Electromagnetic spill valve and control method thereof

Abstract

The present application relates to a kind of electromagnetic overflow valve and its control method, electromagnetic overflow valve includes electronic control unit, main valve and n pilot valve, n>1, main valve and each pilot valve between respectively in series with one damping hole, and the size of the damping hole between main valve and each pilot valve is different, pilot valve is electromagnetic valve, electronic control unit connects each pilot valve.Compared with prior art, the present application improves the pressure regulating instability problem of overflow valve under wide temperature range working condition, when temperature is lower, the pilot branch with larger diameter damping hole is in pressure regulating control state, and the rest pilot branch is in closed state;When temperature is higher, the pilot branch with smaller diameter damping hole is in pressure regulating control state, and the rest pilot branch is in closed state, so that the overflow valve keeps stable pressure regulating state under the working condition that temperature change leads to oil viscosity change, it can be applied to more kinds of extreme temperature change working environment and stable work.

Description

Technical Field

[0001] This invention relates to the field of fluid control technology, and in particular to an electromagnetic relief valve suitable for wide temperature range operating conditions and its control method. Background Technology

[0002] Hydraulic transmission technology features high force density, high standardization, and easy overload protection, and is widely used in aerospace, shipbuilding, port machinery, and construction machinery. Stable pressure in the hydraulic system is crucial for the safe operation and precise execution of the hydraulic power system. Relief valves are typically used for pressure control in hydraulic power systems; they are essential components for pressure control.

[0003] Relief valves can be classified into two types according to their structure: direct-acting relief valves and pilot-operated relief valves. Direct-acting relief valves are single-stage structures with fast response times and are generally used as the pilot stage in safety valves and pilot-operated relief valves. Pilot-operated relief valves were first designed by Harry Vickers in 1931 (Harry Vickers. Liquid Relief Valve [P]. US2043453, USA, 1931). They exhibit good performance under high-pressure and high-flow conditions and are widely used. However, both direct-acting and pilot-operated types experience problems such as pressure regulation instability and high-frequency vibration during use, significantly affecting the reliability of hydraulic systems. Scholars have conducted extensive research on this topic. For example, Hayashi from Japan proposed a method for analyzing the stability and nonlinear characteristics of pilot-operated relief valves and their hydraulic circuits (S. Hayashi. Instability of poppet valve circuit. JSME International Journal, 1995, 38(3): 357-366); K. Dasgupta from India introduced a modeling and simulation method for the dynamic characteristics of pilot-operated relief valves (K. Dasgupta, R. Karmakar. Dynamic analysis of pilot operated pressure relief valve. Simulation Modeling Practice and Theory. 2002(10): 35-49); and Johnston N from Italy used frequency domain analysis to study the stability of relief valves from the perspective of flow resistance (Johnston N, Edge KA and Brunelli M. Impedance and stability characteristics of a relief valve. Proceedings of the Institution of Mechanical Engineers Part I: Journal of Systems and Control). Engineering 2002; 216(5):371-382.); American Merrit proposed using a reasonable match between a damping throttle and the liquid capacity to improve the dynamic performance of the relief valve (HEMerrit. Hydraulic control systems[M]. John Willy & Sons, 1967). Chinese scholars have studied the dynamic performance of the relief valve and the mechanism of valve vibration, and proposed corresponding improvement measures.The Shanghai Aerospace Bureau studied a direct-acting relief valve with a balance piston at the end of the valve core. The results showed that the single-stage relief valve with a fixed throttle valve and a balance piston has a three-in-one comprehensive function of vibration reduction, noise reduction and pressure stabilization, and can achieve precise pressure control (Yin Yaobao. Mechanism and characteristic analysis of single-stage relief valve with fixed throttle valve and balance piston. Shanghai Aerospace, 1995, 3:14-17). Tongji University proposed a stability criterion for an extremely small-sized double-stage relief valve and pointed out that when the volume of the main valve spring cavity and the mass of the pilot valve core cannot be increased due to space size and processing level, a damping orifice of appropriate size can be designed between the pilot valve and the main valve to improve its stability (Yin Yaobao, Yuan Jiayang, Fu Junyong. Characteristics of a new type of double-stage relief valve with a damping orifice added to the front cavity of the pilot valve. Journal of Jilin University, 2017, 47(01):129-136). Huaqiao University proposed a relief valve using a magnetorheological pilot valve. It uses a magnetorheological fluid as the working medium of the pilot valve. The opening pressure of the relief valve is controlled by adjusting the current intensity in the magnetorheological pilot valve coil and the preload of the pilot valve spring. This achieves the purpose of real-time, automated, and intelligent control and increases the pressure regulation range. It also has the characteristics of rapid response (Liu Xiaomei, Li Hongyou. A relief valve using a magnetorheological pilot valve: China, CN104633233B[P]. 2017-10-20).

[0004] Chinese patent application 202310083477.X discloses a two-stage relief valve with a structure of three consecutive series-connected throttling orifices. This two-stage relief valve comprises a main valve and a pilot valve, and its structure is as follows: Figure 2 As shown, the pilot valve controls the opening and closing of the main valve, and the main valve controls the system pressure. To enhance the stability of the two-stage relief valve, a damping orifice of suitable size is added between the main valve and the pilot valve. The damping orifice, together with the main valve core throttling orifice and the pilot valve fixed throttling orifice, forms a three-series throttling orifice structure, enabling the improved two-stage relief valve to operate stably at the rated flow rate, thereby improving its dynamic performance. However, when the hydraulic system is in an extreme high-low temperature transition environment, the viscosity of the hydraulic fluid will also change with the ambient temperature. At this time, the flow capacity of the damping orifice between the main valve and the pilot valve will change, and its hydraulic resistance will also change, thus affecting the pressure regulation stability of the relief valve and causing the hydraulic system pressure regulation to become unstable. Therefore, for the working conditions of extreme high-low temperature transition, the pressure regulation scheme of this hydraulic system needs to be improved. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects of the prior art by providing an electromagnetic overflow valve and its control method.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] According to a first aspect of the present invention, an electromagnetic relief valve is provided, comprising an electronic control unit, a main valve, and n pilot valves, n>1, wherein a damping orifice is connected in series between the main valve and each pilot valve, and the size of the damping orifice between the main valve and each pilot valve is different, wherein the pilot valve is an electromagnetic valve, and the electronic control unit is connected to each pilot valve.

[0008] Furthermore, it also includes a temperature sensor connected to the electronic control unit, the temperature sensor being configured to measure the temperature of the oil.

[0009] Furthermore, the temperature sensor is installed in the oil tank and immersed in the oil.

[0010] Furthermore, the electronic control unit includes system circuitry, drive circuitry, and input / output interfaces.

[0011] Furthermore, the electronic control unit sends a first signal or a second signal to each pilot valve, and the pilot valve is configured to: receive the first signal and be in a pressure regulating state, or receive the second signal and be in a closed state.

[0012] Furthermore, the damping orifices between the main valve and each pilot valve have the same length but different diameters.

[0013] Furthermore, the main valve is connected to n pilot valves through n parallel branches, and the damping orifice between the main valve and each pilot valve is set on the branch.

[0014] According to a second aspect of the present invention, a method for controlling an electromagnetic relief valve is provided, comprising controlling the electromagnetic relief valve described in the first aspect of the present invention, including:

[0015] The electromagnetic relief valve is pre-set to operate in different working conditions. In each working mode, one pilot valve is in the pressure regulating state and the other pilot valves are in the closed state.

[0016] The electronic control unit acquires real-time operating information and controls the electromagnetic relief valve to enter the corresponding working mode based on the operating information.

[0017] Furthermore, the different operating conditions refer to different oil temperature ranges, and the real-time operating condition information refers to the real-time oil temperature.

[0018] Furthermore, in the preset multiple operating modes, as the oil temperature range of the operating condition increases, the damping orifice size corresponding to the pilot valve in the pressure regulating state decreases.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] (1) This invention improves the pressure regulation instability problem of relief valve under wide temperature range conditions. Temperature factors are considered during the pressure regulation process. When the temperature is low, the pilot branch with the larger diameter damping orifice is in the pressure regulation control state, while the other pilot branches are in the closed state. When the temperature is high, the pilot branch with the smaller diameter damping orifice is in the pressure regulation control state, while the other pilot branches are in the closed state. Thus, the relief valve maintains a stable pressure regulation state under the condition that the oil viscosity changes due to temperature changes, and can be applied to and operate stably in a variety of extreme temperature change working environments.

[0021] (2) The oil temperature is regarded as one of the factors affecting the dynamic characteristics of the pressure regulation of the relief valve, and targeted improvements are made, which greatly reduces the application limitations of the relief valve in a wide temperature range.

[0022] (3) In theory, any number of pilot branches greater than zero can be connected in parallel in the pressure regulation method of the relief valve to improve the pressure regulation stability of the hydraulic system in a wide temperature range and has strong scalability.

[0023] (4) The present invention can also adopt the structure of a cartridge-type integrated valve block to improve space utilization.

[0024] (5) The present invention can be easily transformed into a relief valve pressure regulation method suitable for another variable by adjusting the sensor type and relief valve model, such as multiple flow and pressure conditions. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the electromagnetic overflow valve pressure regulation scheme in an embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram of a common overflow valve pressure regulation scheme in an embodiment of the present invention;

[0027] Figure 3 This is the output pressure curve of the electromagnetic overflow valve pressure regulation provided by the present invention under wide temperature range conditions;

[0028] Figure 4 This is the output pressure curve of a common overflow valve pressure regulation scheme under wide temperature range conditions.

[0029] Explanation of markings in the diagram: 1. Hydraulic pump; 2-1. Relief valve pressure regulating module of the present invention; 2-2. Ordinary relief valve pressure regulating module; 3. Hydraulic system load; 4. Main valve; 5. Pilot valve (including 5-1, 5-2...5-n); 6. Electronic control unit; 7. Temperature sensor; 8. Main valve pressure control chamber; 9. Main valve core; 10. Main valve core throttle orifice; 11. Main valve spring chamber; 12. Main valve spring; 13. Damping orifice between the main valve and the pilot valve (including 13-1, 13-2...13-n); 14. Fixed throttle orifice before the pilot valve pressure sensing chamber; 15. Pilot valve pressure sensing chamber; 16. Pilot valve core; 17. Pilot valve pressure control chamber; 18. Pilot valve spring; 19. Pilot valve core armature; 20. Pilot valve proportional electromagnet; 21. Hydraulic oil tank. Detailed Implementation

[0030] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are implemented based on the technical solutions of the present invention, providing detailed implementation methods and specific operating procedures. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them, and the scope of protection of the present invention is not limited to the following embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0031] In the accompanying drawings, components with the same structure are indicated by the same numerical designation, and components with similar structures or functions are indicated by similar numerical designations. The dimensions and thicknesses of each component shown in the drawings are arbitrary, and the present invention does not limit the dimensions and thicknesses of each component. To make the illustrations clearer and show the mating relationships between the components, some parts in the drawings have been appropriately scaled down, and the distances between the components have been increased or decreased.

[0032] In the description of the embodiments of this application, it should be understood that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly placed when the product of this application is used, or the orientation or positional relationship commonly understood by those skilled in the art. They are only for the convenience of describing this application and simplifying the description, and are not intended to indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0033] In the description of the embodiments of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0034] Example 1:

[0035] The structure of the two-stage relief valve (ordinary relief valve) proposed in Chinese patent application 202310083477.X is as follows: Figure 2 As shown, in a typical relief valve pressure regulating scheme, 1 represents the hydraulic pump, 2-2 represents the typical relief valve pressure regulating module, and 3 represents the hydraulic system load. The typical relief valve pressure regulating module 2-2 includes a main valve 4 and a pilot valve 5. When the oil flows into the main valve front chamber (main valve pressure control chamber 8), it enters the main valve spring chamber 11 through the main valve core throttle orifice 10 on the main valve core 9, then flows into the pilot valve pressure control chamber 17 through the damping orifice 13 between the main valve 4 and the pilot valve 5, and finally enters the pilot valve pressure sensing chamber 15 through the pilot valve fixed throttle orifice 14. When the pressure p in the pilot valve pressure sensing chamber 15... d When the pressure is increased enough to overcome the preload of the pilot valve spring 18, the pilot valve 5 opens and generates an overflow flow Q. x This causes a pressure difference to be generated at both ends of the main valve core 9 under the throttling effect of the main valve core throttling orifice 10. When this pressure difference is sufficient to overcome the preload of the main valve spring 12, the main valve 4 opens and generates an overflow flow Q. y This pressure regulating scheme has only one pilot branch (the connection branch between the main valve 4 and the pilot valve 5 + pilot valve 5). The size of the damping orifice 13 is fixed, but the oil viscosity decreases as the temperature rises and increases as the temperature falls. Therefore, the flow performance varies at different temperatures, and it cannot adjust the structural parameters of the components involved in pressure regulation according to temperature changes. The problem with this two-stage relief valve is that, under wide temperature range conditions, temperature changes cause changes in oil viscosity, making the relief valve system an unstable control system. During pressure regulation, this causes large fluctuations in system pressure, severely reducing the stability of the hydraulic system.

[0036] Based on this, the present invention provides an electromagnetic relief valve, including an electronic control unit 6, a main valve 4 and n pilot valves 5, n>1. A damping orifice 13 (13-1 to 13-n) is connected in series between the main valve 4 and each pilot valve 5, and the damping orifice 13 (13-1 to 13-n) between the main valve 4 and each pilot valve 5 has different dimensions. The pilot valve 5 is an electromagnetic valve. The electronic control unit 6 is connected to each pilot valve 5 and controls each pilot valve 5.

[0037] A control method for an electromagnetic relief valve includes:

[0038] The electromagnetic relief valve is pre-set to operate in different modes for different working conditions. In each mode, one pilot valve 5 is in a pressure regulating state and the other pilot valves 5 are in a closed state. The electronic control unit 6 acquires real-time operating condition information and controls the electromagnetic relief valve to enter the corresponding operating mode based on the operating condition information.

[0039] In this application, such as Figure 1 As shown, multiple pilot valves 5 are configured, and n pilot valves 5 are connected to the main valve 4 through n parallel branches. n damping orifices 13 are respectively located on these branches, and the size of the damping orifices 13 on each branch is different. That is, there are n pilot branches, and each pilot branch has a damping orifice 13 of a different size. The operating state of each pilot valve 5 is controlled by an electronic control unit 6, thereby allowing the selection of pilot valves 5 with different damping orifice 13 sizes under different operating conditions to ensure pressure stability.

[0040] It is understood that this application is essentially an improvement on an existing ordinary relief valve. The size of the damping orifice 13 between the main valve 4 and the pilot valve 5 can be adjusted by controlling the state of the solenoid switch valve 14. The structure or model of the relief valve itself does not affect the effect. In fact, this application can be applied to two-stage relief valves of different models and structures, as long as the pilot valve 5 in the two-stage relief valve can switch between pressure regulating and closed states, and the size of the damping orifice 13 between the main valve 4 and each pilot valve 5 differs. For ease of explanation, this embodiment uses... Figure 1 and Figure 2 The two-stage overflow valve structure shown illustrates the working principle of the present invention.

[0041] The electronic control unit 6 includes system circuitry, drive circuitry, and input / output interfaces. External control signals can be input to the electronic control unit 6, which then switches the operating state of the pilot valve 5 based on these signals. Alternatively, a temperature sensor 7 can be installed, connected to the electronic control unit 6. The temperature sensor 7 is configured to measure the oil temperature and send the real-time oil temperature to the electronic control unit 6. The electronic control unit 6 has a built-in control program that switches the operating state of the pilot valve 5. In this embodiment, the temperature sensor 7 is installed in the oil tank 21 and submerged in the oil.

[0042] It is understandable that different operating conditions correspond to different oil temperature ranges, and real-time operating condition information refers to the real-time oil temperature. Depending on the required control accuracy and cost, multiple temperature ranges can be set, along with a corresponding number of pilot branches. Each damping orifice 13 corresponds to a specific temperature range. Within this temperature range, the pilot valve 5 corresponding to the damping orifice 13 is in a pressure regulating state, while other pilot valves 5 are closed, allowing oil flow through this damping orifice 13. When the temperature changes, the flow switches to the corresponding size damping orifice 13, ensuring the relief valve maintains a stable pressure regulating state across a wide temperature range, thus solving the problem of pressure regulation instability in the relief valve under wide temperature range conditions.

[0043] In this embodiment, the damping orifices 13 between the main valve 4 and each pilot valve 5 have the same length but different diameters. In other embodiments, the sizes of the damping orifices 13 (13-1 to 13-n) can also be different by adjusting other parameters.

[0044] The electronic control unit 6 is used to control whether the pilot valve 5 is in a pressure-regulating state. The electronic control unit 6 sends a first signal or a second signal to each pilot valve 5. The pilot valve 5 is a solenoid valve and is configured to: receive the first signal and be in a pressure-regulating state, and receive the second signal and be in a closed state. In this embodiment, the output current of the electronic control voltage has two cases, corresponding to the first signal and the second signal respectively: ① Zero current, at this time the pilot valve proportional electromagnet 20 does not output force to the pilot valve core armature 19, and the pilot valve core 16 is only subjected to the pressure from the pressure sensing chamber 15 and the spring force of the pilot valve spring 18. Under the action of the resultant force, the pilot valve 5 is in a pressure-regulating state and can control the opening and closing of the main valve 4; ② Positive current, under the action of this current, the pilot valve core armature 19 outputs force to the pilot valve spring 18 under the action of the pilot valve proportional electromagnet 20, which acts on the pilot valve core 16. At this time, the pilot valve core 16 is subjected to the pressure from the pressure sensing chamber 15, the spring force of the pilot valve spring 18, and the electromagnetic force of the pilot valve proportional electromagnet 20. Under the combined action of these three forces, the pilot valve 5 is in the closed state.

[0045] The specific applications of this application are as follows:

[0046] Temperature sensor 7 detects the oil temperature in oil tank 21, then converts the detected temperature information into a current signal and transmits it to electronic control unit 6. After receiving the current signal from temperature sensor 7, electronic control unit 6 compares and judges (electronic control unit 6 can set multiple temperature range judgment programs), and then outputs control current to the corresponding pilot valve proportional solenoid 20 according to the judgment result. The pilot valve proportional solenoid 20 outputs control force to the pilot valve core armature 19 according to the current transmitted from electronic control unit 6 to control whether the pilot valve 5 is in the pressure regulating state or the closed state.

[0047] In the multiple operating modes preset in this application, as the oil temperature range increases, the size of the damping orifice 13 corresponding to the pilot valve 5 in the pressure regulating state decreases. When the oil temperature is in a lower range, the electronic control unit 6 outputs zero current to the pilot oil circuit corresponding to the larger diameter damping orifice 13 to put it in the pressure regulating state, and outputs positive current to the other pilot oil circuits to put them in the closed state; when the oil temperature is in a higher range, the electronic control unit 6 outputs zero current to the pilot oil circuit corresponding to the smaller diameter damping orifice 13 to put it in the pressure regulating state, and outputs positive current to the other pilot oil circuits to put them in the closed state.

[0048] When the oil flows into the main valve front chamber (main valve pressure control chamber 8), it enters the main valve spring chamber 11 through the main valve core throttle orifice 10 on the main valve core 9, then flows into the pilot valve pressure control chamber 17 through the damping orifice 13 between the main valve 4 and the pilot valve 5, and finally enters the pilot valve pressure sensing chamber 15 through the pilot valve fixed throttle orifice 14. When the pressure p in the pilot valve pressure sensing chamber 15... d When the pressure is increased enough to overcome the preload of the pilot valve spring 18, the pilot valve 5 opens and generates an overflow flow Q. x This causes a pressure difference to be generated at both ends of the main valve core 9 under the throttling effect of the main valve core throttling orifice 10. When this pressure difference is sufficient to overcome the preload of the main valve spring 12, the main valve 4 opens and generates an overflow flow Q. y This achieves the purpose of regulating system pressure.

[0049] This invention provides an improved electromagnetic relief valve pressure regulation scheme applicable to a wide temperature range, addressing the problem of pressure regulation instability in relief valves under wide temperature range conditions. Temperature is considered during the pressure regulation process, ensuring a stable pressure regulation state for the relief valve even when temperature changes cause variations in oil viscosity. At lower temperatures, the pilot branch containing the larger diameter damping orifice 13 is in pressure regulation control mode, while the other pilot branches are closed. At higher temperatures, the pilot branch containing the smaller diameter damping orifice 13 is in pressure regulation control mode, while the other pilot branches are closed. This invention can ensure a stable pressure regulation state for the relief valve under a wide temperature range by setting multiple temperature range judgment programs in the electronic control unit 6 and coordinating them with a corresponding number of pilot branches, thereby solving the problem of pressure regulation instability in relief valves under wide temperature range conditions.

[0050] The output pressure curve of the electromagnetic relief valve pressure regulation scheme provided in this application under wide temperature range conditions is as follows: Figure 3 As shown, the data comes from dynamic numerical simulation of a pressure regulation method for an electromagnetic relief valve applicable to a wide temperature range, with an input flow rate of 220 L / min and 46# hydraulic oil. The figure shows the output pressure curves of this application at temperatures of 0℃, 20℃, 40℃, 60℃, and 80℃. Figure 3As can be seen, within the temperature range of 0℃ to 80℃, after the system begins to build up pressure, the system pressure exhibits a fluctuating state of energy decay after overshoot, and after a short period of adjustment, the system pressure stabilizes. This demonstrates that the present invention can output stable pressure under wide temperature range conditions without affecting the normal operation of the hydraulic system.

[0051] The output pressure curve of a conventional electromagnetic overflow valve pressure regulation scheme under wide temperature range conditions is as follows: Figure 4 As shown, the data comes from dynamic numerical simulation of a common relief valve pressure regulation method, with an input flow rate of 220 L / min and 46# hydraulic oil. The figure shows the output pressure curves of the common scheme applied at temperatures of 0℃, 20℃, 40℃, 60℃, and 80℃. Figure 4 As can be seen, at 0℃, after the system starts to build up pressure, the system pressure exhibits a fluctuating state of energy decay after overshoot, and then stabilizes after a short period of adjustment. However, at temperatures of 20℃, 40℃, 60℃, and 80℃, the system pressure exhibits a continuous fluctuation after overshoot, and the amplitude of this fluctuation increases with increasing temperature. When the temperature reaches 80℃, the fluctuation amplitude can reach 7.14MPa. This shows that the ordinary relief valve pressure regulation scheme cannot output stable pressure under wide temperature range conditions. The fluctuating system pressure is detrimental to the normal operation of the hydraulic system, reducing its reliability and safety.

[0052] In summary, this invention enables more precise and stable pressure regulation of the relief valve over a wide temperature range, making it applicable to various flow and pressure conditions. Therefore, compared to existing relief valve pressure regulation solutions, this application is suitable for working environments with more extreme temperature variations.

[0053] Example 2:

[0054] This application achieves multi-stage control by setting multiple pilot valves 5 with damping orifices 13 of different sizes. Example 1 uses temperature as the control variable, thereby stabilizing the pressure of the hydraulic system within a set range in environments with extreme high and low temperature transitions, which has the advantage of improving the reliability of the hydraulic system over a wide temperature range. In this example, the sensor type and relief valve model are adjusted to transform the relief valve pressure regulation scheme suitable for other variables, such as flow rate and pressure conditions. The basic principle remains the same and will not be elaborated further here, as those skilled in the art will understand.

[0055] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. An electromagnetic relief valve, characterized in that, It includes an electronic control unit, a main valve, and n pilot valves, where n>1. Each pilot valve is connected in series with a damping orifice, and the size of the damping orifice between the main valve and each pilot valve is different. Each pilot valve is a solenoid valve, and the electronic control unit is connected to each pilot valve. The electronic control unit sends a first signal or a second signal to each pilot valve, and the pilot valve is configured to: receive the first signal and be in a pressure regulating state, or receive the second signal and be in a closed state. The main valve is connected to n pilot valves through n parallel branches, and the damping orifice between the main valve and each pilot valve is set on the branch. The temperature sensor is configured to measure the temperature of the oil. The electromagnetic relief valve is pre-set to operate in different working conditions. In each working mode, one pilot valve is in the pressure regulating state and the other pilot valves are in the closed state. The electronic control unit acquires real-time operating condition information, determines the working mode based on the real-time operating condition information, and controls the two-stage relief valve to enter the corresponding working mode. The different operating conditions refer to different oil temperature ranges, and the real-time operating condition information refers to the real-time oil temperature. In the preset multiple operating modes, as the oil temperature range of the operating condition increases, the damping orifice size corresponding to the pilot valve in the pressure regulating state decreases.

2. The electromagnetic relief valve according to claim 1, characterized in that, The temperature sensor is installed in the oil tank and immersed in the oil.

3. The electromagnetic relief valve according to claim 1, characterized in that, The electronic control unit includes system circuits, drive circuits, and input / output interfaces.

4. The electromagnetic relief valve according to claim 1, characterized in that, The damping orifices between the main valve and each pilot valve have the same length but different diameters.

5. A control method for an electromagnetic relief valve, characterized in that, Based on the electromagnetic relief valve as described in any one of claims 1-4, comprising: The electromagnetic relief valve is pre-set to operate in different working conditions. In each working mode, one pilot valve is in the pressure regulating state and the other pilot valves are in the closed state. The electronic control unit acquires real-time operating condition information, determines the working mode based on the real-time operating condition information, and controls the two-stage relief valve to enter the corresponding working mode. The different operating conditions refer to different oil temperature ranges, and the real-time operating condition information refers to the real-time oil temperature. In the preset multiple operating modes, as the oil temperature range of the operating condition increases, the damping orifice size corresponding to the pilot valve in the pressure regulating state decreases.

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