A threshold conversion test device and method for detecting internal leakage of hydraulic components

Abstract

The present invention belongs to the technical field of internal leakage detection of hydraulic components, and discloses a threshold conversion test device and method for internal leakage detection of hydraulic components, including a test circuit and a tested hydraulic component; the test circuit includes an oil tank, a hydraulic pump, a relief valve, a second stop valve and a pressure sensor, a temperature control module is arranged in the oil tank, one end of the hydraulic pump is connected to the oil tank, and the other end is respectively connected to the relief valve and the second stop valve, and the end of the second stop valve away from the hydraulic pump is connected to the tested hydraulic component; a gas cylinder is connected in the connecting pipeline between the hydraulic pump and the second stop valve, a gas content detector is connected in the connecting pipeline between the gas cylinder and the second stop valve, and a pressure sensor is arranged in the connecting pipeline between the second stop valve and the tested hydraulic component. The threshold conversion technical solution proposed by the present invention can intuitively judge whether the internal leakage test of the tested hydraulic component is qualified, which can greatly save time cost and reduce test error.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydraulic component internal leakage detection, and in particular relates to a threshold conversion test device and method for hydraulic component internal leakage detection. Background Art

[0002] Hydraulic transmission systems are widely used across various manufacturing sectors due to their unique advantages. Key components such as hydraulic cylinders and valves serve as the "lifeblood" of the hydraulic system, and their reliability directly impacts the overall system's performance. Internal leakage is a common fault in hydraulic components, causing a drop in system operating pressure, malfunctioning actuators, and even malfunctioning, leading to downtime and increased maintenance costs. Therefore, detecting internal leakage is particularly important.

[0003] Internal leakage detection is a mandatory part of factory testing for key hydraulic components, such as hydraulic cylinders and valves. According to relevant standards, the measuring cup method is used. This method is cumbersome and inefficient. When the amount of internal leakage is small, the oil adheres to the wall, seriously affecting the accuracy of the measurement results. Data-driven methods primarily utilize various monitoring signals, such as pressure, displacement, vibration, and acoustic emission, to further extract feature quantities. These features are then input into a classifier to identify each leakage fault type. This method offers high detection accuracy but requires a large amount of fault data and complex optimization calculations, making it unsuitable for rapid screening of hydraulic component internal leakage faults. Pressure signals are simple and easy to measure during testing, and even small internal leaks can cause pressure changes. Therefore, using a pressure drop signal to determine the internal leakage compliance of the tested component is feasible. This method is also mentioned and permitted in relevant industry standards, but it does not specify how to convert the standard internal leakage threshold to a pressure drop threshold, and lacks theoretical validation of its effectiveness. Summary of the Invention

[0004] The purpose of the present invention is to provide a threshold conversion test device and method for detecting internal leakage of hydraulic components, so as to solve the problems existing in the above-mentioned prior art.

[0005] On the one hand, to achieve the above-mentioned object, the present invention provides a threshold conversion test device for detecting internal leakage of a hydraulic component, comprising a test circuit and a hydraulic component to be tested;

[0006] The test circuit includes an oil tank, a hydraulic pump, a relief valve, a second stop valve and a pressure sensor. A temperature control module is provided in the oil tank. One end of the hydraulic pump is connected to the oil tank, and the other end is connected to the relief valve and the second stop valve respectively. The end of the second stop valve away from the hydraulic pump is connected to the tested hydraulic component; a gas cylinder is connected to the connecting pipeline between the hydraulic pump and the second stop valve, a gas content detector is connected to the connecting pipeline between the gas cylinder and the second stop valve, and a pressure sensor is provided in the connecting pipeline between the second stop valve and the tested hydraulic component.

[0007] Optionally, a motor is further included, and the hydraulic pump is in transmission connection with the motor.

[0008] Optionally, the hydraulic pump is a plunger pump.

[0009] Optionally, a first stop valve is installed at the gas outlet of the gas cylinder.

[0010] Optionally, a measuring cup is placed below the oil outlet of the tested hydraulic component.

[0011] Optionally, the gas content detector adopts a CGS gas concentration detection system.

[0012] On the other hand, to achieve the above-mentioned purpose, the present invention provides a threshold conversion method for detecting internal leakage of a hydraulic component, which is applied to a threshold conversion test device for detecting internal leakage of a hydraulic component, comprising:

[0013] Step 1: Conduct internal leakage detection on the test circuit;

[0014] Step 2: Setting the test plan under different working conditions, including pressure, temperature and gas content;

[0015] Step 3: Install the tested hydraulic component into the test circuit, perform a pressure holding test based on each of the test schemes, and record the test change curve data corresponding to each of the test schemes, wherein the test change curve data includes pressure-time change curve data and internal leakage volume-time change curve data;

[0016] Step 4: performing rate processing on the test change curve data corresponding to each test scheme to obtain rate curve data, wherein the rate curve data includes pressure drop rate-time change curve data and internal leakage amount-time change curve data;

[0017] Step 5: Combine the pressure drop rate-time variation curve data and the internal leakage amount-time variation curve data and perform polynomial fitting to obtain a pressure drop rate-internal leakage amount polynomial equation;

[0018] Step 6: Substitute the standard internal leakage threshold corresponding to each of the test schemes into the pressure drop rate-internal leakage polynomial equation to obtain the pressure drop threshold corresponding to each of the test schemes.

[0019] Optionally, a pressure holding test is performed, including:

[0020] The temperature control module controls the oil in the tank to reach the preset temperature based on the PID control algorithm;

[0021] The hydraulic pump driven by the motor provides power oil to the test circuit;

[0022] Based on the preset gas content, the first stop valve is opened to allow the gas cylinder to charge the test circuit;

[0023] The pressure in the test circuit is collected in real time through the pressure sensor;

[0024] When the pressure reaches the preset pressure threshold, close the second stop valve, set the test time, and perform the pressure holding test;

[0025] The pressure-time variation curve data of the oil inlet of the tested hydraulic component within the set test time is measured by a pressure sensor, and the internal leakage volume at different times is recorded by a measuring cup. The internal leakage volume-time variation curve data is constructed based on the recorded internal leakage volume.

[0026] The technical effects of the present invention are:

[0027] The present invention designs a test device for detecting pressure changes and internal leakage volumes under different working conditions. It can simultaneously collect real-time data on pressure and internal leakage volume, and can simulate different working conditions through the air content control module and the temperature control module. It can be applied to various types of tested hydraulic components and has strong versatility. Further, the pressure and internal leakage volume data are rate-calculated by the proposed method. By setting a standard internal leakage threshold and performing a conversion calculation, the corresponding mapping relationship between the internal leakage threshold and the pressure drop threshold is identified. The pressure drop threshold under different working conditions is further obtained. The pressure drop threshold can be used to intuitively determine whether the internal leakage test of the tested hydraulic component is qualified, which can greatly save time and cost and reduce experimental errors. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0029] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of this application. The exemplary embodiments and descriptions of this application are intended to explain this application and do not constitute an improper limitation on this application. In the accompanying drawings:

[0030] Figure 1 This is a schematic diagram of a multi-working-condition internal leakage simulation test bench in an embodiment of the present invention;

[0031] Figure 2 Flowchart of the internal leakage threshold-pressure drop threshold conversion steps in an embodiment of the present invention;

[0032] Figure 3 Schematic diagram of the pressure-time and internal leakage volume-time variation curves of the internal leakage simulation test in the embodiment of the present invention; wherein, Figure 3 (a) is a schematic diagram of a pressure-time variation curve in an embodiment of the present invention, Figure 3 (b) is a schematic diagram of the internal leakage volume-time variation curve in an embodiment of the present invention;

[0033] Figure 4 Schematic diagram of the pressure drop rate-time and internal leakage amount-time variation curves of the internal leakage simulation test in the embodiment of the present invention; wherein, Figure 4 (a) is a schematic diagram of the pressure drop rate-time variation curve in an embodiment of the present invention, Figure 4 (b) is a schematic diagram of the internal leakage amount-time variation curve in an embodiment of the present invention;

[0034] Figure 5 Schematic diagram of the internal leakage threshold-pressure drop threshold conversion process in an embodiment of the present invention;

[0035] Explanation of reference numbers: 1. Overflow valve; 2. Hydraulic pump; 3. Motor; 4. First stop valve; 5. Gas cylinder; 6. Gas content detector; 7. Temperature control module; 8. Second stop valve; 9. Pressure sensor; 10. Tested hydraulic component; 11. Measuring cup. DETAILED DESCRIPTION

[0036] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0037] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any intermediate value within a stated value or stated range and any other stated value or intermediate value within the stated range is also encompassed by the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0038] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the present invention. The present description and examples are intended to be illustrative only.

[0039] The words “include,” “including,” “have,” “contain,” etc. used in this article are open-ended terms, meaning including but not limited to.

[0040] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0041] Example 1

[0042] like Figure 1 - Figure 5 As shown, this embodiment provides a threshold conversion test device for detecting internal leakage of a hydraulic component, including a test circuit and a tested hydraulic component 10; the test circuit includes an oil tank, a hydraulic pump 2, a relief valve 1, a second stop valve 8 and a pressure sensor 9, a temperature control module 7 is provided in the oil tank, one end of the hydraulic pump 2 is connected to the oil tank, and the other end is respectively connected to the relief valve 1 and the second stop valve 8, and the end of the second stop valve 8 away from the hydraulic pump 2 is connected to the tested hydraulic component 10; a gas cylinder 5 is connected to the connecting pipeline between the hydraulic pump 2 and the second stop valve 8, a gas content detector 6 is connected to the connecting pipeline between the gas cylinder 5 and the second stop valve 8, and a pressure sensor 9 is provided in the connecting pipeline between the second stop valve 8 and the tested hydraulic component 10.

[0043] On the other hand, a threshold conversion method for detecting internal leakage of a hydraulic component is provided, which is applied to the threshold conversion test device for detecting internal leakage of a hydraulic component, comprising:

[0044] Conduct leak detection on the test circuit;

[0045] Setting test plans under different working conditions, including pressure, temperature and gas content;

[0046] The hydraulic component 10 to be tested is installed in the test circuit, and a pressure holding test is performed based on each of the test schemes, and test change curve data corresponding to each of the test schemes is recorded, wherein the test change curve data includes pressure-time change curve data and internal leakage volume-time change curve data;

[0047] Performing rate processing on the test change curve data corresponding to each of the test schemes to obtain rate-based curve data, wherein the rate-based curve data includes pressure drop rate-time change curve data and internal leakage amount-time change curve data;

[0048] The pressure drop rate-time variation curve data and the internal leakage amount-time variation curve data are combined and polynomially fitted to obtain a pressure drop rate-internal leakage amount polynomial equation;

[0049] The standard internal leakage threshold corresponding to each of the test schemes is substituted into the pressure drop rate-internal leakage polynomial equation to obtain the pressure drop threshold corresponding to each of the test schemes.

[0050] The purpose of this embodiment is to address the shortcomings of the currently commonly used hydraulic component internal leakage detection technology and propose a threshold conversion method and test device for hydraulic component internal leakage detection. This method designs a test device for detecting pressure changes and internal leakage under different working conditions, which can simultaneously collect real-time data of pressure and internal leakage. Furthermore, the proposed method performs rate calculation on the pressure and internal leakage data, and by setting a standard internal leakage threshold and performing conversion calculation, the corresponding mapping relationship between the internal leakage threshold and the pressure drop threshold is identified. The pressure drop threshold under different working conditions is further obtained. This pressure drop threshold can be used to intuitively determine whether the internal leakage test of the tested hydraulic component 10 is qualified, which can greatly save time and cost and reduce test errors.

[0051] like Figure 1 As shown, this embodiment provides a multi-condition internal leakage simulation test bench for a threshold conversion method suitable for detecting internal leakage of hydraulic components, comprising:

[0052] Oil tank, overflow valve 1, hydraulic pump 2, motor 3, first stop valve 4, gas cylinder 5, gas content detector 6, temperature control module 7, second stop valve 8, pressure sensor 9, tested hydraulic component 10, measuring cup 11.

[0053] The oil tank is used to provide the hydraulic oil required for work and also serves as a storage container for return oil;

[0054] A first stop valve 4, one end of which is connected to the oil outlet of the hydraulic pump 2 and the other end of which is connected to the gas cylinder 5, is used to control the gas content in the oil;

[0055] The gas content detector 6 is connected to the main oil circuit through a pipeline connector and is used to measure the gas content in the oil.

[0056] The temperature control module 7 is connected to the oil tank outlet through a pipe connector, wherein a temperature sensor is arranged in the oil tank for measuring the temperature of the oil.

[0057] A second stop valve 8, one end of which forms a passage with the main oil circuit and the other end is connected to a pressure sensor 9;

[0058] A pressure sensor 9 is installed in the circuit formed by the oil outlet of the second stop valve 8 and the oil inlet of the tested hydraulic component 10, and is used to detect the pressure of the tested hydraulic component 10 during the test;

[0059] One end of the hydraulic pump 2 is connected to the oil tank, and the other end is coaxially connected to the motor 3. The oil inlets of the second stop valve 8 and the first stop valve 4 are connected to the oil outlet of the hydraulic pump 2. At the same time, the oil outlet of the hydraulic pump 2 is connected to the relief valve 1. The inlet of the first stop valve 4 is connected to the outlet of the gas cylinder 5. The gas content detector 6 is connected to the passage formed by the hydraulic pump 2 and the second stop valve 8 through a pipe joint. The temperature control module 7 is connected to the oil tank. The temperature control module 7 may specifically include a high-precision temperature sensor, a controller, and a heat sink. The temperature sensor is set in the oil tank. The pressure sensor 9 is set in the passage formed by the oil outlet of the second stop valve 8 and the oil inlet of the tested hydraulic element 10. A measuring cup 11 is placed below the oil outlet of the tested hydraulic element 10.

[0060] In this specific embodiment, the hydraulic pump 2 may preferably be a plunger pump, the motor 3 may be a servo motor 3, the gas content detector 6 may preferably be a CGS gas concentration detection system, and the controller in the temperature control module 7 may adopt PID control.

[0061] PID control uses the control deviation between the supplied oil temperature and the actual oil temperature to form a control variable through a linear combination of proportional, integral, and differential functions to control the oil temperature. Proportional control is responsive and can respond immediately to deviations, but using it alone can lead to steady-state errors in the system. Integral control can eliminate steady-state errors and improve accuracy. When the temperature approaches the setpoint, differential control adjusts the control variable based on the rate of temperature change. If the temperature rises too quickly, differential control generates a negative control variable to reduce the power of the heating equipment, preventing the temperature from rising excessively and exceeding the setpoint.

[0062] The hydraulic pump 2 is driven by the motor 3 to provide power oil to the hydraulic component 10 under test when performing the test items.

[0063] When the first stop valve 4 is in an open state, the gas cylinder 5 can inflate the test circuit to change the gas content in the hydraulic oil. When the first stop valve 4 is closed, the gas source is cut off.

[0064] In the temperature control module 7, the temperature sensor is used to monitor the temperature of the hydraulic oil in real time. When the temperature is lower than the target temperature, the oil is heated by the heater. When the temperature is higher than the target temperature, the radiator is activated to lower the oil temperature. The heat dissipation method can be air convection heat dissipation.

[0065] When the main oil circuit reaches the specified test pressure, the second stop valve 8 closes the main oil circuit to achieve the pressure-maintaining test process for the tested hydraulic component 10 .

[0066] The measuring cup 11 is used to collect the oil generated by the leakage in the tested hydraulic component 10 .

[0067] The threshold conversion method for detecting internal leakage of hydraulic components is shown in the flowchart of the conversion steps. Figure 2 As shown, the specific steps include:

[0068] Step 1: In order to eliminate the interference of internal leakage of other components in the system, it is necessary to conduct a visual inspection before conducting the hydraulic cylinder internal leakage test to eliminate external and internal leakage at each component and pipe joint. The internal leakage simulation test can be carried out only if there is no obvious external or internal leakage after inspection.

[0069] Step 2: Determine the test plan and set the test levels for different working conditions (pressure, temperature and gas content).

[0070] Step 3: Install the tested hydraulic component 10 into the test circuit, pressurize the test circuit to the predetermined test pressure level in turn, and start the pressure holding test. The pressure holding test lasts for T. The internal leakage volume data corresponding to the pressure change at time T is measured and recorded using the oil drop method. Specifically, the pressure change curve of the working chamber at time T is measured by the pressure sensor 9, and the internal leakage volume at different times is recorded using the measuring cup 11. For the collected data, the data points of the internal leakage volume are relatively sparse, so the polynomial fitting and interpolation methods are used to expand the data points. After expansion, the internal leakage volume-time change curve is constructed. The pressure-time and internal leakage volume-time change curves are shown as follows: Figure 3 shown.

[0071] Step 4: Change different working conditions (pressure, temperature, gas content, etc.) and repeat the test multiple times.

[0072] Step 5: After all the tests are completed, data processing is performed to convert the pressure-time and internal leakage volume-time change curves into rate curves, as shown below: Figure 4 The pressure drop rate-time and internal leakage volume-time curves are shown. To address the data heterogeneity problem faced by high-frequency pressure data and low-frequency internal leakage volume data, a polynomial fitting and interpolation method is used to increase the frequency of the internal leakage volume data.

[0073] Step 6: Figure 4 The combination of the pressure drop rate and the internal leakage amount gives the following Figure 5The pressure drop rate-internal leakage rate relationship curve shown in the figure is fitted to obtain a polynomial equation of pressure drop rate-internal leakage. Substituting the internal leakage threshold value determined by the relevant standards into the above pressure drop rate-internal leakage rate equation, the pressure drop threshold value under the corresponding working condition can be obtained, as shown in Table 1, which can be used intuitively to judge whether the internal leakage test under different working conditions is qualified.

[0074] Table 1 Pressure drop thresholds under different working conditions

[0075]

[0076]

[0077] The multi-condition internal leakage simulation test bench proposed in this embodiment can simultaneously measure the pressure and internal leakage volume of a tested hydraulic component during a pressure-maintaining test, improving test efficiency and accuracy. Furthermore, the gas content control module and temperature control module enable simulation of different operating conditions. The conversion method and test bench described in this embodiment can determine pressure drop thresholds under all operating conditions, making it applicable to various types of tested hydraulic components and demonstrating high versatility.

[0078] The internal leakage-to-pressure drop threshold conversion method described in this embodiment is not only applicable to internal leakage-to-pressure drop threshold conversion, but can also be applied to other difficult-to-measure key parameter conversion processes. It is simple, intuitive, and highly practical. Furthermore, this method can be extended to the internal leakage detection process of other liquid media components, enriching and developing internal leakage detection methods for hydraulic / hydraulic components and equipment, improving the reliability and intelligent operation and maintenance capabilities of hydraulic / hydraulic components and equipment.

[0079] This embodiment addresses the heterogeneous problem of mismatched time series between high-frequency pressure data and low-frequency internal leakage volume data, and proposes a polynomial fitting and interpolation method to compensate for the sparseness of internal leakage volume data and improve the accuracy of the test.

[0080] The above description is merely a preferred embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A threshold conversion test device for detecting internal leakage of hydraulic components, characterized in that: It includes a test circuit and a hydraulic component to be tested (10); The test circuit comprises an oil tank, a hydraulic pump (2), a relief valve (1), a second stop valve (8) and a pressure sensor (9); a temperature control module (7) is arranged in the oil tank; one end of the hydraulic pump (2) is connected to the oil tank, and the other end is respectively connected to the relief valve (1) and the second stop valve (8); the end of the second stop valve (8) away from the hydraulic pump (2) is connected to the tested hydraulic element (10); a gas cylinder (5) is connected to the connecting pipeline between the hydraulic pump (2) and the second stop valve (8); a gas content detector (6) is connected to the connecting pipeline between the gas cylinder (5) and the second stop valve (8); and a pressure sensor (9) is arranged in the connecting pipeline between the second stop valve (8) and the tested hydraulic element (10).

2. A threshold conversion test device for detecting internal leakage of hydraulic components according to claim 1, characterized in that: It also comprises a motor (3), and the hydraulic pump (2) is drivingly connected to the motor (3).

3. A threshold conversion test device for detecting internal leakage of hydraulic components according to claim 1, characterized in that: The hydraulic pump (2) is a plunger pump.

4. A threshold conversion test device for detecting internal leakage of hydraulic components according to claim 1, characterized in that: A first stop valve (4) is installed at the gas outlet of the gas cylinder (5).

5. A threshold conversion test device for detecting internal leakage of hydraulic components according to claim 1, characterized in that: A measuring cup (11) is placed below the oil outlet of the tested hydraulic element (10).

6. A threshold conversion test device for detecting internal leakage of hydraulic components according to claim 1, characterized in that: The gas content detector (6) adopts a CGS gas concentration content detection system.

7. A threshold conversion method for detecting internal leakage of a hydraulic component, applied to a threshold conversion test device for detecting internal leakage of a hydraulic component as claimed in any one of claims 1 to 6, characterized in that: include: Step 1: Conduct internal leakage detection on the test circuit; Step 2: setting the test scheme under different working conditions, wherein the working conditions include pressure, temperature and gas content; Step 3: installing the tested hydraulic element (10) into the test circuit, performing a pressure holding test based on each of the test schemes, and recording test change curve data corresponding to each of the test schemes, wherein the test change curve data includes pressure-time change curve data and internal leakage volume-time change curve data; Step 4: performing rate processing on the test change curve data corresponding to each of the test schemes to obtain rate curve data, wherein the rate curve data includes pressure drop rate-time change curve data and internal leakage amount-time change curve data; Step 5: Combining the pressure drop rate-time change curve data and the internal leakage amount-time change curve data and performing polynomial fitting to obtain a pressure drop rate-internal leakage amount polynomial equation; Step 6: Substitute the standard internal leakage threshold corresponding to each of the test schemes into the pressure drop rate-internal leakage polynomial equation to obtain the pressure drop threshold corresponding to each of the test schemes.

8. A threshold conversion method for detecting internal leakage of hydraulic components according to claim 7, characterized in that: Carry out pressure holding test, including: The temperature control module (7) controls the oil in the oil tank to reach a preset temperature based on a PID control algorithm; The hydraulic pump (2) is driven by the motor (3) to supply power oil to the test circuit; Based on the preset gas content, the first stop valve (4) is opened to allow the gas cylinder (5) to inflate the test circuit; The pressure in the test circuit is collected in real time by means of a pressure sensor (9); When the pressure reaches a preset pressure threshold, the second stop valve (8) is closed, the test time is set, and a pressure holding test is performed; The pressure-time variation curve data of the oil inlet of the tested hydraulic element (10) within the set test time is measured by a pressure sensor (9), and the internal leakage volume at different times is recorded by a measuring cup (11), and the internal leakage volume-time variation curve data is constructed based on the recorded internal leakage volume.

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