Sowing disk for pneumatic sowers

Abstract

A sowing disk (1) for pneumatic sowers comprises a discoid body (100) in which at least one ring of through-holes (7) is formed. In the discoid body, a seed side (4) and an air side (6) are identified opposite each other such that a seed is retained by each hole of the ring at the seed side by the effect of a pneumatic pressure difference between the seed side and the air side. The discoid body comprises a support (10) that is more rigid with respect to a resilient covering (11). The covering concerns at least in part the seed side of the discoid body at least in the region of said at least one ring of through-holes.

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 to the main claim.

[0004] In the sowing units of the agricultural precision sowers, it is known to use a disk with one or more concentric rows of holes to pneumatically attract a seed to each hole and transport it to a seed drop duct where it is released. The term "holes" in the following context refers to through openings of any shape capable of pneumatically attracting and retaining the seeds to be dispensed on one side of the disk. The definition of holes is therefore extended to non-cylindrical shapes and geometries suitable to carry out the stated function.

[0005] Typical sowers of this type are described for example in US9338939B1, US6176393B1, US6932236B2. In all the above-mentioned documents are used sowing disks made with a monolithic discoid body, usually of steel or moulded synthetic resins. One of the problems with disks of this type lies in the fact that the seed pneumatically retained against the respective hole does not perfectly copy the geometry of the hole, which inevitably causes air leaks that result at the very least in a greater consumption of air to maintain an adequate pressure differential between the two faces of the disk or even an inadequate retention of the seed at the hole. In the first case, there is an unnecessary dissipation of energy; in the second case, sowing failures may occur, which ultimately lead to a reduction in harvest. It must be taken into account that modern sowers employ a considerable number of sowing units and that, during operation, each unit is subject to jolts, shocks, vibrations and similar disturbance phenomena, which certainly do not help to retain the seed on the hole in the sowing disk. Consequently, the pneumatic system of such sowers must be increased to account for leaks between seed and disk and avoid the worst defect of insufficient retention.

[0006] US7661377B2 describes a sowing disk made of flexible material such as urethane, thin stainless steel, rubber and / or plastic. The disk generally lies within a plane of revolution when in a non-deflected state and is deflected laterally from the plane due to a deflector during rotation within the housing. This solution facilitates sowing on the hillside because it allows for the singularisation of the seeds even when the seeds move sideways in the seed chamber away from the disk. However, the teaching does not result in improved seed retention on the disk hole as no useful teaching is provided to improve the pneumatic seal between the disk and the seeds.

[0007] WO96 / 02123A1 describes a differential pressure seed selection device comprising a seed selection disk assembly and a flexible gasket. The assembly comprises a perforated semi-flexible seed selection disk (0.25 mm thick) mounted on a substantially thicker rotating support disk. This configuration is designed for small seeds as it allows small diameter openings in the thin disk, which are difficult to achieve in thicker conventional disks. During use, the support disk is rigid enough to support both disks against the applied vacuum, while any deflections are absorbed by the gasket. The vacuum attracts and holds the selection disk against the support disk through the openings, creating a unitary assembly. The flexibility of the seed selection disk allows it to adapt to any slight irregularities in the linearity of the support disk. However, this flexibility does not result in an improved retention of the seed on the disk hole, as no teaching is provided to improve the pneumatic seal between disk and seeds.

[0008] The technical problem addressed by the present invention is to make available a sowing disk that is structurally and functionally designed to overcome at least some of the drawbacks complained of with reference to the aforementioned prior art.

[0009] Within the context of this problem, it is an aim of the invention to provide a sowing disk capable of offering an improved pneumatic seal to the seed it is to transport.

[0010] A further aim is to make a sowing disk capable of the above and at the same time free of structural and operational complications for the users.

[0011] This problem is solved and these purposes are at least partly achieved by a sowing disk made in accordance with one or more of the features of the appended claims.

[0012] According to a first aspect of the invention, a sowing disk for pneumatic sowers comprises a discoid body in which at least one ring of through-holes is formed. Preferably, on the discoid body, a seed side and an air side are identified opposite each other such that a seed is retained by each hole of the ring on the seed side by the effect of a pneumatic pressure difference between the seed side and the air side. Preferably, the discoid body comprises a support and a resilient covering. Preferably, the support is more rigid with respect to the resilient covering. Preferably, the resilient covering concerns at least in part the seed side of the discoid body, at least in the region of the ring of through-holes. In this way, when the resilient covering of the disk comes into contact with the seed, it is subject to elastic deformation that allows it to copy the irregular shape of the seed, generating an improved pneumatic coupling. This coupling or sealing reduces air flow consumption and improves the retention of the seed against the disk.

[0013] It should be noted that, preferably, the ring of through-holes is formed both in the support and the covering.

[0014] Preferably the covering adheres to the support. In this way a stable coupling between the covering and the support is obtained.

[0015] Preferably the covering is made of resilient rubber. This feature promotes local elastic deformation that ensures effective pneumatic coupling with the seed.

[0016] Advantageously, the resilience implies the ability of the material to elastically deform around the seed and then return to its original shape, creating a temporary seal.

[0017] In accordance with a preferred feature of the invention, the support comprises a substantially hard disk (e.g. a metal or plastic disk) and the covering is made of resilient rubber. Preferably, the Shore A hardness of the covering is lower than the Shore A hardness of the support.

[0018] In this context, "covering" preferably means a covering layer that, in particular, is applied to the support in such a way that it covers the seed side of the discoid body at least in part, at least in the region of said at least one ring of holes.

[0019] According to a preferred feature the air side of the sowing disk does not have a covering at least in the region of the circumferential area where a roller or sliding block acts to detach the seed.

[0020] In another important example, the holes of the ring are made elastically deformable by the covering, at least in the transition between seed side and air side. This lends itself to the easy removal of any foreign bodies stuck in the openings. Preferably, the seed side and air side are such that, when the sowing disk is immersed with a circumferential sector of the at least one ring of holes into a reservoir of loose seeds, a seed is retained by each hole of said at least one ring of holes on the seed side as a result of the effect of the pneumatic pressure difference between the seed side and the air side.

[0021] Preferably the resilient covering has a thickness not less than the thickness of the support. In this way an extended elastic deformation that promotes the pneumatic coupling with the irregular shape of the seed is obtained.

[0022] According to an aspect of the invention, the discoid body comprises at least one seed-holding bracket which is adjacent to the at least one ring of holes on the seed side, preferably at the radially inner side with respect to the corresponding ring of holes.

[0023] In some embodiments, the seed-holding bracket is provided at least in an angular region of some of the holes of said ring of holes and extends circumferentially over such an extension as to act at least partially counter to the weight of the loose seeds on the seeds retained by the holes of said ring of holes when said disk is immersed into the reservoir of loose seeds.

[0024] In this way, the seed attached to the disk at the respective hole is not burdened and has limited interaction with the loose seeds above it in the reservoir of loose seeds, and the result achieved is a more effective retention of the seed on the corresponding hole until the retained seed emerges from the reservoir of loose seeds.

[0025] The seed-holding bracket can be formed in the covering or in the support.

[0026] Preferably, the bracket is separated from the holes of the ring of holes.

[0027] Preferably, a bracket is provided for each hole of the disk or for each pair of holes in the angular region of the relevant hole or the relevant pair of holes, respectively. This improves the above-mentioned effect.

[0028] Preferably, the bracket is at the base of a recess or recessed cavity in the surface of the disk (particularly in the surface of the covering or of the support). This allows avoiding protrusions projecting from the general surface of the disk.

[0029] Preferably the recess or recessed cavity is blind, i.e. not passing through.

[0030] Preferably the recess or recessed cavity is circumferentially extended to form at least in sections an annular groove and even more preferably the annular groove is continuous.

[0031] Preferably, the annular groove is separated from the holes of the ring of holes. The annular groove can be formed in the covering or in the support.

[0032] In embodiments, the radial dimension of the annular groove is not less than the radial dimension of the holes. Preferably, the annular groove has a maximum radial dimension not less than the radial dimension of each hole of the ring of holes. In other words, the annular groove has a dimension similar to that of the seeds. This corroborates the aforementioned lightening action. It should be noted that, in this context, "radial dimension of each hole" preferably means the dimension of each hole measured along the radial direction of the discoid body (i.e., for example the diameter of each hole).

[0033] The annular groove is preferably unique. It is further preferred that the annular groove is radially more inward on the disk than the ring of holes but adjacent to it.

[0034] In an example embodiment of the invention, the annular groove is associated with a seed agitating device that preferably comprises a plurality of recesses extended into the discoid body (particularly in the covering or in the support) for a thickness commensurable with that of the annular groove and preferably directed radially towards the centre of the disk. These radial recesses contribute to the agitation of the seeds in the seed pickup chamber.

[0035] In a preferred example, the annular hollow has a depth, particularly an axial depth, comprised between 5 % and 90 % of the thickness of the discoid body.

[0036] It is also an object of the invention a sowing unit for pneumatic sowers comprising a disk having one or more of the preceding features and a pneumatic sower comprising a carrier structure and a plurality of the aforesaid sowing units coupled to the carrier structure. The features and advantages of the invention will become clearer from the following detailed description of a preferred but not exclusive embodiment thereof illustrated, by way of non-limiting example, with reference to the accompanying drawings in which:

[0037] - Fig. 1 is a perspective view of a sowing disk made in accordance with the present invention;

[0038] - Fig. 2 is a radial sectional view of a detail of a sowing disk made in accordance with the present invention;

[0039] - Fig. 3 is a schematic view of a sowing unit for a precision pneumatic sower according to the present invention; - Fig. 4 is a schematic view of a precision pneumatic sower according to the present invention;

[0040] - Figures 5a-5c show a radial cross-section of a detail of a sowing disk according to embodiments of the present invention;

[0041] - Figures 6a-6c show a radial cross-section of a detail of a sowing disk according to embodiments of the present invention; Fig. 7 is a front view of a sowing disk made according to the present invention; Fig. 8 is a radial sectional view according to section line VIII-VIII of a detail of the disk in fig. 7;

[0042] Fig. 9 is a sectional view according to section line IX-IX of a detail of the disk in fig. 7;

[0043] Figures lOa-lOf are schematic views of a detail of the sowing disk according to embodiments of the present invention;

[0044] Fig. 11 is a partial perspective view of a sowing disk according to the present invention, shown with seeds on its surface.

[0045] In the figures, 1 generally denotes a sowing disk made in accordance with the present invention. The disk 1 is located 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 coupled to a carrier structure 21.

[0046] Preferably, within the housing 20 of the sowing unit, the sowing disk 1 divides two zones between which a pressure differential is established, in a manner known per se. Preferably, a first zone 3 faces a seed side 4 of the disk and contains a quantity of seeds to be distributed. It 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 a pneumatic pressure lower than that in the first zone 3 is advantageously established therein.

[0047] One or more rows of holes 7, concentric to the axis of rotation X of the disk 1 and passing through a discoid body 100 of the disk itself, allows a passage of air between the first and second zones 3, 5. The disk, rotating about the axis X, is immersed into the seeds contained in the pickup chamber of the first zone 3 and due to the effect of the pressure differential between the first and second zones, a seed remains adhered to each hole, in particular on the seed side, to be transported by the disk towards a drop duct 8 where a vacuum-breaker device 9 (e.g. a block or roller) closes the corresponding hole causing an interruption of the pressure differential and the consequent drop of the seed involved in the duct 8.

[0048] The discoid body 100 of the disk 1 preferably comprises a support 10 which may include a substantially rigid disk 70, e.g., a metal disk or a plastic disk.

[0049] Seen in radial cross-section (example in figure 2), the discoid body 100 in the region of the ring of holes 7 preferably has a resilient covering 11, e.g. made of natural or synthetic rubber, with a Shore A hardness preferably comprised between 10 and 60.

[0050] Advantageously, the support 10 is more rigid than the resilient covering 11. Preferably, the covering 11 concerns at least in part the seed side 4 of the disk 1, at least in the region of the ring of holes 7. The covering is preferably made as a ring concentric to the axis X starting from a diameter slightly smaller than that of the band bearing the ring of holes 7 up to the maximum outer diameter of the disk itself. Alternatively, it is provided that, in the region of the ring 7 of holes, the covering may have a more limited extension, with a lower limit preferably comprising only the zone surrounding each hole 7.

[0051] In any case, it is preferred that the conformation of the covering in the region of a respective hole 7 of the ring comprises, starting from the seed side towards the air side, a truncated conical collar 12 projecting towards the axis of the hole 7, preferably terminating with a lip 13 and preferably followed by a widening 31 of the hole which preferably extends to cover the part of the hole 7 concerning the support 10. In embodiments, the widening 31 of the hole has a cylindrical cross-section (example in figure 2) or has a truncated conical cross-section (examples in figures 5a-5c).

[0052] With reference to the examples in figures 5a-6c, a deformable lip 30 projecting from the truncated conical collar 12 towards the seed side 4 and / or towards the axis of the hole 7 is optionally provided to copy the shape of the seed retained on the hole. In this way, the pneumatic adhesion of the seed retained on the hole is further improved. It is preferred that the lip 30 ends before reaching the surface of the seed side 4, i.e. before emerging from the hole 7. In embodiments, the lip 30 is circumferentially extended to form a continuous lip (examples in figures 5a-6a) or is circumferentially extended in sections (example in figure 6b) or is circumferentially extended in a spiral (example in figure 6c). The lip 30 can be a single lip (examples in figures 5a and 6c) or a plurality of concentric lips 30 can be provided (examples in figures 5b-6b). In the example in figure 6b, a plurality of concentric lips 30 is provided, circumferentially extended in alternating and partially overlapping sections.

[0053] In close proximity to the ring of holes 7 an annular groove 14 is preferably formed. The annular groove 14 is preferably concentric to the ring of holes 7 and preferably closed in a continuous ring. In embodiments, the annular groove 14 is formed on the seed side of the disk at least at the radially inner side with respect to the ring of holes. The annular groove 14 is preferably a single (examples in figures 1, 7-9, lOd, lOe, 11), even if several concentric grooves are provided radially inside or outside the ring of holes (examples in figures 10b, 10c).

[0054] The function of the annular groove 14 is to lighten the weight of the seeds in the seed pickup chamber (zone 3) from the seed (loose seeds) retained on the corresponding hole 7, as shown in the example in figure 11.

[0055] The lightening effect derives mainly from the fact that the edge 16 of the annular groove proximal to the ring of holes 7 defines (and performs the effect of) a seed-holding bracket 17 recessed in the thickness of the discoid body for a thickness preferably comprised between 5 % and 90 % of the thickness of the discoid body. This bracket may alternatively be projecting from the discoid body, in axial protrusion with respect to it. In both the protruding and the recessed form, the bracket 17 is preferably arranged at least in the angular region of some of the holes 7 and is circumferentially extended over such an extension as to act at least partially counter to the weight of the loose seeds on the seeds retained by the holes of the ring when the disk is immersed into the seed pickup chamber (loose seeds collection reservoir).

[0056] Preferably, a seed-holding bracket 17 is made for each hole 7 of the disk in the angular region of the corresponding hole 7 (example in figure 10a) or a bracket for each pair of holes (example in figure lOf) or a continuous bracket in the form of an annular ring (examples in figures 1, 7-9, lOb-lOe, 11).

[0057] In the proposed embodiment, the bracket 17 is at the base of a recess that could be extended circumferentially to form at least in sections an annular groove, or a continuous annular groove as described in the preferred example in figure 1.

[0058] Experimental tests have shown that, given the same geometry of the hole 7, the presence of the annular groove 14 significantly improves the possibility of effective seed pickup, resulting in its firm retention despite collisions with other seeds in the pickup chamber, allowing higher disk rotation speeds with the same singularisation precision. The presence of the annular groove 14 and the stabilising function on the seeds retained by the disk also makes it possible to avoid the stalling effect that is generated on the disk when one or more seeds detach or do not adhere to the respective hole 7 causing a free passage of air through the disk and a consequent decrease in the pneumatic retention force of the seeds on the disk in the remaining holes 7. The effect of the diminished retaining capacity propagates, worsening as the seeds detach from the disk, causing the stalling effect and the propagation of failures in the sowing precision.

[0059] Preferably, the discoid body is also equipped with a seed agitating device which, in the proposed example, can advantageously be made by a plurality of recesses 15 alternating with full thickness of the disk, extending from the annular groove 14 in radial direction towards the centre of the disk. Between circumferentially adjacent radial recesses 15 protrusions 19 seed agitators are preferably defined. In this way, the protrusions 19 do not adversely affect the retention of the seed at the respective hole.

[0060] In embodiments, as shown in the example in figure 8, the radial dimension LI of the annular groove is not less than the radial dimension L2 (e.g. internal diameter) of the holes.

[0061] In embodiments, the annular groove 14 preferably has a depth t, in particular an axial depth, comprised between 5 % and 50 % of the radial dimension of the annular groove itself, and more specifically between 10 % and 25 % with respect to the aforementioned radial dimension.

[0062] In embodiments, the bracket 17 (or annular groove 14) is recessed on the seed side, preferably in the covering 11 or alternatively in the support 10.

[0063] In embodiments, the covering 11 continues towards a hub 60 that is substantially central and preferably shaped to allow for driving the disk 1, for example with a polygonal conformation. In order to improve the anchorage of the covering 11 to the support 10, additional through-holes 18 may be provided in the latter, which, filled with the covering, act as improved means of anchorage between the covering and the support. The holes in this case are plugged by the covering and may concern areas of the support other than the one bearing the ring of holes 7.

[0064] Preferably the support 10 is bare on the air side, i.e. without any covering, at least in the region of the ring of holes 7 so that it is less susceptible to wear due to the contact with the vacuum-breaker device 9.

[0065] On the contrary, due to its elastic nature, the resilient covering of the seed side allows it to copy the irregular shape of the seed, generating an improved sealing pneumatic coupling that reduces the air flow consumption.

[0066] The invention thus solves the proposed problem and also achieves numerous advantages, particularly when adopted on large pneumatic sowers where there are numerous sowing units and the problems associated with pneumatic sealing between the seed and the disk are consequently multiplied. In particular, an improved seed adhesion is obtained, resulting in improved sowing precision, the possibility to increase the sowing speed without complications, reduced seed stall effect, and reduced energy consumption of the entire sower.

Claims

CLAIMS1. A sowing disk (1) for pneumatic sowers comprising a discoid body (100), in which at least one ring of through-holes (7) is formed, there being defined in said discoid body a seed side (4) and an air side (6) which are opposite each other and such that a seed is retained by each hole of the ring on the seed side by the effect of a pneumatic pressure difference between the seed side and the air side, characterized in that said discoid body comprises a more rigid support (10) with respect to a resilient covering (11), said covering concerning at least partially the seed side of said discoid body at least in the region of said at least one ring of through-holes.

2. The sowing disk according to claim 1, wherein the covering (11) adheres to the support (10).

3. The sowing disk according to claim 1 or 2, wherein the covering (11) is made of resilient rubber.

4. The sowing disk according to any one of the preceding claims, wherein said support (10) comprises a substantially rigid disk (70) and said covering (11) is made of resilient rubber adhered to said substantially rigid disk (70).

5. The sowing disk according to any one of the preceding claims, wherein said covering (11) has a Shore A hardness comprised between 10 and 60.

6. The sowing disk according to any one of the preceding claims, wherein said ring of through-holes (7) is formed in the support (10) and in the covering (11).

7. The sowing disk according to any one of the preceding claims, wherein said support (10) at the air side (6) does not have a covering (11) at least in the region of a circumferential zone serving as a path for a device provided fordetaching the seed.

8. The sowing disk according to any one of the preceding claims, wherein said support (10) has a plurality of adhesion holes (18) penetrated by the covering (11) in such a manner as to improve the adhesion between the support (10) and the covering (11).

9. The sowing disk according to claim 8, wherein the plurality of adhesion holes (18) comprises holes that are distinct from the at least one ring of holes (7) and plugged by the covering (11).

10. The sowing disk according to any one of the preceding claims, wherein said seed side (4) and said air side (6) are such that, when the sowing disk is immersed with a circumferential sector of the at least one ring of holes (7) into a reservoir of loose seeds, a seed is retained by each hole of said at least one ring of holes (7) on the seed side (4) as a result of the effect of the pneumatic pressure difference between the seed side (4) and the air side (6), said discoid body (100) comprising at least one seed-holding bracket (17) which is adjacent to the at least one ring of holes (7) on the seed side at the radially inner side with respect to the corresponding ring of holes, said seed-holding bracket (17) being provided at least in an angular region of some of the holes of said ring of holes (7) and extending circumferentially over such an extension as to act at least partially counter to the weight of the loose seeds on the seeds which are retained by the holes of said ring of holes when said disk is immersed into the reservoir of loose seeds.

11. The sowing disk according to any one of the preceding claims, wherein the covering (11) has a thickness not less than the thickness of the support (10).

12. The sowing disk according to any one of the preceding claims, wherein theconformation of the covering (11) in the region of a respective hole (7) of the ring of holes comprises, starting from the seed side (4) towards the air side (6), a truncated conical collar (12) projecting towards the axis of the hole.

13. A sowing unit (2) for pneumatic sowers comprising a sowing disk according to any one of the preceding claims and a housing (20) within which the sowing disk is positioned in such a way as to divide a first and a second zone (3, 5) between which the pneumatic pressure difference is established.

14. A pneumatic sower (200) comprising a carrier structure (21) and a plurality of sowing units according to claim 13, the sowing units being coupled to the carrier structure.

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