AU2003231613A1 - Rotary Shield - Google Patents

Description

ROTARY SHIELD FIELD OF THE INVENTION The present invention relates to a disc opener for an agricultural implement and in particular a disc opener for use in zero or minimal till seeding and fertilizing operations.

BACKGROUND ART Traditionally, after a crop has been harvested, the field is tilled so as to bury the harvest residue into the soil and ready the soil for planting.

However, there are a number of economic and environmental disadvantages with such methods. First, tilling the soil with implements such as ploughs, is energy intensive and time consuming. Ploughing operations require large horsepower tractors and thus fuel costs are significant, together with requiring a considerable investment of a farmer's time. Further, tilling incorporates weed seeds into the soil that encourages weed growth.

Crop residue and trash that remains on the soil surface after harvest can protect the soil surface from water run off and erosion and loss of moisture from the soil by evaporation. It may also inhibit weed growth.

Removal of the surface layer by tilling the soil can therefore result in soil erosion, moisture loss and encourage weed growth, which can translate to an increase in herbicide use.

In order to overcome these difficulties, operations referred to as zero or minimal tilling have been practiced. Zero tillage refers to the practice of directly planting seed into a field without pre seeding tilling. Zero or minimum tillage practices employ implements known as soil openers. One type of opener is referred to as a disc opener. These openers have a vertical disc inclined to the direction of travel cuts a narrow furrow in the soil. After placement of the seed in the furrow, by a seed tube or the like, the furrow is closed and the soil compacted by a packing wheel.

In practice, there are a number of difficulties with conventional zero tillage implements. A major problem is known as "hairpinning" which occurs when straw, trash and/or crop residue becomes embedded in the furrow when the disc of the disc opener does not completely cut through the trash and forces the debris into the furrow. Seed is dispensed into the furrow and onto the residue. As the trailing half of the disc retracts from the furrow, the disc can drag some of the residue from the furrow, taking seed with it. Seed that remains in the furrow will not germinate in an optimum manner if it is in contact with residue rather than soil. Further, erratic seed placement caused by hairpinning will result in poor and non-uniform germination. This can significantly affect the final crop. Hairpinning can also cause moisture loss due to the wicking action of exposed portions of straw, trash and/or crop residue.

Various methods have been developed in an attempt to address the hairpinning problems. One commercially available zero till implement incorporates a disc opener known as the Barton opener. The Barton opener has an upright rotating disc that is inclined in both the vertical and horizontal directions. The disc has a diameter of 18 inches (45cm). A disc inclined in both the vertical and horizontal directions is claimed to slice through the soil at an angle rather than compressing the soil as with conventional vertical discs. It is believed that the slicing action is also more efficient in cutting through the trash and reduces hairpinning.

The Barton opener also has a cleaning wheel mounted parallel to the opening disc. The cleaning wheel controls soil thrown during furrow formation and cleans the opening disc. The axle of the cleaning wheel is connected to a crank assembly. The cleaning wheel is set to run above ground level. This is important to the operation of the Barton opener. If the cleaning wheel ran along the ground it would compact the soil making furrow closure more difficult. The Barton opener also has a rear-packing wheel set at the opposite inclination to the opening disc. The packing wheel closes and compacts the soil and also controls furrow depth.

In practice it has been observed that there are a number of difficulties associated with use of the Barton opener. First, when used in heavy or wet soils, the opening disc picks up soil and can become blocked.

This results in stalling of the opening disc that then drags along the ground.

As mentioned above, the rear-packing wheel controls furrow depth. The packing wheel is spaced from the seed delivery tube that is located in the region of the opening disc. This is acceptable if the ground is even. In practice this is rarely the case. On uneven the ground, the packing wheel can be lifted by a bump which then lifts the opening disc which results in uneven furrow depth.

A further disadvantage with such an arrangement is that the pressure of the packing wheel cannot be varied independently of the furrow depth. Independent adjustment may be desirable to optimize soil compaction, particularly in the case of soft friable soils that result from successful zero till farming. Providing a gauge wheel located adjacent the opening disc may at least partially address the problems associated with the packing wheel controlling the depth. However, as stated above, such an arrangement is unacceptable with the Barton opener.

Another approach to addressing the hairpinning problem that has been proposed is to provide a disc opener having press wheels on either side of a conventional 18 inch (45cm) vertical opening disc. The press wheels hold the trash on either side of the opening disc such that the disc can more easily slice through the residue. The press wheels contribute to the complexity and cost of this type of opener. Further, the press wheels may cause undesirable compaction of the soil. Still further, the presence of the press wheels increases the width of the opener and there is a corresponding increase in the minimum width allowable between plant rows.

In this device, the front press wheels control seeding depth.

Because these wheels are spaced from the seed tubes the same types of difficulties in relation to nonuniform furrow depth as discussed above with respect to the Barton opener can be experienced.

In our earlier application, Australian Patent Application 71798/00, we disclosed a disc opener having a rotatable opening disc providing relatively accurate depth control in seeding and fertilizing operations in a manner that minimized soil disturbance and optimized soil compaction.

Further, the disc opener showed improvements in the likelihood of stalling and clogging. Hairpinning was reduced.

Many disc openers employ a shield disposed in the shadow of the opening disc. Such shields provide better control of the positioning of seeds and/or fertilizer with the furrow created by the opening disc. However, in spite of the use of shields certain disadvantages remain. For example, hairpinning is still a potential problem with the use of opening discs.

SUMMARY OF THE INVENTION We have now found an opening disc assembly that reduces hairpinning and may also ameliorate one or more of the disadvantages described above or at least provide the consumer with a useful or commercial choice. Accordingly, in a first aspect there is provided an opening disc assembly comprising a disc support for attachment to a frame of a disc opener, an opening disc rotatably mounted on said disc support and a rotary shield rotatably mounted on said disc support.

In a second aspect there is provided a disc opener having a frame, said frame having a plurality of opening disc assemblies mounted thereon wherein each opening disc assembly comprises a disc support for attachment to the frame, an opening disc rotatably mounted on said disc support and a rotary shield rotatably mounted on said disc support.

DETAILED DESCRIPTION The opening disc assembly of the first aspect of the present invention in use may be mounted on the frame of a disc opener of the second aspect of the present invention. The disc opener may be removably affixed to a tractor or other powered drive. In use the disc opener forms a furrow in the soil and the rotary shield is disposed in the shadow of the disc opener. The rotary shield rotates during the forward movement of the disc opener assembly and assists in reducing hairpinning.

The opening disc assembly comprises a disc support for attachment to a frame of a disc opener. The frame may be of any convenient configuration whereby the opening disc assemblies are spaced apart to provide desired furrow spacings.

An opening disc is rotatably mounted on said disc support. The opening disc may be aligned vertically or may be set at an angle to the vertical. The vertical angle of inclination may be varied to suit the conditions.

Typically the vertical angle varies between 0 and about 100. When set at 00 a substantially vertical furrow is formed. When set at an angle, and furrow inclined to the vertical is formed.

The opening disc for use in the opening disc assembly of the present invention typically has a diameter of between 20 to about 30 inches (about 50 to about 70cm). This diameter is larger than the diameter of conventional opening discs which generally have a maximum diameter of about 18 inches (45cm). By providing an opening disc having a larger diameter than conventional opening discs we have found that cutting through the residue is facilitated, even when the disc is at an angle of 00 to the vertical and hairpinning is reduced.

Whilst the opening disc may be driven, we have found that by mounting the opening disc rotatably on the support the forward movement of the assembly causes the disc to rotate due to the frictional contact with the soil. It is preferred that the opening disc is rotated by the frictional contact with the soil.

A rotary shield is rotatably mounted on the disc support. The rotary shield is disposed adjacent the trailing surface of the opening disc and forms a v-shaped gap between the opening disc and the rotary shield. The point of the v-shaped gap points toward the direction of forward movement of the opening disc. In use, the shield may be considered to be within the shadow created by the forward movement of the opening disc and can reduce the entry of dry soil into the narrow furrow created by the opening disc.

The rotary shield is preferably in the form of a disc mounted on the frame for rotation. Preferably the rotary shield is of lesser diameter than the opening disc. In particular it is preferred that the rotary shield has a diameter about half that of the opening disc and is positioned towards the trailing edge of the opening disc. The rotary shield typically has a diameter of between to about 12 inches (about 25 to about The rotary shield is preferably inclined relative to the direction of forward travel of the disc opener opposite the angle of inclination of the opening disc. The angle of inclination of the rotary shield may be varied to suit different situations such as varying soil type and hardness, moisture content or amount of organic material on the soil surface. Typically the angle of inclination to the direction of forward motion is between about 4 to about o The rotary shield may be aligned vertically or may be set at an angle to the vertical. The vertical angle of inclination may be varied to suit the conditions. Typically the vertical angle varies between 0 and about 100.

The rotary shield may be driven for rotation by any convenient means. We have found that by mounting the rotary shield in contact at its periphery with the opening disc the opening disc can drive the rotary shield.

Preferably the rotary shield is substantially lesser in diameter than the opening disc such that the rotation of the rotary shield peripherally in contact with the opening disc is at a greater number of revolutions per minute than the opening disc. Preferably the rotary shield is mounted such that the gap between the opening disc and the rotary shield is minimized whilst the longest possible section of the circumference of the rotary shield is in contact with the opening disc. It is preferred that the region of contact is substantially parallel to the periphery of the opening disc and as far as possible from the centre of the opening disc having regard to maintaining the small gap between the rotary shield and the opening disc.

We have found that the operating speed of the opening disc assembly is not a critical factor in the effectiveness of the shield. Further the opening disc assembly has the ability to operate in wet conditions with heavy residue without blockages, the rotary shield and opening disc being at least in part cleaning in all conditions.

In a preferred embodiment, the opening disc assembly includes a scraper blade running on the upper side of the disc. This blade assists in removing any soil adhering to the disc and provides for continuous cleaning of the disc in use. Scrapers may be disposed adjacent the opening disc above the ground and on either or both sides of the opening disc.

The opening disc assembly may also include means for dispensing seed and/or fertilizer into the furrow. Devices for dispensing seed and/or fertilizer are well known the art and need not be further described. However, a seed delivery system of the air seeder type is particularly preferred.

Typically, a seed delivery tube is fitted to the underside of the opening disc.

In the disc opener of the present invention an opening disc assembly as described above may be employed. In a preferred embodiment the opener enables improved placement of seed and/or fertilizer within the furrow formed by the opening disc in no till or minimum till seeding and/or fertilizing operations. Accordingly there is provided a disc opener having a frame adapted to move in a forward direction of travel, an opening disc assembly for forming a furrow in soil when moved in the forward direction, the opening disc assembly comprises a disc support for attachment to the frame, an opening disc rotatably mounted on said disc support and a rotary shield rotatably mounted on said disc support, the opening disc assembly being mounted to the frame and the opening disc being inclined to the forward direction of travel to provide a leading and a trailing surface, the rotary shield disposed adjacent the trailing surface of the opening disc, means for dispensing seed and/or fertilizer into the furrow, a soil retaining wheel mounted to the frame and set to run along an undisturbed soil surface behind the trailing edge of the leading surface of the opening disc in substantially the same direction as the direction of travel, such that in use the soil retaining wheel replaces soil from the furrow formed by the opening disc and also controls the depth of the furrow.

Typically, the disc opener of the second aspect of the present invention further includes a rear packing wheel for compacting the furrow after it has been filled in by the action of the soil retaining wheel. The packing wheel may be oriented at any angle. Preferably, the packing wheel is set at the same angle to the direction of travel as the opening disc. Where the opening disc is also inclined at an angle to the horizontal, it is preferred that the packing wheel is inclined at substantially the same angle to the vertical.

In this way, the packing wheel compacts the soil in the furrow from the same angle as that which the furrow was made.

By orientating the packing wheel in this manner, a more positive seed to soil contact may be obtained than when the packing wheel is oriented in the opposite direction to the opening disc as taught by the prior art. The more positive seed to soil contact facilitates germination and improves plant vigor.

The disc opener of the second aspect of the present invention may have an opening disc inclined relative to the direction of forward travel of the disc opener. Whilst the angle of inclination will generally be fixed, the angle may in more complex configurations be varied to suit different situations such as varying soil type and hardness, moisture content or amount of organic material on the soil surface. Typically the angle of inclination to the horizontal is between about 4 to about The disc opener may include a soil retaining wheel mounted substantially parallel to the direction of travel. The wheel may be mounted such that it runs along the ground on the same side of the device as of the leading surface of the opening disc and behind the trailing edge of the opening disc. It will be appreciated that there may be minor variations to the orientation of the wheel, such as the angle, and these may be advantageous where the wheel travels on the undisturbed ground and continues to replace displaced soil into the furrow behind the opening disc.

When a furrow is formed by the opening disc, soil is displaced and a raised area of soil is formed along the side of furrow which is adjacent to the leading surface of the opening disc. A soil retaining wheel, following behind the trailing edge of the opening disc, throws the displaced soil back into the furrow. By setting the wheel to run in substantially the same direction as the direction of travel that the action of the wheel in returning soil to the furrow is more efficient than the prior art inclined soil retaining wheels.

The soil retaining wheel may be set to run along the undisturbed soil and to control the depth at which the opening disc travels through the soil and consequently the furrow depth. The wheel is typically set to run along the ground adjacent or near where the seed and/or fertilizer is dispensed into the furrow. In this way, the depth is controlled at where the seed is dispensed as opposed to the depth being regulated by a rear packing wheel spaced from the site of seed delivery as in prior art devices. It has been found that by having the depth control means located to the side of the opening disc, more accurate seed depth can be obtained. Accurate seed depth is important for optimizing germination.

The soil retaining wheel typically has a diameter of the same or similar order of magnitude to the opening disc. The soil retaining wheel, or the gauge wheel, is preferably deployed in the line of travel and is not used as a cleaning wheel. It is preferred that rotary scapers are used for minimizing soil buildup on the opening disc. This may be especially important in wet and/or heavy soils.

Advantageously, we have found that the use of a rotary shield substantially reduces the affect of "hairpinning" by removing residue from seeding slot. We have also found that other advantageous effects are provided by the use of an opening disc assembly in accordance with the present invention. These advantages include a reduced braking affect on the opening disc when under load, greater protection in the seeding zone from contamination with debris as is common on single disc openers, a reduced attrition rate and consequent increase in product life.

Advantageously the opening disc assembly and the disc opener may be configured for ready adjustment.

BRIEF DESCRIPTION OF THE DRAWINGS By way of example only, the present invention will now be described with reference to the accompanying figures in which; Figure 1 is a bottom view of a opening disc assembly attached to a disc opener in accordance with the present invention; Figure 2 is a front end view of the disc opener of Figure 1 and Figure 3 is a side view of the disc opener of Figure 1.

Figure 4 is a perspective view of the disc opener of Figure 1.

Figure 5 is a perspective view in greater detail of the section labeled B of the disc opener of Figure 1.

Figure 6 is a digital photograph of a preferred embodiment of the opening disc assembly and the disc opener of the present invention.

BEST MODE Figures 1, 2, 3, 4 and 5 illustrate a preferred disc opener 11 of the present invention. The disc opener 11 has a frame 12 with a connecting arm 13 for connecting the disc opener 11 to a tool bar (not illustrated) which in turn is hitched to a tractor. A plurality of disc openers 11, may be mounted on the tool bar.

The disc opener 11 has an opening disc 14 rotatably mounted to frame 12 on an axle 17 and attached at hub 18. The opening disc 14 is set at an angle of between about 4 to about 100 to the direction of travel A so as to define leading surface 15 and a trailing surface 16. The opening disc has a diameter of about 22 inches A rotary shield 20 is disposed against the trailing surface 16 of the opening disc 14. The rotary shield 20 is mounted on axle 19 connected to arm 21 that is in turn attached to frame 12. The rotary shield 20 engages the opening disc 14 at chord C for rotational drive.

In use, the disc opener travels in a forward direction and opening disc 11 forms a vertical furrow in the ground and a raised area of displaced soil is formed along the side of the furrow adjacent the leading surface 15 of the opening disc 14. Seed and/or fertilizer may be deposited into the furrow by feed tube Other attachments such as a soil retaining wheel and the like may be attached to the frame at mount Figure 6 illustrates a preferred disc opener 31 of the present invention. The disc opener 31 has a frame 32 with a connecting arm (not illustrated) for connecting the disc opener 31 to a tool bar (not illustrated) which in turn is hitched to a tractor. A plurality of disc openers 31, may be mounted to a tool bar.

The disc opener 31 has an opening disc 34 rotatably mounted to frame 32. The opening disc 34 is set at an angle of between about 4 to about 100 to the direction of travel A so as to define leading surface (not illustrated) and a trailing surface 36. The opening disc has a diameter of about 22 inches A rotary shield 40 is disposed against the trailing surface 36 of the opening disc 34. The rotary shield 40 is mounted on axle 39 connected to arm 41 that is in turn attached to frame 32. The rotary shield 40 engages the opening disc 34 at chord C for rotational drive. The scoring 45 on the trailing surface 36 of the opening disc 34 shows the region of contact between the opening disc 34 and the rotary shield The opening disc 34 also has a scraping disc 60 for removing unwanted build up of soil on the opening disc 34. The scraping disc 60 is rotatably mounted on the frame 32.

I

The disc opener 31 includes a soil retaining wheel 37 which is set to run in the direction of travel and behind the opening disc 34. The soil retaining wheel 37 is mounted to the same side of the opening disc 34 as the leading surface (not illustrated) of the opening disc 34. The soil retaining wheel 37 has a similar diameter to the opening disc 34 and a width of about 100mm. A seed delivery tube 55 is fitted to adjacent the trailing surface 36 of the opening disc 34 and feeds seed and/or fertilizer into a furrow formed by the forward movement of opening disc 34.

In use, the soil retaining wheel 37 is in constant contact with the undisturbed soil to the side of the furrow and therefore acts to control the depth at which the opening disc operates. It can be seen that the depth is controlled at the same location as where the seed is dispensed. This can provide for an improved accuracy of planting when compared to prior art devices which rely on forward or rear wheels for gauging depth.

The soil retaining wheel 37 also functions to prevent soil being thrown away from the furrow and to replace displaced soil into the furrow.

When a furrow is formed, a raised portion of displaced soil is formed along the edge of the furrow on the same side of the furrow as the leading surface of the opening disc 34.

Claims (21)

1. An opening disc assembly comprising a disc support for attachment to a frame of a disc opener, an opening disc rotatably mounted on said disc support and a rotary shield rotatably mounted on said disc support.

2. An opening disc assembly according to claim 1 wherein the opening disc is aligned vertically.

3. An opening disc assembly according to claim 1 wherein the opening disc is set at an angle of up to 100 from vertical.

4. An opening disc assembly according to any one of claims 1 to 3 wherein the opening disc has a diameter in the range of from 500 to 700mm.

An opening disc assembly according to any one of claims 1 to 4 wherein the opening disc is rotatably mounted on the support.

6. An opening disc assembly according to any one of claims 1 to wherein the rotary shield is disposed adjacent the trailing surface of .the opening disc and forms a v-shaped gap between the opening disc and the rotary shield and the point of the v-shaped gap points toward the direction of forward movement of the opening disc.

7. An opening disc assembly according to any one of claims 1 to 6 wherein the rotary shield is in the form of a disc mounted on the frame for 2 0 rotation.

8. An opening disc assembly according to claim 7 wherein the rotary shield has a diameter in the range of from 250mm to 300mm.

9. An opening disc assembly according to any one of claims 1 to 8 wherein the rotary shield is inclined relative to the direction of forward travel of the disc opener at an angle of inclination opposite to that of the opening disc.

An opening disc assembly according to claim 9 wherein the angle of inclination of the rotary shield to the direction of forward motion is between about 40 and

11. An opening disc assembly according to any one of claims 7 to wherein the rotary shield is driven for rotation by mounting the rotary shield in contact at its periphery with the opening disc the opening disc can drive the rotary shield.

12. An opening disc assembly according to any one of claims 1 to 11 wherein the opening disc assembly includes a scraper blade running on the upper side of the disc.

13. An opening disc assembly according to any one of claims 1 to 12 wherein the opening disc assembly also includes means for dispensing seed and/or fertilizer into the furrow.

14. A disc opener having a frame, said frame having a plurality of opening disc assemblies mounted thereon wherein each opening disc assembly comprises a disc support for attachment to the frame, an opening disc rotatably mounted on said disc support and a rotary shield rotatably mounted on said disc support.

A disc opener having a frame adapted to move in a forward direction of travel, an opening disc assembly for forming a furrow in soil when moved in the forward direction, the opening disc assembly comprises a disc support for attachment to the frame, an opening disc rotatably mounted on said disc support and a rotary shield rotatably mounted on said disc support, the opening disc assembly being mounted to the frame and the opening disc being inclined to the forward direction of travel to provide a leading and a trailing surface, the rotary shield disposed adjacent the trailing surface of the opening disc, means for dispensing seed and/or fertilizer into the furrow, a soil retaining wheel mounted to the frame and set to run along an undisturbed soil surface behind the trailing edge of the leading surface of the opening disc in substantially the same direction as the direction of travel, such that in use the soil retaining wheel replaces soil from the furrow formed by the opening disc and also controls the depth of the furrow.

16. A disc opener according to either claim 14 or claim 15 wherein the disc opener includes a rear packing wheel for compacting the furrow after it has been filled in by the action of the soil retaining wheel.

17. A disc opener according to claim 16 wherein the packing wheel is set at substantially the same angle to the direction of travel as the opening disc.

18. A disc opener according to any one of claims 14 to 17 wherein the disc opener includes a soil retaining wheel mounted substantially parallel to the direction of travel. 14

19. A disc opener according to claim 18 wherein the soil retaining wheel is mounted such that it runs along the ground on the same side of the device as of the leading surface of the opening disc and behind the trailing edge of the opening disc.

20. A disc opener assembly substantially as hereinabove described with reference to the drawings.

21. A disc opener substantially as hereinabove described with reference to the claims.