Abstract:
A plugged nozzle monitoring system uses a thermal flow sensor located within a spray nozzle of an agricultural sprayer. The thermal flow sensor is free of moving parts and is made of corrosion-resistant materials. The thermal flow sensor is placed within the fluid flow path through the nozzle and activates an alarm if flow through the nozzle falls below the baseline value.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention is directed to farm implements and, more particularly, to a plugged nozzle warning system for use with a sprayer of a farm implement. 
         [0002]    Field sprayers, as known in the art, are typically towed by a tractor or other towing vehicle and include a fluid holding tank supported by a frame and fluidly coupled to a series of spray nozzles equidistantly spaced from one another along booms extending outwardly from the frame. Crop protection fluid, such as pesticides, or liquid fertilizer are dispensed through the spray nozzles onto the farm field and preferably in an even distribution spray patter so that the fluid is applied consistently across the farm field. 
         [0003]    When spraying, or otherwise depositing, fluids onto the farm field, it is important that the spray nozzles are unclogged. If one or more of the nozzles is fully, or partially, clogged, the intended fan angle, pattern, and coverage width will be difficult, if not impossible, to attain. For example, if a nozzle is clogged during the application of a pesticide/herbicide (“chemical solution”), within a few days after the application of the chemical solution, strips of weeds, insects, fungi, and the like will appear on the farm field whereas the portions of the farm field that were covered by unplugged nozzles will be substantially free of the weeds, insects, fungi, and the like. Such a situation requires a farmer to reapply chemical solution to portions of the farm filed where weeds subsequently appear using a smaller sprayer such as an ATV-mounted sprayer or a full size, farm implement mounted sprayer that is set up to apply chemical solution to the weeds. This redundant application of chemical solution ultimately results in twice the application of the chemical solution to some portions of the farm field. In addition to the additional chemical solution cost, there will also be additional fuel costs for the tractor to pull the sprayer across the farm field. Moreover, a farmer can lose confidence in the sprayer&#39;s ability to effectively apply the chemical solution and may transfer that lack of confidence to other implements manufactured by the sprayer manufacturer. 
         [0004]    Conventionally, sprayers have required the farmer to visually inspect the spray nozzles to determine if any spray nozzle of the sprayer is clogged. Visually inspecting the nozzles is particularly difficult for the farmer to do during an active application of the chemical solution. As such, the farmer must either stop the application process periodically and visually inspect the spray nozzles, which adds to the time requirements for the application process, or must assume that the spray nozzles will not become clogged during the application process. In the case of the latter, it is not uncommon for the spray nozzles to become clogged with dirt and/or debris during the application process and therefore assuming that the spray nozzles will not become plugged is unreliable. 
         [0005]    Accordingly, a number of sensor-based systems have been developed that notify the operator if one or more spray nozzles has become plugged. Theses sensors typically rely on moving parts that are moved in response to flow through the spray nozzles. While generally effective, the moving parts can degrade from exposure to the chemical solution and ultimately fail, thereby making such sensors unreliable. One proposed sensor measures a fluid frequency through the nozzle. Since different chemical solutions have different frequency responses, the sensors must be calibrated for each chemical solution. As a single sprayer may be used to apply multiple chemical solutions and the sprayer may have several dozen spray nozzles, requiring calibration of the sensor for each spray nozzle is simply not practical. 
         [0006]    There is therefore a need for a reliable flow sensor that is workable with different types of chemical solutions. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention provides a plugged nozzle monitoring system that uses a thermal flow sensor located within a spray nozzle of an agricultural sprayer. The thermal flow sensor is free of moving parts and is made of corrosion-resistant materials. The thermal flow sensor is placed within the fluid flow path through the nozzle and activates an alarm if flow through the nozzle falls below a baseline value. 
         [0008]    It is therefore an object of the invention to provide a reliable flow monitoring system for use with spray nozzles of an agricultural sprayer. 
         [0009]    It is another object of the invention to provide a nozzle for use with an agricultural sprayer and having a flow sensor that is substantially free of moving parts. 
         [0010]    According to another object of the invention, an improvement for a nozzle of an agricultural sprayer is provided that is usable with sprayers capable of applying different types of chemical solutions onto a farm field or other application surface. 
         [0011]    Various other features, objects and advantages of the present invention will be made apparent from the following detailed description and the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0012]      FIG. 1  is a pictorial view of a spraying system incorporating the principles of the present invention; 
           [0013]      FIG. 2  is an isometric view of a field spray nozzle assembly of the field spraying system of  FIG. 1 ; 
           [0014]      FIG. 3  is a section view of the spray nozzle assembly of  FIG. 2  taken along line  3 - 3  of  FIG. 2 ; 
           [0015]      FIG. 4  is a schematic view of a plugged nozzle monitoring and reporting system according to one embodiment of the present invention; and 
           [0016]      FIG. 5  is a front elevation view of a graphical user interface of the plugged nozzle monitoring and reporting system. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]      FIG. 1  shows an agricultural product application system, which in the illustrated embodiment, is a field spraying system  10  comprised of a self-propelled sprayer  12  having a fluid tank  16  that is supported by a chassis  18  in a known manner. As also known in the art, a rear end  20  of the chassis  18  supports a pair of wing booms  22 ,  24  to which a series of spray nozzle assemblies  26  are coupled. An exemplary spray nozzle assembly  26  is shown in  FIG. 2 . The chassis is supported by a set of tires  28  and the wing booms are supported by smaller wheels  30 . As known in the art, distribution lines  32  are flow coupled to the fluid tank  16  in a conventional manner, which allows fluid, e.g., fluidized fertilizer, pesticide, herbicide, etc., to be passed to a header  34 ,  FIG. 2 , to which the spray nozzle assemblies  26  are coupled. 
         [0018]    Referring now to  FIGS. 2 and 3 , an exemplary spray nozzle assembly  26  has a nozzle body  36  fluidly interconnected between five ( 5 ) fluid outlet ports  38  and a single fluid inlet port  40 . In one implementation, the sprayer  12  has seventy ( 70 ) spray nozzle assemblies  26 . The outlet ports  38  are circumferentially spaced about manifold  42  which allows fluid to be dispensed from the nozzle assembly  26  at various angular positions as needed for the particulars of a given application. In this regard, in a typical implementation, all but one of the ports will be closed by a cap  44  while one of the ports will be fitted with an orifice cap  46 . The orifice cap  46  includes a spray nozzle  48 . The orifice cap  46  threads onto the outlet port in a conventional manner and can be easily replaced by other orifice caps having differently configured spray nozzles to allow an operator flexibility in how fluid is applied, such as droplet size, spray pattern, spray width, etc. The spray nozzle assembly  26  uses a conventional clamp  50  for coupling the spray nozzle assembly  26  to the header  34 . It is understood that other types of coupling devices may be used to fluidly connect the spray nozzle assembly to the distribution manifold. Also, while a five-way spray nozzle assembly is shown, it is understood that the invention is applicable with other types of spray nozzle assemblies. 
         [0019]    To detect and notify an operator that a spray nozzle is plugged, completely or partially, such as by dirt, debris, or chemical buildup, the present invention provides a remote alert system  100 , which is schematically illustrated in  FIG. 4 , and includes a thermal flow sensor  52  disposed within the nozzle body  36  in the flow path between the fluid inlet port  40  and the spray nozzle  48 , as best shown in  FIG. 3 . The thermal flow sensor  52  is free of moving parts and is thus believed to be more reliable than other types of flow sensors. Moreover, the thermal flow sensor  52  is made of corrosion-resistant materials and is therefore well suited for use with an agricultural sprayer. 
         [0020]    With reference to  FIGS. 3 and 4 , the thermal flow sensor  52  includes a sensor rod  54  having a heating element  56 , an upstream temperature sensor element  58  and a downstream temperature sensor element  60 . The sensor rod  54  is situated in the nozzle body  36  such that when the spray nozzle is plugged, or substantially plugged, flow past the sensor rod  54  will cease, or substantially flow. The heating element  56  is electrically coupled to a power source  62  so that as current passes through the heating element  56 , the fluid passing the sensor rod  54  is heated. Each sensor element  58 ,  60  measures a temperature of the fluid and provides a corresponding output signal to a circuit block  64  that provides an output voltage signal corresponding to the difference between the temperatures measured by the sensor elements  58 ,  60 . In one embodiment, the circuit block  64  includes a bridge  66  and amplifier  68 . The output signal is fed to a switch  70 , e.g., MOSFET, that activates an alert in the operator cab of the sprayer  12  when flow through the nozzle body  36  has stopped, or substantially stopped. That is, when the circuit block  64  provides an output voltage that is greater than the threshold voltage of the switch  70 , the switch  70  will close and provide an activation signal to an alert  72  for notifying the operator that a spray nozzle is plugged. 
         [0021]    In one embodiment, the alert  72  is a light  74  that is caused to be illuminated when flow through the nozzle body has stopped, or has substantially stopped. In one embodiment, the operator cab has a control panel (not shown) having a light for each nozzle assembly of the sprayer  12 . Accordingly, when a spray nozzle becomes plugged, the operator is notified of the specific nozzle that has become plugged and can then take measures to service the specific nozzle so that proper flow therethrough can be resumed. It is also contemplated that an audio alarm  76  may be sounded when a spray nozzle is determined to be plugged. The audio alarm  76  is preferably not used to indicate which spray nozzle is plugged but rather alert the operator that any of the spray nozzles are plugged and that the operator should then view the control panel for more information. 
         [0022]    In yet another embodiment, it is contemplated that the sprayer  12  may have an onboard computer or similar processing device and a display unit  78 , such as that illustrated in  FIG. 5 , which provides a graphical user interface  80  that displays the flow rate information for each of the spray nozzles of the sprayer  12 . The manner in which the flow rate information is displayed can take many forms, such as average or instantaneous flow rates or, as illustrated in  FIG. 5 , as a percentage of maximum flow. Color-coding, shading, and other tools may then be used on the GUI  80  to differentiate a spray nozzle that is substantially plugged. For instance, in the example shown in  FIG. 5 , spray nozzle # 7  has a flow rate that is significantly less than a maximum, or desired, flow rate, and as such, the bar reflecting flow rate information for spray nozzle # 7  is displayed in a different color than the bar for the other spray nozzles. 
         [0023]    Various alternatives and embodiments are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter regarded as the invention.