A hoe attachment, a hoe tool, a hoe and harrow tool, an agricultural device, and a method for using an agricultural device

BACKGROUND OF THE INVENTION

The invention relates to the cultivation of crops which requires a lot of different operations, including but not limited to tillage, which is the agricultural preparation of soil by mechanical agitation, e.g. using digging, stirring and overturning.

Tillage that is deeper and more thorough resulting in soil with a rough texture is classified as primary, while tillage that is shallower to produce finer soil and is sometimes more selective, e.g. of location, is classified as secondary. Weed control throughout the growing season during the maturation of the crop plants falls under secondary tillage. Such shallow, selective secondary tillage of row crop fields that kills weeds while sparing the crop plants may alternatively be referred to as cultivating or cultivation.

Although tillage can be done by hand, tilling is typically carried out with draft-animal- powered or mechanized work in which an agricultural device including harrows, hoes, or other tools is drawn over a field to carry out primary and/or secondary tillage.

Hence, tillage can be done non-selective, usually prior to seeding or planting requiring agricultural devices which evenly work the soil of a field, alternatively referred to as full- field agricultural preparation, and can be done selective, usually after seeding or planting during maturation of the crop plants in which care should be taken to spare the crop plants. It is for instance known to sow seeds or plant crops in rows and during the maturation of the crop plants only use hoes for weed control in between the rows.

Depending on the type of crop grown, the distance between rows of crops is not necessarily always the same, so that the agricultural device needs to be able to handle different distances. German patent publication DE20115048U1 discloses an exemplary prior art agricultural device. The device includes a plurality of harrow tines that are arranged in an array to allow non-selective harrowing of the soil when all harrow tines are in the active position. However, harrow tines can also be brought to an inactive position allowing selective harrowing of the soil.

European patent publication EP3146820A1 discloses another exemplary prior art agricultural device in which different tillage operations may be combined. The device includes a front section with a plurality of hoes and a rear section with a plurality of harrow tines to carry out both primary tillage and secondary tillage simultaneously.

The hoes of EP3146820A1 may be exchangeable, allowing to replace worn hoes with new hoes and/or to provide the agricultural device with different hoes. An example of such an exchangeable hoe can be found in German patent publication DE202020104979U1.

A disadvantage of the current prior art soil preparation methods is that either multiple operations have to be performed consecutively and/or the devices are so complex and heavy that there is a high risk of undesired soil compaction and/or damage to the maturing crops.

SUMMARY OF THE INVENTION

In view of the above, it is an object of the invention to provide an agricultural device for soil preparation that reduces the damage to the soil as well as the maturing crops.

According to a first aspect of the invention, there is provided an agricultural device comprising: a frame, and a plurality of harrow tines mounted to said frame, wherein the agricultural device further comprises a plurality of hoe attachments, and wherein each hoe attachment is configured to be selectively mounted to at least one of the plurality of harrow tines. The invention according to the first aspect of the invention is based on the insight that the use of hoe attachments that can selectively be mounted to or dismounted from respective harrow tines allows to easily change the local operation of the agricultural device from harrowing to hoeing or vice versa. Hence, with a single agricultural device it is possible to carry out full field harrowing when no hoe attachments are mounted to the harrow tines, or to carry out full field hoeing when hoe attachments are mounted to all harrow tines, or to carry out both hoeing and harrowing when hoe attachments are mounted to some harrow tines. The latter results in selective soil preparation, so that for instance the harrow tines without hoe attachment are used in a crop row for weed control without or with minimal damage to the maturing crops and the harrow tines with hoe attachment are used in between crop rows for heavier weed control, which is possible as the risk of crop damage in between the crop rows is minimal or absent.

The result is that either the number of operations on a field can be reduced and/or lighter devices can be used thereby reducing the damage to the soil, e.g. reducing soil compaction, and/or reducing the damage to the crops.

Additional advantages may be that:

- energy and/or time and/or resources can be saved as less operations are required,

- different operations can be performed with the same agricultural device, so that less investments are required to obtain or use different agricultural devices,

- the agricultural device itself can be made simple and thus available all around the world for various situations and conditions.

In an embodiment, each hoe attachment is configured to be mounted to a free end of at least one of the plurality of harrow tines.

In an embodiment, each hoe attachment comprises a hoeing part for cutting weeds and a mounting part for mounting the hoe attachment to a harrow tine, and wherein the mounting part comprises a portion to be positioned around a harrow tine to prevent relative motion between hoe attachment and harrow tine in a plane that is perpendicular to the harrow tine. In an embodiment, the mounting part of each hoe attachment further includes a retainer device to prevent any relative motion between hoe attachment and harrow tine.

In an embodiment, each harrow tine is pivotably connected to the frame to pivot about a respective pivot axis, wherein the agricultural device further comprises a corresponding plurality of springs connected to the harrow tines at a distance from the respective pivot axes of the harrow tines to pretension the plurality of harrow tines.

In an embodiment, the agricultural device further comprises an adjusting device to centrally adjust the pretension of the plurality of springs.

In an embodiment, the adjusting device is a first adjusting device and the agricultural device further comprises a second adjusting device to centrally adjust the pretension of the plurality of springs, wherein at least some of the plurality of springs can be selectively connected to the first adjusting device or the second adjusting device allowing to adjust the pretension of a first subset of the plurality of springs to a first value and to adjust the pretension of a second subset (different from the first subset) of the plurality of springs to a second value, wherein the first value can be different from the second value.

In an embodiment, one or more harrow tines are moveable to a non-operational position in which they are not able to engage with the soil. Selectively activating or deactivating a harrow tine provides additional possibilities to optimize the soil preparation with a minimum of tools and devices.

The first aspect of the invention also relates to a method for using an agricultural device according to the first aspect of the invention, said method comprising the following steps: a. mounting one or more hoe attachments to corresponding harrow tines of the plurality of harrow tines, and b. moving the agricultural tool over a piece of land. In an embodiment, the piece of land includes multiple rows of crops, and wherein step a. is carried out such that during step b. harrow tines without respective hoe attachments operate in at least one row of crops and harrow tines with respective hoe attachments operate outside the rows of crops. Preferably, harrow tines with respective hoe attachments do not operate in the at least one row of crops. It is possible that some harrow tines without respective hoe attachments also operate outside the rows of crops.

In an embodiment, the agricultural device further comprises a first adjusting device to centrally adjust the pretension of the plurality of springs, and a second adjusting device to centrally adjust the pretension of the plurality of springs, wherein at least some of the plurality of springs can be selectively connected to the first adjusting device or the second adjusting device allowing to adjust the pretension of a first subset of the plurality of springs to a first value and to adjust the pretension of a second subset (different from the first subset) of the plurality of springs to a second value, wherein the first value can be different from the second value, and wherein the method comprises the following step of connecting the springs associated with harrow tines with hoe attachments to the second adjusting device, and preferably adjusting the first and/or second adjusting device such that the second value is larger than the first value.

In an embodiment, the harrow tines are moveable between an operational position to work the soil and a non-operational position, wherein the method further comprises the step of moving harrow tines from the operational position to the non-operational position and/or from the non-operational position to the operational position.

The first aspect of the invention further relates to a hoe attachment comprising: a hoeing part for cutting weeds, and a mounting part, wherein the mounting part comprises a portion to be positioned around a harrow tine to prevent relative motion between hoe attachment and harrow tine in a plane that is perpendicular to the harrow tine and a retaining device to prevent motion in longitudinal direction of the harrow tine. In an embodiment, the portion of the mounting part to be positioned around a harrow tine includes a hole, space, cavity or recess to receive a free end of the respective harrow tine.

In an embodiment, the orientation of the mounting part relative to the hoeing part is adjustable. This allows the hoeing part to be optimized for different orientations of the harrow tine.

In an embodiment, the retaining device is configured to clamp the mounting part to the harrow tine.

In an embodiment, the hoeing part is perpendicular to the mounting part, i.e. the longitudinal axis of the harrow tine when the hoe attachment is mounted to the harrow tine. This makes the hoe attachment suitable for vertically oriented harrow tines. Alternatively, the hoeing part may be at an angle, preferably an acute angle, relative to the mounting part. This makes the hoe attachment suitable for harrow tines that extend obliquely rearwards.

According to a second aspect of the invention, there is provided an agricultural device comprising: a frame, and a plurality of hoes connected to the frame via corresponding arms, wherein each arm is pivotably connected to the frame to pivot about a corresponding pivot axis, wherein the agricultural device further comprises a set of springs connected to the respective arms of the plurality of hoes at a distance from the respective pivot axes to pretension the respective arms of the plurality of hoes, and wherein the agricultural device comprises an adjusting device to centrally adjust the pretension of the set of springs.

The invention according to the second aspect of the invention is based on the insight that a centrally adjustable pretension of the set of springs allows to optimize the hoeing operation by the plurality of hoes to the properties of the soil and the required soil preparation. When the hoeing operation is optimized, hoeing or other operations can be done less frequently to accomplish the same result.

The result is that either the number of operations on a field can be reduced and/or the same result can be obtained using lighter agricultural devices thereby reducing the damage to the soil, e.g. reduce soil compaction and/or reduce the damage to the crops.

Additional advantages may be that:

- energy and/or time and/or resources can be saved as less operations are required,

- different operations can be performed with the same agricultural device, so that less investments are required to obtain or use different agricultural devices,

- the agricultural device itself can be made simple and thus available all around the world for various situations and conditions.

In an embodiment, the agricultural device further comprises a plurality of harrow tines connected to the frame via corresponding arms, wherein each arm associated with the harrow tine is pivotably connected to the frame to pivot about a corresponding pivot axis, and wherein the set of springs includes a plurality of springs connected to the arms associated with the plurality of harrow tines at a distance from the corresponding pivot axes. And advantage of this embodiment is that both the pretension of the hoes and the harrow tines can be adjusted centrally.

In an embodiment, the adjusting device is a first adjusting device and the agricultural device further comprises a second adjusting device to centrally adjust the pretension of a plurality of springs, wherein a plurality of springs connected to the arms associated with the plurality of hoes are connected to the first adjusting device, and wherein the plurality of springs connected to the arms associated with the plurality of harrow tines are connected to the second adjusting device. This allowing to adjust the pretension of a first subset of the set of springs associated with the hoeing operation to a first value and to adjust the pretension of a second subset (different from the first subset) of the set of springs associated with the harrowing operation to a second value, wherein the first value can be different from the second value.

In an embodiment, the agricultural device includes a harrow tine with associated arm configured such that it can replace a hoe with associated arm. This allows to switch from a hoe operation at a certain location to a harrow operation. The same may be obtained by having both a harrow tine with associated arm and a hoe with associated arm being provided for a certain location with the ability to activate/deactivate the tools.

In an embodiment, the agricultural device includes a hoe with associated arm configured such that it can replace a harrow tine with associated arm. This allows to switch from a harrow operation at a certain location to a hoe operation. The same may be obtained by having both a harrow tine with associated arm and a hoe with associated arm being provided for a certain location with the ability to activate/deactivate the tools.

In an embodiment, the harrow tines with associated arms and the hoes with associated arms may be interchangeable, so that at each mounting location on the frame, a user can make a choice for a harrow operation or a hoe operation by connecting the corresponding tool to the frame.

In an embodiment, the agricultural device further comprises a plurality of harrow tines connected to the frame via corresponding arms, wherein each arm associated with the harrow tine is pivotably connected to the frame to pivot about a corresponding pivot axis, wherein the set of springs includes a plurality of springs connected to the arms associated with the plurality of harrow tines at a distance from the corresponding pivot axes to pretension the plurality of arms associated with the plurality of harrow tines, wherein at least one harrow tine overlaps with a hoe and said at least one harrow tine and the corresponding overlapping hoe are moveable between an operational position and a non- operational position. The second aspect of the invention also relates to a method for using an agricultural device according to the second aspect of the invention, said method comprising the following steps: a. centrally adjusting the pretension applied by the set of spring, and b. moving the agricultural device over a piece of land.

In an embodiment, the method further comprising the step of replacing a hoe with associated arm by a harrow tine with associated arm.

In an embodiment, the agricultural device further comprises a plurality of harrow tines connected to the frame via corresponding arms, wherein each arm associated with the harrow tine is pivotably connected to the frame to pivot about a corresponding pivot axis, wherein the set of springs includes a plurality of springs connected to the arms associated with the plurality of harrow tines at a distance from the corresponding pivot axes to pretension the plurality of arms associated with the plurality of harrow tines, wherein the piece of land includes multiple rows of crops, and wherein the harrow tines and hoes are arranged such that during step b. the harrow tines operate in at least one row of crops and the hoes operate outside the rows of crops.

In an embodiment, the agricultural device further comprises a plurality of harrow tines connected to the frame via corresponding arms, wherein each arm associated with the harrow tine is pivotably connected to the frame to pivot about a corresponding pivot axis, wherein the set of springs includes a plurality of springs connected to the arms associated with the plurality of harrow tines at a distance from the corresponding pivot axes to pretension the plurality of arms associated with the plurality of harrow tines, and wherein the method comprises the step of replacing a harrow tine with associated arm by a hoe with associated arm.

In an embodiment, the agricultural device further comprises a plurality of harrow tines connected to the frame via corresponding arms, wherein each arm associated with the harrow tine is pivotably connected to the frame to pivot about a corresponding pivot axis, wherein the set of springs includes a plurality of springs connected to the arms associated with the plurality of harrow tines at a distance from the corresponding pivot axes to pretension the plurality of arms associated with the plurality of harrow tines, wherein at least one harrow tine overlaps with a hoe and said at least one harrow tine and the corresponding overlapping hoe are moveable between an operational position and a non- operational position, and wherein the method comprises the step of activating a harrow tine or hoe by moving said harrow tine or hoe to the operational position and/or the step of deactivating a harrow tine or hoe by moving said harrow tine or hoe to the non- operational position. Preferably, when one of an overlapping harrow tine or hoe is activated the other one is deactivated.

The second aspect of the invention also relates to a hoe tool comprising: a hoe, and an arm attached to the hoe, wherein the arm defines a pivot axis to pivotably connect the hoe tool to a frame, and wherein the arm further includes an attachment location for a spring at a distance from the pivot axis.

In an embodiment, the hoe is releasably attached to the arm.

The second aspect of the invention yet also relates to a hoe and harrow tool comprising: an arm, a hoe releasably attachable to the arm, and a harrow tine releasably attachable to the arm, wherein the arm defines a pivot axis to pivotably connect the hoe tool to a frame, and wherein the arm further includes an attachment location for a spring at a distance from the pivot axis.

It is explicitly noted here that various embodiments and features described in relation to one aspect of the invention may be combined with other embodiments and features of the same aspect of the invention and/or with embodiments and features of the other aspect of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in a non-limiting way by reference to the accompanying drawings in which like parts are indicated by like reference symbols, and in which:

Fig. 1 schematically depicts a top view of a piece of land being worked with an agricultural device according to an embodiment of the invention,

Fig. 2A schematically depicts a front view of an agricultural device according to an embodiment of the invention,

Fig. 2B schematically depicts a side view of the agricultural device of Fig. 2A,

Fig. 3A schematically depicts a side view of a harrow tine including hoe attachment attached to a free end of the harrow tine according to an embodiment of the invention,

Fig. 3B schematically depicts a perspective view of the harrow tine of Fig. 3A without hoe attachment,

Fig. 3C schematically depicts a perspective view of the hoe attachment of Fig. 3A,

Fig. 4A schematically depicts a hoe tool for use with an agricultural device according to the second aspect of the invention,

Fig. 4B schematically depicts a harrow tool to be exchanged with the hoe tool of

Fig. 4A,

Fig. 5 schematically depicts a side view of a harrow tine including hoe attachment according to another embodiment of the invention,

Fig. 6 schematically depicts a side view of a harrow tine including hoe attachment attached to a free end of the harrow tine according to further embodiment of the invention,

Fig. 7A schematically depicts a cross-sectional view of a mounting part of a hoe attachment of Fig. 3A and Fig. 6,

Fig. 7B schematically depicts a cross-sectional view of a mounting part of a hoe attachment according to another embodiment of the invention, and Fig. 7C schematically depicts a cross-sectional view of a mounting part of a hoe attachment according to yet another embodiment of the invention. DETAILED DESCRIPTION OF THE INVENTION

Fig. 1 schematically depicts a piece of land 1 used for the cultivation of crops. The piece of land 1 is shown after row-wise seeding or planting resulting in rows of crops 2 interspersed with empty strips of land 3.

Usually, the piece of land is worked before the seeding/planting and/or during seeding/planting and/or after seeding/planting. Fig. 1 depicts a situation in which the piece of land 1 is worked using an agricultural device 10 after seeding/planting, e.g. for weed control.

In the situation depicted in Fig. 1, the agricultural device 10 is moved over the piece of land using a vehicle 5, e.g. a tractor, robot or dedicated vehicle. Both the agricultural device 10 and the vehicle 5 are depicted highly schematically and are transparent to clearly show the row of crops 2 and the strips of land 3 below the agricultural device 10 and the vehicle 5. The agricultural device 10 may include one or more wheels (not shown in Fig. 1) to provide at least partial self-support allowing the vehicle 5 to pull or push the agricultural device 10 over the piece of land 1 or the agricultural device 10 may entirely be supported by the vehicle 5, e.g. by being mounted to or being integral with the vehicle 5, to be moved over the piece of land 1 along with the vehicle 5.

Figs. 2A and 2B schematically depicts an agricultural device according to an embodiment of the invention, which is suitable to be used as agricultural device 10 in the embodiment of Fig. 1. Fig 2A schematically depicts a front view and Fig. 2B schematically depicts a side view.

The agricultural device 10 comprises a frame 11 and a plurality of arms 20 mounted to said frame 10. Each arm 20 is pivotably connected to the frame to pivot about a corresponding pivot axis 21. The agricultural device 10 further comprises a set of springs 22 connected to respective arms 20 at a distance from the respective pivot axes 22 to pretension the respective arms 20. IB

The agricultural device 10 further comprises an adjusting device to centrally adjust the pretension of the set of springs 22. In this embodiment, the adjusting device includes a roll 30 and cables 31 connected between the roll 30 and the respective springs 22. The roll 30 can be driven to haul in the cables 31 to simultaneously increase the pretension of the connected springs 22 or to pay out the cables 31 to simultaneously decrease the pretension of the connected springs 22.

As shown in Fig. 2A, the frame 11 may include frame portions 11a, lib pivotably connected to a main frame portion in between the two frame portions 11a, lib using hinges 12. The hinges 12 define corresponding horizontal pivot axes 12a allowing the frame portions 11a, lib to pivot upwards indicated by respective arrows R to a non- operational position in which the width of the agricultural device 10 is significantly decreased compared to the operational situation depicted in Fig. 2A. Reducing the width of the agricultural device 10 may be beneficial for transportation purposes or when an edge of a piece of land is reached and only a part of the agricultural device is able to work the soil.

The agricultural device 10 in this embodiment includes at least two wheels 13 supporting the frame 11 from the ground and a mounting device 14 to connect the agricultural device 10 to a vehicle as for instance depicted in Fig. 1. The position or orientation of the two wheels 13 relative to the frame 11 is preferably adjustable, so that the height H of the frame 11 above the ground is adjustable. The mounting device 14 may also be adjustable to adjust the orientation or position of the frame to the position or orientation of the wheels 13. Alternatively, the vehicle itself mounted to the mounting device 14 provides for height adjustment of the frame 11 above the ground.

It is to be noted here explicitly that the plurality of arms 20 are depicted in a raised position above the ground to clearly indicate tool members 23 connected to the arms 20. In practice, gravity and pretension by the springs 22 will urge the arms and tool members 23 to a position in which the tool members 23 engage with the ground or are oriented downwards. The tool members 23 may include a hoe and/or harrow tine according to various configurations of the invention as described below in more detail.

According to a first configuration, which is depicted in more detail in Figs. 3A, 3B and 3C, the tool member 23 comprises a harrow tine 24 and an optional hoe attachment 25 configured to be selectively mounted to the harrow tine 24, in this case a free end 24a of the harrow tine 24. An end 24b opposite the free end 24a of the harrow tine 24 is mounted to or integral with a respective arm 20.

In this example, the free end 24a of the harrow tine 24 has a cylindrical shape with outer diameter dl. It is envisaged that the free end 24a of the harrow tine 24 has other shapes as well.

The hoe attachment 25 in this example has a hoeing part 25a for cutting weeds and a mounting part 25b for mounting the hoe attachment 25 to a harrow tine 24. The mounting part 25b comprises a hole, cavity, recess or bore 25c to receive the free end 24a of a harrow tine, such that at least a portion of the mounting part can be positioned around a harrow tine to prevent relative motion between hoe attachment and harrow tine in a plane that is perpendicular to the harrow tine. When a Z-direction is oriented parallel to a longitudinal axis 24c of a harrow tine, the aforementioned plane is parallel to the X-Y plane.

The harrow tine 24 may have a diameter dl while the hole, cavity, recess or bore 25c may define a diameter d2. Preferably, d2 is equal to or larger than dl, preferably with sufficient play to allow easy assembly, which play is preferably limited to minimize the movement of the hoe attachment relative to the harrow tine.

The mounting part 25b further includes a threaded bore 25d extending from an opening in an outer face of the mounting part 25b to the hole 25c. The threaded bore 25d is configured to receive a retainer device 26 which has a threaded portion to mate with the threaded bore 25d. Without the retainer device 26, the hoe attachment 25 is able to translate in a direction parallel to the longitudinal axis 24c of the respective harrow tine 24, i.e. the Z-direction, and is able to rotate about an axis extending parallel to the longitudinal axis 24c of the respective harrow tine. By introducing the retainer device 26 into the bore 25d until the retainer device 26 engages with the free end 24a of the harrow tine 24, the hoe attachment 25 can be clamped on the harrow tine 24 to prevent any relative motion between mounting part and thus hoe attachment and harrow tine.

As the hoe attachment 25 can be selectively mounted to a harrow tine 24, a user/operator has the ability to select a tool member 23 to function as a harrow tine (by removing a hoe attachment from or by not mounting a hoe attachment to the harrow tine), or to select a tool member 23 to function as a hoe (by leaving a hoe attachment on or by mounting a hoe attachment on the harrow tine). This selection is possible for each tool member 23. For this reason, the tool members 23 in Fig. 2A and 2B are provided with dashed lines at their free ends representative for the optional hoeing part.

Hence, in this first configuration, a user/operator may use the agricultural device 10 for full-field hoeing by using all available tool members as hoe, for full-field harrowing by using all available tool members as harrow, and for location-selective simultaneous harrowing and hoeing by using some available tool members as harrow and other available tool members as hoe. The latter use may for instance be used on the piece of land depicted in Fig. 1, wherein tool members 23 arranged in the rows of crops 2 are used as harrow and the tool members 23 arranged in the strips of land 3 are used as hoe. It is envisaged that some tool members 23 arranged in the strips of land 3 are used as harrow, for instance to provide both functions in the strips of land 3, e.g. to allow the tool members that are used as harrow to be a pre-operation of the soil for the tool members used as hoe in the strips of land 3.

In the first configuration, the agricultural device 10 is a device according to the first aspect of the invention. When some of the tool members 23 are used as hoe, the agricultural device 10 is also a device according to the second aspect of the invention.

According to a second configuration, which is depicted in Figs. 4A and 4B, at least some of the tool members 23 and respective arms 20 are embodied as a hoe tool, e.g. as a hoe tool 27 depicted in Fig. 4A. Although not necessary, some of the tool members 23 and respective arms 20 are embodied as a harrow tool, e.g. as a harrow tool 28 depicted in Fig. 4B, wherein the hoe tool 27 and the harrow tool 28 are configured to be exchangeable.

The hoe tool 27 of Fig. 4A comprises an arm 20 and a hoe 25' attached to the arm 20. The arm 20 includes an axle portion 20a defining a pivot axis 21 to pivotably connect the hoe tool 27 to a frame, e.g. the frame 11 of Figs. 2A and 2B. The arm 20 further includes an attachment location 20b for a spring, e.g. the spring 22 of Figs. 2A and 2B, which attachment location 20b is arranged at a distance from the pivot axis 21 allowing the spring 22 to apply a moment to the arm 20 when tensioned. The main difference between the first configuration and the second configuration is that the hoe 25' is fixed to the arm 20 and cannot be removed or when removed results in an arm 20 without tool member thereto, where in the first configuration removal of the hoe attachment resulted in the tool member being usable as a harrow. In order to allow an agricultural device in the second configuration to have the same functionality as an agricultural device in the first configuration, the hoe tool 27 or at least the hoe 25' and a portion of the arm 20 are exchangeable.

Fig. 4B depicts a harrow tool 28 with an arm 20 and a harrow tine 24' attached to the arm 20. Similar to the hoe tool 27, the harrow tool 28 includes an axle portion 20a defining a pivot axis 21 to pivotably connect the hoe tool 27 to a frame, e.g. the frame 11 of Figs. 2A and 2B. The arm 20 further includes an attachment location 20b for a spring, e.g. the spring 22 of Figs. 2A and 2B, which attachment location 20b is arranged at a distance from the pivot axis 21 allowing the spring 22 to apply a moment to the arm 20 when tensioned.

Hence, a user/operator using the agricultural device 20 of Figs. 2A and 2B has the possibility to use hoe tools 27 for full-field hoeing, to use harrow tools 28 for full-field harrowing and to use both the hoe tools 27 and the harrow tools 28 for simultaneous hoeing and harrowing, wherein it is possible to exchange a hoe tool for a harrow tool and vice versa. Instead of exchanging the entire hoe tool or harrow tool, it is also possible to exchange the harrow tine 24', possibly including a portion of the arm 20, with a hoe 25' including a portion of the arm 20 or to exchange the hoe 25' including a portion of the arm 20 with a harrow tine 24', possibly including a portion of the arm 20.

Optionally, the attachment location 20b in Fig. 4A and/or Fig. 4B may include a link 29 to limit movement of a spring connected to the attachment location 20b.

Fig. 5 schematically depicts a side view of a harrow tine 24 including hoe attachment 25 according to another embodiment of the invention. The harrow tine 24 has a free end 24a and an end 24b opposite thereof that is connected to an arm 20 via a curved shape so that a longitudinal axis 24c of the harrow tine 24 extends non-parallel, preferably perpendicular to a longitudinal axis 20c of the arm portion 20 connected to the end 24b of the harrow tine 24. In this sense, the harrow tine 24 and arm 20 are similar to the harrow tool 28 of Fig. 4B.

The hoe attachment 25 comprises a hoeing part 25a for cutting weeds and a mounting part 25b with a hole 25c so that a portion of the mounting part 25b can be positioned around the free end 24a of the harrow tine 24 to prevent motion in a plane perpendicular to the Z-direction similar to the hoe attachment of Fig. 3A and 3B.

The hoe attachment 25 further comprises a retainer device 26 which in this embodiment is an extension of the mounting part 25b and extends to above the arm 20. In this example, the retainer device 26 has two parallel plates 26a (of which only one is visible in Fig. 5) for receiving the end 24b, the curve and the arm 20 in between. A hole 26b is provided above the arm 20, so that when a bolt or pin or similar element is introduced through the holes 26b in both plates 26a, the hoe attachment 25 is prevented from falling off the harrow tine 24 while the plates engaging with the curve and the arm 20 prevent the hoe attachment from rotating about the harrow tine 24.

Fig. 6 schematically depicts a tool member 23 with a harrow tine 24 and an optional hoe attachment 25 configured to be selectively mounted to the harrow tine 24, in this case a free end 24a of the harrow tine 24. An end 24b opposite the free end 24a of the harrow tine 24 may be mounted to or integral with a respective arm 20 as for instance shown in Figs. 2A and 2B.

In this example, the free end 24a of the harrow tine 24 has a cylindrical shape with outer diameter dl. It is envisaged that the free end 24a of the harrow tine 24 has other shapes as well.

The hoe attachment 25 in this example has a hoeing part 25a for cutting weeds and a mounting part 25b for mounting the hoe attachment 25 to a harrow tine 24. The mounting part 25b comprises a hole, cavity, recess or bore 25c to receive the free end 24a of a harrow tine, such that at least a portion of the mounting part can be positioned around a harrow tine to prevent relative motion between hoe attachment and harrow tine in a plane that is perpendicular to the harrow tine. When a Z-direction is oriented parallel to a longitudinal axis 24c of a harrow tine, the aforementioned plane is parallel to the X-Y plane.

The mounting part 25b further includes a threaded bore 25d extending from an opening in an outer face of the mounting part 25b to the hole 25c. The threaded bore 25d is configured to receive a retainer device 26 which has a threaded portion to mate with the threaded bore 25d. Without the retainer device 26, the hoe attachment 25 is able to translate in a direction parallel to the longitudinal axis 24c of the respective harrow tine 24, i.e. the Z-direction, and is able to rotate about an axis extending parallel to the longitudinal axis 24c of the respective harrow tine. By introducing the retainer device 26 into the bore 25d until the retainer device 26 engages with the free end 24a of the harrow tine 24, the hoe attachment 25 can be clamped on the harrow tine 24 to prevent any relative motion between mounting part and thus hoe attachment and harrow tine.

A difference with the embodiment of Figs. BA and 3C is that the hoeing part in Figs. 3A and 3C extends in the X-Y plane while the hoeing part in Fig. 6 extends in X' direction making a non-zero angle a with the X-direction. This X' may in use be parallel to the horizontal direction, i.e. parallel to the ground. Fig. 7 A schematically a cross-sectional view of a mounting part 25b of a hoe attachment of Fig. BA and Fig. 6. The mounting part 25b has a cylindrical wall shaped to match the circular shape of the harrow tine 24. Hence, the mounting part 25b surrounds the harrow tine in this cross-section, but this is not necessary the case to allow the mounting part 25b to be positioned around a harrow tine to prevent relative motion between hoe attachment and harrow tine in a plane that is perpendicular to the harrow tine. Alternative embodiments are depicted in Fig. 7B, in which the mounting portion 25b includes three, in other embodiments, two, four or even more, segments distributed about the harrow tine 24, and in Fig. 7C in which a single segment spanning more than 180 degrees is positioned around the harrow tine 24.

Although the invention according to the first and second aspect allow for adding or removing a tool and/or replacing one tool for another tool, it is also envisaged that additionally or alternatively, tools can be activated and deactivated, for instance by moving a tool between an operational position and a non-operational position. It is even possible that for a single location two tools may be provided that can be activated or deactivated allowing to choose between different tools for said location.

Although the adjusting device has been described to centrally adjust the pretension of the set of springs, it is envisaged that the agricultural device includes two or more adjusting devices, each adjusting device being configured to centrally adjust the pretension of a subset of springs, wherein a subset of springs includes at least two springs. This may for instance be beneficial when a subset of springs is arranged in a frame portion that is moveable relative to a main frame portion to allow transportation of the agricultural device or to set a width of the agricultural device. One adjusting device may be provided on the main frame portion and another adjusting device may be provided on the moveable frame portion. Control of both adjusting devices may then be synchronized so that they operate as one and set an equal pretension of all springs simultaneously.

It is further envisaged that two or more adjusting devices are used in parallel, so that the pretension of a first subset of the set of springs associated with for instance the hoeing operation can be adjusted to a first value and the pretension of a second subset (different from the first subset) of the set of springs associated with for instance the harrowing operation can be adjusted to a second value, wherein the first value can be different from the second value allowing to set different pretensions to different operations.