A pressure relief system and a pressure relief system control method

Abstract

The application discloses a pressure relief system and a pressure relief system control method. The pressure relief system comprises a main oil cylinder, an oil tank, a control valve and a proportional valve, the main oil cylinder comprises a piston, the piston divides the inner cavity of the main oil cylinder into a first cavity and a second cavity, the oil tank is communicated with the first cavity through a liquid filling valve, the control valve controls the opening and closing of the liquid filling valve, when the liquid filling valve is closed, the proportional valve is communicated with the first cavity through a first oil path, the proportional valve is communicated with the oil tank through the control valve, and the proportional valve can relieve the pressure in the inner cavity of the main oil cylinder. When relieving the pressure, the opening degree of the proportional valve can be infinitely adjusted according to the pressure in the inner cavity of the main oil cylinder and / or the relieving flow. The pressure relief system control method comprises the pressure relief system. By adopting the application, uniform-speed pressure relief and flow uniform control can be realized, various working conditions can be flexibly adapted, and the pressure relief stability and efficiency are considered.

Description

Technical Field

[0001] This invention relates to the field of pressure relief system technology, and in particular to a pressure relief system and a pressure relief system control method. Background Technology

[0002] In fields such as engineering machinery and metallurgical equipment, pressure relief systems are often used to relieve pressure in the main hydraulic cylinder chamber. Existing pressure relief systems typically employ the following structures as pressure relief schemes: ① Using a cartridge valve as the core pressure relief element, the pressure relief system includes a hydraulic cylinder, an oil tank, and a cartridge valve assembly. The cartridge valve is connected in series in the pressure relief oil circuit, and pressure relief is started and stopped by controlling the opening and closing of the cartridge valve; ② Using multiple cartridge valves of different specifications connected in parallel or in series, supplemented by a pilot valve to form a combined valve group, and achieving staged pressure relief through preset valve group logic; ③ Using an overflow valve as the pressure relief element, the pressure relief curve is set by spring pre-adjustment pressure, and the opening and closing of the pressure relief passage is controlled by the balance relationship between the valve core and the spring. However, in practice, the above pressure relief systems have the following drawbacks: ① When a single cartridge valve directly relieves pressure, the valve core opens quickly, and a sudden drop in pressure is likely to occur in the initial stage of pressure relief, resulting in excessive pressure relief impact and causing equipment vibration. Moreover, the selection of the system is prone to the dilemma of excessive pressure relief impact or excessive pressure relief time; ② The combination method of the multi-specification cartridge valve combination pressure relief scheme is fixed, and the valve group needs to be configured in advance according to the preset working conditions. It cannot adapt to dynamically changing working conditions to form the optimal pressure relief scheme; ③ The overflow valve pressure relief scheme sets a preset curve with pressure as the control condition, which makes it difficult to ensure the uniformity of the pressure relief flow and cannot achieve uniform pressure relief throughout the process, resulting in poor pressure relief stability. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a pressure relief system that can steplessly regulate the pressure relief process, realize the adjustable and controllable pressure and flow rate during the pressure relief process, thereby achieving uniform pressure relief and uniform flow control, flexibly adapting to various working conditions, and taking into account both pressure relief stability and efficiency.

[0004] To solve the above-mentioned technical problems, the present invention provides a pressure relief system, including a main oil cylinder, an oil tank connected to the main oil cylinder, a control valve and a proportional valve. The main oil cylinder includes a piston, which divides the inner cavity of the main oil cylinder into a first cavity and a second cavity. The oil tank is connected to the first cavity through a filling valve, and the control valve controls the filling valve to open or close.

[0005] The proportional valve is connected to the first chamber through the first oil passage; when the filling valve is open, the proportional valve controls the piston to rise or fall; when the filling valve is closed, the proportional valve controls the first chamber to pressurize or depressurize.

[0006] As an improvement to the above solution, the proportional valve includes a first interface and a second interface, the first interface being connected to the first oil circuit, and the second interface being connected to an external hydraulic source.

[0007] As an improvement to the above solution, the proportional valve further includes a third interface, which is connected to the control valve via a second oil circuit.

[0008] As an improvement to the above solution, the proportional valve can switch between a state where the first interface is connected to the second interface and a state where the first interface is connected to the third interface.

[0009] As an improvement to the above solution, the filling valve further includes a valve port and a valve stem, and the control valve controls the descent and ascent of the valve stem to achieve communication and closure between the valve port and the first chamber.

[0010] As an improvement to the above solution, the filling valve further includes a filling cylinder, the valve stem dividing the inner cavity of the filling cylinder into a third cavity and a fourth cavity, the control valve being connected to the third cavity through a third oil passage, and the control valve being connected to the fourth cavity through a fourth oil passage.

[0011] As an improvement to the above solution, the control valve is connected to the second chamber via a fifth oil passage.

[0012] And / or, the pressure relief system further includes an oil passage connecting the oil tank and the first chamber, and the filling valve is located at the connection between the oil passage and the first chamber.

[0013] As an improvement to the above solution, the pressure relief system further includes a control oil circuit, and the control valve is connected to the proportional valve through the control oil circuit. The control valve can control the proportional valve to switch between the state where the first interface is connected to the second interface and the state where the first interface is connected to the third interface.

[0014] And / or, the control valve is connected to the oil tank via a sixth oil passage.

[0015] The present invention also provides a pressure relief system control method for controlling the pressure relief system as described above, comprising the following steps: In the first stage of depressurization, the proportional valve uses a first preset opening degree to depressurize; In the second stage of depressurization, the proportional valve uses a second preset opening degree to depressurize; Wherein, the first preset opening degree is not greater than the second preset opening degree.

[0016] As an improvement to the above solution, the pressure relief system control method further includes the following steps: During the first stage of depressurization, the opening degree of the proportional valve is adjusted according to a first preset adjustment method; During the second stage of depressurization, the opening degree of the proportional valve is adjusted according to the second preset adjustment method; The first preset adjustment method and the second preset adjustment method are both determined by at least the pressure and pressure relief flow rate of the main cylinder cavity.

[0017] As an improvement to the above solution, the pressure relief system control method further includes the following steps: In the first stage of depressurization, the opening degree of the proportional valve is adjusted according to the first depressurization equation, wherein the first depressurization equation is: ; In the second stage of depressurization, the opening degree of the proportional valve is adjusted according to the second depressurization equation, wherein the second depressurization equation is: ; Wherein, A1% is the opening degree of the proportional valve in the first stage of pressure relief, C1 is the correction coefficient of the pressure relief flow rate in the first stage of pressure relief, and Pmax is the maximum pressure in the first stage of pressure relief; A2% is the opening degree of the proportional valve in the second stage of pressure relief, C2 is the correction coefficient of the pressure relief flow rate in the second stage of pressure relief, and P is the real-time pressure of the main cylinder.

[0018] As an improvement to the above scheme, when the calculation result A1% of the first pressure relief equation is greater than or equal to the calculation result A%2 of the second pressure relief equation, the opening change equation of the proportional valve transitions from the first pressure relief equation to the second pressure relief equation.

[0019] When the calculation result A2%≥1 of the second pressure relief equation, the valve opening of the proportional valve is fixed at 100%.

[0020] As an improvement to the above scheme, the correction coefficient C1 for the pressure relief flow rate in the first stage of pressure relief and the correction coefficient C2 for the pressure relief flow rate in the second stage of pressure relief are both positively correlated with the temperature T inside the main cylinder.

[0021] Implementing this invention has the following beneficial effects: The pressure relief system of this invention includes a main oil cylinder, an oil tank, a control valve, a proportional valve, and a filling valve. The proportional valve is connected to the first chamber of the main oil cylinder through a first oil circuit and to the oil tank through the control valve. During pressure relief, three adjustment modes can be implemented, each corresponding to a different effect: First, the opening of the proportional valve is infinitely adjustable according to the pressure inside the main oil cylinder, which can accurately match the pressure change rhythm to control the pressure relief process and avoid shocks caused by sudden pressure drops; Second, the opening of the proportional valve is infinitely adjustable according to the pressure relief flow rate, which can directly ensure the uniformity of the pressure relief flow rate and achieve uniform pressure relief throughout the process; Third, the opening of the proportional valve is infinitely adjustable according to the pressure inside the main oil cylinder and the pressure relief flow rate, which can achieve coordinated control of pressure and flow rate, taking into account both pressure relief stability and efficiency. The above adjustment mode can solve the defect of excessive pressure relief impact of a single cartridge valve, overcome the problem of fixed adaptability of multi-specification cartridge valve combination schemes, and improve the poor pressure relief stability of the relief valve. Thus, it can achieve a balance between pressure relief stability and efficiency, improve the flexible adaptability of the pressure relief system to various working conditions, and ensure the stability of equipment operation. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the pressure relief system of the present invention; Figure 2 This is a schematic diagram of the proportional valve of the present invention; Figure 3 This is a schematic diagram of the piston's state during descent in this invention; Figure 4 This is a schematic diagram of the piston rising during the invention process; Figure 5 This is a schematic diagram of the valve stem rising as described in this invention; Figure 6 This is a schematic diagram of the valve stem descending as described in this invention; Figure 7 This is a schematic diagram of the oil passage, the sixth oil circuit, and the control oil circuit of the present invention; Figure 8 This is a schematic diagram of the first process of the depressurization method of the present invention; Figure 9 This is a schematic diagram of the second process of the depressurization method of the present invention. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. It is hereby declared that the directional terms such as up, down, left, right, front, back, inside, and outside used in this text are based solely on the accompanying drawings and are not intended to specifically limit the invention.

[0024] See Figure 1This invention discloses a pressure relief system, including a main hydraulic cylinder 1, an oil tank 2 connected to the main hydraulic cylinder 1, a control valve 3, and a proportional valve 4. The main hydraulic cylinder 1 is an actuator capable of performing work on a workpiece by descending. The main hydraulic cylinder 1 includes a piston 11, which is located within the inner cavity of the main hydraulic cylinder 1 and can move within it. The piston 11 divides the inner cavity of the main hydraulic cylinder 1 into a first cavity 12 and a second cavity 13. The end of the piston 11 furthest from the workpiece is the first cavity 12, and the end of the piston 11 closer to the workpiece is the second cavity 13. The oil tank 2 is connected to the first cavity 12 via a filling valve 5, and the control valve 3 controls the opening or closing of the filling valve 5. The filling valve 5 controls the connection between the oil tank 2 and the first cavity 12, and, in conjunction with the control valve 3, can switch the oil circuit connection state according to the system's operational requirements.

[0025] During actual pressure relief operations, when the filling valve 5 is closed, the proportional valve 4 is connected to the first chamber 12 through the first oil circuit, and simultaneously connected to the oil tank 2 through the control valve 3. At this time, the proportional valve 4 can perform pressure relief operations on the inner cavity of the main cylinder 1. During pressure relief, the opening degree of the proportional valve 4 can be infinitely adjusted according to the pressure and / or pressure relief flow rate within the main cylinder 1. Unlike the pressure relief schemes of existing technologies using a single cartridge valve, a combination of multiple cartridge valves, or an overflow valve, this embodiment achieves pressure relief control through the infinitely adjustable function of the proportional valve 4, effectively avoiding the shortcomings of existing solutions.

[0026] Specifically, the opening of the proportional valve 4 can be infinitely adjusted according to the pressure inside the main cylinder 1. When the pressure change inside the main cylinder 1 is transmitted to the main controller, the main controller drives the opening of the proportional valve 4 to change accordingly, thereby adjusting the flow rate of the pressure relief passage. This adjustment method can adjust the pressure relief rhythm according to the pressure change inside the main cylinder 1, avoiding the sudden pressure drop phenomenon that occurs when using a single cartridge valve for pressure relief, reducing the impact of pressure relief shock on the equipment, and ensuring stable equipment operation. In addition, the opening of the proportional valve 4 can be infinitely adjusted according to the pressure relief flow rate. When the pressure relief flow rate change is transmitted to the main controller, the main controller drives the opening of the proportional valve 4 to change accordingly, thereby maintaining a stable pressure relief flow rate. This adjustment method can directly ensure the uniformity of the pressure relief flow rate, achieving uniform pressure relief throughout the entire process, improving the shortcomings of large flow fluctuations and poor stability in existing overflow valve pressure relief schemes, and making the pressure relief process more controllable. Moreover, the opening degree of the proportional valve 4 can be infinitely adjusted according to the pressure and pressure relief flow in the inner cavity of the main cylinder 1. When the pressure change and pressure relief flow change in the inner cavity of the main cylinder 1 are simultaneously transmitted to the main controller, the main controller drives the opening degree of the proportional valve 4 to change accordingly, thereby realizing the coordinated control of pressure and flow. This adjustment method can take into account both pressure changes and flow stability, avoiding the impact caused by sudden pressure drops and ensuring flow uniformity, thus taking into account both pressure relief stability and efficiency.

[0027] The beneficial effects of the embodiments of the present invention are as follows: The pressure relief system of this invention includes a main cylinder 1, an oil tank 2, a control valve 3, a proportional valve 4, and a filling valve 5. The proportional valve 4 is connected to the first chamber 12 of the main cylinder 1 through a first oil circuit and to the oil tank 2 through the control valve 3. During pressure relief, three adjustment modes can be achieved, each with different effects: First, the opening of the proportional valve 4 is infinitely adjustable according to the pressure inside the main cylinder 1, which can accurately match the pressure change rhythm to control the pressure relief process and avoid sudden pressure drops that could cause shocks. Second, the opening of the proportional valve 4 is infinitely adjustable according to the pressure relief flow rate, which can directly ensure the uniformity of the pressure relief flow rate and achieve uniform pressure relief throughout the process. Third, the opening of the proportional valve 4 is infinitely adjustable according to the pressure inside the main cylinder 1 and the pressure relief flow rate, which can achieve coordinated control of pressure and flow rate, taking into account both the stability and efficiency of pressure relief. The above adjustment mode can solve the defect of excessive pressure relief impact of a single cartridge valve, overcome the problem of fixed adaptability of multi-specification cartridge valve combination schemes, and improve the poor pressure relief stability of the relief valve. Thus, it can achieve a balance between pressure relief stability and efficiency, improve the flexible adaptability of the pressure relief system to various working conditions, and ensure the stability of equipment operation.

[0028] See Figure 2The proportional valve 4 includes a first interface 41 and a second interface 42. The first interface 41 is connected to the first oil passage 71, providing a pathway for the proportional valve 4 to regulate the pressure and flow rate of the first chamber 12. The second interface 42 is connected to an external hydraulic source, which can introduce external pressurized oil into the system to meet the power supply requirements for pressurizing the first chamber 12 or driving the piston 11. The proportional valve 4 also includes a third interface 43, which is connected to the control valve 3 through the second oil passage 72, providing a basis for the proportional valve 4 to depressurize and drive the piston 11.

[0029] The proportional valve 4 can switch between the state where the first interface 41 is connected to the second interface 42 and the state where the first interface 41 is connected to the third interface 43. By switching between the two connection states, the system can switch between different working modes without the need to set up multiple additional control valves, thus simplifying the system control logic.

[0030] See Figure 3 and Figure 4 When the piston 11 rises or falls, the filling valve 5 opens, and the oil tank 2 connects to the first chamber 12. Specifically, when the first interface 41 is connected to the second interface 42, an external hydraulic source can supply pressure to the first chamber 12 through the second interface 42, the first interface 41, and the first oil circuit 71. The pressure acts on the piston 11, causing it to fall. During this process, the fall of the piston 11 continuously increases the volume of the first chamber 12. The oil tank 2 can continuously supply oil to the first chamber 12 through the filling valve 5, ensuring sufficient oil supply to the first chamber 12, thereby stably realizing the falling action of the piston 11. When the first interface 41 is connected to the third interface 43, the piston 11 rises. At this time, the oil in the first chamber 12 can flow to the control valve 3 through the first oil passage 71, the first interface 41, the third interface 43 and the second oil passage 72, and then return to the oil tank 2 or the second chamber 13 through the control valve 3, so as to realize the reasonable flow of oil in the first chamber 12, thereby stably realizing the rising action of the piston 11.

[0031] See Figure 5During pressurization and depressurization, the filling valve 5 is closed, and the oil tank 2 is not connected to the first chamber 12. This avoids unnecessary communication interference between the oil and the oil tank 2 during pressurization or depressurization, ensuring the accuracy of pressure control. Specifically, when the first interface 41 is connected to the second interface 42, an external hydraulic source can supply pressure to the first chamber 12 through the second interface 42, the first interface 41, and the first oil circuit 71. At this time, the piston 11 does not move, the volume of the first chamber 12 remains unchanged, and the supplied pressure gradually increases the pressure inside the first chamber 12, thereby achieving the pressurization function. When the first interface 41 is connected to the third interface 43, the pressure inside the first chamber 12 can be unloaded through the first oil circuit 71, the first interface 41, the third interface 43, and the second oil circuit 72 via the proportional valve 4. Combined with the stepless adjustment characteristic of the proportional valve 4, a low-impact depressurization process is achieved.

[0032] See Figure 4 The filling valve 5 further includes a valve port 51 and a valve stem 52. The valve stem 52 is movably connected to the valve port 51. The valve port 51 has a valve hole, through which the oil tank 2 can communicate with the first cavity 12. The end of the valve stem 52 can block or unblock the valve hole. The control valve 3 controls the lowering and raising of the valve stem 52 to achieve communication between the valve port 51 and the first cavity 12 or to close the valve port 51 and the first cavity 12. The action of the end of the valve stem 52 in blocking or unblocking the valve hole directly determines the on / off state of the filling valve 5. The control valve 3 controls the raising and lowering of the valve stem 52 to switch the on / off state of the filling valve 5, ensuring the coordinated control effect of the filling valve 5 and other components of the system.

[0033] See Figure 5The filling valve 5 also includes a filling cylinder 53. The valve stem 52 divides the inner cavity of the filling cylinder 53 into a third cavity 531 and a fourth cavity 532. The third cavity 531 is located at the end of the filling cylinder 53 away from the main oil cylinder 1, and the fourth cavity 532 is located at the end of the filling cylinder 53 closer to the main oil cylinder 1. The control valve 3 is connected to the third cavity 531 through the third oil passage 73, and the control valve 3 is connected to the fourth cavity 532 through the fourth oil passage 74. When the control valve 3 fills the third chamber 531 with liquid, the hydraulic force in the third chamber 531 pushes the valve stem 52 down, causing the end of the valve stem 52 to release the seal on the valve orifice, opening the valve port 51, and connecting the oil tank 2 with the first chamber 12; when the control valve 3 fills the fourth chamber 532 with liquid, the hydraulic force in the fourth chamber 532 pushes the valve stem 52 up, causing the end of the valve stem 52 to seal the valve orifice, closing the valve port 51, and disconnecting the oil tank 2 from the first chamber 12. The filling cylinder 53 provides support for the stable movement of the valve stem 52. The division of the third chamber 531 and the fourth chamber 532 allows the raising and lowering of the valve stem 52 to be achieved by hydraulic drive, improving movement stability and control reliability. The connection between the third oil circuit 73 and the fourth oil circuit 74 enables the control valve 3 to hydraulically control the third chamber 531 and the fourth chamber 532, ensuring the stable and controllable switching of the opening and closing state of the valve port 51, and adapting to the system's requirements for the connection state between the oil tank 2 and the first chamber 12 under different operating conditions.

[0034] See Figure 6 The control valve 3 is connected to the second chamber 13 via a fifth oil passage 75. The fifth oil passage 75 establishes an oil flow regulation path between the control valve 3 and the second chamber 13, allowing the control valve 3 to adjust the oil pressure and flow rate in the second chamber 13 in real time. During the depressurization process of the proportional valve 4 in the main cylinder cavity, the pressure state in the second chamber 13 changes with the movement of the piston 11. Through the connection of the fifth oil passage 75, the control valve 3 can promptly balance the oil pressure in the second chamber 13, preventing pressure fluctuations in the second chamber 13 from affecting the depressurization process of the first chamber 12, thereby ensuring the uniformity of flow rate during depressurization by the proportional valve 4 and achieving uniform depressurization.

[0035] See Figure 7 The pressure relief system also includes an oil passage 6, which connects the oil tank 2 and the first chamber 12. The oil passage 6 provides a pathway for oil flow between the oil tank 2 and the first chamber 12, ensuring smooth oil flow and sealing. The filling valve 5 is located at the connection between the oil passage 6 and the first chamber 12, and can directly control the opening and closing of the connection between the oil passage 6 and the first chamber 12.

[0036] The pressure relief system also includes a control oil circuit 77. The control valve 3 is connected to the proportional valve 4 through the control oil circuit 77. The control valve 3 can control the proportional valve 4 to switch between a state where the first interface 41 is connected to the second interface 42 and a state where the first interface 41 is connected to the third interface 43. When the system needs to drive the piston 11 to descend or pressurize the first chamber 12, the control valve 3 outputs a corresponding control signal to the proportional valve 4 through the control oil circuit 77, driving the valve core of the proportional valve 4 to move, so that the first interface 41 is connected to the second interface 42. When the system needs to drive the piston 11 to rise or depressurize the first chamber 12, the control valve 3 outputs another control signal through the control oil circuit 77, driving the valve core of the proportional valve 4 to move in the opposite direction, so that the first interface 41 is connected to the third interface 43.

[0037] The control valve 3 is connected to the oil tank 2 via a sixth oil passage 76. The sixth oil passage 76 establishes an oil flow path between the control valve 3 and the oil tank 2, enabling oil recovery and replenishment. When there is excess oil or excessive pressure inside the control valve 3, the excess oil can be returned to the oil tank 2 through the sixth oil passage 76, preventing control jamming caused by oil stagnation. When the control valve 3 needs replenishment, oil can be obtained from the oil tank 2 through the sixth oil passage 76, ensuring sufficient oil inside the control valve 3, ensuring flexible and smooth control actions, and thus improving the operational stability of the entire system.

[0038] See Figure 8 This invention also discloses a pressure relief system control method for controlling the pressure relief system described above. The method includes the following steps: S01, In the first stage of depressurization, the proportional valve 4 uses the first preset opening degree to depressurize; S02, during the second stage of depressurization, proportional valve 4 uses the second preset opening degree to depressurize; Wherein, the first preset opening degree is not greater than the second preset opening degree.

[0039] This invention achieves staged pressure relief by controlling the preset opening degree of the proportional valve 4. In practical applications, during the initial stage of pressure relief (the first stage), a relatively small first preset opening degree is used to slow down the rate of flow change, avoid sudden pressure drops, reduce the impact of pressure relief shocks on components such as the main cylinder 1 and the pipeline, and ensure the stability of the initial stage of pressure relief. As the pressure relief process enters the second stage, the pressure inside the main cylinder 1 has decreased. At this time, switching to the second preset opening degree, which is not less than the first preset opening degree, can increase the pressure relief flow, accelerate the pressure relief process, and improve the overall pressure relief efficiency. Compared with the existing single-opening pressure relief or fixed-logic pressure relief control methods, this control method, through the staged preset opening degree adjustment strategy, can take into account both the stability of the initial stage of pressure relief and the efficiency of the later stage, further adapting to the pressure relief requirements under different working conditions and ensuring the stable and efficient operation of the pressure relief system.

[0040] See Figure 9 The pressure relief system control method further includes the following steps: S11, during the first stage of depressurization, the opening of the proportional valve 4 is adjusted according to the first preset adjustment method; S21, during the second stage of depressurization, the opening of the proportional valve 4 is adjusted according to the second preset adjustment method; The first preset adjustment method and the second preset adjustment method are both determined by the pressure and pressure relief flow rate inside the main oil cylinder 1.

[0041] It should be noted that, in specific implementation, the main controller will acquire the pressure data and pressure relief flow data of the main cylinder 1 cavity in real time, and determine the first preset adjustment method and the second preset adjustment method based on these two types of data. In the first stage of pressure relief, the opening of the proportional valve 4 is adjusted according to the determined first preset adjustment method, so that the change in the opening of the proportional valve 4 matches the pressure and pressure relief flow requirements of the main cylinder 1 cavity in this stage; after entering the second stage of pressure relief, the opening of the proportional valve 4 is switched to the second preset adjustment method to adapt to the pressure and flow conditions of this stage.

[0042] Furthermore, the pressure relief system control method further includes the following steps: During the first stage of depressurization, the opening of the proportional valve 4 is determined according to the first depressurization equation, which is: ; In the second stage of depressurization, the opening of the proportional valve 4 is depressurized according to the second depressurization equation, wherein the second depressurization equation is: ; Wherein, A1% is the opening degree of the proportional valve 4 in the first stage of pressure relief, C1 is the correction coefficient of the pressure relief flow rate in the first stage of pressure relief, and Pmax is the maximum pressure in the first stage of pressure relief; A2% is the opening degree of the proportional valve 4 in the second stage of pressure relief, C2 is the correction coefficient of the pressure relief flow rate in the second stage of pressure relief, and P is the real-time pressure of the main cylinder 1.

[0043] In practice, the main controller first obtains the maximum pressure Pmax and the real-time pressure P of the main cylinder 1 during the first stage of pressure relief. Substituting these parameters into the first pressure relief equation, the opening degree A1% of the proportional valve 4 in this stage is calculated, and the proportional valve 4 is adjusted according to this opening degree for pressure relief. After entering the second stage of pressure relief, the main controller obtains the real-time pressure P of the main cylinder 1 in this stage, substitutes it into the second pressure relief equation to calculate the opening degree A2%, and then adjusts the proportional valve 4 according to this opening degree.

[0044] The first pressure relief equation is based on the pressure change characteristics of the first stage of pressure relief, and through... and The ratio of the opening degree to the pressure is used to establish the relationship between the opening degree and the pressure. This reflects the change in the difference between the real-time pressure and the maximum pressure of the main hydraulic cylinder 1 during a given period. Reflecting real-time pressure changes, the ratio of these two values ​​can accurately match the characteristics of large pressure fluctuations in the initial stage of pressure relief. At the beginning of pressure relief, the real-time pressure P of the main cylinder 1 is close to Pmax. The numerical value is small, the ratio between the two is small, and the calculated A1% is small. This means that a small opening is used during the initial stage of pressure relief to avoid a sudden pressure drop caused by an excessively large opening during the initial stage of pressure relief, thus preventing shock. As pressure relief progresses, P gradually decreases. As the numerical value increases, the ratio between the two increases simultaneously, and A1% increases gradually, achieving a gradual increase in flow.

[0045] The second pressure relief equation passes through A correlation was established between the opening degree and the real-time pressure. In the initial stage of the second phase, the real-time pressure P of the main hydraulic cylinder 1 was still at a relatively high level, and the change in P was small. The rate of change is gradual, causing the calculated A2% to show a gradual increasing trend; as depressurization continues, P gradually decreases to a lower level, at which point even a small change in P will trigger... The rate of change of A2% increased significantly, which in turn led to a steep increase in the slope of A2%, which was adapted to the pressure relief requirements in the later stage of the second phase.

[0046] From the implementation results, the two pressure relief equations, through differentiated pressure correlation logic, achieve precise adaptation for staged pressure relief: the first pressure relief equation can effectively suppress pressure surges in the initial stage of pressure relief, ensuring stable initial pressure relief; the second pressure relief equation, with its characteristic of "gradual increase followed by a steep increase in slope," can maintain pressure relief stability in the early stage of the second phase, avoiding sudden changes in flow rate, and can also improve the overall pressure relief efficiency by rapidly increasing the opening in the later stage of the second phase. Meanwhile, the correction coefficients C1 and C2 in the two equations can be flexibly adjusted according to the flow requirements of different operating conditions, further enhancing the adaptability of the pressure relief system to diverse operating conditions.

[0047] The pressure relief system control method further includes the following steps: When the calculation result A1% of the first pressure relief equation is greater than or equal to the calculation result A%2 of the second pressure relief equation, the opening change equation of the proportional valve 4 transitions from the first pressure relief equation to the second pressure relief equation.

[0048] When the calculation result A2% of the second pressure relief equation is ≥1, the valve opening of the proportional valve 4 is fixed at 100%.

[0049] During the depressurization process, the main controller synchronously calculates A1% of the first depressurization equation and A2% of the second depressurization equation in real time and continuously compares their values. When A1% ≥ A2%, the main controller triggers an equation switching command, smoothly transitioning the opening adjustment logic of the proportional valve 4 from the first depressurization equation to the second depressurization equation. This ensures continuous opening changes during the stage switching process and avoids flow fluctuations caused by equation switching. During the adjustment process using the second depressurization equation, the main controller continuously monitors the calculated A2% value. When A2% ≥ 1, it immediately controls the opening of the proportional valve 4 to be fixed at 100%, ceasing dynamic adjustment, thus completing the final depressurization process at maximum opening.

[0050] The transition condition of A1%≥A2% is based on the adaptability design of the two-stage pressure relief requirements. When the calculated opening value of the first stage is no longer less than that of the second stage, it indicates that the pressure relief process has adapted to the pressure characteristics of the second stage. At this time, switching equations can ensure the continuity of the pressure relief rhythm.

[0051] The correction coefficients C1 and C2 for the pressure relief flow rate during the first stage of pressure relief and the second stage of pressure relief are both positively correlated with the temperature T inside the main cylinder 1.

[0052] The main controller collects the temperature T data of the main cylinder 1's inner cavity in real time through the temperature sensor 8 installed in the first cavity 12, and determines the correction coefficients C1 and C2 at the corresponding temperature according to a preset positive correlation model. In the first stage of pressure relief, the correction coefficient C1 matching the current temperature T is substituted into the first pressure relief equation to calculate the opening degree A1 of the proportional valve 4 adapted to the temperature conditions in this stage; after entering the second stage of pressure relief, the correction coefficient C2 matching the current temperature T is substituted into the second pressure relief equation to calculate the opening degree A2 of the proportional valve 4 adapted to the temperature conditions, and then the operation of the proportional valve 4 is adjusted according to the corresponding opening degree.

[0053] The temperature T inside the main cylinder 1 affects the viscosity of the oil, which in turn affects the pressure relief flow rate and response characteristics. When the temperature rises, the oil viscosity decreases and the fluidity improves. If the correction coefficient C1 remains unchanged, the opening A1% of the proportional valve 4 calculated using the first pressure relief equation will be too small, making it difficult to ensure that the pressure relief flow rate meets the operating requirements and potentially leading to a decrease in pressure relief efficiency. Therefore, it is necessary to increase the value of the correction coefficient C1 and correspondingly increase the opening of the proportional valve 4 through the first pressure relief equation to compensate for the impact of decreased viscosity on the flow rate and ensure that the pressure relief flow rate meets expectations. When the temperature decreases, the oil viscosity increases and the fluidity deteriorates. If C1 remains unchanged, the calculated A1% will be too large, easily causing pressure relief shocks. Therefore, it is necessary to decrease the value of the correction coefficient C1 and correspondingly decrease the opening of the proportional valve 4 through the equation to avoid the above problems.

[0054] The above are preferred embodiments of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A pressure relief system, characterized in that, The system includes a main hydraulic cylinder, an oil tank connected to the main hydraulic cylinder, a control valve, and a proportional valve. The main hydraulic cylinder includes a piston that divides the inner cavity of the main hydraulic cylinder into a first cavity and a second cavity. The oil tank is connected to the first cavity through a filling valve, and the control valve controls the filling valve to open or close. When the filling valve is closed, the proportional valve is connected to the first chamber through the first oil circuit, and the proportional valve is connected to the oil tank through the control valve. The proportional valve can depressurize the inner cavity of the main cylinder. During depressurization, the opening degree of the proportional valve can be infinitely adjusted according to the pressure in the inner cavity of the main cylinder and / or the depressurization flow rate.

2. The pressure relief system according to claim 1, characterized in that, The proportional valve includes a first interface and a second interface. The first interface is connected to the first oil circuit, and the second interface is connected to an external hydraulic source.

3. The pressure relief system according to claim 2, characterized in that, The proportional valve also includes a third interface, which is connected to the control valve via a second oil circuit.

4. The pressure relief system according to claim 3, characterized in that, The proportional valve can switch between a state where the first interface is connected to the second interface and a state where the first interface is connected to the third interface.

5. The pressure relief system according to any one of claims 1-4, characterized in that, The filling valve also includes a valve port and a valve stem. The control valve controls the descent and ascent of the valve stem to achieve communication and closure between the valve port and the first chamber.

6. The pressure relief system according to claim 5, characterized in that, The filling valve also includes a filling cylinder, and the valve stem divides the inner cavity of the filling cylinder into a third cavity and a fourth cavity. The control valve is connected to the third cavity through a third oil passage, and the control valve is connected to the fourth cavity through a fourth oil passage.

7. The pressure relief system according to claim 1, characterized in that, The control valve is connected to the second chamber via a fifth oil passage; and / or, The pressure relief system also includes an oil passage, which connects the oil tank and the first chamber, and the filling valve is located at the connection between the oil passage and the first chamber.

8. The pressure relief system according to claim 4, characterized in that, The pressure relief system further includes a control oil circuit, through which a control valve is connected to the proportional valve. The control valve is capable of controlling the proportional valve to switch between a state where the first interface is connected to the second interface and a state where the first interface is connected to the third interface; and / or The control valve is connected to the oil tank via the sixth oil passage.

9. A control method for a pressure relief system, characterized in that, For controlling the pressure relief system as described in any one of claims 1-8, the following steps are included: In the first stage of depressurization, the proportional valve uses a first preset opening degree to depressurize; In the second stage of depressurization, the proportional valve uses a second preset opening degree to depressurize; Wherein, the first preset opening degree is not greater than the second preset opening degree.

10. The pressure relief system control method according to claim 9, characterized in that, The pressure relief system control method further includes the following steps: During the first stage of depressurization, the opening degree of the proportional valve is adjusted according to a first preset adjustment method; During the second stage of depressurization, the opening degree of the proportional valve is adjusted according to the second preset adjustment method; The first preset adjustment method and the second preset adjustment method are both determined by at least the pressure and pressure relief flow rate of the main cylinder cavity.

11. The pressure relief system control method according to claim 10, characterized in that, The pressure relief system control method further includes the following steps: In the first stage of depressurization, the opening degree of the proportional valve is adjusted according to a first depressurization equation, wherein the first depressurization equation is: ; In the second stage of depressurization, the opening degree of the proportional valve is adjusted according to the second depressurization equation, wherein the second depressurization equation is: ; Wherein, A1% is the opening degree of the proportional valve in the first stage of pressure relief, C1 is the correction coefficient of the pressure relief flow rate in the first stage of pressure relief, and Pmax is the maximum pressure in the first stage of pressure relief; A2% is the opening degree of the proportional valve in the second stage of pressure relief, C2 is the correction coefficient of the pressure relief flow rate in the second stage of pressure relief, and P is the real-time pressure of the main cylinder.

12. The pressure relief system control method according to claim 11, characterized in that, When the calculation result A1% of the first pressure relief equation is greater than or equal to the calculation result A%2 of the second pressure relief equation, the opening change equation of the proportional valve transitions from the first pressure relief equation to the second pressure relief equation. When the calculation result A2%≥1 of the second pressure relief equation, the valve opening of the proportional valve is fixed at 100%.

13. The pressure relief system control method according to claim 11, characterized in that, The correction coefficient C1 for the pressure relief flow rate during the first stage of pressure relief and the correction coefficient C2 for the pressure relief flow rate during the second stage of pressure relief are both positively correlated with the temperature T inside the main cylinder.

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