A hydraulic valve high and low temperature durability test system and method

Abstract

The present application belongs to the field of aircraft hydraulic system, and relates to a high and low temperature durability test method and system for hydraulic valves, comprising a high / low temperature box, a hydraulic test loop, a controller and a general hydraulic oil source. The general hydraulic source and the environmental box are used, and as long as a suitable electromagnetic reversing valve, a hydraulic actuator cylinder and a controller are configured and a proper control logic is set, the high and low temperature durability test of various hydraulic valves can be applied, and a special high (low) temperature hydraulic source does not need to be constructed, and the energy consumption and cost of the durability test are greatly reduced.

Description

Technical Field

[0001] This invention belongs to the field of aircraft hydraulic systems and relates to a method and system for high and low temperature durability testing of hydraulic valves. Specifically, it relates to the principle, system configuration, and detection control of a method for high and low temperature durability testing of hydraulic valves. Background Technology

[0002] Hydraulic valve durability testing is a crucial qualification test for hydraulic products. Aircraft operating environments encompass ambient, high, and low temperatures. Hydraulic valves installed on aircraft inevitably endure various temperature conditions. Thermal expansion and contraction of hydraulic safety valve components cause changes in the clearances between parts, and the viscosity of the working fluid also changes with temperature, affecting the valve's opening characteristics. To verify the performance and adaptability of hydraulic valves throughout the aircraft's entire lifespan and across all temperature environments, durability testing is typically divided into three temperature ranges: high temperature, ambient temperature, and low temperature. The number of hydraulic valve durability tests usually exceeds 200,000 cycles. Generally, ambient temperature durability tests account for a higher proportion (65%), high temperature tests a smaller proportion (25%), and low temperature tests a smaller proportion (at least 10%). Although the high and low temperature tests account for a relatively smaller proportion compared to ambient temperature tests, they are more challenging to implement, requiring heating (cooling) the test fluid to the specified high (low) temperature and maintaining high (low) temperature stability throughout the entire test.

[0003] Currently, research and development units construct high- and low-temperature hydraulic test benches to conduct high- and low-temperature durability tests on hydraulic products. Constructing such benches requires hydraulic components such as high- and low-temperature resistant hydraulic pumps and solenoid directional valves, which is technically challenging and costly. High- and low-temperature hydraulic test benches use heating (cooling) of the return oil line to raise (lower) the temperature of the test system's oil. However, the significant heat exchange between the high- and low-temperature hydraulic test bench and the test environment severely affects the oil temperature stability, requiring heating (cooling) equipment to continuously provide energy to compensate for the test oil temperature, consuming a large amount of electrical energy. Especially for low-temperature hydraulic durability test benches, the frictional heat generated during hydraulic pump operation and the throttling heat generated in the hydraulic circuit (including components and pipelines) cause the low-temperature oil (generally below -40℃) to easily heat up, making it difficult to maintain the stable low-temperature range required for the test. Russian military industrial enterprises have built specialized cold storage facilities in their laboratories. Placing the test benches in the low-temperature environment of the cold storage reduces the heat absorption of the test system from the external environment and also reduces the impact of heat generation by the hydraulic test benches themselves. The cost of building infrastructure and test equipment for implementing low-temperature durability tests of hydraulic products is staggering.

[0004] In summary, constructing a dedicated high and low temperature durability test bench requires high-performance hydraulic power source components such as high- and low-temperature resistant hydraulic pumps, solenoid directional valves, and relief valves. It may even necessitate the construction of a dedicated low-temperature laboratory, presenting significant technical challenges and requiring substantial financial investment. Furthermore, the high and low temperature hydraulic test bench consumes a significant amount of electrical energy to maintain the stable temperature of the test oil during testing. This includes: firstly, the electrical energy required to raise the temperature of the test bench and test medium to 135℃ (or cool it down to -45℃ to -55℃); and secondly, the heat generated by the hydraulic system during operation, causing the medium temperature to rise, necessitating a continuous supply of electrical energy to maintain the test medium at the temperature required for high and low temperature durability testing.

[0005] Therefore, a high and low temperature durability test method and system for hydraulic valves is needed. This method and system do not require the construction of a dedicated high and low temperature durability test bench and low temperature laboratory. It only needs to provide the high (low) temperature environment provided by the high or (and) low temperature environmental chamber as the heat source (cold source) for the test hydraulic circuit. This method and system only need to heat (cool) a portion of the test oil (rather than the oil of the entire test bench) to reduce the energy consumption for establishing the initial temperature of the test oil. At the same time, placing part of the oil circuit of the test system in a stable high (low) temperature environment reduces the heat exchange between the test system and the external environment during the test, thereby reducing the energy consumed to maintain temperature stability. This method and system place the test hydraulic circuit in the environmental chamber and requires the installation of remote control components such as electromagnetic directional valves, hydraulic bridge circuits for oil circuit isolation and alternating connection, and controllers to realize the opening / closing cycle control of the tested hydraulic valve. Summary of the Invention

[0006] The purpose of this invention is to solve the technical difficulties, testing costs, and energy consumption problems in constructing high (low) temperature hydraulic test benches, and to propose a method and system for high (low) temperature durability testing of hydraulic valves, which consists of a hydraulic actuator, an electromagnetic directional valve, a load regulating valve, a controller, and a high or (and) low temperature environment chamber.

[0007] This invention is achieved through the following technical solution:

[0008] A high / low temperature durability testing system for hydraulic valves includes a high / low temperature chamber, a test hydraulic circuit, a controller, a data logger, and a universal hydraulic oil source. The test hydraulic circuit includes a first hydraulic actuator, a second hydraulic actuator, a solenoid directional valve, a temperature sensor, a pressure sensor, a flow meter, a load regulating valve, and the valve under test. The universal hydraulic oil source is connected to the return port R and the pressure port P of the solenoid directional valve. The first load port C1 of the solenoid directional valve is connected to the left chamber of the first hydraulic actuator and the left chamber of the second hydraulic actuator, respectively. The second load port C2 of the solenoid directional valve is connected to the right chamber of the first hydraulic actuator and the right chamber of the second hydraulic actuator, respectively. The right chamber of the cylinder is connected; the load regulating valve is connected to the flow meter, and the flow meter is connected to the load port C of the valve under test; the right chamber of the first hydraulic actuator cylinder is connected to the second load port C2 of the electromagnetic directional valve; the temperature sensor and pressure sensor are set on the connecting pipeline between the left chamber of the first hydraulic actuator cylinder, the right chamber of the second hydraulic actuator cylinder and the high pressure port P1 of the valve under test, and are close to the high pressure port P1 of the valve under test; the controller is connected to the temperature sensor, pressure sensor, flow meter, electromagnetic directional valve and valve under test respectively through cables; the first hydraulic actuator cylinder, the second hydraulic actuator cylinder, the temperature sensor, the pressure sensor, the flow meter and the valve under test are all set in the high / low temperature chamber.

[0009] Furthermore, it also includes a first check valve, a second check valve, a third check valve, and a fourth check valve. The first check valve is located on the pipeline between the left chamber of the first hydraulic actuator and the load regulating valve; the second check valve is located on the pipeline between the right chamber of the second hydraulic actuator and the load regulating valve; the third check valve is located on the pipeline between the right chamber of the second hydraulic actuator and the high-pressure port P1 of the valve under test; and the fourth check valve is connected at one end to the third check valve and at the other end to the left chamber of the first actuator.

[0010] Furthermore, it also includes a first shut-off valve and a second shut-off valve. The first shut-off valve is installed on the connecting pipeline between the fourth check valve and the first load port C1 of the solenoid directional valve; the second shut-off valve is installed on the connecting pipeline between the second load port C2 of the solenoid directional valve and the right chamber of the second hydraulic actuator.

[0011] Furthermore, it also includes a data logger, which is connected to the controller, temperature sensor, pressure sensor, and flow meter.

[0012] Furthermore, the first check valve, the second check valve, the third check valve, and the fourth check valve are all installed inside the high / low temperature chamber.

[0013] Methods for high and low temperature durability testing systems for hydraulic valves, including high temperature durability testing methods, low temperature durability testing methods, and oil replenishment methods.

[0014] Furthermore, the high-temperature durability test method includes the following steps:

[0015] Step 1: Install and connect the hydraulic test circuit. Connect the temperature sensor, pressure sensor, flow meter, and controller. Then connect the temperature sensor, pressure sensor, flow meter, and controller to the data logger. The first and second shut-off valves are both in the closed state.

[0016] Step 2: Start the general hydraulic oil source, with the controller in manual mode. Open the first shut-off valve and alternately control the solenoid directional valve to the left and right positions 3-5 times. The left chamber of the hydraulic actuator cylinder will be filled with oil. Turn off the power supply to the solenoid directional valve and shut off the first shut-off valve. Open the second shut-off valve and alternately control the solenoid directional valve to the right and left positions 3-5 times. The left chamber of the hydraulic actuator cylinder will be filled with oil. Turn off the power supply to the valve under test and shut off the second shut-off valve.

[0017] Step 3: Set the target temperature of the high / low temperature chamber according to the high temperature test requirements, start the high / low temperature chamber, and after the ambient temperature inside the chamber stabilizes, continue to observe the inlet temperature of the valve under test through the temperature sensor and data logger until the inlet temperature of the valve under test reaches the specified test temperature.

[0018] When the controller is in automatic mode, the controller controls the high-pressure port P of the solenoid directional valve to connect with the right chamber of the first hydraulic actuator through the second load port C2, and the left chamber of the first hydraulic actuator forms high pressure.

[0019] The controller controls the valve under test to open, and the oil flows through the load port C of the valve under test, through the flow meter, the load regulating valve, and the second check valve to the right chamber of the second hydraulic actuator.

[0020] The controller controls the closed valve under test and controls the switching valve to switch directions.

[0021] The controller controls the high-pressure port P of the electromagnetic reversing valve to connect with the left chamber of the second hydraulic actuator through the first load port C1, and the right chamber of the second hydraulic actuator is under high pressure.

[0022] The controller controls the valve under test to open, and the oil flows through the load port C of the valve under test, through the flow meter, the load regulating valve, and the first check valve to the left chamber of the first hydraulic actuator.

[0023] The controller closes the valve under test, completing two high-temperature durability tests on the valve under test.

[0024] Repeat the above process until all the high-temperature durability tests on the valve under test have been completed.

[0025] Furthermore, the low-temperature durability test method includes the following steps:

[0026] Step 1: Install and connect the hydraulic test circuit. Connect the temperature sensor, pressure sensor, flow meter, and controller. Then connect the temperature sensor, pressure sensor, flow meter, and controller to the data logger. The first and second shut-off valves are both in the closed state.

[0027] Step 2: Start the general hydraulic oil source, with the controller in manual mode. Open the first shut-off valve and alternately control the solenoid directional valve to the left and right positions 3-5 times. The left chamber of the hydraulic actuator cylinder will be filled with oil. Turn off the power supply to the solenoid directional valve and shut off the first shut-off valve. Open the second shut-off valve and alternately control the solenoid directional valve to the right and left positions 3-5 times. The left chamber of the hydraulic actuator cylinder will be filled with oil. Turn off the power supply to the valve under test and shut off the second shut-off valve.

[0028] Step 3: Set the target temperature of the high / low temperature chamber according to the low temperature test requirements, start the high / low temperature chamber, and after the ambient temperature inside the chamber stabilizes, continue to observe the inlet temperature of the valve under test through the temperature sensor and data logger until the inlet temperature of the valve under test reaches the specified test temperature.

[0029] The controller is in automatic mode; the controller controls the high-pressure port P of the solenoid directional valve to connect with the right chamber of the first hydraulic actuator 1 through the second load port C2, and the left chamber of the first hydraulic actuator 1 is under high pressure.

[0030] The controller controls the valve under test to open, and the oil flows through the load port C of the valve under test, through the flow meter, the load regulating valve, and the second check valve to the right chamber of the second hydraulic actuator.

[0031] The controller controls the closed valve under test and controls the switching valve to switch directions.

[0032] At this time, the high-pressure port P of the electromagnetic reversing valve is connected to the left chamber of the second hydraulic actuator through the first load port C1, and the right chamber of the second hydraulic actuator is under high pressure.

[0033] The controller controls the valve under test to open, and the oil flows through the load port C of the valve under test, through the flow meter, the load regulating valve, and the first check valve to the left chamber of the first hydraulic actuator 1.

[0034] The controller closes the valve under test, completing two low-temperature durability tests on the valve under test.

[0035] Repeat the above process until all the low-temperature durability tests on the valve under test have been completed.

[0036] Furthermore, the oil replenishment method includes the following steps:

[0037] Step 1: Start the general hydraulic oil source, set the controller to manual mode, and both the first and second shut-off valves are in the closed state.

[0038] Step 2: Open the first shut-off valve, and the controller alternately controls the left and right positions 3 to 5 times. The left chamber of the first hydraulic actuator is filled with oil. Turn off the power supply to the solenoid directional valve and shut off the first shut-off valve. Open the second shut-off valve, and the controller alternately controls the right and left positions 3 to 5 times. The left chamber of the second hydraulic actuator is filled with oil. Turn off the power supply to the solenoid directional valve and shut off the second shut-off valve.

[0039] Compared with previous technologies, the present invention has the following beneficial effects:

[0040] (1) This invention utilizes the high / low temperature environment provided by the high / low temperature chamber to provide a heat source (cold source) for the oil in the test hydraulic circuit placed in the chamber to realize the high and low temperature durability test of the hydraulic valve. There is no need to build a special high and low temperature test bench and low temperature laboratory, which reduces a lot of fixed asset investment and has good economic benefits.

[0041] (2) The present invention places the test hydraulic circuit in a high / low temperature chamber. The oil in the test hydraulic circuit circulates in the high / low temperature environment and basically does not exchange energy with the outside. The energy loss is small and the oil temperature in the test circuit is stable, which reduces the energy consumption during the test process, reduces the test cost, and has good economic benefits.

[0042] (3) This invention utilizes general hydraulic oil sources and general equipment such as high / low temperature chambers. The test hydraulic circuit can be designed and modified according to the specific characteristics of the hydraulic valve. It can quickly carry out tests using general resources and is applicable to a variety of hydraulic valves. It has good applicability and economy. Attached Figure Description

[0043] Figure 1 This is a high and low temperature durability test method and system schematic diagram for hydraulic valves;

[0044] Among them, 1-first hydraulic actuator, 2-second hydraulic actuator, 3-electromagnetic directional valve, 4-first check valve, 5-second check valve, 6-third check valve, 7-fourth check valve, 8-temperature sensor, 9-pressure sensor, 10-flow meter, 11-load regulating valve, 12-first shut-off valve, 13-second shut-off valve. Detailed Implementation

[0045] This section describes embodiments of the present invention, used to explain and illustrate the technical solutions of the present invention.

[0046] A method and system for high and low temperature durability testing of hydraulic valves includes a general-purpose hydraulic oil source, a high / low temperature chamber, and a test hydraulic circuit. The general-purpose hydraulic oil source is a hydraulic power source that drives the actuator in the test hydraulic circuit to generate high-pressure fluid to provide hydraulic power to the valve under test. The high / low temperature chamber has sufficient space to install the hydraulic components and pipelines of the test hydraulic circuit and provides a heat source (cold source) for the oil in the test hydraulic circuit. The test hydraulic circuit consists of hydraulic components such as a first hydraulic actuator 1, a second hydraulic actuator 2, a solenoid directional valve 3, a load regulating valve 11, a first check valve 4, a second check valve 5, a third check valve 6, a fourth check valve 7, a temperature sensor 8, a pressure sensor 9, and a flow meter 10. The hydraulic components and pipelines of the test hydraulic circuit (except for the solenoid directional valve 3 and the load regulating valve 11) are located inside the high / low temperature chamber, providing an oil flow path for the valve under test to operate in a cyclic opening / closing manner. A controller is configured to control the electromagnetic reversing valve 3 to automatically switch in sequence and the test valve to open / close. A data logger is configured to automatically record test data (pressure, temperature, number of times). A replenishment oil circuit is set up to compensate for the oil loss caused by leakage of the test valve, including the first shut-off valve 12, the second shut-off valve 13 and pipelines.

[0047] A method for high and low temperature durability testing of hydraulic valves includes a high temperature durability testing method, a low temperature durability testing method, and an oil replenishment method. This method also includes a room temperature durability test.

[0048] The specific high-temperature durability test method is as follows:

[0049] Step 1: Install and connect the hydraulic test circuit. Connect temperature sensor 8, pressure sensor 9, flow meter 10 to the controller, and then connect temperature sensor 8, pressure sensor 9, flow meter 10, and controller to the data logger. The first shut-off valve 12 and the second shut-off valve 13 are both in the closed state.

[0050] Step 2: Start the general hydraulic oil source, with the controller in manual mode. Open the first shut-off valve 12, and alternately control the solenoid directional valve 3 to the left and right positions 3 to 5 times. The left chamber of the hydraulic actuator cylinder 1 is filled with oil. Turn off the power supply to the solenoid directional valve 3 and shut off the first shut-off valve 12. Open the second shut-off valve 13, and alternately control the solenoid directional valve 3 to the right and left positions 3 to 5 times. The left chamber of the hydraulic actuator cylinder 2 is filled with oil. Turn off the power supply to the valve under test and shut off the second shut-off valve 13.

[0051] Step 3: Set the target temperature of the high / low temperature chamber according to the high temperature test requirements, start the high / low temperature chamber, and after the ambient temperature inside the chamber stabilizes, continue to observe the inlet temperature of the valve under test through temperature sensor 8 and data logger until the inlet temperature of the valve under test reaches the specified test temperature.

[0052] In automatic controller mode, the controller controls the high-pressure port P of the solenoid directional valve 3 to connect with the right chamber of the first hydraulic actuator cylinder 1 through the second load port C2, thereby creating high pressure in the left chamber of the first hydraulic actuator cylinder 1.

[0053] The controller controls the valve under test to open, and the oil flows through the load port C of the valve under test, through the flow meter 10, the load regulating valve 11, and the second check valve 5 to the right chamber of the second hydraulic actuator 2.

[0054] The controller controls the closed valve under test and controls the solenoid directional valve 3 to switch.

[0055] The controller controls the high-pressure port P of the electromagnetic reversing valve 3 to connect with the left chamber of the second hydraulic actuator 2 through the first load port C1, and the right chamber of the second hydraulic actuator 2 is under high pressure.

[0056] The controller controls the valve under test to open, and the oil flows through the load port C of the valve under test, through the flow meter 10, the load regulating valve 11, and the first check valve 4 to the left chamber of the first hydraulic actuator cylinder 1.

[0057] The controller shuts down the valve under test, completing two high-temperature durability tests on the valve.

[0058] Repeat the above process until all the high-temperature durability tests on the valve under test have been completed.

[0059] The specific method for low-temperature durability testing is as follows:

[0060] Step 1: Install and connect the hydraulic test circuit. Connect temperature sensor 8, pressure sensor 9, flow meter 10 to the controller, and then connect temperature sensor 8, pressure sensor 9, flow meter 10, and controller to the data logger. The first shut-off valve 12 and the second shut-off valve 13 are both in the closed state.

[0061] Step 2: Start the general hydraulic oil source, with the controller in manual mode. Open the first shut-off valve 12, and alternately control the solenoid directional valve 3 to the left and right positions 3 to 5 times. The left chamber of the hydraulic actuator cylinder 1 is filled with oil. Turn off the power supply to the solenoid directional valve 3 and shut off the first shut-off valve 12. Open the second shut-off valve 13, and alternately control the solenoid directional valve 3 to the right and left positions 3 to 5 times. The left chamber of the hydraulic actuator cylinder 2 is filled with oil. Turn off the power supply to the valve under test and shut off the second shut-off valve 13.

[0062] Step 3: Set the target temperature of the high / low temperature chamber according to the low temperature test requirements, start the high / low temperature chamber, and after the ambient temperature inside the chamber stabilizes, continue to observe the inlet temperature of the valve under test through temperature sensor 8 and data logger until the inlet temperature of the valve under test reaches the specified test temperature.

[0063] In automatic controller mode, the controller controls the high-pressure port P of the solenoid directional valve 3 to connect with the right chamber of the first hydraulic actuator cylinder 1 through the second load port C2, thereby creating high pressure in the left chamber of the first hydraulic actuator cylinder 1.

[0064] The controller controls the valve under test to open, and the oil flows through the load port C of the valve under test, through the flow meter 10, the load regulating valve 11, and the second check valve 5 to the right chamber of the second hydraulic actuator 2.

[0065] The controller controls the closed valve under test and controls the solenoid directional valve 3 to switch.

[0066] The controller controls the high-pressure port P of the electromagnetic reversing valve 3 to connect with the left chamber of the second hydraulic actuator 2 through the first load port C1, and the right chamber of the second hydraulic actuator 2 is under high pressure.

[0067] The controller controls the valve under test to open, and the oil flows through the load port C of the valve under test, through the flow meter 10, the load regulating valve 11, and the first check valve 4 to the left chamber of the first hydraulic actuator cylinder 1.

[0068] The controller shuts down the valve under test, completing two low-temperature durability tests on the valve under test.

[0069] Repeat the above process until all the low-temperature durability tests on the valve under test have been completed.

[0070] The specific method for replenishing oil is as follows:

[0071] Step 1: Start the general hydraulic oil source, set the controller to manual mode, and both the first shut-off valve 12 and the second shut-off valve 13 are in the closed state.

[0072] Step 2: The first shut-off valve 12 is opened, and the controller alternately controls the left and right positions 3 to 5 times. The left chamber of the first hydraulic actuator 1 is filled with oil. The power supply to the solenoid directional valve 3 is turned off, and the first shut-off valve 12 is shut off. The second shut-off valve 13 is opened, and the controller alternately controls the right and left positions 3 to 5 times. The left chamber of the second hydraulic actuator 2 is filled with oil. The power supply to the solenoid directional valve 3 is turned off, and the second shut-off valve 13 is shut off.

[0073] The specific method for room temperature durability testing is as follows:

[0074] Step 1: Install and connect the hydraulic test circuit. Connect temperature sensor 8, pressure sensor 9, flow meter 10 to the controller, and then connect temperature sensor 8, pressure sensor 9, flow meter 10, and controller to the data logger. The first shut-off valve 12 and the second shut-off valve 13 are both in the closed state.

[0075] Step 2: Start the general hydraulic oil source, with the controller in manual mode. Open the first shut-off valve 12, and alternately control the solenoid directional valve 3 to the left and right positions 3 to 5 times. The left chamber of the hydraulic actuator cylinder 1 is filled with oil. Turn off the power supply to the solenoid directional valve 3 and shut off the first shut-off valve 12. Open the second shut-off valve 13, and alternately control the solenoid directional valve 3 to the right and left positions 3 to 5 times. The left chamber of the hydraulic actuator cylinder 2 is filled with oil. Turn off the power supply to the valve under test and shut off the second shut-off valve 13.

[0076] Step 3, controller in automatic mode; the controller controls the high pressure port P of the solenoid directional valve 3 to connect with the right chamber of the first hydraulic actuator cylinder 1 through the second load port C2, and the left chamber of the first hydraulic actuator cylinder 1 forms high pressure.

[0077] The controller controls the valve under test to open, and the oil flows through the load port C of the valve under test, through the flow meter 10, the load regulating valve 11, and the second check valve 5 to the right chamber of the second hydraulic actuator 2.

[0078] The controller controls the closed valve under test and controls the solenoid directional valve 3 to switch.

[0079] The controller controls the high-pressure port P of the electromagnetic reversing valve 3 to connect with the left chamber of the second hydraulic actuator 2 through the first load port C1, and the right chamber of the second hydraulic actuator 2 is under high pressure.

[0080] The controller controls the valve under test to open, and the oil flows through the load port C of the valve under test, through the flow meter 10, the load regulating valve 11, and the first check valve 4 to the left chamber of the first hydraulic actuator cylinder 1.

[0081] The controller closes the valve under test, completing two room temperature durability tests on the valve under test.

[0082] Repeat the above process until all the room temperature durability tests on the valve under test have been completed.

Claims

1. A high and low temperature durability testing system for hydraulic valves, characterized in that, The system includes a high / low temperature chamber, a test hydraulic circuit, a controller, a data logger, and a universal hydraulic power source. The test hydraulic circuit includes a first hydraulic actuator, a second hydraulic actuator, a solenoid directional valve, a temperature sensor, a pressure sensor, a flow meter, a load regulating valve, and a valve under test. The universal hydraulic power source is connected to the return port R and pressure port P of the solenoid directional valve. The first load port C1 of the solenoid directional valve is connected to the left chamber of the first hydraulic actuator and the left chamber of the second hydraulic actuator, and the second load port C2 of the solenoid directional valve is connected to the right chamber of the first hydraulic actuator and the right chamber of the second hydraulic actuator. The load regulating valve is connected to the flow meter, and the flow meter is connected to the load port C of the valve under test. The temperature sensor and pressure sensor are located on the connecting pipeline between the left chamber of the first hydraulic actuator, the right chamber of the second hydraulic actuator, and the high-pressure port P1 of the valve under test, and are close to the valve under test. The valve has a high-pressure port P1; the controller is connected to the temperature sensor, pressure sensor, flow meter, solenoid directional valve, and the valve under test via cables; the first hydraulic actuator, second hydraulic actuator, temperature sensor, pressure sensor, flow meter, and valve under test are all installed in a high / low temperature chamber; the system also includes a first check valve, a second check valve, a third check valve, and a fourth check valve. The first check valve is installed on the pipeline between the left chamber of the first hydraulic actuator and the load regulating valve, with its outlet facing the left chamber of the first hydraulic actuator; the second check valve is installed on the pipeline between the right chamber of the second hydraulic actuator and the load regulating valve, with its outlet facing the right chamber of the second hydraulic actuator; the third check valve is installed on the pipeline between the right chamber of the second hydraulic actuator and the high-pressure port P1 of the valve under test, with its outlet facing the high-pressure port P1 of the valve under test; the outlet of the fourth check valve is connected to the outlet of the third check valve, and its inlet is connected to the left chamber of the first actuator.

2. The high and low temperature durability testing system for hydraulic valves according to claim 1, characterized in that, It also includes a first shut-off valve and a second shut-off valve. The first shut-off valve is installed on the connecting pipeline between the fourth check valve and the first load port C1 of the solenoid directional valve; the second shut-off valve is installed on the connecting pipeline between the second load port C2 of the solenoid directional valve and the right chamber of the second hydraulic actuator.

3. The high and low temperature durability testing system for hydraulic valves according to claim 2, characterized in that, It also includes a data logger, which is connected to the controller, temperature sensor, pressure sensor, and flow meter.

4. The high and low temperature durability testing system for hydraulic valves according to claim 3, characterized in that, The first check valve, the second check valve, the third check valve, and the fourth check valve are all located inside the high / low temperature chamber.

5. The method for high and low temperature durability testing system of hydraulic valve according to claim 4, characterized in that, This includes high-temperature durability testing methods, low-temperature durability testing methods, and oil replenishment methods.

6. The method for high and low temperature durability testing system of hydraulic valve according to claim 5, characterized in that, The high-temperature durability test method includes the following steps: Step 1: Install and connect the hydraulic test circuit. Connect the temperature sensor, pressure sensor, flow meter, and controller. Then connect the temperature sensor, pressure sensor, flow meter, and controller to the data logger. The first and second shut-off valves are both in the closed state. Step 2: Start the general hydraulic oil source, with the controller in manual mode. Open the first shut-off valve and alternately control the solenoid directional valve to the left and right positions 3-5 times. The left chamber of the hydraulic actuator cylinder will be filled with oil. Turn off the power supply to the solenoid directional valve and shut off the first shut-off valve. Open the second shut-off valve and alternately control the solenoid directional valve to the right and left positions 3-5 times. The left chamber of the hydraulic actuator cylinder will be filled with oil. Turn off the power supply to the valve under test and shut off the second shut-off valve. Step 3: Set the target temperature of the high / low temperature chamber according to the high temperature test requirements, start the high / low temperature chamber, and after the ambient temperature inside the chamber stabilizes, continue to observe the inlet temperature of the valve under test through the temperature sensor and data logger until the inlet temperature of the valve under test reaches the specified test temperature. When the controller is in automatic mode, the controller controls the high-pressure port P of the solenoid directional valve to connect with the right chamber of the first hydraulic actuator through the second load port C2, and the left chamber of the first hydraulic actuator forms high pressure. The controller controls the valve under test to open, and the oil flows through the load port C of the valve under test, through the flow meter, the load regulating valve, and the second check valve to the right chamber of the second hydraulic actuator. The controller controls the closed valve under test and controls the switching valve to switch directions. The controller controls the high-pressure port P of the electromagnetic reversing valve to connect with the left chamber of the second hydraulic actuator through the first load port C1, and the right chamber of the second hydraulic actuator is under high pressure. The controller controls the valve under test to open, and the oil flows through the load port C of the valve under test, through the flow meter, the load regulating valve, and the first check valve to the left chamber of the first hydraulic actuator. The controller closes the valve under test, completing two high-temperature durability tests on the valve under test. Repeat the above process until all the high-temperature durability tests on the valve under test have been completed.

7. The method for high and low temperature durability testing system of hydraulic valve according to claim 6, characterized in that, The low-temperature durability test method includes the following steps: Step 1: Install and connect the hydraulic test circuit. Connect the temperature sensor, pressure sensor, flow meter, and controller. Then connect the temperature sensor, pressure sensor, flow meter, and controller to the data logger. The first and second shut-off valves are both in the closed state. Step 2: Start the general hydraulic oil source, with the controller in manual mode. Open the first shut-off valve and alternately control the solenoid directional valve to the left and right positions 3-5 times. The left chamber of the hydraulic actuator cylinder will be filled with oil. Turn off the power supply to the solenoid directional valve and shut off the first shut-off valve. Open the second shut-off valve and alternately control the solenoid directional valve to the right and left positions 3-5 times. The left chamber of the hydraulic actuator cylinder will be filled with oil. Turn off the power supply to the valve under test and shut off the second shut-off valve. Step 3: Set the target temperature of the high / low temperature chamber according to the low temperature test requirements, start the high / low temperature chamber, and after the ambient temperature inside the chamber stabilizes, continue to observe the inlet temperature of the valve under test through the temperature sensor and data logger until the inlet temperature of the valve under test reaches the specified test temperature. The controller is in automatic mode; the controller controls the high-pressure port P of the solenoid directional valve to connect with the right chamber of the first hydraulic actuator 1 through the second load port C2, and the left chamber of the first hydraulic actuator 1 is under high pressure. The controller controls the valve under test to open, and the oil flows through the load port C of the valve under test, through the flow meter, the load regulating valve, and the second check valve to the right chamber of the second hydraulic actuator. The controller controls the closed valve under test and controls the switching valve to switch directions. At this time, the high-pressure port P of the electromagnetic reversing valve is connected to the left chamber of the second hydraulic actuator through the first load port C1, and the right chamber of the second hydraulic actuator is under high pressure. The controller controls the valve under test to open, and the oil flows through the load port C of the valve under test, through the flow meter, the load regulating valve, and the first check valve to the left chamber of the first hydraulic actuator 1. The controller closes the valve under test, completing two low-temperature durability tests on the valve under test. Repeat the above process until all the low-temperature durability tests on the valve under test have been completed.

8. The method for high and low temperature durability testing system of hydraulic valve according to claim 7, characterized in that, The oil replenishment method includes the following steps: Step 1: Start the general hydraulic oil source, set the controller to manual mode, and both the first and second shut-off valves are in the closed state. Step 2: Open the first shut-off valve, and the controller alternately controls the left and right positions 3 to 5 times. The left chamber of the first hydraulic actuator is filled with oil. Turn off the power supply to the solenoid directional valve and shut off the first shut-off valve. Open the second shut-off valve, and the controller alternately controls the right and left positions 3 to 5 times. The left chamber of the second hydraulic actuator is filled with oil. Turn off the power supply to the solenoid directional valve and shut off the second shut-off valve.

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