Patent Publication Number: US-2007113472-A1

Title: Aeroponic system and method for plant propagation

Description:
CROSS REFERENCE TO RELATED APPLICATION  
      This application claims priority to U.S. Provisional Patent Application No. 60/732,812, filed Nov. 2, 2005, the contents of which are hereby incorporated by reference. 
    
    
     BACKGROUND  
      Growing and sustaining plants aeroponically involves supplying a nutrient solution to the roots of the plants, such as by spraying. The solution may include water, fertilizers and other nutrients. Optimal growth and the survival of the plants require that the roots of the plants be kept within a particular temperature range. This temperature range may be lower than is required for the portion of the plant above the roots. This parallels the situation in nature in which the stem and leaves of the plant are exposed to the air, and the roots of the plant are located in the ground, which is generally at lower temperature than the air.  
      Thus, some aeroponic growing devices include some type of refrigeration to cool the nutrient solution before it is supplied to the roots of the plants. The refrigeration for these aeroponic devices is not located with the reservoir that holds the solution, but is located remotely from the other portions of the growing device. In addition, many of these devices constantly spray solution onto the roots of the plants, leading to root destruction from causes such as root-rot.  
     SUMMARY  
      An aeroponic system for propagating plants and/or seeds includes a chamber, cooling system and a nutrient delivery system. The cooling system is coupled to the chamber directly or indirectly. The chamber includes a top portion for supporting plants and/or seeds. For example, the top portion may include orifices onto which holders may be connected. A holder generally supports a plant so that the roots of the plant are located within the chamber and the remainder of the plant is located outside the chamber. In addition, the chamber holds a nutrient solution, which is delivered to the plants and/or seeds by the nutrient delivery system and maintained within a predetermined temperature range by the cooling system. The system may be adapted to propagate various types of seeds and plants. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The invention can be better understood with reference to the following drawings and description. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. Moreover, in the figures, like reference numerals designate corresponding parts throughout the different views.  
       FIG. 1  is an isometric view of an aeroponic system.  
       FIG. 2  is a cross-sectional view of the aeroponic system of  FIG. 1  viewed along line A-A.  
       FIG. 3  is an expanded cross-sectional view of a portion of the aeroponic system of  FIG. 2 .  
       FIG. 4  is a cross-sectional view of an aeroponic system.  
       FIG. 5  is a cross-sectional view of an aeroponic system.  
       FIG. 6  is a top view of the aeroponic system of  FIG. 5  with the top portion removed. 
    
    
     DETAILED DESCRIPTION  
       FIGS. 1 and 2  illustrate an example of an aeroponic system (also referred to as “the system” or “this system”)  100 . The system  100  generally includes a chamber  110 , a cooling assembly  140 , and a nutrient delivery system  150 . The system  100  may accommodate a number of plants  200  or seeds (not shown). Although only one plant  200  is shown in  FIGS. 1 and 2 , the system  100  may be designed to accommodate any number, type and combination of plants and seeds. The descriptions that follow apply to any such design.  
      The chamber  110  supports the plant  200  and holds a liquid that is supplied to the plants. In some constructions, the liquid is a nutrient solution designed specifically for the nutritional needs of the plants. The composition of the nutrient solution may vary with the particular needs of the type of plant supported by the system  100 . The cooling assembly  140  cools the solution to a solution temperature within a solution temperature range, and the nutrient delivery system  150  delivers the nutrient solution to the roots of the plant  200 , or to a seed (not shown).  
      The cooling assembly  140  may be coupled to the chamber  110 , either directly or indirectly, so that the cooling assembly  140  and the chamber  110  may be moved together, thus making the system  100  portable. The system  100  may also include a support  130  to which the chamber  110  and the cooling assembly  140  may be coupled. The support  130  may include a plate  132  to which the chamber  110  and the compressor  142  may be coupled using screws, bolts and/or the like. In this manner the support  130  provides a structure that indirectly couples the cooling assembly  140  to the chamber  110 . The support  130  may also include one or more legs  134  located under the plate  132  that maintains the plate  132  above the surface on which the system  100  rests. This facilitates easier lifting of the system  100  by allowing the underside of the plate  132  to be engaged. The support  130 , including the plate  132  and the legs  134 , may include any type of suitable material such as metal or wood. For example, the materials used for the plate  132  and/or the legs may include aluminum.  
      The chamber  110  generally includes one or more walls  162 ,  164 ,  166 ,  168 ,  170 ,  172 , and  174 , and a top portion  120  that define a reservoir  111  within. The chamber  110  of  FIGS. 1 and 2  includes a generally rectangular shape. However, the chamber  110  may include any shape. The chamber  110  may also include an overhanging portion  118 , under which the cooling assembly  140  may be located. Such an arrangement reduces the footprint of the system  100 .  
      The top portion  120  provides support for one or more plants and/or seeds. The top portion  120  may include a plurality of orifices  122  so that plants, such as plant  200 , may be positioned so that their roots  202  are located within the chamber  110  and their remaining parts (such as the stem, leaves, flowers, and/or vegetables) are located outside the chamber  110 . The top portion may include a plastic material such as high density polyethylene (HDPE).  
      The top portion  120  may be adapted to support different types of plants. The distance between the orifices may be selected to provide sufficient room for a particular type of plant to propagate while supporting as many plants as possible.  
      In addition, the top portion  120  may include a holder for supporting a plant or seed. The holder may include a lower holder  124 . This lower holder  124  may support one or more seeds and/or the roots  202  of a plant  200  inside the chamber  110 , and may include holes, a mesh, a basket or the like that allow the roots  202  to extend into the reservoir  111  as the roots  202  grow. The lower holder  124  may hold rock wool or other material or materials in which a seed can germinate. In another example, the holder may include an upper holder  126  that provides support to the upper portion of the plant  200  outside the chamber  110 . The upper holder  126  may include a cone shape, as shown in  FIG. 2 , but may include other shapes as well. The upper holder  126  may include holes, mesh or other structure through which the leaves and/or other portions of the plant may extend as the plant grows.  
      An example of a manner in which an upper holder  126  and a lower holder  124  may be attached to the top portion  120  is shown in  FIG. 3 . In this example, the upper holder  126  and the lower holder  124  are attached to the top portion  120  by fasteners  127 . To couple the upper holder  126  to the top portion  120 , the fasteners  127  may be inserted from underneath the top portion  120 , through the top portion  120  and into the upper holder  126 . To couple the lower holder  124  to the top portion  120 , loops  125  may be coupled to the lower holder  124  and arranged around the fasteners  127 . Alternately, the loops  125  may be an extension of the lower holder  124 . For example, if the lower holder  124  includes a wire mesh, wire from the mesh may be used to form the loops  125 . The loops  125  may be arranged around the fasteners  127  before or after the fasteners  127  are inserted through the top portion  120 . In another example, the fasteners  127  may be inserted from above the top portion  120 , through the inner wall of the upper holder  126  and through the top portion  120 . To couple the lower holder to the top portion  120 , nuts and/or washers (not shown) may be coupled to the fasteners  127  from underneath the top portion  120 . The upper and lower holders  126 ,  124  may be coupled to the top portion  120  using other configurations as well, including without limitation clamps, clips, adhesives, welding, and the like.  
      The top portion  120  may include the lower and/or upper holders  124 ,  126  or may not contain any holder. For example, if tomato plants are to be propagated, the top portion  120  may include the lower and upper holders  124 ,  126 . In another example, if lettuce is to be propagated, the top portion  120  may not include any holder. Further, the system  100  may include multiple top portions  120 , each adapted to accommodate a different type of plant or seed. For example, a first top portion  120  may be provided with orifices  122  spaced apart from one another by a first distance suitable for propagating a certain type of plant. A second top portion  120  may also be provided with orifices  122  spaced apart from one another by a second distance, different than the first distance, for propagating a different type of plant. In this manner, the system  100  may be converted from a configuration adapted for the propagation of one type of plant to a configuration adapted for the propagation of a different type of plant by replacing one top portion  120  with another. Similarly, a single top portion  120  may be provided with two or more groups of orifices  122 , each orifice in a given group spaced apart from the other orifices in the group by a distance suitable for propagating a specific type of plant. In this regard, two or more different types of plants may be propagated using the same top portion  120 . In some constructions, the top portion  120  may include a lightweight material, such as plastic, which may add to the ease of such replacement.  
      Referring to  FIG. 2 , the top portion  120  may be supported by the top of one or more of the walls  162 ,  164 ,  172 ,  174 , or by an edge  113  located near the top of one or more of the walls, depending on the shape of the chamber  110 . The edge  113  may run continuously along the approximate top of some or all of the vertical walls  162 ,  164 ,  172  and  174  or be positioned in discrete locations. The edge  113  may include a material such as steel, stainless steel or sheet metal. For example, the edge  113  may include a food-safe material, such as stainless steel. In some constructions the walls  162 ,  164 ,  172 ,  174  include an insulating layer  114  that may include a rigid insulation board, such as extruded polystyrene, or other suitable insulating material. Furthermore, the outer surface of some of the walls, may include a weather-resistant covering, such as sheet metal. To reduce radiant heat absorption by the system  100  (e.g. from sunlight), the outer surfaces of the chamber may include or be painted or otherwise colored a light color, such as white. In some constructions, the reservoir  111  includes a lining  116 . The lining  116  may include a water-tight material, such as PVC.  
      The cooling assembly  140  maintains the liquid stored in the reservoir  111  within a desired temperature range. In this regard, plant roots and seeds may be maintained at a temperature that is lower than the temperature at which the remainder of the plant is maintained. The specific temperature range at which the roots and seeds are maintained will depend, at least in part, upon the surrounding environment in which the system  100  is placed, and upon the type of plants and/or seeds that are being propagated. For example, to propagate lettuce, the desired temperature may be in the range of about 60 to about 80 degrees Fahrenheit, or, more preferably, in the range of about 64 to about 76 degrees Fahrenheit, or even more preferably, in the range of about 68 to about 72 degrees Fahrenheit.  
      The cooling assembly  140  may include a compressor  142 , evaporator line  144 , and a thermostat  146 . The evaporator line  144  may be positioned in the chamber  110 . For example, as shown in  FIG. 2 , the evaporator line  144  goes thru a wall  168  in the chamber  110  and may be located between the insulating layer  114  of the wall  168  and the lining  116 . The wall  168  may include an orifice (not shown) through which the evaporator line  144  enters the chamber  110 . To cool the liquid in the reservoir  111 , as well as the reservoir  111  itself, the compressor  142  compresses a coolant, such as those used in refrigeration, and supplies the compressed coolant to the reservoir  111  via the evaporator line  144 . The compressed coolant removes the heat from the reservoir  111 , and returns to the compressor  142 . To provide more efficient and/or effective heat removal, the cooling assembly  140  may further include a cooling plate  491  (see  FIG. 6 ). The cooling plate  491  includes a thermally conductive material and is located between the insulating layer  114  of the wall  168  and the lining  116 . The evaporator line  144  runs through the cooling plate  491 , thereby cooling the cooling plate  491 . The cooling plate  491  increases the amount of surface area available to remove heat from reservoir  111  and the liquid. To obtain or maintain the liquid within a desired temperature range, the thermostat  146  regulates operation of the evaporator  142 . For example, the thermostat  146  may include or be in communication with a temperature sensor (not shown), which measures the temperature of at least one of the reservoir  111  and the liquid held by the reservoir  111 . The temperature, as measured by the temperature sensor, is monitored by the thermostat  146  so that when the temperature reaches or rises above a maximum temperature, the thermostat  146  turns on the compressor  142 . Similarly, when the temperature reaches or falls below a minimum temperature, the thermostat  146  turns off the compressor  142 . The thermostat  146  may include a gauge  180  ( FIG. 1 ) that displays the sensed temperature, and an adjustment device, such as a dial  181 , for selecting a desired median solution temperature. It should be appreciated that the degree of variation of temperature (e.g. the temperature range between the maximum temperature and the minimum temperature) about the desired median solution temperature will depend upon, among other things, the accuracy and precision of the thermostat  146 , the accuracy and precision of the temperature sensor, the rate at which the compressor  142  is able to respond to the on/off commands provided by the thermostat  146  to compress the coolant, and the efficiency with which heat is transferred from the liquid and/or the reservoir  111  to the coolant.  
      The nutrient solution may be delivered to the roots  202  by a nutrient delivery system  150 . The nutrient delivery system  150  may include a pump  152 , one or more pipes or tubes  154  and one or more sprinkler heads  156 . The pump  152  may include a magnetic pump. The sprinkler heads  156  are coupled to the tubes  154 , which may include, for example, one or more PVC pipes. During operation, the pump  152  pumps the nutrient solution from the reservoir  111  into the tubes  154 . The pressure from the pump  152 , causes the solution to flow through the tubes  154  to the sprinkler heads  156 . The sprinkler heads  156  disperse or spray the nutrient solution into the reservoir  111  for delivery to the plant roots  202  or to seeds in the lower holders  124 .  
      The system  100  may include one or more controls and/or displays. For example, the system  100  may include an indicator  182 , such as a light, that indicates when the system  100  is receiving electrical power. The system  100  may include an indicator  183 , in communication with a level sensor (not shown) in the reservoir  111  that indicates when the nutrient solution reaches a specific level. To control the delivery of the nutrient solution to the roots  202  and/or seeds, the system may include a timer  186 . The timer  186  may be in electromagnetic communication with the pump  152  of the nutrient delivery system  150  via a wired or wireless communications. The timer  186  may turn on the pump  152  at predetermined intervals for a predetermined time period. The intervals and time period may be selected according to the type of plant or seed that is to be propagated in the system  100 . For example, for propagating fully grown lettuce, the timer may turn on the pump  152  for about three minutes (the time period) every thirty minutes (the time interval). The timer  186  may include two separate controls  186  (as shown in  FIG. 1 ), one for adjusting the “on” time period, and one for adjusting the time interval. Alternately, the timer  186  may include a single control by which the time period may be adjusted as a percentage of the time interval.  
       FIG. 4  illustrates another example of an aeroponic system or “system”  300 . The description provided above in connection with the aeroponic system  100  shown in  FIGS. 1 and 2  applies to the aeroponic system  300  of  FIG. 4 , except as described below. Components of the system  300  that are similar to components of the system  100  have been given the same reference numeral, increased by two-hundred. The system  300  shown in  FIG. 4  is similar to the system  100  shown in  FIGS. 1 and 2 . However, in addition to overhang portion  318 , the chamber  310  shown in  FIG. 4  includes a second overhang portion  319 . This second overhang portion  319  reduces the size of the reservoir  311 , and thus the amount of nutrient solution that may be stored in the reservoir  311 . Because the amount of nutrient solution stored in the reservoir  311  is reduced, the energy needed by the cooling assembly  340  to cool the nutrient solution is also reduced. For example, the second overhang portion  319  may include dimensions that reduce the capacity of the reservoir  311  by 30-40 gallons. Wall  364 , which may extend to the support  330 , provides stability for the system  300 . Further, alternate or additional walls may also extend to the support  330 , so that, for example, the system  300  appears virtually identical to the system  100  of  FIG. 1  from the outside. As shown in  FIG. 4 , the tubes or pipes  354  may include a different arrangement than that of the tubes or pipes  154  shown in  FIG. 1  to accommodate the second overhang portion  319 .  
       FIGS. 5 and 6  illustrate another example of an aeroponic system or “system”  400 . The description provided above in connection with the aeroponic system  300  shown in  FIG. 4  applies to the aeroponic system  400  of  FIGS. 5 and 6 , except as described below. Components of the system  400  that are similar to components of the system  100  have been given the same reference numeral, increased by three-hundred. In addition to the first pump  452 , which moves the nutrient solution from the reservoir  411  into the tubes  454 , the system  400  includes a second pump  453 . The second pump  453 , which may include a magnetic pump, moves the nutrient solution over the cooling plate  491  to provide more effective and/or efficient control of the temperature of the solution. As previously discussed, the evaporator line  444  runs through the cooling plate  491 , both of which are generally located between the insulation board of wall  468  and the liner  416 . The temperature of the nutrient solution may be controlled by a thermostat and a probe in, for example, the manner previously discussed. In addition, to more quickly cool the nutrient solution, the second pump  453  circulates the nutrient solution over the cooling plate  491 . The second pump  453  may run continuously or be switched on and off approximately simultaneously with the condenser  442 .  
      The second pump  453  moves the nutrient solution from the reservoir  411 , past the cooling plate  491  and back into the reservoir  411  via a tube  490 . The tube  490  goes through the liner  416  so that it comes into contact with the cooling plate  491 . To prevent nutrient solution from leaking between the liner  416  and the walls of the system  400 , the liner  416  may be sealed around the tube  490 . To provide this seal, a hole having a diameter smaller than that of the tube  490  may be made in the liner  416 . Thus, when tube  490  is inserted into the hole, the liner  416  may stretch to accommodate and provide a seal around the tube  490 . Various types of liquid or gel-type sealants may also be used. For example, if the liner  416  and the tube  490  include PVC material, a solution, such as PVC welding solution may be used to weld the liner  416  to the tube  490 . The PVC welding solution, which generally includes PVC in a solvent, may be applied around the intersections of the liner  416  and the tube  490 . The solution may also be applied to the surface of the liner  416  that will ultimately face the walls of the system  400 .  
      While various embodiments of the invention have been described, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible within the scope of the invention. Accordingly, the invention is not to be restricted except in light of the attached claims and their equivalents.