As the amount of genetically modified (GM) crops planted increases, it is prudent that additional care be taken to protect the various types of crops from contamination with a different crop. Greater vigilance must be taken to insure that identity-preserved grains remain segregated from planting, through harvesting and packaging in seed bags, and to the time it reaches its final market. Contamination tolerances vary from one variety to another, and some, such as corn containing the Starlink gene, can have a zero level contamination for human food consumption (Gil Gullickson, “Snowed Under By Starlink?”, Farm Industry News, Feb. 1, 2001). In extreme cases, the negative result of such contamination can be devastating to the person or company at fault for the contamination.
One of the areas for potential contamination is in a planter. A typical planter has row units, which apply the seed, and which are supplied seed via a row hopper or a shared hopper through a plenum, for example. Each row unit typically includes a seed meter to dispense seeds at a controlled rate into a seed furrow as the seed meter is advanced above and along the seed furrow. In a typical arrangement, a tractor is coupled to tow a tool bar to which are attached in a generally parallel, spaced apart relation a plurality of planting units with a seed meter arrangement attached thereto. In addition to the seed hoppers discussed above, the planters can include a device for opening a furrow in the ground as the tractor drawn tool bar is advanced across the field over the ground, and the seed meter is coupled to the seed hopper for dispensing individual seeds into the furrow at a controlled rate, and a further device for moving soil at the sides of the furrow to close the furrow over the seeds.
With the high adoption rate of GM seeds, it is becoming necessary for farmers to clean the seed out of their planter's seed hopper and meter more often and more completely. Older design planters require the removal of the seed hopper and/or meter and often require removing additional doors or the seed disk itself in order to remove all of the seeds.
The many different types of seeds to be planted using a seed metering mechanism include corn, cotton, sorghum, sugar beets, soybeans and sunflowers, to name a few, and such seeds vary considerably in size, weight and shape. Despite these numerous differences in the size, shape and surfaces of such seeds, seed meters are expected and are required to handle all different types of seeds described above plus many more, while requiring minimum effort regarding part changes and adjustments. Different seed meter devices have been developed and include a mechanical type which typically has a vertical or horizontal seed plate or disc with mechanically actuated fingers or similarly operated mechanical devices for separating individual seeds from the seed disc and then dispense them into the furrow. While some mechanical seed meters are satisfactory for certain applications, they typically suffer from a number of limitations including the limited speed at which they can accurately dispense seeds, and inability to handle different type seeds without making cumbersome and extensive part changes, and an inherent design complexity which may typically add to the cost, wear and maintenance problems of the mechanically operated seed dispensing mechanisms.
Another type of seed meter includes a seed metering mechanism which utilizes an air pressure differential which has been developed in an effort to overcome some of the problems of the mechanical seed meters. Air pressure differential seed meters, which are commonly known as air seed meters, are generally of two types. The first type being the positive pressure type and the second type relying upon negative pressure or vacuum.
In the positive pressure type of air seed metering mechanism, air is blown into the seed chamber and onto the surface of a rotating or otherwise movable and apertured member or disc in order to create the higher than atmospheric pressure in the chamber. This forces seeds from a seed mass onto the seed member or disc where they are retained for later release. The apertures or holes in the rotating member or disc are open to atmosphere where the individual seeds are held by the blowing air until the seeds are dispensed by interrupting the flow of air to the seeds.
While air seed meters of the positive pressure type offer certain advantages over mechanical seed meters, they have certain limitations of their own which may prove to be a significant disadvantage for various seeding applications. In an effort to fill each hole or opening with a seed as the seed disc rotates through the seed mass, a relatively high pressure differential is applied to the disc. Because the seeds are held in place on the rotating disc or other movable member by differential pressure resulting from positive pressure in the chamber, it is usually necessary that the air flow be directed through the seed mass to aid in the depositing of individual seeds onto the disc. The air flow has been found to interfere with the orderly delivery of seeds from the disc and, ultimately, to the ground. In positive pressure seed metering mechanisms, the seed hopper must be sealed to maintain pressure in the system. If for any reason the hopper lid comes off or the hopper otherwise becomes unsealed, the seed meter will not properly function.
Vacuum seed meters have been found to overcome some of the problems in the positive pressure seed meters and offer more control over the seed being transported by the seed disc. In vacuum seed meters, a vacuum source is typically coupled to a separate chamber on the opposite side of the seed disc from the seed mass with the vacuum communicating through the apertures in the seed disc to the seed mass. The vacuum is of sufficient magnitude such that it tends to draw seeds into the openings defined by the disc and hold the seeds thereto as the seeds are moved through the seed disc under the influence of the moving seed disc toward the seed discharge area of the seed metering mechanism. The openings between the outer surface of the seeds and the periphery of the openings in the disc allow air to pass therethrough thereby maintaining the seeds in operable association with the disc. Because the pressure differential at the seed disc comes from a vacuum source on the opposite side thereof and not from the flow of air at the same side thereof as with positive pressure type seed metering mechanisms, the problem of having to direct an air flow through the seed mass and on to the seed disc are eliminated.
Despite the various advantages of vacuum seed meters, over seed meters of the positive pressure type or mechanical type, presently known vacuum seed meters are not without problems of their own relative to clean out. Some designs now offer easier and faster clean out of seeds for vacuum style seed meters by providing a hinged door on the vacuum side of the seed meter. These designs have the disadvantage of still having to remove the seed disk in order to allow the seed to be removed. They also do not allow all of the seeds to be removed without having to use your hand or a brush to get 100% cleanout. A collection tray is provided, but since its sized is limited the tray must be emptied several times into a larger container when the hopper is being emptied.
There are other designs which have a cleanout door on the seed side of the seed meter that unlatches and allows the remaining seed in the hopper to flow through the door into a container. However, the door does not allow all of the seed to be removed from the seed meter. In order for all of the seed to be removed, the entire hopper and meter assembly must be removed from the row unit and emptied into a container by tipping it upside down. In addition, the seed vacuum cover must be removed so that all of the seeds can be removed from the meter.
What is needed in the art is a seed meter apparatus and method which allows for a relatively quick and complete cleanout of seeds from the seed meter.