Planting – Drilling – Furrow closer
Reexamination Certificate
2001-12-05
2003-11-11
Novosad, Christopher J. (Department: 3671)
Planting
Drilling
Furrow closer
Reexamination Certificate
active
06644226
ABSTRACT:
TECHNICAL FIELD
This invention relates to improvements to the blades of a seed sowing apparatus, which has also previously been referred to as a ground channelling apparatus.
BACKGROUND ART
Apparatus for sowing seeds into untilled soils (usually covered by plant residues) wherein the seed is deposited into a slit formed in the ground by a disc have been generally described in the following patents.
“Improvements in and relating to seed sowing implements”—New Zealand No. 184742, U.S. Pat. No. 4,275,671, Canada No. 1092899, United Kingdom No. 2001513, France No. 79/01024, and Australia No. 517689,
“Seed sowing apparatus”—New Zealand No.237288, U.S. Pat. No. 5,269,237, Canada No. 2062/60-5, EU (France, United Kingdom, Spain, Germany) No. 92301760.2, Australia No. 662121, Norway No. 92.0820, Japan No. 4-80523, South Africa No. 92/1553.
Amongst the novel features of the designs described in the above patents, are one or more winged side blades which are arranged so that they each contact the lateral faces on either side of a flat circular disc which rotates about a horizontal axis while partly embedded in the soil, and which is drawn in a forward direction with its axle substantially parallel to the soil surface and is sited perpendicular to the disc axle and direction of travel.
Each side blade contacts the disc face almost throughout the entire length of the leading edge of the blade, which is straight in the vertical-longitudinal plane and has an inclined outer surface to deflect material away from the disc. As the combination advances through the soil the blade is held against the disc by a combination of self-adjusting lateral soil forces and a fixed pre-load exerted on the blade(s) by a spring device located near the top of each blade. This intimate contact is essential to the function of the device in not only passing through soil but also in passing without blockage through plant residues lying on the soil surface. Such plant residues are an essential ingredient of the practice of seeding into untilled soils as they protect the soil from erosion and moisture loss. This practice is variously known as “no-tillage”, “no-till”, “zero tillage”, “conservation tillage” or “direct drilling”.
Towards the rear of each blade, the blade is formed so that the inner surface is sufficiently clear of the disc to allow the passage of granular or particulate objects such as seeds, fertiliser and/or dry pesticides to pass in a controlled manner down the gap between the inner surface of the blade and the flat surface of the disc, to come to rest in the soil. The blade is also angled forward at its top so as to ensure that these particulate materials remain within the blade confines while falling into the soil under gravitational force and/or with the assistance of a controlled air steam blowing down the delivery tubes from a fan.
The above design allows almost identical right and left handed blades to be positioned on opposite sides of a disc and two separate bands of material, such as seed and dry fertiliser can be deposited in the soil simultaneously without the two bands coming into contact with one another. This is an important feature since contact between these two materials in the soil often results in the fertiliser having a toxic effect on the seed.
These types of devices in their present form have several problems:
In all forms in which the blade has so far been described in its relationship to the disc, the leading edge is either straight or slightly curved in the vertical-longitudinal plane. In all versions where this leading edge is straight or not specifically shaped, the angle of the leading edge with respect to an arc described by a portion of the disc surface as it passes beneath the leading edge varies along the leading edge from a positive angle where the arc is inclined outwards with respect to the leading edge, to a zero angle where the arc coincides with, or is parallel to the leading edge, to a negative angle where the arc is inclined inwards with respect to the leading edge.
Generally the blade is arranged so that the arc makes a positive angle with respect to the leading edge, at least over a length of the blade (referred to herein as zone
1
) which is designed to operate beneath the ground. This ensures that the soil, roots and plant residues beneath the soil together with plant residues above the soil or close to the soil surface, are deflected by the inclined surface of the leading edge of the blade away from the disc, and also due to the positive angle are deflected harmlessly towards the outer periphery of the disc surface as the disc surface slides beneath the leading edge.
This positive-to-zero angle may continue over a certain length of the blade leading edge that operates above the ground (referred to herein as zone
3
), thereby similarly deflecting material towards the outer periphery of the disc. However, inevitably, due to design requirements, at an upper portion of the leading edge (referred to herein as zone
2
), the angle with respect to the arc becomes negative, and the leading edge no longer functions to deflect material to the outer periphery of the disc. Although this may not be a problem with dry soils where minimal soil, roots or plant residue material adheres to the disc, this can be a problem in wet and/or sticky soils.
The problem in wet or sticky soils is that a thin film of soil and plant material often adheres to the disc surface and is wiped off by the inside surface of the blade in the negative angle zone
2
region. This causes a build-up of unwanted soil to occur between the inner blade surface behind the leading edge, and the disc. As this build-up is cumulative, it eventually forces the blade to lose contact with the disc, which largely destroys the ability of the blade (and thus the whole device) to clear plant residues. Since the ability to clear such residues is an essential ingredient in its intended function, this problem interferes with the function of the device in the field.
In an attempt to overcome this disadvantage, most previous designs of blades have featured a window designed so as to encourage soil and debris which would otherwise accumulate inside the blade in the negative angle zone
2
region, to instead be ejected to the outside of the blade through the window and fall harmlessly away. This window has proven to be only partially successful in practice, since it is limited in size by the physical dimensions of the blade, and often the window itself becomes blocked with soil, thus negating its function altogether.
A further problem arises because each blade is pivotally mounted at its top about a substantially horizontal-longitudinal axis to allow the blade to deflect a limited amount laterally so that it can maintain faithful contact with the disc as the latter flexes naturally in response to the heterogeneity of the soil and the changing direction of travel. While in zones
1
and
3
the blade can be designed to maintain unrestricted contact with the disc, towards the top of zone
2
, where the pivotal mounting of the blade allows less lateral movement, a small clearance is designed between the blade and the disc to avoid the possibility of mechanical jamming between the disc and the blade.
Occasional pieces of straw or other materials find their way into this small gap from which they are forced progressively downwards, separating the blade from the disc, firstly in zone
2
, then in zone
3
, and eventually in zone
1
. When this occurs the scraping function in the positive angle zone
3
and zone
1
regions is compromised, allowing straw and/or other material and residue on the blade to ingress so that eventually the residue-clearance ability of the device fails, and an undesirable field blockage occurs which seriously disrupts the seeding function unless cleared. At best, clearance of the blockage represents a field stoppage, costing downtime and the loss of operating efficiency.
In other attempts to overcome the disadvantages discussed above, there have been attempts to design a substantially straight side
Baker Christopher John
Kernohan Craig David
Ritchie William Rowlan
Robinson David John
Abelman ,Frayne & Schwab
Novosad Christopher J.
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