Medicament distribution valve and distribution method thereof

Abstract

The invention discloses a medicament dispensing valve and a dispensing method thereof. According to the pre-tightening structure, the pre-tightening bolt and the frame form a screw pair, the pre-tightening bolt and the second pre-tightening block form a rotating pair, the second pre-tightening block and the frame form a sliding pair parallel to the pre-tightening bolt, the first pre-tightening block and the frame form a sliding pair in the vertical direction, and the inclined face of the lower end of the second pre-tightening block is attached to the inclined face of the upper end of the first pre-tightening block to form a sliding friction pair. A cantilever in the displacement amplification mechanism is connected with a frame through a flexible hinge, the upper end of a piezoelectric stack is detachably fixed to a first pre-tightening block, and a first ball head integrally formed at the lower end of the piezoelectric stack is embedded into a hemispherical groove formed in the end, close to the flexible hinge, of the cantilever. In the nozzle assembly structure, a second ball integrally formed at the upper end of a valve rod and a stepped hole formed in the end, away from a flexible hinge, of a cantilever form a ball hinge. The device has better medicament distribution consistency, and can realize accurate adjustment of the output displacement of the valve rod when the medicament viscosity is different or the medicament drop volume distributed at a single time is different.

Description

Technical Field

[0001] The invention belongs to the technical field of medicine dispensing valves, and in particular relates to a high-stability small-amount medicine dispensing valve and a dispensing method thereof. Background Art

[0002] Chemical pesticides are efficient and economical, and are the main means of preventing and controlling pests and diseases. However, my country consumes more than 300,000 tons of pesticides each year, and the effective utilization rate is only 35%. The inefficient application of pesticides has seriously threatened the living environment and health of human beings, and has become a bottleneck problem in the process of plant protection operations. At present, the widely used plant protection spraying machinery is manually pre-mixed and then poured into the plant protection machine medicine box for quantitative spraying. The operation mode of pre-mixed quantitative spraying not only endangers human health and cannot achieve spraying on demand, but also has the phenomenon of dumping and waste of residual liquid medicine and pollution, which does not meet the requirements of sustainable agricultural development.

[0003] The variable spray technology sets up the medicine box and water tank independently. During operation, the mixing control system adjusts the medicine-water ratio (mixing ratio) as needed and completes the online mixing of medicine and water simultaneously. However, different crops, different pesticides, the same crop in different growth periods, and the sprayer at different operating speeds have different mixing ratios (1:100-1:2000), and real-time changes need to be made according to the working conditions. In the complex interference environment of agriculture, how to achieve stable online small-amount precise distribution of pesticides through the drug supply unit is the bottleneck problem of the current variable spray technology. Piezoelectric stacks have the characteristics of fast response, high resolution, and low power consumption, and are beginning to be used in online drug supply and distribution technology. For example, the inventions with patent numbers CN114667984A, CN217207870U and CN218895034U respectively design a drug supply and mixing dispensing valve driven by a piezoelectric stack. However, the piezoelectric stacks are directly pre-tightened by screws, which are easily disturbed by the field environment and the vibration of the piezoelectric stack and become loose, thereby affecting the output of the piezoelectric stack force and displacement. In addition, the pre-tightening force adjustment resolution is small, and overshoot or insufficient pre-tightening force is prone to occur, thereby affecting the service life of the piezoelectric stack or the consistency of drug distribution of the drug supply unit. Moreover, the displacement amplification mechanism in these inventions They all adopt a rigid amplification mechanism, and there are problems of mutual wear and clearance between the various parts; in addition, the valve stem and displacement amplification mechanism used in the existing drug supply and mixing distribution valve cannot avoid the influence of horizontal lateral force on the valve stem in a complex agricultural environment, thereby affecting the consistency of drug distribution; in addition, the cantilever and the valve stem in the existing drug supply and mixing distribution valve are kept in contact by a spring, but when dispensing high-viscosity drugs, the cantilever and the valve stem are prone to separation and collision, affecting the flow stability of the drug, affecting the consistency of drug distribution, and even failing to distribute normally. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art and to provide a small and micro-amount medicine dispensing valve with high stability and a dispensing method thereof.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] The invention discloses a medicine dispensing valve, which comprises a pre-tightening structure, a displacement amplifying mechanism, a nozzle assembly structure, a displacement measuring structure and a frame.

[0007] The pre-tightening structure includes a pre-tightening bolt, a pre-tightening block 1 and a pre-tightening block 2; the horizontally arranged pre-tightening bolt and the threaded hole 1 opened on the frame form a spiral pair; the pre-tightening block 1 and the frame form a sliding pair in the vertical direction; the pre-tightening block 2 and the frame form a sliding pair parallel to the pre-tightening bolt, and form a rotating pair with the pre-tightening bolt, and the inclined surface at the lower end of the pre-tightening block 2 fits the inclined surface at the upper end of the pre-tightening block 1 to form a sliding friction pair. The displacement amplification mechanism is arranged below the pre-tightening block 1, including a cantilever, a flexible hinge and a piezoelectric stack; the two ends of the flexible hinge are connected to the frame and the cantilever, and the cantilever, the flexible hinge and the frame are integrally formed; the upper end of the vertically arranged piezoelectric stack is detachably fixed to the pre-tightening block 1, and the lower end is provided with an integrally formed ball head 1, and the ball head 1 is embedded in a hemispherical groove opened at one end of the cantilever near the flexible hinge.

[0008] The nozzle assembly structure includes a limit bolt, a valve stem, a nozzle body, a nozzle cap, a guide ring, a nozzle and a guide member. A vertically arranged step hole is provided at one end of the cantilever away from the flexible hinge, the valve stem passes through the step hole, and the ball head 2 integrally formed at the upper end of the valve stem and the middle of the step hole form a ball hinge; the limit bolt is connected to the upper end of the step hole by a thread, and the top of the ball head 2 contacts the bottom end of the limit bolt, and there is a gap between the position below the ball head 2 on the valve stem and the inner wall of the lower end of the step hole; the vertically arranged guide member is provided directly below the step hole, fixed on the frame, and connected to the cantilever through a restoring spring, and a guide hole coaxially arranged with the step hole is provided on the guide member.

[0009] The nozzle body is fixed on the frame, and a through hole is provided on the nozzle body directly below the guide member and is coaxially arranged with the step hole, and a flow channel is provided horizontally and connected with the middle of the through hole; the nozzle is placed in a cylindrical groove provided at the bottom end of the guide ring, and the lower part of the nozzle passes through the boss formed integrally at the bottom end of the nozzle cap, the nozzle cap is sleeved on the outside of the guide ring, and the internal thread provided at the lower end of the nozzle cap is connected with the external thread provided at the lower end of the guide ring, and the nozzle is axially limited by the boss and the cylindrical groove; the upper end of the guide ring is embedded in the lower end of the through hole, and the internal thread provided at the upper end of the nozzle cap is threadedly connected to the nozzle body; the guide ring is provided with a The through hole is coaxially arranged with a center hole, a spray chamber connected to the cylindrical groove is provided at the upper end of the nozzle, and a vertical hole connected to the spray chamber is provided at the lower end; the lower end of the valve stem passes through the guide hole of the guide member and the through hole of the nozzle body in turn, forms a sliding pair with the guide hole, and penetrates into the center hole and the cylindrical groove, and the lower end of the valve stem is provided with an integrally formed hemispherical body; a universal plug is provided at the upper end of the through hole, and the inner and outer rings of the universal plug are respectively interference fit with the valve stem and the through hole, an O-type sealing ring 1 is provided between the cylindrical groove and the nozzle, and a plurality of O-type sealing rings 2 arranged at upper and lower intervals are provided at the lower end of the through hole, and each O-type sealing ring 2 is embedded in an annular groove provided on the outer side of the guide ring. The displacement measurement structure includes a sensor bracket and an eddy current sensor, the sensor bracket is fixed on the frame, and the eddy current sensor is vertically fixed on the sensor bracket and is located directly above the limit bolt.

[0010] Preferably, the pre-tightening block 1 and a dovetail guide groove provided on the frame form a sliding pair perpendicular to the pre-tightening bolt.

[0011] Preferably, the second pre-tightening block and a dovetail guide rail integrally formed on the frame form a sliding pair parallel to the pre-tightening bolt.

[0012] Preferably, the guide member is connected to the second threaded hole provided on the frame through threads.

[0013] Preferably, the nozzle body and the frame are fixed by fixing bolts.

[0014] Preferably, the inclined surfaces of the pre-tightening block 1 and the pre-tightening block 2 are roughened.

[0015] The present invention provides a dispensing method of a medicine dispensing valve, which is specifically as follows:

[0016] The inlet channel of the flow channel is connected to the medicine box through the medicine liquid pipeline; initially, the driving voltage of the piezoelectric stack is maintained at the preset level one, at which time the nozzle is opened, and under the action of the medicine supply pressure, the medicine flows through the flow channel, the through hole, the center hole, the cylindrical groove and the spray cavity to the vertical hole; when the driving voltage of the piezoelectric stack is applied to the preset level two, wherein the preset level two is greater than the preset level one, the piezoelectric stack is extended and pushes the cantilever to rotate downward, and the cantilever drives the valve stem to move downward until it hits the nozzle, the hemisphere is embedded in the spray cavity, and the vertical hole is blocked, so that the nozzle is closed, The medicine at the vertical hole gains kinetic energy under the movement of the valve stem, overcomes its own viscosity and surface tension, breaks and forms medicine drops that fall; then the piezoelectric stack maintains the preset level 2 for a preset time, and the medicine stops flowing out; finally, the driving voltage of the piezoelectric stack is returned to the preset level 1, the piezoelectric stack shrinks to its original state, and the cantilever rotates upward to its original position under the action of the flexible hinge and the restoring spring, and drives the valve stem to move upward to its original position, while negative pressure is formed in the spray chamber, and under the medicine supply pressure, the spray chamber is filled with surrounding medicine, waiting for the next cycle of medicine distribution.

[0017] Preferably, the preload force on the piezoelectric stack is adjusted before the piezoelectric stack works so that the preload force on the piezoelectric stack is a preset value. The adjustment process of the preload force of the piezoelectric stack is as follows: in the initial state, the cantilever and the flexible hinge are in a free horizontal state, the preload bolt is turned, and the preload bolt drives the piezoelectric stack to descend through preload block 2 and preload block 1. The piezoelectric stack drives the cantilever to rotate downward, and the flexible hinge is deformed until the preload block 1 descends to a preset height, so that the preload force on the piezoelectric stack is adjusted to the preset value, thereby completing the adjustment of the preload force of the piezoelectric stack.

[0018] More preferably, the lead of the pre-tightening bolt is p, the inclination angle of the inclined plane is α, and α∈(0,90°), when the pre-tightening bolt pushes the piezoelectric stack downward through the pre-tightening block 1 and the pre-tightening block 2, the center of the flexible hinge is the rotation center of the cantilever, and the distance from the rotation center to the point where the output force of the piezoelectric stack acts is L p , the distance between the center of the valve stem and the center of rotation is L, and the rotation stiffness of the flexible hinge is k hinge When the preload bolt is screwed into the angle θ and the piezoelectric stack moves downward by a displacement Δx, the preload force F of the piezoelectric stack is p for:

[0019]

[0020] In the formula, F s To restore the pressure exerted by the spring on the cantilever, k s is the stiffness of the recovery spring and β is the rotation angle of the flexible hinge.

[0021] Preferably, when the viscosity of the medicine is different or the volume of the medicine droplet dispensed at a single time is different, the output displacement of the valve stem is different, and the adjustment process of the output displacement of the valve stem is:

[0022] First, the driving voltage input to the piezoelectric stack and the output displacement of the valve stem are calibrated: After the preload force of the piezoelectric stack is adjusted, the output displacement of the valve stem is recorded as s 0 , assuming the maximum driving voltage of the piezoelectric stack is V max Under this preload condition, the piezoelectric stack is intermittently loaded with a driving voltage of V max , and the voltage interval of each loading voltage is V interl , record the valve stem output displacement corresponding to each driving voltage, and repeat it many times, calculate the average of each output displacement corresponding to the same driving voltage, and use each average value to represent the output displacement corresponding to the corresponding driving voltage. Perform multi-point calibration on the relationship between the driving voltage input by the piezoelectric stack and the output displacement of the valve stem and fit the relationship between the two; then rotate the nozzle cap downward so that there is a gap between the valve stem and the vertical hole, and apply a driving voltage to the piezoelectric stack to V max The piezoelectric stack drives the valve stem to move downward to the lowest position through the cantilever; then the nozzle cap is screwed upward, and when the nozzle contacts the hemisphere, the nozzle cap is stopped; the stroke s of the valve stem is determined according to the viscosity of the drug or the volume of the drug droplet dispensed in a single time, and the driving voltage V of the piezoelectric stack input is obtained from the relationship between the driving voltage input by the piezoelectric stack and the output displacement of the valve stem. 1 , so that the preset level of the piezoelectric stack input is V max -V 1 , then when the driving voltage input to the piezoelectric stack is the preset level, the output displacement of the valve stem is s max -s, and the preset level of the piezoelectric stack input is always V max .

[0023] The present invention has the following beneficial effects:

[0024] 1. The present invention has good consistency in medicine distribution; specifically, the present invention has a high pre-tightening force adjustment resolution, and makes the piezoelectric stack less affected by vibration. The pre-tightening structure of the present invention adopts a pre-tightening block 1 and a pre-tightening block 2 with an inclined mating surface. The pre-tightening bolt pushes the pre-tightening block 2 to translate, and the pre-tightening block 2 pushes the pre-tightening block 1 and the piezoelectric stack to descend. The piezoelectric stack drives the cantilever to rotate downward, and the flexible hinge is deformed, thereby realizing the pre-tightening of the piezoelectric stack. Compared with the existing method of pre-tightening by directly pushing the piezoelectric stack through the coaxial screw, the present invention has a higher adjustment resolution and reduces the inclination angle of the inclined surface. The adjustment resolution can be further increased, and the preload force can be more conveniently set within a lower range. In the present invention, the piezoelectric stack and the cantilever are matched with a spherical surface, which reduces the lateral force on the piezoelectric stack, improves the stability of the piezoelectric stack, ensures the stable output force and displacement of the piezoelectric stack, ensures the consistency of drug distribution, and improves the service life of the piezoelectric stack. In addition, the matching inclined surfaces of the preload block 1 and the preload block 2 are roughened, so that the preload block 1 and the preload block 2 have a self-locking effect under the action of the piezoelectric stack force, and the direction of the preload bolt force is mutually opposite to the direction of the vibration force of the piezoelectric stack. Orthogonal, so that the vibration force generated by the piezoelectric stack on each pre-tightening block will not cause the loosening of the pre-tightening structure, thereby ensuring the stability of the pre-tightening structure, further ensuring the stable output force and displacement of the piezoelectric stack, and ensuring the consistency of drug distribution; in the displacement amplification mechanism of the present invention, the cantilever is connected to the frame through a flexible hinge, and a flexible displacement amplification mechanism is adopted, and the cantilever, flexible hinge and frame are integrally formed, with fewer parts, no motion pair clearance and no wear, which is conducive to improving the consistency of movement, thereby improving the consistency of drug distribution; further, in the present invention, both ends of the valve stem are spherical, and the upper end of the valve stem is The cantilever is connected by a ball hinge, so that the valve stem is always subjected to vertical forces only, avoiding the valve stem from tilting due to the horizontal lateral force transmitted by the cantilever, improving the concentricity between the hemisphere at the lower end of the valve stem and the vertical hole of the nozzle, and the cantilever drives the valve stem to maintain synchronous movement when moving. Compared with the existing structure in which the cantilever and the valve stem are connected by a spring, the valve stem is more likely to obtain a greater speed and kinetic energy, which is beneficial for dispensing high-viscosity medicines, and avoiding the separation or collision between the valve stem and the cantilever, ensuring the stability of the flow of medicine in the spray chamber, and further ensuring the consistency of medicine distribution.

[0025] 2. The present invention can realize accurate adjustment of the valve stem output displacement required for different drug viscosities or different volumes of drug droplets dispensed at a single time; specifically, in the present invention, the relationship between the piezoelectric stack driving voltage and the valve stem output displacement is calibrated and fitted, and in the present invention, the nozzle cap, the guide ring and the nozzle are relatively stationary, and the guide ring and the nozzle are driven to move by twisting the nozzle cap, so that the nozzle is located at the lowest position of the valve stem when the piezoelectric stack driving voltage is maximum, and then the required valve stem stroke is determined according to the drug viscosity or the volume of drug droplets dispensed at a single time, and the preset level one of the piezoelectric stack input is determined according to the required valve stem stroke, so that the piezoelectric stack driving voltage is initially set to the preset level one, thereby realizing accurate adjustment of the valve stem output displacement required for different drug viscosities or different volumes of drug droplets dispensed at a single time, and the adjustment process is simple, the effect is reliable, and the dispensing capacity of the dispensing valve is improved.

[0026] 3. The sealing performance of the nozzle assembly structure in the present invention is good. In the nozzle assembly structure, a plug is provided between the upper end of the through hole of the nozzle body and the valve stem to prevent the leakage of the agent from the upper end of the through hole. A plurality of O-rings are provided between the lower end of the through hole and the guide ring to prevent the leakage of the agent from the gap between the lower end of the through hole and the guide ring. An O-ring is provided between the nozzle and the cylindrical groove opened on the guide ring to prevent the leakage of the agent nozzle and the gap between the guide ring. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0028] Figure 2 It is a partial cross-sectional view of the present invention;

[0029] Figure 3 for Figure 1 The structural diagram of part A in the figure;

[0030] Figure 4 for Figure 3 Sectional view of AA in the middle;

[0031] Figure 5 for Figure 3 Cross-sectional view of the middle BB;

[0032] Figure 6 for Figure 2 A magnified view of part B;

[0033] Figure 7 for Figure 2 Enlarged view of part C;

[0034] Figure 8 A schematic diagram of the driving voltage of the piezoelectric stack when the present invention is working;

[0035] Fig. 9 This is a simplified diagram of force analysis when adjusting the preload force of the piezoelectric stack according to the present invention. DETAILED DESCRIPTION

[0036] The present invention is further described below in conjunction with the accompanying drawings.

[0037] like Figure 1 and Figure 2 As shown, a medicine dispensing valve of the present invention includes a pre-tightening structure, a displacement amplifying mechanism, a nozzle assembly structure, a displacement measuring structure and a frame 5.

[0038] like Figure 2 , Figure 3 , Figure 4 and Figure 5 As shown, the pre-tightening structure includes a pre-tightening bolt 1, a pre-tightening block 17 and a pre-tightening block 19; the horizontally arranged pre-tightening bolt 1 and a threaded hole 1 opened on the frame 5 form a spiral pair; the pre-tightening block 17 and a dovetail guide groove 18 opened on the frame 5 form a sliding pair in the vertical direction; the pre-tightening block 19 and the dovetail guide rail 3 integrally formed on the frame 5 form a sliding pair parallel to the pre-tightening bolt 1, and form a rotating pair with the pre-tightening bolt 1, and the inclined surface at the upper end of the pre-tightening block 17 fits with the inclined surface at the lower end of the pre-tightening block 19 to form a sliding friction pair. The displacement amplification mechanism is arranged below the preload block 17, and includes a cantilever 14, a flexible hinge 15 and a piezoelectric stack 16; both ends of the flexible hinge 15 are connected to the frame 5 and the cantilever 14, and the cantilever 14, the flexible hinge 15 and the frame 5 are integrally formed to improve the consistency of movement; the upper end of the vertically arranged piezoelectric stack 16 is detachably fixed to the preload block 17, and an integrally formed ball head 1 is provided at the lower end, and the ball head 1 is embedded in a hemispherical groove opened at one end of the cantilever 14 near the flexible hinge 15. The ball head 1 and the cantilever 14 are spherically matched, which can reduce the lateral force on the piezoelectric stack 16 and improve the service life of the piezoelectric stack 16.

[0039] like Figure 2 , Figure 6 and Figure 7As shown, the nozzle assembly structure includes a limit bolt 7, a valve stem 8, a nozzle body 11, a guide member 20, a nozzle cap 21, a guide ring 22 and a nozzle 24. A vertically arranged step hole is provided at one end of the cantilever 14 away from the flexible hinge 15, and the valve stem 8 passes through the step hole, and the ball head 2 integrally formed at the upper end of the valve stem 8 forms a ball hinge with the middle part of the step hole, so as to prevent the horizontal lateral displacement generated by the cantilever 14 during the rotation process from affecting the valve stem 8, and to prevent the horizontal interference displacement generated by the environment from affecting the valve stem 8 through the cantilever 14; the limiting bolt 7 is threadedly connected to the upper end of the step hole, and the top of the ball head 2 contacts the bottom end of the limiting bolt 7, so as to prevent the valve stem 8 from having relative movement with the cantilever 14 in the vertical direction, and there is a gap between the position below the ball head 2 on the valve stem 8 and the inner wall of the lower end of the step hole, so as to prevent the valve stem 8 and the cantilever 14 from interfering with each other when the cantilever 14 moves; the vertically arranged guide member 20 is provided directly below the step hole, is threadedly connected to the threaded hole 2 opened on the frame 5, and is connected to the cantilever 14 through the restoring spring 9, and a guide hole coaxially arranged with the step hole is provided on the guide member 20.

[0040] The nozzle body 11 is fixed on the frame 5, and a through hole coaxially arranged with the step hole is provided on the nozzle body 11 directly below the guide member 20, and a flow channel 10 horizontally arranged and connected with the middle of the through hole is provided; the nozzle 24 is placed in the cylindrical groove provided at the bottom end of the guide ring 22, and the lower part of the nozzle 24 passes through the boss integrally formed at the bottom end of the nozzle cap 21, the nozzle cap 21 is sleeved on the outside of the guide ring 22, and the internal thread provided at the lower end of the nozzle cap 21 is connected with the external thread provided at the lower end of the guide ring 22, and the nozzle 24 is axially limited by the boss and the cylindrical groove; the upper end of the guide ring 22 is embedded in the lower end of the through hole, and the internal thread provided at the upper end of the nozzle cap 21 is connected with the nozzle body 11 by threading; the guide ring 22 is located at the top of the cylindrical groove and is provided with a center hole coaxially arranged with the through hole, the upper end of the nozzle 24 is provided with a spray chamber 23 connected with the cylindrical groove, and the lower end is provided with a vertical hole connected with the spray chamber 23; The lower end of the valve stem 8 passes through the guide hole of the guide member 20 and the through hole of the nozzle body 11 in sequence, forming a sliding pair with the guide hole, and penetrates into the center hole and the cylindrical groove, and the lower end of the valve stem 8 is provided with an integrally formed hemispherical body; the upper end of the through hole is provided with a flood plug 27, and the inner ring and outer ring of the flood plug 27 are respectively interference fit with the valve stem 8 and the through hole, and the flood plug 27 is used to prevent the medicine in the flow channel 10 from leaking upward, and an O-ring 1 25 is provided between the cylindrical groove and the nozzle 24, and the O-ring 1 25 is used to prevent the medicine from leaking outward through the contact between the nozzle 24 and the guide ring 22, and the lower end of the through hole is provided with a plurality of O-rings 26 arranged at upper and lower intervals, and each O-ring 26 is embedded in an annular groove opened on the outer side of the guide ring 22, and each O-ring 26 is used to prevent the medicine from leaking outward through the contact between the guide ring 22 and the nozzle body 11, affecting the normal medicine distribution and environmental pollution. The displacement measurement structure includes a sensor bracket 4 and an eddy current sensor 6 . The sensor bracket 4 is fixed on a frame 5 . The eddy current sensor 6 is vertically fixed on the sensor bracket 4 and is located directly above a limiting bolt 7 .

[0041] As a preferred embodiment, a rectangular groove is formed at the bottom end of the preload block 17, and the piezoelectric stack 16 is embedded in the rectangular groove and has an interference fit with the rectangular groove.

[0042] As a preferred embodiment, the nozzle body 11 and the frame 5 are fixed by fixing bolts 12 .

[0043] As a preferred embodiment, the flow channel 10 passes through the through hole, and one end of the flow channel 10 is an inlet channel, and the other end is fixed with a plug 13, and the plug 13 prevents the medicine in the flow channel 10 from leaking.

[0044] As a preferred embodiment, a connection hole group 2 is provided on the frame 5. The connection hole group 2 consists of a plurality of connection holes arranged at intervals and is used for fixing to the sprayer by connecting bolts.

[0045] like Figure 8As shown, a dispensing method of a medicine dispensing valve of the present invention is as follows:

[0046] The inlet channel of the flow channel 10 is connected to the medicine box through the medicine liquid pipeline; the driving voltage of the piezoelectric stack 16 is initially maintained at a preset level of one (corresponding to Figure 8 Medium 0-t 1 The nozzle 24 is opened at this time, and under the action of the medicine supply pressure, the medicine flows through the flow channel 10, the through hole, the center hole, the cylindrical groove and the spray cavity 23 to the vertical hole; the driving voltage of the piezoelectric stack 16 is applied to the preset level 2 (corresponding to Figure 8 Medium 1 -t 2 When the preset level 2 is greater than the preset level 1, the piezoelectric stack 16 quickly extends and pushes the cantilever 14 to rotate downward. The cantilever 14 drives the valve stem 8 to move downward until it hits the nozzle 24. The hemispherical body is embedded in the spray cavity 23 and blocks the vertical hole, so that the nozzle 24 is closed. The medicine at the vertical hole obtains enough kinetic energy to overcome its own viscosity and surface tension and break to form medicine drops that fall and mix with the clean water (not shown) flowing under the nozzle 24. Then, the piezoelectric stack 16 maintains the preset level 2 (corresponding to the preset level 1) for a preset time. Figure 8 Medium 2 -t 4 Finally, the driving voltage of the piezoelectric stack is returned to the preset level (corresponding to Figure 8 Medium 4 -t 5 In the above stage, the piezoelectric stack 16 shrinks rapidly to its original shape, and the cantilever 14 rotates upward to its original position under the action of the flexible hinge 15 and the restoring spring 9, and drives the valve stem 8 to move upward to its original position. At the same time, negative pressure is formed in the spray chamber 23. Under the medicine supply pressure, the spray chamber 23 is quickly filled with the surrounding medicine, waiting for the next cycle of medicine distribution. Among them, the nozzle 24 should maintain a certain distance from the clean water flow channel to avoid the negative pressure formed in the spray chamber 23 when the valve stem 8 rises, which will suck in clean water and affect the actual medicine-water ratio.

[0047] Among them, the preload force on the piezoelectric stack 16 is adjusted before the piezoelectric stack 16 works, so that the preload force on the piezoelectric stack 16 is a preset value, and the adjustment process of the preload force of the piezoelectric stack 16 is as follows: in the initial state, the cantilever 14 and the flexible hinge 15 are in a free horizontal state, and the preload bolt 1 is turned. The preload bolt 1 drives the piezoelectric stack to descend through the preload block 2 19 and the preload block 1 17, and the piezoelectric stack drives the cantilever to rotate downward, and the flexible hinge 15 is deformed until the preload block 1 descends to a preset height, so that the preload force on the piezoelectric stack is adjusted to the preset value, thereby completing the adjustment of the preload force of the piezoelectric stack.

[0048] The preload force of the piezoelectric stack 16 is positively correlated with the height of the descending preload block 1 (i.e., the displacement of the piezoelectric stack 16 moving downward). Assuming that the lead of the preload bolt 1 is p, the inclination angle of the inclined plane of the preload block 17 is α, and α∈(0,90°), when the preload bolt 1 pushes the piezoelectric stack 16 downward through the preload block 17 and the preload block 2 19, only the flexible hinge 15 undergoes rotational deformation. The structures of the preload bolt 1, the preload block 17, the preload block 2 19 and the piezoelectric stack 16 are all rigid bodies and do not undergo deformation. The center of the flexible hinge 15 is the rotation center of the cantilever 14, as shown in FIG. Fig. 9 As shown, the distance between the rotation center and the output force acting point of the piezoelectric stack 16 is L p , the distance between the center of the valve stem 8 and the rotation center is L, and the rotation stiffness of the flexible hinge 15 is k hinge , the calculation formula of the flexible hinge stiffness can be used to solve that under the condition of small displacement, when the angle of the pre-tightening bolt 1 is θ and the displacement of the piezoelectric stack 16 moving downward is Δx, the pre-tightening force F of the piezoelectric stack 16 is p for:

[0049]

[0050] In the formula, F s To restore the pressure exerted by the spring 9 on the cantilever 14, k s To restore the stiffness of the spring 9 , β is the rotation angle of the flexible hinge 15 .

[0051] In addition, compared with the prior art method in which the pre-tightening bolt 1 coaxially directly pushes and squeezes the electric stack 16, assuming that the pre-tightening bolt 1 coaxially directly pushes and squeezes the electric stack 16 to generate a pre-tightening force of F p ', then the preload force of the piezoelectric stack 16 in the present invention is F p =F p 'tanα, under the action of the inclined plane, if the preload bolt 1 rotates a unit angle, the preload force F of the piezoelectric stack 16 p Decrease, F p The reduction amplitude can be adjusted by changing the inclination angle α. If the inclination angle α is smaller, the adjustment resolution of the piezoelectric stack 16 will be higher. The higher the adjustment resolution of the piezoelectric stack 16 in the preload structure, the more convenient it is to set the preload force at a lower value within the allowable range of the preload force, thereby ensuring the stable output of force and displacement, and enabling the piezoelectric stack to have a larger output displacement and a smaller flexible hinge pre-deformation, thereby improving the service life of the piezoelectric stack and the flexible hinge.

[0052] In addition, in order to improve the stability of the pre-tightening structure of the piezoelectric stack 16, the matching inclined surfaces of the pre-tightening block 17 and the pre-tightening block 2 19 are roughened so that the inclined surface angle α is smaller than the friction angle. At this time, the pre-tightening block 17 and the pre-tightening block 2 19 have a self-locking effect under the action of the piezoelectric stack force, and the force direction of the pre-tightening bolt 1 is orthogonal to the vibration force direction of the piezoelectric stack 16. Therefore, the vibration force generated by the piezoelectric stack 16 on the pre-tightening block 17 will not cause the loosening of the pre-tightening structure, thereby improving the stability of the pre-tightening structure and ensuring the stable output force and displacement of the piezoelectric stack.

[0053] Furthermore, the output displacement of the valve stem 8 has a great influence on the distribution of the medicine. For example, the larger the output displacement of the valve stem 8, the larger the volume of the medicine droplets distributed in a single time. The volume of the medicine droplets distributed in a single time can be distributed continuously by the medicine dispensing valve n times, and then measured by the average method. In addition, the viscosity of different medicines is different. Sometimes, in order to improve the adhesion of pesticides to crops, it is also necessary to add specific pesticide thickeners. The viscosity of the medicine increases, and a larger valve stem output displacement is required to complete normal distribution. The relationship between the valve stem output displacement and the viscosity or volume of the medicine can be obtained through preliminary tests. For medicines with different viscosities or different volumes of medicine drops distributed in a single time, the adjustment process of the valve stem output displacement is as follows:

[0054] Due to the limitation of manufacturing process, there are large errors in the parameters of piezoelectric stack, and there is a certain parasitic deformation when the flexible hinge 15 is deformed. There is a certain error in calculating the output displacement of the displacement valve stem. In order to accurately adjust the output displacement of the valve stem, the driving voltage input to the piezoelectric stack 16 and the output displacement of the valve stem 8 are calibrated. Since there is a certain nonlinearity between the driving voltage of the piezoelectric stack and the output displacement of the valve stem, in order to avoid the influence of nonlinear factors, the relationship between the driving voltage input to the piezoelectric stack 16 and the output displacement of the valve stem 8 is first calibrated at multiple points and the relationship between the two is fitted: After completing the adjustment of the preload of the piezoelectric stack 16, the output displacement of the valve stem 8 at this time is recorded as s 0 , assuming the maximum driving voltage of the piezoelectric stack is V max Under this preload condition, the piezoelectric stack 16 is intermittently loaded with a driving voltage to V max , and the voltage interval of each loading driving voltage is V interl , record the output displacement of the valve stem 8 corresponding to each driving voltage, and repeat it many times, calculate the average of each output displacement corresponding to the same driving voltage, and use each average to represent the output displacement corresponding to the corresponding driving voltage, perform multi-point calibration on the relationship between the driving voltage input by the piezoelectric stack 16 and the output displacement of the valve stem 8 and fit the relationship between the two, wherein the output displacement of the valve stem 8 is measured by the eddy current sensor 6; then rotate the nozzle cap 21 downward to ensure that there is enough space between the valve stem 8 and the vertical hole, and apply a driving voltage to the piezoelectric stack 16 to V max, the piezoelectric stack 16 drives the valve stem 8 to move downward to the lowest position through the cantilever 14; then the nozzle cap 21 is screwed upward, and when the nozzle 24 contacts the hemisphere, the nozzle cap 21 is stopped. At this time, the valve stem 8 has the maximum output displacement s max , the maximum stroke of valve stem 8 is s max -s 0 , and the valve stem 8 can effectively block the nozzle 24; finally, the stroke s of the valve stem 8 is determined according to the viscosity of the medicine or the volume of the medicine droplet dispensed in a single time, and the driving voltage V input by the piezoelectric stack 16 is obtained from the relationship between the driving voltage input by the piezoelectric stack 16 and the output displacement of the valve stem 8. 1 , so that the preset level of the piezoelectric stack 16 input is V max -V 1 , then when the driving voltage input by the piezoelectric stack 16 is the preset level 1, the output displacement of the valve stem 8 is s max -s, and the preset level 2 of the piezoelectric stack 16 input is always V max Among them, according to the different viscosity of the medicine or the volume of the medicine drop dispensed at a single time, the stroke s of the corresponding valve stem is obtained through preliminary experiments.

[0055] For different viscosity drugs or different single dispensed drop volumes, no matter how the output displacement of the valve stem 8 is set, there is no need to adjust the distance between the nozzle 24 and the valve stem 8 by screwing the nozzle cap 21, nor is there any need to re-adjust the preload force of the piezoelectric stack 16. It is only necessary to adjust the preset level of the piezoelectric stack 16 input in the range of 0-V by the above method. max Within the driving voltage range (specific value is V max -V 1 ), the valve stem 8 can hit the nozzle 24 and stably block the nozzle 24 when it outputs displacement, so as to avoid the valve stem 8 outputting displacement too small to hit and block the nozzle 24, causing the medicine to be unable to be distributed normally, and also avoid the valve stem 8 outputting displacement too large to damage the nozzle 24. The adjustment method is simple and reliable, and can accurately and real-timely adjust the output displacement of the valve stem 8, thereby enhancing the adaptability and improving the work efficiency.

Claims

1. A medicine dispensing valve, comprising a pre-tightening structure, a displacement amplification mechanism, a nozzle assembly structure and a frame, characterized in that: It also includes a displacement measuring structure; the pre-tightening structure includes a pre-tightening bolt, a pre-tightening block 1 and a pre-tightening block 2; the horizontally arranged pre-tightening bolt and a threaded hole 1 opened on the frame form a spiral pair; the pre-tightening block 1 and the frame form a sliding pair in the vertical direction; the pre-tightening block 2 and the frame form a sliding pair parallel to the pre-tightening bolt, and form a rotating pair with the pre-tightening bolt, and the inclined surface at the lower end of the pre-tightening block 2 fits with the inclined surface at the upper end of the pre-tightening block 1 to form a sliding friction pair; the displacement amplification mechanism is arranged below the pre-tightening block 1, and includes a cantilever, a flexible hinge and a piezoelectric stack; the two ends of the flexible hinge are connected to the frame and the cantilever, and the cantilever, the flexible hinge and the frame are integrally formed; the upper end of the vertically arranged piezoelectric stack is detachably fixed to the pre-tightening block 1, and the lower end is provided with an integrally formed ball head 1, and the ball head 1 is embedded in a hemispherical groove opened at one end of the cantilever near the flexible hinge; The nozzle assembly structure includes a limit bolt, a valve stem, a nozzle body, a nozzle cap, a guide ring, a nozzle and a guide member; a vertically arranged step hole is provided at one end of the cantilever away from the flexible hinge, the valve stem passes through the step hole, and the ball head 2 integrally formed at the upper end of the valve stem forms a ball hinge with the middle of the step hole; the limit bolt is connected to the upper end of the step hole by a thread, and the top of the ball head 2 contacts the bottom end of the limit bolt, and there is a gap between the position of the valve stem below the ball head 2 and the inner wall of the lower end of the step hole; the vertically arranged guide member is provided directly below the step hole, fixed on the frame, and connected to the cantilever through a restoring spring, and a guide hole coaxially arranged with the step hole is provided on the guide member; The nozzle body is fixed on the frame, and a through hole coaxially arranged with the step hole is provided on the nozzle body directly below the guide part, and a flow channel horizontally arranged and connected with the middle part of the through hole is provided; the nozzle is placed in a cylindrical groove provided at the bottom end of the guide ring, and the lower part of the nozzle passes through the boss integrally formed at the bottom end of the nozzle cap, the nozzle cap is sleeved on the outside of the guide ring, and the internal thread provided at the lower end of the nozzle cap is connected with the external thread provided at the lower end of the guide ring, and the nozzle is axially limited by the boss and the cylindrical groove; the upper end of the guide ring is embedded in the lower end of the through hole, and the internal thread provided at the upper end of the nozzle cap is connected with the nozzle body by thread; the guide ring is located at the top end of the cylindrical groove and has a center hole coaxially arranged with the through hole, a spray cavity connected with the cylindrical groove is provided at the upper end of the nozzle, and a nozzle cap is provided at the lower end. There is a vertical hole connected with the spray chamber; the lower end of the valve stem passes through the guide hole of the guide member and the through hole of the nozzle body in sequence, forms a sliding pair with the guide hole, and penetrates into the center hole and the cylindrical groove, and the lower end of the valve stem is provided with an integrally formed hemispherical body; the upper end of the through hole is provided with a universal plug, and the inner ring and outer ring of the universal plug are respectively interference fit with the valve stem and the through hole, an O-type sealing ring 1 is provided between the cylindrical groove and the nozzle, and the lower end of the through hole is provided with a plurality of O-type sealing rings 2 arranged with upper and lower spacings, and each O-type sealing ring 2 is embedded in an annular groove opened on the outer side of the guide ring; the displacement measurement structure includes a sensor bracket and an eddy current sensor, the sensor bracket is fixed on the frame, and the eddy current sensor is vertically fixed on the sensor bracket and is located directly above the limit bolt.

2. A medicine dispensing valve according to claim 1, characterized in that: The pre-tightening block 1 and the dovetail guide groove provided on the frame form a sliding pair perpendicular to the pre-tightening bolt.

3. A medicine dispensing valve according to claim 1, characterized in that: The second pre-tightening block and the dovetail guide rail integrally formed on the frame form a sliding pair parallel to the pre-tightening bolt.

4. A medicine dispensing valve according to claim 1, characterized in that: The guide piece is connected to the second threaded hole provided on the frame through threads.

5. The medicine dispensing valve according to claim 1, characterized in that: The nozzle body and the frame are fixed by fixing bolts.

6. A medicine dispensing valve according to claim 1, characterized in that: The inclined surfaces of the pre-tightening block 1 and the pre-tightening block 2 are roughened.

7. A dispensing method for a medicine dispensing valve according to any one of claims 1 to 6, characterized in that: The details are as follows: The inlet channel of the flow channel is connected to the medicine box through a medicine liquid pipeline; initially, the driving voltage of the piezoelectric stack is maintained at a preset level 1, at which time the nozzle is opened, and under the action of the medicine supply pressure, the medicine flows through the flow channel, the through hole, the center hole, the cylindrical groove and the spray cavity to the vertical hole; when the driving voltage of the piezoelectric stack is applied to a preset level 2, wherein the preset level 2 is greater than the preset level 1, the piezoelectric stack is extended and pushes the cantilever to rotate downward until it hits the nozzle, the hemisphere is embedded in the spray cavity, and the vertical hole is blocked, so that the nozzle is closed, and the medicine at the vertical hole overcomes its own viscosity and surface tension to break and form medicine drops that fall; Then the piezoelectric stack maintains the preset level 2 within the preset time, and the medicine stops flowing out; finally, the driving voltage of the piezoelectric stack is returned to the preset level 1, the piezoelectric stack shrinks to its original state, and the cantilever rotates upward to its original position under the action of the flexible hinge and the restoring spring, and drives the valve stem to move upward to its original position, and at the same time, negative pressure is formed in the spray chamber. Under the medicine supply pressure, the spray chamber is filled with surrounding medicine, waiting for the next cycle of medicine distribution.

8. A method for dispensing a medicine dispensing valve according to claim 7, characterized in that In: Before the piezoelectric stack works, the preload force on the piezoelectric stack is adjusted so that the preload force on the piezoelectric stack is a preset value. The adjustment process of the preload force of the piezoelectric stack is as follows: in the initial state, the cantilever and the flexible hinge are in a free horizontal state, and the preload bolt is turned. The preload bolt drives the piezoelectric stack to descend through preload block 2 and preload block 1, and the piezoelectric stack drives the cantilever to rotate downward, and the flexible hinge is deformed until the preload block 1 descends to a preset height, so that the preload force on the piezoelectric stack is adjusted to the preset value, thereby completing the adjustment of the preload force of the piezoelectric stack.

9. A dispensing method for a medicine dispensing valve according to claim 8, characterized in that: Assume that the lead of the pre-tightening bolt is p, the inclination angle of the inclined plane is α, and α∈(0,90°). When the pre-tightening bolt pushes the piezoelectric stack downward through the pre-tightening block 1 and the pre-tightening block 2, the center of the flexible hinge is the rotation center of the cantilever. Assume that the distance from the rotation center to the output force of the piezoelectric stack is L. p , the distance between the center of the valve stem and the center of rotation is L, and the rotation stiffness of the flexible hinge is k hinge When the preload bolt is screwed into the angle θ and the piezoelectric stack moves downward by a displacement Δx, the preload force F of the piezoelectric stack is p for: In the formula, F s To restore the pressure exerted by the spring on the cantilever, k s is the stiffness of the recovery spring and β is the rotation angle of the flexible hinge.

10. The dispensing method of a medicine dispensing valve according to claim 7, characterized in that: When the viscosity of the medicine is different or the volume of the medicine droplet dispensed at a single time is different, the output displacement of the valve stem is different. The adjustment process of the output displacement of the valve stem is: First, the driving voltage input to the piezoelectric stack and the output displacement of the valve stem are calibrated: after the adjustment of the preload force of the piezoelectric stack is completed, the output displacement of the valve stem at this time is recorded as s0, and the maximum driving voltage of the piezoelectric stack is set to V max Under this preload condition, the piezoelectric stack is intermittently loaded with a driving voltage of V max , and the voltage interval of each loading voltage is V interl , record the valve stem output displacement corresponding to each driving voltage, and repeat it many times, calculate the average value of each output displacement corresponding to the same driving voltage, and use each average value to represent the corresponding driving voltage. The output displacement corresponding to the voltage is calibrated at multiple points on the relationship between the driving voltage input to the piezoelectric stack and the output displacement of the valve stem, and the relationship between the two is fitted; then the nozzle cap is rotated downward to make a gap between the valve stem and the vertical hole, and a driving voltage is applied to the piezoelectric stack to V max The piezoelectric stack drives the valve stem to move downward to the lowest position through the cantilever; then the nozzle cap is screwed upward, and when the nozzle contacts the hemisphere, the nozzle cap is stopped; the stroke s of the valve stem is determined according to the viscosity of the drug or the volume of the drug droplet dispensed in a single time, and the driving voltage V1 of the piezoelectric stack input is obtained from the relationship between the driving voltage input by the piezoelectric stack and the output displacement of the valve stem, so that the preset level of the piezoelectric stack input is V max -V1, then when the driving voltage input to the piezoelectric stack is the preset level 1, the output displacement of the valve stem is s max -s, and the preset level of the piezoelectric stack input is always V max .

Images