Patent Description:
The method has a particular application to seed drills and precision seed drills, in particular to those drills that use furrow openers with disc tools or disc shares.

When sowing crops, it is a known rule of thumb that a sowing depth of approximately <NUM> times the diameter of the seed is often desirable. For grains, this often means a sowing depth of about <NUM>, and for oil-yielding plants a sowing depth of <NUM>-<NUM>. This means that it is desirable to be able to control the sowing depth with a high degree of precision.

A known method for controlling the sowing depth is to spring-load the furrow openers and to vary the speed of travel in order to compensate for varying hardness of the soil.

It is also known to provide seed drills with support wheels, which limit the penetration of the furrow opener into the ground. There are seed drills that have one or more support wheels for each individual output unit, such as furrow opener or row unit. By adjusting the position of a gauge wheel in relation to a furrow opener, it is possible to control, with a high degree of precision, the depth at which the seed is placed. There are also seed drills that have a centrally adjustable working depth. Such seed drills are disclosed in <CIT>, for example.

Seed drills, in particular those parts of the seed drill coming into contact with the soil, are exposed to wear. It is generally the case, for example, that discs for disc shares are used for so long that their diameter decreases by several cm. It will be appreciated that this reduction of the diameter can have a considerable impact on the sowing depth that is obtained.

Seed drills are known from e.g. <CIT>, <CIT> and <CIT>.

There is therefore a need to be able to ensure that a correct sowing depth is always obtained.

It is an object of this document to provide a method for ensuring that a correct sowing depth is obtained. A particular object is to provide such a method that is additionally user friendly and efficient in terms of time.

The invention is defined by the accompanying independent claims. Embodiments are set forth in the accompanying dependent claims, in the description that follows and in the accompanying drawings.

According to a first aspect, a method is made available for calibration of the working depth of an agricultural implement for distributing granular material to the ground over which the agricultural implement is travelling, The agricultural implement has an output unit comprising a ground-engaging tool for forming a furrow, a gauge wheel, and at least one actuator for controlling the ground pressure on the tool or for controlling the position of the gauge wheel relative to the tool. The method comprises placing the agricultural implement on a ground surface that is level and sufficiently hard for the tool not to penetrate into the ground surface, wherein a load from the output unit bears on one of tool and gauge wheel, using the actuator to transfer the load to the other of tool and gauge wheel, recording a first parameter of the actuator while the load is being transferred, which first parameter indicates a force on the actuator, recording a second parameter for the gauge wheel in relation to the tool while the load is being transferred, which second parameter indicates a relative vertical position between the gauge wheel and the tool, identifying a change of the first parameter that occurs when the load is transferred, and assigning the change to a value of the second parameter.

The method thus comprises placing the output unit such that it bears on one of tool and gauge wheel, and then transferring the load to the other of tool and gauge wheel.

The ground surface can be, for example, a concrete floor, or a ground covering of stone, concrete or asphalt. Alternatively, the ground surface can consist of extremely densely packed sand, gravel or earth.

It will be appreciated that the load can be transferred by means of the actuator being driven to move the depth regulator downwards, wherein the force on the actuator increases when the depth regulator takes over the load, or that the load can be transferred by means of the actuator being driven, or unloaded, to move the depth regulator upwards, wherein the force on the actuator decreases when the tool takes over the load.

In this way, a weight transfer is effected from one of tool and depth regulator to the other of tool and depth regulator.

At the same time, the second parameter is recorded, which indicates for example a certain position of the actuator.

Therefore, by means of the method, the height of the tool relative to the depth regulator is determined based on the force needed to lift the tool from the ground. The position where the change of force is measured can be set as a zero point, i.e. the position where the working depth is zero.

A calibration method is thus obtained which permits calibration of the output unit, such that wear, for example, can be taken into account.

According to some embodiments, the actuator can be arranged to control the position of the gauge wheel relative to the tool, wherein the method can comprise transferring weight from the tool to the gauge wheel, and wherein the first parameter can indicate an increase of the load on the actuator.

Alternatively, or in addition, the actuator can be arranged to control the position of the gauge wheel relative to the tool, wherein the method comprises transferring weight from the gauge wheel to the tool, and the first parameter indicates a decrease of the load on the actuator.

The actuator can be designed for adjustment of a single output unit, a subset of the output units of the agricultural implement, or all of the output units of the agricultural implement.

The actuator can be an electrical actuator, wherein said first parameter indicates a drive current for the actuator, and wherein said change can comprise a change of the drive current.

Alternatively, the actuator can be a hydraulic actuator, wherein said first parameter indicates a pressure that is present in the actuator, and wherein the change can comprise a change of the pressure.

The agricultural implement can comprise a first actuator arranged to control the position of the gauge wheel relative to the tool, and a second actuator arranged to control the ground pressure for the output unit. The first parameter is detected at said first actuator.

The output unit can comprise a unit frame, which is mounted movably on an implement frame, wherein the tool and the gauge wheel are supported by the unit frame.

The unit frame can comprise one or more parts, which can be movable relative to one another.

The tool can comprise at least one disc tool, such as a furrow opener disc.

The gauge wheel can overlap the disc tool, seen in a vertical plane containing a work direction.

The method can further comprise a step in which, when driving the agricultural implement across field, a working depth is set based on said assignment of the change to a value of the second parameter.

According to a second aspect, an agricultural implement is provided for distributing granular material to the ground over which the agricultural implement is travelling. The agricultural implement comprises an output unit, comprising a ground-engaging tool for forming a furrow, a gauge wheel, at least one actuator for controlling the position of the gauge wheel relative to the tool, and a control unit, which is arranged to control the actuator. The control unit is so configured that, when the agricultural implement is placed on a ground surface that is level and sufficiently hard for the tool not to penetrate into the ground surface, a load from the output unit bears on one of tool and gauge wheel, a first parameter of the actuator is recorded while the load is being transferred, which first parameter indicates a force on the actuator, a second parameter for the gauge wheel in relation to the tool is recorded while the load is being transferred, which second parameter indicates a relative vertical position between the gauge wheel and the tool, a change of the first parameter is identified that occurs when the load is transferred, and the change is assigned to a value of the second parameter.

The agricultural implement can comprise a first actuator arranged to control the position of the gauge wheel relative to the tool, and a second actuator arranged to control the ground pressure for the output unit. Said first actuator can have an arrangement for detecting the first parameter.

The agricultural implement comprises a depth adjustment mechanism, for adjusting the working depth, and a ground pressure adjustment mechanism, wherein the depth adjustment mechanism has a position sensor for recording the second parameter.

<FIG> show equipment comprising an agricultural implement <NUM> which is coupled to a towing vehicle <NUM>, which is illustrated in the form of a tractor.

The agricultural implement <NUM> is illustrated in the form of a seed drill, which in <FIG> consists of a volumetrically fed seed drill. It will be appreciated that the concepts described herein can also be applied to a precision seed drill.

The agricultural implement <NUM> has a main frame <NUM>, to which a draw bar <NUM> and a transverse beam <NUM> are connected. The main frame <NUM>, the draw bar <NUM> and the beam <NUM> can be arranged fixed in relation to one another. One, two or more wheels 13a, 13b can be arranged to completely or partially support the agricultural implement <NUM>. Alternatively, two or more of the parts <NUM>, <NUM>, <NUM> can be mounted movably relative to one another. Specifically, the beam <NUM> can comprise one, two, three, four or five portions which are movable relative to one another and which can be arranged such that the beam <NUM> can be folded between a work position of large width and a transport position of small width.

The main frame <NUM> can support one or more containers <NUM>, for the material that is to be distributed, a fan <NUM> for generating an air flow that can be passed through a primary channel <NUM>, <NUM>, via a feeder <NUM> for output from the container, to a distributor <NUM> in which the air flow mixed with material is distributed via secondary channels <NUM> to a plurality of output units <NUM>.

<FIG> shows the agricultural implement <NUM> with the output unit <NUM> in a folded-up position, for example for road transport.

<FIG> shows the agricultural implement <NUM> with the output unit <NUM> in the work position.

With reference to <FIG>, an output unit <NUM> can comprise a unit frame <NUM>, which supports a plurality of of functional components of the output unit <NUM>.

The output unit <NUM> can comprise a furrow opener <NUM> which can have the form of a disc tool, which can be rotatable in a disc plane that can be vertical and, seen in a horizontal plane, can have an acute angle to a vertical plane containing the work direction F. Alternatively, the disc plane can slope slightly. The function of the furrow opener is to open a furrow in which the material, for example seeds, fertilizer and/or pesticide, can be placed.

The furrow opener <NUM> can be mounted rotatably on a lower portion of the unit frame <NUM>.

The output unit <NUM> can comprise a depth regulator <NUM> which can have the form of a wheel, which can be adjustable in height relative to the furrow opener <NUM>, such that a working depth of the furrow opener is controllable with the aid of the depth regulator <NUM>.

The depth regulator <NUM> can be connected to an adjustment device <NUM>, <NUM> for adjusting a working depth for the output unit <NUM>.

The adjustment device can comprise a plurality of links <NUM>, <NUM>, which are connected to the depth regulator <NUM>.

For example, a depth regulator in the form of a wheel can be arranged on a lever arm, which is rotatable about an axle to which a first link <NUM> is connected, such that translation of the link <NUM> causes the axle to rotate, thus changing the vertical position of the depth regulator.

The first link <NUM> can be connected directly to an actuator <NUM> (<FIG>) for depth adjustment or to another link <NUM>, which in turn can be connected to the actuator <NUM>.

In some embodiments, the actuator <NUM> can be a hydraulic actuator. In other embodiments, the actuator can be an electrical actuator.

In some embodiments, the actuator <NUM> can be configured to control the depth adjustment for a single output unit <NUM>.

In other embodiments, the actuator <NUM> can be configured to control the depth adjustment for a group of output units. Such a group can be a subset of all the output units <NUM> of the agricultural implement. For example, the group can be output units associated with one side section of the agricultural implement, or a subset of the output units of such a side section.

In further embodiments, the actuator <NUM> can be configured to control the depth adjustment for all the output units of the agricultural implement.

The output unit <NUM> can comprise a material outlet <NUM>, which can have the form of a pipe, a share or a blade. The material outlet <NUM> can be fixed or movable relative to the unit frame <NUM>.

The output unit can moreover comprise a press wheel <NUM>, which can be arranged directly behind the output unit <NUM>, seen in the work direction, and which can have the function of ensuring that output material comes properly into contact with the soil at the bottom of the furrow.

The output unit can further comprise a closer <NUM> for closing the furrow that is formed by the furrow opener. The closer can comprise one or more closer wheels, scrapers or the like for placing soil back in the furrow.

A ground pressure actuator <NUM> can be arranged to interact with the output unit <NUM>. Such a ground pressure actuator <NUM> can act between a portion <NUM> of the implement frame and the unit frame <NUM> for the purpose of applying a pressure to the ground, such that a desired sowing depth can be obtained.

As is illustrated in <FIG>, the lower portion of the depth regulator <NUM> can bear against a ground surface My, wherein a lower portion of the furrow opener <NUM> produces a furrow with a bottom at a level Mb, which is located vertically below the ground surface My.

With reference to <FIG>, a method of calibrating the furrow opener in relation to the depth regulator <NUM> will now be described.

<FIG> shows a first step in a calibration method, in which the agricultural implement <NUM> is placed on a substantially level ground surface that is sufficiently hard for the furrow opener <NUM> not to penetrate into the ground surface. The implement then sinks down such that the furrow opener <NUM> bears against the ground.

With reference to <FIG>, the method preferably proceeds from a position in which substantially the whole weight of the output unit bears on the furrow opener <NUM> and substantially no weight bears on the gauge wheel <NUM>. From this position, the actuator <NUM> which controls the gauge wheel <NUM> is manoeuvred such that the gauge wheel <NUM> is placed against the ground surface, and moreover so as to lift the furrow opener <NUM>, while a first parameter which indicates the force exerted by the actuator <NUM> is recorded, and a second parameter which indicates a position of the actuator <NUM> is recorded.

By analysing the first parameter, it is possible to decide when the furrow opener <NUM> begins to lift from the ground surface, since the force exerted by the actuator will then increase on account of the fact that the depth regulator, from this point, will markedly increase, since it thereafter bears a greater load. By identifying the second parameter and assigning a value thereof to the increase of the force, it is possible to determine a zero position for the actuator, i.e. a position where the working depth is zero.

Upon activation of the output unit <NUM>, it is then possible to proceed from the zero position in adjustment of the working depth.

The actuator <NUM> can be provided with a sensor <NUM> for detection of pressure or drive current and/or for detection of the position of the actuator. The sensor <NUM> and the actuator <NUM> can be connected to a control unit <NUM>, with the assistance of which the above-discussed analysis and control are performed.

The control unit <NUM> can be configured with such functions as are necessary, and known per se, for the control of hydraulic or electrical actuators.

The control unit <NUM> can be a central control unit for the agricultural implement <NUM> or can be part of a control unit of the towing vehicle. For example, the control unit can be implemented as special software or as a function in a general control unit.

Alternatively, the operation can be performed the other way, i.e. the gauge wheel starts in a position in which substantially the whole weight of the output unit is taken up by the gauge wheel, the latter being drawn upward for adjustment of a greater working depth. In such a method, a force reduction on the actuator which controls the position of the gauge wheel can be recorded when the load transfers from the depth regulator to the tool.

The calibration method described herein can also be used for other types of agricultural implements which comprise ground-engaging tools and some form of depth regulator, such as wheels, where the tool and the depth regulator are adjustable in height relative to each other.

Claim 1:
Method for calibration of working depth of an agricultural implement (<NUM>) for distributing granular material to the ground over which the agricultural implement is travelling,
the agricultural implement (<NUM>) having an output unit (<NUM>) comprising a ground-engaging tool (<NUM>) for forming a furrow, a gauge wheel (<NUM>), and at least one actuator (<NUM>) for controlling the position of the gauge wheel (<NUM>) relative to the tool (<NUM>),
wherein the method comprises:
placing the agricultural implement (<NUM>) on a ground surface that is level and sufficiently hard for the tool (<NUM>) not to penetrate into the ground surface,
wherein a load from the output unit (<NUM>) bears on one of the tool (<NUM>) and the gauge wheel (<NUM>),
using the actuator (<NUM>) to transfer the load to the other one of the tool (<NUM>) and the gauge wheel (<NUM>),
recording a first parameter of the actuator (<NUM>) while the load is being transferred, which first parameter indicates a force on the actuator (<NUM>),
recording a second parameter for the gauge wheel (<NUM>) in relation to the tool (<NUM>) while the load is being transferred, which second parameter indicates a relative vertical position between the gauge wheel (<NUM>) and the tool (<NUM>),
identifying a change of the first parameter that occurs when the load is transferred, and
assigning the change to a value of the second parameter.