阅读说明：本技术 一种应用于精准滴灌的晶片式多振子压电液压步进驱动器 (Wafer type multi-vibrator piezoelectric hydraulic stepping driver applied to precise drip irrigation ) 是由 郑晓培 蔡长青 李琳娜 王洪臣 伊延吉 栾鑫 杨云哲 于 2020-08-26 设计创作，主要内容包括：本发明公开了一种应用于精准滴灌的晶片式多振子压电液压步进驱动器,包括双作用压电泵、蓄能器、压力表、换向阀和液压缸,所述双作用压电泵包括多个串联的双晶片压电振子,所述双晶片压电振子包括由压电晶片分隔而成的上、下两个泵腔,所述压电晶片振动变形时,上、下两个所述泵腔一个吸水而另一个排水；所述双作用压电泵工作过程中采用多个截止阀控制液体的流动。本发明的目的是提供一种应用于精准滴灌的晶片式多振子压电液压步进驱动器,控制外界输入条件(电压、频率)即可调节压电振子的振动幅度,改变泵腔体积变化量,即一个周期中压电泵的输出,进而控制液压缸的输出步长,实现精密驱动,调节压电液压驱动器的输出性能。(The invention discloses a wafer type multi-vibrator piezoelectric hydraulic stepping driver applied to precise drip irrigation, which comprises a double-acting piezoelectric pump, an energy accumulator, a pressure gauge, a reversing valve and a hydraulic cylinder, wherein the double-acting piezoelectric pump comprises a plurality of tandem double-wafer piezoelectric vibrators, each double-wafer piezoelectric vibrator comprises an upper pump cavity and a lower pump cavity which are formed by dividing a piezoelectric wafer, and when the piezoelectric wafer vibrates and deforms, one of the upper pump cavity and the lower pump cavity absorbs water while the other pump cavity drains water; a plurality of stop valves are adopted to control the flow of liquid in the working process of the double-acting piezoelectric pump. The invention aims to provide a wafer type multi-vibrator piezoelectric hydraulic step driver applied to precise drip irrigation, which can adjust the vibration amplitude of a piezoelectric vibrator by controlling external input conditions (voltage and frequency), change the volume change of a pump cavity, namely the output of a medium-pressure electric pump in one period, further control the output step length of a hydraulic cylinder, realize precise driving and adjust the output performance of the piezoelectric hydraulic driver.)

1. The utility model provides a be applied to wafer formula many oscillators piezoelectricity hydraulic pressure step driver of accurate driping irrigation, includes two effect piezoelectric pump, energy storage ware, manometer, switching-over valve and pneumatic cylinder, its characterized in that: the double-acting piezoelectric pump comprises a plurality of series-connected bimorph piezoelectric vibrators, each bimorph piezoelectric vibrator comprises an upper pump cavity and a lower pump cavity which are formed by dividing a piezoelectric wafer, and when the piezoelectric wafer vibrates and deforms, one of the upper pump cavity and the lower pump cavity absorbs water while the other pump cavity drains water; a plurality of stop valves are adopted to control the flow of liquid in the working process of the double-acting piezoelectric pump.

2. The wafer type multi-vibrator piezoelectric hydraulic stepping driver applied to precise drip irrigation as claimed in claim 1, wherein: the double-acting piezoelectric pump comprises 5 bimorph piezoelectric vibrators connected in series.

3. The wafer type multi-vibrator piezoelectric hydraulic stepping driver applied to precise drip irrigation as claimed in claim 1, wherein: the piezoelectric ceramic material is selected to be PZT-4, the diameter is 29mm, the thickness is 0.2mm, the metal substrate material is beryllium bronze, the diameter is 35mm, and the thickness is 0.2mm, and the piezoelectric ceramic material is used as a basic element of a piezoelectric hydraulic driver.

4. The wafer type multi-vibrator piezoelectric hydraulic stepping driver applied to precise drip irrigation as claimed in claim 1, wherein: the stop valve is an umbrella-shaped rubber stop valve with the valve thickness of 0.2mm-0.4 mm.

5. The wafer type multi-vibrator piezoelectric hydraulic stepping driver applied to precise drip irrigation as claimed in claim 4, wherein: the stop valve is an umbrella-shaped rubber stop valve with the valve thickness of 0.3 mm.

6. The wafer type multi-vibrator piezoelectric hydraulic stepping driver applied to precise drip irrigation as claimed in claim 4, wherein: the valve hole position of the umbrella-shaped rubber stop valve can be close to the center of the piezoelectric vibrator as much as possible.

7. The wafer type multi-vibrator piezoelectric hydraulic stepping driver applied to precise drip irrigation as claimed in claim 4, wherein: the distance between the valve hole of the umbrella-shaped rubber stop valve and the edge of the valve plate is 1 mm.

8. The wafer type multi-vibrator piezoelectric hydraulic stepping driver applied to precise drip irrigation as claimed in claim 4, wherein: the umbrella-type rubber stop valve includes 6 valve openings, and the valve opening diameter is 1.7 mm.

9. The wafer type multi-vibrator piezoelectric hydraulic stepping driver applied to precise drip irrigation as claimed in claim 1, wherein: the height of the pump cavity of the double-acting piezoelectric pump is 0.3 mm-0.8 mm.

10. The wafer type multi-vibrator piezoelectric hydraulic stepping driver applied to precise drip irrigation as claimed in claim 1, wherein: the wafer type multi-vibrator piezoelectric hydraulic stepping driver adopts a back pressure loading method to ensure that liquid and gas in a pump cavity are compressed into an approximate rigid body before the piezoelectric pump works, so that the energy loss and the impact pressure in the pump cavity in the working process are reduced.

Technical Field

The invention relates to the technical field of agricultural water and fertilizer integrated precise drip irrigation, in particular to a wafer type multi-vibrator piezoelectric hydraulic step driver applied to precise drip irrigation.

Background

Drip irrigation is the most effective water-saving irrigation mode in arid water-deficient areas at present, and the water utilization rate can reach 95%. Compared with spray irrigation, the drip irrigation has higher water-saving and yield-increasing effects, and can be combined with fertilization to improve the fertilizer efficiency by more than one time. The irrigation system is suitable for irrigation of fruit trees, vegetables, economic crops and greenhouses, and can also be used for irrigation of field crops in arid places with water shortage. Most of them use plastic pipes to send water or water fertilizer to the root of crops for local irrigation through the orifices or drippers on the capillary with the diameter of about 10 mm. But the requirement of precision drip irrigation in the process of water and fertilizer integrated drip irrigation in agriculture cannot be met at present.

Disclosure of Invention

The invention aims to provide a wafer type multi-vibrator piezoelectric hydraulic step driver applied to precise drip irrigation, which can adjust the vibration amplitude of a piezoelectric vibrator by controlling external input conditions (voltage and frequency), change the volume change of a pump cavity, namely the output of a medium-pressure electric pump in one period, further control the output step length of a hydraulic cylinder, realize precise driving and adjust the output performance of the piezoelectric hydraulic driver.

In order to solve the technical problems, the invention adopts the following technical scheme:

the utility model provides a be applied to wafer formula many oscillators piezoelectricity hydraulic pressure step driver of accurate driping irrigation, includes two effect piezoelectric pump, energy storage ware, manometer, switching-over valve and pneumatic cylinder, its characterized in that: the double-acting piezoelectric pump comprises a plurality of series-connected bimorph piezoelectric vibrators, each bimorph piezoelectric vibrator comprises an upper pump cavity and a lower pump cavity which are formed by dividing a piezoelectric wafer, and when the piezoelectric wafer vibrates and deforms, one of the upper pump cavity and the lower pump cavity absorbs water while the other pump cavity drains water; a plurality of stop valves are adopted to control the flow of liquid in the working process of the double-acting piezoelectric pump.

Further, the double-acting piezoelectric pump comprises 5 double-wafer piezoelectric vibrators connected in series.

Further, the selected piezoelectric ceramic material is PZT-4, the diameter is 29mm, the thickness is 0.2mm, the metal substrate material is beryllium bronze, the diameter is 35mm, and the thickness is 0.2mm, and the piezoelectric ceramic material is used as a basic element of the piezoelectric hydraulic actuator.

Further, the stop valve is an umbrella-shaped rubber stop valve with the valve thickness of 0.2mm-0.4mm, and preferably 0.3 mm.

Furthermore, the valve hole position of the umbrella-shaped rubber stop valve can be close to the center of the piezoelectric vibrator as much as possible.

Further, the distance between a valve hole of the umbrella-shaped rubber stop valve and the edge of the valve plate is 1 mm;

further, the umbrella-shaped rubber stop valve includes 6 valve openings, and the valve opening diameter is 1.7 mm.

Furthermore, the height of the pump cavity of the double-acting piezoelectric pump is 0.3-0.8 mm.

Furthermore, the wafer type multi-vibrator piezoelectric hydraulic stepping driver adopts a back pressure loading method to enable liquid and gas in the pump cavity to be compressed into an approximately rigid body before the piezoelectric pump works, and energy loss and impact pressure in the pump cavity in the working process are reduced.

Compared with the prior art, the invention has the beneficial technical effects that:

the application loads back pressure in a piezoelectric hydraulic driving system before working, and at the moment, liquid is compressed into an approximate rigid body by the loaded back pressure; during operation, the piezoelectric vibrator deforms, and the liquid is compressed for the second time. Therefore, compared to the conventional actuator, the volume change of the liquid due to the piezoelectric vibrator generating the same amount of deformation is large, and the output speed and the driving force of the actuator are increased.

The driver works by adopting a double-wafer piezoelectric vibrator, and the vibrator is stressed evenly and is not easy to damage; the sealing system can load back pressure, reduce the influence of bubbles in liquid on the performance of the piezoelectric pump, improve the sensitivity of the liquid to the vibration deformation of the piezoelectric vibrator and the stability of the system performance, and increase the output speed, thrust and response speed of the driver.

Drawings

The invention is further illustrated in the following description with reference to the drawings.

FIG. 1 is a schematic structural diagram of a wafer type multi-vibrator piezoelectric hydraulic step actuator for precision drip irrigation according to the present invention;

FIG. 2 is a schematic diagram of the operation of a piezoelectric hydraulic step actuator;

FIG. 3 is a schematic diagram of the umbrella-shaped rubber stop valve;

FIG. 4 is an exploded view of a double acting piezoelectric pump

FIG. 5 is a graph of the output speed versus frequency of the drive when purified water is loaded with different back pressures;

FIG. 6 is a graph of the output thrust versus frequency of the driver when purified water is loaded with different back pressures;

FIG. 7 is a graph of output speed versus frequency for a driver loaded with tap water at different back pressures;

FIG. 8 is a graph of the output thrust versus frequency of the driver when tap water is loaded with different back pressures;

FIG. 9 is a speed-back pressure curve for a drive;

FIG. 10 is a thrust-back pressure curve for the drive;

FIG. 11 is a graph of output speed versus frequency for a driver under different external loads;

FIG. 12 is a graph of output step size versus frequency for a driver under different external loads;

FIG. 13 is a graph of output speed versus external load for a drive at different back pressures;

FIG. 14 is a graph of output power versus external load for a driver at different back pressures;

FIG. 15 is a graph of the output step size versus the external load of the drive at different back pressures;

description of reference numerals: 1. a double-acting piezoelectric pump; 101-a pump body; 1010-pump housing; 1011-a shut-off valve plate; 1012-piezoelectric vibrator support plate; 102-a water inlet; 103-a water outlet; 104-a piezoelectric wafer; 105-a sealing ring; 106-bolt; 107-nut; (ii) a 2. An accumulator; 3. a pressure gauge; 4. a diverter valve; 5. a hydraulic cylinder; 6-a stop valve; 601-valve seat (pump body); 602-a valve bore; 603-valve plate.

Detailed Description

As shown in fig. 1 to 4, a wafer type multi-vibrator piezoelectric hydraulic step driver for precise drip irrigation, wherein a hydraulic cylinder of the driver is connected with a water and fertilizer integrated medicine box, the fertilizing amount is adjusted by controlling the speed and the thrust of the hydraulic cylinder, the wafer type multi-vibrator piezoelectric step driver comprises a double-acting piezoelectric pump 1, an energy accumulator 2, a pressure gauge 3, a reversing valve 4 and a hydraulic cylinder 5, the double-acting piezoelectric pump 1 comprises a plurality of serially connected double-wafer piezoelectric vibrators, the double-wafer piezoelectric vibrator comprises an upper pump cavity and a lower pump cavity which are separated by a piezoelectric wafer 104, and when the piezoelectric wafer 104 vibrates and deforms, one of the upper pump cavity and the lower pump cavity absorbs water while the other pumps water; the double-acting piezoelectric pump 1 adopts a plurality of stop valves 6 to control the flow of liquid in the working process.

The double-acting piezoelectric pump 1 comprises 5 bimorph piezoelectric vibrators connected in series. The piezoelectric ceramic material is selected to be PZT-4, the diameter is 29mm, the thickness is 0.2mm, the metal substrate material is beryllium bronze, the diameter is 35mm, and the thickness is 0.2mm, and the piezoelectric ceramic material is used as a basic element of a piezoelectric hydraulic driver. As shown in fig. 3, the stop valve 6 is an umbrella-shaped rubber stop valve with a valve thickness of 0.2mm to 0.4 mm. The valve hole position of the umbrella-shaped rubber stop valve 6 can be as close to the center of the piezoelectric vibrator as possible. The distance between the valve hole of the umbrella-shaped rubber stop valve and the edge of the valve plate is r₂1mm；

The umbrella-shaped rubber stop valve comprises 6 valve holes, and the diameter r1 of each valve hole is 1.7 mm. In a certain cavity height range, the output flow rate of the piezoelectric pump is in direct proportion to the height of the pump cavity, the output pressure of the piezoelectric pump is in inverse proportion to the height of the pump cavity, in addition, energy loss is inevitably generated in the flowing process of liquid, and the path loss is in inverse proportion to the height of the pump cavity, so the height of the pump cavity of the double-acting piezoelectric pump 1 is 0.3 mm-0.8 mm. The pump body is made of PMMA (polymethyl methacrylate); the wafer type multi-vibrator piezoelectric hydraulic stepping driver adopts a back pressure loading method to ensure that liquid and gas in a pump cavity are compressed into an approximate rigid body before the piezoelectric pump works, so that the energy loss and the impact pressure in the pump cavity in the working process are reduced.

Under 150V alternating current voltage, piezoelectric pumps which take umbrella-shaped valves with valve block diameters of 10mm and valve block thicknesses of 0.2mm, 0.3mm and 0.4mm as stop valves are respectively tested, and test results show that the piezoelectric pumps with the valve block thicknesses of 0.3mm and the umbrella-shaped valves have output flow and pressure higher than those of the piezoelectric pumps with the valve block thicknesses of 0.2mm and 0.4mm, so that the umbrella-shaped rubber stop valves with the valve block thicknesses of 0.3mm are preferably used in the invention.

The operation principle of the actuator is shown in fig. 2, which is the operation state of the piezoelectric pump in one cycle. The piezoelectric pump is formed by connecting the double-wafer piezoelectric vibrators in series, and one double-wafer piezoelectric vibrator forms an upper pump cavity and a lower pump cavity. When the piezoelectric wafer vibrates and deforms, one of the upper pump cavity and the lower pump cavity absorbs water and the other pumps the water. In the figure, Ai, Vi, and Ci (i ═ 1, 2, and 3 …) represent a piezoelectric wafer, a shutoff valve, and a pump chamber of a piezoelectric pump, respectively. The piezoelectric wafers A1, A3 and A5 in the piezoelectric pump are bent downwards, and A2 and A4 are bent upwards as the starting point of one working cycle, as shown in FIG. 2 (a). At this time, the stop valves V1, V3, V5, V8, V10, and V12 are closed, the valves V2, V4, V6, V7, V9, and V11 are opened, and the piezoelectric pump chambers C1, C3, C5, C7, and C9 are in a water discharge state; the pump chambers C2, C4, C6, C8, and C10 are sucking water, and the entire piezoelectric pump exhibits a-side water discharge and B-side water suction. As the volumes of the pump cavities C1, C3, C5, C7 and C9 are gradually reduced, the volumes of the pump cavities C2, C4, C6, C8 and C10 are gradually increased, the pressure difference between the adjacent pump cavities is increased, the pressure difference acts on the stop valves, the stop valves V1, V3, V5, V8, V10 and V12 are forced to be closed more tightly, and the opening amplitude of valve plates of the valves V2, V4, V6, V7, V9 and V11 is increased. When the piezoelectric wafer deforms to the maximum deflection, as shown in fig. 2(b), the valves V2, V4, V6, V7, V9, and V11 are opened to the maximum, and the output flow rate of the piezoelectric pump reaches the maximum. Subsequently, the direction of the voltage is changed, and the piezoelectric wafers a1, A3, a5 start to move upward, and a2, a4 move downward, as shown in fig. 2 (c). At this time, the volumes of the pump chambers C1, C3, C5, C7 and C9 gradually increase, the pressure in the pump chambers decreases, and water starts to be sucked; the pump chambers C2, C4, C6, C8, and C10 gradually decrease, the pump chamber pressure increases, and water starts to be discharged. The shut-off valves V1, V3, V5, V8, V10, V12 are about to open, and the valves V2, V4, V6, V7, V9, V11 are gradually closed. However, the self-suction performance of the piezoelectric pump is insufficient due to relatively large pressure in the pump chambers C1, C3 and C5, the stop valves V1, V3 and V5 cannot be opened, the valves V2, V4 and V6 are closed and delayed, and the phenomenon that the water outlet on the side A of the piezoelectric pump flows backwards occurs; the pressure in the B-side pump cavities C6, C8 and C10 is too small to overcome the energy consumed by opening/closing of the valve plates, so that the stop valves V8, V10 and V12 cannot be opened, the valves V7, V9 and V11 are closed and delayed, and the phenomenon of backflow of a B-side water inlet of the piezoelectric pump occurs. At this time, the piezoelectric pump has no output. As the piezoelectric wafer continues to move, as shown in fig. 2(d), the pressure in the pump chambers C1, C3 and C5 on the a side decreases to a specific value, the chambers generate self-suction to open the stop valves connected to the previous pump chamber, i.e., the valves V1, V3 and V5 are gradually opened, the pump chambers begin to suck water, and the liquid enters the pump chambers through the previous pump chambers, which is integrally expressed as the water suction on the a side of the piezoelectric pump; when the pressure in the B-side pump chambers C6, C8 and C10 is increased to overcome the energy consumed by opening the valve plates, the umbrella-shaped valve entering the next pump chamber is opened, namely the valve plates V8, V10 and V12 are gradually opened, the pump chamber begins to drain, and liquid enters the next pump chamber, which is integrally represented as the B-side drainage of the piezoelectric pump. However, because the pressure in the pump cavities of C2, C4, C6, C8 and C10 is not enough to close the valve plates, the stop valves V2, V4, V6, V7, V9 and V11 are still in an open state, and backflow occurs to the water outlets on the A side and the water outlets on the B side of the piezoelectric pump.

At the beginning of the next half of the duty cycle, the piezo-electric wafers A1, A3, A5 begin to bend upward and A2, A4 bend downward, as shown in FIG. 2 (e). When the shutoff valves V1, V3, V5, V8, V10, and V12 are all opened and the valves V2, V4, V6, V7, V9, and V11 are all closed, the backflow phenomenon disappears, and the piezoelectric pump is in the a-side water suction state and the B-side water discharge state. When the downward bending deformation of the piezoelectric wafers A1, A3 and A5 reaches the maximum and the upward movement deflection of the piezoelectric wafers A2 and A4 reaches the maximum, the volumes of the cavities of the piezoelectric pump chambers C1, C3, C5, C7 and C9 reach the maximum; the pump chambers C2, C4, C6, C8 and C10 have the minimum chamber volume, the stop valves V1, V3, V5, V8, V10 and V12 are completely opened, the side a of the piezoelectric pump sucks water, and the side B of the piezoelectric pump discharges water, as shown in fig. 2 (f). The voltage direction is changed again, the moving direction of the piezoelectric wafer is changed accordingly, a1, A3 and a5 start to move downwards, a2 and a4 move upwards, the pressure in the pump cavity is changed, the opening amplitudes of the stop valves V1, V3, V5, V8, V10 and V12 are gradually reduced, and the water inlets on the a side and the water outlets on the B side of the piezoelectric pump flow backwards, as shown in fig. 2 (g). When the deformation of the piezoelectric wafer approaches 0, all the stop valves are in an open state, as shown in fig. 2(h), the side water inlet of the piezoelectric pump a flows backwards, the water outlet discharges water, the side water inlet of the piezoelectric pump B absorbs water, and the water outlet flows backwards. Then, the piezoelectric wafers a1, A3, a5 start to bend downward, a2, a4 bend upward, and the piezoelectric pump repeats the operation in fig. 2 (a).

Before working, loading backpressure in a wafer type multi-vibrator piezoelectric hydraulic stepping driver, and compressing liquid into an approximate rigid body by the loaded backpressure; during operation, the piezoelectric vibrator deforms, and the liquid is compressed for the second time. Therefore, compared to the conventional actuator, the volume change of the liquid due to the piezoelectric vibrator generating the same amount of deformation is large, and the output speed and the driving force of the actuator are increased. The driver works by adopting a double-wafer piezoelectric vibrator, and the vibrator is stressed evenly and is not easy to damage; the sealing system can load back pressure, reduce the influence of bubbles in liquid on the performance of the piezoelectric pump, improve the sensitivity of the liquid to the vibration deformation of the piezoelectric vibrator and the stability of the system performance, and increase the output speed, thrust and response speed of the driver.

Experiment of loading different back pressures

And the five piezoelectric vibrators simultaneously work under the voltage of 150V as a fixed condition, and different back pressures are loaded and the amount of gas contained in the liquid is changed to be a variable to perform the performance test of the piezoelectric hydraulic driver.

When pure water (containing less gas) is used as the liquid, different back pressures are applied to the driver, and the test results are shown in fig. 5 and 6.

The output speed and the thrust of the piezoelectric hydraulic driver are maximum when the loading backpressure is 0.04 MPa. The maximum output speed and the maximum output thrust of the driver are respectively 23.33mm/s, 80.4N, 25.83mm/s and 92.6N when the back pressure is loaded to be 0MPa and 0.04MPa within the range of 60-400 Hz. The output speed and thrust of the driver at a back pressure of 0.04MPa are 1.11 times and 1.15 times respectively at 0 MPa.

When tap water (containing more gas) was used as the liquid, different back pressures were applied to the driver, and the test results are shown in fig. 7 and 8.

The maximum output speed and the maximum output thrust of the piezoelectric hydraulic driver are respectively 10.72mm/s, 56.8N, 13.83mm/s and 66.4N when the back pressure is loaded between 60 Hz and 400Hz and the back pressure is 0MPa and 0.07 MPa. The output speed and thrust of the driver at a back pressure of 0.07MPa are respectively 1.17 times and 1.29 times of those at 0 MPa.

Experiment of influence of gas content on optimum loading backpressure

As shown in fig. 9 and 10, the output speed and thrust of the driver using pure water as the liquid reach extreme values when the back pressure is 0.04MPa, and the output speed and thrust of the driver using tap water as the working medium reach maximum values when the back pressure is 0.07MPa, which indicates that the more gas is contained in the system, the larger the back pressure value to be loaded by the driver to achieve the optimal output. Because the compressibility of a gas is much greater than that of a liquid, the back pressure of the load required to compress a unit volume of gas to a near-rigid body is greater than that of water.

Performance of the drive under load

The multi-vibrator piezoelectric hydraulic stepping driver has the advantages that the output capacity is optimal when the voltage is 150V, five piezoelectric vibrators work simultaneously, purified water is used as a medium, and the loading backpressure is 0.04MPa, and the output performance of the piezoelectric hydraulic driver when different external loads (0N, 5N, 10N, 15N and 20N) are loaded is tested under the working condition.

The output speed-frequency relationship curve of the driver under different external loads is shown in fig. 11, and the output step-frequency relationship curve of the driver under different external loads is shown in fig. 12.

In order to further study the working performance of the piezoelectric hydraulic driver under an external load, the relationship between the output speed of the driver under different back pressures and the load under the conditions of 400Hz frequency and 150V voltage is tested, and the test result is shown in fig. 13.

The output speed of the driver at different back pressures gradually decreases with increasing external load. For a driver using pure water as a working medium, when the loading backpressure is 0.04MPa, the maximum bearing value of the driver is 30N. The maximum load value of the driver is 20N when the loading back pressure is 0.3 MPa.

FIG. 14 is a graph of output power versus load for a piezo-electric hydraulic drive at a frequency of 400Hz and a voltage of 150V. The curve has a peak value, which is the optimal output power, and the corresponding load is the optimal external load. Loading the appropriate back pressure can increase the optimum external load value of the drive.

The piezoelectric hydraulic driver is a precise stepping driver, and the precision grade and the variation trend of the output step length are important indexes of the piezoelectric hydraulic driver. The output step size versus load of a driver operating at 400Hz, 150V, and different back pressures was analyzed as shown in fig. 15. With the increase of the load, the output step length of the driver under different back pressures is gradually reduced, and when the maximum load value is exceeded, the output step length is 0.

Under the condition that the working mode, the loading backpressure and the gas content in liquid of the double-acting piezoelectric pump are determined, the output speed, the thrust, the power and the step length of the piezoelectric hydraulic driver have direct relations with the working frequency, the working voltage, the external load and other factors. In practical application, the working frequency, voltage and load of the piezoelectric hydraulic actuator are determined according to the specific requirements of the working occasion and the output performance of the piezoelectric hydraulic actuator.

The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solutions of the present invention can be made by those skilled in the art without departing from the spirit of the present invention, and the technical solutions of the present invention are within the scope of the present invention defined by the claims.