A piezoelectric ring bending drive type two-stage spool valve type electro-hydraulic servo valve

Abstract

A piezoelectric ring bending drive type two-stage spool valve, comprising a piezoelectric ring, an output rod, a left feedback slider, a left feedback rod, a left control valve core, a control valve sleeve, a connecting rod, a right control valve core, a right feedback rod, a right feedback slider, a main valve sleeve and a main valve core, the piezoelectric ring is bent and deformed to drive the control valve core to move in the control valve sleeve, the displacement is detected by an LVDT sensor, and then is transmitted to a control circuit to form closed-loop control of the displacement of the control valve core. The movement of the control valve core causes the control valve port to open, a pressure difference is generated to drive the main valve core to move, the movement of the main valve core drives the feedback rod and the feedback slider to reversely drive the control valve sleeve to move, the control valve port is gradually closed, when the control valve port is completely closed, the main valve core stops moving, closed-loop control of the position of the main valve core is formed, and the displacements of the main valve core and the control valve core are proportional. The present application adopts high-speed precise piezoelectric ring driving and closed-loop control of both stages of spool valves, and has the advantages of fast response, high precision, compact structure and the like.

Description

Technical Field

[0001] This invention belongs to the field of electro-hydraulic servo technology, specifically relating to a piezoelectric ring-driven two-stage slide valve electro-hydraulic servo valve. Background Technology

[0002] The development history of electro-hydraulic servo valves shows that improving the frequency response and dynamic load-carrying capacity of the electro-mechanical converter used in servo valves is a prerequisite for improving the dynamic performance of servo valves. The emergence of high-precision, high-frequency-response, and high-reliability electro-mechanical converters, represented by piezoelectric actuators, has provided an opportunity for the development of high-speed, precision, and high-reliability electro-hydraulic servo valves. Piezoelectric actuators are characterized by low energy consumption, no heat generation, long service life, no magnetic field, short response time, and great energy-saving potential; their application research in electro-hydraulic servo valves has always been a research hotspot for new electro-hydraulic servo valves. A comparison of several piezoelectric actuators reveals that piezoelectric bicrystalline, piezoelectric stacked, and enlarged piezoelectric actuators have been extensively studied and applied in electro-hydraulic servo valves. Research on piezoelectric ring-driven electro-hydraulic servo valves is still in its early stages. Considering factors such as size, performance, and price, piezoelectric ring-driven actuators are more suitable for driving electro-hydraulic servo valves.

[0003] Direct position feedback two-stage spool-type electro-hydraulic servo valves are driven by moving-coil force motors. However, moving-coil force motors are large, have low natural frequency, and slow response speed, resulting in poor dynamic performance of such electro-hydraulic servo valves. However, because the control valve core is located within the main valve core, its structure is compact and its reliability is high. Using a piezoelectric ring actuator to drive the direct position feedback two-stage spool-type electro-hydraulic servo valve can produce an electro-hydraulic servo valve with excellent dynamic performance and a compact structure.

[0004] However, due to the small displacement and hysteresis nonlinearity of the piezoelectric ring bending actuator, if the moving coil force motor is directly replaced with the piezoelectric ring bending actuator without modifying the structure of the entire valve, although its dynamic performance can be improved, the flow rate of the entire electro-hydraulic servo valve will be small and the nonlinearity will be severe. Summary of the Invention

[0005] To overcome the above shortcomings, this invention provides a piezoelectric ring-driven two-stage spool-type electro-hydraulic servo valve. This electro-hydraulic servo valve uses a piezoelectric ring to drive the control valve core through bending. The displacement of the control valve core is detected by an LVDT displacement sensor and fed back to the controller to form an electrical feedback closed-loop control of the control valve core displacement. Furthermore, a novel displacement feedback mechanism is added between the main valve core and the control valve, allowing the main valve displacement to be greater than the control valve core displacement, thus enabling the entire valve to output a larger flow rate.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A piezoelectric ring-driven two-stage spool valve electro-hydraulic servo valve includes a left feedback slider, a left feedback rod, a main valve sleeve, a left control valve core, a main valve core, a control valve sleeve, a connecting rod, a wire trough, a right control valve core, a right feedback rod, a right feedback slider, a piezoelectric ring, a support base, a zero-adjustment nut, a right end cap, an output rod, a valve body, an LVDT core, and an electrical housing. Both the left and right control valve cores are housed within the control valve sleeve and are threadedly connected by the connecting rod. The side surface of the piezoelectric ring is glued to the valve body with epoxy resin, and its inner hole is glued to the support base with epoxy resin. The two ends of the output rod are connected to one end of the support base and one end of the right control valve core, respectively. The other end of the right control valve core and one end of the left control valve core are connected by the connecting rod to form a control valve core assembly. The control valve core assembly is located within the control valve sleeve, and the other end of the left control valve core is threadedly connected to the LVDT core.

[0008] Further optimization involves providing threaded holes at both ends of the left and right control valve cores for threaded connection with the connecting rod. The left control valve core has an annular groove on its side and an oil return hole inside, with its central part being an inner cavity communicating with the threaded holes at both ends. The right control valve core also has an annular groove on its side, with an oil return hole inside, and its central part being an inner cavity communicating with the threaded holes at both ends.

[0009] Further optimization involves connecting the two ends of the main valve core to the left feedback rod and the right feedback rod respectively through one or more threaded holes.

[0010] Further optimization involves the control valve sleeve, main valve core, and main valve sleeve being sequentially arranged within the valve body from the inside out. Both ends of the control valve sleeve are inclined planes. One end of the left feedback rod is connected to one end of the main valve core, and the other end of the left feedback rod is an inclined plane that contacts the upper end face of the left feedback slider. The lower end face of the left feedback slider contacts one end face of the control valve sleeve. One end of the right feedback rod is connected to the other end of the main valve core, and the other end face of the right feedback rod is an inclined plane that contacts the upper end face of the right feedback slider. The lower end face of the right feedback slider contacts one end face of the control valve sleeve.

[0011] Further optimization involves having 1 to 4 left and right feedback rods, with the angle between the left end of the left feedback rod and the inclined plane of the right feedback rod and the horizontal direction being less than 45°, and the tilt angle of the lower inclined plane of the left and right feedback sliders being greater than 45°.

[0012] Further optimization is characterized in that the diameter of the connecting rod is smaller than the diameter of the control valve core, one end of the connecting rod has a left return oil passage communicating with the inner cavity of the left control valve core, the left return oil passage communicating with the control valve return oil cavity formed between the connecting rod and the control valve sleeve through the left return oil hole on the side wall, and the other end is provided with a right return oil passage communicating with the inner cavity of the right control valve core, the right return oil passage communicating with the control valve return oil cavity through the right return oil hole on the side wall.

[0013] Further optimization involves providing a left annular groove and a right annular groove inside the control valve sleeve. The right end of the annular groove on the left control valve core and the left end of the annular groove on the control valve sleeve constitute the left control valve port, and the left end of the annular groove on the right control valve core and the right end of the right annular groove on the control valve sleeve constitute the right control valve port.

[0014] Further optimization involves the control valve core assembly being driven by the bending of a piezoelectric ring to form a control slide valve. Its displacement is detected by an LVDT sensor, conditioned by a conditioning circuit, and fed back to the controller to form an electrical feedback closed-loop control of the displacement of the control valve core assembly. The main valve core and the main valve sleeve form a power-stage slide valve. The main valve core pushes a displacement feedback mechanism composed of a left feedback rod and a left feedback slider or a right feedback rod and a right feedback slider to drive the control valve sleeve to move in the opposite direction, causing the left and right control valve ports formed by the control valve sleeve and the left and right control valve cores to gradually close. When the left and right control valve ports are completely closed, the main valve core stops moving, forming a mechanical feedback closed-loop control of the main valve core position, making the displacement of the main valve core proportional to the displacement of the control valve core, with the ratio being the transmission ratio of the feedback mechanism.

[0015] Further optimization involves threading the output rod to the support base, with both using fine-pitch threads. Zeroing is achieved by rotating the output rod, and after zeroing, the two are locked together using the zeroing nut.

[0016] The beneficial effects of this invention are as follows:

[0017] 1. The control valve core assembly is driven by the bending deformation of the piezoelectric ring. Since the piezoelectric ring has a very fast response speed, the valve core can also respond very quickly. The displacement of the control valve core assembly is detected by the LVDT sensor, and after being conditioned by the conditioning circuit, it is fed back to the controller to form an electrical feedback closed-loop control of the displacement of the control valve core assembly. By adjusting the controller parameters, the motion accuracy and response speed of the control valve core can be improved.

[0018] 2. The left feedback rod, left feedback slider, right feedback rod and right feedback slider constitute the displacement reduction feedback mechanism from the main valve core to the control valve sleeve. This makes the displacement of the main valve core greater than the displacement of the control valve core assembly, and forms a direct position feedback closed-loop control of the displacement of the main valve core.

[0019] 3. The hollow structure of the left control valve core, the right control valve core and the connecting rod forms a return oil passage, which also helps to reduce the inertial load of the piezoelectric ring bending actuator.

[0020] In summary, the piezoelectric ring bending drive type two-stage spool valve electro-hydraulic servo valve designed in this invention is driven by a piezoelectric ring bending drive actuator. Both spool valves adopt closed-loop control, with the control spool valve located inside the main spool valve. The minimum oil flow dimension is relatively large, making it less prone to clogging. The electro-hydraulic servo valve designed in this invention has significant advantages such as fast response speed, high control accuracy, compact structure, and excellent anti-contamination performance. In addition, since the feedback mechanism of the main valve is a displacement reduction mechanism, the displacement of the main valve core can be greater than the displacement of the control valve core, allowing the entire electro-hydraulic servo valve to output a larger flow rate without increasing the size of the piezoelectric ring bending drive actuator. Attached Figure Description

[0021] Figure 1 This is a structural diagram of a piezoelectric ring-driven two-stage slide valve electro-hydraulic servo valve.

[0022] Figure 2 This is a diagram of the oil passage for a piezoelectric ring-driven two-stage slide valve electro-hydraulic servo valve.

[0023] Figure 3 This is a schematic diagram of the displacement transmission relationship of the feedback mechanism;

[0024] Figure 4 Diagram showing the displacement relationship between the feedback rod and the feedback slider;

[0025] Figure 5 Diagram showing the relationship between the feedback slider and the displacement of the control valve sleeve;

[0026] Figure 6 This is a circuit diagram for a piezoelectric ring drive.

[0027] Figure 7 Diagram showing the bending deformation of the piezoelectric ring;

[0028] Markings in the diagram: 1. Left feedback slider; 2. Left feedback rod; 3. Main valve sleeve; 4. Left control valve core; 4-1. First annular groove; 4-2. First oil return hole; 4-3. Inner cavity of left control valve core; 5. Main valve core; 6. Control valve sleeve; 7. Connecting rod; 7-1. Left oil return passage; 7-2. Right oil return passage; 7-3. Left oil return hole; 7-4. Right oil return hole; 8. Wire groove; 9. Right control valve core; 9-1. Second annular groove; 9-2. Second oil return hole; 9-3. Right control valve core. 10. Right feedback rod, 11. Right feedback slider, 12. Piezoelectric ring, 13. Support base, 14. Zero adjustment nut, 15. Right end cover, 16. Output rod, 17. Valve body, 18. LVDT core, 19. Electrical housing, 20. Right control chamber, 21. Right control valve port, 22. Right fixed throttle orifice, 23. Left fixed throttle orifice, 24. Left control valve port, 25. Left control chamber, 26. Left high-pressure oil chamber, 27. Control valve return oil chamber, 28. Main valve return oil chamber. Detailed Implementation

[0029] The technical solutions in the embodiments of the present invention will now be clearly and completely described with reference to the accompanying drawings.

[0030] A piezoelectric ring-driven two-stage spool valve electro-hydraulic servo valve includes a left feedback slider 1, a left feedback rod 2, a main valve sleeve 3, a left control valve core 4, a main valve core 5, a control valve sleeve 6, a connecting rod 7, a wire trough 8, a right control valve core 9, a right feedback rod 10, a right feedback slider 11, a piezoelectric ring 12, a support base 13, a zero-adjustment nut 14, a right end cap 15, an output rod 16, a valve body 17, an LVDT iron core 18, and an electrical housing 19. The left control valve core 4 has a first annular groove 4-1 on its side and a first oil return hole 4-2 inside, with its central part being a left control valve core cavity 4-3 communicating with threaded holes at both ends. The right control valve core 9 has an annular groove 9-1 on its side, with a second oil return hole 9-2 inside, and its central part being a right control valve core cavity communicating with threaded holes at both ends. 9-3, the two ends of the main valve core 5 are respectively connected to the left feedback rod 2 and the right feedback rod 10 through one or more threaded holes, and the number of the left feedback rod 2 and the right feedback rod 10 is 1 to 4; the left control valve core 4 and the right control valve core 9 are both set in the control valve sleeve 6, and the two are threadedly connected by the connecting rod 7. The side surface of the piezoelectric ring 12 is glued to the valve body 17 with epoxy resin, and its inner hole is glued to the support seat 13 with epoxy resin. The two ends of the output rod 16 are respectively connected to one end of the support seat 13 and one end of the right control valve core 9. The other end of the right control valve core 9 and one end of the left control valve core 4 are connected by the connecting rod 7 to form a control valve core assembly. The control valve core assembly is located in the control valve sleeve 6, and the other end of the left control valve core 4 is threadedly connected to the LVDT iron core 18.

[0031] The control valve sleeve 6 has a left annular groove and a right annular groove inside. The right end of the annular groove on the left control valve core 4 and the left end of the annular groove on the control valve sleeve 6 form the left control valve port 24, and the left end of the annular groove on the right control valve core 9 and the right end of the right annular groove on the control valve sleeve 6 form the right control valve port 21. The control valve sleeve 6 has an oil drain port in the middle and an oil inlet port inside the annular groove. The main valve core 5 has four annular oil grooves. Its left end face has a set of stepped holes including small and large holes. The small hole is the left fixed throttling hole 23, and the large hole communicates with the left annular oil groove of the control valve sleeve through a vertical hole. The right end face also has a set of stepped holes including small and large holes. The small hole is the right fixed throttling hole 22, and the large hole communicates with the right annular oil groove of the control valve sleeve through a vertical hole.

[0032] The control valve sleeve 6, main valve core 5, and main valve sleeve 3 are sequentially arranged inside the valve body 17 from the inside out. Both ends of the control valve sleeve 6 are inclined planes. One end of the left feedback rod 2 is connected to one end of the main valve core 5, and the other end of the left feedback rod 2 is an inclined plane that contacts the upper surface of the left feedback slider 1. The angle between the inclined plane and the horizontal direction is less than 45°. The lower surface of the left feedback slider 1 contacts one end of the control valve sleeve 6. One end of the right feedback rod 10 is connected to the other end of the main valve core 5, and the other end of the right feedback rod 10 is an inclined plane that contacts the upper surface of the right feedback slider 11. The inclination angle of the lower inclined planes of the left and right feedback sliders is greater than 45°. The lower surface of the right feedback slider 11 contacts one end of the control valve sleeve 6.

[0033] The four sides of the two shoulders of the main valve sleeve 3 and the four annular grooves in the middle of the main valve core 5 form four variable throttling ports. There is an oil passage in the left shoulder leading to the control port A, and an oil passage in the right shoulder leading to the control port B. There is an oil passage in the middle of the main valve sleeve 3 leading to the return port A, and oil ports at both ends of the main valve sleeve 3 leading to the inlet port P.

[0034] The diameter of the connecting rod 7 is smaller than the diameter of the control valve core. One end of the connecting rod 7 has a left return oil passage 7-1 that communicates with the inner cavity 4-3 of the left control valve core. The left return oil passage 7-1 communicates with the control valve return oil cavity 27 formed between the connecting rod 7 and the control valve sleeve 6 through the left return oil hole 7-3 on the side wall. The other end has a right return oil passage 7-2 that communicates with the inner cavity 9-3 of the right control valve core. The right return oil passage 7-2 communicates with the control valve return oil cavity 27 through the right return oil hole 7-4 on the side wall.

[0035] The control valve core assembly is driven by the bending of the piezoelectric ring 8, forming a control slide valve. Its displacement is detected by an LVDT sensor, conditioned by a conditioning circuit, and fed back to the controller to form an electrical feedback closed-loop control of the displacement of the control valve core assembly. The main valve core 5 and the main valve sleeve 3 form a power stage slide valve. The main valve core 5 pushes the displacement feedback mechanism, which is composed of the left feedback rod 2 and the left feedback slider 1 or the right feedback rod 10 and the right feedback slider 11, to drive the control valve sleeve 6 to move in the opposite direction. This causes the left control valve port 24 and the right control valve port 21, which control the movement of the main valve core 5, formed by the left control valve core 4 and the right control valve core 9, to gradually close. When the control valve ports are completely closed, the main valve core 5 stops moving, forming a mechanical feedback closed-loop control of the position of the main valve core 5. This makes the displacement of the main valve core proportional to the displacement of the control valve core, and the ratio is the transmission ratio of the feedback mechanism.

[0036] The specific real-time operation of the main valve displacement feedback mechanism in a piezoelectric ring-driven two-stage slide valve electro-hydraulic servo valve is as follows: The horizontal movement of the main valve core is converted into the vertical movement of the feedback slider by the feedback rod. If the tilt angle of the feedback slider is... θ 1. The relationship between the vertical displacement of the feedback slider and the horizontal displacement of the main valve core is as follows: y =x 1tant θ 1. The feedback slider controls the valve sleeve by pressing it against the inclined plane. If the inclination angle of the control valve sleeve is... θ 2, then y = x 2cot θ 2. The displacement of the main valve core and the control valve sleeve x 1= x 2tant θ 1cot θ 2. Due to θ 2 is greater than 45°, θ 1 is less than 45°, therefore x 1 greater than x 2, for example θ 2. Take 30°. θ If we take 60°, the magnification is 3 times.

[0037] The piezoelectric ring bending actuator uses a three-wire bipolar drive. When the input voltage... u When the input voltage is 0, the piezoelectric ring does not bend or deform; when the input voltage is 0, the piezoelectric ring does not bend or deform. u When the voltage is in the range of -100V to 0V, the piezoelectric ring bends to the right; when the input voltage... u In the range of 0~100V, the piezoelectric ring bends to the left, and its deformed shape is as follows: Figure 7 As shown. The piezoelectric ring bending displacement controls the displacement of the valve core assembly. After the displacement of the valve core assembly is detected by the LVDT sensor, it is fed back to the controller. After comparison and calculation with the input command, the output control quantity is amplified by the drive circuit and output to the piezoelectric ring, so that the piezoelectric ring bending displacement is proportional to the magnitude of the input command and the direction is related to the polarity of the input command.

[0038] The working principle of this invention is as follows: After the system supplies oil, the high-pressure oil flows into the valve body 17 through the oil inlet P and then splits into two paths along the oil passage. One path flows into the left control chamber 25 through the left fixed throttle orifice 23, and the other path flows into the right control chamber 20 through the right fixed throttle orifice 22. When the controller input command is zero, the piezoelectric ring input voltage is 0, the piezoelectric ring does not bend or deform, the left control valve port 24 is closed, and the right control valve port 21 is also closed. The oil pressure in the left control chamber 25 and the right control chamber 20 is equal, so the hydraulic pressure on the left and right ends of the main valve core 5 is equal, the main valve core 5 is at zero position and does not move, the main valve throttle ports A1, A2, B1, and B2 are all closed, and there is no flow output from the control oil ports A and B.

[0039] When the input command is positive, the piezoelectric ring input voltage uWhen the value is positive, the piezoelectric ring bends and deforms to the left, pushing the control valve core assembly to the left via the support seat 13 and output rod 16. The left control valve port 24 closes, and the right control valve port 21 opens. The oil in the right control chamber 20 flows back to the oil tank through the right control valve port 21, the right control valve core annular groove 9-1, the groove return oil hole 9-2, the right control valve core inner cavity 9-3, the right return oil passage 7-2 in the connecting rod, the right return oil hole 7-4 in the connecting rod, the control valve return oil chamber 27, the return oil hole in the middle of the control valve sleeve and the main valve, the main valve return oil chamber 28, the valve body return oil passage, and the return oil port T. This connects the right control chamber 20 to the oil tank, causing a pressure drop in the right control chamber 20. The hydraulic pressure exerted by the oil in the right control chamber 20 on the main valve core 5 to the left decreases, while the oil in the left control chamber 25... With the force remaining constant, the hydraulic pressure acting on the main valve core 5 to the right also remains constant. Therefore, the main valve core 5 is subjected to a resultant force to the right, and the main valve core 5 moves to the right. Through the right feedback rod 10 and the right feedback slider 11, it pushes the control valve sleeve 6 to the left, causing the right control valve port 21 to gradually close. During this process, the pressure in the right control chamber 20 gradually increases. When the right control valve port 21 is completely closed, the oil pressure in the right control chamber 20 is equal to the oil pressure in the left control chamber 25. The hydraulic pressures on both ends of the main valve core 5 are equal, and the main valve core 5 stops moving. Its displacement is proportional to the control valve core. When the main valve core moves to the right, the main valve throttle port A1 and the main valve throttle port B1 are closed, and the main valve throttle port B2 is opened and connected to the right high-pressure oil chamber 29. The high-pressure oil in the chamber flows through the main valve throttle port B2 to the control port B and into one end of the load. Meanwhile, the main valve throttle port A2 is opened and connected to the return oil chamber T. The oil at the other end of the load flows back to the oil tank through the control port A, the main valve throttle port A2, and the return oil chamber T.

[0040] When the input command is negative, the piezoelectric ring input voltage uWhen the value is negative, the piezoelectric ring bends to the right, pushing the control valve core assembly to the right via the support seat 13 and the output rod 16. The left control valve port 24 opens, and the right control valve port 21 closes. Oil in the left control chamber 25 flows back to the oil tank via the left control valve port 24, the left control valve core annular groove 4-1, the groove return oil hole 4-2, the left control valve core inner cavity 4-3, the left return oil passage 7-1 in the connecting rod, the left return oil hole 7-3 in the connecting rod, the control valve return oil chamber 27, the return oil hole in the middle of the control valve sleeve and the main valve, the main valve return oil chamber 28, the valve body return oil passage, and the return oil port T. This connects the left control chamber 25 to the oil tank, causing a decrease in oil pressure within the left control chamber 25. The hydraulic pressure exerted on the main valve core 5 by the oil in the left control chamber 25 decreases to the right, while the oil in the right control chamber 20... The hydraulic pressure remains constant, and the hydraulic pressure acting on the main valve core 5 to the left also remains constant. Therefore, the main valve core 5 is subjected to a resultant force to the left, and the main valve core 5 moves to the left. Through the left feedback rod 2 and the left feedback slider 1, it pushes the control valve sleeve 6 to the right, causing the left control valve port 24 to gradually close. During this process, the pressure in the left control chamber 25 gradually increases. When the left control valve port 24 is completely closed, the oil pressure in the left control chamber 25 is equal to the oil pressure in the right control chamber 20. The hydraulic pressure on both ends of the main valve core 5 is equal, and the main valve core 5 stops moving. Its displacement is proportional to the control valve core. When the main valve core moves to the left, the main valve throttle port A2 and the main valve throttle port B2 close, and the main valve throttle port A1 opens and connects to the left high-pressure oil chamber 26. The high-pressure oil in the chamber flows through the main valve throttle port A1 to the control port A and into the load end. Meanwhile, the main valve throttle port B1 opens and connects to the return oil chamber T. The oil at the other end of the load flows back to the oil tank through the control port B, the main valve throttle port B1, and the return oil chamber T.

[0041] When the load pressure difference is constant, the valve's output flow rate is proportional to the displacement of the main valve core, and the displacement of the main valve core is proportional to the displacement of the control valve core. The ratio is the transmission ratio of the feedback mechanism composed of the feedback rod and the feedback slider. The displacement of the control valve core is also proportional to the input command. Therefore, the output flow rate of the entire valve is proportional to the magnitude of the input command, and the direction and polarity of the input command are the same.

[0042] The foregoing has shown and described the main features, usage methods, basic principles, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention based on actual circumstances without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A piezoelectric ring-bend actuated two-stage spool valve electro-hydraulic servo valve, characterized by, The utility model provides a kind of valve positioner, including left feedback slider (1), left feedback rod (2), main valve sleeve (3), left control valve core (4), main valve core (5), control valve sleeve (6), connecting rod (7), wire slot (8), right control valve core (9), right feedback rod (10), right feedback slider (11), piezoelectric ring (12), support seat (13), zero setting nut (14), right end cover (15), output rod (16), valve body (17), LVDT core (18), electrical shell (19);Left control valve core (4) and right control valve core (9) are all arranged in control valve sleeve (6), and two are connected by connecting rod (7) screw thread, the side surface of piezoelectric ring (12) is glued on valve body (17) by epoxy resin, its inner hole is glued with support seat (13) by epoxy resin, the two ends of output rod (16) are connected with the one end of support seat (13) and the one end of right control valve core (9) respectively, the other end of right control valve core (9) and the one end of left control valve core (4) are connected by connecting rod (7) and form control valve core assembly, the control valve core assembly is located in control valve sleeve (6), the other end of left control valve core (4) is connected with LVDT core (18) screw thread;Left control valve core (4) side is provided with first annular groove (4-1), left control valve core (4) is opened in first oil return hole (4-2), and the middle part is left control valve core inner cavity (4-3) communicated with the screw hole at both ends;Right control valve core (9) side is provided with second annular groove (9-1), and its inside is opened in second oil return hole (9-2), and the middle part is right control valve core inner cavity (9-3) communicated with the screw hole at both ends;The control valve sleeve (6), main valve core (5), main valve sleeve (3) are sequentially arranged in valve body (17) from inside to outside, the two ends of control valve sleeve (6) are inclined plane, one end of left feedback rod (2) is connected with one end of main valve core (5), the other end of left feedback rod (2) is inclined plane, and is contacted and connected with the upper end surface of left feedback slider (1), the lower end surface of left feedback slider (1) is contacted and connected with the one end surface of control valve sleeve (6), one end of right feedback rod (10) is connected with the other end of main valve core (5), the other end surface of right feedback rod (10) is inclined plane, and is contacted and connected with the upper end surface of right feedback slider (11), the lower end surface of right feedback slider (11) is contacted and connected with the other end surface of control valve sleeve (6);The diameter of connecting rod (7) is less than the diameter of control valve core, and one end of connecting rod (7) has left oil return channel (7-1) communicated with left control valve core inner cavity (4-3), left oil return channel (7-1) is communicated with control valve oil return cavity (27) formed in connecting rod (7) and control valve sleeve (6) through left oil return hole (7-3) on side wall, and the other end of connecting rod is provided with right oil return channel (7-2) communicated with right control valve core inner cavity (9-3), and right oil return channel (7-2) is communicated with control valve oil return cavity (27) through right oil return hole (7-4) on side wall.The control valve sleeve (6) is internally provided with a left annular groove and a right annular groove, a left control valve core (4) on the first annular groove right end and the control valve sleeve (6) on the left annular groove left end constitute a left control valve port (24), the right control valve core (9) on the second annular groove left end and the control valve sleeve (6) on the right annular groove right end constitute a right control valve port (21); The control valve core assembly is driven by piezoelectric ring (12) bending, constitutes control spool, its displacement is detected by LVDT sensor, after conditioning circuit conditioning, feedback to the controller forms the electric feedback closed loop control to control valve core assembly displacement; The main valve core (5) and the main valve sleeve (3) constitute the power stage spool valve, the main valve core (5) promotes the displacement feedback mechanism by left feedback rod (2) and left feedback slider (1) or right feedback rod (10) and right feedback slider (11) constitute the displacement feedback mechanism drive control valve sleeve (6) reverse movement, make control valve sleeve (6) and left control valve core (4) and right control valve core (9) form the control main valve core (5) movement left control valve port (24) and right control valve port (21) gradually close, when control valve port is completely closed, the main valve core (5) stops moving, forms the mechanical feedback closed loop control to the main valve core (5) position, so that the main valve core displacement and control valve core displacement are proportional, the ratio is the transmission ratio of feedback mechanism.

2. A piezoelectric ring bend actuated two-stage spool valve electro-hydraulic servo valve as claimed in claim 1, characterized in that, The main valve core (5) is connected with the left feedback rod (2) and the right feedback rod (10) through one or more threaded holes at both ends.

3. A piezoelectric ring bend actuated two-stage spool valve electro-hydraulic servo valve as claimed in claim 1, characterized in that, The left control valve core (4) and the right control valve core (9) are both provided with threaded holes for threaded connection with the connecting rod (7).

4. A piezoelectric ring bend actuated two-stage spool valve electrohydraulic servo valve as claimed in claim 1, characterized in that, The number of the left feedback rod (2) and the right feedback rod (10) is 1-4, and the included angle between the inclined plane of the left end of the left feedback rod (2) and the right end of the right feedback rod (10) and the horizontal direction is less than 45°, and the inclination angle of the inclined plane of the lower end of the left feedback slider and the right feedback slider is greater than 45°.

5. A piezoelectric ring bend actuated two-stage spool valve electrohydraulic servo valve as claimed in claim 1, characterized in that, The output rod (16) is threadedly connected with the support seat (13), the threads of the two are thin threads, zero adjustment is completed by rotating the output rod (16), and after zero adjustment is completed, the two are locked by the zero adjustment nut (14).

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