Abstract:
Disclosed is an electronic control assemblage for improving the watering habits to each zone in an irrigated parcel of land. The system consists of a 24 VAC transformer, a control unit, a sprinkler valve, and a probe assemblage for sensing the moisture level in a zone being watered. The electronic control unit is pre-modified to disable power to the sprinkler valve when the moisture level in the zone exceeds a prearranged level as measured by the moisture probe, buried in the zone area. In a preferred embodiment, the probe consists of a cylindrical stainless steel hollow metal shaft, a high purity dissembler metal point, separated with a dielectric material. The shaft, dielectric spacer, and point all have a predetermined length, wall thickness, and grade of material, pre-established to maximize the moisture detection characteristics of the probe. The control unit applies an electrical current along the shaft, energizing the dissembler metal point. The control unit records the soil impedance to determine the moisture content in the soil.

Description:
BACKGROUND OF THIS INVENTION 
     1. Field of the Invention 
     The present invention relates to a 24VAC sprinkler irrigation control system. More specifically, the present invention details a portable moisture sensing probe that controls the irrigation system based upon the soil moisture content of a single zone or variation of zones in landscapes to be watered. 
     2. Description of Related Art 
     Communities throughout the United States and the world share an uneasy reliance on both surface and sub-surface water supplies. Water tables are dropping more rapidly than expected, and water conservation is of utmost concern to governing officials. As population growth increases, the demand for fresh potable water also increases in most arid states. State and local governments have issued mandates regarding the use of landscape irrigation water, and are promoting the conservation and use thereof Thus, farmers worry there won&#39;t be enough water to feed their crops. And environmentalists worry that too little water is allowed for natural purposes. Additionally, businesses worry that a lack of water will dampen the availability of jobs. 
     Landscape irrigation accounts for approximately 50% of the water used externally by homeowners and businesses. According to landscape architects, most homeowners with large landscapes apply twice as much water as their lawn actually needs. This results in an enormous waste of fresh potable water needed for internal uses. The competing interest for fresh water has driven costs to the point that some homeowners are considering xerscaping. 
     Unfortunately the major cause for over watering is the lack of irrigation information, and technology to control waste. Consequently, there are so few types of landscape irrigation controllers, other than timers. These timers do not know when it is raining, nor do they know over watering must stop. The complexity of a multi-station timer switches opening the sprinkler valves for a specific amount of time daily, are confusing and very labor consuming. The inefficiency is in the fact they deliver water based upon the time of day, regardless of the moisture levels in the soil. Timers which are expensive and inefficient wasters of water can be modified with optimal devices which measure and control the moisture level in the zones prior to watering. Moreover, it is not convenient for most rate payers to check the moisture levels in their lawns, and strictly have relied upon timers to do so. 
     Since moisture probes are extremely sensitive to placement and orientation within the soil itself. Generally, moisture probes react differently to different soils, and have a low probe life of one to two years. The performance is normally at a lessor level, resulting in either over or under watering. The majority of soil probes do not change alternating current (AC) to direct current (DC) in satisfy building and safety codes. 
     Therefore, there is a need for an irrigation control system that does not need a timer to control landscape irrigation. There is also a greater need for a system that can measure “real-time” moisture in the soil and yet, be suited to the both post and pre-market timered landscapes. This system will be extremely responsive to small amounts of moisture changes that occur in all soil types, in all types of weather conditions. In addition, this system will have multiple placement applications for those landscapes with extreme elevations, and soil slippage, should this occur. 
     SUMMARY OF THE INVENTION 
     The above requirements are satisfied by the present invention. In one aspect of the invention, there is disclosed a soil probe system configured to monitor the level of moisture in a watering zone location. The moisture sensor system includes a probe consisting of different metals, with different lengths, utilizing a “pencil like” shaft, separated by a dielectric material, all having a length, width, and circular thickness. The system further includes a transformed source of alternating electrical (VAC) power connected to the control unit. The control unit connects to the probes&#39; tubular shaft and dissimilar metal point for applying a direct current (VDC) to the electrode through the control unit for measuring the electrical potential between the two dissimilar metals. The control unit is configured to disarm the flow of electrical power from the transformer or timer to an electronic valve, if the electrical impedance is below a predetermined value. 
     In another aspect of the invention, there is disclosed a method for controlling water distribution to soil, comprising the steps of placing a moisture sensor vertically in the soil at the grass root level. Another aspect of the invention, the probes can be moved to accommodate changes in soil structure and watering habits. And, in another aspect of the invention, utilizing dissimilar metals improves the life span of probe life considerably. 
     Moreover, another aspect of the invention discloses a unitized system for watering a series of zones. It is comprised of a transformer or timed power supply, (if necessary) for supplying power along the power path. A first soil probe is located along the power pathway. The soil probe system includes a first water valve connected to a first sprinkler, a first moisture probe configured to measure the moisture level in the first watering zone, and a first control unit communicating with the first moisture probe and the first water valve. The first control unit is configured to close the first water valve if the moisture level is below a predetermined level. A second soil probe system is located along the power path and includes a second water valve connected to a second sprinkler, a second moisture robe configured to measure the moisture level in a second watering zone, and a second control unit configured to close the second water valve if the moisture level in the second water zone is below the predetermined level. A relay is located in the power path between the power supply and the second soil probe system. The relay is controlled by the first control unit to allow power to flow across the relay when the moisture level in the first watering zone is greater or equal to the predetermined level, and to inhibit power from passing across the relay when the moisture level in the first watering zone is less than the predetermined level. 
     These and other features of the invention will now be described with reference to the drawings of the preferred embodiment of the moisture sensor and irrigation control system. The illustrations are intended to illustrate, but not to limit the invention. 
    
    
     BRIEF DESCRIPTION OF THIS INVENTION 
     FIG. 1 schematically illustrates the mechanical and electrical components of the sprinkler system of the present invention; 
     FIG. 2 is an actual size, (100%), top view of a first embodiment of a moisture probe that is used in the sprinkler systems of the present invention; 
     FIG. 3 is an exploded top view, ( 4  X), of the moisture probe illustrated in FIG. 2; 
     FIG. 4 is an exploded top view, ( 4  X), of the parts assemblage of the moisture probe illustrated in FIG. 3; 
     FIG. 5 is a side view of the moisture probe of FIG. 2 as positioned “horizontally” under ground in a watering zone. 
     FIG. 6 is a side view of the moisture probe of FIG. 2 as positioned “vertically” above ground in a watering zone. 
     FIG. 7 is a schematic illustration of a sprinkler system having a series of moisture probes and control units. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 schematically illustrates an irrigation system  29  configured in accordance with a preferred embodiment of the present invention. One embodiment of the irrigation system  29  consists of a number of components, including a transformer  21 , a control unit  22 , at least one sprinkler valve  23  which is connected to a plurality of irrigation sprinkler heads  25 , and a moisture sensor or probe  24  for detecting the level of moisture in a watering zone in accordance with the present invention. As used herein, the term “watering zone” refers to an area of plants that is to be watered using the irrigation system  29 . In most watering zones, a wide variety of plant life may be located in the sprinkler patterns, such as, for example, lawn, trees, shrubbery or gardens. The watering zones may be located on a homeowner&#39;s yard, an industrial landscape, a park, on farms with larger acreage sprinkler systems, or any other area of land that is irrigated for a variety of purposes. 
     As discussed, the irrigation system  29  will include a (24VAC) transformer which is connected to a source of 110 VAC power outlet (not shown). A 24VAC transformer is used to reduce the voltage to a safety level described in most city building and safety plumbing codes. The transformer directs power to the system  29 , for continuous energization of the irrigation system  29  at one hundred percent (100%) of the total irrigation time. Any standard 24VAC transformer may be used. A timer (not shown) may be used between the transformer  21 , and the control unit  22 , but need not be included in the irrigation system  29  of the present invention. The inclusion of a timer is only for the convenience of the owner needing a set watering time. 
     As illustrated in FIG. 1, the irrigation system  29  further includes a control unit  22  which is interposed along an electrical circuit between the transformer and the other components of the irrigation system  29 . The control unit  22  controls and monitors a number of functions of the irrigation system  29 , as described in detail below. Preferably, the control unit  22  is electrically connected to the transformer  21  so that the control unit  22  acts as a conduit to route electrical power to the rest of the components of the irrigation system  20 . In a preferred embodiment, the control unit  22  must include a 24 VAC transformer  21  that converts the 110 24 VAC electrical current to a 24 VDC that is received by the moisture probe  24 , and delivered back to the solenoid at the sprinkler valve  23 . Depending on the power source, other suitable transformers could be used. The transformer  21  may be external to the control unit  22 . The control unit  22  converts the incoming 24 VAC to 24VDC for internal use, applies a voltage for external use at the moisture probe  24 , and control circuitry decides whether or not to pass the 24VAC to the sprinkler valve  23 . The probe is an impedance circuit. Advantageously, the control unit  22  includes a converter (not shown) for converting the 24 VAC current into a 1.5 DC current that the control unit  22  supplies to the moisture probe  24 , as described in detail below. 
     As shown in FIG. 1, the control unit  22  is electrically connected to an electronically-controlled sprinkler valve  25 , which is connected to a source of pressurized water (not shown). The sprinkler valve  25  may be any type of electronically-controlled valve, but advantageously is one which opens in response to receiving an electrical current of a pre-determined voltage. Preferably, the valve  23  is a standard, electronically-controlled 24VAC anti-siphon solenoid valve being standard in the industry. 
     Referring to FIG. 1, the valve  23  is connected to, and controls, the supply of water to at least one water conduit  26 , so that when the valve  23  opens in response to an electrical current water flows from the pressurized water source into the water conduit  26  for distribution to the watering zone. The water conduit  26  may be any type of device known to those skilled in the art for transporting the flow of water, such as, for example, plastic or metal pipe, hose, etc. The water conduit  26  may be disposed either above or below ground. Although the irrigation system  29  is illustrated in FIG. 1 as having a single valve  23  connected to water conduit  26 , it will be appreciated that nay number of valves and water conduit combinations may be used with the present invention. 
     As shown in FIG. 1, the water conduit  26  routes a flow of water to an irrigation sprinkler head  25  for dispersing water over a predetermined watering zone. Preferably, the water conduit  26  connects to a plurality of irrigation sprinkler heads  25  which are distributed over the watering zone. The irrigation sprinkler heads  25  are advantageously arranged to uniformly disperse water over the entire watering zone, which may result in overlapping of the watering range of some of the irrigation heads  25 . The present invention may use any wide variety of irrigation heads  25  for dispersing water over the parcel of land zoned for example, spray heads, drip delivery heads, a surface flooding head, or any combination thereof. 
     As shown in FIG. 5 and 6, the irrigation systems  58  and  59  further includes the moisture probe  53 , which is buried either underground, horizontally, or injected into the soil aboveground, vertically, in the watering zone and electronically connected to the control unit  22  as illustrated in FIG.  1 . During operation, the moisture probe  53  detects the moisture level within the watering zone when the control unit supplies an electrical potential to the probes  53 . In response to the electrical potential, the moisture probe  53  sends an electrical signal to the control unit  22  as illustrated in FIG. 1, in accordance with the amount of moisture in the soil adjacent the probe  53 , as described in detail below. The control unit  22  described in FIG. 1 evaluates the electrical signal and enables or disables electrical power to the valve(s)  23  in FIG. 1, if the moisture level is below or above a predetermined threshold. 
     FIGS. 2 illustrate the actual size of a side view, respectively, of a first embodiment of the moisture probe system  29 . It will be appreciated that, as used herein, the word “top” are with reference to the orientation depicted in enclosed drawings and are not intended to limit the scope of the invention. As shown in FIG. 2, the probe system  29  includes one dissembler metal probe tip  31 , one dielectric insert  32 , one stainless steel ¼′ hollow metal shaft  33 , and one shrink-type water sealant  34 . Preferably, each probe assemblage is in a cylindrical shape. 
     In FIG. 3, a full top segregated composite of a complete assembled system  49  views the width and length and thickness of the hollow shaft  43 , the dielectric material  42  and metal probe tip  41  are substantially the same. As shown, the segregated view, exploded 4X that of the actual size of the “pencil” probe when oriented in a predetermined size relative to one another. Specifically, the internal shaft of the metal point  41  are aligned in a substantially internal parallel position with the dissembler metal shaft  41 , and separated by the dielectric material  42 . 
     In the embodiment illustrated in FIG. 3, a single dielectric, cylindrically-shaped spacer  42 , is interposed between the metal probe tip  41  and the hollow metal shaft  43  to maintain the correct positioning relative to one another. An electrical shrink tape  47 , is heated and shrank to securely fasten and strengthen the 18×2 underground cable. 
     As shown in FIG. 4, and parts assemblage system  69 , one electronically-conductive wire  64  are connected to the metal probe tip  61 B. A second wire  45 , as shown in FIGS. 3, is connected to the stainless steel tubing. Referring to FIG. 2, the wires  36  and  37  connect the moisture probe system  39 , and communicate with the control unit  22  in FIG.  1 . Preferably, as in FIG. 3, the wires  44  and  45  are injected into the hollow metal shaft  43 , and sealed internally. Illustrated in FIGS. 4, using a single dielectric spacer  63 A and  61 B, it will be appreciated by those skilled in the art that any wide number of dielectric spacers having various sizes and shapes, may be used to maintain the distance and orientation between the hollow metal shaft  65  and the dissembler metal point  61 A and  61 B. Moreover, the single dielectric spacer is inserted at one end of the hollow metal shaft  65 , and remains sealed within the scope of the present invention. The dielectric spacer  63 A and  63 B is relatively small in diameter so the space between the hollow metal shaft  65  and the metal probe point  61 B remains unobstructed and relatively weather proof. 
     The underground wire  45 , in FIG. 3, may be secured to the hollow metal shaft  43  and the second wire  45  may be secured to the metal probe point  41  in a wide variety of well know manners, such as by soldering, spot welding, screws, or other suitable electrical connections. The length of the underground cable wires  28 A and  28 B in FIG. 1, should be long enough to reach from the position of the control unit  22 , to the location of the watering zone where the moisture probe system is located during use. In FIG. 3, the wires  44  and  45  are inserted through one end of the hollow metal shaft  43 . In FIG. 2, the wires are preferably encased in an underground insulating material  33  to protect the wires from decay and to insulate them electrically from the surrounding environmental elements. The actual size of the underground cable  35 , in FIG. 1, is sized so as when inserted into hollow shaft  33 , it will add strength and allow sealant to the probe system  39 . 
     In FIG. 4, spacer  63 A and  63 B are one in the same piece with a center hole for the metal probe tip to insert into. Both dielectric apertures will systematically fit into one end of the hollow metal tube and be sealed against both chemical and mechanical elements. Because the spacers are mounted to the end of the hollow tube and sealed, it will add stability and rigidity to the shape of the probe, and advantageously do not obstruct the probe when buried horizontally or vertically underground. 
     The preferred dimensions of the moisture probe system  39 , FIG. 2, may vary as described below. The hollow metal tube  33  may range in length from 4½ inches to 6½ inches in length. Preferably, the overall length of the moisture probe including the metal probe tip  31  and  33  is about 5 inches long, which exhibits optimal water detecting characteristics. The preferred outer dimension (OD) of the hollow shaft tubing  33  is ¼ inch and may range upwards to ½ inch. The preferred gauge of the metal of the hollow shaft tubing  33  is {fraction (3/64)} of an inch and will range up to {fraction (5/64)} of an inch. 
     In FIG. 4, probe system  69 , the dielectric spacer  63 A will have a top circumference of ¼ inch, and a preferred thickness {fraction (3/32)} of an inch. The insert portion of the spacer  63 B will have a circumference of {fraction (7/64)} inches, and a length of 1¼ inches. The dielectric spacer will be center drilled to conform with the probe metal tip  61 B, with a circumference of {fraction (4/64)} inches. 
     In FIG. 4, the preferred dimension of the metal tip  61 A, is from zero to ¼ inch in width. The preferred circumference of the inserted portion of the metal tip shaft,  61 B, is {fraction (3/64)} inch of and inch, with a total length of one inch. The metal consistency of the metal tip shall be a mixture of high purity lead, 90 percent, and 10 percent non-corrosive conducive hardener. 
     FIG. 1 illustrates the control unit  22 . The control unit includes a casing that is substantially square in shape and houses the electronic components. The electronic components will be encased in an electronic epoxy for weather and moisture proofing. The control unit  22  will include a rotary mounted knob  22 A that connects to a shaft from the internal electronic equipment. This knob  22 A rotates according to the normal longitudinal axis for adjusting the control unit  22 . One set of electrical wires  28 A and  28 B extend outward from the first control unit  22 , to the Valve  23 . A second set of wires  27 A and  27 B extend outward from the first control unit  22 , to the transformer  21 . A third set of wires  28 C and  28 D extend outward from the first control unit  22 , to the probe. And, a fourth set of wires,  20 A and  20 B extend outward from the control unit  22 , to wires  27 A and  27 B of the second control unit in series. 
     Referring to FIG. 1, the knob  22 A is used as an adjuster for adjusting the sensitivity of the moisture probe  24 , to increase or decrease the moisture threshold at which the control unit enables or disable power to the irrigation system  29 . Preferably, the operator will turn the knob  22 A clockwise to increase the moisture threshold, and counter-clockwise to decrease the moisture threshold. Turning the knob  22 A clockwise would increase the moisture content to the watering zone, and counter-clockwise would decrease the moisture content to the watering zone. It would be appreciated by those skilled in the art, that the present invention is not limited to using a rotatable knob as the sensitivity adjuster. Any wide variety of methods may be used to vary the sensitivity of the moisture probe  24 . 
     FIG. 5 illustrates the preferred horizontal location and orientation of the moisture probe  53 . The probe  53  is located at a depth suitable to detect the amount of moisture for the roots of the plants growing in the watering zone for which the moisture is controlled. The cable  54  is buried at a similar depth, or deeper to accommodate aeration equipment. In areas which are covered by grass  51 , the moisture probe should be buried at the root level of three to four inches to control the vertical penetration of moisture in the soil  52 . 
     When power is received from the timer, the control unit also applies an electricity to the impedance circuit formed by the electrode metals of the probe  53  through the underground cables. Advantageously, a 1.5 volt direct current is applied to one of the dissembler metals of the probe  53 , so there is a 1.5 volt potential between the two dissembler metals. The electrical resistance of the soil  52  that is located along the length of the hollow metal shaft, and the metal point is a function of the level of moisture in the soil. If the soil  52  contains a high level of moisture, the resistance exhibited by the soil is lower than if the soil contains a low moisture level. Accordingly, a higher resistance in the moisture probe  52  corresponds to a low moisture content in the watering zone. A relatively low resistance corresponds to a high moisture content. The moisture probe  52  then sends an electrical signal, having a voltage proportional to the resistance of the soil, to the control unit. 
     In FIG. 1, the control unit  22  enables or disable power to the valves  23  based upon the resistance of the soil as detected by the moisture probe  24 . As discussed, the voltage of the signal sent by the probe  24  is proportional to the resistance as detected by probe  24  in the soil. The control unit  22 , using a potentiometer, compares the resistance of the soil to a predetermined resistance value, corresponding to the resistance at which soil moisture is sufficient for the particular watering zone. As discussed above, as reference to FIG. 1, an operator may manipulate the control unit  22  to adjust the predetermined resistance value. If the soil resistance is below the predetermined resistance value, then the moisture level is sufficiently high for the particular watering zone. The control unit  22  then disables electrical power from being routed to the solenoid valve  23 . If the resistance measured by the moisture probe  24  rises above the predetermined value, the control unit  22  enable power to the valve  22  so that water is supplied to the irrigation sprinkler heads  25  and the zone is watered. 
     The irrigation system  29  therefore does not irrigate the watering zone when the moisture level within the watering zone is above a predetermined value. The moisture probe  24  advantageously assists a user in conserving water by disabling irrigation to the watering zone unless the watering zone actually requires water. The probe  24  having the dimensions described herein advantageously exhibits optimal moisture detecting characteristics in a wide variety of soils so the minimum maintenance of the irrigation system  29  is required by a user. If the watering zone is sloped, the probe or multiple probe locations should be increasingly towards the top as the elevations become steeper. Additionally, the probes should be placed in the portions of the zones that receive the most sunlight and the most wind velocity. 
     As shown schematically in FIG. 7, the system  80  advantageously comprises a plurality of watering zones with one valve  82  and one sprinkler head  84  for each watering zone. Further, there is advantageously a control unit  81  for each valve  82 , with the various control units  81  connected in series such that each valve  82  and its associated sprinkler head  84  operates sequentially. This may be achieved, for example, by connecting a plurality of control units  81  in series, with each control unit  81  having an open relay which is closed when the probe  83  associated with each control unit  81  indicates that the moisture level in the soil is adequate. Thus, a first control unit  81 ′ associated with a first valve  82 ′ and a first watering zone is connected in series with a second control unit  81 ′ associated with a second valve  82 ′ and a second watering zone. The first control unit  81  contains an open relay that interrupts power to the second control unit  81 ′. When the probe  83  associated with the first control unit  81  indicates that the watering zone has sufficient moisture, the relay is closed and power is supplied to the second control unit  81 ′. The second control unit  81 ′ contains an open relay that interrupts power to a third control unit  81 ,″ until sufficient moisture is indicated by second probe  83 ′ associated with second control unit  81 ′. This arrangement can be repeated as many times as desired, provided the wire connecting the control units  81  is adequately sized, and the transformer  86  is large enough to handle the voltage needs. 
     Although the above description of the present invention has disclosed the features of the invention as applied to the various embodiments, it will be understood that various omissions, substitutions, and changes in the form of the detail of the embodiments illustrated may be made by those skilled in the art without departing from the spirit of the present invention. Consequently, the scope of the invention should not be limited to the foregoing disclosure.