Two-stage closed-loop controlled high-flow electro-hydraulic servo valve and control method

Abstract

The invention relates to the technical field of hydraulic control, in particular to a two-stage closed-loop control high-flow electro-hydraulic servo valve and a control method. Comprising a main valve body internally provided with a valve sleeve mounting hole; a main valve oil inlet communicated with the valve sleeve mounting hole is formed in one side of the main valve body, and a main valve oil outlet communicated with the valve sleeve mounting hole is formed in the other side of the main valve body; a pair of main valve working oil ports communicated with the valve sleeve mounting hole is formed in the bottom of the main valve body; the valve sleeve is arranged in the valve sleeve mounting hole, and a valve element hole is formed in the valve sleeve; a plurality of sets of oil passing windows which are through in the radial direction are distributed in the valve sleeve in the axial direction, the oil passing windows are symmetrically arranged in the circumferential direction of the valve sleeve, and an annular sealing piece groove is formed between every two adjacent oil passing windows. A P valve sleeve oil cavity, an A valve sleeve oil cavity, a B valve sleeve oil cavity and a pair of T valve sleeve oil cavities on the valve sleeve are isolated from one another through valve body sealing rings on annular sealing piece grooves, and oil liquid is prevented from flowing into the cavities. According to the high-flow electro-hydraulic servo valve, a two-stage electro-hydraulic position closed-loop control structure is adopted, and the high-frequency, high-flow and high-precision hydraulic control requirements are met.

Description

Technical Field

[0001] This invention relates to the field of hydraulic control technology, and in particular to a high-flow electro-hydraulic servo valve with two-stage closed-loop control and a control method thereof. Background Technology

[0002] As a core control component in hydraulic systems, electro-hydraulic servo valves are widely used in high-frequency, high-precision hydraulic systems that require high response speed and control accuracy. Their performance directly determines the control stability and operational reliability of the entire hydraulic system, making them a key component for achieving precise control in high-end hydraulic equipment.

[0003] Currently, the market for commonly used electro-hydraulic servo valves in the industrial sector is dominated by products from well-known American and German manufacturers. Taking the G761-3500 series electro-hydraulic servo valve from a certain American manufacturer as an example, this series of products can only achieve a maximum flow rate of 100 liters / minute under a system pressure of 21 MPa. These commonly used specifications, due to their large production scale, have the advantages of relatively low price and short delivery cycle, and can meet the needs of conventional small-to-medium flow hydraulic systems, but cannot adapt to the control requirements of large-flow hydraulic systems.

[0004] As industrial equipment develops towards larger scale and higher efficiency, many industrial scenarios urgently require hydraulic systems with high flow control. These systems demand flow rates from electro-hydraulic servo valves far exceeding those of commonly used products. However, existing high-flow electro-hydraulic servo valves suffer from high prices and extremely long delivery cycles due to limited market demand and complex manufacturing processes. Furthermore, the technical parameters of imported products are difficult to fully match the actual operating conditions of domestic equipment, resulting in their inability to effectively meet the needs of relevant industrial scenarios. This severely restricts the research, development, production, and upgrading of equipment in this field, becoming a core technological bottleneck. Therefore, a highly adaptable high-flow electro-hydraulic servo valve solution that can address these pain points is urgently needed. Summary of the Invention

[0005] To address the above problems, this invention provides a high-flow electro-hydraulic servo valve and control method with a two-stage closed-loop control, using a conventional small-flow electro-hydraulic servo valve as the pilot stage and a main valve spool position closed loop as the core, to achieve high-frequency, high-flow, and high-precision control requirements.

[0006] The technical solution of this invention is: A high-flow electro-hydraulic servo valve with two-stage closed-loop control includes: The main valve body has a valve sleeve mounting hole inside; one side of the main valve body has a main valve oil inlet communicating with the valve sleeve mounting hole, and the other side has a main valve oil outlet communicating with the valve sleeve mounting hole; the bottom of the main valve body has a pair of main valve working oil ports communicating with the valve sleeve mounting hole. A valve sleeve is disposed within the valve sleeve mounting hole and has a valve core hole inside. The valve sleeve has multiple sets of radially penetrating oil passage windows distributed along the axial direction. The oil passage windows are symmetrically arranged along the circumference of the valve sleeve, and an annular sealing groove is formed between adjacent oil passage windows. The P valve sleeve oil chamber, A valve sleeve oil chamber, B valve sleeve oil chamber and a pair of T valve sleeve oil chambers on the valve sleeve are isolated from each other by the valve body sealing ring on the annular sealing groove to prevent oil from crossing the chambers. The valve core is slidably disposed in the valve sleeve mounting hole and is used to control the on / off switching of the P valve sleeve oil chamber with the A valve sleeve oil chamber or the B valve sleeve oil chamber. The small flow servo valve has an A port, B port, P port, and T port on its main valve body. The A port is connected to one end of the valve core, and oil is supplied through the A port to push the valve core towards the B valve sleeve oil chamber. The B port is connected to the other end of the valve core, and oil is supplied through the B port to push the valve core towards the A valve sleeve oil chamber. An oil inlet accumulator is provided at the oil inlet of the main valve; an oil return accumulator is provided at the oil outlet of the main valve.

[0007] Specifically, the valve sleeve is provided with valve core end caps that can be detachably and fixedly connected at both ends; Both ends of the valve core extend into the valve core end cap on the corresponding side, and are in clearance fit with the inner side wall of the valve core end cap.

[0008] Specifically, the outer circumference of the valve core extending into the valve core end cap is provided with multiple spaced triangular grooves; The main valve body has valve body end caps at both ends that are sealed, detachable and fixedly installed on the outside of the valve core end cap; The valve body end cap is provided with Y-type oil ports.

[0009] Specifically, a displacement sensor is provided at the end of the main valve body in a sealed and fixed connection; The sensor body of the displacement sensor is fixedly connected to the valve body end cover, and the sensor probe is fixedly connected to the valve core.

[0010] Specifically, the valve core end cap is provided with a pair of valve core anti-rotation blocks that are fixedly connected; The valve core end face is provided with a rectangular anti-rotation guide block that is fixedly connected; The anti-rotation guide block is positioned between a pair of valve core anti-rotation blocks.

[0011] Specifically, the main valve body is provided with a main valve inlet valve block that is sealed and fixedly connected to the main valve inlet side; The main valve inlet valve block is provided with an inlet flow channel connecting the main valve inlet port and the main inlet circuit; The oil inlet accumulator is sealed and fixedly installed on the main valve inlet valve block and is connected to the oil inlet flow channel.

[0012] Specifically, the main valve body has a main valve return valve block that is sealed and fixedly connected to the main valve outlet side; The main valve return valve block is provided with a return oil flow channel connecting the main valve outlet and the external main return oil circuit; The return oil accumulator is sealed and fixedly installed on the return oil valve block of the main valve and is connected to the return oil flow channel.

[0013] Specifically, the main valve return valve block is provided with an elliptical oil port facing the main valve outlet.

[0014] Specifically, the bottom of the main valve body is provided with a pair of cylinder connecting plates that are adapted to the working oil port of the main valve.

[0015] A control method for a high-flow electro-hydraulic servo valve with two-stage closed-loop control is described below: S1, pressurized oil is input to port P of the small flow electro-hydraulic servo valve. When the small flow electro-hydraulic servo valve receives the electrical control signal, pressurized oil is output from port A, pushing the valve core of the main valve body to move towards the oil chamber of valve sleeve B. S2, the pressure oil that pushes the valve core toward the oil chamber of valve sleeve B flows into the triangular groove at the end of the valve core, forming an oil film between the valve core and the valve sleeve, and the excess oil is discharged from the Y port of the valve body end cover. S3, the pressure oil at the main valve inlet enters the B valve sleeve oil chamber through the P valve sleeve oil chamber, and is output from the B valve sleeve oil chamber to the actuator. The return oil from the actuator goes through the A valve sleeve oil chamber and the T valve sleeve oil chamber to the oil tank, driving the actuator to complete the forward movement. S4, the displacement sensor detects the position of the valve core in the valve sleeve in real time, and outputs a position feedback signal based on the relative opening degree of the valve core and the valve sleeve to adjust the output flow of the main valve body and realize the control of the movement speed of the actuator; the position feedback signal is fed back to the control end of the small flow electro-hydraulic servo valve to form a closed-loop control of the valve core position, and accurately regulates the displacement of the valve core and the valve opening degree. S5, when the actuator is in position, a reverse electrical control signal is input to the small flow electro-hydraulic servo valve. The pressure oil is output from the B port of the small flow electro-hydraulic servo valve, pushing the valve core to move to the left of the A valve sleeve oil chamber. The pressure oil enters the A valve sleeve oil chamber through the P valve sleeve oil chamber, driving the actuator to complete the reverse action. S6, the inlet accumulator and the return accumulator work synchronously to absorb hydraulic shock, eliminate oil pulsation, and maintain stable oil flow.

[0016] The high-flow electro-hydraulic servo valve disclosed in this invention adopts a two-stage electro-hydraulic position closed-loop control structure, which solves the requirements of high-frequency, high-flow, and high-precision hydraulic control. Its overall structure is integrated by a pilot control stage (small-flow electro-hydraulic servo valve), a main power stage (main valve body and internal components), a position feedback detection unit (displacement sensor), and an oil source buffer unit (return port accumulator and inlet port accumulator). Each unit is precisely connected and works in coordination through valve blocks, internal oil circuits, and mechanical fasteners. A conventional small-flow electro-hydraulic servo valve is used as the pilot stage to drive the main valve core. The triangular groove on the left side of the main valve core can form a hydrostatic support oil film, and excess oil is discharged from the Y port. The inner wall of the valve core end cap is coated with a wear-resistant polymer material with low friction, making the valve core run more smoothly at low speeds and meeting higher precision requirements. A high-precision displacement sensor detects the relative position of the main valve core and valve sleeve in real time and feeds the signal back to the pilot stage of the small-flow electro-hydraulic servo valve to form a closed-loop control of the valve core position. The main valve inlet and return ports are also equipped with inlet accumulators and return accumulators, respectively. The electrical signal after the actuator is in position can be fed back to the pilot stage to trigger the main valve to reverse its action. Through the two-stage cooperation of the pilot stage and the main valve, combined with the position closed-loop control and the buffer and pressure stabilization design of the accumulator, not only is the overall manufacturing cost reduced by relying on the mature characteristics of conventional small-flow electro-hydraulic servo valves, ensuring supply efficiency and operational stability, but also the precise control of the main valve port opening degree is achieved through the real-time feedback and closed-loop control of the high-precision displacement sensor. This allows for precise adjustment of the output flow rate to achieve stepless control of the actuator speed. At the same time, the circular valve sleeve structure facilitates the control of the fit clearance and relative position between the valve core, valve sleeve and end cap, making it easy to ensure operating accuracy and frequency. The synchronous operation of the accumulators at the oil port and return port effectively absorbs hydraulic shocks and eliminates oil pulsation. This stabilizes the oil supply pressure of the pilot stage and the oil flow state of the main valve, avoiding control deviations caused by pressure fluctuations. It also buffers the valve core reversing impact and prevents pilot stage overload. Simultaneously, it optimizes the stability of the hydrostatic support oil film, reduces the frictional resistance of the valve core movement, and makes the main valve operating frequency closer to the natural frequency of the small-flow electro-hydraulic servo valve, fully leveraging the advantages of high-frequency response. Furthermore, it enhances the anti-interference capability of closed-loop control, suppresses valve core position jitter, and ensures positioning accuracy and repeatability. In addition, this structure requires only a small flow of control oil from the pilot stage to stably drive the main valve core, reducing drive energy consumption. Overall, it solves the application requirements of high-frequency, high-flow, and high-precision servo valves, adapting to various industrial conditions with high requirements for high-flow hydraulic drive and speed and position control accuracy. This effectively extends the service life of the valve assembly and improves the overall operating efficiency of the hydraulic system. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the valve core of the present invention when it is in the neutral position; Figure 2 This is a schematic diagram of the structure in which the oil chamber of valve P and the oil chamber of valve B are connected. Figure 3 This is a schematic diagram of the structure in which the oil chamber of valve P and the oil chamber of valve A are connected. Figure 4 This is a schematic diagram of the three-dimensional structure of the present invention in its disassembled state; Figure 5 This is a three-dimensional schematic diagram of the main valve body. Figure 1 ; Figure 6 This is a three-dimensional schematic diagram of the main valve body. Figure 2 ; Figure 7 This is a schematic diagram of the top surface structure of the main valve body; Figure 8 yes Figure 7 Schematic diagram of the cross section along line A in the middle; Figure 9 yes Figure 7 Schematic diagram of the cross section along the B direction; Figure 10 This is a schematic diagram of the three-dimensional structure of the valve sleeve; Figure 11 This is the main view of the valve sleeve; Figure 12 yes Figure 11 Schematic diagram of the cross-sectional structure along the C-axis; Figure 13 This is a schematic diagram of the valve core structure; Figure 14 This is a schematic diagram of the valve core located inside the valve sleeve. Figure 15 yes Figure 14 Enlarged structural diagram of the circular region; Figure 16 This is a hydraulic schematic diagram of the present invention; In the diagram, 100 is the main valve body, 110 is the valve sleeve mounting hole, 120 is the main valve inlet, 130 is the main valve outlet, and 140 is the main valve working port. 200 is the valve sleeve, 210 is the valve core hole, 220 is the oil passage window, and 230 is the annular seal groove. 300 is the valve core, 400 is the small flow servo valve, 500 is the inlet accumulator, and 600 is the return accumulator. 710 is the valve core end cap, 711 is the valve core anti-rotation block, 712 is the anti-rotation guide block, 720 is the valve body end cap, 721 is the Y-port, 800 is the displacement sensor, 910 is the main valve inlet valve block, 920 is the main valve return valve block, and A00 is the cylinder connecting plate. Detailed Implementation

[0018] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0019] In the description of this invention, it should be understood that the terms "upper," "lower," "left," "right," "vertical," and "horizontal," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0020] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0021] The following is for reference. Figure 1-16 Describe embodiments of the present invention; A high-flow electro-hydraulic servo valve with two-stage closed-loop control includes: The main valve body 100 serves as the supporting base for the entire servo valve and has a valve sleeve mounting hole 110 inside. One side of the main valve body 100 has a main valve inlet 120 communicating with the valve sleeve mounting hole 110, and the other side has a main valve outlet 130 communicating with the valve sleeve mounting hole 110. The bottom of the main valve body 100 has a pair of main valve working ports 140 communicating with the valve sleeve mounting hole 110. The main valve working ports 140 are usually designated as working port A and working port B. The valve sleeve 200 is a cylindrical rotary structure, fixedly installed in the valve sleeve mounting hole 110, and has a valve core hole 210 inside. The valve sleeve 200 has multiple sets of radially penetrating oil passage windows 220 distributed along the axial direction. The oil passage windows 220 are symmetrically arranged along the circumference of the valve sleeve, and there is an annular sealing groove 230 between adjacent oil passage windows 220. The valve body sealing ring on the annular sealing groove 230 isolates the P valve sleeve oil chamber, A valve sleeve oil chamber, B valve sleeve oil chamber and a pair of T valve sleeve oil chambers on the valve sleeve 200 from each other to prevent oil from crossing the chambers. In this case, a pair of T-valve sleeve oil chambers are located on both sides of the P-valve sleeve oil chamber; the A-valve sleeve oil chamber is connected to the A working oil port; the B-valve sleeve oil chamber is connected to the B working oil port; multiple anti-rotation positioning pin holes are machined on both end faces of the valve sleeve 200, which are used to cooperate with the corresponding pin holes of the sensor cover and the valve body end cover. The anti-rotation positioning pins realize the circumferential positioning of the valve sleeve and prevent the valve sleeve 200 from rotating and causing the oil port to be misaligned.

[0022] The valve core 300 is slidably disposed in the valve sleeve mounting hole 110 and is used to control the on / off switching of the P valve sleeve oil chamber with the A valve sleeve oil chamber or the B valve sleeve oil chamber. like Figure 1 As shown, when the valve core 300 is in the neutral position, the P valve sleeve oil chamber is not connected to the A valve sleeve oil chamber and the B valve sleeve oil chamber on the side.

[0023] like Figure 2 As shown, valve core 300 moves to the right in the direction shown in the figure, the oil chamber of valve sleeve P is connected to the oil chamber of valve sleeve B, and the oil chamber of valve sleeve A is connected to the adjacent oil chamber of valve sleeve T.

[0024] like Figure 3 As shown, valve core 300 moves to the left in the direction shown in the figure, and the oil chamber of valve sleeve P is connected to the oil chamber of valve sleeve A, and the oil chamber of valve sleeve B is connected to the adjacent oil chamber of valve sleeve T.

[0025] A small-flow servo valve 400 is installed on the top of the main valve body 100. The main valve body 100 is provided with an A port, a B port, a P port, and a T port corresponding to the small-flow servo valve 400. The A port is connected to one end of the valve core 300, and oil is supplied through the A port to push the valve core 300 to move towards the B valve sleeve oil chamber. The B port is connected to the other end of the valve core 300, and oil is supplied through the B port to push the valve core 300 to move towards the A valve sleeve oil chamber. Specifically, the A port of the conventional small-flow servo valve 400 is connected to the A port on the top surface of the main valve body 100; the B port of the conventional small-flow servo valve 400 is connected to the B port on the top surface of the main valve body 100; the P port of the conventional small-flow servo valve 400 is connected to the P port on the top surface of the main valve body 100, such as... Figure 5As shown, the P-port on the top surface of the main valve body 100 passes through an internal L-shaped oil passage to the top of the main valve inlet 120. Oil enters through the A-port or B-port on the top surface of the main valve body 100, controlling the axial movement of the valve core 300 to change the oil opening degree, thereby regulating the flow rate of the main valve. The inner hole of the valve sleeve is a high-precision cylindrical hole, forming a micron-level precision clearance fit with the outer cylindrical surface of the valve core 300, ensuring smooth and unobstructed sliding of the valve core while achieving clearance sealing and reducing internal leakage. The servo valve is used in high-frequency or high-precision applications. The valve core 300 moves at high frequency in the main valve body 100 and the valve sleeve 200. To consider the processing technology, the service life of the friction pair, and to prevent jamming caused by frictional heat between the valve core 300 and the valve sleeve 200 and valve core end cover 710 during operation, the valve core 300, valve sleeve 200, and valve core end cover 710 are made of the same material, such as 40Cr alloy structural steel or 20CrMnTi alloy structural steel.

[0026] An oil inlet accumulator 500 is provided at the oil inlet 120 of the main valve; an oil return accumulator 600 is provided at the oil outlet 130 of the main valve.

[0027] The configuration of the inlet accumulator 500 and the return accumulator 600 has a crucial positive impact on the switching action of the small flow servo valve 400 driving the valve core 300, as detailed below: 1. As a pilot stage, the small flow servo valve 400 is highly sensitive to fluctuations in the oil supply pressure in terms of valve core displacement and output flow. If the pressure at the main valve inlet P pulsates / impacts due to sudden load changes or valve core 300 reversal, it will directly cause the oil supply pressure at the P port of the small flow servo valve to become unstable, which in turn causes deviations in the output flow of the servo valve and fluctuations in the driving thrust of valve core 300, affecting the reversing accuracy and response speed.

[0028] The inlet accumulator 500 is connected to the main valve inlet 120 pipeline. It can absorb pressure shocks on the inlet side in real time and compensate for pressure fluctuations. It provides a constant and stable pilot oil supply pressure for the small flow servo valve 800, ensuring that the output flow of the servo valve is strictly linearly correlated with the electrical control signal. It eliminates the valve core 300 drive deviation caused by pressure fluctuations from the root, and improves the consistency and controllability of the switching action.

[0029] The return oil accumulator 600 is connected to the return oil pipeline at the main valve outlet 130. It can stabilize the return oil back pressure, prevent the pressure shock / pulsation on the return oil side from being transmitted back to the return oil port of the small flow servo valve, prevent the control failure caused by the pressure buildup in the servo valve return oil, and ensure the smooth flow of the pilot control oil.

[0030] 2. At the moment of reversal, the valve core 300 will generate a violent hydraulic shock due to the large flow of the main valve and the sudden change in the load of the actuator. This shock will act in reverse on the control end of the small flow servo valve 800, causing the servo valve core to be subjected to sudden force, resulting in "sticking" or "overshooting". At the same time, it may cause overload of the internal components of the servo valve.

[0031] The accumulator can quickly absorb the instantaneous hydraulic shock during the switching and start-stop process of the valve core 300, greatly reducing the impact of the shock pressure on the small flow servo valve, avoiding the performance degradation of the servo valve due to shock overload, and at the same time buffering the switching acceleration of the valve core 300, making the movement of the valve core 300 smoother, without "jerking" or "shaking", and improving the smoothness of the switching action.

[0032] The smooth movement of the valve core 300 further reduces the control load of the low-flow servo valve. The servo valve only needs to output precise low-flow control oil to stably drive the valve core 300, without having to deal with the additional thrust required by the impact, thus extending the service life of the low-flow servo valve.

[0033] 3. When valve core 300 switches, the large flow rate of the main valve will cause a sudden change in the flow rate on the oil inlet side, resulting in insufficient oil supply to the P port of the small flow servo valve, which leads to insufficient output flow of the servo valve and delay in switching of valve core 300.

[0034] The inlet accumulator 500 can quickly release the stored pressure oil when the flow rate changes instantaneously, to compensate for the instantaneous oil supply demand of the small flow servo valve, ensuring that the servo valve always has sufficient pressure oil to drive the valve core 300, avoiding switching delay and slow response caused by insufficient oil supply, and ensuring the speed and reliability of valve core 300 switching.

[0035] The return oil accumulator 600 can quickly absorb the instantaneous large flow on the return oil side, avoiding the return oil blockage caused by poor return oil flow in the valve core 300, and further ensuring the smooth switching of the valve core 300.

[0036] In this case, valve sleeve 200 is provided with valve core end caps 710 that can be detachably and fixedly connected at both ends; The two ends of the valve core 300 extend into the valve core end cap 710 on the corresponding side, and are in clearance fit with the inner side wall of the valve core end cap 710 coated with polymer material; the polymer material is a modified polytetrafluoroethylene material filled with copper powder / molybdenum disulfide / carbon fiber, which is fixed to the metal substrate of the valve core end cap 710 by plasma spraying / adhesive composite process.

[0037] The circular valve sleeve 200 is interference-fitted into the valve sleeve mounting hole 110, achieving precise coaxial positioning between the valve sleeve 200 and the main valve body 100. The valve core 300 is slidably fitted inside the circular valve sleeve 200, and can move left and right along the axial direction of the valve sleeve 200. Compared with the traditional structure, the circular valve sleeve 200 structure makes it easier to control the fitting clearance and relative position dimensions between the valve core 300, the valve sleeve 200, and the valve core end cover 200, effectively ensuring the movement accuracy and response frequency of the valve core 300.

[0038] The valve core 300 has multiple spaced triangular grooves on its outer circular surface that extends into the valve core end cover 710. When pressurized oil flows through this area, the oil is stored in the triangular groove. On the one hand, this enables the valve core to automatically center itself within the valve sleeve, ensuring the coaxiality of the valve core 300 and the valve sleeve 200. On the other hand, it forms a stable oil film between the valve core 300 and the valve sleeve 200. The lubricating effect of the oil film further reduces the frictional loss between the valve core 300 and the valve sleeve 200 during high-frequency operation, ensuring the smooth movement of the valve core 300 and avoiding problems such as jamming and wear caused by excessive frictional resistance, thus extending the service life of the friction pair.

[0039] The main valve body 100 has valve body end caps 720 that are sealed and detachably fixed to the outside of the valve core end cap 710 at both ends. The valve body end cover 720 is provided with Y-ports 721. In this case, the valve body end cover 720 is fixed to the side of the main valve body 100 by screws and presses against the valve sleeve 200; the valve body end cover 720 and the valve core end cover 710 are connected by anti-rotation positioning pins.

[0040] The main valve body 100 is provided with a displacement sensor 800 that is sealed and fixedly connected at its end; the sensor body of the displacement sensor 800 is fixedly connected to the valve body end cover 720, and the sensor probe is fixedly connected to the valve core 300.

[0041] In order to match the rapid response of the electrical signal from the high-precision displacement sensor 800, the high-frequency motion valve core 300 must have very low operating resistance, while ensuring that a small hydraulic thrust is required to drive the valve core 300. This requires a reasonable fit clearance between the valve core 300 and the valve sleeve 200, and between the valve core 300 and the valve core end cover 710. Figure 14 As shown, the valve core 300 adopts a symmetrical structure design, wherein the gap between the valve core 300 and the valve core end cover 710 in the K1 area is 0.03mm, the gap between the valve core 300 near the end in the K2 area and the valve sleeve 200 is 0.01mm, and the gap between the valve core 300 near the middle in the K3 area and the valve sleeve 200 is 0.02mm.

[0042] The valve core 300 adopts a symmetrical structural design with differentiated clearances in different mating areas: the clearance in area K1 between the valve core 300 and the valve core end cover 710 is 0.03mm; the clearance between area K2 near the end of the valve core 300 and the valve sleeve 200 is 0.01mm; and the clearance between area K3 near the middle of the valve core 300 and the valve sleeve 200 is 0.02mm. This differentiated clearance design is specifically set based on the working characteristics, mating requirements, and sealing requirements of the valve core 300. During high-frequency reciprocating motion, the force, friction intensity, and sealing requirements of different areas of the valve core 300 vary.

[0043] The K1 area is the mating area between the valve core and the end cover. Its main function is to limit and guide, without having to perform the core sealing function. A certain gap needs to be reserved to compensate for assembly errors and thermal expansion. The 0.03mm gap effectively compensates for dimensional errors during assembly and thermal expansion caused by the high-frequency movement of the valve core, preventing the valve core 300 from jamming with the valve core end cover 710 due to thermal expansion and contraction, while ensuring the guiding accuracy of the valve core.

[0044] The K2 zone is located at the end of the valve core and is the main friction area for the high-frequency movement of the valve core 300. The minimum clearance of 0.01mm maximizes the end sealing performance, reduces internal leakage of hydraulic oil, ensures the accuracy of servo valve flow control, and enhances the wear resistance of the end friction pair, extending the service life of the components.

[0045] The K3 zone, located in the middle of the valve core 300, is the core area for flow regulation. It needs to ensure both sealing performance and smooth valve core movement, avoiding jamming caused by excessively small gaps. Therefore, the gap is set between that of the K1 and K2 zones. This 0.02mm intermediate gap achieves a balance between sealing performance and smooth movement, reducing leakage losses during flow regulation while avoiding problems such as increased frictional resistance, overheating, and jamming caused by excessively small gaps. Simultaneously, the symmetrical structure of the valve core 300 combined with the differentiated gap design ensures uniform force distribution, preventing uneven wear and jamming during high-frequency movement.

[0046] In terms of structural design, in order to effectively reduce the friction between the valve core and the valve sleeve, a design approach of reducing the contact area between the two is adopted. For example, a certain taper is designed in the K2 and K3 areas of the valve core. By reducing the contact area, the frictional resistance is reduced structurally.

[0047] like Figure 14 When the valve core 300 is in the middle position within the valve sleeve 200, axial disconnection structures are formed between the P valve sleeve oil chamber and the A valve sleeve oil chamber, and between the P valve sleeve oil chamber and the B valve sleeve oil chamber, respectively. The axial dimension of this disconnection gap is the disconnection connection surface D; wherein, the disconnection connection surface between the A valve sleeve oil chamber and the P valve sleeve oil chamber is denoted as D. a The disconnected connection surface between the oil chamber of valve sleeve B and the oil chamber of valve sleeve P is denoted as Dᵦ. The value of D when the valve core is in the middle position of the valve sleeve is a key factor affecting the accuracy of the servo valve. A large D value results in a longer valve core movement time and poorer servo valve sensitivity. A small D value increases the repeatability requirement after valve core operation and reset; a slightly poor repeatability after reset may affect the overall valve operation. For example, after reset, the oil chambers of valve sleeve P and A should not be connected. If the D value is too small, the oil chambers of valve sleeve P and A may become connected. Therefore, in this case, D... a =Dᵦ, where D takes the value of 0.2mm≤D≤0.5mm.

[0048] The valve core end cap 710 on the side away from the displacement sensor 800 is provided with a pair of valve core anti-rotation blocks 711 that are fixedly connected; the valve core 300 end face is provided with a rectangular anti-rotation guide block 712 that is fixedly connected; the anti-rotation guide block 712 is limited between the pair of valve core anti-rotation blocks 711.

[0049] The main valve body 100 has a main valve inlet valve block 910 with a sealed and fixed connection on the side of the main valve inlet port 120; the main valve inlet valve block 910 has an inlet flow channel that connects the main valve inlet port 120 and the main inlet circuit; the inlet accumulator 500 is sealed and fixedly installed on the main valve inlet valve block 910 and is connected to the inlet flow channel.

[0050] The main valve body 100 has a main valve return valve block 920 on the main valve outlet 130 side, which is sealed and fixedly connected; the main valve return valve block 920 has a return oil flow channel that connects the main valve outlet 130 with the external main return oil circuit; the return oil accumulator 600 is sealed and fixedly installed on the main valve return valve block 920 and is connected to the return oil flow channel.

[0051] The main valve return valve block 920 is provided with an elliptical oil port on the side facing the main valve outlet 130, which is used to collect the oil from the two main valve outlets 130 and flow into the return oil channel.

[0052] The bottom of the main valve body 100 is provided with a pair of cylinder connecting plates A00 that are adapted to the working oil port 140 of the main valve. The top surface of the cylinder connecting plate A00 is provided with a pair of working oil ports A corresponding to the working oil port 140 of the main valve, and the two sides are respectively provided with working oil passages A that communicate with the corresponding working oil ports A.

[0053] A control method for a high-flow electro-hydraulic servo valve with two-stage closed-loop control is disclosed. The high-flow electro-hydraulic servo valve adopts a pilot-operated closed-loop control structure, using a conventional low-flow electro-hydraulic servo valve as the pilot stage. The main valve is equipped with a high-precision displacement sensor to form a position closed loop, and pressure stabilization is achieved in conjunction with inlet / return port accumulators. It combines the technical advantages of high-flow output, high-frequency response, and high-precision control. Its complete working method is as follows: S1, pressurized oil is input to port P of the small-flow electro-hydraulic servo valve 400. When the small-flow electro-hydraulic servo valve 400 receives an electrical control signal, pressurized oil is output from port A, pushing the valve core 300 of the main valve body 100 to move towards the oil chamber of the valve sleeve B. Figure 1-2 As shown; S2, the pressure oil pushing the valve core 300 toward the oil chamber of valve sleeve B flows into the triangular groove at the end of the valve core 300, forming an oil film between the valve core 300 and the valve sleeve 200, and the excess oil is discharged from the Y port of the valve body end cover 720. S3, the pressure oil at the main valve inlet 120 enters the B valve sleeve oil chamber through the P valve sleeve oil chamber, and is output from the B valve sleeve oil chamber to the actuator. The return oil from the actuator goes through the A valve sleeve oil chamber and the T valve sleeve oil chamber to the oil tank, driving the actuator to complete the forward movement. S4, the displacement sensor 800 detects the position of the valve core 300 in the valve sleeve 200 in real time, and outputs a position feedback signal based on the relative opening degree of the valve core 300 and the valve sleeve 200, thereby adjusting the output flow of the main valve body 100 and realizing the control of the movement speed of the actuator; the position feedback signal is fed back to the control terminal of the small flow electro-hydraulic servo valve 400 to form a closed-loop control of the valve core 300 position, and precisely regulate the displacement of the valve core 300 and the valve opening degree; S5, when the actuator is in position, a reverse electrical control signal is input to the small-flow electro-hydraulic servo valve 400, and pressurized oil is output from port B of the small-flow electro-hydraulic servo valve 400, such as Figure 3 As shown, the valve core 300 is pushed to move to the left of the A valve sleeve oil chamber, and the pressure oil enters the A valve sleeve oil chamber through the P valve sleeve oil chamber, driving the actuator to complete the reverse action; S6, the inlet accumulator 500 and the return accumulator 600 work synchronously to absorb hydraulic shock, eliminate oil pulsation, and maintain stable oil flow.

[0054] This project uses a conventional small-flow electro-hydraulic servo valve 400 as the pilot stage, replacing the dedicated large-flow servo valve, significantly reducing manufacturing costs. It also leverages mature products to ensure stable performance and short delivery cycles. A high-precision displacement sensor 800 provides real-time feedback on the valve core position, forming a fully closed-loop control system. This results in high precision control of the main valve orifice opening and accurate speed adjustment of the actuator. The response frequency of the main valve core 300 is determined by the pilot-stage small-flow servo valve, theoretically enabling high-frequency operation consistent with the small-flow servo valve, meeting the demands of high-frequency, high-flow conditions. The use of a circular valve sleeve 200 structure facilitates precise control of the fit clearance between the valve core 300, the valve sleeve 200, and the end cap, ensuring operational accuracy. The hydrostatic oil film formed by the triangular grooves on the outer surfaces of the valve core 300 reduces frictional resistance. Combined with the pressure buffering of the inlet / return oil accumulator, this effectively suppresses hydraulic shock and pulsation, improving valve lifespan and control stability.

[0055] Regarding the information disclosed in this case, the following points need to be clarified: (1) The accompanying drawings of the embodiments disclosed in this case only involve the structures involved in the embodiments disclosed in this case. Other structures can refer to the general design. (2) Where there is no conflict, the embodiments and features disclosed in this case can be combined with each other to obtain new embodiments; The above are merely specific embodiments disclosed in this case, but the scope of protection of this disclosure is not limited thereto. The scope of protection disclosed in this case shall be determined by the scope of protection of the claims.

Claims

1. A high-flow electro-hydraulic servo valve with two-stage closed-loop control, characterized in that, include: The main valve body (100) has a valve sleeve mounting hole (110) inside; one side of the main valve body (100) has a main valve inlet (120) communicating with the valve sleeve mounting hole (110), and the other side has a main valve outlet (130) communicating with the valve sleeve mounting hole (110); the bottom of the main valve body (100) has a pair of main valve working ports (140) communicating with the valve sleeve mounting hole (110). A valve sleeve (200) is disposed in the valve sleeve mounting hole (110) and has a valve core hole (210) inside. The valve sleeve (200) has multiple sets of radially penetrating oil passage windows (220) distributed along the axial direction. The oil passage windows (220) are symmetrically arranged along the circumference of the valve sleeve, and there is an annular sealing groove (230) between adjacent oil passage windows (220). The valve body sealing ring on the annular sealing groove (230) isolates the P valve sleeve oil chamber, A valve sleeve oil chamber, B valve sleeve oil chamber and a pair of T valve sleeve oil chambers on the valve sleeve (200) from each other to prevent oil from crossing the chambers. The valve core (300) is slidably disposed in the valve sleeve mounting hole (110) and is used to control the on / off switching of the P valve sleeve oil chamber with the A valve sleeve oil chamber or the B valve sleeve oil chamber. The small flow servo valve (400) has an A port, a B port, a P port, and a T port on its main valve body (100) corresponding to the small flow servo valve (400). The A port is connected to one end of the valve core (300), and oil is supplied through the A port to push the valve core (300) to move towards the B valve sleeve oil cavity. The B port is connected to the other end of the valve core (300), and oil is supplied through the B port to push the valve core (300) to move towards the A valve sleeve oil cavity. An oil inlet accumulator (500) is provided at the oil inlet (120) of the main valve; and a return oil accumulator (600) is provided at the oil outlet (130) of the main valve.

2. The high-flow electro-hydraulic servo valve with two-stage closed-loop control according to claim 1, characterized in that, The valve sleeve (200) is provided with valve core end caps (710) that can be detachably and fixedly connected at both ends. The two ends of the valve core (300) extend into the valve core end cap (710) on the corresponding side, and are in clearance fit with the inner side wall of the valve core end cap (710).

3. The high-flow electro-hydraulic servo valve with two-stage closed-loop control according to claim 2, characterized in that, The valve core (300) has multiple spaced triangular grooves on its outer circular surface that extends into the valve core end cap (710); The main valve body (100) is provided with seals at both ends, which can be detachably fixed, and the valve body end cover (720) is located outside the valve core end cover (710). The valve body end cap (720) is provided with Y oil port (721).

4. A high-flow electro-hydraulic servo valve with two-stage closed-loop control according to claim 3, characterized in that, The main valve body (100) is provided with a displacement sensor (800) that is sealed and fixedly connected at its end. The sensor body of the displacement sensor (800) is fixedly connected to the valve body end cap (720), and the sensor probe is fixedly connected to the valve core (300).

5. A high-flow electro-hydraulic servo valve with two-stage closed-loop control according to claim 2, characterized in that, The valve core end cap (710) is provided with a pair of valve core anti-rotation blocks (711) that are fixedly connected. The valve core (300) end face is provided with a rectangular anti-rotation guide block (712) that is fixedly connected; The anti-rotation guide block (712) is positioned between a pair of valve core anti-rotation blocks (711).

6. A high-flow electro-hydraulic servo valve with two-stage closed-loop control according to claim 1, characterized in that, The main valve body (100) is provided with a main valve inlet valve block (910) on the side of the main valve inlet (120) that is sealed and fixedly connected. The main valve inlet valve block (910) is provided with an inlet flow channel connecting the main valve inlet (120) and the main inlet circuit; The oil inlet accumulator (500) is sealed and fixedly installed on the main valve inlet valve block (910) and is connected to the oil inlet channel.

7. A high-flow electro-hydraulic servo valve with two-stage closed-loop control according to claim 1, characterized in that, The main valve body (100) is provided with a main valve return valve block (920) on the side of the main valve outlet (130) that is sealed and fixedly connected. The main valve return valve block (920) is provided with a return oil flow channel connecting the main valve outlet (130) and the external main return oil circuit; The return oil accumulator (600) is sealed and fixedly installed on the main valve return oil block (920) and is connected to the return oil flow channel.

8. A high-flow electro-hydraulic servo valve with two-stage closed-loop control according to claim 7, characterized in that, The main valve return valve block (920) has an elliptical oil port on the side facing the main valve outlet (130).

9. A high-flow electro-hydraulic servo valve with two-stage closed-loop control according to claim 1, characterized in that, The bottom of the main valve body (100) is provided with a pair of cylinder connecting plates (A00) that are adapted to the working oil port (140) of the main valve.

10. A control method for a high-flow electro-hydraulic servo valve with two-stage closed-loop control, applied to the high-flow electro-hydraulic servo valve with two-stage closed-loop control as described in claim 1, characterized in that, The working method is as follows: S1, pressure oil is input to port P of the small flow electro-hydraulic servo valve (400). When the small flow electro-hydraulic servo valve (400) receives the electrical control signal, pressure oil is output from port A, pushing the valve core (300) of the main valve body (100) to move towards the oil chamber of the valve sleeve B. S2, the pressure oil that pushes the valve core (300) toward the oil chamber of valve sleeve B flows into the triangular groove at the end of the valve core (300), forming an oil film between the valve core (300) and the valve sleeve (200), and the excess oil is discharged from the Y port of the valve body end cover (720); S3, the pressure oil from the main valve inlet (120) enters the B valve sleeve oil chamber through the P valve sleeve oil chamber, and is output from the B valve sleeve oil chamber to the actuator. The return oil from the actuator goes through the A valve sleeve oil chamber and the T valve sleeve oil chamber to the oil tank, driving the actuator to complete the forward movement. S4, the displacement sensor (800) detects the position of the valve core (300) in the valve sleeve (200) in real time, and outputs a position feedback signal according to the relative opening degree of the valve core (300) and the valve sleeve (200), and adjusts the output flow of the main valve body (100) to realize the control of the movement speed of the actuator; the position feedback signal is fed back to the control end of the small flow electro-hydraulic servo valve (400) to form a closed-loop control of the valve core (300) position, and accurately regulates the displacement of the valve core (300) and the valve opening degree; S5, when the actuator is in position, a reverse electrical control signal is input to the small flow electro-hydraulic servo valve (400), and the pressure oil is output from the B port of the small flow electro-hydraulic servo valve (400), pushing the valve core (300) to move to the left of the A valve sleeve oil chamber. The pressure oil enters the A valve sleeve oil chamber through the P valve sleeve oil chamber, driving the actuator to complete the reverse action. S6, the inlet accumulator (500) and the return accumulator (600) work synchronously to absorb hydraulic shock, eliminate oil pulsation, and maintain stable oil flow.

Images