Sowing disk for pneumatic sowers

Abstract

A sowing disk (1) for pneumatic sowers comprises a discoid member (100), in which at least one ring of through-holes (7) is formed. There are defined in the discoid member a seed side (4) and an air side (6) which are opposite each other and such that, when the sowing disk is introduced with a circumferential sector of the at least one ring of holes (7) into a bowl of loose seeds, a seed is retained by each hole of the at least one ring of holes at the seed side (4) as a result of the effect of a pneumatic pressure difference between the seed side (4) and the air side (6). The discoid member comprises at least one seed-holding bracket (17) which is adjacent to the at least one ring of holes at the seed side at the radially innermost side with respect to the corresponding ring of holes. The seed-holding bracket (17) is provided at least in angular correspondence with some of the holes of the ring of holes and extends circumferentially over such an extent as to act at least partially counter to the weight of the loose seeds on the seeds which are retained by the holes of the ring of holes when the disk is introduced into the bowl of loose seeds.

Description

[0001] SOWING DISK FOR PNEUMATIC SOWERS

[0002] DESCRIPTION

[0003] The invention relates to a sowing disk for precision pneumatic sowers including the features mentioned in the preamble of the main claim.

[0004] In sowing units of precision agricultural sowers, it is known to use a disk which is provided with one or more rings of concentric holes which serve(s) to pneumatically attract one seed for each hole and to transport it as far as a pipe for dropping the seed, where the seed is released. The term "holes" in the following context is intended to indicate through-openings of any shape capable of attracting and retaining pneumatically the seeds to be distributed at one side of the disk. Therefore, the definition of holes extends to non-cylindrical shapes and geometries which are suitable for performing the function indicated.

[0005] Typical sowers of this type are described, for example, in US9338939B1, US6176393B1, US6932236B2, US7448334B2, or EP3888434A2.

[0006] US6176393B1 particularly describes a sowing disk which is suitable for scattering tiny seeds having a screen or grill mounted in the region of the ring of holes, against which the seeds are pneumatically attracted. In one of the examples described, the grill is removably retained by means of seals which are received, together with the circumferential edges of the grill, in respective circumferential cavities. The cavities have this single function and are therefore limited to a minimum radial dimension imposed for the retention of the grill, besides always being occupied during use by the edges of the grill and respective seals.

[0007] US7448334B2 describes a flat disk type circular seed disk provided with a series of circumferentially arranged seed attracting apertures. The apertures are spaced along a circumferential rim offset axially from the remainder of the disk to approximate the seed release location and characteristics of a cell type seed disk. This offset requires raising the portion of the disc containing the openings relative to the base mounting plane of the disc and has the sole purpose of allowing the seed to fall in the correct location of the seed tube.

[0008] EP3888434A2 describes a seed meter disk in which seed agitators, such as agitator pockets, may be located on the seed-side face of the disk. The only function of the agitator pockets is to agitate the seeds located in the seed pool. The sowing disks with a known configuration have a number of problems in the phase of picking up the seed and relevant transport towards the drop pipe for the seed. In fact, in the phase of picking up the seed, when the hole ring segment travels in a state immersed in the loose seeds which are present in the seed pickup chamber, the weight of the seeds which overlap with the one held above a hole (retained seed) bears on the retained seed, potentially compromising the retention thereof. This factor limits the rotation speed of the disk which allows adequate singulation precision to be maintained. In addition to this limited speed, the sowing precision is compromised.

[0009] Furthermore, when one or more seeds become detached from the respective holes of the disk, there is generated a decrease in the pressure for retaining the seed as a result of the greater air flow admitted by the free holes of the disk. This promotes the additional detachment of the seeds from the holes of the disk and an increasing propagation of failures in the seeds deposited on the ground. At most, a so-called stalling condition is achieved, in which all the seeds fall from the disk as a result of the effect of the insufficient pressure difference established between the seed side and the air side of the disk. It must be taken into account that modern sowers use a considerable number of sowing units and that each unit is subjected, during use, to shocks, impacts, vibrations and similar disruptive phenomena which certainly do not cooperate in terms of retaining the seed on the hole of the sowing disk. Consequently, it is necessary to increase the pneumatic system of these sowers in order to take account of the disruptive phenomena and the problems indicated above. This involves greater construction costs for the machine, a lower level of overall energy efficiency and a risk of malfunctions which is present in any case.

[0010] The technical problem addressed by the present invention is to provide a sowing disk which is structurally and functionally configured to overcome at least some of the disadvantages set out with reference to the cited prior art.

[0011] In the context of this problem, an object of the invention is to provide a sowing disk which is capable of providing better retention of the seed which has to be transported, lightening the weight of the surrounding seeds from the retained seed and substantially limiting the possibilities of stalling.

[0012] Another object is to provide a sowing disk which is capable of greater rotation speeds without compromising the sowing precision.

[0013] This problem is solved and these objects are achieved at least partially by a sowing disk which is constructed according to one or more of the features of the appended claims.

[0014] According to a first aspect of the invention, a sowing disk for pneumatic sowers comprises a discoid member, in which at least one ring of through-holes is formed. Preferably, there are defined in the discoid member a seed side and an air side which are opposite each other and such that, when the disk is introduced with a circumferential sector of the ring(s) of holes into a bowl of loose seeds, a seed is retained by each hole of the ring(s) at the seed side as a result of the effect of a pneumatic pressure difference between the seed side and the air side. Preferably, the discoid member comprises at least one seed-holding bracket which is adjacent to the ring(s) of holes at the seed side, preferably at the radially inner side with respect to the corresponding ring of holes. Preferably, this bracket is provided at least in angular correspondence with some of the holes and preferably extends circumferentially over such an extent as to act at least partially counter to the weight of the loose seeds on the seeds which are retained by the holes of the ring when the disk is introduced into the bowl of loose seeds.

[0015] In this manner, the seed which bonds to the disk in the region of the respective hole is not weighed down and has a limited interaction with the loose seeds which are above it in the bowl of loose seeds and there is achieved the result of a more effective retention of the seed on the corresponding hole until the retained seed is discharged from the bowl of loose seeds.

[0016] Preferably, the bracket is separated from the holes of the ring of holes.

[0017] Preferably, there is provided one bracket for each hole of the disk in angular correspondence with the respective hole or there is provided one bracket for each pair of holes in angular correspondence with the respective pair of holes. This arrangement improves the above-indicated effect.

[0018] In an important aspect of the invention, the bracket is at the base of a recess or indentation which is recessed in the surface of the disk. This avoids projections upwards from the general surface of the disk.

[0019] Preferably, the recess or recessed indentation is blind, that is to say, is not a through-hole. Preferably, the recess or recessed indentation extends circumferentially so as to form at least in sections an annular cavity and even more preferably the annular cavity is continuous.

[0020] In some embodiments, the radial dimension of the annular cavity is not less than the radial dimension of the holes. Preferably, the annular cavity has a maximum radial dimension not less than the radial dimension of each hole of the ring of holes. In other words, the annular cavity has a dimension similar to that of the seeds. This cooperates with the lightening action mentioned above. It may be noted that, in this context, the term "radial dimension of each hole" is preferably intended to be the dimension of each hole measured in the radial direction of the discoid member (that is to say, for example, the diameter of each hole).

[0021] Preferably, the radial dimension of the annular cavity and the radial dimension of the holes are of the same order of magnitude, that is, the ratio between the radial dimension of the annular cavity and the radial dimension of the holes is between 0.1 and 10. Even more preferably, the ratio between the radial dimension of the annular cavity and the radial dimension of the holes is between 0.5 and 5. These features optimize the effect of the seed-holding bracket while maintaining the structural rigidity of the disk.

[0022] Preferably, the annular cavity is separated from the holes of the ring of holes.

[0023] The annular cavity is preferably a single cavity. It is more preferable for the annular cavity to be radially more internal on the disk with respect to the ring of holes but adjacent thereto.

[0024] In one embodiment of the invention, there is associated with the annular cavity an agitating device for the seed which preferably comprises a plurality of recesses which extend in the discoid member over a thickness, which is comparable to that of the annular cavity, and which are preferably directed radially towards the centre of the disk. These radial recesses contribute to the agitation of the seeds in the seed pickup chamber.

[0025] In a preferred embodiment, the annular cavity has a depth, in particular an axial depth, between 5% and 90% with respect to the thickness of the discoid member.

[0026] The invention further relates to a sowing unit for pneumatic sowers including a disk with one or more of the preceding features and a pneumatic sower including a carrier structure and a plurality of the above-mentioned sowing units engaged with the carrier structure.

[0027] The features and advantages of the invention will be better understood from the following detailed description of a preferred though non-limiting embodiment thereof which is illustrated by way of non-limiting example with reference to the appended drawings, in which:

[0028] - Figure 1 is a front view of a sowing disk constructed according to the present invention;

[0029] - Figure 2 is a radially sectioned view according to the line of section II-II of a detail of the disk of Figure 1;

[0030] - Figure 3 is a sectioned view according to the line of section III-III of a detail of the disk of Figure 1;

[0031] - Figure 4 is a schematic view of a sowing unit for a precision pneumatic sower according to the present invention;

[0032] - Figure 5 is a schematic view of a precision pneumatic sower according to the present invention;

[0033] - Figures 6a-6f are schematic views of a detail of the sowing disk according to embodiments of the present invention;

[0034] - Figure 7 is a partial perspective view of a sowing disk according to the present invention, in a state depicted in the presence of seeds on the surface thereof

[0035] - Figure 8 is a perspective view of a detail of the sowing disk according to a further embodiment of the present invention.

[0036] In the Figures, there is generally designated 1 a sowing disk constructed according to the present invention. The disk 1 is arranged in the housing 20 of a sowing unit 2. A pneumatic sower 200 according to the present invention may comprise a plurality of sowing units 2 which are engaged with a carrier structure 21.

[0037] Preferably, the sowing disk 1 defines and separates, inside the housing 20 of the sowing unit, two zones between which a pressure difference is established, in a manner known per se. Preferably, a first zone 3 faces a seed side 4 of the disk and a quantity of seeds to be distributed is contained therein. The first zone 3 may constitute a seed pickup chamber, as better explained below. Preferably, a second zone 5 faces an air side 6 of the disk 1 and there is advantageously established therein a pneumatic pressure which is less than the pressure of the first zone 3.

[0038] Preferably, a ring of holes 7 (but where applicable more than one), which ring is concentric with the rotation axis X of the disk 1 and which holes pass through a discoid member of the disk itself, allows an air passage between the first zone and second zone 3, 5. The disk, by rotating about the axis X, is introduced in the seeds which are contained in the pickup chamber of the first zone 3 and, as a result of the effect of the pressure difference between the first and second zones, a seed remains bonded to each hole, in particular at the seed side, in order to be transported by the disk towards a drop pipe 8, where a vacuumbreaking device 9 (for example, with a block or roller) closes the corresponding hole, generating an interruption in the pressure difference and the consequent fall of the seed involved in the pipe 8.

[0039] In some embodiments, the holes 7 of the ring comprise, starting from the seed side 4 towards the air side 6, a frustoconical collar 12 which projects towards the axis of the hole 7, preferably ending with a lip 13 followed by a widened portion 31 of the hole, which preferably extends as far as the air side 6 of the disk.

[0040] There is preferably formed behind the ring of holes 7 an annular cavity 14. The annular cavity 14 is preferably concentric with respect to the ring of holes 7 and is preferably closed in the manner of a continuous ring. In some embodiments, the annular cavity 14 is formed at the seed side of the disk at least at the radially innermost side with respect to the ring of holes. The annular cavity 14 is preferably a single cavity (examples of Figures 1-3, 6d, 6e) although there is provision for the presence of a plurality of radially internal or external concentric grooves with respect to the ring of holes (examples of Figures 6b, 6c).

[0041] The function of the annular cavity 14 is to reduce the weight of the seeds present in the pickup chamber (zone 3) by the seed (loose seeds) being held on the corresponding hole 7, as shown in the example of Figure 7. The weight-reduction effect mainly results from the fact that the edge 16 of the annular cavity proximal to the ring of holes 7 defines (and performs the effect of) a seedholding bracket 17 which is recessed in the thickness of the discoid member over a thickness which is preferably between 5% and 90% of the thickness of the discoid member. Alternatively, this bracket may project from the discoid member with an axial projection with respect thereto. Both in the projecting version and in the recessed version, the bracket 17 is preferably arranged at least in angular correspondence with some of the holes 7 and extends circumferentially over such an extent as to at least partially act counter to the weight of the loose seeds on the seeds which are retained by the holes of the ring when the disk is introduced in the seed pickup chamber (collecting bowl for the loose seeds).

[0042] Preferably, a seed-holding bracket 17 is constructed for each hole 7 of the disk in angular correspondence with the respective hole 7 (example of Figure 6a) or a bracket for each pair of holes (example of Figure 6f) or even a continuous bracket in the form of an annular ring (examples of Figures 1-3, 6b-6e).

[0043] In the embodiment proposed, the bracket 17 is at the base of a recess 18 which may extend circumferentially so as to form at least in sections an annular cavity or a continuous annular cavity as described in the preferred example of Figures 1-3.

[0044] It is specified that, in some embodiments, the circumferential extension of the sections of the annular cavity formed in sections may be, for example, at least 1.5 times the diameter of the holes 14 and in some examples at least 3 times the diameter of the holes 14.

[0045] Experimental tests have shown how, for the same geometry of the hole 7, the presence of the annular cavity 14 substantially improves the possibility of effective seed pickup, with a resultant firm retention thereof, notwithstanding the impacts with the other seeds in the pickup chamber, allowing greater rotation speeds of the disk for the same singulation precision. The presence of the annular cavity 14 and the stabilizing function on the seeds which are retained by the disk further avoids the stalling effect which is generated on the disk when one or more seeds become detached or do not bond to the respective hole 7, causing a free passage of air through the disk and a consequently reduced pneumatic retention force for the seeds on the disk in the remaining holes 7. The effect of the reduced retention capacity is propagated, gradually becoming worse with detachment of the seeds from the disk, causing particularly the stalling effect and the propagation of failures in the sowing precision.

[0046] Preferably, the discoid member is further provided with an agitating device for the seed which, in the example proposed, can advantageously be formed by a plurality of recesses 15 which alternate with the full thickness of the disk, which extend from the annular cavity 14 in the radial direction towards the centre of the disk. There are preferably defined between circumferentially adjacent radial recesses 15 projections 19 for agitating the seed. In this manner, the projections 19 do not negatively affect the grip of the seed in the region of the respective hole.

[0047] With reference to the example in Figure 8, it is also provided that projections 19 for agitating the seed may be formed within the annular cavity 14. Preferably, these projections 19 have an axial thickness smaller than the full thickness of the disk. In this manner, the presence of the projections 19 does not interrupt the continuity of the annular cavity 14, at least in the portion of the annular cavity axially between the top of the projections 19 and the general surface of the disk.

[0048] In some embodiments, as shown in the example of Figure 2, the radial dimension LI of the annular cavity is not less than the radial dimension L2 (for example, internal diameter) of the holes or, alternatively, is not less than 0.5 times the radial dimension L2 of the holes.

[0049] In some embodiments, the ratio between the radial dimension LI of the annular cavity and the radial dimension L2 of the holes is less than or equal to 5 and, in some particular examples, may be less than or equal to 2.

[0050] In some embodiments, the annular cavity 14 preferably has a depth t, in particular an axial depth, between 5% and 50% of the radial dimension of the annular cavity itself and more particularly between 10% and 25% with respect to the above-mentioned radial dimension. The invention thereby solves the problem proposed, achieving a number of advantages, particularly when used on pneumatic sowers with great dimensions, in which the sowing units are large in number and the problems associated with the pneumatic seal between the seed and the disk are consequently multiplied. In particular, there is obtained improved adhesion of the seed with a resultant improved sowing precision, a possible way of increasing the sowing speed without disadvantages, a reduced stalling effect for the seeds, a reduced energy consumption of the entire sower.

Claims

Claims1. A sowing disk (1) for pneumatic sowers comprising a discoid member (100), in which at least one ring of through-holes (7) is formed, there being defined in the discoid member a seed side (4) and an air side (6) which are opposite each other and such that, when the sowing disk is introduced with a circumferential sector of the at least one ring of holes (7) into a bowl of loose seeds, a seed is retained by each hole of the at least one ring of holes at the seed side (4) as a result of the effect of a pneumatic pressure difference between the seed side (4) and the air side (6), characterized in that the discoid member comprises at least one seed-holding bracket (17) which is adjacent to the at least one ring of holes at the seed side at the radially innermost side with respect to the corresponding ring of holes, the seed-holding bracket being provided at least in angular correspondence with some of the holes of the ring of holes and extending circumferentially over such an extent as to act at least partially counter to the weight of the loose seeds on the seeds which are retained by the holes of the ring of holes when the disk is introduced into the bowl of loose seeds.

2. The sowing disk (1) according to claim 1, comprising a seed-holding bracket (17) for each hole or for each pair of holes of the ring of holes (7) in angular correspondence with the respective hole or with the respective pair of holes, respectively.

3. The sowing disk (1) according to claim 1 or 2, wherein the seed-holding bracket (17) is at the base of a recess (18).

4. The sowing disk (1) according to claim 3, wherein the recess extends circumferentially so as to form at least in sections an annular cavity (14).

5. The sowing disk (1) according to claim 4, wherein the annular cavity (14) iscontinuous.

6. The sowing disk according to claim 4 or 5, wherein the annular cavity (14) has a radial dimension (LI) not less than the radial dimension (L2) of each hole of the ring of holes (7).

7. The sowing disk according to any one of claims 4 to 6, comprising a plurality of radial recesses (15) which are open in the annular cavity (14) from a radially innermost position with respect to the annular cavity, projections (19) for agitating the seed being defined between radial recesses (15) which are circumferentially adjacent.

8. The sowing disk according to any one of claims 4 to 7, wherein the radial dimension (LI) of the annular cavity (14) and the radial dimension (L2) of the holes (7) are of the same order of magnitude.

9. The sowing disk according to any one of claims 4 to 8, wherein the ratio between the radial dimension (LI) of the annular cavity (14) and the radial dimension (L2) of the holes (7) is between 0.5 and 5.

10. A sowing unit (2) for pneumatic sowers comprising the sowing disk according to any one of the preceding claims.

11. The sowing unit according to the preceding claim, comprising a housing (20), inside which the sowing disk is arranged so as to identify and separate a first zone and a second zone (3, 5) between which the pneumatic pressure difference is established, wherein the first zone (3) faces the seed side (4) of the sowing disk and delimits the bowl of loose seeds, and wherein the second zone (5) faces the air side (6) of the sowing disk.

12. A pneumatic sower (200) comprising a carrier structure (21) and a plurality of sowing units according to claim 10 or 11, the sowing units being arranged onthe carrier structure.

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