Patent Description:
In accordance with the invention, there is provided a method of controlling downforce on an air seeder as set out in the appended claims.

Air seeders having variable applied downforce seeding and fertilizing tools are known in the art. One such prior art air seeder having variable applied downforce seeding and fertilizing tools is disclosed in <CIT> ("the '<NUM> Publication"). The Mid Row Bander™ from Bourgault Industries, Ltd. , is a commercial embodiment of the air seeder disclosed in the '<NUM> Publication. Another example of a prior art air seeder having variable applied downforce seeding and fertilizing tools is disclosed in U. Patent Publication No. <CIT> ("the '<NUM> Publication"). A commercial embodiment of the air seeder disclosed in the '<NUM> Publication is the Separate Fertilizer Placement Air Drill <NUM> from Deere and Company.

<FIG> is a perspective view of a section of an air seeder implement <NUM>. As described in the '<NUM> Publication, the implement <NUM> includes a frame <NUM> comprising front, middle, and rear lateral frame members 215F, <NUM>, and 215R. The frame <NUM> is mounted on wheels (not shown) for travel over the ground in an operating travel direction P. Seed assemblies <NUM> are placed at substantially regular intervals along the middle and rear frame members <NUM>, 215R so that the seed furrows created are substantially parallel at approximately regular intervals. The fertilizer assemblies <NUM> are spaced at regular intervals along the front frame member 215F so that the fertilizer furrows opened by the knives <NUM> of the fertilizer assemblies <NUM> are positioned substantially mid-way between adjacent pairs of seed furrows created by the seed assemblies <NUM> as best shown in the front elevation view of <FIG>.

The knives <NUM> of the fertilizer assemblies <NUM> engage the ground along a front line substantially perpendicular to the operating travel direction and about directly under the front frame member 215F, while the first set of seed assemblies 250F are mounted on the middle frame member <NUM> and engage the ground along a middle line rearward of the front frame member 215F and the knives <NUM>, generally under the rear frame member 215R. The seed assemblies 250R mounted on the rear frame member 215R engage the ground along a rear line rearward of the rear frame member 215R. Ample spacing is thus provided for each ground engaging element, fertilizer knives <NUM> and seed knives <NUM>.

The seed assemblies <NUM> comprise a trailing arm <NUM> pivotally connected at a front end thereof to the frame <NUM> about substantially horizontal and parallel front arm axes AA and AA' oriented substantially perpendicular to the operating travel direction P. A seed furrow opener, illustrated as a seed knife <NUM>, is attached to the trailing arm <NUM> and is operative to create a seed furrow when a bottom end thereof is engaged in the ground. A seed feed <NUM> is mounted to the rearward side of the seed knife <NUM>. A packer wheel <NUM> is rotatably attached rearward of the seed knife <NUM> and is oriented to roll substantially along the seed furrow.

A parallel linkage <NUM> comprises upper and lower links <NUM>, <NUM>, each pivotally attached at forward ends thereof about axes AA and AA' respectively. Rear ends of the links <NUM>, <NUM> are pivotally attached to the forward ends of a packer bracket <NUM> about axes BB and BB' respectively. The axes AA, AA', BB, and BB' are oriented such that the upper and lower links <NUM>, <NUM> are parallel as they move up and down.

Packer wheel arm <NUM> is pivotally attached at a front end thereof to the packer bracket <NUM> about axis BB', and packer wheel <NUM> is rotatably attached to the rear end of the packer wheel arm <NUM>. Seed shank <NUM> is pivotally attached at a mid-portion thereof to the packer bracket <NUM>. Seed knife <NUM> is attached to a bottom end of the seed shank <NUM>. During field operations, a first port <NUM> of the hydraulic cylinder <NUM> is connected via a valve <NUM> to an active hydraulic source <NUM>, such that the hydraulic cylinder <NUM> acts as a trailing arm actuator and exerts a substantially constant bias force BF on the top end of the seed shank <NUM>, causing same to pivot about the axis BB' and bear against a stop on the packer bracket <NUM> such that the bias force is transferred to the packer bracket <NUM> and parallel linkage <NUM> which are pushed downward to force the bottom end of the knife <NUM> in the ground and create the seed furrow. Seed is provided to the seed feed <NUM> and is deposited into the seed furrow created by the seed knife <NUM>.

A packer adjustment brace <NUM> is attached to the packer wheel arm <NUM> and engages a slot in the packer bracket <NUM>. The brace <NUM> is moved along the slot to set the vertical position of the seed knife <NUM> with respect to the packer wheel <NUM> at the required location to provide a desired depth D2 of the seed furrow and then the brace <NUM> is locked to the packer bracket <NUM>. The bias force BF pushes the packer wheel <NUM> against the ground <NUM>.

To move the knife <NUM> up and out of engagement with the ground, the active hydraulic source <NUM> is connected to a second port <NUM> on the hydraulic cylinder <NUM> to retract the hydraulic cylinder <NUM> and pivot the top end of the seed shank <NUM> toward the hydraulic cylinder <NUM> and cause a recess in the seed shank <NUM> to bear against a pin providing the axis BB at which point further retraction of the hydraulic cylinder <NUM> raises the parallel linkage <NUM> of the trailing arm <NUM>, and the packer wheel arm <NUM> to the transport position.

Each fertilizer assembly <NUM> comprises a mounting bracket <NUM> attached to the frame <NUM>. The mounting bracket <NUM> is connected to an elongate member <NUM> through a height adjustable connection <NUM>. By using the height adjustable connection <NUM>, the distance between the bottom of the fertilizer knife <NUM> and the frame <NUM> can be varied to set the depth D1 of the fertilizer furrow. A fertilizer knife shank <NUM> is pivotally connected to the lower end of the elongate member <NUM> with a shank pin <NUM>, and a fertilizer knife <NUM> is attached to the fertilizer knife shank <NUM> and is biased downward by a hydraulic cylinder <NUM>.

The hydraulic cylinder <NUM> is connected via a valve <NUM> to the active hydraulic source <NUM> at a first port <NUM> thereof and exerts a downward force on the fertilizer knife <NUM> by exerting an upward bias force BF on the front end of the knife shank <NUM> forward of the shank pin <NUM>. The bias force BF is sufficient to maintain the fertilizer knife <NUM> at an operating position at the maximum downward position during normal operations, thereby maintaining the fertilizer knife <NUM> at a substantially constant vertical position with respect to the frame <NUM>, such that as the frame <NUM> moves across a field, the depth of the fertilizer furrow D1 is maintained more or less consistent, as the frame <NUM> will move up and down on the wheels of the implement following the ground, as is well known in the art. When the fertilizer knife <NUM> contacts an obstruction, such as a rock or the like, the knife will trip and move upward against the bias force of the hydraulic cylinder <NUM> to clear the obstruction, and then move to the operating position again. Fertilizer is provided to the fertilizer feed <NUM> and is deposited into the fertilizer furrow created by the fertilizer knife <NUM>.

Because the frame <NUM> is fixed in vertical relationship to the wheels carrying the frame, the seed knives <NUM> and packer wheels <NUM> are raised from the operating position shown in <FIG> to the transport position (not shown) by the hydraulic cylinder <NUM>, while the frame stays at a constant vertical position with respect to the ground. Similarly, the active hydraulic source <NUM> is connected to a second port <NUM> on the hydraulic cylinder <NUM> to extend the hydraulic cylinder <NUM> and move the fertilizer knives <NUM> upward to the raised transport position.

While the air seeder <NUM> of the '<NUM> Publication as described above and as illustrated in <FIG>, may serve its intended purpose, it is recognized that the depth placement of fertilizer is not as critical as the depth placement of the seed. Accordingly, by managing the total applied downforce or downpressure of all the seeding assemblies <NUM> and the fertilizing assemblies <NUM> across the implement <NUM>, the more critical seed planting depth can be ensured by increasing the downforce applied to the seeding assemblies <NUM> as necessary to maintain the proper seed planting depth while correspondingly reducing the applied downforce of the fertilizer assemblies <NUM>.

One method of managing the total applied downforce of the implement to ensure acceptable seed planting depth may be to determine a total downforce FT of the implement <NUM> by summing the downforce applied to each of the seed assemblies <NUM> (the "Seed Assembly Applied Force" or "SAAF") and the downforce applied to each of the fertilizer assemblies <NUM> (the "Fertilizer Assembly Applied Force" or "FAAF"). The total downforce FT is then compared to a maximum downforce FM. The maximum downforce FM may be the total weight of air seeder <NUM> or it can be an amount set by the operator, which is less than the total weight of air seeder <NUM>. If the total downforce FT is greater than the maximum downforce FM, the FAAF applied to each of the fertilizer assemblies <NUM> is reduced by a proportional amount of the total downforce FT until the total downforce FT is less than the maximum downforce FM. This allows each of the seed assemblies <NUM> to maintain the necessary SAAF to keep the depth of seed planting at an acceptable level. In one embodiment, the total of the FAAF is less than the total of the SAAF.

Although the embodiment of the air seeder <NUM> is described and illustrated with hydraulic actuators to provide the variable applied downforce, it should be appreciated that any device capable of applying a variable downforce can be used in place of the hydraulic cylinders, including but not limited to, pneumatic cylinders or electronic linear actuators.

<FIG> is a schematic embodiment of a control system <NUM> for controlling the SAAS and FAAF, such as the PackMaster™ control system from Bourgault Industries, Ltd. The control system <NUM> includes a load cell <NUM> installed on axle <NUM> (<FIG>) where packer wheel <NUM> is mounted to packer wheel arm <NUM>. The load cell <NUM> is in electrical communication with a monitor <NUM>. The monitor <NUM> may be mounted within the cab of the tractor (not shown) pulling the air seeder implement <NUM> through the field. The monitor <NUM> may include a central processing unit ("CPU"), memory and a graphical user interface ("GUI") allowing the user to view and enter data into the monitor. An example of a suitable monitor is disclosed in <CIT>.

Monitor <NUM> is in communication with the valve <NUM> to control pressure in hydraulic cylinder <NUM> to adjust the SAAF applied by cylinder <NUM> based on a selected value entered into the monitor <NUM> by an operator. An amplifier <NUM> and an analog/digital converter <NUM> may be disposed between the load sensor <NUM> and the monitor <NUM>. To control the FAAF, the monitor <NUM> is in communication with the valve <NUM> to control the pressure in hydraulic cylinder <NUM>. Knowing the amount of pressure applied to cylinder <NUM> to adjust SAAF, pressure in hydraulic cylinder <NUM> is maintained at an amount equal to or less than hydraulic cylinder <NUM>.

In another embodiment, seed assembly <NUM> may be replaced with a disc opener unit (such as that referenced as element "(<NUM>)" in U. Patent Publication Nos. <CIT> and <CIT> ("the '<NUM> and '<NUM> Publications"). In such an embodiment, load cell "(<NUM>)" as disclosed in the '<NUM> and <NUM> Publications is used in place of load cell <NUM> in the control system <NUM>.

Claim 1:
A method of controlling downforce on an air seeder (<NUM>), said air seeder comprising:
a frame (<NUM>);
a plurality of seed assemblies (<NUM>) disposed on said frame for planting seeds in a plurality of seed rows, each of said plurality of seed assemblies having a seed assembly actuator (<NUM>) to adjustably apply a seed assembly downforce; and
a plurality of fertilizer assemblies (<NUM>) disposed on said frame and disposed to place fertilizer between said seed rows, each of said plurality of fertilizer assemblies having a fertilizer assembly actuator (<NUM>) to adjustably apply a fertilizer assembly downforce;
said method comprising:
summing said seed assembly downforce of all of said plurality of seed assemblies (<NUM>) and said fertilizer assembly downforce of all of said plurality of fertilizer assemblies (<NUM>) to determine a total applied downforce;
comparing said total applied downforce to a maximum downforce; and
reducing said total applied downforce when said total applied downforce is equal to or greater than said maximum downforce;
wherein the step of reducing said total applied downforce includes reducing said fertilizer assembly downforce of all of said plurality of fertilizer assemblies (<NUM>) while maintaining said seed assembly downforce of all of said plurality of seed assemblies (<NUM>).