Patent Document

BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to plant pot watering systems and irrigation systems and, more particularly, to systems for controlling the level of irrigation.  
         [0003]     2. Description of the Prior Art  
         [0004]     In potted plant production, irrigation is often a problem, as the stored water volume within a plant pot is rapidly depleted as the plant grows, and thus the plant needs to be regularly monitored and watered by workers. Such a process is both very expensive as well as time consuming. In addition, no plant pot irrigation monitoring system is currently available which is accurate enough to take into account the fact that different plants, or the same plants at different growth stages, have different cycles of growth, and therefore different rates of water consumption. Therefore, there is a need for a plant pot and soil watering system which maintains a constantly available water supply and which diminishes watering frequency. There is also a need for a system which permits salt leaching. A problem frequently associated with prior art plant pot devices using capillary action to drive the water into the substrate is that very little leaching is possible due to the inherent design of the system. Furthermore, there is a need for a system which permits steam sterilization to prevent and limit the spread of disease from the substrate which supports the plant.  
       SUMMARY OF THE INVENTION  
       [0005]     It is an object of the present invention to overcome, or substantially overcome, the disadvantages of the prior art.  
         [0006]     It is another object of the invention to provide a plant pot which stores a volume of water for ready usage, and which dispenses water to the plant in a regular metered fashion.  
         [0007]     It is another object of the invention to provide a plant pot which contains a porous medium, such that dispensing of the water is controlled by capillary movement, and air entry principles.  
         [0008]     It is a further object of the invention to provide a plant pot which permits both salt leaching and steam sterilization.  
         [0009]     According to the invention, there is provided a plant pot which contains a fluid supply reservoir on the periphery of the pot. The fluid supply reservoir is in fluid communication, with an external source, or can be filled manually by removing a stopper which covers a opening at the top portion of the pot. The fluid supply reservoir defines a wall within the inner portion of the pot, and lower portion of this wall contains a porous membrane which permits fluid communication between the fluid supply reservoir and the inner portion of the pot. The fluid thus communicates with a substrate contained within the pot, and is controlled by capillary action, which is facilitated by an air entry tube near the base of the pot, or by the porous membrane which permits the fluid to flow from the fluid supply reservoir to the water absorbent substrate. Drainage holes in the bottom portion of the pot permit an excess of water to be drained, and thus maintain an appropriate water supply within the porous substrate supporting the plant. The present invention also defines a dripper which permits fluid from the fluid reservoir to drip on to the plant supporting substrate so as to permit salt leaching, and prevent the build up of harmful salts within the substrate.  
         [0010]     Therefore, in accordance with the present invention, there is provided a device for watering a substrate, comprising: a reservoir having a cavity for receiving water therein, a hermetically closeable inlet portion in fluid communication with the cavity for filling the cavity with water, and an outlet portion in fluid communication with the cavity, the reservoir being adapted to be positioned such that the outlet portion is buried by the substrate; and a porous member received in the outlet portion so as to be in contact with the substrate such that water flows out of the cavity through the porous member and into the substrate as a result of a capillary action of the substrate to create a negative pressure differential between the cavity and the substrate, the porous member having pores ranging between 10 and 600 micrometers in size to cause a flow of water from the cavity to the substrate as a function of a given value of said negative pressure differential.  
         [0011]     The negative pressure differential at which air enters into the cavity is a function of the pore size of the porous member, and this results in a volume of water flowing form the cavity to the substrate.  
         [0012]     Further in accordance with the present invention, there is provided an irrigation system for watering a substrate, comprising a pipe having a longitudinal dimension, a hermetically closeable inlet portion adapted to be connected to a water supply, a passageway extending generally throughout the longitudinal dimension and in fluid communication with the inlet portion such that water can fill the passageway, and openings in fluid communication with the passageway such that water in the passageway can exit the pipe through the openings, the pipe being adapted to be at least partially buried in the substrate with the openings facing downwardly, and at least one porous member secured to an outer periphery of the pipe so as to cover the openings and be in contact with the substrate such that water flows out of the passageway through the openings and the porous member and into the substrate as a result of a capillary action of the substrate. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]     In order that the invention may be more readily understood and put into practical effect, reference will be made to the accompanying drawings, in which:  
         [0014]      FIG. 1  is a side view of the plant pot of the present invention;  
         [0015]      FIG. 2  is a side view of a variant embodiment having an independent water supply;  
         [0016]      FIG. 3  is a schematic cross-sectional view of an irrigation system in accordance with the present invention;  
         [0017]      FIG. 4  is a schematic cross-sectional view of a porous cup to be used with the irrigation system;  
         [0018]      FIG. 5  is a schematic bottom plan view of the irrigation system with a porous membrane removed; and  
         [0019]      FIG. 6  is an enlarged cross-sectional view of a portion of the irrigation system. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0020]     Reference is made to  FIG. 1 , which discloses a plant pot  1 . This plant pot may be any conventional plant pot  1 , having any known shape, and constructed from materials well known to one of ordinary skill in the art. Contained within the plant pot is a dividing wall  5 , which defines an outer fluid reservoir  20  separate from an internal portion  22  of the plant pot. At the top portion of the outer fluid reservoir  20  is an opening closed by a stopper  7  which, when removed, permits either filling or emptying of the outer fluid reservoir  20 . An external water supply hose  10  connects to the outer fluid reservoir  20  so as to fill the reservoir  20  with the appropriate fluid when desired. It is pointed out that the stopper  7  is optional for filling the outer fluid reservoir  20  as this may be executed through the external water supply hose  10 . On the lower portion of the dividing wall  5  is a porous membrane  8  which permits fluid communication between the fluid reservoir  20  and the internal portion  22  of the plant pot  1 . An air entry hole  9  is optionally provided to communicate ambient air to the outer fluid reservoir  20 . This air entry hole  9  can be used to control the suction (i.e., negative pressure differential between the outer fluid reservoir  20  and the substrate  2 ) within the outer fluid reservoir  20 , to ensure a continual flow of water from the outer fluid reservoir  20  to the internal portion  22  of the plant pot  1 . This flow of water occurs when the suction in the substrate  2  becomes temporarily greater than that in the outer fluid reservoir  20 .  
         [0021]     Contained within the internal portion  22  of the plant pot  1  and externally of the outer fluid reservoir  20  is a plant supporting substrate  2  which supports a growing plant  3 , and which typically includes plant roots at its lower end. Fluid from the outer fluid reservoir  20  is drawn to the plant roots through the porous membrane  8 , and as a result of the capillary action created by the air entry hole  9 , porous membrane  8 , and porous substrate  2 . At the time of filling, positive pressure may exist within the reservoir and excess fluid thus flows through the porous membrane  8 . Any excess fluid which is drawn into the internal portion  22  of the plant pot  1  is drained away by drainage holes  4  at the lower end of the plant pot  1 .  
         [0022]     As the outer fluid reservoir  20  is airtight aside from the porous membrane  8 , the suction exerted by the substrate  2  on the water  6  of the outer fluid reservoir  20  will create a negative pressure in the outer fluid reservoir  20 . It is pointed out that the porous membrane  8  will be saturated with water blocking the pores, during the transfer of water from the reservoir  20  to the substrate  2 .  
         [0023]     The negative pressure in the reservoir  20  will reach an equilibrium with the capillary suction of the substrate  2 , at which point air in the substrate  2  will be sucked into the reservoir  20  to continuously balance the pressure differential between the reservoir  20  and the substrate  2 . The air passing through the pores to reach the reservoir  20  will free the pores, at least momentarily, to let water transfer from the reservoir  20  to the substrate  2 . The pressure differential between the outer fluid reservoir  20  and the substrate  2  is a function of the pore size of the porous membrane  8 , and the air entry in the outer fluid reservoir  20  occurs at a constant pressure differential. It has been experimentally determined that the suction exerted on the substrate of a pot is preferably maintained between 0.5 and 10.0 kPa, with an average of about 5 kPa. For such a range of suction to be attained, the porous membrane  8  must have pores ranging between 30 and 600 micrometers, with the greater pore sizes being matched with suction of lower magnitudes.  
         [0024]     For cultivation fields, the suction exerted on the substrate is preferably maintained between 5.0 and 30.0 kPa. Corresponding pore size of a porous membrane appropriate for this range goes from 10 to 60 micrometers. Once more, there is an inversely proportional relation between the magnitude of suction pressure and the pore size of the porous membrane.  
         [0025]     Examples of materials used for the porous membrane  8  include clay, porous rocks/stones and nylon membranes. Also, various fritted materials having a suitable porosity (e.g., equivalent to the pore sizes described previously) can be used. The nylon membranes are typically used with a geotextile membrane that helps redistributing water, while the nylon membrane also acts to protect the geotextile from root penetration.  
         [0026]     The air entry hole  9  is typically a pin hole (and there can be a plurality of such pin holes) which is optionally provided to enhance the water flow from the reservoir  20  to the substrate  2 . As a result of the small area of the air entry hole  9 , a slight compensation is performed by air entering therethrough when water flows from the reservoir  20  to the substrate  2 . In embodiments where a positive pressure differential must be created between the reservoir  20  and the substrate  2 , as will be described below, the reservoir  20  must be exempt of any such air entry hole  9 .  
         [0027]     The plant pot  1  also optionally includes a dripper  11 , and a closeable, one-way flow valve  12  in fluid communication with the dripper  11 , which allows a leaching solution (e.g., water) from the outer fluid reservoir  20  to flow to the substrate  2 . The dripper  11  is connect ed at one end to the outer fluid reservoir  20  and at its opposite end to the plant supporting substrate  2 . The purpose of the dripper  11  is to permit a leaching of salt accumulations from the substrate  2 , and thus prevent a build up of such salts in the area of the substrate  2  which contacts the plant roots. As a first alternative embodiment (not shown), the leaching can be carried out by filling the outer reservoir  20  with an external supply of leaching solution incoming from either the external water supply hose  10  or from a manual fill through the opening that is selectively closed by the stopper  7 . A positive pressure in the outer fluid reservoir  20  will cause a flow of leaching solution to the substrate  2 . The leaching solution may be water, or other liquid substances known in the art which are capable of leaching salt and salt solutions from substrate. For such an embodiment, the reservoir  20  must be exempt of any such air entry hole  9 .  
         [0028]     In a second alternative embodiment (not shown), the dripper  11  can be replaced with a series of external drippers connecting an external supply of leaching solution with the internal portion  22  of the plant pot  1 . The plant pot  1  of the present invention also may utilize steam, for the purposes of preventing the spread of disease from potted substrates. Steam can be introduced from an external source and into the supply hose  10 , while the one-way valves on the drippers are maintained closed, resulting in the introduction of steam into the outer fluid reservoir  20  and into the plant supporting substrate  2  via the porous membrane  8 . Steam may also be introduced through mechanisms independent of the plant pot  1  itself, or by such means as known to one of ordinary skill in the art. For such an embodiment, the reservoir  20  must be exempt of any such air entry hose  9 .  
         [0029]     The fluid supply reservoir can be made independently of the pot itself, such as tube-shaped reservoir  25  in  FIG. 2  or as irrigation system  30  illustrated in FIGS.  3  to  6 . The reservoir  25  is an independent water supply that is made of any impermeable material and can have various configurations. The reservoir  25  has a porous membrane  17  that respects the above-described criteria of pore size and material for a generally constant air entry therethrough. The reservoir  25  still can have a dripper with a one-way valve  13 , an external water supply  14 , a stopper  15  and an optional air entry  16 . Some of these items are facultative though as the system can operate with the porous membrane  17  and the stopper only  15 . The stopper  15  can be equipped with a one-way stop valve  18  which allows filling the water supply reservoir  25  externally by hand or with any watering device having a pressure high enough to displace the valve  18 , thereby filling the reservoir. The independent water supply system will function exactly as that described in  FIG. 1 .  
         [0030]     A plurality of the reservoirs  25  can be interconnected by a network of water supplies  14 . Therefore, a single water source could feed all reservoirs  25 , for instance each positioned in a different plant pot, to greatly reduce watering logistics. Alternatively, such a system can be used in a cultivation field to supply water to different locations.  
         [0031]     Referring to FIGS.  3  to  6 , an irrigation system  30  is illustrated and is an alternative embodiment to the network of reservoirs  25 . The irrigation system  30  is conceived for being used in cultivation fields. The irrigation system  30  consists of a pipe  31 . In  FIG. 3 , a segment of the pipe  31  is illustrated, and the pipe  31  is substantially longer than that segment. The pipe  31  is shown buried in a substrate or soil S.  
         [0032]     The pipe  31  has an inlet end  32  and an outlet end  33 , and defines a passageway  34  such that fluid can be conveyed from the inlet end  32  to the outlet end  33 . Openings  35  are defined in a bottom portion of the pipe  31  and are spaced from one another on the full length of the pipe  31 . Fluid in the passageway  34  can exit the pipe  31  through the openings  35 . Preferably, the pipe  31  is semi-rigid, whereby its flexibility will be used to create various patterns in the soil S.  
         [0033]     Porous membranes  36  are secured to the bottom portion of the pipe  31  so as to separate the openings  35  from the soil S. The porous membranes  36  follow the above-described criteria of pore size and material for a generally constant air entry value within the pipe. The porous membranes  36  mold the bottom portion of the pipe  31 , on the full length of the pipe  31 , and are preferably separated from one another, so that water can flow through each opening  35  independently (as opposed to a single porous membrane running the length of the pipe  31 ).  
         [0034]     The irrigation system  30  is used in similar fashion to the fluid reservoir  20  of  FIG. 1  and the reservoir  25  of  FIG. 2 . Namely, once the pipe  31  is buried in the soil S, the passageway  34  is filled with water and the inlet end  32  and outlet end  33  are sealed. The soil S will exert a capillary pressure on the water of the passageway  34 , whereby a negative pressure will be created in the passageway  34  as water exits therefrom. At a point of equilibrium, air will free the saturated pores to cause a constant water/air exchange.  
         [0035]     It is possible to increase a rate of water/air exchange by providing grooves  37 , as illustrated in  FIGS. 5 and 6 , on an outer periphery of the pipe  31  and in fluid communication with the openings  35 , and a geotextile  38 . The grooves  37  and the geotextile  38  will increase the flow of water from the passageway  34  to the porous membrane  36 , preferably a nylon membrane in this case. The geotextile  38  must be fully covered by the porous membrane  36  along its length so as to be sandwiched between the porous membrane  36  and the outer periphery of the pipe  31 . The porous membrane  36  will protect the geotextile  38  from root penetration.  
         [0036]     Preferably, the passageway  34  is provided with rigid dividers  39  between each adjacent pair of openings  35 . The dividers  39  will ensure that water is supplied to substantially every opening  35  in the event that the pipe  31  must be slanted with respect to the horizon.  
         [0037]     Referring to  FIG. 4 , an alternative embodiment to the porous membrane  36  is illustrated. A porous cup  40  has a hole  41  that is positioned opposite one of the openings  35  so as to receive water therefrom. The porous cup  40  is disc-shaped, and does not affect the flexibility of the pipe  31 , as adjacent cups  40  are independent from one another.  
         [0038]     The foregoing description of the preferred embodiments of the invention has been presented for the purposes of illustration and description. It is not intended to be exhaustive, or to limit the invention to the precise form disclosed. It is intended that the scope of the invention be limited not by this detailed description, but rather by claims appended hereto.

Technology Category: 1