Patent Publication Number: US-2022232787-A1

Title: System for cultivating plants and operation method thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This patent application claims priority from Italian patent application no. 102019000009603 filed on 20 Jun. 2019, the entire disclosure of which is incorporated herein by reference. 
     TECHNICAL FIELD 
     The present invention relates to a cultivation system for plants. 
     In particular, the invention concerns the recovery of the liquid preferably based on fertiliser that, during the aeroponic feeding procedure, is sprayed towards the plants in a cultivation system preferably, but not necessarily, of the vertical farm type, to which the following discussion will make explicit reference without any loss of generality thereby. 
     BACKGROUND ART 
     As is well known, vertical-farm cultivation systems are structured to implement high-density cultivation processes for plants, such as plants/vegetables, in closed artificial environments generally free of soil/earth and sunlight. The plants are cultivated in dedicated shelves or trays mounted horizontally on support frames and are distributed on several cultivation planes overlapped at progressively increasing heights in relation to the support surface for the frames so as to extend the system, including in the vertical direction. 
     The plant cultivation processes carried out through the above-mentioned cultivation systems essentially involve feeding a fertiliser-based liquid into the cultivation planes in a controlled manner and, at the same time, lighting them using artificial light sources. 
     In some cultivation systems of the type described above, the liquid is fed to the plants by aeroponics. The aeroponic feeding essentially involves spraying/nebulising the fertiliser liquid towards the cultivation tray so as to wet the plants&#39; roots. 
     Since during spraying, part of the sprayed fertiliser liquid is dispersed, i.e. it falls downwards, collection systems are generally provided in cultivation systems. 
     Some collection systems require the use of a hydraulic discharge system comprising collection tanks that are arranged below the cultivation planes and are provided with discharge openings on the bottom that are connected, in turn, to vertical discharge columns through external connections. The discharge system also comprises common liquid recovery containers that are arranged below the first cultivation plane and are hydraulically connected to the discharge columns to receive and store the liquid that flows out of the tanks. In use, the liquid contained in the tanks drains, by gravity, through the discharge openings towards the discharge columns that always convey it by gravity to the tanks below. 
     A first technical problem with the hydraulic discharge system described above is that it is particularly susceptible to clogging both at the discharge openings and in the connections. In addition to the cost of intervention, clogging can cause stagnation in the cultivation planes and, thus, increase the risk of fungal and bacterial formation and contamination of the plants. 
     A second technical problem with the hydraulic discharge system described above is that, in order to ensure correct discharge of the liquid, the tanks must be provided with a significant number of both discharge openings and vertical columns, conditions that affect both the overall size of the system and the cost of its implementation. 
     A third technical problem with the hydraulic discharge system described above is that the common collection tanks occupy a useful space that could potentially be occupied by the first cultivation plane, which is therefore attached at a predetermined minimum height that is greater than the height of the tank itself. 
     A known plant cultivation system is described, for example, in CN 109 699 488 A. 
     DISCLOSURE OF INVENTION 
     The Applicant has therefore conducted an in-depth study with the purpose of identifying a solution that is simple and economical to implement, which is able to overcome the above-mentioned technical problems. 
     This purpose is achieved by the present invention as it relates to a cultivation system, as disclosed in the corresponding appended claims. 
     This purpose is also achieved by the present invention as it relates to an operation method for a cultivation system, as defined in the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       This invention will now be described with reference to the accompanying drawings, which illustrate a non-limiting embodiment thereof, wherein: 
         FIG. 1  schematically shows a cultivation system for the production of plants constructed according to the precepts of the present invention, 
         FIG. 2  is a perspective view with parts removed for clarity of a preferred embodiment of the cultivation system for the production of plants constructed according to the precepts of the present invention, 
         FIG. 3  is a vertical cross-section of a portion of the cultivation system for the production of plants shown in  FIG. 2 , 
         FIG. 4  is a vertical cross-section of a cultivation plane of the cultivation system for the production of plants, constructed according to the precepts of the present invention, 
         FIG. 5  is a vertical longitudinal section of a portion of the cultivation plane of the cultivation system for the production of plants, constructed according to the precepts of the present invention, 
         FIG. 6  is a perspective view from above with parts removed for clarity of a cultivation plane of the cultivation system for the production of plants, constructed according to the precepts of the present invention, 
         FIG. 7  is a perspective view from below with parts removed for clarity of a cultivation plane of the cultivation system for the production of plants, constructed according to the precepts of the present invention. 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     The present invention will now be described in detail with reference to the accompanying drawings in order to allow a person skilled in the art to implement and use it. Various modifications to the described embodiments will be readily apparent to persons skilled in the art and the general principles described may be applied to other embodiments and applications without, however, departing from the protective scope of this invention, as defined in the appended claims. Accordingly, this invention is not to be limited in scope to the embodiments described and illustrated herein, but is to be accorded the widest scope consistent with the principles and characteristics disclosed and claimed herein. 
     The present invention is essentially based on the idea of positioning, in each cultivation plane, at least one suction duct at the nebulizing devices present in the cultivation plane so as to suck up the liquid that, during spraying, is dispersed by the nebulizing devices. The present invention is also based on the idea of positioning a liquid collection basin below the cultivation plane so as to collect the liquid dispersed during the spraying and to use the suction duct inside the basin to empty it. 
     According to an embodiment schematically shown in  FIGS. 1, 2, and 3 , the number 1 schematically denotes, as a whole, a cultivation system for plants. Preferably, but not necessarily, the cultivation system  1  may be of the multi-plane, vertical-farm type ( FIGS. 2 and 3 ). 
     The cultivation system  1  may be arranged inside a greenhouse container  2 , preferably a closed one. The greenhouse container  2  may internally delimit the cultivation environment in which at least one cultivation system  1  is installed (in  FIG. 1  two cultivation systems  1  are illustrated merely by way of non-limiting example). The greenhouse container  2  may comprise at least one pavilion-shaped, closed space formed from walls made of transparent material, based on glass and/or plastic, so as to illuminate the cultivation system  1  via solar radiation. 
     It is understood that the greenhouse container  2  is not limited to the container with transparent walls of the type described above, but may comprise a container formed from walls of non-transparent material. In an embodiment wherein the cultivation system  1  is of the vertical-farm type, the greenhouse container has walls made of non-transparent material. 
     It is also implied that, in the discussion that follows, the term “plant” refers to any vegetal product, preferably for food use. The plants may comprise lettuces, greens, vegetables, and aromatic herbs, such as rocket, basil, mint, and the like. It is, in any case, implied that the above-mentioned invention is not limited to plants for food use of the type listed above, but may also be applied to cultivate other types of plants, generally cultivated in greenhouses of the conventional kind, such as flowers, plants, and the like. 
     In the following discussion, explicit reference will be made to vertical-farm cultivation systems  1  without any loss of generality thereby. 
     With reference to the embodiment shown in  FIGS. 1 and 2 , the greenhouse container  2  is closed and may have, for example, a conveniently parallelepiped shape that internally delimits a space/environment for cultivation, preferably artificial. It is implied that the term “artificial cultivation environment” refers to an earthless or above-ground production area/space (grow area), inside of which the automatic plant cultivation/growth programme is carried out. In the artificial cultivation environment, artificial lighting devices (not illustrated), such as LED devices or the like, may be provided inside the greenhouse container  2 . Since these are of a known type, they will not be described further. 
     The cultivation system  1  comprises one or more frames  3  arranged resting on a horizontal plane P ( FIG. 3 ), and a series of cultivation shelves  4  mounted on the frames  3 , so as to form one or more cultivation planes Li, preferably horizontal (which vary between 1 and n layers) and overlapping each other at corresponding, increasing heights from the plane P. 
     With reference to  FIG. 5 , the cultivation shelves  4 , which form a shared cultivation plane/level Li, are coplanar to each other and are arranged one alongside the other along an extension direction K, with the relative, adjacent sides next to each other. The cultivation shelves  4  are structured to support the plants during growth (indicated with V in  FIGS. 4 and 5 ), can preferably have an approximately rectangular shape, and can have the same dimensions. The cultivation shelves  4  may be structured so as to be firmly coupled to the frame  3  but also so that they can be easily removed/detached (or separated). According to one embodiment shown in  FIGS. 1, 4, and 5 , the cultivation shelves  4  comprise thin, flat sheets that are arranged approximately horizontally with the opposite, straight longitudinal edges (parallel to the direction K) resting on respective lateral, support clamps  5  preferably mounted on the vertical columns of the frame  3  ( FIG. 4 ). The cultivation shelves  4  are preferably made, for example, from a plastic base, and are structured to ensure that the plant roots, during the plants&#39; growth, firmly grasp the body of the cultivation shelf  4  so that the roots extend mainly below the lower surface  4   a  of the cultivation shelf  4 , and the useful plant portion mainly extends above the upper surface  4   b  of the cultivation shelf  4 . 
     With reference to  FIG. 1 , the cultivation system  1  comprises, in addition, an aeroponic feeding system  6 , which is structured so as to selectively nebulise a liquid at the cultivation shelves  4  present in the cultivation planes Li. It is understood that the liquid may be based on a mix of water and nutritional substances suitable for plants (fertilisers). The aeroponic feeding system  6  may be structured to selectively feed the liquid in the cultivation planes Li in a controlled way in terms of quantity and/or type and/or instants of feeding, via spraying. According to one embodiment shown in  FIG. 1 , the aeroponic feeding system  6  may comprise, for each cultivation level/plane Li, at least one delivery tube or duct  7  through which the liquid circulates, and a series of nebulizing devices, for example nozzles  8 , which are preferably arranged below the cultivation shelves  4  of the cultivation plane Li so as to spray the liquid towards the lower surface  4   a  of the cultivation shelves  4  above and are hydraulically connected to the delivery duct  7  to receive the liquid. 
     According to the embodiment shown in the attached figures, the aeroponic feeding system  6  may comprise, for each cultivation plane Li, at least one delivery duct  7  that is arranged below the cultivation shelves  4  and extends along the cultivation plane Li, parallel to the extension direction K of the cultivation plane Li itself ( FIGS. 1 and 5 ). According to a preferred embodiment shown in  FIGS. 3-7 , the aeroponic feeding system  6  may comprise four delivery ducts  7 , while the nozzles  8  are arranged above the delivery ducts  7 , preferably supported by the same. The delivery ducts  7  are, preferably, basically straight, having axes A that are parallel to each other and to the direction K, and are conveniently coplanar and equidistant to each other ( FIG. 4 ). 
     According to the embodiment shown in  FIG. 1 , the aeroponic feeding system  6  comprises, in addition, a feeding assembly  9 , which is designed to selectively supply the feeding ducts  7  with the liquid to feed the cultivation shelves  4 . The feeding assembly  9  is of a known type and, therefore, will not be additionally described if not to specify that it may comprise liquid containment basins (not illustrated) and hydraulic pumps (not illustrated) that suck up liquid from the basins and supply it at the inlet to the ducts  7 . The aeroponic feeding system  6  may also comprise, preferably but not necessarily, solenoid valves  10  that are connected to the ducts  7  and are designed to selectively open/close each relative duct  7  based on a corresponding command/signal generated by an electronic control unit  11 . 
     The cultivation system  1  also comprises a suction system  12  that is structured so as to suck up the dispersed nebulised liquid in each of the cultivation planes Li. According to a preferred embodiment shown in  FIGS. 3, 4 , and  5 , the suction system  12  comprises, for each cultivation plane Li, a liquid collection basin  14 , which is arranged immediately below the cultivation shelves  4  that form the cultivation plane Li and is structured to collect and contain the liquid that falls during spraying performed on the cultivation plane Li itself ( FIGS. 1, 3, 4, and 5 ). 
     The suction system  12  also comprises, for each cultivation plane Li, at least one suction duct  15 , which is arranged below the cultivation plane Li so as to be inside the liquid collection basin  14  and extends along a longitudinal axis B approximately parallel to the extension direction K and to the axis A ( FIG. 5 ). The Applicant has found that the use of the suction duct  15  inside each liquid collection basin  14  makes it possible to quickly empty each basin in a selective way, independently of the other planes and independently of the length of the plane itself. In addition, the synergistic use of the liquid collection basin and of the suction duct in the same, makes it possible to size the length of the system as desired, eliminating, in this way, any limits to the maximum dimensions of the same. 
     According to a preferred embodiment shown in  FIGS. 1-7 , the suction system  12  comprises a suction duct  15  that preferably extends for the whole length of the corresponding cultivation plane Li. 
     According to one embodiment shown in  FIG. 7 , the suction duct  15  has suction through-openings  16  through which the liquid contained in the liquid collection basin  14  is sucked upon into the suction duct  15 . The suction through-openings  16  may be made in the suction duct  15  according to a longitudinal distribution so as to be able to recuperate the liquid (indicated with FL in  FIG. 4 ) in the liquid collection basin  14  for the whole length of the same. For example, the suction through-openings  16  may be made below on the side of the suction duct  15  facing/adjacent to the bottom of the liquid collection basin  14  and/or laterally to the same. The suction through-openings  16  may, preferably, be circular and be approximately 6 mm in diameter. 
     According to a preferred embodiment, the liquid collection basin  14  extends below the cultivation shelves  4  of a cultivation plane Li for the whole length of the same (along the direction K). The liquid collection basin  14  preferably comprises a thin layer in waterproof material that is very flexible. The Applicant found it convenient to use a film of waterproof fabric. For example, the Applicant found it convenient to use a flexible sheet based on plastic material (PVC) since it is extremely simple to mount and is economic. Laboratory tests performed by the Applicant found it was convenient to use, for example, a flexible, waterproof sheet called POLYPLAN Tent Opaque® marketed by SATTLER®. 
     The layer is preferably made of material that is not transparent to light, so as to prevent it from illuminating the plants&#39; roots. 
     However, it remains understood that this invention is not limited to a layer of very flexible waterproof material. For example, according to one embodiment (not illustrated), the layer could be based on stiff material. For example, according to one embodiment (not illustrated), the layer could be based on metal or plastic material. For example, according to one embodiment (not illustrated), the liquid collection basin could comprise a stiff recipient or container, obtained, for example, through moulding, open above that extends below the cultivation shelf  4 . 
     The liquid collection basin  14  is preferably, approximately, horizontal. With reference to the embodiment shown in  FIGS. 4 and 6 , the liquid collection basin  14  has two larger sides  14   a  that extend parallel to the direction K and are coupled to the vertical columns of the frame  3  at the longitudinal sides of the cultivation shelves  4 . The two edges of the layer that form the two larger sides  14   a  laterally delimit the bottom wall of the liquid collection basin  14 . The larger sides  14   a  can, preferably, be coupled to the frame  3  via opposite, lateral retention guides, which are fixed to the frame  3  and inside of which the two larger sides  14   a  of the liquid collection basin  14  are inserted by sliding. In the embodiment shown in  FIG. 4  wherein the liquid collection basin  14  comprises the layer, the larger sides  14   a  may be enlarged, i.e. comprise a cross section that is preferably circular and has a diameter that is greater than the thickness of the layer, while the guides may have a cross section that approximates (upwards) the diameter of the two larger sides  14   a.    
     In the embodiment shown in  FIGS. 3 and 4 , the bottom wall of the liquid collection basin  14  has a cross section in the direction K approximately arched or semi-circular. With reference to  FIG. 5 , the liquid collection basin  14  has, in addition, on the two opposite longitudinal ends, two containment walls  14   b  that are transverse to the direction K. The two containment walls  14   b  close the two openings present at the ends of the bottom wall so as to form the liquid collection recipient. The two containment walls  14   b  extend approximately vertically and are designed to form the two smaller sides of the basin. The two walls  14   b  are preferably constructed via the same layer of the bottom wall of the liquid collection basin  14  and are joined (for example welded along the corresponding edges) to the latter so as to form a single body capable of containing the liquid. 
     The larger sides  14   a  that form the upper edges of the bottom wall and, preferably, the lower edges of the two walls  14   b  are, preferably, approximately coplanar (horizontally) and are basically arranged close to the, resting on the lower surface  4   a  of the cultivation shelves  4  at, approximately, the outer sides of the latter, so as to prevent, on the one hand, the nebulised liquid from coming out of the frame  3  and to facilitate, on the other, its collection in the basin  14 . 
     With reference to  FIGS. 4, 5, 6, and 7 , according to a possible embodiment, the suction duct  15  extends straight centrally for the whole length of the cultivation shelf  4  and is arranged at the, adjacent to the, portion mainly below the liquid collection basin  14  so as to be able to empty it completely. 
     With reference to the embodiment shown in  FIG. 1 , the suction system  12  may comprise, in addition, a suction assembly  20  that is hydraulically connected to the suction ducts  15  to suck up, selectively, the liquid contained in the liquid collection basin  14 . The suction assembly  20  may preferably comprise hydraulic suction pumps (not illustrated), recovery basins (not illustrated), filters (not illustrated), and solenoid valves  21 . The solenoid valves  21  can preferably be arranged along the suction ducts  15  and are designed to close/open them on the basis of the respective commands/signals supplied by the electronic control unit  11 . The suction pumps can be selectively driven by the electronic control unit  11  based on a pre-set suction programme. Electrical/electronic liquid detection sensors may be provided in the liquid collection basins  14  (not illustrated). The operation of sucking up the liquid contained in each liquid collection basin  14  can be controlled based on the detection of the electrical/electronic liquid detection sensors (not illustrated) present in the liquid collection basins  14  themselves. 
     According to one embodiment shown in  FIGS. 6 and 7 , the delivery ducts  7  and the suction duct  15  can be supported inside the liquid collection basin  14 , via the support rods  22  that extend transverse to the extension direction K, below the cultivation shelves  4 , and are rigidly fixed to the upper ends on the vertical columns of the frame  3 . The support rods may be equidistant from each other along the direction K. 
     The support rods  22  can preferably be basically arched, so as to approximately follow the inner surface of the bottom wall of the liquid collection basin  14  and are provided with snap fastening elements, for example tube-holder devices  23 , in which the delivery ducts  7  and the suction duct  15  are inserted. The support rods  22  can preferably keep the layer of the liquid collection basin  14  taut towards the outside. The support rods  22  preferably support the suction duct  15  below the delivery ducts  7  and approximately close to the bottom of the basin  14 . 
     The operation method for the cultivation system  1  can be easily deduced from the above and will not be described further except to specify that it essentially comprises the steps of: collecting the dispersed nebulised liquid in the liquid collection basin  14  arranged immediately below the support shelves  4  of the cultivation plane Li, and sucking up the liquid contained in the liquid collection basin  14  through the suction duct  15  that extends inside the liquid collection basin  14  along the longitudinal axis B parallel to said direction K. 
     The cultivation system described above is advantageous in that it eliminates clogging conditions and therefore ensures that the cultivation environment is very clean, with all the advantages this entails in terms of reducing the risk of contamination caused by stagnation of the dispersed liquid. 
     The cultivation system also eliminates the need to place a common collection basin below the first cultivation plane, to collect the liquid that drains by gravity from the upper basins and therefore allows the minimum height of the first cultivation plane to be reduced, thus optimising the space that is occupied by the basins themselves in the prior art. 
     Lastly, it is clear that modifications and variants may be made to the cultivation system and method described and illustrated herein while remaining within the scope of the present invention defined by the appended claims.