An offline and online servo valve fault diagnosis device and method

Abstract

The present application relates to the technical field of detection and fault diagnosis of servo valves, and particularly relates to a servo valve fault diagnosis device and method which can be offline and online, comprising a test platform and a PC control end; four performance test pipelines are highly integrated, the intelligent switching of electromagnetic valves is used to realize the rapid reconstruction of different test circuits, meanwhile, various types of sensors are configured in the system, which are matched with a data acquisition and processing module to adapt to the expanding test requirements and greatly improve the automation degree, which not only avoids the time-consuming and labor-consuming and equipment damage caused by frequent disassembly and installation of servo valves in traditional offline detection, but also overcomes the limitations of difficult comprehensive performance evaluation and accurate fault diagnosis in online detection, greatly improves the detection efficiency and convenience, reduces the equipment downtime and maintenance cost, shortens the use of pipelines, optimizes the overall layout of the system, and promotes the high integration and operation convenience of the experimental platform.

Description

Technical Field

[0001] This invention relates to the field of servo valve detection and fault diagnosis technology, specifically to a servo valve fault diagnosis device and method that can be used both offline and online. Background Technology

[0002] Electro-hydraulic servo valves are one of the core control components in hydraulic control systems. Due to their advantages such as high control precision, fast response, and good stability, they are widely used in industrial systems. However, due to the influence of the system operating environment, the characteristics of servo valves change over time, and their performance will gradually deteriorate or even cause sudden failures.

[0003] With the increasing automation of industry and the ever-more stringent requirements for production continuity, the demand for performance control and fault prevention of servo valves is growing. Traditionally, the performance testing of servo valves has mainly relied on offline testing methods. Offline testing typically requires disassembling the servo valve from the actual working system and transporting it to a specialized testing laboratory. Various professional testing instruments, such as high-precision flow meters, pressure sensors, and torque meters, are used to simulate its working conditions and measure performance parameters. While this method can obtain relatively accurate performance data, such as the valve's flow-pressure characteristic curve and internal leakage curve, in a relatively ideal and controllable environment, it has many significant drawbacks. On the one hand, the process of disassembling and reinstalling the servo valve is time-consuming and labor-intensive, causing prolonged equipment downtime, production interruptions, and huge economic losses. This is especially true for large production lines or industrial scenarios with extremely high continuity requirements, where downtime costs are incalculable. On the other hand, frequent disassembly and installation operations can easily cause additional mechanical damage to the servo valve and its connecting components, affecting the valve's service life and original performance, and may even introduce new potential faults.

[0004] Meanwhile, during online operation, servo valves face complex and variable working conditions, including different load impacts, oil temperature fluctuations, and changes in the degree of media contamination. These actual working conditions are difficult to simulate completely and accurately in an offline testing environment, resulting in a certain deviation between the offline testing results and the actual performance of the servo valve in a real working system. This makes it impossible to reflect the current working status of the servo valve in real time, which is not conducive to timely detection of potential faults and taking preventive measures.

[0005] In summary, both traditional offline testing and current online testing methods have their limitations in the field of servo valve performance testing and fault diagnosis, making it difficult to meet the modern industrial demand for efficient, accurate, real-time and comprehensive testing and diagnosis of servo valves. Therefore, a servo valve fault diagnosis device and method that can be used both offline and online is proposed. Summary of the Invention

[0006] To address the technical problems existing in the prior art, the present invention provides a servo valve fault diagnosis device and method that can be used both offline and online.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a servo valve fault diagnosis device capable of offline and online operation, comprising a test platform and a PC control terminal. The test platform includes an oil tank, a valve plate, a first hydraulic cylinder, a second hydraulic cylinder, an electromagnetic directional valve, a sensor monitoring component, and a pipeline control component. The valve plate and the electromagnetic directional valve each have four oil ports: P, A, T, and B. The oil port P of the electromagnetic directional valve is connected to the oil port T of the valve plate. The oil port T of the electromagnetic directional valve is connected to the oil port A. The oil port A of the electromagnetic directional valve is connected to the oil port B of the valve plate. The oil port B of the electromagnetic directional valve is connected to the oil ports A and B of the valve plate. The oil port P of the valve plate is connected to the oil tank through a pipeline. The pipeline control component and the sensor monitoring component are installed on the pipelines of the four oil ports P, A, T, and B of the valve plate and the electromagnetic directional valve. The first hydraulic cylinder and the second hydraulic cylinder are connected in series on the pipeline between the oil ports A and B of the valve plate.

[0008] Preferably, the test platform further includes an inlet filter, a flow meter, a level gauge, a first filter, a second filter, a first motor pump unit, a second motor pump unit, an accumulator, an overflow valve, a first check valve, a second check valve, a third check valve, and a fourth check valve. The flow meter is installed on the pipeline between port A and port B of the valve plate. The inlet filter is installed on port P of the valve plate. The flow meter is installed on port B of the solenoid directional valve. The first filter, the second filter, and the level gauge are installed inside the oil tank. The first filter is connected in sequence to the first motor pump unit, the second check valve, and the accumulator. The second filter is connected in sequence to the second motor pump unit and the third check valve. The overflow valve is installed on the pipeline between the first check valve and the oil tank. The first filter and the second filter are connected in parallel on the pipeline between the first check valve and the overflow valve. The fourth check valve is installed on the pipeline between port T of the solenoid directional valve and the air-cooled equipment.

[0009] Preferably, the sensor monitoring assembly includes a first pressure sensor, a second pressure sensor, a third pressure sensor, a fourth pressure sensor, a first flow sensor, a second flow sensor, a third flow sensor, and a displacement sensor. The first, second, third, and fourth pressure sensors are respectively disposed on four oil ports P, A, T, and B of the valve plate. The first, second, and third flow sensors are respectively disposed on three oil ports A, T, and B of the valve plate. The displacement sensor is disposed at one end of the piston rod of the first hydraulic cylinder.

[0010] Preferably, the pipeline control assembly includes a first solenoid valve, a second solenoid valve, a third solenoid valve, a solenoid directional valve, a fifth solenoid valve, a sixth solenoid valve, a seventh solenoid valve, an eighth solenoid valve, and a pressure reducing valve. The first solenoid valve is disposed between port A and port B of the valve plate. The second solenoid valve is disposed at port A of the solenoid directional valve. The third solenoid valve is disposed in the pipeline between the second solenoid valve and the third flow sensor. The fifth solenoid valve is disposed in the pipeline between the inlet filter and the first pressure sensor. The sixth solenoid valve is disposed in the pipeline between the inlet filter and port T of the solenoid directional valve. The seventh solenoid valve is disposed in the pipeline between the first hydraulic cylinder and the first flow sensor. The eighth solenoid valve and the pressure reducing valve are connected in series in the pipeline between the first hydraulic cylinder and the second hydraulic cylinder. The pressure reducing valve is connected to the oil tank through a pipeline.

[0011] Preferably, the pipeline control assembly includes a first shut-off valve, a second shut-off valve, a third shut-off valve, a fourth shut-off valve, a fifth shut-off valve, a sixth shut-off valve, a seventh shut-off valve, an eighth shut-off valve, and a ninth shut-off valve. The first shut-off valve is located on the pipeline connecting the oil port P of the valve plate to the first pressure sensor; the second shut-off valve is located on the pipeline connecting the oil port A of the valve plate to the second pressure sensor; the third shut-off valve is located on the pipeline connecting the oil port T of the valve plate to the third pressure sensor; the fourth shut-off valve is located on the pipeline connecting the oil port B of the valve plate to the fourth pressure sensor; the fifth shut-off valve is located on the pipeline between the relief valve and the oil tank; the sixth shut-off valve is located on the pipeline between the accumulator and the second check valve; the seventh shut-off valve is located on the pipeline between the pressure reducing valve and the oil tank; the eighth shut-off valve is located on the pipeline between the second hydraulic cylinder and the fifth pressure sensor; and the ninth shut-off valve is located on the pipeline between the second hydraulic cylinder and the sixth pressure sensor.

[0012] Preferably, the PC control terminal system is equipped with a fault diagnosis module, which includes a data preprocessing unit, a feature extraction unit, and a state recognition unit. The data preprocessing unit is used to filter, normalize, and time-align the acquired multi-source signals. The feature extraction unit uses a convolutional neural network to extract features from the processed pressure, flow, and displacement time-series data. The state recognition unit optimizes the structural and training parameters of the CNN model based on the whale optimization algorithm to obtain an optimized WOA-CNN model.

[0013] This invention also discloses a method for diagnosing servo valve faults that can be used both offline and online, comprising the following steps:

[0014] S1 performs offline testing on the servo valve under test, including static characteristic testing and dynamic frequency response testing. Static characteristic testing is divided into flow rate, pressure and internal leakage characteristic testing.

[0015] S2, perform online testing on the servo valve under test;

[0016] S3. The data detected in steps S1 and S2 is transmitted to the PC control terminal. The optimized WOA-CNN model classifies and identifies the operating status of the servo valve under test, judges the performance status of the servo valve under test, and finally displays the analysis results on the screen of the PC control terminal, so that the user can intuitively see whether the servo valve under test has a fault and its performance status.

[0017] Preferably, the static characteristic detection in step S1 includes the following steps:

[0018] S111, Flow Characteristic Detection: The servo valve under test is installed on the valve plate, and all shut-off valves are kept in the open state. The first motor pump group and the second motor pump group are turned on. The overflow valve, the first solenoid valve, the third solenoid valve and the fifth solenoid valve are adjusted to the energized state. The working chambers A and B of the servo valve under test are connected to form a flow test circuit. During the test, the oil in the tank passes through the first filter, the second filter, the first motor pump group, the second motor pump group, the second check valve, the third check valve, the first check valve, the oil inlet filter and the fifth solenoid valve in sequence to enter the oil port P of the valve plate, and then enter the servo valve under test. The oil is output through the oil port A and oil port B of the servo valve under test, and flows through the first solenoid valve, the third solenoid valve and the corresponding pipeline through the first flow sensor, the third flow sensor and the flow meter. During the test, the first flow sensor and the third flow sensor collect the flow at oil port A and oil port B. The PC control terminal obtains the flow characteristics of the servo valve under test according to the relationship between the input current and the output flow.

[0019] S112, Pressure Characteristic Detection: The servo valve under test is installed on the valve plate, and all shut-off valves are kept in the open state. The first motor pump group and the second motor pump group are turned on, so that the overflow valve and the fifth solenoid valve are energized. The working chambers A and B of the servo valve under test are not connected, so that the servo valve under test is in a pressure detection state. The oil in the tank enters the P port of the valve plate according to the same path as in step S111, and then enters the servo valve under test. The pressure of oil port P, oil port A, oil port T, and oil port B are detected by the first pressure sensor, the second pressure sensor, the third pressure sensor, and the fourth pressure sensor, respectively. The PC control terminal obtains the pressure characteristics of the servo valve under test according to the pressure changes of each oil port under different input currents.

[0020] S113, Internal Leakage Characteristic Detection: The servo valve under test is installed on the valve plate, with all shut-off valves in the open state. The first and second motor pump groups are turned on, and the overflow valve, second solenoid valve, and fifth solenoid valve are adjusted to the energized state. The solenoid directional valve is energized and switched to the right position. The A and B working chambers of the servo valve under test are not connected, forming an oil circuit with internal leakage oil as the main detection object. The oil in the tank enters the oil port P of the valve plate according to the same path as in step S, and then enters the servo valve under test. If there is an internal leakage problem in the servo valve under test, the leaked oil enters the internal leakage return oil line through the oil port T of the valve plate, the right position oil line of the solenoid directional valve, the second solenoid valve, and the flow meter, and finally returns to the oil tank. During the detection process, the flow meter or the second flow sensor collects the leakage flow in the return oil line. The PC control terminal determines whether the servo valve under test has an internal leakage over-limit fault based on the leakage flow.

[0021] Preferably, the dynamic frequency response in step S1 includes the following steps:

[0022] S121, the servo valve under test is mounted on the valve plate, all shut-off valves are kept in the open state, the first motor pump group and the second motor pump group are turned on, so that the overflow valve, the fifth solenoid valve, the seventh solenoid valve and the eighth solenoid valve are energized, the oil port A and oil port B of the servo valve under test are connected to the two chambers of the first hydraulic cylinder, and at the same time the second hydraulic cylinder and the pressure reducing valve are connected to the loading branch, forming a dynamic loading test circuit from the servo valve under test to the first hydraulic cylinder, then to the second hydraulic cylinder and finally to the pressure reducing valve;

[0023] S122, the oil in the tank enters the valve plate through the same path as in step S, then enters the servo valve under test. The oil is output through the servo valve under test through the oil ports A and B, and then through the seventh solenoid valve, the first hydraulic cylinder, the eighth solenoid valve, the pressure reducing valve, and the second hydraulic cylinder to form a dynamic loading test circuit. The load is changed by the pressure reducing valve and the second hydraulic cylinder, thereby changing the pressure difference environment when the first hydraulic cylinder is working.

[0024] S123, different pressure values ​​are set for the pressure reducing valve, and the second hydraulic cylinder forms a constant load of different levels. When the first hydraulic cylinder moves, it will face different resistances, so the pressure difference between the two chambers will also be different. The characteristics of the first hydraulic cylinder under different pressure differences are tested, which is characterized by the dynamic characteristics of the servo valve. The pressure values ​​of the four oil ports A, P, T and B of the servo valve under test can be obtained by the first pressure sensor, the second pressure sensor, the third pressure sensor and the fourth pressure sensor.

[0025] S124 measures the flow rates of the three oil ports A, T, and B of the servo valve under test through the first flow sensor, the second flow sensor, and the third flow sensor; collects the displacement signal of the piston through the displacement sensor in the first hydraulic cylinder; and cools the hydraulic oil returning to the oil tank through the air-cooling device.

[0026] Preferably, step S2 includes the following steps:

[0027] S21, keep all shut-off valves in the open state, energize the fifth, seventh and eighth solenoid valves, place the servo valve under test on the valve plate, connect the oil port A and oil port B of the servo valve under test, and connect the loading branch where the servo valve under test, the first hydraulic cylinder, the second hydraulic cylinder and the pressure reducing valve are located.

[0028] S22, the opening pressure of the relief valve is adjusted to the pressure value of the servo valve under test when the hydraulic system is working normally by means of a given current signal. After the first motor pump group and the second motor pump group are turned on, oil is supplied to the online detection platform. At this time, the oil enters the oil port P of the valve plate through the same path as in step S111, and enters the servo valve under test through the valve plate. The oil is distributed from oil port P to oil port A and oil port B, and enters the corresponding working chamber of the first hydraulic cylinder, pushing the piston of the first hydraulic cylinder to move. The opening pressure of the relief valve is adjusted by means of a current signal given by the computer, thereby changing the pressure of the oil supply line to simulate different actual working conditions.

[0029] S23, when the oil supply line pressure reaches the relief valve set pressure, excess oil flows back to the oil tank through the relief valve and the fifth shut-off valve, thereby maintaining a stable oil supply pressure. At the same time, the second hydraulic cylinder is connected to the loading branch as an auxiliary loading execution unit. The pressure reducing valve is used to set the loading pressure of the second hydraulic cylinder. When the loading branch pressure exceeds the pressure reducing valve set pressure, excess oil flows back to the oil tank through the pressure reducing valve and the seventh shut-off valve, thereby enabling the second hydraulic cylinder to form a stable and adjustable load on the first hydraulic cylinder.

[0030] S24, after a stable load is formed, the pressure and flow changes of the tested servo valve are monitored by the sensor monitoring component. The information on pressure and flow changes is transmitted to the PC and compared with the qualified data of the tested servo valve by the fault diagnosis module. By monitoring the pressure, displacement signal and flow values ​​of port A and port B of the tested servo valve, the performance of the tested servo valve is accurately displayed and warning information and solutions are given.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] 1. The pipelines for the four performance tests in this invention are highly integrated. The intelligent switching of solenoid valves enables rapid reconstruction of different test loops. At the same time, the system is equipped with various types of sensors, along with data acquisition and processing modules. This avoids the time-consuming, labor-intensive, and equipment-damaging process caused by the frequent disassembly and installation of servo valves in traditional offline testing, and overcomes the limitations of online testing in comprehensively evaluating performance and accurately diagnosing faults. This greatly improves testing efficiency and convenience, reduces equipment downtime and maintenance costs, adapts to the ever-expanding testing needs, and significantly improves the degree of automation. It solves the problems of time-consuming and labor-intensive testing of servo valves in offline testing experimental benches, which may introduce new impurities and cause some wear to the servo valves. It also shortens the use of pipelines, optimizes the overall system layout, and promotes the high integration and ease of operation of the experimental platform.

[0033] 2. This invention collects rich data through multiple sensors and transmits it to the fault diagnosis module. Based on preset diagnostic rules and algorithms, it performs comprehensive analysis, which can accurately locate and qualitatively analyze complex faults and early weak faults caused by the coupling of multiple factors. This provides detailed and reliable decision-making basis for subsequent maintenance and repair, effectively improving the reliability and service life of servo valves. It solves the problem that most online testing test benches on the market can only identify relatively common and typical fault modes, and it is difficult to accurately locate and qualitatively analyze some complex faults and early weak faults caused by the coupling of multiple factors. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the servo valve testing principle of the present invention;

[0035] Figure 2 This is a schematic diagram of the process of the present invention.

[0036] Figure 3 This is a schematic diagram of the simulation model principle of the present invention;

[0037] Figure 4 This is a schematic diagram of the training set results of the present invention;

[0038] Figure 5 This is a schematic diagram of the test set results of the present invention;

[0039] Figure 6 This is a schematic diagram of the convolutional neural network structure of the present invention;

[0040] Figure 7 This is a flowchart of the WOA-CNN algorithm of the present invention;

[0041] Figure 8 This is a diagram of the oil supply and return pipelines for each detection mode of the present invention;

[0042] Figure 9This is the oil circuit diagram for offline detection of flow characteristics in this invention;

[0043] Figure 10 This is the oil circuit diagram for pressure characteristic testing in the offline detection of the present invention;

[0044] Figure 11 This is the oil circuit diagram for offline detection of internal leakage characteristics in this invention;

[0045] Figure 12 This is the circuit diagram for the dynamic frequency response test in the offline detection of the present invention;

[0046] Figure 13 This is the online detection oil circuit diagram of the present invention;

[0047] Figure 14 This is a diagram of the loading branch, the two-chamber pressure detection branch, and the internal leakage return oil pipeline of the present invention.

[0048] The numbers in the image represent:

[0049] 1. Oil tank; 2. First filter; 3. Second filter; 4. Inlet filter; 5. First check valve; 6. Flow meter; 7. First shut-off valve; 8. Second shut-off valve; 9. Third shut-off valve; 10. Fourth shut-off valve; 11. Air-cooled equipment; 12. Fourth check valve; 13. Fifth shut-off valve; 14. First motor pump unit; 15. Second motor pump unit; 16. Second check valve; 17. Third check valve; 18. Sixth shut-off valve; 19. Accumulator; 20. First hydraulic cylinder; 21. Level gauge; 22. Seventh shut-off valve; 23. Second hydraulic cylinder; 24. Eighth shut-off valve; 25. Ninth shut-off valve; 26. Shut-off valve; 27. Valve plate; 28. Relief valve; 29. ​​First solenoid valve; 30. Second solenoid valve; 31. Third solenoid valve; 32. Solenoid directional valve; 33. Fifth solenoid valve; 34. Sixth solenoid valve; 35. Seventh solenoid valve; 36. Eighth solenoid valve; 37. Pressure reducing valve; 38. First pressure sensor; 39. Second pressure sensor; 40. Third pressure sensor; 41. Fourth pressure sensor; 42. Fifth pressure sensor; 43. Sixth pressure sensor; 44. First flow sensor; 45. Second flow sensor; 46. Third flow sensor; 47. Displacement sensor. Detailed Implementation

[0050] The present invention will be further described below with reference to the accompanying drawings and embodiments, which illustrate the above and other technical features and advantages of the present invention. However, the following embodiments are merely preferred embodiments of the present invention and are not exhaustive.

[0051] Example:

[0052] like Figure 1-14As shown, the present invention provides a servo valve fault diagnosis device that can be used both offline and online, including a test platform and a PC control terminal. The test platform includes a valve plate 26 and a solenoid directional valve 31. The oil ports P, A, T, and B of the valve plate 26 are respectively equipped with a first pressure sensor 37, a second pressure sensor 38, a third pressure sensor 39, and a fourth pressure sensor 40; the oil ports A, T, and B of the valve plate 26 are respectively equipped with a first flow sensor 43, a second flow sensor 44, and a third flow sensor 45.

[0053] A first shut-off valve 7 is installed on the pipeline connecting the oil port P of valve plate 26 to the first pressure sensor 37; a second shut-off valve 8 is installed on the pipeline connecting the oil port A of valve plate 26 to the second pressure sensor 38; a third shut-off valve 9 is installed on the pipeline connecting the oil port T of valve plate 26 to the third pressure sensor 39; and a fourth shut-off valve 10 is installed on the pipeline connecting the oil port B of valve plate 26 to the fourth pressure sensor 40. The oil port P of valve plate 26 is connected in sequence to the fifth solenoid valve 32, the inlet filter 4, the first check valve 5, the overflow valve 27, and the fifth shut-off valve 13, and then connected to the oil tank 1. An oil drain ball valve and a junction box are installed on the outside of the oil tank 1. The oil drain ball valve is connected to the drain pipeline of the oil tank 1 for draining hydraulic oil during maintenance. A first solenoid valve 28, a flow meter 6, and a... are installed on the oil line between oil ports A and B of valve plate 26. The third solenoid valve 30 has its port T on the valve plate 26 connected to the port P of the solenoid directional valve 31. On another oil line between ports A and B of the valve plate 26, there is a seventh solenoid valve 34, a first hydraulic cylinder 20, an eighth solenoid valve 35, a pressure reducing valve 36, and a second hydraulic cylinder 23. The pressure reducing valve 36 is connected to the seventh shut-off valve 22 and then to the oil tank 1. The first flow sensor 43 is connected to the pipeline between port A of the valve plate 26 and the seventh solenoid valve 34. The third flow sensor 45 is connected to the pipeline between port B of the valve plate 26 and the eighth solenoid valve 35. An eighth shut-off valve 24 is installed on the pipeline connecting the second hydraulic cylinder 23 and the fifth pressure sensor 41. A ninth shut-off valve 25 is installed on the pipeline connecting the second hydraulic cylinder 23 and the sixth pressure sensor 42. The first hydraulic cylinder 20 is connected to the displacement sensor 46.

[0054] The oil port T of the solenoid directional valve 31 is connected to the sixth solenoid valve 33. The sixth solenoid valve 33 is connected to the pipeline between the fifth solenoid valve 32 and the oil inlet filter 4. The oil port T of the solenoid directional valve 31 is connected to the fourth check valve 12 and the air-cooled part, and then connected to the oil tank 1. The second flow sensor 44 is connected to the pipeline between the oil port T of the solenoid directional valve 31 and the fourth check valve 12. The oil port B of the solenoid directional valve 31 is connected to the pipeline between the first solenoid valve 28 and the flow meter 6. The oil port A of the solenoid directional valve 31 is connected to the oil port T of the solenoid directional valve 31. The oil port A of the solenoid directional valve 31 is connected to the second solenoid valve 29 and the second flow sensor 44.

[0055] In this embodiment, the test platform also includes a first filter 2 and a second filter 3, a first motor pump group 14 and a second motor pump group 15, and an accumulator 19. The first filter 2 and the second filter 3 are placed in the oil tank 1 and are connected in sequence to the first motor pump group and the second motor pump group 15, the second check valve 16 and the third check valve 17, and are connected in parallel to the pipeline between the first check valve 5 and the overflow valve 27. The accumulator 19 is connected to the sixth shut-off valve 18 and is connected to the parallel oil line.

[0056] In this embodiment, the software system of the PC control terminal is equipped with a fault diagnosis module, which includes a data preprocessing unit, a feature extraction unit, and a state recognition unit. The data preprocessing unit is used to filter, normalize, and time-align the acquired multi-source signals. The feature extraction unit uses a convolutional neural network (CNN) to extract features from the processed pressure, flow, and displacement time-series data. The state recognition unit optimizes the structural and training parameters of the CNN model based on the Whale Optimization Algorithm (WOA), including the number of convolutional kernels, the size of the convolutional kernels, the learning rate, and the batch size. It iterative optimization is performed using the model classification error as the fitness function to obtain the optimized WOA-CNN model. The connection lines of each pressure sensor, flow sensor, solenoid valve, and other electrical components are gathered in junction box II and connected to the PC control terminal to realize data transmission and electrical control between the test platform and the control system. A pressure surface plate is set on the top of the test platform. The pressure surface plate is connected to the signal output terminal of each pressure sensor to centrally display the pressure data of each detection position of the tested servo valve.

[0057] In this embodiment, during testing, the first shut-off valve 7, the second shut-off valve 8, the third shut-off valve 9, the fourth shut-off valve 10, the fifth shut-off valve 13, the sixth shut-off valve 18, the seventh shut-off valve 22, the eighth shut-off valve 24, and the ninth shut-off valve 25 are opened. (The first shut-off valve 7, the second shut-off valve 8, the third shut-off valve 9, and the fourth shut-off valve 10 are respectively connected to the pressure testing branches corresponding to oil ports P, A, T, and B of the valve plate 26; the fifth shut-off valve 13 is connected to the return oil line of the overflow valve 27 for easy pressure adjustment; the sixth shut-off valve 18 is connected to the accumulator 19 to improve the stability of the pressure supply; the seventh shut-off valve 22 is connected to the pressure reducing valve 36 or the loading branch, the loading branch being as follows...) Figure 14 The section shown in bold magenta indicates that the eighth shut-off valve 24 and the ninth shut-off valve 25 connect to the pressure detection branch of the two chambers of the second hydraulic cylinder 23. The pressure detection branch of the two chambers is as follows: Figure 14(As shown in the bold green line in the middle), the first motor pump group 14 and the second motor pump group 15 are started, so that the hydraulic oil in the oil tank 1 passes through the first filter 2 and the second filter 3 respectively into the first motor pump group 14 and the second motor pump group 15, and then passes through the second check valve 16 and the third check valve 17 respectively into the oil supply line. The servo valve under test is placed on the valve plate 26. The hydraulic oil in the oil supply line passes through the first check valve 5 and the inlet filter 4 and enters the oil port P of the valve plate 26, and the valve plate 26 supplies hydraulic oil to the servo valve under test. The oil supply line is as follows: Figure 8 The part indicated by the thick blue line.

[0058] Adjust the opening pressure of the relief valve 27. When the pressure exceeds the set value, excess oil flows back to the oil tank 1 through the relief valve 27 and the fifth shut-off valve 13. The return oil from the tested servo valve and test circuit returns to the oil tank 1 through the oil port T of the valve plate 26, the solenoid directional valve 31, or the return oil pipeline. Part of the return oil is cooled by the fourth check valve 12 and the air-cooling device 11 before returning to the oil tank 1 to ensure stable oil temperature during the test. During dynamic testing and online loading testing, when the pressure in the loading chamber of the second hydraulic cylinder 23 exceeds the pressure set by the pressure reducing valve 36, excess oil flows back to the oil tank 1 through the pressure reducing valve 36 and the seventh shut-off valve 22, thereby limiting the pressure of the loading branch and forming a stable and adjustable load. The return oil pipeline is as follows: Figure 8 The part shown is highlighted in red bold.

[0059] In this embodiment, the servo valve under test is tested offline and monitored online through a testing platform, and the monitoring results are sent to the PC control terminal. The optimized WOA-CNN model classifies and identifies the operating status of the servo valve under test, judges the performance status of the servo valve under test, and finally displays the analysis results on the screen of the PC control terminal, so that the user can intuitively see whether the servo valve under test has any faults and its performance status.

[0060] Offline testing of the servo valve under test is divided into static characteristic testing and dynamic frequency response testing. Static characteristic testing is further divided into flow rate, pressure, and internal leakage characteristic testing, specifically:

[0061] (1) Flow characteristic detection: The servo valve under test is installed on the valve plate 26, and all shut-off valves are kept in the open state. The first motor pump group 14 and the second motor pump group 15 are turned on, so that the overflow valve 27, the first solenoid valve 28, the third solenoid valve 30 and the fifth solenoid valve 32 are adjusted to be energized. The working chambers A and B of the servo valve under test are connected to form a flow test circuit. During the test, the oil in the oil tank 1 passes through the first filter 2, the second filter 3, the first motor pump group 14, the second motor pump group 15, the second check valve 16, the third check valve 17, the first check valve 5, the oil inlet filter 4 and the fifth solenoid valve 32 in sequence to enter the oil port P of the valve plate 26, and then enter the servo valve under test. The oil is output through the oil port A and the oil port B of the servo valve under test, and flows through the first solenoid valve 28, the third solenoid valve 30 and the corresponding pipeline through the first flow sensor 43, the third flow sensor 45 and the flow meter 6. During the test, the first flow sensor 43 and the third flow sensor 45 collect the flow rates at ports A and B. The PC control terminal obtains the flow characteristics of the servo valve under test based on the relationship between the input current and the output flow rate. After the flow test is completed, the oil flows back to the oil tank 1 through port T of valve plate 26, the fourth check valve 12, and the air-cooling device 11. When the system pressure exceeds the set value, part of the oil is directly discharged back to the oil tank 1 through the overflow valve 27. The oil circuits involved in the flow characteristic test are as follows: Figure 9 The orange section is shown in the middle.

[0062] (2) Pressure characteristic test: The servo valve under test is installed on the valve plate 26, and all shut-off valves are kept in the open state. The first motor pump group 14 and the second motor pump group 15 are opened, so that the overflow valve 27 and the fifth solenoid valve 32 are energized. The A and B working chambers of the servo valve under test are not connected, so that the servo valve under test is in the pressure test state. The oil in the oil tank 1 passes through the first filter 2, the second filter 3, the first motor pump group 14, the second motor pump group 15, the second check valve 16, the third check valve 17, the first check valve 5, the oil inlet filter 4, and the fifth solenoid valve 32 in sequence into the P port of the valve plate 26, and then into the servo valve under test. Since the A and B working chambers of the servo valve under test are in the closed or nearly closed state, the oil is mainly used to establish the pressure of each oil port, and no obvious external flow is formed. The first pressure sensor 37 detects the pressure at port P, the second pressure sensor 38 detects the pressure at port A, the third pressure sensor 39 detects the pressure at port T, and the fourth pressure sensor 40 detects the pressure at port B. The PC control terminal obtains the pressure characteristics of the servo valve under test based on the pressure changes at each port under different input currents. When the pressure test is completed or when pressure relief is required, the sixth solenoid valve 33 is energized, connecting the oil supply line and the return line. The system pressure is released through the pressure relief branch, and the oil returns to the oil tank 1 through the return line, preventing the servo valve and sensors under test from being under pressure for extended periods. The pressure characteristic test oil circuit is as follows: Figure 10As shown, the orange bold lines represent pipelines with oil flowing through them, the green bold lines represent pipelines without oil flowing through them, and these only represent the four pressure sensors testing four ports respectively. The blue bold line represents the system's pressure relief oil circuit. Because pressure stabilization during the pressure characteristic test primarily relies on oil return through the relief valve 27, port T is only used for oil return pressure detection and to receive any possible minor oil leaks; it is not the main oil return channel in this test mode. Figure 10 The return oil path was not marked in the middle;

[0063] (3) Internal leakage detection: The servo valve under test is installed on the valve plate 26, and all shut-off valves are kept in the open state. The first motor pump group 14 and the second motor pump group 15 are opened, so that the overflow valve 27, the second solenoid valve 29 and the fifth solenoid valve 32 are energized. The solenoid directional valve 31 is energized and switched to the right position. The A and B working chambers of the servo valve under test are not connected, forming an oil circuit with internal leakage oil as the main detection object. The oil in the oil tank 1 enters the oil port P of the valve plate 26 through the oil supply pipeline in sequence, and then enters the servo valve under test. When the A and B working chambers of the servo valve under test are in a closed or nearly closed state, there should be no obvious flow output under normal circumstances. If there are problems such as valve core wear, increased sealing gap, or valve port not closing tightly inside the servo valve under test, the leaked oil will enter the return oil line through the oil port T of valve plate 26, the right position oil line of solenoid directional valve 31, the second solenoid valve 29, and flow meter 6, and finally return to oil tank 1. During the test, flow meter 6 or second flow sensor 44 collects the leakage flow in the internal leakage return oil line. The internal leakage return oil line is as follows: Figure 14 As shown by the thick blue solid line, the PC control terminal determines whether the tested servo valve has an excessive internal leakage fault based on the leakage flow rate. The oil circuit involved in internal leakage detection is as follows: Figure 11 The orange section is shown in the middle.

[0064] (4) Dynamic frequency response detection: The servo valve under test is installed on the valve plate 26, and all shut-off valves are kept in the open state. The first motor pump group 14 and the second motor pump group 15 are opened, so that the overflow valve 27, the fifth solenoid valve 32, the seventh solenoid valve 34 and the eighth solenoid valve 35 are energized. The oil port A and oil port B of the servo valve under test are connected to the two chambers of the first hydraulic cylinder 20. At the same time, the second hydraulic cylinder 23 and the pressure reducing valve 36 are connected to the loading branch, forming a dynamic loading test circuit from the servo valve under test to the first hydraulic cylinder 20, then to the second hydraulic cylinder 23 and finally to the pressure reducing valve 36. The oil in the oil tank 1 passes through the first filter 2, the second filter 3, the first motor pump group 14, the second motor pump group 15, the second check valve 16, the third check valve 17, the first check valve 5, and the inlet. Oil filter 4, fifth solenoid valve 32 enters the oil port P of valve plate 26, and then enters the servo valve under test. The oil is output through oil ports A and B of the servo valve under test, and forms a dynamic loading test circuit through seventh solenoid valve 34, first hydraulic cylinder 20, eighth solenoid valve 35, pressure reducing valve 36, and second hydraulic cylinder 23. By changing the load through pressure reducing valve 36 and second hydraulic cylinder 23, the pressure difference environment of first hydraulic cylinder 20 during operation is changed. Different pressure values ​​are set for pressure reducing valve 36, and second hydraulic cylinder 23 forms different levels of constant load. When first hydraulic cylinder 20 moves, it will face different resistances, and the pressure difference between the two chambers will also be different. The characteristics of first hydraulic cylinder 20 under different pressure differences are tested, which characterizes the dynamic characteristics of the servo valve. The oil circuit involved in the dynamic frequency response test is as follows: Figure 12 The orange section shows the lines where the thick orange lines represent pipelines with oil flowing through them, and the thick green lines represent pipelines without oil flowing through them. This indicates that two pressure sensors are used to test the pressure in the two chambers of the second hydraulic cylinder 23, and one displacement sensor is used to test the piston rod displacement of the first hydraulic cylinder 20. The pressure values ​​at ports A, P, T, and B of the tested servo valve can be obtained by the first pressure sensor 37, the second pressure sensor 38, the third pressure sensor 39, and the fourth pressure sensor 40. The flow rates at ports A, T, and B of the tested servo valve are measured by the first flow sensor 43, the second flow sensor 44, and the third flow sensor 45. The displacement signal of the piston is collected by the displacement sensor 46 in the first hydraulic cylinder 20. The hydraulic oil returning to the oil tank 1 is cooled by the air-cooling device 11.

[0065] Online testing of the servo valve under test: Open the first shut-off valve 7, the second shut-off valve 8, the third shut-off valve 9, the fourth shut-off valve 10, the fifth shut-off valve 13, the sixth shut-off valve 18, the seventh shut-off valve 22, the eighth shut-off valve 24, and the ninth shut-off valve 25, and energize the fifth solenoid valve 32, the seventh solenoid valve 34, and the eighth solenoid valve 35. Place the servo valve under test on the valve plate 26, connect the oil ports A and B of the servo valve under test, and connect the loading branch containing the servo valve under test, the first hydraulic cylinder 20, the second hydraulic cylinder 23, and the pressure reducing valve 36. Adjust the opening pressure of the relief valve 27 to the pressure value of the servo valve under test when the hydraulic system is working normally, using the current signal given by the computer. After the first motor pump group 14 and the second motor pump group 15 are opened, they supply power to the servo valve under test. The hydraulic oil supplied to the online testing platform is purified from the oil tank 1 by the first filter 2 and the second filter 3. It then passes through the second check valve 16, the third check valve 17, the first check valve 5, the inlet filter 4, and the fifth solenoid valve 32 before entering port P of the valve plate 26. From the valve plate 26, it enters the servo valve under test. The oil is distributed from port P to ports A and B, and then enters the corresponding working chamber of the first hydraulic cylinder 20, driving the piston of the first hydraulic cylinder 20. The opening pressure of the relief valve 27 is adjusted by the current signal given by the computer to change the pressure of the oil supply line, simulating different actual working conditions. When the pressure of the oil supply line reaches the set pressure of the relief valve 27, excess oil flows back to the oil tank 1 through the relief valve 27 and the fifth shut-off valve 13, thereby maintaining a stable oil supply pressure. Simultaneously, the second hydraulic cylinder 23 is connected to the loading branch as an auxiliary loading execution unit, and the pressure reducing valve 36 is used to set the loading pressure of the second hydraulic cylinder 23. When the pressure in the loaded branch exceeds the set pressure of the pressure reducing valve 36, the excess oil flows back to the oil tank 1 through the pressure reducing valve 36 and the seventh shut-off valve 22, thereby creating a stable and adjustable load on the first hydraulic cylinder 20 from the second hydraulic cylinder 23. Online monitoring of the oil circuit is as follows: Figure 13 As shown in the bold orange line. The pressure values ​​of the working chambers A and B of the servo valve under test are obtained through the second pressure sensor 38 and the fourth pressure sensor 40. The flow values ​​of the oil ports A and B of the servo valve under test are measured by the first flow sensor 43 and the third flow sensor 45. The displacement sensor 46 collects the piston displacement signal of the first hydraulic cylinder 20. The air-cooling device 11 cools the hydraulic oil returning to the oil tank 1. At this time, the pressure and flow changes of the servo valve under test are monitored by the sensor monitoring component. After the information on pressure and flow changes is transmitted to the PC, it is compared and judged with the qualified data of the servo valve of this model by the fault diagnosis module. By monitoring the pressure, displacement signal and flow values ​​of the two chambers of the servo valve under test, as well as the flow values ​​of oil ports A and B, the performance status of the servo valve under test is accurately displayed and warning information and solutions are given.

[0066] The specific operation for testing the characteristics of the first hydraulic cylinder 20 under different pressure differentials is as follows: the first hydraulic cylinder 20 is used as the test execution response unit to characterize the output control effect of the servo valve under test. The second hydraulic cylinder 23 is used as an auxiliary loading execution unit. The pressure reducing valve 36 sets the load for the second hydraulic cylinder 23. The servo valve under test controls the oil inlet chamber of the first hydraulic cylinder 20 and the loading branch of the second hydraulic cylinder 23. The second hydraulic cylinder 23 acts on the first hydraulic cylinder 20 through a controllable load to change the working state of the first hydraulic cylinder 20 and obtain data under different working states.

[0067] In this embodiment, a Convolutional Neural Network (CNN) is used as the fault feature extraction model. Convolutional operations are used to automatically extract features from the pressure, flow, and displacement signals during the servo valve's operation, and a classification layer is used to identify different fault states. Because CNNs have strong nonlinear feature extraction capabilities, they can effectively mine the correlation features between multi-parameter signals, providing a data foundation for subsequent fault diagnosis. The structure of the CNN used is as follows: Figure 6 As shown.

[0068] To improve the parameter optimization capability of CNN models and avoid performance degradation caused by manual parameter selection, this embodiment introduces the Whale Optimization (WOA) algorithm to optimize key structural parameters of CNNs. A WOA-CNN prediction model is proposed to improve the global search capability and convergence speed of CNNs, obtaining the globally optimal parameters of the CNN network model and corresponding optimal fitness values. The WOA-CNN algorithm flow is as follows: Figure 7 As shown.

[0069] Using WOA to measure the number of convolutional kernels in a convolutional layer ,size Batch size Learning rate To optimize, the four parameters mentioned above are mapped to the spatial vector position of each individual whale. The position of the head whale is:

[0070] ;

[0071] in, Indicates the first The CNN parameter combination corresponding to each individual whale.

[0072] The specific steps are as follows:

[0073] S1, initialize the whale population location, and iteratively update the CNN parameter combination according to the WOA location update mechanism;

[0074] S2, build a network model based on the CNN parameter combination corresponding to the current individual whale, train it using pressure, flow and displacement samples collected by the fault diagnosis device, and calculate the classification accuracy of the model on the validation set;

[0075] S3 uses the classification error as the fitness function to evaluate the performance of the current CNN parameter combination and update the current optimal whale position;

[0076] ;

[0077] in, This represents the fault classification accuracy of the CNN model on the validation set. The smaller the fitness value, the better the performance of the corresponding CNN parameter combination.

[0078] S4, determine if the iteration count meets the termination condition. If not, continue to update the whale's position and recalculate the fitness value; if it does, output the optimal parameter combination.

[0079] S5 uses the obtained optimal number of convolutional kernels, kernel size, batch size, and learning rate to reconstruct the CNN model and apply it to servo valve fault state recognition.

[0080] Taking a set of measured data from the online testing process as an example, the online testing adopts... Figure 3The simulation model shown uses an online detection and fault diagnosis method for the servo valve to simulate its actual operating state. The PC control terminal adjusts the system's working pressure and load state, and collects the operating parameters of the servo valve and actuator. In this set of data, the pressure in the left chamber of the servo valve is 49.1 bar, the pressure in the right chamber of the servo valve is 210 bar, the flow rate at port A is 133.7 L / min, the flow rate at port B is 65.0 L / min, the valve core displacement is 0.5 mm, and the hydraulic cylinder piston rod displacement is ±10 mm. These data correspond to the pressure, flow rate, and displacement monitoring parameters in the fault diagnosis device. The pressure in the left and right chambers of the servo valve corresponds to the pressures in working chambers A and B of the servo valve under test, respectively, and can be collected by the second pressure sensor 38 and the fourth pressure sensor 40. The flow rates at port A and port B correspond to the flow rates at ports A and B during the actual operation of the servo valve under test, respectively, and can be collected by the first flow sensor 43 and the third flow sensor 45. The valve core displacement is used to characterize the valve core position feedback of the servo valve under test. The displacement of the hydraulic cylinder piston rod corresponds to the execution response of the first hydraulic cylinder 20 and is collected by the displacement sensor 46. The above pressure, flow rate, and displacement data are transmitted to the PC control terminal via the data acquisition card and input into the WOA-CNN fault diagnosis model for processing. In the PC control terminal, the data preprocessing unit first filters, normalizes, and aligns the collected left and right chamber pressures, flow rates at port A and port B, valve core displacement, and hydraulic cylinder piston rod displacement to form an online detection sample matrix.

[0081] ;

[0082] in, This indicates the pressure in the left chamber of the servo valve. This indicates the pressure in the right chamber of the servo valve. This indicates the flow rate at port A. This indicates the flow rate at port B. Indicates valve core displacement. This indicates the displacement of the hydraulic cylinder piston rod.

[0083] The online detection sample matrix serves as the input data for the WOA-CNN fault diagnosis model. In the WOA-CNN model, the CNN is used to automatically extract fault features from the aforementioned pressure, flow, and displacement samples, including variations in the pressure difference between the left and right chambers, flow asymmetry at port A or port B, valve core displacement deviation, and hydraulic cylinder displacement response hysteresis. The WOA algorithm is used to globally optimize the key parameters of the CNN model, enabling the CNN to achieve better fault classification performance.

[0084] Finally, the WOA-CNN model described above was used to train and test the online monitoring data, and the final training set results were then used. Figure 4 Test set results Figure 5 The results show that the accuracy rate of the prediction results on the training set is 97.74%, and the accuracy rate of the prediction results on the test set is 95.75%. According to the prediction results on the test set, the servo valve has slight wear and can be used normally.

[0085] The above description is merely a preferred embodiment of the present invention and is illustrative rather than restrictive. Those skilled in the art will understand that many changes, modifications, and even equivalents can be made within the spirit and scope defined by the claims of the present invention, all of which will fall within the protection scope of the present invention.

Claims

1. A servo valve fault diagnosis device capable of both offline and online operation, characterized in that, The test platform includes a test platform and a PC control terminal. The test platform includes an oil tank (1), a valve plate (26), a first hydraulic cylinder (20), a second hydraulic cylinder (23), a solenoid directional valve (31), a sensor monitoring component, and a pipeline control component. The valve plate (26) and the solenoid directional valve (31) each have four oil ports: P, A, T, and B. The oil port P of the solenoid directional valve (31) is connected to the oil port T of the valve plate (26), and the oil port T of the solenoid directional valve (31) is connected to the oil port A. The oil port A of the 31) is connected to the oil port B of the valve plate (26). The oil port B of the electromagnetic reversing valve (31) is connected to the oil ports A and B of the valve plate (26). The oil port P of the valve plate (26) is connected to the oil tank (1) through a pipeline. The pipeline control component and the sensor monitoring component are set on the pipelines of the four oil ports P, A, T and B of the valve plate (26) and the electromagnetic reversing valve (31). The first hydraulic cylinder (20) and the second hydraulic cylinder (23) are connected in series on the pipeline between the oil ports A and B of the valve plate (26).

2. The servo valve fault diagnosis device capable of both offline and online operation as described in claim 1, characterized in that, The test platform also includes an inlet filter (4), a flow meter (6), a level gauge (21), a first filter (2), a second filter (3), a first motor pump group (14), a second motor pump group (15), an accumulator (19), an overflow valve (27), a first check valve (5), a second check valve (16), a third check valve (17), and a fourth check valve (12). The flow meter (6) is installed on the pipeline between the oil port A and the oil port B of the valve plate (26). The inlet filter (4) is installed on the oil port P of the valve plate (26). The flow meter (6) is installed on the oil port B of the solenoid directional valve (31). The first filter (2), the second filter (3), the first filter (4), the second filter (5), the second filter (6), the third filter (21), the fourth filter (3), the fifth filter (4), the sixth filter (5), the seventh filter (6), the eighth filter (7), the ninth filter (8), the ellipse valve (9), the ellipse valve (10), the ellipse valve (11), the ellipse valve (12), the ellipse valve (13), the ellipse valve (14), the ellipse valve (15), the accumulator (19), the overflow valve (27), the first check valve (5), the second check valve (16), the third check valve (17), and the fourth check valve (12). The filter (3) and the level gauge (21) are installed inside the oil tank (1). The first filter (2) is connected in sequence to the first motor pump group (14), the second check valve (16) and the accumulator (19). The second filter (3) is connected in sequence to the second motor pump group (15) and the third check valve (17). The overflow valve (27) is installed on the pipeline between the first check valve (5) and the oil tank (1). The first filter (2) and the second filter (3) are installed in parallel on the pipeline between the first check valve (5) and the overflow valve (27). The fourth check valve (12) is installed on the pipeline between the oil port T of the electromagnetic reversing valve (31) and the air-cooled device (11).

3. The servo valve fault diagnosis device capable of both offline and online operation as described in claim 2, characterized in that, The sensor monitoring assembly includes a first pressure sensor (37), a second pressure sensor (38), a third pressure sensor (39), a fourth pressure sensor (40), a first flow sensor (43), a second flow sensor (44), a third flow sensor (45), and a displacement sensor (46). The first pressure sensor (37), the second pressure sensor (38), the third pressure sensor (39), and the fourth pressure sensor (40) are respectively installed on the four oil ports P, A, T, and B of the valve plate (26). The first flow sensor (43), the second flow sensor (44), and the third flow sensor (45) are respectively installed on the three oil ports A, T, and B of the valve plate (26). The displacement sensor (46) is installed at one end of the piston rod of the first hydraulic cylinder (20).

4. The servo valve fault diagnosis device capable of both offline and online operation as described in claim 3, characterized in that, The pipeline control assembly includes a first solenoid valve (28), a second solenoid valve (29), a third solenoid valve (30), a solenoid directional valve (31), a fifth solenoid valve (32), a sixth solenoid valve (33), a seventh solenoid valve (34), an eighth solenoid valve (35), and a pressure reducing valve (36). The first solenoid valve (28) is located between port A and port B of the valve plate (26). The second solenoid valve (29) is located at port A of the solenoid directional valve (31). The third solenoid valve (30) is located in the pipeline between the second solenoid valve (29) and the third flow sensor (45). The fifth solenoid valve (32) is installed on the pipeline between the oil inlet filter (4) and the first pressure sensor (37). The sixth solenoid valve (33) is installed on the pipeline between the oil inlet filter (4) and the oil port T of the solenoid directional valve (31). The seventh solenoid valve (34) is installed on the pipeline between the first hydraulic cylinder (20) and the first flow sensor (43). The eighth solenoid valve (35) and the pressure reducing valve (36) are connected in series on the pipeline between the first hydraulic cylinder (20) and the second hydraulic cylinder (23). The pressure reducing valve (36) is connected to the oil tank (1) through the pipeline.

5. The servo valve fault diagnosis device capable of both offline and online operation as described in claim 4, characterized in that, The pipeline control assembly includes a first shut-off valve (7), a second shut-off valve (8), a third shut-off valve (9), a fourth shut-off valve (10), a fifth shut-off valve (13), a sixth shut-off valve (18), a seventh shut-off valve (22), an eighth shut-off valve (24), and a ninth shut-off valve (25). The first shut-off valve (7) is located on the pipeline connecting the oil port P of the valve plate (26) to the first pressure sensor (37). The second shut-off valve (8) is located on the pipeline connecting the oil port A of the valve plate (26) to the second pressure sensor (38). The third shut-off valve (9) is located on the pipeline connecting the oil port T of the valve plate (26) to the third pressure sensor (39). The fourth shut-off valve (7) is located on the pipeline connecting the oil port T of the valve plate (26) to the third pressure sensor (39). The stop valve (10) is installed on the pipeline connecting the oil port B of the valve plate (26) and the fourth pressure sensor (40). The fifth stop valve (13) is installed on the pipeline between the overflow valve (27) and the oil tank (1). The sixth stop valve (18) is installed on the pipeline between the accumulator (19) and the second check valve (16). The seventh stop valve (22) is installed on the pipeline between the pressure reducing valve (36) and the oil tank (1). The eighth stop valve (24) is installed on the pipeline between the second hydraulic cylinder (23) and the fifth pressure sensor (41). The ninth stop valve (25) is installed on the pipeline between the second hydraulic cylinder (23) and the sixth pressure sensor (42).

6. The servo valve fault diagnosis device capable of both offline and online operation as described in claim 1, characterized in that, The PC control system is equipped with a fault diagnosis module, which includes a data preprocessing unit, a feature extraction unit, and a state recognition unit. The data preprocessing unit is used to filter, normalize, and time-align the acquired multi-source signals. The feature extraction unit uses a convolutional neural network to extract features from the processed pressure, flow, and displacement time-series data. The state recognition unit optimizes the structural and training parameters of the CNN model based on the whale optimization algorithm to obtain an optimized WOA-CNN model.

7. A method for using the servo valve fault diagnosis device capable of both offline and online operation as described in any one of claims 1-6, characterized in that, Includes the following steps: S1 performs offline testing on the servo valve under test, including static characteristic testing and dynamic frequency response testing. Static characteristic testing is divided into flow rate, pressure and internal leakage characteristic testing. S2, perform online testing on the servo valve under test; S3. The data detected in steps S1 and S2 is transmitted to the PC control terminal. The optimized WOA-CNN model classifies and identifies the operating status of the servo valve under test, judges the performance status of the servo valve under test, and finally displays the analysis results on the screen of the PC control terminal, so that the user can intuitively see whether the servo valve under test has a fault and its performance status.

8. The servo valve fault diagnosis method capable of both offline and online operation as described in claim 7, characterized in that, The static characteristic detection in step S1 includes the following steps: S111, Flow characteristic detection: The servo valve under test is installed on the valve plate (26), and all shut-off valves are kept in the open state. The first motor pump group (14) and the second motor pump group (15) are turned on. The overflow valve (27), the first solenoid valve (28), the third solenoid valve (30) and the fifth solenoid valve (32) are adjusted to the energized state. The A and B working chambers of the servo valve under test are connected to form a flow test circuit. During the test, the oil in the oil tank (1) passes through the first filter (2), the second filter (3), the first motor pump group (14), the second motor pump group (15), the second check valve (16), and the third check valve (17) in sequence. 17) The first check valve (5), the oil inlet filter (4), and the fifth solenoid valve (32) enter the oil port P of the valve plate (26) and then enter the servo valve under test. The oil is output through the oil port A and oil port B of the servo valve under test, and flows through the first solenoid valve (28), the third solenoid valve (30) and the corresponding pipeline through the first flow sensor (43), the third flow sensor (45) and the flow meter (6). During the detection process, the first flow sensor (43) and the third flow sensor (45) collect the flow rate of oil port A and oil port B. The PC control terminal obtains the flow characteristics of the servo valve under test according to the relationship between the input current and the output flow rate. S112, Pressure characteristic detection: The servo valve under test is installed on the valve plate (26), and all shut-off valves are kept in the open state. The first motor pump group (14) and the second motor pump group (15) are opened, so that the overflow valve (27) and the fifth solenoid valve (32) are energized. The A and B working chambers of the servo valve under test are not connected, so that the servo valve under test is in the pressure detection state. The oil in the oil tank (1) enters the P port of the valve plate (26) along the same path as in step S111, and then enters the servo valve under test. The pressure of the oil port P, oil port A, oil port T and oil port B are detected by the first pressure sensor (37), the second pressure sensor (38), the third pressure sensor (39) and the fourth pressure sensor (40) respectively. The PC control terminal obtains the pressure characteristics of the servo valve under test according to the pressure change of each oil port under different input currents. S113, Internal Leakage Characteristic Detection: Install the servo valve under test on the valve plate (26), keep all shut-off valves in the open state, turn on the first motor pump group (14) and the second motor pump group (15), adjust the overflow valve (27), the second solenoid valve (29), and the fifth solenoid valve (32) to the energized state, the solenoid directional valve (31) is energized and switched to the right position, the A and B working chambers of the servo valve under test are not connected, forming an oil circuit with internal leakage oil as the main detection object, and the oil in the oil tank (1) is processed in the same way as in step S111. The path enters the oil port P of the valve plate (26) and then enters the servo valve under test. If there is a leakage problem inside the servo valve under test, the leaked oil will enter the return oil line through the oil port T of the valve plate (26), the right position oil line of the solenoid directional valve (31), the second solenoid valve (29) and the flow meter (6), and finally return to the oil tank (1). During the detection process, the flow meter (6) or the second flow sensor (44) collects the leakage flow in the internal leakage return oil line. The PC control terminal judges whether the servo valve under test has an internal leakage over-limit fault based on the leakage flow.

9. The servo valve fault diagnosis method capable of both offline and online operation as described in claim 7, characterized in that, The dynamic frequency response in step S1 includes the following steps: S121, the servo valve under test is installed on the valve plate (26), and all shut-off valves are kept in the open state. The first motor pump group (14) and the second motor pump group (15) are turned on, so that the overflow valve (27), the fifth solenoid valve (32), the seventh solenoid valve (34) and the eighth solenoid valve (35) are energized. The oil port A and oil port B of the servo valve under test are connected to the two chambers of the first hydraulic cylinder (20). At the same time, the second hydraulic cylinder (23) and the pressure reducing valve (36) are connected to the loading branch, forming a dynamic loading test circuit from the servo valve under test to the first hydraulic cylinder (20), then to the second hydraulic cylinder (23) and finally to the pressure reducing valve (36). S122, the oil in the tank (1) enters the oil port P of the valve plate (26) in sequence through the same path as in step S111, and then enters the servo valve under test. The oil is output through the oil port A and oil port B of the servo valve under test, and passes through the seventh solenoid valve (34), the first hydraulic cylinder (20), the eighth solenoid valve (35), the pressure reducing valve (36), and the second hydraulic cylinder (23) to form a dynamic loading test circuit. The load is changed by the pressure reducing valve (36) and the second hydraulic cylinder (23), thereby changing the pressure difference environment when the first hydraulic cylinder (20) is working. S123, set different pressure values ​​for pressure reducing valve (36), and the second hydraulic cylinder (23) forms different levels of constant load. When the first hydraulic cylinder (20) moves, it will face different resistances, and the pressure difference between the two chambers will also be different. Test the characteristics of the first hydraulic cylinder (20) under different pressure differences, which is characterized by the dynamic characteristics of the servo valve. The first pressure sensor (37), the second pressure sensor (38), the third pressure sensor (39) and the fourth pressure sensor (40) can obtain the pressure values ​​of the four oil ports A, P, T and B of the servo valve under test at this time. S124, the flow values ​​of the three oil ports A, T and B of the servo valve under test are measured by the first flow sensor (43), the second flow sensor (44) and the third flow sensor (45), the displacement signal of the piston is collected by the displacement sensor (46) in the first hydraulic cylinder (20), and the hydraulic oil in the return oil tank (1) is cooled by the air cooling device (11).

10. The servo valve fault diagnosis method capable of both offline and online operation as described in claim 7, characterized in that, Step S2 includes the following steps: S21, keep all shut-off valves in the open state, so that the fifth solenoid valve (32), the seventh solenoid valve (34) and the eighth solenoid valve (35) are energized, place the servo valve under test on the valve plate (26), connect the oil port A and oil port B of the servo valve under test, and connect the loading branch where the servo valve under test, the first hydraulic cylinder (20), the second hydraulic cylinder (23) and the pressure reducing valve (36) are located; S22, the opening pressure of the relief valve (27) is adjusted to the pressure value of the servo valve under test when the hydraulic system is working normally by means of the given current signal. After the first motor pump group (14) and the second motor pump group (15) are opened, they supply oil to the online detection platform. At this time, the oil enters the oil port P of the valve plate (26) through the same path as in step S111, and enters the servo valve under test through the valve plate (26). The oil is distributed from the oil port P to the oil port A and the oil port B, and enters the corresponding working chamber of the first hydraulic cylinder (20), pushing the piston of the first hydraulic cylinder (20) to move. The opening pressure of the relief valve (27) is adjusted by means of the current signal given by the computer, thereby changing the oil supply line pressure to simulate different actual working states. S23, when the oil supply line pressure reaches the set pressure of the relief valve (27), the excess oil flows back to the oil tank (1) through the relief valve (27) and the fifth shut-off valve (13), thereby maintaining the oil supply pressure stable. At the same time, the second hydraulic cylinder (23) is connected to the loading branch as an auxiliary loading execution unit. The pressure reducing valve (36) is used to set the loading pressure of the second hydraulic cylinder (23). When the loading branch pressure exceeds the set pressure of the pressure reducing valve (36), the excess oil flows back to the oil tank (1) through the pressure reducing valve (36) and the seventh shut-off valve (22), thereby making the second hydraulic cylinder (23) form a stable and adjustable load on the first hydraulic cylinder (20). S24, after a stable load is formed, the pressure and flow changes of the tested servo valve are monitored by the sensor monitoring component. The information on pressure and flow changes is transmitted to the PC and compared with the qualified data of the tested servo valve by the fault diagnosis module. By monitoring the pressure, displacement signal and flow values ​​of port A and port B of the tested servo valve, the performance of the tested servo valve is accurately displayed and warning information and solutions are given.

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