Abstract:
A plant nutrient delivery system comprises a sensor, an electronically actuated valve and an electronic controller. The sensor is positionable in plant growing media and operable to detect a condition of the plant growing media. The electronically actuated valve has a connection to a liquid nutrient source. The electronic controller is linked to the sensor and to the electronically actuated valve. The controller is programmed to carry out automatic demand-based nutrient delivery to the plant growing media by controlling the electronically actuated valve to turn on and off based on signals received from the sensor regarding a condition of the plant growing media, thereby causing a flow of the liquid nutrient into the plant growth media to start and to stop. Methods are also described.

Description:
BACKGROUND 
       [0001]    The present application relates to plants and plant nutrients, and in particular to a nutrient delivery system that automatically delivers nutrients (including water and other nutrients) to plants according to sensed conditions in the plant&#39;s environment. 
         [0002]    Automatic watering devices for plants typically incorporate an electrically actuated valve and a timer. According to this approach, water is delivered to the plants based on preset times of day and durations. Users typically guess at an appropriate time(s) of day and duration(s), which likely results in over watering or under watering the plants. A plant&#39;s need for water and other nutrients changes with weather conditions (including temperature and precipitation), sunlight, evaporation rate, soil conditions and the plant&#39;s size, among other factors. As a result, it is very difficult to deliver the appropriate amount of water for the plant at the current time with the typical approaches. 
         [0003]    In addition, the typical approaches cause waste because of over watering and loss of plants and/or plant yield due to under watering in some conditions. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]      FIG. 1  is a perspective view of a nutrient delivery system installed in a conventional container, such as a conventional pot. 
           [0005]      FIG. 2  is an exploded perspective view of the nutrient delivery system of  FIG. 1 . 
           [0006]      FIG. 3  is a perspective view similar to  FIG. 1  that has been sectioned to show levels of a liquid nutrient and plant growing media in the container. 
           [0007]      FIG. 4  is a sectioned side elevation view of the nutrient delivery system. 
           [0008]      FIG. 5  is an exploded perspective view of a valve, riser, battery, reservoir assembly and other components of the nutrient delivery system 
           [0009]      FIG. 6  is an enlarged perspective view of a reservoir assembly. 
           [0010]      FIG. 7  is a plan view of an interior side of a cap. 
           [0011]      FIGS. 8 and 9  are sectioned plan views of the valve in two different operating positions. 
           [0012]      FIG. 10A  is a block diagram of a representative nutrient delivery system. 
           [0013]      FIG. 10B  is a flow chart of a representative method. 
           [0014]      FIG. 11  is a graph of plant stress timer duration versus temperature. 
           [0015]      FIG. 12  is a sectioned perspective view showing a nutrient delivery system according to another implementation. 
           [0016]      FIGS. 13A and 13B  are sectioned side elevation views showing the system at a low level condition. 
           [0017]      FIGS. 14A and 14B  are sectioned side elevation views showing the system at a high level condition. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]    According to representative implementations, and as shown in  FIGS. 1 and 2 , a nutrient delivery system  100  has a sensor  110 , a valve  120  and a controller  130  that is linked to the sensor  110  and to the valve  120 . As explained in more detail below, the controller  130  is programmed to automatically operate the valve  120  according to predetermined conditions. As shown, the nutrient delivery system  100  according to some implementations is configured for use in conjunction with a container C within which one or more plants can be grown, but other configurations are also possible. 
         [0019]    The nutrient delivery system  100  can have a housing  104  coupled to the valve  120  and a riser  106  connected to one of the valve&#39;s fluid passages. The housing  104  can be sized to at least partially enclose and protect the controller  130  and other circuit elements (discussed below in greater detail) from moisture and other environmental conditions. In the illustrated implementation, the sensor  110  is connected to the controller  130  by a sensor wire (not shown). In other implementations, the sensor  110  and the controller can communicate wirelessly. Power can be supplied to the circuit by a battery  118 . 
         [0020]    The nutrient delivery system can have a support  112 . In the illustrated implementation, the support is sized to support the valve  120  and housing  104 , such as at a position above a level of plant growing media P ( FIG. 3 ) in the container C. At its upper end  116 , the support  112  defines a space or recess sized to receive the battery  118  and has a longitudinal bore sized to receive the riser  106 . A lower end  114  of the support is designed to be positioned in or pushed into the plant growing media P or other material in the container. As shown, the battery  118  can be received in a battery holder  132  positioned in the recess and the recess can be covered by a cap  134 . 
         [0021]    An implementation of the riser  106  and the valve  120  is shown in more detail in  FIG. 5 . As illustrated, the valve  120  provides for three connections, although other configurations are of course possible. There is a first inlet connection  122 , which can be connected to a source of a liquid nutrient, such as water or water mixed with other ingredients (e.g., one or more fertilizing ingredients). In some implementations, the first inlet connection  122  is adapted for connection to a household hose bib (not shown) or other source of pressurized water. There is a first outlet connection  124  that is connected to the riser  106  and supplies flow to the container C under predetermined conditions. There is an optional second outlet connection  126 , which, e.g., allows multiple instances of the nutrient delivery system  100  to be daisy chained together. 
         [0022]    The riser  106  can have any suitable configuration, such as a length suitable to position the valve  120  and housing  104  above an upper end of the container C as shown. 
         [0023]    The riser  106  can be assembled together from several segments. In the implementation shown in  FIG. 5 , the riser  106  has a single full length tube section  140  to which the sensor  110  is coupled. Optionally, there is a second larger diameter tube  142  for positioning along the upper length of the tube section  140 . A length of heat shrink tubing  144  is used to secure the sensor  110  in place along the riser tube section  140  with its lower (low level sensing) end exposed and its upper (high level sensing) end exposed. The tube section  140  can be connected at its upper end to a suitable fitting  146 . 
         [0024]    Similarly, the first inlet connection  122  and the second outlet connection  126  can be configured to receive a suitable fitting  150 , such as to allow connection to conventional 1/4″ drip irrigation tubing  152  and an elbow  154 . 
         [0025]    Referring to  FIGS. 8 and 9 , a representative construction of the valve  120  is shown in section. One suitable valve is the CWX-15 Series 3-way motorized valve having a brass construction and a customized controller. In  FIG. 8 , a ball element  160  has been moved to a closed position to stop flow from the inlet connection  122 . In  FIG. 9 , the ball element  160  has been moved to an opened position to allow flow from the inlet connection  122 , through the valve body and out through the outlet connection  124  and into the riser  106 , and out through the second outlet connection  126 . It is also possible to configure the valve  120  to have an opened position in which flow is allowed through only one of the outlet connection  124  and the outlet connection  126 . 
         [0026]      FIG. 7  is a plan view showing an interior side of the cap  134 . The cap be configured with conductive areas  164 ,  166  to connect with the battery  118 . In some implementations, the battery  118  is a conventional 6V lantern cell. 
         [0027]      FIG. 10A  is a schematic block diagram of the nutrient delivery system  100 . As shown, the controller (or MCU)  130  controls an output driver component  176  to send drive signals to move the valve  120 , such as via a valve solenoid or a valve motor. The sensor  110  can be configured as a sensor probe  110  as shown, with a low level sensing portion or low level detector  111  and a high level sensing portion or high level detector  113  (see  FIGS. 13A and 13B ). The sensor signals can be received by a sensor signals conditioner  174 , processed and sent to the controller  130 . In addition to a liquid level or moisture sensor, there can be a temperature sensor  172  that detects an ambient temperature and sends a temperature signal to the controller  130 . The battery  118  can be connected via a power management component  170  to supply appropriate power to the controller  130  and other components. One or more LEDs  178  or other similar indicators can be provided to signal conditions, such as sufficient battery level, low battery level, valve in operation, liquid or moisture level, etc. 
         [0028]    As shown in  FIGS. 3 and 4 , the nutrient delivery system can be configured to deliver liquid nutrient to the container C, on an on-demand basis, when a low level condition is sensed. In some implementations, the system is programmed to include an intentional delay, also called a stress cycle, in supplying the nutrient flow following a sensed low limit condition, because plant health increases if plants are appropriately stressed. Further, the stress cycle duration can be adjusted according to the ambient temperature such that only short stress cycles are used when ambient temperatures are high. 
         [0029]      FIG. 10B  is a flow chart showing steps of a representative method for operating the nutrient delivery system. According to step  190 , the system reads the low level sensor. The interval between readings can be set to manage how much power the sensor drains from the battery. In one implementation, the low level sensor is read every 15 minutes. In step  192 , the system determines if the low level sensor has been triggered, i.e., whether a level of moisture or liquid has fallen below a low limit as determined by the position of the low level sensor. If not, then the program returns to step  190  and reads the low level sensor at the next interval. 
         [0030]    If the low level sensor has been triggered (see  FIGS. 13A and 13B ), then the system initiates a stress cycle (step  194 ). The stress cycle has a predetermined duration, and may be further modified according to ambient temperature, such as may be sensed by the temperature sensor  172 . In one implementation, the stress cycle is set to 60 minutes. In step  196 , following the completion of the stress cycle, the system turns the valve on to allow flow to fill the container until the high level is reached and the high level sensor is triggered. 
         [0031]      FIG. 13A  shows a section view in elevation of the container C with the system  100  in a low level condition when the low level sensor  111  is being triggered. As shown in the magnified view of  FIG. 13B , the water (or other liquid) at level L is contacting the low level detector  111 .  FIGS. 14A and 14B  correspond to  FIGS. 13A and 13B , respectively, but show the system after the stress cycle has been completed, after filling and upon the high level detector  113  detecting that the high level has been reached. 
         [0032]      FIG. 11  is a graph of temperature vs. a stress timer duration, showing that the duration of the stress period is decreased as the ambient temperature increases. 
         [0033]      FIG. 12  is a sectioned perspective of a nutrient delivery system  200  according to another embodiment in which a container C′ has an intermediate supporting surface S above a bottom B, and a lower chamber L is defined between the bottom and the supporting surface S. The intermediate supporting surface S supports plant support materials, such as plant growing media and other materials, above the bottom B. In this way, the lower chamber L serves as the reservoir, the riser  106  is used without a support  112 , and a plant in the container draws liquid from the reservoir up through a central bore F by capillary action. Excess liquid can be returned to the lower chamber L via the drain holes D. 
         [0034]    In view of the many possible embodiments to which the principles of the disclosed invention may be applied, it should be recognized that the illustrated embodiments are only preferred examples of the invention and should not be taken as limiting the scope of the invention. Rather, the scope of the invention is defined by the following claims. We therefore claim as our invention all that comes within the scope and spirit of these claims.