An electro-hydraulic actuator underwater working condition simulation test system and loading method

Abstract

The application discloses an underwater working condition simulation test system and loading method of an electro-hydraulic actuator. The application is based on a test system mainly composed of a gear pump, a pressure compensator, a loading valve group and a loading cylinder. By adjusting the opening pressure of a proportional overflow valve in the loading valve group and combining oil supply of the pressure compensator and the gear pump, the application can realize multi-condition hydraulic load simulation of the electro-hydraulic actuator under underwater high-pressure environment. The application can adjust the oil line pressure of the system through the pressure compensator, adjust and control the active extension and retraction of the piston rod of the loading cylinder and the control cavity pressure through the proportional overflow valve, so as to realize multi-condition hydraulic load simulation under underwater high-pressure environment. The application can judge the safety condition of the system through a sensor, and in the case of unsafe condition, the application can close the oil-immersed motor and make the electromagnetic reversing valve in a power-off state through the controller, so as to ensure the safety of the system. Through the series connection of the overflow valve and the proportional overflow valve, the application can realize high-precision control of the control cavity pressure and the loading force of the loading cylinder.

Description

Technical Field

[0001] This invention relates to an electro-hydraulic actuator testing system, in the field of hydraulic technology, specifically to an underwater operating condition simulation testing system and loading method for electro-hydraulic actuators. Background Technology

[0002] The underwater electro-hydraulic actuator (EHA) is the core unit for marine engineering equipment to perform operations. Its pressure resistance, sealing performance, service life, and motion performance under complex deep-sea conditions are crucial to the normal and stable operation of the marine engineering equipment. However, due to the high cost and long testing cycle of sea trials, it is difficult to conduct performance tests in a truly marine environment, especially in the deep sea. Therefore, it is necessary to design a simulation test platform to conduct full-condition load simulation tests on the underwater electro-hydraulic actuator (EHA).

[0003] In the field of hydraulic transmission, when testing and verifying the response characteristics of the actuators and electro-hydraulic control algorithms of experimental devices, it is necessary to simulate the actual working conditions of the experimental equipment as closely as possible. This is done by simulating the load faced by the actuators through mechanical or hydraulic loading. In linear motion, hydraulic load simulation is mainly achieved by combining a loading cylinder with a proportional relief valve, a proportional throttle valve, or a balance valve. The load force is simulated by setting the valve opening to create a certain back pressure, and the magnitude of the set back pressure is controlled by an external electrical signal.

[0004] Currently, existing high-pressure sealing chambers can only test the pressure resistance and sealing performance of the tested object. They cannot complete the load simulation test of various operating conditions of electro-hydraulic actuators under pressure. Furthermore, traditional actuator load simulation test platforms mostly adopt passive loading methods, that is, the loading cylinder cannot actively extend or retract, and cannot actively generate and apply load loading force. Summary of the Invention

[0005] To address the problems existing in the background art, this invention proposes an underwater operating condition simulation test system and loading method for electro-hydraulic actuators. The system and method of this invention can simulate positive and negative load conditions for electro-hydraulic actuators under underwater high-pressure environments.

[0006] The technical solution adopted in this invention is:

[0007] I. An underwater operating condition simulation test system for electro-hydraulic actuators:

[0008] The testing system includes an oil source component, which is used to supply oil power to the underwater working condition simulation testing system during testing under underwater high pressure environment;

[0009] The testing system includes a safety valve assembly, which is connected to the oil source components and is used for safety control when the underwater working condition testing system is tested in an underwater high-pressure environment;

[0010] The testing system includes a loading valve assembly, a connecting oil source component, and a safety valve assembly, and is used to simulate different underwater load conditions under underwater high pressure to actively load the underwater operating condition testing system.

[0011] The testing system includes an actuator, a connected loading valve group, and is used to simulate active loading under different underwater load conditions in a high-pressure underwater environment by adjusting the oil source component and the loading valve group, in order to test the electro-hydraulic actuator.

[0012] Underwater high-pressure environment refers to an underwater environment with a pressure higher than the preset level.

[0013] The loading valve assembly includes a second check valve, a third check valve, a fourth check valve, a fifth check valve, a second pressure testing connector, a third pressure testing connector, a second pressure sensor, a third pressure sensor, a second relief valve, a third relief valve, a first proportional relief valve, a second proportional relief valve, and a solenoid directional valve. The inlets of the second and third check valves are connected to the safety valve assembly. The oil passage connecting the outlet of the second check valve and the actuator is second oil passage b, and the oil passage connecting the outlet of the third check valve and the actuator is third oil passage c. The inlet of the fifth check valve is connected to second oil passage b between the outlet of the second check valve and the inlet of the solenoid directional valve. The outlet of the fifth check valve, the inlet of the second proportional relief valve, and the inlet of the third relief valve are also connected to the second oil passage b. The oil circuit is connected in sequence: the outlet of the fourth check valve, the inlet of the first proportional relief valve, and the inlet of the second relief valve are connected in sequence; the oil circuit between the outlet of the second relief valve and the outlet of the third relief valve is connected to the oil circuit of the safety valve assembly as the fourth oil circuit d; the oil inlet of the fourth check valve is connected to the third oil circuit c between the outlet of the third check valve and the inlet of the solenoid directional valve; the inlet and outlet of the solenoid directional valve are connected to the second oil circuit b and the third oil circuit c, respectively; the second pressure tester and the second pressure sensor are connected to the second oil circuit b, and the third pressure tester and the third pressure sensor are connected to the third oil circuit c; the loading valve assembly is also threadedly connected to a second pressure compensator for oil pressure compensation of the underwater working condition simulation test system under simulated underwater high pressure environment. The second pressure compensator is fixedly connected to the loading valve assembly by a flange threaded connection.

[0014] The safety valve assembly includes a first check valve, a pressure filter, a first relief valve, a first pressure testing connector, and a first pressure sensor. The inlet of the first check valve is connected to the oil source assembly, and the outlet of the first check valve is connected to the inlet of the first relief valve via the pressure filter. The inlet of the first relief valve is connected between the inlets of the second and third check valves of the loading valve assembly. The oil passage connecting the outlet of the first relief valve and the oil source assembly is designated as the first oil passage a. The outlet of the first relief valve and the outlet of the second relief valve of the loading valve assembly are connected via a fourth oil passage d. The first pressure testing connector and the first pressure sensor are connected to the inlet of the first relief valve.

[0015] The oil source components include an oil tank, a pressure and temperature sensor, an oil suction filter, an oil-immersed motor, and a gear pump. The oil-immersed motor is connected to the gear pump via a coupling. The oil suction port of the gear pump is connected to the oil tank via the oil suction filter. The pressure and temperature sensor is located inside the oil tank. The oil outlet of the gear pump is connected to the oil inlet of the first check valve of the safety valve assembly. The oil tank is connected to the oil outlet of the first relief valve of the safety valve assembly via the first oil passage a. The oil tank and the safety valve assembly are also threadedly connected to a first pressure compensator for oil pressure compensation of the underwater working condition simulation test system under simulated underwater high pressure environment.

[0016] The actuator includes a pressure-resistant displacement sensor, a loading cylinder, and a hinge mechanism. The loading cylinder is a symmetrical cylinder. The first chamber A of the loading cylinder is connected to the oil outlet of the second check valve of the loading valve group via the second oil passage b. The second chamber B of the loading cylinder is connected to the oil outlet of the third check valve of the loading valve group via the third oil passage c. The pressure-resistant displacement sensor is installed at the end of the piston rod on the first chamber A side of the loading cylinder. The piston rod on the second chamber B side of the loading cylinder is connected to the piston rod of the hydraulic cylinder of the electro-hydraulic actuator EHA under test through the hinge mechanism.

[0017] II. A loading method for an underwater operating condition simulation test system for electro-hydraulic actuators:

[0018] The underwater operating condition simulation test system first sets the opening pressure of the first relief valve of the safety valve group to be higher than the preset maximum pressure of the underwater operating condition simulation test system to protect the normal operation of the hydraulic system. When the underwater operating condition simulation test system is not working, the solenoid directional valve is de-energized, and the second oil circuit b and the third oil circuit c are connected. When the underwater operating condition simulation test system is performing test work, the immersion motor and gear pump are in working state, the solenoid directional valve is energized, and the first chamber port A and the second chamber port B of the loading cylinder are not connected. At this time, the underwater operating condition simulation test system is placed in a simulated underwater high-pressure environment inside a pressure vessel, wherein the controllers of the first proportional relief valve, the second proportional relief valve, the solenoid directional valve, and the immersion motor are all located outside the pressure vessel. During the test, the second oil circuit b and the third oil circuit c of the underwater operating condition simulation test system are disconnected, and the gear pump draws oil from the oil tank through the suction filter. The oil outlet of the gear pump delivers high-pressure hydraulic oil with a pressure higher than the preset threshold through the first check valve and the pressure filter to the second check valve and the third check valve. High-pressure hydraulic oil flows into the second oil circuit b and the third oil circuit c through the second and third check valves, respectively. The fourth and fifth check valves are in the open state. By adjusting the oil source assembly, loading valve group, and two pressure compensators, namely adjusting the opening pressure of the first and second proportional relief valves, and the oil supply combination of the first and second pressure compensators and the gear pump, active loading of four underwater load conditions is simulated to test the hydraulic cylinder of the electro-hydraulic actuator EHA under test. The four underwater load conditions include two positive load conditions and two negative load conditions. The oil temperature, pressure, and piston rod displacement of the loading cylinder of the underwater condition simulation test system are monitored in real time by a pressure-resistant temperature sensor, three pressure sensors, and a pressure-resistant displacement sensor. When the oil temperature exceeds the preset temperature, the oil pressure exceeds the preset pressure, or the piston rod displacement of the loading cylinder exceeds the preset displacement range, the controller shuts down the immersion motor and de-energizes the solenoid directional valve to ensure system safety.

[0019] In the first positive load condition of the underwater load operation, the simulation is achieved through a gear pump and a second proportional relief valve that regulates the pressure at the first chamber A of the loading cylinder. The first chamber A of the loading cylinder is the control chamber. The hydraulic pressure in the third oil circuit c is the sum of the opening pressures of the first and second proportional relief valves. The input current signal in the first proportional relief valve is kept constant to maintain a constant hydraulic pressure in the third oil circuit c. The depressurized hydraulic oil flows to the second chamber B of the loading cylinder. The hydraulic pressure in the second oil circuit b is the sum of the opening pressures of the second and third proportional relief valves. The input current signal in the second proportional relief valve is kept constant to maintain a constant hydraulic pressure in the third oil circuit c. The magnitude of the input current signal is adjusted to change its own opening pressure, thereby reducing the pressure of the hydraulic oil in the second oil circuit b. The depressurized hydraulic oil flows to the first chamber A of the loading cylinder. The opening pressure of the second proportional relief valve is changed to control the pressure of the first chamber A of the loading cylinder to be greater than that of the second chamber B. The loading cylinder forms a dynamic load loading force to the right. The piston rod of the actuator hydraulic cylinder extends and the thrust generated acts on the piston rod of the loading cylinder through the hinge mechanism. At this time, the direction of the dynamic load loading force of the loading cylinder is opposite to the direction of the main power of the actuator hydraulic cylinder of the electro-hydraulic actuator EHA under test, thus completing the simulation loading of the first positive load condition.

[0020] In the second positive load condition of the underwater load operation, the simulation is achieved through a gear pump and a first proportional relief valve that regulates the pressure at the second chamber B of the loading cylinder. The second chamber B of the loading cylinder is the control chamber. The oil pressure in the second oil circuit b is the sum of the opening pressures of the second proportional relief valve and the third relief valve. The input current signal in the second proportional relief valve is kept constant to maintain a constant oil pressure in the second oil circuit b. The depressurized hydraulic oil flows to the first chamber A of the loading cylinder. The oil pressure in the third oil circuit c is the sum of the opening pressures of the first proportional relief valve and the second relief valve. The input current signal in the first proportional relief valve is kept constant to maintain a constant oil pressure in the second oil circuit b. The magnitude of the input current signal is adjusted to change its own opening pressure, thereby reducing the pressure of the hydraulic oil in the third oil circuit c. The depressurized hydraulic oil flows to the second chamber B of the loading cylinder. The opening pressure of the first proportional relief valve is changed to control the pressure of the second chamber B of the loading cylinder to be greater than that of the first chamber A. The loading cylinder forms a dynamic load loading force to the left. The piston rod of the actuator hydraulic cylinder retracts and the generated tension is applied to the piston rod of the loading cylinder through the hinge mechanism. At this time, the direction of the dynamic load loading force of the loading cylinder is opposite to the direction of the main power of the actuator hydraulic cylinder of the electro-hydraulic actuator EHA under test, thus completing the simulation loading of the second positive load condition.

[0021] In the first underwater load condition, the simulation is achieved through a gear pump and a first proportional relief valve that regulates the pressure at the second chamber B of the loading cylinder. The second chamber B of the loading cylinder is the control chamber. The oil pressure in the second oil circuit b is the sum of the opening pressures of the second proportional relief valve and the third relief valve. The input current signal in the second proportional relief valve is kept constant to maintain a constant oil pressure in the second oil circuit b. The depressurized hydraulic oil flows to the first chamber A of the loading cylinder. The oil pressure in the third oil circuit c is the sum of the opening pressures of the first proportional relief valve and the second relief valve. The input current signal in the first proportional relief valve is kept constant to maintain a constant oil pressure in the second oil circuit b. The magnitude of the input current signal is adjusted to change its own opening pressure, thereby reducing the pressure of the hydraulic oil in the third oil circuit c. The depressurized hydraulic oil flows to the second chamber B of the loading cylinder. The opening pressure of the first proportional relief valve is changed to control the pressure of the second chamber B of the loading cylinder to be greater than that of the first chamber A. The loading cylinder forms a dynamic load loading force to the left. The piston rod of the actuator hydraulic cylinder extends and the thrust generated is applied to the piston rod of the loading cylinder through the hinge mechanism. At this time, the direction of the dynamic load loading force of the loading cylinder is connected to the main power direction of the actuator hydraulic cylinder of the electro-hydraulic actuator EHA under test, thus completing the simulation loading of the first negative load condition.

[0022] In the second underwater load condition, the simulation is achieved through a gear pump and a second proportional relief valve that regulates the pressure at the first chamber A of the loading cylinder. The first chamber A of the loading cylinder is the control chamber. The hydraulic pressure in the third oil circuit c is the sum of the opening pressures of the first and second proportional relief valves. The input current signal in the first proportional relief valve is kept constant to maintain a constant hydraulic pressure in the third oil circuit c. The depressurized hydraulic oil flows to the second chamber B of the loading cylinder. The hydraulic pressure in the second oil circuit b is the sum of the opening pressures of the second and third proportional relief valves. The input current signal in the second proportional relief valve is kept constant to maintain a constant hydraulic pressure in the third oil circuit c. The magnitude of the input current signal is adjusted to change its own opening pressure, thereby reducing the pressure of the hydraulic oil in the second oil circuit b. The depressurized hydraulic oil flows to the first chamber A of the loading cylinder. The opening pressure of the second proportional relief valve is changed to control the pressure of the first chamber A of the loading cylinder to be greater than that of the second chamber B. The loading cylinder forms a dynamic load loading force to the right. The piston rod of the actuator hydraulic cylinder retracts and the generated tension is applied to the piston rod of the loading cylinder through the hinge mechanism. At this time, the direction of the dynamic load loading force of the loading cylinder is the same as the direction of the main power of the actuator hydraulic cylinder of the electro-hydraulic actuator EHA under test, thus completing the simulation loading of the second negative load condition.

[0023] This invention is based on an underwater operating condition simulation test system for electro-hydraulic actuators, primarily composed of a gear pump, pressure compensator, loading valve assembly, and loading cylinder. By adjusting the opening pressure of the proportional relief valve in the loading valve assembly and the combined oil supply of the pressure compensator and gear pump, multi-condition hydraulic load simulation of electro-hydraulic actuators under underwater high-pressure environments can be achieved. This invention achieves hydraulic circuit oil compensation under underwater high-pressure environments by adjusting the oil circuit pressure of the underwater operating condition simulation test system through the pressure compensator; by controlling the active extension and retraction of the loading cylinder piston rod, four hydraulic load simulations (two positive load conditions and two negative load conditions) can be achieved; a status detection sensor monitors the system oil temperature, pressure, and loading cylinder piston rod displacement in real time. When the pressure displacement sensor reading exceeds the set displacement range or the system temperature and pressure exceed the set values, the controller shuts down the immersion motor and de-energizes the solenoid directional valve, ensuring the safety of the hydraulic system; through the series connection of the relief valve and the proportional relief valve, high-precision control of the loading cylinder control chamber pressure is achieved, thereby realizing high-precision loading force control of the loading cylinder.

[0024] The beneficial effects of this invention are:

[0025] 1. Compared with traditional land-based hydraulic load simulation methods and hydraulic systems, this invention achieves hydraulic load simulation under underwater high-pressure environment by adjusting the oil circuit pressure of the hydraulic load simulation test system through a pressure compensator.

[0026] 2. This invention simulates four working conditions—positive load, negative load, and negative load—by controlling the active extension and retraction of the piston rod of the loading cylinder, and the control chamber pressure for active extension and retraction can be adjusted by a proportional relief valve.

[0027] 3. The present invention is equipped with a status detection sensor, which can monitor the system oil temperature and pressure, and the displacement of the loading cylinder piston rod in real time. When the measured value of the pressure displacement sensor exceeds the set displacement range or the system temperature and pressure exceed the set value, the controller shuts down the oil-immersed motor and puts the electromagnetic reversing valve in a de-energized state to ensure the safety of the hydraulic system.

[0028] 4. By connecting the overflow valve and the proportional overflow valve in series, this invention can achieve high-precision control of the pressure in the control chamber of the loading cylinder, and also achieve high-precision control of the loading force of the loading cylinder. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the underwater working condition simulation test system of the present invention;

[0030] Figure 2 The figure shows the experimental results of simulating a negative load condition according to the present invention.

[0031] Figure 3 The figure shows the experimental results of simulating positive load conditions according to the present invention.

[0032] Figure 4 The figure shows the experimental results of simulating dynamic fixed-value loading of positive and negative loads according to the present invention.

[0033] Figure 5 The figure shows the experimental results of simulating dynamic alternating positive and negative loads according to the present invention.

[0034] In the diagram: 1. Oil tank; 2. First pressure compensator; 3. Pressure-resistant temperature sensor; 4. Suction filter; 5. Oil-immersed motor; 6. Gear pump; 7.1. First check valve; 7.2. Second check valve; 7.3. Third check valve; 7.4. Fourth check valve; 7.5. Fifth check valve; 8. Pressure filter; 9. First relief valve; 10.1. First pressure test connector; 10.2. Second pressure test connector; 10.3. Third pressure test connector; 11.1. First pressure sensor; 11.2. Second pressure sensor; 11.3. Third pressure sensor; 12.1. Second relief valve; 12.2. Third relief valve; 13.1. First proportional relief valve; 13.2. Second proportional relief valve; 14. Solenoid directional valve; 15. Pressure-resistant displacement sensor; 16. Loading cylinder; 17. Actuating hydraulic cylinder; 18. Second pressure compensator. Detailed Implementation

[0035] 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 and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0036] like Figure 1As shown, the underwater operating condition simulation test system for electro-hydraulic actuators of the present invention mainly includes an oil source component, a safety valve group, a loading valve group, and an actuator. The safety valve group is connected to the oil source component, and the loading valve group is connected to the oil source component, the safety valve group, and the actuator. When the underwater operating condition simulation test system is tested in a high-pressure environment underwater with a pressure higher than the preset water pressure, the oil source component provides hydraulic power, the safety valve group provides safety control, the loading valve group simulates different underwater load conditions to actively load the underwater operating condition test system, and the actuator simulates the active loading of different underwater load conditions under the adjustment of the oil source component and the loading valve group to test the electro-hydraulic actuator. The oil source assembly includes an oil tank 1, a pressure-resistant temperature sensor 3, an oil suction filter 4, an oil-immersed motor 5, and a gear pump 6. The safety valve assembly includes a first check valve 7.1, a pressure oil filter 8, a first relief valve 9, a first pressure testing connector 10.1, and a first pressure sensor 11.1. The loading valve assembly includes a second check valve 7.2, a third check valve 7.3, a fourth check valve 7.4, a fifth check valve 7.5, a second pressure testing connector 10.2, a third pressure testing connector 10.3, a second pressure sensor 11.2, a third pressure sensor 11.3, a second relief valve 12.1, a third relief valve 12.2, a first proportional relief valve 13.1, a second proportional relief valve 13.2, and a solenoid directional valve 14. The actuator includes a pressure-resistant displacement sensor 15, a loading cylinder 16, and a hinge mechanism.

[0037] The oil-immersed motor 5 of the oil source component of the underwater working condition simulation test system is connected to the gear pump 6 via a coupling. The oil suction port of the gear pump 6 is connected to the oil tank 1 via the oil suction filter 4. The pressure and temperature sensor 3 is placed inside the oil tank 1. The oil outlet of the gear pump 6 is connected to the oil inlet of the first check valve 7.1 of the safety valve group. The oil tank 1 is connected to the oil outlet of the first relief valve 9 of the safety valve group via the first oil circuit a. The oil tank 1 and the safety valve group are also threadedly connected to a first pressure compensator 2 for oil pressure compensation of the underwater working condition simulation test system under simulated underwater high pressure environment.

[0038] The inlet of the first check valve 7.1 of the safety valve group in the underwater working condition simulation test system is connected to the outlet of the gear pump 6. The inlet of the first relief valve 9 is connected to the outlet of the first check valve 7.1 via the pressure oil filter 8. The inlet of the first relief valve 9 is connected between the inlets of the second check valve 7.2 and the third check valve 7.3 of the loading valve group. The oil passage connecting the outlet of the first relief valve 9 and the oil source component is the first oil passage a. The outlet of the first relief valve 9 is connected to the oil tank 1 via the first oil passage a. The outlet of the first relief valve 9 and the outlet of the second relief valve 12.1 of the loading valve group are connected via the fourth oil passage d. The opening pressure of the first relief valve 9 must be higher than the maximum pressure limit of the system to protect the normal operation of the hydraulic system. The first pressure test connector 10.1 and the first pressure sensor 11.1 are connected to the inlet of the first relief valve 9. The first pressure compensator 2 is fixedly connected to the oil tank 1 and the safety valve group via a flange and threaded connection, thereby compensating for the oil pressure of the oil source component and the safety valve group under high pressure.

[0039] The inlet of the first relief valve 9 of the loading valve assembly of the underwater working condition simulation test system is connected to the inlet of the second check valve 7.2 and the inlet of the third check valve 7.3 via two oil lines. The outlet of the second check valve 7.2 is connected to the first chamber A of the loading cylinder 16 via the second oil line b. The oil line connecting the outlet of the second check valve 7.2 and the actuator is the second oil line b. The oil line connecting the outlet of the third check valve 7.3 and the actuator is the third oil line c. The fifth check valve 7... The oil inlet of the fifth check valve 7.5 is connected to the second oil passage b between the oil outlet of the second check valve 7.2 and the oil inlet of the solenoid directional valve 14. The oil inlet of the second proportional relief valve 13.2 is connected to the oil outlet of the fifth check valve 7.5. The oil inlet of the third relief valve 12.2 is connected to the oil outlet of the second proportional relief valve 13.2. The oil outlet of the third check valve 7.3 is connected to the second chamber B of the loading cylinder 16 via the third oil passage c. The oil inlet of the fourth check valve 7.4 is connected to the oil outlet of the third check valve 7.3. The third oil passage c, connecting the oil port and the inlet of the solenoid directional valve 14, connects the inlet of the first proportional relief valve 13.1 to the outlet of the fourth check valve 7.4, the inlet of the second relief valve 12.1 to the outlet of the first proportional relief valve 13.1, and the oil passage d connecting the outlet of the second relief valve 12.1 to the outlet of the third relief valve 12.2 to the safety valve assembly. The outlets of the second relief valve 12.1 and the third relief valve 12.2 are connected. The fourth oil circuit d is directly connected to the outlet of the first relief valve 9. The inlet and outlet of the electromagnetic directional valve 14 are connected to the second oil circuit b and the third oil circuit c, respectively. The second oil circuit b is connected to the second pressure tester 10.2 and the second pressure sensor 11.2. The third oil circuit c is connected to the third pressure tester 10.3 and the third pressure sensor 11.3. The second pressure compensator 18 is fixedly connected to the loading valve group by a flange threaded connection, thereby achieving oil pressure compensation for the loading valve group under high pressure environment.

[0040] Both the first pressure compensator 2 and the second pressure compensator 18 are diaphragm-type pressure compensators, possessing both environmental pressure compensation and dynamic pressure compensation functions. Environmental pressure compensation refers to the compensator's compensation for hydraulic oil volume changes caused by variations in environmental pressure. Dynamic pressure compensation refers to the compensator's dynamic compensation of the hydraulic system's return oil pressure under a certain environmental pressure. When the hydraulic system is placed in a high-pressure sealed chamber to simulate the high-pressure environment of the deep sea, the compensating diaphragm inside the pressure compensator undergoes a certain displacement under the action of the hydraulic system pressure and the environmental pressure until the compensating diaphragm reaches equilibrium and stops moving under the pressure of the hydraulic oil and seawater. At this point, the hydraulic oil volume compression caused by the high-pressure environment and the cavitation caused by the system's operation are compensated.

[0041] In another embodiment of the invention, the first proportional relief valve 13.1 and the second relief valve 12.1 connected in series can be replaced by a single proportional relief valve, and the second proportional relief valve 13.2 and the third relief valve 12.2 connected in series can be replaced by a single proportional relief valve.

[0042] The loading cylinder 16 of the actuator of the underwater working condition simulation test system is a symmetrical cylinder. The first chamber A of the loading cylinder 16 is connected to the oil outlet of the second check valve 7.2 of the loading valve group via the second oil passage b. The second chamber B of the loading cylinder 16 is connected to the oil outlet of the third check valve 7.3 of the loading valve group via the third oil passage c. An external pressure-resistant displacement sensor 15 is provided at the end of the piston rod on the first chamber A side of the loading cylinder 16. The piston rod on the second chamber B side is connected to the piston rod of the hydraulic cylinder 17 of the underwater electro-hydraulic actuator EHA under test through a hinge mechanism.

[0043] The underwater operating condition simulation test system and loading method of the present invention can perform active loading simulation of four operating conditions, including two positive load conditions and two negative load conditions. 1) In the first positive load condition, the piston rod of the actuator hydraulic cylinder 17 of the underwater electro-hydraulic actuator EHA under test extends, meaning the active force generated by the actuator hydraulic cylinder 17 is a thrust, and the loading cylinder 16 is required to apply a load force opposite to the direction of movement of the piston rod of the actuator hydraulic cylinder 17. 2) In the second positive load condition, the piston rod of the actuator hydraulic cylinder 17 of the underwater electro-hydraulic actuator EHA under test retracts, meaning the active force generated by the actuator hydraulic cylinder 17 is a pull force, and the loading cylinder 16 is required to apply a load force opposite to the direction of movement of the piston rod of the actuator hydraulic cylinder 17. 3) In the first negative load condition, the piston rod of the actuator hydraulic cylinder 17 of the underwater electro-hydraulic actuator EHA under test extends, meaning the active force generated by the actuator hydraulic cylinder 17 is a thrust, and the loading cylinder 16 is required to apply a load force in the same direction as the direction of movement of the piston rod of the actuator hydraulic cylinder 17. 4) Second negative load condition: The piston rod of the actuator hydraulic cylinder 17 of the underwater electro-hydraulic actuator EHA under test retracts, that is, the active force generated by the actuator hydraulic cylinder 17 is a pulling force, and the loading cylinder 16 is required to apply a load force in the same direction as the piston rod of the actuator hydraulic cylinder 17.

[0044] The loading method of the underwater working condition simulation test system in a specific implementation of this invention is as follows:

[0045] Except for the controllers of the first proportional relief valve 13.1, the second proportional relief valve 13.2, the solenoid directional valve 14, and the oil-immersed motor 5, all components of the underwater working condition simulation test system are placed inside a pressure vessel, and system pressure compensation is achieved through the first pressure compensator 2 and the second pressure compensator 18 to simulate the underwater high-pressure environment. The pressure-resistant temperature sensor 3 monitors the oil temperature in the oil tank 1 in real time. The first pressure sensor 11.1 monitors the inlet pressure of the loading valve group in real time. The second pressure sensor 11.2 monitors the pressure of the second oil circuit b and the first chamber A of the loading cylinder 16 in real time. The third pressure sensor 11.3 monitors the pressure of the third oil circuit c and the second chamber B of the loading cylinder 16 in real time. The pressure-resistant displacement sensor 15 monitors the piston rod displacement of the loading cylinder 16 in real time. When the measured value of the pressure-resistant temperature sensor 3 exceeds the set upper limit of temperature, the measured values ​​of the three pressure sensors 11.1, 11.2, and 11.3 exceed the set upper limit of pressure, and the measured value of the pressure-resistant displacement sensor 15 exceeds the set displacement range, the controller shuts down the immersion motor 5 and puts the solenoid reversing valve 14 into a de-energized state to stop the underwater working condition simulation test system from working.

[0046] By adjusting the input current signal of the solenoid directional valve 14, the connection and disconnection between the second oil circuit b and the third oil circuit c can be controlled. Increasing the input current signal energizes the solenoid directional valve 14, disconnecting the second oil circuit b and the third oil circuit c to start the underwater working condition simulation test. Decreasing the input current signal de-energizes the solenoid directional valve 14, connecting the second oil circuit b and the third oil circuit c to quickly balance the pressure in the two chambers of the loading cylinder 16, thus stopping the underwater working condition simulation test. When the underwater working condition simulation test system is working, the pressure-resistant temperature sensor 3, the three pressure sensors 11.1, 11.2, and 11.3, and the pressure-resistant displacement sensor 15 always remain operational. The preset opening pressures of the two relief valves 12.1 and 12.2 remain constant. By adjusting the opening pressures of the two proportional relief valves 13.1 and 13.2 through the controller, and by combining the oil supply of the two pressure compensators 2 and 18 with the gear pump 6, active loading of hydraulic load simulation under underwater high pressure environment can be achieved.

[0047] During testing, the opening pressure of the first relief valve 9 of the safety valve assembly is first set to be higher than the preset maximum pressure of the underwater working condition simulation test system to protect the normal operation of the hydraulic system. When the underwater working condition simulation test system is not working, the solenoid directional valve 14 is de-energized, and the second oil circuit b and the third oil circuit c are connected. When the underwater working condition simulation test system is performing testing, the immersion motor 5 and the gear pump 6 are in working condition, the solenoid directional valve 14 is energized, and the first chamber A and the second chamber B of the loading cylinder 16 are not connected. At this time, the underwater... The operating condition simulation test system is placed in a simulated underwater high-pressure environment inside a pressure vessel. The controllers for the first proportional relief valve 13.1, the second proportional relief valve 13.2, the solenoid directional valve 14, and the oil-immersed motor 5 are all located outside the pressure vessel. During testing, the second oil circuit b and the third oil circuit c of the underwater operating condition simulation test system are disconnected. The gear pump 6 draws oil from the oil tank 1 through the suction filter 4. The outlet of the gear pump 6 delivers high-pressure hydraulic oil (with a pressure exceeding a preset threshold) through the first check valve 7.1 and the pressure filter 8 to the second check valve 7.2 and the third check valve 7.3. The high-pressure hydraulic oil is then divided... The oil flows into the second oil circuit b and the third oil circuit c through the second check valve 7.2 and the third check valve 7.3. The fourth check valve 7.4 and the fifth check valve 7.5 are in the open state. By adjusting the oil source assembly, the loading valve group and the two pressure compensators 2 and 18, that is, adjusting the opening pressure of the first proportional relief valve 13.1 and the second proportional relief valve 13.2, and the oil supply of the first pressure compensator 2, the second pressure compensator 18 and the gear pump 6, the active loading of four underwater load conditions is simulated, so as to test the hydraulic cylinder 17 of the electro-hydraulic actuator EHA to be tested. The underwater load conditions include two positive load conditions and two negative load conditions. The oil temperature, pressure, and piston rod displacement of the loading cylinder 16 of the underwater load simulation test system are monitored in real time by a pressure-resistant temperature sensor 3, three pressure sensors 11.1, 11.2, and 11.3, and a pressure-resistant displacement sensor 15. If the oil temperature exceeds the preset temperature, the oil pressure exceeds the preset pressure, or the piston rod displacement of the loading cylinder 16 exceeds the preset displacement range during the test, the controller will shut down the oil-immersed motor 5 and de-energize the solenoid directional valve 14 to ensure system safety.

[0048] The specific load conditions of the underwater operating condition simulation test system are as follows:

[0049] 1) First positive load condition:

[0050] When the piston rod of the hydraulic cylinder 17 extends and acts on the piston rod of the loading cylinder 16 through the hinge mechanism, generating a pushing force, the loading cylinder 16 provides a load loading force in the opposite direction to the extension direction of the hydraulic cylinder 17. This simulates the first positive load condition. The simulation is achieved through the gear pump 6 and the second proportional relief valve 13.2, which regulates the pressure at the first chamber A of the loading cylinder 16. The first chamber A of the loading cylinder 16 is the control chamber. Specifically, the oil-immersed motor 5 operates, the gear pump 6 is in the open state, the first relief valve 9 functions as a safety valve with its opening pressure set higher than the system's preset maximum pressure, and the solenoid directional valve 14 is energized. Gear pump 6 draws oil from oil tank 1 via suction filter 4. High-pressure oil from the pump outlet flows through first check valve 7.1 and pressure filter 8 to second check valve 7.2 and third check valve 7.3. The high-pressure oil flows into second oil circuit b via second check valve 7.2 and into third oil circuit c via third check valve 7.3. At this time, first proportional relief valve 13.1, second relief valve 12.1, second proportional relief valve 13.2, and third relief valve 12.2 are all in overflow state. The oil pressure in third oil circuit c is the sum of the opening pressures of first proportional relief valve 13.1 and second relief valve 12.1. By keeping the magnitude of the input current signal in first proportional relief valve 13.1 constant, the oil pressure in third oil circuit c can be kept constant. The depressurized oil flows to the second chamber B of loading cylinder 16. The oil pressure in the second oil circuit b is the sum of the opening pressures of the second proportional relief valve 13.2 and the third relief valve 12.2. The opening pressure of the second proportional relief valve 13.2 can be adjusted by regulating the input current signal, thereby regulating the oil pressure in the second oil circuit b. The depressurized oil flows to the first chamber A of the loading cylinder 16. By changing the opening pressure of the second proportional relief valve 13.2, the pressure in the first chamber A is controlled to be greater than that in the second chamber B, causing the loading cylinder 16 to generate a dynamic load force to the right, thus achieving dynamic loading of the loading cylinder 16. It should be noted that if the pressure difference between chambers A and B is greater than the main power of the actuating hydraulic cylinder 17, the piston of the loading cylinder 16 moves to the right, forcing the actuating hydraulic cylinder 17 to retract; if the pressure difference between chambers A and B is less than the main power of the actuating hydraulic cylinder 17, the piston of the loading cylinder 16 is forced to move to the left. In this case, to prevent cavitation in the second chamber B, the gear pump 6 replenishes oil to the second chamber B of the loading cylinder 16 through the third oil circuit c.

[0051] 2) Second positive load condition:

[0052] When the piston rod of the hydraulic cylinder 17 retracts, it acts on the piston rod of the loading cylinder 16 through the hinge mechanism, forming a pulling force on it. The loading cylinder 16 provides a load loading force in the opposite direction to the extension direction of the hydraulic cylinder 17. At this time, a second positive load condition can be simulated. The simulation is completed by the gear pump 6 and the first proportional relief valve 13.1, which adjusts the pressure of the second chamber B of the loading cylinder 16. The second chamber B of the loading cylinder 16 is the control chamber. Specifically, the oil-immersed motor 5 is working, the gear pump 6 is in the open state, the first relief valve 9 is used as a safety valve, and its opening pressure is set to be higher than the preset maximum pressure of the system. The solenoid directional valve 14 is in the energized state. Gear pump 6 draws oil from oil tank 1 via suction filter 4. High-pressure oil from the pump outlet flows through first check valve 7.1 and pressure filter 8 to second check valve 7.2 and third check valve 7.3. The high-pressure oil flows into second oil circuit b via second check valve 7.2 and into third oil circuit c via third check valve 7.3. At this time, first proportional relief valve 13.1, second relief valve 12.1, second proportional relief valve 13.2, and third relief valve 12.2 are all in overflow state. The oil pressure in second oil circuit b is the sum of the opening pressures of second proportional relief valve 13.2 and third relief valve 12.2. By keeping the magnitude of the input current signal in second proportional relief valve 13.2 constant, the oil pressure in second oil circuit b can be kept constant. The depressurized oil flows to the first chamber A of loading cylinder 16. The oil pressure in the third oil circuit c is the sum of the opening pressures of the first proportional relief valve 13.1 and the second relief valve 12.1. The opening pressure of the first proportional relief valve 13.1 can be adjusted by regulating the magnitude of the input current signal, thereby regulating the oil pressure in the third oil circuit c. The depressurized oil flows to the second chamber B of the loading cylinder 16. By changing the opening pressure of the first proportional relief valve 13.1, the pressure in the second chamber B is controlled to be greater than that in the first chamber A, causing the loading cylinder 16 to generate a dynamic load force to the left, thus achieving dynamic loading of the loading cylinder 16. It should be noted that if the pressure difference between chambers A and B is greater than the main power of the actuating hydraulic cylinder 17, the piston of the loading cylinder 16 moves to the left, forcing the actuating hydraulic cylinder 17 to extend; if the pressure difference between chambers A and B is less than the main power of the actuating hydraulic cylinder 17, the piston of the loading cylinder 16 is forced to move to the right. In this case, to prevent cavitation in the first chamber A, the gear pump 6 replenishes oil to the first chamber A of the loading cylinder 16 through the second oil circuit b.

[0053] 3) First negative load condition:

[0054] When the piston rod of the hydraulic cylinder 17 extends and acts on the piston rod of the loading cylinder 16 through the hinge mechanism, generating a pushing force, the loading cylinder 16 provides a load loading force in the same direction as the extension direction of the hydraulic cylinder 17. This simulates the first negative load condition. The simulation is achieved through the gear pump 6 and the first proportional relief valve 13.1, which regulates the pressure at the second chamber B of the loading cylinder 16. The second chamber B of the loading cylinder 16 is the control chamber. Specifically, the oil-immersed motor 5 operates, the gear pump 6 is in the open state, the first relief valve 9 functions as a safety valve with its opening pressure set higher than the system's preset maximum pressure, and the solenoid directional valve 14 is energized. Gear pump 6 draws oil from oil tank 1 via suction filter 4. High-pressure oil from the pump outlet flows through first check valve 7.1 and pressure filter 8 to second check valve 7.2 and third check valve 7.3. The high-pressure oil flows into second oil circuit b via second check valve 7.2 and into third oil circuit c via third check valve 7.3. At this time, first proportional relief valve 13.1, second relief valve 12.1, second proportional relief valve 13.2, and third relief valve 12.2 are all in overflow state. The oil pressure in second oil circuit b is the sum of the opening pressures of second proportional relief valve 13.2 and third relief valve 12.2. By keeping the magnitude of the input current signal in second proportional relief valve 13.2 constant, the oil pressure in second oil circuit b can be kept constant. The depressurized oil flows to the first chamber A of loading cylinder 16. The oil pressure in the third oil circuit c is the sum of the opening pressures of the first proportional relief valve 13.1 and the second relief valve 12.1. The opening pressure of the first proportional relief valve 13.1 can be adjusted by regulating the magnitude of the input current signal, thereby regulating the oil pressure in the third oil circuit c. The depressurized oil flows to the second chamber B of the loading cylinder 16. By changing the opening pressure of the first proportional relief valve 13.1, the pressure in the second chamber B is controlled to be greater than that in the first chamber A, causing the loading cylinder 16 to generate a dynamic load-bearing force to the left, thus achieving dynamic loading of the loading cylinder 16. It should be noted that because the direction of the active force generated by the hydraulic cylinder 17 is consistent with the direction of the load-bearing force provided by the loading cylinder 16, the piston of the loading cylinder 16 will move rapidly to the left. To prevent the loading cylinder 16 from sucking in cavitation at the second chamber B due to the rapid piston movement, the gear pump 6 replenishes oil to the second chamber B of the loading cylinder 16 through the third oil circuit c.

[0055] 4) Second negative load condition:

[0056] When the piston rod of the hydraulic cylinder 17 retracts, it acts on the piston rod of the loading cylinder 16 through the hinge mechanism, forming a tensile force. The loading cylinder 16 then provides a load loading force in the same direction as the extension of the hydraulic cylinder 17. This simulates a second negative load condition. The simulation is achieved through the gear pump 6 and the second proportional relief valve 13.2, which regulates the pressure at the first chamber A of the loading cylinder 16. The first chamber A of the loading cylinder 16 is the control chamber. Specifically, the oil-immersed motor 5 operates, the gear pump 6 is in the open state, the first relief valve 9 functions as a safety valve with its opening pressure set higher than the system's preset maximum pressure, and the solenoid directional valve 14 is energized. Gear pump 6 draws oil from oil tank 1 via suction filter 4. High-pressure oil from the pump outlet flows through first check valve 7.1 and pressure filter 8 to second check valve 7.2 and third check valve 7.3. The high-pressure oil flows into second oil circuit b via second check valve 7.2 and into third oil circuit c via third check valve 7.3. At this time, first proportional relief valve 13.1, second relief valve 12.1, second proportional relief valve 13.2, and third relief valve 12.2 are all in overflow state. The oil pressure in third oil circuit c is the sum of the opening pressures of first proportional relief valve 13.1 and second relief valve 12.1. By keeping the magnitude of the input current signal in first proportional relief valve 13.1 constant, the oil pressure in third oil circuit c can be kept constant. The depressurized oil flows to the second chamber B of loading cylinder 16. The oil pressure in the second oil circuit b is the sum of the opening pressures of the second proportional relief valve 13.2 and the third relief valve 12.2. The opening pressure of the second proportional relief valve 13.2 can be adjusted by regulating the input current signal, thereby regulating the oil pressure in the second oil circuit b. The depressurized oil flows to the first chamber A of the loading cylinder 16. By changing the opening pressure of the second proportional relief valve 13.2, the pressure in the first chamber A is controlled to be greater than that in the second chamber B, causing the loading cylinder 16 to generate a dynamic load-bearing force to the right, thus achieving dynamic loading of the loading cylinder 16. It should be noted that because the direction of the active force generated by the hydraulic cylinder 17 is consistent with the direction of the load-bearing force provided by the loading cylinder 16, the piston of the loading cylinder 16 will move rapidly to the right. To prevent cavitation in the first chamber A due to the rapid piston movement, the gear pump 6 replenishes oil to the first chamber A of the loading cylinder 16 through the second oil circuit b.

[0057] In its specific implementation, this invention utilizes a pressure vessel to simulate a deep-sea environment, applying dynamic loads to the underwater electro-hydraulic actuator (EHA) under test, similar to conditions on land. The internal environment of the pressure vessel is set to simulate a deep-sea environment at a depth of 3000 meters, with a pressure of 30 MPa and a temperature of 4°C. Figure 2 and Figure 3As shown, the underwater electro-hydraulic actuator EHA under test executes a preset trajectory with a preset displacement of 0~150mm. The loading cylinder 16 can apply dynamically changing negative and positive load forces to the actuator 17. The negative load range is -3000N~0N, and the positive load range is 0N~3000N. Figure 4 As shown, the underwater electro-hydraulic actuator EHA under test executes a preset trajectory with a preset displacement of 0~150mm. The loading cylinder 16 can simulate fixed positive and negative load conditions for the actuator 17, with a positive load of 600N and a negative load of -600N, and can quickly switch between positive and negative load conditions, with a switching time of approximately 1.5 seconds. Figure 5 As shown, the hydraulic cylinder 17 of the underwater electro-hydraulic actuator EHA under test executes a preset trajectory with a preset displacement of 0~150mm. The loading cylinder 16 can simulate alternating positive and negative load conditions on the hydraulic cylinder 17, with an alternating frequency of 0.1Hz, a positive load peak value of 2000N, and a negative load peak value of -2000N. Therefore, this invention can simulate the underwater operating conditions of the underwater electro-hydraulic actuator EHA on land, and by applying dynamic loads to the underwater electro-hydraulic actuator EHA under test, the underwater working performance of the underwater electro-hydraulic actuator EHA can be verified.

[0058] In achieving high-precision loading force control, this invention utilizes a first proportional relief valve 13.1 and a second relief valve 12.1 connected in series, then connected to a third oil circuit c via a fourth check valve, to control the pressure at the second chamber B of the loading cylinder 16. Similarly, a second proportional relief valve 13.2 and a third relief valve 12.2 connected in series, then connected to a second oil circuit b via a fifth check valve, to control the pressure at the first chamber A of the loading cylinder 16. The second and third relief valves 12.1 and 12.2 provide wide-range opening pressure adjustment for low-precision system pressure regulation, while the first and second proportional relief valves 13.1 and 13.2 provide narrow-range opening pressure adjustment. Online high-precision system pressure regulation is achieved by controlling the input current signal. Furthermore, through high-precision system pressure regulation, high-precision loading force control of the loading cylinder 16 is realized.

[0059] The above is merely one embodiment of the present invention and should not be construed as limiting the present invention. Therefore, equivalent changes made within the scope of the present invention are still within the protection scope of the present invention.

Claims

1. A loading method for an underwater operating condition simulation test system for an electro-hydraulic actuator, the underwater operating condition simulation test system comprising a hydraulic power supply component, a safety valve group, a loading valve group, and an actuator; the hydraulic power supply component is used for supplying hydraulic power to the underwater operating condition simulation test system during testing in an underwater environment; the safety valve group is connected to the hydraulic power supply component and is used for safety control of the underwater operating condition test system during testing in an underwater environment; the loading valve group is connected to the hydraulic power supply component and the safety valve group and is used to simulate different underwater load conditions in an underwater environment for active loading of the underwater operating condition test system; the actuator is connected to the loading valve group and is used to simulate different underwater operating conditions under the adjustment of the hydraulic power supply component and the loading valve group in an underwater environment. Active loading under underwater load conditions is used to test the electro-hydraulic actuator; the first proportional relief valve (13.1) and the second relief valve (12.1) of the loading valve group are connected in series, and the second proportional relief valve (13.2) and the third relief valve (12.2) are connected in series. A second pressure compensator (18) for oil pressure compensation of the underwater working condition simulation test system under simulated underwater environment is threaded onto the loading valve group; the oil tank (1) of the oil source component and the safety valve group are threaded onto the first pressure compensator (2) for oil pressure compensation of the underwater working condition simulation test system under simulated underwater environment; the loading cylinder (16) of the actuator is a symmetrical cylinder, characterized in that, The underwater working condition simulation test system first sets the opening pressure of the first relief valve (9) of the safety valve group to be higher than the preset maximum pressure of the underwater working condition simulation test system; when the underwater working condition simulation test system is not working, the electromagnetic reversing valve (14) is in a de-energized state, and the second oil circuit b and the third oil circuit c are connected; when the underwater working condition simulation test system is performing test work, the immersion motor (5) and the gear pump (6) are in a working state, the electromagnetic reversing valve (14) is in an energized state, and the first chamber port A and the second chamber port B of the loading cylinder (16) are not connected; at this time, the underwater working condition simulation test system is placed in a simulated underwater environment in a pressure vessel, wherein the first proportional relief valve (13.1) and the second proportional relief valve (13.2) are connected. The controllers of the electromagnetic reversing valve (14) and the oil-immersed motor (5) are all located outside the pressure vessel. During the test, the second oil circuit b and the third oil circuit c of the underwater working condition simulation test system are disconnected. The gear pump (6) draws oil from the oil tank (1) through the suction filter (4). The outlet of the gear pump (6) carries high-pressure hydraulic oil with a pressure higher than the preset threshold through the first check valve (7.1) and the pressure filter (8) to the second check valve (7.2) and the third check valve (7.3). The high-pressure hydraulic oil flows into the second oil circuit b and the third oil circuit c through the second check valve (7.2) and the third check valve (7.3) respectively. By adjusting the oil source component, the loading valve group and the two pressure compensators (2, 18), the active loading of four underwater load conditions is simulated, thereby The hydraulic cylinder (17) of the electro-hydraulic actuator EHA under test was tested. Four underwater load conditions were tested, including two positive load conditions and two negative load conditions. The oil temperature, pressure and piston rod displacement of the loading cylinder (16) of the underwater working condition simulation test system were monitored in real time by a pressure-resistant temperature sensor (3), three pressure sensors (11.1, 11.2, 11.3) and a pressure-resistant displacement sensor (15). When the oil temperature exceeds the preset temperature, the oil pressure exceeds the preset pressure, or the piston rod displacement of the loading cylinder (16) exceeds the preset displacement range, the controller shuts off the immersion motor (5) and puts the solenoid directional valve (14) in a de-energized state. The first pressure sensor (11.1) monitors the loading in real time. The inlet pressure of the loading valve group, the second pressure sensor (11.2) monitors the pressure of the first chamber A of the loading cylinder (16) in real time, and the third pressure sensor (11.3) monitors the pressure of the second chamber B of the loading cylinder (16) in real time; the preset opening pressure of the two relief valves (12.1, 12.2) remains unchanged, and the opening pressure of the two proportional relief valves (13.1, 13.2) is dynamically adjusted by the controller. The loading cylinder (16) simulates alternating positive and negative load conditions for the hydraulic cylinder (17). The second relief valve (12.1) and the third relief valve (12.2) achieve a wide range of opening pressure adjustment, and complete the low-precision adjustment of the system pressure. The first proportional relief valve (13.1) and the second proportional relief valve (13.2) are also adjusted.2) Achieve small-range opening pressure regulation by controlling the input current signal to complete online high-precision regulation of the system pressure, thereby realizing high-precision loading force control of the loading cylinder (16).

2. The loading method of the underwater operating condition simulation test system for electro-hydraulic actuators according to claim 1, characterized in that: In the first positive load condition of the underwater load operation, the first chamber A of the loading cylinder (16) is the control chamber, and the oil pressure in the third oil circuit c is the sum of the opening pressures of the first proportional relief valve (13.1) and the second relief valve (12.1). The magnitude of the input current signal in the first proportional relief valve (13.1) is kept constant, and the depressurized hydraulic oil flows to the second chamber B of the loading cylinder (16). The oil pressure in the second oil circuit b is the sum of the opening pressures of the second proportional relief valve (13.2) and the third relief valve (12.2). The magnitude of the input current signal in the second proportional relief valve (13.2) is controlled to adjust its own opening pressure. This reduces the pressure of the hydraulic oil in the second oil circuit b, and the depressurized hydraulic oil flows to the first chamber A of the loading cylinder (16); the opening pressure of the second proportional relief valve (13.2) is changed to control the pressure of the first chamber A of the loading cylinder (16) to be greater than that of the second chamber B, and the loading cylinder (16) forms a dynamic load loading force. The piston rod of the actuator hydraulic cylinder (17) extends and the generated thrust is applied to the piston rod of the loading cylinder (16) through the hinge mechanism. At this time, the direction of the dynamic load loading force of the loading cylinder (16) is opposite to the direction of the main power of the actuator hydraulic cylinder (17) of the electro-hydraulic actuator EHA under test, and the simulation loading of the first positive load condition is completed.

3. The loading method of the underwater operating condition simulation test system for electro-hydraulic actuators according to claim 1, characterized in that: In the second positive load condition of the underwater load operation, the second chamber B of the loading cylinder (16) is the control chamber. The oil pressure in the second oil circuit b is the sum of the opening pressures of the second proportional relief valve (13.2) and the third relief valve (12.2). The magnitude of the input current signal in the second proportional relief valve (13.2) is kept constant, and the depressurized hydraulic oil flows to the first chamber A of the loading cylinder (16). The oil pressure in the third oil circuit c is the sum of the opening pressures of the first proportional relief valve (13.1) and the second relief valve (12.2). The magnitude of the input current signal in the first proportional relief valve (13.1) is controlled to adjust its own opening pressure. This reduces the pressure of the hydraulic oil in the third oil circuit c, and the depressurized hydraulic oil flows to the second chamber B of the loading cylinder (16); the opening pressure of the first proportional relief valve (13.1) is changed to control the pressure of the second chamber B of the loading cylinder (16) to be greater than that of the first chamber A. The loading cylinder (16) forms a dynamic load loading force, the piston rod of the actuator hydraulic cylinder (17) retracts and the generated tension is applied to the piston rod of the loading cylinder (16) through the hinge mechanism. At this time, the direction of the dynamic load loading force of the loading cylinder (16) is opposite to the direction of the main power of the actuator hydraulic cylinder (17) of the electro-hydraulic actuator EHA under test, and the simulation loading of the second positive load condition is completed.

4. The loading method of the underwater operating condition simulation test system for electro-hydraulic actuators according to claim 1, characterized in that: In the first underwater load condition, the second chamber B of the loading cylinder (16) is the control chamber. The oil pressure in the second oil circuit b is the sum of the opening pressures of the second proportional relief valve (13.2) and the third relief valve (12.2). The magnitude of the input current signal in the second proportional relief valve (13.2) is kept constant, and the depressurized hydraulic oil flows to the first chamber A of the loading cylinder (16). The oil pressure in the third oil circuit c is the sum of the opening pressures of the first proportional relief valve (13.1) and the second relief valve (12.2). The magnitude of the input current signal in the first proportional relief valve (13.1) is controlled to adjust its own opening pressure. This reduces the pressure of the hydraulic oil in the third oil circuit c, and the depressurized hydraulic oil flows to the second chamber B of the loading cylinder (16); the opening pressure of the first proportional relief valve (13.1) is changed to control the pressure of the second chamber B of the loading cylinder (16) to be greater than that of the first chamber A, and the loading cylinder (16) forms a dynamic load loading force. The piston rod of the actuator hydraulic cylinder (17) extends and the generated thrust is applied to the piston rod of the loading cylinder (16) through the hinge mechanism. At this time, the direction of the dynamic load loading force of the loading cylinder (16) is connected to the main power direction of the actuator hydraulic cylinder (17) of the electro-hydraulic actuator EHA to be tested, and the simulation loading of the first negative load condition is completed.

5. The loading method of the underwater operating condition simulation test system for electro-hydraulic actuators according to claim 1, characterized in that: In the second underwater load condition, the first chamber A of the loading cylinder (16) is the control chamber. The oil pressure in the third oil circuit c is the sum of the opening pressures of the first proportional relief valve (13.1) and the second relief valve (12.1). The magnitude of the input current signal in the first proportional relief valve (13.1) remains unchanged, and the depressurized hydraulic oil flows to the second chamber B of the loading cylinder (16). The oil pressure in the second oil circuit b is the sum of the opening pressures of the second proportional relief valve (13.2) and the third relief valve (12.2). The magnitude of the input current signal in the second proportional relief valve (13.2) is controlled to adjust its own opening pressure. This reduces the pressure of the hydraulic oil in the second oil circuit b, and the depressurized hydraulic oil flows to the first chamber A of the loading cylinder (16); the opening pressure of the second proportional relief valve (13.2) is changed to control the pressure of the first chamber A of the loading cylinder (16) to be greater than that of the second chamber B, and the loading cylinder (16) forms a dynamic load loading force. The piston rod of the actuator hydraulic cylinder (17) retracts and the generated tension is applied to the piston rod of the loading cylinder (16) through the hinge mechanism. At this time, the direction of the dynamic load loading force of the loading cylinder (16) is the same as the direction of the main power of the actuator hydraulic cylinder (17) of the electro-hydraulic actuator EHA under test, and the simulation loading of the second negative load condition is completed.

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