Abstract:
A device and method for preventing leak losses in irrigation system zones is disclosed, wherein the device and method monitor a fluid flow characteristic to detect leak conditions, and automatically close off fluid flow to a zone in which a leak condition is detected.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention pertains to irrigation systems, particularly devices and methods of controlling leaks in such systems. 
       BACKGROUND OF THE INVENTION 
       [0002]    Irrigation systems, especially automatic irrigation systems, allow for the distribution of water over areas of land. Permanently installed irrigation systems usually include an piping system that distributes water to sprinkler heads of various designs and functions. To maintain operational water pressure in a sufficiently large irrigation system, the system may be divided into multiple zones that do not operate simultaneously. Smaller systems may comprise single zones. Such systems may be operated by either manual or automatic controls. 
         [0003]    Fully automated systems may include a programmable control system that can be set to operate specific zones at set times, and are often intended to operate for extended periods without human intervention. However, there are limitations to this reliability. Among the failures that can occur are leaks that can be caused by, for example, the failure or breakage of a sprinkler head, or more rarely, by a break in the piping. Such leaks, especially those caused when a sprinkler head breaks, can result in an open flow condition. These leaks waste water and can damage landscaping due to a large amount of water flow being concentrated in a small area. 
         [0004]    Additionally, when leaks do occur, they can happen in areas that are not readily visible to people who may be in the area, or when no one is around. Thus, leaks can go undetected for an extended period while the irrigation system cycles on and off repeatedly. These conditions allow the continuous waste of water and can result in more extensive damage to landscaping than would occur if the leak were promptly identified and prevented. 
         [0005]    Accordingly, it is a goal of the invention to provide an automatic shutoff of an irrigation zone when an excessive flow condition is detected in that zone. 
         [0006]    It is a further goal of the invention to close off one zone with a fault in a multi-zone irrigation system without disrupting the functioning of the other zones. 
         [0007]    It is another goal of the invention to provide leak prevention for irrigation zones without requiring changes from conventional designs. 
         [0008]    It is yet another goal of the invention to provide notification that a leak has occurred in an irrigation zone. 
       SUMMARY OF THE INVENTION 
       [0009]    The invention comprises a device and method for determining whether a flow characteristic of fluid, for example pressure or flow rate, in an irrigation system zone has deviated from an expected value, and, if such deviation is sufficiently significant to indicate a leak, for shutting off flow to that zone until the leak is repaired. 
         [0010]    The device comprises a zone control unit that senses whether a flow characteristic in its zone is out of the normal range for that flow characteristic. Such conditions occur if there is a fault in the zone such as a broken water pipe or flow head. If the flow characteristic is out of range, the zone control unit removes power from the zone control solenoid, thus shutting off water flow to the zone, and preferably “latches” itself into the off state for as long as the master control unit has the zone turned on. Once power to the zone is turned off, the zone control unit preferably resets automatically so that, if the leak has been repaired, the zone will automatically return to its normal function. Conversely, if the leak has not been repaired and the master control unit again turns the zone on, the zone control unit will again sense the leak and turn the zone off. 
         [0011]    In a preferred embodiment, the zone control unit comprises a delay timer to allow the zone to reach its steady-state flow before the zone control unit can operate to turn off the zone. This delay allows air to be purged from the zone and pressure to come up to normal levels if the zone is functioning correctly. The delay will depend on the volume of the piping in the zone and the expected supply characteristics. 
         [0012]    The zone control unit is preferably integrated with and has the same electrical connections as an industry-standard solenoid valve control, allowing systems to be easily and inexpensively retrofitted, and allowing new systems to incorporate the invention without changes to conventional system designs. 
         [0013]    In an additional embodiment, a signal, such as a warning light or buzzer, provides notification that a zone control unit has detected a fault in a zone and turned the zone off. In closely monitored systems, a warning light or buzzer or a combination thereof will be sufficient. However, in remote or only occasionally monitored systems, the system may be linked to a landline or cell phone transmitter to provide a telephone or form of message to provide notification of the existence of a fault. 
         [0014]    In accordance with the invention, irrigation systems can be made less susceptible to water wastage and landscaping damage when breaks occur, and the remainder of the system will continue to function normally. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  is a schematic view of a multiple-zone irrigation system. 
           [0016]      FIG. 2A  is a schematic view of one embodiment of the present invention in a normally operating condition. 
           [0017]      FIG. 2B  is a schematic view of one embodiment of the present invention in a shut-down condition due to a flow fault in the zone. 
           [0018]      FIG. 3A  is a schematic view of an embodiment of the present invention including a signaling unit. 
           [0019]      FIG. 3B  is an alternative schematic view of the system embodiment of  FIG. 3A . 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    Referring to  FIG. 1 , a schematic view of a zoned irrigation system includes water inlet  10 , which provides a water source through main water line  12  to controllable solenoid valves  14 ,  16 , and  18 . Controller  20 , typically a programmable controller, is in signal communication with solenoid valves  14 ,  16 , and  18  via control lines  22 ,  24 , and  26 , allowing controller  20  to selectively switch solenoid valves  14 ,  16 , and  18  on and off, and thus selectively allowing water flow into irrigation zones  28 ,  30 , and  32 , respectively. Control lines  22 ,  24 , and  26  are typically two-wire lines providing an AC control signal (typically 24V) to each solenoid valve. Irrigation zones  28 ,  30 , and  32  have respective flow heads  34 ,  36 , and  38 , which may be any type of flow heads known in the art, and which will be patterned as needed to provide the desired pattern of water flow to the respective zone. 
         [0021]    Those of skill in the art will recognize that the number of zones and the size, type, and number of flow heads within each zone is a matter of design choice, and that the use of three zones in  FIG. 1  is by way of example only. In practice, such an irrigation system might have only a single zone, or as many zones as necessary to properly irrigate the area. 
         [0022]    Referring now to  FIGS. 2A and 2B ,  FIG. 2A  is a schematic reflecting an embodiment of the present invention as applied to one zone is shown in its normally operating condition.  FIG. 2B  reflects the same embodiment when a flow fault has been detected, causing the zone to be shut off. 
         [0023]    Controller  220  (corresponding to controller  20  of  FIG. 1 ) is in signal communication with zone control unit  222 , the components of which are indicated by the outer dashed line. Two-wire control line  224  provides signal communication between controller  220  and zone control unit  222 , and typically provides 24V AC when the zone is “on.” After controller  220  turns on the zone controlled by zone control unit  222 , the zone control unit  222  will turn the zone off if an abnormal flow condition (such as that caused by a broken pipe or flow head) occurs. 
         [0024]    Outputs  226  are in signal communication with the zone control solenoid (not shown), which allows water to flow in the zone when the zone is on, and prevents flow when the zone is off. In normal operation ( FIG. 2A ), double-pole, double-throw relay  228  (designated by the inner dashed line) is not energized. Bypass line  230  is in signal communication with first input line  221  of two-wire control line  224 , and with first output terminal  225  through a first normally-closed contact  232  of relay  228 . Second input line  223  is in direct signal communication with second output terminal  227 . Thus, when zone control unit  222  is in normal operating mode, the 24V AC signal from controller  220  passes directly to the the zone control solenoid (not shown). 
         [0025]    Zone control unit  222  comprises first diode  234 , typically a 1N4002 or equivalent diode, which rectifies the 24V AC signal from controller  220  when the zone is on, and provides effective DC power (approximately 36-40V DC at internal power line  236 ) to the other electronics. 
         [0026]    First capacitor  238  and first resistor  240  comprise an “RC” delay circuit that retards the full power-on status of the remainder of the electronics, thus allowing pressure in the water lines time to reach a normal, steady-state condition. This delay prevents zone control unit  222  from prematurely detecting a “low pressure” condition and shutting off flow to the zone. For example, values of 220 μF and 10KΩ for first capacitor  238  and first resistor  240 , respectively, would provide and RC time constant of approximately 2.2 seconds, with some variance expected for tolerances of the components. 
         [0027]    The initial delay period is a matter of engineering choice, and will be determined in part by the volume of the water lines in the zone. The initial delay period serves to allow pressure to rise in the water lines in the zone and to allow air to be flushed out, thus preventing a spurious low pressure reading. 
         [0028]    Second resistor  244  and second capacitor  242  provide filtering for the “downstream” electronics. In one example, values of 8.2 MΩ for second resistor  244  and 220 μF for second capacitor  242  have been found acceptable. Additionally, second resistor  244  in conjunction with third resistor  248  provide biasing resistance for transistor  250 . Transistor  250  must have sufficient current capacity to allow it to activate coil  258  of relay  228 . Transistor  250  may, for example, be a darlington such as a MPSA13 darlington. 
         [0029]    Pressure switch  246  may be placed in the zone water line either upstream or down-stream of the zone control solenoid (not shown), or may be built into the zone control solenoid, itself. In the example of  FIGS. 2A and 2B , the pressure switch is open when pressure is normal and closed when pressure falls below a preset limit. However, those of skill in the art will recognize that, with appropriate adjustments to the electronics, a which is open on low pressure could also be used. 
         [0030]    Referring now in particular to  FIG. 2B , the zone control unit  222  changes state when a fault occurs in the zone during operation, such as a broken water line or loss of a sprinkler head. The resulting low pressure condition closes pressure switch  246 , which in turn provides power to, and switches on, transistor  250 , activating coil  258  of relay  228 . Second diode  252  maintains a DC condition across coil  258 , otherwise, internal power line  236  would be in signal communication with the AC signal from second control line  223 . Bypass line  230  is switched from first normally closed contact  232  to first normally open contact  233 , removing power from first output  225 , and thus from the zone control solenoid. 
         [0031]    Simultaneously, first internal control line  264 , which was originally left open via contact through second normally closed contact  260 , is transferred into signal communication with second control line  223  via second normally open contact  262  and second internal control line  266 , latching relay  228  into an “on” condition. This latching function prevents the zone from oscillating, or “chattering,” between “on” and “off” states in the event that there are pressure fluctuations in the water lines that cause pressure switch  246  to re-open. 
         [0032]    As an option, fourth resistor  254  is in signal communication with transistor  250  (and first internal control line  264 ), and with internal power line  236  via light emitting diode (“LED”)  256 , causing LED  256  to illuminate if the zone has been turned off by the zone control unit  222 . As discussed above, LED  256  could be used alone, or be replaced by or used in conjunction with an audible alert, such as a piezoelectric buzzer. Alternatively, more sophisticated alert systems could be provided that perform more involved functions, such as dialing a mobile phone number and sending a text message. However, such alternatives are matters of engineering choice (and expense), and can be used without departing from the spirit of the invention. 
         [0033]    If the condition causing the abnormal flow remains unrepaired and controller  220  cycles power to the zone off, the zone control unit will revert to the state of  FIG. 2A . Thus, if the controller  220  later (for example, in response to programming for period irrigation) turns the zone back on, water will flow in the zone only until the zone control unit  222  again recognizes the problem condition, at which point the low pressure situation will again cause the zone to be latched “off.” 
         [0034]    As those of skill in the art will recognize, such a system is also operable by detecting any flow characteristic of the water in the zone water lines. For example, rather than detecting pressure, the system may detect flow rate. Accordingly, the examples provided above are not limiting of the invention. 
         [0035]    Similarly, the control circuitry described above is not considered to be exclusive of other embodiments. Those of skill in the art will recognize that the function provided by the above-described circuitry may be accomplished in a variety of ways without departing from the spirit of the invention. The above-described circuitry is advantageous because it can be incorporated into, or packaged with, industry standard control solenoids, thus allowing existing systems to be retro-fitted with the present invention by a simple replacement of the control solenoid and, if necessary, its associated valve. Similarly, such packaging allows newly installed systems to be installed in the conventional manner, that is, by connecting the two leads of the control wire to the zone control unit, without the need for attaching extra circuitry or wiring. 
         [0036]    Referring now to  FIG. 3A , an alternative embodiment of the zone control system includes a controller  310  in signal communication via first control line  312  with a zone control unit  314  of the present invention, and additionally in signal communication via second control line  318  with signaling unit  316 . Signaling unit  316  may comprise any desired device for providing a signal indicating a system fault, including, for example and without limitation of the present invention, a visual alarm such as a light, an audible alarm such as a buzzer or bell, or more sophisticated devices such as modems capable of linking to landline or cell-phone service and providing fault information to a remote location, or any combination of signals. Thus, signaling unit  316  can provide an indication to the irrigation system owner or operator that a zone has shut itself off as a result of an out-of-bounds flow condition. 
         [0037]    The configuration of  FIG. 3A  has the advantage of requiring only a single signaling unit for a multi-zone controller, but would require a controller capable of recognizing when a zone control unit has shut off a zone. An alternative embodiment, reflected in  FIG. 3B , provides a signaling unit  316  in signal communication with zone control unit  314  via second control line  320 , similar in function to what is reflected internal to the zone control unit  222  in  FIGS. 2A and 2B . This embodiment has the advantage of allowing each zone control unit to be pre-configured to allow the attachment of a signaling unit  316  at any time, for example by providing connections to normally-open contact  238  and first lead  225  of two-wire control line  224  of  FIGS. 2A ,  2 B, and  2 C. These connections may be provided, for example, via a plug or screw terminals (not shown) provided on the body of zone control unit  314 . 
         [0038]    A variety of engineering options, both in circuitry and physical configuration, are available to provide the necessary control for the zone control unit and signaling unit. Accordingly, it will be understood that the above descriptions are provided by way of example only, and are not intended as limiting of the invention.