WO2017013126A1

WO2017013126A1 - Method and defoliation machine for removing leaves from a stalk of a graminaceous plant

Info

Publication number: WO2017013126A1
Application number: PCT/EP2016/067202
Authority: WO
Inventors: Antonio Cesar Azenha; Cassio Da Silva Cardoso Teixeira; Rogerio de Oliveira BARRETO
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2015-07-20
Filing date: 2016-07-19
Publication date: 2017-01-26
Anticipated expiration: 2018-01-20

Abstract

The present invention relates to a method for removing leaves (2) from a stalk (1) of a graminaceous plant. The method comprises moving the stalk (1) essentially along its longitudinal axis. Furthermore, it comprises generating at least one air flow (5), which is directed onto the stalk (1) in a direction from the top of the stalk (1) and at an acute angle relative to the longitudinal axis of the stalk (1), thereby lifting off leaves (2) from the stalk (1). Finally the lifted leaves (2) are detached from the stalk (1). It also relates to a defoliation machine for removing leaves from a stalk (1) of a graminaceous plant.

Description

Method and defoliation machine for removing leaves from a stalk of a graminaceous plant

The present invention relates to a method and defoliation machine for removing leaves from a stalk of a graminaceous plant, in particular a sugarcane plant.

In the process of harvesting sugarcane from a field, separating the leaves from the stalks is an important step, since typically only the stalks are subsequently processed. Several approaches have been developed for removing the leaves of sugarcane stems: WO 2014/074077 A1 describes a sugarcane leaves remover apparatus, which removes the leaves from a sugarcane stalk without cutting it off. A set of rotary brushes shears off the leaves, as the apparatus moves over the field, treating one stalk after the other. A similar mechanism is used, for example, by the harvester described in WO 2012/010235 A1 , where brushes are used to remove the leaves from a sugarcane stalk.

The sugarcane leaf removal machine described in CN 203801298 U comprises two rollers with needles. The stalk is placed between the two parallel rollers and the leaves are scraped off and thereby removed from the stalk. Another principle for removing leaves from the stalk is burning the leaves on the field or, for instance, as described in WO 2014/191679 A1. Here, the sugarcane is fed into a furnace and the combustion and time of the sugarcane in the furnace is controlled to remove the leaves without damaging the core of the cane stems. Furthermore, the leaves can be cut off by knives, for example as described in

CN 201 1 54307 Y, where blades with a concave shape are held by a spring assembly to reduce damage to the stalk. Another assembly of blades to defoliate sugarcane stalks is described in CN 2010 1 1847 Y, where fixed and mobile blades surround a hole, through which the stalk can be moved to cut off the leaves.

Finally, the sugarcane harvester described in US 2004/0074217 A1 comprises a harvest chamber, into which the upright standing sugarcane plant is funneled, while the harvester is moving across the field. High velocity air streams are created within the chamber and remove leaves from the stalk, while the debris is removed from the chamber by a debris vacuum assembly.

The task of defoliating sugarcane stalks gets even more delicate when the stalk needs to be treated particularly carefully. This is especially the case when buds, which are often hidden below leaves, are to be extracted and used to grow new plants. In this case, the leaves need to be removed as carefully as possible to allow access to the buds without damaging the buds. On the other hand, the conditions of modern agriculture require highly efficient and largely automated processes. Thus, there is a necessity to provide a method that allows removing leaves from sugarcane stalks in a highly efficient and gentle manner.

This problem is solved according to the invention by a method according to claim 1 and a defoliation machine according to claim 12. Advantageous embodiments are given in the dependent claims.

The method according to the invention comprises moving the stalk essentially along its longitudinal axis. Furthermore, it comprises generating at least one air flow, which is directed onto the stalk in a direction from the top of the stalk and at an acute angle relative to the longitudinal axis of the stalk, thereby lifting off leaves from the stalk. Finally the lifted leaves are detached from the stalk.

This offers an advantageously gentle way of removing the leaves from the stalk by first lifting off the leaves from the stalk by an air flow and then detaching the leaves. Thereby it is made sure that, e.g., a mechanical device for removing the leaf can be operated at a safe distance from the bud, such that the more sensitive parts of the plants, in particular the buds, are not harmed. Leaves in the sense of the invention can be all parts of the sugarcane plant other than the stalks and buds. The invention is also not limited to environmental air, but can use any gaseous compound available. In particular, this method is advantageous in cases where the leaves are growing tightly on the stalk, where other mechanical methods have difficulties to detach the leaves in this case. As a result, the stalk is efficiently defoliated, giving access to the buds and allowing their extraction to grow seedlings. Furthermore, the stalk may be processed in another way and the leaves are not destroyed as, e.g., by burning them. Since the stalk is moved along its longitudinal axis, the mechanism allows for automation and efficient use on one stalk after the other.

The air flow can be generated by different methods, which are known as such. In particular, at least one nozzle or an arrangement of several nozzles can be used to generate a defined spatial distribution of the air flow, for example to direct the air with a predetermined intensity onto the stalk and to control where and at what angle the air flow hits the stalk, thereby optimizing the lifting of the leaves. To this end, it is central that the air flow is oriented in a direction from the top of the stalk, since the leaves grow in an upward direction from the ground. The top of the stalk is therefore defined as the end opposite to the base where the stalk is growing out of the ground.

Depending on the configuration, the air flow can be constant or variable in time, particularly it can comprise short pulses of high intensity air flow. The distribution of the air flow, in particular the shape of the cross section of the air flow, can be chosen as desired and as suitable for the application. In one embodiment of the invention, the air flow has a laterally elongated cross section. In particular, a flat shape of the air flow can be chosen. The ratio of the length to the width of the elongated cross section is particularly larger than 2, preferably larger than 5 and more preferably larger than 10. Particularly, the direction of the width of the cross section can be essentially tangential to the circumference of the stalk. Thus, the air flow can advantageously be directed specifically to a clearly defined region of the stalk and leaves.

Different technologies may exist that allow achieving a highly defined distribution of regions with high air pressure generated by the air flow. The air flow can be implemented, e.g., as air jet, air blade, air knife or in any other suitable style.

The mechanism to remove the leaves from the stalk can be implemented by different methods or a combination thereof. In particular, cutting and/or shearing the leaves off can be chosen as suitable approaches, allowing both manual operation and more or less

automatically operated machines. Furthermore, cuts can be executed, e.g., by water jet cutters or other cutting devices.

In one embodiment of the invention, the stalk is oriented such that the top of the stalk is moved in the forward direction. Thus, the top is at the front of the moving stalk. Since the leaves grow towards the top of the stalk, it is therefore advantageously possible to lift off the leaves successively and remove them.

In one embodiment, the air flow is generated by a plurality of nozzles surrounding the longitudinal axis of the stalk. This makes it easier to reach all the leaves that are growing on different sides of the stalk with the air flow at one time. An advantageously efficient and thorough defoliation of the stalk can therefore be reached.

The at least one air flow that is generated by the plurality of nozzles comprises individual air flows, which are created by each single air nozzle. The shape of the individual air flows and the arrangement of the single air nozzles determine the shape and distribution of the resulting air flow. Thus, in the present description, the term "air flow" can relate to both the plurality of individual air flows and the total resulting air flow that is generated.

In one embodiment, the air flow is generated by a plurality of nozzles arranged in a ring configuration around the longitudinal axis of the stalk. This makes it easier to reach all the leaves that are growing on different sides of the stalk with the air flow at one time. An advantageously efficient and thorough defoliation of the stalk can therefore be reached.

The ring configuration of the air nozzles is to be understood as an arrangement such that the stalk is surrounded by the plurality of air nozzles. Particularly, the air nozzles are arranged at the same distance to the stalk. Furthermore, they can be arranged such that each of them is aligned at another angle relative to the stalk's longitudinal axis. Particularly, the air nozzles can be arranged at the same position relative to the length of the stalk and evenly distributed around the longitudinal axis of the stalk, particularly at the same distance from the stalk. The air nozzles can further be arranged shifted to each other, forming for example a spiral arrangement, wherein the ring configuration is visible from a view in a direction along the longitudinal axis of the stalk.

In another embodiment, the leaves are detached by shearing forces exerted by the air flow. This allows advantageously simplifying the defoliation process, since the air flow can be used in a dual function for lifting off the leaves and for removing them. In particular, this can be achieved by using a very strong and focused air flow, which is generated by suitably formed air nozzles. Furthermore, a pulsed air flow can be used for the detaching of the leaves, and several sets of nozzles can be used to lift and detach the leaves, respectively. In one embodiment of the invention, the distribution and/or intensity of the air flow is adjusted depending on the position and/or properties of the stalk. For example, image data of the stalk can be retrieved and an image processing method can be used to determine where leaves, nodes and/or buds are positioned on the stalk. Therefore, natural variations in the growth of the stalks and differences in the position of the stalk itself can be compensated.

In one embodiment of the invention, the leaves are detached alternatively or in addition by at least one pair of rollers, which are rotating in opposite directions. In particular, the rollers rotate along axes parallel to the longitudinal axis of the stalk, arranged with respect to each other suitably for drawing leaves between them and shearing the leaves off.

The pair of rollers in this sense in particular comprises two cylindrical bodies, e.g., formed by metal that are mounted such that the circumferential surfaces touch each other or are at a close distance to each other, forming a gap between the rollers. The support can be stiff, holding the rollers firmly in place, or flexible, allowing passive or active displacement of the rollers relatively to each other. The rollers are mounted rotatably around their longitudinal axis. In particular, the rollers' longitudinal axes are arranged in parallel to the longitudinal axis of the stalk, as is the gap between the rollers.

The rollers of one pair are rotated in opposite directions, such that a leaf on the stalk can get jammed in the gap and is drawn in due to the rotation. Therefore, the distance between the circumferential surfaces of the rollers needs to be adjusted to provide a big enough force holding and moving the leaf away from the stalk. The force pulling the leaf away from the stalk can then be used to shear off the leaf. This provides an advantageously efficient way of removing leaves, while the rollers can be arranged such that only the leaves get clamped between the rollers that are to be removed, therefore preserving the buds on the stalk. In one embodiment of the invention, at least one plurality of pairs of rollers is surrounding the longitudinal axis of the stalk in a ring-configuration. This allows advantageously removing leaves on different positions around the stalk's longitudinal axis. Particularly, several rings of roller pairs can be arranged one after the other such that the stalk passes several places in which the leaves are removed. Arranging these rings act out of phase relatively to each other, a leaf that cannot get caught in on ring of rollers can be removed by the next ring.

In other embodiments, the plurality of rollers can be arranged in different configurations, for example in a configuration spiraling around the stalk's longitudinal axis. In particular, the rollers can be arranged in any configuration that ensures that leaves all around the stalk can be detached.

In an embodiment of the invention, the rollers comprise a conical shape at the end pointing opposite to the direction of movement of the stalk. This shape of the rollers forms a funnel for each pair of rollers such that the leaves are guided towards the gap between the rollers.

In another embodiment of the invention, the detached leaves are removed by a second air flow, essentially in a direction perpendicular to the longitudinal axis of the stalk. This allows handling the debris in a way that ensures reliable operation of the defoliation device. The detached leaves can be blown away from the stalk or sucked in by the second air flow. They can be subsequently collected and used, for example for energy production.

The defoliation machine according to the invention comprises a stalk conducting unit, forming an elongated cavity suitable to take up the stalk and providing a movement essentially along the longitudinal axis of the stalk. It further comprises a blower unit, suitable for generating at least one air flow, which is directed onto the cavity in a defined direction and at an acute angle relative to the longitudinal axis of the cavity, and suitable for lifting off leaves from the stalk that is taken up by the cavity. Finally, it comprises a leaf detaching unit for detaching the lifted leaves from the stalk.

The defoliation machine is particularly configured to execute the above-described method according to the invention. It therefore has the same advantages.

In one embodiment of the invention, the blower unit is adapted to generate an air flow that has a laterally elongated cross section. Particularly, the shape of the air flow can be flat. The ratio of the length to the width of the elongated cross section is particularly larger than 2, preferably larger than 5 and more preferably larger than 10. Particularly, air flow can be formed in such that the direction of the width of the cross section can be essentially tangential to the circumference of the cavity and the typical arrangement of the stalk inside the cavity, respectively. Thus, the air flow can advantageously be directed specifically to a clearly defined region of the stalk and leaves. Different technologies may exist that allow achieving a highly defined distribution of regions with high air pressure generated by the air flow. The air flow can be implemented, e.g., as air jet, air blade, air knife or in any other suitable style.

In one embodiment, the blower unit comprises a plurality of air nozzles surrounding the longitudinal axis of the cavity. The air flow can thus advantageously be generated in such a way that leaves in different areas of the stalk can be reached. In another embodiment, the blower unit comprises a plurality of air nozzles arranged in a ring configuration around the longitudinal axis of the cavity. The air flow that is generated by these nozzles can advantageously be arranged around the stalk such that the leaves can be detached evenly all around the stalk. In another embodiment, the air nozzles generate an air flow that is suitable to shear off the leaves from the stalk. This double use of the air flow generated by the air nozzles allows an advantageously compact and simple configuration of the machine. Furthermore, separate sets of nozzles can be used to generate the air flow to lift off the leaves and to shear them off, or the air flow generated by the nozzles can be varied in time to subsequently lift off the leaves and then detach them.

In one embodiment, the leaf detaching unit comprises at least one pair of rollers, comprising a pair of cylindrical bodies, which are arranged in parallel to each other, rotating in opposite directions and suitable to draw lifted leaves in between them and to shear off the leaves. In particular, the rollers are arranged parallel to the longitudinal axis of the cavity. As described above, this allows detaching the leaves efficiently and reliably.

In one embodiment, the rollers comprise a conical shape at the end pointing against the direction of movement of the stalk. The conical shapes can act as a funnel for leaves that are lifted off by the air flow to guide them between the rollers.

In one embodiment of the invention, the rollers comprise a cylindrical shape and a friction surface on the circumferential surfaces. This makes for an advantageously strong grip of the pair of rollers to a drawn-in leaf and therefore allows applying high forces. The friction surface can be provided in different ways, for instance by adjusting the roughness or structures on the surfaces or providing needles or a sticky film on the surfaces. The invention is now described with reference to the drawings.

Figure 1 shows a basic scheme of a sugarcane plant with a stalk, leaves and buds, Figure 2 shows an embodiment of an air nozzle lifting a leaf off the stalk of a sugarcane plant,

Figure 3 shows an embodiment of a defoliation machine,

Figure 4 shows a detailed view of a pair of rollers within the defoliation machine of figure

3,

Figure 5 shows a cross-sectional view of an embodiment of a defoliation machine, Figure 6 shows another embodiment of a defoliation machine,

Figure 7 shows a schematic view of an embodiment of a defoliation machine, driven by a gearing mechanism, and

Figure 8 shows a schematic view of an embodiment of a defoliation machine operated by a user.

With reference to figure 1 , a basic scheme of a sugarcane plant with a stalk, leaves and buds is explained.

The sugarcane plant, as typically without burning off the leaves beforehand on the field, comprises a stalk 1. Leaves 2 have grown on the stalk 1 into a direction towards the top of the plant away from the soil. Buds 3, which are considered embryonic shoots, are typically covered by leaves 2, giving them protection against outer influences.

A common way of growing sugarcane starts by cutting the stalk 1 into pieces, each comprising one or more buds 3, and growing seedlings from these buds 3. The seedlings are then planted on the field and grown to full size, before they are harvested and the cycle can start again. To extract the buds 3 most efficiently, free access is needed to the buds 3 and the covering leaves need to be removed, while the buds 3 may not be damaged. With reference to figure 2, an embodiment of an air nozzle lifting a leaf off the stalk of a sugarcane plant is explained.

The sugarcane plant shown in figure 1 , with the stalk 1 , leaves 2 and buds 3 is exposed to an air flow 5, which is generated by an air nozzle 4. The embodiment comprises a plurality of air nozzles 4, which are surrounding the longitudinal axis of the stalk 1 . More specifically, the air nozzles 4 in the embodiment are arranged in a ring configuration around the longitudinal axis of the stalk 1 . However, only one air nozzle 4 is shown in figure 2 in order to illustrate the functional principal more clearly. The stalk shown in figure 2 has been partially defoliated, such that several buds 3 are already exposed and are no longer covered by leaves 2. The air flow 5 is directed onto the stalk 1 in a direction from the top of the plant, such that it can enter under the tip and the edges of the leaves 2. An acute angle relatively to the longitudinal axis of the stalk 1 ensures that air is entering under the leaves 2 and builds up a pressure that is sufficient to lift the leaves 2 away from the stalk 1. Like this, a mechanism to remove the leaves 2 can attack the leaves at a distance from the stalk 1 and the buds 3 are not harmed in the process.

For optimization purposes, the shape of the air flow 5 is one important variable and can, e.g., be adjusted by choosing an appropriate type of air nozzle 4. In the case shown here, the air nozzle 4 generates an air flow 5 with a laterally elongated, flat cross section. The ratio of the length to the width of the elongated cross section is particularly larger than 2, preferably larger than 5 and more preferably larger than 10. Herein, the direction of the width of the elongated cross section of the air flow 5 extends essentially tangentially relative to the circumference of the stalk 1. This allows reaching under the leaves 2 and lifting them efficiently, without too much sensitivity to varying positions of the leaves 2 on the stalk 1. In other embodiments, the air flow 5 may be differently shaped, for example broader, tapered towards the stalk 1 or less sharply defined than indicated in figure 1 . In particular, techniques like, e.g., air blades, air jets or air knives can be utilized.

With reference to figure 3, an embodiment of a defoliation machine is shown. The sugarcane plant as shown in figure 1 , with stalk 1 and leaves 2, is fed to a defoliation machine according to the invention, comprising air nozzles 4 and rollers 6. The machine further comprises a mechanism to conduct the stalk 1 , for example as detailed below with reference to figure 8. The stalk 1 is moving into the direction of the top of the plant, i.e., to the right in figure 3.

The air nozzles 4 are arranged around the stalk 1 and generate air flows 5, which lift the leaves 2 off the stalk 1 , as detailed above with reference to figure 2 for a single nozzle. Pairs of rollers 6 are arranged in a ring-configuration around the stalk 1 , all aligned in parallel to the longitudinal axis of the stalk 1. In particular, the diameter of the ring of rollers 6 around the stalk 1 is large enough to provide a distance between the stalk 1 and the rollers 6 to ensure that the buds 3 are protected from mechanical stress exerted by the rollers 6.

Each pair of rollers 6 is arranged closely to each other, wherein the rolls rotate in opposite directions, as indicated by arrows 7. A gap between the rollers 6 is adjusted to a width such that leaves 2 can be drawn in and get jammed between the rollers 6. In other embodiments, the gap can be so small that the rollers 6 touch each other or it can be varied depending on the need, for example by mounting the rollers 6 on a flexible support. Further, the distance between the pairs of rollers within the ring can be chosen differently in different

configurations. Since the rotation direction 7 of the rollers 6 is configured such that a force away from the stalk 1 is exerted on the jammed leaves 2 and the leaves 2 are therefore sheared off. They are then, following the rotation of the rollers 6, transported to the outside of the rollers' ring configuration. The stalk 1 is moved further and the leaves 2 further down the stalk 1 are removed in the same way. Air nozzles 4 and rollers 6 are arranged relative to each other and relative to the stalk 1 such that the leaves 4 are most efficiently lifted off and detached from the stalk 1.

With reference to figure 4, a detailed view of a pair of rollers within the defoliation machine of figure 3 is explained.

The rollers 6 comprise a friction surface 8 and a conical shape 9 at the tip facing opposite to the direction of the movement of the stalk 1 . Thus, the leaves 2 are lifted off the stalk 1 by the air flow 5 and are subsequently funneled into the gap between the rollers 6. The angle described by the conical shape 9 can be chosen according to each individual configuration. The friction surface 8 of the rollers 6 can be obtained by structuring the surface, for example by using a roughness that is chosen such that it provides a large enough frictional force to shear a leaf 2 off the stalk 1. Furthermore, other known techniques can be used, for example sticky surfaces, or needle structures on the surface.

With reference to figure 5, a cross-sectional view of an embodiment of a defoliation machine is explained.

The defoliation machine of figure 3 is shown. Arrows indicate the forces exerted on objects between the rollers 6 and the directions of rotation of the rollers 6. The conduction mechanism is indicated, which holds the stalk 1 in a position essentially in the middle between the ring of rollers 6.

The stalk 1 is conducted essentially through the middle of the ring of six rollers 6 that are regularly distributed around the longitudinal axis of the stalk 1 . In other embodiments, any number of rollers can surround the stalk and their arrangement is not limited to a ring shape. The rollers rotate in alternating directions around their longitudinal axes, which are parallel to the longitudinal axis of the stalk. Like this, forces are exerted on objects that get jammed between any pair of rollers, either towards the stalk 1 or away from it.

To remove the leaves 2 from the stalk 1 , a radial force away from the stalk 1 has to be exerted. In the shown embodiment, only every second gap between two rollers 6 fulfills this condition.

A more complete defoliation can therefore be reached by an assembly as explained with reference to figure 6, which shows another embodiment of a defoliation machine.

Referring to figure 6, two of the assemblies of rollers 6 in a ring-configuration around the stalk 1 , a first part 16 and a second part 17, are arranged one after the other, such that a defined position on the stalk passes by the two parts 16 and 17 one after the other. The first part 16 and the second part 17 are rotated to each other such that the direction of the rotation of rollers 6 that are aligned on the same longitudinal axis is opposite. Therefore, pairs of rollers 6 that are arranged after each other exert forces in opposite directions, i.e., leaves 2 that are not detached from the stalk 1 in the first part 16 are detached by the second part 17. By optimizing the arrangements of the two parts 16 and 17, or more parts in analogue configurations, the defoliation efficiency of the stalk can be optimized.

With reference to figure 7, a schematic view of an embodiment of a defoliation machine, driven by a gearing mechanism, is explained

An outer gear wheel 13 is arranged around the ring-configuration of the plurality of rollers 6, here six rollers 6. The outer gear wheel 13 is connected to a gearing mechanism 14, comprising further gear wheels that transfer the motion of the outer gear wheel 13 to the rollers 6 such that they are rotated in alternating directions. It is also indicated that the gearing mechanism 14 is integrated into the conduction mechanism that guides the stalk through the defoliation machine.

With reference to figure 8, a schematic view of an embodiment of a defoliation machine operated by a user is explained.

A user 1 1 is feeding a sugarcane plant with a stalk 1 into a defoliation machine according to the invention. Transport rolls 12 guide the stalk such that it passes a defoliation unit 18, comprising, e.g., an assembly as shown in figure 3 with air nozzles and a ring of rollers to detach the leaves. The stalk 1 is moving through an elongated cavity in the machine, which is adjusted in its diameter and shape to taking up the stalk 1 . After the leaves 2 have been removed, an air stream generated by a fan 15 is blowing them away from the stalk 1 and the defoliation unit 18. The defoliated stalk 10 leaves the machine and can be collected. In another embodiment, additionally or alternatively to the fan 15, a suction unit creates a negative pressure that is used to suck the detached leaves 2 and collect them. Like this, leaves 2 can be collected and used, e.g. for energy production, and do not clog or otherwise disrupt the function of the defoliation machine. In another embodiment, the leaves 2 are sheared off not by the rollers 6 as shown in the previous figures, but by an air stream 5 generated by the air nozzles 4. In this case, the air stream 5 is strong enough to not only lift the leaves 2, but also exert a force that suffices to detach the leaves 2. In particular, techniques like, e.g., air blades, air jets or air knives can be used to generate the localized high air pressure that is needed herein. Therein, the air stream 5 can be constant or variable, in both intensity and distribution. Furthermore, different air nozzles 4 can be used to fulfill the different tasks of lifting the leaves 2 and shearing them off the stalk 1.

In another embodiment, a sensor detects the position and different properties of the stalk. For instance, a camera system can be used to record image data and a data processing unit can extract the position and orientation of the stalk relative to the defoliation unit 18. The intensity and distribution of the air flow 5 that is generated by the nozzles 4 can be adjusted according to these data. For example, it can be ensured to direct the air flow 5 onto the leaves 2 in an optimized angle and at a defined position of the leaves 2, thereby optimizing the lifting of the leaves 2. Furthermore, the air flow 5 can be optimized to direct the lifted-off leaves 2 towards a defined position, e.g., supporting the conical tips 9 of the rollers 6 in funneling the leaves 2 between the rollers 6.

The properties of the air flow 5, such as intensity, shape and intensity distribution can be determined in particular by the shape of the air nozzles 4. This shape can be executed statically by a solid nozzle or flexible nozzles can be used. In particular, the air nozzles 4 are chosen suitably to create the air pressure that is needed to lift the leaves 2 off the stalk 1 , or even detach them from the stalk 1 , as in one embodiment of the invention. Techniques like, e.g., air blades, air jets or air knives can be utilized to create highly defined areas with the desired distribution of the air flow and consequently the air pressure. In addition to that, the stream of air provided to operate the air nozzles 4 can be varied, e.g., by varying the intensity of the air flow or a temporal dependence of the intensity, e.g., with pulses of air at a higher flow rate.

List of reference signs:

1 stalk with leaves

2 leaf

3 bud

4 air nozzle

5 air flow

6 roller

7 direction of rotation

8 friction surface

9 conical tip

10 defoliated stalk

1 1 user

12 transport rolls

13 outer gear wheel

14 gearing mechanism

15 fan

16 first part

17 second part

18 defoliation unit

Claims

1 . Method for removing leaves (2) from a stalk (1 ) of a graminaceous plant,

comprising

moving the stalk (1 ) essentially along its longitudinal axis;

generating at least one air flow (5), which is directed onto the stalk (1 ) in a direction from the top of the stalk (1 ) and at an acute angle relative to the longitudinal axis of the stalk (1 ),

thereby lifting off leaves (2) from the stalk (1 ); and

detaching the lifted leaves (2) from the stalk (1 ).

2. Method according to claim 1 ,

characterized in that

the air flow (5) has a laterally elongated cross section.

3. Method according to claim 2,

characterized in that

the ratio of the length to the width of the elongated cross section of the air flow (5) is larger than 2.

4. Method according to any of the preceding claims,

characterized in that

the stalk (1 ) is oriented such that the top of the stalk (1 ) is moved in the forward direction.

5. Method according to any of the preceding claims,

characterized in that

the air flow (5) is generated by a plurality of nozzles (4) surrounding the longitudinal axis of the stalk (1 ).

6. Method according to any of the preceding claims,

characterized in that

the air flow (5) is generated by a plurality of nozzles (4) arranged in a ring configuration around the longitudinal axis of the stalk (1 ).

7. Method according to any of the preceding claims,

characterized in that

the leaves (2) are detached by shearing forces exerted by the air flow (5).

8. Method according to any of the preceding claims,

characterized in that

the distribution and/or intensity of the air flow (5) is adjusted depending on the position and/or properties of the stalk (1 ).

9. Method according to any of the preceding claims,

characterized in that

the leaves (2) are detached by at least one pair of rollers (6), which are rotating in opposite directions (7).

10. Method according to claim 9,

characterized in that

the rollers (6) are rotating along axes parallel to the longitudinal axis of the stalk (1 ).

1 1 . Method according to any of the preceding claims,

characterized in that

the detached leaves (2) are removed by a second air flow, essentially in a direction perpendicular to the longitudinal axis of the stalk (1 ).

12. Defoliation machine for removing leaves from a stalk of a graminaceous plant, comprising

a stalk conducting unit (12), forming an elongated cavity suitable to take up the stalk (1 ) and providing a movement essentially along the longitudinal axis of the stalk (1 );

a blower unit (4), suitable for generating at least one air flow (5), which is directed onto the cavity in a defined direction and at an acute angle relative to the longitudinal axis of the cavity, and suitable for lifting off leaves (2) from the stalk (1 ) that is taken up by the cavity; and

a leaf detaching unit (18) for detaching the lifted leaves (2) from the stalk (1 ),

13. Defoliation machine according to claim 12,

characterized in that

the blower unit (4) comprises a plurality of air nozzles (4) surrounding the longitudinal axis of the cavity.

14. Defoliation machine according to claim 12 or 13,

characterized in that

the blower unit (4) comprises a plurality of air nozzles (4) arranged in a ring configuration around the longitudinal axis of the cavity.

15. Defoliation machine according to claim 13 or 14,

characterized in that

the air nozzles (4) generate an air flow (5) that is suitable to shear off the leaves (2) from the stalk (1 ).

16. Defoliation machine according to any of claims 12 to 15,

characterized in that

the leaf detaching unit (18) comprises at least one pair of rollers (6), comprising a pair of cylindrical bodies, arranged in parallel to each other, rotating in opposite directions (7).

17. Defoliation machine according to claim 16,

characterized in that

the rollers (6) are arranged parallel to the longitudinal axis of the cavity.

18. Defoliation machine according to claim 16 or 17,

characterized in that

the rollers (6) comprise a conical shape (9) at the end pointing against the direction of movement of the stalk (1 ).

19. Method according any of claims 16 to 18,

characterized in that

the rollers (6) comprise a cylindrical shape and a friction surface (8) on the circumferential surfaces.