,842,428 to Stufflebeam et al., U.S. Patent Publication No. 20050204972 to Eben et al., and U.S. Pat. No. 3,990,606 to Gugenhan. Many of these meters have historically operated at performance levels of 93% to 97% accuracy. Recent improvements to vacuum meters have allowed them to operate at a typical accuracy of 98 to 99%. The vacuum meter is capable of 99% singulation on some seed types but has been plagued with the need for adjustment in order to attain that performance. Secondly, the particular design of many of these meters has made them susceptible to reduced performance levels as a result of manufacturing tolerances. 
     A problem affecting singulation accuracy with vacuum meters that utilize “celled-disks” (i.e., disks with indentations or “cells” around each aperture in the disk, such as the disks disclosed in U.S. Pat. No. 5,170,909 to Lundie et al.), is that such meters have a higher tendency to plant “skips” and “doubles” in near succession when planting flat shaped seeds. Despite this tendency, however, celled-disk vacuum meters offer the unique advantage of permitting the meter to generally operate at lower vacuum levels than meters that use flat or non-celled disks (i.e., vacuum disks with apertures only) because the indentations or cells assist in holding the seeds in place, thus requiring less vacuum pressure to entrain the seeds. 
     In an attempt to improve singulation accuracy, farmers have tried to use non-celled disks with meters originally designed for celled-disk meters. For example, with the John Deere MaxEmerge vacuum meters, farmers started using one of the specialty disks designed by John Deere for planting irregular seeds such as sweet corn (thus, this disk is often referred to as the “sweet corn disk”). The sweet corn disk is flat on the planting surface and does not have any indentations or cells to hold the seed. Similar to the sweet corn disk, an update kit, known as the Accu-Vac Update Kit, available from S.I. Distributing, Inc. St. Marys, Ohio, utilizes a flat, non-celled disk. The Accu-Vac disk has larger apertures in order to ensure the seeds are adequately entrained so they do not prematurely slough-off as the disk rotates. While the sweet corn disk and the Accu-Vac disk have markedly increased singulation performance when used in place of celled-disk, both have resulted in a system that requires very tedious adjustments by the planter operator in order to achieve optimum performance. Furthermore, the design of this meter and the nature of disks to warp over time has resulted in difficulty in keeping the double eliminator in proper alignment with the disk. 
     Other vacuum seed meters such as disclosed in U.S. Pat. No. 3,990,606 to Gugenhan have relied upon the flat disk with apertures and a seed stripping “singulator.” These designs have provided for more repeatable and operator-friendly adjustments but the need still remains for adjustment. The meter disclosed in U.S. Pat. No. 5,842,428 to Stufflebeam et al. utilizes a flat disk and three spring loaded singulating spools that compensate for tolerances in one direction, but the spools do not compensate for radial translation of the disk. 
     Accordingly, there remains a need for a seed singulator that can be used with different types of meters and different types of seed disks, but which can deliver very high singulation accuracy while requiring minimal adjustments for seed type or manufacturing tolerances and wherein the singulation accuracy is not adversely effected by axial and radial translations of the disk. 
     SUMMARY 
     The present invention is directed to a seed singulator for use with a vacuum disk having a seed face and a shoulder. The seed singulator has a first member and a second member supported by biasing members. The first member has upper lobes disposed at a radius of curvature slightly less than the outside radius of a row of apertures on a seed plane of the vacuum disk. The seed member has lower lobes disposed at a radius of curvature slightly greater than the inside radius than the row of apradius. The biasing members permit the lobes to move with the seed plane and the shoulder as the vacuum disk rotates thereby maintaining their position with respect to the apertures. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a partially exploded perspective view of the conventional vacuum meter utilizing a flat non-celled disk. 
         FIG. 2  is a partially exploded perspective view of an offset disk type vacuum seed meter. 
         FIG. 3  is a cross-sectional view of a conventional flat disk as viewed along lines  3 - 3  of  FIG. 1 . 
         FIG. 4  is a cross-sectional view of an offset disk as viewed along lines  4 - 4  of  FIG. 2 . 
         FIG. 5  is an exploded perspective view of a preferred embodiment of the seed singulator of the present invention shown being mountable to the back cover of a conventional vacuum meter housing. 
         FIG. 6  is a detailed perspective view showing the singulator assembly of  FIG. 5  in use on an offset disk. 
         FIG. 7  is a perspective view of a preferred embodiment of a base for the seed singulator of  FIG. 5 . 
         FIG. 8  is a top perspective view of a preferred embodiment of the rail for the seed singulator of  FIG. 5 . 
         FIG. 9  is a bottom perspective view of the rail for the seed singulator of  FIG. 5 . 
         FIG. 10  is a perspective view of the seed singulator of  FIG. 5  illustrating the various degrees of freedom that can be achieved by the preferred embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views,  FIG. 1  shows an exploded perspective view of a conventional vacuum meter  100 , such as the John Deere MaxEmerge® vacuum meter, which is disclosed in U.S. Pat. No. 5,170,909 to Lundie et al., incorporated herein in its entirety by reference. The John Deere MaxEmerge vacuum meter  10  100 is generally designed for use with a celled disk, but in  FIG. 1 , the celled disk has been replaced with a flat non-celled disk  200  such as the sweet corn disk or Accu-Vac disk previously described. The disk  200  is rotatably mounted within a housing  102 . The housing  102  includes a back cover  104  and a front cover  106 . 
       FIG. 2  shows a partially exploded view of vacuum meter  400  that is substantially the same as the vacuum meter  100  as illustrated in  FIG. 1  except that the flat-disk  200 , is replaced by an offset disk  500 .  FIG. 3  is a cross-sectional view of the flat disk  200  as viewed along lines  3 - 3  of  FIG. 1 .  FIG. 4  is a cross-sectional view of the offset disk  500  as viewed along lines  4 - 4  of  FIG. 2 . 
     As best illustrated in  FIG. 3  the seed-side face  204  of the offset flat-disk disk  200  defines a seed plane  222 . A plurality of apertures  208  are disposed around the seed plane  222  for entraining the seeds onto the face of the seed-side face  204  of the disk as it rotates through the seed pool within the vacuum meter housing  102 . Depending on the type of seed to be planted, the apertures  208  may be equally radially spaced or the apertures  208  may comprise radially spaced groupings, or the apertures  208  may be disposed in multiple rows offset or radially aligned. In the embodiment of  FIG. 1 , the apertures are shown equally spaced around a radius R 1 , the outside radius of the apertures is referenced as R 2 , the inside radius of the apertures is referenced as R 3 . The disk  200  further includes a shoulder  230  disposed at a radius R 4  from the centerline of the disk. The shoulder  230  may be the outer circumferential periphery of the disk  200  as illustrated in  FIG. 3 , or the should shoulder  230  may be radially inward from the circumferential outer periphery of the disk, similar to the offset disk  500  but with a flat face and a less pronounced offset. 
     As best illustrated in  FIG. 4  the seed-side face  504  of the offset disk  500  preferably comprises two primary planes offset from each other, the base plane  520 , and the seed plane  522 . The seed plane  522  is a raised planar surface extending from the base plane  520  by inner conical side wall  526  and an outer cylindrical sidewall  528  defining a cylindrical shoulder  530 . As with the flat disk  200 , the offset disk  500  includes a plurality of apertures  508  for entraining the seeds onto the face of the disk as it rotates through the seed pool within the vacuum meter housing. Depending on the type of seed to be planted, the apertures  508  may be equally radially spaced or the apertures  508  may comprise radially spaced groupings, or the apertures  508  may be disposed in multiple rows offset or radially aligned. In the embodiment of  FIG. 2 , the apertures are shown equally spaced around a radius R 1 , the outside radius of the apertures is referenced as R 2 , the inside radius of the apertures is referenced as R 3  and the radius of the cylindrical shoulder  530  is referenced as R 4 . 
     A preferred embodiment of a seed singulator assembly  900  is shown in  FIG. 5  as being mountable to a back cover  104  of a conventional vacuum meter housing  102 .  FIG. 6  illustrates the seed singulator assembly  900  disposed on an offset disk  500 . The singulator assembly  900  includes a singulator base  902  which is preferably mountable in a conventional manner to the back cover  104  of the vacuum meter housing  102  through two mounting ears  904 . The base  902  provides a secure platform from which the other components comprising the singulator assembly  900  are supported. 
     It is known that singulation performance improves with an increasing number of times that the seeds are contacted by the singulating lobes. It has been determined that superior singulation accuracy is achieved by bumping or agitating the seeds from both the top side (i.e., the outside radius R of the apertures) and the bottom side (i.e., the inside radius R 3  of the apertures). For example, if a singulator is used that only bumps the seeds from the top side, then some seeds multiples may be able to “hang” on the very bottom of the aperture and would not be stripped or removed by the top singulator. Furthermore, it has been found that singulation can be best achieved when the seed is contacted three times from the top side of the apertures  208 ,  508  relative to the path of travel and two times from the bottom side of the apertures  208 ,  508 . 
     Accordingly, in the preferred embodiment, a rail  906  supports three lobes  908 ,  910 ,  912 . As illustrated in  FIG. 6 , these three lobes  908 ,  910 ,  912  are disposed on the top side of the apertures  508 . The rail  906  has an inner face  913  having a radius of curvature that is preferably substantially the same or slightly larger than the radius R 4  of the shoulder  230 ,  530 . Continuing to refer to  FIG. 6 , two bottom lobes  914 ,  916  are preferably supported by two divergent arms  918 ,  920  preferably extending from an L-shaped bracket  922  connected to the rail  906 . The bottom lobes  914 ,  916  are also preferably made of a wear resistant and durable material such as metal or brass using the investment casting or metal injection molding process. Each of the lobes  908 ,  910 ,  912 ,  914 ,  916  has a surface  924  that is co-planar with the other lobes. As shown in  FIG. 6  each of these co-planar surfaces  924  is disposed adjacent the seed plane  522  of the offset disk  500 . For the flat disk  200 , each of these co-planar surfaces  924  would be disposed adjacent the seed plane  222  of the flat disk  200 . 
     Referring to  FIG. 7 , in the preferred embodiment, a first wire  926  is supported at each end by tabs or slots 928 in the base  902 . As illustrated in  FIG. 7 , this first wire  926  is preferably received within hooks  930  disposed on the L-shaped bracket  922 . This first wire  926  serves as an axial spring which biases the co-planar surfaces  924  of the lobes  908 ,  910 ,  912 ,  914 ,  916  against or in contact with the seed plane  222 ,  522  of the disk  200 ,  500 . 
     Continuing to refer to  FIG. 7 , a second wire  932  is secured at or near its ends to the base  902 . Disposed on the back side of the rail  906  is a tongue  934  which is receivable by and is slidable within a groove  936  formed in the top wall  938  of the base  902 . The tongue  934  within the groove  936  also receives the second wire  932  as best illustrated in  FIG. 9 . Thus, the second wire  932  serves as a radial spring which biases the inner face  913  of the rail  906  against the top or outside diameter of the shoulder  230 ,  530 . 
     It should be appreciated that the preferred embodiment permits the lobes  908 ,  910 ,  912 ,  914 ,  916  to “float” with the seed plane  222 ,  522  and the shoulder  230 ,  530  of the disk  200 ,  500 . This ability to float provides inherent advantages. For example, during rotation, the disk  200 ,  500  may translate about the central axis due to warping, or as a result of the bearing or hub being out of alignment, or possibly due to bending or flexing of the disk  200 ,  500  caused by the pressure differential between the seed-side face and the vacuum side face of the disk. Additionally, the disk  200 ,  500  may be subject to radial translation caused by improper hub alignment, mounting tolerances or disk eccentricities associated with the manufacturing process or manufacturing tolerances.  FIG. 10  illustrates the various degrees of freedom that is provided by the foregoing spring biased suspension system of the seed singulator assembly  900 . 
     Thus, by providing a singulator with lobes that float and remain in contact with the seed plane  222 ,  522  and/or in contact with the top of the shoulder  230 ,  530 , the singulator assembly  900  is able to compensate for both radial translation and axial translation and radial rotation of the disk, while the amount of coverage of the apertures  108 ,  208 ,  508  by the passing lobes  908 ,  910 ,  912 ,  914 ,  916  remains constant regardless of the movement of the disk  200 ,  500 . Additionally, the spring biased suspension of the lobes permits the lobes to flex away from the apertures  208 ,  508  in the case a seed or fragment becomes stuck in the aperture. This flexure prevents adverse wear to the surfaces  924  and edges of the lobes and also improves performance by preventing sudden jerking of the disk due to seeds wedging between an inflexible or immovable singulator and the aperture. 
     A further advantage of the preferred embodiment of the spring suspension system of the singulator  900  is that the singulator assembly  900  need not be removed when switching from the offset disk  500  to a celled (with which a singulator is not generally used). Instead, in the preferred embodiment, the rail  906  is capable of being locked into a depressed position whereby the lobes  908 ,  910 ,  912 ,  914 ,  916  will not contact the seed-side face  104  204, 504 of the disk  100  200, 500. Referring to  FIGS. 7 ,  8  and  9 , a groove  940  is formed in the top side edge of the rail  906 . A tab  942  also projects from the top side edge of the rail  906 . By depressing the rail  906  downwardly and rearwardly relative to the base  902 , the tab  942  can be forced behind the second wire  932  such that the second wire  932  locks the rail in place in the downward or depressed position with the second wire  932  disposed on the top edge of the rail  906  and resting groove  940 . 
     The foregoing description is presented to enable one of ordinary skill in the art to make and use the invention and is provided in the context of a patent application and its requirements. Various modifications to the preferred embodiment of the singulator assembly, such as the various alternative embodiments disclosed in co-pending U.S. Provisional Application No. 60/710,014 incorporated herein in its entirety, and the general principles and features described herein will be readily apparent to those of skill in the art. Thus, the present invention is not to be limited to the embodiments of the apparatus and methods described above and illustrated in the drawing figures, but is to be accorded the widest scope consistent with the spirit and scope of the appended claims.