Overflow pressure control method for pilot-operated overflow valve and overflow valve system

Abstract

The invention relates to the field of overflow valve automation control, in particular to an overflow pressure control method of a pilot-operated overflow valve and an overflow valve system. The method comprises the steps that firstly, target overflow pressure is set, and overflow flow of a main valve of an overflow valve and displacement of a valve element of a pilot valve are collected; the opening displacement of a main valve element is calculated according to the flow, and the target control oil pressure in a pilot control cavity is determined in combination with the stress balance relation of the main valve element; and then active control force which should be applied to the pilot valve element is calculated based on the stress balance relation of the pilot valve element, and the proportional electromagnet applies the active control force to the pilot valve element, so that the overflow pressure output by the main valve approaches the target overflow pressure. According to the method, the stress state of the main valve and the stress state of the pilot valve are analyzed and modeled, calculation is conducted in combination with flow and displacement measurement, accurate adjustment and stable control over the overflow pressure are achieved, and the pressure stabilizing precision and the dynamic response performance of the system are improved.

Description

Technical Field

[0001] This invention relates to the field of automated control of relief valves, specifically to a method for controlling the overflow pressure of a pilot-operated relief valve and an active compensation pilot-operated relief valve system. Background Technology

[0002] Pilot-operated relief valves are commonly used in hydraulic systems to limit and regulate system pressure. Their basic structure generally includes a two-stage configuration: a main valve and a pilot valve. High-pressure oil in the main system circuit acts on the main valve spool. When the system pressure exceeds the set value, the main valve opens, allowing oil to return to the tank via the relief channel, thus limiting the system pressure within the allowable range. The opening pressure of the main valve is typically determined by the control oil pressure established by the pilot valve and the force of the main valve's return spring.

[0003] In traditional designs, pilot valves are typically spring-loaded and rely on a throttling mechanism to automatically generate a certain control oil pressure. Their pressure setpoint is primarily determined by the spring preload, spring stiffness, and the relevant pressure-bearing area. While this type of pilot-operated relief valve has a mature structure and low cost, it still suffers from the following technical problems: On the one hand, pressure regulation is significantly affected by spring precision and nonlinearity. Factors such as spring manufacturing errors, assembly errors, elastic hysteresis, and fatigue changes during operation can all lead to deviations between the actual pressure and the theoretical set value. Furthermore, the relationship between spring force and displacement is not strictly linear, making it difficult to accurately model and correct pressure regulation and compensation.

[0004] On the other hand, the stress state of the main valve is closely related to the flow rate. When the overflow flow rate changes, the opening displacement of the main valve core also changes, resulting in changes in the flow channel pressure difference, hydraulic force, and valve core balance. Especially under conditions of large flow rate or dynamic load, the main valve core is significantly affected by the hydraulic force, which easily causes the overflow pressure to fluctuate with the flow rate, making it difficult to maintain an approximately constant pressure.

[0005] Therefore, it is necessary to propose a pilot-operated relief valve control method and system that can model the actual force relationship between the main valve and the pilot valve and compensate for the effects of flow changes and spring nonlinearity through active control, so as to improve the stability of relief pressure and control accuracy. Summary of the Invention

[0006] This invention addresses the problems of pressure deviation caused by changes in the force state of the main valve during the overflow pressure regulation process of pilot-operated relief valves, and the difficulty in achieving accurate modeling and compensation relying on spring characteristics. It provides a method and system for controlling the overflow pressure of pilot-operated relief valves. By modeling the force relationship between the main valve core and the pilot valve core, and actively calculating and adjusting the control oil pressure based on real-time detection data, stable control of the overflow pressure is achieved while still using a pilot-operated two-stage valve structure.

[0007] To achieve the above objectives, the present invention provides a method for controlling the overflow pressure of a pilot-operated relief valve, comprising: Set target overflow pressure ; Collect the overflow flow rate of the main valve of the relief valve. ; Collect pilot valve core displacement ; Based on overflow flow Calculate the main valve core opening displacement ; The target control oil pressure is calculated based on the force balance relationship of the main valve core. ; Control oil pressure according to target And the force balance relationship of the pilot valve core, calculate the active control force to be applied to the pilot valve core. ; Apply the active control force to the pilot valve core To make the overflow pressure output by the main valve approach the target overflow pressure. .

[0008] In some implementations, the main valve core opening displacement Based on overflow flow Determined according to the following relationship:

[0009] in: For flow coefficient, Main valve seat bore diameter, The semi-cone angle of the main valve core sealing cone surface. This represents the density of the oil.

[0010] In some implementations, the force balance of the main valve core satisfies the following relationship:

[0011] in: The effective pressure-bearing area of ​​the outer end face of the main valve core, bearing ; The effective pressure-bearing area of ​​the inner end face of the main valve core, bearing ; The stiffness coefficient of the main valve core return spring; The initial pre-compression of the main valve core return spring.

[0012] In some implementations, the force balance of the pilot valve core satisfies:

[0013] in: The pilot valve core pressure-bearing area, bearing ; For the stiffness of the pilot valve core reset spring; It is a constant force.

[0014] In some implementations, a pressure sensor is used to detect the actual control oil pressure. And control the oil pressure according to the actual situation. With target control hydraulic pressure The deviation between them corrects the active control force This enables the actual control of hydraulic pressure. Approaching the target control oil pressure .

[0015] In some implementations, a proportional electromagnet applies an active control force to the pilot valve spool. ; The displacement sensor detects the displacement of the proportional electromagnet armature, and uses the armature displacement to characterize the pilot valve core displacement. .

[0016] This invention also proposes an active compensation pilot-operated relief valve system applying the aforementioned method, comprising: Main valve sleeve and main valve core; Pilot valve body and pilot valve core; The proportional electromagnet, which is directly connected to the pilot valve spool, is used to apply active control force to the pilot valve spool. ; A displacement sensor is installed at the pilot valve to detect the displacement of the pilot valve core or its corresponding armature displacement. A flow sensor installed in the overflow channel is used to detect the overflow flow rate Q; A controller for executing the control method proposed in this invention.

[0017] In some embodiments, the main valve core is connected to the main valve core return spring via a pre-tightening piston. The pre-tightening piston can slide axially and is disposed in the pre-tightening piston sleeve. The main valve core return spring acts on the pre-tightening piston, and the pre-tightening piston transmits axial pre-tightening force to the main valve core. The pre-tightened piston sleeve constrains the radial force generated by the main valve core return spring, thereby preventing the radial force from acting directly on the main valve core.

[0018] In some implementations, the system further includes a pressure sensor connected to the chamber or pipeline containing the control oil pressure for detecting the actual control oil pressure. .

[0019] In some embodiments, the main valve sleeve, pilot valve body, proportional electromagnet, and displacement sensor are connected in series along the same axis. The pilot valve body is mounted on the main valve sleeve; The proportional electromagnet is installed at one end of the pilot valve body, with one end of its armature facing the pilot valve core and being positioned opposite to the pilot valve core. The displacement sensor is located at the other end of the proportional electromagnet armature, and this end of the armature is inserted into the detection cavity of the displacement sensor so that the displacement sensor can detect the axial displacement of the armature.

[0020] Beneficial effects: The overflow pressure control method of the pilot-operated relief valve of the present invention controls the overflow flow rate of the main valve of the relief valve in real time. and pilot valve spool displacement The opening displacement of the main valve core is calculated based on the force balance relationship between the main valve core and the pilot valve core. and target control hydraulic pressure This allows for the calculation of the active control force that should be applied to the pilot valve core. This allows for active adjustment of the pilot valve core position and stress state, ensuring that the overflow pressure output by the main valve continuously approaches and stabilizes at the set target overflow pressure. Compared to traditional relief valves that rely on mechanical spring-hydraulic pressure self-balancing for passive regulation, this method introduces active control force into the regulation process. This significantly improves the dynamic response characteristics and steady-state accuracy of relief pressure control, reduces the impact of system load fluctuations, oil temperature changes, and component wear on relief pressure, and enhances the consistency and reliability of system pressure control. Furthermore, because the control algorithm considers the inherent mechanical relationship between valve core force balance and valve core displacement, the control process more closely reflects actual physical characteristics, reducing the risk of pressure oscillation and overshoot.

[0021] The active compensation pilot-operated relief valve system of the present invention, based on the traditional main valve sleeve, main valve core, and pilot valve structure, is equipped with a proportional electromagnet that is directly connected to the pilot valve core, for applying active control force to the pilot valve core. A displacement sensor is installed at the pilot valve to obtain the displacement of the pilot valve core or armature in real time, and a flow sensor is installed in the overflow channel to detect the overflow flow rate. By combining the controller with the method proposed in this invention, closed-loop active control of the overflow pressure is achieved. Through this system configuration, valve core displacement, overflow flow rate, and control algorithm are tightly coupled to form a complete active compensation control link. This allows the overflow valve to no longer rely solely on mechanical self-balancing to maintain pressure stability, but instead uses an externally adjustable active control force to offset the effects of external disturbances in real time, thereby significantly improving the pressure stability, dynamic adjustment capability, and anti-disturbance capability of the overflow valve. The system structure is simple to implement and easy to engineering apply, achieving a significant improvement in overflow pressure control performance while ensuring system reliability.

[0022] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0023] Figure 1 This is a perspective view of the active compensation pilot-operated relief valve system of the present invention; Figure 2 yes Figure 1 A sectional view of the internal structure; Figure 3 This is an illustration of the internal chambers and flow channels of an active compensation pilot-operated relief valve system; Figure 4 yes Figure 3 A simplified diagram of the pilot chamber and flow channel; Figure 5 This is a schematic diagram of the working process of a pilot-operated relief valve.

[0024] Explanation of reference numerals in the attached figures 1-Displacement sensor housing; 2-Proportional electromagnet housing; 3-Electromagnet coil; 4-Armature; 5-Pilot valve body; 6-Pilot valve core; 7-Pressure sensor; 8-Pilot valve core return spring; 9-Main valve core return spring; 10-Preload piston sleeve; 11-Preload piston; 12-Main valve cover plate; 13-Main valve core; 14-Main valve sleeve; 15-Displacement sensor cover; 16-Displacement sensor; 17-Armature fixing sleeve; 18-Control signal interface. Detailed Implementation

[0025] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0026] In this invention, unless otherwise stated, directional terms such as "upper" and "lower" generally refer to the orientation in the assembled and used state. "Inner" and "outer" refer to the inner and outer sides relative to the outline of each component itself.

[0027] I. Overall Technical Solution This invention provides a technical solution for an active compensation pilot-operated relief valve (see attached document). Figure 1-4 This includes an overflow pressure control method and a pilot-operated overflow valve system for implementing the method. Based on the traditional two-stage pilot-operated overflow valve structure, this technical solution introduces flow detection, displacement detection, and an active force application device, combined with a control algorithm, to achieve active adjustment and real-time compensation of the overflow pressure, thereby improving pressure control accuracy and stability.

[0028] The system as a whole includes a main valve sleeve 14 and a main valve core 13 disposed therein, a pilot valve body 5 and a pilot valve core 6 disposed on the main valve sleeve 14, a proportional electromagnet directly connected to the pilot valve core 6, a displacement sensor 16 for detecting the displacement of the pilot valve core 6 or its corresponding armature 4, a flow sensor disposed in the overflow channel, a pressure sensor 7 (optional) for detecting control oil pressure, and a controller electrically connected to the above components.

[0029] The main valve serves as the main flow channel for overflow oil. The main valve core 13 opens under overflow pressure to establish the main overflow passage. To ensure that the radial force generated by the main valve core return spring 9 during compression does not directly act on the main valve core 13, a preload piston 11 is provided between the main valve core 13 and the return spring. The preload piston 11 transmits the axial preload force to the main valve core 13. Simultaneously, a preload piston sleeve 10 is provided outside the preload piston 11 to constrain the radial force of the return spring, preventing it from interfering with the movement of the main valve core 13. The preload piston 11 can slide axially within the preload piston sleeve 10, thereby achieving stable and reliable spring force transmission.

[0030] A pilot valve is mounted on the main valve sleeve 14. The pilot valve core 6 is used to generate and regulate control oil pressure, which indirectly affects the force state at both ends of the main valve core 13. This invention uses a proportional electromagnet as the active actuator. The proportional electromagnet is directly connected to the pilot valve core 6 axially, with one end of its armature 4 facing and opposite to the pilot valve core 6. By adjusting the current in the proportional electromagnet coil, a controllable active control force is applied to the pilot valve core 6. A displacement sensor 16 is provided at the other end of the proportional electromagnet. Its detection chamber is arranged along the insertion direction of the armature 4 of the proportional electromagnet. The other end of the armature 4 of the proportional electromagnet is inserted into the detection chamber of the displacement sensor 16, thereby realizing the detection of the axial displacement of the armature 4. This displacement can then be used as the displacement of the pilot valve core 6. The representative quantity.

[0031] To achieve closed-loop control of the main valve overflow pressure, this invention incorporates a flow sensor in the overflow channel to detect the main valve overflow flow rate in real time. In a preferred embodiment, a pressure sensor 7 can also be installed in the control oil circuit, connecting the pressure sensor 7 to the chamber or pipeline containing the control oil pressure, for detecting the actual control oil pressure. This provides feedback signals for subsequent compensation control.

[0032] The main valve, pilot valve, proportional electromagnet, and displacement sensor 16 are preferably arranged in series along the same axis, so that the whole structure forms an axial linear force transmission chain, reducing the impact of off-center load and assembly tolerance, and facilitating structural integration and miniaturization.

[0033] In terms of control strategy, the present invention first sets the target overflow pressure in the controller. And collect the overflow flow rate of the main valve of the relief valve in real time. And pilot valve core 6 displacement Based on the detected overflow flow rate Based on the main valve structural parameters (including the main valve seat bore diameter) 13. Main valve core sealing cone surface half cone angle Flow coefficient and oil density (etc.), the opening displacement of the main valve core 13 was calculated. Furthermore, the main valve core 13 is designed to withstand overflow pressure on its outer and inner end faces respectively. With control oil pressure The force balance relationship and the stiffness of the main valve core return spring 9 With pre-compression The target control oil pressure is calculated. .

[0034] Simultaneously, combining the force balance model of the pilot valve core 6, including the controlled pressure application area of ​​the pilot valve core 6... Pilot valve reset spring stiffness Initial constant force Parameters such as these are used by the controller to control the oil pressure according to the target. Calculate the active control force to be applied to the pilot valve core 6. .

[0035] The proportional electromagnet is controlled by the target active force. The corresponding electromagnetic force is output and acts on the pilot valve core 6, so that the control oil pressure is adjusted to a level that meets the force balance requirements of the main valve core 13, thereby making the overflow pressure output by the main valve approach and stabilize at the target overflow pressure. .

[0036] With pressure sensor 7 installed, the controller can also collect the actual control oil pressure in real time. and according to With target control hydraulic pressure The deviation between them affects the active control force Corrective compensation is performed to further improve system stability and control accuracy.

[0037] Through the synergistic design of the above-mentioned structure and control methods, this invention constructs a pilot-operated relief valve system with active compensation capability, realizing the fixed-value control and dynamic adjustment of relief pressure. The overall system structure is compact, and the detection and execution links are clear, making it suitable for engineering implementation and product promotion.

[0038] II. Hardware Structure of Overflow Valve 2.1 Main Valve Structure The main valve housing includes a main valve sleeve 14 and a main valve cover plate 12. A sliding hole for the main valve core 13 is axially arranged within the main valve sleeve 14, allowing the main valve core 13 to reciprocate axially within this hole. The main valve sleeve 14 has an oil inlet (port A), an overflow return port (port B), and a control port connected to the pilot valve. The oil inlet is connected to the system pressure oil circuit to receive pressure oil from the hydraulic system; the overflow return port is connected to the oil tank or low-pressure return oil line to drain overflow oil back to the oil tank.

[0039] One end of the main valve core 13 is provided with a conical sealing surface for forming a sealing fit. The sealing surface fits with the main valve seat orifice. When the main valve core 13 is in a closed or slightly open state, the main overflow channel is partially or completely closed. When the system pressure rises to near the set value, the main valve core 13 moves in the opening direction under the action of pressure, so that the main overflow channel gradually opens, thereby allowing some pressurized oil to enter the overflow return port through the oil inlet and the main valve seat orifice to form pressure relief.

[0040] The main valve core 13 has an outer end cavity and an inner end cavity at its two ends, respectively. The outer end cavity is connected to the overflow return port and bears the overflow pressure. Function: The inner end cavity (C5 cavity) is connected to the control oil circuit on the pilot valve side and bears the control oil pressure. Function. To control the oil pressure by adjusting it. With external overflow pressure The pressure difference between the two ends adjusts the force balance at both ends of the main valve core 13, thereby achieving controllable adjustment of the main valve opening pressure and opening stroke. A main valve core return spring 9 is provided on the side of the main valve core 13 near the inner end to provide an elastic return force to push the main valve core 13 in the closing direction.

[0041] 2.2 Preload piston 11 and lateral force isolation structure In this embodiment, a pre-tightening piston 11 assembly is provided inside the main valve, which is used to transmit axial control force to the main valve core 13 through the pre-tightening piston 11 under the action of control oil pressure, and at the same time realize the isolation of lateral force.

[0042] To prevent the radial force generated by the return spring during compression from directly acting on the main valve core 13 and affecting its motion accuracy, this invention incorporates a preload piston 11 structure. One end of the main valve core return spring 9 acts on the preload piston 11, which transmits the axial preload force to the main valve core 13. A preload piston sleeve 10 is provided outside the preload piston 11, with the return spring located inside the preload piston sleeve 10. The preload piston sleeve 10 constrains the radial deformation of the main valve core return spring 9, thereby effectively suppressing the transmission of the radial force to the main valve core 13. The preload piston 11 can slide axially within the preload piston sleeve 10 to accommodate the elastic deformation and working stroke of the main valve core return spring 9.

[0043] Specifically, control oil enters the preload piston 11 chamber from the control channel and acts directly on the end face of the preload piston 11, causing the preload piston 11 to move axially within the chamber. The other end of the preload piston 11 abuts against the main valve core 13, thereby transmitting the axial force generated by the oil pressure to the main valve core 13, which is used to push the main valve core 13 to open or adjust its balance position, thereby controlling the overflow pressure.

[0044] To prevent lateral forces caused by factors such as control oil flow, misalignment of the main valve core 13, and machining or assembly errors of the main valve sleeve 14 from being directly applied to the main valve core 13, this embodiment sets the preload piston 11 in a separate preload piston sleeve 10. The piston sleeve is used to radially guide the preload piston 11, ensuring stable sliding within the chamber and bearing any potential lateral loads.

[0045] In this way, the various lateral forces caused by the control oil pressure will first act on the preload piston 11 and its preload piston sleeve 10, with the preload piston sleeve 10 bearing the radial reaction force, instead of being directly transmitted to the main valve core 13. The main valve core 13 obtains pure axial driving force only through end-face contact with the preload piston 11, and its motion guidance is still provided by the guide hole of the main valve core 13 itself or the valve body structure.

[0046] Through the above structural design, the lateral force can be effectively avoided from acting directly on the main valve core 13, thereby reducing the risk of wear and jamming of the main valve core 13 at the guide hole, improving the linear motion characteristics of the main valve core 13, and improving the stability, linearity and repeatability of the relief valve during pressure regulation.

[0047] 2.3 Pilot valve body 5 and pilot valve structure The pilot valve is usually located above or to the side of the valve body, and its internal structure includes a pilot valve seat, a pilot valve core, and a pilot spring cavity. The pilot valve is connected to the control chamber of the main valve, enabling it to regulate the pressure within the control chamber.

[0048] Specifically, the pilot valve applies a preload to the pilot valve core 6 via a pressure regulating mechanism (pilot valve core return spring 8), causing the pilot valve core 6 to form an adjustable throttling channel at the valve seat. A process oil chamber (C2 chamber) is formed in the middle of the throttling channel, and control oil pressure is generated in the process oil chamber. One side of this throttling channel is usually connected to the pressure upstream of the main valve or the inlet side of the main valve, while the other side is connected to the oil tank or back pressure.

[0049] 2.4 Pressure Regulation Mechanism (See Appendix) Figure 5 ) In this structure, the opening degree of the main valve is not directly driven by the fluid, but indirectly achieved through the control chamber pressure. The core function of the pilot valve is to dynamically adjust the control chamber pressure to keep the main valve at a certain stable opening degree, thereby stabilizing the downstream pressure near the set value.

[0050] Pressure regulation of this valve is achieved by pilot-controlled valve spool in three states: State 1: Oil-filled pressure boosting ( Figure 5 a) In the initial state or when pressure needs to be established, the proportional electromagnet is not energized or has a small thrust. The pilot valve core 6 is in the zero position (or a lower position). At this time, high-pressure oil enters the R1 flow channel from port X, flows into the R2 flow channel through the C2 chamber, and finally enters the C3 and C5 chambers.

[0051] Since chamber C1 is under back pressure (low pressure), the pressure in chamber C3 increases and acts on the bottom of the pilot valve core 6, generating upward hydraulic pressure.

[0052] State 2: Oil unloading and pressure reduction ( Figure 5 b) When the pressure in chamber C3 increases, causing the upward hydraulic pressure to exceed the sum of the downward thrust of the proportional electromagnet and the spring force, the pilot valve core 6 moves upward.

[0053] At this point, chamber C2 is disconnected from the high-pressure flow channel R1 and instead connected to the oil unloading flow channel R3. The high-pressure oil in chambers C3 and C5 flows back to the oil tank (Y port) via R2, C2, and R3. Control chamber pressure. It decreased rapidly.

[0054] State 3: Dynamic Equilibrium Figure 5 c) As the pressure decreases, the pilot valve core 6 moves downward again under the thrust of the proportional electromagnet. Under closed-loop control, the system quickly reaches a small throttling equilibrium position (critical state). At this time, chamber C2 is neither fully open to R1 nor fully open to R3 (or is in a high-frequency fine-tuning state), so that the pressure in chambers C3 and C5 stabilizes at the set value.

[0055] This stabilizes the oil pressure. It acts on the upper surface of the main valve core 13, and together with the main valve core return spring 9, it resists the pressure of the main oil port A, thereby controlling the opening size of the main valve port and realizing overflow pressure regulation.

[0056] 2.5 Sensor and Actuator Setup 2.5.1 Arrangement of proportional electromagnet and displacement sensor 16 The proportional electromagnet includes an electromagnet coil 3 and an armature 4. A proportional electromagnet housing 2 is provided on the outside of the proportional electromagnet to protect it. An armature fixing sleeve 17 is also provided on the proportional electromagnet housing 2, and the armature 4 is slidably mounted on the armature fixing sleeve 17.

[0057] A proportional electromagnet is installed at one end of the pilot valve body 5. The proportional electromagnet is fixedly installed on the outside of the valve body, and its armature 4 is arranged along the axis of the pilot valve body, and is directly connected to the pilot valve core 6 or indirectly arranged opposite to it. One end face of the proportional electromagnet armature 4 faces the pilot valve core 6 and forms an axial force transmission relationship with the pilot valve core 6. After being energized, the proportional electromagnet generates an electromagnetic force that acts on the pilot valve core 6, thereby applying an active control force to the pilot valve core 6. .

[0058] A displacement sensor 16 is installed at the other end of the proportional electromagnet armature 4. The displacement sensor 16 has an axially arranged detection cavity. The tail end of the proportional electromagnet armature 4 is inserted into this detection cavity. The displacement sensor 16 can detect the axial displacement of the armature 4 in real time, and thus use this displacement as a feedback input to the controller for the displacement of the pilot valve core 6 or its equivalent displacement, for participation in active compensation control. A displacement sensor housing 1 and a displacement sensor cover 15 are installed on the outside of the displacement sensor 16 to seal the displacement sensor 16 and prevent the displacement sensor 16 from being affected by dust or oil leakage.

[0059] A control signal interface 18 is provided on the valve body for signal connection with the controller or the upper control system.

[0060] The main valve sleeve 14, pilot valve body 5, proportional electromagnet and displacement sensor 16 are preferably designed to be arranged in series along the same axis, thereby forming a compact axial structure with a direct force transmission path, which is beneficial to reduce off-center load and improve the accuracy and stability of valve core movement.

[0061] 2.5.2 Flow and pressure detection structure A flow sensor is installed on the main valve overflow passage, preferably near the overflow return port or the main overflow throttling point, to accurately measure the overflow flow rate. The system can also include a pressure sensor 7 installed in the control oil circuit, connected to the control oil chamber, for real-time monitoring of the control oil pressure. And feed it back to the controller to achieve active control force. Fine-grained compensation adjustment.

[0062] III. Overflow Pressure Control Methods In this embodiment, the overflow pressure control method for an actively compensating pilot-operated relief valve is based on real-time detection of parameters such as overflow flow rate, pilot valve core 6 displacement, and control oil pressure. By establishing a force balance model between the main valve core 13 and the pilot valve core 6, the active control force that should be applied to the pilot valve core 6 is calculated, thereby achieving precise regulation of the overflow pressure. This method is applicable to constant pressure systems, proportional pressure regulating systems, and hydraulic systems that require dynamic pressure adjustment within a certain range.

[0063] 3.1 Target Pressure Setting and Signal Acquisition First, based on the operating requirements of the hydraulic system, the target overflow pressure is preset in the controller. The target overflow pressure can be input by the main controller of the whole machine via CAN bus, RS485 or analog signal through control signal interface 18, or it can be manually set on the local control module, and can be dynamically adjusted during system operation.

[0064] A flow sensor is installed in the downstream channel of the main oil circuit of the relief valve to collect the overflow flow rate passing through the main valve port in real time. The flow sensor can be a vortex flow sensor, a hot-film flow sensor, or a differential pressure flow sensor. Its installation position should be as close as possible to the main valve outlet to minimize flow feedback lag. The sensor output signal is converted into a voltage or current signal by a signal conditioning circuit before being input to the controller.

[0065] Meanwhile, a displacement sensor 16 is installed on the proportional electromagnet armature 4 or the pilot valve core 6 to detect the displacement of the proportional electromagnet armature 4, and the displacement amount is used to characterize the displacement of the pilot valve core 6. The displacement sensor 16 can adopt an LVDT, Hall effect, or strain gauge structure and be coaxially mounted with the pilot valve core 6 to reduce lateral errors. The sampling frequency is generally not lower than 100Hz to ensure control accuracy.

[0066] 3.2 Force balance calculation of main valve core 13 To establish the target overflow pressure on the main valve side, it is necessary to first determine the force balance relationship of the main valve core 13 in steady state. In this embodiment, the outer end face of the main valve core 13 bears the overflow pressure of the main pipeline. The inner end face bears the control oil pressure in the control chamber. And it is subjected to the elastic force generated by the main valve core return spring 9, and the three together act on the main valve core 13.

[0067] In steady state, the main valve core 13 satisfies the following force balance relationship:

[0068] in: The effective pressure-bearing area of ​​the outer end face of the main valve core 13, which bears the pressure. ; The effective pressure-bearing area of ​​the inner end face of the main valve core 13, which bears the pressure. ; and Determined by the valve core structure, it remains essentially constant during manufacturing; The stiffness coefficient of the main valve core return spring is 9. The spring constant is linear, and a compression spring with good stability is preferred. For the current valve core to be open, The initial pre-compression of the main valve core return spring 9.

[0069] By solving this balance equation, the theoretical target control oil pressure can be obtained. The controller will use this pressure as an intermediate target for overflow pressure regulation.

[0070] 3.3 Calculation of the opening displacement of the main valve core 13 To determine the spring compression, the opening displacement of the main valve core 13 needs to be obtained. Based on the geometric relationship between the flow area of ​​the main valve port and the displacement of the main valve core 13, and the formula for the flow rate of the small orifice, the opening displacement x_m of the main valve core 13 is determined.

[0071] In this embodiment, the instantaneous flow area of ​​the main valve port is... With valve core displacement It has the following geometric relationship:

[0072] in: Main valve seat bore diameter, The main valve core 13 sealing cone surface half cone angle, and It is determined by the valve port structure design.

[0073] Combining the flow rate formula for thin-walled orifices:

[0074] It can then be deduced that:

[0075] Flow coefficient The calibration results can be corrected and stored in the controller.

[0076] The controller calculates the current main valve opening displacement based on the real-time collected flow signal. Furthermore, the main valve spring force is calculated and substituted into the main valve balance equation to obtain the target control oil pressure. .

[0077] In one embodiment, the controller can be configured with different smoothing filtering algorithms (such as first-order low-pass filtering or Kalman filtering) according to different operating conditions to suppress the impact of instantaneous flow fluctuations on the calculation results.

[0078] 3.4 Force balance calculation of pilot valve core 6 Obtain the target control oil pressure Next, it is necessary to further determine the active control force that the pilot valve core 6 should withstand. In this embodiment, the pilot valve core 6 is regarded as a force-balanced body, with its bottom subjected to control oil pressure. Its function is that the upper part is subjected to the force of the pilot return spring and a constant force. In steady state, it satisfies:

[0079] in: It is generated by a proportional electromagnet and controlled by the coil current; The pilot valve core 6 has a pressure-bearing area that can withstand pressure. The diameter is determined by the diameter of the pilot valve core 6; To obtain displacement signals for real-time monitoring; The stiffness of the pilot return spring; It is a constant force.

[0080] The controller calculates the corresponding target electromagnetic force based on the equation, and converts it into a coil current value by looking up a table or through a calibration function, then outputs it to the proportional valve drive circuit to achieve the corresponding active control force. adjust.

[0081] 3.5 Closed-loop correction control In a further implementation, a pressure sensor 7 can be installed in the control cavity to measure the actual pressure in the control cavity. The controller calculates the pressure theoretically. and actual pressure A comparison is performed, and when a deviation exists, the control current of the electromagnet is corrected according to a proportional or PID algorithm to ensure... Towards Approaching each other, thus forming a pressure closed loop.

[0082] In addition, combined with displacement feedback signals It can monitor the displacement status of the pilot valve core 6, avoiding errors caused by valve core jamming or hysteresis. When the difference between the displacement feedback and the model prediction exceeds a set threshold, the controller can trigger an alarm or enter a safety mode (such as reducing the target pressure or limiting the flow), thereby improving system reliability.

[0083] In a further embodiment, the controller performs cyclic calculations at a frequency of 10–1000 Hz, selecting a specific value based on the system's response speed. For slower-responding hydraulic systems, the calculation frequency can be reduced to minimize noise impact.

[0084] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0085] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0086] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method for controlling the overflow pressure of a pilot-operated relief valve, characterized in that, include: Set target overflow pressure ; Collect the overflow flow rate of the main valve of the relief valve. ; Collect the displacement of the pilot valve core (6) ; Based on overflow flow Calculate the opening displacement of the main valve core (13) ; The target control oil pressure is calculated based on the force balance relationship of the main valve core (13). ; Control oil pressure according to target And the force balance relationship of the pilot valve core (6) is used to calculate the active control force that should be applied to the pilot valve core (6). ; The active control force is applied to the pilot valve core (6). To make the overflow pressure output by the main valve approach the target overflow pressure. .

2. The control method according to claim 1, characterized in that, The main valve core (13) opens and moves. Based on overflow flow Determined according to the following relationship: in: For flow coefficient, Main valve seat bore diameter, The main valve core (13) sealing cone surface half cone angle, This represents the density of the oil.

3. The control method according to claim 1, characterized in that, The force balance of the main valve core (13) satisfies the following relationship: in: The effective pressure-bearing area of ​​the outer end face of the main valve core (13) is borne by ; The effective pressure-bearing area of ​​the inner end face of the main valve core (13) is subjected to... ; Stiffness coefficient of the main valve core return spring (9); The initial pre-compression of the main valve core return spring (9).

4. The control method according to claim 1, characterized in that, The force balance of the pilot valve core (6) satisfies: in: The pilot valve core (6) has a pressure-bearing area that can withstand pressure. ; Stiffness of the pilot valve core return spring (8); It is a constant force.

5. The control method according to claim 1, characterized in that, Set a pressure sensor (7) to detect the actual control oil pressure. And control the oil pressure according to the actual situation. With target control hydraulic pressure The deviation between them corrects the active control force This enables the actual control of hydraulic pressure. Approaching the target control oil pressure .

6. The control method according to claim 1, characterized in that, The proportional electromagnet applies active control force to the pilot valve core (6). ; The displacement sensor (16) detects the displacement of the proportional electromagnet armature (4) and uses the displacement of the armature (4) to characterize the displacement of the pilot valve core (6). .

7. An active compensation pilot-operated relief valve system, characterized in that, include: Main valve sleeve (14) and main valve core (13); Pilot valve body (5) and pilot valve core (6); The proportional electromagnet, which is directly connected to the pilot valve core (6), is used to apply active control force to the pilot valve core (6). ; A displacement sensor (16) is installed at the pilot valve to detect the displacement of the pilot valve core (6) or its corresponding armature (4); A flow sensor installed in the overflow channel is used to detect the overflow flow rate Q; A controller for performing the control method according to any one of claims 1-6.

8. The system according to claim 7, characterized in that, The main valve core (13) is connected to the main valve core return spring (9) through the pre-tightening piston (11). The pre-tightening piston (11) can slide axially and is set in the pre-tightening piston sleeve (10). The main valve core return spring (9) acts on the pre-tightening piston (11) and transmits axial pre-tightening force to the main valve core (13) through the pre-tightening piston (11). The pre-tightened piston sleeve (10) constrains the radial component force generated by the main valve core return spring (9), thereby preventing the radial component force from acting directly on the main valve core (13).

9. The system according to claim 7, characterized in that, The system also includes a pressure sensor (7), which is connected to the chamber or pipeline containing the control oil pressure to detect the actual control oil pressure. .

10. The system according to claim 7, characterized in that, The main valve sleeve (14), pilot valve body (5), proportional electromagnet and displacement sensor (16) are connected in series along the same axis. The pilot valve body (5) is mounted on the main valve sleeve (14); The proportional electromagnet is installed at one end of the pilot valve body (5), and one end of its armature (4) faces the pilot valve core (6) and is set opposite to the pilot valve core (6); The displacement sensor (16) is located at the other end of the proportional electromagnet armature (4), and the end of the armature (4) is inserted into the detection cavity of the displacement sensor (16) so that the displacement sensor (16) can detect the axial displacement of the armature (4).

Images