Flow-adjustable coaxial reverse centrifugal atomization nozzle and use method

Abstract

The invention discloses a flow-adjustable coaxial reverse centrifugal atomization nozzle and a using method, and belongs to the technical field of plant protection unmanned aerial vehicles. A proportional electromagnetic valve and a motor are fixed in a protective shell, a liquid inlet funnel is fixed to the bottom of the protective shell, and a liquid inlet pipe of the proportional electromagnetic valve communicates with an outlet of a liquid medicine box of the plant protection unmanned aerial vehicle; the liquid outlet pipe is communicated with a liquid inlet of the liquid inlet funnel, and the flow adjusting unit is connected with the proportional electromagnetic valve and used for controlling the opening degree of a valve element of the proportional electromagnetic valve. The upper-layer atomizing disc is fixed to the bottom of the liquid inlet funnel, the lower-layer atomizing disc is arranged in an inner cavity in the bottom of the upper-layer atomizing disc, a gap between the upper-layer atomizing disc and the lower-layer atomizing disc forms a spraying opening of the centrifugal atomizing nozzle, a planetary gear mechanism is installed in the upper-layer atomizing disc, and an output shaft of the motor sequentially penetrates through the liquid inlet funnel and a driving gear in the planetary gear mechanism and then is fixed to the lower-layer atomizing disc. The planetary gear mechanism is used for driving the upper atomizing disc to rotate opposite to the output shaft of the motor, adjustment is convenient, and performance is stable.

Description

Technical Field

[0001] The present invention belongs to the technical field of plant protection unmanned aerial vehicles, and particularly relates to a coaxial reverse centrifugal atomizing nozzle with adjustable flow rate and a using method thereof. Background Art

[0002] Plant protection unmanned aerial vehicles have been widely used in agriculture and forestry. Spraying pesticides using unmanned aerial vehicles can not only save manpower and material resources, but also be remotely controlled from a distance to avoid the harm to operators from pesticides. The use of plant protection unmanned aerial vehicles improves the safety of operations and significantly improves the efficiency of pesticide spraying.

[0003] The commonly used nozzles for plant protection unmanned aerial vehicles are mainly divided into pressure nozzles and centrifugal nozzles. Pressure nozzles have defects such as being prone to blockage, uneven atomization, and poor adaptability to high-viscosity materials. In addition, since the system needs to spray the liquid from the nozzle through high pressure, the presence of a high-pressure pump increases the complexity, cost, and energy consumption of the system, and requires a certain installation space, which has certain limitations on the wide adoption of the system. During the process of the liquid passing through the nozzle at high speed, a large scouring force will be generated on the nozzle, and long-term use will lead to increased wear of the nozzle, increasing the use cost and maintenance workload. Centrifugal nozzles belong to ultra-low volume atomizing nozzles, which use an electric motor to drive the atomizing disk to rotate at a high speed to generate centrifugal force to atomize the liquid medicine. They have advantages such as good atomization effect, wide application range, not easy to block, and convenient replacement.

[0004] Centrifugal atomizing nozzles mainly adopt a single-motor single-atomizing disk structure or a multi-atomizing disk coaxial and co-rotating structure. With the progress of technology, the existing centrifugal atomizing nozzles have problems such as deviation in atomization effect, low operation efficiency, and large volume. Therefore, the demand for new atomizing nozzles for agricultural plant protection unmanned aerial vehicles is increasing day by day. The utility model patent with the application number 202223467698.7 and the name of "A Coaxial Reverse Centrifugal Atomizing Nozzle" discloses a structure with coaxial reverse rotation of the atomizing disk, specifically including a centrifugal atomizing upper disk, a centrifugal atomizing lower disk, a transmission outer shaft, and a transmission inner shaft. Multiple teeth are arranged at intervals along the circumference at the edge of the centrifugal atomizing upper disk. The centrifugal atomizing lower disk has multiple diversion grooves and multiple teeth are arranged at intervals along the circumference at the edge. The centrifugal atomizing upper disk and the centrifugal atomizing lower disk are coaxially arranged. The bevel gear transmits the power input by the motor to the centrifugal atomizing upper disk and the centrifugal atomizing lower disk through the outer shaft and the inner shaft, so that the two atomizing disks perform coaxial reverse rotation, so that the atomizing nozzle performs atomization operation. This secondary atomization mechanism has a more uniform particle size distribution, making the droplets have both a smaller particle size and appropriate kinetic energy, balancing the penetrability and anti-drift ability, improving the adhesion and coverage rate of the liquid medicine on the crop surface, and reducing drift and bounce. Smaller droplets can penetrate deep into the crop canopy through Brownian motion. However, this centrifugal atomizing nozzle only realizes coaxial reverse rotation under a single motor from the structure, and cannot adjust the flow rate according to different crops, which is not conducive to improving the comprehensive control operation of plant protection unmanned aerial vehicles against various crop diseases and pests. Summary of the Invention

[0005] Aiming at the problems existing in the prior art, the present invention provides a coaxial reverse centrifugal atomizing nozzle with adjustable flow rate and its usage method, which solves the problem that the current coaxial reverse centrifugal atomizing nozzle cannot adjust the flow rate according to different crops, and has convenient adjustment and stable performance.

[0006] The present invention is realized through the following technical solutions: A coaxial reverse centrifugal atomizing nozzle with adjustable flow rate, including a proportional solenoid valve, a motor, a liquid inlet funnel, an upper atomizing disk, and a controller, a flow sensor and a solenoid valve driver arranged on a plant protection unmanned aerial vehicle; The proportional solenoid valve and the motor are fixed in a protective shell. The liquid inlet funnel is fixedly connected to the bottom of the protective shell. The liquid inlet pipe of the proportional solenoid valve is communicated with the outlet of the liquid medicine tank of the plant protection unmanned aerial vehicle, and the liquid outlet pipe of the proportional solenoid valve is communicated with the liquid inlet of the liquid inlet funnel; The upper atomizing disk is fixed to the bottom of the liquid inlet funnel, and the lower atomizing disk is arranged in the upper atomizing disk. A planetary gear mechanism is installed in the upper atomizing disk. The output shaft of the motor sequentially passes through the liquid inlet funnel and the driving gear in the planetary gear mechanism and is then fixed to the lower atomizing disk. The planetary gear mechanism is used to drive the upper atomizing disk to rotate in the opposite direction to the output shaft of the motor; The controller is used to collect the flow feedback value of the flow sensor in real time, and then output a PWM control signal to the solenoid valve driver; the solenoid valve driver is used to analyze the PWM control signal, control the average voltage applied to the proportional solenoid valve through the duty cycle, and further control the valve core opening of the proportional solenoid valve.

[0007] A further improvement of the present invention lies in: The protective shell includes a first protective shell and a second protective shell with the same shape and size. The first protective shell and the second protective shell are aligned and spliced to form the protective shell. The protective shell is divided into a cuboid section and a frustum section from top to bottom, and their central axes coincide. The upper opening of the frustum section is smaller than the lower opening, and one side of the cuboid section is open; The end cover of the proportional solenoid valve is fixed in the cuboid section. The liquid inlet pipe and the liquid outlet pipe are arranged outside the protective shell through the opening of the cuboid section. The motor is a brushless motor, and the brushless motor is fixed in the frustum section.

[0008] The end cover of the proportional solenoid valve is a cuboid, and the length, width and height are respectively the same as the corresponding dimensions of the cuboid cavity formed by the inner wall of the cuboid section. Positioning pins are respectively arranged at the centers of the front and rear two faces. Pin holes are opened at the positions corresponding to the positioning pins in the cuboid section. The end cover of the proportional solenoid valve fits in the cuboid cavity of the cuboid section, and the positioning pins are in interference fit with the corresponding pin holes.

[0009] It also includes a cylindrical motor cover. A step is provided along the circumference at the top of the motor cover. The cylindrical boss corresponding to the vertical section of the step is fixedly inserted into the opening at the lower end of the frustum section of the protective shell. The liquid inlet funnel is fixedly connected to the frustum section of the protective shell through the motor cover; A circular groove communicating with the outside is provided at the center of the top of the motor cover. A motor shaft hole communicating with the inner cavity of the motor cover is provided at the center of the groove. Four bolt holes are evenly provided along the circumference outside the groove at the top of the motor cover. After the output shaft of the brushless motor passes through the motor shaft hole, it then passes through the liquid inlet funnel and the driving gear in the planetary gear mechanism in sequence. After the bottom connecting plate of the brushless motor housing contacts the top of the motor cover, the through holes at the four corners of the connecting plate are respectively aligned with each bolt hole. Four bolts respectively pass through the through holes at the four corners of the connecting plate, and the ends are installed in the bolt holes at the top of the motor cover.

[0010] The liquid inlet funnel is a cylindrical groove with the same outer diameter as the motor cover. A step is provided along the circumference at the bottom of the motor cover. The cylindrical boss corresponding to the vertical section of the step fits with the inner wall of the liquid inlet funnel. Four symmetrically distributed and flush cylindrical bumps are provided along the circumference on the boss. L-shaped through grooves are respectively provided at the positions corresponding to the cylindrical bumps on the upper side of the liquid inlet funnel. The horizontal sections of the through grooves are distributed in the same direction, and the inner diameter of the through grooves is the same as that of the cylindrical bumps; The liquid inlet pipe of the liquid inlet funnel has a radian of π / 12, and the upper end of the liquid inlet pipe is the liquid inlet of the liquid inlet funnel.

[0011] The upper atomization disc includes an atomization disc body and a convex ring vertically extending upward along the inner diameter of the atomization disc body. The convex ring is fixed at the bottom of the liquid inlet funnel in a horizontal state, and a planetary gear mechanism is installed in the convex ring of the upper atomization disc; The planetary gear mechanism includes an inner ring gear, a driving gear, and three first planet gears, second planet gears, and third planet gears with the same structure and size. The inner ring gear is fixed on the inner side wall of the convex ring of the upper atomization disc in a horizontal state, and the two are in interference fit. The centers of the driving gear and the inner ring gear coincide. The output shaft of the brushless motor is fixedly penetrated through the driving gear, and the center of the output shaft of the brushless motor coincides with the center of the driving gear. The first planet gear, the second planet gear, and the third planet gear are evenly distributed along the circumference of the driving gear and respectively mesh with the teeth of the driving gear and the inner ring gear.

[0012] The first planet gear, the second planet gear, and the third planet gear are each fixedly sleeved on a transmission bearing, and the three transmission bearings are each fixedly sleeved on a core shaft. Each transmission bearing is connected to the liquid inlet funnel through its corresponding core shaft, and the upper end of the core shaft is fixed in the bottom surface of the liquid inlet funnel; A support bearing is provided between the convex ring of the upper atomization disc and the inner wall of the liquid inlet funnel. The outer ring of the support bearing is in interference fit with the inner wall of the liquid inlet funnel.

[0013] The bottom of the lower atomizing disk and the upper atomizing disk are flush and their centers coincide. A sleeve perpendicular to the atomizing disk body is provided at the center of the lower atomizing disk, and the end of the output shaft of the brushless motor is fixedly inserted into the sleeve, and the two are in interference fit; The atomizing disk body of the upper atomizing disk is in the shape of a frustum of a cone, with the lower opening larger than the upper opening. 50 - 70 radially distributed rectangular atomizing teeth are evenly arranged along the circumferential direction on the inner wall of the atomizing disk body, and the rectangular atomizing teeth extend beyond the outer edge and the inner edge of the atomizing disk body; 50 - 70 diversion channels are evenly arranged along the circumferential direction on the atomizing disk body of the lower atomizing disk. The inner side of each diversion channel is far away from the sleeve, and the inner sides of all the diversion channels form a circle. The outer side of each diversion channel extends to the edge of the atomizing disk body, and each diversion channel is in an arc distribution.

[0014] A method for using a flow - adjustable coaxial reverse - rotation centrifugal atomizing nozzle according to any one of the above, characterized by comprising the following steps: S1, The mixed and prepared liquid medicine is stored in the liquid supply tank of the plant protection unmanned aerial vehicle; The motor transmits power to the lower atomizing disk to realize the forward rotation of the lower atomizing disk; The motor transmits power to the driving gear, and the planetary gear mechanism realizes the reverse rotation of the upper atomizing disk; S2, After the controller receives the target flow command signal from the upper computer, it real - time collects the flow feedback value of the flow sensor, and then outputs a PWM control signal to the solenoid valve driver. The solenoid valve driver analyzes the PWM control signal, controls the average voltage applied to the proportional solenoid valve through the duty cycle, and further controls the valve core opening of the proportional solenoid valve; S3, Under the control of the proportional solenoid valve, the liquid medicine is supplied to the liquid inlet funnel. After the liquid medicine flows through the liquid inlet funnel to the inside of the lower atomizing disk for primary atomization and then enters the inside of the upper atomizing disk for secondary atomization, it is ejected from the gap between the lower atomizing disk and the upper atomizing disk under the action of centrifugal force and physical fragmentation of the lower atomizing disk and the upper atomizing disk.

[0015] After the controller in S2 real - time collects the flow feedback value of the flow sensor, it executes the flow - loop PID control algorithm of the following process to obtain the duty cycle of the proportional solenoid valve drive signal, and then outputs a PWM control signal to the solenoid valve driver according to the duty cycle of the proportional solenoid valve drive signal: The controller obtains the actual flow and the desired flow based on the flow feedback value, and the flow deviation e 1 is:

[0016] where, q is the desired flow of the nozzle, q1 is the actual flow rate of the nozzle; Calculate the adjustment signal using the following PID control formula u 1 That is:

[0017] Wherein, K p 1 is the proportionality coefficient, K i 1 is the integral coefficient, K d 1 is the differential coefficient, T i 1 is the integral time; Based on the adjustment signal u 1 and the flow deviation e 1 obtain the flow adjustment value q 0 :

[0018] Based on the relationship between the PWM duty cycle of the proportional solenoid valve drive signal and the flow adjustment value as shown below q 0 determine the duty cycle of the proportional solenoid valve drive signal: .

[0019] Wherein, D is the duty cycle of the proportional solenoid valve drive signal, K is the proportionality coefficient, D min is the minimum effective duty cycle.

[0020] Compared with the prior art, the present invention has the following beneficial technical effects: The present invention relates to a coaxial reverse centrifugal atomizing nozzle with adjustable flow rate. An inlet funnel, an upper atomizing disc and a lower atomizing disc form an atomizing assembly. The motor first transmits power to the lower atomizing disc to achieve the forward high-speed rotation of the lower atomizing disc. At the same time, the motor transmits power to the driving gear, and the planetary gear mechanism can achieve the reverse rotation of the upper atomizing disc. After the mixed and prepared liquid medicine is stored in the liquid supply tank of the plant protection unmanned aerial vehicle, the flow rate regulating unit can control the valve core opening of the proportional solenoid valve, and supply it to the inlet funnel under the control of the proportional solenoid valve. The liquid medicine flows through the inlet funnel to the inside of the lower atomizing disc for primary atomization and then enters the inside of the upper atomizing disc for secondary reverse atomization and then sprays out, improving the atomization performance. The additionally added proportional solenoid valve also ensures that the overall nozzle is small in size, compact in structure and convenient to install on the plant protection unmanned aerial vehicle. The two atomizing discs improve the atomization level, and the double-disc coaxial reverse rotation is achieved by relying on the planetary gear mechanism to further improve the atomization effect. The liquid medicine realizes two-stage crushing atomization through the high-speed rotational movement of the atomizing disc. The atomized liquid medicine particles are ejected from the spraying port (the gap between the lower atomizing disc and the upper atomizing disc) under the action of centrifugal force and the physical crushing of the two-layer atomizing disc, realizing the spraying operation. The flow rate can be adjusted according to different crops, which is beneficial to improving the comprehensive prevention and control operation of the plant protection unmanned aerial vehicle against various crop diseases and pests.

[0021] Furthermore, through the simple structural design of the planetary gear mechanism composed of an inner ring gear, a driving gear, and the first, second, and third planetary gears, the meshing between the teeth can achieve the coaxial reverse rotation of the lower atomizing disc and the upper atomizing disc without a gearbox, and the flowing liquid medicine can cool the high-speed rotating gears, which is beneficial to the stable operation of the planetary gear mechanism.

[0022] The using method of the coaxial reverse centrifugal atomizing nozzle with adjustable flow rate according to the present invention is as follows: The motor transmits power to the lower atomizing disc to achieve the forward rotation of the lower atomizing disc. At the same time, the motor transmits power to the driving gear, and the planetary gear mechanism achieves the reverse rotation of the upper atomizing disc. After the mixed and prepared liquid medicine is stored in the liquid supply tank of the plant protection unmanned aerial vehicle, the flow rate regulating unit receives the target flow rate command signal from the upper computer, and then controls the valve core opening. Under the control of the proportional solenoid valve, the liquid medicine is supplied to the inlet funnel. The liquid medicine flows through the inlet funnel to the inside of the lower atomizing disc for primary atomization and then enters the inside of the upper atomizing disc for secondary atomization. Then, under the action of centrifugal force and the physical crushing of the two-layer atomizing disc, it is ejected from the gap between the lower atomizing disc and the upper atomizing disc. The flow rate can be adjusted according to different crops, which is beneficial to improving the comprehensive prevention and control operation of the plant protection unmanned aerial vehicle against various crop diseases and pests. The high-speed rotating centrifugal nozzle can change the rotation speed to obtain fog droplets of different sizes, and at the same time can change the flow rate for different crops, greatly improving the atomization effect of the liquid medicine, especially suitable for scenarios sensitive to endurance, and can extend the operation time. Description of the Drawings

[0023] Figure 1 This is the assembly drawing of the centrifugal atomizing nozzle described in the present invention.

[0024] Figure 2 It is Figure 1 the exploded view of the parts of

[0025] Figure 3 It is Figure 1 the structural schematic diagram of the planetary gear mechanism in

[0026] Figure 4a It is Figure 1 the structural schematic diagram of the motor cover in

[0027] Figure 4b It is Figure 1 the structural schematic diagram of the liquid inlet funnel in

[0028] Figure 4c It is Figure 1 the assembly drawing of the motor cover and the liquid inlet funnel in

[0029] Figure 5 It is Figure 1 the structural schematic diagram of the upper atomizing disc in

[0030] Figure 6 It is Figure 1 the structural schematic diagram of the lower atomizing disc in

[0031] Figure 7 This is the overall working flow chart of the centrifugal atomizing nozzle described in the present invention.

[0032] Figure 8 This is the speed adjustment flow chart of the centrifugal atomizing nozzle described in the present invention.

[0033] Figure 9 This is the liquid supply flow rate adjustment flow chart of the centrifugal atomizing nozzle described in the present invention.

[0034] In the figure: 1 - proportional solenoid valve; 2 - first protective shell; 3 - second protective shell; 4 - brushless motor; 5 - bolt; 6 - motor cover; 7 - liquid inlet funnel; 8 - support bearing; 9 - core shaft; 10 - driving gear; 11 - transmission bearing; 12 - first planet gear; 13 - second planet gear; 14 - third planet gear; 15 - inner ring gear; 16 - upper atomizing disc; 17 - lower atomizing disc; 101 - liquid inlet pipe; 102 - liquid outlet pipe. Specific embodiments

[0035] The following further elaborates on the present invention in conjunction with specific embodiments, which is an explanation rather than a limitation of the present invention.

[0036] A flow rate adjustable coaxial reverse centrifugal atomizing nozzle of the present invention is first described in terms of its mechanical structure, that is, the function of coaxial reverse: The centrifugal atomizing nozzle includes a protective shell, a liquid inlet funnel 7 and a motor cover 6. As Figure 1 and Figure 2 shown, the upper end of the motor cover is fixedly inserted into the bottom of the protective shell, the upper end of the liquid inlet funnel 7 is fixed to the bottom of the motor cover 6, a proportional solenoid valve 1 is installed in the upper half of the protective shell, the liquid inlet pipe 101 and the liquid outlet pipe 102 of the proportional solenoid valve 1 are located outside the protective shell, the liquid inlet pipe 101 is communicated with the liquid outlet of the liquid medicine tank of the plant protection UAV through an infusion hose, and the liquid outlet pipe 102 is communicated with the liquid inlet of the liquid inlet funnel 7 through an infusion hose. A through hole is opened on the protective shell and can be fixed to the spray rod of the plant protection UAV by bolts. The spray rod is located directly below each rotor of the plant protection UAV, and the uppermost end of the entire nozzle is installed at the lowermost end of the spray rod. The spray rod is used for wiring and arranging the water path.

[0037] A brushless motor 4 is installed in the lower half of the protective shell, which can protect the circuits of the brushless motor 4 and the proportional solenoid valve 1. The output shaft of the brushless motor 4 extends vertically downward through the motor cover 6 and the liquid inlet funnel 7. The connecting plate at the bottom of the brushless motor 4 housing is fixed to the top of the motor cover 6 by bolts 5. The upper atomizing disc 16 includes an atomizing disc body and a convex ring vertically extending upward along the inner diameter of the atomizing disc body. The convex ring is fixed to the bottom of the liquid inlet funnel 7 in a horizontal state. A planetary gear mechanism is installed in the convex ring of the upper atomizing disc 16.

[0038] As Figure 3 shown, the planetary gear mechanism includes an inner ring gear 15, a driving gear 10 and three driven gears with the same structure and size, namely the first planet gear 12, the second planet gear 13 and the third planet gear 14. The inner ring gear 15 is fixed to the inner side wall of the convex ring of the upper atomizing disc 16 in a horizontal state, and the two are in interference fit, so that the power can be transmitted to the upper atomizing disc. The centers of the driving gear 10 and the inner ring gear 15 coincide. The output shaft of the brushless motor 4 is fixedly penetrated through the driving gear 10, and the center of the output shaft of the brushless motor 4 coincides with the center of the driving gear 10. The three driven gears are evenly distributed along the circumference of the driving gear 10, and the teeth are meshed with the teeth of the driving gear 10 and the inner ring gear 15 respectively. The lower atomizing disc 17 is arranged in the inner cavity at the bottom of the upper atomizing disc 16. The gap between the lower atomizing disc 17 and the upper atomizing disc 16 forms the spraying orifice of the centrifugal atomizing nozzle. Their bottoms are flush and the centers coincide. A sleeve perpendicular to the atomizing disc body is arranged at the center of the lower atomizing disc 17. The end of the output shaft of the brushless motor 4 is fixedly inserted into the sleeve, and the two are in interference fit.

[0039] The liquid inlet funnel 7, the upper atomizing disk 16 and the lower atomizing disk 17 constitute an atomizing assembly. The brushless motor 4 first transmits power to the lower atomizing disk 17 to realize the forward rotation of the lower atomizing disk. At the same time, the brushless motor 4 also transmits power to the driving gear 10. Through the meshing of the driving gear 10 with the first planetary gear 12, the second planetary gear 13 and the third planetary gear 14, the power is transmitted to the inner ring gear 15, and then through the interference connection between the inner ring gear 15 and the upper atomizing disk 16, the power is transmitted to the upper atomizing disk 16 to realize the reverse rotation of the upper atomizing disk 16. The mixed and prepared liquid medicine is stored in the liquid supply tank of the plant protection UAV and is supplied to the liquid inlet funnel 7 under the control of the proportional solenoid valve 1. The liquid medicine flows through the liquid inlet funnel 7 to the inside of the lower atomizing disk 17 for primary atomization and then enters the inside of the upper atomizing disk 16 for secondary atomization and then is sprayed out. This process is completed in a very short time. The two atomizing disks improve the atomization level, and rely on the planetary gear mechanism to achieve the coaxial reverse rotation of the two disks to further improve the atomization effect. The liquid medicine realizes two-stage crushing atomization through the high-speed rotation movement of the atomizing disk. The atomized liquid medicine particles are ejected from the spraying port (the gap between the lower atomizing disk 17 and the upper atomizing disk 16) under the action of centrifugal force to realize the spraying operation.

[0040] The protective shell of the present invention specifically includes a first protective shell 2 and a second protective shell 3 with the same shape and size. After the first protective shell 2 and the second protective shell 3 are aligned and spliced with each other, a protective shell is formed. The protective shell is divided into a cuboid section and a frustum section from top to bottom, and their central axes coincide. The upper opening of the frustum section is smaller than the lower opening. One side of the cuboid section is provided with an opening. The liquid inlet pipe 101 and the liquid outlet pipe 102 are arranged outside the protective shell through the opening of the cuboid section. The end cover of the proportional solenoid valve 1 is a cuboid, and the length, width and height are respectively the same as the corresponding dimensions of the cuboid cavity formed by the inner wall of the cuboid section. Positioning pins are respectively arranged at the centers of the front and rear two faces. Pin holes are opened at the positions of the cuboid section corresponding to the positioning pins. The end cover of the proportional solenoid valve 1 is fitted in the cuboid cavity of the cuboid section, and the positioning pins are in interference fit with the corresponding pin holes. The upper end face of the cuboid section extends outward horizontally to be provided with a connecting plate. Through holes are opened at the four corners of the connecting plate and are fixed directly below each rotor of the plant protection UAV by bolts. In this way, the first protective shell 2 and the second protective shell 3 are connected to the proportional solenoid valve 1. The proportional solenoid valve 1 is fixed inside the protective shell. The first protective shell 2 and the second protective shell 3 are convenient to open, close and disassemble, and the proportional solenoid valve 1 can further realize the control of the flow rate.

[0041] As Figure 4aAs shown, the motor cover 6 is cylindrical. A circular groove communicating with the outside is provided at the center of the top of the motor cover 6. A motor shaft hole communicating with the inner cavity of the motor cover 6 is provided at the center of this groove. Four bolt holes are evenly arranged circumferentially on the top of the motor cover 6 along the outer edge of this groove. The output shaft of the brushless motor 4 passes through the motor shaft hole. After the bottom connecting plate of its housing contacts the top of the motor cover 6, the through holes at the four corners of the connecting plate are respectively aligned with each bolt hole. Four bolts 5 respectively pass through the through holes at the four corners of the connecting plate, and the ends are installed in the bolt holes at the top of the motor cover 6, so that the brushless motor 4 can be fixed in the frustum section of the protective shell. A step is arranged circumferentially on the top of the motor cover 6, and the cylindrical boss corresponding to the vertical section of the step is fixedly inserted into the opening at the lower end of the frustum section of the protective shell.

[0042] As Figure 4b shown, the liquid inlet funnel 7 is a cylindrical groove with the same outer diameter as the motor cover 6. A step is also arranged circumferentially at the bottom of the motor cover 6. The cylindrical boss corresponding to the vertical section of the step fits with the inner wall of the liquid inlet funnel 7. Four symmetrically distributed and flush cylindrical protrusions are arranged circumferentially on this boss. As Figure 4c shown, L-shaped through grooves are provided at the positions corresponding to these protrusions on the upper side of the liquid inlet funnel 7. The horizontal sections of the four through grooves are distributed in the same direction, and the inner diameter of the through grooves is the same as that of the protrusions. In this way, each protrusion can be connected in cooperation with the corresponding through groove. When the protrusion reaches the bottom of the through groove and rotates the motor cover 6 along the horizontal section of the through groove, the liquid inlet funnel 7 and the motor cover 6 can be relatively fixed in position. By adopting this connection method, the liquid inlet funnel 7 and the motor cover 6 can be quickly disassembled and installed in a plug-and-play manner, the parts can be replaced quickly, the work efficiency can be effectively improved, and the installation and use are reliable. At the same time, a motor lower end protective cover is provided at the center of the bottom of the liquid inlet funnel, which contacts the motor output shaft, so that the liquid medicine will not contact the motor output shaft, thereby protecting the motor output shaft.

[0043] Each of the three driven gears is fixedly sleeved on a transmission bearing 11, and each of the three bearings is fixedly sleeved on the core shaft 9. Each transmission bearing 11 is connected to the liquid inlet funnel 7 through its corresponding core shaft 9, and the upper end of the core shaft 9 is fixed in the bottom surface of the liquid inlet funnel 7.

[0044] A support bearing 8 is arranged between the convex ring of the upper atomizing disk 16 and the inner wall of the liquid inlet funnel 7. The outer ring of the support bearing 8 is in interference fit with the inner wall of the liquid inlet funnel 7. The liquid inlet pipe of the liquid inlet funnel 7 has a 15° slope to play a role in sufficient liquid inlet.

[0045] To improve the ability of the atomizing disk to break the liquid medicine, as Figure 5 shown, 50 - 70 radially distributed rectangular atomizing teeth are evenly arranged circumferentially on the inner wall of the atomizing disk body (which is a frustum-shaped structure, with the lower opening larger than the upper opening, so as to form a certain inclination angle, which is more conducive to the outflow of the liquid medicine) of the upper atomizing disk 16. These rectangular atomizing teeth extend out of the outer edge and the inner edge of the atomizing disk body. As Figure 6As shown in the figure, 50 to 70 diversion grooves are evenly arranged along the circumference on the atomization disk body of the lower atomization disk 17. The inner sides of each diversion groove are far away from the sleeve. The inner sides of all the diversion grooves form a circle. The outer sides of each diversion groove extend to the edge of the atomization disk body, and each diversion groove is distributed in an arc shape.

[0046] For a coaxial reverse centrifugal atomizing nozzle with adjustable flow rate in the present invention, the following is an explanation from the aspects of nozzle speed adjustment and liquid inlet flow rate control: The brushless motor control system based on speed loop PID control in the present invention realizes the adjustment of the nozzle speed. The system includes a controller, a brushless motor driver and a Hall element arranged on the plant protection unmanned aerial vehicle. The output end of the Hall element is connected to the input end of the controller, the output end of the controller is connected to the input end of the brushless motor driver, the output end of the brushless motor driver is connected to the input end of the brushless motor, and the output end of the brushless motor is connected to the input end of the Hall element; the controller is used to receive the target rotation speed command signal from the upper computer (unmanned aerial vehicle flight control system), collect the motor rotation speed feedback value of the Hall element in real time and execute the speed loop PID control algorithm, and output a PWM control signal to the brushless motor driver; the brushless motor driver is used to analyze the PWM signal output by the controller. The brushless motor driver adjusts the voltage amplitude of the three-phase full-bridge inverter circuit according to the PWM duty ratio, generates a six-step commutation drive waveform with a phase difference of 120°, directly controls the motor winding current, and thus adjusts the output rotation speed. At the same time, it has an overheat protection function; the Hall element is used to detect the position of the rotor and output a motor rotation speed feedback signal; the brushless motor is used to drive the atomization disk to rotate.

[0047] The proportional solenoid valve control system based on flow loop PID control in the present invention includes a controller, a solenoid valve driver and a liquid flow sensor arranged on the plant protection unmanned aerial vehicle. The liquid flow sensor is specifically installed on the spray boom of the plant protection unmanned aerial vehicle. The output end of the liquid flow sensor is connected to the input end of the controller, the output end of the controller is connected to the input end of the solenoid valve driver, the output end of the solenoid valve driver is connected to the input end of the proportional solenoid valve, and the output end of the proportional solenoid valve is connected to the input end of the liquid flow sensor; the controller is used to receive the target flow rate command signal from the upper computer, collect the flow rate feedback value of the flow sensor in real time and execute the flow loop PID control algorithm, and output a PWM control signal to the solenoid valve driver; the solenoid valve driver is used to analyze the PWM signal output by the controller, and controls the average voltage applied to the proportional solenoid valve through the PWM signal duty ratio, and further controls the valve core opening.

[0048] After the controller receives the target speed command signal from the host computer, it collects the motor speed feedback value of the Hall element in real time, executes the speed loop PID control algorithm, and outputs the PWM control signal to the brushless motor driver. The brushless motor driver analyzes the PWM control signal, and adjusts the voltage amplitude of the three-phase full-bridge inverter circuit according to the PWM duty ratio to generate a six-step commutation drive waveform with a phase difference of 120°, directly controlling the motor winding current, thereby adjusting the output speed. Figure 8 is the centrifugal atomizing nozzle speed adjustment flowchart, setting the desired speed of the nozzle v , detecting the actual speed of the nozzle through the Hall element v 1 , comparing the desired speed v and the actual speed v 1 , if the two are equal, continue to output the PWM signal from the brushless motor controller to the brushless motor driver to drive the brushless motor to run; if not equal, adjust the controller parameters to make the actual speed reach the desired speed, so as to achieve precise control of the brushless motor. The specific adjustment process is as follows: The controller obtains the actual speed and the desired speed of the nozzle based on the real-time feedback signal of the Hall element, then the speed deviation e is:

[0049] where, v is the desired speed of the nozzle, v 1 is the actual speed of the nozzle; Based on the speed deviation e , the adjustment signal u can be calculated by applying the PID control formula as:

[0050] where, K p is the proportional coefficient, K i is the integral coefficient, K d is the differential coefficient, T i is the integral time; Based on the adjustment signal u the speed adjustment value v 0 of the nozzle can be obtained:

[0051] The controller will adjust the speed value v 0Output a PWM control signal in PWM form and send it to the motor driver to control the motor to reach the desired speed.

[0052] After the controller receives the target flow command signal from the host computer, it real-time collects the flow feedback value of the flow sensor, executes the flow loop PID control algorithm to obtain the duty cycle of the proportional solenoid valve drive signal, and then outputs a PWM control signal to the solenoid valve driver according to the duty cycle of the proportional solenoid valve drive signal. The solenoid valve driver analyzes the PWM control signal and controls the average voltage applied to the proportional solenoid valve 1 through the duty cycle, thereby controlling the valve core opening of the proportional solenoid valve 1. Figure 9 It is the flow adjustment flowchart of the centrifugal atomizing nozzle. Set the desired flow of the nozzle q , and detect the actual flow of the nozzle through the liquid flow sensor q 1 , compare the desired flow q and the actual flow q 1 . If the two are equal, continue to output a PWM signal by the controller to control the flow of the proportional solenoid valve; if they are not equal, adjust the controller parameters to make the actual flow reach the desired flow, so as to achieve precise control of the liquid supply volume of the nozzle. The adjustment process of the specific flow loop PID control algorithm is as follows: The controller obtains the actual flow and desired flow of the nozzle based on the real-time feedback signal (flow feedback value) of the liquid flow sensor, then the flow deviation e 1 is:

[0053] where, q is the desired flow of the nozzle, q 1 is the actual flow of the nozzle; Apply the PID control formula to calculate the adjustment signal u 1 is:

[0054] where, K p 1 is the proportional coefficient, K i 1 is the integral coefficient, K d 1 is the differential coefficient, T i 1 is the integral time; Based on the adjustment signal u 1 and the flow deviatione 1 The flow rate adjustment value of the nozzle can be obtained. q 0 :

[0055] Based on the PWM duty cycle of the proportional solenoid valve drive signal and the flow rate adjustment value q 0 Determine the duty cycle of the proportional solenoid valve drive signal: .

[0056] Where q 0 is the flow rate adjustment value, D is the duty cycle of the proportional solenoid valve drive signal, that is, the ratio of the high level in one cycle of the drive signal, K is the proportionality coefficient, that is, the flow rate change corresponding to the change in the unit duty cycle, and D min is the minimum effective duty cycle, that is, the minimum duty cycle threshold for opening the solenoid valve.

[0057] Control the opening of the valve by adjusting the duty cycle of the proportional solenoid valve drive signal, so as to realize the adjustment of the fluid flow rate.

[0058] When the coaxial reverse centrifugal atomizing nozzle with adjustable flow rate of the present invention is in use, the mixed and prepared liquid medicine is stored in the liquid supply tank of the plant protection unmanned aerial vehicle. The operator sets the rotation speed of the brushless motor 4 and the flow rate of the proportional solenoid valve 1 according to the specific requirements of the spraying operation. The brushless motor 4 transmits the power to the atomizing assembly, driving the upper atomizing disk 16 and the lower atomizing disk 17 to rotate at high speed. Figure 7 As the overall working flow chart of the atomizing nozzle of the plant protection unmanned aerial vehicle, the system initializes the settings of the brushless motor speed and the proportional solenoid valve flow rate. After the controller receives the spraying instruction, the controller sends a PWM signal to the motor driver and at the same time opens the proportional solenoid valve. While the brushless motor drives the atomizing disk to rotate, the liquid medicine is supplied to the atomizing disk, realizing the precise control of the brushless motor speed and the precise control of the liquid supply amount of the nozzle according to the above process; when the spraying operation is completed, after the controller receives the stop spraying instruction, it closes the proportional solenoid valve, and after a delay of 3 seconds, controls the brushless motor to stop rotating through the brushless motor driver, so that the atomizing disk stops rotating and the spraying operation ends, ensuring that all the liquid medicine in the nozzle has been discharged, avoiding the outflow of the liquid medicine that has not been atomized and causing environmental pollution.

Claims

1. A coaxial inverted centrifugal atomizing nozzle with adjustable flow rate, characterized in that: It comprises a protective shell, a liquid inlet funnel (7), an upper atomizing disk (16) and a flow regulating unit; A proportional solenoid valve (1) and a motor are fixed in the protective shell, a liquid inlet funnel (7) is fixedly connected to the bottom of the protective shell, a flow regulating unit is arranged on the plant protection UAV, a liquid inlet pipe (101) of the proportional solenoid valve (1) is connected to the outlet of the liquid tank of the plant protection UAV, a liquid outlet pipe (102) of the proportional solenoid valve (1) is connected to the liquid inlet of the liquid inlet funnel (7), the flow regulating unit is connected to the proportional solenoid valve (1), and the flow regulating unit is used to control the valve core opening of the proportional solenoid valve (1); The upper atomizing disk (16) is fixed to the bottom of the liquid inlet funnel (7), the lower atomizing disk (17) is arranged in the inner cavity at the bottom of the upper atomizing disk (16), the gap between the lower atomizing disk (17) and the upper atomizing disk (16) forms the spraying port of the centrifugal atomizing nozzle, the upper atomizing disk (16) is provided with a planetary gear mechanism, the output shaft of the motor passes through the liquid inlet funnel (7) and the driving gear (10) in the planetary gear mechanism in sequence and is then fixed to the lower atomizing disk (17), the planetary gear mechanism being used to drive the upper atomizing disk (16) to rotate in the opposite direction to the output shaft of the motor.

2. The flow-adjustable coaxial inverted centrifugal atomizing nozzle according to claim 1, characterized in that: The flow regulating unit includes a controller, a flow sensor and a solenoid valve driver. The flow sensor is arranged on the spray rod of the plant protection UAV. The controller is used to collect the flow feedback value of the flow sensor in real time, and then output a PWM control signal to the solenoid valve driver. The solenoid valve driver is used to analyze the PWM control signal, control the average voltage applied to the proportional solenoid valve (1) through the duty cycle, and control the valve core opening of the proportional solenoid valve (1).

3. The flow-adjustable coaxial inverted centrifugal atomizing nozzle according to claim 2, characterized in that: The protective shell comprises a first protective shell (2) and a second protective shell (3) of symmetrical structure, the first protective shell (2) and the second protective shell (3) being aligned and spliced ​​with each other to form the protective shell, the end cover of the proportional solenoid valve (1) being adapted to the inner wall of the upper half of the protective shell, the center of the front and rear surfaces of the end cover of the proportional solenoid valve (1) being respectively provided with a positioning pin, a pin hole being provided at a position of the upper half of the protective shell corresponding to the positioning pin, the end cover of the proportional solenoid valve (1) being fitted in the cavity of the upper half of the protective shell, and the positioning pin being interference fit with the corresponding pin hole; The liquid inlet pipe (101) and the liquid outlet pipe (102) are arranged outside the protective shell through an opening in the upper half of the protective shell, and the motor is a brushless motor (4), which is fixed in the lower half of the protective shell.

4. The flow-adjustable coaxial counter-rotating centrifugal atomizing nozzle according to claim 3, characterized in that: It also includes a motor cover (6), the top of the motor cover (6) is provided with a step along the circumferential direction, a cylindrical boss corresponding to the vertical section of the step is fixedly inserted into the opening at the lower end of the lower half of the protective shell, and the liquid inlet funnel (7) is fixedly connected to the lower half of the protective shell through the motor cover (6); A circular groove communicating with the outside is provided at the center of the top of the motor cover (6), and a motor shaft hole communicating with the inner cavity of the motor cover (6) is provided at the center of the groove. Four bolt holes are evenly provided at the top of the motor cover (6) and located outside the groove along the circumferential direction. After the output shaft of the brushless motor (4) passes through the motor shaft hole, it passes through the liquid inlet funnel (7) and the driving gear (10) in the planetary gear mechanism in sequence. After the connecting plate at the bottom of the housing of the brushless motor (4) contacts the top of the motor cover (6), the through holes at the four corners of the connecting plate are aligned with each bolt hole respectively. Four bolts (5) pass through the through holes at the four corners of the connecting plate respectively, and the ends are installed in the bolt holes at the top of the motor cover (6).

5. The flow-adjustable coaxial counter-rotating centrifugal atomizing nozzle according to claim 4, characterized in that: The liquid inlet funnel (7) is a cylindrical groove having the same outer diameter as the motor cover (6); a step is provided at the bottom of the motor cover (6) along the circumferential direction; a cylindrical boss corresponding to the vertical section of the step is fitted with the inner wall of the liquid inlet funnel (7); the boss is provided with four symmetrically distributed and flush cylindrical protrusions along the circumferential direction; L-shaped through grooves are provided at positions corresponding to the cylindrical protrusions on the upper side of the liquid inlet funnel (7); the horizontal sections of the through grooves are distributed in the same direction; and the inner diameter of the through grooves is the same as that of the cylindrical protrusions; The liquid inlet pipe of the liquid inlet funnel (7) has an arc of π / 12, and the upper end of the liquid inlet pipe is the liquid inlet port of the liquid inlet funnel (7).

6. The flow-adjustable coaxial inverted centrifugal atomizing nozzle according to claim 5, characterized in that: The upper atomizing disk (16) comprises an atomizing disk body and a convex ring extending vertically in the radial direction of the atomizing disk body, the convex ring being fixed to the bottom of the liquid inlet funnel (7) in a horizontal state, and a planetary gear mechanism is installed in the convex ring of the upper atomizing disk (16); The planetary gear mechanism comprises an inner ring gear (15), a driving gear (10), and three first planetary gears (12), a second planetary gear (13), and a third planetary gear (14) of the same structure and size. The inner ring gear (15) is fixed in a horizontal state on the inner side wall of the convex ring of the upper atomizing disk (16). The two are interference fit. The center of the driving gear (10) coincides with the center of the inner ring gear (15). The output shaft of the brushless motor (4) is fixed and passes through the driving gear (10). The center of the output shaft of the brushless motor (4) coincides with the center of the driving gear (10). The first planetary gear (12), the second planetary gear (13), and the third planetary gear (14) are evenly distributed along the circumferential direction of the driving gear (10) and mesh with the gear teeth of the driving gear (10) and the inner ring gear (15).

7. The flow-adjustable coaxial inverted centrifugal atomizing nozzle according to claim 6, characterized in that: The first planetary gear (12), the second planetary gear (13) and the third planetary gear (14) are each fixedly sleeved on a transmission bearing (11), and the three transmission bearings (11) are each fixedly sleeved on a core shaft (9), and each transmission bearing (11) is connected to the liquid inlet funnel (7) via a corresponding core shaft (9), and the upper end of the core shaft (9) is fixed to the bottom surface of the liquid inlet funnel (7); A support bearing (8) is provided between the convex ring of the upper atomizing disk (16) and the inner wall of the liquid inlet funnel (7), and the outer ring of the support bearing (8) is interference-fitted with the inner wall of the liquid inlet funnel (7).

8. The flow-adjustable coaxial inverted centrifugal atomizing nozzle according to claim 6, characterized in that: The bottoms of the lower atomizing disk (17) and the upper atomizing disk (16) are flush and their centers overlap; a sleeve perpendicular to the atomizing disk body is provided at the center of the lower atomizing disk (17); the end of the output shaft of the brushless motor (4) is fixedly inserted into the sleeve, and the two are interference fit; The atomizing disk body of the upper atomizing disk (16) is a truncated cone-shaped structure, the lower end opening is larger than the upper end opening, and the inner wall of the atomizing disk body is evenly provided with 50 to 70 radially distributed rectangular atomizing teeth along the circumferential direction, and the rectangular atomizing teeth extend out of the outer edge and the inner edge of the atomizing disk body; The atomizer disc body of the lower atomizer disc (17) is evenly provided with 50 to 70 guide grooves along the circumferential direction, the inner side of each guide groove is away from the sleeve, the inner sides of all the guide grooves form a circle, the outer side of each guide groove extends to the edge of the atomizer disc body, and each guide groove is distributed in an arc shape.

9. A method for using the flow-adjustable coaxial counter-rotating centrifugal atomizing nozzle according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1, the motor transmits power to the lower atomizing disk (17), so that the lower atomizing disk (17) rotates forward; The motor transmits power to the driving gear (10), and the planetary gear mechanism realizes the reverse rotation of the upper atomizing disk (16); S2, after receiving the target flow command signal from the host computer, the flow regulating unit controls the valve core opening of the proportional solenoid valve (1); S3, under the control of the proportional solenoid valve (1), the liquid medicine is supplied to the liquid inlet funnel (7), the liquid medicine flows through the liquid inlet funnel (7) to the interior of the lower atomizing disk (17) for primary atomization, then enters the interior of the upper atomizing disk (16) for secondary atomization, and then is sprayed out from the gap between the lower atomizing disk (17) and the upper atomizing disk (16) under the action of centrifugal force and physical crushing of the lower atomizing disk (17) and the upper atomizing disk (16).

10. The method for using the flow-adjustable coaxial counter-rotating centrifugal atomizing nozzle according to claim 9, characterized in that: After receiving the target flow command signal from the host computer, the controller in S2 collects the flow feedback value of the flow sensor in real time, and executes the flow loop PID control algorithm of the following process to obtain the duty cycle of the proportional solenoid valve drive signal, and then outputs a PWM control signal to the solenoid valve driver according to the duty cycle of the proportional solenoid valve drive signal. The solenoid valve driver analyzes the PWM control signal and controls the average voltage applied to the proportional solenoid valve (1) through the duty cycle, thereby controlling the valve core opening of the proportional solenoid valve (1): The controller obtains the actual flow rate and expected flow rate based on the flow feedback value, and the flow deviation e 1 is: in, q is the expected flow rate of the nozzle, q 1 is the actual flow rate of the nozzle; Apply the following PID control formula to calculate the adjustment signal u 1 is: in, K p 1 is the proportionality coefficient, K i 1 is the integration coefficient, K d 1 is the differential coefficient, T i 1 is the integration time; Based on the adjustment signal u 1 and flow deviation e 1Get the flow adjustment value q 0: Based on the proportional solenoid valve drive signal PWM duty cycle and flow adjustment value as shown below q 0 determines the duty cycle of the proportional solenoid valve drive signal: ； Where D is the duty cycle of the proportional solenoid valve drive signal, K is the proportional coefficient, and D min is the minimum effective duty cycle.

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