Lock-up valve of closed system and working method

Abstract

The invention provides a lock valve of a closed system and a working method, relates to the field of hydraulic systems, and aims to solve the problem that the precise output of the action of an executive component is influenced by the change of the volume of an oil way of the closed system caused by the action of a valve core of the lock valve of an existing plug-in structure, a valve body and a valve sleeve are adopted to form a first cavity, a flow channel and a second cavity which are communicated with each other; by keeping the total volume of the first cavity, the flow channel and the second cavity at a set value, the volume fluctuation of an oil way during the action of the valve core is avoided, and the oil flow caused by the volume change is reduced, so that a hydraulic motor and a hydraulic cylinder can be more accurately positioned and act, and the cost is reduced for equipment needing to accurately control the position of an executive component. The lockup valve can remarkably improve the machining precision and the operation stability of equipment.

Description

Technical Field

[0001] This invention relates to the field of hydraulic systems, and more specifically to a closed-loop system lock-up valve and its operating method. Background Technology

[0002] A closed-loop hydraulic system forms a closed circulation of hydraulic fluid between the pump and the actuators (such as hydraulic cylinders and hydraulic motors). The hydraulic pump's suction port is connected to the actuator's outlet port, and the pump's output port is connected to the actuator's inlet port. The hydraulic fluid does not pass through a tank; it circulates within the pipeline system in a closed loop. Taking the hydraulic system of a CNC machine tool as an example, the hydraulic pump inputs hydraulic fluid to drive the hydraulic motor to rotate, which in turn raises or lowers or rotates the worktable, tool post, and other actuators. The hydraulic fluid discharged from the hydraulic motor returns directly to the hydraulic pump's suction port. This makes the entire closed-loop system compact, highly efficient in energy recovery, and reduces oil contamination, minimizing air ingress and improving system stability.

[0003] In a hydraulic closed system, in order to fix the rotation angle of the hydraulic motor or the displacement of the hydraulic cylinder piston and meet the requirement of locking the working position of the actuator, a locking valve needs to be installed on the pipeline between the hydraulic pump and the actuator. In a low-pressure, low-flow closed system, a conventional hydraulic control check valve can achieve the function of locking the working position of the actuator. However, for a high-pressure, high-flow closed system, a cartridge-type locking valve is required to lock the actuator and keep the motor rotation angle or the hydraulic cylinder piston position fixed.

[0004] However, in current cartridge-type lock-up valves, the volume of the valve core protruding into the closed-loop system oil circuit changes when the valve core moves, resulting in a significant change in the volume of the closed-loop system oil circuit. For hydraulic closed-loop systems, when the volume of the closed-loop system oil circuit changes due to the movement of the valve core, the oil inside the closed-loop system oil circuit will flow, causing the hydraulic motor to rotate and the hydraulic cylinder piston to displace, thus affecting the accurate output of the actuator.

[0005] In addition, the self-locking switch of cartridge-type lock-up valves often relies on the constant pressure source of the control oil circuit. When there is a power failure or oil leakage in the control oil circuit, the lock-up valve cannot close, which causes the hydraulic motor rotation angle or hydraulic cylinder piston displacement to be unable to be locked, posing a safety hazard to the closed system. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by providing a closed-loop system lock-up valve and its operating method. The valve body and valve sleeve form a connected first cavity, flow channel, and second cavity. By maintaining the total volume of the first cavity, flow channel, and second cavity at a set value, fluctuations in the oil circuit volume during valve core movement are avoided, thus reducing oil flow caused by volume changes. This ensures more precise positioning and operation of the hydraulic motor and hydraulic cylinder. For equipment requiring precise control of the actuator position, the lock-up valve can significantly improve the equipment's machining accuracy and operational stability.

[0007] The first objective of this invention is to provide a closed-loop system lock-up valve, which employs the following solution: The valve includes a valve core and a valve sleeve. The valve core is slidably installed inside the valve sleeve. One end of the valve core extends into a pre-set flow cavity at one end of the valve sleeve to form a first cavity. A first main oil port and a second main oil port on the valve sleeve are connected through the first cavity and are cut off when the valve core is locked. The other end of the valve core and the other end of the valve sleeve form a second cavity. The valve core has a flow channel inside. The first cavity is connected to the second cavity through the flow channel, keeping the total volume of the first cavity, the flow channel and the second cavity at a set value. A control oil chamber is also formed between the valve core and the valve sleeve for connecting to the control oil circuit.

[0008] Furthermore, a return spring is installed in the second cavity. One end of the return spring abuts against the valve sleeve, and the other end abuts against the valve core. It applies a spring force upward along the valve core axis, causing the valve core to tend to lock.

[0009] Furthermore, the first cavity, the second cavity, and the flow channel are all isolated from the control oil cavity, and the control oil cavity receives the control oil circuit drive to lock or unlock the valve core.

[0010] Furthermore, the control oil chamber includes a first oil chamber and a second oil chamber. The valve core is provided with an annular cylinder piston that separates the first oil chamber and the second oil chamber. The first oil chamber and the second oil chamber are respectively connected to the control oil circuit through a one-way throttle valve.

[0011] Furthermore, the control oil circuit is also connected to a two-position four-way seat valve, and the one-way throttle valve is connected to the two-position four-way seat valve.

[0012] Furthermore, an opening degree detector is installed on the valve sleeve. The pointer module of the opening degree detector is inserted into the first cavity and connected to the valve core to obtain the position of the valve core.

[0013] Furthermore, one end of the valve core that extends into the flow cavity is a sealing end. The sealing end can form a seal with the conical surface in the flow cavity of the valve sleeve. The conical surface is coaxially distributed with the first oil port at the end of the valve sleeve. A groove is provided on the conical surface as an auxiliary channel for connecting the first main oil port and the second main oil port.

[0014] Furthermore, the groove is a gradient groove. Along the radial direction of the first oil port, the projected profile of the gradient groove is cosine function-shaped, and the width at the end near the axis of the first oil port is greater than the width at the end away from the axis of the first oil port; along the normal direction of the conical surface, the projected profile of the gradient groove is an isosceles trapezoid.

[0015] A second objective of the present invention is to provide a method for operating a closed-loop system lock-up valve as described in the first objective, comprising: The first and second main oil ports are respectively connected to the main oil circuit, and the control oil chamber is connected to the control oil circuit. Under normal operating conditions, the control oil chamber drives the valve core to move, so that the first main oil port and the second main oil port can be connected through the first chamber, and the main oil circuit is connected to drive the actuator to run. In the locking condition, the control oil chamber drives the valve core to move in the reverse direction, cutting off the first main oil port and the second main oil port, and cutting off the main oil circuit to lock the position of the actuator. When the valve core is activated, the oil in the first and second chambers can communicate with each other through the flow channel, maintaining the volume of the main oil circuit of the closed system at the set value.

[0016] Furthermore, when the oil in the control circuit loses pressure, the valve core moves to cut off the first and second main oil ports, maintaining a locked state.

[0017] Compared with the prior art, the advantages and positive effects of this invention are: To address the issue that the movement of the valve core in current cartridge-type lock-up valves causes changes in the oil circuit volume of the closed system, affecting the precise output of the actuator, a new design is adopted. This design uses a valve body and valve sleeve to form a connected first chamber, flow channel, and second chamber. By maintaining the total volume of the first chamber, flow channel, and second chamber at a set value, fluctuations in the oil circuit volume during valve core movement are avoided. This reduces oil flow caused by volume changes, ensuring more precise positioning and movement of the hydraulic motor and hydraulic cylinder. For equipment requiring precise control of the actuator position, the lock-up valve can significantly improve the equipment's machining accuracy and operational stability.

[0018] A return spring is installed in the second chamber, and the return spring applies an upward elastic force along the valve core axis to make the valve core tend to lock, providing an automatic locking mechanism for the lock-up valve. When the control oil circuit experiences a power outage or oil leakage, and the locking or unlocking force applied to the control oil chamber ceases, the return spring can push the valve core back to the locked position, ensuring that the working position of the actuator is fixed. The return spring enhances the reliability of the lock-up valve. In some complex working environments, the hydraulic system may experience momentary pressure loss or control signal interruption. In this case, without the return spring, the lock-up valve may not be able to return to the locked state in time, causing the actuator to move unexpectedly and causing safety hazards. When a short power outage or hydraulic control signal failure occurs, the return spring can quickly lock the lock-up valve. The return spring simplifies the operation process, eliminating the need for operators to manually ensure that the lock-up valve is in the locked state every time work stops.

[0019] A seal is formed by the sealing end and the conical surface, ensuring the tightness between the first and second main oil ports, effectively preventing oil leakage and ensuring stable locking of the actuator. The groove is designed as a gradient groove. Along the radial direction of the first oil port, the projected profile is a cosine function shape, with the width at the end closer to the axis of the first oil port being greater than that at the end farther away. Along the normal direction of the conical surface, the projected profile is an isosceles trapezoid. This specially shaped gradient groove can effectively regulate the flow of oil during the small opening stage of the lock-up valve. When disturbances occur at the sealing position, such as flow diversion or vortex shedding, the gradient groove can adjust the flow state of the oil through its special shape and gradually changing flow area, reducing disturbances and improving the dynamic response performance of the lock-up valve while also ensuring stability.

[0020] The number and parameters of the gradient channels can be adjusted to suit different operating requirements. In conditions of drastic flow field changes, unstable impacts, and unfavorable dynamic loads, the effects of dynamic loads can be better mitigated by adjusting the parameters of the gradient channels, such as increasing the channel depth or changing the rate of change of channel width. Conversely, in conditions of slower flow field changes and near-static loads, the design of the gradient channels can be optimized to prioritize ensuring the sealing performance and stability of the lock-up valve. This adjustability allows the lock-up valve to be widely used in various hydraulic closed-loop systems, improving its versatility and adaptability. Attached Figure Description

[0021] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0022] Figure 1 This is a schematic diagram of the principle of a closed-loop system lock-up valve in one or more embodiments of the present invention.

[0023] Figure 2This is a schematic diagram of the structure of a closed-loop system lock-up valve in one or more embodiments of the present invention.

[0024] Figure 3 This is a schematic diagram showing the distribution of the gradient grooves in one or more embodiments of the present invention.

[0025] Figure 4 These are three views of the gradient groove structure in one or more embodiments of the present invention.

[0026] Figure 5 This is a schematic diagram of a closed system in one or more embodiments of the present invention.

[0027] Figure 6 This is a schematic diagram of two closed-loop system lock-up valves connected in series in one or more embodiments of the present invention.

[0028] The components include: 1. Opening degree detector; 2. Return spring; 3. Second cavity; 4. First flow channel; 5. First oil chamber; 6. Annular cylinder piston; 7. Second oil chamber; 8. Valve core; 9. Valve sleeve; 10. Second main oil port; 11. First main oil port; 12. First cavity; 13. Second flow channel; 14. Third flow channel; 15. Control cover plate; 16. Fourth flow channel; 17. One-way throttle valve; 18. Two-position four-way seat valve; 19. Pointer module; 20. Gradient groove; 21. Hydraulic cylinder; 22. Closed system lock-up valve; 23. Accumulator; 24. Hydraulic pump motor unit. Detailed Implementation

[0029] Example 1 In a typical embodiment of the present invention, such as Figures 1-6 As shown, a closed-loop system lock-up valve is presented.

[0030] In high-pressure, high-flow-rate hydraulic closed-loop systems, existing cartridge-type lock-up valves have shortcomings. When the valve core 8 actuates, its volume within the closed-loop system's oil circuit changes, leading to a significant alteration in the oil circuit's volume. This change in oil circuit volume causes internal oil flow, which in turn causes the hydraulic motor to rotate and the hydraulic cylinder piston to displace, ultimately affecting the precise output of the actuator. For example, in the hydraulic system of a CNC machine tool, the actuator's actuation is affected by the change in the internal volume of the closed-loop oil circuit due to the lock-up valve core 8's movement, resulting in a deviation in the actuator's operation. Therefore, this embodiment provides a closed-loop system lock-up valve that uses a valve body and valve sleeve 9 to form a connected first cavity 12, a flow channel, and a second cavity 3. By maintaining the total volume of the first cavity 12, the flow channel, and the second cavity 3 at a set value, fluctuations in the oil circuit volume when the valve core 8 actuates are avoided, thus solving the problem of oil circuit volume changes caused by the valve core 8's movement and improving the accuracy of the actuator's operation.

[0031] like Figures 1-4As shown, the closed-loop locking valve mainly includes a valve sleeve 9 and a valve core 8. The valve core 8 is slidably installed inside the valve sleeve 9. One end of the valve sleeve 9, which is connected to the main oil circuit, has a flow chamber. One end of the valve core 8 extends into the flow chamber of a section of the valve sleeve 9. After the valve core 8 occupies the volume of the flow chamber, a first cavity 12 is formed between the valve core 8 and the inner wall of the flow chamber. The first main oil port 11 and the second main oil port 10 on the valve sleeve 9 are connected through the first cavity 12. When the first main oil port 11 and the second main oil port 10 are connected to the main oil circuit, when the valve core 8 is unlocked, the oil in the main oil circuit can pass through the first cavity 12. When the valve core 8 is locked, the connection is cut off, realizing the on / off control of the main oil circuit. When it is necessary to lock the actuator, the connection between the main oil ports is cut off to prevent the flow of oil from causing displacement of the actuator. For example, in the braking system of a hydraulic elevator, when the elevator reaches the floor and stops, the locking valve cuts off the oil circuit, so that the elevator car stops stably.

[0032] The other end of the valve core 8 and the control cover plate 15 at the other end of the valve sleeve 9 form a second cavity 3. The valve core 8 has a flow channel inside, connecting the first cavity 12 and the second cavity 3, and maintaining the total volume of the first cavity 12, the flow channel, and the second cavity 3 at a set value. Through this constant volume design, even if the position of the valve core 8 changes during operation, it will not cause significant fluctuations in the overall system oil circuit volume. The continuous movement of the valve core 8 of the lock-up valve and the constant total cavity volume ensure stable hydraulic oil flow, making the actuator's operation precise and smooth.

[0033] A control oil chamber is formed between the valve core 8, the valve sleeve 9, and the control cover plate 15 installed at the end of the valve sleeve 9, for connecting to the control oil circuit. The control oil chamber receives the drive from the control oil circuit, which drives the valve core 8 to perform locking or unlocking operations.

[0034] In the hydraulic system of CNC machine tools, the positioning accuracy of the actuators is extremely high. The closed-loop locking valve in this embodiment ensures that the machine tool's worktable, tool post, and other actuators are precisely locked in their designated positions when the movement stops. When machining complex parts, the tool needs to perform precise cutting at different positions. If the actuator positioning is inaccurate, the dimensional accuracy and surface quality of the machined parts cannot be guaranteed. The closed-loop locking valve provided in this embodiment effectively avoids changes in oil circuit volume and oil flow caused by the movement of the valve core 8, significantly improving the machining accuracy of the machine tool, reducing the scrap rate, and increasing production efficiency. Simultaneously, in some large port loading and unloading equipment, such as gantry cranes, the lifting and translation movements require high-precision control. The closed-loop locking valve ensures that the actuators of these devices can work stably and accurately during the lifting of heavy objects and the movement of goods, enhancing the safety and reliability of the equipment operation.

[0035] like Figure 2As shown, the return spring 2 is located inside the second cavity 3, with one end tightly abutting against the valve sleeve 9 and the other end securely connected to the valve core 8. During installation, the spring is compressed to a certain extent and is in a pre-tightened state. As an internal component of the second cavity 3, the return spring 2 is in direct contact with the valve core 8 and the valve sleeve 9, and its installation position ensures that the force can be transmitted axially along the valve core 8.

[0036] The return spring 2 provides a locking force to the valve core 8. When no unlocking force is applied to the control oil chamber, the valve core 8 moves due to its own elasticity, causing the sealing end of the valve core 8 to fit against the conical surface of the valve sleeve 9, cutting off the connection between the first main oil port 11 and the second main oil port 10, thereby locking the position of the actuator. After the control oil chamber drives the valve core 8 to unlock, if the pressure in the control oil chamber disappears, the return spring 2 can quickly return the valve core 8 to the locked state, ensuring the safety and stability of the system.

[0037] The first chamber 12, the second chamber 3, and the flow channel are separated from the control oil chamber by sealing structures to prevent direct oil passage between the corresponding chambers of the main oil circuit and the control oil chamber. Although the chambers are isolated from each other, they form an integral structure through the cooperation of the valve core 8 and the valve sleeve 9. The control oil chamber can indirectly affect the movement of the valve core 8 within the valve sleeve 9, thereby controlling the connection status between the first chamber 12, the second chamber 3, the flow channel, and the main oil port.

[0038] This ensures that pressure changes and oil flow in the control oil chamber do not interfere with the oil state in the first chamber 12, the second chamber 3, and the flow channel. It also ensures that when the lock-up valve is activated by the control valve core 8, fluctuations in the control oil chamber will not affect the stability of the main oil circuit, thus guaranteeing the positioning accuracy and operational reliability of the actuator. Figure 2 As shown, during the upward or downward movement of the valve core 8, the total volume of the first chamber 12, the flow channel and the second chamber 3 is a set value, and the sum of the volumes remains unchanged when the valve core 8 moves. This can prevent the volume of the closed oil circuit from changing due to the movement of the valve core 8.

[0039] The control oil chamber includes a first oil chamber 5 and a second oil chamber 7. The valve core 8 is equipped with an annular cylinder piston 6 that separates the first oil chamber 5 and the second oil chamber 7. The first oil chamber 5 and the second oil chamber 7 are respectively connected to the control oil circuit through a one-way throttle valve 17. The annular cylinder piston 6 on the valve core 8 separates the two, and the one-way throttle valve 17 controls the inflow and outflow speed of the oil.

[0040] The annular cylinder piston 6 and valve core 8 are an integral structure, moving together with the valve core 8. One end of the one-way throttle valve 17 is connected to the first and second oil chambers 7 of the control oil chamber, and the other end is connected to the control oil circuit, used to regulate the oil flow rate. By controlling the oil inlet and outlet of the first oil chamber 5 and the second oil chamber 7, precise control of the movement of the valve core 8 is achieved. The one-way throttle valve 17 can regulate the speed at which oil enters or flows out of the control oil chamber, thereby controlling the movement speed of the valve core 8, avoiding system shock or response delay caused by the valve core 8 moving too fast or too slow, and enabling the valve core 8 to smoothly achieve locking and unlocking actions.

[0041] like Figure 1 and Figure 2 As shown, ignoring friction, the force equations for valve core 8 are as follows: ； In the formula: - Combined force; - The elastic force of the return spring 2; - Valve core diameter 8; - Diameter of the first main oil inlet 11; - Hydraulic power; - Hydraulic pressure at the first main oil port 11; - Second main oil port 10 hydraulic pressure; - 6-piston thrust of the annular cylinder.

[0042] When the resultant force on valve core 8 When the force is greater than zero, valve core 8 moves downward, and the lock-up valve closes. When the resultant force on valve core 8 is greater than zero... When the pressure is less than zero, the valve core 8 moves upward, and the lock-up valve opens. For a given closed system, the diameter of the valve core 8, the diameter of the first main oil port 11, the hydraulic pressure of the first main oil port 11, and the hydraulic pressure of the second main oil port 10 are all known parameters. The hydraulic force is relatively small and can be ignored. Therefore, by reasonably selecting the return spring 2 (the force of the return spring 2 is greater than the force exerted by the first main oil port 11 on the valve core 8) and reasonably setting the thrust of the annular cylinder piston 6 (the thrust of the annular cylinder piston 6 is equal to the product of the oil pressure in the control oil circuit and the pressure-bearing area of ​​the annular cylinder piston 6), the locking and unlocking control of the lock-up valve of the closed system can be achieved.

[0043] Specifically, the control oil circuit is also connected to a two-position four-way seat valve 18, and a one-way throttle valve 17 is connected to the two-position four-way seat valve 18. The two-position four-way seat valve 18, as a key component of the control oil circuit, has multiple ports. The one-way throttle valve 17 is connected to the two-position four-way seat valve 18, and the flow direction of the control oil is changed by switching the seat valve. The outlet of the one-way throttle valve 17 is connected to the corresponding port of the two-position four-way seat valve 18, the inlet of the seat valve is connected to the main pipeline of the control oil circuit, and the other ports are used to connect to different control branches or return oil pipelines.

[0044] The two-position four-way seat valve 18 can control the flow direction and on / off state of the control oil. By switching the working position of the two-position four-way seat valve 18, the path of the oil entering the first oil chamber 5 and the second oil chamber 7 is changed, thereby controlling the locking and unlocking actions of the valve core 8, realizing remote or automated control of the entire locking valve's working state.

[0045] An opening detection instrument 1 is installed on the valve sleeve 9. The pointer module 19 of the opening detection instrument 1 extends into the first cavity 12 and connects to the valve core 8 to obtain the position of the valve core 8. The pointer module 19 can be movably extended into the first cavity 12 and connected to the valve core 8. The pointer module 19 typically includes components such as a pointer and a transmission mechanism, used to convert the displacement of the valve core 8 into the movement of the pointer. The opening detection instrument 1 is fixed outside the valve sleeve 9, and the pointer module 19 passes through the valve sleeve 9 into the first cavity 12 and connects to the valve core 8 to realize real-time monitoring of the position of the valve core 8.

[0046] The valve core 8 position information is acquired in real time by the opening detection instrument 1, and the opening degree of the valve core 8 is displayed intuitively by the pointer on the dial. The operator can use this to judge the working status of the lock valve and understand the connection degree of the first main oil port 11 and the second main oil port 10, providing a basis for system operation monitoring and adjustment.

[0047] like Figure 1 and Figure 2 As shown, various operating conditions of the shut-off valve in a closed system are explained.

[0048] Under normal operating conditions, such as Figure 1 As shown, when the two-position four-way seat valve 18 is energized, the high-pressure oil in the control oil circuit X flows into the second oil chamber 7, the piston 6 of the annular cylinder experiences an upward thrust (the thrust is negative), and the valve core 8 experiences a resultant force... When the value is less than zero, the piston 6 of the annular cylinder is pushed upward, which in turn drives the valve core 8 and the pointer module 19 of the opening degree detector to move upward, opening the lock-up valve of the closed system, and connecting the first main oil port 11 and the second main oil port 10 of the main oil circuit.

[0049] When the two-position four-way seat valve 18 is de-energized, the high-pressure oil in the control oil circuit X flows into the first oil chamber 5, and the piston 6 of the annular cylinder experiences a downward thrust (a positive number), resulting in a net force on the valve core 8. If the value is greater than zero, the valve core 8 and the pointer module 19 of the opening detection meter will move downwards, the closed system lock valve will close, and the first main oil port 11 and the second main oil port 10 of the main oil circuit will be blocked.

[0050] In the event of a power outage or oil leak, even if the hydraulic oil controlling oil circuit X loses pressure, the valve core 8 will still be protected by the resultant force. When the value is greater than zero, the valve core 8 and pointer module 19 of the closed-loop system lock-up valve will also move downward under the action of the return spring 2, closing the closed-loop system lock-up valve, thus solving the problem that the self-locking closure of the lock-up valve requires a constant pressure source in the control oil circuit. The pointer module 19 of the opening degree detector moves synchronously with the valve core 8, and the opening degree detector can measure the opening degree of the new lock-up valve in real time.

[0051] like Figure 1 and Figure 3 , Figure 4 As shown, the end of the valve core 8 that protrudes into the flow cavity is the sealing end. Its shape is adapted to the conical surface inside the flow cavity of the valve sleeve 9, and it can fit tightly to form a seal. The conical surface is coaxially distributed with the first oil port at the end of the valve sleeve 9. A groove is provided on the conical surface as an auxiliary channel for connecting the first main oil port 11 and the second main oil port 10.

[0052] The groove is a gradient groove 20. Along the radial direction of the first oil port, the projected outline of the gradient groove 20 is cosine-shaped, and the width at the end near the axis of the first oil port is greater than the width at the end away from the axis of the first oil port. Along the normal direction of the conical surface, the projected outline of the gradient groove 20 is an isosceles trapezoid. The sealing end of the valve core 8 is in direct contact with the conical surface of the valve sleeve 9. The gradient groove 20, serving as an auxiliary channel connecting the first main oil port 11 and the second main oil port 10, is located on the surface of the conical surface and communicates with the main oil port and the first cavity 12.

[0053] The sealing structure formed by the sealing end and the conical surface cuts off the connection between the first main oil port 11 and the second main oil port 10 when the valve core 8 is locked, preventing oil leakage and ensuring reliable locking of the actuator. The gradient groove 20 optimizes the flow state of the oil during the opening or closing of the valve core 8, especially at small openings. Its special shape can adjust the oil velocity and flow rate, reducing phenomena such as flow diversion and vortex shedding, lowering unstable impacts and dynamic loads caused by changes in the flow field, and balancing the dynamic response and stability of the lock-up valve.

[0054] It should be noted that the number and parameters of the gradient grooves 20 can be adjusted adaptively for different working requirements. Under conditions of drastic flow field changes, unstable impacts, and unfavorable dynamic loads, the effects of dynamic loads can be better mitigated by adjusting the parameters of the gradient grooves 20, such as increasing the groove depth or changing the groove width change rate. Under conditions of slower flow field change rate and near-static loads, the design of the gradient grooves 20 can be optimized to focus more on ensuring the sealing performance and stability of the lock-up valve. This adjustability allows the lock-up valve to be widely used in various hydraulic closed systems, improving its versatility and adaptability.

[0055] like Figure 5As shown, in the closed system, hydraulic cylinder 21 is connected to hydraulic pump motor unit 24 via closed system lock-up valve 22, and an accumulator is also connected to the hydraulic pipeline. This accumulator can input high-pressure hydraulic oil into the rodless chamber of hydraulic cylinder 32 to extend the piston rod, and can also input high-pressure hydraulic oil into the rod chamber of hydraulic cylinder 32 to retract the piston rod. To achieve reliable locking of the piston rod in both extension and retraction directions, two closed system lock-up valves 22 are used in series, as shown in the structural diagram. Figure 6 As shown.

[0056] Example 2 In another typical embodiment of the present invention, such as Figures 1-6 As shown, a method for operating a closed-loop system lock-up valve is presented, utilizing the closed-loop system lock-up valve as described in Example 1.

[0057] A method for operating a closed-loop system lock-up valve includes: The first main oil port 11 and the second main oil port 10 are respectively connected to the main oil circuit, and the control oil chamber is connected to the control oil circuit. Under normal operating conditions, the control oil chamber drives the valve core 8 to move, so that the first main oil port 11 and the second main oil port 10 can be connected through the first chamber 12, and the main oil circuit is connected to drive the actuator to run. In the locking condition, the control oil chamber drives the valve core 8 to move in the reverse direction, so that the first main oil port 11 and the second main oil port 10 are cut off, and the main oil circuit is cut off to lock the position of the actuator. When the valve core 8 is activated, the oil in the first chamber 12 and the second chamber 3 can communicate with each other through the flow channel, keeping the volume of the main oil circuit of the closed system at the set value.

[0058] When the oil in the control circuit loses pressure, the valve core 8 moves to cut off the first main oil port 11 and the second main oil port 10, keeping it locked.

[0059] A return spring 2 is installed in the second cavity 3, and the return spring 2 applies an upward elastic force along the valve core 8 to make the valve core 8 tend to lock, providing an automatic locking mechanism for the lock-up valve. When the control oil circuit is de-energized or leaks oil and stops applying locking or unlocking force to the control oil cavity, the return spring 2 can push the valve core 8 back to the locked position, ensuring that the working position of the actuator is fixed. The return spring 2 enhances the reliability of the lock-up valve.

[0060] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A closed-loop system lock-up valve, characterized in that, It includes a valve core and a valve sleeve. The valve core is slidably installed in the valve sleeve. One end of the valve core extends into a pre-set flow cavity at one end of the valve sleeve to form a first cavity. The first main oil port and the second main oil port opened on the valve sleeve are connected through the first cavity and are cut off when the valve core is locked. The other end of the valve core and the other end of the valve sleeve form a second cavity. The valve core has a flow channel inside. The first cavity is connected to the second cavity through the flow channel, keeping the total volume of the first cavity, the flow channel and the second cavity at a set value. A control oil chamber is also formed between the valve core and the valve sleeve for connecting to the control oil circuit.

2. The closed-loop system lock-up valve as described in claim 1, characterized in that, A return spring is installed in the second cavity. One end of the return spring abuts against the valve sleeve, and the other end abuts against the valve core. It applies a spring force upward along the valve core axis, causing the valve core to tend to lock.

3. The closed-loop system lock-up valve as described in claim 2, characterized in that, The first cavity, the second cavity, and the flow channel are all isolated from the control oil cavity. The control oil cavity receives the control oil circuit drive to lock or unlock the valve core.

4. The closed-loop system lock-up valve as described in claim 1, characterized in that, The control oil chamber includes a first oil chamber and a second oil chamber. The valve core is provided with an annular cylinder piston that separates the first oil chamber and the second oil chamber. The first oil chamber and the second oil chamber are respectively connected to the control oil circuit through a one-way throttle valve.

5. The closed-loop system lock-up valve as described in claim 4, characterized in that, The control oil circuit is also connected to a two-position four-way seat valve, and a one-way throttle valve is connected to the two-position four-way seat valve.

6. The closed-loop system lock-up valve as described in claim 1, characterized in that, An opening degree detector is installed on the valve sleeve. The pointer module of the opening degree detector is inserted into the first cavity and connected to the valve core to obtain the position of the valve core.

7. The closed-loop system lock-up valve as described in claim 1, characterized in that, The end of the valve core that extends into the flow cavity is the sealing end. The sealing end can form a seal with the conical surface in the flow cavity of the valve sleeve. The conical surface is coaxially distributed with the first oil port at the end of the valve sleeve. A groove is provided on the conical surface as an auxiliary channel for connecting the first main oil port and the second main oil port.

8. The closed-loop system lock-up valve as described in claim 7, characterized in that, The groove is a gradient groove, which extends radially upward along the first oil port. The projected outline of the gradient groove is in the shape of a cosine function, and the width at the end closer to the axis of the first oil port is greater than the width at the end farther from the axis of the first oil port. Along the conical surface upwards, the projected profile of the gradient groove is an isosceles trapezoid.

9. A method for operating a closed-loop system lock-up valve, utilizing the closed-loop system lock-up valve as described in any one of claims 1-8, characterized in that, include: The first and second main oil ports are respectively connected to the main oil circuit, and the control oil chamber is connected to the control oil circuit. Under normal operating conditions, the control oil chamber drives the valve core to move, so that the first main oil port and the second main oil port can be connected through the first chamber, and the main oil circuit is connected to drive the actuator to run. In the locking condition, the control oil chamber drives the valve core to move in the reverse direction, cutting off the first main oil port and the second main oil port, and cutting off the main oil circuit to lock the position of the actuator. When the valve core is activated, the oil in the first and second chambers can communicate with each other through the flow channel, maintaining the volume of the main oil circuit of the closed system at the set value.

10. The operating method of the closed-loop system lock-up valve as described in claim 9, characterized in that, When the oil in the control circuit loses pressure, the valve core moves to cut off the first and second main oil ports, keeping it locked.

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