Patent Description:
The undisclosed <CIT>, discloses a vehicle for treating an agricultural field that includes a weeding-injection unit and a control unit. The weeding-injection unit includes at least one weeding knife and at least one actuator configured to move the at least one weeding knife for cutting and destroying weed. The control unit is configured to identify a plant and to control the at least one actuator to treat the identified plant.

Document <CIT> discloses a weeding unit for treating an agricultural field according to the preamble of claim <NUM>.

When weed is cut by a weeding unit the roots or parts of the roots of the weed may remain in the soil of the agricultural field and may grow again. So, it is an objective to provide a weeding unit that separates and removes the roots out of the agricultural field.

According to an aspect of the invention there is provided a weeding unit for treating an agricultural field including a carrier, at least one working lever moveably connected with the carrier, at least one actuator for moving the at least one working lever and a control unit configured to distinguish crop from weed and to control the at least one actuator for treating the weed. The at least one working lever includes a weeding knife and at least one harrowing tine.

When crop is detected the at least one working lever may be moved to an opened position to avoid damaging the crop by the weeding knife and the at least one harrowing tine. In case of weed, the at least one working lever may be moved to a closed position to cut the weed with the weeding knife. The at least one harrowing tine may harrow the agricultural field and pull the weed cut by the weeding knife. While the weed is pulled by the at least one harrowing tine the roots or part of the roots of the weed are pulled out of the soil and removed from soil.

The weeding unit may also include a camera for detecting crop and weed.

Based on the captured images of the camera the control unit may distinguish crop from weed and control the working lever to treat the weed and to spare the crop.

The at least one harrowing tine may be moveably connected with the weeding knife for moving the at least one harrowing tine relative to the weeding knife.

Thus, the at least one harrowing tine may be moveable in a different direction than the weeding knife or may be moveable independently from the weeding knife.

The at least one harrowing tine may be connected with a locking mechanism for blocking a movement of the at least one harrowing tine relative to the weeding knife.

The locking mechanism may be a ratchet to block and unlock the at least one harrowing tine. If blocked, the at least one harrowing tine may move synchronously with a movement of the weeding knife such as the at least one harrowing tine would be fixed to the weeding knife. If unlocked, the at least one harrowing tine may by moveable relative to the weeding knife.

The at least one harrowing tine may be pivotably connected with the weeding knife about a pivot axis.

So, the at least one harrowing tine may be connected to the weeding knife by a pivot joint for rotating on the weeding knife.

The at least one working lever may be pivotably connected with the carrier about a pivot axis. The pivot axis of the working lever may be parallel to the pivot axis of the harrowing tine.

If both the pivot axis of the working lever and the pivot axis of the harrowing tine are parallel the range of the relative movement of the at least one harrowing tine can be extended without the risk of a collision between the at least one harrowing tine and the working lever.

The least one working lever may include a first actuating element configured to move the at least one harrowing tine into a first deflected position.

The at least one working lever may comprises a second actuating element configured to move the at least one harrowing tine into a second deflected position.

The movement caused by the first actuating element may be contrary to the movement of the second actuating element so that the at least one harrowing tine may be moveable from the first deflected position to the second deflected position and vice versa.

The first actuating element and the second actuating element may be configured to move the at least one harrowing tine contrary for urging the at least one harrowing tine into a neutral position.

The neutral position may be a position between the first and the second deflected position. Starting from the neutral position, the at least one harrowing tine may be rotated into the first deflected position when rotated in a first rotation direction and into the second deflected position when rotated in a second rotation direction contrary to the first rotation direction.

The actuating element may be a torsion spring.

One end of the torsion spring may be fixed to the working lever and the other end to the at least one harrowing tine. If both, the first and the second actuating element are designed as a torsion spring the spring force of the first actuating element may be oriented contrary to the spring force of the second actuating element. The actuating element for moving the at least one harrowing tine into the first or the second deflected position may be any other device such as an electromechanical actuator controlled by the control unit. In this case, the first and second actuating element are combined in the same actuating element.

The least one working lever may comprise at least one adjustment device for adjusting the actuation force of the actuating element.

For example, the adjustment device may be configured to adjust the bias of the torsion spring. The higher the bias is adjusted the higher the actuation force of the corresponding actuation actuating element may be adjusted. Dependent on the setting of the adjustment device the actuation delay of the movement of the at least one harrowing tine can be adjusted for both moving into the first deflected position and moving into the second deflected position.

The least one working lever may comprise a first adjustment device for adjusting the actuation force of the first actuating element and a second adjustment device for adjusting the actuation force of the second actuating element.

The actuation force for moving the at least one harrowing tine into the second deflected position may be adjusted higher than the actuation force for moving the at least one harrowing tine into the first deflected position.

Thus, it can be ensured that the at least one harrowing tine may be moved back to the neutral position when deflected in the second position.

The at least one adjustment device may be an adjustment screw integrated into the weeding knife.

But other adjustment devices instead of a adjustment screw may be possible.

The at least one harrowing tine may be designed such that a ground engageable end of the at least one harrowing tine in at least a neutral position of the harrowing tine is more distant from the carrier than a blade of the weeding knife.

Thus, the weed is cut before the at least one harrowing tine gets in contact with the weed to pull the roots out of the soil. Another advantages of a longer distance are a higher efficiency of the weeding action and that the risk for residue build-up is decreased. The at least one harrowing tine may be designed that the ground engageable end is more distant from the carrier than a blade of the weeding knife also in positions of the harrowing tine other than the neutral position.

An inclination of the at least one harrowing tine may be adjustable.

Thus, an angle between the at least one harrowing tine and the ground of the agricultural field can be alternated wherein the angle between the at least one harrowing tine and the ground may be adjusted to increase the chance that residue or dragged weeds will be released earlier.

Another aspect includes a method for treating an agricultural field with a weeding unit traversing the agricultural field with the steps of detecting crop in a crop row of the agricultural field, moving the at least one weeding knife to an opened position and moving the at least one harrowing tine to a neutral position for preventing of treating the crop, moving the at least one weeding knife to a closed position while the at least one harrowing tine remains in a deflected position for treating the crop row with the at least one weeding knife, and moving the at least one harrowing tine to the neutral position delayed to the at least one weeding knife for additional treating of the crop row with the at least one harrowing tine.

The method may be used to control the weeding unit described above. When crop is detected the at least one working lever may be moved to an opened position to avoid damaging the crop by the weeding knife and the at least one harrowing tine. The at least one harrowing tine may be moved to the neutral position for preventing of treating the crop based on a friction force between the ground of the agricultural field and the ground engageable end of the at least one harrowing tine. In case of weed, the at least one working lever may be moved to a closed position to cut the weed with the weeding knife. The at least one harrowing tine may remain in the deflected position to avoid a damage of the crop. After the weed was cut by the weeding knife the at least one harrowing tine may harrow the agricultural field and pull the weed cut by the weeding knife. While the weed is pulled by the at least one harrowing tine the roots or part of the roots of the weed are pulled out of the soil and removed from soil.

The delayed movement of the at least one harrowing tine to the neutral position may be time-delayed.

The delayed movement of the at least one harrowing tine to the neutral position may be based on a travel distance of the weeding unit.

The delayed movement of the at least one harrowing tine may be adjustable by the adjustment device. In case of an electromechanical actuator for controlling the at least one harrowing tine the delayed movement may be controllable by the control unit.

The at least one weeding knife may be moved to a closed position if weed, an absence of crop or both is detected.

Since no crop is detected, no crop may be damaged when the at least one weeding knife is moved to the closed position. The weeding knives can be moved to the closed position even if no weed is detected to aerate the soil by the blades of the weeding knives.

The method may also include the step of separating roots of a weed from soil of the agricultural field with the at least one harrowing tine.

As mentioned above, the at least one harrowing tine may harrow the agricultural field and pull the weed cut by the weeding knife. While the weed is pulled by the at least one harrowing tine the roots or part of the roots of the weed are pulled out of the soil and removed from soil.

Where features are described with reference to a single aspect or embodiment, it should be understood that such features are applicable to all aspects and embodiments unless otherwise stated or where such features are incompatible.

Several aspects of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:.

<FIG> shows an agricultural vehicle <NUM> driving on an agricultural field <NUM> in a driving direction <NUM>. The agricultural vehicle <NUM> comprises a hitch <NUM> to which an implement <NUM> is connected with. The implement <NUM> comprises two weeding units 4a and 4b for treating weeds <NUM> growing on the agricultural field <NUM> between crops <NUM>. The weeding unit 4a may be equivalent to the weeding unit 4b.

The crops <NUM> are arranged in different crop rows 6a to 6d. The position of the weeding units 4a and 4b may be adjustable so that each weeding unit 4a and 4b may be brought into alignment with a separate crop row, e. weeding unit 4a with crop row 6b and weeding unit 4b with crop row 6c.

<FIG> show one of the weeding units in more detail, e. weeding unit 4a. The weeding unit 4a comprises a carrier <NUM> to which a left working lever 15a and a right working lever 15b are pivotably connected with. The left working lever 15a may rotate about a left pivot axis <NUM> and the right working lever 15b may rotate about a right pivot axis <NUM>. The left working lever 15a is driven by a left actuator <NUM> and the right working lever 15b is driven by a right actuator <NUM> to pivot the working levers 15a and 15b.

The actuators <NUM> and <NUM> may comprise an electric motor and a gear or any other type of drive such as a hydraulic drive.

The carrier <NUM> also comprises a camera <NUM> for detecting the crops <NUM> and the weeds <NUM>. The camera <NUM> is connected with a control unit <NUM> to send the captured images of the crops <NUM> and weeds <NUM> to the control unit <NUM>. The control unit <NUM> analyses the captured images and distinguishes crop <NUM> from weed <NUM>. Depending on whether crop <NUM> or weed <NUM> was detected the control unit <NUM> controls the left and the right actuator <NUM> and <NUM> to drive the left and right working levers 15a and 15b. The left and the right actuator <NUM> and <NUM> may drive the left and right working levers 15a and 15b independently from each other (see <FIG>). The left and right working levers 15a and 15b are rotated into a closed position as shown in <FIG> if weed <NUM> is detected and into an opened position as shown in <FIG> if crop <NUM> is detected.

The captured images of the cameras <NUM> of each weeding unit 4a and 4b are also used to check whether the positions of the weeding units 4a and 4b are in alignment with the corresponding crop rows, for example whether weeding unit 4a is aligned with crop row 6b and weeding unit 4b is aligned with crop row 6c. If not, the implement <NUM> adjusts the position of the corresponding weeding unit to bring each weeding unit 4a and 4b into alignment with its corresponding crop row. Optionally, also the hitch <NUM> may be adjusted to change the position of the implement <NUM>. Also optionally, the implement <NUM> may comprise a GNSS receiver to determine and adjust the position of the implement <NUM> or the weeding units 4a and 4b to bring them in alignment with the crop rows.

The right working lever 15b comprises a weeding knife <NUM> with a blade <NUM> for cutting or destroying weed <NUM>. Additionally, the right working lever 15b comprises at least one harrowing tine <NUM> with a ground engageable end <NUM> for pulling the weed <NUM> including its roots <NUM> out of the agricultural field <NUM> and separating the roots <NUM> of the weed <NUM> from soil of the agricultural field <NUM>. The at least one harrowing tine <NUM> is attached to an arm <NUM> that is pivotably connected with an abutment <NUM> of the weeding knife <NUM> so that the at least one harrowing tine <NUM> may rotate relatively to the weeding knife <NUM> about a pivot axis <NUM> (as can be seen in <FIG>).

The at least one harrowing tine <NUM> may be actuated by a first actuating element <NUM> and a second actuating element <NUM>. The first actuating element <NUM> may be a torsion spring attached between the abutment <NUM> and the arm <NUM> to urge the at least one harrowing tine <NUM> to a first deflected position (as can be seen in <FIG>). The second actuating element <NUM> may also be a torsion spring attached between the abutment <NUM> and the arm <NUM> to urge the at least one harrowing tine <NUM> to a second deflected position (as can be seen in <FIG>). Thus, the first actuating element <NUM> and the second actuating element <NUM> are configured to move the at least one harrowing tine <NUM> contrary so that the at least one harrowing tine <NUM> is urged by both actuating elements <NUM> and <NUM> to a neutral position (as can be seen in <FIG>, <FIG>). , the at least one harrowing tine <NUM> holds the neutral position when an equilibrium of forces of the first and second actuating elements <NUM> and <NUM> acting on the arm <NUM> is reached.

The right working lever 15b also comprises a first and a second adjustment device <NUM> and <NUM>. The first adjustment device <NUM> is an adjustment screw screwed in the right weeding knife <NUM> for adjusting the actuation force of the first actuating element <NUM>. The second adjustment device <NUM> is also an adjustment screw screwed in the right weeding knife <NUM> for adjusting the actuation force of the second actuating element <NUM>. As can be seen in <FIG>, the first and the second adjustment devices <NUM> and <NUM> can be separately screwed in to increase the actuation force of the corresponding actuating element <NUM> or <NUM>, or separately screwed out to decrease the actuation force of the corresponding actuating element <NUM> or <NUM>. The second adjustment device <NUM> may be screwed in more than the first adjustment device <NUM> so that the actuation force of the second actuating element <NUM> for moving the at least one harrowing tine <NUM> into the second deflected position (see <FIG>) is adjusted higher than the actuation force of the first actuating element <NUM> for moving the at least one harrowing tine <NUM> into the first deflected position (see <FIG>).

The carrier <NUM> also comprises a left end stop <NUM> to abut the harrowing tines <NUM> of the left working lever 15a and a right end stop <NUM> to abut the harrowing tines <NUM> of the right working lever 15b.

The left working lever 15a is equivalent to the right working lever 15b and comprises a weeding knife <NUM> with a blade <NUM> for cutting or destroying weed <NUM>. Additionally, the left working lever 15a comprises at least one harrowing tine <NUM> with a ground engageable end <NUM> for pulling the weed <NUM> including its roots <NUM> out of the agricultural field <NUM> and separating the roots <NUM> of the weed <NUM> from soil of the agricultural field <NUM>. The at least one harrowing tine <NUM> is attached to an arm <NUM> that is pivotably connected with an abutment <NUM> of the weeding knife <NUM> so that the at least one harrowing tine <NUM> may rotate relatively to the weeding knife <NUM> about a pivot axis <NUM>.

The at least one harrowing tine <NUM> may be actuated by a first actuating element <NUM> and a second actuating element <NUM>. The first actuating element <NUM> may be a torsion spring attached between the abutment <NUM> and the arm <NUM> to urge the at least one harrowing tine <NUM> to a first deflected position. The second actuating element <NUM> may also be a torsion spring attached between the abutment <NUM> and the arm <NUM> to urge the at least one harrowing tine <NUM> to a second deflected position. Thus, the first actuating element <NUM> and the second actuating element <NUM> are configured to move the at least one harrowing tine <NUM> contrary so that the at least one harrowing tine <NUM> is urged by both actuating elements <NUM> and <NUM> to a neutral position (as can be seen in <FIG>). , the at least one harrowing tine <NUM> holds the neutral position when an equilibrium of forces of the first and second actuating elements <NUM> and <NUM> acting on the arm <NUM> is reached.

The left working lever 15a also comprises a first and a second adjustment device <NUM> and <NUM>. The first adjustment device <NUM> is an adjustment screw screwed in the left weeding knife <NUM> for adjusting the actuation force of the first actuating element <NUM>. The second adjustment device <NUM> is also an adjustment screw screwed in the left weeding knife <NUM> for adjusting the actuation force of the second actuating element <NUM>. The first and the second adjustment devices <NUM> and <NUM> can be separately screwed in to increase the actuation force of the corresponding actuating element <NUM> or <NUM>, or separately screwed out to decrease the actuation force of the corresponding actuating element <NUM> or <NUM>. The second adjustment device <NUM> may be screwed in more than the first adjustment device <NUM> so that the actuation force of the second actuating element <NUM> for moving the at least one harrowing tine <NUM> into the second deflected position is adjusted higher than the actuation force of the first actuating element <NUM> for moving the at least one harrowing tine <NUM> into the first deflected position.

<FIG> show each a right part of the weeding unit 4a with some modifications of the right working lever 15b. These modifications are also applicable to the left working lever 15a as well as to the other weeding unit 4b of the implement <NUM>.

The length of the at least one harrowing tines can be different. As can be seen in <FIG>, the harrowing tines <NUM> are shorter than the harrowing tines <NUM> or <NUM> of the weeding unit 4a shown in <FIG>. The shorter the harrowing tines are the closer the ground engageable ends <NUM> and <NUM> are positioned to the blades <NUM> and <NUM>. But longer harrowing tines have the advantage that there is some distance between the cutting or weeding of the weeds <NUM> by the blades <NUM>, <NUM> and the harrowing action by the harrowing tines <NUM>, <NUM>. This is more efficient since the two separate actions cause more harm to the weeds <NUM> than when these actions are combined. Another advantage of the longer harrowing tines is that the risk for residue build-up is decreased.

However, when the harrowing tines <NUM>, <NUM>, <NUM> are in the neutral position as can be seen in <FIG> and <FIG>, the lengths of the harrowing tines <NUM>, <NUM> and <NUM> are long enough that the ground engageable ends <NUM> and <NUM> of the harrowing tines <NUM>, <NUM> and <NUM> are more distant from the carrier <NUM> than the blades <NUM> and <NUM> of the corresponding weeding knives <NUM> and <NUM> with which the harrowing tines <NUM>, <NUM>, <NUM> are connected.

As can be seen in <FIG>, the number of harrowing tines of each working lever 15a, 15b can be varied. For example, the working lever 15b can be equipped with three (or more) harrowing tines <NUM>.

As can be seen in <FIG>, the harrowing tines <NUM>, <NUM> can be driven by an actuating element <NUM> other than the torsion spring designed first or second actuating element <NUM>, <NUM>, <NUM>, <NUM>. For example, the torsion springs of the working levers 15a, 15b are replaced by an actuating element <NUM> designed as an electric motor for rotating the harrowing tines <NUM>, <NUM> about their corresponding pivot axes <NUM> and <NUM>. The actuating element <NUM> may drive the arm <NUM>, <NUM> and may be controlled by the control unit <NUM>.

<FIG> shows the right working lever 15b and the carrier <NUM> of the weeding unit in a side view. It is apparent that the pivot axis <NUM> of the right working lever 15b is parallel to the pivot axis <NUM> of the harrowing tines <NUM>. Analogously, the pivot axis <NUM> of the left working lever 15a is parallel to the pivot axis <NUM> of the harrowing tines <NUM>.

The ground engageable end <NUM> of the harrowing tine <NUM> is in contact with the agricultural field <NUM> for harrowing the agricultural field <NUM>. The harrowing tine <NUM> is inclined wherein the inclination is defined by the inclination angle <NUM>. The inclination angle <NUM> is adjustable by an adjuster <NUM> of the right working lever 15b and may be increased or decreased to adapt the time when the weeds <NUM> or residue will be released. The more the inclination angle <NUM> is increased the earlier the weeds <NUM> or residue will be released.

<FIG> shows the control unit <NUM> comprising an interface <NUM>, a controller <NUM> and a memory <NUM>. The control unit <NUM> may receive and send signals or data via the interface <NUM>. The interface <NUM> may be a wireless interface or a connector. The controller <NUM> may store the data or signals received by the control unit <NUM> in the memory <NUM>. The memory <NUM> may contain additional data or executable programs, for example in terms of a computer-implemented method, that may be retrieved, processed or carried out by the controller <NUM>. Data or signals resulting from the processing of data or signals or from the execution of a program may be stored to the memory <NUM> or sent to the interface <NUM> by the controller <NUM>. Each weeding unit 4a and 4b may comprise an equivalent control unit <NUM>.

<FIG> shows a method for weeding and harrowing the agricultural field <NUM> for each weeding unit 4a and 4b when the agricultural vehicle <NUM> traverses the agricultural field <NUM>. The method is stored in the memory <NUM> of the control unit <NUM> of each weeding unit 4a and 4b and may be designed as a computer-implemented method. Each weeding unit 4a and 4b may carry out the method separately. For easier understanding the method will be explained by way of example of weeding unit 4a in the following description.

The method starts with step S100 and proceeds to step S101 for capturing images of the crop row 6b with which the weeding unit 4a is aligned while the agricultural vehicle <NUM> traverses the agricultural field <NUM> along the driving direction <NUM>. The images of the crop row 6b are captured continuously by the camera <NUM> and received by the control unit <NUM>. The controller <NUM> processes the images for detecting a crop <NUM> (see <FIG>).

The method proceeds to step S102 and the control unit <NUM> determines whether crop <NUM> is detected. As long as an absence of crop <NUM>, i. no crop <NUM>, is detected the left and right working levers 15a and 15b of the weeding unit 4a are hold in the closed position (see <FIG>). If the control unit <NUM> detects crop <NUM> (see <FIG>) the method proceeds to step S103.

At step S103, the control unit <NUM> controls the left and right actuator <NUM> and <NUM> to move the left and right working lever 15a and 15b into the opened position (see <FIG>). Thus, the blades <NUM> and <NUM> of the weeding knives <NUM> and <NUM> are brought out of the crop row 6b and a damage of the crop <NUM> is avoided.

Since the treating of the agricultural field <NUM> by the ground engageable ends <NUM> and <NUM> of the harrowing tines <NUM> and <NUM> causes a friction the harrowing tines <NUM> and <NUM> do not synchronously rotate with their corresponding weeding knives <NUM> and <NUM> but remain for a short delay in their position. while the weeding knives <NUM> and <NUM> are opened the friction created by the harrowing tines <NUM> and <NUM> in the agricultural field <NUM> keeps the harrowing tines <NUM> and <NUM> temporarily in place. Thus, the harrowing tines <NUM> and <NUM> are deflected in the second deflected position in relation to their corresponding weeding knives <NUM> and <NUM>. Due to this deflection the first actuating elements <NUM> and <NUM> (torsion springs) are tensioned (see <FIG>).

Then, the method proceeds to step S104 for moving the harrowing tines <NUM> and <NUM> to the neutral position for preventing of treating the crop <NUM> (see <FIG>). The increased tension of the first actuating elements <NUM> and <NUM> forces the harrowing tines <NUM> and <NUM> out of the crop row 6b. , the first actuating elements <NUM> and <NUM> urge the harrowing tines <NUM> and <NUM> to rotate in the same direction as the weeding knives <NUM> and <NUM> rotated into the opened position until an equilibrium of forces of the first and second actuating elements <NUM>, <NUM> and <NUM>, <NUM> acting on the arms <NUM> and <NUM> is reached again. Then, the harrowing tines <NUM> and <NUM> are positioned in the neutral position in relation to the weeding knives <NUM> and <NUM> as shown in <FIG>.

The agricultural vehicle <NUM> drives continuously in the driving direction <NUM> and the weeding knives <NUM> and <NUM> will pass the crop <NUM>. The controller <NUM> may process the captured images of the camera <NUM> and the control unit <NUM> may detect that the weeding knives <NUM> and <NUM> have passed the crop <NUM>. If no further crop <NUM> is detected the method proceeds to step S105.

At step S105, the control unit <NUM> controls the left and right actuator <NUM> and <NUM> to move the left and right working lever 15a and 15b into the closed position (see <FIG>). Thus, the blades <NUM> and <NUM> of the weeding knives <NUM> and <NUM> are brought back to the crop row 6b for treating the crop row 6b and weeding weed <NUM> growing along the crop row 6b.

Again, since the treating of the agricultural field <NUM> by the ground engageable ends <NUM> and <NUM> of the harrowing tines <NUM> and <NUM> causes a friction the harrowing tines <NUM> and <NUM> do not synchronously rotate with their corresponding weeding knives <NUM> and <NUM> but remain for a short delay in their position. while the weeding knives <NUM> and <NUM> are closed the friction created by the harrowing tines <NUM> and <NUM> in the agricultural field <NUM> keeps the harrowing tines <NUM> and <NUM> temporarily in place. Thus, the harrowing tines <NUM> and <NUM> are deflected in the first deflected position in relation to their corresponding weeding knives <NUM> and <NUM>. Due to this deflection the second actuating elements <NUM> and <NUM> (torsion springs) are tensioned (see <FIG>).

Then, the method proceeds to step S106 for moving the harrowing tines <NUM> and <NUM> to the neutral position for additional treating of the crop row 6b (see <FIG>). While the weeding knives <NUM> and <NUM> have started to move to the closed position, the harrowing tines <NUM> and <NUM> follow to move after a short delay. The increased tension of the second actuating elements <NUM> and <NUM> forces the harrowing tines <NUM> and <NUM> back to the crop row 6b. , the second actuating elements <NUM> and <NUM> urge the harrowing tines <NUM> and <NUM> to rotate in the same direction as the weeding knives <NUM> and <NUM> rotated into the closed position until an equilibrium of forces of the first and second actuating elements <NUM>, <NUM> and <NUM>, <NUM> acting on the arms <NUM> and <NUM> is reached again. Then, the harrowing tines <NUM> and <NUM> are positioned in the neutral position in relation to the weeding knives <NUM> and <NUM> and abut against the end stops <NUM> and <NUM> as shown in <FIG>.

As explained above, the positioning of the harrowing tines <NUM> and <NUM> is slightly delayed with respect of the opening movement as well as of the closing movement of the weeding knives <NUM> and <NUM>. By adjusting the actuation forces of the first and second actuating elements <NUM>, <NUM> and <NUM>, <NUM> of the harrowing tines <NUM> and <NUM> of each working lever 15a and 15b by their corresponding adjustment devices <NUM>, <NUM> and <NUM>, <NUM> the delay of the movement of the harrowing tines <NUM> and <NUM> into the neutral position can be adjusted. Preferably, the actuation forces of the second actuating elements <NUM> and <NUM> are set slightly more than actuation forces of the first actuating elements <NUM> and <NUM> since the movement of the harrowing tines <NUM> and <NUM> caused by the second actuating elements <NUM> and <NUM> enduring more friction from the forward moving motion.

If the weeding unit 4a is equipped with a controllable actuating element <NUM> such as an electric motor for controlling the movement of the harrowing tines <NUM> and <NUM> (see <FIG>) the delay of the movement of the harrowing tines <NUM> and <NUM> into the neutral position is adjustable. For example, the delay can be compensated completely so that the harrowing tines <NUM> and <NUM> move synchronously with their corresponding weeding knives <NUM> and <NUM>.

The adjustment of the delayed movement of the harrowing tines <NUM> and <NUM> can be based on a time delay or on a travel distance of the weeding unit 4a.

The method steps back to step S102. After the left and right working levers 15a and 15b have been moved into the closed position (see <FIG>, <FIG>) the working levers 15a and 15b remain in the closed position as long as an absence of crop <NUM>, i. no crop <NUM>, is determined by the control unit <NUM>.

As can be seen in <FIG>, the weeding unit 4a moves in driving direction <NUM> towards weed <NUM>. The control unit <NUM> distinguishes the weed <NUM> from crop <NUM> and detects an absence of crop <NUM> at step S102. Thus, the method proceeds to step S107 for cutting the weed <NUM>. The control unit <NUM> controls the actuators <NUM> and <NUM> to hold the working levers 15a and 15b in the closed position (see <FIG>, <FIG>) for weeding the crop row 6b of the agricultural field <NUM> with the blades <NUM> and <NUM> of the weeding knives <NUM> and <NUM>. The weeding blades <NUM> and <NUM> cut the soil of the agricultural field <NUM>.

As shown in <FIG>, when the blades <NUM> and <NUM> get in contact with the weed <NUM> the blades <NUM> and <NUM> cut the weed <NUM> and its roots <NUM>.

The weeding unit 4a moves further in the driving direction <NUM> while the weed <NUM> and its roots <NUM> remains on the agricultural field <NUM> (see <FIG>). Weed <NUM> may be loosened in the soil of the agricultural field <NUM> and roots <NUM> may still be covered in a soil lump.

Then, the method proceeds to step S108 for harrowing the crop row 6b. While the weeding unit 4a is still moving in the driving direction <NUM> the ground engageable ends <NUM> and <NUM> of the harrowing tines <NUM> and <NUM> get in contact with the weed <NUM> and its roots <NUM> (see <FIG>). Since the harrowing tines <NUM> and <NUM> are urged by the first actuating elements <NUM> and <NUM> and the second actuating elements <NUM> and <NUM> into the neutral position (see <FIG>) the harrowing tines <NUM> and <NUM> pick up the weed <NUM> and its roots <NUM> cut by the blades <NUM> and <NUM> of the weeding knives <NUM> and <NUM>. So, the harrowing tines <NUM> and <NUM> may catch on to leaves or part of the root <NUM> or displace the weed <NUM> in its entirely which results in a disruption of the root <NUM>.

The method proceeds to step S109 for separating the roots <NUM> of a weed <NUM> from soil of the agricultural field <NUM> with the harrowing tines <NUM> and <NUM>. The weeding unit 4a is still moving in the driving direction <NUM> so that the harrowing tines <NUM> and <NUM> drag the weed <NUM> forward to further separate the roots <NUM> of the weed <NUM> from soil (lump). The weed <NUM> may also be hurled out of the crop row when the harrowing tines <NUM> and <NUM> move away from the crop <NUM>, for example from the second deflected position (as can be seen in <FIG>) to the neutral position (as can be seen in <FIG>). Finally, weed <NUM> lays on top of the agricultural field <NUM> without soil attached to the roots <NUM>.

Then, the method proceeds to step S110 and ends. The method may restart with step S100 again.

<FIG> and <FIG> show each a right part of the weeding units 4a comprising the right working lever 15b. Nevertheless, the foregoing description with respect to these figures is also analogously applicable to the left part of the weeding unit 4a comprising the left working lever 15a.

Claim 1:
A weeding unit (4a, 4b) for treating an agricultural field (<NUM>), comprising:
a carrier (<NUM>);
at least one working lever (15a, 15b) moveably connected with the carrier (<NUM>);
at least one actuator (<NUM>, <NUM>) for moving the at least one working lever (15a, 15b); and
a control unit (<NUM>) configured
to distinguish crop (<NUM>) from weed (<NUM>); and
to control the at least one actuator (<NUM>, <NUM>) for treating the weed (<NUM>);
wherein the at least one working lever (15a, 15b) comprises
a weeding knife (<NUM>, <NUM>); characterized in that the at least one working lever further comprises
at least one harrowing tine (<NUM>, <NUM>).