Liquid application unit for air seeders

A liquid application unit for use on air seeders is provided which is cost-effective, has low maintenance and is highly reliable. This unit permits farmers to apply liquid substances, i.e. seed treatment substances to particulate material, namely seeds, just prior to the seed being inserted into the soil. The system uses an auger having two different pitches of flighting and/or different diameter flighting such that the volume available in between pitches of the flighting on the portion of the auger outboard of the orifice is greater than the volume available between the pitches inboard of the orifice. Chemicals are applied downstream of a sump area where the auger has either a larger pitch or larger diameter such that the volume available to the seed in the downstream area of the sump is greater. This will allow for better mixing action and minimize any effects on metering accuracy caused by build-up of chemicals on the flighting. In this device seed and chemicals are mixed by the rotation of the auger flighting within its cylinder.

This invention relates to air seeders generally used for inserting 
fertilizer or seed into agricultural fields. More particularly, this 
invention relates to a metering auger/chemical applicator system which is 
attached directly to an air seeder. 
BACKGROUND 
Farmers are continually seeking methods that allow them to farm more 
efficiently. They are also concerned about disposing of treated seed which 
can create an environmental hazard to animals. 
It is an object of present invention to provide a highly cost-effective, 
low maintenance and highly reliable liquid application unit for use on air 
seeders to provide farmers with the ability to apply liquid substances to 
particulate matter only as it is being consumed for insertion into the 
soil. 
It is also an object of the present invention to have an effective system 
which compensates for instantaneous changes in material application rate, 
to keep the amount of seed treatment per bushel of grain constant. 
It is also an object of the present invention to provide a system or 
delivery unit which allows for variances in ground speed in order that the 
rate of product metered per hour changes accordingly. 
SUMMARY OF THE INVENTION 
The inventors of the present invention have found that a two-pitch or 
two-diameter metering screw is an effective way to accurately meter, mix 
seed and liquid treatment and to discharge material into an air stream of 
an air seeder. A sump is located and attached to the bottom of the bins of 
the air seeder cart. The area of the sump is much wider than the width 
taken up by the flighting. This minimizes the amount of drag on the 
metering screw and allows particulate to flow around the screw to ensure 
complete filling of the flighting. In a preferred embodiment, the 
flighting located in the sump before the downstream orifice has a smaller 
pitch and is of smaller diameter than the flighting which is located after 
the downstream orifice. This ensures that the larger flighting cannot be a 
bottleneck in the metering system and will also provide for good mixing 
action for the seed and liquid seed treatment. 
The invention includes a metering screw assembly, a metering screw housing, 
a liquid metering pump, at least one liquid treatment injection port and a 
liquid holding tank all attached to the air seeder. The metering screw 
assembly includes flighting attached to shafting such that the shafting 
extends past both ends of the screw flighting. The liquid metering pump 
communicates directly with the metering screw assembly to instantaneously 
adjust the output of the pump as to the rotational speed of the metering 
screw. 
A sheave is placed on one end of the shafting supporting the flighting. A 
driven sheave is either placed on or attached directly or indirectly to 
the input shaft of the metering pump, depending on the location of the 
pump. The drive and driven sheaves are connected by an endless belt or 
chain. In a preferred embodiment, the sheaves and belt are notched to 
provide positive drive. 
A holding tank contains one or more liquid chemicals and a tubular line 
connects the holding tank to the input port of the pump. The output of the 
pump is connected by a tubular line to the injection port(s) located on 
the housing downstream of the sump. In a preferred embodiment, the 
injection port(s) is(are) located just downstream of where the transfer 
tube portion of the metering screw housing and the inner sump wall 
connect. 
On the bottom of the sump is located a removable cover which, once removed, 
allows complete emptying of the air seeder bin. The sump also has openings 
on both ends for the metering screw. The diameter of the hole in the 
outboard end of the sump is slightly larger than the diameter of the 
metering screw shaft. On the inboard end of the sump, the strategically 
sized hole acts as an orifice and interacts with a metering screw to 
produce consistent and predictable metering. 
One or more injection port(s) is(are) located on the transfer tube 
downstream of the orifice located in the sump. Injectors are typically 
nozzles for dispersing liquid over a large area on the particulate 
materials as they pass. The particulate material is further acted upon by 
the rotation and translation of the metering screw which further assists 
to distribute the liquid more uniformly over the outer surfaces of the 
seed or other treated particles. When the particulate material exits the 
metering assembly it has the liquid treatment efficiently and uniformly 
applied to the particulate material so that no further mixing action is 
required although more may occur in the air stream. 
In normal operation, the metering assembly moves the treated material into 
the transfer ducts that contain a high-speed air stream. The air stream 
carries the treated material away from the air seeder bins to be deposited 
either in or on top of the soil. In a preferred embodiment, the metering 
pump is a positive displacement piston pump and is connected by belts and 
sheaves to communicate with a metering screw. For a given product, the 
output of the metering system increases as the rotation speed of the 
metering screw increases, as does the output of the pump. Normally, the 
particulate requires a specific amount of liquid treatment per pound of 
material. The output per revolution of the pump can be varied by changing 
the stroke that the piston displaces. This allows the operator to vary the 
output of the metering pump to match the particular requirements of 
different treatments and materials. 
Therefore this invention seeks to provide an improved metering auger 
assembly for use with an air seeder cart; said assembly including an 
auger, a sump and a downstream housing fixedly attached to said sump; said 
downstream housing further including a liquid chemical injection means 
adapted in operation to spray liquid pesticides or herbicides on 
particulate matter; said sump being in open communication with particulate 
within said air seeder cart, and said downstream housing including a 
discharge port at one end remote from said sump; the improvement being a 
first portion of said auger is adapted to rotate within said sump and the 
second portion is adapted to rotate within said downstream housing; 
wherein, in operation, said first portion having a lesser volume available 
between adjacent pitches of the flighting for each revolution of said 
auger than said second portion. 
This invention further seeks to provide a system attached to an air seeder 
for applying liquids to particulate materials including: a) a metering 
screw housing capable of receiving particulate materials from an air 
seeder bin, b) a tank for holding said liquids, c) at least one liquid 
injection port located in said metering screw housing for receiving and 
dispersing said liquids, d) a metering screw assembly rotatable within 
said metering screw housing and capable of accurately metering said 
particulate materials into transfer ducts used to convey said particulate 
materials to an implement delivering said particulate material into or 
onto an agricultural field, e) a liquid metering pump in direct 
communication with said metering screw assembly, said liquid metering pump 
capable of receiving said liquid from said holding tank and delivering 
said liquid to said liquid injection port where said metering pump's 
output varies proportionally with a change in the rotational speed of said 
metering screw assembly.

DETAILED DESCRIPTION OF THE INVENTION 
In FIGS. 1 and 2 there is a downstream metering housing or transfer tube 1. 
It is connected to a sump 2 which has a discharge orifice 3. The 
downstream metering housing 1 is equipped with a discharge port 4. In this 
embodiment a pressurization port 5 is also used. 
The metering screw assembly is shown generally as 6. It has a first section 
of flighting 7 which, in this embodiment, is of lesser diameter and 
generally of smaller pitch. This portion of the metering auger is adapted 
to rotate within the sump 3 and carries a smaller volume per each 
revolution. Located on the shaft 14 is a downstream portion of the 
metering auger 8 which, in this embodiment, has a wider diameter flighting 
as well as larger pitch. However, it is to be understood that all that is 
necessary for the invention is that the downstream portion be capable of 
carrying a larger volume per revolution than the upstream portion located 
in the sump. This ensures that particulate material is basically moved 
translationally rather than rotationally in the downstream portion and 
therefore ensures that the seed and liquid seed treatment will mix 
adequately. 
On the downstream end of a first embodiment of the invention is a 
connecting block 9 over which is placed a gasket 10 and a bearing 11. 
Bolts 12 and nuts 13 secure the bearing, gasket and connecting block to 
the downstream end of the metering housing 1. Shaft 14 of the metering 
screw assembly rotates with the bearings 11 at one end and 22 at the 
opposite end of the sump 2. 
The sump has an open top or housing inlet 15 which is secured to the bottom 
of the hopper of an air seeder bin (not shown). The sump is also equipped 
with a lower clean out cover which is fastened to the bottom of the sump 
by means of wing bolts 17. Both the sump and the air seeder hopper can be 
completely cleaned out, when seed changeover is necessary. On the upstream 
side of the sump, nuts and bolts 18, 22 and 19 secure the connecting block 
20, gasket 21 and bearing 22 to the sump. 
FIG. 2 illustrates a first embodiment of the invention without the chemical 
injection apparatus. One notes the significant difference in the size and 
pitch of the two parts of auger assembly 3. 
FIGS. 3, 4 and 5 show a preferred embodiment of the invention. An injection 
port 25 is secured just downstream of the sump discharge orifice 3. The 
injection port 25, which is a wide spread nozzle, carries liquid herbicide 
or pesticide from hose 26 which is connected to pump 27. Particulate 
material passing through downstream metering housing 1 is broadly covered 
with such liquid such that when the seed leaves the airstream duct 34 it 
is completely covered and ready to be placed in or on the soil. 
Pump 27 is a chemical pump which could be a positive displacement piston 
pump. Liquid is supplied to the pump by a hose 28 which leads from the 
holding tank 36 shown in FIG. 6. Metering screw housing adapter 29 is 
attached to downstream metering housing. Metering screw shaft 14 is 
equipped with a driving sheave 30 which connects to a driven sheave 32 on 
the liquid metering pump 27 by way of a notch belt 31. A pump support 
bracket 33 is attached to metering screw housing adapter 29. 
The chemically treated seed or particulate matter is discharged into and 
through air stream duct 34 which communicates with a high speed blower fan 
and distributes seed or other particulate matter to various manifolds and 
discharge hoses located on a agricultural planting implement. As shown, 
most clearly in FIG. 4, a clean-out cover gasket 35 is located between 
clean-out cover 16 and sump 2. The liquid chemical holding tank 36 is 
secured to an air seeder (not shown) by bracket 37. The holding tank 36 is 
equipped with various valves 38 and a clean out drain 39. Normally, lower 
valve 38 is open and drain 39 is closed and liquid runs through tank hose 
28 to the pump 27. 
With this arrangement the metering auger assembly 6 rotates proportionately 
to ground speed and similarly the pump turns proportionately to the 
metering auger assembly 6, although at a much quicker rate. Thus, 
regardless of ground speed the correct amount of chemically covered 
particulate seed is dispersed evenly to each acre of farm land.