Abstract:
An agricultural sprayer arrangement includes a chassis; a ground engaging traction member carried by the chassis; a liquid tank carried by the chassis; a boom carried by the chassis; a conduit associated with the boom in fluid communication with the liquid tank that acts as a fluid flow path; a nozzle having an inlet in fluid communication with the conduit; a first flow sensor placed upstream of the inlet in the fluid flow path that provides a first flow signal; a second flow sensor placed downstream of the inlet in the fluid flow path that provides a second flow signal; and an electrical processing circuit coupled to the first flow sensor and the second flow sensor that is configured to compare the first and second flow signals to determine a flow rate decrease and issue an alarm if the flow rate decrease is less than a predetermined threshold level.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This divisional patent application is based on and takes priority from U.S. patent application Ser. No. 14/322,248 filed Jul. 2, 2014, entitled, “DEVICE AND METHOD FOR DETECTING BLOCKAGES IN AN AGRICULTURAL SPRAYER,” which is hereby incorporated by reference herein in its entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to agricultural sprayers, and, more particularly, to detecting a nozzle blockage in an agricultural sprayer. 
         [0004]    2. Description of the Related Art 
         [0005]    Agricultural sprayers apply a liquid to a crop or the ground at a specified application rate. The liquid may be in the form of a solution or mixture, with a carrier liquid (such as water) being mixed with one or more active ingredients (such as an herbicide, fertilizer, fungicide and/or a pesticide). The application rate can vary over different parts of a field through the use of precision farming techniques, such as by using GPS data to activate/deactivate boom sections of the sprayer as the sprayer traverses over the field. 
         [0006]    Agricultural sprayers may be pulled as an implement or self-propelled, and typically include a tank, a pump, a boom assembly, and a plurality of nozzles carried by the boom assembly at spaced locations. The boom assembly typically includes a pair of wing booms, with each wing boom extending to either side of the sprayer when in an unfolded state. Each wing boom may include multiple boom sections, each with a number of spray nozzles (also sometimes referred to as spray tips). Of course, a self-propelled sprayer also includes an onboard power plant (e.g., diesel engine) providing motive force and other power such as hydraulic power, electrical power, etc. 
         [0007]    The spray nozzles on the boom disperse one or more liquids from a tank carried by the sprayer on to a field. Each spray nozzle typically connects to a fluid conduit that is carried by the boom and receives a fluid flow from the tank, typically supplied to the fluid conduit by a pump. The nozzles have an inlet that connects to the fluid conduit and allows the fluid flow through the conduit to flow into the nozzle, which distributes the fluid to the field in a droplet or spray mist form. 
         [0008]    During a spray operation, one or more of the nozzles can become clogged due to various reasons such as impurities in the carrier or active ingredient(s) accumulating in the nozzle. The nozzles are typically optimized to reduce application overlap during the spray operation, so even a single clogged nozzle can cause the active ingredient to be improperly applied to the field and leave strips unsprayed which may require a make-up run that generates no revenue but requires additional fuel and labor costs. A make-up run also causes additional ground compaction due to more passes and timing delays in killing the target pest or other operations dependent upon the spray application. 
         [0009]    One known way to determine whether a blockage exists within a nozzle is to place a flow rate sensor within the nozzle. The sensor outputs a signal that corresponds to the fluid flow rate within the nozzle, which is compared to a preset value to determine whether a blockage exists in the nozzle. Such arrangements place a relatively large sensor within the fluid flow path in the nozzle, which is usually small, that can disrupt the fluid flow through the nozzle. Depending on the configuration of the nozzles, it can also be difficult to replace the sensors within the nozzle if the sensor fails. 
         [0010]    What is needed in the art is a less invasive way to detect nozzle blockages in an agricultural sprayer. 
       SUMMARY OF THE INVENTION 
       [0011]    The present invention provides an agricultural sprayer arrangement that compares a reference flow rate before a nozzle to a flow rate past the nozzle to determine whether a blockage exists in the nozzle. 
         [0012]    The invention in one form is directed to an agricultural sprayer arrangement that includes a chassis, at least one ground engaging traction member carried by the chassis, a liquid tank carried by the chassis, a boom carried by the chassis, a fluid conduit associated with the boom that is in fluid communication with the liquid tank and configured as a fluid flow path, a nozzle that has an inlet in fluid communication with the fluid conduit, a first flow sensor placed upstream of the inlet in the fluid flow path that provides a first flow signal, a second flow sensor placed downstream of the inlet in the fluid flow path that provides a second flow signal, and an electrical processing circuit coupled to the first flow sensor and second flow sensor. The electrical processing circuit is configured to compare the first flow signal to the second flow signal to determine a flow rate decrease and to issue an alarm if the flow rate decrease is less than a predetermined threshold level. 
         [0013]    The invention in another form is directed to a method for detecting a blockage in an agricultural sprayer that includes the steps of providing a sprayer that includes a chassis, at least one ground engaging traction member carried by the chassis, a liquid tank carried by the chassis, a boom carried by the chassis, a fluid conduit associated with the boom, a pump configured to produce a liquid flow through at least a portion of the fluid conduit from the liquid tank, a nozzle that has an inlet fluidly connected to the liquid flow in the fluid conduit, a first flow sensor in the liquid flow upstream of the inlet, and a second flow sensor in the liquid flow downstream of the inlet. A first flow rate is determined at the first flow sensor and a second flow rate is determined at the second flow sensor. The first flow rate is compared to the second flow rate to determine a flow rate decrease. A blockage in the nozzle is reported when the flow rate decrease is less than a determined threshold level. 
         [0014]    An advantage of the present invention is that the flow rate sensors are not placed within the nozzle and have less of an impact on the fluid flow rate through the nozzle. 
         [0015]    Another advantage is that the flow rate sensors are in a location where they can be easily replaced. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein: 
           [0017]      FIG. 1  is a perspective view of an agricultural sprayer of the present invention; 
           [0018]      FIG. 2  is a sectional view of a portion of a wing boom section shown in  FIG. 1 ; 
           [0019]      FIG. 3  is a schematic view of an electrical processing circuit of the present invention; 
           [0020]      FIG. 4  is a perspective view of an unclogged nozzle in operation; 
           [0021]      FIG. 5  is a perspective view of a partially clogged nozzle in operation; 
           [0022]      FIG. 6  is a waveform diagram of an output signal that indicates an unclogged nozzle; 
           [0023]      FIG. 7  is a waveform diagram of an output signal that indicates a partially clogged nozzle; and 
           [0024]      FIG. 8  is a bar graph illustrating flow rate percentage deviations in an agricultural sprayer for unclogged and partially clogged sprayer nozzles 
       
    
    
       [0025]    Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate embodiments of the invention and such exemplifications are not to be construed as limiting the scope of the invention in any manner. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0026]    Referring now to the drawings, and more particularly to  FIG. 1 , there is shown an agricultural sprayer  10  according to one embodiment of the present invention. Agricultural sprayer  10  is shown as a self-propelled sprayer with a plurality of wheels  12  and a prime mover in the form of an internal combustion (IC) engine (e.g., diesel engine) within an engine compartment  14 . However, agricultural sprayer  10  could also be configured as a towed sprayer which is towed behind a work vehicle such as a tractor. Moreover, agricultural sprayer could also be a track-type self-propelled vehicle for certain applications. 
         [0027]    Agricultural sprayer  10  includes a chassis  16  to which a pair of wing booms  18 ,  20  are connected, united by a center boom  19 . For sake of description, wing boom  18  is considered a left wing boom and wing boom  20  is considered a right wing boom. The wing booms  18 ,  20  are connected to center boom  19 , joined about respective pivot connections  22 ,  24 . Center boom  19  is connected at or near the rear of chassis  16 . The wing booms  18 ,  20  are designed to fold forward toward the leading end of chassis  16  when wing booms  18 ,  20  are moved from an extended position, shown in  FIG. 1 , to a stowed or transport position (not shown). 
         [0028]    Each wing boom  18 ,  20  supports a number of boom sections  18 A,  18 B,  18 C,  20 A,  20 B and  20 C. Center boom  19  and wing boom sections  18 A,  18 B,  18 C,  20 A,  20 B and  20 C each include a number of spray nozzles (not shown). In the embodiment shown, each wing boom has three boom sections, corresponding to the fold locations of the wing boom. In the illustrated embodiment, the spray nozzles of center boom  19  and wing boom sections  18 A,  18 B,  18 C,  20 A,  20 B and  20 C are fluidly connected in parallel relative to each other. Moreover, the spray nozzles within center boom  19  and a same wing boom section  18 A,  18 B,  18 C,  20 A,  20 B or  20 C are typically connected together in series. This arrangement of spray nozzles allows the spray nozzles of center boom  19  and wing boom sections  18 A,  18 B,  18 C,  20 A,  20 B and  20 C to be independently turned on and off as sprayer  10  advances across a field (e.g., manually or using GPS data). A liquid tank  26  is carried by the chassis  16  and supplies carrier fluid mixed with active ingredient(s) to the spray nozzles for dispersion on a field. Although the liquid tank  26  is shown as a single tank, the present invention contemplates multiple liquid tanks supplying a solution of carrier fluid mixed with active ingredient(s) to the spray nozzles. 
         [0029]    Referring now to  FIG. 2 , a sectional view of a portion of wing boom section  18 A is shown. Although a section of wing boom section  18 A is shown, the present invention contemplates that any of the other wing boom sections  18 B,  18 C,  20 A,  20 B and  20 C can be structured in a similar manner. As can be seen, a fluid conduit  38  is associated with wing boom section  18 A and is supplied with fluid from liquid tank  26  by a pump  40  that is connected to the liquid tank  26  and the fluid conduit  38 . In the illustrated embodiment, fluid conduit  38  is assumed to be a reinforced hose which is carried by wing boom section  18 A and is supplied with fluid from liquid tank  26  by a pump  40  that is connected to the liquid tank  26  and the fluid conduit  38 . Arrows  42  and  44  represent the fluid flow direction through fluid conduit  38 , with “downstream” referring to the direction that arrows  42  and  44  point (to the right of the page) and “upstream” referring to the direction opposite downstream (to the left of the page). Reference to “downstream” and “upstream” are used only for convenience in describing the relative locations of various elements of the present invention and are not intended to limit the scope of the invention. A series of spray nozzles N 4 , N 3 , N 2 , N 1  are fluidly connected to the fluid conduit  38  and are configured to disperse fluid from the liquid tank  26  to a field that the agricultural sprayer  10  is travelling across. Each spray nozzle N 4 , N 3 , N 2 , N 1  has a respective inlet  46 ,  48 ,  50 ,  52  where fluid from the fluid conduit  38  enters the spray nozzle N 4 , N 3 , N 2 , N 1 . Typically, the inlets  46 ,  48 ,  50 ,  52  have a diameter that is significantly smaller than the diameter of the fluid conduit  38 . 
         [0030]    Flow rate sensors S 5 , S 4 , S 3 , S 2 , S 1  are placed in the fluid conduit  38  to measure a local fluid flow rate at each sensor&#39;s location. Each flow rate sensor S 5 , S 4 , S 3 , S 2 , S 1  provides an output signal that can be processed by an electrical processing circuit (described later) to determine the local fluid flow rate. Flow rate sensors S 5 , S 4 , S 3 , S 2 , S 1  are shown as being thermal dispersion flow rate sensors, which don&#39;t have moving parts, but any flow rate sensor is contemplated for use in the present invention. Similarly, the flow rate sensors S 5 , S 4 , S 3 , S 2 , S 1  shown will provide an output signal with varying frequency to indicate different local fluid flow rates, but flow rate sensors that output signals with varying voltages could also be used. As can be seen, each spray nozzle N 4 , N 3 , N 2 , N 1  has a pair of associated flow rate sensors, with one of the flow rate sensors being upstream of the nozzle&#39;s inlet and the other flow rate sensor being downstream of the nozzle&#39;s inlet. For example, spray nozzle N 4  has associated flow rate sensor S 5  upstream of the inlet  46  and associated flow rate sensor S 4  downstream of the inlet  46 . Similarly, spray nozzle N 3  has associated flow rate sensor S 4  upstream of the inlet  48  and associated flow rate sensor S 3  downstream of the inlet  48 . It can therefore be seen that each spray nozzle does not need a separate pair of associated flow rate sensors, but one or more flow rate sensors can be associated with one or two nozzles. 
         [0031]    Referring now to  FIG. 3 , a diagram of an electrical processing circuit (EPC)  54  of the present invention is shown. The EPC  54  is configured to determine whether a blockage exists in the nozzles, based on output signals from the flow rate sensors S 5 , S 4 , S 3 , S 2 , S 1 , and can be configured as any type of suitable processor, such as a digital controller, an analog processor, hardwired components or an application specific integrated circuit (ASIC). The EPC  54  can include a multiplexer  56  that is coupled to the flow rate sensors S 5 , S 4 , S 3 , S 2 , S 1  and a frequency converter  58  that converts the varying frequency output signals from the sensors S 5 , S 4 , S 3 , S 2 , S 1  to varying voltage signals. If flow rate sensors that provide varying voltage output signals are used, the frequency converter  58  is not necessary. The varying voltage output signals are received by an amplifying filter  60 , which will increase the voltage of the output signals and remove signal noise. It is useful if the amplifying filter  60  adds a high gain to the varying voltage output signals, for reasons that will be described below. The amplified output signal is then received by a de-multiplexer  62 . When a multiplexer  56  and de-multiplexer  62  are used to send output signals from each individual flow rate sensor S 5 , S 4 , S 3 , S 2 , S 1  across a single path, a timing circuit  64  is included to generate a clock signal that controls the multiplexer  56  and de-multiplexer  62 . This allows each flow rate sensor&#39;s output signal to be sorted out by the EPC  54 . The timing circuit  64  includes a timer  66  and a counter  68  to control the multiplexer  56  and de-multiplexer  62 . 
         [0032]    A subtractor  70  is coupled to the de-multiplexer  62  and receives the amplified output signals. Once two amplified output signals are received, the subtractor  70  can output a differential signal, which has a voltage equal to the difference between the two received signals, to a multi-channel display  72  that is coupled to the subtractor  70 . For example, flow rate sensor S 5  can output a signal that gets converted and amplified to have a voltage V 1  and flow rate sensor S 4  can output a signal that gets converted and amplified to have a voltage V 2 . The signals are transmitted through multiplexer  56  and the de-multiplexer  62  to the subtractor  70 , which can subtract voltage V 2  from voltage V 1  to produce a differential signal that corresponds to the nozzle N 4 . The differential signal is then output to the multi-channel display  72 , which can be placed in view of a user and configured to report an alarm if one or more spray nozzles is clogged, based on the differential signal received from the subtractor  70 . One multi-channel display  72  that could be used is commercially sold as the AFS Pro  700  by Case IH Corporation. It is contemplated that the multi-channel display  72  can also be interactive so that a user could, for example, reset an issued alarm through the multi-channel display  72  if a false positive clogged condition is reported. While a differential signal from sensors S 5  and S 4  is described that corresponds to nozzle N 4 , all the nozzles N 4 , N 3 , N 2 , N 1  shown can have corresponding differential signals produced from the nozzle&#39;s associated sensors. As shown in  FIG. 2 , nozzle N 4 &#39;s associated sensors are sensors S 5  and S 4 ; nozzle N 3 &#39;s associated sensors are sensors S 4  and S 3 ; nozzle N 2 &#39;s associated sensors are sensors S 3  and S 2 ; and nozzle N 1 &#39;s associated sensors are sensors S 2  and S 1 . While four nozzles N 4 , N 3 , N 2 , N 1  and five sensors S 5 , S 4 , S 3 , S 2 , S 1  are shown, it is contemplated that fewer or more nozzles and sensors could be utilized by the present invention. It is only required that each nozzle have a pair of associated sensors. 
         [0033]    Referring now to  FIGS. 4 and 5 , an unclogged spray nozzle  74  is shown operating in  FIG. 4  and a partially clogged spray nozzle  76  is shown operating in  FIG. 5 . As can be seen, the partially clogged spray nozzle  76  is still dispersing fluid, but at a lower rate than the unclogged spray nozzle  74 . Under the principle of continuity, the flow rate of liquid in the fluid conduit  38  will drop across each nozzle N 4 , N 3 , N 2 , N 1  by an amount that is equal to the flow rate of liquid out the respective nozzle N 4 , N 3 , N 2 , N 1 . Using this relationship, it can be determined whether a nozzle is blocked or not based on the difference in flow rates at a location directly upstream of the nozzle and directly downstream of the nozzle. A greater dispersed liquid flow rate will lead to a greater flow rate drop across the nozzle, leading to a greater differential signal being output by the subtractor  70 . If using a frequency converter  58 , this means that a differential signal with a higher voltage corresponds to a greater flow rate through a particular nozzle. The associated sensors for each nozzle can be configured to output a signal that is directly affected by changes in flow rate decreases, allowing for the percentage of unobstructed flow rate through each nozzle to be determined based on a known unobstructed flow rate and the obtained differential signal from the associated sensors. 
         [0034]    The multi-channel display  72  can be configured so that an alarm is issued upon receiving a differential signal below a predetermined threshold value that indicates a flow rate decrease below a predetermined threshold level. As the predetermined threshold value directly correlates to a predetermined threshold level of flow through the nozzle, the terms can be used interchangeably when referring to flow rate measurement in the present invention. The predetermined threshold value can be set as any value that indicates a nozzle is not clogged, which can be easily determined by sampling flow rate decrease values of known unclogged nozzles to determine values that correlate to unobstructed flow rates. One simple example of a predetermined threshold value is the voltage required to keep an LED light (not shown) included in the multi-channel display  72  turned on. When the differential signal drops below a certain voltage, indicating a low difference in flow between two associated sensors and potential clog in the nozzle, the LED light can turn off. A turned off LED light could then act as an alarm to an operator that there is a nozzle that may not be properly functioning. Each nozzle&#39;s associated pair of sensors can be coupled to a single LED in the multi-channel display  72  using the multiplexer  56 , de-multiplexer  62  and subtractor  70 , allowing for a large number of nozzles to be monitored simultaneously. Other more elaborate ways of determining whether the differential signal indicates a clogged nozzle and reporting a blockage could be used, such as signal processing being performed within the multi-channel display  72  that creates an audible or visual alarm on the multi-channel display  72  when the received differential signal indicates a clogged nozzle. Since the difference between two flow sensors might be low, even when the nozzle is unclogged, high gains added by the amplifying filter  60  can allow for greater precision in determining whether a nozzle is clogged or not by increasing the effect on the differential signal. Larger differential signals allow for a greater range of predetermined threshold values to be chosen that indicate an unclogged vs. partially or fully clogged nozzle. 
         [0035]    While the EPC  54  is shown in  FIG. 3  as utilizing a frequency converter and subtractor, it is also contemplated that associated sensors could be coupled together to produce a single output signal with varying frequency, which could then be the differential signal.  FIG. 6  shows an example differential signal produced by associated sensors of unclogged nozzle  74  that are coupled together and  FIG. 7  shows an example differential signal produced by associated sensors of partially clogged nozzle  76  that are coupled together. As can be seen, the frequency of the signal output by the associated sensors in  FIG. 6  has a relatively high frequency, indicating an unclogged nozzle, compared to the frequency of the signal output by the associated sensors in  FIG. 7 , which indicates a partially clogged nozzle. The predetermined threshold value could therefore be a certain signal frequency that is processed by the multi-channel display  72 , with frequency values below the predetermined threshold value indicating a clogged nozzle. 
         [0036]    It is normal for the flow rate between identically structured nozzles to deviate from each other, as shown in  FIG. 8 . The flow rate through the unclogged nozzles  1 ,  2 ,  3 ,  4 ,  5 ,  6 ,  8 ,  9  and  10  are shown as varying between approximately 90% and a little over 100% of maximum flow. The unclogged nozzles  1 - 6 , and  8 - 10  have a relatively tight distribution of flow rate percentages. Nozzle  7  is shown with a significantly lowered flow rate of just over 40%, which is indicative that the nozzle  7  has been clogged. It is therefore contemplated that the predetermined threshold value chosen before an alarm is issued can take into account normal flow rate deviations that are not indicative of a clogged spray nozzle. The predetermined threshold value can be chosen to issue an alarm when it correlates to a flow rate of 80% or lower of maximum flow, which could be indicative of a spray nozzle clogging. It is also contemplated that the predetermined threshold value can correlate to a flow rate percentage that deviates from the median or average flow rate of all spray nozzles by a certain number of standard deviations calculated by the EPC  54 . It is also contemplated that multiple alarms can be issued, such as a warning alarm that alerts a user to a pressure difference signal which correlates to a flow rate percentage of below 90% but above 80% and a clogged alarm that alerts a user to a pressure difference signal which correlates to a flow rate percentage of below 80%. The predetermined threshold values before issuing an alarm are given only by way of example and not to limit the scope of the invention in any manner. 
         [0037]    While this invention has been described with respect to at least one embodiment, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.