Abstract:
A direct drive electric seed metering system is provided for use with a row crop planter or seed planter that intakes a volume of multiple seeds from a seed hopper, draws individual seeds from the volume of multiple seeds and discharges them into a seed furrow formed in an agricultural field. The direct drive electric seed metering system includes a meter assembly having a meter housing and a seed plate rotatably mounted concentrically in the housing for singulating the seeds. A direct drive mechanism is mounted to the meter assembly for interfacing and driving the seed plate at an angular velocity which corresponds to the travel velocity of the seed planter. A single seed planter can have multiple direct drive electric seed metering systems, and each of the multiple direct drive electric seed metering systems preferably has its own prime mover to effectuate driving the seed plate.

Description:
FIELD OF THE INVENTION 
   The invention relates generally to seed planters for dispensing individual seeds at a controlled rate into a seed furrow, and in particular, to a device and corresponding method for metering seeds at a desired rate. 
   BACKGROUND OF THE INVENTION 
   Modern row crop planters or seed planters include multiple row planting units attached to a toolbar and towed behind a tractor. Each of the row planting units are responsible opening a seed trench or furrow, dispensing the seeds into the furrow, then closing the furrow after the seeds are planted. The seed furrows are opened by a first pair of disks extending down from the planter at its leading end, closed by a second pair of disks extending down from the planter at its trailing end, and then tamped down by a trailing wheel which follows both disk pairs. 
   Typically, each row planting unit has its own seed hopper and seed metering system for dispensing the seeds at a controlled rate into the seed trench or furrow as the planter advances along the ground. The most common seed metering systems are vacuum-type meters that use vacuum force to draw air through multiple openings in a rotating seed disk, trapping individual seeds within each opening for delivery to a second location for their release to a seed placement device. The individual seeds are then delivered by the seed placement device, between the furrow opening disk and the furrow closing disks, into the open furrow at a controlled rate. 
   To perform the various seed metering operations, conventional row crop planters utilize a vacuum provided by, e.g., a blower driven by a hydraulic motor attached to the hydraulic system of the tractor. However, the force required to rotate the seed disk is typically provided by a ground drive or a hydraulic drive. The ground drive, hydraulic drive, or other power source rotates a main, common driveshaft extending substantially the entire width of the row crop planter. The individual seed metering systems of the individual row planting units take power from this main driveshaft. The power is transmitted from the main driveshaft to the individual row planting units by way of chain or cable drives, driving a meter driveshaft, whereby the meter driveshaft serves as a power accepting jackshaft. 
   Typical meter driveshafts extend axially from, and concentrically drive, the seed plate. Notwithstanding, some attempts have been previously made to improve the compactness of seed metering systems by moving the meter driveshaft from a concentric drive interface to a perimeter drive interface, driving the outer circumferential surface of the seed disk. Known perimeter drive systems still rely on a main driveshaft serving as a common power source for all the row planting units within a row crop planter. Although such previous perimeter drive units may improve compactness of seed metering systems to some extent, they fail to address numerous issues associated with operational uniformity of seed metering systems. 
   In modern farming practices, there is an increased reliance upon precision planting methods. Correspondingly, the integrity of modern seed metering system operations are closely related to system efficiency, consistency, accuracy, repeatability, and thus uniformity in placing seeds during use. Known seed metering systems, concentric drive and perimeter drive alike, face various performance unifornity issues related to the operation of conventional main, common driveshaft and meter driveshaft linkages. For example, the torque required to drive all of the seed metering systems by a common main driveshaft can be significant, since each seed metering system can experience high levels of friction during operation as, e.g. the vacuum force pulls the seed plate toward and into contact with the meter housing. As another example, non-uniform operation can result from non-desired rotational drive speed variations realized at the meter driveshaft as the chains and/or cables flex, relax, tighten, and slacken as the row crop planter traverses somewhat irregular field surfaces. Any of these and other operating characteristics can lead to erratic seed placement. 
   Additionally, typical seed planters do not have the ability to deactivate individual row planting units, independently of one another. This can lead to overseeding or overplanting, dispensing more seed than needed, during various instances in which portions of the seed planter passes over a segment of the field more than once. Such instances include those in which point rows are commonly utilized, such as while working fields having irregular shapes, or fields with trees or other obstacles therein. Other such instances include various field turn areas such as turn rows, headland rows, or end rows. Some efforts have been made to deactivate individual row planting units. However, such efforts require the use of complex, for example, pneumatic clutch assemblies with numerous parts and which can require relatively large amounts of energy to operate. 
   SUMMARY OF THE INVENTION 
   There is a need for a seed metering system that provides improved uniformity of seed placement during row crop planting. There is also a need for a seed metering system that reduces the number of moving parts and complex mechanical linkages in a seed planter. Furthermore, there is a need for seed planters which include multiple seed metering systems which can be activated and deactivated independently of each other such that individual row planting units can be engaged or disengaged independently as desired, whereby overplanting can be managed and minimized. 
   The present invention provides a direct drive electric seed metering system which meets the desires and needs described above, while being used, e.g., in combination with a row crop planter or seed planter. In a first embodiment of the present invention, a direct drive mechanism for use with a seed metering system is provided. The seed metering system can be of the vacuum-type and can have a metering housing that encapsulates a seed plate. The seed plate is rotatable and is adapted to transfer individual seeds from one portion of the metering housing to another where they are discharged. In vacuum-type implementations of the seed metering systems, the seed transfer by the seed plated is aided by vacuum or negative pressure, holding the seeds against the seed plate. 
   It is contemplated for the direct drive mechanism to be provided with a drive housing and prime mover attached to the drive housing. The drive housing is preferably attached to the metering housing. In such a configuration, the prime mover can drive an output gear that, in turn, drives the seed plate. As desired, the prime mover can be an electric motor, preferably a 12V DC electric motor. In some implementations, the output shaft of the prime mover can have a pinion gear mounted thereto, which drives the output gear, and thus, the seed plate. 
   In still further implementations, the direct drive mechanism interfaces with the outer circumferential surface of the seed plate and selectively rotates it. Such an interfacing relationship can be realized between the seed plate and the prime mover and/or the output gear of the direct drive mechanism. Accordingly, the outer circumferential surface of the seed plate and the outer circumferential surface of the output gear have corresponding structures which facilitate the transfer of force therebetween. As one example, the outer circumferential surfaces can have spur gear teeth, interfacing and meshing with each other. As another example, the outer circumferential surfaces can have helical gear teeth, interfacing and meshing with each other. 
   Other objects, features, and advantages of the invention will become apparent to those skilled in the art from the following detailed description and accompanying drawings. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the present invention, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the present invention without departing from the spirit thereof, and the invention includes all such modifications. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Preferred exemplary embodiments of the invention are illustrated in the accompanying drawings in which like reference numerals represent like parts throughout. 
       FIG. 1  illustrates a side elevational view of a portion of a seed planter incorporating a first embodiment of direct drive electric seed metering systems in accordance with the present invention. 
       FIG. 2  illustrates a side elevational view of the direct drive electric seed metering system shown in  FIG. 1 , with the metering cover removed. 
       FIG. 3  illustrates an enlarged side elevation of a portion of the direct drive electric seed metering system, shown in  FIG. 2 . 
       FIG. 4  illustrates a cross-sectional view of a portion of a direct drive electric seed metering system taken at line  4 - 4  in  FIG. 3 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring now to the drawings and specifically to  FIG. 1 , a portion of a multiple row crop planter implement or seed planter  5  is shown. The seed planter  5  is typically pulled by a tractor or other traction device (not shown). Seed planter  5  includes a toolbar  8  that holds multiple individual row planting units  10 , each row planting unit  10  being substantially identical. Only a single row planting unit  10  is shown for simplicity sake. 
   Row planting unit  10  includes a frame  12  that attaches the unit  10  to toolbar  8  by way of parallel linkages  15 . Row planting unit  10  has a leading end  17  which faces the direction of travel, indicated by arrow  20 . A trailing end  1   8  faces the opposite direction, away from the direction of travel  20 . Frame  12  supports a furrow opening mechanism  22  near the leading end  17  of row planting unit  10 , for cutting open the furrow to receive the deposited seeds. As is known in the art, the furrow opening mechanism  22  includes a pair of lateral spaced furrow opener disks  23 , a furrow forming point, and an opener shoe  24 . Optionally, the row planting unit  10  can include a runner-type opener for providing a furrow in the ground. 
   A furrow closing mechanism  25  is located at the opposing end of the planting unit  10 , near trailing end  18 . Closing mechanism  25  includes a pair of furrow closer disks  26  and a trailing wheel  28 . The closer disks  26  are mounted in front of the trailing wheel  28 , such that the two define a fore and aft aligned relationship relative each other. Correspondingly, after the closer disks  26  close the furrow, the trailing wheel  28  rolls over and tamps the furrow down. 
   In some implementations, an optional pesticide hopper  29  sits atop the frame, at the trailing end  18 . Pesticide hopper  29  contains, e.g., an herbicide or an insecticide and is provided with conventional dispensing means for applying controlled amounts of the contents in the desired locations while using seed planter  5 . 
   Seed hopper  30  is mounted atop frame  12 , as is optional herbicide or pesticide hopper  29 . Seed hopper  30  holds the seed supply for planting by the row planting unit  10 . The particular seed hopper  30  shown in  FIG. 1  is adapted and configured to store the seed material and gravitationally deposit the seed material to the ground as the seed planter  5  moves over and across the field. This procedure is explained in greater detail elsewhere herein. In other implementations, the seed supply is held in a primary seed hopper at a remote location, distant the various row planting units  10 , whereby the seeds are supplied to the row planting units  10  pneumatically, or otherwise, through a seed conduit. 
   Regardless of the particular configuration of seed hopper  30 , the seeds are directed from the seed hopper  30  to the seed metering system  50 . As best seen in  FIGS. 1-2 , seed metering system  50  includes vacuum port  52 , singulator assembly  55 , seed inlet  57 , meter housing  60 , seed plate  70 , and direct drive mechanism  100 . Vaccum port  52  extends from the meter housing  60  and is connected to a vacuum source (not shown). Singulator assembly  55  is attached to the meter housing  60  and is adapted and configured to inhibit more than one seed from being discharged from the seed metering system  50  per seed discharge event. Seed inlet  57  is an elongate enclosure or conduit extending and directing seeds between the seed hopper  30  and meter housing  60 . In such configuration, the seeds move, e.g., by way of gravity from the seed hopper  30  through seed inlet  57  and into a reservoir or void space within the meter housing, such as meter cavity  61 . 
   Meter housing  60  has a backing plate  62  and a cover  64 , which are connected to each other and define a meter cavity  61  therebetween. The meter cavity  61  houses the seed plate  70  therein. As seen in  FIG. 2 , vacuum port  52  extends outwardly from cover  64  and seed inlet  57  extends from backing plate  62 . In this configuration, it is apparent that the vacuum port  52  and seed inlet  57  are positioned on opposing sides of the meter housing  60  and seed plate  70 . As desired, the vacuum port  52  and seed inlet  57  are at least partially registered with each other, on opposing sides of the seed plated  70 . An opening  65  passes through the meter housing  60  permitting, e.g., portions or components of the direct drive mechanism  100  to extend into the meter cavity  61  and cooperate and interface with the seed plate  70 . 
   The seed plate  70  is a flat, disk-like member, having opposing front and back surfaces  72  and  74 , respectively. Seed plate  70  has a geared outer circumferential surface  75 , with, e.g., gear teeth radially extending therefrom. Seed pockets  76  are discrete openings that extend between front and back surfaces  72 ,  74 , and thus through the entire thickness of the seed plate  70 . The seed pockets  76  are spaced from each other, yet are radially spaced equidistant from an axis of rotation of the seed plate  70 . 
   Seeds are guided, by the seed inlet  57 , from seed hopper  30  to the meter cavity  61 , generally into the space between the back surface  74  of seed plate  70  and the inwardly facing surface of backing plate  62 . The seed plate  70  rotates in the meter cavity  61 , whereby the seed pockets  76  pass across and interface the seeds which accumulate in the meter cavity  61 . In vacuum-type implementations of the seed metering system  50 , the vacuum or negative pressure is drawn through the vacuum port  52  and thus also through the seed pockets  76 . In other words, vacuum or negative pressure is drawn from the beyond the front surface  72  which draws the seeds into the seed pockets  76 , against the back surface  74  of seed plate  70 . Regarding the particular vacuum-based methods and devices to apply negative pressure or vacuum to the seek pockets  76 , any of the various conventional vacuum-based seed metering techniques will suffice. However, preferred structures, apparatuses, and methods are disclosed in commonly owned U.S. application Ser. No. 10/388,342, entitled SEED PLANTER APPARATUS AND METHOD, filed on Mar. 13, 2003 and issued as U.S. Pat. No. 6,776,108 on Aug. 17, 2004, which is herein incorporated by reference, in its entirety. 
   The vacuum holds the seeds in the seed pockets  76  where they are rotatably transported in unison with the rotation of seed plate  70 . As the seeds rotate with seed plate  70 , and thus as they approach the discharge portion of the seed metering system  50 , the seeds encounter the singulator assembly  55 . Singulator assembly  55  is a conventional seed singulator device which insures that one and only one seed is present in each seed pocket  76  as each particular seed pocket  76  approaches the discharge area of the seed metering system  50 , for dispensation through seed tube  80 . The seeds that are delivered into seed tube  80  are deposited into the furrow, between the furrow opening and closing mechanisms  22  and  25 , respectively. 
   Seed tube  80  is a generally upright or vertical passage, which directs the seed to the ground or furrow for planting. Preferred versions of suitable seed tubes  80  are disclosed in commonly owned U.S. application Ser. No. 08/581,444, entitled SEED METERING APPARATUS SEED TUBE, filed on Dec. 29, 1995 and issued as U.S. Pat. No. 5,974,988 on Nov. 2, 1999, which is herein incorporated by reference, in its entirety. 
   Referring now to  FIGS. 3-4 , seed plate  70 , rotates by way of its driven cooperation with direct drive mechanism  100 . Direct drive mechanism  100  selectively rotates or drives the seed plate  70  at a variable speed. The particular speed at which speed plate  70  is driven by the direct drive mechanism  100  is related, at least in part, to the ground speed or travel velocity of seed planter  5 . The direct drive mechanism  100  includes prime mover  110 , drive output assembly  120 , and drive housing  130 , and is directly attached to the remainder of the seed metering system  50 . Prime mover  110  is preferably an electric motor with an output shaft  112 , and, more preferably, a 12V DC electric motor with an output shaft  112 . Conductors  114  operably connect the prime mover  110  to a controller  115  and a power supply  117  ( FIG. 1 ) which can be electrically connected to the 12V DC electrical system of the tractor. The controller  115  is further operably connected, in a conventional manner, to any of a variety of suitable sensors for sensing, e.g., travel velocity of the row crop planter  10 , and/or other operating characteristics, which will be evaluated by the controller  115  in determining the desired rate of rotation of seed plate  70  by energizing direct drive mechanism  100 . 
   The particular configuration of drive output assembly  120  is selected based on the operating characteristics of prime mover  110  and seed plate  70 . In preferred embodiments, drive output assembly  120  provides an output gear  125  which rotates at a variable speed between 0-rpm and 600-rpm. Accordingly, for implementations of prime mover  110  that suitably operated with an output shaft speed of between 0-rpm and 600-rpm, the output assembly can be the output gear  125  alone. Stated another way, in some implementations, the output gear  125  is mounted concentrically to the prime mover  110  output shaft  112  and it directly interfaces with and drives the geared outer circumferential surface  75  of seed plate  70 . 
   In other implementations, the drive output assembly  120  includes other transmission or gear train components, for example, when the primer mover  110  optimally functions at operational speeds of about 2,000-3,000-rpm. In such implementations, the drive output assembly  120  includes output gear  125  and pinion gear  127  that is mounted to the output shaft  112  of the prime mover  110 . The diameters of output and pinion gears  125  and  127 , respectively, are selected to mechanically step down the 2,000-3,000-rpm shaft speed of prime mover  110  to the desired 600-rpm maximum rotational speed of output gear  125 , ensuring the desired rotational operation speeds of seed plate  70 . Besides realizing different rotational rates of seed plate  70  and output shaft  112 , multiple gears such as output and pinion gears  125  and  127 , respectively, can be implemented based on other gear-train kinetic reasons. For example, both output and pinion gears  125  and  127 , respectively, can be included in the direct drive output assembly  100  when it is desired to have the seed plate  70  and the prime mover output shaft  112  rotate in the same direction. 
   Regardless of whether output gear  125  or pinion gear  127  is mounted to output shaft  112 , the output gear  125  and the geared outer circumferential surface  75  of seed plate  70  are configured in a cooperating, force transmitting, preferably gear teeth meshing manner. Accordingly, outer circumferential surface  75  and the outer circumferential surface of output gear  125  can have cooperating, e.g., spur gear teeth, helical gear teeth, or suitable force transmitting configurations. 
   Drive housing  130  includes mounting plate  132  that is connected to, and optionally integral with, meter housing  60 . Drive housing  130  has an open end  135  having a perimeter shape and configurations that correspond to the perimeter shape and configuration of the meter housing opening  65 . In the complete assemblage, the void space within drive housing  130  and the void space within meter housing  60  commingle within the intersection of drive housing open end  135  and meter housing opening  65 . In this configuration, the output gear  125  can extend into meter housing  60  whereby the gear teeth of the seed plate  70 , geared outer circumferential surface  75 , and those of the output gear  125  can mesh and cooperatively interface. 
   Prime mover  110  and output gear  125  are attached to mounting plate  132 . In some implementations, prime mover  110  extends outwardly from a first side  133  of the mounting plate  132  and its output shaft  112  extends through a bore  140 , outwardly from the second side  134  of the mounting plate  132 . Pinion gear  127  is rotatably mounted to a pin  142  that is attached to and extends from the second side  134  of the mounting plate  132 . Accordingly, prime mover  110  extends from an opposing side of mounting plate  132 , as compared to output shaft  112  and pinion gear  127 . Output gear  125  is mounted on the same side of mounting plate  132  as output shaft  112  and pinion gear  127 , and meshes with both pinion gear  127  and seed plate  70 . In other words, output gear  125  provides the means to transfer the rotational force of direct drive mechanism  100  to seed plate  70 . 
   It is apparent that direct drive mechanism  100  eliminates, mitigates, or otherwise reduces the need for a typical main driveshaft, common to all row planting units  10  of the seed planter  5 . Direct drive mechanism  100  further eliminates, mitigates, or otherwise reduces the need for any, e.g., meter driveshaft or jackshaft to drive the seed plate  70 . This is because each row planting unit  10  has its own direct drive mechanism  100  attached directly thereto, and each direct drive mechanism  100  has its own prime mover  110 . In this configuration, there is no need for a common source of mechanical energy to power the drive assemblies  100  through, e.g., chains, cables, or other mechanical linkages. Rather, the number of drive assemblies  100  and the number of prime movers  110  corresponds to, preferably are equivalent to, the number of row planting units  10  utilized by the seed planter  5 . 
   In light of the above, during use, the desired seed type is received from the seed hopper  30 , through the inlet  57 , into the seed metering system  50 . Simultaneously, furrow opening mechanism  22  opens a trough or furrow to receive seeds. Drive mechanism  100  rotates the seed plate  70  by energizing the prime mover  110 , rotating its output shaft  112 . The output shaft  112  rotates the pinion gear  127 , which correspondingly rotates the output gear  125 . The teeth of output gear  125  mesh with and drive the corresponding teeth on the geared outer circumferential surface  75  of the seed plate  70 . 
   Vacuum is applied from the front surface  72  of the seed plate  70 , drawn through the seed pockets  76 , thereby drawing seeds from the meter cavity  61  into the seed pockets  76 . As desired, in some configurations, a positive pressure airflow can be provided toward the back surface  74  to enhance the transfer of seeds from the meter cavity  61  to the seed pockets  76 . The seed plate continues to rotate which draws the seeds in the seed pockets  76  radially away from the mass of accumulated sees in the meter cavity  61 . All but one seed per seed pocket  76  are removed by the singulator assembly  55 , and each such single seed is ultimately discharged from the system  50  through seed tube  80  into the furrow. As the seed planter  5  advances further, the furrow closing mechanism  25  closes the furrow with the seeds therein and the trailing wheel  28  tamps down the closed furrow. 
   All the while, the controller  115  ( FIG. 1 ) monitors the ground speed or travel speed of the seed planter  5 , the rotational velocity of the seed plate  70  or the seed depositing rate from seed metering system  50 , and, as required, adjusts or regulates the operating characteristics of the seed metering system  50  to suitably correspond to the ground speed. The desired instantaneous seed depositing rate is a function of the travel velocity of the seed planter  5  at that instant, whereby such desired depositing rate can be predicted and sought by the controller. Accordingly, the seed metering system  50  is selectively driven by drive assembly  100 , preferably at a variable rate and, more preferably, at an infinitely variable rate, based at least in part on the ground speed or travel velocity of seed planter  5 . 
   Furthermore, preferred implementations include a single controller  115  which controls all of the drive assemblies  100 , and thus, the operating characteristics of all of the seed metering systems  50 . Doing so can ensure that each drive assembly  100  receives the same control signals, whereby the resultant output responses of the assemblies  100  should be substantially analogous, when that is desired. This can enhance uniformity of seed placement between the individual rows and other operating characteristics. 
   However, controller  115  can also control the individual drive assemblies  100  independently of each other, optionally each row planting unit has its own controller  115 . In such configuration, the row planting units  10  can be activated and deactivated independently of each other, whereby overplanting can be managed and minimized. Accordingly, when using row crop planting techniques such as, e.g., planting point rows, turn rows, headland rows, or end rows, or in other situations which could lead to double planting or other overplanting conditions, the operator can de-energize and thus disengage any one or more of the individual row planting units as desired. This enables the user to comprehensively manage the application of seed, on a per row planting unit and thus per row basis. Moreover, since each row has its own controller, the user can apply corn at different population rates on each individual row, as desired. This can be particularly beneficial to growers that grow seed corn for the industry and are planting different varieties, or “male only” seeds, or otherwise desire different population rates in the individual row planting units  10  on the planter  5 . 
   While the invention has been shown and described with respect to particular embodiments, it is understood that alternatives and modifications are possible and are contemplated as being within the scope of the present invention. A wide variety of ground-engaging implements (e.g., conventional seeders, seed planters, and row crop planters) can employ the direct drive electric seed metering system  50  of the present invention. In addition, it should be understood that the number of direct drive electric seed metering systems  50  employed on the row crop planter or seed planter  5  is not limiting on the invention. 
   Many changes and modifications could be made to the invention without departing from the spirit thereof. The scope of these changes will become apparent from the appended claims.