CA2784578A1 - Pressure controller for forces applied to tools - Google Patents
Pressure controller for forces applied to tools Download PDFInfo
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- CA2784578A1 CA2784578A1 CA2784578A CA2784578A CA2784578A1 CA 2784578 A1 CA2784578 A1 CA 2784578A1 CA 2784578 A CA2784578 A CA 2784578A CA 2784578 A CA2784578 A CA 2784578A CA 2784578 A1 CA2784578 A1 CA 2784578A1
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Abstract
This application discloses a system for controlling the force applied to a tool for cutting a seed trench in soil. The system comprises a cutting tool, a gauge for determining a first position indicative of the surface of the soil and a drive assembly for applying a force to the cutting tool to position the cutting tool at a second position relative to the first position. The drive assembly determines the applied force based on the spacing between the first position and the position of the tool. In terms of disc seeders, the system operates to maintain cutting discs at a desired soil penetration range by accounting for localised variations in soil hardness.
Description
PRESSURE CONTROLLER FOR FORCES APPLIED TO TOOLS
Field of the invention This invention relates to a system for controlling force applied to a tool.
The invention has particular, although not exclusive, application to agricultural machinery, such as seeders, where control over the depth of ground penetration of tilling tools is important because the penetration depth affects the depth that seeds are planted.
Background Disc seeders are used to plant seeds for a crop. The disc seeders operate by cutting a shallow trench, placing seed in the trench and back-filling the trench to cover the seed with soil. It is important to control the depth of the trench so that the seeds are exposed to conditions that are conducive to germination and growth.
Specifically, if the trench is too deep, the germinating seeds will not be able to reach the surface of the soil. This means that the germinating seeds will not receive sunlight and, therefore, will not grow. Alternatively, if the trench is too shallow, there may not be enough soil surrounding the seed to allow it to germinate and take root. Additionally, the soil may not contain enough moisture to enable the seed to germinate or to sustain the germinated seed.
Controlling the trench depth, and therefore the seed depth, is critical to achieving high germination rates that are required for efficient farming practices. In most cases, however, farmers rely on their working experience of soil to adjust their machinery to a configuration that, in use, applies a set trench-cutting force that they believe will produce a desired trench depth. This is partly because seeder machinery is not adjusted to differing soil conditions in real-time. The adjustments are typically carried out by bringing machinery to a stop, manually carrying out the adjustments and then restarting the machinery. For this reason, machinery adjustments typically are not carried out during operation.
Therefore, the general practice is to adjust the machinery and then work entire fields on the basis that the set configuration will result in some seeds being planted outside the desired depth range. In other words, the farmer simply accepts a lower rate of germination and growth than if the machinery was adjusted because of the time and effort required to properly adjust the machinery.
Accordingly, it is an object of the invention to provide a system for controlling the working force on tools. In its applications to seeders, this object involves controlling the force applied to trench cutting tools so that tool penetration is adjustable during operation. The underlying objective being to control tool penetration depth so that plant seeds are planted at a depth that improves the chances of germination and growth.
Summary of the disclosure In a first aspect, there is provided a system for controlling the force applied to a tool for cutting a seed trench in soil, the system comprising:
(a) a cutting tool;
(b) a gauge for determining a first position indicative of the surface of the soil;
(c) a drive assembly for applying a force to the cutting tool to position the cutting tool at a second position relative to the first position, and wherein the drive assembly determines the applied force based on the spacing between the first position and the position of the tool.
Field of the invention This invention relates to a system for controlling force applied to a tool.
The invention has particular, although not exclusive, application to agricultural machinery, such as seeders, where control over the depth of ground penetration of tilling tools is important because the penetration depth affects the depth that seeds are planted.
Background Disc seeders are used to plant seeds for a crop. The disc seeders operate by cutting a shallow trench, placing seed in the trench and back-filling the trench to cover the seed with soil. It is important to control the depth of the trench so that the seeds are exposed to conditions that are conducive to germination and growth.
Specifically, if the trench is too deep, the germinating seeds will not be able to reach the surface of the soil. This means that the germinating seeds will not receive sunlight and, therefore, will not grow. Alternatively, if the trench is too shallow, there may not be enough soil surrounding the seed to allow it to germinate and take root. Additionally, the soil may not contain enough moisture to enable the seed to germinate or to sustain the germinated seed.
Controlling the trench depth, and therefore the seed depth, is critical to achieving high germination rates that are required for efficient farming practices. In most cases, however, farmers rely on their working experience of soil to adjust their machinery to a configuration that, in use, applies a set trench-cutting force that they believe will produce a desired trench depth. This is partly because seeder machinery is not adjusted to differing soil conditions in real-time. The adjustments are typically carried out by bringing machinery to a stop, manually carrying out the adjustments and then restarting the machinery. For this reason, machinery adjustments typically are not carried out during operation.
Therefore, the general practice is to adjust the machinery and then work entire fields on the basis that the set configuration will result in some seeds being planted outside the desired depth range. In other words, the farmer simply accepts a lower rate of germination and growth than if the machinery was adjusted because of the time and effort required to properly adjust the machinery.
Accordingly, it is an object of the invention to provide a system for controlling the working force on tools. In its applications to seeders, this object involves controlling the force applied to trench cutting tools so that tool penetration is adjustable during operation. The underlying objective being to control tool penetration depth so that plant seeds are planted at a depth that improves the chances of germination and growth.
Summary of the disclosure In a first aspect, there is provided a system for controlling the force applied to a tool for cutting a seed trench in soil, the system comprising:
(a) a cutting tool;
(b) a gauge for determining a first position indicative of the surface of the soil;
(c) a drive assembly for applying a force to the cutting tool to position the cutting tool at a second position relative to the first position, and wherein the drive assembly determines the applied force based on the spacing between the first position and the position of the tool.
It will be appreciated that this system operates in the reverse manner to typical seeder machinery in that the desired tool depth is selected, i.e. a set difference between the tool position and the first position, and then the system selects the appropriate force to apply to the tool to achieve the desired tool depth.
Furthermore, the system automatically accounts for changes in soil hardness so that tool depth is generally constant. In soft soils, a given force will drive the tool deeper into the soil. Conversely, in hard soils, a given force will result in shallow penetration of the tool. However, the system accounts for this by recognising that the difference between the tool position and the first position changes and by adjusting the force applied to the tool. This means that the system can control the depth of penetration of a disc seeder in real-time and in response to local variations in soil conditions.
In the form of a disc seeder, the tool may comprise a disc for cutting a seed furrow in soil and the gauge member may comprise a gauge wheel for travelling on the surface of the soil.
The drive assembly may comprise one or more sensors that provide an indication of the vertical position of the gauge wheel relative to the cutting disc and comprises a drive member that applies a force to the disc in response to a signal from the or each sensor.
The drive member may be a hydraulic or pneumatic ram.
The disc may be part of disc assembly that comprises a chassis on which the disc is mounted and comprises a cantilevered arm extending from the chassis and on which the gauge wheel is mounted.
The one or more sensors may be mounted on the chassis in positions that track movement of the cantilevered arm such that upward movement of the arm causes the one or more sensors to reduce the force applied to the disc and such that downward movement of the arm causes the one or more sensors to increase the force applied to the disc.
The one or more sensors may be mounted on the chassis in positions that track movement of the cantilevered arm such that downward movement of the arm causes the one or more sensors to reduce the force applied to the disc and such that upward movement downward movement of the arm causes the one or more sensors to increase the force applied to the disc.
Upward movement of the arm relative to the disc indicates that the soil is relatively soft because the applied pressure causes the disc to penetrate further into the soil. This greater penetration increases the distance between the soil surface on which the gauge wheel travels and the lowermost position of the disc which represents the depth of the trench. The reverse applies when the arm moves downward relative to the disc, i.e. the depth of disc penetration decreases.
The system may comprise a plurality of cutting tools and the drive assembly may include a plurality of drive members that are operable to apply a force to a respective cutting tool to position the respective cutting tools at a second position relative to the first position.
The system may further comprise a biasing means that counteracts the weight force of at least the cutting disc and a chassis to which the cutting disc is connected so that the drive assembly is primarily responsible for applying a force to the cutting tool to position the cutting tool at the second position.
In a second aspect, there is provided a disc assembly for sowing seeds in soil, the disc assembly comprising:
(a) a chassis having link that enables the chassis to be connected to a vehicle to trail the vehicle;
Furthermore, the system automatically accounts for changes in soil hardness so that tool depth is generally constant. In soft soils, a given force will drive the tool deeper into the soil. Conversely, in hard soils, a given force will result in shallow penetration of the tool. However, the system accounts for this by recognising that the difference between the tool position and the first position changes and by adjusting the force applied to the tool. This means that the system can control the depth of penetration of a disc seeder in real-time and in response to local variations in soil conditions.
In the form of a disc seeder, the tool may comprise a disc for cutting a seed furrow in soil and the gauge member may comprise a gauge wheel for travelling on the surface of the soil.
The drive assembly may comprise one or more sensors that provide an indication of the vertical position of the gauge wheel relative to the cutting disc and comprises a drive member that applies a force to the disc in response to a signal from the or each sensor.
The drive member may be a hydraulic or pneumatic ram.
The disc may be part of disc assembly that comprises a chassis on which the disc is mounted and comprises a cantilevered arm extending from the chassis and on which the gauge wheel is mounted.
The one or more sensors may be mounted on the chassis in positions that track movement of the cantilevered arm such that upward movement of the arm causes the one or more sensors to reduce the force applied to the disc and such that downward movement of the arm causes the one or more sensors to increase the force applied to the disc.
The one or more sensors may be mounted on the chassis in positions that track movement of the cantilevered arm such that downward movement of the arm causes the one or more sensors to reduce the force applied to the disc and such that upward movement downward movement of the arm causes the one or more sensors to increase the force applied to the disc.
Upward movement of the arm relative to the disc indicates that the soil is relatively soft because the applied pressure causes the disc to penetrate further into the soil. This greater penetration increases the distance between the soil surface on which the gauge wheel travels and the lowermost position of the disc which represents the depth of the trench. The reverse applies when the arm moves downward relative to the disc, i.e. the depth of disc penetration decreases.
The system may comprise a plurality of cutting tools and the drive assembly may include a plurality of drive members that are operable to apply a force to a respective cutting tool to position the respective cutting tools at a second position relative to the first position.
The system may further comprise a biasing means that counteracts the weight force of at least the cutting disc and a chassis to which the cutting disc is connected so that the drive assembly is primarily responsible for applying a force to the cutting tool to position the cutting tool at the second position.
In a second aspect, there is provided a disc assembly for sowing seeds in soil, the disc assembly comprising:
(a) a chassis having link that enables the chassis to be connected to a vehicle to trail the vehicle;
(b) a cutting disc mounted to the chassis and being configured to cut a furrow in soil to enable seed to be delivered into the furrow;
(c) a gauge wheel connected to a member that is, in turn, pivotably connected to the chassis such that the gauge wheel overlaps a trailing edge of the cutting disc and travels on the soil surface and wherein the pivotable connection allows the gauge wheel to move vertically with variations in the soil surface level relative to the cutting disc; and (d) the system defined in any one of claims 2 to 9 wherein the system controls the depth of soil penetration by the cutting disc based on the vertical spacing between the cutting disc and the gauge wheel.
The disc assembly may further comprise a press wheel for compacting loose soil covering seed in the furrow to improve seed-soil contact.
The disc assembly may further comprise a biasing element connected to both the chassis and an arm on which the press wheel is mounted to apply a force for compacting soil in the furrow. The biasing element may include impact absorbing means to reduce bouncing of the press wheel.
In a third aspect, there is provided a disc seeder for sowing seeds in soil, the disc seeder comprising a plurality of disc assemblies according to the second aspect.
Brief description of the drawings The invention will now be described, by way of example only, with reference to the accompanying drawings, in which:
Figure 1 is a side view of a disc assembly for use with a system according to the first aspect and including sensors that monitor the height of a gauge wheel relative to a disc.
(c) a gauge wheel connected to a member that is, in turn, pivotably connected to the chassis such that the gauge wheel overlaps a trailing edge of the cutting disc and travels on the soil surface and wherein the pivotable connection allows the gauge wheel to move vertically with variations in the soil surface level relative to the cutting disc; and (d) the system defined in any one of claims 2 to 9 wherein the system controls the depth of soil penetration by the cutting disc based on the vertical spacing between the cutting disc and the gauge wheel.
The disc assembly may further comprise a press wheel for compacting loose soil covering seed in the furrow to improve seed-soil contact.
The disc assembly may further comprise a biasing element connected to both the chassis and an arm on which the press wheel is mounted to apply a force for compacting soil in the furrow. The biasing element may include impact absorbing means to reduce bouncing of the press wheel.
In a third aspect, there is provided a disc seeder for sowing seeds in soil, the disc seeder comprising a plurality of disc assemblies according to the second aspect.
Brief description of the drawings The invention will now be described, by way of example only, with reference to the accompanying drawings, in which:
Figure 1 is a side view of a disc assembly for use with a system according to the first aspect and including sensors that monitor the height of a gauge wheel relative to a disc.
Figure 2 is a rear view of the disc assembly in Figure 1 and mounted to a bar alongside other disc assemblies of the same construction.
Figure 3 is side view of the disc assembly in Figure 1 and showing the configuration of the sensors.
Figure 4 is a schematic representation of a hydraulic system for adjusting the height of the disc in Figure 1 relative to the height of the gauge wheel.
Detailed description A system for controlling the force applied to a tool will be described in the context of seeder machinery in the form of a disc opener. However, it will be appreciated that the system can be applied to other forms of machinery where it is important to control the pressure applied to a tool.
A disc assembly 1 for planting crop seeds is shown in Figure 1. In operation, a series of disc assemblies 1 are mounted to a main bar 42 (Figure 2) pulled by a tractor. Each disc assembly 1 is mounted to the main bar 42 by a clamp 60.
Upper and lower linkages 62, 64 are hingeably connected to the clamp 60 and extend rearwardly of the main bar 42 with respect to the direction of travel. The rear ends of the upper and lower linkages 62, 64 are connected to a frame 66 that extends downwardly and rearwardly. A disc 74 is rotatably mounted to the frame 66 and a gauge wheel 76 is also pivotably mounted to the frame 66.
A press wheel 78 is rotatably mounted to a cantilevered arm 68 that is hingeably connected to the frame 66 to extend rearwardly thereof. A biasing means, such as a hydraulic ram or a compression spring (82 in Figure 2), extends between the arm 68 and the frame 66 to provide a downward biasing force on the press wheel 78.
The compression spring 79 may alternatively be a hydraulic ram. However, in the form of a compression spring, the compression spring 79 includes a pneumatic or hydraulic shock absorber to reduce bouncing of the press wheel 78, so that loose soil covering seed in the furrow is compacted to improve seed-soil contact.
The extent of down force provided by the compression spring 79 is selected to facilitate germination of the seed.
The disc 74 is inclined slightly to the direction of travel such that, as the disc assembly 1 moves forward, the disc 74 creates a narrow furrow. A seed tube 80 is arranged behind the disc 74 having regard to the direction of travel such that seed can be delivered via the seed tube 80 to the furrow formed by the disc 74. The seed tube 80 terminates in a seed boot (not shown) through which seed is funnelled into the furrow.
In operation, the disc 74 forms a furrow by displacing soil laterally of the disc 74.
For the most part, the soil piles-up on the side of the furrow corresponding to a leading surface side of the disc. Other soil is projected into the air laterally and rearwardly of the disc 74. Seed is deposited into the furrow from a seed boot 130.
The gauge wheel 77 runs over the piled-up soil and pushes some of it back into the furrow. Additionally, the gauge wheel 74 deflects some projected soil back into the furrow. As a result, seed disposed in the furrow is covered by loose soil.
A hydraulic ram 70 connects an inner end of the upper linkage 62 to an outer end of the lower linkage 64 so that actuation of the hydraulic ram 70 causes lifting or lowering of the disc 74. Accordingly, the hydraulic ram 70 can be operated to lift the disc assemblies 1 to a position where the disc 74 is raised clear of the ground to enable the disc opener machine to be transported to and from fields.
A tension spring 72 connects the frame 66 to the upper linkage 62 to provide an upward biasing force that tends to lift the disc opener 20. The tension spring 72 as shown in Figures 1 and 2 provides an upward bias force on the disc assembly 1 that counterbalances the weight of the frame 66, disc 74, gauge wheel 74, arm and press wheel 78. Accordingly, in the absence of the hydraulic ram 70, there is a zero down pressure experienced by the discs 74 and gauge wheel 76 that would force them into contact with the ground. The hydraulic ram 70, therefore, applies a required downward force to achieve appropriate contact between the disc 74 and the ground.
The gauge wheel 76 is arranged to travel over the surface of the ground adjacent to a trailing end of the disc 74 as the disc assembly 1 moves forwardly in the direction of travel. The gauge wheel (with reference to Figure 2) is offset from vertical by an acute angle to reduce soil build up in the disc opener 20 when operating on wet soil. The close proximity of the gauge wheel 76 to the disc 74 in the direction of travel ensures that the gauge wheel 76 provides a reasonable indication of the ground level at a position where the disc 74 cuts into the soil.
A sensor plate 90 (Figures 2 and 3) is mounted to the frame 66 so that the sensor plate 90 remains stationary relative to the frame 66. The sensor plate 90 includes a pair of proximity sensors 96, 98 spaced apart in the direction of travel by 5 to 10 cm.
The gauge wheel 76 is rotatably mounted to a location plate 92 which in turn is pivotably mounted to the frame 66 such that both the location plate 92 and the gauge wheel 76 pivot about pivot 96 at a position on the frame 66 ahead of the axis of the gauge wheel 76. The gauge wheel 76 rests on the soil surface under the influence of gravity. However, to avoid bouncing, a biasing force provided by a spring, for example, may be linked between the location plate 92 and the frame to bias the gauge wheel against the soil surface.
An arm 94 extends upwardly from the location plate 92 and in the vicinity of the sensors 96, 98. As the arm is linked to the location plate 92, it provides an indication of the vertical position of the gauge wheel 76 relative to the disc.
Accordingly, the position of the arm 92 can be used as a basis for controlling the height of the disc. For this purpose, the sensors 96, 98 are selected to detect the proximity of the arm 94. Signals generated by the sensors are used to control the hydraulic ram 70 that applies a downward force on the disc 74. The extent of that force controls the extent to which the disc penetrates the soil, thereby controlling the depth of a trench formed by the disc 74.
Specifically, as the disc travels forwardly, the force applied to the disc by the hydraulic ram 70 will cause the disc to penetrate the soil to a depth dependent on the hardness of the soil. Provided the soil hardness remains constant as the disc travels forwardly, the disc will penetrate the soil to a constant depth.
Farmers will select the force that provides disc penetration to the desired depth. However, in the event the soil hardness changes so that it is softer, the same force applied by the hydraulic ram 70 will cause the disc to penetrate the soil to a greater depth.
In this case, the vertical spacing between the disc penetration depth and the soil surface, as represented by the vertical position of the gauge wheel 76 relative to the disc 74, increases. This vertical movement causes a corresponding rotational movement of the location plate 92 about the pivot 96 and is, in turn, reflected in movement of the arm 92 forwardly, having regard to the direction of travel, so that the arm 92 moves into proximity with forward sensor 96. Upon sensing the proximity of the arm 92, the sensor 96 sends a signal to a directional valve 120 to decrease the hydraulic pressure in the hydraulic ram 70. The decrease in pressure causes the disc to penetrate the soil to a lesser extent. As a consequence, the vertical spacing between the disc penetration depth and the soil surface, as represented by the position of the gauge wheel 76, is reduced and the arm 92 moves in a rearward direction away from forward sensor 96.
In the event that the soil is harder, the vertical spacing between the disc penetration depth and the soil surface, as represented by the position of the gauge wheel 76, is reduced and the arm 92 moves in a rearward direction toward the rearward sensor 98. Upon detecting the proximity of the arm 92, the sensor 98 sends a signal to the directional valve 120 to increase the pressure in the hydraulic ram 70. The increase in pressure will cause the disc to penetrate the soil to a greater extent. As a consequence, the vertical spacing between the disc penetration depth and the soil surface, as represented by the position of the gauge wheel 76, is increased and the arm 92 moves in a forward direction away from the rearward sensor 96.
After seed is placed in the formed furrow, soil is replaced in the furrow by gravity causing the sides of the furrow to fall into the furrow. Then press wheel 78 presses down the soil to improve soil contact with the planted seed.
The hydraulic ram 70 for each disc assembly 1 is linked to a central directional valve 120 so that the hydraulic ram pressure adjustments are controlled centrally.
Additionally, only one disc assembly 1 in the series of disc assemblies attached to the main bar may be fitted with the sensor plate and sensors. The applicant has found that this arrangement works well with adjusting the pressure in the hydraulics rams 70 across all the disc assemblies 1. However, it is possible to configure a system in which more than disc assembly 1 is fitted with sensors 96, 98 to account for variations in soil conditions across the width of the seeder machinery.
The advantage of this system, particularly in being incorporated in seeder machinery, is that the depth of penetration of the discs 74 can be selected by adjusting the vertical position of the gauge wheel 76 relative to the disc 74 and positioning the sensors 96, 98 to maintain the disc 74, at a desired position relative to the surface of the soil. The sensors 96, 98 and the hydraulic ram 70 will then automatically apply the hydraulic pressure necessary to achieve the selected penetration depth. This means that the system automatically accounts for variations in soil conditions. This is particularly advantageous because it avoids the need for farmers to rely on their own experience of soil conditions as a basis for controlling the force applied to the discs.
A schematic diagram of suitable hydraulics for the above described system is shown in Figure 4. Hydraulic fluid and pressure are provided from a tank and fan motor respectively through lines 112 and 114 to the directional valve 120.
Line 116 links the directional valve 120 to a series of hydraulic rams 70 in parallel via branch lines 117. The branch lines 117 link to one side of a piston 71 in the hydraulic rams 70. Line 118 links the directional valve 120 to a series of hydraulic rams 70 in parallel via branch lines 119. The branch lines 119 link to the other side of the piston 71 in the hydraulic rams 70. Sensors 96, 98 which detect the position of the arm 94 are linked to the direction valve 120 so that when the arm 94 is in the proximity of the sensor 96 a signal is sent to the directional valve 120 to send hydraulic fluid through line 116 and branch lines 117 so that the hydraulic rams 70 extend. This increases the downward force on the discs 74. When the arm 94 is in the proximity of the sensor 98, hydraulic fluid is sent through the line 118 and branch lines 119 so that the hydraulic rams 70 retract, thereby decreasing the downward force on the discs 74.
A pressure transducer 122 is included in line 116 to provide a pressure readout in a digital display 124 that is located in the cabin of a prime mover, such as a tractor that pulls the disc opener and seed supply equipment.
In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.
Figure 3 is side view of the disc assembly in Figure 1 and showing the configuration of the sensors.
Figure 4 is a schematic representation of a hydraulic system for adjusting the height of the disc in Figure 1 relative to the height of the gauge wheel.
Detailed description A system for controlling the force applied to a tool will be described in the context of seeder machinery in the form of a disc opener. However, it will be appreciated that the system can be applied to other forms of machinery where it is important to control the pressure applied to a tool.
A disc assembly 1 for planting crop seeds is shown in Figure 1. In operation, a series of disc assemblies 1 are mounted to a main bar 42 (Figure 2) pulled by a tractor. Each disc assembly 1 is mounted to the main bar 42 by a clamp 60.
Upper and lower linkages 62, 64 are hingeably connected to the clamp 60 and extend rearwardly of the main bar 42 with respect to the direction of travel. The rear ends of the upper and lower linkages 62, 64 are connected to a frame 66 that extends downwardly and rearwardly. A disc 74 is rotatably mounted to the frame 66 and a gauge wheel 76 is also pivotably mounted to the frame 66.
A press wheel 78 is rotatably mounted to a cantilevered arm 68 that is hingeably connected to the frame 66 to extend rearwardly thereof. A biasing means, such as a hydraulic ram or a compression spring (82 in Figure 2), extends between the arm 68 and the frame 66 to provide a downward biasing force on the press wheel 78.
The compression spring 79 may alternatively be a hydraulic ram. However, in the form of a compression spring, the compression spring 79 includes a pneumatic or hydraulic shock absorber to reduce bouncing of the press wheel 78, so that loose soil covering seed in the furrow is compacted to improve seed-soil contact.
The extent of down force provided by the compression spring 79 is selected to facilitate germination of the seed.
The disc 74 is inclined slightly to the direction of travel such that, as the disc assembly 1 moves forward, the disc 74 creates a narrow furrow. A seed tube 80 is arranged behind the disc 74 having regard to the direction of travel such that seed can be delivered via the seed tube 80 to the furrow formed by the disc 74. The seed tube 80 terminates in a seed boot (not shown) through which seed is funnelled into the furrow.
In operation, the disc 74 forms a furrow by displacing soil laterally of the disc 74.
For the most part, the soil piles-up on the side of the furrow corresponding to a leading surface side of the disc. Other soil is projected into the air laterally and rearwardly of the disc 74. Seed is deposited into the furrow from a seed boot 130.
The gauge wheel 77 runs over the piled-up soil and pushes some of it back into the furrow. Additionally, the gauge wheel 74 deflects some projected soil back into the furrow. As a result, seed disposed in the furrow is covered by loose soil.
A hydraulic ram 70 connects an inner end of the upper linkage 62 to an outer end of the lower linkage 64 so that actuation of the hydraulic ram 70 causes lifting or lowering of the disc 74. Accordingly, the hydraulic ram 70 can be operated to lift the disc assemblies 1 to a position where the disc 74 is raised clear of the ground to enable the disc opener machine to be transported to and from fields.
A tension spring 72 connects the frame 66 to the upper linkage 62 to provide an upward biasing force that tends to lift the disc opener 20. The tension spring 72 as shown in Figures 1 and 2 provides an upward bias force on the disc assembly 1 that counterbalances the weight of the frame 66, disc 74, gauge wheel 74, arm and press wheel 78. Accordingly, in the absence of the hydraulic ram 70, there is a zero down pressure experienced by the discs 74 and gauge wheel 76 that would force them into contact with the ground. The hydraulic ram 70, therefore, applies a required downward force to achieve appropriate contact between the disc 74 and the ground.
The gauge wheel 76 is arranged to travel over the surface of the ground adjacent to a trailing end of the disc 74 as the disc assembly 1 moves forwardly in the direction of travel. The gauge wheel (with reference to Figure 2) is offset from vertical by an acute angle to reduce soil build up in the disc opener 20 when operating on wet soil. The close proximity of the gauge wheel 76 to the disc 74 in the direction of travel ensures that the gauge wheel 76 provides a reasonable indication of the ground level at a position where the disc 74 cuts into the soil.
A sensor plate 90 (Figures 2 and 3) is mounted to the frame 66 so that the sensor plate 90 remains stationary relative to the frame 66. The sensor plate 90 includes a pair of proximity sensors 96, 98 spaced apart in the direction of travel by 5 to 10 cm.
The gauge wheel 76 is rotatably mounted to a location plate 92 which in turn is pivotably mounted to the frame 66 such that both the location plate 92 and the gauge wheel 76 pivot about pivot 96 at a position on the frame 66 ahead of the axis of the gauge wheel 76. The gauge wheel 76 rests on the soil surface under the influence of gravity. However, to avoid bouncing, a biasing force provided by a spring, for example, may be linked between the location plate 92 and the frame to bias the gauge wheel against the soil surface.
An arm 94 extends upwardly from the location plate 92 and in the vicinity of the sensors 96, 98. As the arm is linked to the location plate 92, it provides an indication of the vertical position of the gauge wheel 76 relative to the disc.
Accordingly, the position of the arm 92 can be used as a basis for controlling the height of the disc. For this purpose, the sensors 96, 98 are selected to detect the proximity of the arm 94. Signals generated by the sensors are used to control the hydraulic ram 70 that applies a downward force on the disc 74. The extent of that force controls the extent to which the disc penetrates the soil, thereby controlling the depth of a trench formed by the disc 74.
Specifically, as the disc travels forwardly, the force applied to the disc by the hydraulic ram 70 will cause the disc to penetrate the soil to a depth dependent on the hardness of the soil. Provided the soil hardness remains constant as the disc travels forwardly, the disc will penetrate the soil to a constant depth.
Farmers will select the force that provides disc penetration to the desired depth. However, in the event the soil hardness changes so that it is softer, the same force applied by the hydraulic ram 70 will cause the disc to penetrate the soil to a greater depth.
In this case, the vertical spacing between the disc penetration depth and the soil surface, as represented by the vertical position of the gauge wheel 76 relative to the disc 74, increases. This vertical movement causes a corresponding rotational movement of the location plate 92 about the pivot 96 and is, in turn, reflected in movement of the arm 92 forwardly, having regard to the direction of travel, so that the arm 92 moves into proximity with forward sensor 96. Upon sensing the proximity of the arm 92, the sensor 96 sends a signal to a directional valve 120 to decrease the hydraulic pressure in the hydraulic ram 70. The decrease in pressure causes the disc to penetrate the soil to a lesser extent. As a consequence, the vertical spacing between the disc penetration depth and the soil surface, as represented by the position of the gauge wheel 76, is reduced and the arm 92 moves in a rearward direction away from forward sensor 96.
In the event that the soil is harder, the vertical spacing between the disc penetration depth and the soil surface, as represented by the position of the gauge wheel 76, is reduced and the arm 92 moves in a rearward direction toward the rearward sensor 98. Upon detecting the proximity of the arm 92, the sensor 98 sends a signal to the directional valve 120 to increase the pressure in the hydraulic ram 70. The increase in pressure will cause the disc to penetrate the soil to a greater extent. As a consequence, the vertical spacing between the disc penetration depth and the soil surface, as represented by the position of the gauge wheel 76, is increased and the arm 92 moves in a forward direction away from the rearward sensor 96.
After seed is placed in the formed furrow, soil is replaced in the furrow by gravity causing the sides of the furrow to fall into the furrow. Then press wheel 78 presses down the soil to improve soil contact with the planted seed.
The hydraulic ram 70 for each disc assembly 1 is linked to a central directional valve 120 so that the hydraulic ram pressure adjustments are controlled centrally.
Additionally, only one disc assembly 1 in the series of disc assemblies attached to the main bar may be fitted with the sensor plate and sensors. The applicant has found that this arrangement works well with adjusting the pressure in the hydraulics rams 70 across all the disc assemblies 1. However, it is possible to configure a system in which more than disc assembly 1 is fitted with sensors 96, 98 to account for variations in soil conditions across the width of the seeder machinery.
The advantage of this system, particularly in being incorporated in seeder machinery, is that the depth of penetration of the discs 74 can be selected by adjusting the vertical position of the gauge wheel 76 relative to the disc 74 and positioning the sensors 96, 98 to maintain the disc 74, at a desired position relative to the surface of the soil. The sensors 96, 98 and the hydraulic ram 70 will then automatically apply the hydraulic pressure necessary to achieve the selected penetration depth. This means that the system automatically accounts for variations in soil conditions. This is particularly advantageous because it avoids the need for farmers to rely on their own experience of soil conditions as a basis for controlling the force applied to the discs.
A schematic diagram of suitable hydraulics for the above described system is shown in Figure 4. Hydraulic fluid and pressure are provided from a tank and fan motor respectively through lines 112 and 114 to the directional valve 120.
Line 116 links the directional valve 120 to a series of hydraulic rams 70 in parallel via branch lines 117. The branch lines 117 link to one side of a piston 71 in the hydraulic rams 70. Line 118 links the directional valve 120 to a series of hydraulic rams 70 in parallel via branch lines 119. The branch lines 119 link to the other side of the piston 71 in the hydraulic rams 70. Sensors 96, 98 which detect the position of the arm 94 are linked to the direction valve 120 so that when the arm 94 is in the proximity of the sensor 96 a signal is sent to the directional valve 120 to send hydraulic fluid through line 116 and branch lines 117 so that the hydraulic rams 70 extend. This increases the downward force on the discs 74. When the arm 94 is in the proximity of the sensor 98, hydraulic fluid is sent through the line 118 and branch lines 119 so that the hydraulic rams 70 retract, thereby decreasing the downward force on the discs 74.
A pressure transducer 122 is included in line 116 to provide a pressure readout in a digital display 124 that is located in the cabin of a prime mover, such as a tractor that pulls the disc opener and seed supply equipment.
In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.
Claims (14)
1. A system for controlling the force applied to a tool for cutting a seed trench in soil, the system comprising:
(a) a cutting tool;
(b) a gauge for determining a first position indicative of the surface of the soil;
(c) a drive assembly for applying a force to the cutting tool to position the cutting tool at a second position relative to the first position, and wherein the drive assembly determines the applied force based on the spacing between the first position and the position of the tool.
(a) a cutting tool;
(b) a gauge for determining a first position indicative of the surface of the soil;
(c) a drive assembly for applying a force to the cutting tool to position the cutting tool at a second position relative to the first position, and wherein the drive assembly determines the applied force based on the spacing between the first position and the position of the tool.
2. The system defined in claim 1, wherein the cutting tool comprises a disc for cutting a seed furrow in soil and the gauge includes a gauge wheel for travelling on the surface of the soil.
3. The system defined in claim 2, wherein the drive assembly comprises one or more sensors that provide an indication of the vertical position of the gauge wheel relative to the cutting disc and comprises a drive member that applies a force to the disc in response to a signal from the or each sensor.
4. The system defined in claim 3, wherein the drive member is a hydraulic or pneumatic ram.
5. The system defined in any one of the preceding claims, wherein the cutting disc is part of a disc assembly that comprises a chassis on which the disc is mounted and comprises a cantilevered arm extending from the chassis and on which the gauge wheel is mounted.
6. The system defined in claim 5, wherein the one or more sensors are mounted on the chassis in positions that track movement of the cantilevered arm such that upward movement of the arm causes the one or more sensors to reduce the force applied to the disc and such that downward movement of the arm causes the one or more sensors to increase the force applied to the disc.
7. The system defined in claim 5, wherein the one or more sensors are mounted on the chassis in positions that track movement of the cantilevered arm such that downward movement of the arm causes the one or more sensors to reduce the force applied to the disc and such that upward movement downward movement of the arm causes the one or more sensors to increase the force applied to the disc.
8. The system defined in any one of the preceding claims, wherein system comprises a plurality of cutting tools and the drive assembly includes a plurality of drive members that are operable to apply a force to a respective cutting tool to position the respective cutting tools at a second position relative to the first position.
9. The system defined claim 2, wherein the system further comprises a biasing means that counteracts the weight force of at least the cutting disc and a chassis to which the cutting disc is connected so that the drive assembly is primarily responsible for applying a force to the cutting tool to position the cutting tool at the second position.
10. A disc assembly for sowing seeds in soil, the disc assembly comprising:
(a) a chassis having link that enables the chassis to be connected to a vehicle to trail the vehicle;
(b) a cutting disc mounted to the chassis and being configured to cut a furrow in soil to enable seed to be delivered into the furrow;
(c) a gauge wheel connected to a member that is, in turn, pivotably connected to the chassis such that the gauge wheel overlaps a trailing edge of the cutting disc and travels on the soil surface and wherein the pivotable connection allows the gauge wheel to move vertically with variations in the soil surface level relative to the cutting disc; and (d) the system defined in any one of claims 2 to 9 wherein the system controls the depth of soil penetration by the cutting disc based on the vertical spacing between the cutting disc and the gauge wheel.
(a) a chassis having link that enables the chassis to be connected to a vehicle to trail the vehicle;
(b) a cutting disc mounted to the chassis and being configured to cut a furrow in soil to enable seed to be delivered into the furrow;
(c) a gauge wheel connected to a member that is, in turn, pivotably connected to the chassis such that the gauge wheel overlaps a trailing edge of the cutting disc and travels on the soil surface and wherein the pivotable connection allows the gauge wheel to move vertically with variations in the soil surface level relative to the cutting disc; and (d) the system defined in any one of claims 2 to 9 wherein the system controls the depth of soil penetration by the cutting disc based on the vertical spacing between the cutting disc and the gauge wheel.
11. The disc assembly defined in claim 10, wherein the disc assembly further comprises a press wheel for compacting loose soil covering seed in the furrow to improve seed-soil contact.
12. The disc assembly defined in claim 11, wherein the disc assembly further comprises a biasing element connected to both the chassis and an arm on which the press wheel is mounted to apply a force for compacting soil in the furrow.
13. The disc assembly defined in claim 12, wherein the biasing element includes impact absorbing means to reduce bouncing of the press wheel.
14. A disc seeder for sowing seeds in soil, the disc seeder comprising a plurality of disc assemblies as defined in any one of claim 10 to 13.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AU2011903081A AU2011903081A0 (en) | 2011-08-03 | Pressure controller for forces applied to tools | |
| AU2011903081 | 2011-08-03 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2784578A1 true CA2784578A1 (en) | 2013-02-03 |
Family
ID=47664731
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA2784578A Abandoned CA2784578A1 (en) | 2011-08-03 | 2012-08-03 | Pressure controller for forces applied to tools |
Country Status (2)
| Country | Link |
|---|---|
| AU (1) | AU2012211338A1 (en) |
| CA (1) | CA2784578A1 (en) |
-
2012
- 2012-08-03 AU AU2012211338A patent/AU2012211338A1/en not_active Abandoned
- 2012-08-03 CA CA2784578A patent/CA2784578A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| AU2012211338A1 (en) | 2013-02-21 |
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| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Dead |
Effective date: 20160803 |