On-line and off-line combined hydraulic pump test platform

Abstract

The invention discloses an on-line and off-line combined hydraulic pump test platform, relates to the technical field of hydraulic pump detection and fault diagnosis, combines an off-line detection mode and an on-line detection mode, avoids time and labor consumption and equipment damage caused by frequent disassembly and assembly of a hydraulic pump in traditional off-line detection, and improves the detection efficiency. And the limitation that the online detection is difficult to comprehensively evaluate the performance and accurately diagnose the fault is overcome, the detection efficiency and convenience are greatly improved, and the downtime and maintenance cost of the equipment are reduced. Accurate performance data, such as a flow-pressure characteristic curve, volume efficiency, mechanical efficiency and the like, can be obtained in a relatively ideal environment through offline detection; physical quantities such as pressure, flow, temperature, vibration and the like can be monitored in real time through online detection, comprehensive evaluation on the comprehensive performance of the hydraulic pump is achieved through combination of the two, and deep performance indexes such as volume efficiency dynamic changes under different working conditions and the mechanical wear trend under the complex load condition can be accurately measured.

Description

Technical Field

[0001] The invention relates to the field of hydraulic pump detection technology and fault diagnosis technology, and in particular to an online and offline combined hydraulic pump test platform. Background Art

[0002] In the modern industrial field, hydraulic pumps, as the core power components of hydraulic systems, are widely used in many key industries such as engineering machinery, aerospace, shipbuilding, and the automotive industry. Their performance and operational reliability are directly related to the working efficiency and safety of the entire hydraulic system and even the entire set of equipment.

[0003] With the continuous improvement of industrial automation and the increasingly stringent requirements for production continuity, the demand for performance control and fault prevention of hydraulic pumps is growing. Traditionally, the detection of hydraulic pump performance mainly relies on offline detection methods. Offline detection usually requires the hydraulic pump to be disassembled from the actual working system and transported to a special testing laboratory. Various professional testing instruments, such as high-precision flow meters, pressure sensors, torque meters, etc., are used to simulate its working conditions for performance parameter measurement. Although this method can obtain more accurate performance data in a relatively ideal and controllable environment, such as the flow-pressure characteristic curve, volumetric efficiency, mechanical efficiency and other key indicators of the pump, it has many significant disadvantages. On the one hand, the process of disassembling and reinstalling the hydraulic pump is time-consuming and labor-intensive, which will not only cause long-term equipment downtime, leading to production interruptions and huge economic losses, but also cause the downtime cost to be difficult to estimate for some large production lines or industrial scenarios with extremely high continuity requirements; on the other hand, frequent disassembly and installation operations can easily cause additional mechanical damage to the hydraulic pump and its connecting parts, affecting the service life and original performance of the pump, and may even introduce new fault hazards.

[0004] At the same time, during actual operation, hydraulic pumps face complex and changeable working conditions, including different load shocks, oil temperature fluctuations, changes in the degree of medium contamination, etc. These actual working conditions are difficult to fully and accurately simulate in an offline detection environment, resulting in a certain deviation between the offline detection results and the actual performance of the hydraulic pump in the real working system. It is impossible to reflect the current working status of the hydraulic pump in real time, which is not conducive to timely detection of potential faults and taking preventive measures.

[0005] In recent years, with the rapid development of sensor technology, data acquisition technology, computer processing power and network communication technology, online detection technology has emerged. By installing various sensors at the hydraulic pump operation site, real-time physical quantities such as pressure, flow, temperature, vibration, etc. during its operation are continuously collected, and the data is transmitted to the monitoring terminal by wired or wireless transmission. The data is analyzed by using pre-set algorithms and models, and the operating status of the hydraulic pump can be monitored in real time, and whether there are signs of performance degradation or failure can be preliminarily determined. Online detection greatly makes up for the lack of real-time performance of offline detection, and provides strong support for ensuring the continuous operation of equipment. However, the existing online detection system often focuses on the monitoring of a single operating parameter, lacks the ability to comprehensively evaluate the all-round performance of the hydraulic pump, and is difficult to accurately determine deep-level performance indicators such as the dynamic changes of volumetric efficiency under different working conditions and the mechanical wear trend under complex load conditions; moreover, most online detection schemes have limited diagnostic accuracy in the fault diagnosis link, and can usually only identify more common and typical fault modes. For some complex faults and early weak faults caused by multi-factor coupling, it is difficult to accurately locate and qualitatively analyze them, and it is difficult to provide detailed and reliable decision-making basis for subsequent repair and maintenance.

[0006] In summary, both traditional offline detection and current online detection methods have their own limitations in the field of hydraulic pump performance detection and fault diagnosis, and it is difficult to meet the modern industry's demand for efficient, accurate, real-time and comprehensive detection and diagnosis of hydraulic pumps. Therefore, it is urgent to develop a comprehensive test bench and method that can integrate the advantages of offline and online detection, and integrate comprehensive performance detection and high-precision fault diagnosis functions, in order to fill this technical gap, improve the maintenance and management level of hydraulic pumps, and ensure the stable and reliable operation of industrial production. Summary of the invention

[0007] The present invention provides a comprehensive test bench and method for offline and online performance detection and fault diagnosis of a hydraulic pump, which solves the problem that most online detection test benches on the market can usually 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. It also solves the problem that the offline detection test bench is time-consuming and labor-intensive to detect the hydraulic pump, and may introduce new impurities and cause certain wear on the hydraulic pump.

[0008] In order to solve the above technical problems, the present invention provides an online and offline combined hydraulic pump test platform, including an experimental platform, a test pump and a PC control cabinet, the PC control cabinet including a PC control end, and a fault diagnosis module being provided in the PC control end; the test platform includes an offline detection experimental platform and an online detection experimental platform; the offline detection experimental platform forms a circuit with a test pump and a proportional relief valve in series with an oil tank, the test pump is driven by a motor, a first oil product backflow prevention device and a third stop valve are provided on the connecting oil circuit between the test pump and the oil tank, a pressure detection device is provided on the connecting oil circuit between the test pump and the proportional relief valve, and a first flow sensor is provided on the connecting oil circuit between the proportional relief valve and the oil tank; the first flow sensor and the pressure detection device are electrically connected to the fault diagnosis module; the online detection experimental platform includes all hydraulic components of the offline detection experimental platform, and further includes a temperature sensor and a vibration sensor, the temperature sensor is connected in series in the connecting oil circuit between the test pump and the proportional relief valve, and the vibration sensor is attached to the housing of the test pump; the temperature sensor and the vibration sensor are electrically connected to the fault diagnosis module.

[0009] In some embodiments, the test platform also includes a hydraulic pump leakage test unit, which includes a second flow sensor, which is connected in series in the oil circuit connecting the test pump and the oil tank, a filter is provided between the test pump and the second flow sensor, and a fourth one-way valve is provided between the second flow sensor and the oil tank.

[0010] In some embodiments, the pressure detection device includes a pressure sensor and a pressure gauge, a third one-way valve is provided on the connecting oil circuit between the test pump and the proportional relief valve, a first one-way valve and a second one-way valve are provided in parallel on the connecting oil circuit between the third one-way valve and the proportional relief valve, the oil outlet of the first one-way valve is connected to the pressure sensor, a first stop valve is provided on the connecting oil circuit between the first one-way valve and the pressure sensor, the oil outlet of the second one-way valve is connected to the pressure gauge, and a second stop valve is provided on the connecting oil circuit between most of the second one-way valves and the pressure gauges.

[0011] In some embodiments, a second oil backflow prevention device and a third oil backflow prevention device are provided in the oil circuit connecting the first flow sensor and the oil tank, and the second oil backflow prevention device and the third oil backflow prevention device are connected in parallel in the oil circuit.

[0012] In some embodiments, the oil tank is provided with a thermometer, an air filter, a liquid level gauge, and a drain valve.

[0013] The present invention provides a method for using an online and offline combined hydraulic pump test platform, which specifically includes the steps of using an offline detection experimental platform and the steps of using an online detection experimental platform: The steps of using the offline detection experimental platform:

[0014] S1: Turn on the motor, open the first stop valve, the second stop valve, and the third stop valve, and the tested pump starts to work, providing pressurized oil to the main oil circuit to start the offline detection experimental platform;

[0015] S2: Control the opening pressure of the proportional relief valve through the PC control terminal. By adjusting the opening pressure of the proportional relief valve, simulate different working conditions of the tested pump and provide different pressure conditions for subsequent tests.

[0016] S3: monitor the pressure and flow changes of the tested pump through the pressure sensor, the pressure gauge and the first flow sensor;

[0017] S4: The monitored pressure and flow data are transmitted to the fault diagnosis module, which analyzes and processes the received data, uses the preset diagnosis rules and algorithms, determines the performance status of the tested pump, and finally displays the analysis results on the screen of the PC control terminal, so that the user can intuitively check whether the tested pump has faults and the performance status;

[0018] Steps for using the online detection experimental platform:

[0019] S5: Start the motor, open the first stop valve, the second stop valve, and the third stop valve, and the tested pump starts to work, providing pressurized oil to the main oil circuit to start the online detection experimental platform;

[0020] S6: The PC control terminal outputs a current signal, which accurately controls the opening pressure of the proportional relief valve, simulates various working states of the tested pump, and provides the required working conditions for the online detection experiment;

[0021] S7: The pressure sensor continuously monitors the pressure of the tested pump and provides important pressure data for fault diagnosis. The first flow sensor continuously monitors the flow of the tested pump and updates the flow data in real time. The temperature sensor measures the working temperature of the tested pump in real time and obtains the temperature information of the tested pump during operation. The vibration sensor is attached to the outer casing of the tested pump to monitor the vibration frequency of the tested pump and reflect the operating status of the tested pump from the vibration aspect.

[0022] S8: The pressure, flow, temperature, vibration frequency and other data obtained by S7 are transmitted to the fault diagnosis module. The fault diagnosis module conducts a comprehensive analysis of the data from these different sensors based on the preset diagnosis rules and algorithms, and finally accurately displays the comprehensive analysis results on the screen of the PC control terminal, helping users to determine whether the test pump is operating normally, accurately identify various possible fault problems, and provide users with a more comprehensive test pump performance evaluation and fault judgment basis.

[0023] Compared with the related art, the online and offline combined hydraulic pump testing platform provided by the present invention has the following beneficial effects:

[0024] The present invention provides an online and offline combined hydraulic pump test platform, which combines offline and online detection methods, avoids the time-consuming and labor-intensive equipment damage caused by frequent disassembly and installation of hydraulic pumps in traditional offline detection, and overcomes the limitation that online detection is difficult to comprehensively evaluate performance and accurately diagnose faults, greatly improves detection efficiency and convenience, and reduces equipment downtime and maintenance costs. Offline detection can obtain accurate performance data such as flow-pressure characteristic curve, volumetric efficiency, mechanical efficiency, etc. under relatively ideal conditions; online detection can monitor physical quantities such as pressure, flow, temperature, vibration, etc. in real time. The combination of the two realizes a comprehensive evaluation of the all-round performance of the hydraulic pump, and can accurately measure the dynamic changes of volumetric efficiency under different working conditions, the mechanical wear trend under complex load conditions, and other deep-level performance indicators. Rich data is collected through a variety of sensors and transmitted to the fault diagnosis module. Comprehensive analysis is performed according to preset diagnostic rules and algorithms, which can accurately locate and qualitatively analyze complex faults and early weak faults caused by multi-factor coupling, provide detailed and reliable decision-making basis for subsequent repair and maintenance, and effectively improve the reliability and service life of the hydraulic pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the hydraulic pump test principle of the present invention;

[0026] Figure 2 The overall structure of the present invention is shown in FIG. Figure 1 ;

[0027] Figure 3 The overall structure of the present invention is shown in FIG. Figure 2 ;

[0028] Figure 4 It is a schematic diagram of the process of the present invention;

[0029] Figure 5 It is a schematic diagram of the simulation model principle of the present invention;

[0030] Figure 6 It is a schematic diagram of the training set results of the present invention;

[0031] Figure 7 It is a schematic diagram of the test set results of the present invention.

[0032] Numbers in the figure: 1. pressure sensor; 2. pressure gauge; 31. first stop valve; 32. second stop valve; 33. third stop valve; 41. first one-way valve; 42. second one-way valve; 43. third one-way valve; 44. fourth one-way valve; 5. proportional relief valve; 61. first flow sensor; 62. second flow sensor; 7. test pump; 8. motor; 9. filter; 101. first oil backflow prevention device; 102. second oil backflow prevention device; 103. third oil backflow prevention device; 11. thermometer; 12. air filter; 13. liquid level gauge; 14. drain valve; 15. oil tank; 16. temperature sensor; 17. vibration sensor; 18. current signal; 19. bracket; 20. base; 21. PC control cabinet. DETAILED DESCRIPTION

[0033] This embodiment provides an online and offline combined hydraulic pump test platform, including a PC control terminal, a hydraulic pump offline and an online experimental platform. The PC terminal controls the hydraulic pump of the experimental bench through a programmable controller; the PC terminal controls the experimental bench, displays and stores the experimental data. The experimental bench tests the performance of the hydraulic pump according to the latest national testing standards. The signals of the sensors of the entire experimental bench are sent to the PC terminal through a data acquisition card. The PC terminal is equipped with a fault diagnosis module, which can perform fault diagnosis on the tested pump. The present invention is further elaborated below in conjunction with specific embodiments.

[0034] Example

[0035] like Figure 2-3 As shown, the present invention includes a base 20 and a bracket 19 fixedly mounted on the base 20, a motor 8, a PC control cabinet 21, and an oil tank 15 are arranged on the base 20, a proportional relief valve 5 is arranged on the bracket 19, and a second oil backflow prevention device 102 and a third oil backflow prevention device 103 are arranged on the bracket 19. The PC control cabinet 21 includes a PC control terminal, and a fault diagnosis module is arranged in the PC control terminal.

[0036] like Figure 1 As shown, the present invention also includes a test platform, which includes an offline detection experimental platform and an online detection experimental platform; the offline detection experimental platform forms a circuit by connecting the tested pump 7 and the proportional relief valve 5 in series with the oil tank 15, the tested pump 7 is driven by the motor 8, a first oil product backflow prevention device 101 and a third stop valve 33 are provided on the connecting oil circuit between the tested pump 7 and the oil tank 15, a pressure detection device is provided on the connecting oil circuit between the tested pump 7 and the proportional relief valve, and a first flow sensor 61 is provided on the connecting oil circuit between the proportional relief valve 5 and the oil tank 15. The online detection experimental platform includes all the hydraulic components of the offline detection experimental platform, and also includes a temperature sensor 16 and a vibration sensor 17, the temperature sensor 16 is connected in series in the connecting oil circuit between the tested pump 7 and the proportional relief valve 5, and the vibration sensor 17 is attached to the outer shell of the tested pump 7.

[0037] The test platform also includes a hydraulic pump leakage test unit, which includes a second flow sensor 62. The second flow sensor 62 is connected in series to the connecting oil line between the test pump 7 and the oil tank 15. A filter 9 is provided between the test pump 7 and the second flow sensor 62. A fourth one-way valve 44 is provided between the second flow sensor 62 and the oil tank 15.

[0038] The pressure detection device includes a pressure sensor 1 and a pressure gauge 2. A third one-way valve 43 is provided on the connecting oil circuit between the test pump 7 and the proportional relief valve 5. A first one-way valve 41 and a second one-way valve 42 are provided in parallel on the connecting oil circuit between the third one-way valve 43 and the proportional relief valve 5. The oil outlet of the first one-way valve 41 is connected to the pressure sensor 1. A first stop valve 31 is provided on the connecting oil circuit between the first one-way valve 41 and the pressure sensor 1. The oil outlet of the second one-way valve 42 is connected to the pressure gauge 2. A second stop valve 32 is provided on the connecting oil circuit between the majority of the second one-way valves 42 and the pressure gauge 2.

[0039] The oil circuit connecting the first flow sensor 61 and the oil tank 15 is provided with a second oil backflow prevention device 102 and a third oil backflow prevention device 103, which are connected in parallel in the oil circuit. The oil backflow prevention device can prevent oil from flowing back, and also has the effect of buffering vibration and filtering impurities.

[0040] The oil tank 15 is provided with a thermometer 11 , an air filter 12 , a liquid level gauge 13 , and a drain valve 14 .

[0041] The algorithm uses a convolutional neural network (WOA-CNN) optimized based on the whale algorithm, and uses WOA to adjust the number of convolution kernels k in the two convolutional layers. 1 , k 2 , size s 1 、s 2 , training batch batch, learning rate η are optimized, and the above 6 parameters are mapped into the spatial vector position of each individual whale. The position of the nth whale is:

[0042] x n =(k 1n , k 2n ,s 1n ,s 2n , batch n , η n )

[0043] Whales can perform random searches based on each other's positions. When |A|≥1, a whale x is randomly selected from the group. rand (t) is used as the local optimal position and used to update the positions of other whales. The replacement formula is:

[0044] x n (t+1)=x rand (t)-A·|C·x rand (t)-x n (t)|

[0045] In the WOA algorithm, each whale moves towards the location of the prey, and the whale group updates the prey information. The final position of the prey is the individual with the best position in the whale group. At this time, the position of the prey is used as the global optimal parameter of the CNN network structure, corresponding to the optimal fitness value.

[0046] Since each whale x i =(k 1i , k 2i ,s 1i ,s 2i , batch i , η i ) has different spatial positions, that is, the structural parameters of CNN will change each time it is trained. For different CNN network structural parameters, the same training set and test set are used for training and testing, where the training set is for known fault category labels and the test set is for unknown labels. The output layer of CNN uses the Softmax function to convert the output signal into a distribution with a probability sum of 1, and calculates the average loss value of the i-th iteration. Finally, after N iterative optimization operations, the whale group finds the generation with the smallest average loss value, which corresponds to the global optimal whale, that is, the prey position. The global optimal whale x is obtained n =(k 1n , k 2n ,s 1n ,s 2n , batch n , η n ), the CNN model is reconstructed with the optimal number, size, training batch, learning rate and other six parameters, and the training set is used for training and the test set is used for testing. The test set test results output at this time represent the degree of overlap between the four parameters of hydraulic pump pressure, flow, temperature and vibration frequency and the sample data in the national standard database.

[0047] Working principle: Turn on the motor 8, and the tested hydraulic pump starts to work, providing pressurized oil to the main oil circuit.

[0048] 1. Offline detection and fault diagnosis of pumps

[0049] The off-line detection unit of the hydraulic pump can be obtained by opening the first stop valve 31, the second stop valve 32, and the third stop valve 33. The opening pressure of the proportional relief valve 5 is adjusted. When the motor 8 is powered on, the tested pump 7 is driven to supply oil to the off-line detection platform. At this time, the first oil backflow prevention device 101 purifies the hydraulic oil from the oil tank 15. The pressure sensor 1 and the pressure gauge 2 can obtain the pressure value of the oil outlet of the tested pump 7 at this time and compare them. The first flow sensor 61 and the second flow sensor 62 respectively measure the outlet flow and the leakage oil port flow of the tested pump 7. The second oil backflow prevention device 102 and the third oil backflow prevention device 103 purify the return oil. By changing the pressure value of the proportional relief valve 5 for many times, different pressure values ​​and flow values ​​can be read out through the pressure sensor 1, the pressure gauge 2 and the first flow sensor 61, so as to obtain the pressure flow curve of the tested pump 7. After the fault information is transmitted to the PC end, it is diagnosed by the fault diagnosis module. By monitoring the pressure flow value of the tested pump 7, the performance of the tested pump 7 is accurately displayed and warning information and solutions are given.

[0050] 2. Online detection and fault diagnosis of pumps

[0051] The online detection unit of the hydraulic pump can be obtained by opening the first stop valve 31, the second stop valve 32 and the third stop valve 33. The opening pressure of the proportional relief valve 5 is adjusted to the pressure value of the test pump 7 when the hydraulic system is working normally through the current signal 18 given by the computer. When the motor 8 is energized, the test pump 7 is driven to supply oil to the online detection platform. At this time, the first oil backflow prevention device 101 purifies the hydraulic oil from the oil tank 15, the first flow sensor 61 and the second flow sensor 62 respectively measure the outlet flow and the leakage oil port flow of the test pump 7, and the second oil backflow prevention device 102 and the third oil backflow prevention device 103 purify the return oil. At this time, the pressure value and flow value of the test pump 7 can be read out by the pressure sensor 1, the pressure gauge 2 and the first flow sensor 61 respectively, and the temperature value and vibration frequency value of the test pump 7 at this time can be read out by the temperature sensor 16 and the vibration sensor 17 respectively. After the fault information is transmitted to the PC end, it is compared and judged with the information of the test pump 7 of this model by using the fault diagnosis module. By monitoring the pressure, flow, temperature and frequency values ​​of the test pump 7, the performance of the test pump 7 is accurately displayed and warning information and solutions are given.

[0052] 3. Pump internal leakage test and fault diagnosis

[0053] The internal leakage detection unit of the hydraulic pump can be obtained by opening the third stop valve 33 and closing the third one-way valve 43. When the motor 8 is powered on, it drives the tested pump 7 to supply oil to the internal leakage detection platform. The oil purified by the first oil backflow prevention device 101 enters the tested pump 7 and then enters the second flow sensor 62 after being filtered by the filter 9. At this time, the measurement value of the second flow sensor 62 is the internal leakage amount of the tested pump 7. When the internal leakage amount of the tested pump 7 exceeds the threshold, the fault diagnosis module displays an excessive internal leakage fault warning message.

[0054] 4. Example of online detection of pumps

[0055] This online monitoring adopts Figure 5 The simulation model principle shown in the figure is to adjust the pressure of the hydraulic pump to 35MPa, flow rate to 80L / min, temperature to 40℃, and frequency to 30Hz during normal operation through the operation method of working principle 2. After the above data is collected and transmitted through the data acquisition card, the appropriate algorithm is selected on the PC for data processing and the final training set results are Figure 6 , test set results Figure 7 It is shown that the comparison accuracy of the training set prediction results is 98.3%, and the comparison accuracy of the test set prediction results is 97.4%. According to the test set prediction results, it can be seen that the hydraulic pump has only a small amount of wear and does not affect normal use.

Claims

1. An online and offline combined hydraulic pump test platform, including an experimental platform, a tested pump and a PC control cabinet, characterized in that: The PC control cabinet comprises a PC control terminal, in which a fault diagnosis module is provided; The test platform includes an offline detection experimental platform and an online detection experimental platform; The offline detection experimental platform forms a loop by connecting a test pump and a proportional relief valve in series with an oil tank, the test pump is driven by a motor, a first oil backflow prevention device and a third stop valve are provided on the oil line connecting the test pump and the oil tank, a pressure detection device is provided on the oil line connecting the test pump and the proportional relief valve, and a first flow sensor is provided on the oil line connecting the proportional relief valve and the oil tank; The first flow sensor, the pressure detection device and the fault diagnosis module are electrically connected; The online testing experimental platform includes all hydraulic components of the offline testing experimental platform, and also includes a temperature sensor and a vibration sensor. The temperature sensor is connected in series in the connecting oil circuit between the tested pump and the proportional relief valve, and the vibration sensor is attached to the housing of the tested pump. The temperature sensor and the vibration sensor are electrically connected to the fault diagnosis module.

2. The online and offline combined hydraulic pump testing platform according to claim 1 is characterized in that: The test platform also includes a hydraulic pump leakage test unit, which includes a second flow sensor, which is connected in series to the oil circuit connecting the test pump and the oil tank, a filter is provided between the test pump and the second flow sensor, and a fourth one-way valve is provided between the second flow sensor and the oil tank.

3. The online and offline combined hydraulic pump testing platform according to claim 1, characterized in that: The pressure detection device includes a pressure sensor and a pressure gauge, a third one-way valve is provided on the connecting oil circuit between the test pump and the proportional relief valve, a first one-way valve and a second one-way valve are provided in parallel on the connecting oil circuit between the third one-way valve and the proportional relief valve, an oil outlet of the first one-way valve is connected to the pressure sensor, a first stop valve is provided on the connecting oil circuit between the first one-way valve and the pressure sensor, an oil outlet of the second one-way valve is connected to the pressure gauge, and a second stop valve is provided on the connecting oil circuit between most of the second one-way valves and the pressure gauges.

4. The online and offline combined hydraulic pump testing platform according to claim 1 is characterized in that: A second oil backflow prevention device and a third oil backflow prevention device are provided on the oil circuit connecting the first flow sensor and the oil tank, and the second oil backflow prevention device and the third oil backflow prevention device are connected in parallel in the oil circuit.

5. The online and offline combined hydraulic pump testing platform according to claim 1, characterized in that: The oil tank is provided with a thermometer, an air filter, a liquid level gauge and a drain valve.

6. A method for using the online and offline combined hydraulic pump testing platform as claimed in any one of claims 1 to 5, characterized in that: Specifically include the use steps of the offline detection experiment platform and the use steps of the online detection experiment platform; Steps for using the offline detection experimental platform: S1: Turn on the motor, open the first stop valve, the second stop valve, and the third stop valve, and the tested pump starts to work, providing pressurized oil to the main oil circuit to start the offline detection experimental platform; S2: Control the opening pressure of the proportional relief valve through the PC control terminal. By adjusting the opening pressure of the proportional relief valve, simulate different working conditions of the tested pump and provide different pressure conditions for subsequent tests. S3: monitor the pressure and flow changes of the tested pump through the pressure sensor, the pressure gauge and the first flow sensor; S4: The monitored pressure and flow data are transmitted to the fault diagnosis module, which analyzes and processes the received data, uses the preset diagnosis rules and algorithms, determines the performance status of the tested pump, and finally displays the analysis results on the screen of the PC control terminal, so that the user can intuitively check whether the tested pump has faults and the performance status; Steps for using the online detection experimental platform: S5: Start the motor, open the first stop valve, the second stop valve, and the third stop valve, and the tested pump starts to work, providing pressurized oil to the main oil circuit to start the online detection experimental platform; S6: The PC control terminal outputs a current signal, which accurately controls the opening pressure of the proportional relief valve, simulates various working states of the tested pump, and provides the required working conditions for the online detection experiment; S7: The pressure sensor continuously monitors the pressure of the tested pump and provides important pressure data for fault diagnosis. The first flow sensor continuously monitors the flow of the tested pump and updates the flow data in real time. The temperature sensor measures the working temperature of the tested pump in real time and obtains the temperature information of the tested pump during operation. The vibration sensor is attached to the outer casing of the tested pump to monitor the vibration frequency of the tested pump and reflect the operating status of the tested pump from the vibration aspect. S8: The pressure, flow, temperature, vibration frequency and other data obtained by S7 are transmitted to the fault diagnosis module. The fault diagnosis module conducts a comprehensive analysis of the data from these different sensors based on the preset diagnosis rules and algorithms, and finally accurately displays the comprehensive analysis results on the screen of the PC control terminal, helping users to determine whether the test pump is operating normally, accurately identify various possible fault problems, and provide users with a more comprehensive test pump performance evaluation and fault judgment basis.

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