Patent Description:
In agricultural spraying, the flow rate through a spray nozzle is an important factor in delivering a specified amount of agrochemical to a specified area. Most agrochemicals such as crop protection agents and many fertilizers are applied as liquid solutions, suspensions, and emulsions that are sprayed onto the target fields. Certain agrochemicals, such as anhydrous ammonia, are dispensed into soil through dispensing tubes positioned behind knives or plows that prepare the soil for application.

Typically, the agrochemical liquid is supplied by powered pumps to simple or complex orifice nozzles that atomize the liquid stream into spray droplets. Nozzles are often selected primarily on the desired range of flow rates needed for the job and secondarily on the range of liquid droplet size spectra and spray distribution patterns they produce.

Increasing concerns over inefficient agrochemical use, the cost of agrochemicals and inadvertent spray drift or pesticide run-off have resulted in attempts to improve the quality, precision, accuracy and reliability of application of agrochemicals. This has led to increased use of electronic control systems and GPS-guided operations. Growth in these "precision agriculture" products and strategies has led to greater demand for "variable rate" technologies and the fluid handling means to alter spray liquid flow rates.

New sprayer models may have booms of <NUM> (approximately <NUM> ft) widths and allow application at speeds up to <NUM>/hr (<NUM> mph) or higher. Faster ground speeds and wider spray booms can lead to application errors that are significant yet unavoidable with existing spray technology. For example, if the sprayer is traversing the edge of a field while scribing about a <NUM> radius (actually, a very gentle turn), the outer nozzles are traveling <NUM>% faster than the inner nozzles. At a <NUM> radius, the difference in nozzle ground speeds is <NUM>%. With sharp turns, such as at the end of a pass, the inner nozzles will travel backwards, thereby retracing and overdosing previously sprayed areas, while the outer nozzles will significantly accelerate giving their associated land areas sparse coverage of chemical. Unless the flow rate from each nozzle is individually adjusted to compensate for these differences in travel speeds, application errors may occur.

Individual control of spray nozzles or nozzle assemblies is of growing importance in agrochemical application. As individual control increases, the need for individual flow monitoring will increase since feedback is often needed for closed loop control. Even with a linear control strategy, such as the binary control of multiple nozzles or pulse width modulation, confirmation of proper flow is important.

As the spray application industry adopts larger liquid storage tanks on mobile equipment, operators are likely to make fewer stops for refilling and cover greater land area between stops. Consequently, clogged nozzles or other problems on the boom are unlikely to be detected while significant land areas are being treated. For example, assuming a <NUM>/hr ground speed, a <NUM> boom width and <NUM>/ha (apprx. <NUM> gal/acre) application rate, a <NUM> (apprx. <NUM> gal) tank will cover 81ha (<NUM> acres) in apprx. <NUM> hour. A single nozzle in this example would treat apprx. <NUM> ha (<NUM> acres) per tank load and a single undetected nozzle malfunction would correspond to this <NUM> ha (<NUM> acres) area receiving an incorrect, or perhaps zero, dose of agrochemical.

Additionally, wider boom widths, travel speeds and vehicle sizes increasingly restrict an operator's view of the boom and the opportunities to view the boom while driving. On modern agricultural spray vehicles, <NUM> to <NUM>% of the spray boom may not be visible to the operator.

On some larger sprayers such as those typically used by custom applicators in the Midwest, Central Canada and the Plains, video cameras are sometimes mounted on the rear of the sprayer so that the operator can monitor, at least in theory, the spray boom out of his or her line of sight. However, at high travel speeds, the operator's attention is fully devoted to driving instead of monitoring the spray boom in the rear, either in the line of direct sight or shown on the video monitor. Due to poor overall visibility from the operator's station and the infrequency of stops and refillings, there is a need for individual nozzle monitoring to confirm that no clogging, pinched hoses, damaged nozzles or other problems may be present or developing on the spray boom.

A similar problem exists on shielded or shrouded sprayers sometimes used in the North American Plains and in urban and landscape applications. In farming areas in extreme southern and northern latitudes and in high value specialty crops, often grown in coastal areas, the agronomic time window for pesticide applications can be critically short and often occurs during windy periods. Shielded sprayers are often used in these conditions. Similarly, sprayers used in golf course, landscape and other urban conditions commonly use shrouds, curtains or shields to reduce spray drift and as a concession to public relations. However, the shields prevent the operator from visually inspecting the nozzle spray patterns to confirm proper operation. Improperly operating nozzles are not easily detected. Commercial systems for agricultural use often address this problem by routing individual liquid lines to each nozzle through a small rotameter (ball in tube) flow monitor that is mounted in the operator's line of sight. Such rotameters require cumbersome plumbing for each nozzle and require the operator visually monitor the bank of tubes.

One drawback of relying on visual inspection (either direct line of sight or video) or simple flow measurement (ball in tube) is that such methods do not assure proper nozzle operation. Nozzles can be partially clogged or have an obstruction in the flow path and appear to be operating correctly even if the flow rate is significantly affected. Conversely, the nozzle pattern and spray droplet size can be severely distorted by an obstruction or damage, yet the flow rate remains close to the original value.

Electronic spray rate control systems and application monitors typically use a single flowmeter and/or pressure transducer for feedback of the flow conditions on the entire spray boom. In systems with many nozzles, such as a <NUM>-<NUM> nozzle boom, failure of <NUM> or <NUM> nozzles would be unlikely to raise an alarm since the overall effect is only <NUM>% of the expected flow rate; the system would compensate by maintaining the correct overall flow to the entire boom. So, if one nozzle became completely clogged, the system would simply increase the spray pressure and force an additional <NUM>% flow through the remaining nozzles operating properly. Even with the electronic control or monitor system, the driver would likely remain unaware of the failure.

Additionally, when individual nozzle control is implemented, the need for individual nozzle monitoring increases. Pulse width modulation systems have electrical and mechanical components on each nozzle. Multiple nozzle manifolds have multiple tips and actuators at each boom location. The opportunity for failure is increased over that of a simple nozzle. These systems require not only flow monitoring but also monitoring of the control actuators used for flow or droplet size modulation. Moreover, individual nozzle control implies that individual nozzle feedback is required for closed loop operation.

Future systems may incorporate individual nozzle injection of multiple agrochemicals or adjuvants, individual control of droplet size spectra, droplet velocity or spray distribution. In each case, the need for monitoring and actuation on a single-nozzle or single manifold basis increases.

Thus, a need currently exists for a system and process for monitoring spray nozzle operation. Such a system and process is well suited for use in the agricultural field. It should be understood, however, that similar needs also exist in other fields. For example, on irrigation systems, there may be many small nozzles, often obscured from view or in areas that are difficult to access. Failure of a nozzle might not be detected until drought damage to a plant had occurred and symptoms were visible. Likewise, in industrial spray driers, malfunction of a nozzle might not be detected until significant amounts of product had been damaged. In spray humidification or cooling systems, nozzle failures might not be detected until excessive heating or drying had occurred. Specifically, a system that monitors nozzle operation may find wide applicability in any system, whether commercial, industrial or residential, that utilizes spray nozzles.

<CIT> discloses an electric solenoid valve, methods for operating and/or actuating the solenoid valve, valve system diagnostics, and applications. The valve may be designed to actuate in a manner so as to control liquid flow into and/or through a device, such as a spray nozzle.

<CIT> discloses a method of operating an injection valve comprising determining wear of a valve seat and maximum flow of a fluid injected into an injection valve for affecting a sturgeon effect; determining the coking of an injector nozzle of the injection valve using a partial model; and using an output of the partial model to correct the control of an actuator.

In one aspect, a method of detecting fluid flow through a nozzle coupled in fluid communication with a solenoid valve of an agrochemical fluid application system according to claim <NUM> is provided.

In another aspect, an assembly of a drive circuit and a solenoid valve coupled in fluid communication with a nozzle of an agrochemical application system to regulate flow of agrochemical towards the nozzle according to claim <NUM> is provided.

In yet another aspect, an agrochemical fluid application system according to claim <NUM> is provided.

These and other features, aspects and advantages of the present disclosure will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and, together with the description, serve to explain the principles of the disclosure.

Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.

Referring now to the Figures, <FIG> is a perspective view of one embodiment of a spray system, indicated generally at <NUM>, operatively connected to a work vehicle <NUM>. As shown, work vehicle <NUM> includes a cab <NUM> and a plurality of wheels <NUM>. Work vehicle <NUM> may in certain embodiments be an agricultural tractor having any suitable configuration. However, it should be appreciated that in other embodiments, any other suitable aero or ground means may be provided for moving spray system <NUM>. For example, in other embodiments, work vehicle <NUM> may not include a cab, and instead may have any suitable operator station. Further, in some embodiments, work vehicle <NUM> and/or spray system <NUM> may include a global positioning system (e.g., a GPS receiver) for automated control of work vehicle <NUM> and/or spray system <NUM>. In some embodiments, the global positioning system is used to monitor a travel speed of vehicle <NUM> and/or spray system <NUM>, and/or to monitor a position of work vehicle <NUM> and/or spray system <NUM>.

In the example embodiment, spray system <NUM> includes at least one boom wheel <NUM> for engaging a section of ground with a crop, produce, product or the like (generally, P), a tank or reservoir <NUM>, and a spray boom <NUM>. Spray boom <NUM> includes a plurality of nozzle assemblies <NUM> attached thereto and in fluid communication with tank <NUM>. Tank <NUM> holds a product S, such as a liquid, a mixture of liquid and powder, or other product. Product S may be a quantity of water or an agrochemical such as a fertilizer or a pesticide, and may be sprayed from nozzle assemblies <NUM> onto, for example, a crop or produce or ground P itself, as shown in <FIG> and described in greater detail below. It should be appreciated, however, that in other embodiments, system <NUM> may have any other suitable configuration. For example, in other embodiments, system <NUM> may not include boom wheel <NUM> or may alternatively include any suitable number of boom wheels <NUM>. Further, while work vehicle <NUM> is depicted as towing spray system <NUM> in the example embodiment, it should be appreciated that, in other embodiments, work vehicle <NUM> may transport spray system <NUM> in any suitable manner that enables spray system <NUM> to function as described herein.

The quantity of product S held in tank <NUM> generally flows through a conduit to nozzle assemblies <NUM>. More specifically, in the embodiment illustrated in <FIG>, product S flows from tank <NUM>, through a pipe <NUM> to a boom pipe <NUM>, and from boom pipe <NUM> to nozzle assemblies <NUM>. In certain embodiments, nozzle assemblies <NUM> comprise direct acting solenoid valve equipped nozzles (see, e.g., <FIG>) and system <NUM> may include a pump, transducers to measure fluid pressure and fluid flow, sectional regulating valves, and a pressure and/or flow controller (not shown in <FIG>). If included, the pump may be positioned downstream from tank <NUM>, upstream from boom pipe <NUM> and nozzle assemblies <NUM>, and in operative communication with the controller. The pump may be a pulse width modulation controlled pump configured to provide a desired amount of product S flow through system <NUM>. The pressure or flow controller may be configured to vary certain operating parameters of the pump, such as the pump's pulse frequency and/or duty cycle, to obtain a desired product flow rate through system <NUM>.

Referring still to <FIG>, product S flows through nozzle assemblies <NUM> and may be applied to ground P in various ways. For example, product S may flow from nozzle assemblies <NUM> in a pulsed pattern. It should be appreciated that terms "pipe" and "conduit," as used herein, may mean any type of conduit or tube made of any suitable material such as metal or plastic, and moreover that any other suitable ground application devices can be added to provide varying effects of placement of product S on top or below a soil surface of ground P, such as via pipes, knives, coulters, and the like.

<FIG> is a perspective view of one embodiment of a nozzle assembly <NUM> suitable for use with spray system <NUM> of <FIG>. As shown in <FIG>, nozzle assembly <NUM> generally includes a valve assembly <NUM>, a nozzle body <NUM> configured to receive product S flowing through boom pipe <NUM> and a spray nozzle <NUM> mounted to and/or formed integrally with nozzle body <NUM> for expelling product S from nozzle assembly <NUM> onto crops, product and/or ground P.

In some embodiments, valve assembly <NUM> is a solenoid valve (see, e.g., <FIG> and <FIG>). Moreover, in some embodiments, valve assembly <NUM> may be configured to be mounted to and/or integrated with a portion of spray nozzle <NUM>. In some embodiments, for example, valve assembly <NUM> may be mounted to the exterior of nozzle body <NUM>, such as by being secured to nozzle body <NUM> through the nozzle's check valve port. Alternatively, valve assembly <NUM> may be integrated within a portion of nozzle body <NUM>.

<FIG> is a simplified, cross-sectional view of one embodiment of an electric solenoid valve <NUM> suitable for use in nozzle assembly <NUM> shown in <FIG>. In general, valve <NUM> includes an inlet <NUM> and an outlet <NUM> for receiving and expelling fluid <NUM> from valve <NUM>. Valve <NUM> also includes a solenoid coil <NUM> (outlined by the dashed lines) located on and/or around a guide <NUM>. For instance, in one embodiment, solenoid coil <NUM> is wrapped around guide <NUM>. Additionally, an actuator or poppet <NUM> is movably disposed within guide <NUM>. In particular, poppet <NUM> may be configured to be linearly displaced within guide <NUM> relative to inlet <NUM> and/or outlet <NUM> of valve <NUM>. Moreover, as shown, valve <NUM> includes a spring <NUM> coupled between guide <NUM> and poppet <NUM> for applying a force against poppet <NUM> in the direction of outlet <NUM>. It should be appreciated that valve <NUM> may also include a valve body or other outer covering (not shown) disposed around coil <NUM>.

As shown in the illustrated embodiment, valve <NUM> is configured as an in-line valve. Thus, fluid <NUM> may enter and exit valve <NUM> through inlet <NUM> and outlet <NUM>, respectively, along a common axis <NUM>. In other words, the inlet <NUM> and outlet <NUM> may generally be aligned along axis <NUM>. Additionally, as shown in <FIG>, in one embodiment, inlet <NUM> and outlet <NUM> may be concentrically aligned with both one another and the positioning of poppet <NUM> within guide <NUM>. As such, poppet <NUM> may be configured to be linearly displaced within guide <NUM> along axis <NUM> such that fluid <NUM> may generally be directed through valve <NUM> along axis <NUM> as the movement of poppet <NUM>.

In addition, solenoid coil <NUM> may be coupled to a controller <NUM> configured to regulate or control the current provided to coil <NUM>. Controller <NUM> may be enclosed within valve assembly <NUM>, may be enclosed within nozzle assembly <NUM>, as shown in <FIG>, or may exist some distance away from nozzle assembly <NUM>. Controller <NUM> may generally comprise any suitable computer and/or other processing unit, including any suitable combination of computers, processing units and/or the like that may be communicatively coupled to one another (e.g., controller <NUM> may form all or part of a controller network). Thus, controller <NUM> may include one or more processor(s) and associated memory device(s) configured to perform a variety of computer-implemented functions (e.g., performing the methods, steps, calculations and/or the like disclosed herein). As used herein, the term "processor" refers not only to integrated circuits referred to in the art as being included in a computer, but also refers to a controller, a microcontroller, a microcomputer, a programmable logic controller (PLC), an application specific integrated circuit, and other programmable circuits. Additionally, the memory device(s) of controller <NUM> may generally comprise memory element(s) including, but not limited to, computer readable medium (e.g., random access memory (RAM)), computer readable non-volatile medium (e.g., a flash memory), a floppy disk, a compact disc-read only memory (CD-ROM), a magneto-optical disk (MOD), a digital versatile disc (DVD) and/or other suitable memory elements. Such memory device(s) may generally be configured to store suitable computer-readable instructions that, when implemented by the processor(s), configure controller <NUM> to perform various functions including, but not limited to, controlling the current supplied to solenoid coil <NUM>, monitoring inlet and/or outlet pressures of the disclosed valve(s), monitoring poppet operation of the disclosed valves, receiving operator inputs, performing the calculations, algorithms and/or methods described herein and various other suitable computer-implemented functions.

Coil <NUM> may be configured to receive a controlled electric current or electric signal from controller <NUM> such that poppet <NUM> may move within guide <NUM> relative to inlet <NUM> and/or outlet <NUM>. For example, in one embodiment, controller <NUM> includes a square wave generator, a coil drive circuit as shown in <FIG>, or any other suitable device that is configured to apply a regulated current to coil <NUM>, thereby creating a magnetic field which biases (by attraction or repulsion) poppet <NUM> toward inlet <NUM>. As a result, poppet <NUM> may be moved to a proper throttling position for controlling the pressure drop across valve <NUM>. Additionally, the attraction between coil <NUM> and poppet <NUM> may also allow poppet <NUM> to be pulsated or continuously cyclically repositioned, thereby providing for control of the average flow rate through valve <NUM>.

In several embodiments, a modulated square wave may drive valve <NUM> to control the pressure and flow rate. The duty cycle of a high-frequency modulation (e.g., at a frequency greater than about <NUM>) may be used to regulate coil current and partially open valve <NUM> by moving poppet <NUM> to a particular throttling position, thereby providing a means for manipulating the outlet pressure of fluid <NUM>. Additionally, the low-frequency pulse duty cycle (e.g., at a frequency of less than <NUM>) may be used to meter the average flow rate by enabling/disabling the temporally-averaged flow rate that results from the outlet pressure.

In certain embodiments, the poppet position may be regulated by the forces acting on poppet <NUM>, with a steady throttling position resulting from equilibrium of the forces. For example, in the illustrated embodiment, forces from spring <NUM>, fluid <NUM> and coil <NUM> may act on poppet <NUM> simultaneously. Specifically, the forces from spring <NUM> and fluid <NUM>, tend to bias poppet <NUM> in the direction of outlet <NUM> while the force from coil <NUM> tends to bias poppet <NUM> in the direction of inlet <NUM>.

Thus, when valve <NUM> is unpowered (i.e., when a voltage is not applied across coil <NUM>), spring <NUM> may force poppet <NUM> towards outlet <NUM> such that the increased system pressure has a tendency to force valve <NUM> into a sealed or closed position. In such an embodiment, poppet <NUM> may include a rubber disk or any other suitable sealing member <NUM> configured to press against an outlet seat <NUM> of outlet <NUM> to create a leak-free seal on valve <NUM> when valve <NUM> is in the closed position. Additionally, when valve <NUM> is powered (i.e., when a voltage is applied to coil <NUM>), poppet <NUM> may be attracted by coil <NUM> toward inlet <NUM> such that poppet <NUM> is moved to the throttling position. Specifically, the current supplied to coil <NUM> may be controlled such that the force acting on poppet <NUM> by coil <NUM> is sufficient to position poppet <NUM> a predetermined distance <NUM> from an inlet seat <NUM> of inlet <NUM>, thereby allowing the pressure across valve <NUM> to be throttled.

The particular distance <NUM> from inlet seat <NUM> (also referred to herein as the "poppet displacement") at which poppet <NUM> is positioned may generally vary depending on the desired outlet pressure for valve <NUM>. However, given the configuration of the disclosed valve <NUM>, distance <NUM> may always be less than total stroke of poppet <NUM> (defined as the summation of distance <NUM> and a distance <NUM> between poppet <NUM> and outlet seat <NUM>). In several embodiments, distance <NUM> may be less than <NUM>% of the total stroke of poppet <NUM>, such as less than <NUM>% of the total stroke of poppet <NUM> or less than <NUM>% of the total stroke of poppet <NUM>.

In several embodiments, when valve <NUM> is being pulsed, the movement of poppet <NUM> may be cycled between the throttling position and a sealed position, wherein poppet <NUM> is sealed against inlet <NUM>. Thus, as shown in <FIG>, poppet <NUM> may also include a rubber disk or other suitable sealing member <NUM> that is configured to be pressed against inlet seat <NUM> of inlet <NUM> so as to create a leak-free seal when valve <NUM> is in the sealed position. In such an embodiment, in order to transition valve <NUM> from the closed position (wherein poppet <NUM> is sealed against outlet <NUM>) to the sealed position (wherein the poppet <NUM> is sealed against inlet <NUM>), the solenoid may be initially turned on with a <NUM>% high frequency duty cycle so as to move poppet <NUM> from outlet <NUM> to inlet <NUM> as quickly as possible. Subsequently, the current supplied to coil <NUM> may be controlled such that poppet <NUM> may be cyclically pulsed between the sealed position and the throttling position. However, in alternative embodiments, valve <NUM> may be configured to be pulsed between the closed position (wherein poppet <NUM> is sealed against outlet <NUM>) and the throttling position.

The sizes of inlet <NUM> and outlet <NUM> (e.g., diameter <NUM> and diameter <NUM>, respectively), as well as the geometry and/or configuration of poppet <NUM> and guide <NUM>, may be chosen such that the force acting on poppet <NUM> from coil <NUM> may overcome the fluid forces and spring forces for every throttling position within the total stroke of valve <NUM> when the coil is fully powered. Similarly, in one embodiment, spring <NUM> may be sized such that the spring force corresponds to the minimal amount of force required to maintain a drip-free valve <NUM> when valve <NUM> is unpowered.

In several embodiments, poppet <NUM> and/or guide <NUM> may include a tapered portion at and/or adjacent to inlet <NUM>. Specifically, as shown in <FIG>, both poppet <NUM> and guide <NUM> include a tapered portion defining a taper angle <NUM> at and/or adjacent to inlet <NUM>. In several embodiments, taper angle(s) <NUM> may range from about <NUM> degrees to about <NUM> degrees, such as from about <NUM> degrees to about <NUM> degrees or from about <NUM> to about <NUM> degrees and all other subranges there between. However it is foreseeable that, in alternative embodiments, taper angle(s) <NUM> may be less than about <NUM> degrees or greater than about <NUM> degrees.

As indicated above, coil <NUM> may be driven with a complex pulsed voltage waveform. A "pulse" may correspond to a duration (e.g., a <NUM> millisecond cycle) in which a low frequency duty cycle value sets the amount of on/off time. The "on" time may correspond to a "coil discharging (or charging) period" in which the drive voltage is turned off (or on) continuously and a "modulated period" in which the voltage is turned on and off at a high frequency (e.g., at a frequency of greater than <NUM>). The duration of the coil discharging (or charging) period may be determined by the amount of time for the coil current to reach the desired value. The coil current may be continuously measured and compared to a threshold in order to trigger switching of the drive voltage to a modulated signal.

According to the present invention the movement of poppet <NUM> is sensed by a poppet measurement device <NUM>. For example, in certain embodiments, measurement device <NUM> may be an accelerometer, a hall-effect sensor, a coil current sensor, or other suitable device capable of sensing when a poppet moves from an open position to a closed position. The measurement device <NUM> may be communicatively coupled to controller <NUM>, and may be disposed within valve assembly <NUM>, within nozzle assembly <NUM>, as shown in <FIG>, or some distance away from nozzle assembly <NUM>.

Referring now to <FIG>, a simplified, cross-sectional view of another embodiment of an electric solenoid valve <NUM> suitable for use in nozzle assembly <NUM> shown in <FIG> is illustrated. In general, valve <NUM> may be configured similarly to valve <NUM> described above with reference to <FIG> and, thus, may include many or all of the same components. For example, valve <NUM> may include an inlet <NUM> and an outlet <NUM> for receiving and expelling a fluid <NUM> from valve <NUM>. Additionally, valve <NUM> may include a solenoid coil <NUM> (outlined by dashed lines) located on and/or around a guide <NUM> and a poppet <NUM> movably disposed within guide <NUM>. Solenoid coil <NUM> may be configured to receive a controlled electric current or electric signal from a controller <NUM> such that poppet <NUM> may be moved within guide <NUM> relative to outlet <NUM>. Controller <NUM> may have the same configuration as controller <NUM> described above with reference to <FIG>, and may be enclosed within the valve assembly <NUM>, may be enclosed within the nozzle assembly <NUM> as shown in <FIG>, or may exist some distance away from nozzle assembly <NUM>. Valve <NUM> may also include a spring <NUM> coupled between guide <NUM> and poppet <NUM> for applying a force against the poppet <NUM> in the direction of outlet <NUM>. It should be appreciated that valve <NUM> may also include a valve body or other outer covering (not shown) disposed around solenoid coil <NUM>.

In some embodiments of the present invention, valve <NUM> includes a poppet measurement device <NUM> capable of sensing when a poppet moves from an open position to a closed position. For example, in certain embodiments, measurement device <NUM> may be an accelerometer, a hall-effect sensor, a coil current sensor, or other suitable device capable of sensing when a poppet moves from an open position to a closed position. The measurement device <NUM> may be communicatively coupled to controller <NUM>, and may be disposed within valve assembly <NUM>, within nozzle assembly <NUM>, as shown in <FIG>, or some distance away from nozzle assembly <NUM>.

In contrast to the in-line valve <NUM> described above, valve <NUM>, illustrated in <FIG>, is configured as a counter flow valve. Thus, fluid <NUM> may be configured to enter and exit valve <NUM> along different axes. For example, as shown, outlet <NUM> may generally be aligned with the axis of movement of poppet <NUM> and inlet <NUM> may be offset from such axis, such as by being disposed above outlet <NUM>.

Additionally, in one embodiment, poppet <NUM> may be configured to include a projection <NUM> (e.g., a section of poppet <NUM> being reduced in size) extending outwardly in the direction of outlet <NUM>. For example, as shown in <FIG>, projection <NUM> may extend outwardly from the portion of poppet <NUM> configured to be sealed against an outlet seat <NUM> of outlet <NUM> (e.g., a rubber disk or any other suitable sealing member <NUM>).

As described in <CIT>, projection <NUM> may be configured to be received within a portion of outlet <NUM> such that a partial opening of valve <NUM> generates a first constant flow coefficient, and fully opening valve <NUM> generates a second constant flow coefficient greater than the first constant flow coefficient. In alternative embodiments, the illustrated valve <NUM> may not include projection <NUM> shown in <FIG>.

Similar to valve <NUM> described above, the partially open state may be achieved by controlling the forces acting on poppet <NUM>. For example, a regulated amount of voltage may be applied to solenoid coil <NUM> (generating a regulated amount of coil current through solenoid coil <NUM>) such that the forces acting on poppet <NUM> by solenoid coil <NUM>, spring <NUM> and fluid <NUM> are in an equilibrium state when poppet <NUM> is located at the desired throttling position. In such an embodiment, a resulting distance <NUM> between sealing member <NUM> and outlet seat <NUM> may be chosen to position the volume of the outlet occupied by projection <NUM> to throttle the pressure across valve <NUM>.

Generally, the disclosed solenoid valves <NUM> and <NUM> may be utilized to control the instantaneous pressure drop across and the cyclic duration of flow through any suitable device. However, in several embodiments of the present disclosure, the solenoid valves <NUM> and <NUM> may be used to control the instantaneous pressure drop across and the cyclic duration of flow through an agricultural spray nozzle. In such embodiments, the disclosed solenoid valves <NUM> and <NUM> may be configured as part of a nozzle assembly for use with various agricultural spraying systems.

<FIG> is a schematic diagram of one embodiment of a drive circuit <NUM> for controlling valves <NUM> and <NUM> shown in <FIG> and <FIG>, or may form all or part of the disclosed controllers <NUM> or <NUM>. Drive circuit <NUM> may further include or interface with a poppet measurement device, such as poppet measurement devices <NUM> and <NUM>, shown in <FIG> and <FIG>, respectively. In general, circuit <NUM> may be configured to generate a waveform for a solenoid valve and may also be configured to measure the solenoid coil current. In one embodiment, circuit <NUM> includes a field-effect transistor (FET) <NUM> controlled by a control signal or waveform <NUM> to connect/disconnect a supply voltage <NUM> to a solenoid coil <NUM>, thereby energizing or de-energizing solenoid coil <NUM>. Solenoid coil <NUM> may be, for example, solenoid coil <NUM> or solenoid coil <NUM> of valves <NUM> and <NUM> shown in <FIG> and <FIG>. In addition, drive circuit <NUM> includes a current sense resistor <NUM> configured to generate a sense voltage <NUM> directly indicating the current through current sense resistor <NUM> and solenoid coil <NUM>.

While solenoid coil <NUM> is energized to open the solenoid valve, a fly-back switch <NUM> enables a fly-back diode <NUM> to allow current in solenoid coil <NUM> to remain nearly constant during a high frequency modulation of control signal <NUM>. Fly-back switch <NUM> may disable fly-back diode <NUM> at the beginning or end of a low-frequency pulse to force a more rapid coil current change. Fly-back switch <NUM> may be implemented as, for example, a field-effect transistor (FET), a silicon controlled rectifier (SCR), relay, or any other suitable switch.

FET <NUM> disconnects supply voltage <NUM> to de-energize solenoid coil <NUM> and to close the solenoid valve. During closing, current through solenoid coil <NUM> is dissipated to allow a poppet of the solenoid valve to translate toward the closed position. Fly-back switch <NUM> disables fly-back diode <NUM> by opening the fly-back circuit when FET <NUM> disconnects supply voltage <NUM>. Disabling fly-back diode <NUM> facilitates dissipating the current in solenoid coil <NUM> more quickly through a charge build up and resulting large potential across coil <NUM>. In certain embodiments, FET <NUM> may be protected from the voltage induced by coil <NUM> with a transient voltage suppressor diode <NUM> having a clamping voltage suitable to protect FET <NUM>.

As the current through solenoid coil <NUM> dissipates, the force exerted by solenoid coil <NUM> on the poppet decreases until the sum of forces acting on the poppet (e.g., spring forces, pressure differential forces, and magnetic force) cause the poppet to translate within solenoid coil <NUM> toward the closed position. As the poppet translates, an electromagnetic flux is generated and the poppet induces a coil current within solenoid coil <NUM>. Immediately before or as the poppet begins to translate to the closed position, fly-back diode <NUM> can be re-enabled by closing fly-back switch <NUM>, such that current may flow freely through the fly-back circuit and current sense resistor <NUM> detects the induced current, which manifests as sense voltage <NUM>. In this manner, current sense resistor <NUM> may serve as poppet measurement device <NUM> or <NUM>.

In certain embodiments, drive circuit <NUM> includes a processor <NUM>. Processor <NUM> receives current sense voltage <NUM> and determines a peak coil current after solenoid coil <NUM> has been de-energized. The time between de-energizing solenoid coil <NUM> and the peak coil current represents the closing time delay for the solenoid valve. The time required for the solenoid valve to close is related to a fluid flow through the solenoid valve. Generally, the greater the fluid flow through the solenoid valve, the greater the pressure drop that develops across the poppet; and the less time required for the poppet to translate to the closed position. This relationship is governed by the following equation: <MAT> where, Q is fluid flow through the solenoid valve, CV<NUM> is a flow coefficient of the valve metering orifice, Δp<NUM> is a pressure drop across the valve metering orifice, and SG is the specific gravity of the fluid. Given the time at which the peak coil current occurs during closing of the solenoid valve and the relationship between peak coil current time and fluid flow, a fluid flow value representing fluid flow through the nozzle assembly may be determined.

In certain embodiments, processor <NUM> uses the time at which the peak coil current occurs to estimate flow through the solenoid valve based on experimental or statistical data gathered for close times for the solenoid valve. In one embodiment, for example, the flow is estimated by precomputed values in a look-up table. Additionally or alternatively, the flow may be computed using a "fit line" characterized by the experimental or statistical data, such as the data shown and described herein with reference to <FIG> and <FIG>.

In certain embodiments, processor <NUM> is further configured to compare the determined nozzle flow to a target nozzle flow for the nozzle assembly. For example, for a nozzle assembly having a given nozzle size and measured upstream pressure yielding a target nozzle flow of <NUM> litres (<NUM> gallons) per minute, the determined nozzle flow is compared to the <NUM> litres (<NUM> gallons) per minute. If the determined nozzle flow is less than <NUM> litres (<NUM> gallons) per minute, the nozzle assembly may have a clog in the nozzle spray tip or elsewhere in the nozzle assembly that is impeding nozzle flow. Conversely, if the determined nozzle flow is greater than <NUM> litres (<NUM> gallons) per minute, the nozzle assembly may be damaged and is not properly regulating flow through the nozzle assembly and nozzle spray tip. This may occur, for example, if the nozzle assembly strikes the ground or some other object and damages or shears off the nozzle spray tip.

In certain embodiments, processor <NUM> is further configured to generate control signal <NUM> to control FET <NUM>. In certain embodiments, processor <NUM> is further configured to generate a second control signal <NUM> for controlling fly-back switch <NUM>. Processor <NUM>, for example, may be configured to close fly-back switch <NUM> to enable fly-back diode <NUM> for a period of time after solenoid coil <NUM> is de-energized. In such an embodiment, current would dissipate from solenoid coil <NUM> more slowly if fly-back switch <NUM> were closed and fly-back diode <NUM> were enabled. Opening fly-back switch <NUM> permits the poppet to translate sooner, thereby closing the valve more quickly. In one embodiment, fly-back switch <NUM> is open for a period of <NUM> milliseconds, which is sufficient for current to dissipate in solenoid coil <NUM> and to allow the poppet to begin translating toward the closed position. The period of time may vary per embodiment, depending on the particular solenoid valve, nozzle, spray system, or fluid, for example. Processor <NUM> is further configured to generate second control signal <NUM> to close fly-back switch <NUM>.

<FIG> is a flow diagram of one embodiment of a method <NUM> of detecting nozzle flow in a spray system, such as spray system <NUM> of <FIG>. Method <NUM> begins at a start step <NUM>. At a coil de-energizing step <NUM>, a voltage across a solenoid coil, such as solenoid coils <NUM> and <NUM> of <FIG> and <FIG>, is turned off. Referring to <FIG> and <FIG>, solenoid valve <NUM> is in fluid communication with a nozzle, such as nozzle <NUM> of <FIG>. The solenoid valve regulates flow of a fluid through the valve and toward the nozzle.

As the solenoid coil current dissipates, poppet <NUM> translates toward valve outlet <NUM> to a closed position. In step <NUM>, poppet measurement device <NUM> senses the transition of poppet <NUM> to the closed position. Controller <NUM> detects the measurement device output at a step <NUM>, and determines a time delay between de-energizing the solenoid coil and the measured poppet closure. Controller <NUM> then determines the nozzle flow based on the time delay between de-energizing the solenoid coil and the measured poppet closure at a nozzle flow determination step <NUM>. In some embodiments, the time delay between de-energizing the solenoid coil and the measured poppet closure is determined based on a measured coil current, as described below with reference to <FIG>. The method ends at an end step <NUM>.

<FIG> is a flow diagram of another embodiment of a method <NUM> of detecting nozzle flow in a spray system, such as spray system <NUM> of <FIG>. Method <NUM> begins at a start step <NUM>. Referring to <FIG>, <FIG>, and <FIG>, at a de-energizing step <NUM>, solenoid coil <NUM> is de-energized by opening FET <NUM>. Fly-back diode <NUM> is disabled at a fly-back disabling step <NUM> by opening fly-back switch <NUM>. Opening FET <NUM> and fly-back switch <NUM> facilitates dissipation of coil current at a dissipation step <NUM> through a charge build up across coil <NUM>.

After a period of time, fly-back diode <NUM> is enabled at a fly-back enabling step <NUM> for the purpose of measuring coil current through current sense resistor <NUM>. A coil current induced by the poppet translating through solenoid coil <NUM> toward the closed position is detected at a detection step <NUM>. A controller, such as controllers <NUM> and <NUM> of <FIG> and <FIG>, receives the coil current measurement and determines, at a peak detection step <NUM>, a time of a peak coil current after solenoid coil <NUM> is de-energized. The controller then uses the time delay of the valve closure to determine nozzle flow at a determination step <NUM>.

<FIG> is a plot <NUM> showing times of peak coil current for variously sized nozzle assemblies, such as nozzle assembly <NUM> shown in <FIG>. Plot <NUM> includes three different spray nozzles <NUM>: a nozzle assembly without a spray tip attached, a nozzle assembly with a small nozzle spray tip that permits a low nozzle flow relative to the nozzle assembly without a spray tip, and a nozzle assembly with a large nozzle spray tip that permits a large nozzle flow relative to the small nozzle spray tip, but still more restricted nozzle flow relative to the nozzle assembly without a nozzle spray tip.

For each of the nozzle spray tips, closing of the solenoid valve for the nozzle assembly was initiated at a time of <NUM> milliseconds by the opening of the drive switch. The opening of the solenoid valve for the nozzle assembly was some time before <NUM> milliseconds, e.g., at a time of <NUM> milliseconds. When solenoid valve closure is initiated, the solenoid coil is de-energized, which is illustrated by each of the coil current plots for the three different nozzle assemblies falling initially toward zero amps. After approximately <NUM> milliseconds, each of the coil current plots begin to rise toward respective peaks, which corresponds with movement of the solenoid valve poppet toward the closed position. The precise time of the peak coil currents correlates to a fluid flow value.

The nozzle assembly without a nozzle spray tip permits the largest nozzle flow. The nozzle flow corresponds to an earlier valve closure indicated by a peak coil current at a time <NUM> that occurs at slightly less than <NUM> milliseconds, or slightly less than <NUM> milliseconds after the drive switch opened and initiated the de-energizing of the solenoid coil.

The nozzle assembly having the large nozzle spray tip permits less nozzle flow than the nozzle assembly without any nozzle spray tip. The nozzle flow corresponds to a valve closure indicated by a peak coil current at a time <NUM> that occurs at slightly less than <NUM> milliseconds.

The nozzle assembly having the small nozzle spray tip permits the least nozzle flow among the three. The nozzle flow corresponds to a valve closure indicated by a peak coil current at a time <NUM> that occurs at slightly less than <NUM> milliseconds.

<FIG> is a plot <NUM> showing nozzle fluid flow in gallons per minute versus time of peak coil current in milliseconds. The data points on plot <NUM> represent various nozzle assemblies having variously sized nozzle spray tips. The solenoid valve for the nozzle assembly was closed at a time of <NUM> milliseconds. The solenoid valve for the nozzle assembly was opened at a time earlier than <NUM> milliseconds, e.g., at a time of <NUM> milliseconds. Each data point on plot <NUM> illustrates the relationship between nozzle flow and valve closure time as indicated by the time at which the peak coil current induced by the poppet translating to the closed position occurs.

In certain embodiments, nozzle flow is determined by the controller at determination step <NUM> based on experimental data for solenoid valve closing times, such as the data shown in <FIG> and <FIG>. In alternative embodiments, nozzle flow is determined according to a mathematical relationship characterized by Eq. <NUM> above. The method ends at an end step <NUM>.

Although systems and methods are described above with reference to an agricultural spray system, embodiments of the present disclosure are suitable for use with agricultural fluid application systems other than spray systems. In some embodiments, for example, the systems and methods of the present disclosure are implemented in a fluid application system that injects fluid, such as fertilizer, into the soil through dispensing tubes, rather than spray nozzles.

<FIG> is a perspective view of one embodiment of a fluid application system <NUM>. Fluid application system <NUM> includes a volatile liquid fertilizer application system for application of fertilizers such as, for example, anhydrous ammonia. Fluid application system <NUM> includes a motorized vehicle <NUM>, a fluid storage tank <NUM>, and a distribution manifold <NUM>. Motorized vehicle <NUM> may be any machine that enables fluid application system <NUM> to function as described herein. In suitable embodiments, one or more components of fluid application system <NUM> may be incorporated into motorized vehicle <NUM> without departing from some aspects of this disclosure. In the exemplary embodiment, fluid storage tank <NUM> and distribution manifold <NUM> are disposed on a wheeled chassis <NUM> towed behind motorized vehicle <NUM>.

During operation, fluid storage tank <NUM> may contain any type of fluid for distribution by fluid application system <NUM>. For example, fluid storage tank <NUM> may store a volatile fluid intended to be applied to fields for agricultural purposes. A common fluid used for agricultural purposes is anhydrous ammonia, which is applied to fields primarily as a fertilizer to increase the nutrient level of soils. The anhydrous ammonia includes at least some gaseous substance and, therefore, is maintained at a carefully controlled pressure to control the gaseous properties. In the exemplary embodiment, fluid storage tank <NUM> is configured to store and maintain the fluid at a desired pressure as fluid flows out of the fluid storage tank. Fluid application system <NUM> includes at least one pump <NUM> connected to fluid storage tank <NUM> to facilitate maintaining the fluid in the fluid storage tank at the desired pressure.

In the exemplary embodiment, fluid storage tank <NUM> is fluidly connected to a distribution manifold <NUM> by a fluid line <NUM>. Disposed between distribution manifold <NUM> and fluid storage tank <NUM> is a valve <NUM> and quick connect <NUM>. In suitable embodiments, quick connect <NUM> and valve <NUM> may be coupled to any portions of fluid application system <NUM>. For example, in some suitable embodiments, any of quick connect <NUM> and valve <NUM> may be omitted without departing from some aspects of this disclosure. In the exemplary embodiment, quick connect <NUM> facilitates fluid storage tank <NUM> being connected to and removed from fluid line <NUM>. Valve <NUM> controls fluid flow through fluid line <NUM>. For example, valve <NUM> is positionable between a closed position where fluid is inhibited from flowing through fluid line <NUM> and an open position where fluid is allowed to flow through fluid line <NUM>. In certain embodiments, valve <NUM> may be any valve that enables fluid application system <NUM> to function as described herein.

The fluid is directed from fluid line <NUM> through valve <NUM> and into distribution manifold <NUM>. As shown in <FIG> and <FIG>, distribution manifold <NUM> includes a plurality of supply lines <NUM> each connected to valve assemblies <NUM>. Each valve assembly <NUM> regulates flow of the fluid through a nozzle body <NUM> and into a dispensing tube <NUM> for injecting the fluid into a soil. Distribution manifold <NUM> distributes the fluid to valve assemblies <NUM> and dispensing tubes <NUM> for emitting the fluid from fluid application system <NUM>.

Each valve assembly <NUM> is controlled by a controller, such as controllers <NUM> or <NUM> described above with reference to <FIG> and <FIG>, respectively. The controller may be configured to determine or estimate fluid flow through dispensing tubes <NUM> based on a valve closure time using the methods described above with reference to <FIG> and <FIG>. More specifically, the controller may be configured to determine or estimate fluid flow through dispensing tubes <NUM> based on a time delay between de-energizing a solenoid coil within valve assembly <NUM> and a measured poppet closure time, as described in more detail herein with reference to <FIG> and <FIG>.

In suitable embodiments, fluid application system <NUM> may include any number of dispensing tubes <NUM>. In some embodiments, as the fluid is emitted from dispensing tubes <NUM>, vehicle <NUM> moves fluid application system <NUM> along a desired path for fluid application, such as rows <NUM> of a field <NUM>. In the exemplary embodiment, dispensing tubes <NUM> are connected to or positioned behind a soil preparation mechanism <NUM>, such as a knife or plow, that contacts the soil as dispensing tubes <NUM> dispense fluid onto the soil, as best seen in <FIG>. Soil preparation mechanisms <NUM> are connected to a boom <NUM>, which is connected to and pulled behind vehicle <NUM>.

The systems and methods described herein provide fluid flow measurements through a solenoid valve. For example, in spray systems within which the systems and methods may be embodied or carried out, fluid flow may be determined and presented to the operator. Additionally, determined fluid flow may be compared to a target fluid flow for the spray system or further compared to determined fluid flows from adjacent nozzle assemblies. The comparison of measured fluid flow to a target fluid flow facilitates determining whether a particular nozzle assembly is functioning properly. The determined fluid flow measurements facilitate determining, during operation, the state of the various nozzle assemblies on the spray system that are otherwise difficult to ascertain during operation. The systems described herein may include diagnostic capabilities derived from the determined fluid flow through the solenoid valve. For example, the system may be able to determine if valve <NUM> contains debris lodging it open or closed, if spray nozzle <NUM> is partially or fully clogged, if spray nozzle <NUM> has fallen off of nozzle body <NUM>, or if a spray boom section is failing to receive flow due to a conduit problem or section valve malfunction.

Claim 1:
A method (<NUM>, <NUM>) of detecting fluid flow through a solenoid valve (<NUM>, <NUM>, <NUM>) of an agrochemical fluid application system (<NUM>), the solenoid valve being coupled in fluid communication with a nozzle (<NUM>) of the agrochemical fluid application system and including a solenoid coil (<NUM>, <NUM>, <NUM>) and a poppet (<NUM>, <NUM>), the method (<NUM>, <NUM>) comprising:
dispensing (<NUM>) agrochemical fluid through the solenoid valve (<NUM>, <NUM>, <NUM>);
de-energizing (<NUM>) the solenoid coil (<NUM>, <NUM>, <NUM>) to close the solenoid valve (<NUM>, <NUM>, <NUM>) and control a fluid flow through the solenoid valve (<NUM>, <NUM>, <NUM>);
determining (<NUM>) a closing time of the solenoid valve (<NUM>, <NUM>, <NUM>) based on a signal from a poppet measuring device (<NUM>, <NUM>); and
determining (<NUM>) a fluid flow value based on a time delay between the de-energizing the solenoid coil (<NUM>, <NUM>, <NUM>) and the closing time, wherein a determined fluid flow value below a target flow value is indicative of the nozzle being clogged.