Patent Publication Number: US-2021176977-A1

Title: Continuously-variable nozzle system with integrated flow meter

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to a continuously-variable nozzle system (CVNS), and in particular to a system for interactively controlling operational variables in an automated or autonomous agricultural sprayer. 
     2. Description of the Related Art 
     Liquid application systems have utilized a wide variety of nozzle configurations and spray operation controls, which are generally based on the liquids being sprayed, environmental factors and other operational considerations. Without limitation, an exemplary application of the present invention is in a mobile agricultural spraying system, which applies liquids to field crops. Such liquids can comprise herbicides, pesticides, liquid fertilizers, nutrients and other substances. Crop field spray operations generally have the objectives of optimizing crop yields, maximizing spray operation efficiency (e.g., material usage) and minimizing unintended spray operation consequences (e.g., spray drift onto neighboring fields). 
     Spraying system operating condition variables generally include liquid viscosities, pump pressures, discharge nozzle configurations and fluid flow rates. These and other aspects of a spraying system can be controlled to deliver more or less liquid to target surfaces. However, changing the operating pressures and the flow rates in spraying systems can have adverse effects on other operational variables, such as droplet sizes and spray fan angles. For example, if the droplets are too small, the spray can be more susceptible to drift, even in relatively light wind conditions. Unintended drift of agricultural chemicals onto neighboring fields, water supply sources, non-cultivated land, livestock and individuals is generally undesirable. For example, spray operations which may be desirable for a target crop could be harmful to other crops located in adjacent fields. Accidental applications of harmful agricultural chemicals can create financial liabilities for applicators. 
     Another potential problem with spray operations relates to coverage gaps. For example, decreasing pressure can shrink spray pattern coverage, resulting in unintended coverage gaps and compromising spray operation effectiveness. Environmental conditions can also affect agricultural spraying system performance. For example, temperature and humidity can affect the spray material droplets and alter plant absorption. Effective spraying systems, especially for agricultural applications, preferably provide selective and/or individual control of the spray nozzles. Such control functionality can minimize overlapping spray patterns. It can also enable sectional control of the equipment by independently controlling individual nozzles or equipment sections with multiple nozzles. Relatively accurate spray patterns and material application rates can thus be achieved. For example, varying amounts of chemicals can be applied at different locations, e.g., based on criteria such as equipment sensor readings and pre-determined field conditions. Equipment turns causing differential nozzle ground speeds can also be accommodated because nozzles located over the sprayer-swath outside edges have higher ground speeds than nozzles located over the inside edges of equipment turns. Still further, equipment with differential nozzle control capabilities can automatically compensate for reduced-flow conditions, e.g., caused by worn and defective nozzles. 
     Croplands, pastures and other fields can be effectively sprayed using appropriate guidance and navigation systems. Current state-of-the-art agricultural vehicles commonly use a Global Navigation Satellite System (GNSS), such as the U.S.-based Global Positioning System (GPS), for precision guidance, prescription farming and material placement. 
     US-2017/0036228 discloses an intelligent spray nozzle having an input pressure sensor, a flow sensor, a flow modulator, a nozzle pressure sensor and an output orifice modulator. An output from the flow sensor is used to control the flow modulator and the output orifice modulator to control an output spray rate. An ultrasonic-based sensor and “time of flight” principal is used to measure the fluid flow. 
     The continuously variable nozzle system of the present invention addresses these sprayer performance objectives, and overcomes many of the deficiencies with prior art nozzle and control systems. Heretofore there has not been available a continuously variable nozzle system with the features and elements of the present invention. 
     BRIEF SUMMARY OF THE INVENTION 
     In accordance with an aspect of the present invention, a continuously-variable nozzle system (CVNS) is provided for a sprayer, such as an agricultural sprayer. The nozzle system is configured for connection to a spray liquid source and configured for continuously, variably controlling a spray characteristic. The nozzle system comprises a nozzle body with an inlet and an outlet, a conduit between the inlet and the outlet, and a flow meter disposed in the conduit. The flow meter comprises a chamber with internal helical splines configured to interact with a spray liquid passing through the chamber and create a cyclone-like effect, a sphere disposed inside the chamber for free movement along a circular path, and a sensor disposed outside the chamber and configured to detect motion of the sphere and generate an output signal in response to detected motion. 
     The invention delivers a “smart” nozzle system with a flow meter that has been found to be highly accurate when measuring very low flow rates or rapidly changing flow rates. This is due to the low friction and low inertia of the sphere arrangement. Furthermore the flow meter of the present invention is more reliable and robust compared to known flow meters for individual nozzles. 
     The nozzle system may be connected to a spray material source and configured to automatically control fluid pressures, discharge volume rates, droplet sizes and discharge spray patterns. 
     The flow meter preferably comprises an upper section, wherein the upper section comprises an outer wall of the chamber, and wherein the helical splines are provided on an inner surface of the outer wall. The flow meter may further comprise a lower section comprising a cone that projects from the base into the chamber, wherein the cone is aligned on a central axis, and wherein the circular path is disposed between the cone and the outer wall. In one preferred embodiment the upper section comprises a transparent material and the sensor is a photodiode that ‘looks’ through the transparent material at the sphere. A light source may be provided outside the chamber to illuminate the sphere and improve detection reliability by the photodiode. 
     In one embodiment an automated control system includes a microprocessor configured for receiving input signals representing operating condition variables and providing output signals for controlling adjustable sprayer parameters. The control system includes a feedback loop functions for interactively modifying sprayer parameters in real-time, responding to field, weather, crop and other conditions. 
     In a preferred embodiment the nozzle system further comprises a flow control valve disposed in the conduit, and an actuator for controlling the flow control valve. Advantageously, the flow control valve permits nozzle-by-nozzle regulation of the flow rate of spray liquid. The flow control valve is preferably a needle valve although other types of valve are viable. The actuator may be provided by a stepper motor for example. Alternatively, a voice coil (or non-commutated DC linear) actuator may be employed. 
     In another preferred embodiment the nozzle system may further comprise an electronic controller that is in communication with the sensor and the actuator for control of the flow control valve, wherein the controller is configured to compute a flow rate from the output signal and control the actuator in dependence upon the flow rate. 
     A pressure sensor may be mounted in the conduit downstream of the flow meter and configured to generate a pressure signal, wherein the controller is in communication with the pressure sensor and configured to receive the pressure signal. In one example of the system in operation a supply pressure of the spray liquid source and the flow control valve is controlled in dependence upon the measured flow rate and the nozzle pressure so as to maintain a desired flow rate and spray pattern. 
     The nozzle system may further comprise an impinging valve disposed in the conduit downstream of the flow control valve, and a further actuator for controlling the impinging valve, wherein the impinging valve serves to modify a mean droplet size of a spray output. Advantageously, the provision of an impinging valve in addition to a flow control valve permits a high degree of nozzle-by-nozzle control of the output spray characteristics, especially with regard to droplet size and flow rate. 
     The nozzle system can be embodied, by way of example only, in a sprayer that can be configured as a self-propelled vehicle, a mounted or a towed implement, or an unmanned aerial vehicle. 
     The CVNS of the present invention is adaptable for retrofitting in aftermarket installations, and for original equipment manufacturing (OEM) applications. The modular design accommodates such various applications. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further advantages of the invention will become apparent from reading the following description of specific embodiments with reference to the accompanying drawings. The drawings constitute a part of this specification and include exemplary embodiments of the present invention illustrating various objects and features thereof. 
         FIG. 1  is a block diagram of an automated sprayer including a continuously variable nozzle system (CVNS) embodying an aspect of the present invention. 
         FIG. 2  is a front, perspective view of the CVNS. 
         FIG. 3 a    is a front, upper, right side perspective view of the CVNS, shown in an exploded configuration. 
         FIG. 3 b    is another front, upper, right side perspective view of the CVNS, shown in an exploded configuration. 
         FIG. 4 a    is a vertical, cross-section thereof in a closed configuration. 
         FIG. 4 b    is another vertical cross-section thereof in an open configuration. 
         FIG. 5  is a perspective view of a linear stepper motor thereof, mounting a needle valve. 
         FIG. 6  is another perspective view of the linear stepper motor, particularly showing a junction box thereof. 
         FIG. 7  is an enlarged, cross-section with an impinging valve or nozzle subassembly in a closed position, taken generally in circle  7  in  FIG. 4   a.    
         FIG. 8  is an enlarged, cross-section with the impinging valve or nozzle subassembly in an open position, taken generally in circle  8  in  FIG. 4   b.    
         FIG. 9  is an enlarged, cross-section of the impinging valve or nozzle subassembly. 
         FIG. 10  is an enlarged, cross-section of the impinging valve or nozzle subassembly, taken generally in circle  10  in  FIG. 8 . 
         FIG. 11  is a perspective view of the impinging valve or nozzle subassembly. 
         FIG. 11 a    is a perspective view of the impinging nozzle insert. 
         FIG. 11 b    is a perspective view of the impinging nozzle valve. 
         FIG. 12  is a cross-section of a flow meter of the CVNS, taken generally in circle  12  in  FIGS. 4 a    and  4   b.    
         FIG. 13  is an enlarged, fragmentary view of the flow meter an adjacent enclosure panel mounting and LED and a photodiode sensor for detecting passage of a tracking ball. 
         FIG. 14  is an enlarged, fragmentary top plan view of portions of the flow meter shown, taken generally along line  FIG. 14  in  FIG. 13 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     I. Introduction and Environment 
     As required, detailed aspects of the present invention are disclosed herein, however, it is to be understood that the disclosed aspects are merely exemplary of the invention, which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art how to variously employ the present invention in virtually any appropriately detailed structure. 
     Certain terminology will be used in the following description for convenience in reference only and will not be limiting. For example, up, down, front, back, right and left refer to the invention as orientated in the view being referred to. The words, “inwardly” and “outwardly” refer to directions toward and away from, respectively, the geometric center of the aspect being described and designated parts thereof. Forwardly and rearwardly are generally in reference to the direction of travel, if appropriate. Said terminology will include the words specifically mentioned, derivatives thereof and words of similar meaning. 
     II. Sprayer  2   
     In the practice of an aspect of the present invention, a CVNS  4  is shown in a sprayer  2 . Without limitation on the generality of useful applications of the present invention, the sprayer  2  can be configured for agricultural sprayer applications, e.g., either self-propelled, mounted or towed behind a tractor. As shown in  FIG. 1 , a fluid supply  6  is connected to a generally horizontal tubular supply manifold  8 , which can be mounted in front of or behind a vehicle and supported on a boom structure. For agricultural operations, the manifold  8  can extend substantially the width of a crop field swath, e.g., with multiple CVNSs  4  mounted thereon at spaced intervals corresponding to respective crop row spacing. 
     Each CVNS  4  comprises a nozzle body  5  having an input  7  and an output  9  shown diagrammatically in  FIG. 1 . Fluid enters the CVNS  4  through input  7  into a flow meter  10  (described in more detail below), which generates an output signal corresponding to the flow rate, which signal is input to the guidance and control microprocessor  12 . The fluid flow rate is automatically controlled by a needle valve  14  connected to a linear stepper motor  16 . A pressure sensor  18  monitors fluid pressure and outputs a corresponding signal for input to the microprocessor  12 . 
     The fluid enters an impinging valve  20  controlled by another linear stepper motor  22  connected to the microprocessor  12 . Depending on the impinging valve  20  open/closed condition, fluid either discharges from the impinging valve  20  or is diverted to an optional discharge valve  24 . A fluid-conveying conduit is thus provided between the input  7  and output  9  a series connected plurality of components including the flow meter  10 , needle valve  14  and impinging valve  20 . 
     The guidance and control microprocessor  12  receives inputs from the flow meter  10 , the pressure sensor  18  and, optionally, from an external data connection  26 . The external data connection  26  can comprise a variety of resources, such as the Internet (e.g., via the “Cloud”) an operator, a smart device, a LAN, a WAN, electronic storage media, etc. Moreover, multiple vehicles and equipment pieces with CVNSs can be linked and their operations coordinated. Such vehicles and equipment pieces can be assigned individual operators, or can operate autonomously. 
     III. Continuously-Variable Nozzle System (CVNS)  4   
     As shown in  FIG. 2 , the nozzle body  5  defines an enclosure  30 , which can comprise a high-density, where-resistant material, e.g., Acetal plastic. However, the enclosure  30 , and other components of the CVNS  4 , can comprise other durable materials, including metals, ceramics, etc. The enclosure  30  generally comprises a mounting frame  32  and a cover  34 , which can comprise injection-molded components. The CVNS  4  is attached to the manifold  8  by a plug-in, modular, boom mounting clamp  36  with upper and lower jaws  38 ,  40  (e.g., injection molded plastic) digitally connected by a pressed hinge pin  42  and clamp together by a clamping bolt fastener  44 . Connections throughout the CVNS  4  can be sealed fluid-tight by appropriate O-rings, gaskets, sealants and other connecting devices and techniques. Without limitation, O-rings are shown and are generally designated  46 . The lower jaw  40  includes a pipe insert  48  with slots  50  allowing complete drainage of fluids in the manifold  8  to the CVNS  4 . 
     As shown in  FIG. 3 a   . the flow meter or sensor  10  and the impinging valve or nozzle subassembly  20  can be secured to the enclosure  30  by suitable U-shaped clips  28 . 
     As shown in  FIGS. 4 a  and 4 b   , the CVNS  4  has closed and open configurations respectively. For example,  FIG. 4 a    shows both the needle valve  14  and the impinging valve  20  closed. With the valves  14 ,  20  open ( FIG. 4 b   ) fluid enters from the boom or manifold  8  through an opening in the boom mounting clamp  36 , enters the flow meter  10  and spins a sphere  52  located therein. The needle valve  14  is mounted on a linear actuator, which can comprise a stepper motor  16 , which varies the flow, either incrementally (e.g., with a stepper motor as shown) or continuously. Pressure in the enclosure  30  can be monitored by the pressure sensor  18 , which can comprise a diaphragm gasket-type construction for mounting on a printed circuit board (PCB)  54  forming a sidewall of the enclosure  30  and closed by a side cover panel  56  ( FIG. 3 a   ). The needle valve  14  controls droplet size, fluid pressure and flow rate. 
     A needle valve seat  58  acts as a seal against the needle valve  14  as the needle valve closes down to restrict flow. As the fluid passes through the CVNS  4 , the pressure of the fluid is red by the pressure sensor  18 , which is covered by a gasket  19  preventing fluid from directly contacting the sensor  18  and the PCB  54 . The positions of the needle valve  14  and the impinging valve  20  are monitored with a magnet  60 , which is pressed into a magnet holder  62  mounted on and sliding with respective motor shafts  64 ,  66 . The magnets  60  interact with magnet sensors (not shown) in the enclosure  30 , which provide output signals to the controller  12  for monitoring and controlling the positions of the valves  14 ,  20 , e.g., through an appropriate feedback loop. The needle valve  14  ( FIG. 5 ) can comprise a relatively soft material, such as brass or acetyl thermoplastic. In one embodiment the needle valve  14  is formed from a polyoxymethylene (POM), (also known as acetal, polyacetal), and polyformaldehyde, as commonly used in precision parts requiring high stiffness, low friction, and excellent dimensional stability. Relatively tight tolerances or preferably provided with a relatively precise cone shaped to allow for proper sealing. As shown, the needle valve  14  has a dual-ramp configuration, or is otherwise variably contoured geometrically for optimizing a linear or otherwise defined flow rate response. 
     As shown in  FIG. 6 , the motors  16 ,  22  can include suitable junction boxes with electrical and mechanical connections to other components of the CVNS  4 . 
       FIG. 7  shows the impinging valve  20  in a closed position. The impinging valve  20  opens and closes to discharge fluid and create a desired fluid flow. Acetyl thermoplastic can be used for forming the impinging valve  20  components, due to its resistance to chemicals and low coefficient of friction. The impinging valve  20  generally includes an impinging nozzle insert  68  ( FIG. 11 ) and an impinging nozzle valve  70  with relatively precise dimensions and geometries for achieving a desired fluid flow. The impinging nozzle insert  68  and valve  70  are shown in  FIG. 9  (closed) and  FIG. 10  (open). The interaction between the insert  68  and about 70 create desired flow patterns at various flow rates. The impinging nozzle valve  70  slides along the  68  to effectively change the flow rate in droplet size of the fluid exiting the CVNS  4  the fluid 1st passes through  3  orifice  72  on the insert  68 , which creates an increase in the fluids velocity. A turbulence pocket  74  is formed between the insert  68  and the valve  70 . The shape of the turbulence pocket  74  allows the fluid to swirl. The increased velocity of the fluid increases the turbulence of the fluid within the pockets  74 . The fluid then exits the turbulence pocket  74  at a final orifice  76 , which is the final interface between the valve  70  and the insert  68 . As the valve  70  slides across the insert  68 , the opening size of the final orifice changes, causing change in flow rate in droplet size of the fluid. Upon exiting the final orifice  76 , the fluid follows the path of a ramp  78  formed by the impinging nozzle valve  70 . The length of the ramp  78  should be long enough to create a flat sheet of fluid, but not so long as to allow the fluid sheet to re-convergence into streams after exiting the turbulence pocket  74 . 
     With reference to  FIGS. 12 to 14  the flow meter  10  comprises an upper section  80  and a lower section  81 , one or both of which are preferably injection molded. The upper section  80  provides an outer wall of a chamber  83  through which the spray fluid flows. The lower section  81  comprises a cone portion  85  the projects away from a base portion  87  into the chamber  83 . The cone portion  85  extends along a central axis  100  of the flow meter  10 . 
     A fluid passage is defined through the chamber  83  from an inlet side  102  to an outlet side  104  between the inside surface of upper section  80  and an external surface of cone portion  85 . Helical splines  82  are provided on an inner surface of the outer wall and serve to interact with the fluid to create a cyclone-like effect, which spins the flow meter sphere  52  inside the flow meter  10 , along a circular path  106 . The speed of revolution of the sphere  52  is proportional to the fluid flow allowing the flow rate of fluid running through the CVNS  4  to be measured. In a preferred embodiment of the flow meter  10 , it comprises a clear material so that the motion of the sphere  52  inside can easily be read. In an alternative embodiment, magnetic sensors, acoustic sensors or ultrasonic sensors can be used. 
     An important characteristic of this particular flow meter design is its ability to measure very low flow rates and rapidly changing flow rates with high accuracy. This is due to the low friction and low inertia of the sphere arrangement. In a preferred embodiment, the density of the sphere material should match that of the spraying liquid. For example, acrylic material, or plexiglass, with a density of 1.17-1.20 g/cm 3 , is particularly suited to spraying liquids with a density dose to 1.0 g/cm 3 . 
     As shown in  FIGS. 13 and 14 , an LED  84  and a photodiode  86  are mounted on the inside of the PCB  54 , facing the flow meter  10 . The LED, or other suitable light source, illuminates the sphere  52 , which reflected light is sensed by the photodiode  86 , which provides an output signal as an input to the microprocessor  12  for counting passes by the sphere  52 , thus enabling computing flow rate. The configurations of the sphere  52 , the LED  84  and the photodiode  86  are very able to accommodate different fluid properties and other conditions, which can include fluid collar, turbidity, contamination and dulling of the optically relevant surfaces of the device, which can occur from aging and hazing effects on plastics. The output of the photodiode  86  is an input to a trans-impedance amplifier, followed by an analog low pass filter with a predetermined cutoff frequency. These components can be incorporated into the flow meter  10  and/or the processor  12 , which interact. The resulting voltage-based signal is output as an input to the processor  12 , which samples the analog signal with an analog-to-digital (A/D) converter. Signal processing techniques are utilized to determine the fluid flow rate. O-rings  46  or other sealing measures are utilized to prevent fluid from entering the top of the nozzle body enclosure. As an alternative implementation, the output of the trans-impedance amplifier can be utilized as input to a compared tour to generate a digital signal the digital signal can provide input to a timer/capture/compare unit on the processor to measure the time between pulses corresponding to sphere passes by the photodiode. 
     For many agricultural operations the discharge from the CVNS  4  will be through the impinging valve or nozzle subassembly  20 . Alternatively, a lower discharge tube  88  can be provided and can include lugs  90  for removably mounting a cap  92  for closing the discharge tube  88 . Alternatively, the cap  92  can be replaced with or connected to a suitable spray discharge nozzle (not shown) for bypassing the impinging valve or nozzle subassembly  20  in operation. 
     Alternative flow meters include, without limitation, thermal mass flow meters, ultrasonic flow sensors, electromagnetic flow meters, acoustic material flow meters and sensors, impeller flow meters, axial turbine flow meters, paddlewheel flow sensors, and a standalone flow meter spray system component that is unconnected to the needle and impinging valves  14 ,  20 . 
     Although the spraying system is particularly suited for agricultural applications, various other applications for flexibly controlling and managing the flow of liquid material can be accommodated. For example, prescription farming operations can benefit from such control measures. Farmers and other machine users can thus place water, chemicals, liquid fertilizers, or any other liquid material, as well as controlling quantities deposited. Such control provides a solution to the issues such as over-application and underapplication of liquid material. 
     Other undesirable consequences, which can be mitigated with the present invention, include drift with airborne droplets, issue is exacerbated with smaller droplet sizes. Application on unintended target areas can thus be mitigated. Moreover, the present invention can communicate with a control system on a machine, such as a vehicle, for navigating and controlling precision farming operations. Such navigational and positioning systems can include a global navigation satellite system (GNSS), e.g., the U.S.-based global positioning system (GPS). Real-time kinematic (RTK), inertial and other navigational/positional procedures can also be used. Interactive communication with vehicles and other equipment and machines can coordinate and control other aspects of precision farming and other operations. For example, multiple CVNSs  4  can be selectively and individually controlled, or can be controlled collectively in sections or on entire implements. 
     It is to be understood that the invention can be embodied in various forms, and is not to be limited to the examples discussed above. The range of components and configurations which can be utilized in the practice of the present invention is virtually unlimited.