Patent Application
20240109085
The present disclosure is directed generally to a control system for a liquid pump sprayer. The control system improves upon such conventional sprayers by providing a user-selectable series of defined spray application pressures, flow rates, and patterns that are that are accurately sustained over the duration of a spray application session.
Portable liquid-pump sprayers are widely employed both professionally and around the home to apply such chemicals as herbicides, insecticides, fertilizers, detergents, disinfectants, and water. These sprayers may be hand-carried, worn as a backpack, or wheeled on a cart for transport to the application site.
The earliest and most traditional liquid-pump sprayers are manually pumped so to produce the pressure necessary to spray; more recent sprayers employ battery-powered electric motor technology to drive the pump. As will be shown, both types of sprayers lack the control to accurately establish and sustain a specified pump outlet pressure for the duration of a spraying session.
Especially for professionals, the control of a specified pump outlet pressure, with the resulting flow rate and spray pattern for a given spray outlet nozzle, is important. This control of outlet pump pressure is needed for efficient, accurate, and economical application of the sprayed liquid product.
The operational effectiveness of pressure control for both types of conventional sprayers are discussed herein as relevant background to the disclosed control system.
Shown as a backpack sprayer in
Note here that spray nozzle 9 may be of adjustable form, or may be changed out via a selection of various nozzle formats, in order to produce the pattern necessary for the intended spray application.
A well-understood disadvantage of a traditional manual pump system is that in order to sustain the pressure needed to produce the desired outlet flow and spray pattern, the user must pump repeatedly and regularly over the course of the spray session. As an attempt to improve the control of pump outlet pressure for pumping efficiency and spraying effectiveness, a pressure accumulator is widely employed.
The schematic of
In preparation for spraying, shutoff valve 11 is closed and pump handle 1 is manually reciprocated so as to prime the pump and pressurize the liquid to be sprayed. The pressure accumulator is designed to contain a prescribed volume of air and liquid such that, as the pressurized liquid from the pump now flows into the accumulator, the contained air becomes increasingly compressed. Once sufficiently compressed, this air pressure acts beneficially against the liquid also contained within the accumulator.
This preparation completed, and hand-held spray wand 10 aimed appropriately, shutoff 11 is now opened, which permits the pressurized air acting on the liquid within the accumulator to cause the similarly pressurized liquid to flow out from pressure accumulator 8 and along through hose 9 and wand 10, to spray nozzle 12, where the liquid exits as a spray pattern.
Without such a pressure accumulator, the liquid flowing from the reciprocating action of the manual pump would contain a high pressure pulse on the pressure stroke, followed by zero pressure pulse on the return stroke. Even with a system of check valves, the resulting alternating pressure spikes would make it difficult to establish and sustain the desired flow rate and spray pattern for an application.
With the employment of such a pressure accumulator, the spring-like force provided by the compressed air acts on the liquid co-contained within the accumulator to even-out the incoming alternating pulsations of liquid flow produced by the manual pump. In this manner, liquid pump system 5 can provide a relatively stable average outlet liquid pressure; however, to control this desired liquid pressure at the outlet nozzle, the user must regularly and continuously operate the pump by manually reciprocating handle 1 in order to maintain the needed air pressure within the accumulator. Even with such regular pumping, the air pressure can vary between pump strokes such that the control of outlet liquid pressure and resulting application flow rate are resultantly varying and, therefore, inefficient.
As an improvement to manual pump sprayers, more recently introduced are now-conventional portable liquid-pump sprayers that employ battery-powered electric motor technology to drive the pump. Shown as a backpack sprayer in
Also not required, as needed for the manual liquid pump sprayer, is a pressure accumulator to control the pump outlet pulse variation. The pressure pulses from a battery-powered liquid-pump sprayer pump are of such small magnitude and high speed that the outlet pressure pulse variation is negligible. As will be shown, however, the overall pump outlet pressure can vary unacceptably, depending on the in-use state of charge of the battery.
With power on and the liquid sufficiently pressurized, and with hand-held spray wand 105 aimed appropriately, shutoff 106 is opened, which permits the liquid to flow from the tank and along through hose 104 to outlet spray nozzle 109, where the liquid exits as a pattern.
A battery charge indicator is conveniently provided adjacent to the power switch, so that the user can monitor the in-use state of charge of the rechargeable battery.
For both this exemplar conventional sprayer and the disclosed sprayer to follow, and as a reference for the purpose of this disclosure, a modern nominal 18 V lithium-ion (Li-ion) battery is employed; this battery specifies a safe full-charge state at 21.0 V and a safe depleted state at 16.5 V. Other nominal battery voltage configurations, such as 12, 20, and 40 volts, would be equally applicable for the compared conventional and disclosed sprayers of this disclosure.
The schematic of
Referring to
The battery powers the electric motor, which drives the pump by mechanical means. For this exemplar sprayer, and by convention, the nominal operating demand voltage of the electric motor is 18-volt, to match the nominal 18-volt battery supply voltage.
Note here that the in-use state of charge for a modern Li-ion battery requires proper management by controller 209 in order to provide user safety and to protect the functional integrity of the battery. Accordingly, and as is typical, controller 209 monitors the supply voltage from installed battery 211 so as to limit the upper (full-charge) supply condition at 21.0 V, and terminate the battery supply when the voltage becomes depleted to a low charge limit at 16.5 V. Additionally, the controller terminates the battery supply to the motor if pressure sensor 213 detects a high pressure limit has been reached.
Note also that this battery voltage supplied to the motor directly controls the speed (revolutions/minute) of the motor which, in similarly direct fashion, controls the pump speed and the resulting pump outlet pressure, flow rate, and the ultimate spray pattern for a given nozzle.
As will be shown, a weakness in this voltage control aspect of the conventional battery-powered liquid pump sprayer becomes apparent as the battery voltage supply state depletes during the course of a spray application session. As mentioned earlier, the nominal 18 V motor that is paired with the nominal 18 V battery is specified to provide a determined nominal pump pressure and resulting liquid flow and spray pattern.
However, because the 18 V motor speed is directly related to the battery supply voltage as provided by the controller, a freshly-charged battery at 21.0 V can result in a high application spray pressure and, in corresponding fashion, a depleted-charge battery at 16.5 V can result in a low application spray pressure. For a given nozzle, the resulting variation of pump outlet pressures, caused by this drop in supply voltage to the motor, results in application flow rates and spray patterns that vary from the desired specification.
With continued reference to
A weakness of this means of adjusting pump pressure to correct the loss of spray pattern as the battery voltage charge becomes depleted during the course of a spray application session is that it requires operator judgement and constant attention to the changing spray pattern during the spray application session.
This same weakness holds for those conventional sprayers that provide for nozzle 217 to be adjustable or changed-out to configure for various application spray patterns. As the nozzle is adjusted or changed out, optional flow control 208 may be used to subsequently adjust the pump speed to effect a liquid pressure needed to produce the desired spray pattern from the nozzle outlet. As before, this flow control adjustment requires operator judgement to establish the correct initial pattern, and constant attention to the changing spray pattern during the spray application session.
The battery and motor inputs to the pump are charted over the duration of a spray application session, with the battery supply voltage, as expected, dropping over time from its full-charge state of 21 volts to its full discharge state of 16.5 volts (row 2, columns F-K). The corresponding motor drive speed is seen to drop from 4400 rpm to 3800 rpm (row 4, columns F-K).
Below these charted inputs, the outputs of pump pressure and flow are now considered, with the requisite variation in performance clearly presented.
The 16.5 V low limit of battery supply voltage produces a motor speed of 3800 rpm, with which the pump met the specified performance output of 0.50 gpm at 40 psi (column K, and note C).
Alternatively, the full-charge 21.0 V limit of battery supply voltage produces an increased motor speed of 4400 rpm, with which the pump produced 0.56 gpm at 48.8 psi (column F, and note D).
Thus, it can be appreciated that during a spray session the sprayer performance will vary from the specified value as the battery supply voltage drops. In this selected exemplar session, the pump liquid outlet pressure varied from the specified value by as much as 21%, and the liquid outlet flow varied by as much as 12%.
Beyond this one example, this variation of performance due to a drop in battery performance would occur for any nominal battery output specification for a conventional sprayer and nozzle configuration.
The variation in sprayer performance that results from the drop in battery voltage during a spray session is a weakness found in conventional portable battery-powered liquid pump sprayers. Such sprayers are not capable of sustaining a specified outlet pressure, flow rate, and the resulting desired spray pattern for a given nozzle. Even with an optional flow control, sustaining a desired pressure and flow is a crude and inaccurate process, requiring user judgement and continuous attention to the spray pattern.
Accordingly, there is a need in the art for a battery-powered liquid pump sprayer with a control system that provides the user with a selectable series of defined spray application pressures, flow rates, and patterns that are accurately sustained over the duration of a spray application session.
The present disclosure is directed to a control system for a liquid pump sprayer.
According to an aspect is a battery powered liquid pump sprayer, comprising a liquid tank; a liquid pump having an inlet and an outlet; a conduit fluidly connecting the liquid tank to the inlet of the liquid pump, whereby liquid contained within the liquid tank can flow to the liquid pump; a hose fluidly connected to the outlet of the liquid pump and having a spray nozzle through which pressurized liquid can be discharged; a battery having a nominal low limit of safe battery supply voltage; a motor having a nominal demand voltage that is equivalent to the nominal low limit of safe battery supply voltage; at least one pressure sensor positioned within the hose adjacent the outlet of the liquid pump; a power switch to actuate the battery between on and off positions; a control system electrically coupled between the power switch and the battery and electrically coupled to the at least one pressure sensor; a spray flow control mechanism having a plurality of user selectable flow-control settings and electrically connected to the control system, wherein each flow-control setting has a particular motor demand voltage; wherein the control system comprises a microcomputer controller with pulse width modulation and comparator functions, and the pulse width modulation function continuously attenuates the varying battery supply voltage to the motor so that, for a given flow-control setting, the supply voltage to the motor is maintained at the motor demand voltage needed for that application setting.
Another aspect is a control system for a battery powered liquid pump sprayer. The control system includes a battery having a voltage supply amount, a motor having a voltage demand amount that is less than the voltage supply amount, and a microcontroller coupled to the battery and the motor, wherein the microcontroller is programmed to provide a supply voltage from the battery to the motor and to ensure that the supply voltage is at least as much as the voltage demand amount. The microcontroller may be programmed to attenuate the supply voltage to match the voltage demand amount if the supply voltage is greater than the voltage demand amount. The system may have a spray flow input having a plurality of user selectable flow rates. The microcontroller may be programmed to adjust the supply voltage according to a selected one of the plurality of user selectable flow rates. The microcontroller may be programmed to use pulse width modulation to attenuate the supply voltage. The microcontroller may be programmed to include a comparator function that can continuously read the supply voltage from the battery and compare it to the voltage demand amount. The microcontroller may be programmed to an encoder system for obtaining results from the comparator function and directing the pulse width modulation to continuously attenuate the supply voltage so that the supply voltage matches the voltage demand amount. The encoder system may provide motor speed information to the comparator.
A further aspect is a method of controlling a battery powered liquid pump sprayer. The method involves providing a battery having a voltage supply amount, providing a motor having a voltage demand amount that is less than the voltage supply amount and using a microcontroller coupled to the battery and the motor to provide a supply voltage from the battery to the motor and to ensure that the supply voltage is at least as much as the voltage demand amount. The step of using a microcontroller coupled to the battery and the motor to provide a supply voltage includes the step of attenuating the supply voltage to match the voltage demand amount if the supply voltage is greater than the voltage demand amount. The method may further comprise the step of providing a spray flow input having a plurality of user selectable flow rates. The method may further comprise the step of using the microcontroller to adjust the supply voltage according to a selected one of the plurality of user selectable flow rates. The step of attenuating the supply voltage comprises using pulse width modulation. The method may further include the step of using a comparator function that can continuously read the supply voltage from the battery and compare it to the voltage demand amount. The method may further include the step of using an encoder system for obtaining results from the comparator function and directing the pulse width modulation to continuously attenuate the supply voltage so that the supply voltage matches the voltage demand amount. The method may further include the step of providing motor speed information to the comparator from the encoder system.
These and other aspects of the invention will be apparent from the embodiments described below.
The present invention will be more fully understood and appreciated by reading the following Detailed Description in conjunction with the accompanying drawings, in which:
The present disclosure describes a control system for a liquid pump sprayer and is directed to a battery-powered liquid pump sprayer that comprises a novel control system capable of providing the user with a selectable series of defined spray application pressures, flow rates, and patterns that are accurately sustained over the duration of a spray application session.
A battery charge indicator 312 is conveniently provided adjacent to the power switch 307, so that the user can monitor the in-use state of charge of the rechargeable battery 309.
As with the previously-described exemplar conventional sprayer, the disclosed sprayer employs a modern nominal 18 V lithium-ion (Li-ion) battery; this battery specifies, as is typical, a safe full-charge state at 21.0 V and a safe depleted state at 16.5 V. The battery is inserted for operation, and removed for convenient charging on a separate charging station.
The schematic of
The liquid mixture 313 to be sprayed is filled into tank 301 via the opening at fill cap 302, and enters battery 309 and pump drive systems 304 via inlet filter 314. Battery charge indicator 312 indicates the state of charge of the battery 309. A discrete spray flow control 316 enables one of ten specific nozzle application flow rates to be specified by the user. As power switch 307 is engaged, the liquid flows through inlet filter 314 and is pressurized by battery-powered pump drive system 304. With hand-held spray wand 326 aimed appropriately, shutoff 327 is opened, which permits the liquid to then flow along through hose 325 to outlet spray nozzle 328, where the liquid exits as a pattern.
With continuing reference to
As managed by control system 329, the battery powers the electric motor, which drives the liquid pump by mechanical means. Note that this battery voltage, as supplied to the motor, directly controls the speed (revolutions/minute) of the motor which, in similarly direct fashion, controls the pump speed and the resulting pump outlet pressure, flow rate, and ultimate spray pattern for a given nozzle.
Controller 330, as is a typical requirement for user safety and the integrity of Li-ion batteries, monitors the supply voltage from the battery so as to limit the upper (full-charge) supply condition to 21.0 V, and terminate the battery supply when the voltage becomes depleted to a low charge limit at 16.5 V. Additionally, the controller terminates the battery supply to the motor if pressure sensors 332 detect that either a high pressure limit or low pressure limit has been reached.
A first aspect of this disclosed control system 329 is spray flow control 316, which enables the user to selectively input into controller 330 one of ten different programmed flow rate/nozzle spray application settings. These programmed, nozzle-specific flow rates, range in a preferred embodiment from 0.1 gpm to 0.5 gpm, with each setting a 0.04 gpm increment; of course, other increments and other ranges of values could be provided. As will be further disclosed, for each application setting as input from spray flow control 316, control system 329 will output a unique supply voltage to motor 334, which will result in a unique motor speed and corresponding pump outlet liquid pressure, flow rate, and nozzle-specific spray pattern.
A second aspect of this disclosed control system 329 is the application of an electric motor 334 having a nominal demand voltage that is equivalent to the nominal low limit of safe battery supply voltage.
The low limit of safe battery supply voltage for the considered 18 V Li-ion battery sprayers, as previously discussed, is 16.5 V. Accordingly, unlike the conventional application of an 18 V motor with the 18 V battery supply voltage, here is disclosed the application of a motor with a 16.5 V demand to the 18 V battery. As will be further described, this 16.5 V motor will be specified to deliver the same performance output at the 16.5 V low-limit battery supply voltage that the 18 V motor would deliver at the 16.5 V low-limit supply voltage. Importantly, in this way, the greatest required power output from this disclosed motor will be obtained when both the battery supply voltage and motor demand voltage are 16.5 V.
Continuing with this second aspect, and as previously discussed, 21.0 V is the upper limit of safe battery supply voltage for the 18 V Li-ion battery sprayers under consideration. Thus, for the disclosed sprayer having the 16.5 V motor configured with performance equivalent to the 18 V motor, there is never a battery supply voltage to the motor that is below the highest demand voltage of the motor. The benefit here is that, as the battery naturally discharges during a spraying session, whereby the supply voltage to the motor drops from the 21.0 V full-charge state to the fully-depleted 16.5 V state, the available supply voltage to the motor is always equal to or greater than the motor's 16.5 V demand.
A third aspect of this disclosed control system 329 is the unique utilization of a pulse-width modulation (PWM) function within microcomputer controller 330. In coordination with the first and second aspects whereby, with advantage, the available supply voltage to the motor is always equal to or greater than the highest motor demand voltage, this PWM function will be capably directed to continuously attenuate the varying battery supply voltage to the motor so that, for a given flow-control setting, the supply voltage to the motor is beneficially maintained at the motor demand voltage needed for that application setting.
As will be disclosed next, the PWM is provided a directive control in order to maintain, over the course of a spray session, this continuous and accurate attenuation of the varying supply voltage from the depleting battery.
The fourth aspect of this disclosed control system 329 is the comparator function within microcomputer controller 330. By continuously reading the varying supply voltage from the battery, and by comparing this available supply voltage to the motor demand voltage as specified by the selected flow rate setting, the comparator can accordingly direct the PWM to appropriately attenuate this supply voltage, so that the directed supply voltage meets, but does not exceed or fall below, this specified motor demand voltage.
Alternatively, or as a functional enhancement, the comparator function within microcomputer controller 330 may utilize an encoder system as a means to direct the PWM to appropriately and continuously attenuate the supply voltage to the motor so that, with similar beneficial result, the directed supply voltage matches the motor demand voltage as specified by the selected flow rate setting. This encoder system provides motor speed (revolutions per minute) information to the comparator for the purpose of directing PWM voltage attenuation to match the motor demand voltage as specified by the selected flow rate setting.
In summary, from the schematic of
Despite the drop in available supply voltage from the battery as it discharges during operation, these four aspects of the disclosed control system enable the available battery voltage, as supplied to the motor for each often flow control settings, to be accurately aligned and sustained in order to meet each setting's defined application performance requirements for liquid pressure, flow rate, and nozzle spray pattern for the duration a spraying session.
For this application spraying session, the ten-position flow control is set to provide 0.5 gpm at 40 psi with a straight-stream nozzle (note F). As with the equivalent exemplar conventional sprayer, and for the purpose of this comparison, this application setting represents an equivalent highest-performance output from both sprayers.
As discussed previously, because the disclosed 16.5 V motor is purposefully specified to be equivalent in performance to the conventional 18 V motor, the user-selected flow setting for this 16.5 V motor is obtained, as with the 18 V motor, when the battery supply to the motor is 16.5 volts. With equivalent pumps and nozzles employed, the motor speed necessary to produce this liquid outlet flow and pressure is the same, at 3800 rpm.
Over the duration of the spraying session, the battery becomes discharged, as expected. As shown, the battery supply voltage dropped from its full-charge upper limit of 21 volts, down to its nominal 18 volts, and eventually down to its full-discharge state limit of 16.5 volts (Input/Battery, row 8, columns P-V).
The means by which the disclosed control system can beneficially provide and sustain the user-selected liquid pressure, flow rate, and resulting pattern for the full duration of the spray application session is presented in the charted values for the PWM Percent Duty Cycle (Input/Motor, row 10, columns P-V). As directed by the controller comparator function, the controller PWM function provides greatest attenuation at the battery's upper supply voltage of 21.0 V, resulting in a 75 percent PWM duty cycle (rows 8 and 10, column Q). This attenuation provides the needed supply of 16.5 V to the motor.
As the battery discharges, this charting of the PWM duty cycle shows how the control system continues to provide, with decreasing attenuation provided by the increasing PWM duty cycle, a constant 16.5 V battery supply to the motor.
Accordingly, this constant 16.5 V supply to the motor enables the motor to drive the pump with a constant speed of 3800 rpm (Input/Motor, row 11, columns P-V)
With the motor speed maintained at 3800 rpm for the duration of the spray session, the charting of pump pressure and pump flow (note G) demonstrates that the user-selected application setting of 0.50 gpm at 40 psi is accordingly held constant for the session, even as the battery supply voltage is dropping from its upper limit of 21.0 volts to its lower limit of 16.5 volts.
The disclosed beneficial control of liquid pump performance as charted in
As has been shown, for both manual and battery-powered liquid pump sprayers, the means for control of liquid pressure is an important aspect of sprayer performance.
The novel control system disclosed herein improves upon such conventional sprayers by providing a user-selectable series of defined spray application pressures, flow rates, and patterns that are that are accurately sustained over the duration of a spray application session. This control system provides for efficient, accurate, and economical application of the sprayed liquid product.
While various embodiments have been described and illustrated herein, those of ordinary skill in the art will readily envision a variety of other means and/or structures for performing the function and/or obtaining the results and/or one or more of the advantages described herein, and each of such variations and/or modifications is deemed to be within the scope of the embodiments described herein. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and/or configurations will depend upon the specific application or applications for which the teachings is/are used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments described herein. It is, therefore, to be understood that the foregoing embodiments are presented by way of example only and that, within the scope of the appended claims and equivalents thereto, embodiments may be practiced otherwise than as specifically described and claimed. Embodiments of the present disclosure are directed to each individual feature, system, article, material, kit, and/or method described herein. In addition, any combination of two or more such features, systems, articles, materials, kits, and/or methods, if such features, systems, articles, materials, kits, and/or methods are not mutually inconsistent, is included within the scope of the present disclosure.
The above-described embodiments of the described subject matter can be implemented in any of numerous ways. For example, some embodiments may be implemented using hardware, software or a combination thereof. When any aspect of an embodiment is implemented at least in part in software, the software code can be executed on any suitable processor or collection of processors, whether provided in a single device or computer or distributed among multiple devices/computers.
The present application relates and claims priority to Applicant's U.S. Provisional Patent Application No. 63/212,796, filed Jun. 21, 2021, the entirety of which is hereby incorporated by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US22/34329 | 6/21/2022 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 63212796 | Jun 2021 | US |
